MOTOR WITHOUT BRUSH

专利摘要:
magnet-assisted reluctance motor rotor, and brushless motor. [problem] improving the output while still reducing the edge torque and torque oscillation in a well balanced way in a magnet assisted reluctance motor. [solution] a rotor 3 is used for a magnet assisted reluctance motor in which the rotor is rotated by reluctance torque and magnetic torque. rotor 3 includes pole s and pole n 26s and 26n magnets, which are arcuate in cross section. each pole has three 26s magnets or three 26n magnets. each magnet is embedded in the rotor 3 in such a way that a convex side portion of the magnet faces the center or the rotor. the distance rs between the center of the circular arcs of the pole magnets 26s and the center or of the rotor 3 is different from the distance rn between the center n of the circular arcs of the pole magnets n 26n and the center of the rotor 3 (rs (different) rn). the ratio of the two distances is 0.92 (rs / rn = 0.92). an outer peripheral section 41 of a pole magnet s of the innermost layer 26s is arranged in such a way as to protrude from a pole zone s1 or s2 in an adjacent pole zone n1 or n2.
公开号:BR112015003256B1
申请号:R112015003256-7
申请日:2013-08-10
公开日:2021-03-30
发明作者:Masayuki Okubo；Keisuke MITSUOKA；Masaru Watanabe
申请人:Mitsuba Corporation；
IPC主号:

专利说明:

