JP7431066B2 - wheel drive device - Google Patents

Description

The present disclosure relates to a wheel drive device.

2. Description of the Related Art Conventionally, wheel drive devices that drive wheels of transport vehicles and the like are known. Patent Document 1 discloses a wheel drive device that includes a speed reduction mechanism, a rotation member that rotates together with the wheel by receiving rotation from the speed reduction mechanism, and a fixed member that rotatably supports the rotation member.

JP 2018-131068 Publication

An oil seal for sealing lubricant is usually placed between the rotating member and the stationary member. The technique disclosed in Patent Document 1 does not take any special measures to reduce the risk of lubricant leakage at the location where the oil seal is arranged. From this perspective, the inventor of the present application has recognized that there is room for improvement regarding the technology disclosed in Patent Document 1.

One of the objectives of the present disclosure is to provide a technique that can reduce the risk of lubricant leakage.

An aspect of the present disclosure for solving the above problems is a wheel drive device. The wheel drive device of this aspect includes a speed reduction mechanism that decelerates the rotation transmitted from the drive source, a rotation member that rotates together with the wheel to which the rotation reduced by the speed reduction mechanism is transmitted, and a rotary member that rotatably rotates the rotation member. A wheel drive device comprising a supporting fixed member and a first oil seal sealing a space in which the speed reduction mechanism is housed, the member being disposed on the radially outer side of the rotating member and the fixed member. is an outer member, and a member disposed radially inward is an inner member, the outer member includes an extension portion extending radially inward beyond the outermost diameter portion of the inner member, The first oil seal is arranged on the inner circumferential surface of the extension part.

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

It is a front sectional view of the wheel drive device of a 1st embodiment. FIG. 2 is an enlarged view of FIG. 1; It is a front sectional view which expanded the wheel drive device of 2nd Embodiment. It is a front sectional view of the wheel drive device of a 3rd embodiment.

Embodiments will be described below. Identical components are given the same reference numerals and redundant explanations will be omitted. In each drawing, constituent elements are omitted, enlarged, or reduced as appropriate for convenience of explanation. The drawings should be viewed according to the direction of the symbols. Unless otherwise specified, "contact," "fixation," and "attachment" as used herein refer to cases in which the mentioned conditions are satisfied not only directly between the two parties but also through another member. Also included.

(First Embodiment) Refer to FIG. 1. The wheel drive device 10 is assembled to a vehicle body 12 such as a transport vehicle, and is used to drive wheels 20. Although the reference numeral 12 is strictly a motor, since the motor is fixed to the vehicle body, in this embodiment, the motor is included in the vehicle body 12. Hereinafter, the direction along the rotation center line CL1 of the wheel 20 will be referred to as the axial direction X of the wheel drive device 10. The circumferential direction and radial direction of a circle centered on the rotation center line CL1 are referred to as the "circumferential direction" and "radial direction" of the wheel drive device 10.

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 deceleration mechanism 14 is capable of decelerating the rotation transmitted from the drive source. The driving source is, for example, a motor, a gear motor, an engine, or the like. The speed reduction mechanism 14 of this embodiment is an eccentric swing type speed reduction mechanism. The speed reduction mechanism 14 mainly includes an input shaft 24, an external gear 26, and an internal gear 28.

The input shaft 24 is provided so as 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 swinging the external gear 26. A plurality of eccentric portions 24a are provided at intervals in the axial direction X.

The external gear 26 is provided individually corresponding to each of the plurality of eccentric portions 24a. The external gear 26 is rotatably supported by the corresponding eccentric portion 24a via an eccentric 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 be different from the number of external teeth of the external gear 26.

Rotation reduced by the speed reduction mechanism 14 is transmitted to the rotating member 16 . The rotating member 16 of this embodiment includes a casing 34 disposed on the outer peripheral side of the speed reduction mechanism 14 . The casing 34 has a cylindrical shape as a whole. An internal gear 28 is provided on the inner circumference of the casing 34 .

