WO2015098489A1 - In-wheel motor drive device - Google Patents

Abstract

A reduction unit (B) that constitutes this in-wheel motor drive device (21) is equipped with a plurality of outer pins (27) (outer-periphery engagement members) that engage with the outer peripheries of curved plates (26a, 26b) to rotate the curved plates (26a, 26b). Each outer pin (27) is rotatably supported by needle roller bearings (61) positioned at both ends of each outer pin in the axial direction. A needle roller (65) that constitutes the needle roller bearing (61) includes a crowning (65c) at the outer diameter end. In the crowning (65c), the displacement amount (N) towards the diameter direction interior at a measuring point (M), which is a positioned 1.0mm towards the axial direction interior from a rolling end-face (65a), is 1-15μm.

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, Japanese Patent Laid-Open No. 2008-44537 (Patent Document 1). As shown in FIG. 12, the in-wheel motor drive device 101 includes a motor unit 103 that generates a driving force, a wheel bearing unit 104 that is connected to a wheel, and a wheel bearing that decelerates rotation of the motor unit 103. The speed reduction part 105 which transmits to the part 104 and the casing 102 which hold | maintained these are provided, and the casing 102 is attached to a vehicle body via the suspension apparatus (suspension) which is not shown in figure.

In the in-wheel motor drive device 101 having the above-described configuration, a low torque and high rotation type motor is employed for the motor unit 103 from the viewpoint of making the device compact. On the other hand, the wheel bearing portion 104 requires a large torque to drive the wheel. For this reason, a cycloid reduction gear that is compact and provides a high reduction ratio is employed for the speed reduction unit 105 of the in-wheel motor drive device 101.

The speed reducer 105 to which the cycloid speed reducer is applied is disposed on the speed reducer input shaft 106 having the eccentric portions 106a and 106b and the eccentric portions 106a and 106b, respectively, and the rotation shaft of the speed reducer input shaft 106 rotates as the speed reducer input shaft 106 rotates. Revolving members (curved plates) 107a and 107b that revolve around the center and a plurality of outer peripheral engaging members that cause the curved plates 107a and 107b to rotate by engaging with the outer peripheral portions of the curved plates 107a and 107b. Outer pin) 109 and a plurality of inner pins 111 that transmit the rotational motion of the curved plates 107a and 107b to the reduction gear output shaft 110 are mainly configured.

The reduction gear input shaft 106 is rotatably supported by the rolling bearings 112a and 112b with respect to the casing 102 and the reduction gear output shaft 110, and the curved plates 107a and 107b are supported with respect to the reduction gear input shaft 106 by the rolling bearings 108a and 108b. And is supported rotatably. The plurality of outer pins 109 are rotatably supported with respect to the casing 102 by rolling bearings 113a and 113b disposed at both ends in the axial direction. A needle roller bearing 114 is incorporated in the inner pin 111 and is in rolling contact with the curved plates 107a and 107b.

JP 2008-44537 A

The in-wheel motor drive device needs to accommodate the entire device inside the wheel, and its weight and size affect the unsprung weight of the automobile and the size of the cabin space. From this point of view, the in-wheel motor drive device needs to be further downsized. On the other hand, in practical use of the in-wheel motor drive device, it is necessary to increase the reliability of the in-wheel motor drive device as much as possible. Therefore, it is necessary to further improve the durability of the cycloid reduction gear (deceleration unit) that exhibits a special operation mode.

Therefore, an object of the present invention is to provide an in-wheel motor drive device that is small and excellent in durability.

The present invention devised to achieve the above object includes a casing for holding a motor part, a reduction part, and a wheel bearing part, and the motor part rotationally drives a reduction gear input shaft having an eccentric part, and the reduction part Is an in-wheel motor drive device that decelerates the rotation of the speed reducer input shaft and transmits it to the speed reducer output shaft connected to the wheel bearing portion. The speed reduction portion includes the speed reducer input shaft and the speed reducer input shaft. A revolving member that is rotatably held by the eccentric portion of the reciprocator and performs a revolving motion around the rotation axis as the speed reducer input shaft rotates, and the revolving member is engaged with the outer peripheral portion of the revolving member. An outer peripheral engagement member that generates a rotation motion, a motion conversion mechanism that converts the rotation motion of the revolution member into a rotation motion around the rotation axis of the speed reducer input shaft, and transmits the rotation motion to the speed reducer output shaft; With a decelerating part lubrication mechanism for supplying lubricating oil The joint member is rotatably supported by needle roller bearings disposed at both ends in the axial direction, and the needle roller is positioned at the outer diameter end at a position of 1.0 mm inward in the axial direction from the roller end face. And a crowning having a radially inward displacement (N) of 1 to 15 μm at a measurement point.

As described above, when the outer peripheral engagement member is rotatably supported by the needle roller bearings disposed at both ends in the axial direction, the outer peripheral engagement member is supported by a general ball bearing. In comparison, the speed reduction part can be reduced in size in the radial direction as a whole.

