JP2016061375A - In-wheel motor driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an in-wheel motor driving device which is silent and has high durability.SOLUTION: In an in-wheel motor driving device 21 in which a deceleration portion B includes a decelerator input shaft 25 having eccentric portions 25a, 25b and rotated and driven by a motor portion A, curved plates 26a, 26b rotatably held at outer peripheries of the eccentric portions 25a, 25b through rolling bearings 40, and a motion converting mechanism for converting a self-rotating motion generated on the curved plates 26a, 26b during revolving motion, into a rotating motion of the decelerator output shaft 28, a rolling bearing 40 has a cylindrical roller 44 disposed between an inner raceway surface 42 and an outer raceway surface 43, and annular flange portions 46, 46 disposed in adjacent to an axial outer side of the cylindrical roller 44, surface roughness of at least one of an end face 44a of the cylindrical roller 44 and an end face 46a of the flange portion 46 opposed to each other in an axial direction is determined to be Ra0.25 μm or less.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an in-wheel motor drive device.

As is well known, an in-wheel motor drive device is housed inside the wheel or disposed near the wheel, so that the weight and size of the in-wheel motor drive device are the unsprung weight (running performance) of the vehicle and the cabin space. Affects the size of For this reason, the in-wheel motor drive device needs to be as light and compact as possible. On the other hand, the in-wheel motor drive device requires a large torque to drive the wheels. In order to satisfy these requirements at the same time, for example, in Patent Document 1 below, a motor unit that generates a driving force employs a high-rotation type motor that rotates at a rotational speed of, for example, about 15000 min ^−1. An in-wheel motor drive device has been proposed that employs a cycloid reduction gear that is compact and provides a high reduction ratio in a speed reduction portion that decelerates the rotation of the (motor) and transmits it to the wheel bearing portion.

  The speed reduction part to which the cycloid reduction gear is applied mainly has an eccentric part, and is held rotatably on the outer periphery of the eccentric part via a reduction gear input shaft that rotates by receiving the driving force of the motor part and a rolling bearing. The output of the reducer connected to the wheel bearing section is the curved plate that performs the revolving motion centered on the rotation axis as the reducer input shaft rotates, and the rotational motion that occurred on the curved plate during the revolving motion. A motion conversion mechanism that converts the rotational motion of the shaft. In the speed reduction part having such a configuration, when the motor part is driven, the speed reducer input shaft rotates at a high speed as described above, and a large load (mainly radial load) via a curved plate or the like. Is repeatedly loaded on the rolling bearing. For this reason, as said rolling bearing, the cylindrical roller bearing which can respond to high-speed rotation and was excellent in load carrying capacity is used suitably.

JP 2012-148725 A

  The inventors of the present application examined the miniaturization of the components of the speed reducer in the course of studying the technical means for realizing the light weight and compactness of the in-wheel motor drive device, and in particular, rolling that supports the curved plate rotatably. We focused on bearings (cylindrical roller bearings). That is, it is preferable to reduce the diameter of the cylindrical roller bearing in order to suppress the amount of heat generated inside the bearing accompanying the high speed rotation of the reduction gear input shaft and to prevent the occurrence of seizure as much as possible. However, as described above, a large load is repeatedly applied from the curved plate to the cylindrical roller bearing that rotatably supports the curved plate as the speed reducer input shaft rotates. For this reason, considering the required load capacity, it is difficult to reduce the diameter of the cylindrical roller bearing (particularly, the cylindrical roller as a rolling element), and it is rather necessary to use a relatively large diameter cylindrical roller.

  By the way, in the cylindrical roller bearing described above, an axial direction outer side of the cylindrical roller is subjected to an induced thrust load generated due to the eccentric load on the cylindrical roller, and an annular shape is used to hold the roller position on the rolling surface. A buttocks is provided. Since the radial dimension of the flange is mainly set according to the radial dimension of the cylindrical roller, if it is necessary to use a relatively large diameter cylindrical roller as described above, the radial dimension of the flange is also There is a need to increase it. However, since the peripheral speed of the outer diameter portion of the cylindrical roller increases as the diameter of the cylindrical roller increases, it has been found that noise and vibration that cannot be ignored are caused by the sliding contact between the cylindrical roller and the flange portion. Such abnormal noise / vibration contributes to a decrease in NVH characteristics of a vehicle equipped with an in-wheel motor drive device.

  In view of the above situation, an object of the present invention is to prevent the generation of abnormal noise and vibration as much as possible in a speed reduction unit to which a cycloid reduction gear is applied, and through this, an in-wheel motor drive device that is quiet and excellent in durability. Is to realize.

  In order to solve the above-described problems, the present invention provides a reduction gear that is provided with a motor portion, a reduction portion, and a wheel bearing portion that are held in a casing, the reduction portion has an eccentric portion, and is rotated by the motor portion. An input shaft, a curved plate that is rotatably held on the outer periphery of the eccentric part via a rolling bearing, and performs a revolving motion around the rotation shaft center as the speed reducer input shaft rotates, and a curve during the revolving motion A cylindrical roller interposed between the inner raceway surface and the outer raceway surface, and between the raceway surfaces, and a motion conversion mechanism that converts the rotational motion of the curved plate generated in the plate into the rotational motion of the reducer output shaft. And an in-wheel motor drive device having an annular flange disposed adjacent to the outside in the axial direction of the cylindrical roller, the surface roughness of at least one of the opposed two surfaces of the cylindrical roller and the flange is Ra 0.25 μm or less. It is characterized by that. In addition, "surface roughness" as used in the field of this invention means the arithmetic mean roughness prescribed | regulated to JISB0031.

