JP2013126279A - Vehicle driving apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle driving apparatus for accurately measuring a rotor temperature in an electric motor, and implementing motor control according to a measured temperature.SOLUTION: The vehicle driving apparatus 100 comprises: the electric motor 1 for driving wheels; a reduction gear 2 for reducing a rotational output from the electric motor 1; and a wheel bearing 5 rotated by an input shaft 3 of the reduction gear 2 and an output member 4 of a coaxial shaft center. A permanent magnet 16 is provided in a motor rotor 11 of the electric motor 1 so as to measure the rotor temperature. A magnetic flux detector 17 is provided in a motor housing 9 side of the electric motor 1 so as to detect a magnetic flux of the permanent magnet 16. A rotor temperature measuring means 18 is provided so as to estimate the temperature of the motor rotor 11 from the magnetic flux detected by the magnetic flux detector 17. If an output from the rotor temperature measuring means 18 is the defined predetermined threshold or more, a motor current or a motor rotational speed of the electric motor 1 is reduced by a temperature-responsive motor control means 19a.

Description

  The present invention relates to a vehicle drive device used for an electric vehicle or the like.

  In a motor having a permanent magnet and a field coil in a rotor, the resistance value of a field coil wound around the rotor is detected, and the coil temperature is estimated from the coil resistance value. The thing is proposed (patent document 1).

  Further, in this type of motor, a method of estimating the magnet temperature by measuring the temperature of the coolant that cools the outer periphery of the stator and the temperature of the stator coil, the thermal resistance between the coolant and the stator coil, and the stator coil A method has been proposed in which the heat generation ratio between the magnet and the permanent magnet is obtained in advance, and the magnet temperature is obtained by calculation based on the stator coil temperature, the coolant temperature, the heat generation ratio, and the thermal resistance ratio during motor operation. (Patent Document 2).

  Further, in this type of motor, a motor in which a temperature sensor is embedded in the stator and the temperature of the permanent magnet is estimated based on the stator temperature measured by the temperature sensor has been proposed (Patent Document 3). In this proposed example, a configuration in which a temperature detector is provided at a position suitable for detecting the temperature of the permanent magnet of the rotor is also disclosed.

  As another proposed example, a temperature sensor for measuring the temperature is provided in the in-wheel motor vehicle drive device, and the motor drive current is limited or the motor rotation speed is set according to the temperature information measured by the temperature sensor. There is also known one provided with a temperature corresponding motor control means for reducing the temperature (Patent Document 4).

JP 2008-187862 A JP 2008-245486 A JP 2004-194406 A JP 2008-168790 A

In a motor using a permanent magnet, the rotor generates heat and the permanent magnet is thermally demagnetized in a high-speed rotation region. However, in the case of irreversible demagnetization, there is a problem that torque performance is lowered. In addition, since the electric motor rotates at high speed by oil cooling, the surface temperature of the rotor cannot be accurately measured with an optical sensor or radiation thermometer that is a non-contact temperature sensor. If the temperature sensor is a contact sensor, the temperature of the rotor during high-speed rotation cannot be measured.
In each of the proposed examples described above, a method for estimating the temperature of the permanent magnet of the rotor is described, but a specific temperature detection method is not disclosed.

  An object of the present invention is to provide a vehicle drive device capable of accurately controlling the rotor temperature of an electric motor, and capable of motor control that can reliably avoid thermal demagnetization, which is irreversible demagnetization, without reducing motor drive unnecessarily. Is to provide.

The vehicle drive device of the present invention includes an electric motor that drives a wheel, a speed reducer that decelerates the rotational output of the electric motor, and a wheel bearing that is rotated by an output member that is coaxial with the input shaft of the speed reducer. In the vehicle drive device provided,
A permanent magnet for measuring the rotor temperature provided in the motor rotor of the electric motor, a magnetic flux detector provided on the motor housing side of the electric motor for detecting the magnetic flux of the permanent magnet, and a map defining the relationship between the detected magnetic flux and the temperature Rotor temperature measuring means for estimating the temperature of the motor rotor from the magnetic flux detected by the magnetic flux detector, and the electric motor when the output of the rotor temperature measuring means exceeds a predetermined threshold value. Temperature-responsive motor control means for reducing the motor current or the motor rotation speed of the motor is provided.

