WO2019146752A1

WO2019146752A1 - In-wheel motor drive device

Info

Publication number: WO2019146752A1
Application number: PCT/JP2019/002450
Authority: WO
Inventors: 英範柄澤
Original assignee: Ntn株式会社
Priority date: 2018-01-29
Filing date: 2019-01-25
Publication date: 2019-08-01
Also published as: JP2019130930A; JP7037375B2; CN111655526B; CN111655526A

Abstract

A sealing structure of the present invention comprises: a wheel hub bearing part (11) which has an inner race (12), an outer race (13), and a rotating body (14); an output shaft (38), which has an end part inserted into a center hole of the inner race (12) and fitted to the inner race, and a base part (38n) partitioning an annular gap between the inner race (12) and said base part (38n); a sealing member (65) which is positioned in the annular gap between the inner race (12) and the base part (38n), and which seals the annular gap; and backup members (66, 67) which are attached to the outer peripheral surface of the base part (38n) or to the inner peripheral surface (12q) of the inner race (12) facing the base part (38n), and which extend in the circumferential direction. Both ends of the backup members (66, 67) are close to each other, and the backup members (66, 67) restrict the position of the sealing member (65) in the direction of an axis O.

Description

In-wheel motor drive

The present invention relates to an in-wheel motor drive device disposed inside a wheel, and more particularly to a connection point between a hub wheel and an output shaft.

The in-wheel motor mainly includes a motor unit, a speed reduction unit, and a wheel hub bearing unit. The wheel hub bearing rotatably supports the hub wheel. The motor unit drives the hub wheel. The hub wheel is coupled to the wheel. The decelerating unit decelerates the number of revolutions output by the rotation shaft of the motor unit and transmits the reduced number of revolutions to the hub wheel. In addition, it is also possible to omit the speed reducing portion and directly connect the rotating shaft of the motor portion to the hub wheel of the wheel hub bearing portion.

In JP-A-2015-137733 (Patent Document 1), the output shaft of the speed reduction portion and the hub wheel of the wheel hub bearing portion are spline-fitted to each other. As a result, the speed reducing portion and the hub wheel can be moved relative to each other in the axial direction. In the spline fitting in one embodiment of Patent Document 1, grease is enclosed in order to prevent wear of the spline.

FIG. 13 shows an example of the grease sealing structure described in Patent Document 1. As shown in FIG. In this structure, the spline groove 100 is formed on the outer peripheral surface of one end portion of the output shaft of the speed reduction portion (spline shaft portion 102). Further, a spline groove 100 is also formed on the inner peripheral surface of the hub wheel 101. The spline shaft portion 102 is inserted into the other end opening of the hub wheel 101, and the hub wheel 101 and the spline shaft portion 102 are spline fitted.

One end opening of the hub wheel 101 is sealed by a cap 103. As a result, the grease in the spline groove 100 is prevented from flowing out from inside the hub wheel 101 to one end in the axial direction. A flange portion 104 is formed at the root of the spline shaft portion 102. The flange portion 104 faces the other end 105 of the hub wheel 101. A seal member 106 such as an O-ring is interposed between the flange portion 104 and the other end surface 105. Further, a seal member 107 such as an O-ring is disposed at a corner where the spline shaft portion 102 and the flange portion 104 are coupled. The seal member 107 is triangularly fixed to the above-mentioned corner by the other end 105 of the spline shaft portion 102. As a result, the grease in the spline groove 100 is prevented from flowing out from inside the hub wheel 101 to the other end in the axial direction.

FIG. 14 shows another example of the grease sealing structure described in Patent Document 1. As shown in FIG. In this structure, with respect to the output shaft of the reduction gear, one end of the output shaft is a spline shaft 102, and an annular groove 108 is formed on the outer peripheral surface of the output shaft on the root side (the other side in the axial direction) than the spline shaft 102 . A seal member 109 such as an O-ring is disposed in the annular groove 108. The seal member 109 contacts the outer peripheral surface of the spline shaft portion 102 and the inner peripheral surface of the other axial end of the hub wheel 101. As a result, the grease in the spline groove 100 is prevented from flowing out from inside the hub wheel 101 to the other end in the axial direction.

JP, 2015-137733, A

However, the inventor has found that there is a point to be further improved in the seal structure between the hub wheel and the spline shaft as in the prior art. That is, in the conventional example of FIG. 13, the

seal members

106 and 107 intervene in the gap opened in the axial direction. However, since the hub wheel 101 and the spline shaft portion 102 move relative to each other in the axial direction, the

seal members

106 and 107 may be temporarily separated from the hub wheel 101 or the spline shaft portion 102, and the sealing performance may be impaired. Therefore, there is room for improvement in the sealing performance of the sealing

members

106 and 107.

In the conventional example of FIG. 14, since the annular groove 108 for positioning the seal member 109 is provided on the outer peripheral surface of the root portion of the spline shaft portion 102, the cross-sectional area of the root portion of the spline shaft portion 102 is reduced. As a result, there is a concern that stress may concentrate at the root of the spline shaft 102 and the strength may decrease. Alternatively, if the shaft diameter of the spline shaft portion is increased to secure strength in an attempt to avoid this concern, the structure will be increased, and the restriction of arranging the in-wheel motor in the inner air space area of the wheel Become.

