Wheel drive

Abstract

The object of the present invention is to provide a wheel drive device capable of increasing the permissible radial load. A wheel drive device (100) according to one embodiment of the present invention comprises an internal gear (16) integrated with a housing, an external gear (14), an eccentric body (12a) for causing the external gear (14) to swing, an output flange (18) arranged on the axial side of the external gear (14), a pin member supported by the output flange (18) and penetrating the external gear (14), and a first main bearing (24) arranged between the output flange (18) and the housing, wherein a wheel (50) is connected to the output flange (18), and the inner diameter of the inner ring of the first main bearing (24) is larger than the inscribed circle diameter of the pin member.

Description

[0001] This application claims priority based on Japanese Patent Application No. 2020-035002 filed on March 2, 2020. The entire contents of the Japanese Patent Application are incorporated herein by reference. Technical Field

[0002] The invention relates to a wheel driving device. Background Art

[0003] A driving device for driving a wheel by a motor and a reduction mechanism is known. For example, Patent Document 1 describes a wheel driving device for driving a wheel hub by reducing the rotation of a motor and transmitting it to an output shaft. The device includes a motor unit, a reduction unit, and a wheel hub bearing unit. The reduction unit includes a housing side component, an output shaft inserted into the housing side component, and a bearing provided on the housing side component to support the output shaft.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2011-117577

[0005] For example, in a transport cart, a drive device including a reduction mechanism is mounted in order to drive the wheels of the cart. In the cart, the weight of the cart and the weight of the transported object directly act on the output component of the reduction mechanism connected to the wheels, so the weight that can be transported is limited based on the allowable radial load of the reduction mechanism. From the viewpoint of improving durability, it is desired that the allowable radial load of the reduction mechanism of the cart is larger. However, in the wheel drive device described in Patent Document 1, the allowable radial load of the reduction mechanism is not taken into consideration. This problem is not limited to transport carts, but may also occur in other types of wheel drive devices. Summary of the invention

[0006] The present invention has been made in view of such a problem, and an object of the present invention is to provide a wheel drive device capable of increasing the permissible radial load.

[0007] In order to solve the above-mentioned problems, a wheel drive device in one embodiment of the present invention comprises an internal gear integrated with a housing, an external gear, an eccentric body that causes the external gear to swing, an output flange arranged on the axial side of the external gear, a pin component supported by the output flange and passing through the external gear, and a first main bearing arranged between the output flange and the housing, wherein the wheel is connected to the output flange, and the inner diameter of the inner ring of the first main bearing is larger than the diameter of the inscribed circle of the pin component.

[0008] In addition, any combination of the above-mentioned constituent elements or any form of expression of the present invention in the form of a method, a system, or the like may also be practiced as additional embodiments of the present invention.

[0009] According to the present invention, there is provided a wheel drive device capable of increasing the permissible radial load. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a side cross-sectional view showing the wheel drive device according to the first embodiment.

[0011] Figure 2 It is used to illustrate Figure 1 Diagram of the output flange and wheel carrier of the wheel drive device.

[0012] Figure 3 It indicates schematically Figure 1 Diagram of the configuration of the main bearings of a wheel drive unit.

[0013] Figure 4 It is a side cross-sectional view showing a wheel drive device according to a second embodiment.

[0014] Figure 5 It is used to illustrate Figure 4 Diagram of the output flange and wheel carrier of the wheel drive device.

[0015] Figure 6 It indicates schematically Figure 4 Diagram of the configuration of the main bearings of a wheel drive unit.

[0016] In the figure: 12-input shaft, 12a-eccentric body, 14-external gear, 16-internal gear, 18-output flange, 20-wheel carrier, 21, 22, 23-housing, 24-first main bearing, 24n-inner ring, 26-second main bearing, 26n-inner ring, 32, 33-pin components, 50-wheel, 100, 200-wheel drive device. DETAILED DESCRIPTION

[0017] Hereinafter, the preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the embodiments and the modified examples, the same or equivalent components and parts are marked with the same symbols, and repeated descriptions are appropriately omitted. In addition, in order to facilitate understanding, the size of the components is appropriately enlarged or reduced in each of the drawings. In addition, in each of the drawings, a part of the components that are not important for the description of the embodiments is omitted.

