WO2016017351A1

WO2016017351A1 - Cycloidal speed reducer and in-wheel motor drive device provided with same

Info

Publication number: WO2016017351A1
Application number: PCT/JP2015/068944
Authority: WO
Inventors: 牧野　智昭; 功平井
Original assignee: Ntn株式会社; 牧野　智昭; 功平井
Priority date: 2014-08-01
Filing date: 2015-07-01
Publication date: 2016-02-04
Also published as: JP2016035278A

Abstract

This cycloidal speed reducer is provided with an input shaft (25), which has an eccentric section (25a, 25b), and roller bearings (37, 37) that rotatably support the input shaft (25) with respect to an output shaft (28). The input shaft (25) is provided with a lubricating oil path (25c) extending in the axial direction therewithin, and a first oil supply hole (P1) that extends in the radial direction and supplies the lubricating oil flowing through the lubricating oil path (25c) to roller bearings (41, 41) that support a curved plate (26a, 26b). The roller bearings (37, 37) are loosely fitted to the input shaft (25), and the input shaft (25) further has a second oil supply hole (P2) that extends in the radial direction and of which the inner end opens at the lubricating oil path (25c) and the outer end opens at the fitting section (M1, M2) of the roller bearings (37, 37).

Description

Cycloid speed reducer and in-wheel motor drive apparatus equipped with the same

The present invention relates to a cycloid reducer and an in-wheel motor drive device including the same.

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 high-rotation motor of about 15000 rpm, for example, is adopted as a motor unit for generating a driving force, and the motor unit and wheels are connected and fixed. 2. Description of the Related Art An in-wheel motor drive device has been proposed that employs a cycloid speed reducer that is compact and can provide a high reduction ratio in a speed reduction portion that is to be provided with a bearing portion.

The cycloid reducer is mainly an input shaft having an eccentric portion and a curve that is rotatably fitted to the outer periphery of the eccentric portion and performs a revolving motion around the rotational axis as the input shaft rotates. A plate, a plurality of outer pins that engage with the outer peripheral portion of the curved plate to cause the curved plate to rotate, and a motion conversion mechanism that converts the rotational motion of the curved plate into the rotational motion of the output shaft. The input shaft is connected to the rotation shaft of the motor unit so as to be able to transmit torque, and is supported rotatably with respect to the output shaft via a rolling bearing (input shaft support bearing).

The input shaft includes an axial oil passage extending in the axial direction inside the input shaft, and an oil supply hole extending in the radial direction and discharging and supplying lubricating oil flowing through the axial oil passage into the reduction gear. Provided. In order to efficiently supply the lubricating oil to the rolling bearing that supports the curved plate, the oil supply hole is provided so as to open, for example, on the outer diameter surface of the eccentric portion of the input shaft (see FIG. 1 of Patent Document 1). 13 and FIG. 15).

JP 2012-141028 A

By the way, if the fitting of the input shaft support bearing to the output shaft and the input shaft is both a tight fit, the assemblage of the reducer will deteriorate and indentation will occur on the bearing raceway surface during the process of assembling the input shaft support bearing. This may adversely affect the bearing performance and durability of the input shaft support bearing. For this reason, it has been studied that the fitting of the input shaft support bearing to the output shaft and the input shaft is an interference fit and a clearance fit, respectively.

However, when the fitting of the input shaft support bearing to the input shaft is a clearance fit, even if the input shaft is provided with the oil supply hole as described above, operation with high torque output, long-time high speed operation, or turning travel The part of the input shaft where the support bearing is fitted (support bearing fitting portion), the inner ring inner surface of the input shaft support bearing, and the like are likely to wear due to repetition of the above, and this is caused by the vicinity of the support bearing fitting portion. It was found that this was because the amount of lubricating oil supplied to was small. If the inner diameter surface of the inner ring of the support bearing fitting part or input shaft support bearing is worn, the input shaft support position of the input shaft support bearing is likely to deviate from the initial position, increasing the noise and vibration generated from the reducer due to misalignment. The risk of doing so increases. In addition, wear powder generated as a result of wear of each part diffuses into the reducer together with the lubricating oil, which may cause further wear and indentation, and thus cause abnormal noise and vibration.

In view of the above circumstances, the problem to be solved by the present invention is a cycloid capable of effectively suppressing wear at the fitting portion between the input shaft and its support bearing, and further, wear on the inner ring inner surface of the input shaft support bearing. An object of the present invention is to provide a speed reducer and to provide a cycloid speed reducer excellent in acoustic performance, durability life, and the like, and, in turn, an in-wheel motor drive device equipped with the speed reducer.

The present invention, which has been devised to solve the above-mentioned problems, is fitted with an input shaft having an eccentric portion, and is rotatably fitted to the outer periphery of the eccentric portion via a first rolling bearing. A curved plate that performs a revolving motion around the rotation axis, a plurality of outer pins that engage with the outer periphery of the curved plate to cause the curved plate to rotate, and the rotational motion of the curved plate to turn the output shaft. A motion converting mechanism for converting, and a second rolling bearing that rotatably supports the input shaft with respect to the output shaft. The input shaft has an axial oil passage extending in the axial direction and a radial direction extending in the axial direction. A cycloid reduction gear provided with a first oil supply hole for supplying lubricating oil flowing in the axial oil passage to the first rolling bearing, and fitting the second rolling bearing to the input shaft by clearance fitting And the input shaft extends in the radial direction and the inner diameter end opens into the axial oil passage. Wherein the diameter end portion is provided with a second oil supply holes opened in the fitting portion between the second rolling bearing. The “first rolling bearing” and the “second rolling bearing” in the present invention correspond to the “rolling bearing that supports the curved plate” and the “input shaft support bearing”, respectively.

According to the above configuration, the lubricating oil flowing in the axial oil passage of the input shaft is fitted to the fitting portion between the input shaft and the second rolling bearing (the second rolling bearing is fitted to the input shaft by a clearance fit. Can be efficiently supplied to the inside of the second rolling bearing. This effectively prevents wear of the fitting portion of the input shaft with the second rolling bearing and wear of the inner ring inner surface of the second rolling bearing, and prevents abnormal noise and vibration due to misalignment. In addition, it is possible to effectively prevent the internal wear of the second rolling bearing and to prevent the generation of abnormal noise and vibration due to the internal wear of the second rolling bearing. Therefore, it is possible to realize a cycloid reducer that is excellent in acoustic performance, durability life, and the like.

