Wheel drive unit

Abstract

To provide a technology that can attain good workability during supply of grease.SOLUTION: A wheel driving device includes: a driving source; and a speed reducer 18, which reduces a speed of power input from the driving source and outputs the power, and drives a wheel 20 with output of the speed reducer 18. The speed reducer 18 includes a grease supply hole 62 and a grease discharge hole 64. The wheel driving device 14 is configured to supply or discharge a lubricant 54 through the grease supply hole 62 and the grease discharge hole 64 with the speed reducer 18 attached to a vehicle body 12.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to a wheel drive device that drives a wheel. [Background technology]

[0002] Conventionally, there has been known a wheel drive device that drives the wheels of a transport vehicle, etc. Patent Document 1 discloses a wheel drive device that includes a drive source, a reducer that reduces and outputs power input from the drive source, and a wheel that rotates by the output of the reducer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-131068 Summary of the Invention [Problem to be solved by the invention]

[0004] In some cases, a lubricant is supplied into a reducer. The technology disclosed in Patent Document 1 does not incorporate any special measures to improve the workability of the lubrication process. From this perspective, the inventors of the present application have recognized that there is room for improvement in the technology disclosed in Patent Document 1.

[0005] One of the objects of the present disclosure is to provide a technique that allows for good workability during greasing. [Means for solving the problem]

[0006] One aspect of the present disclosure for solving the above-mentioned problems is a wheel drive device that includes a drive source and a reducer that reduces and outputs power input from the drive source, and drives wheels with the output of the reducer, the reducer having a grease inlet and a grease drain hole, and the wheel drive device is configured so that lubricant can be supplied and drained through the grease inlet and the grease drain hole while the reducer is attached to the vehicle body.

[0007] Another aspect of the present disclosure is a greasing method for a wheel drive device, the wheel drive device including a drive source and a reducer that reduces the speed of power input from the drive source and outputs the reduced speed, the reducer including a speed reducer unit that reduces the speed of the power input from the drive source, an internal member that is disposed axially to the reducer unit and that is provided with a grease hole, and a cover that covers the internal member and that is provided with a grease hole, the greasing method including rotating the cover and the internal member relative to each other to align the phases of the grease hole and the grease hole and thereby supplying grease through the grease hole and the grease hole.

[0008] Another aspect of the present disclosure is a vehicle including a vehicle body and a plurality of wheel drive units mounted on the vehicle body, each wheel drive unit including a drive source and a reducer that reduces the speed of power input from the drive source and outputs the reduced power, the wheel drive unit is driven by the output of the reducer, the reducer includes a grease supply port and a rotating body that rotates together with the wheel, the wheel drive unit is capable of changing its state between a grease-appropriate state that is appropriate for grease using the grease supply port and a grease-inappropriate state that is inappropriate for grease using the grease supply port by changing the phase of the rotating body, and the vehicle is configured such that when any of the wheel drive units is in the grease-appropriate state, the other wheel drive units are also in the grease-appropriate state. [Effects of the Invention]

[0009] According to the present disclosure, good workability can be achieved during greasing. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic plan view of a vehicle. [Figure 2] FIG. [Figure 3] FIG. 4 is another side cross-sectional view of the wheel drive device. [Figure 4] 4 is a view showing a part of the wheel drive device as seen from the arrow A in FIG. 3. [Figure 5] 5 is another view of a part of the wheel drive device seen from the same viewpoint as FIG. 4. [Figure 6] FIG. 4 is a diagram showing a state before grease is supplied into the reducer. [Figure 7] FIG. 10 is a diagram showing a state in which grease is being supplied into the reducer. [Figure 8] FIG. 2 is a schematic plan view showing the phases of each wheel drive device. [Figure 9] 10A and 10B are explanatory diagrams of a modified example of a greasing method. DETAILED DESCRIPTION OF THE INVENTION

[0011] The following describes the embodiments. Identical components are assigned the same reference numerals, and redundant explanations are omitted. In each drawing, components are omitted, enlarged, or reduced as appropriate for the sake of convenience. The drawings should be viewed according to the orientation of the reference numerals. Unless otherwise specified, the terms "fixing" and "attaching" in this specification include cases where the conditions mentioned are met directly by two parties, as well as cases where the conditions are met via other members.

[0012] Referring to Figure 1, a vehicle 10 includes a vehicle body 12 and a plurality of wheel drive devices 14 mounted on the vehicle body 12. The wheel drive devices 14 include wheels 20 driven by drive sources 16. The vehicle 10 of this embodiment is an all-wheel drive vehicle in which the wheels 20 of each of the plurality of wheel drive devices 14 are driven by individual drive sources 16. The vehicle 10 of this embodiment is a transport vehicle. The transport vehicle may be an unmanned transport vehicle such as an AGV, or may be a manned transport vehicle that travels under the control of an operator.

[0013] See Figure 2. 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 14. The circumferential direction and radial direction of a circle centered on this rotation center line CL1 will be referred to as the "circumferential direction" and "radial direction" of the wheel drive device 14.