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

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

The carriers 36A, 36B include a first carrier 36A provided on one side in the axial direction with respect to the external gear 26, and a second carrier 36B provided on the other side in the axial direction with respect to the external gear 26. The first carrier 36A is the first fixing member 18A, and the second carrier 36B is the second fixing member 18B. In this embodiment, the carriers 36A and 36B are connected to a vehicle body fixing member 40 that is fixed to the vehicle body 12. The fixing members 18A and 18B are connected to the vehicle body fixing member 40, so that they cannot rotate with respect to the rotating member 16.

The wheels 20 can travel on a running surface by rotating together with the rotating member 16. The running surface is, for example, the floor of a building, a rail, or the like. The wheel 20 includes a wheel body 42 and a grounding member 44.

The wheel body 42 has a cylindrical shape as a whole. The wheel main body 42 of this embodiment is arranged on the outer peripheral side of the rotating member 16. The wheel body 42 is integrated with the rotating member 16 using bolts B1 and the like. In this embodiment, the rotating member 16 and the wheel body 42 are tightened together by a bolt B<b>1 screwed into the rotating member 16 , so that they are integrated with the rotating member 16 . The bolt B1 passes through the first cover 64A without being screwed into the first cover 64A, which will be described later.

The ground member 44 makes contact with the running surface. The grounding member 44 of this embodiment is a tire, and is attached to the wheel body 42 using adhesive or the like.

In addition, the wheel drive device 10 includes a vehicle body fixing member 40. The vehicle body fixing member 40 of this 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 that is removably attached to the vehicle body 12 with bolts or the like, and an anti-vehicle body side member 48 that is removably attached to the vehicle body side member 46 with bolts B2 or the like. The vehicle body side member 46 covers the wheel 20 from the vehicle body side, and the anti-vehicle body side member 48 covers the wheel 20 from the vehicle body side. A second carrier 36B is removably connected to the vehicle body side member 46 using bolts B3 or the like. The first carrier 36A is removably connected to the opposite-to-vehicle body side member 48 using spigot fitting or the like. Thereby, both the first carrier 36A and the second carrier 36B are connected to the vehicle body fixing member 40. Since the vehicle body fixing member 40 supports the wheels 20 from both sides in the axial direction, it is possible to stabilize the running operation of the wheels 20.

The operation of the above wheel drive device 10 will be explained. When the input shaft 24 rotates due to 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 wheels 20 rotate together with the rotating member 16, so that the wheels 20 run on the running surface.

In this embodiment, the eccentric portion 24a rotates together with the input shaft 24 around the rotation center line CL1, and this rotation causes the external gear 26 to oscillate so that the axis of the external gear 26 rotates around the rotation center line CL1. move. When the external gear 26 swings, the meshing positions of the external gear 26 and the internal gear 28 are sequentially shifted. As a result, the internal gear 28 and the external gear 26 rotate relative to each other by an amount corresponding to the difference in the number of teeth between the internal gear 28 and the external gear 26 each time the input shaft 24 rotates once. At this time, one of the internal gear 28 and the external gear 26 (in this embodiment, the internal gear 28) rotates, and the rotation component is transmitted to the rotating member 16.

Here, of the rotating member 16 and the fixed members 18A and 18B, the member disposed on the radially outer side is referred to as an outer member 50, and the member disposed on the radially inner side as inner members 52A and 52B. In this embodiment, the rotating member 16 is the outer member 50, and the fixed members 18A, 18B are the inner members 52A, 52B. The outer member 50 is a member that supports the outer circumferential side of the first oil seal 76, which will be described later, and the inner member 52 can also be understood as a member that comes into contact with the inner circumferential side (lip portion) of the first oil seal 76. I can do it. The inner members 52A and 52B of this embodiment include a first inner member 52A provided on one axial side (anti-vehicle side) and a second inner member 52B provided on the other axial side (vehicle body side). The first inner member 52A is constituted by the first fixing member 18A (first carrier 36A), and the second inner member 52B is constituted by the second fixing member 18B (second carrier 36B).

