Electric machine for motor vehicle with piezoelectric bearing

Abstract

The invention relates to an electric machine (1) for a motor vehicle, comprising a stator (10) and a rotor (20) mounted on said stator (10) in a movable rotational manner by a rotational axis (20A) and a plurality of bearing modules (40). At least one bearing element of at least one bearing module (40) comprises a piezoelectric transceiver, referred to as the "main" transceiver (120), configured to emit an ultrasonic power supply signal. The electric machine (1) comprises a sensor (30) mounted inside the rotor (20). Figure 1

Description

Title of the invention: Electric machine for motor vehicle with piezoelectric bearing. Technical field

[0001] The present invention relates to the field of automobiles and more particularly concerns an electric machine for motor vehicles with piezoelectric bearings for measuring parameters such as, for example, the temperature inside the rotor. Previous technique

[0002] As is known, an electric motor comprises a rotor and a stator. The operation of such a motor causes the rotor and stator to heat up. However, the rotor's temperature rise can lead to performance losses and demagnetization of the magnets inside it beyond a certain temperature, which can result in damage or even motor failure. It is therefore necessary to measure the temperature inside the rotor in order to reduce its speed when the temperature approaches the critical operating limit and thus prevent damage to the motor or its failure.

[0003] Due to its rotation during operation, the rotor temperature is difficult to measure directly by wired temperature probes, therefore it is estimated by algorithms and models integrated into the motor management system.

[0004] However, these integrated algorithms and models result in measurement errors of up to plus or minus 20°C, which is not satisfactory for controlling the motor in order to avoid damaging it or causing its failure.

[0005] A simple, reliable and effective solution that would at least partially remedy these drawbacks would therefore be advantageous. Description of the invention

[0006] To this end, the invention first relates to an electric machine for a motor vehicle, said electric machine comprising a stator and a rotor mounted on said stator in a movable rotational manner by means of an axis of rotation and a plurality of bearing modules, each bearing module comprising a fixed element mounted on the stator, a movable element mounted on the rotor, at least one bearing element mounted between the fixed element and the movable element and configured to permit rotation of the rotor relative to the stator, the electric machine being remarkable in that:

[0007] - at least one bearing element of at least one bearing module is a piezoelectric transceiver, referred to as the "main" transceiver, configured to emit an ultrasonic power signal,

[0008] - the stator includes a control stage configured to control said transmitter- main piezoelectric receiver in transmitting mode

[0009] - the electric machine includes a sensor, mounted inside the rotor, comprising a so-called "remote" piezoelectric transceiver, a measurement stage and a sensing element, said remote piezoelectric transceiver being configured to receive the ultrasonic feed signal and to transmit it to the measurement stage, the measurement stage being configured to collect and store the electrical energy contained in the received ultrasonic feed signal and to electrically power the sensing element from the stored electrical energy, the sensing element being configured to measure a parameter inside the rotor, to generate a measurement signal comprising at least one value of the measured parameter and to transmit said generated measurement signal to the measurement stage, the measurement stage being configured to extract at least one value of the measured parameter contained in the measurement signal,to generate an ultrasonic response signal containing at least one value of the extracted parameter and to control the emission by the remote piezoelectric transceiver of said generated ultrasonic response signal, the main piezoelectric transceiver being configured to receive said ultrasonic response signal and to transmit said received ultrasonic response signal to the control stage, said control stage being configured to extract at least one value of the parameter contained in the transmitted ultrasonic response signal.

[0010] The device according to the invention allows for remote measurements via the remote module by powering the sensing element with energy from signals sent by the main module over a wireless link. Thus, measurements can be taken very close to the magnets, thereby increasing the performance of the electrical machine control. The invention also eliminates the need for metallic barriers such as, for example, the casing and protective flanges, which block electromagnetic waves of the Wifi or Bluetooth type. The use of one or more bearing elements to constitute the main piezoelectric transmitter allows for the efficient transmission of signals to the sensor, as these signals are no longer attenuated by the bearing module.

[0011] Preferably, the main piezoelectric transmitter-receiver is made of ceramic.

[0012] In one embodiment, the main piezoelectric transmitter-receiver is a ball or a roller.