FIELD OF THE INVENTION
[001] The present invention relates to a brushless motor in which a rotor is rotated by the reluctance torque and, in particular, to the configuration of a rotor used in a magnet assisted reluctance motor in which the rotor rotation is assisted by magnetic force of a magnet embedded in the rotor. BACKGROUND OF THE INVENTION
[002] As an electric motor of a type that generates a rotational force using a difference in magnetic resistance between a stator and a rotor, a reluctance motor has been known. In the reluctance motor, reluctance torque generated by the difference in magnetic resistance is used to rotate the rotor. However, since the reluctance torque is less than the torque obtained by a magnet, compared to a motor of the same physical structure that uses a magnet, the output torque of the reluctance motor tends to be less. Therefore, the problem is that, in order to achieve a desired torque with the reluctance motor, the structure of the motor becomes larger.
[003] In recent years, a magnet-assisted reluctance motor has been proposed, with a magnet being arranged on a rotor in the basic configuration of a reluctance motor. For example, patent document 1 discloses a magnet-assisted reluctance motor like this, and shows a magnet embedded in a rotor of the reluctance motor. In the case of the engine of patent document 1, in one of the magnetic poles, that is, pole N or S, of a rotor core, a first permanent magnet is embedded, which has a high magnetic flux density and is made of the same material of magnet and that has the same shape. In the other magnetic pole, a second permanent magnet is embedded, which is different from the first permanent magnet. The second permanent magnet is made of the same magnet material that has a low magnetic flux density. According to this configuration, the reluctance motor uses assistance from the magnetic force of the magnet and rotates the rotor with both the reluctance torque and the magnetic torque, thereby leading to both an improvement in output and a reduction in motor size. PREVIOUS TECHNOLOGY DOCUMENTS PATENT DOCUMENTS - [Patent Document 1] Japanese Patent No. 3,818,340 - [Patent Document 2] Publication of Japanese Open Patent Application No. 2011-83066 SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION
[004] However, the problem with the magnet-assisted reluctance motor is that, due to the use of the magnet, there is an edge effect, which a reluctance motor has not experienced. In addition, even in the magnet-assisted reluctance motor, as in the case of a normal magnet-assisted reluctance motor, a torque fluctuation, or a fluctuation in torque when being driven, is a problem. That is, in the reluctance motor, the reluctance torque varies with the rotation of the rotor, thereby causing a torque oscillation as the rotor is rotated.
[005] In particular, when the magnet-assisted reluctance motor is used as a motor for an electrically assisted steering device, the effect of the motor edge on the electrically assisted steering device needs to be reduced due to a flywheel encountering difficulty returning to the original position because of the edge effect. Another problem is that the torque fluctuation makes the steering feel worse in the electrically assisted steering device, and makes a driver feel frustrated. In terms of comfortable driving, the magnet-assisted reluctance motor needs to reduce torque oscillation.
[006] In addition, in the engine of patent document 1, compared to the case where rare earth magnets are used for both pole N and S, the motor has a lower magnetic flux density, and the touch of the motor is less. However, if an attempt is made to obtain the same characteristics as when rare earth magnets are used for both pole N and S using the configuration of patent document 1, the problem arises that the motor structure gets larger, and that the oscillation of torque and edge effect increases in this way.
[007] As for torque oscillation, for example, in the case of patent document 2, a closed stator structure is adopted in which the stator ends are connected together in order to make the fluctuation in the reluctance torque less and reduce torque oscillation. However, even if the closed stator structure is adopted, the magnetic flow of the stator is polarized in the motor in which a rotor core outside a magnet becomes a magnetic path when current is being applied, and the torque oscillation inevitably remains . Especially, in the case of the magnet-assisted reluctance motor, the reluctance torque ratio is large, and the problem therefore is that the impact of the torque oscillation is large. MEANS TO SOLVE THE PROBLEMS
[008] A rotor of the present invention used in a magnet assisted reluctance motor, which includes a stator which includes windings of a plurality of phases, and a rotor which is arranged within the stator in a rotatable manner and which includes a plurality of internal mounting holes in which a plurality of permanent magnets are embedded, in which the direction of magnetic flux formed by each of the magnetic poles of the plurality of permanent magnets is established as geometric axis d, a geometric axis that is magnetically orthogonal to the axis geometric d is established as the geometric axis q, a plurality of the geometric axes of q is alternately provided in a circumferential direction in the rotor, and the rotor is rotated by the reluctance torque generated by a difference in the magnetic resistance between the directions of the geometric axis of the axis geometric qe by the magnetic torque generated by the permanent magnets, it is characterized in that: the plurality of permanent magnets i includes permanent magnets that are of arcuate cross section and form a first magnetic pole that is pole N or S, and permanent magnets that are of arcuate cross section and form a second magnetic pole that is of different polarity from the first magnetic pole; each of the permanent magnets that form the first and second magnetic poles is embedded in the rotor in such a way that a convex side portion of the same faces the center of the rotor; and, when a cross section of the rotor is equally divided into regions to which each of the geometrical axes d belongs with respect to each of the geometrical axes d of the first and second magnetic poles, the permanent magnets on the side of the first magnetic pole are arranged in a manner such to be highlighted in a region on the side of the second magnetic pole without interfering with the permanent magnets on the side of the second magnetic pole.
[009] Another rotor of the present invention used in a magnet assisted reluctance motor, which includes a stator which includes windings of a plurality of phases, and a rotor which is arranged within the stator in a rotatable manner and which includes a plurality of internal mounting holes in which a plurality of permanent magnets are embedded, in which the direction of magnetic flux formed by each of the magnetic poles of the plurality of permanent magnets is established as the geometric axis d, a geometric axis that is magnetically orthogonal to the geometric axis d is established as geometry axis q, a plurality of geometry axes deq is alternately provided in a circumferential direction in the rotor, and the rotor is rotated by the reluctance torque generated by a difference in magnetic resistance between the directions of the geometric axis and that of the geometric axis qe by the magnetic torque generated by the permanent magnets, it is characterized in that: the plurality of permanent magnets in includes permanent magnets which are three sides of a trapezoid in cross section and form a first magnetic pole which is the N or S pole, and permanent magnets which are three sides of a trapezoid in cross section and form a second magnetic pole which is of polarity different from the first magnetic pole; each of the permanent magnets that form the first and second magnetic poles is embedded in the rotor in such a way that a convex side portion of the same faces the center of the rotor; and, when a cross section of the rotor is equally divided into regions to which each of the geometrical axes d belongs with respect to each of the geometrical axes d of the first and second magnetic poles, the permanent magnets on the side of the first magnetic pole are arranged in a manner such to be highlighted in a region on the side of the second magnetic pole without interfering with the permanent magnets on the side of the second magnetic pole.
[0010] A brushless motor of the present invention, which includes a stator that includes windings of a plurality of phases, and a rotor that is arranged inside the stator in a rotatable manner and that includes a plurality of internal mounting holes in which a plurality of permanent magnets is embedded, in which a direction of magnetic flux formed by each of the magnetic poles of the plurality of permanent magnets is established as the geometric axis d, a geometric axis that is magnetically orthogonal to the geometric axis d is established as the geometric axis q , a plurality of the geometrical axes deq is alternately provided in a circumferential direction in the rotor, and the rotor is rotated by the reluctance torque generated by a difference in the magnetic resistance between directions of the geometric axis and that of the geometric axis q and by the magnetic torque generated by the permanent magnets , is characterized in that: the plurality of permanent magnets includes permanent magnets that are of cross section arched cross and form a first magnetic pole that is the N or S pole, and permanent magnets that are arcuate in cross section and form a second magnetic pole that is of different polarity from the first magnetic pole; each of the permanent magnets that form the first and second magnetic poles is embedded in the rotor in such a way that a convex side portion of them faces a center of the rotor; and, when a cross section of the rotor is equally divided into regions to which each of the geometrical axes d belongs with respect to each of the geometrical axes d of the first and second magnetic poles, the permanent magnets on the side of the first magnetic pole are arranged in a manner such to be highlighted in a region on the side of the second magnetic pole without interfering with the permanent magnets on the side of the second magnetic pole.
[0011] Another brushless motor of the present invention, which includes a stator that includes windings of a plurality of phases, and a rotor that is arranged inside the stator in a rotatable manner and that includes a plurality of internal mounting holes in the in which a plurality of permanent magnets is embedded, in which a direction of magnetic flux formed by each of the magnetic poles of the plurality of permanent magnets is established as the geometric axis d, a geometric axis that is magnetically orthogonal to the geometric axis d is established as the geometric axis q, a plurality of the geometrical axes of q is alternately provided in a circumferential direction in the rotor, and the rotor is rotated by the reluctance torque generated by a difference in the magnetic resistance between the directions of the geometric axis and the geometrical axis q and by the magnetic torque generated by the magnets permanent, it is characterized in that: the plurality of permanent magnets includes permanent magnets that are three l of a trapezoid in cross section and form a first magnetic pole which is the N or S pole, and permanent magnets that are three sides of a trapezoid in cross section and form a second magnetic pole that is of different polarity from the first magnetic pole; each of the permanent magnets that form the first and second magnetic poles is embedded in the rotor in such a way that a convex side portion of them faces a center of the rotor; and, when a cross section of the rotor is equally divided into regions to which each of the geometrical axes d belongs with respect to each of the geometrical axes d of the first and second magnetic poles, the permanent magnets on the side of the first magnetic pole are arranged in a manner such to be highlighted in a region on the side of the second magnetic pole without interfering with the permanent magnets on the side of the second magnetic pole.
[0012] The brushless motor can be used as a drive source for an electrically assisted steering device. Therefore, it is possible to provide an engine for steering with electric assistance that can reduce torque oscillation and edge effect, leading to an improvement in the return of the steering wheel and in the feeling of steering. ADVANTAGES OF THE INVENTION
[0013] As for the magnet-assisted reluctance motor rotor of the present invention, in the rotor used in the magnet-assisted reluctance motor in which the rotor rotates using the assistance of a magnet's magnetic force, the permanent magnets that are of section arcuate cross are used to form the first and second magnetic poles, and the permanent magnets on the side of the first magnetic pole are arranged in such a way as to stand out in a region on the side of the second magnetic pole without interfering with the permanent magnets on the side of the second pole magnetic. Therefore, it is possible to reduce the torque oscillation and edge effect of the reluctance motor that uses the rotor.
[0014] As for another magnet-assisted reluctance motor rotor of the present invention, in the rotor used in the magnet-assisted reluctance motor in which the rotor rotates using the assistance of a magnet's magnetic force, the permanent magnets whose cross section is in a form composed of three sides of a trapezoid are used to form the first and second magnetic poles, and the permanent magnets on the side of the first magnetic pole are arranged in such a way as to stand out in a region on the side of the second magnetic pole without interfere with the permanent magnets on the side of the second magnetic pole. Therefore, it is possible to reduce the torque oscillation and edge effect of the reluctance motor that uses the rotor.