An object of the present invention is, in view of the above-mentioned situation, to provide a seal structure in which the sealing performance is improved as compared with the conventional one without providing an annular groove in the shaft portion.

For this purpose, the in-wheel motor drive apparatus according to the present invention comprises a wheel hub bearing having a plurality of inner and outer rings, and rolling elements arranged in a plurality of annular gaps between the inner and outer rings, An output shaft which is engaged with the inner ring and whose root portion divides an annular gap from the inner ring, a motor unit which drives the output shaft, and a seal member which is disposed in the annular gap and seals the annular gap; It has a backup member attached to the outer peripheral surface of the root portion or the inner peripheral surface of the inner ring facing the root portion and extending in the circumferential direction, with both ends in the circumferential direction being close to each other to restrict the axial position of the seal member.

According to the present invention, since the backup member regulates the axial position of the seal member, the seal member can be held at an appropriate position without providing an annular groove for holding the seal member on the output shaft. The seal member of the present invention is disposed in an annular gap defined by the inner peripheral surface of the inner ring corresponding to the hub wheel and the outer peripheral surface of the output shaft. Since the annular gap is a gap opened in the radial direction, the radial width of the gap does not change even if the inner ring and the output shaft relatively move in the axial direction. Therefore, the sealing member can always seal the annular gap to prevent the deterioration of the sealing performance.

The material and shape of the backup member are not particularly limited. Since the backup member extends in the circumferential direction, both ends of the backup member may overlap in the circumferential direction so as to surround the entire circumference or more of the output shaft like a ring, or all of the output shaft is C-shaped. Both ends of the backup member may be circumferentially separated so as to surround less than the circumference. Both circumferential ends of the backup member may be adjacent to or separated from each other. As one aspect of the present invention, circumferential ends of the backup member engage with each other. According to this aspect, since the both ends of the backup member engage with each other, the diameter of the backup member does not increase unless the engagement is released. Therefore, it is possible to prevent the diameter of the backup member from expanding due to the vibration of the output shaft or the centrifugal force, and the backup member can be fixed at an appropriate axial position.

As a preferable aspect of the present invention, the backup members are respectively provided on both sides in the axial direction of the seal member. According to this aspect, the axial position of the seal member can be regulated from both sides in the axial direction. As another aspect, the backup member is provided only on one axial side of the seal member.

As another aspect of the present invention, the output shaft further includes a flange portion coupled to the root portion, and the flange surface of the flange portion is formed with a step or a protrusion to be in contact with the backup member. According to this aspect, the backup member is restricted from moving in the other axial direction by the step or the projection because the backup member abuts against the step or the projection provided on the flange portion. Therefore, it is possible to prevent the backup member from moving in the other axial direction due to vibration or centrifugal force of the output shaft, and to fix the backup member at an appropriate axial position.

As a preferable aspect of the present invention, the backup member is in close contact with the outer peripheral surface of the output shaft with a radial interference, and defines a gap between the backup member and the inner peripheral surface of the inner ring. Alternatively, the backup member closely contacts the inner circumferential surface of the inner ring with a radial interference, and divides a gap between the backup member and the outer circumferential surface of the output shaft. According to this aspect, the inner ring and the output shaft are allowed to incline relative to each other at a slight angle.

Thus, according to the present invention, the sealing performance is improved over the prior art. Therefore, even if the inner ring corresponding to the hub ring moves in the axial direction relative to the output shaft, the seal member seals the annular gap between the inner peripheral surface of the end of the inner ring and the outer peripheral surface of the root of the output shaft. Moreover, it is not necessary to provide an annular groove on the outer peripheral surface of the root portion of the output shaft, the cross-sectional area of the root portion is not reduced, and stress concentration on the root portion of the output shaft can be avoided.

It is an expanded sectional view showing the in-wheel motor drive which becomes a 1st embodiment of the present invention. It is a rear view which shows 1st Embodiment. It is an expanded sectional view showing a wheel hub bearing part of a 1st embodiment. It is an enlarged view which shows the encircled part A in FIG. In FIG. 4, it is sectional drawing which takes out and shows the connection part of the output-shaft root part of 1st Embodiment, and an output-shaft flange part. It is a front view which takes out and shows the backup member of 1st Embodiment. It is a longitudinal cross-sectional view which takes out and shows the backup member of 1st Embodiment. It is an expanded sectional view showing a 2nd embodiment of the present invention. It is a longitudinal cross-sectional view which takes out and shows the backup member of 2nd Embodiment. It is a front view which takes out and shows the backup member of 2nd Embodiment. It is an enlarged view which shows the both-ends part of the backup member of 2nd Embodiment. It is an expanded sectional view showing a reference example. It is sectional drawing which shows the conventional seal structure. It is sectional drawing which shows another conventional seal structure.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings. FIG. 1 is a developed sectional view showing an in-wheel motor drive device according to a first embodiment of the present invention. In FIG. 1, the right side of the drawing represents the inner side in the vehicle width direction (inboard side), and the left side of the drawing represents the outer side in the vehicle width direction (outboard side). FIG. 2 is a rear view showing the first embodiment, and is viewed from the inside in the vehicle width direction (inboard side) to the outside in the vehicle width direction (outboard side) in the axial line O direction. In FIG. 2, the right side of the drawing represents the front of the vehicle, the left of the drawing represents the rear of the vehicle, the upper side of the drawing represents the upper side of the vehicle, and the lower side of the drawing represents the lower part of the vehicle. The cross section represented in FIG. 1 is a development plane in which a plane including the axis M and the axis N shown in FIG. 2 and a plane including the axis N and the axis O are connected in this order.