[0013] In another embodiment, the main piezoelectric transmitter-receiver is a crown, a ring or a torus.

[0014] In one embodiment, all the bearing elements of at least one bearing module are primary piezoelectric transmitter-receivers.

[0015] In one embodiment, each bearing module is circular in shape and fully surrounds the axis of rotation of the rotor.

[0016] Advantageously, the control stage is configured to control the position of the rotor as a function of at least one value of the extracted parameter.

[0017] In one embodiment, the sensor further comprises an external communication stage, and the measurement stage can be configured to control the transmission of signals containing the measured values ​​via said external communication stage. The measured values ​​can thus be sent to an entity external to the measuring device for processing. The external communication stage can, for example, transmit using a communication protocol such as Bluetooth, Wi-Fi, 5G, or RFID.

[0018] In one embodiment, the main piezoelectric transceiver is configured to resonate at at least one predetermined frequency. The control stage is configured to generate a signal at said at least one predetermined frequency and to deliver the generated signal to the main piezoelectric transceiver, and the remote piezoelectric transceiver is configured to resonate at said at least one predetermined frequency. These technical features allow for communication selectivity and, in particular, the use of several sensors with a single main piezoelectric transceiver, which improves performance and allows the frequency to be adapted according to the natural modes of the electrical machine and acoustic reflections.

[0019] The invention also relates to a motor vehicle comprising an electric machine as presented above, said electric machine being configured to drive the wheels of said vehicle in rotation.

[0020] The invention also relates to a method for measuring a parameter in a rotor of an electric motor vehicle machine, said method comprising the steps of:

[0021] - control, by the control stage, of the piezoelectric transceiver main broadcaster

[0022] - emission, by the main piezoelectric transceiver, of an ultrasonic signal food,

[0023] - reception, by the remote piezoelectric transceiver, of the ultrasonic signal power supply emitted,

[0024] - collection and storage, by the measuring stage, of the electrical energy contained in the ultrasonic power signal received,

[0025] - power supply, via the measuring stage, of the sensitive element from stored electrical energy,

[0026] - measurement, by the sensitive element, of the parameter,

[0027] - generation, by the sensitive element, of a measurement signal comprising at least one value of the measured parameter,

[0028] - transmission, by the sensitive element, of the measurement signal generated at the stage of measure,

[0029] - extraction, by the measurement stage, of at least one value of the measured parameter contained in the transmitted measurement signal,

[0030] - generation, by the measurement stage, of an ultrasonic response signal comprising the minus a value of the extracted parameter,

[0031] - control, by the measuring stage, of the emission, by the transceiver remote piezoelectric, of said generated ultrasonic response signal,

[0032] - emission, by the remote piezoelectric transceiver, of said ultrasonic signal response generated,

[0033] - reception, by the main piezoelectric transceiver, of the ultrasonic signal of response issued,

[0034] - transmission, by the main piezoelectric transceiver, of the ultrasonic signal of the response received, on the control floor,

[0035] - extraction, by the control stage, of at least one value of the contained parameter in the transmitted ultrasonic response signal.

[0036] Advantageously, the method includes a control step, by the control stage, of the rotor position based on at least one extracted parameter value. Brief description of the drawings

[0037] Other features and advantages of the invention will become apparent from the following description. This description is purely illustrative and should be read in conjunction with the accompanying drawings, in which:

[0038] [Fig-1] Fig. 1 is a schematic cross-sectional view of an example machine electric according to the invention.

[0039] [Fig.2] Fig.2 schematically illustrates, in a functional manner, a first embodiment of the electric machine according to the invention.

[0040] [Fig.3] Fig.3 schematically illustrates, in a functional manner, a second embodiment of the electric machine according to the invention.

[0041] [Fig.4] The [Fig.4] is a schematic cross-sectional view of a first example of an electric machine bearing module according to the invention.

[0042] [Fig.5] The [Fig.5] is a schematic cross-sectional view of a second example of an electric machine bearing module according to the invention.

[0043] [Fig.6] Fig.6 schematically illustrates one embodiment of the process according to the invention. Description of the implementation methods

[0044] Figure 1 is an example of an electric machine 1 according to the invention. The electric machine 1 is intended to be mounted in a motor vehicle in order to drive its wheels in rotation.