According to this configuration, the permanent magnet for measuring the rotor temperature is provided on the motor rotor, and the magnetic flux is detected by the magnetic flux detector provided on the motor housing side. From this detected magnetic flux, the temperature of the motor rotor is estimated by rotor temperature measuring means having means such as a map that defines the relationship between detected magnetic flux and temperature. When the output of the rotor temperature measuring means becomes equal to or greater than the threshold value, the motor corresponding to the electric motor or the motor speed is reduced by the temperature corresponding motor control means.
As described above, the rotor temperature measurement permanent magnet is provided in the motor rotor, and the rotor temperature is detected from the predetermined relationship between the magnetic flux and the temperature. Therefore, the rotor temperature of the electric motor can be accurately measured without contact. . Therefore, it is possible to appropriately control the reduction of the motor current and the motor rotation speed according to the motor temperature, it is not necessary to give a large margin to the threshold value, and without reducing the motor driving wastefully, Thermal demagnetization that becomes irreversible demagnetization can be avoided reliably.

  In the present invention, the magnetic flux detector may be a Hall IC or a coil. If it is a Hall IC or a coil, the magnetic flux can be detected with high accuracy.

  In this invention, when the magnetic flux detector is constituted by a coil, the magnetic flux detector may detect the magnetic flux of the permanent magnet for measuring the rotor temperature from the voltage value detected by the coil. . According to the voltage value, the detection process is easy.

  Only one magnetic flux detector or a plurality of magnetic flux detectors may be provided. When a plurality of outputs are provided, the magnetic flux can be detected with high accuracy by averaging the plurality of outputs.

A plurality of the permanent magnets for measuring the rotor temperature may be equally arranged in a circumferential direction concentric with the electric motor. The permanent magnet may be a cylindrical or columnar magnet. Further, when a plurality of permanent magnets are equally arranged in this way, the magnetic flux detector averages the magnetic flux detected from the plurality of permanent magnets equally arranged in the circumferential direction for each rotation of the electric motor. It is good also as what outputs.
If a plurality of permanent magnets are provided around the motor center, the temperature can be detected more accurately. When the magnetic fluxes detected from the plurality of permanent magnets are averaged and output every rotation of the electric motor, temperature detection using the detected magnetic flux can be performed with higher accuracy.

  In this invention, the permanent magnet for measuring the rotor temperature may be a ring magnet having a single pole or a multipole arranged concentrically with the electric motor. This ring magnet may be divided into a plurality of arc-shaped magnets arranged in the circumferential direction concentric with the electric motor. If the permanent magnet is in the shape of a ring concentric with the electric motor, the generated magnetic flux increases, and the temperature can be detected with high reliability by stable magnetic flux detection.

  In the present invention, when the magnetic flux detector is constituted by a coil, the magnetic flux detector determines the degree of demagnetization of the magnetic flux of the permanent magnet for measuring the rotor temperature from the peak value of the voltage detected by the coil. It may be estimated. In the case of a coil, the degree of demagnetization can be detected easily and accurately according to the peak value of the voltage.

In the present invention, the rotor temperature measuring means has a temperature measuring device for measuring the ambient temperature in the vehicle drive device, and corrects the detection value of the magnetic flux detector based on the ambient temperature measured by the temperature measuring device. It is good as a thing.
By correcting the temperature in this way, the temperature of the motor rotor can be correctly estimated without being influenced by the ambient temperature in the vehicle drive device.

  In this invention, the speed reducer may be a cycloid speed reducer. With a cycloid reducer, a high reduction ratio can be obtained smoothly and the electric motor can be reduced in size, but the electric motor is rotated at a high speed and the temperature is likely to rise. For this reason, motor control for preventing demagnetization by accurate temperature measurement by the vehicle drive device becomes even more effective.