The wheel drive device 10 includes main bearings 54A and 54B such as rolling bearings. The main bearings 54A, 54B include a first main bearing 54A disposed between the outer member 50 and the first inner member 52A, and a second main bearing 54B disposed between the outer member 50 and the second inner member 52B. Equipped with.

See FIG. 2. The first inner member 52A includes a first bearing arrangement surface 56A on which (the inner ring of) the first main bearing 54A is arranged. The first inner member 52A includes a first outermost diameter portion 58A having the largest outer diameter in the first inner member 52A. The first outermost diameter portion 58A of this embodiment is provided axially outer than the first main bearing 54A and radially outer than the first bearing placement surface 56A. The second inner member 52B includes a second bearing arrangement surface 56B on which (an inner ring of) the second main bearing 54B is arranged. The second inner member 52B includes a second outermost diameter portion 58B having the largest outer diameter in the second inner member 52B. The second outermost diameter portion 58B is provided axially outer than the second main bearing 54B and radially outer than the second bearing placement surface 56B. Each inner member 52A, 52B includes a protrusion 60 that protrudes axially outward on the axially outer surface.

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

The covers 64A and 64B are applied to one side surface of the outer member main body 62 in the axial direction, and are removably connected to the outer member main body 62 using, for example, bolts B4. A sealing member 66 such as an O-ring is arranged between the outer member main body 62 and the covers 64A, 64B. A seal member 66 seals between the outer member main body 62 and the covers 64A, 64B.

In this embodiment, the covers 64A and 64B are individually provided on both sides of the outer member main body 62 in the axial direction. The covers 64A, 64B include a first cover 64A provided on the axially outer side of the first inner member 52A, and a second cover 64B provided on the axially outer side of the second inner member 52B. The covers 64A, 64B include an annular fitting portion 68 that protrudes 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 fitted into the outer member main body 62 with a spigot. The fitting portion 68 is arranged at a position radially overlapping the outermost diameter portions 58A, 58B of the carriers 36A, 36B.

The outer member 50 includes extensions 70A and 70B. The extending portions 70A and 70B include a first extending portion 70A corresponding to the first inner member 52A and a second extending portion 70B corresponding to the second inner member 52B. The first extending portion 70A is provided on the first cover 64A as a part of the first cover 64A, and the second extending portion 70B is provided on the second cover 64B as a part of the second cover 64B. The extension 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 from the bearing arrangement surfaces 56A, 56B of the corresponding inner members 52A, 52B. In this embodiment, the extending portions 70A and 70B extend to a position overlapping an inserted member 94, which will be described later, when viewed from the axial direction X.

The extending portions 70A and 70B include a thin wall portion 72 and a thick wall portion 74 provided radially inside the thin wall portion 72. The axial dimension of the thick portion 74 is set to be larger than the axial dimension of the thin portion 72. The thick portion 74 is formed to protrude inward in the axial direction with respect to the thin portion 72.

The wheel drive device 10 includes a first oil seal 76 arranged between the outer member 50 and the inner members 52A and 52B. The first oil seals 76 individually correspond to the plurality of inner members 52A and 52B. The first oil seal 76 is arranged between the inner circumferential surface of the first extending portion 70A of the outer member 50 corresponding to the first inner member 52A and the protrusion 60 of the first inner member 52A. In addition, the first oil seal 76 is arranged between the inner peripheral surface of the second extending portion 70B of the outer member 50 corresponding to the second inner member 52B and the protruding portion 60 of the second inner member 52B. Ru. The extending portions 70A and 70B of the outer member 50 include a seal placement surface 78 on which the first oil seal 76 is placed. The seal arrangement surface 78 is provided on the inner circumferential surface of the thick portion 74 .