As shown in FIG. 1, the in-wheel motor drive device 10 decelerates the rotation of the wheel hub bearing 11 provided at the center of the wheel (not shown), the motor 21 for driving the wheels, and the motor. And a decelerating unit 31 for transmitting information to the vehicle. The motor unit 21 and the speed reduction unit 31 are disposed offset from the axis O of the wheel hub bearing unit 11. The axis O extends in the vehicle width direction and coincides with the axle. The wheel hub bearing portion 11 is disposed at one axial direction (outboard side) of the in-wheel motor drive device 10, and the motor portion 21 is the other axial direction of the in-wheel motor drive device 10 (inboard side). The reduction gear portion 31 is disposed on one side in the axial direction of the motor portion 21, and the axial position of the reduction gear portion 31 overlaps the axial position of the wheel hub bearing portion 11.

The in-wheel motor drive device 10 is a motor drive device for a vehicle that drives the wheels of the electric vehicle. The in-wheel motor drive device 10 is connected to a vehicle body (not shown). The in-wheel motor drive device 10 can travel the electric vehicle at a speed of 0 to 180 km / h.

The wheel hub bearing portion 11 is a rotating inner ring and a fixed outer ring, and on the outer diameter side of the inner ring 12 as a rotating wheel (hub wheel) coupled with the load wheel W of the wheel (shown only in outline in FIG. 2) An outer ring 13 as a fixed ring coaxially disposed and a plurality of rolling elements 14 disposed in an annular space between the inner ring 12 and the outer ring 13 are provided.

As shown in FIG. 1, the outer ring 13 penetrates an opening 39 p formed in the front portion 39 f of the main body casing 39. The main body casing 39 refers to a casing including the outer shell of the reduction gear portion 31 and accommodates the rotary elements (reduction gear portion rotation shaft and gear) of the reduction gear portion 31. The front portion 39 f is a casing wall that covers one end of the main casing 39 in the direction of the axis O of the speed reduction portion 31.

A plurality of outer ring protruding portions 13 g are further provided on the outer circumferential surface of the outer ring 13 at different positions in the circumferential direction. A through hole is bored in each of the outer ring protruding portions 13g protruding in the outer diameter direction. Further, a front portion 39f of the main body casing 39 is disposed adjacent to the outer ring protruding portion 13g. A plurality of female screw holes (not shown) are formed in the front portion 39f. The respective female screw holes of the front portion 39f and the respective through holes of the outer ring protrusion 13g extend in parallel with the axis O and coincide with each other. A bolt 15 is passed through one of the through holes and the female screw hole from one side in the direction of the axis O, and in the axial portion of the bolt 15, the head of the outer ring projecting portion 1315 abuts on the outer ring projecting portion 13g. Is securely fixed to the front portion 39f.

The inner ring 12 is a cylindrical body longer than the outer ring 13, and is passed through the center hole of the outer ring 13. A coupling portion 12 f is formed at one end of the inner ring 12 in the direction of the axis O that protrudes from the outer ring 13 to the outside of the in-wheel motor drive device 10. The coupling portion 12 f is a projection provided at intervals in the circumferential direction, and constitutes a coupling portion for coupling coaxially with the road wheel W (FIG. 2). The inner ring 12 is connected to the road wheel W of the wheel at a connecting portion 12f and integrally rotates with the wheel.

A plurality of rows of rolling elements 14 are disposed in an annular space between the inner ring 12 and the outer ring 13. The outer peripheral surface of the central portion in the direction of the axis O of the inner ring 12 constitutes an inner raceway surface of the plurality of rolling elements 14 arranged in the first row. An inner race 12r is fitted on the outer periphery of the other end of the inner ring 12 in the direction of the axis O. The outer peripheral surface of the inner race 12r constitutes an inner raceway surface of the plurality of rolling elements 14 arranged in the second row. The inner circumferential surface of the central portion of the outer ring 13 in the axial line O direction constitutes an outer raceway surface of the rolling elements 14 in the first row. The inner circumferential surface of the other end of the outer ring 13 in the direction of the axis O forms the outer raceway surface of the second row of rolling elements 14. The outer diameter of the other end of the inner ring 12 in the direction of the axis O is smaller than the outer diameter of the central portion of the inner ring 12 by the thickness dimension of the inner race 12r. As a result, the outer diameter of the central portion of the inner ring 12 and the outer diameter of the inner race 12r are made the same. A seal member 16 further intervenes in an annular space between the inner ring 12 and the outer ring 13. The sealing member 16 seals both ends of the annular space to prevent the entry of dust and foreign matter.