  According to such a configuration, even when the end surface of the cylindrical roller and the end surface of the collar portion facing each other in the axial direction are in sliding contact with the rotation of the speed reducer input shaft, the contact resistance between the two is effectively reduced. Since it can be reduced, it is possible to effectively prevent the generation of abnormal noise and vibration in the speed reduction portion. Thereby, the in-wheel motor drive device which was quiet and excellent in durability is realizable.

  Considering the cost, it is preferable that the surface roughness of one of the opposing two surfaces is Ra 0.25 μm or less. However, if the surface roughness of both of the opposing two surfaces is Ra 0.25 μm or less, deceleration is achieved. It is possible to more effectively prevent the generation of abnormal noise and vibration in the part.

  In the above configuration, if the outer raceway surface is formed on the inner diameter surface of the curved plate, the outer ring of the rolling bearing is substantially omitted, so that the speed reduction portion can be reduced in weight and size.

  In consideration of the ease of assembly of the rolling bearing (incorporability of cylindrical rollers), it is preferable that the flange portion is provided integrally with the inner ring having the inner raceway surface.

  The eccentric part (and the curved plate that is rotatably held by the eccentric part via the rolling bearing) can be provided at a plurality of positions in the axial direction. In this case, it is preferable that the eccentric portions are provided with phases different from each other so as to cancel the centrifugal force generated with the rotation of the speed reducer input shaft.

  As mentioned above, according to this invention, generation | occurrence | production of the noise and vibration in the deceleration part to which a cycloid reduction gear is applied can be prevented as much as possible. Thereby, the in-wheel motor drive device which was quiet and excellent in durability is realizable.

It is a figure which shows the in-wheel motor drive device which concerns on one Embodiment of this invention. It is an enlarged view of the deceleration part of the in-wheel motor drive device shown in FIG. FIG. 3 is a cross-sectional view taken along line ZZ in FIG. 1. It is explanatory drawing which shows the load which acts on a curve board. It is a cross-sectional view of a rotary pump. It is a schematic plan view of an electric vehicle. It is the schematic sectional drawing which looked at the electric vehicle of Drawing 6 from back.

  Based on FIG. 6 and FIG. 7, the outline | summary of the electric vehicle 11 carrying an in-wheel motor drive device is demonstrated. As shown in FIG. 6, the electric vehicle 11 is configured to drive an chassis 12, a pair of front wheels 13 that function as steering wheels, a pair of rear wheels 14 that function as drive wheels, and a left and right rear wheel 14. A wheel motor drive device 21. As shown in FIG. 7, the rear wheel 14 is accommodated in the wheel housing 12a of the chassis 12, and is fixed to the lower portion of the chassis 12 via a suspension device (suspension) 12b.

  The suspension device 12b supports the rear wheel 14 by a suspension arm that extends to the left and right, and suppresses vibration of the chassis 12 by absorbing vibration received by the rear wheel 14 from the road surface by a strut including a coil spring and a shock absorber. Furthermore, a stabilizer that suppresses the inclination of the vehicle body during turning or the like is provided at a connecting portion of the left and right suspension arms. The suspension device 12b is an independent suspension type in which the left and right wheels can be moved up and down independently in order to improve the followability to the road surface unevenness and efficiently transmit the driving force of the rear wheel 14 to the road surface. desirable.

  In this electric vehicle 11, an in-wheel motor drive device 21 that rotates each of the left and right rear wheels 14 is incorporated in the left and right wheel housings 12 a, so that a motor, a drive shaft, a differential gear mechanism, and the like are mounted on the chassis 12. There is no need to provide it. Therefore, the electric vehicle 11 has an advantage that a large 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. Moreover, in order to expand the cabin space of the electric vehicle 11, it is necessary to reduce the size of the in-wheel motor drive device 21. Therefore, as shown in FIG. 1, an in-wheel motor drive device 21 according to an embodiment of the present invention is employed.

  The in-wheel motor drive device 21 which concerns on embodiment of this invention is demonstrated based on FIGS. As shown in FIG. 1, the in-wheel motor drive device 21 includes a motor unit A that generates a driving force, a deceleration unit B that decelerates and outputs the rotation of the motor unit A, and outputs from the deceleration unit B to the rear wheels. 14 (see FIGS. 6 and 7), and a wheel bearing portion C that is transmitted to 14 (see FIGS. 6 and 7). Although the details will be described later, the in-wheel motor drive device 21 has a lubrication mechanism that supplies lubricating oil to the motor part A and the speed reduction part B. The motor part A and the speed reduction part B are mounted in the wheel housing 12a (see FIG. 7) of the electric vehicle 11 while being housed in the casing 22. In addition, the casing 22 of this embodiment is comprised by fastening the part which accommodated the motor part A, and the part which accommodated the deceleration part B with the volt | bolt.

The motor part A includes a stator 23a fixed to the casing 22, a rotor 23b disposed opposite to the inside of the stator 23a via a radial gap, and a hollow rotating shaft (motor) mounted with a rotor 23b on the outer periphery. The rotary shaft 24 is configured to be rotatable at a rotational speed of about 15000 min ⁻¹ .

  The motor rotating shaft 24 has ends on one side in the axial direction (right side in FIG. 1, hereinafter also referred to as “inboard side”) and the other side (left side in FIG. 1 and hereinafter also referred to as “outboard side”). The bearings are rotatably supported with respect to the casing 22 by rolling bearings (in the example shown, deep groove ball bearings) 36 and 36 disposed in the respective portions.

