WO2015133277A1

WO2015133277A1 - In-wheel motor drive device

Info

Publication number: WO2015133277A1
Application number: PCT/JP2015/054466
Authority: WO
Inventors: 雪島　良; 鈴木　稔; 朋久魚住
Original assignee: Ntn株式会社; 雪島　良; 鈴木　稔; 朋久魚住
Priority date: 2014-03-04
Filing date: 2015-02-18
Publication date: 2015-09-11
Also published as: JP2015166224A; JP6333579B2

Abstract

An in-wheel motor drive device (21) is configured in such a manner that a motor section (A), a speed reduction section (B), and a bearing section (C) for a wheel, which are sequentially arranged from the inboard side of a vehicle to the outboard side thereof, are held by a casing (22), the speed reduction section (B) being provided with: a speed reducer input shaft (25) rotated and driven by the motor section (A); and a speed reducer output shaft (28) for transmitting the rotation of the speed reducer input shaft (25), the speed of the rotation having been reduced, to the bearing section (C) for a wheel. The speed reducer output shaft (28) has a weakest section (W) at a position closer to the inboard side than the section where the speed reducer output shaft (28) and the bearing section (C) for a wheel are connected. Among the sections of the power transmission system of the device, the weakest section (W) has the lowest strength against external force inputted into the device.

Description

In-wheel motor drive device

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

A conventional in-wheel motor drive device is disclosed in, for example, Patent Document 1 below. The in-wheel motor drive device is housed inside the wheel or placed near the wheel, so its weight and size affect the unsprung weight (running performance) of the vehicle and the size of the passenger compartment. Effect. For this reason, the in-wheel motor drive apparatus needs to make the whole apparatus as lightweight and compact as possible. Therefore, in the in-wheel motor drive device of Patent Document 1, the rotation of the motor unit is decelerated between the motor unit that generates the driving force and the wheel bearing unit to which the wheel is attached and fixed to the wheel bearing unit. By providing a speed reducing portion for transmission, the motor portion, and thus the entire device is reduced in size. The motor part, the speed reduction part and the wheel bearing part are held in a casing, and the casing is attached to the vehicle body via a suspension device (suspension) (not shown).

Further, in the above-described in-wheel motor drive device, in order to obtain a large torque required for the wheel bearing portion while promoting weight reduction and compactness, the motor portion has a low torque and a high rotation type (for example, 15000 min ^−1). A cycloid reducer that is compact and provides a high reduction ratio in the reduction part.

JP 2012-148725 A

As described above, since the entire in-wheel motor drive device is housed inside the wheel or disposed in the vicinity of the wheel, the vehicle equipped with the in-wheel motor drive device is not suitable for having irregularities or obstacles. When traveling on the road, a large external force is input to the inside of the in-wheel motor drive device via the wheels, and accordingly, components / members (power transmission components and power components constituting the power transmission system of the in-wheel motor drive device). The transmission shaft may be damaged. Such a problem can be prevented as much as possible by, for example, increasing the thickness of the power transmission component or increasing the shaft diameter of the power transmission shaft. However, if such measures are taken, the in-wheel motor drive device will be increased in size and weight, which is contrary to the demand for lighter and more compact devices. There is also a problem that the cost of the apparatus is increased.

In view of the above situation, the present invention can mitigate the adverse effects on the internal components of the device when there is an excessive external input without incurring an increase in size, weight and cost of the device. An object is to provide a wheel motor driving device.

The present invention, which was created to achieve the above object, includes a motor part, a reduction part, and a wheel bearing part, which are arranged in order from the inboard side to the outboard side of the vehicle, and are held in the casing. An in-wheel motor drive comprising: a reduction gear input shaft that is rotationally driven by the motor portion; and a reduction gear output shaft that is coupled to the wheel bearing portion and transmits the reduced speed reduction gear input shaft to the wheel bearing portion. In the device, the speed reducer output shaft is located on the inboard side of the connecting portion with the wheel bearing portion, and the strength against an external force input into the device via the wheel bearing portion is within the power transmission system of the device. It is characterized by having the lowest weakest part. The inboard side and the outboard side of the vehicle are synonymous with the vehicle width direction inner side and the vehicle width direction outer side of the vehicle, respectively.