The first oil seal 76 seals the storage space 80 that houses the speed reduction mechanism 14, thereby forming an enclosure space 84 in which the lubricant 82 is enclosed. In addition to the first oil seal 76, the enclosed space 84 is sealed by a seal cover 85 (see FIG. 1) arranged inside the first inner member 52A (first carrier 36A). Although the lubricant 82 in this embodiment is lubricating oil, it may also be grease or the like. The enclosed space 84 includes a storage space 80 that accommodates the deceleration mechanism 14, and a gap space 86 provided between the outer member 50 and the inner members 52A and 52B. In this embodiment, the external gear 26 and internal gear 28 of the speed reduction mechanism 14 are stored in the storage space 80 . The gap space 86 is provided between an outer circumferential space 88 provided between the outer member main body 62 and the inner members 52A, 52B, and a radially inner side of the outer circumferential space 88 between the covers 64A, 64B and the inner members 52A, 52B. and an inner peripheral side space 90. Main bearings 54A and 54B are arranged in the outer peripheral space 88.

The effects of the above wheel drive device 10 will be explained.

Consider the case where the lubricant 82 is sealed in the sealed space 84 sealed by the first oil seal 76 as in this embodiment. In this case, the lubricant 82 tends to accumulate in the outer peripheral 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 following the rotation of the outer member 50, and centrifugal force is applied to the lubricant 82. When the inner members 52A, 52B become the rotating members 16, the lubricant 82 adhering to the inner members 52A, 52B is shaken off radially outward. In addition, dynamic pressure acts on the lubricant 82 accumulated in the outer peripheral space 88 due to the movement of the rolling elements of the main bearings 54A, 54B. This dynamic pressure acts particularly strongly when the outer member 50 becomes the rotating member 16 due to the centrifugal force applied to the lubricant 82. Due to this, when the first oil seal 76 is disposed in the outer peripheral space 88, the first oil seal 76 is required to have high sealing performance.

The first oil seal 76 of this embodiment is disposed between the extending portions 70A, 70B of the outer member 50 and the inner members 52A, 52B, which are located inwardly away from the outer peripheral space 88. Therefore, it becomes difficult for the lubricant 82 to reach the location where the first oil seal 76 is arranged, and the risk of the lubricant 82 leaking from there to the outside can be reduced. In addition, dynamic pressure is less likely to act on the first oil seal 76 than in the case where the first oil seal 76 is disposed in the outer peripheral space 88. Therefore, the first oil seal 76 is not required to have high sealing performance, and the first oil seal 76 can be used at a low cost to ensure the sealing performance.

In addition, compared to the case where the first oil seal 76 is disposed in the outer peripheral space 88, it is possible to plan for a smaller outer diameter dimension required for the first oil seal 76. As a result, the degree of freedom in designing the first oil seal 76 can be increased, and the cost of parts for the first oil seal 76 can be reduced.

The casing 34 of this embodiment is at least a part of the rotating member 16 that becomes the outer member 50. Therefore, a particularly large dynamic pressure acts on the lubricant 82 due to the above-mentioned centrifugal force. Even under such a situation, there is an advantage that the sealing performance required of the first oil seal 76 can be reduced, as described above.

Let us consider a case where the first oil seal 76 is disposed between the outer member main body 62 and the inner members 52A and 52B. In this case, in order to replace the first oil seal 76, it is necessary to disassemble the outer member main body 62 and the inner members 52A and 52B. Accordingly, it is necessary to largely move the components of the speed reduction mechanism 14 (external gear 26, etc.) within the outer member main body 62, which requires large-scale work.

In this regard, the outer member 50 includes covers 64A and 64B that are removably 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 first oil seal 76 is disposed. . Therefore, by removing the covers 64A, 64B from the outer member main body 62, the first oil seal 76 can be separated from the outer member main body 62 together with the covers 64A, 64B. At this time, in this embodiment, the covers 64A and 64B are removed from the outer member main body 62 while the outer member 50 and inner members 52A and 52B are separated from the vehicle body fixing member 40. At this time, the covers 64A and 64B are removed from the outer member main body 62 while the inner members 52A and 52B are placed inside the outer member main body 62. In this manner, the process of separating the first oil seal 76 from the outer member main body 62 does not involve disassembly of the outer member main body 62 and the inner members 52A, 52B. Therefore, when replacing the first oil seal 76, the components of the speed reduction mechanism 14 within the outer member main body 62 do not have to be moved significantly, and good workability can be obtained.