  The vehicle drive device of the present invention includes an electric motor that drives a wheel, a speed reducer that decelerates the rotational output of the electric motor, and a wheel bearing that is rotated by an output member that is coaxial with the input shaft of the speed reducer. In the vehicle drive apparatus, a permanent magnet for measuring a rotor temperature provided in a motor rotor of the electric motor, a magnetic flux detector provided on a motor housing side of the electric motor and detecting a magnetic flux of the permanent magnet, and a detected magnetic flux A rotor temperature measuring means for estimating the temperature of the motor rotor from a magnetic flux detected by a magnetic flux detector having a means for determining a temperature relationship, and an output of the rotor temperature measuring means exceeds a predetermined threshold value; Temperature-responsive motor control means for reducing the motor current or the motor speed of the electric motor when the It made constant, without unnecessarily lowering the motor drive enables motor control can be reliably avoid thermal demagnetization to be irreversible demagnetization can maintain good running performance.

It is sectional drawing of the vehicle drive device which concerns on embodiment of this invention. It is sectional drawing of the reduction gear used as the II-II arrow cross section of FIG. It is a front view of an example of the permanent magnet for rotor temperature measurement used as the III-III arrow cross section of FIG. It is a front view of the other example of the permanent magnet. It is a front view of the further another example of the permanent magnet. It is a front view of the further another example of the permanent magnet. It is explanatory drawing of estimation of the demagnetization degree of the magnetic flux of the permanent magnet performed with a magnetic flux detector. It is a block diagram of a rotor temperature measurement means and a motor control means. It is a block diagram of a conceptual structure which shows the electric vehicle containing the vehicle drive device with a top view.

  An embodiment of the present invention will be described with reference to FIGS. The vehicle drive device 100 according to this embodiment is an in-wheel motor vehicle drive device, and is mounted on, for example, an electric vehicle. As shown in a sectional view in FIG. 1, a vehicle drive device 100 includes an electric motor 1 that drives wheels, a speed reducer 2 that decelerates the rotation of the electric motor 1, and an input shaft 3 that is coaxial with the speed reducer 2. The wheel bearing 5 rotated by the output member 4 and a lubricating oil supply mechanism 40 described later are provided.

  A reduction gear 2 is interposed between the wheel bearing 5 and the motor 1, and a wheel hub, which is a driving wheel supported by the wheel bearing 5, and a motor rotating shaft 6 of the motor 1 are connected on the same axis. It is. In this specification, the side closer to the outside in the vehicle width direction of the vehicle with the in-wheel motor vehicle drive device 100 attached to the vehicle is referred to as the outboard side, and the side closer to the center of the vehicle is referred to as the inboard side. Call it.

  As shown in FIG. 1, the electric motor 1 is a radial gap type IPM motor in which a radial gap is provided between a motor stator 10 fixed to a cylindrical motor housing 9 and a motor rotor 11 attached to the motor rotating shaft 6. (That is, an embedded magnet type coaxial motor). The motor housing 9 is provided with bearings 12 and 13 spaced apart in the axial direction, and the motor rotating shaft 6 is rotatably supported by the bearings 12 and 13. The motor rotating shaft 6 transmits the driving force of the electric motor 1 to the speed reducer 2. A flange portion 6a extending radially outward is provided in the vicinity of the middle portion of the motor rotating shaft 6 in the axial direction, and the motor rotor 11 is attached to the flange portion 6a via a rotor fixing member 14.

  The input shaft 3 of the speed reducer 2 has one axial end extending into the motor rotation shaft 6 and is splined to the motor rotation shaft 6. A bearing 23 is provided in the speed reducer housing 7, and the other axial end of the input shaft 3 is supported by the bearing 23. Therefore, the input shaft 3 and the motor rotating shaft 6 of the speed reducer 2 are supported by the bearings 12, 13, and 23 so as to be rotatable together. Eccentric portions 24 and 25 are provided on the outer peripheral surface of the reduction gear housing 7 near the other axial end of the input shaft 3. These eccentric portions 24 and 25 are provided with a 180 ° phase shift so that the centrifugal force due to the eccentric motion is canceled out from each other.

