WO2015133278A1

WO2015133278A1 - In-wheel motor drive device

Info

Publication number: WO2015133278A1
Application number: PCT/JP2015/054470
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: JP2015166616A

Abstract

An in-wheel motor drive device (21) is configured in such a manner that a speed reduction section (B) has: a speed reducer input shaft (25) rotated and driven by a motor section (A); and a speed reduction mechanism for reducing the speed of rotation of the speed reducer input shaft (25). The speed reduction mechanism has: eccentric sections (25a, 25b) provided to the speed reducer input shaft (25); curve plates (26a, 26b) rotatably held at the outer peripheries of the eccentric sections (25a, 25b) and revolving about the rotation axis of the speed reducer input shaft (25) as the speed reducer input shaft (25) rotates; and outer pins (27) engaging with the outer peripheral sections of the curve plates (26a, 26b) and causing the curve plates (26a, 26b) to rotate. The outer pins (27) are formed from case hardening steel and has a hardened layer (H) obtained by carburizing, quenching, and tempering.

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 device needs to be as light and compact as possible. Therefore, in the in-wheel motor drive device of Patent Document 1, by providing a speed reduction unit between the motor unit that generates the driving force and the wheel bearing unit to which the wheels are connected, the motor unit, and thus the overall size of the device is reduced. It tries to make it. The motor part, the wheel bearing part and the speed reduction part are held in a casing, and the casing is attached to the vehicle body via a suspension device (not shown).

Furthermore, in the in-wheel motor drive device of Patent Document 1, 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 ) and a cycloid reducer that is compact and provides a high reduction ratio.

The speed reducer to which the cycloid speed reducer is applied is mainly a speed reducer input shaft having an eccentric portion, and is rotatably held on the outer periphery of the eccentric portion, with the rotation axis centering on the rotation of the speed reducer input shaft. A curved plate as a revolving member that performs the revolving motion, and a plurality of outer peripheral engaging members (outer pins) that engage with the outer peripheral portion of the curved plate (curved plate during the revolving motion) to cause the curved plate to rotate. And a motion conversion mechanism for converting the rotational motion of the curved plate into the rotational motion of the output shaft of the speed reducer.

JP 2012-148725 A

As described above, the outer pin, which is a component of the speed reduction part, has a function of engaging with the outer peripheral part of the curved plate as the reduction gear input shaft rotates and causing the curved plate to rotate. Not only the strength (bending rigidity) that can withstand the load acting on the plate, but also the wear resistance (surface) so that at least the portion engaged (sliding) with the curved plate will not wear when sliding with the curved plate Hardness). In addition, when driving the vehicle, an instantaneous impact load may be input to the deceleration portion via the wheel bearing portion, so that the outer pin does not break even when an instantaneous impact load is applied. It is also necessary to have high toughness.

On the other hand, in order to popularize the in-wheel motor drive device, it is necessary to promote cost reduction of the in-wheel motor drive device. For this reason, it is desired that the outer pin constituting the speed reducing portion can be manufactured (processed) as simply as possible.

As described above, the outer pin, which is a component of the speed reduction part, must satisfy various required characteristics at the same time. However, in the in-wheel motor drive device disclosed in Patent Document 1, no technical means for satisfying the above various required characteristics at the same time has been studied. Therefore, there is room for improvement in the in-wheel motor drive device of Patent Document 1.

The present invention was devised in view of the above circumstances, and the object of the present invention is to realize an outer pin that can be easily manufactured while being excellent in strength, wear resistance, toughness, etc. An object of the present invention is to provide an in-wheel motor drive device that is low in cost and excellent in durability.

In order to achieve the above object, the present invention is based on the following findings found as a result of examining the material surface of the outer pin, which is a component part of the speed reduction portion.

