• 专利附录
  • 专利说明
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  • 类似技术
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    • 专利摘要:
    The invention relates to means for measuring a fluid level in a tank, for example a level of an aqueous solution of urea in a tank for catalytic converters of combustion engines. The measuring means comprise: at least one sensor comprising a capacitive element electrically coupled to an oscillator configured to deliver a signal Si whose frequency FiPAD is a function of the capacity of the capacitive element; said at least one sensor being intended to be disposed outside the reservoir, so that the capacitance of the capacitive element varies as a function of the level n of the fluid, when said level is between a first hi-min threshold and a second hi-max threshold; A processing module, coupled to said at least one sensor, and configured to determine the level n of fluid in the reservoir as a function of the frequency of the signal Si.
    公开号:FR3040484A1
    申请号:FR1557947
    申请日:2015-08-26
    公开日:2017-03-03
    发明作者:Regis Munoz
    申请人:MGI Coutier SA；
    IPC主号:
    专利说明:

    Non-contact measuring device of a level in a tank
    Introduction
    The present invention relates to the field of systems for storing and pressurizing / feeding a fluid. Such systems are used for various purposes in private motor vehicles, heavy goods vehicles, agricultural machinery, and construction machinery and machines.
    In particular, the invention relates to means for measuring a fluid level in such systems, for example a level of an aqueous solution of urea (a commercial name of which is "AdBlue®"), in a storage system for catalytic converters of combustion engines.
    Prior art
    Catalysts using the principle of selective catalytic reduction to reduce emissions of nitrogen oxides (NOx), generally include a storage system adapted to contain a fluid composed mainly of urea and water (a trade name is " AdBlue® "). When the catalyst is in active operation, the fluid is brought into contact with the gases resulting from the combustion of the fuel in the engine of the vehicle, so as to allow the transformation of the nitrogen oxides into nitrogen and water.
    It is desirable to have reliable means for measuring a fluid level in the storage system, for example to provide the information necessary for a gauge capable of indicating the current fluid level in the pressurized storage system and trigger an alert when this level is insufficient to ensure the proper operation of the catalyst.
    Various solutions are now implemented to try to provide measurement solutions. Thus, it is known to employ mechanical devices, for example floats, introduced into the chamber of the storage system containing the fluid. The reliability of the information produced by these mechanical measuring devices is limited by the sensitivity to dispersions of the fluid. In addition, in case of freezing of the fluid - the aqueous solutions of urea freeze at about -11 ° C - the mechanical devices are inoperative, because of the immobility imposed on the floats. Finally, the mechanical devices are generally bulky.
    It is also known to employ measuring devices comprising an ultrasonic source such as a ceramic capsule or a piezoelectric component. However, in addition to the impossibility of obtaining a measurement of the fluid level in the event of freezing of the latter, the cost of this solution proves to be high.
    Another solution is to use a level measuring device based on the measurement of electrical capacitance variations. There are devices in contact with the fluid comprising a measuring circuit -typically an integrated circuit - provided with a capacitive sensor, inserted into a protective sleeve itself immersed in the storage system. To ensure the capacitive coupling between the sensor and the liquid, through the sheath, a capacitive transmission element, for example a gel, is required. This solution is therefore difficult to produce because, in addition to the complexity of assembly, it is necessary that the walls of the sheath are thin to allow the measurement of the capacity, and built in a material adapted to both the immersion in the aqueous solution of urea and the measurement of the capacity through said walls. These devices finally require managing a seal to separate the wet zone from the dry zone, at the interface between the reservoir and the measuring device.
    There is therefore still a need for alternative means for measuring a fluid level, in a fluid storage system, not requiring the use of additional elements in contact with said fluid, while being reliable and inexpensive to produce and implement. Summary of the invention
    One of the objects of the invention is to provide effective means for determining a fluid level, in a fluid storage system, not requiring the use of additional elements in contact with said fluid, while being reliable and little expensive to produce and implement. Another object of the invention is to allow the determination of a level of fluid contained in a container whose thermoplastic walls - for example, high density polyethylene, polyethylene, polypropylene, or polyoxymethylene - have a lower thickness or equal to substantially 5 mm, and through an air gap whose thickness can reach up to substantially 3 mm. Another object of the invention is to allow the determination of a fluid level included in a container, without however requiring the use of a conductivity gel between the wall of the container and the measuring means. Another object of the invention is to provide means that do not require the use of elements whose manufacture and assembly prove complex, for example the sleeves used in the devices of the prior art for containing sensors. Another object of the invention is to provide means for measuring a fluid level in a container adapted to be disposed outside said container, without contact with the fluid, and without contact with the container.
    One or more of these objects are filled by the one-level measuring device, the kits and the one-level measuring method according to the independent claims. The dependent claims further provide solutions to these objects and / or other advantages.
    More particularly, according to a first aspect, the invention relates to a measuring device for cooperating with a reservoir adapted to contain a fluid. The device is adapted to determine a level n of the fluid, along a vertical axis NM of said reservoir. The device comprises: at least one sensor comprising a capacitive element electrically coupled to an oscillator configured to deliver a signal Si whose frequency F i pad is a function of the capacitance of the capacitive element; said at least one sensor being intended to be disposed outside the reservoir, so that the capacity of the capacitive element varies as a function of the level n of the fluid, when said level is between a first threshold hi.min and a second threshold hi.max; A processing module, coupled to said at least one sensor, and configured to determine the level n of fluid in the tank as a function of the frequency of the signal S i.
    The processing module can be configured to determine the level n of fluid in the tank according to the frequency of the signal S, and a reference frequency FjVco specific to said at least one sensor.
    The processing module can be configured to determine the reference frequency FiVco, in an initial calibration phase, and / or periodically-for example every week-, and / or during the occurrence of an event, for example after identification. potential measurement errors, and / or upon receipt of a command, for example from a user via a user interface or another system. Such an operation also makes it possible to calibrate the measuring device, throughout its lifetime, in order to compensate for the potential drift of the electronic components and aging / deformation of the tank. The reference frequency FjVco may be equal to the frequency of the signal Si delivered by the oscillator of said at least one sensor when the fluid level is below the threshold hj.mjn.
