JP2018157683A - In-wheel motor drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently cool a parallel axis gear reducer and an electric motor in low-speed high-torque operation and high-speed low-torque operation.SOLUTION: An in-wheel motor drive device 21 includes: an electric motor 28; a parallel axis gear reducer 38; a wheel bearing 53; a casing 22 for accommodating the electric motor 28 and the parallel axis gear reducer 38; and a lubrication mechanism for feeding lubrication oil to the electric motor 28 and the parallel axis gear reducer 38 to cool the electric motor 28 and the parallel axis gear reducer 38. The lubrication mechanism installs an oil passage 23 in the casing 22 through which the lubrication oil circulates from a parallel axis gear reducer 38 side toward an electric motor 28 side, successively forms a distribution line 24 in the oil passage 23 for supplying the lubrication oil to the parallel axis gear reducer 38, and installs a control valve 30 for regulating an amount of the lubrication oil supplied to the parallel axis gear reducer 38 in the oil passage 24.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an in-wheel motor drive device in which, for example, an output shaft of an electric motor and a wheel bearing are connected via a reduction gear.

  A conventional in-wheel motor drive device has a structure disclosed in Patent Document 1, for example. The in-wheel motor drive device of Patent Document 1 includes an electric motor that drives a wheel, a speed reducer that decelerates rotation 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. It consists of and.

  The electric motor includes a stator fixed to the motor housing and a rotor attached to the motor rotation shaft. The stator has a structure in which a coil is wound around a stator core made of a magnetic material.

  The in-wheel motor drive device includes an oil supply mechanism that supplies lubricating oil to the electric motor and the speed reducer for the purpose of cooling the electric motor and cooling and lubricating the speed reducer.

  The oil supply mechanism of the electric motor and the reduction gear is a circulating structure that supplies the lubricating oil discharged from the built-in pump to the electric motor and the reducer with an axial oil supply structure that passes through the oil passage of the motor housing and returns to the built-in pump. It is said.

Japanese Patent Laid-Open No. 2006-86495

  By the way, the above-described in-wheel motor drive device requires an electric motor that is small in size and has high-speed rotation and high torque. When miniaturizing a high-speed rotation and high-torque electric motor, heat generation due to loss, particularly heat generation of a coil due to copper loss, becomes significant. Therefore, it is very important to cool the stator coil of the electric motor.

  Here, in the conventional in-wheel motor drive device, as shown in FIG. 8, an oil path 123 for supplying lubricating oil to the electric motor and the speed reducer is formed by a trochoid built-in pump (not shown). Some have a lubrication structure.

  In this oil supply structure, the lubricating oil pumped from the built-in pump is distributed through the oil holes 124 and 129 of the oil passage 123, and as shown in FIG. The lubricating oil is supplied to the electric motor (refer to the Q portion in the figure) at a constant ratio.

  Here, the amount of lubricating oil discharged from the trochoidal internal pump increases and decreases in proportion to the rotational speed of the electric motor. Therefore, the amount of lubricating oil supplied to the oil passage 123 is small in the low speed range. If this built-in pump is of a large flow rate type, the amount of lubricating oil will increase, but the loss of stirring resistance and the like will increase and the motor efficiency will decrease. In addition, since the speed reducer generates heat in the high speed range, a distribution ratio of the lubricating oil amount to the speed reducer is also required to some extent.

  In general, an electric vehicle generates a large amount of heat from an electric motor during low-speed, high-torque operation centering on an uphill road. On the other hand, in high-speed and low-torque operation such as a highway, the rate of heat generation of the speed reducer increases. Therefore, as in the conventional case, it is difficult to perform efficient cooling with refueling at a constant ratio to the speed reducer and the electric motor (see FIG. 9).

  Accordingly, the present invention has been proposed in view of the above-described problems, and an object of the present invention is to drive an in-wheel motor that can efficiently cool a reduction gear and an electric motor in low speed high torque operation and high speed low torque operation. To provide an apparatus.

  An in-wheel motor drive device according to the present invention includes an electric motor, a reduction gear, a wheel bearing, a casing that houses the electric motor and the reduction gear, and an electric motor that supplies lubricating oil to the electric motor and the reduction gear. And a lubrication mechanism for cooling the reduction gear.