[0018] Furthermore, terms including numbers such as 1 and 2 are used to describe a plurality of constituent elements, but such terms are only used to distinguish one constituent element from other constituent elements, and such terms are not used to limit the constituent elements.

[0019] [First embodiment]

[0020] Below, reference Figure 1 , the structure of the wheel drive device 100 according to the first embodiment of the present invention will be described. Figure 1It is a side cross-sectional view schematically showing the wheel drive device 100 according to the present embodiment.

[0021] The wheel drive device 100 is a drive device for driving the wheels of an unmanned transport vehicle or the like that carries a transport object on a trolley and transports the object. In addition, the wheel drive device 100 is not limited to the unmanned transport vehicle, and can be applied to wheel drive devices of various vehicles. The wheel drive device 100 decelerates the rotation input from the motor 40 and then drives the wheel 50 to rotate. In the wheel drive device 100, the wheel 50 is connected to the output flange 18.

[0022] Hereinafter, the direction along the central axis La of the output flange 18 is referred to as the "axial direction", and the circumferential direction and the radial direction of a circle with the central axis La as the center are referred to as the "circumferential direction" and the "radial direction", respectively. Also, hereinafter, for the sake of convenience, one side in the axial direction (the right side in the figure) is referred to as the input side, and the other side in the circumferential direction (the left side in the figure) is referred to as the opposite input side. The motor 40 is arranged on the input side of the wheel drive device 100, and the wheel 50 is arranged on the opposite input side of the wheel drive device 100.

[0023] The wheel drive device 100 mainly includes: an input shaft 12; an external gear 14; an internal gear 16; an output flange 18; a wheel carrier 20; housings 21, 22, 23; main bearings 24, 26; pin members 32, 33; and a wheel 50. This embodiment includes a center crank type reduction mechanism in which the input shaft 12 is arranged on the same axis as the center axis of the internal gear 16.

[0024] The housings 21, 22, and 23 are hollow cylindrical components surrounding the output flange 18 and the wheel carrier 20, and constitute the housing of the reduction mechanism. Figure 1 In the example, the housings 21 , 22 , and 23 include a first housing 21 provided on the opposite side to the input, a third housing 23 provided on the input side, and a second housing 22 provided between the first housing 21 and the third housing 23 .

[0025] The main bearings 24 and 26 include a first main bearing 24 disposed on the side opposite to the input side of the external gear 14 and a second main bearing 26 disposed on the side on the input side of the external gear 14. The output flange 18 and the wheel carrier 20 are disposed inside the housings 21, 22, and 23, and rotate relative to the housings 21, 22, and 23. The input shaft 12 is connected to the motor shaft 42 of the motor 40 through a cylindrical connecting member 44, thereby transmitting the rotation of the motor 40.

[0026] The internal gear 16 is integrated with the second housing 22. The external gear 14 meshes with the internal gear 16. The eccentric body 12a of the input shaft 12 causes the external gear 14 to swing. The output flange 18 is arranged on the side opposite to the input side of the external gear 14 in the axial direction and is synchronized with the rotation component of the external gear 14. The wheel carrier 20 is arranged on the side on the input side of the external gear 14. The pin components 32 and 33 are supported by the output flange 18 and the wheel carrier 20 and penetrate the external gear 14. The pin components 32 and 33 connect the output flange 18 and the wheel carrier 20 together. The first main bearing 24 is arranged between the output flange 18 and the first housing 21. The second main bearing 26 is arranged between the wheel carrier 20 and the third housing 23. The wheel 50 is connected to the output flange. The following is a detailed description.