  The speed reducer 2 may have a reduction ratio of 1/6 or more. The speed reducer 2 is a cycloid speed reducer having curved plates 26 and 27, a plurality of outer pins 28, a motion conversion mechanism 29, and counterweights 30 and 30. As shown in FIG. 2, the curved plates 26 and 27 are rotatably provided in the eccentric portions 24 and 25, respectively. A plurality of outer pins 28 are supported across the motor housing 9 and the speed reducer housing 7, and these outer pins 28 are in rolling contact with the outer peripheries of the curved plates 26 and 27. The motion conversion mechanism 29 is a mechanism for transmitting the rotational motion of the curved plates 26 and 27 to the output member 4. The motion conversion mechanism 29 includes a plurality of inner pins 31 provided in the output member 4 and through holes 32 provided in the curved plates 26 and 27. The inner pins 31 are arranged at equal intervals in the circumferential direction around the rotation axis of the output member 4. As shown in FIG. 1, counterweights 30 and 30 are provided at axial positions adjacent to the eccentric portions 24 and 25 in the input shaft 3 of the speed reducer 2, respectively.

  The wheel bearing 5 includes an outer member 33 having a double-row raceway surface formed on the inner periphery, an inner member 34 having a raceway surface facing the respective raceway surfaces on the outer periphery, the outer member 33 and the inner member. And the double row rolling elements 35 interposed between the raceway surfaces of the side members 34. The inner member 34 also serves as a hub for mounting the drive wheel. The wheel bearing 5 is a double-row angular ball bearing, and the rolling elements 35 are formed of balls and are held by a cage for each row. The raceway surface has an arc shape in cross section, and each raceway surface is formed such that the contact angle is aligned with the back surface. Further, the outboard side end and the inboard side end of the bearing space between the outer member 33 and the inner member 34 are sealed by seal members 36 and 37, respectively.

  The outer member 33 is a stationary raceway, and has a flange 33a attached to the outboard side end of the speed reducer housing 7. The outer member 33 and the speed reducer housing 7 are an integral part. . The flange 33a is provided with bolt insertion holes at a plurality of locations in the circumferential direction, and the speed reducer housing 7 is provided with bolt screw holes made of female screws at positions corresponding to the bolt insertion holes. The outer member 33 is attached to the speed reducer housing 7 by screwing the mounting bolt inserted through the bolt insertion hole into the bolt screwing hole.

  The inner member 34 is a rotation side raceway, and a step portion 34a is formed on the outer peripheral surface on the inboard side in the hollow portion through which the output member 4 is inserted, and the inner ring 38 is fitted to the step portion 34a. It is fixed. A row of raceway surfaces is integrally formed on the outer peripheral surface of the inner member 34, and another row of raceway surfaces is formed on the outer peripheral surface of the inner ring 38. A hub flange 34b for attaching a wheel is provided at the end of the inner member 34 on the outboard side. A spline hole is formed in the hollow portion of the inner member 34, and the output member 4 is spline fitted into the hollow portion. A male screw is formed at the distal end portion of the output member 4, and the output member 4 and the inner member 34 are connected by screwing a nut 39 to the distal end portion of the output member 4 protruding from the hollow portion.

  In this example, the lubricating oil supply mechanism 40 is a mechanism that supplies lubricating oil used for both the lubrication of the speed reducer 2 and the cooling of the electric motor 1. The lubricating oil supply mechanism 40 is a so-called shaft-centered oil supply mechanism, and includes a lubricating oil passage 41, a motor rotation shaft oil passage 42, a speed reducer oil passage 43, a pump 44, and a lubricating oil reservoir that stores the lubricating oil. Part 45. The lubricating oil passage 41 is provided in the motor housing 9 and includes a first passage 41a to a fourth passage 41d. A through hole 6 b is provided in the motor rotating shaft 6, and an oil passage 14 a is provided in the rotor fixing member 14. The oil passage 14 a communicates with an annular gap δ 1 between the rotor fixing member 14 and the inner peripheral surface of the motor rotor 11. The pump 44 is a cycloid pump having a suction port 44a and the discharge port 44b. The lubricating oil reservoir 45 has a speed reducer side reservoir 45 a and a motor side reservoir 45 b and communicates with the through hole 46.