FIG. 3 is an enlarged vertical sectional view of the wheel hub bearing 11 shown in FIG. The other end 12t of the inner ring 12 in the direction of the axis O is expanded to be in contact with the end face of the inner race 12r. As a result, the inner race 12r is held at the other end of the inner ring 12 in the direction of the axis O so as not to come out in the other direction of the axis O.

A spline groove 12 s is formed on the inner peripheral surface of the central hole of the inner ring 12. The spline grooves 12 s are formed circumferentially at intervals, and extend in parallel with the axis O. The spline groove 12s is disposed in the central region of the inner ring 12 in the direction of the axis O, and is not provided in both end regions of the inner ring 12 in the direction of the axis O.

The inner diameter of one region of the center hole of the inner ring 12 in the direction of the axis O is made larger than the inner diameter of the central region, and a circular lid member 64 is placed. The lid member 64 is, for example, one in which a sealing rubber is adhered to the entire outer periphery of the metal ring, and seals one end of the center hole of the inner ring 12 in the direction of the axis O.

Of the central hole of the inner ring 12, the inner diameter of the other region in the direction of the axis O is made larger than the inner diameter of the central region of the central hole. Thus, the thickness dimension of the other end of the inner ring 12 in the direction of the axis O is made thinner than the central portion in the direction of the axis O, which contributes to the above-described diameter increasing process of the other end 12t in the direction of the axis O.

The output shaft 38 of the speed reduction portion 31 is inserted into and fitted in the center hole of the inner ring 12 from the other side in the direction of the axis O. Therefore, spline grooves 38 s are formed on the outer peripheral surface of one end of the output shaft 38 in the direction of the axis O. A large number of spline grooves 38s are circumferentially spaced to correspond to the spline grooves 12s described above, and extend in parallel with the axis O. Then, the spline teeth formed between the

spline grooves

38s and 38s engage with the spline grooves 12s, and the spline teeth formed between the

spline grooves

12s and 12s engage with the spline grooves 38s.

In such spline fitting, relative rotation of the inner ring 12 and the output shaft 38 is prohibited, but relative movement in the direction of the axis O is permitted. Alternatively, the fitting of the inner ring 12 and the output shaft 38 described above may be a serration fitting. In the case of serration fitting, not only the relative rotation of the inner ring 12 and the output shaft 38 but also relative movement is prohibited.

A region of the output shaft 38 in the direction of the axis O in which the spline groove 38 s is formed is taken as the tip of the output shaft 38. The root portion 38 n of the output shaft 38 protrudes from the flange portion 37 f of the output shaft 38 in the direction of the axis O. A gap opened in the direction of the axis O is defined between the flange surface 37i of the flange portion 37f and the other end 12t of the inner ring 12 in the direction of the axis O.

The outer diameter of the root portion 38n is smaller than the circle connecting the groove bottoms of the

spline grooves

38s, 38s,. Further, the outer peripheral surface of the root portion 38 n is separated from the inner peripheral surface of the other region of the axis line O direction of the inner ring 12 and divides an annular gap opened in the radial direction between the root portion 38 n and the inner ring 12. The annular gap is continuous with the gap between the flange portion 37 f and the inner ring 12. A seal member 65 and

backup members

66 and 67 are disposed in an annular gap between the root portion 38 n and the inner ring 12.

The seal member 65 is made of rubber and can be elastically deformed. The

backup members

66 and 67 are made of plastic or metal harder than the seal member 65, but some elastic deformation is possible. The annular gap in which the sealing member 65 and the

backup members

66 and 67 are disposed allows the inner ring 12 and the output shaft 38 to be relatively inclined at a slight angle.

The

spline grooves

12s, 38s are filled with grease. The grease prevents wear, rust, and heat generation at the fitting portion of the inner ring 12 and the output shaft 38. The center hole of the inner ring 12 is sealed by the lid member 64 on one side in the direction of the axis O from the spline groove 12s. Further, the annular gap between the inner ring 12 and the output shaft 38 is sealed by the seal member 65 on the other side of the spline groove 12s in the axis O direction. The grease is thereby sealed in the central hole of the inner ring 12.

FIG. 4 is an enlarged view showing the circled portion A in FIG. The outer peripheral surface 38p of the root portion 38n has a constant outer diameter in the direction of the axis O. The inner circumferential surface 12 q of the other region in the axis O direction of the inner ring 12 also has a constant outer diameter, and faces the outer circumferential surface 38 p via an annular gap.

The radius of the joint between the outer peripheral surface 38p and the flange portion 37f gradually increases toward the flange portion 37f and is smoothly connected to the flange surface 37g of the flange portion 37f. For this reason, as shown in FIG. 4, the cross-sectional shape of the corner portion 37r where the outer peripheral surface 38p and the flange surface 37g join is a circular arc. In FIG. 5, the cross-sectional shapes of a series of outer peripheral surface 38p, corner 37r, flange surface 37g, step 37j and flange surface 37i are shown enlarged.