According to the above configuration, when a large external force is input to the inside of the device via the wheel bearing portion, the weakest portion provided on the output shaft of the speed reducer is preferentially broken, so that the inner portion is less than the weakest portion. It is possible to prevent an excessive external force from being transmitted to the board side as much as possible. As a result, a large external force acts on the speed reduction part and motor part arranged on the inboard side (downstream of the external force transmission direction) with respect to the weakest part. As a result, internal parts of the speed reduction part (components of the speed reduction mechanism) In addition, it is possible to prevent the rotating shaft or the like of the motor unit from being damaged or broken as much as possible. Moreover, according to the said structure, damage, a fracture | rupture, etc. of the component of the wheel bearing part can be prevented as much as possible. For this reason, it is not necessary to increase the thickness of other parts / parts constituting the power transmission system of the in-wheel motor drive device, and the size, weight, and cost of the device can be avoided.

Since the wheel bearing portion is held in the casing, the wheel bearing portion is idled even if the reduction gear output shaft breaks at the weakest portion on the inboard side of the connecting portion with the wheel bearing portion. Thus, it is possible to prevent the occurrence of a fatal problem such that the wheel bearing portion and the wheel connected and fixed to the wheel bearing portion are separated from and detached from the chassis (suspension).

As the reduction gear output shaft, a shaft portion having the weakest portion and the connecting portion and a flange portion to which the rotation of the reduced reduction gear input shaft is transmitted (integrated flange type) is used. In addition, a shaft portion having the weakest portion and the connecting portion, and a flange portion that is detachably connected to the shaft portion and transmits the rotation of the reduced speed reducer input shaft (for each flange) Body type) can also be used. In particular, if a reduction gear output shaft with a separate flange is used, even if the reduction gear output shaft (shaft portion) breaks at the weakest part as a large external force is input to the inside of the device, the shaft portion It is sufficient to replace the shaft with a new one, and it is not necessary to replace the entire output shaft of the reduction gear. Therefore, there is an advantage that labor and cost required for maintenance can be reduced.

The weakest part can be formed, for example, by making the cross-sectional area in the cross section perpendicular to the axis smaller than the other part of the reducer output shaft, and the hardness is made lower than the other part of the reducer output shaft. It can also be formed. Moreover, the weakest part can also be formed by using these means together.

A seal member may be provided in a region between the reduction gear output shaft and the wheel bearing portion and closer to the inboard side than the weakest portion. In this way, it is possible to prevent, as much as possible, debris generated when the speed reducer output shaft breaks at the weakest part, etc., entering the inside of the speed reduction part (inside the speed reduction mechanism). it can. Therefore, it is possible to prevent adverse effects on the function and performance of the speed reduction unit, and it is possible to facilitate maintenance work required after the reduction gear output shaft is broken.

In the above configuration, as the speed reducer, a revolving member that is rotatably held by an eccentric portion provided on the speed reducer input shaft and performs a revolving motion centering on the rotation axis as the speed reducer input shaft rotates. The outer peripheral engagement member that engages with the outer peripheral portion of the revolution member and causes the revolution member to rotate, and the revolution movement of the revolution member is converted into a rotation movement around the rotation axis of the speed reducer input shaft. In addition, it is possible to employ a mechanism further including a motion conversion mechanism that transmits to the output shaft of the reduction gear.

As described above, according to the present invention, an in-wheel motor drive device that can alleviate the adverse effects on the components of the device when there is an excessive external input without increasing the size and weight of the device is realized. be able to.

It is a figure which shows the in-wheel motor drive device which concerns on 1st Embodiment of this invention. FIG. 2 is a cross-sectional view taken along line OO in FIG. It is explanatory drawing which shows the load which acts on the curve board of FIG. It is a cross-sectional view of the rotary pump of FIG. It is a principal part enlarged view of FIG. It is a principal part enlarged view of the in-wheel motor drive device which concerns on 2nd Embodiment of this invention. It is a principal part enlarged view of the in-wheel motor drive device which concerns on 3rd Embodiment of this invention. It is a schematic plan view of an electric vehicle. It is the schematic sectional drawing which looked at the electric vehicle shown in FIG. 8 from back.

The outline of the electric vehicle 11 equipped with the in-wheel motor drive device will be described with reference to FIGS. An electric vehicle 11 shown in FIG. 8 has an in-wheel motor drive that drives 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, respectively. Device 21. As shown in FIG. 9, the rear wheel 14 is accommodated in the wheel housing 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 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 that 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, an in-wheel motor drive device 21 as shown in FIG. 1 is employed.