[0014] The wheel drive device 14 includes a drive source 16, a reducer 18 that reduces the power input from the drive source 16, i.e., the rotation, and outputs the reduced power, and a wheel 20 that rotates due to the output of the reducer 18. The drive source 16 in this embodiment is a motor. There are no particular limitations on the specific example of the drive source 16. Other examples of the drive source 16 include a gear motor and an engine.

[0015] The reducer 18 includes a base 22 that supports the drive source 16. The base 22 is a cylindrical member that extends in the axial direction X. The base 22 is detachably fixed to the vehicle body 12. A main body 16a of the drive source 16 is attached to the base 22.

[0016] The reducer 18 includes an input shaft 24 and a reduction unit 26 to which power is input from the drive source 16 via the input shaft 24. The reducer 18 includes carriers 28A, 28B that support the reduction unit 26, a case 30 that is rotatable relative to the carriers 28A, 28B, and main bearings 32A, 32B that are arranged between the carriers 28A, 28B and the case 30.

[0017] The input shaft 24 is connected to the output shaft 14b of the drive source 16 so as to be able to transmit power from the output shaft 14b. The input shaft 24 is disposed inside the case 30 and the base 22.

[0018] The speed reducer 26 reduces the speed of the power input from the drive source 16 and transmits the power to the carriers 28A, 28B or the case 30. The destination of this power transmission forms a rotating body 38, which will be described later, and in this embodiment, this is the case 30. The speed reducer 18 in this embodiment is a planetary gear type speed reducer, and the speed reducer 26 is a planetary gear that meshes with an internal gear 34 provided on the inner periphery of the case 30.

[0019] The case 30 is a cylindrical member extending in the axial direction X. Inside the case 30, the speed reducer 26 and the carriers 28A and 28B are arranged.

[0020] The carriers 28A, 28B are disposed axially to the sides of the speed reducer 26. The carriers 28A, 28B are fixed to the end of the base 22 on the side opposite the vehicle body by fastening members B1 such as bolts. In this embodiment, the carriers 28A, 28B include a first carrier 28A disposed on the vehicle body side of the speed reducer 26, and a second carrier 28B disposed on the side opposite the vehicle body of the speed reducer 26. The first carrier 28A and the second carrier 28B are connected by a connecting member 36 such as a carrier pin. The connecting member 36 may be integrally formed as part of one of the first carrier 28A and the second carrier 28B, or may be a separate member from them.

[0021] The main bearings 32A, 32B are rolling bearings such as angular contact ball bearings, tapered roller bearings, etc. The main bearings 32A, 32B include a first main bearing 32A arranged between the case 30 and the first carrier 28A, and a second main bearing 32B arranged between the case 30 and the second carrier 28B.

[0022] The above-described speed reducer 18 includes a rotating body 38 that rotates together with the wheel 20, and a fixed body 40 that rotatably supports the rotating body 38 via main bearings 32A and 32B. The rotating body 38 in this embodiment is configured by a case 30 and a cover 50 (described later). The fixed body 40 in this embodiment is configured by carriers 28A and 28B and a base 22, and is fixed to the vehicle body 12.

[0023] The wheel 20 can travel on a travel surface by rotating together with the rotating body 38. The travel surface may be, for example, a floor surface, a rail, etc. In addition to the case 30, a speed reducer 26 is disposed inside the wheel 20 of this embodiment.

[0024] The wheel 20 comprises a wheel body 42 and a ground contact member 44 attached to the wheel body 42. The wheel 20 of this embodiment is a Mecanum wheel. The wheel body 42 is a cylindrical member. The ground contact member 44 comes into contact with the running surface. The ground contact member 44 of this embodiment is a plurality of barrel-shaped rollers that make up the Mecanum wheel. The rollers are attached to the wheel body 42 so as to be rotatable about rotation axes that are inclined with respect to the rotation center line CL1 of the wheel 20. In addition, the wheel 20 comprises a wheel hole 46 that opens into the side of the wheel body 42 facing away from the vehicle body.

[0025] The wheel 20 is fixed to the case 30 and one of the carriers 28A, 28B. This "one" is an element that constitutes the rotating body 38, which in this embodiment is the case 30. To achieve this, the wheel body 42 of the wheel 20 is connected to the case 30 by a fastening member B2 such as a bolt so as to be rotatable integrally with the case 30.

[0026] The operation of the wheel drive device 14 described above will now be described. Rotation is input from the drive source 16 to the speed reducer 26. The rotation input to the speed reducer 26 is reduced by the speed reducer 26 and transmitted to the rotating body 38. The rotating body 38 rotates together with the wheel 20, causing the wheel 20 to travel on the traveling surface.

[0027] Here, the reducer 18 includes an internal member 48 that is arranged axially to the side of the reduction unit 26. In this embodiment, the internal member 48 is formed by the second carrier 28B. Like the second carrier 28B, the internal member 48 is arranged on the opposite side of the vehicle body in the axial direction X from the reduction unit 26. The internal member 48 includes a central hole 48a that is provided in the axial center.

