INDUCTIVE DISPLACEMENT SENSORS

专利摘要:
The invention relates to a target (401) for an inductive displacement sensor, said target being formed of a single conductive metal part machined so that a face of the target intended to be turned towards a transducer of an inductive displacement sensor comprises one or more metal studs (407i) projecting from a wall (309) of said piece.
公开号:FR3031589A1
申请号:FR1550232
申请日:2015-01-13
公开日:2016-07-15
发明作者:Yohan Maniouloux；Gor Lebedev
申请人:DYMEO；
IPC主号:

专利说明:

[0001] The present application relates to the field of inductive measurement of movement of a mechanical part relative to another. By inductive measurement is meant here the measurement of alternating electromagnetic fields, by means of electric windings. More particularly, but not exclusively, the present application relates to the technical subdomain of eddy current sensors, in which an electromagnetic field generated by an inductor is established in a different manner depending on the presence and arrangement of moving conductive parts (relative to to the inductor) near the inductor. Such electromagnetic phenomena become exploitable for instrumentation purposes when certain electric frequencies of the electromagnetic field take sufficiently large values, this notion of importance being conditioned by several parameters such as the geometrical dimensions of the conductive parts, their electrical and magnetic properties, their temperature, etc. Displacement measurement here means the estimation of information relating to the position, the speed, the acceleration or any other quantity characteristic of the displacements of the conductive part relative to the inductor or to the reference frame of the inductor. By displacements, one considers at 3031589 B13316 2 both the angular displacements (rotation about an axis), linear (translation along an axis), or any combination of such displacements between them or along disjoint axes. More particularly, but not exclusively, the present application relates to the technical subdomains of inductive position sensors, inductive speed sensors and / or inductive acceleration sensors. DISCUSSION OF THE PRIOR ART An inductive displacement sensor typically comprises a transducer (for example integral with a measurement reference frame, also called a frame), and a target (for example, integral with a moving mechanical part with respect to the reference frame). measured). The target is placed away from the transducer, and is not in contact (mechanically or electrically) with the transducer 15 (non-contact measurement). The transducer comprises a primary winding, or inductor, adapted to produce an alternating electromagnetic field, and at least one secondary winding across which is induced an alternating voltage, also called electromotive force or EEM, in the presence of the electromagnetic field produced by the primary winding. The target is a partially or totally conductive element, also called a coupling armature, whose presence and / or displacement in front of the transducer modifies the coupling between the primary winding and the secondary winding. Note that the effect of the target on the coupling between the primary winding and the secondary winding depends on the position of the target relative to the transducer, but also on its speed relative to the transducer. The electromagnetic field distribution is thus shaped spatially according to the position and the relative displacement of the target with respect to the transducer. During a displacement of the mechanical part, the spatial distribution of the electromagnetic field evolves, and thus the EEM induced in the secondary winding evolves as well. The analysis of the EMF induced at the terminals of the secondary winding by the electromagnetic field produced by the primary winding makes it possible to estimate the position and / or the displacement of the target with respect to the winding. secondary of the transducer. More particularly, but not exclusively, the temporal variations in the amplitude of the EMF at the terminals of the secondary winding make it possible to estimate the position, the speed and / or the acceleration of the target with respect to the transducer. It is specified that here and in the remainder of the present application, by amplitude of the envelope of the electromotive force 10 at the terminals of the secondary winding, reference is made to the instantaneous value taken by a signal of limited frequency content, for example in a frequency band between -Af and + Af around the excitation frequency (that is to say the frequency of the AC voltage applied across the terminals of the primary winding), with Af being able for example take a value between 100Hz and 100kHz, carrier of the information or part of the information characteristic of mechanical displacement. This signal is contained in the electromotive force, modulated at the excitation frequency and / or its harmonics. It can be obtained by a method of frequency translation and filtering, and more specifically by a baseband transposition and filtering. A preferred example of such a method is to perform a synchronous demodulation of the electromotive force (modulated) by a synchronous signal of the excitation frequency, and whose electrical phase has been chosen to meet particular criteria, for example to maximize the signal obtained at the demodulation output. An alternative method consists in calculating the signal module after synchronous demodulation, which has the advantage and the disadvantage of not fixing an electrical phase of demodulation. It is also specified that the amplitude of the electromotive force is a preferred measurement variable for the implementation of a measurement of displacement with the sensors of the invention, but that it is by no means exclusive of other electrical quantities of measurement such as the phase, the frequency, or the electrical power at the secondary when a finite load is connected to the terminals of the secondary winding (load adaptation). Examples of displacement inductive sensors, and more particularly of eddy current position sensors, have been described in patent EP0182085. Inductive displacement sensors known, however, have various disadvantages. In particular, the known sensors are relatively sensitive to inaccuracies in mounting (decentering, inclination and / or target distance / transducer), as well as to the presence of conductive parts in the vicinity of the measurement zone, which poses a problem for a industrial exploitation. Problems related to the lack of linearity of the sensor response may also arise. In addition, the accuracy and robustness of the position and / or displacement estimation of the target in the known sensors would need to be improved. In addition, it would be desirable to be able to increase the range of the measurement range of certain types of known sensors. Furthermore, a disadvantage of known sensors is that they are relatively fragile, which is problematic in certain types of application, particularly in industrial environments. It would be desirable to have inductive displacement sensors that overcome all or some of the disadvantages of known sensors.
[0002] SUMMARY Thus, an embodiment provides a target for an inductive displacement sensor, which target is formed of a single conductive metal part machined so that a face of the target intended to be turned towards a transducer of a sensor. inductive displacement comprises one or more metal studs projecting from a wall of said part. According to one embodiment, the entire surface of the target intended to be turned towards the transducer is metallic. According to one embodiment, the target comprises several pads of substantially the same height.
[0003] According to one embodiment, the height of the pad or pads is between 0.1 and 30 mm. According to one embodiment, each stud has an upper face parallel to the wall.
[0004] According to one embodiment, the wall is approximately flat. According to one embodiment, the piece has the general shape of a disc, and comprises a plurality of studs distributed along a circular annular band on the side of a face of the disc.
[0005] According to one embodiment, the piece has the general shape of a rectangular plate, and comprises a plurality of studs distributed along a rectangular band on the side of a face of the plate. According to one embodiment, the metal part is a part of a motor shaft or transmission shaft of a speed reduction gearbox. According to one embodiment, the metal part is a part of a motor vehicle steering column. According to one embodiment, the metal part is a part of a piston rod. According to one embodiment, the metal part is secured to a ring of a ball bearing. BRIEF DESCRIPTION OF THE DRAWINGS These and other features and advantages will be set forth in detail in the following description of particular embodiments in a non-limiting manner with reference to the accompanying figures in which: FIGS. 1A and 1B are respectively a front view and a side view schematically showing an example of an inductive angular displacement sensor; Figure 2 is a diagram schematically illustrating the operation of the sensor of Figure 1; Figs. 3A and 3B are front views schematically showing a transducer and a target of another example of an inductive angular displacement sensor; Figure 4 is a diagram schematically illustrating the operation of the sensor of Figures 3A and 3B; Fig. 5 is a front view schematically showing a transducer of another example of an inductive sensor 5 of angular displacement; Figure 6 is a diagram schematically illustrating the operation of the sensor of Figure 5; Fig. 7 is a front view schematically showing a transducer of another example of an inductive sensor 10 of angular displacement; Fig. 8 is a diagram schematically illustrating the operation of the sensor of Fig. 7; Fig. 9A is a diagram showing the expected theoretical evolution of output signals from an inductive angular displacement sensor; FIG. 9B is a diagram showing the real evolution, typically obtained in practice, of the output signals of an inductive angular displacement sensor; Fig. 10 is a diagram showing, for a plurality of different target-transducer distances, the evolution of an output signal of an inductive angular displacement sensor; Fig. 11 is a diagram showing the evolution, as a function of the target-transducer distance, of the linearity error of an output signal of an inductive angular displacement sensor; Figs. 12A-12D are sectional views schematically illustrating four exemplary embodiments of an inductive angular displacement sensor; FIG. 13A is a diagram showing, for the four sensor examples of FIGS. 12A-12D, the evolution, as a function of the target-transducer distance, of the linearity error of an output signal of the sensor; Fig. 13B is a diagram showing the evolution of the optimal target-transducer distance in terms of linearity as a function of a parameter of an example of an inductive displacement sensor; Fig. 13C is a diagram showing the evolution of the optimal target-transducer distance in terms of linearity as a function of a parameter of another example of an inductive displacement sensor; FIG. 14 is a front view showing an example of a field confinement part of an exemplary embodiment of an inductive angular displacement sensor; FIG. 15 is a front view showing another example of a field confinement piece of an exemplary embodiment of an inductive angular displacement sensor; Figs. 16A and 16B are front views schematically showing two exemplary embodiments of a target of an inductive angular displacement sensor; Fig. 17 is a diagram showing the evolution, in an inductive angular displacement sensor, of the optimal target-transducer distance in terms of linearity, as a function of a shape parameter of a target pattern; Fig. 18A is a front view schematically and partially showing three exemplary embodiments of a target of an inductive angular displacement sensor; Fig. 18B is a front view schematically and partially showing an exemplary embodiment of a secondary winding of a transducer adapted to operate in cooperation with the targets of Fig. 18A; Fig. 19 is a diagram showing the evolution, in an inductive angular displacement sensor, of the optimal target-transducer distance in terms of linearity, as a function of another shape parameter of a target pattern; Fig. 20A is a front view schematically showing an example of a transducer of an inductive angular displacement sensor; Figure 20B is a front view schematically showing an example of a transducer of an inductive linear displacement sensor; Fig. 20C is a front view schematically showing an example of an embodiment of a transducer of an inductive angular displacement sensor; Fig. 20D is a front view schematically showing an example of an embodiment of a transducer of an inductive linear displacement sensor; Figure 20E is a small electrical representation of the behavior of the transducer of Figure 20D; Figs. 21A and 21B are front views schematically showing an exemplary embodiment of a transducer of an inductive angular displacement sensor; Figs. 22A and 22B are front views schematically showing another exemplary embodiment of a transducer of an inductive angular displacement sensor; Fig. 23 is a front view schematically showing a target of an exemplary angular displacement inductive sensor; Fig. 24 is a diagram schematically showing the evolution of measurement signals of the sensor of Fig. 23; Fig. 25 is a front view schematically showing a target of an exemplary embodiment of an inductive angular displacement sensor; Fig. 26 is a front view schematically showing a target of an alternative embodiment of an inductive angular displacement sensor; Figs. 27A-27C are front views schematically showing another alternative embodiment of an inductive angular displacement sensor; Fig. 28 is a perspective view showing an exemplary embodiment of a target for an inductive angular displacement sensor; and Fig. 29 is a perspective view showing another embodiment of a target for an inductive angular displacement sensor. DETAILED DESCRIPTION For the sake of clarity, the same elements have been designated with the same references in the various figures and, in addition, the various figures are not drawn to scale. Furthermore, in the remainder of the description, unless otherwise indicated, the terms "approximately", "substantially", "about", "of the order of", "almost", etc., mean "to within 20% and preferably to within 5% ", or" within 5 degrees and preferably to 2 ° "when referring to angular distances, and directional references such as" vertical "," horizontal "," lateral " , "below", "above", "upper", "lower", etc., apply to devices oriented in the manner illustrated in the corresponding views, it being understood that, in practice, such devices can be oriented differently. Of particular interest here are angular displacement sensors, and more specifically angular displacement sensors of approximately planar general shape, for example, sensors having a generally disk-like shape, or, more generally, sensors having a generally planar shape. circular annular band shape of angular opening less than or equal to 360 °. However, it will be understood from the following that all the exemplary embodiments, embodiments and variants described in the present application can be adapted to other types of inductive displacement sensors, for example inductive sensors of the present invention. linear displacement of the type described in the patent EP0182085 mentioned above. The adaptation of the examples and embodiments described in the present application to other types of inductive displacement sensors is within the abilities of those skilled in the art and will therefore not be detailed hereinafter. By way of illustrative but nonlimiting example, the inductive sensors described in the present application and illustrated in the figures have characteristic dimensions (diameter for the angular sensors and width for the linear sensors) of between 5 mm and 200 mm. mm, and preferably between 40 mm and 50 mm.
[0006] Figs. 1A and 1B are respectively a front view and a side view schematically showing an example of a planar-type angular position inductive sensor 100 having a generally disk-like shape. The sensor 100 comprises a transducer 110 having a primary conductive winding 101 and a secondary conductive winding 103. In Fig. 1B, the primary and secondary windings of the transducer 110 have not been detailed. Preferably, the primary winding 101 comprises two roughly circular, concentric and coplanar, turns or loops 101a and 101b of opposite winding directions and radii. Each turn 101a, 101b of the primary winding 101 comprises at least one turn, and preferably several turns. The turns 101a and 101b are preferably connected in series so as to be traversed by currents of the same intensity but in opposite directions of flow, but may optionally be connected in parallel so as to see the same voltage at their terminals (applied from preferably so that the flow directions of the current in the two turns are opposite). An advantage of the exemplary primary winding arrangement of FIG. 1 is that it produces a substantially uniform excitation field in the annular band between the two turns, and substantially zero outside this band. . Alternatively, the primary winding 101 may comprise a single turn (at one or more turns). More generally, the primary winding 101 may comprise one or more concentric turns (at one or more turns each) arranged to generate an electromagnetic field in the measurement zone of the transducer. The described embodiments are not limited to these particular arrangements of the primary winding.
[0007] In the example shown, the secondary winding 103 consists of a coil or conductive loop disposed in the circular annular band-shaped space between the turns 101a and 101b. The winding 103 is for example located approximately in the same plane as the turns 101a and 101b, or in a substantially parallel plane. In this example, in front view, the turn 103 substantially follows the contour of an angular sector of angular aperture a of the annular band delimited by the turns 101a 10 and 101b. The turn 103 comprises in particular radial portions and ortho-radial portions of the contour of the annular band portion. Such a winding allows an angular position measurement over a range of a °. In the example shown, the angular aperture of turn 103 is approximately equal to 30 °. The described embodiments are however not limited to this particular case. As a variant, the angle α can take any value between 0 and 180 °. The turn 103 preferably comprises a single turn but may optionally include several turns. The primary windings 101 and secondary windings 103 are for example arranged in and on the same dielectric support (not shown) in the form of a plate of a few hundred micrometers to a few millimeters in thickness, for example a circuit board support of the type PCB (from the English "Printed Circuit Board").
[0008] The sensor 100 further comprises a target 111 comprising a conductive pattern 107, located at a non-zero distance from the transducer and adapted to move relative to the transducer. In Figure 1A, only the conductive portion 107 of the target has been shown. In this example, the conductive pattern 107 of the target 111 has substantially the same shape as the annular band portion delimited by the pattern of the turn 103 of the transducer. The target is rotatably mounted about an axis Z orthogonal to the plane of the transducer passing through the center of the turns 101a and 101b, so that when the target rotates by an angle 2a around the axis Z, the conductive pattern (angular aperture a), covers approximately integrally and then discovers approximately integrally the surface of the annular band delimited by the turn of the secondary winding 103 of the transducer. By way of non-limiting example, the target may consist of a plate made of a dielectric material, for example in the form of a disc, of which a face turned towards the transducer is partially coated with a layer of a conductive, magnetic material or not, for example a metal layer, for example a layer of iron, steel, aluminum, copper, etc., forming the conductive pattern 107. Alternatively, the target may consist solely of a metal plate portion cut to the shape of the conductive pattern 107, mounted by any means adapted to be rotatable relative to the transducer above the annular band portion delimited by the turns 101a and 101b. The operation of the sensor 100 of FIGS. 1A and 1B will now be described in relation with FIG. 2 which represents the evolution of the amplitude of the electromotive force 20 V across the secondary winding 103 of the sensor as a function of the position. angular 0 of the target 111 relative to the transducer 110. In operation, the circulation of an alternating current Ip in the primary winding 101 is applied by electrical means. The flow of the current Ip in the winding 101 produces a field electromagnetic B having, in the absence of a target, a substantially symmetrical distribution per revolution in the circular annular band traversed by the secondary winding 103. By way of non-limiting example, the frequency of the alternating current of excitation Ip imposed in the primary winding is between 500 kHz and 50 MHz (for example 4 MHz). The amplitude of the current Ip is for example between 0.1 mA and 100 mA (for example 2 n0). In the absence of a target 111, or, more generally, when the conductive pattern 107 of the target does not cover the secondary winding 103, the secondary winding 103 provides between its ends an alternating VF frequency VF. substantially equal to the excitation frequency of the primary winding, and amplitude a priori non-zero. When the conductive pattern 107 of the target 111 covers all or part of the secondary winding 103, the spatial distribution of the electromagnetic field in the vicinity of the turn 103 changes according to the arrangement and displacement of the surface portion of the conductive pattern 107 is opposite to the turn 103. Another formulation consists in considering that under the effect of the magnetic excitation generated by the circulation of the current Ip in the primary winding, eddy currents appear in the conductive pattern 107, causing a modification of the spatial distribution of the electromagnetic field according to the disposition and displacement of the surface portion of the pattern 107 located opposite the turn 103. These changes or variations in the spatial distribution of the electromagnetic field depending on the arrangement and of the displacement of the surface portion of the pattern 107 situated opposite the turn 103, translate, by way of duction, by variations or evolutions of the amplitude V of the envelope of the voltage across the secondary winding, a function of the arrangement and the displacement of the surface portion of the pattern 107 situated opposite the turn 103 As a nonlimiting illustrative example, the target can be rotated about the Z axis with respect to the transducer in a range of angular positions from 0 ° to 0 °. It is arbitrarily considered that the position 0-a ° corresponds to the arrangement shown in FIG. 1A, in which the conductive pattern 107 does not mask the turn 103, but has, seen from above, a radial edge attached to a radial edge of the turn 103. Thus, for the angular positions 0 ranging from -a ° to 0 °, the surface of the portion of the conductive pattern 107 located opposite the turn 103 increases as the angular position 0 increases, then, for the angular positions 0 ranging from 0 ° to a °, the surface of the portion of the conductive pattern 107 opposite the turn 103 35 decreases as the angular position 0 increases. Outside the range of angular positions ranging from 0 = -a ° to 0 = e, the area of the portion of the conductive pattern 107 facing the turn of the secondary winding 103 is zero, and the position and or the displacement of the target 111 relative to the transducer can not be measured. The amplitude V of the envelope of the voltage measured at the terminals of a secondary winding of an inductive displacement sensor is theoretically proportional to the area of the surface portion of the conductive pattern of the target situated opposite the secondary winding. Thus, as shown in FIG. 2, for the angular positions 0 ranging from -a ° to 0 °, the signal V decreases as the angular position 0 increases from a high value Vmax for 0 = -a ° to a low value Vmin for 0 = 0 °, and for the angular positions 0 ranging from 0 ° to a °, the signal V increases as the angular position 0 increases, from the low value Vmin for 0 = 0 ° to the high value Vmax for 0 = this. The signal V is therefore theoretically a triangular signal varying linearly between Vmin and Vmax over the angular range from -a ° to a °. As will be seen below, in practice, the signal V has zones of nonlinearity and consequently has a sinusoidal shape. Thus, in the range of angular positions ranging from 0 = -a ° to 0 = 0 °, or in the range of angular positions ranging from 0 = 0 ° to 0 = e, the measurement of the amplitude V of the envelope of the electromotive force across the secondary winding 103 determines the angular position 0 of the target relative to the transducer. Although the value of the signal V varies as a function of the angular position 0 of the target in the two aforementioned angular position ranges, the measurement of the signal V does not make it possible to discriminate the position values of the range from -a ° at 0 ° position values in the range from 0 ° to a ° (non-surjective measurement). The extent of the range of angular positions that can effectively be measured by the sensor 100 is therefore approximately equal to a °, provided that the angle α does not exceed 180 °.
[0009] FIGS. 3A and 3B are front views schematically showing another example of an angular position inductive sensor having a general disk shape. This sensor comprises a transducer 112 shown in FIG. 3A and a target 114 shown in FIG. 3B. The target 114 of FIG. 3B differs from the target 111 of FIG. 1A mainly by its conductive pattern. In particular, the target 114 of FIG. 3B differs from the target 111 of FIG. 1A in that it no longer comprises a single conductive pattern 107, but a set of N conductive patterns 117i integral with the target, and adapted to move relative to the transducer, where N is an integer greater than or equal to 2 and i is an integer from 1 to N. The transducer 112 of Fig. 3A differs from the transducer 110 of Fig. 1A primarily in the form of its secondary winding. 113. In particular, the secondary winding 113 of the transducer 112 of FIG. 3A no longer includes a single conductive turn, but a set of N turns 113i. The target 114 of FIG. 3B is intended to be rotatably mounted relative to the transducer 112 of FIG. 3A, in a manner similar or identical to that described with reference to FIGS. 1A and 1B. In this example, in front view, the set of conductive patterns 117i and the set of turns 113i, consist of the repetition by revolution of N substantially identical patterns, respectively 117i and 113i. The repetition by revolution of these patterns is carried out with a spatial periodicity of 2a, that is to say that each angular aperture pattern substantially equal to a ° is spaced from its nearest neighbor by a circular annular band portion. void of ortho-radial extent substantially equal to a °.