By the way, although each member constituting the speed reducing portion naturally has the required mechanical strength, it is realistic to obtain a rigidity that does not cause any bending when stress is applied to each member. is not. In particular, when a cycloid speed reducer is used for the speed reducing part, when the outer peripheral part of the revolution member and the outer peripheral engagement member are engaged with each other as the revolution member revolves, a large radial load and moment are applied to the outer peripheral engagement member. Since the load acts simultaneously, it is inevitable that the outer peripheral engagement member that is rotatably supported by the bearings disposed at both ends in the axial direction is slightly bent or inclined. In this case, a local load is applied to the needle roller, and as a result, the outer diameter end portion (edge portion) of the needle roller and / or the contact portion of the outer peripheral engagement member with the needle roller wears quickly. There is a risk of damage. Such problems such as early wear are difficult to solve simply by providing a speed reduction part lubrication mechanism that supplies lubricating oil to various parts of the speed reduction part.

Therefore, in the present invention, the crowning is provided at the outer diameter end (edge) of the needle roller. This makes it difficult for a local load to be applied to the needle rollers when the outer peripheral engagement member is bent or tilted, so that the needle rollers and / or the outer peripheral engagement member are not worn or damaged. Can be prevented. Thereby, durability of a needle roller bearing and by extension, a reduction part can be improved, and thereby durability and reliability of an in-wheel motor drive device can be improved. The reason why the displacement amount N is limited to 1 to 15 μm (1 μm to 15 μm) is that when the displacement amount N is less than 1 μm, the above-mentioned effects cannot be enjoyed effectively, and the displacement amount N is 15 μm. This is because abnormal noise and vibration are generated when the value exceeds the range, and the NVH (Noise Vibration Harshness) characteristics may be adversely affected.

The bearing ring constituting the needle roller bearing is preferably made of bearing steel or carburized steel, subjected to carbonitriding, and the amount of retained austenite in the surface layer portion is preferably 20 to 35%. If it does in this way, since rolling fatigue life can be improved and generation | occurrence | production and the progress of the crack by a retained austenite can be suppressed, durability of an in-wheel motor drive device can be improved.

For the same reason as described above, the needle roller constituting the needle roller bearing is preferably made of bearing steel, subjected to carbonitriding, and the amount of retained austenite in the surface layer portion is preferably 20 to 35%.

The needle roller bearing includes an outer ring having an outer raceway surface on the inner diameter surface, an inner raceway surface formed on the outer diameter surface of the outer peripheral engagement member, and a plurality of needles disposed between the outer raceway surface and the inner raceway surface. It can be configured with a roller. As described above, if the outer peripheral engagement member is supported by the needle roller bearing of the type in which the inner ring is omitted, the speed reduction portion and, in turn, the in-wheel motor drive device can be further reduced in size and weight.

As described above, according to the present invention, it is possible to provide an in-wheel motor drive device that is small and lightweight and excellent in durability.

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 an enlarged view of the deceleration part of FIG. It is a principal part enlarged view of FIG. It is explanatory drawing which shows the load which acts on the curve board of FIG. FIG. 2 is a cross-sectional view taken along line PP in FIG. 1. FIG. 2 is a cross-sectional view taken along line QQ in FIG. 1. FIG. 2 is a cross-sectional view taken along line RR in FIG. 1. It is a cross-sectional view of the rotary pump of FIG. It is a schematic plan view of an electric vehicle. It is the schematic sectional drawing which looked at the electric vehicle of Drawing 10 from back. It is a figure which shows the conventional in-wheel motor drive device.

An in-wheel motor drive device according to an embodiment of the present invention will be described with reference to the drawings.

First, an outline of the electric vehicle 11 equipped with the in-wheel motor drive device will be described based on FIGS. 10 and 11. An electric vehicle 11 shown in FIG. 10 includes a chassis 12, a front wheel 13 as a steering wheel, a rear wheel 14 as a drive wheel, and an in-wheel motor drive device 21 that drives each of the left and right rear wheels 14. It is a rear wheel drive type. As shown in FIG. 11, 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 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 that can move the left and right wheels up and down independently in order to improve the followability to the road surface unevenness and efficiently transmit the driving force of the driving wheel (rear wheel 14) to the road surface. Is desirable.

In the electric vehicle 11, since the in-wheel motor drive device 21 that drives the left and right rear wheels 14 is provided inside the left and right wheel housings 12 a, a motor, a drive shaft, a differential gear mechanism, and the like are provided on the chassis 12. There is no need. For this reason, it is possible to secure a wide cabin space and to control the rotation of the left and right drive wheels.

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 an output from the deceleration unit B as driving wheels. 14 and a wheel bearing portion C that is transmitted to 14, and these are held in the casing 22. The motor part A and the speed reduction part B are mounted in a wheel housing 12a (see FIG. 11) 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 stator 23a via a radial gap, and a motor rotating shaft 24a fixed to the rotor 23b and rotating integrally with the rotor 23b. Is a radial gap motor.