[0028] The reducer 18 includes a cover 50 that covers the internal member 48 from the outside in the axial direction. The cover 50 covers the internal member 48 from the side opposite the vehicle body in the axial direction X. The cover 50 is disk-shaped. The cover 50 is integrated with the case 30 by fastening members B3 such as bolts. The wheel 20, the cover 50, and the case 30 are connected in the axial direction X by fastening members B2 with the cover 50 sandwiched between the wheel 20 and the case 30. This allows the cover 50 to be firmly fixed to the case 30 by the wheel 20 and the case 30.

[0029] Please refer to Figures 2 and 3. Figure 3 shows a state in which the phase of the wheel 20 and the rotating body 38 is different from that in Figure 2. Figure 3 shows the level L1 of the upper surface of the lubricant 54 in a stationary state. The reducer 18 includes multiple seal elements 58A and 58B that seal the storage space 52 that houses the reduction gear unit 26, thereby forming an enclosed space 56 in which the lubricant 54 is enclosed. In this embodiment, the lubricant 54 is semi-solid grease, but it may also be lubricating oil or the like. The lubricant 54 is used to lubricate the meshing points between the reduction gear unit 26 and the internal gear 34, as well as the main bearings 32A and 32B. The seal elements 58A and 58B include a first seal element 58A that seals between the base 22 of the reducer 18 and the input shaft 24, a second seal element 58B that seals between the first carrier 28A and the case 30, and a cover 50 as a third seal element that is disposed axially outward of the internal member 48.

[0030] The enclosed space 56 includes a storage space 52 that stores the speed reducer 26, and an axial gap 60 that is provided between the internal member 48 and the cover 50. The storage space 52 is formed on the radially inner side of the case 30, at a location sandwiched between the pair of carriers 28A, 28B.

[0031] Please refer to Figures 3 and 4. In Figure 4, plug members 66A and 66B, which will be described later, are omitted. The reducer 18 has a grease supply hole 62 used to supply the lubricant 54 and a grease drain hole 64 used to drain the lubricant 54. The grease supply hole 62 and the grease drain hole 64 are provided in the cover 50 and penetrate the cover 50 in the axial direction X. The grease supply hole 62 and the grease drain hole 64 are provided in positions that overlap with the internal member 48 in the axial direction X. At least a portion of the grease drain hole 64 and the grease supply hole 62 are provided in positions symmetrical with respect to the rotation center line CL1 when viewed in the axial direction X. The grease supply hole 62 and the grease drain hole 64 in this embodiment are provided in positions that are visible from the outside through the wheel hole 46 when viewed in the axial direction X.

[0032] The reducer 18 includes a first plug member 66A that closes the grease supply hole 62 and a second plug member 66B that closes the grease drain hole 64. The first plug member 66A and the second plug member 66B are detachably attached to the grease supply hole 62 and the grease drain hole 64, respectively, via a screw structure or the like.

[0033] The reducer 18 has a plurality of grease holes 68 (two in this embodiment) provided in the internal member 48. In this embodiment, the plurality of grease holes 68 are provided separately from the central hole 48a of the internal member 48. The plurality of grease holes 68 axially penetrate the second carrier 28B that constitutes the internal member 48. The plurality of grease holes 68 in this embodiment are provided above and below both sides of the rotation center line CL1 as viewed from the axial direction X. At least some of the plurality of grease holes 68 in this embodiment are provided at positions symmetrical with respect to the rotation center line CL1 as viewed from the axial direction X.

[0034] Please refer to FIGS. 4 and 5. FIG. 5 is a diagram showing a state in which the phase of the cover 50 (rotating body 38) is shifted 90° clockwise from the state shown in FIG. 4. At least a portion of the grease supply hole 62 and the grease passage hole 68 are arranged to overlap in the axial direction X by rotating the cover 50 and the internal member 48 relative to each other. This can be achieved by rotating an element of the rotating body 38 (the cover 50 in this embodiment) out of the cover 50 and the internal member 48. In this embodiment, the central axis CL2 of the grease supply hole 62 and the grease passage hole 68 are arranged to overlap in the axial direction X. In addition, at least a portion of the grease drain hole 64 and the other grease passage holes 68 are also arranged to overlap in the axial direction by rotating the cover 50 and the internal member 48 relative to each other. In this embodiment, the central axis CL3 of the grease drain hole 64 and the other grease passage holes 68 are arranged to overlap in the axial direction X. In this embodiment, when the grease supply hole 62 and the grease vent hole 68 are overlapped in the axial direction, the grease drain hole 64 and the other grease vent holes 68 are also arranged to overlap in the axial direction.

[0035] 6 and 7. The grease vent hole 68 is used in cooperation with the grease supply hole 62 to supply the lubricant 54 directly from the outside to the storage space 52. The grease vent hole 68 is also used in cooperation with the grease drain hole 64 to drain the lubricant 54 directly from the storage space 52 to the outside.