[0015] As for the brushless motor of the present invention, in the magnet-assisted reluctance motor in which the rotor rotates using the assistance of a magnet's magnetic force, which is used as that rotor is a rotor in which: the magnets permanent ones that are of arcuate cross section are used to form the first and second magnetic poles, and the permanent magnets on the side of the first magnetic pole are arranged in such a way as to stand out in a region on the side of the second magnetic pole without interfering with the permanent magnets on the side of the second magnetic pole. Therefore, it is possible to reduce the torque oscillation and motor edge effect.
[0016] As for another brushless motor of the present invention, in the magnet-assisted reluctance motor in which the rotor rotates using the assistance of a magnet's magnetic force, which is used as that rotor is a rotor in which: permanent magnets whose cross section is in a shape composed of three sides of a trapezoid are used to form the first and second magnetic poles, and the permanent magnets on the side of the first magnetic pole are arranged in such a way as to stand out in a region on the side the second magnetic pole without interfering with the permanent magnets on the side of the second magnetic pole. Therefore, it is possible to reduce the torque oscillation and motor edge effect.
[0017] In addition, in another brushless motor of the present invention, in the magnet-assisted reluctance motor, the stator tooth tip portions are connected together via the bridge section, and incisions are provided in order to house magnets on the rotor. The sections of the magnetic pole are formed along the circumferential direction of the rotor by each of the magnets. If the length in the circumferential direction of the bridge section is represented by W1, and the distance between the incisions in the section of the magnetic pole of the same polarity by W2, W1 and W2 are established in such a way that W1 <W2. Therefore, it is possible to reduce the torque oscillation. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a cross-sectional view of a brushless motor according to a first embodiment of the present invention.
[0019] FIG. 2 is a cross-sectional view of FIG. 1 made along line A-A.
[0020] FIG. 3 is an explanatory diagram showing the configuration of a bridge section.
[0021] FIG. 4 is an explanatory diagram showing the configuration of fitting-fixing sections of an external stator and an internal stator.
[0022] FIG. 5 is an explanatory diagram showing the configuration of a rotor.
[0023] FIG. 6 is a graph showing each pole trend in the results of analysis of the relationship between the distance between a magnet in the innermost layer of each pole and a centerline and torque oscillation using the modeFRONTIER® for combinations of the distance between the magnet and the center line.
[0024] FIG. 7 is a graph showing the relationship between the ratio of distance from the center of the magnet Rs and Rn to the torque oscillation.
[0025] FIG. 8 is a graph showing each pole trend in the analysis results using modeFRONTIER® for distance (shortest distance) combinations Ls, Ln between an inner magnet of each pole and the center Or of a rotor.
[0026] FIG. 9A is an explanatory diagram showing torque fluctuations when magnets are asymmetrically arranged based on configurations (a) to (c) of the present invention and when magnets are symmetrically arranged as before; FIG. 9B is an explanatory diagram showing a difference in the edge torque between the two mentioned.
[0027] FIG. 10A is an explanatory diagram showing output torque when magnets are asymmetrically arranged based on configurations (a) to (c) of the present invention; FIG. 10B is an explanatory diagram showing the output torque when magnets are symmetrically arranged as before.
[0028] FIG. 11A is an explanatory diagram showing reluctance torque when magnets are asymmetrically arranged based on configurations (a) to (c) of the present invention; FIG. 11B is an explanatory diagram showing reluctance torque when magnets are symmetrically arranged as before.
[0029] FIG. 12A is an explanatory diagram showing a voltage waveform induced when magnets are asymmetrically arranged based on configurations (a) to (c) of the present invention; FIG. 12B is an explanatory diagram showing an induced voltage waveform when magnets are symmetrically arranged as before.
[0030] FIG. 13 is an explanatory diagram showing the eccentric configuration of a rotor.
[0031] FIG. 14A is an explanatory diagram showing a torque waveform when an outer periphery of a rotor becomes eccentric; FIG. 14B is an explanatory diagram showing a torque waveform when an outer periphery of a rotor does not become eccentric.
[0032] FIG. 15A is an explanatory diagram showing a comparison between torque oscillation caused by the use of a rotor in which configurations (1) to (3) of the present invention are used in combination, and torque oscillation caused by the use of a rotor in which conventional configurations are used. (no settings (1) through (3)) are used; FIG. 15B is an explanatory diagram showing a comparison between torque caused by the use of a rotor in which configurations (1) to (3) of the present invention are used in combination, and torque caused by the use of a rotor in which conventional configurations are used.
[0033] FIG. 16 is an explanatory diagram showing a modified example of a magnet arrangement.
[0034] FIG. 17 is an explanatory diagram showing a modified example of a magnet shape.
[0035] FIG. 18 is an explanatory diagram showing the configuration of a magnetic flow control section in a brushless motor according to a second embodiment of the present invention.
[0036] FIG. 19A is a diagram showing various types of combinations of conic sections provided in incision for each layer; FIG. 19B is a graph showing a comparison of the torque oscillation rate between the combinations.
[0037] FIG. 20 is an explanatory diagram showing the relationship between angle of rotation and torque when conventional specifications are used, when conical sections are provided in an innermost layer and an intermediate layer, and when a conical section is provided only in an outermost layer.
[0038] FIG. 21 is a graph showing a comparison of the torque oscillation rate between when conventional specifications are used and when the taper angle θt is 60, 70 or 80 degrees.
[0039] FIG. 22 is an explanatory diagram showing the relationship between rotation angle and torque when conventional specifications are used and when the taper angle θt is 60, 70 or 80 degrees.
[0040] FIG. 23 is an explanatory diagram showing the rates of torque oscillation when, in a magnet-assisted reluctance motor of the present invention, maximum torque control or maximum rotational frequency control are performed.
[0041] FIG. 24 is a cross-sectional view of a brushless motor according to a third embodiment of the present invention.
[0042] FIG. 25 is a cross-sectional view of FIG. 24 made along line A-A.
[0043] FIG. 26 is an explanatory diagram showing the configuration of a portion X in FIG. 25.
[0044] FIG. 27 is an explanatory diagram showing the state of a winding housed in a slot; FIG. 27A shows a conventional fan-shaped slot structure; FIG. 27B shows the configuration of an engine of the present invention that uses a parallel slot structure.
[0045] FIG. 28 is a graph showing results of experiments by the inventors, showing the relationship between rotor rotation angle and torque.
[0046] FIG. 29 is an explanatory diagram showing a comparison between an average torque of a conventional engine and an average torque of an engine of the present invention based on the experiment results of FIG. 28.
[0047] FIG. 30 is an explanatory diagram illustrating a torque swing reduction operation in accordance with the present invention.
[0048] FIG. 31 is an explanatory diagram showing a comparison between a torque oscillation of a conventional engine and a torque oscillation of an engine of the present invention based on the experiment results of FIG. 28.
[0049] FIG. 32 is an explanatory diagram showing the configuration of a rotor production device when attached magnets are used as magnets. MODALITIES FOR CARRYING OUT THE INVENTION
[0050] In the following, modalities of the present invention will be described in detail based on the attached drawings. The purpose of the modalities described below is to increase the output of a brushless motor, or particularly a magnet-assisted reluctance motor, and to reduce edge torque and torque oscillation in a well-balanced manner. (First modality)
[0051] FIG. 1 is a cross-sectional view of a brushless motor 1 (simply referred to as motor 1, below) according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view of FIG. 1 made along line A-A. Motor 1 is a magnet-assisted reluctance motor that is based on a reluctance motor and uses assistance from a magnetic force of a magnet arranged on a rotor. For example, motor 1 is used as a drive source for an electrically assisted steering device. As shown in FIG. 1, motor 1 is a brushless motor of an internal rotor type in which, as in the case of a typical reluctance motor, a stator (Stator) 2 is located on the outside and a rotor (Rotor) 3 is on the inside .
[0052] The stator 2 includes a casing of the motor 4 in a cylindrical form with a bottom; a stator core 5; and a coil of stator 6 (simply referred to as coil 6, below), which is wound on the core of stator 5; and a busbar unit (terminal unit) 7, to which the coil 6 mounted on the stator core 5 is electrically connected. The engine lining 4 is made of iron or similar and made in a cylindrical shape with a bottom. In an opening of the engine casing 4, with fixing screws (not shown), a clamp 8 made by die casting aluminum is attached. After the coil 6 is wound on the core of the stator 5, the core of the stator 5 is pressed into the casing of the motor 4 and fixed on its inner peripheral surface. Motor 1 adopts the so-called external winding, with coil 6 disposed in stator 2, which is an external element. The external winding motor can achieve an improvement in the motor output because the motor can increase the winding space factor more than a motor in which a coil is wound on an internal element.
[0053] As shown in FIG. 2, the core of the stator 5 includes a cylindrical outer stator 11 and an inner stator 12, which is attached to an inner peripheral side of the outer stator 11. The outer stator 11 and the inner stator 12 are made by stacking magnetic steel sheets with thickness t (t = about 0.35 to 0.70 mm). The internal stator 12 includes 24 sections of teeth 13, which are radially formed; and a bridge section 14, which connects the inner peripheral sides of the tooth sections 13 to each other. Between sections of adjacent teeth 13, slits 15 are formed. As shown in FIG. 3, in this motor 1, the width in the radial direction W of the bridge section 14 is established in the range of t <W <1.5 mm: t is the thickness of the plate of one of the steel plates that make up the core pile of the stator 5.
[0054] In motor 1, the inner peripheral sides of the tooth sections 13 are connected by the bridge section 14. Thus, unlike a typical motor, a coil cannot be wound on the teeth using incisions on the sides of the tips of the teeth. In the case of motor 1, stator 2 is divided into external stator 11 and internal stator 12, and the outer peripheral sides of the tooth sections of internal stator 12 are made open. This configuration allows the formation of the coil 6, by wrapping a copper wire in the sections of teeth 13. After the coil 6 is wound in the sections of teeth 13 in a distributed winding pattern, the sections of teeth 13 are mounted on the inner peripheral side of external stator 11 (fitting and fixing). In this way, the stator core 5 is formed, with the coil 6 housed in the slots 15. Incidentally, the distributed winding can keep the leakage of magnetic flux in the bridge section 14 smaller than in the concentrated winding, and can have a higher maximum torque. than the concentrated winding. Therefore, coil 6 is wound in a winding pattern distributed on motor 1.
[0055] FIG. 4 is an explanatory diagram showing the configuration of snap-fastening sections of the external stator 11 and internal stator 12. In motor 1, 24 tooth sections are provided 13. The outer peripheral sides of the tooth sections 13 are fitted and fixed in the grooves tooth assembly (concave sections) 16, which are formed on the inner peripheral surface of the external stator 11. As shown in FIG. 4, in the external stator 11, the tooth mounting grooves 16, which are dovetail grooves that are V-shaped in cross section, are formed. The tooth mounting grooves 16 are provided for the entire length of the external stator 11 in such a way as to extend along a direction of the axis. At the outer peripheral ends of the tooth sections 13, tang-shaped interlocking sections 17 are formed in such a way as to have enlarged outer ends.
[0056] The external stator 11 and the internal stator 12 are fixed in such a way as not to be separated in the radial and circumferential directions, as the locking sections 17 are inserted and engaged in the tooth mounting grooves 16 in the direction of the axle. As a result, movement in the rotational direction of the internal stator 12 is restricted, and a positional displacement of the internal stator 12 associated with a force in the rotational direction can be reliably prevented.