    In one embodiment, the processing module is coupled to an external module: by a communication module, able to allow transmission of the level n of fluid in the reservoir to the external module; and / or • by a power supply module, able to allow a transmission of energy from the external module to said at least one sensor.
    Typically, the plug-in can be a motherboard.
    In one embodiment, the processing module comprises a diagnostic module configured for: when the level n of fluid determined by the processing module is less than the first threshold hj.mjn, identifying a malfunction if the difference between the frequency F pad of the signal Si and a first reference frequency is substantially non-zero; When the level n of fluid determined by the processing module is greater than the second threshold hj.max, identifying a malfunction if the difference between the frequency F ipad of the signal S, and a second reference frequency is substantially non-zero.
    The first reference frequency may be equal to the frequency of the signal S, delivered by the oscillator of said at least one sensor when the fluid level is below the threshold hj.mjn, for example when the reservoir is empty. The first reference frequency can be determined during a calibration phase by measuring the frequency of the signal S, or be predetermined. The second reference frequency may be equal to the frequency of the signal S, delivered by the oscillator of said at least one sensor when the level of the fluid is greater than the second threshold hi.max, for example when the reservoir is full of fluid. The second reference frequency can be determined during a calibration phase by measuring the frequency of the signal Si or be predetermined.
    In one embodiment, the processing module comprises: a voltage controlled reference oscillator configured to produce a signal whose frequency FiVco varies as a function of a control signal; A microprocessor configured to generate and deliver to the reference oscillator the control signal so that the frequency F, vco of the signal produced by the reference oscillator substantially corresponds to the own reference frequency of said at least one sensor; A phase-locked loop configured to generate an output signal Ai as a function of the difference between the frequency F, pad of the signal S, delivered by the at least one sensor and the reference frequency F, vco; An output filter, coupled to the output of the phase-locked loop, adapted to convert the phase-shift signal Ai into output voltage Uj; A conversion module configured to determine the level n as a function of the output voltage Uj.
    The processing module may comprise a diagnostic module configured for: when the level n of fluid determined by the conversion module is less than the first threshold hj.mjn, identifying a malfunction if the difference between the output voltage Uj and a first Udec reference voltage is substantially non-zero; When the level n of fluid determined by the conversion module is greater than the second threshold hj.max, identifying a malfunction if the difference between the output voltage Uj and a second reference voltage Urec is substantially non-zero.
    The first reference voltage Udec may be equal to the voltage U, measured for the ith sensor when the fluid level n determined by the conversion module is lower than the first threshold hj.mjn, for example when the reservoir is empty. The first reference voltage Udec can be determined during a calibration phase by measuring the voltage Uj for the ith sensor or be predetermined. The second reference voltage Urec may be equal to the voltage Uj measured for the ith sensor when the level n of fluid determined by the conversion module is greater than the second threshold hj.max, for example when the tank is full. The second reference voltage Urec can be determined during a calibration phase by measuring the voltage Uj for the ith sensor or be predetermined.
    The measuring device may also comprise at least one second sensor comprising a second capacitive element electrically coupled to a second oscillator configured to deliver a second signal whose frequency is a function of the capacitance of the second capacitive element. Said at least one second sensor is intended to be disposed outside the reservoir, so that the capacity of the second capacitive element varies as a function of the level n of the fluid, when said level is between a third threshold hj.mjn and a fourth threshold hi.max. The processing module is coupled to said at least one second sensor, and is configured to determine the level n of fluid in the reservoir as a function of the frequency of the signal Si of said at least one first sensor and the frequency of the signal Si of said at least one a second sensor. In one embodiment, the range of values defined by the third threshold and the fourth threshold is disjoint from the range of values defined by the first threshold and the second threshold. Thus, it is possible to cover the case where it is necessary to know the level n only when the latter is close to certain values, for example only when the level n is between 0 and 5 cm and between 15 and 20 cm. The third threshold may be lower than the second threshold. When the third threshold is lower than the second threshold, the processing module may comprise a diagnostic module configured for, when the level n of fluid determined by the conversion module is between the third threshold and the second threshold, identifying a malfunction if the absolute value of the difference between, on the one hand, the level n of fluid determined by the processing module from the signal S1 of the said at least one second sensor and, on the other hand, the level n of fluid determined by the treatment module at from the signal Si of said at least one sensor is greater than a permissible deviation. For example, the allowable deviation can be chosen and / or configured according to the measurement accuracy, theoretical or measured during a calibration step, for each sensor.
    According to a second aspect, the invention relates to a kit comprising a measuring device according to the first aspect and a reservoir intended to be assembled so that a space is reserved between the surface of the capacitive element of said at least one sensor and the tank wall. The kit may also comprise an aqueous urea solution intended to be contained in the reservoir. The reservoir may also be adapted to contain other types of fluids, for example a fuel, a fuel, a coolant, a cleaning liquid, a lubricant, a coolant, etc.
    According to a third aspect, the invention relates to a kit comprising a measuring device according to the first aspect, and an external module, for example a motherboard, configured to receive the level n of fluid in the reservoir and / or to allow a power transmission to said at least one sensor.
    According to a fourth aspect, the invention relates to a method for measuring a level n of fluid contained in a reservoir, along a vertical axis NM of said reservoir. The method is particularly adapted to be implemented by the device according to the first aspect. The method comprises the following steps: • collecting at least one signal S, delivered by a sensor, the sensor comprising a capacitive element electrically coupled to an oscillator configured to deliver a signal S, whose frequency F, pad is a function of the capacitance of the capacitive element; said at least one sensor being intended to be disposed outside the tank, so that the capacitance of the capacitive element varies as a function of the level n of the fluid, when said level is between a first threshold hj.min and a second threshold hj.max; • calculate the difference between the frequency of the signal Si and a reference frequency FiVco; • determine the level n of fluid in the tank according to the frequency of the signal Si.