The flange surface 37g on the inner diameter side is recessed to the other side in the direction of the axis O from the flange surface 37i on the outer diameter side. The flange surface 37g and the flange surface 37i are connected by a step 37j. The step 37j is an annular inner peripheral surface directed in the inner diameter direction.

The seal member 65 is, for example, an O-ring, contacts the outer circumferential surface 38p and the inner circumferential surface 12q over the entire circumference, and seals the other end of the central hole of the inner ring 12 in the direction of the axis O. In the original form, the thickness of the seal member 65 is larger than the annular gap between the outer peripheral surface 38p and the inner peripheral surface 12q.

The backup member 66 is disposed between the spline groove 38s and the seal member 65 with respect to the position in the direction of the axis O, and regulates movement of the seal member 65 in the direction of the axis O in one direction. The backup member 66 is a C-shaped ring, and the original diameter of the backup member 66 is smaller than the outer diameter of the outer peripheral surface 38p. Therefore, the backup member 66 is mounted and fixed with radial interference so as to hold the outer peripheral surface 38p. As shown in FIG. 4, a gap G1 is defined between the backup member 66 and the inner circumferential surface 12q.

The backup member 67 is disposed between the seal member 65 and the flange portion 37f with respect to the position in the direction of the axis O, and restricts the movement of the seal member 65 in the other direction of the axis O. FIG. 6 is a front view of the backup member 67 and shows a state as viewed from one direction of the axis O. As shown in FIG. FIG. 7 is a longitudinal cross-sectional view of the backup member 67, and shows a state in which the cross section taken along line VII-VII in FIG. 6 is viewed in the direction of the arrow. The backup member 67 is also a C-shaped ring extending in the circumferential direction, and both ends of the backup member 67 are close to each other at an interval D. In the original form, the inner diameter of the backup member 67 is smaller than the outer diameter of the outer peripheral surface 38p. Therefore, the backup member 67 is also mounted and fixed with radial interference so as to hold the outer peripheral surface 38p. As shown in FIG. 4, a gap G2 is defined between the backup member 67 and the inner circumferential surface 12q. The thickness of the

backup members

66 and 67 is smaller than the annular gap between the outer peripheral surface 38p and the inner peripheral surface 12q.

As shown in FIG. 7, while the diameter of the backup member 66 is constant, the diameter of the backup member 67 is constant in one axial region 67a, and the other axial region 67b is shaped to correspond to the corner 37r. The diameter increases toward the other axial direction. The other axial region 67b abuts on the step 37j shown in FIG. The other axial direction region 67b abuts on the flange surface 37g. By accommodating the other axial direction region 67b in the annular recess defined by the step 37j, the flange surface 37g and the corner 37r, the backup member 67 is restricted not only from movement in the direction of the axis O, but also enlarged. To be deformed.

The

backup members

66 and 67 are disposed apart in the direction of the axis O, and the seal member 65 is disposed between the

backup members

66 and 67. Thereby, the movement of the seal member 65 in the direction of the axis O is restricted, and the seal member 65 is held in the annular gap between the outer peripheral surface 38p and the inner peripheral surface 12q. Moreover, even if the outer peripheral surface 38p slides in the direction of the axis O with respect to the inner peripheral surface 12q or moves in the direction perpendicular to the axis O, the seal member 65 is provided on both the outer peripheral surface 38p and the inner peripheral surface 12q. There is no loss in sealing performance due to contact.

As shown in FIG. 1, the motor unit 21 includes a motor rotation shaft 22, a rotor 23, a stator 24, and a motor casing 29, and is sequentially arranged from the axis M of the motor unit 21 to the outer diameter side in this order. The motor unit 21 is an inner rotor, a radial gap motor of an outer stator type, but may be another type. For example, although not shown, the motor unit 21 may be an axial gap motor. The motor casing 29 surrounds the outer periphery of the stator 24. One end of motor casing 29 in the direction of the axis M is coupled to rear surface portion 39 b of main casing 39. The other end of the motor casing 29 in the direction of the axis M is sealed by a plate-like motor casing cover 29v. The back surface portion 39 b is a casing wall portion that covers the other end of the main body casing 39 in the direction of the axis M (the direction of the axis O) of the speed reduction portion 31.

The main casing 39 and the motor casing 29 constitute a casing that forms an outer shell of the in-wheel motor drive device 10. In the following description, the main body casing 39 and a part of the motor casing 29 are also simply referred to as a casing.

The stator 24 includes a cylindrical stator core 25 and a coil 26 wound around the stator core 25. The stator core 25 is formed by laminating ring-shaped steel plates in the axis M direction.

Both end portions of the motor rotation shaft 22 are rotatably supported by the back surface portion 39 b of the main body casing 39 and the motor casing cover 29 v of the motor portion 21 via the rolling

bearings

27, 28.

An axis M, which is the rotational center of the motor rotation shaft 22 and the rotor 23, extends parallel to the axis O of the wheel hub bearing portion 11. That is, the motor unit 21 is offset from the axis O of the wheel hub bearing unit 11. For example, as shown in FIG. 2, the axis M of the motor unit is offset from the axis O in the longitudinal direction of the vehicle, and specifically, is disposed forward of the axis O in the vehicle.

