Omnidirectional wheel

Abstract

The omnidirectional wheel (1) includes: a rotating part (30) whose outer peripheral surface is formed by a plurality of rollers (40, 50) and rotates around a rotation axis; and a plurality of support parts (60) arranged along the circumferential direction of the rotating part (30) and respectively mounted on the rotating part (30) to support the rollers (40, 50) on the rotating part (30). The rollers (40, 50) include a plurality of first rollers (40) and a plurality of second rollers (50), and the first rollers (40) and the second rollers (50) are alternately arranged along the circumferential direction. Each support part (60) has: a first arm (70) that supports the axial one end side of the corresponding first roller (40) among the plurality of first rollers (40); and a second arm (80) that supports the axial other end side of the corresponding first roller (40). The corresponding second roller (50) among the plurality of second rollers (50) is supported by the first arm (70) of one of the two support parts (60) adjacent in the circumferential direction and the second arm (80) of the other one.

Description

[0001] This application is a divisional application of Patent Application No. 202080031883.6, with the filing date of October 23, 2020 and the invention title of "Omnidirectional Wheel". Technical Field

[0002] The present invention relates to an omnidirectional wheel. Background Art

[0003] As such an omnidirectional wheel, there is known an omnidirectional wheel having: a drive shaft; a disk-shaped member rotatably supported by the drive shaft; a plurality of support members mounted on the outer peripheral portion of the disk-shaped member at intervals along the circumferential direction; small-diameter rollers respectively supported by the plurality of support members so as to be rotatable; and a plurality of large-diameter rollers respectively supported by two support members adjacent to each other along the circumferential direction. For example, such an omnidirectional wheel is disclosed in Patent Document 1.

[0004] Patent Document 1: Japanese Patent No. 3421290

[0005] The outer peripheral surface of the omnidirectional wheel is formed by a plurality of rollers. Therefore, it is difficult to achieve both firm support of each roller and weight reduction of the omnidirectional wheel at a high level. For example, when an omnidirectional wheel is used in an electric mobile device for one person to sit and ride, sometimes each roller receives a force of more than 300 N, and sometimes each roller receives a force of more than 500 N. In addition, such an electric mobile device is used daily for a long time. Therefore, if the support members are as weak as those shown in Patent Document 1, the support positions of the rollers change, or each support member is deformed or damaged, and the performance of the omnidirectional wheel is significantly reduced. Summary of the Invention

[0006] In view of the above circumstances, there is a need for an omnidirectional wheel that can achieve both an increase in the force borne by each roller and weight reduction at a high level.

[0007] An omnidirectional wheel according to a first aspect of the present invention has an outer peripheral surface formed by a plurality of rollers and rotates about an axle rotation axis, wherein the omnidirectional wheel includes: a rotating portion that rotates about the axle rotation axis; and a plurality of support portions that are arranged along the circumferential direction of the rotating portion and are respectively mounted on the rotating portion to support the plurality of rollers on the rotating portion. The plurality of rollers include a plurality of small-diameter rollers and a plurality of large-diameter rollers, the outer diameter of the large-diameter rollers being larger than the outer diameter of the small-diameter rollers, and the small-diameter rollers and the large-diameter rollers being alternately arranged along the circumferential direction. Each of the support portions has a first arm and a second arm. The first arm supports one axial end side of a corresponding small-diameter roller among the plurality of small-diameter rollers, and the second arm supports the other axial end side of the corresponding small-diameter roller. The corresponding large-diameter roller among the plurality of large-diameter rollers is supported by the first arm of one of the two support portions adjacent to each other along the circumferential direction and the second arm of the other. In the first arm, the large-diameter roller support portion that supports the corresponding large-diameter roller is arranged closer to the inner side in the radial direction of the rotating portion than the small-diameter roller support portion that supports the one axial end side of the corresponding small-diameter roller. In at least one of the plurality of rollers, a hole extending from the outer peripheral surface to the inner peripheral surface is formed.