The in-wheel motor drive device 21 according to the first embodiment of the present invention 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 from the deceleration unit B to the rear wheels. 14 (see FIGS. 8 and 9), and wheel bearing portions C that are transmitted to the vehicle, and these are arranged in order from the inboard side (right side in FIG. 1) to the outboard side (left side in FIG. 1) of the vehicle. It is held in the casing 22 above. Moreover, although mentioned later for details, this in-wheel motor drive device 21 has a lubrication mechanism which supplies lubricating oil to each part of the motor part A and the deceleration part B. FIG. The motor part A and the speed reduction part B are mounted in a wheel housing 12a (see FIG. 9) of the electric vehicle 11 while being housed in the casing 22.

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 motor rotating shaft 24 having a rotor 23b mounted on the outer periphery. Is a radial gap motor. In the motor portion A, when an external force exceeding a predetermined value is applied to the rear wheel 14 during driving (more specifically, the reduction gear output shaft 28 is broken by the external force being input to the power transmission system). When a control device (not shown) detects this, the driving of the motor rotating shaft 24 is immediately stopped.

The motor rotating shaft 24 is rotatably supported with respect to the casing 22 by rolling

bearings

36 and 36 arranged at one end and one end in the axial direction, respectively. The rolling bearing 36 is a so-called deep groove ball bearing, and is interposed between an outer ring fitted and fixed to the inner diameter surface of the casing 22, an inner ring fitted and fixed to the outer diameter surface of the motor rotating shaft 24, and the outer ring and the inner ring. A plurality of balls disposed; and a cage for holding the plurality of balls in a circumferentially spaced state.

The motor rotating shaft 24 is made of case-hardened steel such as SCM415 or SCM420, for example, and has a hardened layer formed by carburizing, quenching and tempering. Although not shown in detail, the hardened layer is formed in a portion of the motor rotating shaft 24 where at least the rotor 23b and the inner ring of the rolling bearing 36 are fitted and fixed. Thereby, the deformation | transformation, abrasion, damage, etc. of the motor rotating shaft 24 accompanying the assembly | attachment of the rotor 23b and the rolling bearing 36 are prevented as much as possible. In the motor rotating shaft 24, the hardness of the portion where the hardened layer is formed is about HRC62 to 66.5, and the hardness of the core is about HRC29 to 38.

The speed reduction part B decelerates the rotation of the speed reducer input shaft 25 rotated by the motor rotational shaft 24, the speed reducer output shaft 28 arranged coaxially with the speed reducer input shaft 25, and the speed reducer input shaft 25. The reduction gear output shaft 28 transmits the rotation of the reduction gear input shaft 25 decelerated by the reduction gear mechanism to the wheel bearing portion C. The speed reducer input shaft 25 has two

eccentric portions

25a and 25b, and the substantially central portion in the axial direction and the end portion on the outboard side rotate with respect to the speed reducer output shaft 28 by rolling

bearings

37a and 37b, respectively. It is supported freely. The two

eccentric portions

25a and 25b are provided so as to have a phase difference of 180 ° in order to cancel the centrifugal force caused by the eccentric motion.

The speed reducer input shaft 25 has a spline fitting (a spline or serration) formed on the end portion on the inboard side and a tooth surface formed on the end portion on the outboard side of the motor rotating shaft 24 ( Including the serration fitting, the same applies hereinafter), and the driving force of the motor part A is transmitted to the speed reduction part B. The connecting portion (spline fitting portion) between the motor rotating shaft 24 and the speed reducer input shaft 25 is configured to suppress the influence on the motor rotating shaft 24 even if the speed reducer input shaft 25 is inclined to some extent.

The speed reduction mechanism constituting the speed reduction part B is held at a fixed position on the casing 22 and curved plates 26a and 26b as revolving members that are rotatably held by the

eccentric parts

25a and 25b of the speed reducer input shaft 25. A plurality of outer pins 27 as outer peripheral engagement members that engage (in the circumferential direction) with the outer peripheral portions of the plates 26a and 26b, and a motion that converts the rotational motion of the curved plates 26a and 26b into the rotational motion of the reducer output shaft 28. A conversion mechanism and

counterweights

29 and 29 arranged adjacent to the outer sides in the axial direction of the

eccentric portions

25a and 25b are provided.