[0036] The wheel drive device 14 is configured so that the lubricant 54 can be supplied and drained through the grease supply hole 62 and the grease drain hole 64 while the reducer 18 remains attached to the vehicle body 12. This means that the lubricant 54 can be supplied and drained without removing the reducer 18 from the vehicle body 12. In other words, it can be said that the lubricant 54 can be supplied and drained while the reducer 18 remains supported by the vehicle body 12. Here, "supplying and draining the lubricant 54" means supplying new lubricant 54 into the reducer 18 through the grease supply hole 62, while draining old lubricant 54 from the reducer 18 through the grease drain hole 64.

[0037] A method for supplying lubricant 54 using the above-described wheel drive device 14 will now be described. Here, a case will be described in which old lubricant 54 in the reducer 18 is replaced with new lubricant 54 using this lubricating method.

[0038] Referring to FIG. 6 , first, the operation of the wheel drive device 14 is stopped. In this state, a phase alignment process is performed in which the cover 50 and the internal member 48 are rotated relative to each other to align the phases (circumferential positions) of the grease supply hole 62 of the cover 50 and the grease passage hole 68 of the internal member 48. That is, the phase of the rotating body 38 (cover 50) is changed to align the phases of the grease supply hole 62 and the grease passage hole 68. At this time, the phase of the rotating body 38 is changed so that at least a portion of the grease supply hole 62 and the grease passage hole 68 overlap in the axial direction X. In this embodiment, by performing this phase alignment process, the phase of the grease drain hole 64 of the cover 50 and the other grease passage holes 68 of the internal member 48 is also aligned. At this time, the phase of the rotating body 38 is changed so that at least a portion of the grease drain hole 64 and the other grease passage holes 68 overlap in the axial direction X. In this embodiment, the phase of the rotating body 38 is changed so that the grease supply hole 62 and the grease passage hole 64 are located above and below the rotation center line CL1 as viewed in the axial direction X. At this time, the grease supply hole 62 is arranged on the lower side, and the grease drain hole 64 is arranged on the upper side.

[0039] The phase alignment process is performed, for example, by driving the motor while the wheel 20 is placed on the running surface, and rotating the wheel 20 together with the rotor 38. That is, in this example, the phase alignment process is performed by running the wheel 20 on the running surface. Note that the wheel 20 may also be rotated, for example, manually, while the wheel 20 is separated from the running surface.

[0040] Next, a greasing process is performed in which grease is supplied to the reducer 18 through the grease supply hole 62 and the grease passage hole 68 with the phases of the grease supply hole 62 and the grease passage hole 68 aligned. In this embodiment, grease is supplied to the reducer 18 with the phases of the grease supply hole 62 and the grease passage hole 68 aligned and with the phases of the grease drain hole 64 and the other grease passage holes 68 aligned.

[0041] Prior to the greasing step, the plug members 66A, 66B are removed from the greasing hole 62 and the greasing hole 64. Furthermore, prior to the greasing step, the greasing pipe 70 arranged outside the reducer 18 is connected to the greasing hole 62, and the greasing pipe 72 arranged outside the reducer 18 is connected to the greasing hole 64. In this state, new lubricant 54 in a pressurized state is supplied through the greasing pipe 70 and the greasing hole 62 using a pump.

[0042] As a result, as shown in FIG. 7 , new lubricant 54 is supplied into the reducer 18 through the grease supply hole 62 and the grease passage hole 68 (see arrow D1). The old lubricant 54 in the reducer 18 is washed away by the new lubricant 54. At least a portion of the old lubricant 54 in the storage space 52 is washed away by the new lubricant 54 so as to approach the other grease passage holes 68 (see arrow D2). As a result, at least a portion of the old lubricant 54 is pushed out through the other grease passage holes 68 and the grease drain hole 64 (see arrow D3). In this embodiment, the old lubricant 54 in the storage space 52 is pushed up and pushed out to the outside by the new lubricant 54. By supplying new lubricant 54 under pressure through the grease supply hole 62, the old lubricant 54 is drained through the grease drain hole 64. The lubricant 54 pushed out to the grease drain hole 64 is collected in an external tank through the grease drain pipe 72.

[0043] Once the greasing process is complete, the lubricant 54 inside the reducer 18 is drained through the grease drain hole 64 until it reaches the required level. Thereafter, plug members 66A, 66B are attached to the grease supply hole 62 and the grease drain hole 64, completing the entire process.

[0044] The above phase alignment process and greasing process are performed while the reducer 18 (the entire wheel drive device 14 in this embodiment) is attached to the vehicle body 12. In this embodiment, the above processes are performed while the wheel 20 is fixed to the reducer 18. At this time, the inside of the wheel hole 46 of the wheel 20 becomes a work space.

[0045] The effects of the above-described wheel drive device 14 will now be described. The wheel drive device 14 is configured so that the lubricant 54 can be supplied and drained through the grease supply hole 62 and the grease drain hole 64 while the reducer 18 remains attached to the vehicle body 12. Therefore, when supplying the lubricant 54, there is no need to remove the reducer 18 from the vehicle body 12, and good workability can be achieved. In addition, when draining the lubricant 54, there is no need to remove the reducer 18 from the vehicle body 12, and good workability can be achieved.