  As a technical means for achieving the above-mentioned object, the lubricating mechanism according to the present invention is provided with an oil passage in the casing through which the lubricating oil flows from the speed reducer side to the electric motor side, and supplies the lubricating oil to the speed reducer. The distribution path is connected to the oil path, and an adjustment valve for increasing or decreasing the amount of lubricating oil supplied to the speed reducer is provided in the distribution path.

  In the present invention, the distribution ratio of the lubricating oil amount to the speed reducer and the electric motor can be varied as necessary by providing an adjustment valve for increasing or decreasing the amount of lubricating oil supplied to the speed reducer in the distribution path of the oil path. be able to.

  For example, the distribution ratio to the electric motor is increased during low-speed high-torque operation where the heat generated by the electric motor is large. That is, the amount of lubricating oil supplied to the electric motor is increased by decreasing the amount of lubricating oil supplied to the speed reducer. Thereby, heat_generation | fever of an electric motor can be suppressed.

  In addition, during high-speed low-torque operation where the reducer generates a large amount of heat, the distribution ratio to the electric motor is reduced. That is, the amount of lubricating oil supplied to the reduction gear is increased by reducing the amount of lubricating oil supplied to the electric motor. Thereby, the heat_generation | fever of a reduction gear can be suppressed.

  The adjustment valve in the present invention preferably has a structure including an elastic member that enables adjustment of the opening degree of the distribution path with respect to the pressure of the lubricating oil flowing into the distribution path.

  By adopting such a structure, an adjustment valve that increases or decreases the amount of lubricating oil supplied to the reduction gear can be easily realized by simple means.

  The adjustment valve according to the present invention preferably has a structure including a stopper for restricting the opening degree of the distribution path with respect to the elastic force of the elastic member.

  By adopting such a structure, an adjustment valve that increases or decreases the amount of lubricating oil supplied to the reduction gear can be easily realized by simple means.

  According to the present invention, the adjustment valve for increasing or decreasing the amount of lubricating oil supplied to the speed reducer is provided in the distribution path of the oil path, so that the distribution ratio of the amount of lubricating oil to the speed reducer and the electric motor can be adjusted as necessary. Can be variable. As a result, the speed reducer and the electric motor can be efficiently cooled in the low speed high torque operation and the high speed low torque operation.

In embodiment of this invention, it is sectional drawing which shows the whole structure of an in-wheel motor drive device. It is the schematic which looked at the parallel shaft gear reducer of FIG. 1 from the outboard side. It is a characteristic view which shows the distribution ratio of lubricating oil amount about the parallel-shaft gear reducer and electric motor in this invention. It is a principal part expanded sectional view which shows the adjustment valve provided in the distribution path of the oil path of FIG. It is a principal part expanded sectional view which shows the operation state of the regulating valve of FIG. It is a top view which shows schematic structure of the electric vehicle carrying an in-wheel motor drive device. FIG. 7 is a rear sectional view showing the electric vehicle of FIG. 6. It is a principal part expanded sectional view which shows the conventional oil supply structure. It is a characteristic view which shows the distribution ratio of lubricating oil amount about the reduction gear and electric motor in the past.

  An embodiment of an in-wheel motor drive device according to the present invention will be described in detail with reference to the drawings. FIG. 6 is a schematic plan view of the electric vehicle 11 on which the in-wheel motor drive device 21 is mounted, and FIG. 7 is a schematic cross-sectional view of the electric vehicle 11 as viewed from the rear.

  As shown in FIG. 6, the electric vehicle 11 includes a chassis 12, a front wheel 13 as a steering wheel, a rear wheel 14 as a drive wheel, and an in-wheel motor drive device 21 that transmits driving force to the rear wheel 14. Equip. As shown in FIG. 7, the rear wheel 14 is accommodated in a wheel housing 15 of the chassis 12 and is fixed to a lower portion of the chassis 12 via an independent suspension type suspension device (suspension) 16.

  In the electric vehicle 11, the in-wheel motor drive device 21 that drives the left and right rear wheels 14 is provided inside the wheel housing 15, thereby eliminating the need to provide a motor, a drive shaft, a differential gear mechanism, and the like on the chassis 12. Therefore, there is an advantage that a wide cabin space can be secured and the rotation of the left and right rear wheels 14 can be controlled.