The motor rotating shaft 24a has a hollow structure. The end portion of the motor rotating shaft 24a on one side in the axial direction (right side in FIG. 1, hereinafter also referred to as “inward in the vehicle width direction”) is rotatably supported by the rolling bearing 36a, and the other side in the axial direction (left side in FIG. 1). In the following, the end portion of the vehicle (also referred to as “vehicle width direction outer side”) is rotatably supported by the rolling bearing 36b.

The reduction gear input shaft 25 has its axially substantially central portion and the outer end portion in the vehicle width direction supported rotatably with respect to the reduction gear output shaft 28 by rolling bearings 37a and 37b, respectively. The speed reducer input shaft 25 has eccentric portions 25 a and 25 b in the range of the speed reduction portion B. 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 motor rotating shaft 24a and the speed reducer input shaft 25 are connected by serration fitting in order to transmit the driving force of the motor part A to the speed reducing part B. The serration fitting portion is configured to suppress the influence on the motor rotation shaft 24a even if the speed reducer input shaft 25 is inclined to some extent.

The deceleration portion B is held at a fixed position on the casing 22 and curved plates 26a and 26b as revolving members rotatably held by the eccentric portions 25a and 25b, and can be engaged with the outer peripheral portions of the curved plates 26a and 26b. A plurality of outer peripheral engagement members (outer pins) 27, a motion conversion mechanism for transmitting the rotational motion of the curved plates 26a, 26b to the reducer output shaft 28, and the axially outer sides of the eccentric portions 25a, 25b. Counterweights 29 and 29 are provided. The speed reduction part B is provided with a speed reduction part lubrication mechanism that supplies lubricating oil to various parts of the speed reduction part B, the details of which will be described later.

The reduction gear output shaft 28 has a flange portion 28a and a shaft portion 28b. On the end face of the flange portion 28a, holes for fixing the inner pins 31 at equal intervals are formed on the circumference centered on the rotational axis of the reduction gear output shaft 28. The shaft portion 28b is fitted and connected to the hub wheel 32, and transmits the output of the speed reduction portion B to the rear wheel 14 (see FIG. 10) as a drive wheel.

As shown in FIG. 2, the curved plate 26 a has a plurality of corrugations composed of trochoidal curves such as epitrochoids on the outer periphery thereof, and axial through holes 30 a and 30 b that open at both end faces thereof. Have A plurality of through holes 30a are provided at equal intervals on the circumference centering on the rotation axis of the curved plate 26a, and one inner pin 31 is inserted through each through hole 30a. The through hole 30b is provided at the center of the curved plate 26a and is fitted to the eccentric portion 25a.

The curved plate 26a is rotatably supported by the rolling bearing 41 with respect to the eccentric portion 25a. As shown in FIG. 2 and FIG. 3, the rolling bearing 41 has an inner raceway surface 42a on the outer diameter surface, an inner ring 42 fitted to the outer diameter surface of the eccentric portion 25a, and a through hole 30b of the curved plate 26a. A cylindrical roller bearing comprising an outer raceway surface 43 formed on the inner diameter surface, a plurality of cylindrical rollers 44 disposed between the inner raceway surface 42 a and the outer raceway surface 43, and a cage 45 that holds the cylindrical rollers 44. is there. 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, the inner raceway 42a is formed on the inner ring 42 provided separately from the eccentric portion 25a. However, the inner raceway 42 is formed directly on the outer diameter surface of the eccentric portion 25a. It may be omitted. Although detailed illustration and description are omitted, the curved plate 26b is rotatably supported with respect to the eccentric portion 25b by a rolling bearing having the same structure as the rolling bearing 41 that supports the curved plate 26a.

As shown in FIGS. 2 and 3, the outer pins 27 as outer peripheral engagement members are provided at equal intervals on the 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. Each outer pin 27 is rotatably supported in the radial direction by needle roller bearings 61 and 61 arranged at the ends of one axial side and the other side (inner side and outer side in the vehicle width direction) of the outer pin 27. With this configuration, the contact resistance between the outer pin 27 and the curved plates 26a and 26b can be reduced. In the present embodiment, the outer pin 27 is rotatably supported in the radial direction with respect to the casing 22 (see FIG. 1) via the needle roller bearing 61 and the housing 60 that holds the needle pin bearing 61 on the inner periphery. The housing 60 may be omitted, and the needle roller bearing 61 may be directly fixed to the inner periphery of the casing 22. In any case, the outer pin 27 is rotatably supported with respect to the casing 22.