[0046] (A) At least a portion of the grease supply hole 62 and the grease vent hole 68 are arranged to overlap in the axial direction X by rotating the cover 50 and the internal member 48 relative to each other. Therefore, by aligning these phases, the lubricant 54 can be supplied to the storage space 52 while preventing the lubricant 54 from leaking into the axial gap 60. This in turn improves the work efficiency when supplying the lubricant 54.

[0047] (B) At least a portion of the grease drain hole 64 and the grease vent hole 68 are arranged to overlap in the axial direction X by rotating the cover 50 and the internal member 48 relative to each other. Therefore, by aligning these phases, the lubricant 54 can be drained from the storage space 52 while preventing the lubricant 54 from leaking into the axial gap 60. This in turn improves the efficiency of draining the lubricant 54. Furthermore, in this embodiment, by aligning the phases of the grease supply hole 62 and the grease vent hole 68, the phases of the grease drain hole 64 and the other grease vent holes 68 also align. Therefore, the phase alignment work is simplified, and grease supply and drainage can be performed simultaneously, improving workability.

[0048] Next, features of the vehicle 10 will be described with reference to Figures 4 and 5. The wheel drive device 14 can change its state between a lubrication appropriate state S1 (see Figure 4) and a lubrication inappropriate state S2 (see Figure 5) by changing the phase of the rotor 38.

[0049] The lubrication-appropriate state S1 is a predetermined state that is appropriate for lubrication using the lubrication hole 62. In this embodiment, the lubrication-appropriate state S1 refers to a state in which the lubrication hole 62 and the lubrication hole 68 are at least partially overlapping in the axial direction X (hereinafter referred to as an overlapping state), as shown in Fig. 4. In the overlapping state, as described above, it becomes easier to directly lubricate the storage space 52 using the lubrication hole 62.

[0050] The lubrication inappropriate state S2 is a predetermined state that is inappropriate for lubrication using the lubrication hole 62. In this embodiment, the lubrication inappropriate state S2 refers to a state in which the lubrication hole 62 and the lubrication hole 68 are positioned so as not to overlap in the axial direction, as shown in Fig. 5 (hereinafter referred to as a non-overlapping state). In this state, even if the lubricant 54 is supplied using the lubrication hole 62, it is difficult to supply the lubricant directly to the storage space 52.

[0051] Please refer to Figure 8. This figure also shows the internal members 48 and covers 50 of the multiple wheel drive units 14 viewed from the same perspective as Figure 4. The vehicle 10 is configured so that when any one of the wheel drive units 14 is in the lubrication appropriate state S1, the other wheel drive units 14 are also in the lubrication appropriate state S1. In this embodiment, when the lubrication hole 62 and the lubrication hole 68 of any one of the wheel drive units 14 overlap, the other wheel drive units 14 also satisfy the same condition.

[0052] In this configuration, before the vehicle 10 starts running, the phase of the rotating body 38 of each wheel drive unit 14 is preset to a phase that puts it in the lubrication appropriate state S1. This can be achieved, for example, by fixing the cover 50 of each wheel drive unit 14 to the case 30 in a phase that puts it in the lubrication appropriate state S1. The phase of the rotating body 38 of each wheel drive unit 14 is preset to a phase when the lubrication hole 62 and the lubrication hole 68 are overlapping.

[0053] The vehicle 10 of this embodiment is used to travel while maintaining the phase difference of the rotating bodies 38 among the multiple wheel drive devices 14. For example, if the phase difference of the rotating bodies 38 among the multiple wheel drive devices 14 is zero before the vehicle 10 begins to travel, the phase difference remains at zero after the vehicle 10 begins to travel. In this case, the phase difference of the rotating bodies 38 among the multiple wheel drive devices 14 does not change before and after the vehicle 10 begins to travel. Therefore, when the phase of the rotating body 38 of one wheel drive device 14 is set to the lubrication-appropriate state S1 in the phase alignment process described above, the phases of the rotating bodies 38 of the other wheel drive devices 14 also remain in the lubrication-appropriate state S1. In other words, the phase alignment process described above can be performed collectively for multiple wheel drive devices 14. Therefore, when lubricating the wheel drive devices 14 with the lubricant 54, it is not necessary to perform the phase alignment process for each individual wheel drive device 14. Consequently, good workability can be achieved when lubricating multiple wheel drive devices 14.

[0054] One of the cover 50 and the internal member 48 is the fixed member 74 that constitutes the fixed body 40 described above. In this embodiment, this "one" refers to the internal member 48. The phases of the grease holes 68 and the grease supply holes 62 provided in the fixed member 74 of the multiple wheel drive devices 14 are aligned. In this embodiment, this means that the phases (circumferential positions) of the grease holes 68 provided in the fixed member 74 (internal member 48) are aligned among the multiple wheel drive devices 14. In this embodiment, the phases of the grease holes 68 provided in the fixed member 74 (internal member 48) are aligned among the multiple wheel drive devices 14. Here, "aligned" does not only refer to the case where the phases of the holes provided in the fixed member 74 are completely aligned among the multiple wheel drive devices 14, but also includes cases where they are off by several degrees.