It is preferable that the outer diameter end portion of the second oil supply hole is opened at the axially central portion of the fitting portion. In this way, the lubricating oil can be easily spread over the entire area of the fitting portion, so that wear of the fitting portion can be more effectively prevented.

In the above configuration, in order to prevent as much as possible the swinging of the input shaft and the uneven wear of the input shaft due to this, the eccentric portion is provided at two positions in the axial direction of the input shaft with a phase difference of 180 °. Is preferred.

The second oil supply hole can be provided at a position (two places) in which the phase is different by 90 ° on one side and the other side in the circumferential direction with respect to the eccentric direction of the eccentric portion. In this way, regardless of the rotation direction of the input shaft, the outer diameter end of one of the second oil supply holes can be positioned on the inlet side of the load-loading area of the second rolling bearing (details will be described later). To do). Therefore, the lubricating oil supplied to the bearing fitting portion via the second oil supply hole is efficiently supplied to a region where the load is substantially loaded in the fitting portion as the input shaft rotates. Can do.

As the second rolling bearing, a ball bearing having an inner ring and an outer ring that rotate relative to each other via balls can be used. In this case, it is possible to generate noise and vibration due to wear of the fitting portion and deformation of the inner ring (especially the inner raceway surface) of the second rolling bearing while ensuring the workability of the second oil supply hole. In order to prevent as much as possible, it is preferable to set the opening diameter of the outer diameter end portion of the second oil supply hole to 10% or more and 40% or less of the ball diameter.

In the above configuration, it is preferable to use an input shaft made of case-hardened steel and subjected to carburizing, quenching and tempering as a heat treatment. The reason is as follows.

First, case-hardened steel, which is a kind of low-carbon steel, is relatively soft and excellent in workability before heat treatment, so that a predetermined shape can be obtained easily and with high accuracy. On the other hand, if carburizing quenching and tempering is applied to the workpiece made of case-hardened steel as a heat treatment, a hardened surface layer that can improve the wear resistance and strength of the surface layer while securing the toughness required for the core is formed. can do. In addition, carburizing, quenching, and tempering have flexibility for small changes in shape as compared with other heat treatment methods (specifically, high frequency heat treatment) that can form a surface hardened layer similar to the above, so the cost required for heat treatment. Is less. As described above, it is possible to obtain an input shaft that can be manufactured at a low cost, and has improved wear resistance of the bearing fitting portion and the like and has ensured toughness required for the core portion.

The cycloidal speed reducer according to the present invention described above can be preferably applied to a speed reduction part that constitutes an in-wheel motor drive device having a motor part, a speed reduction part, and a wheel bearing part. In this case, if the input shaft of the cycloid reducer is connected to the rotating shaft of the motor unit so as to be able to transmit torque, an in-wheel motor drive device having excellent acoustic performance and durability can be realized.

As described above, according to the present invention, it is possible to realize a cycloid reduction gear capable of effectively suppressing wear at the fitting portion between the input shaft and its support bearing, and further wear of the inner ring inner surface of the input shaft support bearing. Can do. Thereby, the cycloid reduction gear excellent in acoustic performance, durable life, etc. and by extension, the in-wheel motor drive device carrying this can be provided.

It is a figure which shows an example of the in-wheel motor drive device which applied the cycloid reduction gear which concerns on one Embodiment of this invention to the deceleration part. It is a longitudinal cross-sectional view of the input shaft shown in FIG. FIG. 2B is a sectional view taken along the line Z ₁ -Z ₁ shown in FIG. 2A. FIG. 2B is a cross-sectional view taken along the line Z ₂ -Z ₂ shown in FIG. 2A. FIG. 2 is a cross-sectional view taken along line ZZ in FIG. 1. It is explanatory drawing which shows the load which acts on the curve board which comprises the cycloid reduction gear shown in FIG. It is a cross-sectional view of the rotary pump incorporated in the in-wheel motor drive device shown in FIG. It is an enlarged view of the input shaft shown in FIG. FIG. 6B is a cross-sectional view taken along line Z ₁₁ -Z ₁₁ shown in FIG. 6A. FIG. 6B is a cross-sectional view taken along line Z ₁₂ -Z ₁₂ shown in FIG. 6A. FIG. 6B is a sectional view taken along line Z ₁₃ -Z ₁₃ shown in FIG. 6A. FIG. 6B is a sectional view taken along the line Z ₁₄ -Z ₁₄ shown in FIG. 6A. It is a schematic plan view of the electric vehicle carrying an in-wheel motor drive device. It is the schematic sectional drawing which looked at the electric vehicle of Drawing 7 from back.

First, an outline of the electric vehicle 11 equipped with the in-wheel motor drive device will be described with reference to FIGS. As shown in FIG. 7, the electric vehicle 11 includes an chassis that drives each of a 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 left and right rear wheels 14. A wheel motor drive device 21. As shown in FIG. 8, the rear wheel 14 is accommodated in the wheel house 12a of the chassis 12, and is fixed to the lower part of the chassis 12 via the suspension device 12b.

The suspension device 12b supports the rear wheel 14 by a suspension arm extending 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 houses 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 noise / vibration / harshness characteristics (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, an in-wheel motor drive device 21 as shown in FIG. 1 is employed.

An example of an in-wheel motor drive device 21 in which a cycloid reduction gear according to an embodiment of the present invention is applied to a reduction unit will be described with reference to 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 the deceleration unit B to the rear wheel 14. (Refer to FIGS. 7 and 8) and a wheel bearing portion C for transmission to the casing 22, which are held by the casing 22. 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 house 12a (see FIG. 8) of the electric vehicle 11 while being housed in the casing 22.

The motor portion 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 motor rotating shaft 24 having a rotor 23b mounted on the outer periphery. The motor rotating shaft 24 is rotatable at a rotation speed of about 15000 rpm.

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”). It is rotatably supported with respect to the casing 22 by rolling

bearings

36, 36 respectively disposed in the section. The rolling bearing 36 is a so-called ball bearing, and is disposed between the outer ring fitted and fixed to the inner diameter surface of the casing 22, the inner ring fitted and fixed to the outer diameter surface of the motor rotating shaft 24, and the outer ring and the inner ring. And a cage for holding the plurality of balls in a state of being separated in the circumferential direction.