    The method may further comprise the following steps: when the determined level n of fluid is lower than the first threshold h ,, min, identifying a malfunction if the difference between the frequency F ipad signal S, and a first reference frequency is substantially no nothing; When the level n of determined fluid is greater than the second threshold hi.max, identifying a malfunction if the difference between the frequency FjpAD of the signal S, and a second reference frequency is substantially non-zero.
    In one embodiment, at least one second signal Sj delivered by a second sensor is collected. The second sensor comprises a capacitive element electrically coupled to an oscillator configured to deliver a second signal S, whose frequency Pad Pad is a function of the capacity of the capacitive element. Said at least one second sensor is intended to be disposed outside the tank, so that the capacity of the capacitive element varies according to the level n of the fluid, when said level is between a third threshold hi.min and a fourth threshold hi.max. The third threshold is lower than the second threshold. The level n of fluid is determined in the reservoir according to the frequency of the signal Si of said at least one sensor and the frequency of the signal Si of said at least one second sensor. When the level n of fluid determined during the step of determining the level n of fluid is between the third threshold and the second threshold, the method further comprises the step of: identifying a malfunction if the absolute value of the difference between, on the one hand, the level n of fluid determined from the signal S1 of the said at least one second sensor and, on the other hand, the level n of fluid determined from the signal S1 of the said at least one sensor, which is greater than a permissible deviation .
    BRIEF DESCRIPTION OF THE FIGURES Other features and advantages of the present invention will become apparent from the following description of embodiments with reference to the accompanying drawings, in which: FIG. 1 is a cross-section of a measuring device of FIG. a fluid level in a storage system, according to an embodiment of the invention; Figure 2 is a block diagram of one of the sensors used in the measuring device; Figure 3 is a schematic three-dimensional view of a measuring device, according to one embodiment of the invention; FIG. 4 is a schematic view illustrating the physical principle of measurement implemented by the measuring device according to the invention; Figure 5 is a block diagram of an electrical measuring circuit of the measuring device according to one embodiment of the invention; FIG. 6a is a diagram illustrating the level measurement range specific to each sensor of the measuring device; FIG. 6b is a diagram showing a theoretical curve describing the frequency observed by a sensor as a function of the fluid level in the storage system; FIG. 6c is a diagram representing a theoretical curve describing the voltage delivered by the electric measuring circuit when the latter takes into account the frequency observed by one of the sensors, as a function of the fluid level in the storage system; FIG. 7 is a diagram representing theoretical curves describing the voltage delivered by the electrical measuring circuit when the latter takes into account the frequency observed for each sensor, as a function of the fluid level in the storage system; FIG. 8 is a diagram representing theoretical curves describing the voltage, delivered by the electrical measurement circuit, according to an embodiment in which the number of sensors is equal to 11, each sensor being adapted to measure the fluid level on a wide range of 24 mm; FIG. 9 is a block diagram of the steps of a method for measuring a fluid level in a storage system, according to one embodiment of the invention; FIG. 10 is a diagram representing theoretical curves describing the voltage delivered by the electrical measuring circuit when the latter takes into account the frequency observed for each sensor, as well as examples of voltage values measured by the sensors, as a function of the fluid level in the storage system, when the latter is included in one of the overlapping ranges of two adjacent sensors; FIG. 11 is a diagram representing theoretical curves describing the voltage delivered by the electrical measuring circuit when the latter takes into account the frequency observed for each sensor, as well as examples of voltage values measured by the sensors, as a function of the fluid level in the storage system, when the latter is located outside the overlapping ranges of the adjacent sensors; FIG. 12 is a block diagram of the steps of a diagnostic method according to the invention for checking the coherence of the signals delivered by the sensors.
    detailed description
    With reference to FIGS. 1, 2 and 3, a device for measuring a level n of fluid along an axis NM of a reservoir, according to one embodiment of the invention, will now be described. The measuring device is adapted to measure the level n of a fluid 1 along the axis NM of a reservoir 2, without contact with said fluid 1. Typically, the axis NM is the vertical axis of the reservoir 2, and the level n then corresponds to the height of the fluid 1 in the tank 2. A possible, but not exclusive, use of the measuring device is the determination of a level of an aqueous solution of urea (a commercial name of which is " AdBlue® "), in a storage system for catalytic converters for combustion engines. However, the measuring device according to the invention is also suitable for measuring the level of other types of fluids contained in various types of fluid storage systems, such as, for example, windshield washer fluid, fuel oil, oil, water, glycol.
    The measuring device comprises a detection circuit 10 -typically an electronic card - on which a number nc of sensors 12 is arranged. The number nc is chosen as a function of the variations of the level n which can be measured as well as of the desired accuracy. In the example illustrated in FIG. 1, the detection circuit 10 has a number nc = 4 of sensors 12. However, the number nc can also be equal to 1, a single sensor 12 being sufficient to determine the level n if the n-level variations that can be measured are limited and / or if the level n should be measured only for a predetermined range of values. In the remainder of the description, the number i refers to the ith sensor of the electronic card, i being between 1 and nc. Also, the ieme sensor 12 outputs a signal S, electrical. As illustrated in FIG. 6a, each sensor 12 is designed and arranged to allow measurement of the level n when the latter is within a predetermined value range. Thus, the ith sensor 12 makes it possible to measure the level n when the latter is within a determined range Pi [hj-min · · hi-max]. For example, if the level n can vary between 0 and 20 cm in the tank 2, the number nc of sensors 12 can be chosen equal to 11, each sensor being adapted to measure the level n over a wide range of 24 mm. The P2 range of the second sensor may be [18 mm .. 42 mm]. Thus the second sensor 12 will measure the level n when the latter is between 1.8 and 4.2 cm.