Materials that can satisfy the strength and wear resistance at a high level include, for example, carburized and tempered low-carbon steels such as case-hardened steel, bearing steels that have been subjected to continuous quenching, and high-carbon steels. The thing which gave induction hardening can be mentioned. However, when quenching is performed, the hardness of the core portion as well as the surface layer portion is increased. Therefore, there is a problem that it is difficult to ensure the toughness required for the outer pin in the case where the bearing steel has been subjected to continuous quenching. In addition to the problems that high carbon steel has a higher material unit price and inferior workability before heat treatment compared to low carbon steel, induction hardening is appropriate for workpieces made of high carbon steel. In order to apply, it is necessary to design and prepare a dedicated coil according to the shape of the workpiece, so that flexibility for changing the shape of the outer pin is lacking.

Therefore, in the present invention, the motor unit, the reduction unit, and the wheel bearing unit are held in the casing, and the reduction unit includes a reduction gear input shaft that is rotationally driven by the motor unit, and a reduction gear input shaft that is reduced by the reduction mechanism. A reduction gear output shaft that transmits rotation to the wheel bearing portion, and the reduction gear mechanism is an eccentric portion provided on the reduction gear input shaft, and is rotatably held on the outer periphery of the eccentric portion. A revolving member that performs a revolving motion around its rotation axis, a plurality of outer pins that engage with the outer peripheral portion of the revolving member to cause the revolving member to rotate, and a revolving motion of the revolving member. An in-wheel motor drive device comprising a motion conversion mechanism for converting to a rotational motion of a reduction gear output shaft, wherein the outer pin is made of case-hardened steel and carburized, quenched and tempered. Equipment Subjected to.

Since case-hardened steel, which is a kind of low-carbon steel, is relatively soft and excellent in workability before heat treatment, a predetermined shape can be obtained easily and with high accuracy. On the other hand, if carburizing quenching and tempering is performed as a heat treatment on the workpiece made of case-hardened steel, a hardened layer can be formed only on the surface layer portion, so that the strength and surface are ensured while ensuring the toughness required for the core portion. Hardness (abrasion resistance) can be effectively increased. In addition, since carburizing, quenching and tempering have flexibility with respect to shape change, the cost required for new workpiece fabrication and design change can be reduced. As described above, according to the above configuration, it is possible to obtain an outer pin that can be manufactured at a low cost but has improved strength and wear resistance and ensures the toughness required for the core. Therefore, cost reduction and durability improvement of the in-wheel motor drive device can be realized at the same time.

The deceleration portion may further include a rolling bearing that rotatably supports the outer pin in the radial direction. In this way, the contact resistance between the outer pin and the revolving member is reduced, so that the life of the outer pin and the revolving member can be extended. In this case, it is necessary to fit the rolling bearing to the outer pin. However, because of the configuration of the present invention, the outer pin has a sufficiently high surface hardness, so the rolling bearing is fitted to the outer pin. As a result, it is possible to prevent as much as possible the situation that the outer pin is worn and deformed.

The outer pin is disposed so as to be engageable with the outer peripheral portion of the revolving member, and is provided on a large diameter portion having a relatively large outer diameter size and on both sides in the axial direction of the large diameter portion, and the outer diameter size is relatively small. What has a pair of small diameter parts can be employ | adopted, and a rolling bearing can be fitted to each of a pair of small diameter parts in this case. In this way, the strength (bending rigidity) required for the portion of the outer pin that engages with the outer peripheral portion of the revolving member is secured while reducing the size and weight of the outer pin, and hence the speed reduction portion. Can do.

The deceleration portion may further include a restraining member that restrains the outer pin in the axial direction and a pivot bearing that supports the outer pin in point contact with the restraining member. In this way, the contact resistance between the outer pin and the revolution member can be further reduced while restricting the axial movement of the outer pin and holding the outer pin at a predetermined position in the axial direction. The pivot bearing can be composed of, for example, a restraining member and a ball that is slidably fitted in a recess provided on the end face of the outer pin, and a convex spherical surface provided on the end face of the restraining member and the outer pin. It can be composed of parts.

As described above, according to the present invention, an outer pin having excellent strength, wear resistance, toughness and the like can be realized while being easily manufactured, so that an in-wheel motor drive excellent in durability (reliability) can be realized. The apparatus can be provided at low cost.