  The wheel bearing portion C includes a hollow hub wheel 32 having a hollow structure and a wheel bearing 33 that rotatably supports the hub wheel 32 with respect to the casing 22. The hub wheel 32 extends radially outward from the cylindrical hollow portion 32a connected to the shaft portion 28b of the reduction gear output shaft 28 constituting the speed reduction portion B, and the end portion on the outboard side of the hollow portion 32a. The flange portion 32b is integrally provided. The rear wheel 14 (see FIGS. 6 and 7) is connected and fixed to the flange portion 32b by a bolt 32c. Accordingly, when the hub wheel 32 rotates, the rear wheel 14 rotates integrally with the hub wheel 32.

  The wheel bearing 33 has an inner member having an inner raceway surface 33 f formed directly on the outer diameter surface of the hub wheel 32 and an inner ring 33 a fitted to a small diameter step portion of the outer diameter surface, and an inner diameter surface of the casing 22. The outer ring 33b fitted and fixed, a plurality of balls 33c disposed between the inner member and the outer ring 33b, a retainer 33d that holds the balls 33c in a circumferentially separated state, and a shaft of the wheel bearing 33 It is a double row angular contact ball bearing provided with the sealing member 33e which seals a direction both ends.

  As shown in an enlarged view in FIG. 2, the speed reducer B includes a speed reducer input shaft 25 that is rotationally driven by the motor portion A, a speed reducer output shaft 28 that is arranged coaxially with the speed reducer input shaft 25, and a speed reducer. And a speed reduction mechanism that transmits the speed to the speed reducer output shaft 28 after decelerating the rotation of the speed input shaft 25. The reduction gear output shaft 28 transmits the rotation of the reduction gear input shaft 25 decelerated by the reduction mechanism to the hub wheel 32 of the wheel bearing portion C.

  The speed reducer input shaft 25 is fitted with a spline 25g (including serrations; the same applies hereinafter) formed on the outer periphery of the end portion on the inboard side to a spline formed on the inner periphery of the end portion on the outboard side of the motor rotation shaft 24. The motor rotating shaft 24 is connected by so-called spline fitting.

  Eccentric portions 25a and 25b whose shaft centers are eccentric with respect to the rotational axis of the speed reducer input shaft 25 are provided at two locations in the axial direction of the speed reducer input shaft 25. In the present embodiment, these two eccentric portions are provided. 25 a and 25 b are provided integrally with the reduction gear input shaft 25. The two eccentric portions 25a and 25b are provided with a phase difference of 180 ° in order to cancel the centrifugal force due to the eccentric motion.

  The speed reducer input shaft 25 is rotatably supported with respect to the speed reducer output shaft 28 by rolling bearings 37a and 37b that are spaced apart from each other in two axial directions. One rolling bearing 37a supports a substantially central portion of the reduction gear input shaft 25 in the axial direction, and the other rolling bearing 37b supports an end portion of the reduction gear input shaft 25 on the outboard side.

  The reduction gear output shaft 28 has a shaft portion 28b and a flange portion 28a. The flange portion 28a has a hole portion (through hole in the illustrated example) in which an end portion on the outboard side of the inner pin 31 described later is fitted and fixed. The hole portion serves as a rotational axis of the speed reducer output shaft 28. A plurality are formed at equal intervals on the circumference of the center. The shaft portion 28b is connected to the hub wheel 32 constituting the wheel bearing portion C by spline fitting. The reduction gear output shaft 28 is rotatably supported by the outer pin housing 60 via rolling bearings 48 and 48 that are spaced apart from each other in two axial directions.

  The speed reduction mechanism (cycloid speed reducer) is rotatably held on the outer periphery of the eccentric portions 25a and 25b via the rolling bearings 40 and 40, and revolves around the rotation axis as the speed reducer input shaft 25 rotates. The curved plates 26a and 26b that perform the movement and the outer pin housing 60 are held at fixed positions, and engage with the outer peripheral portions of the curved plates 26a and 26b (during the revolving motion) to cause the curved plates 26a and 26b to rotate. A plurality of outer pins 27 to be moved, a motion conversion mechanism for converting the rotational motion of the curved plates 26a and 26b into the rotational motion of the speed reducer output shaft 28, and a counterweight 29 disposed adjacent to the outer side in the axial direction of the eccentric portions 25a and 25b. , 29.

  As shown in FIG. 3, the curved plate 26 a has a plurality of waveforms formed of trochoidal curves such as epitrochoid on the outer periphery thereof. The curved plate 26a has axial through-holes 30a and 30b that open at both end faces thereof. A plurality of through-holes 30a are provided at equal intervals on the circumference centered on the rotation axis of the curved plate 26a, and receive one inner pin 31 to be described later. The through hole 30b is provided at the center of the curved plate 26a, and is fitted to the outer periphery of the eccentric portion 25a (rolling bearing 40) of the speed reducer input shaft 25.

  As shown in the enlarged view in FIG. 2 and FIG. 3, the rolling bearing 40 has an inner race 41 having an inner raceway surface 42 on the outer diameter surface and fitted to the outer diameter surface of the eccentric portion 25a, and a curved plate 26a. An outer raceway surface 43 formed directly on the inner diameter surface (inner wall surface defining the through-hole 30b), a plurality of cylindrical rollers 44 interposed between the inner raceway surface 42 and the outer raceway surface 43, and the cylindrical rollers 44. A cylindrical roller bearing provided with a retainer 45 (not shown in FIG. 3) to be held, and annular flanges 46 and 46 provided integrally with the inner ring 41 and disposed adjacent to the outside in the axial direction of the cylindrical roller 44. .

