CN113386559A - Wheel drive device - Google Patents

Abstract

The present invention provides a technique capable of reducing the risk of lubricant leakage. A wheel driving device is provided with: a deceleration mechanism that decelerates the rotation transmitted from the drive source; a rotating member to which the rotation decelerated by the deceleration mechanism is transmitted and which rotates together with the wheel; a fixed member rotatably supporting the rotating member; and a 1 st oil seal for sealing a space for accommodating the speed reducing mechanism, wherein when a member disposed on a radially outer side of the rotating member and the fixed member is an outer member and a member disposed on a radially inner side is an inner member, the outer member includes an extending portion extending radially inward beyond an outermost diameter portion of the inner member, and the 1 st oil seal is disposed between an inner peripheral surface of the extending portion and the inner member.

Description

Wheel drive device

The present application claims priority based on japanese patent application No. 2020-043803, filed on 3/13/2020. The entire contents of this japanese application are incorporated by reference into this specification.

Technical Field

The present invention relates to a wheel driving device.

Background

Conventionally, a wheel driving device for driving wheels of a transport carriage or the like is known. Patent document 1 discloses a wheel driving device including: a speed reduction mechanism; a rotating member that rotates together with the wheel and to which rotation is transmitted from the speed reduction mechanism; and a fixed member for rotatably supporting the rotating member.

Patent document 1: japanese laid-open patent publication No. 2018-131068

An oil seal for sealing lubricant is generally disposed between the rotating member and the fixed member. In the technique disclosed in patent document 1, no special measures are taken to reduce the risk of leakage of the lubricant at the location where the oil seal is disposed. From this viewpoint, the present inventors have recognized that the technique disclosed in patent document 1 has room for improvement.

Disclosure of Invention

An object of the present invention is to provide a technique capable of reducing the risk of lubricant leakage.

One aspect of the present invention for solving the above problems is a wheel driving device. The wheel driving device according to this aspect includes: a deceleration mechanism that decelerates the rotation transmitted from the drive source; a rotating member to which the rotation decelerated by the deceleration mechanism is transmitted and which rotates together with a wheel; a fixed member rotatably supporting the rotating member; and a 1 st oil seal that seals a space in which the speed reduction mechanism is accommodated, wherein, in the wheel drive device, when a member disposed on a radially outer side of the rotating member and the fixed member is an outer member and a member disposed on a radially inner side is an inner member, the outer member includes an extending portion that extends radially inward beyond an outermost diameter portion of the inner member, and the 1 st oil seal is disposed on an inner peripheral surface of the extending portion.

According to the present invention, the risk of lubricant leakage can be reduced.

Drawings

Fig. 1 is a front sectional view showing a wheel drive device according to embodiment 1.

Fig. 2 is an enlarged view of fig. 1.

Fig. 3 is an enlarged front sectional view of the wheel drive device according to embodiment 2.

Fig. 4 is a front sectional view showing the wheel drive device according to embodiment 3.

In the figure: 10-wheel drive device, 12-vehicle body, 14-speed reduction mechanism, 16-rotating member, 18-fixed member, 20A-main bearing, 22-wheel, 26-external gear, 28-internal gear, 34-outer shell, 36A-1 st wheel carrier, 36B-2 nd wheel carrier, 40-vehicle body fixed member, 50-external member, 52A, 52B-internal member, 52A-external side surface, 54A, 54B-main bearing, 56A, 56B-bearing arrangement surface, 58A, 58B-outermost diameter portion, 62-external member main body, 64A-cover body, 70A, 70 BB-extension portion, 76-1 st oil seal, 76A-lip portion, 82-lubricant, 84-enclosed space, 92-lip abutment surface, 94-inserted part, 96-insertion hole, 98-2 nd oil seal.

Detailed Description

In the following description of the embodiments, the same components are denoted by the same reference numerals, and redundant description thereof will be omitted. In each drawing, constituent elements are omitted, enlarged, or reduced as appropriate for convenience of description. The orientation of the drawing depends on the orientation of the symbol. Unless otherwise stated, the terms "abutting", "fixing" and "mounting" in this specification include not only a case where both directly satisfy the mentioned conditions but also a case where the mentioned conditions are satisfied via other components.