[0027] The input shaft 12 functions as a crankshaft having a plurality of eccentric bodies 12a for swinging the external gear 14. In this example, the input shaft 12 has two eccentric bodies 12a that are 180 degrees out of phase with each other. Both ends of the input shaft 12 are supported by the output flange 18 and the wheel carrier 20 via a pair of input shaft bearings 34, 34, respectively.

[0028] The external gear 14 is rotatably supported by the input shaft 12 via an eccentric bearing 30. A plurality of pin insertion holes 14j and 14h are formed at positions offset from the axis of the external gear 14. Pin members 32 and 33 are inserted into the pin insertion holes 14j and 14h. The external teeth formed on the outer periphery of the external gear 14 mesh with the internal teeth of the internal gear 16 and rotate, thereby causing the external gear 14 to swing.

[0029] The internal gear 16 has internal teeth meshing with the external gear 14, and is a component that rotates relative to the external gear 14 according to the swinging rotation of the external gear 14. The internal teeth of the present embodiment have external pins 16a arranged in pin grooves (not shown) formed in the inner peripheral portion of the housing 22. In the present embodiment, the number of external pins 16a (the number of internal teeth) of the internal gear 16 is one more than the number of external teeth of the external gear 14.

[0030] The output flange 18 and the wheel carrier 20 are rotatably supported by the housings 21, 22, and 23 via the first main bearing 24 and the second main bearing 26. The output flange 18 and the wheel carrier 20 support the input shaft 12 via the input shaft bearing 34. The output flange 18 and the wheel carrier 20 are separately arranged on the input side and the input side of the external gear 14 and are connected together via pin members 32 and 33. The pin members 32 and 33 penetrate the pin through holes 14j and 14h of the external gear 14 in the axial direction at positions radially offset from the axis of the external gear 14. In this example, the pin members 32 and 33 are cylindrical members.

[0031] One of the output flange 18 and the housing 21, 22, 23 functions as an output member that outputs rotational power to the wheel, and the other functions as a fixed member fixed to an external member that supports the wheel drive device 100. In the present embodiment, the output member is the output flange 18, and the fixed member is the housing 21, 22, 23.

[0032] Next, refer to Figure 1 and Figure 2 , the output flange 18 and the wheel carrier 20 are described. Figure 2 1 is a diagram for explaining the output flange 18 and the wheel carrier 20. Figure 2 The cross-sectional view itself is Figure 1 Same as Figure 1 Different. The output flange 18 has a fitting portion 18s that fits with the inner ring 24n of the first main bearing 24, and a large diameter portion 18f having a diameter larger than that of the fitting portion 18s. A plurality of pin hole portions 18h and 18j that penetrate in the axial direction are provided in the large diameter portion 18f. The pin hole portions 18h are provided at prescribed intervals in the circumferential direction on the same circle, and the pin component 32 is embedded and supported therein. The pin component 32 may also be loosely fitted in the pin hole portion 18h so as to be supported to rotate. The pin hole portions 18j are provided at prescribed intervals in the circumferential direction on the same circle, and the pin component 33 is embedded and supported therein. The pin component 33 may also be fixed to the pin hole portion 18j by pressing in, etc. In Figure 2 In the example of , the end portion (end face) of the large diameter portion 18f on the opposite side to the input is axially opposed to the first main bearing 24. The end portion (end face) of the large diameter portion 18f on the input side is axially opposed to the external gear 14.

[0033] The wheel frame 20 has a fitting portion 20s that fits with the second main bearing 26 and a large diameter portion 20f having a diameter larger than that of the fitting portion 20s. The large diameter portion 20f is provided with a plurality of pin hole portions 20h and 20j that penetrate in the axial direction. The pin hole portions 20h are provided at predetermined intervals in the circumferential direction on the same circumference, and the pin component 32 is embedded and supported therein. The pin component 32 can also be loosely fitted in the pin hole portion 20h so as to be supported to be rotatable. The pin hole portions 20j are provided at predetermined intervals in the circumferential direction on the same circumference, and the pin component 33 is embedded and supported therein. The end portion (end face) on the input side of the large diameter portion 20f is axially opposed to the second main bearing 26. The end portion (end face) on the opposite side of the input of the large diameter portion 20f is axially opposed to the external gear 14.