As shown in FIG. 3, the needle roller bearing 61 has an outer raceway surface 63 on the inner diameter surface, and an outer ring 62 fixed to the inner periphery of the housing 60 and an inner surface formed on the outer diameter surface of the outer pin 27. The needle roller bearing is composed of a raceway surface 64 and a plurality of needle rollers 65 disposed between the raceway surfaces 63, 64. The needle roller 65 is arranged in a so-called full roller state in which a cage is omitted. It is installed. In this way, by adopting the needle roller bearing 61 as a bearing for supporting the outer pin 27, compared with the case where a general ball bearing is employed, the reduction portion B as a whole is reduced in size in the radial direction and has a large load capacity. Can be secured. In particular, the needle roller bearing 61 of the present embodiment is a type that does not have an inner ring or a cage, so that the speed reduction part B can be further reduced in size and weight. If there is no particular problem in terms of load capacity, it is also possible to use a needle roller bearing 61 provided with a cage that holds the needle rollers 65 at appropriate intervals.

The needle roller bearing 61 used in this embodiment has a more characteristic configuration. Specifically, first, as shown in FIG. 4, the needle roller 65 constituting the needle roller bearing 61 has a crowning 65c (crowning length) at an axial end portion (edge portion) of the outer diameter surface 65b. CL, crowning radius CR). The crowning 65c is a radially inward displacement amount (a displacement amount radially inward with respect to the outer diameter surface 65b) N at a measurement point M at a position displaced 1.0 mm inward in the axial direction from the roller end surface 65a. Is 1 to 15 μm.

Further, in terms of the material and heat treatment of the constituent members of the needle roller bearing 61, the bearing ring (the outer ring 62 and the outer pin 27) is made of bearing steel or carburized steel, and the needle roller 65 is made of bearing steel. Further, the outer ring 62, the outer pin 27, and the needle roller 65 were subjected to carbonitriding treatment, and nitrogen was diffused in these surface layers to stably hold 20 to 35% of retained austenite. Here, as bearing steel, SUJ3 and SUJ5 classified into the high carbon chromium bearing steel prescribed | regulated to JISB 4805 can be used, for example. Moreover, as carburized steel, SCM415, SCM420, SCr420 etc. can be used, for example. In this embodiment, the outer ring 62, the outer pin 27, and the needle roller 65 are all made of SUJ3, and nitrogen is diffused in these surface layers by carbonitriding to stably hold 20 to 35% of retained austenite. It was.

As shown in FIG. 3, the counterweight 29 is substantially fan-shaped and has a through hole that fits with the speed reducer input shaft 25 to counteract the unbalanced inertia couple caused by the rotation of the curved plates 26a and 26b. The eccentric portions 25a and 25b are disposed at positions adjacent to the eccentric portions 25a and 25b in the axial direction with a phase difference of 180 °.

When the center point in the direction of the rotational axis between the two curved plates 26a and 26b is defined as G, L ₁ × m between the curved plate 26a arranged on the right side of the central point G and the counterweight 29 ₁ × ε ₁ = L ₂ × m ₂ × ε ₂ is established (in this relational expression, L ₁ : distance between the center point G and the center of the curved plate 26a, m ₁ : curved plate 26a, rolling) Sum of the masses of the bearing 41 and the eccentric portion 25a, ε ₁ : the amount of eccentricity of the center of gravity of the curved plate 26a from the rotation axis, L ₂ : the distance between the center point G and the counter weight 29, m ₂ : the mass of the counter weight 29 , Ε ₂ : the amount of eccentricity of the center of gravity of the counterweight 29 from the rotation axis). The above-mentioned relationship of L ₁ × m ₁ × ε ₁ = L ₂ × m ₂ × ε ₂ allows an error that inevitably occurs. The same relationship as described above is established between the curved plate 26b arranged on the left side of the center point G in FIG.

The motion conversion mechanism includes a plurality of inner pins 31 held by the reduction gear output shaft 28 and through holes 30a provided in the curved plates 26a and 26b. The inner pins 31 are provided at equal intervals on a circumference centered on the rotational axis of the speed reducer output shaft 28, and an end portion on the outer side in the vehicle width direction is fixed to the speed reducer output shaft 28. 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. This is transmitted to the reduction gear output shaft 28. Further, in order to reduce the frictional resistance between the inner pin 31 and the curved plates 26a and 26b, a needle roller bearing 31a is provided at a position where the inner surface of the through hole 30a of the curved plates 26a and 26b comes into contact.

A stabilizer 31b is provided at the end of the inner pin 31 in the axial direction. The stabilizer 31b includes an annular ring portion 31c and a cylindrical portion 31d extending in the axial direction from the inner diameter surface of the annular portion 31c. The ends of the inner pins 31 on the inner side in the vehicle width direction are fixed to the annular portion 31c. 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 is provided at a position corresponding to each of the plurality of inner pins 31, and the inner diameter of the through hole 30 a is the outer diameter of the inner pin 31 (“including the needle roller bearing 31 a. It is set to be larger than the maximum outer diameter.

As shown in FIG. 1, the wheel bearing portion C includes a hub wheel 32 connected to the speed reducer output shaft 28 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 and a flange portion 32b. The rear wheel 14 (see FIGS. 10 and 11) is connected and fixed to the flange portion 32b by a bolt 32c. A spline is formed on the outer diameter surface of the shaft portion 28 b of the reduction gear output shaft 28, and the spline is fitted into a spline hole formed in the inner diameter surface of the hollow portion 32 a of the hub wheel 32, thereby reducing the speed reducer. The output shaft 28 and the hub wheel 32 are connected so that torque can be transmitted.