The wheel bearing portion C includes a hub ring 32 having a hollow structure and a wheel bearing 33 that rotatably supports the hub ring 32 with respect to the casing 22. The hub wheel 32 includes a cylindrical hollow portion 32a connected to the shaft portion 28b of the output shaft 28 constituting the speed reduction portion B, and a flange portion extending radially outward from the end portion on the outboard side of the hollow portion 32a. 32b integrally. Since the rear wheel 14 (see FIGS. 7 and 8) is connected and fixed to the flange portion 32b by the bolt 32c, the rear wheel 14 rotates integrally with the hub wheel 32 when the hub wheel 32 rotates.

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.

The main part of the speed reduction part B is composed of a cycloid speed reducer, the input shaft 25 that is rotationally driven by the motor part A, the output shaft 28 arranged coaxially with the input shaft 25, and the speed of the input shaft 25 is reduced. And a speed reduction mechanism that transmits the output to the output shaft 28. The output shaft 28 transmits the rotation of the input shaft 25 decelerated by the deceleration mechanism to the wheel bearing portion C.

As shown in FIG. 2A,

eccentric portions

25 a and 25 b whose shaft centers are eccentric with respect to the rotation shaft center of the input shaft 25 are provided at two positions in the axial direction of the input shaft 25. Two

eccentric portions

25 a and 25 b are provided integrally with the input shaft 25. The two

eccentric portions

25a and 25b are provided with phases different from each other by 180 ° in order to cancel the centrifugal force due to the eccentric motion to each other (to prevent the input shaft 25 from swinging).

The input shaft 25 is rotatably supported with respect to the output shaft 28 by rolling bearings (input shaft support bearings) 37 and 37 that are disposed apart from each other in two axial directions. Accordingly, the rolling

bearings

37 and 37 correspond to the second rolling bearing referred to in the present invention. One rolling bearing 37 is disposed on the inboard side with respect to the eccentric portion 25a to support the substantially central portion in the axial direction of the input shaft 25, and the other rolling bearing 37 is disposed on the outboard side with respect to the eccentric portion 25b. The end of the shaft 25 on the outboard side is supported. Each rolling bearing 37 is a so-called ball bearing (deep groove ball bearing), and is fitted to an inner ring 37 a fitted to the outer diameter surface of the input shaft 25 and an inner diameter surface of the output shaft 28 as shown in FIG. 2A. The outer ring 37b, a plurality of balls 37c disposed between the inner raceway surface of the inner ring 37a and the outer raceway surface of the outer ring 37b, and a cage (not shown) for holding the plurality of balls 37c spaced apart in the circumferential direction. ).

The fitting between each rolling bearing 37 (the outer ring 37b) and the output shaft 28 and the fitting between each rolling bearing 37 (the inner ring 37a) and the input shaft 25 may all be a tight fitting. In this case, it becomes difficult to assemble the cycloid reducer, and indentation or the like is formed on the raceway surface of the rolling bearing 37 in the process of assembling the rolling bearing 37, which may adversely affect the bearing performance and durability life of the rolling bearing 37. is there. Therefore, the fit between the outer ring 37b of the rolling bearing 37 and the output shaft 28 is an interference fit, and the fit between the inner ring 37a of the rolling bearing 37 and the input shaft 25 is a clearance fit.

The input shaft 25 fits 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. Thereby, the driving force of the motor part A is transmitted to the deceleration part B.

The input shaft 25 having the above configuration is formed of, for example, case-hardened steel such as SCM415, SCM420, and SCr420, and a hardened layer (surface hardened layer) H formed by carburizing, quenching, and tempering as heat treatment. Have. In the present embodiment, the entire input shaft 25 is carburized, quenched, and tempered. The hardness of the hardened layer H is about 660 to 780 in terms of Vickers hardness (Hv), and the hardness of the core (the portion where the hardened layer H is not formed) is about 25 to 38 in terms of Rockwell hardness C scale (HRC). It is.

The output shaft 28 has a shaft portion 28b and a flange portion 28a as shown in FIG. The flange portion 28a is formed with a hole portion (through hole in the illustrated example) into which an end portion on the outboard side of the inner pin 31 described later is fitted and fixed. The hole portion is a rotation of the speed reducer output shaft 28. A plurality are formed at equal intervals on the circumference centered on the axis. The shaft portion 28b is connected to the hub wheel 32 constituting the wheel bearing portion C by spline fitting. The output shaft 28 is rotatably supported with respect to the outer pin housing 60 via rolling

bearings

46 and 46.

The speed reduction mechanism is held at a fixed position of the outer pin housing 60 and the curved plates 26a and 26b that are rotatably fitted to the outer periphery of the

eccentric portions

25a and 25b via the rolling bearings 41 and 41 (see FIG. 3). A plurality of outer pins 27 engaged with the outer peripheral portions of the curved plates 26a, 26b, and a motion conversion mechanism for converting the rotational motion of the curved plates 26a, 26b into the rotational motion of the output shaft 28 are provided. Therefore, the rolling bearing 41 constitutes the first rolling bearing referred to in the present invention.

As shown in FIG. 3, the curved plate 26a has a plurality of waveforms composed 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 eccentric portion 25a (rolling bearing 41) of the speed reducer input shaft 25.

As shown in FIG. 3, the rolling bearing 41 has an inner raceway surface 42a on the outer diameter surface, and an inner ring 42 fitted to the outer diameter surface of the eccentric portion 25a, and an inner diameter surface of the through hole 30b of the curved plate 26a. A cylindrical roller including a directly formed outer raceway surface 43, a plurality of cylindrical rollers 44 disposed between the inner raceway surface 42a and the outer raceway surface 43, and a cage (not shown) that holds the cylindrical rollers 44. It is a bearing. The inner ring 42 has flanges 42b that protrude radially outward from both axial ends of the inner raceway surface 42a. In the rolling bearing 41 of the present embodiment, the inner raceway surface 42a is formed on the inner ring 42 provided separately from the eccentric portion 25a. However, the inner raceway surface is formed directly on the outer diameter surface of the eccentric portion 25a. The inner ring 42 may be omitted. In addition, although detailed description is abbreviate | omitted, the curved plate 26b has the structure similar to the curved plate 26a, and with respect to the eccentric part 25b by the rolling bearing 41 similar to the rolling bearing 41 which supports the curved plate 26a. It is supported rotatably.