[0055] As a result, when any of the wheel drive devices 14 is set to the grease-suitable state S1, the phases of the grease holes 68 and the grease supply holes 62 can be aligned between the wheel drive devices 14. In other words, the circumferential positions of the grease holes 68 and the grease supply holes 62 can be aligned between the wheel drive devices 14, and grease can be supplied to each wheel drive device 14 in the same manner. Consequently, good workability can be achieved when supplying grease to multiple wheel drive devices 14.

[0056] Next, other features of the wheel drive device 14 will be described. Refer to FIG. 3 . One of the cover 50 and the internal member 48 is referred to as a first one member 78, and the other is referred to as a first other member 80. In this embodiment, the first one member 78 is the cover 50, and the first other member 80 is the internal member 48. The first one member 78 has a first protruding portion 82 that protrudes toward the first other member 80. Parts of the grease supply hole 62 and the grease passage hole 68 that are provided in the first one member 78 are provided in the first protruding portion 82. In this embodiment, part of the grease supply hole 62 provided in the cover 50 (first one member 78) is provided in the first protruding portion 82.

[0057] With the above configuration, the axial dimension of the axial gap 60 near the grease supply hole 62 and the grease passage hole 68 between the cover 50 and the internal member 48 can be made smaller than when the first protrusion 82 is not provided. This makes it difficult for the lubricant 54 to leak into the axial gap 60 when supplying grease through the grease supply hole 62 and the grease passage hole 68. Consequently, the lubricant 54 can be smoothly supplied all the way to the storage space 52.

[0058] To obtain a similar effect, the internal member 48 may be the first one member 78, and the cover 50 may be the first other member 80. In this case, the first protruding portion 82 is provided on the internal member 48 (first one member 78), and a part of the hole (grease passage hole 68) provided in the internal member 48 is provided in the first protruding portion 82. To obtain a similar effect, in addition to the first one member 78, the first other member 80 may be provided with another first protruding portion that protrudes toward the first one member 78. In this case, it is sufficient that a part of the grease supply hole 62 and the grease passage hole 68 that are provided in the first other member 80 is provided in the other first protruding portion.

[0059] One of the cover 50 and the internal member 48 is referred to as a second one member 84, and the other is referred to as a second other member 86. In this embodiment, the second one member 84 is the cover 50, and the second other member 86 is the internal member 48. The second one member 84 has a second protruding portion 88 that protrudes toward the second other member 86. Part of the grease drain hole 64 and the grease pass-through hole 68 that are provided in the second one member 84 are provided in the second protruding portion 88. In this embodiment, part of the grease drain hole 64 that is provided in the cover 50 (second one member 84) is provided in the second protruding portion 88.

[0060] With the above configuration, the axial dimension of the axial gap 60 near the grease drain hole 64 and the grease passage hole 68 can be made smaller between the cover 50 and the internal member 48 compared to when the second protrusion 88 is not provided. This makes it difficult for the lubricant 54 to leak into the axial gap 60 when draining grease through the grease drain hole 64 and the grease passage hole 68. Consequently, the lubricant 54 can be smoothly drained from the storage space 52.

[0061] To obtain a similar effect, the internal member 48 may be the second one member 84, and the cover 50 may be the second other member 86. In this case, the second protruding portion 88 is provided on the internal member 48 (second one member 84), and a part of the hole (grease passage hole 68) provided in the internal member 48 is provided in the second protruding portion 88. To obtain a similar effect, in addition to the second one member 84, the second other member 86 may be provided with another second protruding portion that protrudes toward the second one member 84. In this case, it is sufficient that a part of the grease drain hole 64 and the grease passage hole 68 that are provided in the second other member 86 is provided in the other second protruding portion 88.

[0062] Here, an example has been described in which the first one member 78 and the second one member 84 are covers 50. Alternatively, either the first one member 78 or the second one member 84 may be the internal member 48. For example, the first one member 78 may be the cover 50, the cover 50 may be provided with the first protrusion 82, and the second one member 84 may be the internal member 48, the internal member 48 may be provided with the second protrusion 88.

[0063] Next, a modified example of the above-described greasing method will be described. See FIG. 9 . When performing the above-described greasing process, greasing may be performed through the greasing hole 62 and the greasing hole 68 with a first cylindrical guide 90 disposed inside the greasing hole 62 and the greasing hole 68. The first cylindrical guide 90 is disposed so as to pass through the inside of each of the greasing hole 62 and the greasing hole 68. This allows the lubricant 54 to be guided from the greasing hole 62 to the greasing hole 68 through the inside of the first cylindrical guide 90. Therefore, when greasing is performed through the greasing hole 62 and the greasing hole 68, leakage of the lubricant 54 into the axial gap 60 can be prevented.