It is a figure which shows the in-wheel motor drive device which concerns on one 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 the in-wheel motor drive device shown in FIG. It is an expanded sectional view of an outer pin. It is a principal part enlarged view of the in-wheel motor drive device which concerns on other embodiment. FIG. 6B is an enlarged cross-sectional view of the outer pin shown in FIG. 6A. It is a principal part enlarged view of the in-wheel motor drive device which concerns on other embodiment. It is a schematic plan view of an electric vehicle. It is the schematic sectional drawing which looked at the electric vehicle of Drawing 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. As shown in FIG. 8, the electric vehicle 11 includes an in-vehicle 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. A wheel motor drive 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 portion of the chassis 12 via a suspension device (suspension) 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 the rotation of the left and right rear wheels 14 can be controlled.

In order to improve the running stability and NVH characteristics of the electric vehicle 11, it is necessary to suppress the unsprung weight. Moreover, in order to expand the cabin space of the electric vehicle 11, it is necessary to reduce the size of the in-wheel motor drive device 21. Therefore, as shown in FIG. 1, an in-wheel motor drive device 21 according to an embodiment of the present invention is employed.

An in-wheel motor drive device 21 according to an 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 transmit to 14 (see FIGS. 8 and 9). 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 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 rotating shaft (motor) mounted with a rotor 23b on the outer periphery. The rotary shaft 24 is configured to be rotatable at a rotational speed of about 15000 min ⁻¹ .

The motor rotating shaft 24 has ends on one side in the axial direction (right side in FIG. 1, hereinafter also referred to as “inboard side”) and the other side (left side in FIG. 1 and hereinafter also referred to as “outboard side”). It is rotatably supported with respect to the casing 22 by rolling

bearings

36, 36 respectively disposed in the section. The rolling bearing 36 includes an outer ring that is fitted and fixed to the inner diameter surface of the casing 22, an inner ring that is fitted and fixed to the outer diameter surface of the motor rotation shaft 24, and a plurality of balls disposed between the outer ring and the inner ring. A deep groove ball bearing comprising a cage that holds a plurality of balls in a circumferentially spaced state.

The speed reduction unit B decelerates the rotation of the speed reducer input shaft 25 rotated by the motor part A, 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 is rotatably supported with respect to the speed reducer output shaft 28 by rolling

bearings

37a and 37b that are spaced apart from each other in two axial directions.

Eccentric portions

25a and 25b whose shaft centers are eccentric with respect to the rotational axis of the speed reducer input shaft 25 are provided at two locations in the axial direction of the speed reducer input shaft 25. These two

eccentric portions

25a and 25b are In order to cancel out the centrifugal force due to the eccentric motion, the phases are different from each other by 180 °.

The speed reducer input shaft 25 is fitted with a spline formed on the outer periphery of the end portion on the inboard side (including serrations, the same applies hereinafter) to a spline formed on the inner periphery of the end portion on the outboard side of the motor rotation shaft 24. In other words, it is connected to the motor rotating shaft 24 by so-called spline fitting. Thus, since the speed reducer input shaft 25 is connected to the motor rotation shaft 24, when the motor unit A is driven, the speed reducer input shaft 25 also rotates at a high speed of about 15000 min ⁻¹ as with the motor rotation shaft 24. . At this time, if the fit between the speed reducer input shaft 25 and the inner rings of the rolling

bearings

37a and 37b is a clearance fit, an abnormal noise / vibration that cannot be ignored when the motor rotating shaft 24 rotates is generated. This adversely affects the NVH characteristics. For this reason, the fit between the reduction gear input shaft 25 and the inner rings of the rolling

bearings

37a and 37b is preferably an interference fit.

As shown in FIG. 1, the reduction gear output shaft 28 includes a shaft portion 28 b and a flange portion 28 a that extends radially outward from an end portion of the shaft portion 28 b on the inboard side. The flange portion 28a is formed with axial through-holes opened at both end faces, and a plurality of through-holes are formed at equal intervals on the circumference centering on the rotation axis of the reduction gear output shaft 28. ing. An end portion on the outboard side of an inner pin 31 described later is fitted into each through hole. The shaft portion 28b is connected by spline fitting to a hollow hub wheel 32 that constitutes the wheel bearing portion C.