As shown in FIG. 3, a plurality of outer pins 27 are provided at equal intervals on the circumference centering on the rotational axis of the speed reducer input shaft 25. When the curved plates 26a and 26b revolve with the rotation of the input shaft 25, the outer peripheral portions of the curved plates 26a and 26b and the outer pins 27 are engaged in the circumferential direction, and the curved plates 26a and 26b rotate. Cause it to occur. As shown in FIG. 1, each outer pin 27 includes a pair of rolling bearings (needle roller bearings) 61 and 61 and a pair of needle roller bearings arranged at the end portions on the inboard side and the outboard side, respectively. 61 and 61 are rotatably supported by the casing 22 via an outer pin housing 60 holding the inner periphery thereof. With this configuration, the contact resistance between the outer pin 27 and the curved plates 26a and 26b is reduced.

Although detailed illustration is omitted, 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 a motion conversion mechanism that absorbs a large radial load or moment load caused by turning or sudden acceleration / deceleration of the vehicle and converts the rotational motion of the curved plates 26a, 26b into the rotational motion of the reducer output shaft 28. This is to prevent damage.

Counterweights 29 are adjacently arranged on the outer sides in the axial direction of the

eccentric portions

25a and 25b, respectively. The counterweight 29 has a substantially fan shape and is fitted and fixed to the outer periphery of the 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 FIGS. 1 and 3, the motion conversion mechanism is composed of 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 rotation axis of the output shaft 28, and the end portion on the outboard side is fixed to the hole provided in the flange portion 28 a of the output shaft 28. Has been. Since the output shaft 28 is arranged coaxially with the input shaft 25, the rotational motion of the curved plates 26 a and 26 b is converted into rotational motion around the rotational axis of the input shaft 25 and then applied to the output shaft 28. Communicated. 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).

The reduction part B (cycloid reduction gear) further has a stabilizer 31b. 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. It is fixed to the annular portion 31c.

Here, the state of the load acting on the curved plate 26a 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 input shaft 25 is eccentric from the axis (rotation axis) O of the input shaft 25 by the amount of eccentricity e. Eccentric portion 25a, so that rotatably supports the curve plate 26a via a rolling bearing 41, the axis O ₂ is also the axis of the curved plate 26a. The outer peripheral portion of the curved plate 26a is formed by a waveform curve, and has concave portions 34 that are recessed inward in the radial direction at equal intervals in the circumferential direction. Around the curved plate 26 a, a plurality of outer pins 27 that are engaged with the recesses 34 in the circumferential direction are arranged in the circumferential direction around the axis O of the input shaft 25.

In FIG. 4, when the input shaft 25 rotates counterclockwise on the paper surface, the eccentric portion 25 a revolves around the axis O of the input shaft 25, so that the concave portion 34 of the curved plate 26 a is connected to the outer pin 27. Sequentially contact and engage in the circumferential direction. As a result, the curved plate 26a receives a load Fi as indicated by an arrow in the drawing from the plurality of outer pins 27, and rotates clockwise.

Further, the curve plates 26a and a plurality of circumferentially disposed around the through hole 30a is the axis O _2, the through holes 30a, is fixed to an output shaft 28 disposed on the input shaft 25 coaxially The inner pin 31 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 revolution movement of the curved plate 26a, and the output shaft 28 is extracted by taking out the rotational movement of the curved plate 26a. Rotate. At this time, the output shaft 28 has a higher torque and a lower rotational speed than the 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. The resultant force Fs of the plurality of loads Fi and Fj acts on the fitting portion of the input shaft 25 with the rolling

bearings

41 and 37 via the rolling

bearings

41 and 37.

The direction of the resultant force Fs changes due to the influence of the centrifugal force in addition to geometrical conditions such as the waveform shape of the curved plate 26a and the number of recesses 34. Specifically, through the rotation axis O _2, and the reference line X extending in the direction of 90 ° to the straight line Y connecting the the axis O rotation axis O _2, the angle α formed by the force Fs substantially Fluctuates between 30 ° and 60 °. The directions and magnitudes of the loads Fi and Fj change during one rotation of the input shaft 25. As a result, the resultant force Fs acting on the input shaft 25 also varies in the direction and magnitude of the load. . When the 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 shown in FIG.

Next, the lubrication mechanism will be explained. 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 2A, the lubricating

oil paths

24a and 24b provided on the motor rotating shaft 24 and the input Lubricating

oil passages

25c, 25e provided in the shaft 25 extending in the axial direction, lubricating oil passages 25a1, 25b1, 25d1, 25d2 provided in various axial directions of the input shaft 25 and provided in the stabilizer 31b. A lubricating oil passage (not shown), a lubricating oil passage (not shown) provided inside the inner pin 31, a lubricating oil discharge port 22b provided in the casing 22, a lubricating oil reservoir 22d, and a lubricating oil passage 22e. The main components are the lubricating oil passage 45 and the rotary pump 51 that is disposed in the casing 22 and pumps the lubricating oil to the circulating oil passage 45. The white arrow shown in FIG. 1 indicates the direction in which the lubricating oil flows.

Lubricating

oil passages

24 a and 24 b provided on the motor rotating shaft 24 extend in the axial direction and the radial direction inside the motor rotating shaft 24, respectively. The lubricating oil passage 24 a is provided inside the input shaft 25. A lubricating oil passage 25c extending in the axial direction is connected. As shown in FIG. 2A, each of the lubricating oil passages 25a1 and 25b1 provided on the input shaft 25 and extending in the radial direction has an inner diameter end portion that opens into the lubricating oil passage 25c, and an outer diameter end portion that is an eccentric portion 25a. , 25b. The lubricating oil passages 25 d 1 and 25 d 2 each have an inner diameter end portion that opens into the lubricating oil passage 25 c, and an outer diameter end portion of the rolling bearing (second rolling bearing) 37 of the outer diameter surface of the input shaft 25. It opens to fitting parts M1 and M2 into which the inner ring 37a is fitted. 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 input shaft 25 on the outboard side. From the above configuration, the lubricating oil passage 25c, the lubricating oil passage 25a1,25b1 and the lubricating oil passage 25d1,25d2, respectively, axial oil passage in the present invention, a first oil supply hole _{P 1} and the second oil supply hole _{P 2} Function.

Radially outer end portion of the lubricating oil passage 25d1 functioning as the second oil supply hole P ₂ is opened in the axial center portion of the fitting portion M1 of the inboard side. As shown in FIG. 2C, the lubricating oil passage 25d1 is provided at a position (two places) where the phase is different by 90 ° in the circumferential direction on one side and the other side with respect to the eccentric direction of the eccentric portion 25a (and 25b). . The outer diameter end portion of the lubricating oil passage 25d2 functioning as the second oil supply hole P ₂ is opened in the axial center portion of the fitting portion M2 of the outboard side. As shown in FIG. 2B, the lubricating oil passage 25d2 is provided at a position where the phase is different by 90 ° in the circumferential direction on one side and the other side with respect to the eccentric direction of the eccentric portion 25b (and 25a).