[0010] For sensors whose general shape is a closed circular annular band, that is to say of angular aperture equal to 360 °, the value of the opening angle has patterns is chosen preferably such that a = 360 ° / 2N, to guarantee an integer number of pattern repetitions per revolution (over 360 °). In the example of FIGS. 3A and 3B, N = 6 and a = 30 °.
[0011] In other words, the transducer of FIG. 3A comprises a secondary winding 113 comprising N loops or turns 113i in series. Each turn 113i has a circular annular band sector shape, of the same type as the turn 103 of FIG. 1A, and has an angular dimension approximately equal to = 360 ° / 2N (i.e., a = 30 ° in this example). The N turns 113i are regularly distributed along the 360 ° of the circular annular band approximately delimited by the turns 101a and 101b of the primary winding 101, that is to say that two consecutive turns 113i of the secondary winding are separated by an annular band portion of angle approximately equal to a. The target of FIG. 3B comprises N conductive patterns 117i. Each pattern 117i has an annular band sector shape, of the same type as the conductive pattern 107 of FIG. 1, and an angular dimension approximately equal to = 360 ° / 2N. The N conductive patterns 117i are regularly distributed along an annular band of the target intended to be positioned facing the annular band of the transducer containing the turns 113i.
[0012] In the remainder of the present application, the multipole sensor will refer to the sensors of the type described in relation with FIGS. 3A and 3B, N denoting the number of pairs of poles of the sensor. In the example of FIG. 1A, if a takes the value 180 °, it is called a pair of poles. More particularly, a multipole sensor will be defined as a sensor in which an elementary conductive pattern is regularly repeated at least twice on the target in a direction parallel to a degree of freedom of movement of the target relative to the transducer (ie that is to say in an orthoradial direction in an angular sensor of the type described above). By analogy with the electrical period of a multipole-pair electric motor, reference will now be made to the angular aperture between two adjacent patterns 117i, and to the angular aperture between two adjacent patterns 113i, 35 as the electrical period. of the sensor. In the particular case of the sensor of FIGS. 3A and 3B, for which the conductive patterns are of angular aperture a ° and the empty spaces between these patterns are also of angular aperture a °, the electric period is equal to 2 °. °, and, conversely, the angular aperture of a conductive pattern is worth a half-electric period of sensor, which is a privileged but not exclusive case. By construction, for the sensors whose general shape is a closed circular annular band, an electric period is preferably a sub-multiple of 360 °, since 10 a = 360 ° / 2N. In these terms, an inductive multipole sensor has a measurement range of a °, equal to half of its electrical period of 2a °. In the example of FIG. 1A, if a is 180 °, the electrical period is 360 °, and the measurement range is approximately half the electrical period, 180 °. In the example of FIGS. 3A and 3B for which a = 30 °, the electrical period is 2a = 60 °, and the measuring range is approximately equal to half the electrical period, ie a = 30 °. FIG. 4 is a diagram showing the evolution of the amplitude V of the envelope of the electromotive force across the secondary winding 113 of the sensor of FIGS. 3A and 3B as a function of the angular position 0 of the target by relative to the transducer. As shown in FIG. 4, when the angular position 0 of the target relative to the transducer varies from 0 ° to 360 °, the signal V varies periodically between a high value Vmax and a low value Vmin, with a period angular variation approximately equal to the electric period 2a of the sensor.
[0013] The amplitude of the range of angular positions 0 which can be measured by the sensor of FIGS. 3A and 3B is approximately equal to half the electrical period, ie a. An advantage of the sensor of FIGS. 3A and 3B with respect to the sensor of FIGS. 1A and 1B is that the larger number of patterns distributed over the target and on the transducer allows distributed measurement over an extended measurement area, in wherein each pattern contributes locally and constructively to the generation of a global electromotive force, said electromotive force being more immune to positioning errors of the target relative to the transducer than in the sensor of Figs. LA and 1B, wherein the realized measurement is a local measurement performed using a single set of patterns 107-103. This robustness of the measurement is all the more important as the number 10 N of pairs of poles of the sensor is high. FIG. 5 illustrates an alternative embodiment of the sensor of FIGS. 3A and 3B. In FIG. 5, only the transducer of the sensor has been shown, the target being identical to that of FIG. 3B.
[0014] The transducer of the sensor of FIG. 5 comprises the same elements as the transducer of FIG. 3A, and further comprises a second secondary winding 113 'comprising N loops or turns 113i' in series. For the sake of clarity, the connections between the different loops 113i of the winding 113 and the connections between the different loops 113i 'of the winding 113' have not been shown in FIG. 5. The secondary winding 113 ' (shown in broken lines) is substantially identical to the secondary winding 113 (shown in solid lines), and is disposed in the same annular band of the transducer as the secondary winding 113, with an angular offset corresponding to a quarter of the electrical period of the sensor, ie approximately equal to a / 2, relative to the secondary winding 113. FIG. 6 is a diagram showing the evolution of the amplitude V (solid line) of the envelope of the electromotive force at the terminals of the secondary winding 113 of the sensor of FIG. 5, and the evolution of the amplitude V '(in broken lines) of the envelope of the electromotive force at the terminals of the secondary winding. 113 of the sensor of FIG. 5, as a function of the angular position 0 of the target with respect to the transducer. As shown in FIG. 6, when the angular position 0 of the target with respect to the transducer varies from 0 ° to 360 °, the signals V and V 'vary periodically between a high value Vmax and a low value Vmin, with a period of variation equal to the electrical period of the sensor, that is to say approximately equal to 2a ° in this example, and with an angular offset with respect to each other substantially equal to a quarter of the electrical period of the sensor, that is to say approximately a / 2 ° in this example. An advantage of the transducer of FIG. 5 with respect to the transducer of FIG. 3A is that it extends the range of angular positions 0 that can be measured by the sensor to approximately an entire electrical period (ie ie 2a °), instead of half a period (i.e., a °) in the example of Figures 3A and 3B. FIG. 7 illustrates another variant embodiment of the sensor of FIGS. 3A and 3B. In FIG. 7, only the transducer of the sensor has been shown, the target being identical to that of FIG. 3B. The transducer of the sensor of FIG. 7 differs from the transducer of FIG. 3A mainly in the shape of its secondary winding. The transducer of the sensor of Fig. 7 comprises a secondary winding 123 comprising 2N alternating winding-loop or winding turns, connected together in series. In other words, the secondary winding 123 comprises 2N electrical circuit patterns or turns, each being connected to its nearest neighbor in anti-series. More particularly, the winding 123 comprises N turns 123i + of the same winding direction, substantially identical to the N turns 113i of the transducer of FIG. 3A, and furthermore comprises N turns 123i of opposite winding direction, each turn 123i being arranged between two consecutive turns 123i +, and each turn 123i having a circular annular band sector shape, of the same type as the turns 123i +. For the sake of clarity, the connections between the turns 123i + and 123i of the winding 123 have not been shown in FIG. 7, and the two winding directions have been schematized by a + sign for the turns 123i + and by a 5 sign - for turns 123i_. More precisely, in the example of FIG. 7, the angular aperture a of each turn 123i + and 123i has been chosen strictly less than one half electric period in order to allow a more legible graphical representation. In practice, the angular aperture a of each turn 123i + and 123i_ can approach a half electric period by lower value, by exact value, or by higher value. In the particular case where the angular aperture is exactly one electric half-period, which is a preferred but non-exclusive embodiment, the sum of the angular apertures of the N turns 123i + and the angular apertures of the N turns 123i is 360 ° or in other words, the radial tracks constituting two turns 123i + and 123i adjacent share the same spatial coordinates in a frame {R, 0} (not shown) directed by the axis Z and centered on the center of the sensor. Of course, this does not mean that these tracks are merged and that the turns 123i + and 123i are short-circuited, since said tracks can be placed on two different planes along the Z axis.
[0015] The spatial period of repetition between two adjacent turns 123i +, and the spatial period of repetition between two adjacent turns 123i, are maintained equal to an electrical period of the sensor regardless of the angular aperture at turns 123i + and 123i_. A preferred but non-limiting example of the implementation of such a set of angular aperture turns different from an electric half-period of a sensor consists in regularly ortho-radially distributing the turns 123i + and 123i-as illustrated. FIG. 8 is a diagram showing the evolution of the amplitude V of the envelope of the electromotive force at the terminals of the secondary winding 123 of the sensor of FIG. 7 as a function of the position angular 0 of the target relative to the transducer. As shown in FIG. 8, when the angular position 0 of the target relative to the transducer varies from 0 ° to 360 °, the amplitude V varies periodically between a high value Vmax and a low value Vmin, with a period of variation approximately equal to an electrical period. An advantage of the transducer of FIG. 7 with respect to the transducer of FIG. 3A is that the amplitude V is approximately centered around 0 volts (Vmin-Vmax). More generally, the implementation of a spatially differential measurement, such as that described, for example, with reference to FIG. 7, makes it possible to obtain an amplitude V which is small in relation to the values Vmin and Vmax. This simplifies the operation of the measurement for displacement estimation purposes, and in particular reduces the influence of parasitic drifts and disturbances. Indeed, certain variations of the amplitude V related to spurious effects, that is to say the origin of which is not the displacement of the target, result only in a variation of gain in the case of sensor of Figure 7, while they result in both a gain variation and an offset variation in the case of the sensor of Figure 3A.
[0016] This is for example the case when the coupling coefficient between the primary, the target and the secondary varies due to a parasitic variation of the target-transducer distance. This is furthermore the case when the amplitude of the excitation current varies, for example in case of parasitic fluctuation of the supply voltage, or in case of drifts of the electrical properties of the primary winding, for example depending on the temperature or relative distance of the transducer and the target. On the other hand, in the example of FIG. 7, the coupling 35 of the secondary winding with external fields carrying information on the displacement of the target is considerably reduced because of the spatially differential nature. of the measure. This is particularly the case for the part of the electromagnetic field generated by the primary which induces the constant part (independent of the position of the target) of the amplitude of the EMF, but also for all the external electromagnetic disturbances which present a substantially uniform distribution in the vicinity of the secondary winding 123.
[0017] The variant of FIG. 7 can be combined with the variant of FIG. 5 to obtain two amplitude signals V and V 'angularly offset by a quarter of an electric period and centered on about 0 volts. It should be noted that the fact that the amplitude V of the envelope 15 of the EMF is approximately centered on 0 volts does not necessarily mean that the modulated electromotive force satisfies these same properties before the implementation of a frequency translation method. and filtering. Generally, the electromotive force (modulated) has a non-zero average value, either because of a voluntary referencing of one of the two terminals of the secondary winding to a defined electrical potential (electrical ground for example), or because of from a referencing by capacitive coupling of its average potential to the potential of the environment (for example the mechanical mass) in the case of a high impedance measurement at the level of the secondary winding. This illustrative example applied to the average value of the electromotive force, also applies to any frequency component of the electrical signal, regardless of its origin, which lies outside a frequency band of interest -Af to 30 + Af around the modulation frequency, or in other words, which is outside a frequency band of interest -Af to + Af around the zero frequency at the end of the frequency translation process.
[0018] First aspect Figure 9A is a diagram showing the expected theoretical evolution of the amplitude signals V and V 'as a function of the angular position 0, in an inductive sensor of the type described above combining the implementation options. FIGS. 5 (two spatially offset secondaries of a quarter electric period) and 7 (each secondary comprises 2N alternating turns of winding direction). As shown in FIG. 9A, the expected theoretical V and V 'amplitudes are triangular periodic signals of period equal to the electrical period of the sensor, varying linearly between the values Vmin and Vmax, with an angular shift of a quarter electric period relative to each other. Indeed, in theory, as indicated in the aforementioned patent EP0182085 (column 12, lines 22 to 57), the amplitude of the envelope of the voltage measured across a secondary winding of an inductive sensor is proportional to the area of the surface portion of the conductive patterns of the target located opposite this secondary winding. However, in the embodiments described above, the conductive surface portion of the target facing the electric circuit patterns or turns of the secondary winding varies linearly with the angular position 0, for the patterns 123i + as for The signals V and V 'should thus vary linearly in portions according to the position 0. However, the inventors have found that, in practice, the variation of the signals V and V' as a function of the position 0, generally has large non-linear areas in an electric period of the sensor. More precisely, in practice, the variation of the signals V and V 'as a function of the position 0 has two substantially linear zones of reduced extent in an electric period of the sensor, these zones being approximately centered on the zero crossings of the amplitudes. V and V ', but between these linear zones are interspersed saturated areas and less linear, these areas being approximately centered on extrema amplitudes V and V'. The low linearity of the amplitudes V and V 'as a function of the position 0 has drawbacks. In particular, by way of non-limiting example, having reduced linearity ranges does not make it possible to take full advantage of the signal processing methods described in patents FR2914126 and FR2891362. FIG. 9B is a diagram showing the actual evolution, typically obtained in practice, of signals V and V 'as a function of the angular position 0 in an inductive sensor of the type described above. As shown in FIG. 9B, the signals V and V 'vary linearly only in portions of angular extent a1, reduced by the measurement range of the sensor, referred to as linearity ranges. By way of example, each linearity range ai has a range of between 20% and 90% of the electrical half-period of the sensor (equal to a ° in the example shown). The linearity range a1, for example, is defined as being the maximum angular range, substantially centered on the average value of the amplitude V, for which it is possible to find a linear approximation VL at the amplitude V, such that the difference EL between the linear approximation VL and the amplitude V is less than a threshold ELO, the threshold ELO being for example defined as a percentage of the extrema of the amplitude V, for example in a range of values between 0, 01% and 10% of the extrema of the amplitude V according to the degree of linearity sought for the sensor. In other words, the linearity range a1, is the maximum angular range over which the amplitude V evolves substantially linearly with the position of the target relative to the transducer, to a maximum approximation close to the fixed value ELO. In practice, it is generally desired to do the opposite, namely to evaluate the maximum linearity error ELm over a given angular range aL, for example but not limited to the angular range over which the measurement is to be made. Also, another way to appreciate the linearity of a sensor is to evaluate the linearity error ELm, defined as the maximum difference between the amplitude V and its linear approximation VL for a given range aL. In a preferred but nonlimiting manner, the desired linearity range for a sensor with two secondary windings is at least 50% of an electric half-period, for example between 50% and 80% of a half-period. When the displacements to be measured are fast and the observation of several samples of the amplitude requires to go beyond 50% of a half electric period. In another preferred example, the desired linearity range for a sensor with three secondary windings is at least 33% of an electric half-period, for example between 33% and 50% of an electric half-period when the displacements to be measured are fast. In the following, unless otherwise stated and without this being considered as an exclusive choice, we will limit ourselves to presenting a sensor with two secondary windings, and for questions of readability we will limit ourselves to presenting the linearity error on a range. of linearity desired of 50% of an electric half-period, without making explicit mention of these conditions, and with reference to the linearity error defined under these conditions by the simple mention of linearity error EL. The inventors have notably found that, for a given target-transducer distance (and for a given range aL), the linearity error EL is generally higher the higher the number N of the sensor poles. However, this limitation does not support the industrial use of an inductive sensor since such use generally requires a high number of poles, typically N = 6, to ensure a robust measurement as indicated below. above. It would be desirable to have inductive displacement sensors, and especially multipole sensors, having a lower linearity error (or wider linearity ranges) than existing sensors, in particular to facilitate operation. amplitudes provided by the sensor. By way of nonlimiting example, the extension of the linearity ranges may advantageously make it possible to take advantage of the signal processing methods described in patents FR2914126 and FR2891362. According to a first aspect, an inductive displacement sensor is sought, and in particular (but not only) a multipole sensor, for example a sensor with two or more pairs of poles and preferably a sensor with six or more pairs of poles, 10 to reduce the linearity error EL over an angular range a1, given, for example over a range b1, extending over half an electric half-period of the sensor for a sensor with two secondary windings, or on a al range, extending over one-third of a half-period electrical period for a sensor with three secondary windings. It can also be considered that an attempt is made to increase the range of the linearity range of the sensor, ie the extent of the range of positions, included in the measurement range of the sensor, in which the amplitude The envelope of the electromotive force across a secondary winding of the sensor varies approximately linearly with the angular position of the target relative to the transducer. The studies carried out by the inventors have shown that the extent of the linearity range of an inductive sensor depends on the target-transducer distance d, sometimes referred to as the air gap, i.e. the distance between the average plane of the or secondary windings of the transducer, and the conductive patterns of the target. By way of example, the target-transducer distance d is defined as the distance between the average plane of the secondary winding (s) of the transducer and the surface of the conductive patterns of the target facing the transducer. Fig. 10 is a diagram showing, for several distinct target-transducer distances in an inductive sensor of the type described above (for example of the type described in relation to Fig. 7, with N = 6 pairs of poles); , the evolution of the amplitude V of the envelope of the electromotive force measured at the terminals of a secondary winding of the transducer as a function of the angular position 0 of the target. The curve V1 represents the evolution of the amplitude V for a target-transducer distance d1, the curve V2 represents the evolution of the amplitude V for a target-transducer distance d2 less than d1, and the curve V3 represents evolution of the amplitude V for a target-transducer distance d3 lower d2. The line V11, in dashed lines, represents the linear approximation of the amplitude V1, the line D12, in dashed line, represents the linear approximation of the amplitude V2, and the line V13, in dotted lines, represents the linear approximation. amplitude V3. As shown in FIG. 10, the signal V has, at the distance d3, a maximum amplitude greater than the maximum amplitude obtained at the distances d2 and d1. On the other hand, the linearity error EL2 of the amplitude V, at the distance d2, is smaller than the linearity errors EL 'and EL3 of the amplitude V at the distances d1 and d3 respectively.
[0019] FIG. 11 is a diagram showing the evolution, as a function of the target-transducer distance, of the linearity error EL of the amplitude V of the envelope of the electromotive force measured across a secondary winding of the transducer of an inductive displacement sensor, for example a sensor of the type described in relation to FIG. 7 (with N = 6 pairs of poles). In this example, the linearity error EL corresponds, in a given range of angular positions 0 extending for example over half of the electrical period of the sensor (on a monotonic portion of the EEM), to the maximum difference ( in absolute value) between a linear approximation of the sensor response and the actual measured response. As can be seen in FIG. 11, there is an optimum target-transducer distance dopt for which the linearity error EL passes through a minimum. More generally, the inventors have found that a minimum of linearity error is observable in all types of inductive displacement sensor, irrespective of the number of pairs of poles in particular. This minimum value is reached for an optimal target-transducer distance which depends on the configuration of the sensor (and in particular the number of pole pairs). It is therefore theoretically possible to obtain a linear response regardless of the inductive sensor. Theoretically, it is meant that when the number of pairs of N-poles is particularly important, the distance D0 becomes extremely low to the extent that it can no longer be measured in practice because of the limited precision and the constraints of implementation of the instrumentation instruments. adapted measures. According to a first embodiment, an inductive displacement sensor is provided in which the target-transducer distance d is between 0.8 and 1.5 times the dopt distance for which the linearity error of the amplitude measured by the sensor is minimal. It should be noted that this optimum distance can easily be determined by tests, for example by drawing curves of the type shown in FIG. 11. However, the inventors have found that, in practice, for certain sensors, and in particular sensors having a number N of large pairs of poles, typically greater than or equal to three and even more particularly for N greater than or equal to six, the optimal target-transducer distance in terms of linearity may be relatively small, for example less than 0.2 mm, this can be problematic for certain types of measurement, especially in industrial environments in which such distances are difficult to accept, especially because of tolerances of manufacture, assembly and use. Moreover, the inventors have found that the optimal target-transducer distance in terms of linearity is a function of several other parameters, including geometric parameters of the sensor such as the outside diameter of the transducer and / or the target. More particularly, the inventors have found that as the diameter of the sensors 35 increases, the optimal target-transducer distance in terms of linearity increases and can take a relatively large value, for example greater than 1 mm, which can be problematic. for certain types of measurement, especially in industrial environments in which it is desired to guarantee a certain compactness. In the case where the optimal target-transducer distance in terms of linearity is incompatible (too much or too little) with the measurement environment, it can be expected to be at a target-transducer distance as close as possible to the distance. optimal within the constraints of the environment, and correct the non-linearity by applying a mathematical processing (post-processing) of the measurement signal. The inventors have, however, found that in practice this solution has limitations in terms of accuracy and robustness, and is not particularly satisfactory for the implementation of the signal processing methods described in patents FR2914126 and FR2891362. A first solution proposed by the inventors and illustrated by FIGS. 12A to 12D, 13A to 13C, 14 and 15, is to add to the sensor an additional piece of electromagnetic field confinement placed at a particular distance from the primary winding. of the transducer, chosen so as to significantly increase the optimal target-transducer distance in terms of linearity.