(embodiment 1)

Refer to fig. 1. The wheel driving device 10 is assembled to a vehicle body 12 such as a conveyance carriage, and drives wheels 20. In addition, strictly speaking, the reference numeral 12 is a motor, but since the motor is fixed to the vehicle body, the vehicle body 12 is shown including the motor in the present embodiment. Hereinafter, the direction along the rotation center line CL1 of the wheel 20 is referred to as the axial direction X of the wheel drive device 10. The circumferential direction and the radial direction of a circle centered on the rotation center line CL1 are referred to as the "circumferential direction" and the "radial direction" of the wheel drive device 10, respectively.

The wheel drive device 10 mainly includes a speed reduction mechanism 14, a rotating member 16, fixed members 18A and 18B, and wheels 20.

The speed reduction mechanism 14 can reduce the speed of the rotation transmitted from the drive source. The drive source is, for example, a motor, a gear motor, an engine, or the like. The speed reduction mechanism 14 of the present embodiment is an eccentric oscillation type speed reduction mechanism. The reduction mechanism 14 mainly has an input shaft 24, an external gear 26, and an internal gear 28.

The input shaft 24 is provided to be rotatable by the rotational power output from the output shaft 30 of the drive source. The input shaft 24 includes an eccentric portion 24a for oscillating the external gear 26. A plurality of eccentric portions 24a are provided at intervals in the axial direction X.

The external gears 26 are provided individually corresponding to the respective eccentric portions 24 a. The external gear 26 is rotatably supported by the corresponding eccentric portion 24a via an eccentric body bearing 32.

The internal gear 28 meshes with the external gear 26. The number of internal teeth of the internal gear 28 is set to a number different from the number of external teeth of the external gear 26.

The rotation decelerated by the deceleration mechanism 14 is transmitted to the rotating member 16. The rotating member 16 of the present embodiment includes a housing 34 disposed on the outer peripheral side of the reduction mechanism 14. The casing 34 is cylindrical as a whole. The inner peripheral portion of the housing 34 is provided with an internal gear 28.

The fixed members 18A and 18B rotatably support the rotating member 16 via main bearings 54A and 54B (described later). The fixing members 18A, 18B include: a 1 st fixing member 18A provided on one side in the axial direction; and a 2 nd fixing member 18B provided on the other side in the axial direction. In the present embodiment, one side in the axial direction is an opposite side to the vehicle body (left side in the figure) on the opposite side to the vehicle body 12 in the axial direction, and the other side in the axial direction is the vehicle body 12 side (right side in the figure).

The fixing members 18A, 18B of the present embodiment include carriers 36A, 36B provided on the axial side portion of the external gear 26. The carriers 36A, 36B are disposed on the inner peripheral side of the casing 34. The carriers 36A, 36B are annular, and the input shaft 24 is disposed inside thereof. The carriers 36A, 36B rotatably support the input shaft 24 via an input shaft bearing 38.

The wheel frames 36A, 36B include: a 1 st carrier 36A provided on one side in the axial direction of the external gear 26; and a 2 nd carrier 36B provided on the other side in the axial direction of the external gear 26. The 1 st carrier 36A is the 1 st fixing member 18A, and the 2 nd carrier 36B is the 2 nd fixing member 18B. In the present embodiment, the wheel carriers 36A, 36B are coupled to a vehicle body fixing member 40 fixed to the vehicle body 12. Since the fixed members 18A, 18B are coupled to the vehicle body fixing member 40, they cannot rotate together with the rotating member 16.

The wheel 20 rotates together with the rotating member 16 to be able to travel on the running surface. The travel surface is, for example, a floor of a building, a track, or the like. The wheel 20 includes a wheel body 42 and a ground contact member 44.

The wheel main body 42 is cylindrical as a whole. The wheel body 42 of the present embodiment is disposed on the outer peripheral side of the rotating member 16. The wheel main body 42 is integrated with the rotary member 16 by a bolt B1 or the like. In the present embodiment, the wheel body 42 and the rotating member 16 are integrated by fastening the rotating member 16 and the wheel body 42 together with the bolt B1 screwed into the rotating member 16. The bolt B1 is not screwed to the 1 st cover 64A described later, but penetrates the 1 st cover 64A.