The speed reduction unit 31 includes an input shaft 32 coaxially coupled to the motor rotation shaft 22 of the motor unit 21, an input gear 33 coaxially provided on the outer peripheral surface of the input shaft 32, a plurality of

intermediate gears

34 and 36, and these intermediate An intermediate shaft 35 connected to the center of the

gears

34 and 36, an output shaft 38 connected to the inner ring 12 of the wheel hub bearing 11, an output gear 37 coaxially provided on the outer peripheral surface of the output shaft 38 It has the main body casing 39 which accommodates a gearwheel and a reduction part rotational shaft. Since the main body casing 39 forms the outer shell of the speed reduction portion 31, it is also referred to as a speed reduction portion casing.

The input gear 33 is a helical gear with external teeth. The input shaft 32 has a hollow structure, and one end of the motor rotation shaft 22 in the axial direction is inserted into the hollow hole 32h, and splines are engaged (including the serration). The input shaft 32 is rotatably supported on the front portion 39f and the rear portion 39b of the main casing 39 via rolling bearings 32a and 32b at both ends of the input gear 33.

An axis N, which is the center of rotation of the intermediate shaft 35 of the reduction gear 31, extends parallel to the axis O. Both ends of the intermediate shaft 35 are rotatably supported by the front portion 39f and the back portion 39b of the main body casing 39 via the rolling bearings 35a and 35b. A first intermediate gear 34 is coaxially provided at the other end of the intermediate shaft 35 in the direction of the axis N. A second intermediate gear 36 is coaxially provided in a central region of the intermediate shaft 35 in the direction of the axis N.

In addition, a recess is formed on the other end surface of the first intermediate gear 34 in the direction of the axis N, and the bearing 35 b is accommodated in the recess. As a result, the axial N direction position of the bearing 35 b and the axial N direction position of the tooth surface of the first intermediate gear 34 overlap, and the length of the intermediate shaft 35 is shortened.

The first intermediate gear 34 and the second intermediate gear 36 are externally toothed helical gears, and the diameter of the first intermediate gear 34 is larger than the diameter of the second intermediate gear 36. The large diameter first intermediate gear 34 is disposed on the other side in the direction of the axis N relative to the second intermediate gear 36 and meshes with the small diameter input gear 33. The small diameter second intermediate gear 36 is disposed on one side in the axial direction N relative to the first intermediate gear 34 and meshes with the large diameter output gear 37.

The axis N of the intermediate shaft 35 is disposed above the axis O and the axis M, as shown in FIG. The axis N of the intermediate shaft 35 is disposed forward of the axis O in the vehicle and rearward of the axis M in the vehicle. The speed reduction unit 31 is a three-axis parallel-shaft gear reduction gear having axes O, N, and M which are arranged at intervals in the vehicle front-rear direction and extend in parallel to each other.

Returning to FIG. 1, the output shaft 38 extends along the axis O. A flange portion 37 f is formed at a central portion in the direction of the axis O of the output shaft 38. An output gear 37 is formed on the outer peripheral surface of the flange portion 37f. The output gear 37 is a helical gear with external teeth. One end of the output shaft 38 in the direction of the axis O is inserted into the center hole of the inner ring 12 and is fitted in a relatively non-rotatable manner. The central portion of the output shaft 38 in the direction of the axis O is rotatably supported by the front portion 39f of the main body casing 39 via the rolling bearing 38a. The other end of the output shaft 38 in the direction of the axis O is rotatably supported by the rear surface portion 39 b of the main casing 39 via the rolling bearing 38 b.

The input shaft 32, the intermediate shaft 35, and the output shaft 38 are supported on both sides by the above-described rolling bearing. These rolling

bearings

32a, 35a, 38a, 32b, 35b, 38b are radial bearings.

In addition, an annular convex portion 37k is provided upright on one end face of the output gear 37 in the direction of the axis O. One end surface of the output gear 37 in the direction of the axis O in the inner diameter side of the annular convex portion 37k is recessed more than the outer diameter side of the annular convex portion 37k. The bottom surface of the recess is a flange surface 37i shown in FIG. The recess defined by the annular convex portion 37 k and the flange surface 37 i accommodates the other end of the inner ring 12 and the outer ring 13 in the direction of the axis O.

The annular convex portion 37k is surrounded by an annular convex portion 39i erected on the inner wall surface of the front portion 39f. The rolling bearing 38a is accommodated between the annular

convex portions

37k and 39i. Thereby, the axial O direction position of the rolling bearing 38a and the axial O direction position of the other axial end of the inner ring 12 and the outer ring 13 in the axial O direction overlap, and the wheel hub bearing portion 11 protrudes from the front portion 39f in the axial O direction. The protrusion length is shortened.