  In the rolling bearing 40 of the present embodiment, the curved plate 26a is integrally provided with a portion constituting the outer ring of the rolling bearing 40, the outer raceway surface 43 is directly formed on the inner diameter surface of the curved plate 26a, and the eccentric portion 25a is defined. Although the inner raceway surface 42 is formed on the inner ring 41 provided separately, for example, the inner raceway 41 may be omitted by directly forming the inner raceway surface 42 on the outer diameter surface of the eccentric portion 25a. If it does in this way, the rolling bearing 40 and by extension, the deceleration part B can be reduced in weight and size. In addition, although detailed description is abbreviate | omitted, the curved plate 26b has the structure similar to the curved plate 26a, and it is eccentric part 25b via the rolling bearing 40 similar to the rolling bearing 40 which supports the curved plate 26a. Is supported so as to be freely rotatable.

  The counterweight 29 is substantially fan-shaped and is fitted and fixed to the outer periphery of the speed reducer input shaft 25. Each counterweight 29 is arranged with a 180 ° phase shift from the eccentric portion 25a (or 25b) adjacent in the axial direction in order to cancel out the unbalanced inertia couple generated by the rotation of the curved plates 26a, 26b.

  As shown in FIG. 3, a plurality of outer pins 27 are provided at equal intervals on a circumference centered on the rotational axis of the speed reducer input shaft 25. When the curved plates 26a and 26b revolve as the speed reducer input shaft 25 rotates, the outer peripheral portions of the curved plates 26a and 26b engage with the outer pins 27, and the curved plates 26a and 26b are caused to rotate. Let As shown in FIG. 1, each outer pin 27 has a pair of rolling bearings (needle roller bearings) 61, 61 arranged at both ends in the axial direction and a pair of needle roller bearings 61, 61 on the inner periphery. It is rotatably supported on the casing 22 via the held outer pin housing 60. With this configuration, the contact resistance between the outer pin 27 and the curved plates 26a and 26b is reduced.

  Although not shown in detail, the outer pin housing 60 is supported in a floating state with respect to the casing 22 by a detent means (not shown) having an elastic support function. This is a component of the motion conversion mechanism that absorbs a large radial load or moment load generated by turning or sudden acceleration / deceleration of the vehicle, and converts the rotational motion of the curved plates 26a and 26b into the rotational motion of the reducer output shaft 28. This is to prevent damage.

  As shown in FIGS. 2 and 3, the motion conversion mechanism of the present embodiment includes a plurality of inner pins 31 and a plurality of through holes 30a provided in the curved plates 26a and 26b. The through hole 30 a is provided at a position corresponding to each of the plurality of inner pins 31. The inner pins 31 are arranged at equal intervals on the circumference centering on the rotational axis of the reduction gear output shaft 28, and the end portion on the outboard side is provided on the flange portion 28 a of the reduction gear output shaft 28. It is fixed to the hole. Since the speed reducer output shaft 28 is arranged coaxially with the speed reducer input shaft 25, the rotational motion of the curved plates 26 a and 26 b is converted into a rotational motion around the rotational axis of the speed reducer input shaft 25. It is transmitted to the reduction gear output shaft 28 above. Further, in order to reduce the frictional resistance between the inner pin 31 and the curved plates 26a, 26b, a needle roller bearing 31a is provided on the outer periphery of the inner pin 31 inserted into the through hole 30a of the curved plates 26a, 26b. . The inner diameter dimension of the through hole 30a is set larger than the outer diameter dimension of the inner pin 31 (referred to as “maximum outer diameter including the needle roller bearing 31a”; the same applies hereinafter).

  As illustrated in FIG. 2, the speed reduction unit B further includes a stabilizer 31 b. The stabilizer 31b integrally includes a ring-shaped annular portion 31c and a cylindrical portion 31d extending from the inner diameter surface of the annular portion 31c toward the inboard side, and the end portions on the inboard side of the inner pins 31 are circular. It is fixed to the ring portion 31c. As a result, when the motor part A is driven (when the speed reducer input shaft 25 is rotated), the load applied to some of the inner pins 31 from the curved plates 26a, 26b is all internal via the flange part 28a and the stabilizer 31b. Supported by pins 31.

  Here, the state of the load acting on the curved plate 26a and further on the reduction gear input shaft 25 when the motor part A is driven will be described with reference to FIG. When the motor unit A is driven, a load acts on the curved plate 26b in the same manner as described below.

The axis O ₂ of the eccentric portion 25 a provided on the speed reducer input shaft 25 is eccentric from the axis (rotational axis) O of the speed reducer input shaft 25 by the amount of eccentricity e. The outer periphery of the eccentric portion 25a is held curved plate 26a via a rolling bearing 40, since the eccentric portion 25a (roller bearing 40) rotatably supports the curve plate 26a, the axial center O ₂ is the curved plates 26a Axis It is also a heart. The outer peripheral portion of the curved plate 26a is formed by a waveform curve, and has concave portions 34 that are recessed in the radial direction at equal intervals in the circumferential direction. Around the curved plate 26a, a plurality of outer pins 27 that engage with the recesses 34 are arranged in the circumferential direction with the axis O as the center.