[0008] An omnidirectional wheel according to a second aspect of the present invention has an outer peripheral surface formed by a plurality of rollers and rotates about an axle rotation axis, wherein the omnidirectional wheel includes: a rotating portion that rotates about the axle rotation axis; and a plurality of support portions that are arranged along the circumferential direction of the rotating portion and are respectively mounted on the rotating portion to support the plurality of rollers on the rotating portion. The plurality of rollers include a plurality of small-diameter rollers and a plurality of large-diameter rollers, the outer diameter of the large-diameter rollers being larger than the outer diameter of the small-diameter rollers, and the small-diameter rollers and the large-diameter rollers being alternately arranged along the circumferential direction. Each of the support portions has a first arm and a second arm. The first arm supports one axial end side of a corresponding small-diameter roller among the plurality of small-diameter rollers, and the second arm supports the other axial end side of the corresponding small-diameter roller. The corresponding large-diameter roller among the plurality of large-diameter rollers is supported by the first arm of one of the two support portions adjacent to each other along the circumferential direction and the second arm of the other. In the first arm, the large-diameter roller support portion that supports the corresponding large-diameter roller is arranged closer to the inner side in the radial direction of the rotating portion than the small-diameter roller support portion that supports the one axial end side of the corresponding small-diameter roller. The first arm has a connecting portion that connects the large-diameter roller support portion and the small-diameter roller support portion, and the direction in which the connecting portion of the first arm extends forms an angle of 20° or less with the direction in which the rotation axis of the corresponding large-diameter roller extends.

[0009] An omnidirectional wheel according to a third aspect of the present invention has an outer peripheral surface formed by a plurality of rollers and rotates about an axle rotation axis, wherein the omnidirectional wheel includes: a rotating portion that rotates about the axle rotation axis; and a plurality of support portions that are arranged along the circumferential direction of the rotating portion and are respectively mounted on the rotating portion to support the plurality of rollers on the rotating portion. The plurality of rollers include a plurality of small-diameter rollers and a plurality of large-diameter rollers, the outer diameter of the large-diameter rollers being larger than the outer diameter of the small-diameter rollers, and the small-diameter rollers and the large-diameter rollers being alternately arranged along the circumferential direction. Each of the support portions has a first arm and a second arm. The first arm supports one axial end side of a corresponding small-diameter roller among the plurality of small-diameter rollers, and the second arm supports the other axial end side of the corresponding small-diameter roller. A corresponding large-diameter roller among the plurality of large-diameter rollers is supported by the first arm of one of two support portions adjacent to each other along the circumferential direction and the second arm of the other. In the first arm, a large-diameter roller support portion that supports the corresponding large-diameter roller is arranged closer to the radially inner side of the rotating portion than a small-diameter roller support portion that supports the one axial end side of the corresponding small-diameter roller. The first arm has a proximal-side portion that mainly extends along the axial direction of the corresponding small-diameter roller, and the proximal-side portion connects a mounted portion mounted on the rotating portion to the large-diameter roller support portion. A part of the radially inner surface of the proximal-side portion faces the inner peripheral surface of the corresponding large-diameter roller, and a central portion in the wheel width direction of the part of the inner surface bulges toward the radially inner side.

[0010] An omnidirectional wheel according to a fourth aspect of the present invention has an outer peripheral surface formed by a plurality of rollers and rotates about an axle rotation axis, wherein the omnidirectional wheel includes: a rotating portion that rotates about the axle rotation axis; and a plurality of support portions arranged along the circumferential direction of the rotating portion and respectively mounted on the rotating portion to support the plurality of rollers on the rotating portion. The plurality of rollers include a plurality of small-diameter rollers and a plurality of large-diameter rollers, the outer diameter of the large-diameter rollers being larger than the outer diameter of the small-diameter rollers, and the small-diameter rollers and the large-diameter rollers being alternately arranged along the circumferential direction. Each of the support portions has a first arm and a second arm. The first arm supports one axial end side of a corresponding small-diameter roller among the plurality of small-diameter rollers, and the second arm supports the other axial end side of the corresponding small-diameter roller. A corresponding large-diameter roller among the plurality of large-diameter rollers is supported by the first arm of one of two adjacent support portions along the circumferential direction and the second arm of the other. In the first arm, a large-diameter roller support portion that supports the corresponding large-diameter roller is arranged closer to the radially inner side of the rotating portion than a small-diameter roller support portion that supports the one axial end side of the corresponding small-diameter roller. The first arm has a proximal end side portion that mainly extends along the axial direction of the corresponding small-diameter roller, and the proximal end side portion connects a mounted portion mounted on the rotating portion to the large-diameter roller support portion. A part of the radially inner surface of the proximal end side portion faces the inner peripheral surface of the corresponding large-diameter roller, and the distance between the part of the inner surface and the inner peripheral surface of the corresponding large-diameter roller is 2 mm or less.