The speed reduction mechanism is held at fixed positions on the casing 22 and

curved plates

26a and 26b as revolving members that are rotatably held by the

eccentric portions

25a and 25b of the speed reducer input shaft 25, and the outer periphery of the

curved plates

26a and 26b. The main structure includes a plurality of outer pins 27 engaged with the portion and a motion conversion mechanism for converting the rotational motion of the

curved plates

26a and 26b into the rotational motion of the reducer output shaft 28.

As shown in FIG. 2, the curved plate 26 a has a plurality of corrugations composed of trochoidal curves such as epitrochoids on its outer peripheral portion, and has axial through

holes

30 a and 30 b 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 receives 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 has an inner raceway surface 42a on the outer diameter surface, an inner race 42 fitted to the outer diameter surface of the eccentric portion 25a, and an outer raceway surface formed directly on the inner diameter surface of the through hole 30b of the curved plate 26a. 43, a cylindrical roller bearing including 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. 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 illustration is abbreviate | omitted, the curved plate 26b has the same structure as the curved plate 26a, and is arrange | positioned in the outer periphery of the eccentric part 25b, The structure similar to the rolling bearing 41 which supports the curved plate 26a Is supported rotatably with respect to the eccentric portion 25b.

As shown in FIG. 2, a plurality of outer pins 27 are provided at equal intervals on the circumference around the rotation axis of the speed reducer input shaft 25, and as the speed reducer input shaft 25 rotates. When the

curved plates

26a, 26b revolve, the

curved plates

26a, 26b are engaged with the outer peripheral portions of the

curved plates

26a, 26b (recesses 34 provided on the outer peripheral portion) in the circumferential direction to cause the

curved plates

26a, 26b to rotate.

As shown also in FIG. 5A, the outer pin 27 is disposed on the outer diameter side of the

curved plates

26a and 26b so as to be engageable with the outer peripheral portions of the

curved plates

26a and 26b, and has an outer diameter dimension (thickness) relatively. A solid shaft-like member integrally having a large large-diameter portion 27a and a pair of small-

diameter portions

27b and 27b provided on both sides in the axial direction of the large-diameter portion 27a and having a relatively small outer diameter (wall thickness). is there. The outer pin 27 includes an outer pin housing 60 that holds the rolling

bearings

61 and 61 on the inner periphery by a pair of rolling

bearings

61 and 61 disposed at both ends in the axial direction (the outer diameter side of the

small diameter portions

27b and 27b). Furthermore, it is rotatably supported in the radial direction with respect to the casing 22. Thereby, the contact resistance between the outer pin 27 and the

curved plates

26a and 26b is reduced. Each rolling bearing 61 includes an inner raceway surface formed directly on the outer diameter surface of the small diameter portion 27 b of the outer pin 27, and an outer ring having an outer raceway surface on the inner diameter surface and fitted to the inner periphery of the outer pin housing 60. A needle roller bearing comprising a plurality of needle rollers arranged between the inner raceway surface and the outer raceway surface.

An annular restraining

member

62, 62 is fixed to one end surface and the other end surface of the outer pin housing 60, respectively. Thereby, the outer pin 27 is restrained in the axial direction, and the axial movement of the outer pin 27 is restricted.

Although not shown in detail, the outer pin housing 60 and the restraining

members

62 and 62 are supported in a floating state with respect to the casing 22 by a detent means (not shown) having an elastic support function. This is a component of the motion conversion mechanism that absorbs a large radial load or moment load generated by turning or sudden acceleration / deceleration of the vehicle, and converts the rotational motion of the

curved plates

26a and 26b into the rotational motion of the reducer output shaft 28. This is to prevent damage.