  In FIG. 4, when the motor part A is driven and the speed reducer input shaft 25 rotates counterclockwise on the paper surface, the eccentric part 25a and the curved plate 26a held on the outer periphery thereof revolve around the axis O. Therefore, the concave portion 34 formed on the outer peripheral portion of the curved plate 26a sequentially contacts the outer pin 27 in the circumferential direction. As a result, the curved plate 26a rotates clockwise in response to a load Fi as indicated by an arrow in the drawing from the plurality of outer pins 27.

Further, the curve plates 26a and a plurality of circumferentially disposed around the the axis O ₂ through-holes 30a, each through-hole 30a, which is arranged coaxially with the axis O (reduction gear input shaft 25) An inner pin 31 that is fixedly provided to the reduction gear output shaft 28 is inserted. Since the inner diameter of the through hole 30a is larger than the outer diameter of the inner pin 31, the inner pin 31 does not hinder the revolving motion of the curved plate 26a, and the inner diameter of the through hole 30a of the rotating curved plate 26a is not reduced. The rotational movement of the curved plate 26a is taken out by sliding contact with the wall surface, and the reduction gear output shaft 28 is rotated (converted into the rotational movement of the reduction gear output shaft 28). At this time, the speed reducer output shaft 28 has a higher torque and a lower rotational speed than the speed reducer input shaft 25, and the curved plate 26a receives a load Fj as indicated by arrows in the figure from the plurality of inner pins 31. A resultant force Fs of the plurality of loads Fi and Fj is applied to the reduction gear input shaft 25.

The direction of the resultant force Fs changes due to the influence of centrifugal force in addition to geometric conditions such as the shape of the outer peripheral portion of the curved plate 26a and the number of concave portions 34. Specifically, the angle α between the reference line X perpendicular to the straight line Y connecting the rotation axis O ₂ and the axis O and passing through the rotation axis O ₂ and the resultant force Fs is approximately 30 ° to 60 °. It fluctuates with. The plurality of loads Fi and Fj change in the direction and magnitude of the load while the speed reducer input shaft 25 rotates once. As a result, the resultant force Fs acting on the speed reducer input shaft 25 is also in the direction and magnitude of the load. Fluctuates. Then, when the speed reducer input shaft 25 rotates once, the concave portion 34 of the curved plate 26a is decelerated and rotated clockwise by one pitch, resulting in the state of FIG. 4, and this is repeated.

  Next, the lubrication mechanism will be described. The lubricating mechanism supplies lubricating oil to various parts of the motor part A and the speed reducing part B. As shown in FIGS. 1 and 2, the lubricating oil paths 24a and 24b provided on the motor rotating shaft 24, and the speed reducing part are provided. Lubricating oil passages 25c, 25d, 25e provided on the machine input shaft 25, a lubricating oil passage (not shown) provided on the stabilizer 31b, a lubricating oil passage (not shown) provided on the inner pin 31, and the casing 22 A lubricating oil discharge port 22b, a lubricating oil reservoir 22d, a lubricating oil passage 22e, a lubricating oil passage 49, and a rotary pump 51 disposed in the casing 22 for pumping the lubricating oil to the circulating oil passage 49 of the casing 22. Is the main configuration. The white arrow shown in FIG. 1 indicates the direction in which the lubricating oil flows.

  The lubricating oil passage 24a extends along the axial direction inside the motor rotating shaft 24, and the lubricating oil passage 24a includes a lubricating oil passage 25c extending along the axial direction inside the reduction gear input shaft 25. It is connected. The lubricating oil passage 25d extends in the radial direction from the lubricating oil passage 25c toward the outer diameter surface of the speed reducer input shaft 25, and the outer diameter end portion of the lubricating oil passage 25d in the illustrated example is outside the eccentric portions 25a and 25b. Open to the radial surface. The lubricating oil passage 25e extends in the axial direction from the end portion on the outboard side of the lubricating oil passage 25c, and opens to the outer end surface of the reduction gear input shaft 25 on the outboard side. The formation position of the lubricating oil passage 25d extending in the radial direction is not limited to this, and can be provided at any position in the axial direction of the reduction gear input shaft 25.

  The lubricating oil discharge port 22b provided in the casing 22 is for discharging the lubricating oil inside the speed reduction part B, and is provided in at least one location of the casing 22 at the position of the speed reduction part B. The lubricating oil discharge port 22b and the lubricating oil path 24a of the motor rotating shaft 24 are connected via a lubricating oil reservoir 22d, a lubricating oil path 22e, and a lubricating oil path 49. Therefore, the lubricating oil discharged from the lubricating oil discharge port 22b returns to the lubricating oil path 24a of the motor rotating shaft 24 via the lubricating oil path 22e, the circulating oil path 49, and the like. The lubricating oil reservoir 22d has a function of temporarily storing the lubricating oil.

  As shown in FIG. 1, the circulating oil passage 49 provided in the casing 22 includes an axial oil passage 49a extending in the axial direction inside the casing 22, and end portions on the outboard side and the inboard side of the axial oil passage 49a. Are formed by radial oil passages 49b and 49c extending in the radial direction.

  The rotary pump 51 is provided between the lubricating oil passage 22e connected to the lubricating oil reservoir 22d and the circulating oil passage 49. By disposing the rotary pump 51 in the casing 22, it is possible to prevent the in-wheel motor drive device 21 from being enlarged as a whole.