[0057] On one end side of the stator core 5, the bus bar unit 7 is mounted. The bus bar unit 7 is made by molding by inserting a bus bar, which is made of copper, into a main body made of synthetic resin. Around the bus bar unit 7, a plurality of terminals of the power supply 21 are provided in such a way as to project in the radial direction. When the busbar unit 7 has to be mounted, at the terminals of the power supply 21, ends 6a of the coils 6, which are pulled out of the core of the stator 5, are welded. The number of busbars provided in the busbar unit 7 matches the number of phases of motor 1 (In this case, a total of four busbars is provided, with three for three-phase, phase U, phase V and phase W , and one for connection between the phases). Each coil 6 is electrically connected to a terminal of the power supply 21 corresponding to its phase. After the bus bar unit 7 is assembled, the stator core 5 is pressed and attached to the motor casing 4.
[0058] In stator 2, rotor 3 is inserted. The rotor 3 includes a rotor shaft 22. The rotor shaft 22 is supported by bearings 23a and 23b in a rotatable manner. Bearing 23a is fixed in the center of a lower section 4a of the motor jacket 4. Bearing 23b is fixed to a central portion of the clamp 8. On rotor shaft 22, a cylindrical rotor core 24 and a rotor (solver rotor) ) 32 of a solver 31, which is a device for detecting the rotational angle, are attached.
[0059] On the outside (or right side in FIG. 1) of the lower section 4a of the motor jacket 4, a cover 33 is attached. The rotor shaft 22 extends from the lower section 4a of the motor casing 4 to the cover 33. At the tip of the rotor shaft 22, the rotor of the resolver 32 is mounted. Inside the cover 33, control panels 34 and 35 are housed. On the control panel 34, an element of the power system 36 is mounted. In the control panel 35, an element of the control system 37 is mounted. On the control panel 35, a solver 38 stator is mounted in such a way that it faces the outer peripheral side of the solver 31 rotor. In the solver 38 stator, a signal line from a rotational angle detection coil is provided. The solver stator 38 is electrically connected to the control system element 37 via the signal line.
[0060] The core of rotor 24, which constitutes rotor 3, is made by stacking a large number of disc-shaped magnetic steel plates. In the steel sheets that constitute the core of the rotor 24, a plurality of incisions 25 are provided as mounting holes in which magnets are to be mounted. Incisions 25 are curved in an arc. There is space in the incisions 25. If the direction of magnetic flux formed by magnetic poles (or central axis of permanent magnets) is referred to as the geometric axis d, and, if the geometric axis that is magnetically orthogonal to the geometric axis d (axis between permanent magnets) ) is established as a geometry axis q, a plurality of sets of incisions 25 is provided, with the geometry axis q, which is perpendicular to the geometry axis of the rotor 22, as a boundary. The incisions 25 are arranged in an arc shape around imaginary points (described later; Os and On centers of circular arcs of 26n and 26s S and N pole magnets), which are established outside the outer periphery of rotor 3 on the axis geometric d. In motor 1, four sets of a plurality of incisions 25 are provided in an arc shape around the imaginary points on the geometric axis d. In each set, a plurality of layers of magnetic paths are formed. Incidentally, after the magnets 26, described below, are embedded in the incisions 25, the spaces formed in the end portions by the incisions 25 and the magnets 26 function as a flow barrier, so that the magnetic resistance of the rotor 3 varies over time. along the rotational direction.
[0061] In the case of a normal reluctance motor, in order to change the magnetic resistance of rotor 3, the incisions 25 are left hollow and used as a flow barrier. In motor 1 of the present invention, in order to increase the output, a plurality of magnets (permanent magnets) 26 are embedded in the incisions 25. In motor 1, the reluctance torque is considered the main force, and the magnetic torque as an auxiliary force . In this way, inexpensive ferrite magnets are used as 26 magnets. However, in order to further increase the output, attached neodymium magnets or other rare earth magnets can be used as magnets 26.
[0062] FIG. 5 is an explanatory diagram showing the configuration of rotor 3. In rotor 3 of FIG. 5, as a plurality of magnets 26, magnets 26s (26s1, 26s2) whose outer peripheral sides serve as poles S, and magnets 26n (26n1, 26n2) whose outer peripheral sides serve as poles N, are provided. That is, the rotor 3 has a four pole structure, and the motor 1 is formed in such a way that it has a structure with 24 slots of four poles (2 poles 12 slits x 2). The rotor 3 of the present invention has three features described below. (1) The magnets 26 on each pole are formed in a circular arc. Sets of three magnets 26 are provided along the radial direction, and a plurality of geometric axes of geometric axes q is provided alternately in the circumferential direction on the rotor 3. Therefore, it is possible to intensify the torque with the help of the magnetic torque, still making use of of the reluctance torque. (2) S 26s1 and 26s2 pole magnets and N 26n1 and 26n2 pole magnets are arranged asymmetrically around the center line, thereby reducing torque oscillation and the edge effect. (3) The rotor 3 is shaped in such a way as to have an eccentric outer periphery. Therefore, the torque oscillation can be reduced.
[0063] Each of the resources will be described below. (1) Arrangement of three arc-shaped magnets
[0064] As for the previous feature (1), in rotor 3, as previously described, the direction of the magnetic flux formed by magnetic poles is referred to as the geometric axis d, and the geometric axis that is magnetically orthogonal to the geometric axis d is considered geometric axis q. In rotor 3, a plurality of geometry axes d and geometry axes q is established. In this case, geometric axes d and geometric axes q are alternately provided along the circumferential direction. In the rotor 3, in order to make it easier for the magnetic flow of the geometric axis q to pass, arcuate incisions 25 are provided. In incisions 25, arched magnets 26 are embedded. That is, the rotor 3 is formed in such a way as to make it easier for the magnetic flux of the geometric axis q to pass and increase the inductance Lq. Therefore, it is possible to increase the magnetic torque caused by magnets 26 and to obtain sufficient torque even with ferrite magnets.
[0065] In this case, by increasing the number of circular arcs (incisions 25), the number of magnetic paths can be increased, and the magnetic torque can be intensified. However, in order to increase the number of incisions 25, magnets 26 need to be made thinner. In addition, if a large number of incisions 25 are provided, the magnetic paths in the steel sheets become smaller in width, leaving the rotor prone to magnetic saturation. In addition, Ld-Lq (difference between Ld and Lq) to obtain the reluctance torque does not change much even when the number of magnets 26 (or number of layers) is greater than or equal to three. Therefore, a realistic number of magnets 26 (or number of layers) is about three. In the case of rotor 3, magnets 26 are formed as three layers.
[0066] The incisions 25a to 25c in each layer are formed in order to have the same radius, regardless of whether the incisions are for pole N or S. For magnets 26a (innermost layer), 26b (intermediate layer) and 26c (outermost layer) in each layer, the same magnet is used. That is, magnets 26 require three types of magnet, 26a to 26c, thereby leading to a reduction in the number of components. (2) Asymmetric arrangement of magnets
[0067] As for the previous feature (2), in the rotor 3, the asymmetric configuration of magnets reduces the torque oscillation. In this case, the asymmetric configuration of rotor 3 is characterized in that: (a) The cross section of rotor 3 is equally divided into regions to which each geometrical axis d belongs, with respect to each of the geometrical axes d of magnets 26s (first pole magnetic) and 26n magnets (second magnetic pole). Then, a more internal magnet 26a of a pole (pole S, in this case) with respect to the center lines M1 and M2 of the rotor 3 that are perpendicular to each other and serve as dividing lines for each region is arranged in such a way as to stand out in an area (region) with an adjacent pole. The magnet protruding from the adjacent pole zone does not interfere with a magnet from an adjacent pole, and a space for a magnetic path of the geometric axis q is ensured. As a result, the angle θ1 (central angle around the center Or of rotor 3) of a region of the magnet 26s that is divided by the geometric axis q is established greater than angle θ2 (the same previous) of a region of the magnet 26n ( θ1> θ2). (b) The central positions of magnets 26 are different between poles S and N. That is, the distance (distance from the center of the magnet) Rs (R1) between the center Os (first center point) of a circular arc of pole magnets S 26s and the center Or of rotor 3 is different from the distance (distance from the center of the magnet) Rn (R2) between the center On (second center point) of a circular arc of N 26n pole magnets and the center Or of rotor 3 (Rs Φ Rn). (c) The distance (shortest distance) Ls (L1) between the innermost magnet 26a of pole S and the center Or of rotor 3 is different from the distance (shortest distance) Ln (L2) between the innermost magnet 26a of pole N and the center Or of rotor 3 (Ls Φ Ln). (d) Overlapping magnets
[0068] As shown in FIG. 5, on rotor 3, with respect to each of the geometric axes d of magnets 26s (first magnetic pole) and magnets 26n (second magnetic pole), there are four regions, which are defined by dividing the cross section of rotor 3 equally into regions to which each geometric axis d belongs, or four zones of poles S1, N1, S2 and N2, which are defined by center lines M1 and M2. In the rotor 3 of the present invention, an outer peripheral portion 41 of a pole magnet S 26s of an innermost layer (or a layer closer to the center rotor Or) protrudes from the pole zone S1 or S2 to the zone adjacent pole N1 or N2 on the other pole. Incidentally, a magnet that protrudes to a side region of the adjacent zone can be both S and N pole. What is shown here is the case where an S 26s pole magnet superimposed (or highlighted) in an N pole zone The larger the overlap margin in an adjacent zone becomes, the more the torque fluctuation can be reduced. However, in order to prevent interference at an adjacent pole, between an S 26s pole magnet and an adjacent 26n N pole magnet, a space 42 is provided.
[0069] FIG. 6 is a graph showing each pole trend in the results of analysis of the relationship between the distance between a magnet of the outermost layer 26a of each pole and the center line M1, M2 and torque oscillation using modeFRONTIER® (Multipurpose robust design optimization support tool: trade name) for combinations of the distance between the magnet and the centerline. Incidentally, on the horizontal axis of FIG. 6, a negative value indicates the situation where a magnet overlaps an adjacent pole zone. As can be seen from FIG. 6, the overlapping of pole S reduces oscillation. However, in the case of pole N, the oscillation is reduced when it is a certain distance from the center line. However, if pole S interferes with pole N, the oscillation of pole S increases (when pole S is established in such a way as to emphasize). If the distance between the poles is too small, the torque decreases. Thus, in the case of rotor 3, while a magnet of pole S 26s superimposed a zone of pole N, the space 42, whose size (for example, 1.2 mm) is approximately twice the thickness of the plate (about 0 , 35 to 0.70 mm) of the magnetic steel plates, is provided between the pole magnet S 26s and the pole magnet N 26n. (e) Shifting the central position of the pole
[0070] FIG. 7 is a graph showing the relationship between the ratio of distance from the center of the magnet Rs and Rn to the torque oscillation. As can be seen from FIG. 7, as Rs / Rn gets bigger, the torque oscillation increases. Therefore, the lower Rs / Rn, the more the torque oscillation is reduced. However, after Rs / Rn becomes less than 0.92, an S 26s pole magnet interferes with an N 26n pole magnet. In this way, the Rs / Rn which is set at 0.92 is ideal for reducing torque fluctuation. (f) Displacement in the arrangement of magnets
[0071] FIG. 8 is a graph showing each pole trend in the analysis results using modeFRONTIER® for combinations of the above-described distances Ls and Ln. As shown in FIG. 8, Ls marks a minimum value at 7, and Ln marks a minimum value at 9. It is clear from the results that, as for Ln and Ls, the magnets of the outermost layer 26a of each pole must be placed in such a way that Ls : Ln = 7: 9.
[0072] In general, when magnets are symmetrically arranged in a motor, the number of times the edge effect occurs is equal to a minimum common multiple of the poles and slits. Thus, in the case of a 24-slot four-pole motor, the edge effect occurs for 24 peaks per motor rotation. In order to reduce the edge effect, some methods are available, such as applying a distortion. In this case, the problem is that the torque is reduced because of the flow leakage effects. In the case of motor 1 of the present invention, the rotor 3 is made in an asymmetric form in line with (a) to (c). Therefore, the edge effect is reduced as the suction forces generated at each pole between the rotor and the stator are canceled. FIG. 9 is an explanatory diagram showing torque fluctuations when magnets are asymmetrically arranged based on the above-described configurations (a) to (c) and when magnets are symmetrically arranged as before (FIG. 9A), as well as a difference in edge torque between the two previous ones (FIG. 9B). As shown in FIG. 9A, when magnets are asymmetrically arranged, fluctuations in torque can be kept small. As shown in FIG. 9B, if the result of conventional configurations is 100, the configurations of the present invention can maintain the edge effect at 20 percent of that result.