[0020] Figs. 12A-12D are sectional views schematically illustrating four exemplary embodiments of an inductive displacement sensor. In the example of FIG. 12A, the sensor comprises a transducer 201 and a target 203, arranged at a target-transducer distance d (d being in this example the distance between the mean plane of the secondary winding (s) of the transducer and the plane of the conductive pattern of the target facing the transducer), and does not include additional piece of field confinement.
[0021] In the example of FIG. 12B, the sensor comprises a transducer 201 and a target 203, arranged at a target-transducer distance d, and furthermore comprises an additional piece 205 of field confinement made of a conductive material, for example 5 made of the same material as the conductive patterns of the target, or in any other conductive material, magnetic or not, such as iron, steel, aluminum, copper, etc. In this example, the workpiece 205 is disposed on the side of the target 203 opposite the transducer 201 (i.e., the target 203 is located between the transducer 201 and the workpiece 205), the surface of the workpiece 205 facing the target 203 being preferably approximately parallel to the average plane of the transducer, and thus also approximately parallel to the mean plane of the target (with mounting inaccuracies near). The field confinement piece 205 is preferably periodic in a direction parallel to the degree of freedom in displacement of the sensor, that is periodic by revolution (about an axis which is approximately the axis of symmetry of the target ) in the case of an angular position sensor, the spatial period of the conductive patterns of the confinement piece preferably being different from that of the conductive patterns of the target. As an illustrative but nonlimiting example, the part 205 is symmetrical by revolution. The workpiece 205 is disposed at a workpiece-transducer distance 1, defined in this example as the distance between the mean plane of the primary winding (s) of the transducer, and the plane of the surface of the conductive pattern (s) of the workpiece the transducer. The part 205 is preferably secured to the target, that is to say mobile relative to the transducer when the position of the target 30 relative to the transducer changes. In the example of FIG. 12C, the sensor comprises a transducer 201 and a target 203, arranged at a target-transducer distance d, and furthermore comprises an additional piece 205 'of field confinement, for example identical or similar to the Piece 205 of FIG. 12B. The piece 205 'is preferably periodic by revolution, and for example symmetrical by revolution, around an axis of symmetry which is approximately the axis of symmetry of the primary winding of the transducer. In this example, the workpiece 205 'is placed on the side of the transducer 201 opposite the target 203 (i.e., the transducer 201 is located between the target 203 and the workpiece 205'). The piece 205 'is disposed at a transducer-piece distance 1'. By way of example, the distance is defined as being the distance between the mean plane of the primary winding or windings of the transducer, and the plane of the surface of the conductive pattern or patterns of the part facing the transducer. The piece 205 'is preferably integral with the transducer, that is to say fixed relative to the transducer when the position of the target relative to the transducer changes.
[0022] In the example of FIG. 12D, the sensor comprises a transducer 201 and a target 203 arranged at a target-transducer distance of a first field confinement part 205 (for example identical or similar to the part 205 of the FIG. 12B) disposed on the side of the transducer 201 opposite the target 203, 20 at a distance 1 from the transducer, and a second field confinement piece 205 '(for example, the same as or similar to the piece 205' of Fig. 12C), arranged on the side of the target 203 opposite the transducer 201 at a distance from the transducer (i.e., the transducer 201 and the target 203 are located between the pieces 205 and 205 '). The parts 205 and / or 205 'may be electrically connected or not, punctually or in a spatially distributed manner, to other elements of the sensor. In particular, the workpiece 205 may be electrically connected to one or more conductive patterns of the target, and the workpiece 205 'may be electrically connected to an available electrical potential on the transducer, for example at a point of a secondary winding, at one point of the primary winding, or to the electrical ground of the transducer.
[0023] FIG. 1aA is a diagram comprising four ELA, ELB, ELC and ELD curves respectively representing, for the four sensor examples of FIGS. 12A to 12D, the evolution of the linearity error EL of the sensor as a function of the target distance - transducer. Each of the ELA, ELB, ELC and ELD curves is of the same type as the curve of FIG. 11, ie it passes through a minimum value of linearity error for a certain optimal target-transducer distance, respectively dop tAf doptB, doptC and do- pt. As shown in FIG. 13A, the distance dop tA is smaller than the distance doptB which is itself smaller than the distance dop at the distance dop tp. The tests carried out by the inventors have shown that the addition of one or more additional pieces of field confinement can increase from several tenths of 15 millimeters to several millimeters the optimal target-transducer distance in terms of the linearity of an inductive sensor. displacement. Z-axis positioning of the additional field confinement part (s), and more specifically the distance between this or these parts and the primary winding of the transducer, influences the efficiency of the increase in the field. optimal target-transducer distance in terms of linearity that results from the addition of this or these parts. There is therefore an optimal distance (s) between the primary winding and the additional field confinement piece (s), such as the optimal target-transducer distance dopt. is increased to reach a value between 0.65 and 1.25 times the distance d at which it is desired to operate the sensor, this desired value being for example but not limited to between 0.5 and 1.5 mm, which is a range of values compatible with various industrial applications. FIG. 13B is a diagram showing the evolution, for an inductive angular displacement sensor of the type described above, of the optimum dopt-transducer target distance in tC which is itself less than 30 linearity terms, function of the ratio of the primary-distance distance dpipr, on the target-primary distance decr, in the case of the addition of the additional room 205 'of field confinement as shown in FIG. 12C or 12D. As shown in FIG. 13B, the optimal target-transducer distance in terms of linearity is all the greater as the dpipr '/ dcpr ratio is small. FIG. 13C is a diagram showing the evolution, for an inductive angular displacement sensor of the type described above, of the optimal dopt target-transducer distance in terms of linearity, as a function of the component-primary distance ratio dpipr on the primary-target distance decpr, in the case of the addition of the additional field containment piece 205 as shown in Fig. 12B or 12D. As shown in FIG. 13C, the optimal target-transducer distance in terms of linearity is all the greater as the dpipr '/ dcpr ratio is small. In other words, if we consider the transducer as a set of which we can not distinguish the constituent layers, we can say that the optimal target-transducer distance dopt is all the more important that the ratio l / d ( respectively l / d) is weak. Under these conditions, an illustrative but nonlimiting example of positioning the additional field confinement parts of FIG. 12D is to place: the upper part 205 'at a distance from the primary winding approximately between 0.5 and 2 times the distance between the primary winding and the surface of the conductive patterns of the target; The lower part 205 at a distance from the primary winding approximately between 1.3 and 3 times the distance between the primary winding and the surface of the conductive patterns of the target. Thus, for a given sensor configuration, the dpipr / dec ratio and / or the dpipr '/ dec ratio may be chosen such that the distance dopt is compatible with the constraints of the application, e.g. equal to 0.3 mm, for example between 0.3 and 10 mm, and preferably between 0.5 and 1.5 mm, in particular for a sensor comprising a number N of large pole pairs, for example 1 14 and preferably 1 16. It will be appreciated that the aforementioned choice of distance between the field confinement piece and the transducer is generally not optimal in terms of the signal level provided by the secondary winding (s) of the transducer. Indeed, at this distance, the conductive part 205/205 'causes a significant decrease in the level of the signals V and V' provided by the transducer. It will be noted in particular that in the state of the art of the inductive measurement of angular displacement, it is agreed to remove as far as possible the conductive parts likely to modify the spatial distribution of the electromagnetic field which is established in the presence of the only primary, secondary and target elements. This dimensioning criterion is particularly applicable in the case of electrostatic screens (or shielding screens), which, when provided, are arranged at distances along the Z axis which are much greater than the distances provided for in the modes. described, so as not to too much attenuate the level of useful signal measured at the secondary level. However, the proposed embodiments define a compromise which may be sensible in applications for which linearity is important, and particularly in applications in which it is desired to implement signal processing methods of the type described in patents FR2914126. and FR2891362 mentioned above.
[0024] Figures 14 and 15 are front views showing examples of field containment pieces 205 that may be used in an inductive displacement sensor of the type described above (parts 205 'of the aforementioned sensors may have different configurations). similar or identical). In the example of FIG. 14, the piece 205 is a simple disc made of a conductive material (for example metal) of diameter, for example greater than or equal to the outside diameter of the target. Alternatively (not shown), the disk may be pierced at its center, for example a hole less than or equal to the inner diameter of the conductive patterns of the target. In the example of FIG. 15, the part 205 is a disk of the same diameter but having radial grooves or slots coherent with the patterns of the target, making it possible to obtain a Moiré-type constructive effect with the target capable of amplifying the image. influence of the part 205 on the distribution of the field at a secondary winding of the transducer. The described embodiments are however not limited to these two particular examples. A second solution for changing the optimal target-transducer distance in terms of linearity, usable in addition or as an alternative to the addition of a conductive field confinement part, is illustrated by FIGS. 16A, 16B and 17. FIGS. 16A and 16B illustrate two embodiments of an inductive angular position sensor. In Figures 16A and 16B, only the target of the sensor has been shown. The arrangement of the transducer, and in particular of its primary winding and its secondary winding or windings, is in correspondence with the arrangement of the target, and can easily be deduced from the shape of the target on reading the foregoing.
[0025] In this example, the target of the sensor of Fig. 16A is similar or identical to the target of Fig. 3B. The target of the sensor of FIG. 16B also comprises N angular-shaped annular band sector-shaped conductors 137i approximately equal to one half electric period (for example 360 ° / 2N), the N units 137i being regularly distributed on along an annular band described by the target. The target of FIG. 16B differs from the target of FIG. 16A in that the conductive patterns 137i have different radial dimensions (lower in the example shown) than the radial dimensions of the conductive patterns 117i of the target of FIG. 16A. . More particularly, in this example, the annular band determining the shape of the conductive patterns 137i has an external radius Rext substantially identical to that of the annular band determining the shape of the patterns 117i, but has an internal radius Rint less than 5. of the annular band of the conductive patterns 117i. The inventors have found, as illustrated by FIG. 17, that, for a given number of pairs of poles, the optimal target-transducer distance dopt in terms of the linearity of the response of the sensor, varies according to the ratio Rint / Rext 10 between the inner radius and the outer radius of the annular band in which are located the conductive patterns of the target, and consequently in which are located the turns of the secondary windings of the sensor. It should be noted that the implementation of FIG. 16B, which consists in changing the Rint / Rext ratio by modifying the internal radius Rint of the conducting patterns of the target, is by no means exclusive of other implementations making it possible to evolve the Rint / Rext ratio by modifying either the outer radius Rext or the two radii together.
[0026] FIG. 17 is a diagram showing the evolution, for an inductive angular displacement sensor of the type described above, of the optimum linear dopt target-transducer distance in terms of the ratio Rint / Rext. in Fig. 17, the optimal target-transducer distance in terms of linearity is all the more important as the ratio Rint / Rext is important. Thus, for a given sensor configuration, the ratio Rint / Rext can be chosen such that the distance Dopt is compatible with the constraints of the application, for example greater than or equal to 0.3 mm, for example between 0 , 3 and 10 mm, and preferably between 0.5 and 1.5 mm, especially for a sensor having a number N of large pole pairs, for example 1 14 and preferably 1 16. Electromagnetically, it appears that modifications to the internal and / or external radii of the target have the effect of modifying the shape ratio of the conductive patterns, and in particular of modifying the contribution of the radial edges to the to the contribution of the orthoradial edges, this ratio of the contributions being a determining factor of the optimal target-transducer distance in terms of linearity dopt. When the ratio Rint / Rext between the inner radius and the outer radius of the target increases, the annular band portion which constitutes a conductive pattern crushes in the radial direction, resulting in a reduction of the contribution of the radial edges to the distribution of the target. global field measured by the secondary, reflected in the secondary output signal by an increase in the target distance-optimal transducer in terms of linearity. The solution described therefore consists in modifying the spatial distribution of the electromagnetic field, and more particularly the ratio of the radial contributions with respect to the orthoradial contributions, in order to adjust the optimal target-transducer distance in terms of linearity dopt so that it is compatible with the constraints of the application. In the sensor of Fig. 16B, when the inner radius Rint and / or the outer radius Rext of the target of Fig. 16B change, the inner and outer radii of the associated transducer preferably evolve substantially in the same proportions, in order to maximize the signal level received by the secondary. By maximizing the secondary output signal level, more specifically is meant maximizing the slope at the origin of the signal rather than maximizing the values taken by the signal extrema for certain positions. For a set of internal Rint radii and external Rext of given target, the signal received by the secondary of the associated transducer 30 is maximum when the annular band delimiting the patterns of the target and the annular band delimiting the patterns of the secondary overlap substantially, or presented differently, when the orthoradial outer and respectively inner edges of the target and the outer and inner orthoradial branches respectively of the secondary are superimposed.
[0027] It will be noted that for a given sensor size (and especially for a high limit of outer radius and a low limit of internal radius), increasing the ratio Rint / Rext amounts to decreasing the surface of the conducting patterns of the target, this which causes a decrease in the amplitude of the variations of the level of the sensor output signals as a function of the position of the target relative to the transducer. Thus, in the state of the art of the inductive measurement of angular displacement, the inner diameter and the outer diameter of the annular band in which are located the conductive patterns of the target, and consequently in which are located the turns of the secondary winding or windings of the sensor are dimensioned so as to occupy the maximum of available surface space in the given space, the space requirement being generally constrained by the interior opening and the outside diameter of the support and / or the housing in which the sensor is integrated, or by the outside diameter of the shaft around which the sensor is installed and by the inside diameter of the interfaces between which the sensor is housed.
[0028] Nevertheless, the proposed solution of modifying the Rint / Rext ratio defines a compromise which may be sensible in applications for which linearity is important. A third solution for modifying the optimal target-transducer distance in terms of linearity, usable in addition or as an alternative to adding an additional piece of field confinement, and / or modifying the Rint / Rext ratio, is 18A, 18B and 19. This third solution is in the same logic as the solution just described, in the sense that it consists in modifying the shape factor of the conductive patterns of the target and / or corresponding secondary winding turns, and in particular to modify the ratio between the radial dimension and the ortho-radial dimension of the target patterns and / or the secondary winding turns, in order to adapt the target distance-3031589 B13316 39 optimal transducer in terms of linearity to the constraints of the application. FIG. 18A illustrates three exemplary embodiments of an angular position sensor of the type described above. In FIG. 18A, only a conductive pattern of the target, designated respectively by the references 117i for the first example (solid line), 117i 'for the second example (in broken lines), and 117i "for the third example ( In each example, the target is obtained by regularly repeating the conductive pattern shown along a circular annular band, and the inner and outer radii of the patterns 117i, 117i ', and 117i "are substantially identical, but the patterns 117i, 117i ', and 117i "differ from each other in their angular dimensions, more particularly in this example, the angular aperture of the pattern 117i' is approximately equal to one half electric period (e.g. 360 ° / 2N), as described above, the angular aperture of the pattern 117i "is greater than one half electric period of a value Aal, for example between 0% and 50% of a half electric period 20 , and the angular aperture of the pattern 117i is less than 360 ° / 2N of a value 4a2, for example between 0% and 50% of a half electric period. As for the implementation of the solution of FIGS. 16A, 16B and 17, the secondary arrangement of the transducer is preferably in correspondence with the arrangement of the conductive patterns of the target, that is to say that the Angular aperture of the secondary patterns matched to the patterns 117i 'of the target is substantially equal to an electric half-period (for example 360 ° / 2N), the angular aperture of the secondary patterns 30 adapted to the patterns 117i "of the target is greater than 360 ° / 2N by a value substantially equal to Accl, and that the angular aperture of the secondary patterns adapted to the target 117i is less than 360 ° / 2N by a value substantially equal to 4a2. when the angular aperture of the secondary patterns 35 takes a value greater than one half electrical period of 3031589 B13316 sensor, it can be provided to ensure electrical isolation between the adjacent turns of tracks, to change the shape of the tracks d at least one metallization plane, and / or to increase the number of metallization planes. Another embodiment option may consist in limiting the maximum angular aperture of the secondary patterns to substantially one half electric period, and in changing only the angular aperture of the target patterns (values Aal or 4a2). In this case, the angular aperture of the patterns of the secondary winding of the transducer is not strictly in correspondence with the angular aperture of the patterns of the target. The inventors have found that the optimum dopt target-transducer distance in terms of the linearity of the sensor response varies as a function of the angular deviation Δ entre between the angular aperture chosen for the target and secondary patterns, and the nominal angular aperture equal to one half electric period of the sensor. Fig. 19 is a diagram showing the evolution, for a given multi-pin angular displacement sensor of the type described above and illustrated in Figs. 18A and 18B, of the optimal dopt-target transducer distance in terms of linearity, according to of the value Aa. As can be seen in FIG. 19, the optimal target-transducer distance in terms of linearity is all the lower as the value Aix is large by 25 negative values, and conversely the more important the value Aix is by positive values. Thus, for a given sensor configuration, the angular aperture of the conductive patterns of the target can be modified by a value Aix with respect to the nominal value a (equal to one half electric period, for example 360 ° / 2N). ), the value Aix being chosen such that the distance dopt is compatible with the constraints of the application, for example is greater than or equal to 0.3 mm, for example between 0.3 and 10 mm, and preferably between 0.5 and 1.5 mm, especially for a sensor having a number N of large pole pairs, for example 1 14 and preferably 1 16. Solutions have been described above for decreasing the linearity error (or increasing the range of the linearity range) of the response of an inductive displacement sensor, as well as for modifying, i.e. to say increase or decrease according to the initial situation, the target-transducer distance for which an inductive displacement sensor presents or approaches the optimal characteristics in terms of linearity.
[0029] Note that if the linearity error still remains too large (or if the range of the linearity range obtained remains insufficient), it will be possible to add one or more additional secondary windings, spatially offset (of a substantially angular offset). equal to each other), so as to reduce the extent of the minimum linearity zone necessary for good reconstruction of the positioning and / or displacement information of the target, in combination with the application of the solutions described above. By way of illustrative example, in the sensor of FIG. 5, instead of providing two identical secondary windings spatially offset by a quarter of an electric period, three identical secondary windings can be provided which are spatially offset by one sixth of the period electric sensor. In addition, it will be appreciated that the above-described solutions can be adapted to inductive linear displacement sensors, for example by "unwinding" the circular band patterns described above to turn them into straight strip patterns. In addition, it will be noted that the solutions described above can be adapted to inductive angular displacement transducers whose transducer has an angular aperture less than 360 °, for example less than 180 ° in order to allow mounting "by the side of the transducer around a rotating shaft, rather than a "through" mount. In this case, the angular aperture of the target may have a value of 360 °, independent of the angular aperture of the transducer, or take a value less than 360 °, corresponding, for example, to the angular displacement range. of the application. Second aspect The inventors have furthermore found that, in practice, independently of the problem of linearity, the existing displacement inductive sensors, and in particular the multipole sensors, are sensitive to various disturbances by coupling effect. Such disturbances occur, for example, on the one hand at the level of the transduction zone, that is to say directly at the secondary level of the transducer, and on the other hand at the level of the electrical connection zone between the secondary transducer and a functional block of conditioning electronic means. These disturbances include the coupling of electromagnetic disturbances coming from outside the sensor (ie not generated by the primary winding), the direct inductive coupling of the primary winding with the winding. secondary (i.e., the proportion of inductive coupling that remains constant regardless of the position of the target), and / or the capacitive coupling between the primary winding and the secondary winding. These disturbances can cause undesirable fluctuations in the output signal (s) of the sensor and errors in interpretation of the output signals of the sensor.
[0030] It would be desirable to have inductive displacement sensors, and in particular multipole sensors, which are less sensitive to interference disturbances and / or less subject to spurious coupling than existing sensors. Thus, according to a second aspect, it is sought to reduce the sensitivity to interference disturbances and coupling effects of inductive sensors for multipole displacement, and more particularly to sensors of the type described with reference to FIG. 7, that is to say wherein the secondary winding (s) each comprises 2N alternating winding turns, N being the number of pairs of poles of the sensor. For this purpose, the inventors propose a particular arrangement of the secondary winding (s) of the sensor, which will be described hereinafter. FIGS. 20A and 20C schematically illustrate two exemplary embodiments of an inductive angular displacement sensor, with 360 ° angular aperture, consisting of N = 6 pairs of poles, and carrying out a spatially differential measurement (for example such as described in connection with Figure 7). In Figs. 20A and 20C, only one secondary 213 of each sensor has been shown, making the primary winding, the target, and, optionally, one or more additional secondary windings spatially offset from the winding 213, being within the reach of those skilled in the art from the explanations of the present description. In this example, the secondary of the sensor of FIG. 20A and the secondary of the sensor of FIG. 20C are similar or identical to the secondary of FIG. 7, with the difference that the electrical connections between the turns are presented. The secondary of FIG. 20A presents a first method of connecting the turns to each other, according to which the entire angular aperture of the annular band over which the secondary stretches is traversed for a first time, for example in the direction trigonometrically in the figure, then the whole of the annular band is scanned a second time, this time in the clockwise direction, in order to bring the end of the electrical end E2 close to the electrical end El of departure, and thus close the measuring circuit. The secondary of FIG. 20C shows a second method of connecting the turns to each other, according to which a first half of the angular aperture of the annular band over which the secondary stretches is first traversed, for example in the counterclockwise in the figure, then the return path is traversed clockwise to approach the input end E1, and then the other half of the angular aperture of the annular band on which the secondary retaining the direction of clockwise rotation, then one traverses the return path in the trigonometric direction in order to bring the end electrical end E2 close to the electrical end El of departure, and thus close the measurement circuit as for the secondary of Figure 20A.