The ground engaging member 44 contacts the running surface. The ground contact member 44 of the present embodiment is a tire, and is attached to the wheel body 42 by bonding or the like.

The wheel drive device 10 is further provided with a vehicle body fixing member 40. The vehicle body fixing member 40 of the present embodiment functions as a wheel cover that covers the wheel 20 from the axial direction X. The vehicle body fixing member 40 includes: a vehicle body-side member 46 detachably assembled to the vehicle body 12 by bolts or the like; and a vehicle body opposite-side member 48 detachably attached to the vehicle body-side member 46 by a bolt B2 or the like. The vehicle body-side member 46 covers the wheel 20 from the vehicle body side, and the vehicle body-side member 48 covers the wheel 20 from the vehicle body-side. The 2 nd wheel carrier 36B is detachably coupled to the vehicle body-side member 46 by a bolt B3 or the like. The 1 st wheel carrier 36A is detachably connected to the vehicle body side member 48 by snap-fitting or the like. Thereby, both the 1 st carrier 36A and the 2 nd carrier 36B are coupled to the vehicle body fixing member 40. The vehicle body fixing member 40 supports the wheel 20 on both sides in the axial direction, thereby stabilizing the traveling operation of the wheel 20.

Next, the operation of the wheel driving device 10 will be described. When the input shaft 24 rotates based on the rotation of the drive source, the rotation of the input shaft 24 is decelerated by the deceleration mechanism 14 and transmitted to the rotating member 16. When the rotating member 16 rotates, the wheel 20 rotates together with the rotating member 16, and the wheel 20 travels on the traveling surface.

In the present embodiment, the eccentric portion 24a rotates about the rotation center line CL1 together with the input shaft 24, and the rotation causes the external gear 26 to oscillate so that the axial center thereof rotates about the rotation center line CL 1. When the external gear 26 oscillates, the meshing positions of the external gear 26 and the internal gear 28 sequentially shift. As a result, the internal gear 28 and the external gear 26 rotate relative to each other by the amount corresponding to the difference in the number of teeth between the internal gear 28 and the external gear 26 for each rotation of the input shaft 24. At this time, one of the internal gear 28 and the external gear 26 (the internal gear 28 in the present embodiment) rotates, and the rotation component thereof is transmitted to the rotating member 16.

Here, the radially outward-disposed member of the rotating member 16 and the fixed members 18A and 18B is referred to as an outer member 50, and the radially inward-disposed member is referred to as an inner member 52A and 52B. In the present embodiment, the rotating member 16 is the outer member 50, and the fixed members 18A, 18B are the inner members 52A, 52B. It can also be understood that: the outer member 50 supports the outer peripheral side of the 1 st oil seal 76 described later, and the inner member 52 is in contact with the inner peripheral side (lip) of the 1 st oil seal 76. The inner members 52A, 52B of the present embodiment include: a 1 st inner member 52A provided on one side (the opposite side to the vehicle body) in the axial direction; and a 2 nd inner member 52B provided on the other side (vehicle body side) in the axial direction. The 1 st inner side member 52A is constituted by the 1 st fixing member 18A (the 1 st carrier 36A), and the 2 nd inner side member 52B is constituted by the 2 nd fixing member 18B (the 2 nd carrier 36B).

The wheel drive device 10 includes main bearings 54A and 54B such as rolling bearings. Main bearings 54A, 54B include: a 1 st main bearing 54A disposed between the outer member 50 and the 1 st inner member 52A; and a 2 nd main bearing 54B disposed between the outer member 50 and the 2 nd inner member 52B.