[0011] An omnidirectional wheel according to a fifth aspect of the present invention has an outer peripheral surface formed by a plurality of rollers and rotates about an axle rotation axis, wherein the omnidirectional wheel includes: a rotating portion that rotates about the axle rotation axis; and a plurality of support portions that are arranged along the circumferential direction of the rotating portion and are respectively mounted on the rotating portion to support the plurality of rollers on the rotating portion. The plurality of rollers include a plurality of small-diameter rollers and a plurality of large-diameter rollers, the outer diameter of the large-diameter rollers being larger than the outer diameter of the small-diameter rollers, and the small-diameter rollers and the large-diameter rollers are alternately arranged along the circumferential direction. Each of the support portions has a first arm and a second arm. The first arm supports one axial end side of a corresponding small-diameter roller among the plurality of small-diameter rollers, and the second arm supports the other axial end side of the corresponding small-diameter roller. A corresponding large-diameter roller among the plurality of large-diameter rollers is supported by the first arm of one of two circumferentially adjacent support portions and the second arm of the other. In the first arm, a large-diameter roller support portion that supports the corresponding large-diameter roller is arranged closer to the inner side in the radial direction of the rotating portion than a small-diameter roller support portion that supports the one axial end side of the corresponding small-diameter roller. The first arm has a proximal-side portion that mainly extends along the axial direction of the corresponding small-diameter roller, and the proximal-side portion connects a mounted portion mounted on the rotating portion to the large-diameter roller support portion. A part of the inner side surface in the radial direction in the proximal-side portion faces the inner peripheral surface of the corresponding large-diameter roller, the large-diameter roller support portion side in the proximal-side portion is arranged in a recess formed at an end of the corresponding large-diameter roller, and the weakest portion in the proximal-side portion is arranged in the recess.

[0012] An omnidirectional wheel according to a sixth aspect of the present invention has an outer peripheral surface formed by a plurality of rollers and rotates about an axle rotation axis. The omnidirectional wheel includes: a rotating portion that rotates about the axle rotation axis; and a plurality of support portions that are arranged along the circumferential direction of the rotating portion and are respectively mounted on the rotating portion to support the plurality of rollers on the rotating portion. The plurality of rollers include a plurality of small-diameter rollers and a plurality of large-diameter rollers, the outer diameter of the large-diameter rollers being larger than the outer diameter of the small-diameter rollers, and the small-diameter rollers and the large-diameter rollers being alternately arranged along the circumferential direction. Each of the support portions has a first arm and a second arm. The first arm supports one axial end side of a corresponding small-diameter roller among the plurality of small-diameter rollers, and the second arm supports the other axial end side of the corresponding small-diameter roller. The corresponding large-diameter roller among the plurality of large-diameter rollers is supported by the first arm of one of the two support portions adjacent to each other along the circumferential direction and the second arm of the other. In the first arm, a large-diameter roller support portion that supports the corresponding large-diameter roller is arranged closer to the radially inner side of the rotating portion than a small-diameter roller support portion that supports the one axial end side of the corresponding small-diameter roller. The small-diameter roller or the large-diameter roller has a substantially cylindrical core member, an outer peripheral member bonded to the outer peripheral surface of the core member, and a shaft disposed in a hole formed in the core member. The hole extends along the axial direction of the small-diameter roller or the large-diameter roller.

[0013] An omnidirectional wheel according to a seventh aspect of the present invention has an outer peripheral surface formed by a plurality of rollers and rotates about an axle rotation axis. The omnidirectional wheel includes: a rotating portion that rotates about the axle rotation axis; and a plurality of support portions that are arranged along the circumferential direction of the rotating portion and are respectively mounted on the rotating portion to support the plurality of rollers on the rotating portion. The plurality of rollers include a plurality of small-diameter rollers and a plurality of large-diameter rollers, the outer diameter of the large-diameter rollers being larger than the outer diameter of the small-diameter rollers, and the small-diameter rollers and the large-diameter rollers being alternately arranged along the circumferential direction. Each of the support portions has a first arm and a second arm. The first arm supports one axial end side of a corresponding small-diameter roller among the plurality of small-diameter rollers, and the second arm supports the other axial end side of the corresponding small-diameter roller. The corresponding large-diameter roller among the plurality of large-diameter rollers is supported by the first arm of one of the two support portions adjacent to each other along the circumferential direction and the second arm of the other. In the first arm, a large-diameter roller support portion that supports the corresponding large-diameter roller is arranged closer to the radially inner side of the rotating portion than a small-diameter roller support portion that supports the one axial end side of the corresponding small-diameter roller. A hole for screwing a fastening member is provided in the large-diameter roller support portion and the small-diameter roller support portion.