[0073] The output torque of motor 1 is a combination of reluctance torque and magnetic torque. In the case of a symmetrical rotor, due to fluctuations in Ld-Lq, the oscillation of the reluctance torque becomes greater. In the case of motor 1 of the present invention, the rotor is asymmetrical. Therefore, the reluctance torque that is generated in pole zones S S1, S2 of FIG. 5, and the reluctance torque that is generated in pole zones N N1, N2 are canceled out, leading to a reduction in torque oscillation.
[0074] FIG. 10A is an explanatory diagram showing the output torque when magnets are asymmetrically arranged based on the above-described configurations (a) to (c). FIG. 10B is an explanatory diagram showing the output torque when magnets are symmetrically arranged as before. Incidentally, in the diagrams, the magnetic torque is represented by Tm, and the reluctance torque by Tr. The output torque (total torque), which is a combination of Tm and Tr, is represented by Tt. As shown in FIG. 10A, it is clear that when the magnets are asymmetrically arranged, the torque oscillation is reduced much more than in the case of FIG. 10B.
[0075] In this case, as for the oscillation related to the reluctance torque, as shown in FIG. 11A, the reluctance torque Tr (a) in portion A and the reluctance torque Tr (B) in portion B cancel each other out. As a result, the total reluctance torque Tr (combined) is much lower than that of the symmetrical structure shown in FIG. 11B.
[0076] As for magnetic torque, in the case of a symmetrical rotor, an induced voltage waveform deforms as high frequency components are superimposed on the magnetic flux, resulting in an increase in torque oscillation. In the case of an asymmetric rotor, high frequency components are canceled out, an induced voltage waveform is transformed into a sine wave, and a torque oscillation of the magnetic torque is reduced. As previously described, a method of reducing torque oscillation by transforming the induced voltage into a distortion sine wave is also available. However, in this case, the distortion leads to a reduction in torque. The asymmetric structure of the rotor of the present invention does not achieve a reduction in torque. Therefore, the asymmetric structure is more effective than the distortion in reducing torque oscillation.
[0077] FIG. 12A is an explanatory diagram showing the voltage waveform induced when magnets are asymmetrically arranged based on the above-described configurations (a) to (c). FIG. 12B is an explanatory diagram showing the voltage waveform induced when magnets are symmetrically arranged as before. As shown in FIG. 12B, when magnets are symmetrically arranged, the induced voltage waveform deforms. When magnets are asymmetrically arranged, as shown in FIG. 12A, it is clear that the waveform is transformed into a sine wave. (3) Rotor eccentricity
[0078] As for the previous feature (3), in the rotor 3, the torque oscillation is reduced by the external peripheral eccentric configuration. FIG. 13 is an explanatory diagram showing the eccentric configuration of rotor 3. Incidentally, in FIG. 13, in order to make the eccentric state of the rotor 3 clear, the external shape of the rotor is exaggerated. As previously described, a magnet that protrudes in an adjacent lateral region of the zone can be either pole S or N. Therefore, different from that shown in FIG. 5, FIG. 13 illustrates an N 26n pole magnet that was superimposed on an S pole zone.
[0079] As shown in FIG. 13, the outer periphery of rotor 3 is not a uniform circumference of a circle around the point Or. The outer periphery of rotor 3 consists of circular arcs, each of which has a radius from a different central point for each of the four pole zones S1, S2, N1 and N2. The circular arcs are connected to each other at a limit point P of each pole zone. That is, the outer periphery of each pole zone is formed as a circular arc with a radius of Rec from the eccentric point, or center, Oec. The eccentric point Oec is an eccentric distance Lec away from the central point of the rotor Or towards an external side in the radial direction. The eccentric point Oec is located on a line segment that is angled 45 degrees with the center lines M1 and M2. The radius Rec is less than the distance Rmax between an outermost position Q of rotor 3 and the center of rotor Or.
[0080] When the outer periphery of rotor 3 is made eccentric, the components of higher frequency of the induced voltage waveform can be reduced further. As a result, the torque oscillation can be further reduced. In addition, the rotor eccentricity can moderate fluctuations in the magnetic flux caused by rotor rotation. As a result, fluctuations in the magnetic torque can be reduced, and the torque oscillation can be reduced. FIG. 14A is an explanatory diagram showing the torque waveform when an outer periphery of a rotor is made eccentric. FIG. 14B is an explanatory diagram showing the torque waveform when an outer periphery of a rotor is not made eccentric.
[0081] As shown in FIG. 14, if the rotor 3 is configured eccentric, the torque oscillation, particularly the torque oscillation of the magnetic torque Tm, can be reduced, and the oscillation of the output torque Tt, is also reduced. According to the results of experiments by the inventors, even in the case of an “asymmetric / non-eccentric” configuration, the torque oscillation was much lower than the “symmetric / non-eccentric” (Torque oscillation rate: reduced from 8 percent to 5 percent ). In the case of an “asymmetric / eccentric” configuration, the torque oscillation is further reduced (torque oscillation rate reduced to about 3.7 percent). In general, in the case of an electrically assisted steering motor, it is preferred that the torque oscillation is maintained at less than 5 percent. The “asymmetric / non-eccentric” configuration can roughly meet this criterion. However, in order to reduce both the oscillations of the reluctance torque and the magnetic torque and to keep the total torque oscillation below 5 percent without failure, it is desirable that the outer periphery of the rotor be made eccentric.
[0082] In this way, due to the asymmetric rotor configurations described above (1) to (3), motor 1 of the present invention can reduce both oscillations of the reluctance torque and magnetic torque, and can reduce the edge effect. FIG. 15 is an explanatory diagram showing: a comparison between torque oscillation caused by the use of a rotor in which the above-described configurations (1) to (3) are used in combination, and torque oscillation caused by the use of a rotor that is configured as before without using (1) to (3) (FIG. 15A); and a comparison between torque caused by the use of a rotor in which the above-described configurations (1) to (3) are used in combination, and torque caused by the use of a rotor which is configured as before without using (1) to (3) (FIG. 15B). As shown in FIG. 15, in the case of the configurations of the present invention, although the torque is practically the same as that obtained by conventional configurations, the torque oscillation is divided in half. That is, according to the present invention, it is possible to reduce torque fluctuation without sacrificing torque, compared to conventional configurations.
[0083] Incidentally, the configuration similar to the one described above can be performed by having magnets in a different way from the first mode described above. That is, according to the first modality, S 26s pole magnets are arranged around the same central point in layers, and N 26n pole magnets are arranged around the same central point in layers. Then, three-layer magnets 26 are arranged in such a way that the distance Rs between the center Os and the center of the rotor Or is different from the distance Rn between the center On and the center of the rotor Or. In this way, magnets 26a are placed in such a way as to overlap in an adjacent pole zone, without letting the magnets 26a interfere with the magnets on the other pole. However, the structures shown in FIGS. 16A and 16B are also possible.
[0084] That is, as shown in FIG. 16A, magnets 26 can be layered in such a way that the radii of the magnets in each layer are set at the same R0 value and that the central points of the rays are placed in different positions O1 to O3. In the case of FIG. 16A, the centers of the magnets are placed on a line segment that is inclined 45 degrees with the center lines M1 and M2, and the distances between the center points and the center of the Or rotor are different. As shown in FIG. 16B, magnets can be arranged in such a way that the distance between the center point of the radii of the pole magnets S 26s and the center of the rotor Or is equal to the distance between the center point of the radius of the pole magnets N 26n and the center of the Or rotor (Or-Os distance = Or-On distance); and that the radii of the 26s and 26n magnets are different from each other.
[0085] What is shown here as an example is the use of permanent magnets that are arcuate in cross section to magnets 26 in motor 1. Instead, as shown in FIG. 17, a magnet 43 whose cross section is in the form formed by three sides of an isosceles trapezoid (upper base and two oblique sides) can be used. Incidentally, as previously described, placement of three magnets 26 or 43 is adequate in terms of balance. However, the number is not limited to three; two or four magnets can be placed, for example.
[0086] In the above-described modality, what is described is an example of a brushless motor in which the inner peripheral sides of the tooth sections 13 are connected to each other via the bridge section 14. However, the present invention can also be applied to a brushless motor in which teeth are formed separately without a bridge section. The structure of the tooth sections 13 is not limited to one in which the tooth sections 13 are fitted and fixed in the tooth mounting grooves 16 of the external stator 11. The tooth sections 13 can be formed integrally with the external stator 11 . (Second modality)
[0087] FIG. 18 is an explanatory diagram showing the configuration of a brushless motor 51 (simply referred to as motor 51, below) according to a second embodiment of the present invention. In addition to the three features described above for engine 1 of the first modality, a fourth feature is added to engine 51. That is, in the case of engine 51, in a region (one of the pole S region of FIG. 5, a pole N region of the FIG. 13) where a magnet of the innermost layer 26 protrudes in a zone of pole adjacent to the other pole, a linear conical section 52 is provided in an end portion of an incision of the outermost layer 25. Incidentally, the same portions, elements and components of those of the first modality are represented by the same reference symbols, and will not be described again.
[0088] In the above-described motor 1, due to the structures of the above-described configurations (1) to (3), an oscillation rate of the upper torque limit (5%) for the EPS motor can be met. However, the execution of the maximum torque control or the control of the maximum rotational frequency tends to leave only a little space in a low current region. Thus, in the case of motor 51, in a peripheral edge portion of an incision of the outermost layer 25c of rotor 3, a linear conical section 52 is provided and, in an end portion of the incision, a flow control section magnetic 53 is formed in order to control the amount of magnetic flux that passes between incisions 25a and 25b and additionally to reduce the rate of torque oscillation.
[0089] As shown in FIG. 18, at the core of the rotor 24 of the motor 51, in two end portions of an incision of the outermost layer 25c, conical sections 52, which are made by transforming the peripheral edges of the incision 25c in a straight line, are provided. In the motor 51, magnetic flow control sections 53 are formed between the conical sections 52 and an incision of the intermediate layer 25b. The conical sections 52 are provided outside the arc angle of pole α of the magnet of the outermost layer 26c and within the opening angle β of the incision 25c. That is, the angle θk formed by base points K of the two conical sections 52 is: α <θk <β. Incidentally, in the case of FIG. 18, θk = α. Furthermore, the taper angle θt formed by the line A extending along the conical section 52 and the line B at the position of an end portion of the magnet 26c is formed in such a way as to be greater than 0 degree and less than 90 degrees (0 degree <θt <90 degrees). According to the results of experiments by the inventors, θt should be about 60 degrees to 75 degrees, or more preferably about 68 degrees to 72 degrees. In the present mode, θt = 70 degrees.
[0090] Motor 51 is designed to rotate in the forward and reverse directions for EPS. In order to perform forward and reverse rotations in a balanced manner, the tapered sections 52 at both ends of the incision 25c are arranged symmetrically around the centerline Ot. That is, the angle of the base point θk between the two conical sections 52 is equally divided by the centerline Ot. The taper angles θt of the two conical sections 52 are the same. Incidentally, in an engine that is designed to rotate in only one direction, there is no need to provide conical sections 52 and form magnetic flow control sections 53 at both end portions of the incision 25c; a conical section 52 can be provided on one side only, depending on the direction of rotation. In such a case, the base point K of the conical section 52 is located outside the arc angle of pole α and within the opening angle β as previously described. However, since there is only one conical section 52, the base point angle θk is zero.