Refer to fig. 2. The 1 st inner member 52A includes a 1 st bearing arrangement surface 56A on which (the inner ring of) the 1 st main bearing 54A is arranged. The 1 st inner member 52A includes a 1 st outermost portion 58A having the largest outer diameter in the 1 st inner member 52A. The 1 st outermost diameter portion 58A of the present embodiment is provided axially outward of the 1 st main bearing 54A and radially outward of the 1 st bearing arrangement surface 56A. The 2 nd inner member 52B includes a 2 nd bearing arrangement surface 56B on which (the inner ring of) the 2 nd main bearing 54B is arranged. The 2 nd inner member 52B includes a 2 nd outermost diameter portion 58B having the largest outer diameter in the 2 nd inner member 52B. The 2 nd outermost diameter portion 58B is provided axially outward of the 2 nd main bearing 54B and radially outward of the 2 nd bearing arrangement surface 56B. Each of the inner members 52A, 52B includes a projection 60 whose outer side surface in the axial direction projects outward in the axial direction.

The outer 50 includes an outer body 62 and covers 64A and 64B. The outer member main body 62 of the present embodiment is the housing 34.

The covers 64A and 64B are detachably coupled to the outer member main body 62 by, for example, bolts B4 in a state of being in contact with one side surface portion of the outer member main body 62 in the axial direction. A seal member 66 such as an O-ring is disposed between the outer member main body 62 and the covers 64A and 64B. The outer member main body 62 and the covers 64A and 64B are sealed by a seal member 66.

In the present embodiment, the covers 64A, 64B are provided on both sides of the outer member body 62 in the axial direction. The covers 64A, 64B include: a 1 st cover 64A provided on the outer side in the axial direction of the 1 st inner side member 52A; and a 2 nd cover 64B provided on the outside in the axial direction of the 2 nd inner member 52B. The covers 64A, 64B include annular fitting portions 68 that project inward in the axial direction. The fitting portion 68 is fitted into the inner peripheral portion of the outer member main body 62 and is snap fitted to the outer member main body 62. The fitting portion 68 is disposed at a position radially overlapping the outermost diameter portions 58A, 58B of the carriers 36A, 36B.

The outer member 50 includes extension portions 70A and 70B. The extension portions 70A, 70B include: the 1 st extension 70A corresponding to the 1 st inner side member 52A; and a 2 nd extending portion 70B corresponding to the 2 nd inner side member 52B. The 1 st extension 70A is provided as a part of the 1 st cover 64A on the 1 st cover 64A, and the 2 nd extension 70B is provided as a part of the 2 nd cover 64B on the 2 nd cover 64B. The extending portions 70A, 70B extend radially inward beyond the outermost diameter portions 58A, 58B of the corresponding inner members 52A, 52B. The extending portions 70A, 70B extend radially inward of the bearing arrangement surfaces 56A, 56B of the corresponding inner members 52A, 52B. In the present embodiment, the extending portions 70A and 70B extend to positions overlapping with an inserted member 94 described later when viewed in the axial direction X.

The extension portions 70A, 70B include: a thin-walled portion 72; and a thick portion 74 provided radially inward of the thin portion 72. The dimension in the axial direction of thick portion 74 is set larger than the dimension in the axial direction of thin portion 72. The thick portion 74 is formed to protrude further inward in the axial direction than the thin portion 72.

The wheel drive device 10 includes a 1 st oil seal 76 disposed between the outer member 50 and the inner members 52A, 52B. The 1 st oil seal 76 corresponds to the plurality of inner side members 52A, 52B, respectively. The 1 st oil seal 76 is disposed between the inner peripheral surface of the 1 st extension 70A of the outer member 50 corresponding to the 1 st inner member 52A and the projection 60 of the 1 st inner member 52A. Further, the 1 st oil seal 76 is also disposed between the inner peripheral surface of the 2 nd extending portion 70B of the outer member 50 corresponding to the 2 nd inner member 52B and the projecting portion 60 of the 2 nd inner member 52B. The extension portions 70A, 70B of the outer member 50 include seal arrangement surfaces 78 on which the 1 st oil seals 76 are arranged. The seal arrangement surface 78 is provided on the inner peripheral surface of the thick portion 74.