    In one embodiment, illustrated in FIG. 7, the predetermined value range P of each sensor 12 partially overlaps the ranges Pm; Pi + i of predetermined values of the adjacent sensors 12. Thus, taking for example the ieme and i + 1eme sensors 12 which are associated respectively the range Pj [hi.min ... hLmax] and the range Pi + i [hi + i.min ... hi + i- max], the overlap range Rj then corresponds to [hj + i.mjn ... hj.max] with hi + i.min <hj. max. For example, if the level n can vary between 0 and 20 cm in the tank 2, and the number nc of sensors 12 is chosen equal to 11, considering a range P2 equal to [18 mm. P3 range equal to [36 mm ... 60 mm], the recovery range R2 will be equal to [36 mm ... 42 mm].
    The ranges do not necessarily cover all possible level values, but may only cover a critical area. For example it can be expected to measure the value of the level only if the latter is greater than or equal to 10 cm.
    Alternatively, each sensor 12 may be arranged so that the P ranges are substantially adjacent.
    Alternatively, each sensor 12 may be further arranged so that the P ranges are disjoint, especially if it is not necessary to measure the value of the level n for certain ranges of values. For example, the case may occur when it is necessary to know the level n only when the latter is close to certain values, for example only when the level n is between 0 and 5 cm and between 15 and 20 cm.
    The detection circuit 10 further comprises a processing module 14, coupled to the sensors 12, and configured to collect the signals S 1. The detection circuit 10, and in particular its processing module 14, are adapted to be coupled to a motherboard 16 via a communication module 18. The motherboard 16 is external to the measuring device, and can for example be shared with other external devices. The communication module 18 is in particular configured to establish a data link between the motherboard 16 and the processing module 14 of the detection circuit 10. It is then possible to transmit the value of the level n and / or the nc levels n , as measured by each sensor 12 and determined (s) by the processing module 14 to the motherboard 16. The detection circuit 10 further comprises a power supply module 20 configured to receive power from the motherboard 16 and supplying the components of the detection circuit 10. The supply module 20 may comprise wire means for transmitting the energy.
    In an advantageous embodiment, shown in FIGS. 1 and 3, the communication module 18 comprises radio transmission means, for example radio-identification means, more often referred to by the English acronym "RFID" for " radio frequency identification ". The radio-identification means may comprise a first induction loop 22 disposed on the detection circuit 10, electromagnetically coupled to a second induction loop 24 disposed on the motherboard 16. The supply module 20 may then be configured to receive by means of the first induction loop 22 the energy transmitted by the second induction loop 24 of the motherboard 16.
    As illustrated in FIG. 2, each sensor 12 comprises a voltage oscillator 40 coupled to a capacitive element 28. More particularly, the capacitive element 28 may take the form of a block (or "pad" in English) comprising a zone central conductive 30 around which a conductive peripheral zone 34 is disposed. An insulating zone 32 separates the central conductive zone 30 from the peripheral zone 34. The peripheral zone 34 is intended to be maintained at a neutral potential, typically 0 volts. The conductive central zone 30 as well as the peripheral zone 34 may be formed by deposition of an electrical conductor on a surface of the detection circuit 10, for example by deposition of copper. Each block therefore forms an air capacitor or open plate. The conductive central zone 30 and the peripheral zone 34 of the block are electrically coupled to the oscillator 40, so that a variation in the capacitance of the block produces a variation in the frequency of the signal S 1.
    In one embodiment, each oscillator 40 is formed by an inverting logic gate with a Schmitt trigger input, thus making it possible to produce a signal S whose frequency has a good stability, typically whose variation is less than 0.05% Hz / ° C. In the present application, each oscillator 40 has an input capacitance whose value is less than or equal to substantially 5 μF and a bandwidth greater than substantially 5 MHz. Depending on the cost of the electronic components and the space available, it is possible to choose the components of the oscillator 40 from the following non-exhaustive list: oscillators with transistor (s), oscillators with operational amplifier, Colpitts, Clapp, Hartley, Quartz, Wien bridge, logic gate. Typically, the components chosen for the oscillators 40 have the following characteristics: a high immunity to noise, a very low input capacitance, a high input resistance. The sensors 12 can therefore be assembled using components at very low cost.
    As shown in FIG. 2, the detection circuit 10 can be arranged facing the reservoir 2 so that the longitudinal axis CD (shown in FIG 2) of the block of each sensor 12 is substantially parallel to the NM axis of the reservoir 2. Alternatively in other configurations not shown in the figures, the angle formed by the axes NM and CD may be non-zero. During the calibration phase described later, the influence on the measurements made by the sensors of a non-zero angle between the NM and CD axes on the sensors is then taken into consideration.
    A space I between the surface of the sensors 12 and the wall of the tank 2 facing the sensors is reserved, so as to form an air gap. For optimum operation, in the case of a tank whose walls are made of thermoplastic material - for example, high density polyethylene, polyethylene, polypropylene, or polyoxymethylene - and whose thickness e is less than or equal to substantially 5 mm, the space I of the air space must be substantially less than or equal to 3 mm.
    With particular reference to FIG. 4, the physical principle of measurement implemented by the measuring device according to the invention will now be described. The measurement of the level n along the NM axis in the tank 2 is obtained by the measuring device by observing the frequency variations of the signals S, delivered by the sensors 12, said variations being a function of the level n. Indeed, the capacitance C of the capacitive element 28 of each sensor 12 is a function of the dielectric constants of the materials present between the surfaces of the conductive central zone 30 and of the peripheral zone 34 (the electric field lines are represented for one of the sensors 12 in Figure 4). The capacitance C therefore varies as a function of the dielectric constants of the air present between the capacitive element 28 and the wall of the tank 2, the material of the walls of the tank 2, and the possible presence of the fluid or gas / vacuum contained in the tank 2 for measuring range Pj. The distance I between the sensor and the wall of the reservoir being constant and the thickness of the tank wall, only the level n of fluid in the reservoir has a significant influence on the overall dielectric constant as observed by the sensor 12 The capacitance C of the capacitive element 28 thus being modified as a function of the level n of fluid, the frequency of the signal S, corresponding from the ith sensor 12 also varies as a function of the level n. For example, if the frequency of the corresponding signal from the sensor 12 is greater than or equal to 1 MHz, the variation observed will typically be between 0 and 20 Hertz. The level n of fluid 1 in the tank 2 is then determined by comparing the frequency of the signals S, at reference frequencies. The reference frequency may be specific to each sensor 12. For example, the reference frequency of the ith sensor 12 may be chosen equal to the frequency of the signal Si delivered by the oscillator of the ith sensor 12, when the level n of the fluid is lower than hj. min. Reference frequencies can be determined during a calibration phase. The calibration phase can be performed for the measuring device itself without external intervention. The calibration phase can be performed during the installation of the measuring device.