[0091] Such conical sections 52 can be provided not only in the incision of the outermost layer 25c, but in the incisions of the innermost layer or of the intermediate layer 25a or 25b. What is shown in FIG. 19 are combinations of conical sections provided in the incision of each layer 25 (FIG. 19A) and a graph showing a comparison of the torque oscillation rate between the combinations (FIG. 19B). As shown in FIG. 19, when the conical sections were provided in the incision of the innermost layer 25a (No. 1 to No. 4), the torque oscillation rate was generally high, and the torque oscillation was even greater than conventional specifications ( No. 8). When the conical sections were provided in the incision of the intermediate layer 25b (No. 1, 2, 5, 6), while there was part in which a torque oscillation reducing effect was confirmed (No. 5), it was suggested that the sections conics of the outermost layer can be effective, and the result was not so much greater than that of conventional specifications. When tapered sections are provided only in the incision of the outermost layer 25c (No. 7), regardless of whether maximum torque control or maximum rotational frequency control was performed, the torque oscillation reduction effect was large, and the rate of oscillation torque was kept lower than conventional specifications.
[0092] FIG. 20 is an explanatory diagram showing the relationship between rotation angle and torque when conventional specifications are used (without conical sections), when conical sections are provided in an inner layer and an intermediate layer, and when a conical section is provided only in one outermost layer. In this case, FIG. 20A shows the torque at each location. In the diagram, TP represents fluctuations in torque at a location where a conical section 52 is provided (overlapping side of the magnet), and NT represents fluctuations in torque at a location where no conical section 52 is provided. FIG. 20B shows the torque at location TP, which is separated into reluctance torque Tr and magnetic torque Tm.
[0093] In FIG. 20A, take a look at a peak torque at the TP location. If the conical sections are provided in the innermost and intermediate layers, the torque is amplified at the TP and NT locations. If the conical section is provided only in the outermost layer, the torque is canceled at the TP and NT locations. As shown in FIG. 20B, the Tr phase is significantly altered in each case; it is clear that a change in the torque waveform in FIG. 20A is mainly because of a change in the Tr phase. That is, if the conical sections 52 are provided and the magnetic magnetic flux control sections 53 are formed, the magnetic flux density distribution at the TP location is altered, resulting in a change in the Tr phase. As a result, the torque peaks are canceled between the TP and NT locations, leading to a reduction in torque oscillation.
[0094] As for the taper angle θt, if the conical sections 52 are provided in the incision of the outermost layer 25c, and if θt is established between approximately 60 degrees and 75 degrees, or preferably between 68 degrees and 72 degrees, the rate oscillation torque is less than conventional specifications. FIG. 21 is a graph showing the results of experiments by the inventors. In this case, the conventional specifications are compared with the case where θt is set at 60, 70 or 80 degrees (FIG. 21A is for maximum torque control, and FIG. 21B is for maximum rotational frequency control). As can be seen from FIG. 21, in the control of maximum torque and in the control of the maximum rotational frequency, the case where θt is established in 70 degrees is better balanced with a low torque oscillation rate from the low current region to the high current region. As in the case described above, in terms of torque change at the TP and NT locations, as shown in FIG. 22A, a maximum torque rotation angle at the TP location is shifted, in the case where θt is equal to 70 or 60 degrees, from 10 degrees to 16 degrees, which is the same value as conventional specifications. As shown in FIG. 22B, if θt is set at 70 or 60 degrees, the peak torque of Tm becomes higher. This change in peak torque leads to a shift in the maximum torque rotation angle at the TP location, and peak torque is canceled between the TP and NT locations. Therefore, the torque oscillation can be reduced by setting θt between about 60 degrees and 75 degrees.
[0095] In this way, the motor 51 of the present invention can reduce the torque oscillation using the asymmetric configurations of the rotor (1) to (3) of the first modality and the conical sections 52 of (4). FIG. 23 is an explanatory diagram showing a comparison of the torque oscillation rate between when a rotor is used in which the above-described configurations (1) to (4) are used in combination and when a rotor that is configured as before without the configurations is used (1) to (4). As shown in FIG. 23, in the case of the configurations of the present invention, during the control of maximum torque or the control of the maximum rotational frequency, the torque oscillation in the low current region is reduced, thereby giving the upper limit a greater margin than the configurations conventional. (Third modality)
[0096] FIG. 24 is a cross-sectional view of a brushless motor 101 (simply referred to as motor 101, hereinafter) according to a third embodiment of the present invention. FIG. 25 is a cross-sectional view of FIG. 24 made along line A-A. Motor 101, too, is a magnet-assisted reluctance motor that is based on a reluctance motor and uses assistance from a magnetic force of a magnet arranged on a rotor. For example, motor 101 is used as a drive source for an electrically assisted steering device. As shown in FIG. 24, motor 101 is a brushless motor with an internal rotor type in which, as in the case of a typical reluctance motor, a stator (Stator) 102 is located on the outside and a rotor (Rotor) 103 is on the inside .
[0097] Stator 102 is fixed to the inside of a motor casing 104 (simply referred to as casing 104, below) in a cylindrical form with a bottom. Stator 102 includes a core of stator 105; a stator coil 106 (simply referred to as coil 106, below), which is wound in tooth sections 109 of the stator core 105; and a bus bar unit (terminal unit) 107, which is attached to the stator core 105 and electrically connected to the coil 106. The casing 104 is made of iron or the like and produced in a cylindrical shape with a bottom. In an opening of the casing 104, with fixing screws, not shown, a clamp 108 made by die casting aluminum is attached.
[0098] The core of stator 105 is formed by stacking steel sheets (for example, magnetic steel sheets). At the core of stator 105, a plurality of tooth sections 109 is provided in such a way as to protrude towards the inner side in the axial direction. Between adjacent tooth sections 109, slits 131 are formed. Within slots 131, a coil 106 is housed in a distributed winding pattern. At the core of stator 105, an insulator 111, which is made of synthetic resin, is attached. Coil 106 is wound on the outside of insulator 111 ,.
[0099] FIG. 26 is an enlarged view of portions of the tooth sections 109, or an X portion of FIG. 25. As shown in FIG. 26, on the inner peripheral sides of the tooth sections 109, a bridge section 132 is provided in such a way as to connect adjacent tooth tip portions 109a to each other. In the bridge section 132, in order to make it easier for the magnetic flow on the stator side to pass and make the press work easier, chamfered sections 133 (chamfered in R or C) are provided between bridge section 132 and the tip portions of tooth 109a. The width in the radial direction t1 of the bridge section 132 is set at roughly the same value as the thickness of the magnetic steel sheets that make up the core of stator 105. Incidentally, the reason why coil 106 is in a distributed winding pattern as before described is due to the distributed winding pattern being able to keep the magnetic flux leakage in the bridge section 132 smaller than a concentrated winding pattern, and to make a maximum torque greater than the concentrated winding pattern.
[00100] In addition, width in the circumferential direction B of the tooth sections 109 becomes smaller towards the tip portions. The tooth sections 109 are generally fan-shaped, with a central angle θ. Thus, in the slits 131, internal surfaces in the circumferential direction 131a that face each other are parallel to each other along the radial direction. In a conventional magnet-assisted reluctance motor, teeth are formed in a straight shape with equal width, and slots are fan-shaped. Therefore, when a winding is housed in a slot, as shown in FIG. 27A, the coil cannot be placed comfortably; when the coil is welded, an insulation failure could cause the parts of the coil to rub against each other. Especially, when the inner peripheral sides of the tooth are connected to each other in the case of motor 101, winding by a winding machine is difficult. Therefore, a method of inserting a thick coil into a slit and then welding parts of the coil together is employed. However, in the case of this engine, the coil needs to be twisted when it is being welded. If there is play on the bobbin inside the slot, parts of the bobbin may rub against each other, possibly damaging a film that covers the bobbin.
[00101] In the case of motor 101, the internal surfaces 131a of the slots 131 are parallel to each other. Therefore, as shown in FIG. 27B, the thick coil 106 can be cleverly placed in the slot 131. In addition, the SW width of the slot 131 is established roughly equal (or slightly larger) to the thickness of a wire of the coil 106. Therefore, the coil 106 is placed in the slot 131 practically no game. Therefore, even if the coil is twisted before being welded, the coil is likely to move freely, thereby reducing the chance that parts of the coil will rub against each other. In this way, this configuration prevents damage to the coil film, and contributes to an improvement in the insulation performance of the coil.
[00102] In motor 101, as previously described, the bases of the tooth sections 109 are wide. Therefore, the magnetic flux flows smoothly through the teeth, and there is unlikely to be a saturation in the magnetic flux in the tooth sections. In addition, compared to the case where the teeth are formed in a straight shape, the space of a portion of the rear core in the stator core 105 is increased. As a result, the magnetic resistance is reduced, and the torque can be increased, compared to a motor of the same physical structure. FIG. 28 is a graph showing results of experiments by the inventors. FIG. 29 is an explanatory diagram showing a comparison between the average torque of a conventional engine and the average torque of an engine of the present invention based on the results of the experiment. As can be seen from FIGS. 28 and 23, the engine of the present invention performs a better torque, compared to the conventional engine, and the average torque is about 5 percent higher than that of the conventional engine.
[00103] On one end side of the stator core 105, the busbar unit 107 is mounted. The bus bar unit 107 is made by molding by inserting a bus bar, which is made of copper, into a main body made of synthetic resin. Around the bus bar unit 107, a plurality of terminals of the power supply 112 are provided in such a way as to project in the radial direction. When the busbar unit 107 has to be mounted, at the power supply terminals 112, ends 106a of the coils 106, which are pulled out of the stator core 105, are welded. The number of busbars provided in the busbar unit 107 matches the number of phases of the motor 101 (In this case, a total of four busbars are provided, with three for three-phase, phase U, phase V and phase W , and one for connection between the phases). Each coil 106 is electrically connected to a terminal of the power supply 112 corresponding to its phase. After the bus bar unit 107 is assembled, the stator core 105 is pressed and secured to the casing 4.
[00104] Rotor 103 is inserted into stator 102. Rotor 103 includes a rotor shaft 113. The rotor shaft 113 is supported by bearings 114a and 114b in a rotatable manner. Bearing 114a is attached to the center of a lower portion of the liner 4. Bearing 114b is attached to a central portion of the clamp 108. On the rotor shaft 113, a cylindrical rotor core 115 and a rotor (solver rotor) are attached 122 of a solver 121, which is a device for detecting the rotational angle. A stator (solver stator) 123 of solver 121 is housed in a clamp of solver 124, which is made of synthetic resin. The resolver clamp 124 is attached to the inside of clamp 108 with an attachment screw 125.
[00105] The rotor core 115, too, is made by stacking a large number of disc-shaped magnetic steel plates. In the steel sheets that constitute the core of the rotor 115, a plurality of incisions 134 are provided as mounting holes for the magnet. Incisions 134 are curved in an arc. There is space within the incisions 134. The incisions 134 are provided along a circular arc whose center is an imaginary point (not shown) established outside an outer periphery of the rotor 103. Each of the incisions 134 is formed in the rotor in a different way such that a convex side portion of the same faces the center of the rotor 103. The width t2 between an end portion on the outer diameter side 134a of an incision 134 and an outer peripheral edge 115a of the rotor core 115 is configured almost the same the thickness of the magnetic steel sheets.