The 1 st oil seal 76 seals the accommodating space 80 accommodating the speed reducing mechanism 14 to form an enclosing space 84 enclosing a lubricant 82. The enclosed space 84 is sealed by a seal cover body 85 (refer to fig. 1) disposed inside the 1 st inner member 52A (1 st carrier 36A) in addition to the 1 st oil seal 76. The lubricant 82 of the present embodiment is a lubricating oil, but grease or the like may be used. The enclosed space 84 includes: an accommodating space 80 accommodating the reduction mechanism 14; and a gap space 86 provided between the outer member 50 and the inner members 52A, 52B. In the present embodiment, the external gear 26 and the internal gear 28 of the reduction mechanism 14 are accommodated in the accommodation space 80. The gap space 86 includes: an outer peripheral side space 88 provided between the outer member body 62 and the inner members 52A, 52B; and an inner peripheral side space 90 provided radially inward of the outer peripheral side space 88 between the covers 64A and 64B and the inner members 52A and 52B. Main bearings 54A and 54B are disposed in outer circumferential space 88.

Next, the effects of the wheel driving device 10 will be described.

Here, a case where the lubricant 82 is sealed in the sealed space 84 sealed by the 1 st oil seal 76 as in the present embodiment will be considered. At this time, the lubricant 82 is likely to be retained in the outer peripheral side space 88 between the outermost diameter portions 58A, 58B of the inner members 52A, 52B and the outer member 50. This is because, when the outer member 50 becomes the rotating member 16, the lubricant 82 rotates with the rotation of the outer member 50, and a centrifugal force is applied to the lubricant 82. When the inner members 52A, 52B become the rotating member 16, the lubricant 82 adhering to the inner members 52A, 52B is thrown radially outward. Further, dynamic pressure acts on lubricant 82 retained in outer circumferential side space 88 by the movement of the rolling elements of main bearings 54A, 54B, and the like. When the outer member 50 becomes the rotating member 16, the action of the dynamic pressure becomes particularly large due to the centrifugal force applied to the lubricant 82. For this reason, when the 1 st oil seal 76 is disposed in the outer peripheral side space 88, the 1 st oil seal 76 is required to have high sealing performance.

In the present embodiment, the 1 st oil seal 76 is disposed between the inner members 52A, 52B and the extension portions 70A, 70B of the outer member 50 located at a position separated inward from the outer peripheral side space 88. Therefore, the lubricant 82 hardly reaches the location of the 1 st oil seal 76, and the risk of leakage of the lubricant 82 from this location to the outside can be reduced. Further, compared with the case where the 1 st oil seal 76 is disposed in the outer peripheral side space 88, dynamic pressure is less likely to act on the 1 st oil seal 76. Therefore, the 1 st oil seal 76 is not required to have high sealing performance, and the 1 st oil seal 76 of low cost can be used to ensure sealing performance.

Further, as compared with the case where the 1 st oil seal 76 is disposed in the outer peripheral side space 88, the 1 st oil seal 76 can be reduced in outer diameter size. Further, the degree of freedom in designing the 1 st oil seal 76 can be improved, and the part cost of the 1 st oil seal 76 can be reduced.

The housing 34 of the present embodiment is at least a part of the rotating member 16 which becomes the outer member 50. Therefore, a particularly large dynamic pressure acts on the lubricant 82 due to the centrifugal force. In this case, as described above, there is also an advantage that the sealing performance required of the 1 st oil seal 76 can be reduced.

Here, a case where the 1 st oil seal 76 is disposed between the outer member main body 62 and the inner members 52A, 52B is considered. At this time, in order to replace the 1 st oil seal 76, the outer member body 62 and the inner members 52A, 52B need to be detached. Accordingly, it is necessary to perform a large operation on the constituent elements (the external gear 26 and the like) of the reduction mechanism 14 in the outer member main body 62, and a large-scale operation is required.

In contrast, the outer member 50 includes covers 64A and 64B detachably connected to the outer member main body 62, and the covers 64A and 64B are provided with extension portions 70A and 70B in which the 1 st oil seal 76 is disposed. Therefore, by detaching the covers 64A, 64B from the outer member body 62, the 1 st oil seal 76 can also be detached from the outer member body 62 together with the covers 64A, 64B. In this case, in the present embodiment, the covers 64A and 64B are removed from the outer member body 62 in a state where the outer member 50 and the inner members 52A and 52B are removed from the vehicle body fixing member 40. At this time, the covers 64A, 64B can be detached from the outer member body 62 while maintaining the inner members 52A, 52B arranged inside the outer member body 62. In this way, in the process of removing the 1 st oil seal 76 from the outer member body 62, there is no need to detach the outer member body 62 and the inner members 52A, 52B. Therefore, when the 1 st oil seal 76 is replaced, it is not necessary to perform a large operation on the constituent elements of the speed reduction mechanism 14 in the outer member main body 62, and good operability can be obtained.