  In order to improve the running stability and NVH characteristics of the electric vehicle 11, it is necessary to suppress the unsprung weight, and further, downsizing of the in-wheel motor drive device 21 is required in order to secure a wide cabin space.

  The in-wheel motor drive device 21 of the embodiment shown in FIG. 1 has the following structure. Thereby, the compact in-wheel motor drive device 21 is implement | achieved and the electric vehicle 11 excellent in driving | running | working stability and NVH characteristic can be obtained by restraining unsprung weight.

  Before describing the characteristic configuration of this embodiment, the overall configuration of the in-wheel motor drive device 21 will be described. In the following description, with the in-wheel motor drive device 21 mounted on the vehicle body, the side closer to the outside of the vehicle body is referred to as the outboard side (left side in the drawing), and the side closer to the center is inboard side (right side in the drawing). Called.

  As shown in FIG. 1, the in-wheel motor drive device 21 includes an electric motor 28, a parallel shaft gear reducer 38, and a wheel bearing 53. The electric motor 28 and the parallel shaft gear reducer 38 are accommodated in the casing 22 and are mounted in the wheel housing 15 (see FIG. 7) of the electric vehicle 11.

  The electric motor 28 includes a stator 25 fixed to the casing 22, a rotor 26 disposed so as to face the inner side in the radial direction of the stator 25 with a gap, and a rotor 26 disposed on the inner side in the radial direction of the rotor 26 so as to rotate integrally with the rotor 26. A radial gap type including a motor rotating shaft 27 is provided.

  The motor rotating shaft 27 can rotate at a high speed of about 10,000 to 1000 rotations per minute. The stator 25 is configured by winding a coil around the outer periphery of the magnetic core. The rotor 26 has a permanent magnet or a magnetic material disposed therein.

  The motor rotating shaft 27 holds the rotor 26 by a holder portion 31 that extends integrally outward in the radial direction. The holder portion 31 has a configuration in which a concave groove in which the rotor 26 is fitted and fixed is formed in an annular shape. The motor rotating shaft 27 is rotatable with respect to the casing 22 by one end in the axial direction (right side in FIG. 1) as the rolling bearing 32 and the other end in the axial direction (left side in FIG. 1) by the rolling bearing 33. It is supported by.

  The parallel shaft gear reducer 38 includes a first gear 34 that is an input gear, a second gear 35 and a third gear 36 that are intermediate gears, and a fourth gear 37 that is an output gear. The second gear 35 has a small-diameter tooth portion 39 on the inboard side and a large-diameter tooth portion 40 on the outboard side coaxially. Further, the third gear 36 has a large-diameter tooth portion 41 on the inboard side and a small-diameter tooth portion 42 on the outboard side coaxially.

  In this parallel shaft gear reducer 38, the tooth portion 43 of the first gear 34 meshes with the large diameter tooth portion 40 of the second gear 35, and the small diameter tooth portion 39 of the second gear 35 and the large diameter of the third gear 36. The tooth portion 41 meshes, and the small diameter tooth portion 42 of the third gear 36 and the tooth portion 44 of the fourth gear 37 mesh with each other, whereby the rotational motion of the motor rotating shaft 27 is decelerated with a predetermined reduction ratio.

  Since the in-wheel motor drive device 21 is housed in the wheel housing 15 (see FIG. 7) and becomes an unsprung load, it is essential to reduce the size and weight. Therefore, by using the parallel shaft gear reducer 38 having a large reduction ratio, the electric motor 28 can be downsized by combining it with the high-speed electric motor 28 of about several thousand revolutions per minute, and it is compact and has a high speed reduction. Ratio in-wheel motor drive device 21 can be realized.

  The first gear 34 is coaxially attached to the motor rotating shaft 27 by spline fitting, and is rotatably supported on the casing 22 by rolling bearings 45 and 46. The second gear 35 is rotatably supported on the casing 22 by rolling bearings 47 and 48. The third gear 36 is rotatably supported on the casing 22 by rolling bearings 49 and 50. The fourth gear 37 is coaxially attached to the outer ring 58 of the wheel bearing 53 by spline fitting, and is rotatably supported by the casing 22 by the rolling bearings 51 and 52.