As shown in FIG. 5, the rotary pump 51 includes an inner rotor 52 that rotates using the rotation of the reducer output shaft 28, an outer rotor 53 that rotates following the rotation of the inner rotor 52, both rotors 52, 53 is a cycloid pump comprising a plurality of pump chambers 54 provided in a space between 53, a suction port 55 communicating with the lubricating oil passage 22e, and a discharge port 56 communicating with the radial oil passage 49b of the circulating oil passage 49. . The inner rotor 52 rotates about the rotation center c ₁ , and the outer rotor 53 rotates about a rotation center c ₂ different from the rotation center c ₁ of the inner rotor 52. Therefore, the volume of the pump chamber 54 changes continuously. As a result, the lubricating oil flowing into the pump chamber 54 from the suction port 55 is pumped from the discharge port 56 to the radial oil passage 49 b of the circulation oil passage 49.

  The lubrication mechanism mainly has the above configuration, and lubricates and cools each part of the motor part A and the speed reduction part B as follows.

  First, as shown in FIG. 1, in the motor portion A, the lubricating oil is supplied to the rotor 23 b and the stator 23 a mainly through the circulating oil passage 49 of the casing 22 and the lubricating oil passage 24 a of the motor rotating shaft 24. A part of the lubricating oil supplied to the cylinder is discharged from the opening on the outer diameter side of the lubricating oil passage 24 b under the influence of the centrifugal force generated by the rotation of the motor rotating shaft 24 and the pressure of the rotary pump 51. Done. That is, the lubricating oil discharged from the outer diameter side opening of the lubricating oil passage 24b is supplied to the rotor 23b and then supplied to the stator 23a. Further, the rolling bearing 36 that supports the end portion of the motor rotating shaft 24 on the inboard side mainly oozes out part of the lubricating oil flowing through the circulating oil passage 45 from between the casing 22 and the motor rotating shaft 24. It is lubricated by. Further, the rolling bearing 36 that supports the end portion on the outboard side of the motor rotating shaft 24 is mainly discharged from the lubricating oil passage 24b, and the inner portion on the outboard side of the portion of the casing 22 in which the motor portion A is accommodated. It is lubricated by the lubricating oil that has fallen along the wall.

  Next, the lubricating oil that has flowed into the lubricating oil passage 25c of the reduction gear input shaft 25 via the lubricating oil passage 24a of the motor rotation shaft 24 is subjected to centrifugal force and pressure of the rotary pump 51 accompanying the rotation of the reduction gear input shaft 25. The oil is discharged from the openings of the lubricating oil passages 25d and 25e toward the inside of the deceleration unit B. The discharged lubricating oil is supplied to various locations in the speed reduction portion B mainly by centrifugal force, and lubricates and cools the various locations in the speed reduction portion B. Then, as shown in FIG. 1, the lubricating oil that has reached the inner wall surface of the casing 22 is discharged from the lubricating oil discharge port 22b and stored in the lubricating oil storage portion 22d. As described above, since the lubricating oil reservoir 22d is provided between the lubricating oil discharge port 22b and the lubricating oil passage 22e connected to the rotary pump 51, it can be completely discharged by the rotary pump 51 especially during high-speed rotation. Even if no lubricating oil is temporarily generated, the lubricating oil can be stored in the lubricating oil storage unit 22d. As a result, it is possible to prevent an increase in heat generation and torque loss at various portions of the deceleration portion B. On the other hand, the amount of lubricating oil reaching the lubricating oil discharge port 22b decreases particularly during low-speed rotation. Even in such a case, the lubricating oil stored in the lubricating oil reservoir 22d is used as the lubricating oil. Since it can recirculate | reflux to the path | routes 24a and 25c, lubricating oil can be supplied to the motor part A and the deceleration part B stably.

  In addition, the lubricating oil inside the deceleration part B moves outside also by gravity in addition to centrifugal force. Therefore, it is desirable that the in-wheel motor drive device 21 is attached to the electric vehicle 11 so that the lubricating oil reservoir 22d is positioned below the in-wheel motor drive device 21.

  The overall structure of the in-wheel motor drive device 21 is as described above, and the in-wheel motor drive device 21 of the present embodiment has a characteristic configuration as described below.

  As shown in FIG. 2, among rolling bearings (cylindrical roller bearings) 40 in which the curved plates 26 a and 26 b are rotatably held in the deceleration portion B, the end surfaces 44 a and the flange portions 46 of the cylindrical rollers 44 facing each other in the axial direction. The surface roughness of at least one of the end surfaces 46a is set to Ra 0.25 μm or less, more preferably Ra 0.13 μm or less. In this embodiment, the surface roughness of both the opposing two surfaces 44a and 46a is Ra0. It is set to 25 μm or less. It should be noted that the surface roughness of the end faces 44a and 46a can be sufficiently achieved by turning under specific machining conditions.

  In this way, if the surface roughness of both opposing surfaces 44a and 46a is set to Ra 0.25 μm or less, as described above, the eccentric parts 25a and 25b of the speed reducer input shaft 25 (the rolling bearing 40 rotates at high speed). ) In the state of being fitted to the outer periphery of the motor), and a large load is repeatedly applied from the curved plates 26a and 26b to the rolling bearing 40 as the speed reducer input shaft 25 rotates. Even in the case where it is necessary to use a cylindrical roller bearing having a relatively large diameter cylindrical roller 44 as a rolling element as the bearing 40, abnormal noise and vibration are generated due to the sliding contact between the cylindrical roller 44 and the flange 46. It can be prevented as much as possible. As a result, the speed reduction part B that is quiet and excellent in durability, and thus the in-wheel motor drive device 21, can be realized, so that a passenger of the vehicle equipped with the in-wheel motor drive device 21 can feel abnormal noise, vibration, and the like. Sex is reduced.