[0034] like Figure 1As shown, the main bearings 24 and 26 are arranged between the output flange 18 and the housing 21 and between the wheel carrier 20 and the housing 23. In this example, the main bearings 24 and 26 have inner rings 24n and 26n, outer rings 24m and 26m, and spherical rolling elements. The outer rings 24m and 26m of the main bearings 24 and 26 are supported by the housings 21 and 23. The inner rings 24n and 26n of the main bearings 24 and 26 are supported by the output flange 18 and the wheel carrier 20.

[0035] The pin member 32 is an inner pin that transmits the rotation component of the external gear to the output flange. In this example, six pin members 32 are arranged at intervals of 60 degrees in the circumferential direction. Figure 1 Only one pin member 32 is shown in the figure. The opposite side of the input of the pin member 32 is supported by the output flange 18, and the input side is supported by the wheel frame 20. The pin member 32 abuts against a portion of the pin through hole 14h. The pin member 32 restricts the rotation of the external gear 14 and only allows it to swing. In addition, the number of pin members 32 is not limited to six, as long as a plurality of them are provided.

[0036] The pin member 33 is a carrier pin that does not participate in the transmission of the rotation component of the external gear 14 but only connects the output flange 18 and the carrier 20. In this example, three pin members 33 are arranged at intervals of 120 degrees in the circumferential direction. Figure 1 Only one pin member 33 is shown in the figure. The opposite side of the input of the pin member 33 is supported by the output flange 18, and the input side is supported by the wheel frame 20. A spacer 33s is provided on the outer periphery of the pin member 33. The spacer 33s is a cylindrical member that maintains a predetermined interval between the output flange 18 and the wheel frame 20. The pin member 33 and the spacer 33s are inserted into the pin through hole 14j with a gap therebetween. In addition, the number of the pin members 33 is not limited to three, and may be two, or may be four or more.

[0037] The motor 40 may be a motor based on various principles as long as it can input a rotational driving force to the wheel drive device 100. In this example, the motor 40 is a servo motor. The motor 40 includes a motor flange 40f having a bolt hole 40h. The motor flange 40f of the motor 40 is fixed to the input side end surface of the third housing 23 by a bolt B5.

[0038] The housings 21, 22, and 23 have bolt holes 21h, 22h, and 23h extending therethrough in the axial direction, respectively. A plurality of the bolt holes 21h, 22h, and 23h are provided at predetermined intervals in the circumferential direction. Figure 1As shown, the bolt B2 passes through the bolt holes 21h and 22h and is screwed into the bolt hole 23h, thereby integrating the housings 21, 22, and 23. The second housing 22 is fixed to the first housing 21 by the bolt B3. The third housing 23 has a housing flange 23f protruding radially outward. The housing flange 23f is provided with a flange hole 23j penetrating in the axial direction. The housing flange 23f is connected to an external component.

[0039] Next, the wheel 50 will be described. The wheel 50 includes a wheel hub 52 and a tire 54 disposed on the outer periphery of the wheel hub 52. The wheel hub 52 has a disc-shaped disc portion 52b and a hollow cylindrical rim portion 52s disposed on the outer periphery of the disc portion 52b. A plurality of bolt holes 52h are provided along the circumferential direction at a position offset from the center of the disc portion 52b. The wheel 50 is fixed to the output flange 18 by bolts B4 passing through the bolt holes 52h. The tire 54 may be made of metal or non-metal such as resin. The tire 54 of the present embodiment is made of rubber.