    Referring to Figures 5, 6a, 6b, 6c, and 7, the processing module 14 according to one embodiment of the invention and its operation will now be described. The processing module 14 comprises a microprocessor 50 coupled to an input 51 for receiving a power supply. The processing module 14 is configured to implement the principle of the phase-locked loop coupled to a reference oscillator for determining the frequency variations of the signal Si of the sensors 12, produced by the variations of the level n of fluid.
    The processing module 14 comprises a phase-locked loop 58, generally designated by the acronym "PLL" for "Phase-Locked Loop", activated by the microprocessor 50. The microprocessor 50 is provided with a selector module 52. The selector module 52 makes it possible, successively, to couple the output of the oscillator 40 of each of the different sensors 12 to the phase-locked loop 58. In the rest of the description, the signal Si, selected at a time t given by the selector module 52 is designated Padpad · The frequency of the signal Si, selected at a given instant t, by the selector module 52 is designated padpad ·
    The processing module 14 comprises a voltage-controlled oscillator 54, acting as a reference oscillator, able to produce a signal at a variable frequency, as a function of a control signal generated by a generator 56. The controlled oscillator voltage 54 is coupled to the phase locked loop 58. The generator 56 may be a pulse width modulated signal generator - more generally referred to by the acronym "PWM" for ( "Pulse Width Modulation"), driven by the microprocessor 50. The generator 56 may be a digital to analog converter, driven by the microprocessor 50, to produce the control signal. The control signal is then converted into voltage by an RC filter 59. The frequency F, vco of the signal produced by the voltage controlled oscillator 54 is predetermined for each of the sensors 12, during a calibration phase, in the no fluid 1 in the reservoir 2. Thus, the microprocessor 50 is configured to drive the generator 56 so that the voltage controlled oscillator 54 delivers a signal whose frequency Fjvco corresponds to the predetermined frequency Fcal during the calibration phase for the oscillator 40 currently selected by the selector module 52.
    The phase-locked loop 58 is configured to generate an output signal Ai, as a function of the difference between the frequency FjPAD of the signal Sipad currently selected by the selector module 52 and the frequency Fjvco of the signal produced by the voltage-controlled oscillator. 54. The output signal Ai is therefore a function of the difference Fjvco - FjPAD. The two frequencies Fjvco, FjPAD being sufficiently close, the output signal Ai corresponds to a phase shift signal (in the digital domain, a duty cycle), and can therefore be converted into voltage Uj by an output filter RC 60 coupled to the output of the phase lock loop 58. The voltage Uj is then digitized by the microprocessor 50 using an analog digital converter 62. Using the selector module 52, the microprocessor 50 reads successively the value of the voltage Uj for each sensor 12 of the detection circuit 10 and records the corresponding values.
    The microprocessor 50 further includes a conversion module 63 adapted to convert voltages Uj collected for each sensor 12 into the level n of the fluid in the tank 2. An example of the conversion tables of the voltages U, in level n is given on the diagrams of the FIGS. 6c, 7 and 8. The level n can be transmitted on an output 64. Alternatively, the nc values of the levels n, as measured by each of the sensors 12 can be transmitted on the output 64.
    Reference is now made to FIG. 9 describing by a block diagram the steps of a method for measuring a level n of fluid contained in a reservoir, along a vertical axis NM of said reservoir. The method is particularly suitable for being implemented by the measurement device described above. The method comprises the following steps: • collecting S110 at least one signal S, delivered by a sensor, the sensor comprising a capacitive element electrically coupled to an oscillator configured to deliver a signal S, whose frequency F ipad is a function of the capacitance of the capacitive element; said at least one sensor being intended to be disposed outside the reservoir, so that the capacity of the capacitive element varies as a function of the level n of the fluid, when said level is between a first threshold hi.min and a second threshold hj.max; Calculating S120 the difference between the frequency of the signal Si and a reference frequency Fjvco; • determine S130 the level n of fluid in the tank according to the frequency of the signal Si.
    With particular reference to FIG. 8, an example will now be described, in which the level n may vary between 0 and 20 cm in the tank 2, and the number nc of the sensors 12 is equal to 11, each sensor being adapted to measure the level n over a wide range of 24 mm. The Pt range of the first sensor is equal to [0 mm .. 24 mm], the P2 range of the second sensor to [18 mm .. 42 mm], the P3 range of the third sensor to [36 mm .. 60 mm], the P4 range of the fourth sensor at [54 mm .. 78 mm], the P5 range of the fourth sensor at [72 mm .. 96 mm], etc. The processing module will determine for each sensor the voltage Uj. Thus, in the present example, the voltage Ui, will correspond to the voltage when the level n is greater than or equal to hi.max, or 0V in the example of the conversion tables of FIG. 7. Similarly, the voltage U2, will correspond to the voltage when the level n is greater than or equal to h2-max, ie 0 V in the example of the conversion tables of Figure 7. The voltage U, for i between 5 and 11 corresponding to the 5th , 6th, 7th, 8th, 5th, 5th and 5th sensors will correspond to the voltage when the level n is less than or equal to hj.mjn, ie 4 V in the example of the conversion tables of FIG. In the example of the conversion tables of FIG. 8, the voltage U3 will be substantially equal to 0.5 V, and the voltage U4 will be substantially equal to 3.5 V. Also, knowing the measurement range of each of the sensors, the processing module 14 can determine the value of the level n.