  As shown in FIG. 1, the first gear 34 to the third gear 37 are arranged on a straight line along the radial direction. Further, the rotation centers C1 to C4 of the first gear 34 to the fourth gear 37 are offset with a positional relationship as shown in FIG. Thus, by arranging the first gear 34 to the fourth gear 37, the parallel shaft gear reducer 38 is made compact in the axial direction and the radial direction. In addition, the code | symbol M in a figure shows wheel space.

  As shown in FIG. 1, the wheel bearing 53 includes a pair of inner rings 56 and 57 fitted on the outer periphery of the distal end of a fixed shaft 55 attached to the suspension member 54, and an outer ring disposed outside the inner rings 56 and 57. 58, and a plurality of rolling elements 59, 60 arranged in two rows in the axial direction between the inner rings 56, 57 and the outer ring 58. The outer ring 58 is connected to the fourth gear 37 of the parallel shaft gear reducer 38 so that torque can be transmitted by spline fitting.

  Inner rings 56, 57 arranged on the inboard side and the outboard side of the wheel bearing 53 are stopped together with the fixed shaft 55, and are prevented from coming off by a nut 61 screwed into the end of the fixed shaft 55. A preload is applied to the wheel bearing 53 by the tightening force of the nut 61. By applying this preload, the wheel bearing 53 has a double-row angular ball bearing structure.

  Seal members 62 and 63 are provided at both ends of the wheel bearing 53 in the axial direction to prevent entry of muddy water and the like and leakage of grease. A flange 64 is integrally formed on the outboard side of the outer ring 58, and the rear wheel 14 (see FIGS. 6 and 7) is connected to the flange 64 with a hub bolt (not shown).

  The overall operation principle of the in-wheel motor drive device 21 having the above configuration will be described.

  As shown in FIG. 1, in the electric motor 28, the rotor 26 rotates by receiving electromagnetic force generated by supplying an alternating current to the stator 25. In the parallel shaft gear reducer 38, the rotation of the motor rotation shaft 27 is decelerated by the first gear 34 to the fourth gear 37 and transmitted to the wheel bearing 53.

  At this time, the rotation of the motor rotating shaft 27 is decelerated by the parallel shaft gear reducer 38 and transmitted to the wheel bearing 53. Therefore, even when the low torque, high speed rotating electric motor 28 is employed, the rear wheel 14 ( It is possible to transmit the torque required for the process (see FIGS. 6 and 7).

  In this embodiment, the radial gap type electric motor 28 is illustrated, but an axial gap type electric motor may be used, and a motor having an arbitrary configuration is applicable. Further, in this embodiment, the parallel shaft gear reducer 38 is illustrated, but for example, a planetary gear reducer, a cycloid reducer, or the like may be used.

  The overall configuration of the in-wheel motor drive device 21 in this embodiment is as described above, and the characteristic configuration will be described in detail below.

  In the in-wheel motor drive device 21, lubricating oil for cooling the electric motor 28 and cooling and lubricating the parallel shaft gear reducer 38 is enclosed. With this lubricating oil, the electric motor 28 is cooled by the rotation of the rotor 26, and the parallel shaft gear reducer 38 is cooled and lubricated by splashing by the rotation of the first gear 34 to the fourth gear 37.

  Thus, the in-wheel motor drive device 21 is a lubrication mechanism that supplies lubricating oil to the electric motor 28 and the parallel shaft gear reducer 38 for the purpose of cooling the electric motor 28 and cooling and lubricating the parallel shaft gear reducer 38. It comprises.

  As shown in FIG. 1, the lubrication mechanism is disposed in the casing 22 so as to communicate with a trochoid internal pump (not shown), an oil passage 23 disposed on the upper portion of the casing 22, and the oil passage 23. The two distribution paths 24 and 29 are provided.

  The amount of lubricating oil discharged from the internal pump increases and decreases in proportion to the rotational speed of the electric motor 28. That is, the internal pump has a small amount of lubricating oil and a low oil pressure when the rotation speed of the electric motor 28 is low. Conversely, when the rotational speed of the electric motor 28 is high, the amount of lubricating oil is large and the hydraulic pressure is high.