In addition, when replacing the first oil seal 76, there is a method of pulling out only the first oil seal 76 using a tool, or a method of inserting a tapping screw into the first oil seal 76. When these methods are used, there is a risk of damaging the surrounding structures (outer member 50 and inner members 52A, 52B). There is an advantage in avoiding this.

Other features of the wheel drive device 10 will be explained. The first oil seal 76 is attached to the extensions 70A, 70B of the outer member 50 by an interference fit or the like. The first oil seal 76 includes a lip portion 76a that is elastically deformed and comes into contact with the lip contact surfaces 92 of the inner members 52A, 52B. The sealed space 84 is sealed by the lip portion 76a of the first oil seal 76 coming into contact with the inner members 52A, 52B. Let L be the liquid level of the lubricant 82 in a stationary state when the wheel drive device 10 is stopped. At least a portion of the lip portion 76a is provided at a position lower than the liquid level L of the lubricant 82. In this embodiment, at least a portion of the lip contact surface 92 is provided at a position lower than the liquid level L of the lubricant 82. It can also be considered that the outer diameter of the lip contact surface 92 is set so as to satisfy this condition. This condition is satisfied by the lip contact surfaces 92 of each of the plurality of inner members 52A, 52B in this embodiment. This condition may be satisfied only by the lip contact surface 92 of a single inner member 52A, 52B.

Thereby, a portion of the lip portion 76a of the first oil seal 76 can be reliably wetted with the lubricant 82. As a result, it is possible to prevent the lip portion 76a of the first oil seal 76 from running out of lubrication.

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 the object to be ground (here, the lip contact surface 92) by moving a grindstone relative to the object to be ground (here, the inner members 52A and 52B) in the circumferential direction. be. Thereby, it is possible to form minute annular irregularities on the lip abutting surface 92 while reducing the surface roughness of the lip abutting surface 92. Furthermore, compared to traverse grinding, it is possible to make it difficult for the lubricant 82 to leak in the axial direction X through between the lip portion 76a of the first oil seal 76 and the lip contact surface 92.

An insertion hole 96 into which an inserted member 94 is inserted is opened in the axially outer surface 52a of the second inner member 52B. The insertion hole 96 opens at a position exposed to the gap space 86. The insertion hole 96 is provided at a position overlapping the first oil seal 76 in the axial direction X. The inserted member 94 is inserted inward in the axial direction from the opening of the insertion hole 96 on the outer surface 52a. The inserted member 94 is, for example, a pin that synchronizes with the rotation component or revolution component of the external gear 26. "Synchronization" here refers to maintaining the rotation component or revolution component of the external gear 26 and the revolution component of the pin at the same magnitude within a numerical range including 0. The revolution component assumes that, for example, a planetary gear of a simple planetary mechanism constitutes the external gear 26.

Please refer to FIG. The central axis of the inner members 52A and 52B is referred to as CL2. This is provided at a position overlapping the rotation center line CL1 of the wheel 20. The outer diameter L2 of the lip contact surface 92 of the inner members 52A, 52B is set to be less than or equal to the minimum distance L1 in the radial direction from the central axis CL2 of the inner members 52A, 52B to the insertion hole 96. This minimum distance L1 is the minimum diameter of a circle inscribed in the insertion hole 96 centered on the central axis CL2. In this embodiment, the outer diameter L2 of the lip contact surface 92 is set to be less than this minimum distance L1. This makes it possible to avoid interference between the lip contact surfaces 92 of the inner members 52A and 52B when inserting the inserted member 94.

(Second Embodiment) Refer to FIG. 3. The wheel drive device 10 of this embodiment includes a second oil seal 98 disposed between the outer member 50 and the inner members 52A and 52B on the outer side in the radial direction than the first oil seal 76. The second oil seals 98 are individually provided corresponding to the plurality of inner members 52A, 52B, and are arranged between the outermost diameter portions 58A, 58B of the corresponding inner members 52A, 52B and the outer member 50. The inner diameter of the second oil seal 98 in this embodiment is set to be larger than the outer diameter of the first oil seal 76. The axial dimension of the second oil seal 98 in this embodiment is set to be smaller than the axial dimension of the first oil seal 76.