[00106] If the direction of magnetic flux formed by magnetic poles (or central axis of permanent magnets) is referred to as the geometric axis d, and, if the geometric axis that is magnetically orthogonal to the geometric axis d (axis between permanent magnets) is established as a geometric axis q, a plurality of sets of incisions 134 is provided, with geometric axis q, which is perpendicular to the axis of the rotor 113, as a boundary. In motor 101, four sets of a plurality of incisions 134 are provided in an arc shape. In each set, a plurality of layers of magnetic paths are formed.
[00107] In motor 101, in order to increase the output, a plurality of magnets (permanent magnets) 116 are embedded in the incisions 134. In an area of each magnet 116, a section of the magnetic pole 135 is formed along the circumferential direction . In motor 101, the reluctance torque is considered the main force, and the magnetic torque as the auxiliary force. In this way, cheap ferrite magnets are used as 116 magnets. However, in order to further increase the output, attached neodymium magnets or other rare earth magnets can be used as 116 magnets.
[00108] In the rotor 103, as a plurality of magnets 116 that constitute the sections of the magnetic pole 135, magnets 116s are provided whose outer peripheral sides serve as S poles, and magnets 116n whose outer peripheral sides serve as N poles. Rotor 103 it has a four-pole structure with four sections of magnetic pole 135, and the motor 101 is formed so as to have a structure of 24 slots of four poles. The magnets 116 of each pole are formed in a circular arc, and sets of three magnets are provided along the radial direction. A plurality of geometrical axes d and geometrical axes q is alternately provided in the circumferential direction in the rotor 103. Therefore, it is possible to intensify the torque with the help of the magnetic torque, still making effective use of the reluctance torque.
[00109] In rotor 103, as previously described, the direction of magnetic flux formed by magnetic poles is referred to as the geometric axis d, and the geometric axis that is magnetically orthogonal to the geometric axis d is considered to be the geometric axis q. In rotor 103, a plurality of geometry axes d and geometry axes q is established. In this case, geometric axes d and geometric axes q are alternately provided along the circumferential direction. In the rotor 103, in order to make it easier for the magnetic flow of the geometric axis q to pass, arcuate incisions 134 are provided. In incisions 134, arcuate magnets 116 are embedded. That is, the rotor 103 is formed in such a way as to make it easier for the magnetic flux of the geometric axis q to pass and increase the inductance Lq. Therefore, it is possible to increase the magnetic torque caused by magnets 116 and to obtain sufficient torque even with ferrite magnets.
[00110] In motor 101, the relationship between width in the circumferential direction W1 of the bridge section on the stator side 132 and the distance W2 between the incisions 134 of the rotor core 115 is established in such a way that W1 <W2. In this case, W1 represents the distance between the ends of the two chamfered sections 133 of a bridge section 132. W2 is the distance between adjacent incisions 134 at the same pole, or length in the circumferential direction of a magnetic path section 136 formed between the incisions 134. Since motor 101 has a closed stator structure, fluctuations in the reluctance torque are canceled out, and the torque oscillation is therefore kept relatively low. In addition, the dimensions of motor 101 are established in such a way that W1 <W2, that is, the bridge section on the side of the stator 132 is established in such a way that it is not larger than the magnetic path section on the side of the stator. rotor 136. As a result, fluctuations in the reluctance torque are mild, and the torque oscillation is further reduced.
[00111] FIG. 30 is an explanatory diagram illustrating a torque oscillation reduction operation according to the exposed configurations based on the present invention. FIG. 30A shows the case where W1> W2. FIG. 30B shows the case where W1 <W2, as in the case of the present invention. As shown in FIG. 30A, if W1 and W2 are established in such a way that W1> W2, when state A emerges after rotor 103 is rotated, a magnetic path section 136p of rotor 103 is closer to a left tooth section 109p than which the 136p magnetic path section is facing. Therefore, because of the magnetic flux 1 passing from the tooth section 109p through the magnetic path section 136p, reluctance torque is generated in a direction opposite to the direction of rotation. Then, when state (B) emerges after rotor 103 is rotated (or the state where the center of the magnetic path section on the rotor side 136 meets the center of the bridge section on the stator side 132, and the two are exactly towards each other), the magnetic flux 2 suddenly drops because of an increase in magnetic resistance, and the magnetic flux on the right side 3, which cancels the magnetic flux 2, becomes smaller, too. Even if a change in the magnetic flux value is improved by the closed stator structure, the reluctance torque is rapidly reduced between (A) and (B).
[00112] When state (C) emerges after rotor 103 is additionally rotated, then the section of magnetic path 136p is closer to a section of right tooth 109p. Therefore, magnetic flux 4 that passes from tooth section 109p to magnetic path section 136p is rapidly increased, and reluctance torque is generated in the same direction (forward direction) as the rotational direction. That is, when W1> W2, (a) the reluctance torque in the reverse direction is generated ^ (B) the reluctance torque suddenly drops ^ (C) the reluctance torque in the forward direction is generated. In this way, the direction and magnitude of the reluctance torque changes rapidly. Therefore, still being suppressed by the closed stator structure, the occurrence of torque oscillation is inevitable because of a rapid change in the reluctance torque.
[00113] Contrary to this, as shown in FIG. 30B, when W1 and W2 are established in such a way that W1 <W2, the reluctance torque is generated in a direction opposite to the rotational direction because of the magnetic flux Φ1 in state (a), as in case (a). When state (B) emerges as rotor 103 is rotated, a R-facing portion exists between a tip portion of a tooth section 109 and a magnetic path section 136p of rotor 103 because W2 is greater than W1 in this case. In this way, the magnetic resistance does not fall quickly, and the magnetic fluxes Φ 2 and Φ 3 are greater, compared to case (a). That is, the magnetic flux that enters the portion in the closed stator structure is effectively used, the left magnetic flux Φ 2 and the right magnetic flux Φ 3 are smoothly canceled out by one another, while a change in the magnetic flux value is suppressed.
[00114] When state (C) emerges after rotor 103 is additionally rotated, as in case (a), magnetic flux Φ 4 is generated. At the same time, magnetic flux Φ 5 passing from the tooth section 109p to the magnetic path section 136p remains. Therefore, still being canceled by the magnetic flux Φ 5, the magnetic flux Φ 4 continues to increase, thereby generating slightly reluctance torque in the forward direction. That is, even when W1 <W2, (a) the reluctance torque in the reverse direction is generated ^ (B) the reluctance torque decreases ^ (C) the reluctance torque in the forward direction is generated. However, the left magnetic flux properly cancels the right magnetic flux, leading to a slight change in the direction and magnitude of the reluctance torque. Therefore, the rapid change in the reluctance torque that could occur in the manner described in (a) can be suppressed, resulting in a reduction in torque oscillation. FIG. 31 is an explanatory diagram showing results of experiments by the inventors (compared to the oscillations in FIG. 28). As can be seen from FIG. 31, the motor of the present invention can maintain the torque oscillation less than that of a conventional motor.
[00115] Incidentally, the width in the circumferential direction W1 of the bridge section 132 can vary from zero, or, when the chamfered sections 133 that face each other are connected to each other seamlessly, up to a value equal to the distance between the adjoining tip portions 109a (if chamfered sections 133 are not provided).
[00116] The present invention is not limited to the modalities presented. Needless to say, several changes can be made without departing from the spirit of the invention. For example, the configurations of the first and second modes shown can also be applied to motor 101 of the third mode, or the configuration of the third mode shown can be applied to motors 1 and 51 of the first and second modes.
[00117] Like magnets 26 or 116, bonded or sintered magnets can be used. For example, if the bonded magnets are to be used as magnets 26, a molten magnetic molding material is cast into an incision 25, and a bonded magnetic body is molded into the incision 25 by cooling the material. During the process, in order to have the molecules of the magnetic molding material oriented in the same direction, as shown in FIG. 32, a rotor core 24 is placed inside a rotor production device 201, and the magnetic molding material is poured into the incisions 25. The rotor production device 201 includes a field system device 204 in which magnets field system 202 and magnetic cores 203 are alternately arranged in the circumferential direction. The magnetic flux that is generated by the magnets of the field system 202 adjacent in the circumferential direction is concentrated in the magnetic cores 203 located between the field system magnets 202, before extending on an inner side in the radial direction. In this way, a high magnetic flux magnetic field can be generated in a section of the rotor 205 housing. Therefore, it is possible to generate, in a region X close to the inner side in the radial direction of the rotor core 24, a magnetic field of about of 1 (T), which is necessary to have the molecules of the magnetic material oriented in the same direction.
[00118] Thus, in the core of the rotor 24 which is housed in the device of the field system 204, the magnetic field can be applied throughout the region in the radial direction. When the magnetic molding material of the bonded magnetic body is poured into each incision 25, it is possible to have the molecules of the bonded magnetic body oriented in the same direction throughout the region in the radial direction. Therefore, when the attached magnetic body is magnetized after the molecules are oriented, it is possible to provide a magnet 26 with a desired magnetic force. In this case, even in a rotor of a multilayer IPM structure like the one described in the present modality, the molecules can be reliably oriented in the same direction even towards a connected magnetic body that is poured into an incision 25 located in an innermost layer in the radial direction. . In this way, it is possible to suppress the variation of the magnetic force between the magnets 26 formed in the incisions 25.
[00119] Furthermore, the brushless motor of the present invention can be applied not only to an electrically assisted steering device but to other electrical machinery or equipment in hybrid or electric cars or the like. EXPLANATION OF REFERENCE SYMBOLS 1: Brushless motor 2: Stator 3: Rotor 4: Motor casing 4a: Bottom section 5: Stator core 6: Stator coil 6a: End 7: Bus bar unit 8: Clamp 11: External stator 12: Internal stator 13: Tooth section 14: Bridge section 15: Slot 16: Tooth mounting groove 17: Plug-in section 21: Power supply terminal 22: Rotor shaft 23a, 23b: Bearing 24: Rotor core 25: Incision (mounting hole) 25a to 25c: Incision 26: Magnet 26a: Inner layer magnet 26b: Middle layer magnet 26c: Outer layer magnet 26n: pole magnet N 265: pole magnet S 266: Solver 267: Solver rotor 268: Cover 269: Control panel 270: Control panel 271: Power system element 272: Control system element 273: Solver stator 41: Outer peripheral portion 42: Space 43 : Magnet 51: Brushless motor 52: Conical section 53: Magnetic flow control section M1, M2: Line center N1, N2: Pole zone N S1, S2: Pole zone S Os: Center point of the pole magnet S On: Center point of the pole magnet N Or: Center point of the rotor Rs: Distance from the center of the magnet (Os -Or) Rn: Distance from the center of the magnet (On-Or) Ls: Distance from the magnet to the innermost layer Ln: Distance from the innermost magnet Oec: Eccentric point Lec: Eccentric distance P: Limit point Q: External position Rec: Eccentric radius Rmax: Distance from the outermost rotor position (Q-Or) Tr: Reluctance torque Tm: Magnetic torque Tt: Output torque 101: Brushless motor 102: Stator 103: Rotor 104: Motor casing 105: Stator core 106: Stator coil 106a: Coil end 107: Bus bar unit 108: Clamp 109: Tooth section 109a: Tooth tip portion 109p, 109q: Tooth section 111: Insulating 112: Source terminal supply 113: Rotor shaft 114a, 114b: Bearing 115: Rotor core 115a: Outer peripheral edge 116: Magnet 116n: N-pole magnet 1165: Pole magnet S 121: Resolver 122: Resolver rotor 123: Resolver stator 124: Resolver clamp 125: Attachment screw 131: Slot 131a: Inner surface 132: Bridge section 133: Bevel section 134: Bridge incision 134a: Portion end side with outside diameter 135: Magnetic pole section 136: Magnetic path section 136p: Magnetic path section R: Confronting portion W1: Length in the circumferential direction of the section of W2: Distance between incisions in sections of the magnetic pole of the same polarity t1: Width in the radial direction of the bridge section t2: Width between the end portion on the side of the incision outside diameter and the outer peripheral edge of the rotor core 15a θ: central angle of tooth section 201: Rotor production device 202: Field system magnet 203: Magnetic core 204: Field system device 205: Rotor housing section