As shown in FIG. 1, the speed reduction part B (speed reduction mechanism) further includes counterweights 29 arranged adjacent to each other on the outer side in the axial direction of the

eccentric parts

25a and 25b. The counterweight 29 has a substantially fan shape, for example, and is fitted and fixed to the outer periphery of the speed reducer input shaft 25. Each counterweight 29 is arranged with a 180 ° phase shift from the axially adjacent eccentric portion 25a (25b) 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 2, the motion conversion mechanism mainly includes a plurality of inner pins 31 and a plurality of through holes 30 a provided in the

curved plates

26 a and 26 b, and the motion conversion mechanism of the present embodiment. Further includes a needle roller bearing 31a disposed on the inner periphery of each through hole 30a (see also FIG. 5A). By providing such a needle roller bearing 31a, the frictional resistance between the inner pin 31 and the inner wall surface of the through hole 30a is reduced. The inner pins 31 are provided at equal intervals on the circumference centered on the rotational axis of the speed reducer output shaft 28, and the end on the outboard side is provided on the flange portion 28 a of the speed reducer output shaft 28. It is fitted and fixed in the hole. The through hole 30a is provided at a position corresponding to each of the plurality of inner pins 31, and the inner diameter dimension of the through hole 30a indicates the outer diameter dimension of the inner pin 31 ("maximum outer diameter including the needle roller bearing 31a"). The same shall apply hereinafter). Since the speed reducer output shaft 28 is arranged coaxially with the speed reducer input shaft 25, the rotational motion of the

curved plates

26a and 26b is converted into rotational motion about the rotational axis of the speed reducer input shaft 25. Is transmitted to the reduction gear output shaft 28.

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, when the motor part A is driven (when the speed reducer input shaft 25 is rotated), the load applied to some of the inner pins 31 from the

curved plates

26a and 26b is supported by all the inner pins 31 via the stabilizer 31b. Therefore, the stress acting on the inner pin 31 is reduced and the durability is improved.

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

The axis O ₂ of the eccentric portion 25 a provided on the speed reducer input shaft 25 is eccentric from the axis (rotational axis) O of the speed reducer input shaft 25 by the amount of eccentricity e. The outer periphery of the eccentric portion 25a is attached the curve plate 26a, the eccentric portion 25a so that rotatably supports the curve plate 26a, the axial center _{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 in the radial direction at equal intervals in the circumferential direction. Around the curved plate 26a, a plurality of outer pins 27 that engage with the recesses 34 are arranged in the circumferential direction with the axis O as the center.

In FIG. 3, when the motor part A is driven and the speed reducer input shaft 25 rotates counterclockwise on the paper surface, the eccentric part 25a performs a revolving motion around the axis O, so that the outer peripheral part of the curved plate 26a The recesses 34 formed in the contact with the outer pins 27 sequentially 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 curved plates 26a through hole 30a has a plurality of circumferentially disposed about the axis O _2, the through holes 30a, are arranged and coaxially axis O (reduction gear input shaft 25) An inner pin 31 fixed to the reduction gear output shaft 28 is inserted. Since the inner diameter of the through hole 30a is larger than the outer diameter of the inner pin 31, the inner pin 31 does not 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 eccentric portion 25a thereof).

The direction of the resultant force Fs changes due to the influence of centrifugal force in addition to geometric conditions such as the shape of the outer peripheral portion of the curved plate 26a and the number of concave portions 34. Specifically, the angle α between the reference line X perpendicular to the straight line Y connecting the rotation axis O ₂ and the axis O and passing through the rotation axis O ₂ and the resultant force Fs is approximately 30 ° to 60 °. 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 integrally includes a cylindrical hollow portion 32a connected to the shaft portion 28b of the reduction gear output shaft 28 and a flange portion 32b extending radially outward from the end portion on the outboard side of the hollow portion 32a. Have. 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 lubrication mechanism supplies lubricating oil to various parts of the motor part A and the speed reducing part B. As shown in FIG. 1, the lubricating

oil paths

24a and 24b provided on the motor rotating shaft 24 and the speed reducer input shaft are provided. Lubricating