As shown in FIG. 1, the lubricating oil discharge port 22 b provided in the casing 22 discharges 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. ing. 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 45. 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 through the lubricating oil path 22e, the circulating oil path 45, 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 45 provided in the casing 22 includes an axial oil passage 45a 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 45a. Are connected to each other, and are constituted by

radial oil passages

45b and 45c extending in the radial direction. The radial oil passage 45b supplies the lubricating oil pumped from the rotary pump 51 to the axial oil passage 45a, and the lubricating oil supplied to the axial oil passage 45a passes through the radial oil passage 45c to the motor rotating shaft 24. Is supplied to the lubricating oil passage 24a of the speed reducer and the lubricating oil passage 25c of the reduction gear input shaft 25.

The rotary pump 51 is provided between the lubricating oil passage 22e connected to the lubricating oil reservoir 22d and the circulating oil passage 45. 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 output shaft 28, an outer rotor 53 that rotates following the rotation of the inner rotor 52, and between the

rotors

52 and 53. The cycloid pump includes a plurality of pump chambers 54 provided in the space, a suction port 55 communicating with the lubricating oil passage 22e, and a discharge port 56 communicating with the radial oil passage 45b of the circulation oil passage 45. The inner rotor 52 rotates around the rotation center c ₁ , and the outer rotor 53 rotates around a rotation center c ₂ different from the rotation center c ₁ of the inner rotor 52. Thus, since the inner rotor 52 and the outer rotor 53 rotate about different rotation centers c ₁ and c ₂ , the volume of the pump chamber 54 changes continuously. Thereby, 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 45 b of the circulating oil passage 45.

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

First, in the motor part A, the lubrication of the rotor 23b and the stator 23a is mainly supplied to the lubricating oil path 24a of the motor rotating shaft 24 via the circulating oil path 45 of the casing 22, as shown in FIG. A part of the lubricating oil is discharged from the outer diameter end portion of the lubricating oil passage 24 b under the influence of the centrifugal force generated with the rotation of the motor rotating shaft 24 and the pressure of the rotary pump 51. That is, the lubricating oil discharged from the outer diameter end of the lubricating oil passage 24b is supplied to the rotor 23b and then supplied to the stator 23a. The rolling bearing 36 that supports the end of the motor rotating shaft 24 on the inboard side is mainly lubricated by a part of the lubricating oil flowing through the circulating oil passage 45 oozing out between the casing 22 and the motor rotating shaft 24. Is done. The rolling bearing 36 that supports the end portion of the motor rotating shaft 24 on the outboard side is mainly discharged from the lubricating oil passage 24b and travels along the inner wall surface of the casing 22 where the motor portion A is accommodated. It is lubricated by the falling lubricant.

Next, the lubricating oil flowing into the lubricating oil passage 25c (axial oil passage) of the input shaft 25 via the lubricating oil passage 24a of the motor rotating shaft 24 and flowing through the lubricating oil passage 25c is supplied to the input shaft 25. centrifugal and radially outer end of the lubricating oil passage 25d1,25d2 as the lubricating oil passage 25a1,25b1 and second oil supply hole _{P 2} as a first oil supply hole _{P 1} under the influence of the pressure of the rotary pump 51 caused by the rotation of the Is discharged into the deceleration portion B (deceleration mechanism). 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.

More particularly, lubricating oil discharged from the radially outer end portion of the lubricating oil passage 25a1,25b1 as a first oil supply hole _{P 1} is a rolling bearing for supporting the curved plates 26a, a 26b 41, 41 (see FIG. 3) Is supplied to the raceway surfaces 42a and 43 and the cylindrical rollers 44 are lubricated. Further, due to the action of centrifugal force, the abutting portions between the curved plates 26a and 26b and the inner pin 31, the abutting portions between the curved plates 26a and 26b and the outer pin 27, etc. are moved radially outward while being lubricated.

On the other hand, the lubricating oil discharged from the radially outer end portion of the lubricating oil passage 25d1,25d2 as a second oil supply holes _{P 2,} of the outer diameter surface of the input shaft 25, a rolling bearing for supporting the input shaft 25 (second The

bearings

37 and 37 are supplied to the inside of the rolling

bearings

37 and 37 by the action of centrifugal force while lubricating the fitting portions M1 and M2 with the rolling

bearings

37 and 37 and the inner ring 37a inner diameter surface of each rolling bearing 37. Lubricate. In particular, the lubricating oil discharged from the outer diameter end of the lubricating oil passage 25d1 passes through a lubricating oil passage (not shown) in the stabilizer 31b and a lubricating oil passage (not shown) in the inner pin 31. It is supplied to a rolling bearing 31a that supports the inner pin 31. Further, similarly to the lubricating oil discharged from the lubricating oil passages 25a1 and 25b1, due to centrifugal force, the abutting portion between the curved plates 26a and 26b and the inner pin 31 and the contacting between the curved plates 26a and 26b and the outer pin 27 are achieved. The part, the rolling bearing 61 that supports the outer pin 27, the rolling bearing 46 that supports the reduction gear output shaft 28, and the like are moved radially outward while being lubricated.

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. Thus, since the lubricating oil storage part 22d is provided between the lubricating oil discharge port 22b and the lubricating oil passage 22e connected to the rotary pump 51, the lubricating oil is agitated by stirring especially during high-speed rotation. Even if the amount of the lubricating oil staying inside and reaching the lubricating oil discharge port 22b temporarily decreases, the lubricating oil stored in the lubricating oil reservoir 22d can be returned to the lubricating

oil passages

24a and 25c. The lubricating oil can be stably supplied to the motor part A and the speed reducing part B. As a result, it is possible to prevent heat generation at various portions of the deceleration portion B.

In addition, the lubricating oil inside the deceleration part B moves to the outside by gravity in addition to the 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.