Further, the method of replacing the 1 st oil seal 76 includes: a method of extracting only the 1 st oil seal 76 using a tool and a method of inserting a tapping screw into the 1 st oil seal 76. With these methods, the peripheral structures (the outer member 50 and the inner members 52A, 52B) may be damaged. The present invention has an advantage that such a situation can be avoided.

Next, other features of the wheel drive device 10 will be described. The 1 st oil seal 76 is mounted to the extension portions 70A, 70B of the outer member 50 by interference fit or the like. The 1 st oil seal 76 includes a lip portion 76a, and the lip portion 76a comes into contact with the lip contact surface 92 of the inner members 52A, 52B as it elastically deforms. The lip 76a of the 1 st oil seal 76 abuts against the inner members 52A, 52B, whereby the enclosed space 84 is sealed. The liquid level of the lubricant 82 in the stationary state in which the wheel drive apparatus 10 stops operating is set to L. The lip 76a is disposed such that at least a portion thereof is located at a position lower than the level L of the lubricant 82. In the present embodiment, the lip abutment surface 92 is provided such that at least a part thereof is located at a position lower than the liquid level L of the lubricant 82. It can also be understood that the outer diameter of the lip abutment surface 92 is set to satisfy this condition. In the present embodiment, the lip contact surfaces 92 of the inner members 52A and 52B satisfy this condition. Only the lip abutment surfaces 92 of the single inner members 52A, 52B may satisfy this condition.

This enables a part of the lip portion 76a of the 1 st oil seal 76 to be reliably wetted with the lubricant 82. Further, the occurrence of insufficient lubrication at the lip portion 76a of the 1 st oil seal 76 can be suppressed.

The lip contact surfaces 92 of the inner members 52A, 52B are finished by plunge grinding. Plunge grinding is a method of grinding a part of a grinding object (here, the lip contact surface 92) by moving a grinding wheel relative to the grinding object (here, the inner members 52A, 52B) in a circumferential direction. This reduces the surface roughness of the lip contact surface 92, and forms an annular fine unevenness on the lip contact surface 92. Further, compared to the longitudinal grinding, the lubricant 82 can be made less likely to leak through between the lip portion 76a of the 1 st oil seal 76 and the lip abutment surface 92 in the axial direction X.

An insertion hole 96 into which the insertion member 94 is inserted is formed in the axially outer surface 52a of the 2 nd inner member 52B. The insertion hole 96 is opened at a position exposed to the gap space 86. The insertion hole 96 is provided at a position overlapping with the 1 st oil seal 76 in the axial direction X. The inserted member 94 is inserted axially inward from an opening portion of the insertion hole 96 in the outer side surface 52 a. The inserted member 94 is, for example, a pin synchronized with the rotation component or revolution component of the external gear 26. Here, "synchronization" means: in the numerical range including 0, the rotation component or revolution component of the external gear 26 and the revolution component of the pin are maintained at the same size. The revolution component is, for example, considered in the case where the external gear 26 is constituted by a planetary gear of a simple planetary mechanism.

Refer to fig. 1. The center axis of the inside members 52A, 52B is referred to as CL 2. Which is provided at a position overlapping with the rotation center line CL1 of the wheel 20. The outer diameter L2 of the lip contact surface 92 of the inner member 52A, 52B is set to be equal to or less than the minimum distance L1 in the radial direction from the center axis CL2 of the inner member 52A, 52B to the insertion hole 96. The minimum distance L1 is the minimum diameter of a circle that is inscribed in the insertion hole 96 and centered on the center axis CL 2. In the present embodiment, the outer diameter L2 of the lip abutment surface 92 is set to be smaller than the minimum distance L1. This can avoid interference with the lip contact surfaces 92 of the inner members 52A and 52B when the inserted member 94 is inserted.