oil passages

25c, 25d, 25e provided in 25, a lubricating oil passage 31e provided in the stabilizer 31b, a lubricating oil passage 31f provided in the inner pin 31, a lubricating oil discharge port 22b provided in the casing 22, and a lubricating oil The storage unit 22d, the lubricating oil passage 22e, the lubricating oil passage 45 (45a to 45c), and the rotary pump 51 that is disposed in the casing 22 and pumps the lubricating oil to the circulating oil passage 45 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. The lubricating oil passage 25d extends in the radial direction from the lubricating oil passage 25c toward the outer diameter surface of the speed reducer input shaft 25, and is open to the outer diameter surfaces of the

eccentric portions

25a and 25b in the present embodiment. The lubricating oil passage 25e extends in the axial direction from the end portion on the outboard side of the lubricating oil passage 25c, and opens to the outer end surface of the reduction gear input shaft 25 on the outboard side. In particular, the formation position of the lubricating oil passage 25d extending in the radial direction is not limited to this, and can be provided at any position in the axial direction of the reduction gear input shaft 25.

The lubricating oil discharge port 22b provided in the casing 22 discharges the lubricating oil inside the speed reduction part B (speed reduction mechanism), and is provided in at least one position 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. 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. 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. 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 mainly has the above configuration, and lubricates and cools each part of the motor part A and the reduction part B 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 cylinder is discharged from the opening on the outer diameter side of the lubricating oil passage 24 b under the influence of the centrifugal force generated by the rotation of the motor rotating shaft 24 and the pressure of the rotary pump 51. Done. That is, the lubricating oil discharged from the outer diameter side opening of the lubricating oil passage 24b is supplied to the rotor 23b and then supplied to the stator 23a. Further, the rolling bearing 36 that supports the end portion of the motor rotating shaft 24 on the inboard side mainly oozes out part of the lubricating oil flowing through the circulating oil passage 45 from between the casing 22 and the motor rotating shaft 24. It is lubricated by. Further, the rolling bearing 36 that supports the end portion on the outboard side of the motor rotating shaft 24 is mainly discharged from the lubricating oil passage 24b, and the inner portion on the outboard side of the portion of the casing 22 in which the motor portion A is accommodated. It is lubricated by the lubricating oil that has fallen along the wall.

Next, the lubricating oil that has flowed into the lubricating oil passage 25c of the reduction gear input shaft 25 via the lubricating oil passage 24a of the motor rotation shaft 24 is subjected to centrifugal force and pressure of the rotary pump 51 accompanying the rotation of the reduction gear input shaft 25. The oil is discharged from the openings of the lubricating

oil passages

25d and 25e toward the inside of the reduction unit 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. 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.

The outer pin 27 is made of case-hardened steel such as SCM415, SCM420, and SCr420, and as shown in FIG. 5B, a hardened layer H (cross-hatched in the figure) formed by carburizing and tempering as heat treatment. It is indicated by). In the present embodiment, the hardened layer H is formed on the entire surface layer portion of the outer pin 27. The hardness of the hardened layer H is 62 to 66.5 on the Vickers hardness C scale (HRC), while the hardness of the core (the portion where the hardened layer H is not formed) is about HRC29 to 38.

As described above, the outer pin 27 is rotatably supported by the rolling bearings (needle roller bearings) 61 and 61 (see FIG. 5A) disposed at both ends in the axial direction, and is accompanied by the rotation of the speed reducer input shaft 25. It rotates while engaging and sliding with the outer peripheral portions of the

curved plates

26a and 26b, but a hardened layer H is formed on the surface layer portion of the outer pin 27 by carburizing, quenching and tempering, and the surface hardness of the outer pin 27 is increased. Therefore, wear / damage of the outer diameter surface of the small diameter portion 27b due to the assembly of the rolling bearing 61 and rolling of the needle rollers, and wear of the outer diameter surface of the large diameter portion 27a due to engagement / sliding with the curved plates 26a, 26b.・ Damage can be effectively prevented. On the other hand, since the hardened layer H is not formed on the core portion of the outer pin 27, the outer pin 27 has toughness. Thereby, for example, even when an instantaneous impact load is input to the deceleration portion B via the wheel bearing portion C during driving of the vehicle, the possibility that the outer pin 27 may be damaged or broken by this impact load is effective. Can be reduced.