As described above, in the cycloid reduction gear (deceleration unit B) of the present embodiment, the inner rings 37a of the rolling bearings (second rolling bearings) 37 and 37 that support the input shaft 25 are clearance-fitted to the input shaft 25. The second oil supply hole P ₂ (lubricating oil passage 25d1, the input shaft 25 extends in the radial direction, and the outer diameter end portion opens to the fitting portions M1, M2 with the rolling

bearings

37, 37. 25d2). In this way, the lubricating oil flowing in the lubricating oil passage 25c (axial oil passage) of the input shaft 25 is used as the fitting portions M1 and M2 (the rolling bearing 37 for the rolling bearing 37) between the input shaft 25 and the rolling

bearings

37, 37. (Radial clearance formed by fitting with the input shaft 25 by clearance fitting), and by extension, can be efficiently supplied to the inside of the rolling bearing 37. This effectively prevents wear of the fitting portions M1 and M2 with the rolling

bearings

37 and 37 and the inner diameter surface of the inner ring 37a of each rolling bearing 37 out of the outer diameter surface of the input shaft 25, resulting in misalignment. In addition to preventing the generation of abnormal noise and vibration, the internal wear of the rolling

bearings

37 and 37 is effectively prevented, and the generation of abnormal noise and vibration due to the internal wear of the rolling

bearings

37 and 37 is prevented. be able to.

In particular, the second outer diameter end of the oil supply hole _{P 2,} since is opened in the axial center portion of the fitting portion M1, M2, the fitting portion M1, M2 of the rolling

bearings

37 and 37, and rolling each Lubricating oil is easily spread over the entire inner diameter surface of the inner ring 37a of the bearing 37. Thereby, the wear of the fitting portions M1 and M2 and the inner surface of the inner ring 37a of each rolling bearing 37 can be more effectively prevented. Incidentally, in particular, when is opened a second outer diameter end of the oil supply hole P ₂ in the axial center portion of the fitting portion M1, M2, the second oil supply hole to the position directly below the inner raceway surface of the rolling bearing 37 since the outer diameter end portion of the P ₂ will be located, when the load radially inward into the rolling bearing 37 by the actuation of the cycloid reducer acts raceways of the rolling bearing 37 (particularly the inner raceway surface) There is a possibility of deformation. If the raceway surface of the rolling bearing 37 is deformed, it may cause abnormal noise and vibration, and may cause a shortened life of the rolling bearing 37.

To prevent such a problem occurs as much as possible, the opening diameter of the radially outer end portion of the second oil supply hole P ₂ is preferably 40% or less of the ball 37c diameter of the rolling bearing 37. However, when the opening diameter of the second outer diameter end of the oil supply hole P ₂ is too small, other workability is lowered, fitting portions M1, M2, and sufficiently lubricated as possible the inner ring 37a radially inner surface of the rolling bearings 37 It becomes difficult to discharge the lubricating oil. Therefore, the opening diameter of the second outer diameter end of the oil supply hole P ₂ is preferably at least 10% of the diameter of the ball 37c.

Here, as described with reference to FIG. 4, as the input shaft 25 rotates, the

load bearings

41 and 37, and further, the load on the fitting portions of the input shaft 25 with the rolling bearings 41 and 37 ( The resultant force Fs) acts, but the direction and magnitude of the load vary depending on various conditions, and the load actually acts on a partial region in the circumferential direction. Specifically, in the present embodiment in which the input shaft 25 rotates counterclockwise when viewed from the outboard side, the end portion on the outboard side of the input shaft 25 is supported as the input shaft 25 rotates. The inner ring 37a (and its fitting portion M2) of the rolling bearing 37, the inner ring 42 (and its fitting portion) of the rolling bearing 41 that supports the curved plate 26b, and the inner ring 42 (and the rolling bearing 41 that supports the curved plate 26a). 6B to 6E are hatched in each of the fitting portion) and the inner ring 37a (and its fitting portion M1) of the rolling bearing 37 that supports the substantially central portion of the input shaft 25 in the axial direction. A load acts on the load area E.

In the present embodiment, as described above, the lubricating oil passage 25d2 (second oil supply hole P ₂ ) opened in the fitting portion M2 has one side in the circumferential direction and the other side in the eccentric direction of the

eccentric portions

25a and 25b. In this case, the outer diameter end portion of one lubricating oil passage 25d2 is a rolling bearing 37 that supports the end portion of the input shaft 25 on the outboard side. Open to the entrance side of the load area E (see FIG. 6B). Further, the lubricating oil passage 25d1 (second oil supply hole P ₂ ) opened to the fitting portion M1 has a phase that is 90 ° different in the circumferential direction on one side and the other side with respect to the eccentric direction of the

eccentric portions

25a and 25b. In this case, the outer diameter end portion of one lubricating oil passage 25d1 opens to the inlet side of the load load region E of the rolling bearing 37 that supports the substantially central portion in the axial direction of the input shaft 25 ( (See FIG. 6E). Although illustration is omitted, when the input shaft 25 rotates clockwise as viewed from the outboard side, the load area E is in relation to the symmetry plane including the eccentric direction of the

eccentric portions

25a and 25b and the rotational axis of the input shaft. In this case, the outer diameter ends of the other lubricating oil passages 25d2 and 25d1 open to the inlet side of the load load area E.

In short, the second oil supply hole P _2, the eccentric portion 25a, if provided phase at two locations having different 90 ° in the one circumferential direction and relative to the eccentric direction of 25b the other side, the rotational direction of the input shaft 25 Regardless, the outer diameter end portion of any one of the second oil supply holes P < _b > ₂ can be positioned on the inlet side of the load load area E of each rolling bearing 37. Therefore, when the rotation of the input shaft 25, the lubricating oil supplied to the fitting portion M1, M2 via the second oil supply hole P _2, the fitting portion M1 of the rolling bearing 37, M2, and each rolling bearing 37 It can supply efficiently to the area | region where a load is substantially loaded among the inner ring | wheels 37a inner diameter surface. As a result, of the outer diameter surface of the input shaft 25, the fitting portions M1, M2 with the second rolling bearing (rolling bearing 37) and the inner diameter surface of the inner ring 37a of each rolling bearing 37 are more effectively worn. Can be prevented. Further, the second oil supply hole P ₂ by forming the above manner to prevent whirling of the input shaft 25 can be avoided the collapse of the weight balance of the input shaft 25 due to the provision of the (1) second oil supply hole P ₂ (2) Since there is no need to create and use two types of input shafts 25 according to the rotation direction, it is possible to reduce the management man-hours and to prevent erroneous assembly of the input shafts 25. You can also enjoy the benefits of being able to.