The reduction gear output shaft 28 has a flange portion 28a and a shaft portion 28b. In this embodiment, the flange portion 28a and the shaft portion 28b are integrally provided. In the flange portion 28a, holes for fixing the inner pins 31 at equal intervals are formed on a circumference centered on the rotation axis of the reduction gear output shaft 28. The shaft portion 28b is connected to the hub wheel 32 by spline fitting in which the tooth surface 28c formed on the outer periphery thereof is fitted to the tooth surface formed on the inner periphery of the hollow hub wheel 32 constituting the wheel bearing portion C. Thus, the output of the speed reduction unit B is transmitted to the rear wheel 14 (see FIGS. 8 and 9) via the hub wheel 32.

As shown in FIG. 2, the curved plate 26a has a plurality of waveforms composed of trochoidal curves such as epitrochoids 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 30 b is provided at the center of the curved plate 26 a and is fitted to the eccentric portion 25 a of the reduction gear input shaft 25.

The curved plate 26a is rotatably supported by the rolling bearing 41 with respect to the eccentric portion 25a. The rolling bearing 41 is a so-called cylindrical roller bearing having 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. The outer raceway surface 43 formed directly, the some cylindrical roller 44 arrange | positioned between the inner raceway surface 42a and the outer raceway surface 43, and the holder | retainer (not shown) holding the cylindrical roller 44 are provided. 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. Although detailed illustration and description are omitted, the curved plate 26b has the same structure as the curved plate 26a, and the eccentric portion 25b is formed by a rolling bearing having the same structure as the rolling bearing 41 that supports the curved plate 26a. On the other hand, it is supported rotatably.

As shown in FIG. 2, 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, the curved waveform formed on the outer periphery of the curved plates 26a and 26b and the outer pin 27 are engaged in the circumferential direction to cause the curved plates 26a and 26b to rotate. As shown in FIG. 1, each outer pin 27 has a pair of rolling bearings (needle roller bearings) 61, 61 and a pair of needle roller bearings 61 arranged at the end portions on the inboard side and the outboard side. , 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 absorbs a large radial load or moment load generated by turning or sudden acceleration / deceleration of the vehicle, and prevents damage to the components of the speed reduction portion B (speed reduction mechanism) such as the curved plates 26a and 26b and the outer pin 27. It is.

The counterweight 29 is substantially fan-shaped and has a through hole that engages with the speed reducer input shaft 25, and in order to cancel out the unbalanced inertia couple caused by the rotation of the curved plates 26a and 26b, the

eccentric portions

25a and 25b. In the positions adjacent to each other in the axial direction, the

eccentric portions

25a and 25b are arranged with a phase difference of 180 °.

As shown in FIGS. 1 and 2, the motion conversion mechanism includes a plurality of inner pins 31 and through holes 30a provided in the curved plates 26a and 26b. The inner pins 31 are arranged at equal intervals on the circumference centered on the rotational axis of the reduction gear output shaft 28, and the end portion on the outboard side is fixed to the flange portion 28 a of the reduction gear output shaft 28. ing. 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. This is transmitted to the reduction gear output shaft 28. A needle roller bearing 31a is provided on the inner periphery of the through hole 30a of the curved plates 26a, 26b in order to reduce the frictional resistance between the inner pin 31 and the curved plates 26a, 26b.

The deceleration part B further has a stabilizer 31b. The stabilizer 31b integrally includes an annular portion 31c and a cylindrical portion 31d extending in the axial direction from the inner diameter surface of the annular portion 31c, and the end portion on the inboard side of each inner pin 31 is connected to the annular portion 31c. It is fixed. Thereby, since the load applied to a part of the inner pins 31 from the curved plates 26a and 26b is supported by all the inner pins 31 via the stabilizer 31b, the stress acting on the inner pins 31 is reduced and the durability is improved. Can be improved.

As shown in FIG. 2, the through hole 30 a provided in the curved plate 26 a is provided at a position corresponding to each of the plurality of inner pins 31, and the inner diameter dimension of the through hole 30 a is the outer diameter dimension of the inner pin 31 (“ It indicates the maximum outer diameter including the needle roller bearing 31a. The same shall apply hereinafter.

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 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 curved plates 26a is attached via a rolling bearing 41, since the eccentric portion 25a (the rolling bearing 41) rotatably supports the curve plate 26a, the axial center _{O 2} the axis of the curved plates 26a 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 are engaged with the recesses 34 in the circumferential direction are arranged in the circumferential direction around the axis O.