[0040] In this embodiment, the axial center Mw of the wheel 50 is closer to the first main bearing 24 than the second main bearing 26. The axial center Mw is located on a straight line that bisects the wheel 50 in the axial direction. At this time, the proportion of the wheel load supported by the first main bearing 24 becomes larger, and the proportion of the wheel load applied to the second main bearing 26 becomes relatively smaller, so a bearing with lower load resistance performance can be used as the second main bearing 26. Figure 1 In the example of , the rim portion 52s has a rim width that substantially surrounds the pin members 32 and 33 of the wheel drive device 100. At this time, the wheel drive device 100 is substantially accommodated in the wheel 50, so the overall axial dimension becomes correspondingly smaller.

[0041] Next, refer to Figure 3 , the characteristic structure of this embodiment is described. Figure 3 2 is a diagram schematically showing the arrangement of the main bearings 24 and 26 of the wheel drive device 100. Figure 3 As shown, the inner diameter (diameter) Dn24 of the inner ring 24n of the first main bearing 24 is larger than the inscribed circle diameter (diameter) J32, J33 of the pin members 32, 33. In addition, the inscribed circle diameter (diameter) can also be expressed as twice the shortest distance from the axis of the output flange 18 to the pin member 32 or the pin member 33. In this structure, the inner diameter Dn24 is large, so a large bearing with high load resistance can be used as the first main bearing 24. As a result, the load resistance of the output flange 18 on the side connected to the wheel 50 is improved, so the durability of the wheel drive device 100 is improved. Since the load resistance is improved, the load that can be loaded on the wheel drive device 100 becomes larger, and the device can be miniaturized accordingly.

[0042] like Figure 3 As shown, the inner diameter Dn24 of the inner ring 24n of the first main bearing 24 is smaller than the circumscribed circle diameters G32 and G33 of the pin members 32 and 33 .

[0043] In the present embodiment, the pin member 32 is an inner pin that transmits the rotation component of the external gear 14 to the output flange 18. At this time, since the inner diameter Dn24 of the first main bearing 24 is larger than the inscribed circle diameter of the inner pin, the diameter of the fitting portion 18s of the output flange 18 that fits with the inner ring 24n can be increased in the vicinity thereof, thereby improving the load resistance performance of the fitting portion 18s.

[0044] In the present embodiment, the pin member 33 is a wheel carrier pin that does not participate in the transmission of the self-rotation component of the external gear 14 but only connects the output flange 18 and the wheel carrier 20. At this time, the inner diameter Dn24 of the inner ring 24n of the first main bearing 24 is larger than the inscribed circle diameter of the wheel carrier pin, so the diameter of the fitting portion 18s of the output flange 18 that fits with the inner ring 24n can be increased in the vicinity thereof, thereby improving the load resistance performance of the fitting portion 18s.

[0045] In this embodiment, the inner diameter (diameter) Dn26 of the inner ring 26n of the second main bearing 26 is smaller than the inscribed circle diameters J32 and J33 of the pin members 32 and 33. Since the inner diameter Dn26 is small, a lightweight small bearing can be used as the second main bearing 26.

[0046] In this embodiment, the inner ring 24n of the first main bearing 24 is opposed to the pin members 32 and 33 in the axial direction, thereby restricting the axial movement of the pin members 32 and 33. In this case, since the movement of the pin members 32 and 33 can be restricted by the inner ring 24n, a structure without providing other members for restricting the movement can also be selected. In addition, the inner ring 24n of the first main bearing 24 and the pin members 32 and 33 may be opposed to each other in the axial direction with a spacer or the like interposed therebetween.

[0047] Next, the operation of the wheel drive device 100 described above will be described. When the rotation is transmitted from the motor 40 to the input shaft 12, the eccentric body 12a of the input shaft 12 rotates around the rotation center line passing through the input shaft 12, thereby causing the external gear 14 to oscillate. When the external gear 14 oscillates, the meshing positions of the external gear 14 and the internal gear 16 are sequentially shifted. As a result, for each rotation of the input shaft 12, the self-rotation of one of the external gear 14 and the internal gear 16 is equal to the difference in the number of teeth between the external gear 14 and the internal gear 16. In the present embodiment, the external gear 14 rotates, and the self-rotation component is transmitted to the output flange 18 via the pin member 32, and the decelerated rotation is output from the output flange 18. By rotating the output flange 18, the wheel 50 connected to the output flange 18 rotates. The above is the description of the first embodiment.