[0064] Furthermore, in performing a similar greasing process, grease may be drained through the grease drain hole 64 and the grease passage hole 68 with a second cylindrical guide 92 disposed inside the grease drain hole 64 and the grease passage hole 68. The second cylindrical guide 92 is disposed so as to pass through the inside of each of the grease supply hole 62 and the grease passage hole 68. This allows the lubricant 54 to be guided from the grease passage hole 68 to the grease drain hole 64 through the inside of the second cylindrical guide 92. Therefore, when draining grease through the grease drain hole 64 and the grease passage hole 68, leakage of the lubricant 54 into the axial gap 60 can be prevented.

[0065] Here, the case where both the first cylindrical guide 90 and the second cylindrical guide 92 are used in the greasing process has been described. Alternatively, only one of the first cylindrical guide 90 and the second cylindrical guide 92 may be used in the greasing process.

[0066] Other variations of each component will be described.

[0067] The reducer 18 is not limited to a planetary gear reducer, and other types may be adopted. The reducer 18 may be, for example, an eccentric oscillating reducer, a combination of an eccentric oscillating type and a planetary gear type, or a flexible mesh reducer. In the case of an eccentric oscillating reducer, the reduction unit 26 is, for example, an oscillating external gear. As the eccentric oscillating reducer, a center crank type in which the input shaft 24 (crankshaft) is arranged on the rotation center line CL1 has been described. Specific examples of eccentric oscillating reducers are not particularly limited. In addition to this, a distribution type in which multiple input shafts 24 (crankshafts) are arranged at positions offset from the rotation center line CL1 may also be used.

[0068] The example has been described in which the case 30 forms at least a part of the rotating body 38, and the carriers 28A and 28B form at least a part of the fixed body 40. Alternatively, the case 30 may form at least a part of the fixed body 40, and the carriers 28A and 28B may form at least a part of the rotating body 38. In this case, the wheel 20 only needs to be fixed to the carriers 28A and 28B that form the rotating body 38.

[0069] There are no particular limitations on the specific example of the wheel 20. The wheel 20 may be, for example, an omniwheel. In this case, the ground contact member 44 is formed by a roller whose center of rotation is along a tangent line passing through the outer circumferential surface of the wheel body 42. There are no particular limitations on the specific example of the ground contact member 44. The ground contact member 44 may be, for example, a tire.

[0070] In the above description, the wheel 20 is provided at a position where it overlaps the reduction unit 26 of the reducer 18 in the radial direction. However, the present invention is not limited to this, and the wheel 20 may be provided at a position where it does not overlap the reduction unit 26 in the radial direction. This assumes, for example, a case where the wheel 20 is disposed on the opposite side of the vehicle body from the reduction unit 26.

[0071] Although the example in which the cover 50 constitutes the rotating body 38 has been described, the cover 50 may also constitute the fixed body 40. The cover 50 may be connected to the case 30 or the like without being sandwiched between the wheel 20 and the case 30.

[0072] A specific example of the internal member 48 is not limited to the carrier 28B. The internal member 48 may be, for example, a member provided separately from the carrier 28B.

[0073] In the above description, the grease supply hole 62 and the grease drain hole 64 are provided in the cover 50. The grease supply hole 62 and the grease drain hole 64 may be provided in any suitable material, as long as the lubricant 54 can be supplied and drained through the grease supply hole 62 and the grease drain hole 64 while the reducer 18 is attached to the vehicle body 12. For example, the grease supply hole 62 and the grease drain hole 64 may be provided in the case 30. This is intended for the example embodiment, in which the lubricant 54 is supplied and drained while the wheel 20 is separated from the reducer 18. Furthermore, when the wheel 20 is provided at a position that does not overlap the case 30 in the radial direction, the lubricant 54 can be supplied and drained using the grease supply hole 62 and the grease drain hole 64 of the case 30, without separating the wheel 20 from the reducer 18. In either case, the grease hole 68 need not be provided in the carrier 28B.

[0074] There are no particular limitations on the relative positions in the circumferential direction of the grease supply hole 62 and the grease drain hole 64. For example, the grease drain hole 64 may be disposed at a position offset by an angle of 45° in the circumferential direction from the grease supply hole 62.

[0075] Although the example has been described in which the multiple grease holes 68 are provided separately in the internal member 48, they may be configured as a single hole provided in the internal member 48. Furthermore, the number of grease holes 68 is not particularly limited, and may be one or three or more.

[0076] To obtain the effect of (A), it is sufficient that the grease supply hole 62 and the grease passage hole 68 are at least partially arranged to overlap in the axial direction X, and the grease drain hole 64 and the other grease passage holes 68 do not have to be arranged to overlap in the axial direction X. Here, the "other grease passage holes 68" refer to grease passage holes 68 other than the grease supply hole 62 and the grease passage hole 68 arranged to overlap in the axial direction X.

[0077] To obtain the effect of (B), it is sufficient that the grease drain hole 64 and the grease passage hole 68 are arranged at positions where at least a part of them overlap in the axial direction X, and it is not necessary that the grease supply hole 62 and the other grease passage hole 68 are arranged at positions where they overlap in the axial direction X. Here, the “other grease passage hole 68” refers to a grease passage hole 68 other than the grease drain hole 64 and the grease passage hole 68 arranged at a position where they overlap in the axial direction X.