In FIG. 3, when the speed reducer input shaft 25 rotates counterclockwise on the paper surface, the eccentric portion 25a revolves around the axis O, so that the concave portion 34 of the curved plate 26a is in the circumferential direction with the outer pin 27. In order. 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 curved plates 26a through hole 30a has a plurality circumferentially disposed about the axis O _2. Each through hole 30a is inserted with an inner pin 31 fixed to the reduction gear output shaft 28 arranged coaxially with the axis O (the reduction gear input shaft 25). 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 become an obstacle to the revolution movement of the curved plate 26a. 28 is rotated. 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 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, 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 °. Fluctuates. 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 rotates clockwise by one pitch, resulting in the state of FIG. 3, and this is repeated.

As shown in FIG. 1, the wheel bearing portion C includes a hub wheel 32 and a wheel bearing 33 that rotatably supports the hub wheel 32 with respect to the casing 22. The hub wheel 32 has a cylindrical hollow portion 32a connected to the shaft portion 28b of the reduction gear output shaft 28, and a flange portion 32b extending outward in the radial direction from an end portion on the outboard side of the hollow portion 32a. . Since the rear wheel 14 (see FIGS. 8 and 9) 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 rolling elements (balls) 33c arranged between the inner member and the outer ring 33b, a retainer 33d that holds the balls 33c in a circumferentially spaced state, and a wheel It is a double row angular contact ball bearing provided with a seal member 33e that seals both axial ends of the bearing 33.

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 FIG. 1, a lubricating oil path 24a and a lubricating oil supply port 24b provided in the motor rotating shaft 24, In the lubricating oil passage 25c and the lubricating

oil supply ports

25d, 25e, 25f provided in the speed reducer input shaft 25, the lubricating oil passage 31e provided in the stabilizer 31b, the lubricating oil passage 31f provided in the inner pin 31, and the casing 22 The provided lubricating oil discharge port 22b, the lubricating oil reservoir 22d, the lubricating oil passage 22e, the lubricating oil passage 45 (45a to 45c), and the rotary pump 51 are mainly configured. 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. Lubricating

oil supply ports

25d and 25e extend radially from the lubricating oil path 25c toward the outer diameter surface of the reducer input shaft 25, and the lubricating oil supply port 25f extends from the lubricating oil path 25c to the outside of the reducer input shaft 25. It extends in the axial direction toward the end face.

The lubricating oil discharge port 22b provided in the casing 22 discharges the lubricating oil in 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 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. Note that the lubricating oil reservoir 22d provided between the lubricating oil discharge port 22b and the circulating oil passage 22e has a function of temporarily storing the lubricating oil.

As shown in FIG. 1, the circulating oil passage 45 provided in the casing 22 is connected to an axial oil passage 45 a extending in the axial direction inside the casing 22 and an end portion on the inboard side of the axial oil passage 45 a. A radial oil passage 45c extending in the radial direction and a radial oil passage 45b extending in the radial direction connected to an end portion on the outboard side of the axial oil passage 45a are configured. 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. The oil is supplied to the lubricating oil passage 24 a and further to the lubricating oil passage 25 c of the reduction gear input shaft 25.

The rotary pump 51 is provided between the lubricating oil passage 22e connected to the downstream side of the lubricating oil reservoir 22d and the circulating oil passage 45, and forcibly circulates the lubricating oil. By disposing the rotary pump 51 in the casing 22, it is possible to prevent the in-wheel motor drive device 21 as a whole from being enlarged.

As shown in FIG. 4, the rotary pump 51 includes an inner rotor 52 that rotates using the rotation of the reduction gear 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 including 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 45b of the circulating 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. 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 45b.

The lubrication mechanism mainly has the above-described configuration. Lubricating oil is supplied to each part of the motor part A and the speed reducing part B, and each part of the motor part A and the speed reducing part B is lubricated and cooled as follows. .

First, in the motor portion A, the lubricating oil is supplied to the rotor 23b and the stator 23a mainly as shown in FIG. 1 through the circulating oil passage 45 of the casing 22 and the lubricating oil passage 24a of the motor rotating shaft 24. A part of the lubricating oil supplied to the motor is discharged from the lubricating oil supply port 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. That is, the lubricating oil discharged from the lubricating oil supply port 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. Furthermore, 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 supply port 24b, and the portion of the casing 22 in which the motor portion A is accommodated is located on the outboard side. It is lubricated by the lubricating oil that has fallen along the inner wall surface.

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. Is discharged from the lubricating

oil supply ports

25d, 25e, and 25f to the speed reduction unit B, and then flows as follows.