Further, in the present embodiment, the lubricating oil passage 25a1,25b1 functioning as the first oil supply hole _{P 1,} it is provided at positions having different 180 ° phase relative to the eccentric direction of the

eccentric portion

25a, 25b, in this case The outer diameter end portions of the lubricating oil passages 25a1 and 25b1 open near the inlet side of the load load area E of the rolling

bearings

41 and 41 that support the curved plates 26a and 26b on the outer diameter surface of the input shaft 25 ( (See FIGS. 6D and 6C). Therefore, the lubricating oil supplied to the raceway surfaces 42 a and 43 of the rolling bearing 41 through the first oil supply hole P ₁ and the oil holes provided in the inner ring 42 of the rolling bearing 41 is caused by the rotation of the input shaft 25. The load can be efficiently supplied to the load area E where the load is substantially applied.

Furthermore, in this embodiment, since the input shaft 25 has a hardened layer H formed by carburizing, quenching and tempering on the surface layer portion, the surface hardness of the outer diameter surface of the speed reducer input shaft 25 is sufficiently increased. It has been. Therefore, in accordance with the operation of the deceleration unit B, the rolling bearings (first rolling bearings) 41 and 41 that support the curved plates 26a and 26b and the rolling bearings (second rolling bearings) 37 and 37 that support the input shaft 25 are provided. Even when a load is applied to the input shaft 25 through the outer diameter surface, it is possible to prevent the outer diameter surface of the input shaft 25 from being worn or damaged.

Moreover, in the in-wheel motor drive device 21 of this embodiment which employ | adopted the cycloid reduction gear for the deceleration part B, the direction and magnitude | size of a load are from the curved board 26a, 26b with respect to the input shaft 25 at the time of the drive of the motor part A. Fluctuating radial load and moment load are applied. For this reason, torque transmission in the spline fitting portion formed by fitting the spline formed on the motor rotation shaft 24 and the spline 25g formed on the input shaft 25 is the center of the motor rotation shaft 24 and the input shaft 25. Is often performed in a state of being tilted to some extent or being misaligned. Therefore, a relatively large frictional force or load is applied to the spline fitting portion of the input shaft 25 and the motor rotating shaft 24, but the hardened layer H is formed on the surface layer portion of the input shaft 25 including the portion where the spline 25g is formed. Therefore, the wear resistance and the like of the spline 25g can be enhanced to prevent the spline 25g from being worn or damaged as much as possible.

Moreover, since the hardened layer H is not formed in the core part of the input shaft 25 formed of case-hardened steel, the input shaft 25 has toughness. Thereby, it is possible to withstand an instantaneous impact load that is input to the input shaft 25 via the wheel bearing portion C during driving of the vehicle.

In particular the input shaft 25 of the present embodiment includes an

eccentric portion

25a, and 25b together, and the lubricating oil passage 25c as axial oil passage constituting a lubrication mechanism, lubrication of the first oil supply hole P ₁ oil passage 25A1,25b1, and the second oil supply hole on relationships with such lubricating oil passage 25d1,25d2 as _{P 2,} the shape is increased complexity and manufacturing cost is concerned. On the other hand, as the forming material of the input shaft 25, case hardening steel that is relatively soft and rich in workability is selected at the stage before carburizing, quenching, and tempering, so that the production cost of the input shaft 25 is effectively suppressed. Can do.

As described above, according to the present invention, wear at the fitting portions M1, M2 between the input shaft 25 and the

support bearings

37, 37, wear of the raceway surfaces of the

support bearings

37, 37, and the like can be effectively suppressed. A cycloid reducer can be realized. Thereby, the cycloid reduction gear excellent in acoustic performance, durable life, etc., and the in-wheel motor drive device 21 which mounts this by extension can be provided.

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

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. Thereby, the revolution movement of the curved plates 26 a and 26 b is not transmitted to the inner pin 31, but only the rotational motion of the curved plates 26 a and 26 b is transmitted to the wheel bearing portion C via the output shaft 28. At this time, the rotation of the input shaft 25 is transmitted to the output shaft 28 after being decelerated by the decelerating unit B. Therefore, even when the low-torque, high-rotation type motor unit A is employed, the drive wheels (rear wheels) 14 It is possible to transmit the torque required for.

The speed reduction ratio of the speed reduction portion B having the above-described configuration is (Z _A −Z _B ) / Z _B , where Z _{A is} the number of outer pins 27 and Z _B is the number of waveforms provided on the outer peripheral portions of the curved plates 26a and 26b. Is calculated by 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 reduction part B that can obtain a large reduction ratio without using a multistage configuration, the in-wheel motor drive device 21 having a compact and high 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 resistance is reduced, the power transmission efficiency in the deceleration part B improves.

As described above, the in-wheel motor drive device 21 of the present embodiment is lightweight 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 embodiment described above, the material for forming the motor rotation shaft 24 is not particularly mentioned, but the motor rotation shaft 24 is made of case-hardened steel that has been carburized, quenched, and tempered, like the input shaft 25. Can be formed. In this case, since the thermal expansion amounts of the motor rotating shaft 24 and the input shaft 25 are substantially equal, it is possible to prevent the connection state of the two

shafts

24 and 25 from changing as much as possible even when the motor unit A is driven. Can do. Thereby, power transmission between the two

shafts

24 and 25 can be stably performed. In addition, if the motor rotating shaft 24 is formed with the said material, the motor rotating shaft 24 can be produced simply and surface hardness and abrasion resistance in the fitting part of other members (the rolling bearing 36 and the rotor 23b) are good. A motor rotating shaft 24 that is excellent and has the required toughness can be realized.

In the above description, the cycloid pump is used as the rotary pump 51. However, the rotary pump 51 is not limited to this, and any rotary pump driven using the rotation of the output shaft 28 can be used. 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 input shaft 25. However, the number of formed eccentric portions can be arbitrarily set. For example, the eccentric portions can be provided at three positions in the axial direction of the input shaft 25. In this case, the eccentric portions change the phase by 120 ° so as to cancel the centrifugal force generated by the rotation of the input shaft 25. It is preferable to provide it.

In the above description, the motion conversion mechanism is configured by the inner pin 31 having one end fixed to the flange portion 28a of the output shaft 28 and the through hole 30a provided in the curved plates 26a and 26b. It is possible to adopt an arbitrary configuration that can transmit the rotation of the part B to the hub wheel 32.