The wheel bearing 33 is fitted to an inner bearing member having an inner raceway surface 33 f formed 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 the inner diameter surface of the casing 22. A fixed outer ring 33b, a plurality of rolling elements (balls) 33c disposed between the inner bearing member and the outer ring 33b, a retainer 33d that holds a gap between balls 33c adjacent in the circumferential direction, and a wheel bearing 33 It is a double row angular contact ball bearing provided with the sealing member 33e which seals both axial direction both ends.

Next, the speed reducer lubrication mechanism will be described. The speed reduction part lubrication mechanism supplies lubricating oil to various parts of the speed reduction part B, and as shown in FIGS. 1 and 3, a lubricating oil path 25c and a lubricating oil supply port 25d provided in the speed reducer input shaft 25 are provided. , 25e, 25f, a lubricating oil passage 31e provided in the stabilizer 31b, a lubricating oil passage 31f provided in the inner pin 31, a lubricating oil outlet 22b provided in the casing 22, a lubricating oil reservoir 22d, and a lubricating oil passage 22e. The lubricating oil passage 45 and the rotary pump 51 are the main components. The white arrow shown in FIG. 1 indicates the direction in which the lubricating oil flows.

The lubricating oil passage 25c extends along the axial direction inside the reduction gear input shaft 25. The lubricating oil supply ports 25d and 25e extend from the lubricating oil passage 25c toward the outer diameter surface of the speed reducer input shaft 25, and the lubricating oil supply port 25f extends from the shaft end of the speed reducer input shaft 25 in the direction of the rotational axis. It extends toward the shaft end face.

At least one location of the casing 22 at the position of the speed reduction part B is provided with a lubricating oil discharge port 22b for discharging the lubricating oil inside the speed reduction part B. A circulating oil passage 45 that connects the lubricating oil discharge port 22 b and the lubricating oil passage 25 c is provided inside the casing 22. The lubricating oil discharged from the lubricating oil discharge port 22 b returns to the lubricating oil path 25 c via the circulating oil path 45.

As shown in FIGS. 1 and 6 to 8, 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 an inner side in the vehicle width direction of the axial oil passage 45a. And a radial oil passage 45c extending in the radial direction and connected to an outer end portion in the vehicle width direction of the axial oil passage 45a and 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 supplies the lubricating oil from the axial oil passage 45a to the lubricating oil passage 25c via the radial oil passage 45c.

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, and forcibly circulates the lubricating oil. As shown in FIG. 9, the rotary pump 51 includes an inner rotor 52 that rotates using the rotation of the speed reducer output shaft 28 (see FIG. 1), and an outer rotor 53 that rotates following the rotation of the inner rotor 52. The cycloid pump includes a pump chamber 54, a suction port 55 that communicates with the lubricating oil passage 22e, and a discharge port 56 that communicates with the radial oil passage 45b of the circulation oil passage 45.

The inner rotor 52 has a tooth profile formed of a cycloid curve on the outer diameter surface. Specifically, the shape of the tooth tip portion 52a is an epicycloid curve, and the shape of the tooth gap portion 52b is a hypocycloid curve. The inner rotor 52 is fitted to the outer diameter surface of the cylindrical portion 31d (see FIGS. 1 and 3) of the stabilizer 31b and rotates integrally with the inner pin 31 and the speed reducer output shaft 28.

The outer rotor 53 has a tooth profile formed of a cycloid curve on the inner diameter surface. Specifically, the shape of the tooth tip portion 53a is a hypocycloid curve, and the shape of the tooth gap portion 53b is an epicycloid curve. The outer rotor 53 is rotatably supported by the casing 22.

The inner rotor 52 is rotated about the rotation center _{c 1.} On the other hand, the outer rotor 53 rotates around a rotation center c ₂ different from the rotation center c ₁ of the inner rotor 52. When the number of teeth of the inner rotor 52 is n, the number of teeth of the outer rotor 53 is (n + 1). In this embodiment, n = 5.

A plurality of pump chambers 54 are provided in the space between the inner rotor 52 and the outer rotor 53. When the inner rotor 52 rotates using the rotation of the reduction gear output shaft 28, the outer rotor 53 rotates in a driven manner. At this time, 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 in from the suction port 55 is pumped from the discharge port 56 to the radial oil passage 45b.

If the inner rotor 52 is tilted during the rotation of the rotary pump 51 configured as described above, the volume of the pump chamber 54 changes and the lubricating oil cannot be properly pumped, or the inner rotor 52 and the outer rotor 53 are There is a risk of contact and damage. Therefore, as shown in FIG. 1, the inner rotor 52 is provided with a stepped portion 52 c. The stepped portion 52 c has an outer diameter surface (guide surface) that abuts against the inner diameter surface of the casing 22, and prevents the inner rotor 52 from being inclined by a radial load from the wheel 14.