[0078] Unlike the embodiment, the above-described greasing method may also be used when new lubricant 54 is supplied into the reducer 18 in a situation where no lubricant 54 is present in the reducer 18. In the embodiment, an example has been described in which, when the cover 50 constitutes the rotating body 38, the phase of the rotating body 38 is changed so that the grease supply hole 62 is located on the lower side and the grease drain hole 64 is located on the upper side. Alternatively, the grease supply hole 62 may be located on the upper side and the grease drain hole 64 may be located on the lower side. In this case, grease may be supplied using the upper grease inlet hole 68 and grease supply hole 62, and grease may be drained using the lower grease inlet hole 68 and grease drain hole 64.

[0079] In the above description, the lubrication appropriate state S1 and the lubrication inappropriate state S2 are a combination of an overlapping state and a non-overlapping state. Specific examples of the lubrication appropriate state S1 and the lubrication inappropriate state S2 are not limited to these. For example, the lubrication appropriate state S1 may be a lubrication available state in which lubrication is possible using the lubrication hole 62, and the lubrication inappropriate state may be a lubrication inaccessible state in which lubrication is not possible using the lubrication hole 62. The lubrication available state is, for example, a state in which the lubrication hole 62 is not covered by another member when viewed from the axial direction X, and the lubrication hole 62 is accessible from the outside. The lubrication inaccessible state is, for example, a state in which the lubrication hole 62 is covered by another member when viewed from the axial direction X, and the lubrication hole 62 is inaccessible from the outside.

[0080] Although the example in which the fixed member 74 is the internal member 48 has been described, it may also be the cover 50. In this case, the phases of the grease supply holes 62 provided in the fixed member 74 (cover 50) among the grease passage holes 68 and the grease supply holes 62 of the multiple wheel drive devices 14 may be aligned.

[0081] The above-described embodiments and modifications are merely examples. The abstract technical ideas should not be interpreted as being limited to the contents of the embodiments and modifications. Many design modifications are possible in the contents of the embodiments and modifications, such as changing, adding, or deleting components. In the above-described embodiments, the contents that allow such design modifications are emphasized by adding the notation "embodiment." However, design modifications are also permitted even in contents that do not have such notation. Hatching on cross sections in the drawings does not limit the material of the hatched objects. [Explanation of symbols]

[0082] 10...vehicle, 12...vehicle body, 14...wheel drive device, 16...drive source, 18...reduction gear, 20...wheel, 26...reduction section, 26A, 26B...carrier, 30...case, 38...rotating body, 40...fixed body, 48...internal member, 50...cover, 54...lubricant, 62...grease supply hole, 64...grease drain hole, 68...grease passage hole, 74...fixed member.

Claims

1. A driving source; a reducer that reduces the speed of the power input from the drive source and outputs the reduced speed, A wheel drive device that drives a wheel by an output of the reducer, the reducer includes a speed reducer unit that reduces the speed of power input from the drive source, a grease supply port and a grease drain port, a case, and a carrier that is disposed inside the case and is rotatable relative to the case, the carrier is disposed axially to the side of the reduction gear portion and constitutes an internal member provided with a grease passage hole through which a lubricant can pass; the grease hole is located at a position offset in a radial direction with respect to a rotational center line of the wheel, the wheel is fixed to one of the case and the carrier; This wheel drive device is configured so that lubricant can be supplied to and drained from the reduction unit through the grease supply hole, grease drain hole, and grease passage hole radially inward of the wheel, while the reducer to which the wheel is fixed remains attached to the vehicle body.

2. the reducer includes a cover that covers the internal member and in which the grease supply hole is provided, the cover and the carrier are disposed inside the wheel; The wheel drive device according to claim 1 , wherein at least a portion of the oil supply hole and the oil vent hole are provided so as to overlap in the axial direction by rotating the cover and the internal member relative to each other.

3. When one of the cover and the internal member is referred to as a "one member" and the other is referred to as a "other member," the one member includes a protruding portion that protrudes toward the other member, The wheel drive device according to claim 2 , wherein the protruding portion is provided with a part of the oil supply hole and the oil vent hole that are provided in the one member.

4. the reducer includes the carrier that supports the reduction unit, 4. The wheel drive device according to claim 2, wherein the cover is integrated with the case.

5. the cover covers the carrier from an axially outer side, the grease supply hole axially penetrates the cover, The wheel drive device according to claim 4 , wherein the grease hole passes through the carrier in the axial direction.

6. the wheel is coupled to the case so as to be rotatable integrally with the case; 6. The wheel drive device according to claim 4, wherein the wheel, the cover, and the case are axially connected with the cover sandwiched between the wheel and the case.

7. the reducer includes a cover that covers the internal member and in which the grease drain hole is provided, The wheel drive device according to claim 1 , wherein at least a portion of the grease drain hole and the grease passage hole are arranged to overlap in the axial direction by rotating the cover and the internal member relative to each other.

8. The wheel drive device according to any one of claims 1 to 7, wherein the wheel is a Mecanum wheel.

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