  In the vehicle drive device having this basic configuration, a permanent magnet 16 for measuring the rotor temperature is provided on the side surface of the motor rotor 11. A magnetic flux detector 17 that detects the magnetic flux of the permanent magnet 16 is provided on the side of the motor housing 9 that is a non-rotating member so as to face this. FIG. 3 is a front view of a configuration example of the permanent magnet 16 having a cross section taken along the line III-III in FIG. In this configuration example, the permanent magnet 16 includes a cylindrical magnet 16 </ b> A that is cylindrical or columnar, and a plurality (four in this case) of the cylindrical magnets 16 </ b> A are arranged concentrically with the electric motor 1. It is equally distributed.

FIG. 4 is a front view of another configuration example of the permanent magnet 16. In this configuration example, 18 cylindrical magnets 16 </ b> A are equally arranged in the circumferential direction concentric with the electric motor 1.
FIG. 5 is a front view of still another configuration example of the permanent magnet 16. In this configuration example, the permanent magnet 16 includes a single-pole ring magnet 16 </ b> B, which is disposed concentrically with the electric motor 1.
FIG. 6 is a front view of still another configuration example of the permanent magnet 16. In this configuration example, the ring magnet 16 </ b> B is divided into arc-shaped magnets 16 </ b> B <b> 1 to 16 </ b> B <b> 6 (here, 6 poles) for each pole or each pole pair, and is equally arranged in the circumferential direction concentric with the electric motor 1. In the case of a multi-pole ring magnet, it is preferable that they are equally distributed, but they are not necessarily equally distributed.

  In FIG. 1, the magnetic flux detector 17 is constituted by a Hall IC or a coil. One or more magnetic flux detectors 17 may be provided. When the magnetic flux detector 17 is configured by a coil, the magnetic flux detector 17 detects the magnetic flux of the permanent magnet 16 from the voltage value detected by the coil. In this case, the magnetic flux detector 17 may estimate the degree of demagnetization of the magnetic flux of the permanent magnet 16 from the peak value of the voltage detected by the coil, as shown in FIG. In the waveform diagram of FIG. 7, the permanent magnet 16 is divided into, for example, multiple poles, and each divided portion is a ring magnet having the same polarity. When the permanent magnet 16 has a configuration in which a plurality of cylindrical magnets 16A are equally arranged in the circumferential direction as shown in FIGS. 3 and 4, the magnetic flux detector 17 has a plurality of cylinders. The magnetic flux detected from the magnet 16 </ b> A may be averaged and output every rotation of the electric motor 1. The magnetic flux detector 17 is connected to the rotor temperature measuring means 18.

  The rotor temperature measuring means 18 is means for estimating the temperature of the motor rotor 11 from the magnetic flux detected by the magnetic flux detector 17. The rotor temperature measuring means 18 has a relation setting means (not shown) such as a map for associating the magnetic flux of the permanent magnet 16 and the rotor temperature, which has been obtained in advance by experiments or simulations, and is detected by the magnetic flux detector 17. The temperature of the motor rotor 11 is estimated by comparing the magnetic flux with the relationship setting means such as this map. The rotor temperature measuring means 18 is connected to the temperature corresponding motor control means 19a.

  The temperature-corresponding motor control means 19a is provided in the motor control unit 19 in the inverter device 72 (FIG. 9) described later. The motor control unit 19 is a part that performs various controls of the electric motor 1, and a temperature corresponding motor control means 19 a is provided as one of its control functions. The temperature-corresponding motor control means 19a reduces the motor current or the motor speed of the electric motor 1 when the output of the rotor temperature measurement means 18 becomes equal to or more than a predetermined threshold value.

  FIG. 8 is a block diagram showing the configuration of the control system from the permanent magnet 16 to the motor control unit 19 including the temperature-corresponding motor control means 19a. Here, the rotor temperature measuring means 18 has a temperature measuring device 18a for measuring the ambient temperature in the vehicle drive device 100, and a detection value correcting unit 18b for correcting the detection value of the magnetic flux detector 17, and the temperature measuring device. The detection value of the magnetic flux detector 17 is corrected based on the ambient temperature in the vehicle drive device 100 measured by 18a. Thereby, the temperature of the motor rotor 11 can be correctly estimated without being influenced by the ambient temperature in the vehicle drive device 100.