Also, as the material for forming the outer pin 27, the case-hardened steel pin 27 having a relatively soft and rich workability is selected before the heat treatment (carburizing quenching and tempering). can do. In addition, since the carburizing and tempering selected as the heat treatment method has flexibility in changing the shape, the cost required for newly producing the outer pin 27 and changing the design can be reduced.

As described above, according to the present invention, it is excellent in workability and can be easily manufactured, but has high wear resistance and strength against bending load, and further has toughness enough to withstand an instantaneous impact load. Pin 27 can be realized. Thereby, the in-wheel motor drive device 21 with low cost and excellent durability can be realized.

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 curved waveform provided on the outer periphery of the

curved plates

26a and 26b in the circumferential direction, and the

curved plates

26a and 26b are opposite to the rotation direction of the speed reducer input shaft 25. To rotate around.

The inner pin 31 inserted through the through hole 30a comes into contact with the inner wall surface of the through hole 30a as the

curved plates

26a and 26b rotate. As a result, the revolving motion of the

curved plates

26 a and 26 b is not transmitted to the inner pin 31, and only the rotational motion of the

curved plates

26 a and 26 b is transmitted to the wheel bearing portion C via the reduction gear output shaft 28. At this time, since the rotation of the speed reducer input shaft 25 is decelerated by the speed reducing portion B and then transmitted to the speed reducer output shaft 28, even when the low torque, high speed type motor portion A is employed, the drive wheels ( The required torque can be transmitted to the (rear wheel) 14.

The speed reduction ratio of the speed reduction portion B having the above-described configuration is (Z _A −Z _B ), where Z _{A is} the number of outer pins 27 and Z _B is the number of waveforms (concave portions 34) provided on the outer peripheral portions of the curved plates 26a and 26b. ) / is calculated by _{Z B.} In the embodiment shown in FIG. 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 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, as shown in FIG. 6A, the speed reduction part B can further be provided with a pivot bearing 63 that supports the outer pin 27 in point contact with the restraining member 62. In this way, the contact resistance between the outer pin 27 and the

curved plates

26a and 26b can be further reduced. A pivot bearing 63 shown in FIG. 6A has a restraining member 62 having a smooth surface facing the outer pin 27 and a ball 64 fitted in a recess 27c provided on the end surface of the outer pin 27 so as to be freely rollable. It consists of and. In this case, as the outer pin 27, a solid shaft-shaped material made of case-hardened steel before quenching is formed into a stepped shaft shape having a large-diameter portion 27a and a small-diameter portion 27b and having recesses 27c on both end faces. After the processing, a carburized quenching and tempering process is performed as a heat treatment to form a hardened layer H on the entire surface layer portion (see FIG. 6B). Thereby, it is possible to effectively prevent the inner wall surface of the concave portion 27 c of the outer pin 27 from being worn by the rolling of the ball 64.

In addition, the form of the pivot bearing 63 that supports the outer pin 27 in point contact with the restraining member 62 is not limited to the above. That is, as shown in FIG. 7, the pivot bearing 63 may be composed of a restraining member 62 having a smooth surface facing the outer pin 27 and a convex spherical surface 27 d provided on the end surface of the outer pin 27. Is possible. Although not shown in the drawings, the pivot bearing 63 has, for example, a restraining member 62 whose surface facing the outer pin 27 is formed as a convex spherical surface and an end surface (a surface facing the restraining member 62) formed as a smooth surface. It is also possible to configure with an outer pin 27.