[0031] Figures 20B and 20D are front views schematically showing an exemplary embodiment of a transducer of an inductive linear displacement sensor. The sensors of FIGS. 20B and 20D are sensors in which a target (not shown) having N conductive patterns is adapted to move in translation in a rectilinear direction x with respect to the transducer. The sensor of FIG. 20B is for example of the same type as the sensor of FIG. 20A, adapted in a linear configuration, which essentially amounts to "unrolling" the circular annular bands of the sensor of FIG. 20A and replacing the patterns conductors and turns in the form of an annular band sector, with conductive patterns and turns of rectangular or square general shape. The sensor of FIG. 20D is for example of the same type as the sensor of FIG. 20C, adapted in a linear configuration. In FIGS. 20B and 20D, only one secondary winding 213 of each sensor has been shown, the realization of the target, the primary winding, and, optionally, one or more additional secondary windings spatially offset from the winding 213 being within the abilities of those skilled in the art from the explanations of the present description. By way of example and unlike the primary winding of the angular sensors of FIGS. 20A and 20C, an example of a primary winding obtained when "unwinding" the set of two concentric turns 101a and 101b for example described for the sensor of Figure LA, for example consists of a single turn for a linear sensor as described in Figures 20B and 20D, possibly consisting of several turns. The turn of the primary winding is, for example, of generally rectangular shape, of dimension along y close to the dimension according to the conductive patterns of the target and / or turns of the secondary winding as described above, and of dimension over x greater than the dimension according to x of the conductive patterns of the target and / or turns of the secondary, so that the contribution to the global electromagnetic field distribution, created at the level of the primary branches oriented according to y and which is located at both ends along x of the primary, or relatively attenuated in the vicinity of secondary branches oriented along y and which are located at both ends along the secondary x. In particular, for a transducer with a single secondary winding, the extent of the primary will be greater than the extent of the secondary, and preferably but not exclusively, greater by at least one half electric period of the sensor, distributed equally (at least a quarter of an electrical period) at each end of the sensor. In general, a preferred embodiment of the primary winding of an inductive linear displacement sensor is a coil of generally rectangular shape and of greater extent than the overall extent of the set of secondary, for example, but not exclusively, greater than at least one half electric period 20 of the sensor, distributed equally (at least a quarter of electric period) at each end of the sensor. In the examples of FIGS. 20B and 20D, the sensors comprise N = 6 pairs of poles. The described embodiments are however not limited to this particular case.
[0032] In the example of the sensor of FIG. 20D, the secondary winding 213 extends in a zone having a dimension Dtot parallel to the degree of freedom of the sensor, that is to say parallel to the direction x of displacement of the target relative to the transducer. The winding 213 comprises 2N 30 alternating winding winding loops or turns of turns connected electrically in series between its ends E1 and E2. More particularly, the winding 213 comprises N loops or turns 213i + having the same first winding direction, and N loops or turns 213i having the same second direction of winding opposite the first direction, each turn 213i + or 213i having a dimension in the direction x approximately equal to an electric half-period of the sensor (ie for example approximately equal to Dtot / 2N), and the turns 213i and 213i + being juxtaposed two by two from alternately along the dimension zone Dtot 5 of the secondary winding. According to a second embodiment, the secondary winding is constituted by: a first conductor section 213A in a serpentine forming N half-turns of alternating directions, extending between a first end El of the winding, situated approximately at the level of midpoint of the distance Dtot along which the winding 213 extends parallel to the x direction, and a first intermediate point A of the winding, located at a first end of the distance Dtot; A second conductor section 213B serpentine forming N half-turns of alternating directions complementary to the N half-turns of the section 213A, extending between the point A and a second intermediate point M of the winding, situated approximately at the level of middle of the distance Dtot; A third conductor section 213C in a serpentine pattern forming N half-turns of alternating directions, extending between the point M and a third intermediate point B of the winding, located at the second end of the distance Dtot; and a fourth coil conductor section 213D forming N half-turns of alternating directions, complementary to the N half-turns of the section 213C, extending between the point B and a second end E2 of the winding, situated approximately at the level of middle of the distance Dtot, near the first end El of the winding.
[0033] More particularly, in the example shown, in the left part of the winding (in the orientation of the figure), the section 213A comprises N U-shaped half-turns whose vertical branches are oriented in opposite directions. in a direction y which is approximately normal to the x direction, and the section 213B comprises N U-shaped half-turns, the vertical branches of which are alternately oriented in opposite directions in the y-direction. Each U-shaped half-turn of the section 213A has its vertical branches approximately aligned with the vertical branches of a U-shaped half-turn of opposite orientation of the section 213B. The sections 213C and 213D are arranged in a similar arrangement in the right part of the winding. Thus, in this example, the portions of the winding 213 orthogonal to the direction of displacement x are traversed twice and only twice by the wire or the track of the winding 10 (with the exception of the two extreme orthogonal portions of the winding). at the two ends of the distance Dtot, which, in this example, are traversed once - this exception does not occur, however, in the case of an angular sensor angular opening of 360 °, in which all 15 radial portions of the winding can be traversed twice and twice only by the thread or the winding track), and the portions of the winding 213 parallel to the direction of displacement x are traveled once and once only by the wire or the track of the winding.
[0034] In terms of the path traveled by the constituent electrical circuit of the secondary winding patterns, the implementation of the solution of FIG. 20D is in accordance with the implementation of a solution of the type described in relation to FIG. 20B. , and by linear-angular transposition is also consistent with the implementation of the solutions of Figures 20A and 20C. In contrast, the sequence in which this path is traveled differs between the transducer of FIG. 20D (and by transposition of the transducer of FIG. 20C), and the transducer of FIG. 20B (and by transposition of the transducer of FIG. 20A). . In particular, the arrangement described in connection with Figures 20D and 20A is designed to reveal an intermediate connection point M between the ends E1 and E2.
[0035] The winding 213 may be provided, in addition to terminals PE1 and PE2 for connection at its ends E1 and E2, with a third access terminal PM connected to the midpoint M of the winding. In the case of multipole sensors comprising a number 5 N of even pole pairs, and as shown in FIG. 20D, the secondary winding has as many turns 213i + (so-called positive) on the right as turns 213i + to left (N / 2 on each side), and consequently the secondary winding has as many turns 213i (so-called negative) on the right than turns 213i on the left (N / 2 on each side). An advantage of the secondary winding arrangement of FIG. 20D when the number of pole pairs takes an even value lies in the fact that the induction is substantially identical, with the sign close, regardless of the position of the target. 15 relative to the transducer, on the two portions El-M and E2-M on either side of the midpoint, while allowing the three connections El, E2 and M to be close to each other. This preferred implementation in which the number of pole pairs takes even values is by no means exclusive of other embodiments. As a variant, if the number N of pairs of poles is high, the choice of an odd number N is quite acceptable insofar as the signal symmetry error between the portion El-M and the portion E2 -M evolves as an inverse function of N.
[0036] The inventors have found that when the sensor is produced according to the second embodiment, if reference is made to the midpoint M of the winding at a given electrical potential of differential measuring means, for example at a constant and centered potential. on the voltage measurement dynamic of the measuring means, the common-mode component contained in the electrical signal present at the terminals of the dipole E1-E2, which carries no useful information on the position and displacement of the target by relative to the differential mode component contained in the same electrical signal present at the terminals of the dipole E1-E2, the differential mode component being, on the other hand, carrying useful information on the displacement. of the target relative to the transducer. The arrangement of the sensor of FIGS. 20C and 20D making it possible to place the midpoint M in the immediate vicinity of the ends E1 and E2 thus has a certain advantage, for example with respect to the arrangement of the sensor of FIG. 20B in which the point medium M is remote from the ends E1 and E2, and more generally with respect to the arrangements of the sensors of FIGS. 20A and 20B in which the voltages E1-M and E2-M depend on the position of the target relative to the transducer, or otherwise, with respect to the sensor arrangements in which the ratio of the common mode component to the differential mode component across a secondary winding is not small and varies greatly with the position of the target relative to the transducer . In particular, an advantage of the sensors described in FIGS. 20C and 20D when the mid-point M is connected in a manner adapted to the measuring means, lies in the high immunity of the two electrical potentials at the ends E1 and E2, at the component the electromagnetic excitation field (primary) which does not vary with the position, whereas the only spatially differential character of the measurement of the sensor of FIG. 7 guarantees immunity only on the difference of potentials at the ends E1 and E2.
[0037] In addition to the immunity to the "direct" field emitted by the primary (source internal to the system), the sensors of FIGS. 20C and 20D also offer increased immunity to electromagnetic and / or electrostatic disturbances emitted by an external source at the level of the transduction zone and whose spatial distribution is relatively homogeneous, or more generally an increased immunity to any form of electromagnetic and / or electrostatic disturbance with respect to sensors such as those described in Figures 20A and 20B. Examples of practical advantages of increased immunity to external disturbances in the transduction zone are, for example, the reduction of stress on the protections of the electronic measuring means, such as overvoltage protection, and / or relaxation of design constraints on electrical signal conditioning systems, such as the common mode rejection ratio of the differential amplifiers. It will be noted that the adaptation of an inductive sensor to implement a mid-point according to the second embodiment can lead to increasing the number of interfaces of the conditioning circuit (for example the number of legs of an integrated circuit ). It will be noted in particular that according to the state of the art of inductive measurement, it is rather agreed to minimize the number of physical interfaces by substituting electronic or digital processing. However, this second embodiment makes it possible to achieve with a relatively simple electronic solution, levels of immunity and robustness of measurement much higher than with known solutions. FIG. 20E is an electrical representation "small signals" of the useful induction phenomena Vivi 'and VM2, that is, signals carrying information or part of the information on the position and / or the displacement of the target with respect to the transducer, and parasitic induction phenomena Vp, Vp ', and Vp "at the connection wires between the terminals El, E2 and M of the transducer, and the terminals PE1, PE2 and 25 PM for example connected to the level of external electrical means In this figure, and since the son connected from El, E2 and M closely follow each other, the common mode disturbances Vp, Vp ', and Vp "are substantially equal and are compensated substantially in the VpEi measurements (performed at the terminals of the PM-PE1 dipole) and VPE2 (performed at the terminals of the PM-PE2 dipole) on the one hand, and in the VpE1pE2 measurement carried out on the PE1-PE2 dipole terminals. somewhere else. Once the potential of the PM terminal is set to a known value VREF, the signals measured across the tripole (PE1, PE2, PM) become extremely immune to external electromagnetic disturbances in the connection area between the transducer terminals. (E1, E2, M) and the connection terminals to the external electrical means (PE1, PE2, PM), on the one hand to the first order by limiting the risks of overvoltage on the inputs of the electronic means (the signal levels remain 5 in the dynamics of the conditioning means, and the measurement is valid unconditionally), and secondly in the second order by relaxing the requirements on the common mode rejection ratio of the differential measurement VpmpE2 (the measurement error introduced by the disturbances is low). For example, a reference voltage of the conditioning unit, or half of the supply dynamics of the conditioning unit, or the electronic mass, can be applied to the terminal PM, without these embodiments being exclusive to the control unit. other embodiments such as for example the connection of the terminal PM or M directly to a potential of the transducer such as the mass. This gives a signal representative of the position of the target relative to the transducer, particularly robust to disturbances and / or parasitic coupling effects, whether they occur at the transduction zone or the connection zone between the transducer and external electrical means, and whether they are of inductive nature as shown in the electrical diagram of FIG. 20E, or of capacitive nature with the electrical environment of the transducer and / or the primary winding and in particular the portions close to the primary hot spot (high voltage). On the other hand, in the case where the transducer comprises a plurality of spatially offset secondary windings (for example as described with reference to FIG. 5), the different windings may be arranged in and / or on different superimposed support layers each comprising one or more metallization levels. This configuration, although satisfactory for many applications, can however pose problems of robustness and accuracy. Indeed, it follows that the average planes of the different secondary windings are located at slightly different distances from the primary winding and the target. This results, in particular, in the first order, a difference in transduction gain, and therefore a difference in signal level at the output of the different secondary windings, and in the second order of the characteristics of different linearity between several secondary windings of the same transducer. . To solve this problem, it is preferably provided, as illustrated by FIGS. 21A, 21B, 22A and 22B by way of non-limiting example, of distributing the different secondary windings of the transducer in two metallization levels, for example in a same carrier layer with two metallization levels, such that for each winding, the runway length or wire of the winding disposed in the first metallization level is approximately equal to the length of the track or wire of the winding arranged in the second level of metallization. Preferably, there is provided a sustained alternation of the metallization plane changes, such that a secondary track can not travel on the same plane a distance (for example an angular aperture in the case of an angular sensor) greater at half an electric period. In a preferred embodiment, the metallization plane changing zones are located such that there is a symmetry and / or antisymmetry relationship between most of the track portions disposed on the first metallization level. , and most of the track portions disposed on the second metallization level, as shown in Figs. 21A, 21B, 22A and 22B. Thus, the average planes of the different secondary windings are merged and correspond to a virtual intermediate plane located between the first and second metallization levels. This gives each electromotive force induced at the terminals of each secondary, a response as a function of the position of the target substantially identical in terms of amplitude and linearity, to that of the electromotive forces 35 induced at the terminals of the other secondary.
[0038] It will be noted that the exemplary embodiments presented in FIGS. 21A, 21B, 22A and 22B correspond to sensors of angular extent Dtot = 360 °, that is to say the angular band occupied by each secondary element. an angular aperture substantially equal to one complete revolution. These examples are not exclusive of alternative embodiments which would implement angular aperture sensors strictly less than 360 °, for example less than or equal to 180 ° in order to allow mounting "by the side" of the sensor around a rotating shaft, rather than a "through" mounting of the sensor around said shaft in the case of a 360 ° angular aperture sensor as described in Figs. 21A, 21B, 22A and 22B for example. Under these conditions it will be recalled moreover that the angular aperture of the target may alternatively maintain a value of 360 ° independently of the angular aperture taken by the secondary or secondary transducer, or take a value less than 360 ° and for example adapted to the range of angular displacement of the application. FIGS. 21A and 21B are front views diagrammatically representing an exemplary embodiment of a transducer with two secondary windings 223 (as a dashed line) and 223 '(as a solid line) spatially offset by a quarter of the period electrical sensor, for an inductive sensor of angular displacement. In the example shown, the number N of 25 pole pairs of the sensor is 6, and each secondary winding 223, 223 'comprises 2N = 12 loops or turns. The described embodiments are however not limited to this particular case. In this example, the two secondary windings 223 and 223 'are formed in and on the same support with two metallization levels Ml and M2 connected by conductive vias (shown schematically by circles). For each winding, the track length formed in the level Ml is approximately equal to the track length formed in level M2. Fig. 21A is a front view of the metallization level M1, and Fig. 21B is a front view of the metallization level M1. The patterns of the level M1 are found substantially from the units of the level M2 by antisymmetry with respect to an intermediate plane between the mean planes of the levels Ml and M2. The windings 223 and 223 'each have, seen from above, an arrangement of the type described in connection with Fig. 20C (i.e., an arrangement of the type described in connection with Fig. 20D adapted in an angular configuration, the winding principle described in connection with FIG. 20D then applying in a similar manner, the distance Dtot being no longer a linear distance but being now an angular distance, equal to 360 °). Thus, the winding 223 comprises: a first curved serpentine conductor section 223A forming N half-turns of alternating directions, extending along a first circular annular half-strip in the illustrated example) between a first end El of the winding 223, located approximately at the middle of the distance Dtot (for example in the vicinity - that is to say, within 5 ° and preferably to 2 ° close - of an angular position to which will arbitrarily assign the value 0 °), and an intermediate point A of the winding, located at a first end of the distance Dtot (for example in the vicinity of the angle 180 °); a second conductor section 223B in a curved coil forming N half-turns of alternating directions, complementary to the N 25 half-turns of the section 223A, extending along the first annular halfband between the point A and a second intermediate point; M of the winding, located approximately at the middle of the distance Dtot (for example in the vicinity of the 0 ° angle); A third conductor section 223C in a curved coil forming N half-turns in alternating directions, extending along a second complementary annular half-band of the first half-band between the point M and a third intermediate point B of the winding, located at an opposite end of the distance Dtot (for example in the vicinity of the angle -180 °); and a third conductive section 223D in a curved coil forming N half-turns of alternating directions, complementary to the N half-turns of the section 223C, extending along the second annular half-band between the point B and a second end 5 E2 of the winding, located approximately at the middle of the distance Dtot (in this example in the vicinity of the 0 ° angle). As shown in FIGS. 21A and 21B, in this (nonlimiting) example, the portions of the winding 223 orthogonal to the direction of movement of the target relative to the sensor, that is to say the radial branches of the winding, are traversed twice and twice only by the wire or the winding track, and the portions of the winding 223 parallel to the direction of movement of the target relative to the sensor, that is, that is to say the ortho-radial branches of the winding, are traversed once and once only by the thread or the winding track. More particularly, in this example: the radial portions positioned at angles offset by 0 ° modulo electric half-period, with respect to the angle that characterizes the end El, are traversed twice and twice only by the wire or the winding track 223; the radial portions positioned at angles offset by one quarter electric period modulo one electric half-period, with respect to the angle which characterizes the end E1, are traversed twice and only twice by the wire or the track of the winding 223 '; and the ortho-radial portions are traversed once and once only by the wire or the track of the winding 223, and once and once only by the wire or the track of the winding 223 '.
[0039] This embodiment makes it possible to contain in two planes and only two metallization planes, two secondary ones as described in the preceding solutions, that is to say without making any concessions on the overall shape of the patterns of each secondary. It should be noted that the embodiments shown in FIGS. 21A, 21B, 22A and 22B implement two secondary ones arranged on two metallization planes, but are not at all exclusive of other embodiments such as a mode of embodiment. embodiment that would implement for example three secondary disposed on three metallization planes.
[0040] In this example, each of the U-shaped half-turns of each of the sections 223A, 223B, 223C and 223D of the winding 223 (in outline) has approximately half of its length in the metallization level M1 and the other half half of its length in the metallization level M2. A change of level occurs every L / 2 meters of approximately conductive track, where L denotes the length of a turn of the winding, consisting of two U-shaped half-turns in series. In the example shown, the level change points of the winding are located at the midpoints of the orthoradial branches (or horizontal branches) of the U forming the half-turns. The described embodiments are however not limited to this particular case. In FIGS. 21A and 21B, the numbers going from C1 to C28 designate, in the order of travel between the terminals E1 and E2, different portions of the winding 223.