    In one embodiment, the processing module 14 comprises at least one reference sensor 65, delivering a signal Sref, adapted to allow the detection of variations of the environment likely to influence the sensors 12. The reference sensor 65 can for example comprise the same elements as the other sensors 12, but be disposed on the detection circuit 10 so that the variations of the level n do not affect its capacitive element. The microprocessor is then coupled to the reference sensor 65 so as to receive the signal Sref and configured to correct the signals S, as a function of the frequency variations of the signal Sref, by acting on each F, vco of each sensor 12.
    In one embodiment, the processing module 14 comprises at least one temperature sensor 66 adapted to deliver a Utemp voltage as a function of the temperature of the environment of the sensors 12. The microprocessor 50 is then coupled to the temperature sensor 66 of so as to receive the signal Ujemp and configured to correct the signals S, according to the temperatures observed by the temperature sensor 66.
    In one embodiment, the processing module 14 comprises a diagnostic module 70. As illustrated in FIG. 5, the diagnostic module 70 may be included in the microprocessor 50. The diagnostic module 70 is configured to check the correct operation. sensors 12 and / or components of the measuring device. The diagnostic module 70 is coupled to the digital analog converter 62 so as to have access to the voltages U for each sensor 12. In addition, the diagnostic module 70 has access to the voltage conversion tables U, in level n, used by the conversion module 63. The diagnostic module 70 can therefore in particular determine the theoretical values of voltages that each sensor 12 must deliver according to the level n.
    With particular reference to FIG. 12, the steps of a diagnostic method according to the invention for verifying the coherence of the signals Si delivered by the sensors 12 will now be described. The diagnostic method may in particular be implemented by the diagnostic module 70. The diagnostic method may advantageously be used to diagnose any problems or errors that may affect the validity or accuracy of the value of the level n. obtained at the end of step S130 of the measuring method according to the invention.
    The steps described below apply when the fluid 1 is in a liquid state in the tank 2: also, the method may comprise an optional step (not shown in FIG. 12) during which the state of the fluid is determined. For example, the state can be obtained by determining physical parameters, such as temperature and pressure, relative to the fluid and / or its environment, and checking whether the value of the physical parameters is within a range in which it is known that the entire fluid in the reservoir is in the liquid state. If the fluid is not in the liquid state or only partially, then the process is terminated or alternatively a message indicating that the result of the consistency test should not be taken into account is issued
    During a first step S210, it is determined whether the level n, obtained at the end of step S130, is included in one of the overlap ranges R, of two adjacent sensors 12.
    If the level n is included in one of the recovery ranges Ri, an error determination step S220 is implemented. Such a case is illustrated in FIG. 10. In this example, the level n is equal to 57 mm. The level n is therefore included both in the range P3 of the third sensor 12 and in the range P4 of the fourth sensor 12. The level n is therefore in the recovery range R3. During step S220, the difference DIFFjable in absolute value is determined between the expected value U3_table for the level n of the voltage U3 for the third sensor and the expected value U4-table for the level n of the voltage U4 for the 4th sensor:
    The expected value U3_table and the expected value U4_table can be determined by reading, for the level n, the value corresponding to each sensor in the same conversion tables used by the conversion module 63 to determine the level n. Thus, the DIFFjable difference corresponds to the expected variation, for the level n, according to the conversion tables, between the voltages U3 and U4. In the example of FIG. 10, the difference DIFFjable is equal to the absolute value of the difference between the voltage U3 and the voltage U4, obtained by reading the conversion tables for the level n = 57mm, ie | 0.5-3.5 | = 3V.
    During step S220, the difference DIFFs in absolute value is determined between, on the one hand, the value of the voltage U3 measured for the third sensor and, on the other hand, the value of the voltage U4 measured for the fourth sensor:
    Thus, the difference DIFFmes corresponds to the difference actually measured by the measuring device, between the voltages U3 and U4.
    During step S220, a permissible deviation δ is determined or obtained. For example, the admissible deviation δ can be chosen and / or configured to be substantially equal to the measurement precision, theoretical or measured during a calibration step, for each sensor 12. During the step S220, is then determined whether the absolute value of the difference between the difference DIFFMES and the difference DIFFjable is less than twice the allowable difference, namely:
    If yes, the measured level n is considered valid. Otherwise, the level n measured is considered potentially unreliable, an alert can then be transmitted to the external module, for example the motherboard 16, to indicate a potential malfunction of the measuring device.
    If, during the first step S210, it has been determined that, the level n, obtained at the end of step S130, is located outside the overlap ranges R, of two adjacent sensors 12, a step S230 of upstream error determination and a downstream error determination step S240 are carried out. Such a case is illustrated in FIG. 11. In this example, the level n is equal to 48 mm, and is thus included only in the range P3 of the third sensor 12.
    During step S230 of upstream error determination, an expected voltage Udec corresponding to the expected voltage Uj is determined when the level n is lower than the lower limit hi.min of the corresponding range Pj. The expected voltage Udec can be determined by reading, when the level n is lower than the lower bound hj-mjn of the range Pj, the corresponding value in the same conversion tables used by the conversion module 63 to determine the level n. The voltage Udec can also be determined during a calibration phase, in the absence of fluid 1 in the tank 2. In the example of FIG. 11, the voltage Udec is equal to 4 V.
    During step S230, for each sensor whose lower limit hj.min of the measuring range Pj is greater than the level n, the voltage Uj measured for each of said sensors is compared with the expected voltage Udec- Thus, in the In the example of FIG. 11, it is verified during step S230 whether the voltage U4 measured for the 4th sensor and the voltage U5 measured for the 5th sensor are substantially equal to the expected voltage Udec ·
    If so, the signals Sj of each sensor whose lower bound hj.min of the range Pj is greater than the level n, are considered valid. In the opposite case, the signals Sj of the sensors whose lower limit hj.mjn of the range Pj is greater than the level n, and for which the difference between the voltage Uj and the expected voltage Udec is substantially non-zero, are considered as potentially unreliable, an alert can then be transmitted to the external module, for example the motherboard 16, to indicate a potential malfunction of the corresponding sensors.