Lubricating oil discharged from the lubricating

oil supply ports

25e and 25f is supplied to rolling

bearings

37a and 37b that support the reduction gear input shaft 25 by the action of centrifugal force. Further, the lubricating oil flowing out from the lubricating oil supply port 25e is guided to the lubricating oil passage 31e in the stabilizer 31b, reaches the lubricating oil passage 31f in the inner pin 31, and supports the inner pin 31 from the lubricating oil passage 31f. It is supplied to a rolling bearing (needle roller bearing) 31a. Further, due to the centrifugal force, the contact portion between the curved plates 26a, 26b and the inner pin 31, the contact portion between the curved plates 26a, 26b and the outer pin 27, the rolling bearing 61 that supports the outer pin 27, the output shaft of the speed reducer It moves radially outward while lubricating the rolling bearing 46 and the like that support 28.

On the other hand, the lubricating oil discharged from the lubricating oil supply port 25d is supplied to the rolling bearing 41 (see FIG. 2) that supports the curved plates 26a and 26b. Further, like the lubricating oil discharged from the lubricating

oil supply ports

25e and 25f, the contact between the curved plates 26a and 26b and the inner pin 31 and the curved plates 26a and 26b and the outer pin 27 are caused by centrifugal force. It moves radially outward while lubricating the contact part.

The various parts in the deceleration part B are lubricated by the flow of the lubricating oil as described above. And the lubricating oil which reached | attained the inner wall surface of the casing 22 is discharged | emitted from the lubricating oil discharge port 22b, and is stored by the lubricating oil storage part 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 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.

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 an enlarged view in FIG. 5, the shaft portion 28 b of the reduction gear output shaft 28 is located on the inboard side of the tooth surface 28 c (connecting portion with the wheel bearing portion C) via the wheel bearing portion C. The in-wheel is mainly composed of the motor rotation shaft 24, the reduction gear input shaft 25, the reduction gear mechanism, the reduction gear output shaft 28, and the hub wheel 32 with respect to the external force input to the inside of the in-wheel motor drive device 21. It has the lowest weakest part W in the power transmission system of the motor drive device 21. In the present embodiment, an annular groove 28d is formed on the outer peripheral surface of the shaft portion 28b, and the cross-sectional area in the cross-axis orthogonal section of the portion is made smaller than the cross-sectional area in the cross-axis cross-section of the other portion of the shaft portion 28b. The weakest part W is formed.

According to such a configuration, when a large external force is input to the inside of the apparatus via the wheel bearing portion C (hub wheel 32), the weakest portion W provided on the shaft portion 28b of the reduction gear output shaft 28. Therefore, it is possible to prevent an excessive external force from being transmitted to the inboard side of the weakest portion W as much as possible. As a result, a large external force acts on the speed reduction part B and the motor part A arranged on the inboard side with respect to the weakest part W. As a result, internal parts of the speed reduction part B (components of the speed reduction mechanism) and motor rotation shaft It is possible to prevent the 24 and the like from being damaged or broken as much as possible. Moreover, according to the said structure, damage, a fracture | rupture, etc. of the components of the wheel bearing part C can be prevented as much as possible. Therefore, it is not necessary to increase the thickness of other parts / parts constituting the power transmission system of the in-wheel motor drive device 21, and avoid the increase in size, weight, and cost of the in-wheel motor drive device 21. Can do.

Since the wheel bearing portion C is held in the casing 22, the speed reducer output shaft 28 is the weakest portion W provided on the inboard side of the tooth surface 28c (the connecting portion with the wheel bearing portion C). The hub wheel 32 of the wheel bearing portion C merely idles like a driven wheel even when the wheel ring is broken, and the hub wheel 32 and the rear wheel 14 connected and fixed thereto are removed from the chassis 12 (suspension device 12b). There will be no fatal failure that will cause separation or withdrawal. In the in-wheel motor drive device 21 of the present embodiment, as described above, the drive of the motor rotation shaft 24 is stopped when the speed reducer output shaft 28 is broken. The situation where the speed reducer input shaft 25 connected to 24 and the speed reduction mechanism (internal parts of the speed reduction part B) are damaged is also effectively prevented.

Furthermore, in this embodiment, since the inner rotor 52 of the rotary pump 51 rotates using the rotation of the speed reducer output shaft 28, a control device (not shown) that the speed reducer output shaft 28 is broken at the weakest portion W. Is detected and the driving of the motor part A is immediately stopped, the operation of the rotary pump 51 is also stopped. Thereby, since the motor part A and the reduction gear part B are stopped by the control device, the failure of the rotary pump 51 and the malfunction of the lubrication mechanism are also prevented.