Further, in the embodiment shown in FIG. 7, the outer diameter surface has a constant diameter instead of the stepped shaft-shaped outer pin 27 having the large diameter portion 27a and the

small diameter portions

27b, 27b provided on both axial sides thereof. An outer pin 27 formed on the cylindrical surface is used. Of course, also in the in-wheel motor drive device 21 shown in FIG. 1 and FIG. 6A, it is possible to use the outer pin 27 formed on a cylindrical surface having a constant outer diameter surface. In this case, since the shape is simplified, the manufacturing cost of the outer pin 27 can be further reduced. When the outer pin 27 having the large-diameter portion 27a and the small-

diameter portions

27b and 27b provided on both sides in the axial direction is used, the outer pin 27 and the reduction portion B can be reduced in size and weight while the outer pin 27 is reduced. There is an advantage that the strength (bending rigidity) required for the portion of the pin 27 that engages with the

curved plates

26a, 26b can be secured.

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.

In the above description, the

eccentric portions

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

In the above description, the motion conversion mechanism is configured by the inner pin 31 having one end fixed to the flange portion 28a of the reduction gear output shaft 28 and the through hole 30a provided in the

curved plates

26a and 26b. The rotation of the speed reduction unit B can be any configuration that can be transmitted 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.

Also, the case where power is supplied to the motor unit A to drive the motor unit and the power from the motor unit A is transmitted to the rear wheels 14 is shown. On the contrary, the vehicle decelerates or goes down the hill. In such a case, the power from the rear wheel 14 side can be converted to rotation of high rotation and low torque by the speed reduction unit B and transmitted to the motor unit A, and the motor unit A can generate power. Furthermore, the electric power generated here can be stored in a battery and used as electric power for driving the motor unit A and electric power for operating other electric devices provided in the vehicle.

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

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

The present invention is not limited to the above-described embodiments, and can of course be implemented in various forms without departing from the 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 25a Eccentric part 25b Eccentric part 26a Curved board (revolving member)
26b Curved plate (revolving member)
27 Outer pin 27a Large diameter part 27b Small diameter part 27c Concave surface 27d Convex spherical surface 28 Reduction gear output shaft 31 Inner pin 60 Outer pin housing 61 Rolling bearing 62 Restriction member 63 Pivot bearing 64 Ball A Motor part B Reduction part C Wheel bearing part H Hardened layer

Claims

A motor part, a speed reduction part, and a wheel bearing part are held in a casing, and the speed reduction part rotates the speed reducer input shaft rotated by the motor part and the speed reducer input shaft decelerated by the speed reduction mechanism. A reduction gear output shaft that transmits to the wheel bearing portion,
The speed reduction mechanism is rotatably held on an eccentric portion provided on the speed reducer input shaft and on the outer periphery of the eccentric portion, and performs a revolving motion centering on the rotation shaft center with the rotation of the speed reducer input shaft. A revolving member to be performed, a plurality of outer pins that engage with an outer peripheral portion of the revolving member to cause the revolving member to rotate, and a motion conversion that converts the revolving motion of the revolving member into a rotational motion of the reduction gear output shaft. In-wheel motor drive device comprising a mechanism,
An in-wheel motor drive device, wherein the outer pin is made of case-hardened steel and is carburized, quenched, and tempered.
The in-wheel motor drive device according to claim 1, further comprising a rolling bearing that rotatably supports the outer pin in a radial direction.
The outer pins are disposed so as to be engageable with the outer peripheral portion of the revolving member, and are provided on a large-diameter portion having a relatively large outer diameter size and on both sides in the axial direction of the large-diameter portion. The in-wheel motor drive device according to claim 2, further comprising: a small pair of small diameter portions, wherein the rolling bearing is fitted to each of the pair of small diameter portions.
The speed reduction portion further includes a restraining member that restrains the outer pin in the axial direction, and a pivot bearing that supports the outer pin in point contact with the restraining member. In-wheel motor drive device.
The in-wheel motor drive device according to claim 4, wherein the pivot bearing is constituted by the restraining member and a ball that is fitted to a recess provided on an end surface of the outer pin so as to be able to roll.
The in-wheel motor drive device according to claim 4, wherein the pivot bearing is configured by the restraining member and a convex spherical surface provided on an end surface of the outer pin.