Between the lubricating oil discharge port 22b and the rotary pump 51, there is provided a lubricating oil reservoir 22d that temporarily stores the lubricating oil. Thereby, at the time of high speed rotation, the lubricating oil that cannot be discharged by the rotary pump 51 can be temporarily stored in the lubricating oil storage section 22d. As a result, an increase in torque loss of the deceleration unit B can be prevented. On the other hand, at the time of low speed rotation, the lubricating oil stored in the lubricating oil reservoir 22d can be returned to the lubricating oil passage 25c even if the amount of lubricating oil reaching the lubricating oil discharge port 22b decreases. As a result, the lubricating oil can be stably supplied to the deceleration unit B.

潤滑 Lubricating oil inside the deceleration part B moves to the outside due to gravity in addition to centrifugal force. Therefore, it is desirable that the in-wheel motor drive device 21 is attached to the electric vehicle 11 (see FIGS. 10 and 11) so that the lubricating oil reservoir 22d is positioned below the in-wheel motor drive device 21.

The flow of the lubricating oil in the deceleration part B having the above configuration will be described. First, the lubricating oil flowing through the lubricating oil passage 25c flows out from the lubricating oil supply ports 25d, 25e, and 25f to the speed reducing unit B due to the centrifugal force and pressure accompanying the rotation of the speed reducer input shaft 25. Thereafter, the lubricating oil flows to the rolling bearings in the deceleration portion B as follows.

Lubricating oil flowing out from the lubricating oil supply ports 25e and 25f is supplied to the rolling bearings 37a and 37b that support the reduction gear input shaft 24b 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 to the outer side in the radial direction while lubricating the rolling bearing 46 and the like that support the 28 (stabilizer 31b).

Meanwhile, the lubricating oil flowing out from the lubricating oil supply port 25d is supplied into the bearing from a supply hole 42c (see FIG. 3) provided in the inner ring 42 of the rolling bearing 41 that supports the curved plates 26a and 26b. Thereby, the outer surface of the cylindrical roller 44, the inner raceway surface 42a, and the outer raceway surface 43 are lubricated. Further, like the lubricating oil flowing out 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 contact between the curved plates 26a and 26b and the outer pin 27 are caused by centrifugal force. Moves radially outward while lubricating the contact part.

各 Each rolling bearing in the deceleration part B is lubricated by the flow of the lubricating oil as described above. The lubricating oil that has reached the inner wall surface of the casing 22 is discharged from the lubricating oil discharge port 22b and stored in the lubricating oil storage portion 22d. The lubricating oil stored in the lubricating oil reservoir 22d is supplied from the suction port 55 to the rotary pump 51 through the lubricating oil passage 22e, and is pumped from the discharge port 56 to the circulating oil passage 45. As a result, the lubricating oil returns to the lubricating oil passage 25c via the radial oil passage 45b, the axial oil passage 45a, and the radial oil passage 45c of the circulation oil passage 45.

The amount of lubricating oil discharged from the lubricating oil discharge port 22b increases in proportion to the rotational speed of the speed reducer input shaft 25. On the other hand, since the inner rotor 52 rotates integrally with the speed reducer output shaft 28, the discharge amount of the rotary pump 51 increases in proportion to the rotational speed of the speed reducer output shaft 28. Then, the amount of lubricating oil supplied from the lubricating oil discharge port 22 b to the speed reduction unit B increases in proportion to the discharged amount of the rotary pump 51. That is, since both the supply amount and the discharge amount of the lubricating oil to the speed reduction unit B change depending on the rotational speed of the in-wheel motor drive device 21, the lubricating oil can be circulated smoothly and constantly.

Part of the lubricating oil flowing through the circulating oil passage 45 lubricates the rolling bearing 36a that supports the inner end in the vehicle width direction of the motor rotation shaft 24a from between the casing 22 and the motor rotation shaft 24a. The rolling bearing 36b that supports the outer end of the motor rotating shaft 24a in the vehicle width direction is lubricated by lubricating oil from between the stepped portion 52c of the rotary pump 51 and the casing 22.

Thus, by supplying the lubricating oil from the speed reducer input shaft 25 to the speed reducing portion B, the shortage of lubricating oil around the speed reducer input shaft 25 can be solved. Further, by forcibly discharging the lubricating oil by the rotary pump 51, it is possible to suppress the stirring resistance and reduce the torque loss of the speed reduction unit B. Furthermore, by arranging 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.

Although the speed reduction part B includes the speed reduction part lubrication mechanism described above, each rolling bearing in the speed reduction part B is exposed to a very severe usage environment when the in-wheel motor drive device 21 (motor part A) is driven. . The details will be described based on FIG. 5 schematically showing the state of the load acting on the curved plates 26a and 26b when the motor part A is driven.

The axis O ₂ of the eccentric portion 25 a provided on the speed reducer input shaft 25 is eccentric from the 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 is curved plates 26a, the eccentric part 25a is so 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 wavy curve, and has corrugated concave portions 33 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 33 are arranged in the circumferential direction with the axis O as the center.