As described above, the weakest portion W can be formed by providing the shaft portion 28b with the annular groove 28d that makes the cross-sectional area in the cross section perpendicular to the axis smaller than other portions of the shaft portion 28b. In addition, it can be formed by making the hardness lower than that of other portions of the shaft portion 28b. As an example, it is conceivable that the hardness of the weakest portion W is HRC 29 to 38 and the hardness of other portions is HRC 58 to 64. Further, the weakest portion W is formed by using in combination a means for reducing the cross-sectional area in the cross section perpendicular to the axis than the other portion of the shaft portion 28b and a means for reducing the hardness of the other portion of the shaft portion 28b. You can also The same applies to other embodiments described later (see FIGS. 6 and 7).

The overall operation 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 waveform in the circumferential direction of the curved shape provided on the outer peripheral portions of the curved plates 26a and 26b, so that the curved plates 26a and 26b are opposite to the rotation of the speed reducer input shaft 25. Rotate and rotate.

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 26a, 26b is not transmitted to the inner pin 31, but only the rotational motion of the curved plates 26a, 26b is transmitted to the wheel bearing portion C via the inner pin 31 and 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 transmitted to the speed reducer output shaft 28, even when the low torque, high speed motor portion A is employed, the drive wheel (rear wheel) ) 14 can transmit the necessary torque.

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. 2, 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 the resistance is reduced, the transmission efficiency of the deceleration unit B is improved.

With the above configuration, it is possible to realize the in-wheel motor drive device 21 that is light and compact, yet has excellent quietness (NVH characteristics) and durability. Therefore, if the in-wheel motor apparatus 21 of this embodiment is mounted in the electric vehicle 11, the unsprung weight can be suppressed. As a result, the electric vehicle 11 excellent in running stability and NVH characteristics can be realized.

FIG. 6 shows an enlarged view of a main part of the in-wheel motor drive device 21 according to the second embodiment of the present invention. The main differences between the in-wheel motor drive device 21 according to this embodiment and the in-wheel motor drive device 21 according to the first embodiment described above are the reduction gear output shaft 28 and the wheel bearing portion C (hub wheel). 32), and in that the seal member S is provided in a region closer to the inboard side than the weakest portion W. In the illustrated example, the base portion of the shaft portion 28b of the reduction gear output shaft 28 and the hub wheel are provided. An annular seal member S is interposed in a compressed state between the 32 hollow portions 32a. In this way, it is possible to effectively prevent the fragments generated by the reduction gear output shaft 28 from breaking at the weakest portion W from entering the inside of the speed reduction portion B (speed reduction mechanism). it can. Thereby, it is possible to effectively prevent the function and performance of the speed reducer B from being adversely affected, and to facilitate the maintenance work of the in-wheel motor drive device 21 required after the speed reducer output shaft 28 is damaged or broken. it can.

FIG. 7 shows an enlarged view of a main part of an in-wheel motor drive device 21 according to the third embodiment of the present invention. The main difference between the in-wheel motor drive device 21 according to this embodiment and the in-wheel motor drive device 21 according to the first embodiment is that, first, the hub wheel of the reduction gear output shaft 28 and the wheel bearing portion C. 32, the point that the seal member S is provided in the region on the inboard side of the weakest portion W, and secondly, the flange portion 28a has the weakest portion W with respect to the shaft portion 28b. A reduction gear output shaft 28 (the shaft portion 28b and the flange portion 28a are separate reduction gear output shafts 28) that are detachably connected is used. Thus, if the shaft portion 28b and the flange portion 28a are configured to be detachable, even if the speed reducer output shaft 28 (shaft portion 28b) is broken at the weakest portion W, the shaft portion 28b is made new. It is sufficient to replace it, and it is not necessary to replace the entire reduction gear output shaft 28. Therefore, there is an advantage that labor and cost required for maintenance can be reduced.

In addition, although an explicit description is omitted above, the fit between the tooth surface 28c provided on the shaft portion 28b of the reduction gear output shaft 28 and the tooth surface provided on the hollow portion 32a of the hub wheel 32 is an interference fit. There may be a clearance fit. In particular, if the tooth surfaces are fitted with a clearance fit, the hub wheel 32 and the reducer output shaft 28 can be easily separated, so that the maintenance work after the reduction gear output shaft 28 (shaft portion 28b) is broken. The property is further improved. Further, if the fitting between the tooth surfaces is a clearance fit, for example, when a moment load is applied to the rear wheel 14, a part of the moment load is absorbed up to the fitting clearance between the reduction gear output shaft 28 and the hub wheel 32. Therefore, there is an advantage that the external force acting on the power transmission system of the in-wheel motor drive device 21 can be reduced.