[0045] The electrical machine 1 comprises a stator 10 and a rotor 20 mounted on said stator 10 in a movable and rotating manner.

[0046] The stator 10 includes a control stage 110 and a main piezoelectric transceiver 120.

[0047] The control stage 110 is configured to control said main piezoelectric transceiver 120 in transmission.

[0048] The main piezoelectric transceiver 120 is configured to emit an ultrasonic signal called "supply" SUA ([Fig.6]) and to receive an ultrasonic signal called "response" SUR ([Fig.6]).

[0049] The electric machine 1 also includes a sensor 30, mounted inside the rotor 20.

[0050] With reference to figures 2 and 3, the sensor 30 comprises a so-called "remote" piezoelectric transceiver 310, a measuring stage 320 and a sensitive element 330.

[0051] The remote piezoelectric transceiver 310 is configured to receive the SUA power supply ultrasonic signal and to transmit it to the measurement stage 320.

[0052] The measuring stage 320 is configured to collect and store the electrical energy contained in the received SUA power supply ultrasonic signal and to electrically power the sensitive element 330 from the stored electrical energy.

[0053] The sensitive element 330 is configured to measure a parameter inside the rotor 20, to generate a measurement signal S ([Fig.6]) comprising at least one value of the measured parameter and to transmit said generated measurement signal S to the measurement stage 320.

[0054] The measuring stage 320 is configured to extract at least one value of the measured parameter contained in the measuring signal S, to generate an ultrasonic response signal SUR comprising at least one value of the extracted parameter and to control the emission by the remote piezoelectric transceiver 310 of said generated ultrasonic response signal SUR to the main piezoelectric transceiver 120.

[0055] The main piezoelectric transceiver 120 is configured to receive said SUR response ultrasonic signal and to transmit said received SUR response ultrasonic signal to the control stage 110.

[0056] The control stage 110 is configured to extract at least one value of the parameter contained in the transmitted SUR response ultrasonic signal and to control the position and / or rotational speed of the rotor 20 from at least one value of the extracted parameter.

[0057] In one embodiment, illustrated in [Fig. 3], the sensor 30 includes an external communication stage 340, and the measurement stage 320 is configured to control the transmission of signals containing the measured parameter values ​​(extracted from the measurement signal S) via said external communication stage 340. This transmission can, for example, be carried out on a communication interface such as Bluetooth or RFID, which are known per se. In this case, the external communication stage 340 preferably includes a microcontroller for implementing this transmission function.

[0058] In one embodiment:

[0059] - the main piezoelectric transceiver 120 is configured to resonate at minus one predetermined frequency, preferably two predetermined frequencies, for example 200 kHz and 2 MHz,

[0060] - the control stage 320 is configured to generate a signal to said at least a predetermined frequency and to deliver the generated signal to the main piezoelectric transceiver 120, and

[0061] - the remote piezoelectric transceiver 310 is configured to resonate at said at least a predetermined frequency, in order to improve the quality of the ultrasonic signals transmitted between the main piezoelectric transceiver 120 and the remote piezoelectric transceiver 310.

[0062] Now with reference to figures 1, 4 and 5, the stator 10 includes an armature 10A and the rotor 20 includes a rotation shaft 20A which allows the rotor 20 to be mounted on the stator 10 in a movable rotational manner via a plurality of bearing modules 40, only one of which is shown in figures 4 and 5 for the sake of clarity, in a manner known per se.

[0063] It is necessary to have at least two circular bearing modules 40, i.e. completely surrounding the axis of rotation 20A of the rotor 20 or at least two sets of three bearing-type bearing modules 40 to support the rotor 20.

[0064] In the examples in Figures 4 and 5, the bearing module 40 is of the circular type and comprises a fixed element 410, a movable element 420 and a plurality of rolling elements 430.

[0065] The fixed element 410 is in this example in the form of a ring mounted on the armature 10A of the stator 10.

[0066] The moving element also takes the form of a ring, mounted on the axis of rotation 20A of the rotor 20.