As a result, the second oil seal 98 makes it difficult for the lubricant 82 to reach the inner space 90 from the storage space 80 of the sealed space 84 . As a result, it becomes even more difficult for the lubricant 82 to reach the location where the first oil seal 76 is arranged, and the risk of leakage of the lubricant 82 can be further reduced.

(Third Embodiment) Refer to FIG. 4. The wheel drive device 10 of this embodiment is different from the first embodiment regarding the wheels 20. The wheels 20 of this embodiment are mecanum wheels. The grounding member 44 of the wheel 20 is a plurality of barrel-shaped rollers rotatably supported by the wheel body 42. The roller is rotatable around a rotation axis that is inclined with respect to the rotation center line CL1 of the wheel 20. In addition, the vehicle body fixing member 40 of this embodiment differs in that it only includes a vehicle body side member 46.

In this way, the type of wheel 20 is not particularly limited. Wheel 20 may be an omniwheel, for example. In this case, the grounding member 44 is constituted by a roller whose rotation center is a direction along a tangent passing through the outer peripheral surface of the wheel body 42.

Other modifications of each component will be explained.

Although an example has been described in which the wheel drive device 10 is incorporated into a transport vehicle, the vehicle body to which the wheel drive device 10 is incorporated is not particularly limited.

An example has been described in which one axial side is the anti-vehicle side and the other axial side is the vehicle body side. Alternatively, one axial side may be on the vehicle body side, and the other axial side may be on the opposite side to the vehicle body.

Although the speed reduction mechanism 14 has been described using an eccentric swing type speed reduction mechanism as an example, its type is not particularly limited. For example, it may include any one of a planetary gear mechanism, a parallel axis gear mechanism, an orthogonal axis gear reduction mechanism, a flexible mesh type reduction mechanism, and the like. In this embodiment, a center crank type in which the input shaft 24 (crankshaft) is arranged on the rotation center line CL1 has been described as the eccentric swing type speed reduction mechanism. In addition to this, the eccentric swing type speed reduction mechanism may be of a distributed type in which a plurality of input shafts 24 (crankshafts) are arranged at positions offset from the rotation center line CL1.

The rotating member may be an inner member and the stationary member may be an outer member. This assumes, for example, that the casing 34 becomes part of the stationary member and the carriers 36A, 36B become part of the rotating member.

An example has been described in which the wheels 20 are provided at positions that overlap in the radial direction with respect to the speed reduction mechanism 14. The present invention is not limited thereto, and the wheels 20 may be provided at positions that do not overlap with the speed reduction mechanism 14 in the radial direction. This assumes, for example, that the wheels 20 are arranged on the opposite side of the vehicle body with respect to the speed reduction mechanism 14.

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

The entire lip portion 76a of the first oil seal 76 may be provided at a position higher than the liquid level L of the lubricant 82.

The outer diameter L2 of the lip contact surfaces 92 of the inner members 52A, 52B may be set to the same size as the above-mentioned minimum distance L1. In addition to this, the outer diameter L2 may be set to a size exceeding the minimum distance L1.

The outer member 50 may include only the outer member main body 62 and may not include the covers 64A and 64B. In this case, the outer member main body 62 may be provided with extending portions 70A and 70B. In addition to this, the outer member 50 may include only one of the covers 64A and 64B.

Although an example has been described in which the casing 34 constitutes the outer member main body 62, it may constitute the entire outer member 50. It is also understood that the casing 34 only needs to be at least a part of the outer member 50.

The fixing members 18A and 18B, which become the inner members 52A and 52B, may be configured in combination with other members other than the carriers 36A and 36B. It is also understood that the carriers 36A, 36B may be at least a portion of the fixing members 18A, 18B, which become the inner members 52A, 52B.

Only one of the first carrier 36A and the second carrier 36B may be connected to the vehicle body fixing member 40.