The in-wheel motor drive device 21 described above is merely an example, and various changes can be made to the in-wheel motor drive device 21 without departing from the gist of the present invention.

For example, in the embodiment described above, an example in which the lubricating oil supply port 25d is provided in the

eccentric portions

25a and 25b, and the lubricating

oil supply ports

25e and 25f are provided in the middle of the reduction gear input shaft 25 in the axial direction and at the shaft end. However, the present invention is not limited to this, and the speed reducer input shaft 25 can be provided at any position.

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 by using the rotation of the reduction gear 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.

Moreover, although the example which provided the curve board 26a, 26b of the deceleration part B by changing 180 degree phase was shown, the number of the curve board can be set arbitrarily. For example, when three curved plates are provided, the 120 ° phase may be changed.

In the above description, the motion conversion mechanism is configured by the inner pin 31 fixed to the speed reducer output shaft 28 and the through holes 30a provided in the curved plates 26a and 26b. Any configuration that can be transmitted to the hub wheel 32 can be adopted. For example, you may comprise a motion conversion mechanism with the inner pin fixed to the curve board, and the hole formed in the reduction gear output shaft.

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 the vehicle is lowered, the rotation of the rear wheel 14 may be converted into a rotation of high rotation and low torque by the reduction unit B and transmitted to the motor unit A, and the motor unit A may 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.

Furthermore, the in-wheel motor drive device according to the present invention includes not only 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, and the front wheel 13. It can also be applied to a four-wheel drive type electric vehicle using the rear wheel 14 as a drive wheel. The “electric vehicle” in this specification is a concept including all vehicles that obtain driving force from electric power, and includes, for example, a hybrid car.

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 24 Motor rotating shaft 25 Reduction gear input shaft 28 Reduction gear output shaft

28a Flange part

28b Shaft part 28c Tooth surface (connection part with a wheel bearing part)
28d annular groove 32 hub wheel 32a hollow part A motor part B reduction part C wheel bearing part S seal member W weakest part

Claims

A motor part, a reduction part, and a wheel bearing part arranged in order from the inboard side to the outboard side of the vehicle are held in a casing, and the reduction part is rotated by the motor part, and a reduction gear input shaft An in-wheel motor drive device comprising: a reduction gear output shaft connected to the wheel bearing portion and transmitting the reduced rotation of the reduction gear input shaft to the wheel bearing portion;
The reduction gear output shaft has a strength against an external force input to the inside of the device via the wheel bearing portion on the inboard side with respect to the connecting portion with the wheel bearing portion. An in-wheel motor drive device having the lowest weakest part.
2. The in-wheel according to claim 1, wherein the reduction gear output shaft integrally includes a shaft portion having the weakest portion and the connecting portion, and a flange portion to which rotation of the reduced speed reducer input shaft is transmitted. Motor drive device.
The reduction gear output shaft includes a shaft portion having the weakest portion and the connecting portion, a flange portion that is detachably connected to the shaft portion, and that transmits the reduced rotation of the speed reducer input shaft. The in-wheel motor drive device of Claim 1 provided with.
The in-wheel motor drive device according to any one of claims 1 to 3, wherein the weakest portion is formed by making a cross-sectional area in an axial orthogonal cross section smaller than other portions of the reduction gear output shaft. .
The in-wheel motor drive device according to any one of claims 1 to 4, wherein the weakest portion is formed by lowering hardness than other portions of the reduction gear output shaft.
The in-hole according to any one of claims 1 to 5, wherein a seal member is provided in a region between the speed reducer output shaft and the wheel bearing portion and closer to the inboard side than the weakest portion. Wheel motor drive device.
The speed reduction portion is rotatably held by an eccentric portion provided on the speed reducer input shaft, and a revolving member that performs a revolving motion around the rotation center as the speed reducer input shaft rotates, and the revolution An outer peripheral engagement member that engages with the outer peripheral portion of the member to cause the revolving member to generate a rotation motion, and the rotation motion of the revolution member is converted into a rotation motion around the rotation axis of the speed reducer input shaft. The in-wheel motor drive device according to any one of claims 1 to 6, further comprising a motion conversion mechanism that transmits to the output shaft of the speed reducer.