    During the step S240 for determining the downstream error, the expected voltage Urec corresponding to the voltage U is determined, when the level n is greater than the upper limit hj.max of the corresponding range P. The expected voltage Urec can be determined by reading, when the level n is greater than the upper bound hj.max of the corresponding range P, the corresponding value in the same conversion tables used by the conversion module 63 to determine the level. not. The voltage Urec can also be determined during a calibration phase, the tank 2 being completely filled with fluid 1. In the example of FIG. 11, the voltage Urec is equal to 0 V. During step S240 for each sensor whose upper limit hj.max of the measuring range Pj is lower than the level n, the voltage Uj measured for each of said sensors is compared with the expected voltage Urec- Thus, in the example of FIG. is checked, in step S240, if the voltage Ui measured for the first sensor and the voltage U2 measured for the second sensor are substantially equal to the expected voltage Urec
    If so, the signals S, of each sensor whose upper limit hj.max of the measurement range Pj is lower than the level n, are considered valid. In the opposite case, the signals Sj of the sensors whose upper limit hj.max of the measuring range Pj is lower than the level n, and for which the difference between the voltage Uj and the expected voltage Urec is substantially non-zero, are considered as potentially unreliable, an alert can then be transmitted to the external module, for example the motherboard 16, to indicate a potential malfunction of the corresponding sensors.
    If, during the steps S230 and S240, the signals S, of each sensor whose upper limit hj.max of the measurement range P is lower than the level n, and the signals S, of each sensor whose lower bound hj .min of the range P, is greater than the level n, are considered valid, then the level n determined by the measuring device is considered valid. This information can be transmitted to the external module, for example the motherboard 16. In the opposite case, the level n determined by the measuring device is considered as potentially unreliable, an alert can then be transmitted to the external module, for example the motherboard 16, to indicate a potential malfunction of the measuring device.
    权利要求:
    Claims (17)
    [1" id="c-fr-0001]
    1. Measuring device intended to cooperate with a reservoir (2) capable of containing a fluid (1), said device being adapted to determine a level (n) of the fluid, along a vertical axis (NM) of said reservoir, characterized in that it comprises: • at least one sensor (12) comprising a capacitive element (28) electrically coupled to an oscillator (40) configured to deliver a signal (S,) whose frequency (FiPAD) is a function of the capacitance of the capacitor capacitive element (28); said at least one sensor being intended to be disposed outside the tank, so that the capacity of the capacitive element varies as a function of the level (n) of the fluid, when said level is between a first threshold (hj- min) and a second threshold (hj.max); A processing module (14), coupled to said at least one sensor, and configured to determine the level (n) of fluid in the tank as a function of the frequency of the signal (Si).
    [2" id="c-fr-0002]
    2. Device according to claim 1, wherein the processing module (14) is configured to determine the level (n) of fluid in the tank according to the frequency of the signal (Si) and a reference frequency (Fjvco ) clean to at least one sensor.
    [3" id="c-fr-0003]
    3. Device according to claim 2, wherein the processing module (14) is configured to determine the reference frequency (Fjvco), in an initial calibration phase, and / or periodically, and / or on the occurrence of an event, and / or upon receipt of an order.
    [4" id="c-fr-0004]
    4. Device according to claim 2 or 3, wherein the reference frequency (Fjvco) is equal to the frequency of the signal (Si) delivered by the oscillator of said at least one sensor when the fluid level is below the first threshold ( hj.mjn).
    [5" id="c-fr-0005]
    5. Device according to any one of the preceding claims, wherein the processing module (14) is coupled to an external module (16): • by a communication module (18), able to allow transmission of the level (n ) fluid in the reservoir to the external module (16); and / or • by a power supply module (20) capable of enabling power transmission from the external module (16) to said at least one sensor.
    [6" id="c-fr-0006]
    6. Device according to any one of the preceding claims, further comprising a diagnostic module (70) configured for: • when the level (n) of fluid determined by the processing module (14) is less than the first threshold (hj .mjn), identifying (S240) a malfunction if the difference between the frequency (F ipad) of the signal (S i) and a first reference frequency is substantially non-zero; When the level (n) of fluid determined by the processing module (14) is greater than the second threshold (hi.max), identifying (S240) a malfunction if the difference between the frequency (F ipad) of the signal (S,) and a second reference frequency is substantially non-zero.
    [7" id="c-fr-0007]
    Apparatus according to any one of claims 2 to 6, wherein the processing module (14) comprises: a voltage controlled reference oscillator (54) configured to produce a signal whose frequency (FiVco) varies according to a control signal; A microprocessor (50) configured to generate and deliver to the reference oscillator the control signal such that the frequency (Fjvco) of the signal produced by the reference oscillator substantially corresponds to the own reference frequency of said at least one sensor (12); A phase-locked loop (58) configured to generate an output signal (Ai) as a function of the difference between the frequency (F i pad) of the signal (Si) delivered by the at least one sensor (12) and the reference frequency (FiVco); An output filter (60), coupled to the output of the phase locked loop (58), adapted to convert the phase shift signal (Ai) into output voltage (U,); A conversion module (63) configured to determine the level (n) as a function of the output voltage (11).
    [8" id="c-fr-0008]
    8. Device according to claim 7, further comprising a diagnostic module (70) configured for: • when the level (n) of fluid determined by the conversion module (63) is less than the first threshold (hj.min), identifying (S230) a malfunction if the difference between the output voltage (U,) and a first reference voltage (Udec) is substantially non-zero; When the level (n) of fluid determined by the conversion module (63) is greater than the second threshold (hi-max), identifying (S240) a malfunction if the difference between the output voltage (U) and a second Reference voltage (Urec) is substantially non-zero.