In FIG. 5, when the eccentric part 25a rotates counterclockwise on the paper surface integrally with the speed reducer input shaft 25, the eccentric part 25a performs a revolving motion around the axis O, so that the concave part 33 of the curved plate 26a The outer pins 27 are sequentially brought into contact with 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 circumferentially disposed about the axis O _2. Each through-hole 30a is inserted with an inner pin 31 that is coupled to the reduction gear output shaft 28 that is disposed coaxially with the axis O. 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 centrifugal force in addition to geometrical conditions such as the waveform shape of the curved plate 26a and the number of the concave portions 33. 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 load directions and magnitudes of the plurality of loads Fi and Fj change during one rotation (360 °) of the speed reducer input shaft 25. As a result, the resultant force Fs acting on the speed reducer input shaft 25 is also a load. The direction and size of fluctuate. Then, when the speed reducer input shaft 25 rotates once, the corrugated concave portion 33 of the curved plate 26a is decelerated and rotated clockwise by one pitch, resulting in the state of FIG. 5, and this is repeated.

For this reason, when the motor part A is driven, the outer pin 27 is loaded with a radial load and a moment load whose load direction and magnitude vary, and at that time, the outer pin 27 is arranged at both axial ends. Since the needle roller bearings 61 and 61 are rotatably supported, the outer pin 27 is somewhat bent or inclined. In this case, as the needle roller bearing 61 for supporting the outer pin 27, in particular, in this embodiment using the inner raceway surface 64 provided on the outer diameter surface of the outer pin 27 (in short, the inner ring is omitted) A local load is applied to the needle roller 65, and the outer diameter end portion of the needle roller 65 and / or the inner raceway surface 64 of the outer pin 27 are likely to be quickly worn or damaged. Such a problem is difficult to solve even if the above-described reduction part lubrication mechanism is provided.

Therefore, in the present invention, as described with reference to FIG. 4, the crowning 65 c is provided at the outer diameter end portion of the needle roller 65 constituting the needle roller bearing 61 that supports the outer pin 27. In this way, when the outer pin 27 is bent or tilted, it becomes difficult for a local load to be applied to the needle roller 65, so that the needle roller 65 and / or the outer pin 27 are not worn or damaged. Can be prevented. Thereby, durability of the needle roller bearing 61 and by extension, the deceleration part B can be improved, and thereby durability and reliability of the in-wheel motor drive device 21 can be improved. The reason why the displacement amount N of the crowning 65c is limited to 1 to 15 μm (1 μm or more and 15 μm or less) is that when the displacement amount N is less than 1 μm, the above-mentioned effects cannot be enjoyed effectively. This is because if it exceeds 15 μm, abnormal noise and vibration are generated, which may adversely affect the NVH characteristics.

Further, in terms of the material and heat treatment of the constituent members of the needle roller bearing 61, both the outer ring 62 and the outer pin 27 are made of SUJ3 which is a kind of bearing steel, and the needle roller 65 is a kind of bearing steel. The outer ring 62, the outer pin 27, and the needle roller 65 were carbonitrided, and nitrogen was diffused in the surface layer portion to stably hold 20 to 35% of retained austenite.

Because of the above materials and heat treatment, the retained austenite reduces crack sensitivity, so that the corrected rated life (ISO 281) can be improved, and the needle roller bearing 61 has a long life. In other words, in order to ensure the equivalent life, the outer ring 62 is made thinner and the needle roller bearing 61 is reduced in size in the radial direction and lighter than the case where the outer ring not having the above configuration is adopted. can do. As described above, through the improvement and miniaturization of the needle roller bearing 61, it is possible to realize the in-wheel motor drive device 21 that is rich in durability and that is small and light.

In the present embodiment, as described above, all of the outer ring 62, the outer pin 27, and the needle roller 65 constituting the needle roller bearing 61 are made of SUJ3, and the amount of retained austenite in these surface layers is 20. Although an example in which the carbonitriding process is performed so as to be 35% is shown, other configurations can be adopted. For example, one of the bearing rings (the outer ring 62 and the outer pin 27) and the needle rollers 65 constituting the needle roller bearing 61 is made of bearing steel, and the amount of retained austenite in the surface layer portion is 20 to 35 by carbonitriding. % Can be adopted.

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

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 reduction gear input shaft 25 connected to the motor rotation shaft 24 a rotates, the curved plates 26 a and 26 b revolve around the rotation axis of the reduction gear input shaft 25. At this time, the outer pin 27 engages with a curved waveform provided on the outer periphery of the curved plates 26a and 26b, and rotates the curved plates 26a and 26b in the direction opposite to the rotation of the speed reducer input shaft 25. .

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 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 outer pin 27 and the inner pin 31 and the curved plates 26a and 26b is provided. Since the resistance is reduced, the transmission efficiency of the deceleration unit B is improved.