[0041] The secondary winding 223 '(solid line) is disposed in the levels M1 and M2 in an arrangement substantially identical to that of the winding 223, but with an angular offset of approximately one quarter electric period (this is 15 ° in this example) with respect to the winding 223. Note that in the structure of FIGS. 21A and 21B, the connection tracks at the ends E1 and E2 of the winding 223 may for example be located respectively in the metallization levels M1 and M2, and superimposed on each other. This makes it possible to minimize the parasitic coupling difference on each of these branches with any external induction source (primary connection track, external electromagnetic disturbance, etc.). An access track at the mid-point M of the winding may be located in a third metallization level (not shown) superimposed on the access paths to the terminals E1 and E2 which are in the metallization levels. Ml and / or M2, or be located in one of the metallization levels Ml and M2, slightly offset with respect to the access paths to the terminals El and E2. A similar arrangement of the access paths to the corresponding terminals El ', E2' and M 'of the winding may be provided for the winding 223'. More generally, regardless of the arrangement of the access tracks, in order to increase the immunity to electromagnetic interference between the (secondary) transduction zone and the access and / or connection terminals to the signal conditioning means , it is preferably sought to keep the paths from the ends E1 and E2 as close as possible (for example superimposed in the PCB technology), and to a lesser extent to place the path from the intermediate point M close to the 15 paths since the ends E1 and E2. It will also be noted that in the example of FIGS. 21A and 21B, in addition to the vias performing the metallization level changes of the windings 223 and 223 ', and the conductive tracks flowing in each metallization plane for the purposes of field capture. , vias or conductive filler pads, without electrical connection function between field capture tracks, have been regularly distributed along the windings 223 and 223 '. These conductive filler patterns have the role of symmetrizing the conductive structure 25 of the transducer, in order to periodise their influence on the spatial distribution of the field, and particularly to minimize the singularities of the field distribution which would result in an evolution of the signal. secondary school leaving depending on the position. The addition of these conductive filler patterns, however, is optional. In particular, if the vias performing the metallization level changes have small dimensions relative to the skin thickness, the working frequency, the material that constitutes them, it can be expected not to add the conductive pads and In particular, they do not drill, which can reduce the cost of the device. Figs. 22A and 22B are front views schematically showing an alternative embodiment of a transducer 5 of the type described in connection with Figs. 21A and 21B. This variant embodiment differs from the example of FIGS. 21A and 21B in that, in the example of FIGS. 22A and 22B, the metallization level changes are more numerous than in the example of FIGS. 21A and 21B. Thus, in the example of Figs. 22A and 22B, instead of a metallization level change every L / 2 meter conductive track of the secondary winding, where L is the length of a turn of the coil. Winding, it is expected to make k metallization level changes every L / 2 meter track, with k integer 15 greater than or equal to 2. The number k can be chosen taking into account the internal and external radii of the transducer. By way of nonlimiting example, for given sensor dimensions and when the level changes are made only in the orthoradial portions of the turns, k can be chosen as large as it is possible to place adjacent vias (e.g. equi-distributed) on the orthoradial portions without these vias short circuit. For the sake of simplification, FIGS. 22A and 22B show an exemplary embodiment for a sensor with N = 2 pairs of poles, in which the transducer comprises 2 secondary windings 233 (in broken lines) and 233 '(in a broken line). solid) angularly offset by a quarter of the electrical period of the sensor (that is 360 ° / 4N = 45 ° in this example). The variant of FIGS. 22A and 22B, however, is compatible with sensors having a larger number of pole pairs. As in the example of Figs. 21A and 21B, conductive filler patterns without an electrical connection function can be provided to further symmetrize the structure.
[0042] Third aspect In the embodiments of multipole sensors described up to now, for a given dimension Dtot of a secondary winding of the transducer parallel to the degree of freedom of the target with respect to the sensor, and for a number N of given pairs of poles, the maximum range of the range of positions that can be detected by the sensor is about one half electric period (for example Dtot / 2N ie 360 ° / 2N in the case of an angular sensor) if the sensor has only one secondary winding, and can rise to about one electrical period (for example Dtot / N ie 360 ° / N in the case of an angular sensor ) if the sensor comprises more than one secondary winding, for example if it comprises two identical secondary windings spatially offset by a quarter of an electric period (for example Dtot / 4N, that is to say 360 ° / 4N in the case of an angular sensor), or e if it comprises three identical secondary windings spatially offset by one sixth of the electrical period (for example Dtot / 6N, that is to say 360 ° / 6N in the case of an angular sensor).
[0043] In any case, the multipole angular displacement sensors of the type described above do not make it possible to carry out displacement measurements over a complete revolution (360 °) in an absolute manner, that is to say without recourse methods for storing the history of displacements, and / or methods for referencing the position at the start and / or during the operation of the sensor. This observation is true regardless of the number N of pairs of poles greater than or equal to 2, and can be even more problematic when the number N is high, for example 1 14 and preferably 1 16. The linear displacement inductive sensors described above have the same limitations and do not allow absolute measurement of the full extent of Dtot. According to a third aspect, it is sought to provide an inductive displacement sensor such that, for a given number N of 35 pairs of poles, for a given dimension Dtot of the secondary windings of the transducer, parallel to the degree of freedom of the sensor, the sensor is adapted to detect the position of the target relative to the transducer substantially over the entire extent Dtot of the transducer. In particular, in the case of an angular position sensor, it is sought to provide a sensor adapted to detect the position of the target relative to the transducer over a complete revolution, that is to say over an angular range of approximately 360 °, even when the number N of pairs of poles of the sensor is large, for example 1 14 and preferably 1 16. Fig. 23 is a front view schematically showing an example of an inductive multi-pole angular displacement sensor. In Figure 23, only the target of the sensor has been shown.
[0044] The target of the sensor of FIG. 23 comprises, as in the example of FIG. 3B, N conductive patterns 117i (N = 6 in the example shown) regularly distributed along the 360 ° of a first circular annular strip 118 of the target. Each conductive pattern 117i has the shape of a portion or sector of the first annular strip 118, of angular aperture aN approximately equal to Dtot / 2N = 360 ° / 2N, two consecutive patterns 117i being separated by a sector of the first annular band 118, substantially of the same angular aperture aN. The target of the sensor of FIG. 23 further comprises N + 1 conductive patterns 119i, with j integer ranging from 1 to N + 1, regularly distributed along the 360 ° of a second circular annular band 120 of the target, concentric with the first band 118 and not superimposed on the first band 118. In the example shown, the second annular band has an inner radius 30 greater than the outer radius of the first annular band. Each conductive pattern 119i has the shape of a sector of the second annular band 120, of angular opening OEN + 1 approximately equal Dtot / 2 (N + 1) = 360 ° / 2 (N + 1), two conducting patterns 119i consecutive ones being separated by a sector of the second annular band 120, substantially of the same angle OEN + 1.
[0045] The transducer (not shown for simplification) of the sensor of Fig. 23 is in correspondence with the target shown, i.e. it comprises: one or more primary windings adapted to produce excitation magnetic in first and second circular annular bands of the transducer substantially identical to the first and second annular bands 118 and 120 of the target, intended to be positioned respectively facing the first and second annular bands 118 and 120 of the target; at least first and second secondary windings of electrical period Dtot / N (for example 360 ° / N in the example of an angular sensor), each having N turns of the same winding direction, in the form of opening sectors 15 angular aN of the first annular band of the transducer, evenly distributed along the first annular band of the transducer, or, alternatively, having 2N turns of alternating winding directions in the form of angular aperture sectors aN of the first annular band of the transducer, evenly distributed along the first annular band of the transducer; and at least third and fourth secondary windings of electrical period Dtot / (N + 1) (for example 360 ° / (N + 1)), each having N + 1 turns of the same direction of winding in the form of sectors of angular opening OEN + 1 of the second annular band of the transducer, regularly distributed along the second annular band of the transducer, or, alternatively, comprising 2 (N + 1) turns of the winding direction alternating in the form of angular aperture sectors OEN + 1 of the second annular band of the transducer, evenly distributed along the second annular band of the transducer. Preferably, in the first annular band, the second electric period secondary winding Dtot / N is substantially identical to the first winding and spatially shifted by one quarter electric period (Dtot / 4N) compared to the first winding, and in the second annular band, the fourth electric period secondary winding Dtot / (N + 1) is substantially identical to the third winding and spatially shifted by one quarter electric period (Dtot / 4 (N + 1)) by compared to the third winding. More generally, the transducer may comprise, in the first annular band, a plurality of secondary windings of electrical period Dtot / N, substantially identical to the first winding and spatially offset with respect to each other by a certain percentage of electrical period. and, in the second annular band, a plurality of electric period secondary windings Dtot / (N + 1), substantially identical to the third winding and spatially offset from each other by a certain percentage of electrical period. The operation of the sensor of FIG. 23 will now be described in relation to FIG. 24. Consider the (non-limiting) case where the transducer of the sensor comprises, in the first annular band of the transducer, a first pair of secondary windings. identical of electric period 360 ° / 2N, shifted spatially by a quarter of electric period, and, in the second annular band of the transducer, a second pair of identical secondary windings of electric period 360 ° / 2 (N + 1), spatially shifted by a quarter 25 of electrical period. As indicated above, this sensor is able to provide two sets of two distinct electromotive forces, from which a position estimate can be constructed respectively over a range of position equal to 360 ° / 2N and over a range of position equal to 360 ° / 2 (N + 1).
[0046] FIG. 24 is a diagram showing the evolution, as a function of the position of the target relative to the transducer, of the ON estimate (in solid line) of the position obtained from the electromotive forces measured at the terminals of the first couple. secondary windings, and estimate eN + 1 (in broken lines) of the position obtained from the electromotive forces measured across the second pair of secondary windings of the transducer. As shown in FIG. 24, when the angular position e of the target relative to the transducer varies from 0 ° to 360 °, the position estimation signal eN varies periodically between a low value substantially equal to 0 and a high value substantially equal to 1 (the position estimates are here standardized for the sake of simplification, the described embodiments being not limited to this particular case), with a period of variation equal to the electrical period of the first pair of secondary windings, that is to say to say equal to 360 ° / N = 60 ° for N = 6. In addition, the position estimation signal eN + 1 varies periodically between the low values 0 and high 1, with a period of variation equal to the electrical period of the second pair of secondary windings, that is to say to say equal to 360 ° / N + 151.4 ° for N = 6. By combining the levels of the position estimation signals eN and ON + 1, we obtain t two separate measurement scales on a complete sensor revolution, ie two different divisions of the same range of 360 °. The principle of a vernier applied to these two scales of angular measurement, that is to say the construction of the difference ON + 1-ON between the two estimates of standardized position eN + 1 and eN, makes it possible to estimate the position and / or displacement of the target relative to the transducer over the entire distance Dtot = 360 ° (i.e., one full revolution). More particularly, one of the position estimation signals, for example the eN signal, may be used to provide "fine" target traveling information in N angular ranges of restricted ranges to the 360 ° electrical period. / N, and the difference ON + 1-ON between the other position estimation signal (the signal eN + 1 in this example) and this signal can be used to provide a coarse absolute information of the position of the target on a complete turn. Under these conditions, the coarse absolute information makes it possible to adapt the fine information but limited angularly, in order to make an estimation of absolute and fine displacement over 360 °. An advantage of the sensor of FIG. 23 is that it makes it possible to benefit to a certain extent from the advantages of the multipole sensors, particularly in terms of robustness to positioning errors, while being adapted to provide measurements over an extended position range. compared to multipole sensors of the type described above. In general, it should be noted that the embodiment described above can be adapted to two signals ON 'and 6N2, N1 and N2 being different integers not necessarily having a unit difference. Under these conditions, a sensor characterized by N1 and N2 = N1 + 2, having an arrangement similar to the arrangement of the sensor of FIG. 23, makes it possible to extend the absolute measurement over a range Dtot / N = 180 °. More generally, a sensor characterized by Ni and N2 = Nl + r, with r positive integer strictly less than N1, allows under certain conditions to extend the absolute measurement over a range Dtot / k = 360 ° / r.
[0047] The sensor of Fig. 23, however, has several problems. In particular, the size of the sensor is increased compared to a sensor of the type described above. In fact, in the example of FIG. 23, the transducer surface "useful" for making a measurement is that of a circular annular band 25 approximately twice the width of the "useful" annular band of a transducer of the type described in connection with Figure 3A. Similarly, the "useful" target surface for making a measurement is that of an annular band about twice the width of the "useful" annular band of a target of the type described with reference to FIG. 3B. In addition, the realization of the primary is more complex than in the previous embodiments if it is desired to excite in a relatively uniform manner each of the annular bands of scale N and N + 1 of the sensor. In practice, it may be necessary to use three sets of separate turns to achieve the primary excitation winding. Fig. 25 is a front view schematically showing an example of an embodiment of an inductive displacement sensor. The sensor of FIG. 25 is a multi-pole sensor with two scales of N and N + 1 measurements, operating according to the principle of a vernier as described with reference to FIGS. 23 and 24. In FIG. 25, only the target of FIG. sensor has been shown.
[0048] The target of the sensor of Fig. 25 comprises a plurality of disjoint conductive patterns 127i distributed along the 360 ° of a circular annular band 130 of the target. As shown in FIG. 25, the pattern set formed by the conductive patterns 127i is non-periodic. The various conductive patterns 127i have the shape of angular sectors, of different angular openings, of the annular band 130 of the target, and are a priori irregularly distributed along the annular band 130. The pattern set formed by the patterns conductors 127i on the annular band 130 of the target corresponds to the (virtual) superposition of first and second sets of periodic conducting patterns of respective periodicities 360 ° / N and 360 ° / (N + 1). The first set of patterns comprises N elementary patterns 129i (in solid lines) regularly distributed along the annular band 130 of the target, each elementary pattern 129i having the shape of a sector of the annular band 130, of angular opening. approximately equal to 360 ° / 2N. The second set of patterns comprises N + 1 elementary patterns 131k (in broken lines) regularly distributed along the annular band 130, each elementary pattern 131k having the shape of a sector of the annular band 130, of angular opening approximately equal to 360 ° / 2 (N + 1). In other words, the conductive pattern surfaces of the target of FIG. 25 correspond to the accumulation or union of the surfaces of the conductive patterns of a first target of the type described in relation with FIG. 3B, electric period 360 / N, and a second similar target, having the same internal and external radii as the first target, but having an electric period 360 ° / (N + 1). The transducer (not shown for the sake of simplification) of the sensor of FIG. 25 is for example adapted to the conductive patterns of the target in a manner similar to that described in connection with the example of FIG. 23. it comprises for example: at least one primary winding adapted to produce an approximately uniform magnetic excitation in a circular annular band of the transducer substantially identical to the circular annular band 130 of the target, intended to be positioned facing the annular band 130 of target ; at least first and second secondary windings of 360 ° / N periodicity, spatially offset by an electric period fraction, extending along the circular annular band of the transducer; and at least third and fourth secondary windings of 360 ° / (N + 1) periodicity, spatially shifted by an electric period fraction, extending along the same annular band of the transducer. The inventors have found that although the 360 ° / N and 360 ° / (N + 1) electrical period conductive patterns overlap and short-circuit, and therefore the target has conductive patterns 127i. irregularly distributed over a complete 360 ° revolution, these patterns having residual angular apertures which may be different from the periodic angular apertures of the patterns of the sets of secondary windings of the transducer, the sensor of FIG. good performance, displacement measurements over the entire distance Dtot (that is to say on a complete turn) by a vernier type reading method similar or identical to the method described in relation to the figures 23 and 24.
[0049] An advantage of the sensor of FIG. 25 is that, due to the superposition of the respective electrical period patterns 360 ° / N and 360 ° / (N + 1), the size of the sensor can be reduced compared to a configuration of the type described in connection with FIG. 23. In addition, a single primary winding, for example of the type described in connection with FIG. 3A, is sufficient to generate a sufficiently uniform magnetic excitation for a good operation of the sensor. Fig. 26 is a front view schematically showing an alternative embodiment of the sensor of Fig. 25. In Fig. 26, only the target of the sensor has been shown. The target of the sensor of Fig. 26 comprises a plurality of disjointed conductive patterns 137i distributed along the 360 ° of a first circular annular band 138 or wide band of the target. The set of patterns formed by the patterns 137i on the annular band 138 of the target corresponds to the superimposition of first and second sets of periodic patterns of respective electric periods 360 ° / N and 360 ° / (N + 1). The first set of patterns 20 comprises N elementary conductor patterns 139i (in solid lines) evenly distributed along the first annular band 138 of the target, each elementary pattern 139i having the shape of an angular sector of the first annular band 138 of the target, of angular aperture approximately equal to a half electric period 360 ° / 2N. The second set of patterns comprises N + 1 elementary patterns 141k (in broken lines), regularly distributed along a second circular annular band 142 or narrow band of the target, concentric with the annular band 138 and included in the annular band 138 that is, having an inner radius greater than the inner radius of the first annular band, and / or an outer radius less than the outer radius of the annular band 138. Each elementary pattern 141k has the shape of an angular sector of the annular band 142 of the target, with an angular aperture of approximately 360 ° / 2 (N + 1). The width (radial dimension) of the second annular band 142 of the target is preferably substantially less than the (radial) width of the first annular band 138 of the target, for example two to twenty times smaller than the width. of the first annular band (the wide band).
[0050] The transducer (not shown for the sake of simplification) of the sensor of FIG. 26 is for example adapted to the conductive patterns of the target in a manner similar to that described with reference to the examples of FIGS. 23 and 25. In particular, it comprises for example: at least one primary winding adapted to produce an approximately uniform magnetic excitation in a first circular annular band of the transducer (wide band) substantially identical to the first annular band 138 of the target, intended to be positioned opposite the the first circular annular band of the target; at least first and second secondary windings of 360 ° / N periodicity, spatially shifted by an electric period fraction, extending along the first circular annular band of the transducer (the wide band); and at least third and fourth secondary windings of 360 ° / (N + 1) periodicity, spatially offset by a fraction of an electrical period, arranged along a second circular annular band of the transducer (narrow band), substantially identical to the second annular band 142 of the target and intended to be positioned facing the annular band 142 of the target. The operation of the sensor of FIG. 26 is similar to that of the sensor of FIG. 25. Preferably, in the sensor of FIG. 26, the secondary winding or windings 30 carrying out the "fine" measurement as described above, are the windings. whose turns have the shape of angular sectors of the widest annular band of the transducer (substantially identical to the annular band 138 of the target). It is understood by the notion of fine measurement that the priority of the design efforts is attributed to ensuring performance and robustness to the measurement carried out by the secondary of the broadband, possibly and in a further way. to some extent, at the expense of the performance and robustness of the measurement made by the narrow-band
[0051] An additional advantage of the sensor of Fig. 26 with respect to the sensor of Fig. 25 is that it is more robust to positioning errors between the target and the transducer than the sensor of Fig. 25. In particular, the measurement obtained at Figs. terminals of the secondary windings of the broadband 10 (preferably associated with the fine measurement) is more robust to the positioning errors between the target and the transducer than in the sensor of FIG. 25. Indeed, in the sensor of FIG. 26 , reducing the area of one of the measurement scales relative to the other makes it possible to reduce to a certain extent the coupling created by the patterns of the narrow band on the patterns of the broadband at the level of the target, in particular with respect to the target of FIG. 25 for which the reciprocal influence of one set of patterns on the other is substantially equivalent and very strong. It is thus possible to increase the robustness of one of the sets of secondary to positioning errors. Note that in the example shown, the average radius of the second circular annular band of the sensor (the narrow band) is approximately equal to the average radius of the first circular annular band of the target (the wide band). This configuration is advantageous because it allows substantially equivalent distance away from the effects of the inner and outer orthordial portions of the conductive patterns. The described embodiments are however not limited to this particular configuration. FIGS. 27A to 27C are front views schematically showing another alternative embodiment of the sensor of FIG. 25. More particularly, FIG. 27A is a front view of the target, FIG. 27B is a front view of FIG. a portion of the transducer, and Fig. 27C is a front view of another portion of the transducer. In practice, the two parts of the transducer shown separately in FIGS. 27B and 27C for illustrative purposes, are integrally and concentrically superimposed in one and the same transducer, without the decomposition of the constituent elements of said transducer on these transducers. two figures do not presage a particular distribution on several levels of metallization. The sensor target of Figs. 27A-27C comprises a plurality of disjointed conductive patterns 147i distributed along 360 ° of a first circular annular band 148 or wide band of the target. The set of patterns formed by the conductive patterns 147i on the first annular band 148 corresponds to the superposition of a first set of periodic patterns of electric period 360 ° / N, and second and third sets of periodic patterns of electrical periods 360 ° / (N + 1). The first set of patterns comprises N conductive patterns 149i (in solid lines) evenly distributed along the annular band 148 of the target (wide band), each elemental pattern 149i having the shape of a sector 20 of the band 148, d angular aperture approximately equal to 360 ° / 2N. The second set of patterns comprises N + 1 elementary conductor patterns 151k (in broken lines), regularly distributed along a second annular band 152 of the target (narrow band), concentric with the first annular band 148 and included in FIG. strip 148, ie having an inner radius greater than the inner radius of the annular band 148, and an outer radius smaller than the outer radius of the annular band 148. In this example, the inner radius of the annular band 152 of the The target is greater than the average radius of the first annular band 148. This exemplary embodiment is in no way limiting, and in particular the narrow strips 152 and 154 may be arranged differently in the wide band 148, without the average radius of the wide band 148 is an impassable limit for one or the other of the narrow bands.