As shown in FIG. 1, the reduction portion 31 meshes with a small diameter drive gear and a large diameter driven gear, that is, a mesh between the input gear 33 and the first intermediate gear 34, and a mesh between the second intermediate gear 36 and the output gear 37; Thus, the rotation of the input shaft 32 is decelerated and transmitted to the output shaft 38. The rotating elements from the input shaft 32 to the output shaft 38 of the speed reduction unit 31 constitute a drive transmission path for transmitting the rotation of the motor unit 21 to the inner ring 12.

The body casing 39 includes a tubular portion in addition to the front portion 39f and the back portion 39b described above. The cylindrical portion covers the internal components of the speed reduction unit 31 so as to surround the axes O, N, and M extending in parallel to one another. The plate-like front portion 39f covers the internal components of the speed reduction portion 31 from one side in the axial direction, and is coupled to one end of the cylindrical portion. The plate-like back surface portion 39b covers the internal components of the speed reduction portion 31 from the other side in the axial direction, and is coupled to the other end of the cylindrical portion. The back surface portion 39 b of the main body casing 39 is also a partition that is coupled to the motor casing 29 and partitions the internal space of the speed reduction unit 31 and the internal space of the motor unit 21. The motor casing 29 is supported by the main body casing 39 and protrudes from the main body casing 39 to the other side in the axial direction.

The main body casing 39 divides the internal space of the reduction gear 31 and accommodates all the rotating elements (reduction gear rotational shaft and gear) of the reduction gear 31 in the internal space. As shown in FIG. 2, the lower part of the main body casing 39 is an oil reservoir 41. The oil reservoir 41 is provided to project downward from the lower portion of the motor unit 21. Lubricating oil is stored in the oil storage portion 41 occupying the lower portion of the internal space of the main body casing 39. The stored lubricating oil is pumped up by an oil pump (not shown) to lubricate the motor unit 21 and the speed reduction unit 31 and return it to the oil storage unit 41. Thus, the lubricating oil circulates in the in-wheel motor drive device 10.

When electric power is supplied to the coil 26 described above from the outside of the in-wheel motor drive device 10, the rotor 23 of the motor unit 21 rotates, and the rotation is output from the motor rotation shaft 22 to the speed reduction unit 31. The speed reduction unit 31 decelerates the rotation input from the motor unit 21 to the input shaft 32, and outputs the rotation from the output shaft 38 to the wheel hub bearing unit 11. The inner ring 12 of the wheel hub bearing unit 11 rotates at the same rotational speed as the output shaft 38, and drives a wheel (road wheel W) (not shown) attached and fixed to the inner ring 12.

By the way, the in-wheel motor drive device 10 of the present embodiment has a wheel hub bearing 11 having an inner ring 12, an outer ring 13, and a plurality of rolling elements 14 disposed in an annular gap between the inner ring 12 and the outer ring 13; An output shaft 38 which is inserted into the central hole 12 and fitted to the inner ring 12 and the root 38n divides an annular gap between the inner ring 12 and the motor portion 21 for driving the output shaft 38, the inner ring 12 and the root A seal member 65 disposed in an annular gap of 38 n and sealing the annular gap, and attached to the outer peripheral surface 38 p of the root portion 38 n and extends in the circumferential direction, both ends close to each other at an interval D The back-up

members

66 and 67 which regulate the axial O direction position are provided. Since the movement of the seal member 65 in the direction of the axis O is restricted by the

backup members

66 and 67, the seal member 65 is always held in the annular gap regardless of the relative movement of the inner ring 12 and the output shaft 38. The annular gap of the portion 38 n is sealed. According to the present embodiment, the sealing performance of the sealing member 65 is not reduced.

Further, according to the present embodiment, the seal member 65 can be fixed to the root portion 38n by the

backup members

66 and 67 without providing the annular groove in the root portion 38n, and the cross-sectional reduction and stress concentration of the root portion 38n It can be avoided.

Further, according to the present embodiment, since the

backup members

66 and 67 are provided on both sides of the sealing member 65 in the direction of the axis O, the position of the sealing member 65 in the direction of the axis O is fixed. Therefore, the seal member 65 can be prevented from coming too close to the

spline grooves

12s and 38s.

Further, the

backup members

66 and 67 of the present embodiment are in close contact with the output shaft 38 with radial interference and define the gaps G1 and G2 between the inner ring 12 and the inner ring 12 by the radial gaps G1 and G2. It becomes possible to move relative to the output shaft 38 so as to be inclined at a slight angle.

In order to deepen the understanding of the present embodiment, reference examples shown in FIG. 12 will be described in comparison.

About a reference example, the same code | symbol is attached | subjected about the structure in common with embodiment mentioned above, description is abbreviate | omitted, and a different structure is demonstrated below. In the reference example, no step is provided on the flange surface of the flange portion 37f. The outer peripheral surface 38p, the corner 37r, and the flange surface 37i are connected in this order.

In the reference example, the backup member 67 is deformed so as to expand in diameter due to the vibration of the inner ring 12 and the output shaft 38 or due to the relative movement of the inner ring 12 and the output shaft 38 or the centrifugal force, as shown in FIG. As described above, the annular gap between the inner circumferential surface 12 q and the outer circumferential surface 38 p is pulled out in the other direction of the axis O.