[0048] [Second embodiment]

[0049] Below, reference Figure 4 and Figure 5 , the structure of the wheel drive device 200 according to the second embodiment of the present invention will be described. Figure 4 It is a side cross-sectional view schematically showing the wheel drive device 200 according to the present embodiment. Figure 5 1 is a diagram for explaining the output flange 18 and the wheel carrier 20. Figure 5 The cross-sectional view itself is Figure 4 Same, indicating the symbol marked with Figure 4 different.

[0050] The second embodiment differs from the first embodiment in that the relationship between the inner diameter Dn24 of the inner ring 24n of the first main bearing 24 and the diameter of the inscribed circle of the pin members 32 and 33 is different, and the inner diameter Dn26 of the inner ring 26n of the second main bearing 26 is relatively large, and the other structures are the same as the first embodiment. Here, repeated descriptions are omitted, and the differences are mainly described. In this example, the inner diameter Dn26 is substantially equal to the inner diameter Dn24 of the inner ring 24n of the first main bearing 24. The second main bearing 26 can be the same bearing as the first main bearing 24.

[0051] Next, refer to Figure 6 , the characteristic structure of this embodiment is described. Figure 6 It is a diagram schematically showing the arrangement of main bearings 24 and 26 of the wheel drive device 200 .

[0052] like Figure 6 As shown, in this embodiment, the inner diameter Dn24 of the inner ring 24n of the first main bearing 24 is smaller than the inscribed circle diameter J32 of the pin member 32 (inner pin) and larger than the inscribed circle diameter J33 of the pin member 33 (carrier pin). At this time, since the inner diameter Dn24 is larger than the inscribed circle diameter of the carrier pin, the diameter of the fitting portion 18s of the output flange 18 can be increased in the vicinity thereof, thereby improving the load resistance performance of the fitting portion 18s.

[0053] In this embodiment, the inner diameter Dn26 of the inner ring 26n of the second main bearing 26 is smaller than the inscribed circle diameter J32 of the pin member 32. At this time, since the inner diameter Dn26 is small, a lightweight small bearing can be used as the second main bearing 26.

[0054] In this embodiment, the inner ring 24n of the first main bearing 24 is axially opposed to the pin members 32 and 33, thereby restricting the axial movement of the pin members 32 and 33. At this time, since the movement of the pin members 32 and 33 can be restricted by the inner ring 24n, a structure without providing other members for restricting the movement can also be selected.

[0055] The second embodiment operates in the same manner as the first embodiment, and exhibits the same operational effects as the first embodiment. The above is the description of the second embodiment.

[0056] The examples of the embodiments of the present invention are described in detail above. The above embodiments are only specific examples of the present invention. The contents of the embodiments are not intended to limit the technical scope of the present invention. Various design changes such as changes, additions, and deletions of constituent elements may be made without departing from the scope of the inventive concept specified in the technical solution. In the above embodiments, the contents that can be subjected to design changes are described by adding expressions such as "embodiment mode" and "in the embodiment mode", but this does not mean that design changes are not allowed without such expressions. In addition, the hatching marked on the cross-section of the accompanying drawings is not used to limit the material of the object marked with the hatching.

[0057] In the drawings and description of the modified examples, the same reference numerals are used for the same or equivalent components and parts as those in the embodiment. The descriptions that overlap with the embodiment are appropriately omitted, and the description focuses on the structures that are different from the embodiment.

[0058] [Modifications]

[0059] In the description of the embodiment, an example in which the inner pin and the carrier pin are provided as the pin member is shown, but the provision of the carrier pin is not essential, and the carrier pin may not be provided.