[0052] Each elemental pattern 151k has the shape of a sector of the second annular band 152 of the target, having an angular aperture of approximately 360 ° / 2 (N + 1). The (radial) width of the annular band 152 of the target is preferably small relative to the width of the annular band 148 of the target, for example, three to twenty times smaller than the width of the first band. The third set of patterns comprises N + 1 elementary conductor patterns 153k (in broken lines), regularly distributed along a third annular band 154 of the target (narrow band), concentric with the annular band 148 and included in the band In this example, the outer radius of the annular band 154 of the target is less than the average radius of the annular band 148. The difference between the mean radius of the first annular band 148 and the average radius of the third annular band 154 is for example approximately equal to the difference between the average radius of the second annular band 152 and the average radius of the first annular band 148. Each elemental pattern 153k has the shape of a sector of the third annular band 154 of the target, of angular aperture approximately equal to 360 ° / 2 (N + 1). The width of the third annular band is for example approximately equal to the width of the second annular band. Alternatively, the width of the third annular band 154 is such that the area of a pattern of the annular band 154 is approximately equal to the area of a pattern 25 of the annular band 152. These two exemplary embodiments are in no way limiting. As shown in FIG. 27A, the periodic patterns of 360 ° / (N + 1) periodicity of the annular band 154 of the target are spatially shifted 360 ° / 2 (N + 1) with respect to the periodicity periodic patterns. 360 ° / (N + 1) of the annular band 152 of the target. Thus, in the "empty" angular aperture ranges 360 ° / (N + 1) separating two adjacent elementary conductor patterns 151k, approximately one elemental pattern 153k extends, and in the "empty" angular ranges 360 ° / (N + 1) angular aperture separating two adjacent 153k elementary conductive patterns extends approximately an elemental conductor pattern 151k. In other words, substantially all the radial directions of the target intersect an elemental conductive pattern 151k or an elemental pattern 153k.
[0053] The transducer of the sensor of FIGS. 27A to 27C is for example adapted to the conductive patterns of the target in a manner similar to that described with reference to the examples of FIGS. 23, 25 and 26. It comprises for example: at least one primary winding 211 (FIG. 27B) adapted to produce an approximately uniform magnetic excitation in a first annular band of the transducer substantially identical to the first annular band 148 of the target, intended to be positioned facing the annular band 148 of the target; At least first and second secondary windings 243 (only one secondary winding 243 has been shown in FIG. 27B) with an electric period 360 ° / N, each having N turns having the same winding direction or, alternatively, 2N turns of alternating winding direction, each turn of the first and second secondary windings having the shape of a 360 ° / 2N angular aperture sector of the first annular band of the transducer, and the N or 2N turns of each winding being regularly distributed along the 360 ° of the first annular band of the transducer; At least third and fourth secondary windings 253 (only one secondary winding 253 has been shown in FIG. 27C) of periodicity 360 / (N + 1), each having N + 1 turns having the same winding direction or, preferably , 2 (N + 1) alternating turns of winding direction, each turn of the third and fourth secondary windings having the shape of a 360 ° / 2 (N + 1) angular aperture sector of a second annular band the transducer, substantially identical to the second annular band 152 of the target and intended to be positioned opposite the band 152 of the target, the N + 1 or 2 (N + 1) turns of each winding being regularly distributed 3031589 B13316 73 along the 360 ° of the second annular band of the transducer; and at least fifth and sixth secondary windings 255 (only one secondary winding 255 has been shown in FIG. 27C) of periodicity 360 ° / (N + 1), each having N + 1 turns of the same winding direction or, preferably, 2 (N + 1) turns of alternating winding direction, each turn of the fifth and sixth secondary windings having the shape of a 360 ° / 2 (N + 1) angular aperture sector of a third annular band of the transducer, substantially identical to the third annular band 154 of the target and intended to be positioned facing the annular band 154 of the target, the N + 1 or 2 (N + 1) turns of each winding being regularly distributed along the 360 ° of the third annular band of the transducer. The third and fifth secondary windings are of opposite polarities, that is to say they are spatially shifted by 360 ° / 2 (N + 1) according to the polarity convention (represented by a + or - sign) established on Figure 7 and 20 repeated in the following description. The fourth and sixth secondary windings are arranged relative to one another in an arrangement substantially identical to the arrangement between the third and fifth secondary windings. Preferably, in the first circular annular band 25, the first and second secondary windings are spatially offset 360 ° / 2N relative to each other, in the second circular annular band, the third and fourth secondary windings are offset spatially 360 ° / 2 (N + 1) relative to each other, and in the third circular annular band 30, the fifth and sixth secondary windings are shifted 360 ° / 2 (N + 1) 1 one with respect to the other. More generally, the transducer may comprise, in the first annular band, a plurality of secondary windings of electrical period Dtot / N, substantially identical to the first secondary winding and spatially offset with respect to one another by a fraction. electric period; in the second annular band, a plurality of electric period secondary windings Dtot / (N + 1), substantially identical to the third secondary winding and spatially offset relative to one another by an electric period fraction; and in the third annular band, a plurality of electrical period secondary windings Dtot / (N + 1) substantially identical to the fifth secondary winding and spatially offset relative to each other by an electric period fraction. The operation of the sensor of Figs. 27A-27C is similar to that of the sensor of Figs. 25 and 26. Various read patterns may be implemented in the example of Figs. 27A through 27C. The inventors have found in particular that: the reading of the set of patterns 147i by a secondary winding 243 generates a usable useful signal, of electric period 360 ° / 2N; reading the set of patterns 147i by a secondary winding 253 generates a usable useful signal, of electric period 360 ° / 2 (N + 1); reading the set of patterns 147i by a secondary winding 255 generates a usable useful signal, of electric period 360 ° / 2 (N + 1); A combination of the simultaneous readings of the pattern set 147i by a secondary winding 253 and a secondary winding 255, for example when the two secondary ones are of alternating polarities (as shown in FIG. 27C) and electrically connected in series, generates a signal 30 usable, electric period 360 ° / 2 (N + 1) and amplitude approximately equal to twice the useful signal read by the secondary winding 253 or useful signal read by the secondary winding 255; the reading of the set of patterns 147i by a secondary winding 243 generates a parasitic signal (in particular of 360 ° / (N + 1) and 360 ° periodicity) relatively low relative to the useful signal picked up by this secondary winding; a combination of the simultaneous readings of the pattern set 147i by a secondary winding 253 and a secondary winding 255, for example when the two secondary ones are of alternating polarities (as shown in FIG. 27C) and electrically connected in series, generates a signal parasite (including 360 ° / N and 360 ° periodicities) relatively low compared to the useful signal captured by this secondary winding. An additional advantage of the sensor of Figs. 27A-27C is that it is even more robust to positioning errors between the target and the transducer than the sensor of Fig. 26.
[0054] In particular, the measurement obtained across the secondary windings 243 of the wide band (preferably associated with the fine measurement) is more robust to the positioning errors between the target and the transducer than in the sensor of FIG. in the sensor of Figs. 27A-27C, substantially all the radial directions of the target intersect with one and only one narrow band elementary conductive pattern disposed on either of the two narrow bands of the target. In addition, the two narrow bands of the target are preferably disposed sufficiently far from the two inner and outer orthoradial branches of the secondary 243 of the broad band of the transducer. Under these conditions, the coupling of the conductive patterns of the two narrow bands of the target to the measurement across the broadband secondaries 243 results from the combination of the induction of the narrow band conductive patterns of the target and induction of the conductive patterns of the other narrow band of the target, these two contributions compensating substantially regardless of the position of the target relative to the transducer. The parasitic coupling then takes a relatively stable value as the position of the target relative to the transducer changes. In addition, the coupling takes a substantially zero value when the secondaries of the broadband comprise 2N alternating turns of winding direction, as described for the sensor of FIG. 3 for example, in order to realize a spatially differential measurement. Another formulation is to consider that the secondary broadband transducer "roughly" sees the two narrow bands shifted as a single narrow and substantially full conductive medium band or continues on Dtot electromagnetically (and not at all). electrical sense), and that this virtual band 10 actually induces at the terminals of said secondary a signal substantially independent of the position. Moreover, the inventors have found that the measurement obtained at the terminals of the secondary winding 253 (of a narrow band) exhibits a behavior as a function of the position of the target relative to the transducer which is similar to the behavior as a function of the position of the measurement obtained at the terminals of the secondary winding 255 (of the other narrow band). The inventors have also found that, in the event of positioning defects of the target with respect to the transducer, the behavior as a function of the position of the measurement at the terminals of one of the two windings 253 or 255 of one of the two bands narrow, presents relatively complementary deformations of the deformations obtained on the measurement at the terminals of the other winding. Thus, by combining the measurements of the two secondary of the two narrow bands, and preferably by connecting in series the two windings if they are designed to exhibit a relatively similar behavior in terms of amplitude and linearity in particular it is possible to obtain a measurement at the terminals of the new composite winding 30 which is relatively robust to the positioning defects. In fact, in the sensor of FIGS. 27A to 27C, substantially all the radial directions of the transducer intersect exactly two elementary windings of the composite winding, of opposite polarity and alternately arranged on each of the two narrow strips of the transducer. In addition, the two narrow strips of the transducer are disposed sufficiently far from the two inner and outer orthoradial branches of the conductors of the broad band of the target. Under these conditions, the coupling of the target wide band conductor patterns 149i to the measurement across the composite winding results from the combination of the induction of the conductive patterns 149i on the secondary 253 (a narrow band) and induction of the conductive patterns 149i on the secondary 255 (the other narrow band), these two contributions substantially compensating regardless of the position of the target relative to the transducer. The parasitic coupling then takes a relatively stable value when the position of the target relative to the transducer changes. In addition, the coupling takes a substantially zero value when the secondary 253 and 255 (narrow strips) comprise 2 (N + 1) turns 15 of alternating winding direction, as has been described for the sensor of FIG. example, to perform a spatially differential measurement. Another formulation is to consider that as the position of the target relative to the transducer changes, a secondary reading of the transducer's narrow band of conductive pattern play associated with it on the target is substantially "in phase. "with the reading made by the secondary of the other narrow band of the transducer of the set of conductive patterns associated with it on the target. On the other hand, and as the position of the target relative to the transducer changes, a secondary reading of the narrow band of the transducer of the set of conductive patterns 149i of the wide band of the target is substantially "out of phase" with the secondary reading of the other narrow band of the transducer of the same set of conductive patterns of the broad band of the target. Thus, when the two measurements are added by mathematical or electrical means (for example by a series electrical connection), parasitic coupling takes a substantially zero value when the secondary elements of each narrow band are designed for this purpose, whereas the useful signal 35 is conserved and / or amplified.
[0055] It will be noted that in the case of the series electrical connection of the secondary winding of a narrow band with the secondary winding of the other narrow band, and in order to recover the characteristics of the sensors described in connection with FIG. 2E, it is for example possible to choose for midpoint of the composite winding the series connection point of the two elementary windings. It will be appreciated that other methods of combining the measurements of the two narrow-band side-channels, such as linear combinations of the separately packaged signals, or other methods of connecting the secondary ones to one another with each other, can be provided. For the same purpose, the increase in the robustness of the measurements at the wide band and / or the narrow bands of the transducer, the defects in the positioning of the target with respect to the transducer can be used. It will be noted that in the examples shown in FIGS. 23, 25, 26 and 27A, one of the elementary electric period patterns 360 ° / (N + 1) is approximately centered on the same angular position as one of the elementary patterns. of period 20 electric 360 ° / N. For example, in FIG. 25, the pattern 1311 is centered on the same angular position as the pattern 1291, and in FIG. 27A, the pattern 1511 is centered on the same angular position as the pattern 1491. This configuration is preferential because it contributes to increase the overall symmetry level of the sensor, which makes it possible in particular to facilitate the manufacture and visual control of the target, or to facilitate the design and manufacture of sets of secondary windings. The described embodiments are however not limited to this particular case.
[0056] In general, it will be recalled that the embodiments described above can be adapted to two signals 6N1 and 6N2, N1 and N2 being different integers but their difference is not necessarily unitary. Under these conditions, a sensor characterized by N1 and N2 = N1 + 2 and of similar arrangement to the arrangement of the sensors of FIGS. 3031589 B13316 79 23, 25, 26 and 27A to 27C, makes it possible to extend the absolute measurement over a range Dtot / N = 180 °. More generally, a sensor characterized by N1 and N2 = N1 + r, with a positive integer and strictly less than N, allows under certain conditions 5 to extend the absolute measurement over a range Dtot / r = 360 ° / r. In addition, as an alternative, in the examples of FIGS. 26 and 27A to 27C, instead of reducing the width of the patterns of periodicity 360 ° / (N + 1) with respect to the width of the units of periodicity 360 ° / N it will be possible to reduce the width of the patterns of 360 ° / N periodicity with respect to the width of the patterns of 360 ° / 2 (N + 1) periodicity. Furthermore, it should be noted that the number of pairs of poles is preferably even for the broadband patterns, in order to benefit from increased symmetry of the transducer on both sides of the midpoint (especially when the transducer is realized according to the second aspect). Furthermore, it will be appreciated that the embodiments described in connection with Figs. 23 to 27C do not apply only to planar angular displacement sensors, but may be applicable to other types of inductive displacement sensors, and in particular planar linear displacement sensors, or non-planar angular displacement sensors, for example linear "wound" displacement sensors (for example formed according to a cylinder) around and facing a rotating part on which is fixed a target also of linear type and "wound" (for example shaped according to a cylinder). These two embodiments are in no way limiting. Fourth aspect Generally, the target of an inductive displacement sensor consists of a metal plate cut over its entire thickness in order to keep, opposite the windings of the transducer, only portions of the plate corresponding to the conductive patterns of the target. as shown for example in FIG. 50 of the aforementioned EP0182085 patent. Alternatively, the target may be constituted by a dielectric support, for example a plastic plate, a side facing the transducer is partially coated with a metal layer forming the conductive pattern or patterns of the target.
[0057] Targets of the aforementioned type, however, have points of weakness, which can be problematic in some applications, including applications in which the moving parts whose displacement is desired to be detected are susceptible to severe shocks or vibrations.
[0058] Among these points of weakness, the inventors have in particular identified the conductive patterns when they are relatively thin and / or angular, and the dielectric support which is generally soft (PCB epoxy, plastic. "). A robust fastening between the target and a moving part whose displacement is desired to be able to detect may cause difficulties.This fixation (for example by gluing, screwing, fitting, etc.) may in particular constitute a point of mechanical weakness. points of weakness limit the industrial applications of sensors equipped with such targets, and in particular oblige either to instrument the rotating mechanical part subsequent to the assembly operations of said part especially when these assembly operations are carried out using force tools such as mallets and presses, or to protect the target and / or the transducer in a solid mechanical case. For example the case of instrumented bearings which are embedded in the means of presses large tonnage. According to a fourth aspect, it would be desirable to have a target for an inductive displacement sensor that overcomes all or part of the disadvantages of existing targets, particularly in terms of solidity. For this, according to a fourth embodiment, provision is made for a target for an inductive displacement sensor, formed of a single conductive metal part (for example a piece of steel), or monoblock target, machined so that the The transducer face of the transducer target has one or more metal studs protruding from a bottom metal wall. The target or pads of the target correspond to the conductive pattern or the conductive patterns of the target, and the portions of the bottom wall not surmounted by a stud correspond to zones without a conductive pattern of the target, that is to say say usually non-conductive areas in traditional targets for inductive displacement sensor. Fig. 28 is a perspective view showing an exemplary embodiment of such a monoblock target 301 for an inductive displacement sensor. The target 301 has the general shape of a metal disc, machined so that a face of the disc intended to be turned towards the transducer has N conductive pads 307i (N = 6 in the example shown) of substantially the same height, in protruding from a bottom wall 309 approximately flat. Each pad 307i has an apex or an upper surface approximately flat and parallel to the wall 309. In addition, in this example, the side walls of the studs are approximately orthogonal to the wall 309. The upper faces of the studs 307i of the target 301 define the conductive patterns of the target.
[0059] In this example, the target 301 has a conductive pattern substantially identical to that of the target of FIG. 3B, that is to say that, when projected in a direction orthogonal to the mean plane of the disk, the pads 307i have substantially the same and are arranged in substantially the same manner as the conductive patterns 117i of the target of FIG. 3B. The operating principle of the target 301 is similar to what has been described previously, ie when the target is placed in front of a transducer emitting a magnetic excitation, induction phenomena, for example eddy currents. , occur in the pads 307i, especially at the upper face of the pads, causing a variation of a transducer output signal level depending on the position of the pads 307i relative to the transducer.
[0060] It will be noted that in the target 301, the portions of the surface of the target opposite the transducer located between the pads 307i are conductive. Therefore, under the effect of the magnetic excitation generated by the primary winding, induction phenomena, for example eddy currents, can also occur in these portions of the target, at the Background 309. More generally, and for example in the case of the sensor of FIG. 28 where the pads are in uniform electrical contact with the support of the target characterized by the wall 309, the electromagnetic field distribution results from the global interaction of the conductive structure of the target with the magnetic excitation generated by the primary. In particular, there are electromagnetic phenomena associated with the overall conductive structure of the target rather than with that of each conductive pad, for example the circulation of an induced current substantially in a concentric loop to the axis of rotation of the target. , rather than according to local loops substantially delimited by the surfaces of the pads 307i or by the surface portions of the wall 309 which are between the studs. It will be noted in particular that in the state of the art, it is agreed to move the bottom wall 309 as far as possible and to electrically isolate the pads 307i in order to avoid these parasitic induction phenomena. However, since the distance between the transducer and the wall 309 is greater than the distance between the transducer and the pads 307i, the induction phenomena occurring in the wall 309 are smaller than the induction phenomena occurring at the surface. studs 307i. The tests carried out by the inventors have shown that the inductive contribution of the wall 309 may possibly cause a modification such as attenuation or a modification of the linearity characteristics of the useful output signal of the transducer when the height of the pads 307i is small, however, it does not degrade the accuracy of the position measurements that can be made by the sensor.
[0061] It will be recalled that according to the first aspect, described in particular with reference to FIGS. 12A to 12D, it is possible to provide, by geometric adjustments of the target and in particular by adjusting the height of the studs 307i in the sensor of FIGS. Figure 28, to adjust the optimal dopt target-transducer distance in terms of linearity. Thus, the height of the pads can be chosen so that the distance Dopt is compatible with the intended application, for example between 0.5 and 1.5 mm, which is a range of values compatible with various industrial applications. By way of nonlimiting example, the height of the pads 307i is between 0.1 and 30 mm and preferably between 1 and 10 mm. More generally, any type of target for an inductive displacement sensor with one or more conductive patterns can be made in one-piece form, as described with reference to FIG. 28, for example targets for inductive sensor for linear displacement, or even targets for planar angular displacement inductive sensor having conductive patterns different from that of FIG. 28, that is to say for example different from angular sectors or rectangles, and for example characterized in that at least one of their contours (for example the outer contour) evolves substantially as a spiral as a function of the angle on the target, or in that at least one of their contours evolves substantially sinusoidally as a function of the angle on the target. By way of illustration, another nonlimiting example of a single-piece target 401 for an inductive sensor for planar angular displacement is shown in FIG.
[0062] As in the example of FIG. 28, the target 401 has the general shape of a metal disk, machined such that a face of the disk intended to be turned towards the transducer comprises conductive pads 407 of substantially the same height, projecting from an approximately planar bottom wall 309. As before, each stud 407 has an apex or an upper surface 3031589 B13316 84 approximately parallel to the wall 309, and the side walls of the studs are approximately orthogonal to the wall 309. The upper faces of the studs 407 of the target 401 define the conductive patterns of the target. In this example, the target 401 has conductive patterns substantially identical to those of the target of FIG. 27A, that is to say that, seen from above, the pads 407 have substantially the same shape and are arranged substantially of the same shape. way that the conductive patterns 147i of the target of Figure 27A.
[0063] The production of monobloc targets of the aforementioned type can be carried out by any known means for machining a solid metal part, for example by etching, by sintering, by molding, by stamping, etc. An advantage of monoblock targets of the type mentioned above is that they are particularly robust with respect to existing targets, and can thus be manipulated without particular precautions. This robustness results in particular from the fact that such targets are massive and have no apparent points of weakness. In addition, these targets are easier to securely attach to moving parts than existing targets. In particular, all metal-on-metal and / or metal-to-metal bonding techniques can be used. Both of these features make it possible to pre-instrument a very large majority of the rotating metal parts even before they are mounted or used in the host system. To finalize the instrumentation of the system, it is then sufficient to report the transducer in front of the mounted target, either at the end of assembly or at any time in the life cycle of the host system. According to a particularly advantageous embodiment, a single-piece target for an inductive displacement sensor of the type described above can be machined directly in a metal part whose position (and / or displacement) is to be detected, for example: angular measurement, a steering column of a motor vehicle, a shaft of a motor or speed reduction box (for example at a disc-shaped face of an end section of a motor vehicle), shaft), a rotating ring (inner or outer) of a ball bearing, a gear, etc. ; or 5 for a linear measurement, the rod of a piston, the body of a damper, etc. Various examples and embodiments with various variants have been described above. It will be appreciated that those skilled in the art will be able to combine various elements of these various examples, embodiments and variants without demonstrating inventive step. It will be noted in particular that the first, second, third and fourth embodiments described above can be implemented independently of one another or combined in whole or in part according to the needs of the application.