A specific example of the inserted member 94 is not particularly limited. The inserted member 94 may be a bolt that connects the first inner member 52A and the second inner member 52B, or may be a bolt that connects the wheels. The insertion hole 96 may be opened in both the first inner member 52A and the second inner member 52B, or may be opened only in the first inner member 52A.

The above embodiments and modifications are merely examples. These abstracted technical ideas should not be interpreted as being limited to the contents of the embodiments and modifications. The content of the embodiments and modifications may be subject to many design changes such as changes, additions, and deletions of constituent elements. In the embodiments described above, the content that allows such design changes is emphasized by adding the notation "embodiment". However, design changes are allowed even if there is no such notation. The hatching added to the cross section of the drawing does not limit the material of the hatched object.

DESCRIPTION OF SYMBOLS 10... Wheel drive device, 12... Vehicle body, 14... Reduction mechanism, 16... Rotating member, 18... Fixed member, 20A... Main bearing, 22... Wheel, 26... External gear, 28... Internal gear, 34... Casing, 36A...first carrier, 36B...second carrier, 40...vehicle body fixing member, 50...outer member, 52A, 52B...inner member, 52a...outer surface, 54A, 54B...main bearing, 56A, 56B...bearing arrangement surface, 58A, 58B...outermost diameter part, 62...outer member main body, 64A...cover, 70A, 70BB...extension part, 76...first oil seal, 76a...lip part, 82...lubricant, 84...enclosed space, 92 ...Lip abutting surface, 94...Inserted member, 96...Insertion hole, 98...Second oil seal.

Claims (8)

a deceleration mechanism that decelerates the rotation transmitted from the drive source;
an inner member provided on the side of the wheel in the axial direction with respect to the speed reduction mechanism;
an outer member that is disposed radially outward of the inner member and forms a space that accommodates the speed reduction mechanism together with the inner member;
a first oil seal sealing the space ;
Among the inner member and the outer member, one member is a rotating member to which rotation decelerated by the speed reduction mechanism is transmitted and rotates together with the wheel, and the other member rotatably supports the rotating member. A wheel drive device that is a fixed member that
The outer member includes an extending portion that extends from a location radially outer than the outermost diameter portion of the inner member beyond the outermost diameter portion and radially inward,
The first oil seal is disposed between the inner circumferential surface of the extending portion and the inner member , and seals between the extending portion and the inner member . a main bearing disposed between the outer member and the inner member;
The inner member includes a bearing arrangement surface on which the main bearing is arranged,
The wheel drive device according to claim 1 , wherein the extending portion extends from a location radially outer than the outermost diameter portion to radially inward than the bearing arrangement surface. The wheel drive device according to claim 1 or 2, further comprising a second oil seal arranged between the outer member and the inner member at a radially outer side than the first oil seal. comprising a lubricant sealed in the space ,
The first oil seal includes a lip portion that comes into contact with the inner member,
According to any one of claims 1 to 3, at least a portion of the lip portion is provided at a position lower than the liquid level of the lubricant when the wheel drive device is stopped. wheel drive. An insertion hole into which the inserted member is inserted is opened on the outer surface of the inner member in the axial direction,
The first oil seal includes a lip portion that comes into contact with a lip contact surface of the inner member,
The wheel drive device according to any one of claims 1 to 4, wherein the outer diameter of the lip contact surface is set to be less than or equal to the minimum distance in the radial direction from the central axis of the inner member to the insertion hole. The wheel drive device according to any one of claims 1 to 5, wherein the outer member includes an outer member main body and a cover that is removably connected to the outer member main body and is provided with the extension portion. casing and
an internal gear provided in the casing;
an external gear that meshes with the internal gear;
a carrier provided on the side of the external gear in the axial direction;
The casing is at least a part of the rotating member that becomes the outer member,
The wheel drive device according to any one of claims 1 to 6, wherein the carrier is at least a part of the fixed member that becomes the inner member. The carrier includes a first carrier provided on one side of the external gear in the axial direction, and a second carrier provided on the other side of the external gear in the axial direction,
The wheel drive device according to claim 7, wherein a vehicle body fixing member is connected to both the first carrier and the second carrier.

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