  In the oil passage 23, the lubricating oil supplied from the internal pump flows from the parallel shaft gear reducer 38 side toward the electric motor 28 side. One distribution path 24 is located above the parallel shaft gear reducer 38, and the lubricating oil diverted from the oil path 23 is supplied to the parallel shaft gear reducer 38. The other distribution path 29 is located above the electric motor 28, and lubricating oil that has been diverted from the oil path 23 is supplied to the stator 25 of the electric motor 28.

  The lubrication mechanism of this embodiment is an adjustment that increases or decreases the amount of lubricating oil supplied to the parallel shaft gear reducer 38 in one distribution passage 24 located on the upstream side (parallel shaft gear reducer 38 side) of the oil passage 23. A structure provided with a valve 30 is provided.

  The regulating valve 30 is attached to a recess 65 in the vicinity of the inlet of the distribution path 24. The adjustment valve 30 includes a valve body 67 that adjusts the opening degree of the opening 66 of the distribution path 24, an elastic member 68 disposed between the valve body 67 and the casing 22, and the valve body 67. It comprises a stopper 69 provided on the casing 22 so as to overhang the distribution path 24.

  The valve body 67 is biased upward by the elastic force of the elastic member 68, and the position of the valve body 67 is restricted by the stopper 69. As the elastic member 68, a coil spring, a leaf spring, or the like is effective, but any member can be used as long as its shape changes depending on pressure.

  The lubrication mechanism configured as described above, that is, the flow control of the lubricating oil by the oil passage 23, the distribution passages 24 and 29, and the regulating valve 30 will be described below.

  The lubricating oil discharged from the internal pump flows through the oil passage 23 and reaches the two distribution passages 24 and 29. Lubricating oil that has flowed into one distribution path 24 flows down toward the parallel shaft gear reducer 38. Thereby, the parallel shaft gear reducer 38 is cooled. Further, the lubricating oil that has flowed into the other distribution path 29 flows down toward the stator 25 of the electric motor 28. Thereby, the stator 25 of the electric motor 28 is cooled.

  Here, in the electric vehicle 11 (see FIGS. 6 and 7), the electric motor 28 generates a large amount of heat during low-speed, high-torque operation centering on an uphill road. On the other hand, in the high-speed and low-torque operation such as a highway, the ratio of heat generated by the parallel shaft gear reducer 38 is increased. Therefore, it is preferable to increase the amount of lubricating oil supplied to the electric motor 28 during low speed and high torque operation, and to increase the amount of lubricating oil supplied to the parallel shaft gear reducer 38 during high speed and low torque operation.

  Therefore, in this embodiment, the adjustment valve 30 for increasing or decreasing the amount of lubricating oil supplied to the parallel shaft gear reducer 38 is provided in the distribution passage 24 of the oil passage 23, so that the parallel shaft gear reducer 38 and the electric motor 28 are provided. The distribution ratio of the amount of lubricating oil is varied as necessary.

  That is, as shown in FIG. 3, during low-speed high-torque operation, the distribution ratio to the electric motor 28 is increased (see the X portion in the figure). On the other hand, during high-speed low-torque operation, the distribution ratio to the electric motor 28 is lowered (see the Y portion in the figure). In addition, the broken line in a figure shows the distribution ratio to the conventional electric motor (refer FIG. 9).

  For example, when the electric vehicle 11 is operated at low speed and high torque, the amount of lubricating oil discharged from the internal pump is proportional to the number of revolutions of the electric motor 28, so that the amount of lubricating oil discharged from the internal pump and flowing through the oil passage 23 is small. The hydraulic pressure is low. Thus, while the pressure of the lubricating oil flowing through the oil passage 23 is low, the elastic force of the elastic member 68 of the regulating valve 30 is large.

  Therefore, in the adjustment valve 30, as shown in FIG. 4, the position of the valve body 67 is regulated by the stopper 69 by the elastic force of the elastic member 68. At this time, the opening degree of the opening 66 of the distribution path 24 is reduced by the valve body 67.

  As a result, the amount of lubricating oil supplied from the distribution path 24 located on the upstream side of the oil path 23 to the parallel shaft gear reducer 38 decreases. The distribution ratio to the electric motor 28 is increased by the decrease in the amount of lubricating oil, and the amount of lubricating oil supplied to the electric motor 28 from the distribution path 29 located on the downstream side of the oil path 23 increases. Thereby, heat_generation | fever of the electric motor 28 can be suppressed.