[0067] The bearing elements 430 are mounted between the fixed element 410 and the moving element 420, in a manner known per se, to allow the rotation of the rotor 20 relative to the stator 10.

[0068] The bearing elements 430 of a bearing module 40 can be a set of balls or rollers, a ring, a ring or a torus.

[0069] The main piezoelectric transceiver 120 is one or more of the bearing elements 430.

[0070] To this end, the main piezoelectric transmitter-receiver 120 is made of ceramic.

[0071] The control stage is connected on one side to the fixed element 410 of the bearing module 40 and on the other side to the moving element 420 of the bearing module 40 to constitute the excitation circuit of the main piezoelectric transmitter-receiver 120. The moving element 420 constitutes the fixed positive electrical terminal 410 for the main piezoelectric transmitter-receiver 120 while the fixed element 410 constitutes the negative electrical terminal for the main piezoelectric transmitter-receiver 120.

[0072] In the example of [Fig.4], the main piezoelectric transmitter-receiver 120 is a ball or set of balls of the bearing module 40.

[0073] In the example of [Fig.5], the main piezoelectric transmitter-receiver 120 is a ring which constitutes the rolling element 430 of the rolling module 40.

[0074] Example of implementation

[0075] An example of an implementation of the electric machine 1 will now be described with reference to [Fig. 6]. In this non-limiting example, the parameter to be measured may, for example, be the temperature inside a rotor 20A of the electric machine 20.

[0076] First, when it is necessary to measure the parameter, the control stage 110 commands in a step El the emission of ultrasonic signals by the piezoelectric transmitter 120.

[0077] The main piezoelectric transceiver 120 emits in a step E2 an ultrasonic power supply signal SUA to the remote piezoelectric transceiver 310 which receives it in a step E3.

[0078] In a step E4, the measuring stage 320 of the sensor 30 collects and stores the electrical energy contained in the received ultrasonic power supply signal SUA, for example in a capacitor and electrically supplies the sensitive element 330 from the electrical energy stored in a step E5.

[0079] The sensitive element 330 measures the parameter, for example the temperature, in a step E6 and then generates a measurement signal S including at least one value of the parameter measured in a step E7.

[0080] The sensitive element 330 then transmits in a step E8 the measurement signal S generated to the measurement stage 320 which receives it and extracts at least one value of the measured parameter contained in the measurement signal S in a step E9.

[0081] The measuring stage 320 then generates in a step E10 an ultrasonic response signal SUR comprising at least one value of the extracted parameter and then controls the emission, by the remote piezoelectric transceiver 310, of said ultrasonic response signal SUR generated in a step Eli.

[0082] The remote piezoelectric transceiver 310 emits in a step E12 the generated SUR response ultrasonic signal, which is received by the main piezoelectric transceiver 120 in a step El3.

[0083] The main piezoelectric transceiver 120 then transmits in a step E14 the received SUR ultrasonic response signal to the control stage, which extracts at least one value of the parameter contained in said ultrasonic response signal transmitted in a step E15 and then optionally controls the position of the rotor 20 as a function of said at least one value of the measured parameter, for example to slow down the rotor 20 and avoid damaging it when the temperature measured inside the rotor is too high.

[0084] The invention therefore makes it possible to measure a parameter using a remote module powered remotely by electrical energy, thus avoiding the use of a battery to be changed, which is particularly advantageous in the case of an electric machine rotor while allowing efficient transmission of signals between the control stage 110 and the sensor 30.