  According to the vehicle drive device 100 configured as described above, the rotor temperature measuring permanent magnet 16 provided in the motor rotor 11 of the electric motor 1 and the magnetic flux provided on the motor housing 9 side of the electric motor 1 and detecting the magnetic flux of the permanent magnet 16. The detector 17, the rotor temperature measuring means 18 for estimating the temperature of the motor rotor 11 from the magnetic flux detected by the magnetic flux detector 17, and the output of the rotor temperature measuring means 18 is equal to or higher than a predetermined threshold value. Temperature-responsive motor control means 19a for reducing the motor current or the motor rotation speed of the electric motor 1 when the motor is driven, the rotor temperature of the electric motor 1 is accurately measured, and the motor is controlled according to the measured temperature. Can do. Further, the temperature can be measured in a non-contact manner, and the temperature can be measured even at high speed rotation. For these reasons, thermal demagnetization, which is irreversible demagnetization, can be reliably avoided without reducing motor drive unnecessarily, and motor drive performance can be maintained over a long period of time.

  FIG. 9 is a plan view showing a conceptual configuration of an electric vehicle on which the vehicle drive device 100 of the above-described embodiment is mounted. This electric vehicle is a four-wheeled vehicle in which the wheels 52 that are the left and right rear wheels of the vehicle body 51 are driving wheels and the wheels 53 that are the left and right front wheels are driven wheels. The front wheel 53 is a steering wheel. The left and right wheels 52 and 52 serving as driving wheels are driven by independent electric motors 1, respectively. The rotation of the electric motor 1 is transmitted to the wheel 52 via the speed reducer 2 and the inner member 34 (FIG. 1) of the wheel bearing 5. The electric motor 1, the speed reducer 2, and the wheel bearing 5 constitute the in-wheel motor vehicle drive device 100 described above, which is one assembly part. The speed reducer 2 is a cycloid type speed reducer described above and has a high speed reduction ratio of 10 or more. In the vehicle drive device 100, the electric motor 1 is installed in the vicinity of the wheel 52, and a part or the whole is disposed in the wheel 52. The storage battery 69 is used as a drive for the electric motor 1 and as a power source for the electrical system of the entire vehicle.

  The control system will be described. A general control unit 71, which is a main ECU (electrical control unit) that performs overall control of the entire vehicle, and a plurality of (2 in the illustrated example) that respectively control the electric motors 1 for traveling according to instructions from the general control unit 71. The inverter device 72 is mounted on the vehicle body 51. The overall control unit 71 and the inverter device 72 constitute a motor drive device 70. The overall control unit 71 includes a computer, a program executed by the computer, various electronic circuits, and the like. Note that the overall control unit 71 and the weak electric system of each inverter device 72 may be configured by a common computer or an electronic circuit on a common substrate.

  The overall control unit 71 includes a torque distribution unit 98, and the torque distribution unit 98 includes an accelerator opening signal output from the accelerator operation unit 66, a deceleration command output from the brake operation unit 67, and a steering unit 65. , The acceleration / deceleration command to be given to the left and right wheel electric motors 1, 1 is generated as a torque command value and output to each inverter device 72. The accelerator operation unit 66 and the brake operation unit 67 are each composed of a pedal such as an accelerator pedal and a brake pedal, and a sensor that detects an operation amount of the pedal. The steering means 65 includes a steering wheel and a sensor that detects the rotation angle thereof. In addition to the above control, the overall control unit 71 controls each part of the vehicle based on signals from various sensors such as a vehicle speed sensor, a load sensor, and a wheel rotation sensor (all not shown) provided in the vehicle. The function to perform.