    [9" id="c-fr-0009]
    9. Device according to any one of claims 1 to 8, further comprising at least a second sensor (12) having a second capacitive element (28) electrically coupled to a second oscillator (40) configured to deliver a second signal (Si ) whose frequency (F ipad) is a function of the capacitance of the second capacitive element (28); said at least one second sensor being intended to be disposed outside the reservoir, so that the capacitance of the second capacitive element varies as a function of the level (n) of the fluid, when said level is between a third threshold (hi_min) and a fourth threshold (hj.max); the processing module (14) being coupled to said at least one second sensor, and being configured to determine the level (n) of fluid in the reservoir as a function of the signal frequency (Si) of said at least one sensor and the frequency of the signal (Si) of said at least one second sensor.
    [10" id="c-fr-0010]
    Apparatus according to claim 9, wherein the range of values defined by the third threshold (hj.mjn) and the fourth threshold (hj.max) is disjoint from the range of values defined by the first threshold (hj.mjn). and the second threshold (hj max) ·
    [11" id="c-fr-0011]
    11. Device according to claim 9, wherein the third threshold is less than the second threshold, and further comprising a diagnostic module (70) configured for, when the fluid level (n) determined by the conversion module (63). is between the third threshold and the second threshold: • identify (S220) a malfunction if the absolute value of the difference between, on the one hand, the level (n) of fluid determined by the processing module from the signal (Si) said at least one second sensor and secondly the fluid level (n) determined by the processing module from the signal (Si) of said at least one sensor is greater than a permissible deviation.
    [12" id="c-fr-0012]
    Kit comprising a measuring device according to any one of claims 1 to 11, and a reservoir (2) intended to be assembled so that a space is reserved between the surface of the capacitive element of said at least one sensor ( 12) and the tank wall (2).
    [13" id="c-fr-0013]
    13. Kit according to claim 12, further comprising an aqueous urea solution intended to be contained in the reservoir.
    [14" id="c-fr-0014]
    14. Kit comprising a measuring device according to any one of claims 1 to 11, and an external module (16) configured to receive the level (n) of fluid in the tank and / or to allow a transmission of energy auditing at least one sensor.
    [15" id="c-fr-0015]
    15. A method for measuring a level (n) of fluid contained in a reservoir (2), along a vertical axis (NM) of said reservoir, characterized in that it comprises the following steps: • collect (S110) at least a signal (Si) delivered by a sensor (12), the sensor (12) comprising a capacitive element (28) electrically coupled to an oscillator (40) configured to deliver a signal (Si) whose frequency (F ipad) is a function of the capacitance of the capacitive element (28); said at least one sensor being intended to be disposed outside the tank, so that the capacity of the capacitive element varies as a function of the level (n) of the fluid, when said level is between a first threshold (hj- mjn) and a second threshold (hi.max); • calculate (S120) the difference between the signal frequency (Si) and a reference frequency (Fjvco); • determine (S130) the level (n) of fluid in the tank as a function of the signal frequency (Si).
    [16" id="c-fr-0016]
    16. The method of claim 15, further comprising the following steps: when the level (n) of determined fluid is less than the first threshold (hj-min), identify (S230) a malfunction if the difference between the frequency (Fîpad ) of the signal (Si) and a first reference frequency is substantially non-zero; When the determined fluid level (n) is greater than the second threshold (hj-max), identifying (S240) a malfunction if the difference between the frequency (F ipad) of the signal (Si) and a second reference frequency is substantially nil nothing.
    [17" id="c-fr-0017]
    17. The method of claim 15 or 16, wherein at least a second signal (S,) delivered by a second sensor (12) is collected (S110), the second sensor (12) having a capacitive element (28) electrically coupled. an oscillator (40) configured to output a second signal (Si) whose frequency (F i pad) is a function of the capacitance of the capacitive element (28); said at least one second sensor being intended to be disposed outside the tank, so that the capacitance of the capacitive element varies as a function of the level (n) of the fluid, when said level is between a third threshold (hi .min) and a fourth threshold (hj.max); the third threshold being lower than the second threshold; the level (n) of fluid being determined in the reservoir as a function of the frequency of the signal (Si) of said at least one sensor and the frequency of the signal (Si) of said at least one second sensor; and wherein, when the fluid level (n) determined during the determining step (S130) of the fluid level (n) is between the third threshold and the second threshold, further comprising the step of: • identify (S220) a malfunction if the absolute value of the difference between on the one hand the fluid level (n) determined from the signal (Si) of said at least one second sensor and on the other hand the level (n) of fluid determined from the signal (Si) of said at least one sensor is greater than a permissible deviation.
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    同族专利:
    公开号 | 公开日
    US20170059386A1|2017-03-02|
    FR3040484B1|2019-01-25|
    US10330515B2|2019-06-25|
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    法律状态:
    2016-06-23| PLFP| Fee payment|Year of fee payment: 2 |
    2017-03-03| PLSC| Publication of the preliminary search report|Effective date: 20170303 |
    2017-07-25| PLFP| Fee payment|Year of fee payment: 3 |
    2018-07-24| PLFP| Fee payment|Year of fee payment: 4 |
    2019-07-17| PLFP| Fee payment|Year of fee payment: 5 |
    2020-05-01| CD| Change of name or company name|Owner name: AKWEL, FR Effective date: 20191127 |
    2020-07-22| PLFP| Fee payment|Year of fee payment: 6 |
    2021-07-19| PLFP| Fee payment|Year of fee payment: 7 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1557947|2015-08-26|
    FR1557947A|FR3040484B1|2015-08-26|2015-08-26|NON-CONTACT MEASURING DEVICE OF A LEVEL IN A RESERVOIR|FR1557947A| FR3040484B1|2015-08-26|2015-08-26|NON-CONTACT MEASURING DEVICE OF A LEVEL IN A RESERVOIR|
    US15/248,302| US10330515B2|2015-08-26|2016-08-26|Device for contactless measurement of a level in a tank|
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