  The cylindrical roller 44 is preferably made of bearing steel, subjected to carbonitriding, and the amount of retained austenite in the surface layer portion is preferably 20 to 35%. The inner ring 41 is made of bearing steel, subjected to carbonitriding treatment, preferably has a surface layer retained austenite amount of 25 to 50% and a core portion retained austenite amount of 15 to 20%. In this way, the rolling fatigue life can be improved and the occurrence of cracks due to retained austenite and the progress thereof can be suppressed, so that the durability of the rolling bearing 40 and thus the in-wheel motor drive device 21 can be improved ( (Long life) can be achieved. Further, in order to ensure the same life, it is possible to reduce the thickness of the raceway compared to the case where raceways (inner and outer races) that do not have the above configuration are employed. Therefore, the in-wheel motor drive device 21 can be reduced in size and weight through, for example, downsizing the rolling bearing 40 in the radial direction.

  Moreover, although detailed illustration is abbreviate | omitted, the curved board 26a, 26b is formed with case hardening steel, such as SCM415, SCM420, and SCr420, and the hardening layer formed by performing carburizing quenching tempering as heat processing on this It is preferable to have a (surface hardened layer).

  In this embodiment, even in this embodiment in which the outer ring constituting the rolling bearing 40 is integrally provided on the curved plate 26a, and the outer raceway surface 43 of the rolling bearing 40 is directly formed on the inner diameter surface of the curved plate 26a. Wear and damage due to the transfer of the 44 on the outer raceway surface 43 can be prevented as much as possible. Further, if a hardened layer accompanying carburizing, quenching and tempering is formed on the surface layers of the curved plates 26a and 26b, the outer peripheral portions of the curved plates 26a and 26b are deformed by a load applied from the outer pin 27, or The inner wall surface of the through hole 30a provided in the curved plates 26a and 26b is deformed by a load applied from the inner pin 31, or the inner pin 31 is worn. It is possible to effectively prevent wear due to sliding with the needle roller bearing 31a. Accordingly, it is possible to increase the durability life of the curved plates 26a and 26b, and consequently the speed reducing portion B.

  On the other hand, if the above-mentioned thing is employ | adopted as curved board 26a, 26b, the hardened layer will not be formed in the core part of curved board 26a, 26b, In this case, curved board 26a, 26b has toughness. . Thereby, for example, even when an instantaneous impact load is input to the deceleration portion B via the wheel bearing portion C during driving of the vehicle, the curved plates 26a and 26b may be deformed or damaged by the impact load. Can be effectively reduced. In addition, the case-hardened steel is relatively soft and rich in workability before the heat treatment (carburizing quenching and tempering), so that the curved plates 26a and 26b having complicated shapes can be produced efficiently. Moreover, since the carburizing and quenching tempering selected as the heat treatment method has flexibility in changing the shape, the cost required for newly producing and changing the design of the curved plates 26a and 26b can be reduced.

  The overall operation principle of the in-wheel motor drive device 21 having the above configuration will be described with reference to FIGS. 1 and 3.

  In the motor part A, for example, the rotor 23b made of a permanent magnet or a magnetic material rotates by receiving an electromagnetic force generated by supplying an alternating current to the coil of the stator 23a. Accordingly, when the speed reducer input shaft 25 connected to the motor rotating shaft 24 rotates, the curved plates 26 a and 26 b revolve around the rotational axis of the speed reducer input shaft 25. At this time, the outer pin 27 engages with the curved waveform provided on the outer periphery of the curved plates 26a and 26b in the circumferential direction, and the curved plates 26a and 26b are opposite to the rotation direction of the speed reducer input shaft 25. To rotate around.

  The inner pin 31 inserted through the through hole 30a comes into contact with the inner wall surface of the through hole 30a as the curved plates 26a and 26b rotate. As a result, the revolving motion of the curved plates 26 a and 26 b is not transmitted to the inner pin 31, and only the rotational motion of the curved plates 26 a and 26 b is transmitted to the wheel bearing portion C via the reduction gear output shaft 28. At this time, since the rotation of the speed reducer input shaft 25 is decelerated by the speed reducing portion B and then transmitted to the speed reducer output shaft 28, even when the low torque, high speed type motor portion A is employed, the drive wheels ( The required torque can be transmitted to the (rear wheel) 14.

The speed reduction ratio of the speed reducing portion B having the above-described configuration is expressed as (Z _A −Z _B ) where Z _{A is} the number of outer pins 27 and Z _B is the number of waveforms (recesses 34) provided on the outer peripheral portions of the curved plates 26a and 26b. ) / is calculated by Z _B. In the embodiment shown in FIG. 3, since Z _A = 12 and Z _B = 11, a very large reduction ratio of 1/11 can be obtained.

  In this way, by adopting the speed reduction unit B that can obtain a large speed reduction ratio without using a multi-stage configuration, the in-wheel motor drive device 21 having a compact and high speed reduction ratio can be obtained. Further, by providing rolling bearings (needle roller bearings) 61 and 31a that rotatably support the outer pin 27 and the inner pin 31, friction between the curved plates 26a and 26b and the outer pin 27 and the inner pin 31 is achieved. Since the resistance is reduced, the power transmission efficiency in the speed reduction portion B is also improved from this point.