When the backup member 67 moves in the other direction of the axis O, the seal member 65 also moves in the other direction of the axis O and tries to get out of the annular gap between the inner peripheral surface 12 q and the outer peripheral surface 38 p. As a result, the seal member 65 may be separated from the inner circumferential surface 12 q, and the sealing performance of the seal member 65 is reduced.

As understood from the comparison between the present embodiment shown in FIG. 3 and the reference example shown in FIG. 12, the backup member 67 of the present embodiment abuts against the step 37j to prevent the diameter from expanding and the inner circumferential surface 12q and the outer periphery It does not get out of the annular clearance of the surface 38p.

Next, a second embodiment of the present invention will be described. FIG. 8 is a longitudinal sectional view showing a second embodiment of the present invention. About 2nd Embodiment, the code | symbol same about the structure in common with embodiment mentioned above is attached | subjected, description is abbreviate | omitted, and a different structure is demonstrated below. In the second embodiment, no step is provided on the flange surface of the flange portion 37f. The outer peripheral surface 38p, the corner 37r, and the flange surface 37i are connected in this order.

In place of the backup member 66 described above, a backup member 68 is attached between the seal member 65 and the corner 37r. The backup member 68 abuts on the corner 37r on the other side in the direction of the axis O, and the movement of the backup member 68 in the other direction of the axis O is restricted. The backup member 68 is fixed to the outer peripheral surface 38p with a radial interference.

FIG. 9 is a longitudinal sectional view showing the backup member 68 taken out. FIG. 10 is a front view showing the backup member 68 taken out. The backup member 68 is a circumferentially extending band member and has both ends.

FIG. 11 is an enlarged view showing both ends of the backup member 68. As shown in FIG. Both end portions are narrower than the band width of the circumferential central region 68c, and each have a recess 68d and a claw portion 68e. When the both ends are compared, the recess 68 d at one end points in one axial direction, and the recess 68 d at the other end points in the other axial direction.

The claws 68e are provided at the ends of both ends, and define the recess 68d together with the circumferential center region 68c. The claw 68e at one end is directed in one axial direction and is fitted into the recess 68d at the other end. The claw 68e at the other end is directed to the other side in the axial direction and is fitted into the recess 68d at one end. Thereby, both ends of the backup member 68 engage with each other. At this time, the both end portions are close to each other with an interval D.

According to the second embodiment, since the

claws

68e, 68e formed at both ends of the backup member 68 engage with each other, the diameter of the backup member 68 is difficult to expand. Further, as shown in FIG. 8, since at least a part of the backup member 68 is disposed in the annular gap between the outer peripheral surface 38p and the inner peripheral surface 12q, both ends of the backup member 68 can not relatively move in the radial direction. Therefore, the claw 68e at one end is prevented from coming out of the recess 68d at the other end.

The embodiments of the present invention have been described above with reference to the drawings, but the present invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiment within the same scope as the present invention or within the equivalent scope.

The in-wheel motor drive according to the present invention is advantageously used in electric vehicles and hybrid vehicles.

DESCRIPTION OF SYMBOLS 10 in-wheel motor drive device, 11 wheel hub bearing part, 12 inner ring (hub wheel), 12f joint part, 12q inner peripheral surface, 12r inner race ring, 12s, 38s spline groove, 12t axial direction other end edge, 13 outer ring, 14 rolling element, 15 bolt, 21 motor part, 38a rolling bearing, 31 speed reducing part, 32 input shaft, 37 output gear, 37f flange part, 37g, 37i flange surface, 37j level difference, 37k annular convex part, 37r corner part, 38 Output shaft, 38n root portion, 38p outer peripheral surface, 39 body casing, 39f front portion, 39p opening, 64 lid member, 65 seal member, 66, 67, 68 backup member, 67a axial direction one region, 67b axial direction other region, 68c circumferential center region, 68d recess, 68e Claw portions, D spacing, G1, G2 gap, M, N, O axis.

Claims

A wheel hub bearing portion having an inner ring, an outer ring, and a plurality of rolling elements disposed in an annular gap between the inner ring and the outer ring;
An output shaft which is inserted into a center hole of the inner ring and fitted to the inner ring, and whose root portion divides an annular gap from the inner ring;
A motor unit for driving the output shaft;
A sealing member disposed in the annular gap to seal the annular gap;
A backup member attached to the outer peripheral surface of the root portion or the inner peripheral surface of the inner ring facing the root portion and extending in the circumferential direction, with both circumferential ends being close to each other to restrict the axial position of the seal member; An in-wheel motor drive provided.
The in-wheel motor drive according to claim 1, wherein the both ends of the backup member engage with each other.
The in-wheel motor drive according to claim 1 or 2 with which said backup member is provided in axial direction both sides of said seal member, respectively.
The output shaft has a flange portion coupled to the root portion,
The in-wheel motor drive according to claim 1 with which a level difference or projection which contacts said backup member is formed in a flange side of said flange part.
The in-wheel motor drive according to any one of claims 1 to 4, wherein the backup member is in close contact with the output shaft with a radial interference and defines a gap between the backup member and the inner ring.