[0060] In the description of the embodiment, an example is shown in which the pin member 33 (carrier pin) is formed separately from the output flange 18 and the carrier 20 and connected to the output flange 18 and the carrier 20, but the carrier pin may be formed integrally with the output flange or the carrier.

[0061] In the description of the embodiment, an example is shown in which the pin member 32 (inner pin) is supported to be rotatable relative to the output flange 18 and the wheel carrier 20, but the present invention is not limited to this. For example, the inner pin may be fixed to at least one of the output flange 18 and the wheel carrier 20, or may be formed integrally with the output flange or the wheel carrier. In this case, a rotatable sleeve may be provided on the outer periphery of the inner pin.

[0062] In the description of the embodiment, an example is shown in which the housing is composed of three members (housings 21, 22, and 23), but the housing may be composed of two or less or four or more members.

[0063] In the description of the embodiment, an example is shown in which the housing flange 23 f for connecting to an external member is provided on the third housing 23 , but the housing flange may be provided on a member different from the third housing 23 , such as the first housing 21 or the second housing 22 .

[0064] In the description of the embodiment, an example is shown in which the reduction mechanism of the wheel drive device 100 is an eccentric swing type reduction machine of a center crank type, but the present invention is not limited to this. The reduction mechanism of the wheel drive device only needs to have an output flange, a pin component and a main bearing and be able to reduce the input rotation. For example, a so-called distributed eccentric swing type reduction machine, a simple planetary gear type reduction machine, etc., in which a crankshaft is provided at a position offset from the center axis, can be used. In addition, when a distributed eccentric swing type reduction machine or a simple planetary gear type reduction machine is used, it is not necessary to provide an inner pin and only a wheel carrier pin can be provided.

[0065] In the description of the embodiment, an example in which the rolling element of each bearing is a spherical body is shown, but as each bearing, a bearing having a rolling element of various shapes known in the art can be used.

[0066] The above-mentioned modifications achieve the same effects as those of the embodiment.

[0067] Any combination of the constituent elements and modifications of the above-described embodiments is also effective as an embodiment of the present invention. A new embodiment generated by the combination has the effects of the combined embodiments and modifications.

Claims

1. A wheel drive device comprising an internal gear integrated with a housing, an external gear, an eccentric body for causing the external gear to swing, an output flange arranged on a side portion of the external gear in an axial direction, a pin member supported by the output flange and penetrating the external gear, and a first main bearing arranged between the output flange and the housing, wherein: The wheel is connected to the output flange, and the wheel drive device is characterized in that: The wheel drive device includes a wheel carrier, and the wheel carrier is arranged on the side opposite to the output flange in the axial direction of the external gear. The pin member comprises: a carrier pin which does not participate in the transmission of the self-rotation component of the external gear but only connects the output flange and the carrier; and an inner pin which transmits the self-rotation component of the external gear to the output flange. The inner diameter of the inner ring of the first main bearing is larger than the inscribed circle diameter of the wheel carrier pin and smaller than the inscribed circle diameter of the inner pin. The inner ring of the first main bearing is opposed to the inner pin and the carrier pin in the axial direction, so that the inner pin and the carrier pin can be restricted from moving in the axial direction.

2. A wheel drive device comprising an internal gear integrated with a housing, an external gear, an eccentric body for causing the external gear to swing, an output flange arranged on the axial side of the external gear, a pin member supported by the output flange and penetrating the external gear, and a first main bearing arranged between the output flange and the housing, wherein: The wheel is connected to the output flange, and the wheel drive device is characterized in that: The inner diameter of the inner ring of the first main bearing is larger than the inscribed circle diameter of the pin member. The wheel drive device further comprises: a wheel carrier arranged on the side opposite to the output flange in the axial direction of the external gear; and a second main bearing arranged between the wheel carrier and the housing. The inner diameter of the inner ring of the second main bearing is smaller than the inscribed circle diameter of the pin member. The axial center of the wheel is closer to the first main bearing than to the second main bearing.

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