The in-wheel motor drive device 21 according to the present embodiment is reduced in weight as described above. 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 having excellent running stability and NVH characteristics can be obtained.

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, the embodiment described above shows 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 position and the shaft end of the speed reducer input shaft 25. However, the present invention is not limited to this, and the speed reducer input shaft 25 can be provided at an arbitrary position. However, from the viewpoint of stably supplying lubricating oil to the rolling bearings 41, 37a, and 37b, the lubricating oil supply port 25d is provided to the eccentric portions 25a and 25b, and the lubricating oil supply ports 25e and 25f are provided to the speed reducer input shaft 25. It is desirable to be provided in the middle position and at the shaft end.

In the above description, the rotary pump 51 is driven using the rotation of the speed reducer output shaft 28. However, the rotary pump 51 can be driven using the rotation of the speed reducer input shaft 25. However, since the rotational speed of the speed reducer input shaft 25 is larger than the speed reducer output shaft 28 (11 times in this embodiment), the durability of the rotary pump 51 may be reduced. Further, a sufficient discharge amount can be ensured even when connected to the decelerator output shaft 28 that has been decelerated. From these viewpoints, the rotary pump 51 is preferably driven by utilizing the rotation of the speed reducer output shaft 28.

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 reduction gear output shaft 28 and the through holes 30a provided in the curved plates 26a and 26b. Any configuration capable of transmitting the rotation to the hub wheel 32 can be employed. 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 unit A to the rear wheel 14 as a drive wheel. 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 may be converted into high-rotation and low-torque rotation 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.

Also, a brake can be added to the in-wheel motor drive device 21. For example, in the configuration of FIG. 1, the casing 22 is extended in the axial direction to form a space on the inner side in the vehicle width direction of the rotor 23 b, a rotating member that rotates integrally with the rotor 23 b in this space, and the casing 22 cannot rotate. If a piston that can move in the axial direction and a cylinder that operates the piston are arranged, a parking brake that locks the rotor 23b by the piston and the rotating member when the vehicle is stopped can be provided. The brake may be a disc brake that sandwiches a flange formed on a part of the rotating member and a friction plate installed on the casing 22 side with a cylinder installed on the casing 22 side. A drum brake may be formed in which a drum is partially formed and a brake shoe is fixed to the casing 22 side to lock the rotating member by friction engagement and self-engagement.

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

Furthermore, the in-wheel motor drive device 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. In the present specification, “electric vehicle” is a concept including all vehicles that obtain driving force from electric power, and should be understood as including, 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 25 Reduction gear input shaft 25a, 25b Eccentric part 26a, 26b Curved board (revolving member)
27 Outer pin (outer peripheral engagement member)
28 Reduction gear output shaft 31 Inner pin 51 Rotary pump 60 Outer pin housing 61 Needle roller bearing 62 Outer ring 65 Needle roller 65a Roller end face 65b Outer diameter surface 65c Crowning A Motor part B Reduction part C Wheel bearing part M Measurement point N Displacement

Claims (4)

A casing for holding a motor part, a speed reduction part and a wheel bearing part, wherein the motor part rotationally drives a speed reducer input shaft having an eccentric part, and the speed reduction part decelerates rotation of the speed reducer input shaft to An in-wheel motor drive device that transmits to a reduction gear output shaft connected to a wheel bearing portion,
The speed reducer is rotatably held by the speed reducer input shaft and an eccentric portion of the speed reducer input shaft, and performs a revolving motion around the rotation axis as the speed reducer input shaft rotates. A revolving member, an outer peripheral engaging member that engages with an outer peripheral portion of the revolving member to cause the revolving member to generate a revolving motion, and the revolving motion of the revolving member is centered on a rotation axis of the speed reducer input shaft. A motion conversion mechanism that converts rotational motion and transmits it to the speed reducer output shaft, and a speed reduction portion lubrication mechanism that supplies lubricating oil to the speed reduction portion,
The outer peripheral engagement member is rotatably supported by needle roller bearings disposed at both axial ends thereof,
The needle roller constituting the needle roller bearing has a radially inward displacement of 1 to 15 μm at a measuring point located 1.0 mm inward in the axial direction from the roller end surface at the outer diameter end of the needle roller. An in-wheel motor drive device characterized by having a crowning. The bearing ring constituting the needle roller bearing is made of bearing steel or carburized steel, is subjected to carbonitriding, and the amount of retained austenite in the surface layer portion is 20 to 35%. The in-wheel motor drive device of description. The in-wheel motor drive device according to claim 1 or 2, wherein the needle rollers are made of bearing steel, are subjected to carbonitriding, and a surface portion has a retained austenite amount of 20 to 35%. . The needle roller bearing includes an outer ring having an outer raceway surface on an inner diameter surface, an inner raceway surface formed on the outer diameter surface of the outer peripheral engagement member, and a plurality of rollers disposed between the outer raceway surface and the inner raceway surface. The in-wheel motor drive device according to any one of claims 1 to 3, wherein the in-wheel motor drive device comprises a needle roller.

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