The inverter device 72 includes a power circuit unit 78 that is a power conversion circuit unit provided for each electric motor 1, a motor control unit 19 that controls the power circuit unit 78, and the rotor temperature measuring unit 18. Is done. The motor control unit 19 is provided with the temperature-corresponding motor control means 19a. As described above, the temperature-corresponding motor control means 19a is information for reducing the motor current or the motor rotation speed of the electric motor 1 when the output of the rotor temperature measurement means 18 becomes equal to or higher than a predetermined threshold value. Is a means for outputting.
The power circuit unit 78 includes an inverter 81 that converts DC power of the storage battery 69 into three-phase AC power that is used to drive the electric motor 1, and a PWM driver 82 that is a means for controlling the inverter 81.
As described above, the rotor temperature measuring means 18 has a function of estimating the temperature of the motor rotor 11 from the magnetic flux detected by the magnetic flux detector 17 (FIG. 1).

  Thus, since this electric vehicle is equipped with the vehicle drive device 100 of the above-described embodiment, in the vehicle drive device 100, the rotor temperature of the electric motor 1 is accurately measured, and the motor according to the measured temperature. Control can be performed, heat generation can be prevented in the high-speed rotation region of the electric motor 1, torque performance can be prevented from being lowered, and good running performance can be maintained.

DESCRIPTION OF SYMBOLS 1 ... Electric motor 2 ... Reducer 3 ... Input shaft 4 ... Output member 5 ... Wheel bearing 9 ... Motor housing 11 ... Motor rotor 16 ... Permanent magnet 16A ... Cylindrical magnet 16B ... Ring magnet 17 ... Magnetic flux detector 18 ... Rotor temperature Measuring means 18a ... Temperature measuring device 18b ... Detected value correction unit 19 ... Motor control unit 19a ... Temperature-compatible motor control means 100 ... Vehicle drive device

Claims (12)

In a vehicle drive device comprising: an electric motor that drives a wheel; a speed reducer that reduces the rotational output of the electric motor; and a wheel bearing that is rotated by an output member that is coaxial with an input shaft of the speed reducer.
A permanent magnet for measuring the rotor temperature provided in the motor rotor of the electric motor, a magnetic flux detector provided on the motor housing side of the electric motor for detecting the magnetic flux of the permanent magnet, and means for determining the relationship between the detected magnetic flux and the temperature Rotor temperature measuring means for estimating the temperature of the motor rotor from the magnetic flux detected by the magnetic flux detector, and the motor of the electric motor when the output of the rotor temperature measuring means exceeds a predetermined threshold value A vehicle drive device comprising temperature-responsive motor control means for reducing current or motor rotation speed.   2. The vehicle drive device according to claim 1, wherein the magnetic flux detector is a Hall IC.   The vehicle drive device according to claim 1, wherein the magnetic flux detector is formed of a coil.   4. The vehicle drive device according to claim 3, wherein the magnetic flux detector detects a magnetic flux of the permanent magnet for measuring the rotor temperature from a voltage value detected by the coil.   5. The vehicle drive device according to claim 1, wherein a plurality of the magnetic flux detectors are provided.   6. The vehicle drive device according to claim 1, wherein a plurality of the permanent magnets for measuring the rotor temperature are equally arranged in a circumferential direction concentric with the electric motor.   7. The vehicle drive device according to claim 6, wherein the permanent magnet for measuring the rotor temperature is a cylindrical or columnar magnet.   8. The vehicle drive device according to claim 6, wherein the magnetic flux detector averages and outputs the magnetic flux detected from the plurality of permanent magnets for each rotation of the electric motor.   6. The vehicle drive device according to claim 1, wherein the permanent magnet for measuring the rotor temperature is a single-pole or multi-pole ring magnet arranged concentrically with the electric motor.   The vehicle drive device according to claim 9, wherein the ring magnet is divided into a plurality of arc-shaped magnets arranged in a circumferential direction concentric with the electric motor.   11. The magnetic flux detector according to claim 1, wherein the magnetic flux detector calculates a degree of demagnetization of the magnetic flux of the permanent magnet for measuring the rotor temperature from a peak value of a voltage detected by the coil or the Hall IC. Vehicle drive device to be estimated.   In any one of Claims 1 thru | or 11, The said rotor temperature measurement means has a temperature measuring device which measures the atmospheric temperature in a vehicle drive device, Based on the atmospheric temperature which this temperature measuring device measures, A vehicle drive device for correcting a detection value of the magnetic flux detector.

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