  As described above, the in-wheel motor drive device 21 of this embodiment is light and compact as a whole device. Therefore, if the in-wheel motor drive device 21 is mounted on the electric vehicle 11, the unsprung weight can be suppressed, so that the electric vehicle 11 excellent in running stability and NVH characteristics can be realized.

  As described above, the in-wheel motor driving device 21 according to the embodiment of the present invention has been described. However, the in-wheel motor driving device 21 can be variously modified without departing from the gist of the present invention. is there.

  For example, in the above description, the annular flange 46 to be provided in the rolling bearing (cylindrical roller bearing) 40 that rotatably holds the curved plates 26a and 26b is provided integrally with the inner ring 41. It may be provided integrally with the outer ring of the rolling bearing 40.

  In the above description, the cycloid pump is employed as the rotary pump 51 constituting the lubrication mechanism. However, the present invention is not limited to this, and any rotary pump driven by using the rotation of the reduction gear output shaft 28 can be employed. Furthermore, the rotary pump 51 may be omitted, and the lubricating oil may be circulated only by centrifugal force.

  In the above description, the eccentric portions 25a and 25b are provided at two positions in the axial direction of the speed reducer input shaft 25. However, the number of installed eccentric portions can be arbitrarily set. For example, the eccentric portions can be provided at three positions in the axial direction of the speed reducer input shaft 25. In this case, each eccentric portion is 120 ° so as to cancel out the centrifugal force generated by the rotation of the speed reducer input shaft 25. It is preferable to change the phase.

  In the above, mainly, the through hole 30a provided in the curved plates 26a and 26b and the inner pin 31 fixed to the flange portion 28a of the reduction gear output shaft 28 so as to be slidable with the inner wall surface of the through hole 30a. Although the motion conversion mechanism is configured, the motion conversion mechanism is not limited to this, and any configuration that can transmit the rotational motion of the curved plates 26a and 26b to the hub wheel 32 of the wheel bearing portion C can be used.

  The description of the operation in the present embodiment has been made by paying attention to the rotation of each member, but in reality, power including torque is transmitted from the motor part A to the rear wheel 14. Therefore, the power decelerated as described above is converted into high torque.

  Moreover, although the case where the electric power is supplied to the motor unit A to drive the motor unit A and the power from the motor unit A is transmitted to the rear wheel 14 is shown, the vehicle decelerates or slopes are reversed. When it falls, the power from the rear wheel 14 side can be converted into high-rotation and low-torque rotation by the speed reduction part B and transmitted to the motor part A, and the motor part A can generate power. . Furthermore, the electric power generated here can be stored in a battery and used as electric power for driving the motor unit A and electric power for operating other electric devices provided in the vehicle.

  In the above description, the present invention is applied to a configuration in which a radial gap motor is used for the motor part A. However, the present invention is an axial gap motor in which the stator and the rotor are opposed to the motor part A via an axial gap. It is preferably applicable also when adopting.

  Further, the in-wheel motor drive device 21 according to the present invention is not limited to the rear wheel drive type electric vehicle 11 having the rear wheel 14 as the drive wheel, but also the front wheel drive type electric vehicle having the front wheel 13 as the drive wheel, The present invention can also be applied to a four-wheel drive type electric vehicle having 13 and rear wheels 14 as drive wheels. In the present specification, the “electric vehicle” is a concept including all vehicles that obtain driving force from electric power, and includes, for example, a hybrid vehicle, a fuel cell vehicle, and the like.

  The present invention is not limited to the above-described embodiments, and can of course be implemented in various forms without departing from the scope of the present invention. The scope of the present invention is not limited to patents. 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 11 Electric vehicle 21 In-wheel motor drive device 22 Casing 25 Reduction gear input shaft 25a, 25b Eccentric part 26a, 26b Curved plate 27 Outer pin 28 Reduction gear output shaft 40 Rolling bearing 41 Inner ring 42 Inner raceway surface 43 Outer raceway surface 44 Cylindrical roller 44a end face 46 collar part 46a end face A motor part B reduction part C wheel bearing part

Claims (5)

The motor part, the reduction part and the wheel bearing part are held in the casing,
The speed reduction part has an eccentric part and is rotatably held on the outer periphery of the eccentric part via a rolling bearing and a speed reducer input shaft that is rotationally driven by the motor part. A curved plate that performs a revolving motion around its rotational axis, and a motion conversion mechanism that converts the rotational motion generated in the curved plate during the revolving motion into the rotational motion of the reducer output shaft, and the rolling In an in-wheel motor drive apparatus, wherein the bearing has an inner raceway surface and an outer raceway surface, a cylindrical roller interposed between both raceway surfaces, and an annular flange disposed adjacent to the outside in the axial direction of the cylindrical roller.
An in-wheel motor drive device characterized in that the surface roughness of at least one of the two opposing surfaces of the cylindrical roller and the flange portion is set to Ra 0.25 μm or less.   2. The in-wheel motor drive device according to claim 1, wherein the surface roughness of both the cylindrical roller and the opposite two surfaces of the flange portion is set to Ra 0.25 μm or less.   The in-wheel motor drive device according to claim 1, wherein the outer raceway surface is formed on an inner diameter surface of the curved plate.   The in-wheel motor drive device as described in any one of Claims 1-3 which provided the said collar part integrally in the inner ring | wheel which has the said inner track surface.   2. The eccentric portions are provided at a plurality of positions in the axial direction, and the eccentric portions are provided with phases different from each other so as to cancel out centrifugal forces generated with the rotation of the speed reducer input shaft. The in-wheel motor drive device as described in any one of -4.

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