权利要求:
Claims (12)
[0001]
REVENDICATIONS1. Target (301; 401) for an inductive displacement sensor, said target being formed of a single conductive metal part machined so that a face of the target intended to be turned towards a transducer of an inductive displacement sensor comprises one or several metal studs (307i; 407) projecting from a wall (309) of said piece.
[0002]
The target (301; 401) of claim 1, wherein the entire surface of the target to be turned towards the transducer is metallic.
[0003]
3. Target (301; 401) according to claim 1 or 2, comprising several pads (307i; 407) of substantially the same height.
[0004]
4. Target (301; 401) according to any one of claims 1 to 3, wherein the height of the or pads (307i, 407) is between 0.1 and 30 mm.
[0005]
A target (301; 401) according to any one of claims 1 to 4, wherein each stud (307i; 407) has an upper face parallel to the wall (309).
[0006]
The target (301; 401) of any one of claims 1 to 5, wherein the wall (309) is approximately planar.
[0007]
A target (301 401) according to any one of claims 1 to 6, wherein said part is generally disk-shaped, and has a plurality of studs (307i, 407) distributed along a circular annular band. on the side of one side of the disc.
[0008]
A target according to any one of claims 1 to 6, wherein said part is generally rectangular in shape and has a plurality of studs distributed along a rectangular strip on the side of a face of the plate. .
[0009]
The target (301; 401) according to any one of claims 1 to 7, wherein said metal part is a part of a drive shaft or transmission shaft of a gearbox. 3031589 B13316 87
[0010]
The target (301; 401) according to any one of claims 1 to 7, wherein said metal part is a part of a motor vehicle steering column.
[0011]
The target (301; 401) of any one of claims 1 to 8, wherein said metal part is a part of a piston rod.
[0012]
12. Target (301; 401) according to any one of claims 1 to 7, wherein said metal part is integral with a ring of a ball bearing.