  On the other hand, when the electric vehicle 11 is operated at high speed and low torque, the amount of lubricating oil discharged from the internal pump is proportional to the number of revolutions of the electric motor 28, so that the amount of lubricating oil discharged from the internal pump and flowing through the oil passage 23 is large. The hydraulic pressure is also high. As described above, when the pressure of the lubricating oil flowing through the oil passage 23 increases, the pressure of the lubricating oil becomes larger than the elastic force of the elastic member 68 of the regulating valve 30.

  Therefore, in the regulating valve 30, as shown in FIG. 5, the valve body 67 is pushed downward by the pressure of the lubricating oil flowing into the distribution path 24 against the elastic force of the elastic member 68. Thereby, the opening degree of the opening part 66 of the distribution path 24 becomes large by the fall of the valve body 67.

  As a result, the distribution ratio to the electric motor 28 decreases, the amount of lubricating oil supplied to the electric motor 28 from the distribution path 29 located on the downstream side of the oil path 23 decreases, and the distribution located on the upstream side of the oil path 23. The amount of lubricating oil supplied from the path 24 to the parallel shaft gear reducer 38 increases. Thereby, the heat_generation | fever of the parallel shaft gear reducer 38 can be suppressed.

  As described above, the adjustment valve 30 for increasing or decreasing the amount of lubricating oil supplied to the parallel shaft gear reducer 38 is provided in the distribution passage 24 of the oil passage 23, so that the parallel shaft gear reducer 38 and the electric motor 28 are connected. The distribution ratio of the lubricating oil amount can be varied as necessary. As a result, the parallel shaft gear reducer 38 and the electric motor 28 can be efficiently cooled in the low speed high torque operation and the high speed low torque operation.

  The adjustment valve 30 resists the elastic member 68 that allows the opening degree of the opening 66 of the distribution path 24 to be adjusted with respect to the pressure of the lubricating oil flowing into the distribution path 24, and the elastic force of the elastic member 68. And a stopper 69 for restricting the opening degree of the opening 66 of the distribution path 24. Thereby, the adjustment valve 30 which increases / decreases the amount of lubricating oil supplied to the parallel shaft gear reducer 38 can be easily realized by simple means.

  In the above embodiment, as shown in FIGS. 6 and 7, the electric vehicle 11 having the rear wheel 14 as a drive wheel is illustrated, but the front wheel 13 may be a drive wheel or a four-wheel drive vehicle. . In the present specification, “electric vehicle” is a concept including all vehicles that obtain driving force from electric power, and includes, for example, a hybrid vehicle.

  The present invention is not limited to the above-described embodiments, and can of course be implemented in various forms without departing from the gist of the present invention. It includes the equivalent meanings recited in the claims and the equivalents recited in the claims, and all modifications within the scope.

DESCRIPTION OF SYMBOLS 21 In-wheel motor drive device 22 Casing 23 Oil path 24 Distribution path 28 Electric motor 30 Adjustment valve 38 (Parallel shaft gear) Reduction gear 53 Wheel bearing 68 Elastic member 69 Stopper

Claims (3)

An electric motor, a speed reducer, a wheel bearing, a casing that houses the electric motor and the speed reducer, and a lubrication mechanism that supplies lubricating oil to the electric motor and the speed reducer to cool the electric motor and the speed reducer. In-wheel motor drive device,
The lubrication mechanism is provided with an oil passage in the casing through which lubricating oil flows from the speed reducer side to the electric motor side, and a distribution path for supplying the lubricating oil to the speed reducer is connected to the oil path to reduce the speed. An in-wheel motor drive device characterized in that an adjustment valve for increasing or decreasing the amount of lubricating oil supplied to the machine is provided in the distribution path.   2. The in-wheel motor drive device according to claim 1, wherein the adjustment valve includes an elastic member that enables the opening degree of the distribution path to be adjusted with respect to the pressure of the lubricating oil flowing into the distribution path.   The in-wheel motor drive device according to claim 2, wherein the adjustment valve includes a stopper that regulates an opening degree of the distribution path with respect to an elastic force of the elastic member.

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