权利要求:
Claims (13)
[0001]
1. Brushless motor (1) which includes a stator (2) which includes windings of a plurality of phases, and a rotor (3) which is arranged inside the stator (2) in a rotatable manner and which includes a plurality of holes internal mounting brackets (25) in which a plurality of permanent magnets (26) are embedded, in which a magnetic flux direction formed by each of the magnetic poles of the plurality of permanent magnets (26) is established as a geometric axis d, a geometric axis which is magnetically orthogonal to the geometric axis d is established as the geometric axis q, a plurality of the geometric axes of q is alternately provided in a circumferential direction in the rotor (3), and the rotor (3) is rotated by the reluctance torque generated by a difference in the magnetic resistance between directions of the geometric axis and of the geometric axis q and by the magnetic torque generated by the permanent magnets (26), in which: the plurality of permanent magnets (26) includes permanent magnets that are of section tr arcuate ansversal and form a first magnetic pole which is the N or S pole, and permanent magnets (26) which are arcuate in cross section and form a second magnetic pole which is of different polarity than the first magnetic pole and which is located circumferentially adjacent to the first magnetic pole; each of the permanent magnets (26) that form the first and second magnetic poles is embedded in the rotor (3) in such a way that a convex side portion of them faces a center of the rotor (3); the brushless motor (1) being characterized by the fact that: when a cross section of the rotor (3) is equally divided into regions by central lines (M1, M2) that are perpendicular to each other and serve as lines of distinction for each region, and each of the geometric axes d belongs to a region, the permanent magnets (26) innermost on the side of the first magnetic pole are arranged in such a way as to stand out in a region on the side of the second magnetic pole without interfering with the magnets (26) on the side of the second magnetic pole.
[0002]
2. Brushless motor (1), according to claim 1, characterized by the fact that: a plurality of magnetic magnets (26) that form the first and second magnetic poles is embedded in the rotor (3); the permanent magnets (26) that form the first magnetic pole are arranged in layers around a first common central point that is located outside the rotor (3); the permanent magnets (26) that form the second magnetic pole are arranged in layers around a second central common point that is located outside the rotor (3); and, the first and second center points are arranged in such a way that the distance between the first center point and a center of rotation of the rotor (3) is different from a distance between the second center point and the center of rotation of the rotor (3) .
[0003]
3. Brushless motor (1), according to claim 2, characterized by the fact that: when the number of magnetic poles is four, a distance ratio (Rs) between the first central point and the center of rotation of the rotor (3) for the distance (Rn) between the second central point and the center of rotation of the rotor (3) is 0.92 (Rs / Rn = 0.92).
[0004]
4. Brushless motor (1), according to claim 1, characterized by the fact that: a plurality of permanent magnets (26) forming the first and second magnetic poles is embedded in the rotor (3); the plurality of permanent magnets (26) that form the first magnetic pole have the same radius as a plurality of permanent magnets (26) that form the second magnetic pole, and the permanent magnets are arranged around different central positions that are located outside the rotor (3); and, radius centers of the permanent magnets (26) are arranged in such a way that the distance between the center of the radius of the permanent magnets that form the first magnetic pole and the center of rotation of the rotor (3) is different from a distance between the center of the radius of the permanent magnets that form the second magnetic pole and the center of rotation of the rotor (3).
[0005]
5. Brushless motor (1), according to claim 1, characterized by the fact that: a plurality of permanent magnets (26) forming the first and second magnetic poles is embedded in the rotor (3); the permanent magnets that form the first magnetic pole are layered around a first common central point that is located outside the rotor (3); the permanent magnets that form the second magnetic pole are layered around a second central common point that is located outside the rotor (3); and, the first and second center points are arranged in such a way that the distance between the first center point and a center of rotation of the rotor (3) is equal to the distance between the second center point and the center of rotation of the rotor (3 ), and the permanent magnets that make up the first magnetic pole have a different radius than the permanent magnets that make up the second magnetic pole.
[0006]
6. Brushless motor (1), according to claim 1, characterized by the fact that: the stator (2) includes a plurality of tooth sections (109), which protrude on an internal side in the radial direction, and a coil (106), which is wound on the tooth sections (109) through slits (131) formed between the tooth sections (109), and a bridge section (132), which is provided on the tip portions of the inner side in the radial direction of the tooth sections (109) to connect the adjacent tip portions (109a) to each other; and, if the length in the circumferential direction of the bridge section (132) is represented by W1, and a distance between the incisions in the section of the magnetic pole of the same polarity by W2, W2 is established in such a way not to be less than W1 (W1 ≤ W2).
[0007]
7. Brushless motor (1) according to claim 1, characterized by the fact that: the magnet mounting holes are arranged in layers in the radial direction at the first and second magnetic poles; and, an end portion of the magnet mounting hole that is disposed in an outermost layer of the first magnetic pole contains a magnetic flow control section (53) that controls the value of the magnetic flux that passes between the mounting holes of the magnet magnet on the magnetic pole.
[0008]
8. Brushless motor (1) according to claim 7, characterized in that: an end portion in the longitudinal direction of the magnet mounting hole in the outermost layer contains a tapered section (52), which is made forming a periphery of the magnet mounting hole in a straight line; and, the magnetic flow control section (53) is formed between the conical section (52) and another magnet mounting hole which is disposed adjacent to an inner side of the mounting hole of the outermost layer of the magnet.
[0009]
9. Brushless motor (1) according to claim 7 or 8, characterized by the fact that: a base point of the conical section (52) is located outside the angle of the pole arc α of the magnet housed in the bore of mounting the outermost layer of the magnet and within the opening angle β of the magnet mounting hole of the outermost layer.
[0010]
10. Brushless motor (1) according to any one of claims 7 to 9, characterized by the fact that in the conical section (52), the taper angle θt formed by the line A extending along the conical section (52) and line B at a position of an end portion of the magnet housed in the magnet mounting hole of the outermost layer is greater than 0 degrees and less than 90 degrees (0 degrees <θt <90 degrees).
[0011]
11. Brushless motor (1), according to claim 10, characterized by the fact that the taper angle θt is between 68 degrees and 72 degrees.
[0012]
Brushless motor (1) according to any one of claims 7 to 12, characterized by the fact that: regardless of whether the magnet mounting holes are for the first or second magnetic pole, the magnet mounting holes are formed along the radial direction in such a way as to have the same radius in the same layer.
[0013]
13. Brushless motor (1) according to any one of claims 1 to 12, characterized in that the brushless motor (1) is used as a drive source for an electrically assisted steering device.

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同族专利:

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公开号 | 公开日

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US20150303749A1|2015-10-22|

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BR112015003256A2|2018-04-24|

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EP2887503B1|2018-11-14|

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CN104508948A|2015-04-08|

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CN104508948B|2017-08-25|

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EP2887503A1|2015-06-24|

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EP2887503A4|2016-06-22|

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US9490673B2|2016-11-08|

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WO2014027630A1|2014-02-20|

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法律状态:
2018-11-21| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|

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2019-12-31| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|

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2021-03-09| B09A| Decision: intention to grant|

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2021-03-30| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 10/08/2013, OBSERVADAS AS CONDICOES LEGAIS. |

优先权:

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申请号 | 申请日 | 专利标题

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JP2012-180357|2012-08-16|

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JP2012180357A|JP5975786B2|2012-08-16|2012-08-16|Magnet-assisted reluctance motor rotor and brushless motor|

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JP2012-244733|2012-11-06|

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JP2012244733A|JP2014093914A|2012-11-06|2012-11-06|Brushless motor|

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PCT/JP2013/071738|WO2014027630A1|2012-08-16|2013-08-10|Rotor for use in magnet-assisted reluctance motor, and brushless motor|

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