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 the in-wheel motor drive device 21 that employs a radial gap motor for the motor portion A. However, the present invention is configured such that the stator and the rotor are connected to the motor portion A via an axial gap. The present invention can also be preferably applied to an in-wheel motor drive device that employs an axial gap motor to be opposed.

Furthermore, the in-wheel motor drive device in which the cycloid reduction gear according to the present invention is applied to the speed reduction part B is not only the rear wheel drive type electric vehicle 11 having the rear wheel 14 as the drive wheel, but also the front wheel 13 as the drive wheel. The present invention can also be applied to a front-wheel drive type electric vehicle and a four-wheel drive type electric vehicle using the front wheels 13 and the rear wheels 14 as drive wheels. 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.

Further, the cycloid reduction gear according to the present invention can be preferably applied to a drive device for an electric vehicle other than the in-wheel motor drive device, for example, a reduction portion of an on-board drive device (not shown).

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.

In order to demonstrate the usefulness of the present invention, a reduction gear specimen (example) having the configuration of the present invention and a reduction gear specimen (comparative example) not having the configuration of the present invention, It was confirmed how much difference occurred in the amount of wear at the fitting portion with the support bearing and the amount of wear on the inner ring inner surface of the support bearing. The only difference between the example and the comparative example is whether or not the input shaft is provided with a radially extending oil supply hole (second oil supply hole P ₂ ) opened in the fitting portion with the support bearing. The configuration is common to the examples and comparative examples. Specifically, specimens according to Examples and Comparative Examples were manufactured using an input shaft and a support bearing as described below. Incidentally, formation of the second oil supply hole P ₂ in the input shaft according to the embodiment similar to that shown in FIG. 2, and the opening diameter of the second oil supply hole P ₂ was 2 mm. The fit between the input shaft and its support bearing was a clearance fit in which a fit clearance of about 0 to 0.015 mm was formed.
(1) Input shaft: formed of case-hardened steel and carburized, quenched, and tempered to provide a hardened layer on the surface layer. The surface hardness is about 660 to 780 HV in terms of Vickers hardness.
(2) Support bearing: Deep groove ball bearing using a ball having a diameter of 7.9375 mm, each member formed of SUJ2 material that has been subjected to continuous quenching (surface hardness is 58 on the Vickers hardness C scale) ~ About 63).

Then, when a load corresponding to the turning of the vehicle was applied to each specimen, in the specimen according to the comparative example, the wear amount in the support bearing fitting portion of the input shaft and the wear amount in the inner ring inner surface of the support bearing were The maximum radial dimension was about 30 μm and about 20 μm, respectively. On the other hand, in the specimen according to the example, the wear amount at the support bearing fitting portion of the input shaft and the wear amount at the inner ring inner surface of the support bearing were both less than 1 μm in the radial dimension. Further, in the specimen according to the comparative example, the support bearing raceway surface of the input shaft was worn by the wear powder, but in the specimen according to the example, the surface condition of the support bearing raceway surface of the input shaft was good. there were.

Further, as a specimen according to the example, the ball diameter using a deep groove ball bearing is 5.55625Mm, and was also performed to confirm the wear amount for that the second opening diameter of the oil supply hole P ₂ and 1 mm. Also in this case, as described above, the wear amount at the support bearing fitting portion of the input shaft and the wear amount at the inner ring inner surface of the support bearing were both less than 1 μm in the radial dimension. The surface condition of the support bearing raceway surface of the input shaft was also good as described above.

As described above, the present invention is extremely useful in realizing a cycloid reduction gear that can effectively suppress wear at the fitting portion between the input shaft and its support bearing, and further wear on the raceway surface of the support bearing. It was confirmed.

DESCRIPTION OF SYMBOLS 11 Electric vehicle 21 In-wheel motor drive device 25

Input shaft

25a, 25b Eccentric part 25a1, 25b1 Lubricating oil path (1st oil supply hole)
25c Lubricating oil passage (axial oil passage)
25d1, 25d2 Lubricating oil passage (second oiling hole)
26a, 26b Curved plate 27 Outer pin 28 Output shaft 31 Inner pin 37 Second rolling bearing 41 First rolling bearing A Motor part B Reduction part (cycloid reduction gear)
C Wheel bearing part E Load area H Hardened layer M1, M2 Fitting part P ₁ 1st oil hole P ₂ 2nd oil hole

Claims

An input shaft having an eccentric portion, and a curved plate that is rotatably fitted to the outer periphery of the eccentric portion via a first rolling bearing and performs a revolving motion around the rotational axis as the input shaft rotates. A plurality of outer pins that engage with the outer periphery of the curved plate to cause the curved plate to rotate, a motion conversion mechanism that converts the rotational motion of the curved plate into a rotational motion of an output shaft, and the input shaft And a second rolling bearing that rotatably supports the output shaft, an axial oil passage extending in the axial direction inside the input shaft, a radial oil passage extending in the axial direction, and the inside of the axial oil passage. A cycloid reducer provided with a first oil supply hole for supplying the flowing lubricating oil to the first rolling bearing,
Fitting the second rolling bearing to the input shaft with a clearance fit,
The input shaft further includes a second oil supply hole extending in a radial direction, having an inner diameter end opened in the axial oil passage and an outer diameter end opened in a fitting portion with the second rolling bearing. A cycloid reducer characterized by.
The cycloid reducer according to claim 1, wherein an outer diameter end portion of the second oil supply hole is opened at an axially central portion of the fitting portion.
The cycloid reducer according to claim 1 or 2, wherein the eccentric portion is provided at two positions in the axial direction of the input shaft with a phase difference of 180 °.
The first oil supply hole is provided at a position where the phase is different by 90 ° on one side and the other side in the circumferential direction with respect to the eccentric direction of the eccentric portion. The cycloid reducer described in 1.
The second rolling bearing is a ball bearing having an inner ring and an outer ring that rotate relative to each other via a ball, and an opening diameter of an outer diameter end portion of the second oil supply hole is 10% to 40% of the diameter of the ball. The cycloid reducer according to any one of claims 1 to 4, wherein
The cycloid reducer according to any one of claims 1 to 5, wherein the input shaft is formed of case-hardened steel and is subjected to carburizing, quenching and tempering as a heat treatment.
An in-wheel motor drive device having a motor part, a speed reduction part and a wheel bearing part,
The cycloid reducer according to any one of claims 1 to 6 is applied to the speed reduction unit, and the input shaft constituting the cycloid speed reducer is connected to a rotation shaft of the motor unit so as to transmit torque. An in-wheel motor drive device.