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同族专利:

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公开号 | 公开日

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MX2017009158A|2018-03-06|

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FR3031589B1|2018-11-16|

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CN107407692B|2019-10-22|

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JP2018508759A|2018-03-29|

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US20180274591A1|2018-09-27|

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US10480580B2|2019-11-19|

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ES2817124T3|2021-04-06|

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CN107407692A|2017-11-28|

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JP6619440B2|2019-12-11|

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CA2973053A1|2016-07-21|

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BR112017014936A2|2018-03-13|

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HK1245392A1|2018-08-24|

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KR20170118725A|2017-10-25|

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DK3245485T3|2020-09-14|

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WO2016113501A1|2016-07-21|

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EP3245485B1|2020-06-17|

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EP3245485A1|2017-11-22|

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法律状态:
2016-01-28| PLFP| Fee payment|Year of fee payment: 2 |

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2016-07-15| PLSC| Publication of the preliminary search report|Effective date: 20160715 |

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2016-12-23| PLFP| Fee payment|Year of fee payment: 3 |

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2017-06-16| TP| Transmission of property|Owner name: HUTCHINSON, FR Effective date: 20170517 |

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2017-12-29| PLFP| Fee payment|Year of fee payment: 4 |

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2018-12-24| PLFP| Fee payment|Year of fee payment: 5 |

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2019-12-23| PLFP| Fee payment|Year of fee payment: 6 |

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2020-12-23| PLFP| Fee payment|Year of fee payment: 7 |

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2021-12-22| PLFP| Fee payment|Year of fee payment: 8 |

优先权:

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申请号 | 申请日 | 专利标题

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FR1550232|2015-01-13|

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FR1550232A|FR3031589B1|2015-01-13|2015-01-13|INDUCTIVE DISPLACEMENT SENSORS|FR1550232A| FR3031589B1|2015-01-13|2015-01-13|INDUCTIVE DISPLACEMENT SENSORS|

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BR112017014936-2A| BR112017014936A2|2015-01-13|2016-01-13|bearing comprising an angular displacement sensor|

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PCT/FR2016/050055| WO2016113501A1|2015-01-13|2016-01-13|Bearing comprising an angular movement sensor|

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JP2017537242A| JP6619440B2|2015-01-13|2016-01-13|Bearing with angular displacement sensor|

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HK18102835.5A| HK1245392A1|2015-01-13|2018-02-27|Bearing comprising an angular movement sensor|