(embodiment 2)

Refer to fig. 3. The wheel drive apparatus 10 of the present embodiment includes the 2 nd oil seal 98 disposed between the outer member 50 and the inner members 52A, 52B at a position radially outward of the 1 st oil seal 76. The 2 nd oil seal 98 is provided separately corresponding to each of the inner members 52A, 52B, and is disposed between the outermost diameter portions 58A, 58B of the corresponding inner members 52A, 52B and the outer member 50. The inner diameter of the 2 nd oil seal 98 of the present embodiment is set larger than the outer diameter of the 1 st oil seal 76. The dimension in the axial direction of the 2 nd oil seal 98 of the present embodiment is set smaller than the dimension in the axial direction of the 1 st oil seal 76.

Thus, the lubricant 82 is less likely to reach the inner peripheral side space 90 from the housing space 80 enclosed in the space 84 by the 2 nd oil seal 98. Further, the lubricant 82 becomes more difficult to reach the location where the 1 st oil seal 76 is disposed, and the risk of leakage of the lubricant 82 can be further reduced.

(embodiment 3)

Refer to fig. 4. The wheel driving device 10 of the present embodiment is different from that of embodiment 1 in the wheel 20. The wheel 20 of the present embodiment is a mecanum wheel. The ground contact member 44 of the wheel 20 is a plurality of drum-shaped rollers rotatably supported by the wheel main body 42. The roller can rotate around a rotation axis line inclined with respect to the rotation center line CL1 of the wheel 20. The vehicle body fixing member 40 of the present embodiment is different from that of embodiment 1 in that only the vehicle body side member 46 is provided.

As such, the kind of the wheel 20 is not particularly limited. The wheels 20 may also be omni wheels, for example. In this case, the ground contact member 44 is formed of a roller having a rotation center in a direction passing through a tangent line of the outer peripheral surface of the wheel main body 42.

Next, another modification of each constituent element will be described.

Although the example in which the wheel drive device 10 is mounted on the transport carriage has been described above, the vehicle body to be mounted is not particularly limited.

In the above, an example has been described in which one side in the axial direction is the vehicle body side and the other side in the axial direction is the vehicle body side. Further, one side in the axial direction may be a vehicle body side and the other side in the axial direction may be an opposite vehicle body side.

Although the description has been given of the example in which the reduction mechanism 14 is an eccentric oscillating type reduction mechanism, the type thereof is not particularly limited. For example, any of a planetary gear mechanism, a parallel axis gear mechanism, an orthogonal axis gear reduction mechanism, a flexible mesh reduction mechanism, and the like may be included. In the present embodiment, a description has been given of a center crank type speed reduction mechanism in which the input shaft 24 (crank shaft) is disposed on the rotation center line CL1, as an eccentric oscillation type speed reduction mechanism. Further, as the eccentric oscillation type reduction mechanism, a distributed reduction mechanism in which a plurality of input shafts 24 (crank shafts) are arranged at positions offset from the rotation center line CL1 may be employed.

The rotating member may be an inner member, and the fixed member may be an outer member. In this case, for example, a case where the casing 34 is a part of the fixed member and the carriers 36A and 36B are a part of the rotating member is considered.

The above description has been given of an example in which the wheel 20 is provided at a position overlapping the speed reduction mechanism 14 in the radial direction. However, the present invention is not limited to this, and the wheel 20 may be provided at a position not overlapping with the reduction mechanism 14 in the radial direction. In this case, for example, it is considered that the wheels 20 are disposed on the opposite side of the vehicle body with respect to the reduction mechanism 14.

The extending portions 70A, 70B of the outer member 50 may be disposed only radially outward of the bearing disposition surfaces 56A, 56B of the inner members 52A, 52B.

The 1 st oil seal 76 may also be disposed such that the entire lip portion 76a thereof is located at a position higher than the level L of the lubricant 82.

The outer diameter L2 of the lip contact surface 92 of the inner member 52A, 52B may be set to the same size as the minimum distance L1. The outer diameter L2 may be set to be larger than the minimum distance L1.

The outer 50 may be provided with only the outer body 62 and without the covers 64A and 64B. At this time, the extension portions 70A, 70B may be provided on the outer member main body 62. The outer 50 may be provided with only one of the covers 64A and 64B.