Claims

1. Demands Electric machine (1) for a motor vehicle, said electric machine (1) comprising a stator (10) and a rotor (20) mounted on said stator (10) in a movable rotational manner by a rotational axis (20A) and a plurality of bearing modules (40), each bearing module (40) comprising a fixed element (410) mounted on the stator (10), a movable element (420) mounted on the rotor (20), at least one bearing element (430) mounted between the fixed element (410) and the movable element (420) and configured to permit rotation of the rotor (20) relative to the stator (10), the electric machine (1) being characterized in that: - at least one bearing element (430) of at least one bearing module (40) is a piezoelectric transceiver called "main" (120) configured to emit an ultrasonic power signal (UPS), - the stator (10) includes a control stage (110) configured to control said main piezoelectric transceiver (120) in transmission, - the electric machine (1) includes a sensor (30), mounted inside the rotor (20), comprising a so-called "remote" piezoelectric transceiver (310), a measuring stage (320) and a sensing element (330), said remote piezoelectric transceiver (310) being configured to receive the ultrasonic feed signal (UAS) and to transmit it to the measuring stage (320), the measuring stage (320) being configured to collect and store the electrical energy contained in the received ultrasonic feed signal (UAS) and to electrically power the sensing element (330) from the stored electrical energy, the sensing element (330) being configured to measure a parameter inside the rotor (20), to generate a measurement signal (S) comprising at least one value of the measured parameter and to transmit said generated measurement signal (S) to the measuring stage (320),the measurement stage (320) being configured to extract at least one value of the measured parameter contained in the measurement signal (S), to generate an ultrasonic response signal (SUR) comprising at least one value of the extracted parameter and to control the emission by the piezoelectric transceiver, remote (310) of said generated ultrasonic response signal (URS), the main piezoelectric transceiver (120) being configured to receive said ultrasonic response signal (URS) and to transmit said received ultrasonic response signal (URS) to the control stage (110), said control stage (110) being configured to extract at least one parameter value contained in the transmitted ultrasonic response signal (URS).

2. Electric machine (1) according to claim 1, wherein the main piezoelectric transmitter-receiver (120) is made of ceramic.

3. Electric machine (1) according to any one of the preceding claims, wherein the main piezoelectric transmitter-receiver (120) is a ball or a roller.

4. Electric machine (1) according to any one of the preceding claims, wherein the main piezoelectric transmitter-receiver (120) is a crown, a ring or a torus.

5. Electric machine (1) according to any one of the preceding claims, wherein all the rolling elements (430) of at least one rolling module (40) are primary piezoelectric transmitter-receivers (120).

6. Electric machine (1) according to any one of the preceding claims, wherein each bearing module (40) is circular in shape and fully surrounds the axis of rotation (20A) of the rotor (20).

7. Electric machine (1) according to any one of the preceding claims, wherein the control stage (110) is configured to control the position of the rotor (20) as a function of at least one value of the extracted parameter.

8. Motor vehicle comprising an electric machine (1) according to any one of the preceding claims, said electric machine (1) being configured to drive the wheels of said vehicle in rotation.

9. A method for measuring a parameter in a rotor (20) of an electric machine (1) of a motor vehicle, said method comprising the steps of: - controlling (E1), by the control stage (110), the main piezoelectric transmitter-receiver (120) in transmission, - emission (E2), by the main piezoelectric transceiver (120), of an ultrasonic power signal (SUA), - reception (E3), by the remote piezoelectric transceiver (310), of the emitted ultrasonic power supply signal (SUA), - collection and storage (E4), by the measurement stage (320), of the electrical energy contained in the received ultrasonic power supply signal (SUA), - power supply (E5), via the measuring stage (320), to the sensing element (330) from the stored electrical energy, - measurement (E6), by the sensitive element (330), of the parameter, - generation (E7), by the sensitive element (330), of a measurement signal (S) comprising at least one value of the measured parameter, - transmission (E8), by the sensitive element (330), of the measurement signal (S) generated at the measurement stage (320), - extraction (E9), by the measurement stage (320), of at least one value of the measured parameter contained in the transmitted measurement signal (S), - generation (E10), by the measurement stage (320), of an ultrasonic response signal (SUR) comprising at least one value of the extracted parameter, - control (El 1), by the measurement stage (320), of the emission, by the remote piezoelectric transceiver (310), of said generated ultrasonic response signal (SUR), - emission (E12), by the remote piezoelectric transceiver (310), of said generated ultrasonic response signal (SUR), - reception (E13), by the main piezoelectric transceiver (120), of the emitted ultrasonic response signal (SUR), - transmission (E14), by the main piezoelectric transceiver (120), of the received ultrasonic response signal (SUR), to the control stage (110), - extraction (E15), by the control stage (110), of at least one value of the parameter contained in the transmitted ultrasonic response signal (SUR).

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