Although the example in which the outer case 34 constitutes the outer member main body 62 has been described above, the outer case may constitute the entire outer member 50. It should be understood that the housing 34 may be at least a part of the outer member 50.

The fixing members 18A, 18B serving as the inner members 52A, 52B may be combined with other members other than the carriers 36A, 36B. The wheel frames 36A, 36B may be at least a part of the fixed members 18A, 18B serving as the inner members 52A, 52B.

Only one of the 1 st carrier 36A and the 2 nd carrier 36B may be coupled to the vehicle body fixing member 40.

Specific examples of the inserted member 94 are not particularly limited. The inserted member 94 may be a bolt for connecting the 1 st inner member 52A and the 2 nd inner member 52B, or may be a bolt for connecting a wheel. The insertion hole 96 may be opened in both the 1 st inner side member 52A and the 2 nd inner side member 52B, or may be opened only in the 1 st inner side member 52A.

The above-described embodiment and modifications are merely examples. These abstract technical ideas are not to be construed as limiting the contents of the embodiments and the modifications. The contents of the embodiments and the modifications may be changed in many ways, for example, by changing, adding, deleting, etc. the components. In the above-described embodiments, the contents that can be subjected to such design changes are highlighted with the label "embodiment". However, content without such a flag also allows design changes. The hatching line shown in the cross section of the drawings does not limit the material of the object marked with the hatching line.

Claims (8)

1. A wheel driving device is provided with:

a deceleration mechanism that decelerates the rotation transmitted from the drive source;

a rotating member to which rotation reduced by the reduction mechanism is transmitted and which rotates together with a wheel;

a fixed member rotatably supporting the rotating member; and

a 1 st oil seal sealing a space accommodating the speed reducing mechanism,

the wheel drive apparatus is characterized in that,

when a member disposed on the radially outer side of the rotating member and the fixed member is an outer member and a member disposed on the radially inner side is an inner member,

the outer member includes an extending portion extending radially inward beyond an outermost diameter portion of the inner member,

the 1 st oil seal is disposed between an inner peripheral surface of the extending portion and the inner member.

2. The wheel drive apparatus according to claim 1,

a main bearing disposed between the outer member and the inner member,

the inner member has a bearing arrangement surface on which the main bearing is arranged,

the extending portion extends more radially inward than the bearing arrangement surface.

3. The wheel drive apparatus according to claim 1 or 2,

the second oil seal is disposed between the outer member and the inner member at a position radially outward of the first oil seal 1.

4. The wheel drive apparatus according to any one of claims 1 to 3,

comprises a lubricant sealed in a sealed space sealed by the 1 st oil seal,

the 1 st oil seal is provided with a lip part which is abutted with the inner side part,

the lip is disposed such that at least a portion thereof is located at a position lower than the level of the lubricant in a state where the vehicle wheel drive unit is stopped.

5. The wheel drive apparatus according to any one of claims 1 to 4,

an insertion hole into which an inserted member is inserted is formed in an axially outer side surface of the inner member,

the 1 st oil seal includes a lip portion abutting against a lip abutting surface of the inner member,

the outer diameter of the lip contact surface is set to be equal to or less than a minimum distance in a radial direction from a central axis of the inner member to the insertion hole.

6. The wheel drive apparatus according to any one of claims 1 to 5,

the outer member includes: an outer component body; and a cover body detachably connected to the outer member main body and provided with the extension portion.

7. The wheel drive device according to any one of claims 1 to 6, further comprising:

a housing;

an internal gear provided at the housing;

an outer gear engaged with the inner gear; and

a carrier disposed at an axial side portion of the outer gear,

the housing is at least a part of the rotating member which becomes the outside member,

the wheel carrier is at least a part of the fixing member that becomes the inner member.

8. The wheel drive apparatus according to claim 7,

the wheel carrier comprises: a 1 st carrier provided on one side of the outer gear in an axial direction; and a 2 nd carrier provided on the other side in the axial direction of the outer gear,

the vehicle body fixing member is coupled to both the 1 st wheel carrier and the 2 nd wheel carrier.

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