[0014] An omnidirectional wheel according to an eighth aspect of the present invention has an outer peripheral surface formed by a plurality of rollers and rotates about an axle rotation axis. The omnidirectional wheel includes: a rotating portion that rotates about the axle rotation axis; and a plurality of supporting portions that are arranged along the circumferential direction of the rotating portion and are respectively mounted on the rotating portion to support the plurality of rollers on the rotating portion. The plurality of rollers include a plurality of small-diameter rollers and a plurality of large-diameter rollers. The outer diameter of the large-diameter rollers is larger than the outer diameter of the small-diameter rollers. The small-diameter rollers and the large-diameter rollers are alternately arranged along the circumferential direction. Each of the supporting portions has a first arm and a second arm. The first arm supports one end side in the axial direction of a corresponding small-diameter roller among the plurality of small-diameter rollers, and the second arm supports the other end side in the axial direction of the corresponding small-diameter roller. The corresponding large-diameter roller among the plurality of large-diameter rollers is supported by the first arm of one of the two adjacent supporting portions along the circumferential direction and the second arm of the other. In the first arm, a large-diameter roller supporting portion that supports the corresponding large-diameter roller is arranged closer to the inner side in the radial direction of the rotating portion than a small-diameter roller supporting portion that supports one end side in the axial direction of the corresponding small-diameter roller. A first hole through which a small-diameter roller bolt passes is provided in one of the small-diameter roller supporting portions in the first arm and the second arm. A second hole for threadedly connecting a large-diameter roller bolt is provided in one of the large-diameter roller supporting portions in the first arm and the second arm. The small-diameter roller bolt is threadedly connected to a third hole provided in the small-diameter roller supporting portion in the other of the first arm and the second arm. A fourth hole through which the large-diameter roller bolt passes is provided in the large-diameter roller supporting portion in the other of the first arm and the second arm. The second hole and / or the third hole is a female threaded hole, or a nut is provided in the second hole and / or the third hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a cross-sectional view of an omnidirectional wheel according to a first embodiment of the present invention.

[0016] Figure 2 is a perspective view of the omnidirectional wheel according to the first embodiment.

[0017] Figure 3 is a perspective view of a state in which a part of the rollers of the omnidirectional wheel according to the first embodiment is removed.

[0018] Figure 4 is a partial cross-sectional perspective view of the omnidirectional wheel according to the first embodiment.

[0019] Figure 5 is a perspective view of an electric mobile device using the omnidirectional wheel according to the first embodiment.

[0020] Figure 6 is a schematic view of the bottom surface of an electric mobile device using the omnidirectional wheel according to the first embodiment.

[0021] Figure 7 Stereogram of the support part used for the omnidirectional wheel of the first embodiment.

[0022] Figure 8 Stereogram of the first arm member used for the omnidirectional wheel of the first embodiment.

[0023] Figure 9 Front view of the first arm member and the second arm member used for the omnidirectional wheel of the first embodiment.

[0024] Figure 10 Top view of the first arm member and the second arm member used for the omnidirectional wheel of the first embodiment.

[0025] Figure 11 Cross-sectional view of the omnidirectional wheel of the first embodiment.

[0026] Figure 12 It is Figure 1 Cross-sectional view taken along line XII-XII in

[0027] Figure 13 Cross-sectional view of the omnidirectional wheel of the first modification of the first embodiment.

[0028] Figure 14 Cross-sectional view of the omnidirectional wheel of the second modification of the first embodiment.

[0029] Figure 15 Cross-sectional view of the omnidirectional wheel of the third modification of the first embodiment.

[0030] Figure 16 Cross-sectional view of the omnidirectional wheel of the fourth modification of the first embodiment.

[0031] Figure 17 Cross-sectional view of the omnidirectional wheel of the second embodiment of the present invention.

[0032] Figure 18 Cross-sectional view showing the first modification of the above-described embodiment.

[0033] Figure 19 Partial cross-sectional stereogram showing the second modification of the above-described embodiment.

[0034] Figure 20 Stereogram showing the third modification of the above-described embodiment.

[0035] Figure 21 Stereogram of the first arm member and the second arm member of the third modification of the above-described embodiment.

[0036] Figure 22 It is Figure 1 Cross-sectional view taken along line XXII-XXII in Detailed implementation manners

[0037] The omnidirectional wheel 1 according to the first embodiment of the present invention will be described below with reference to the accompanying drawings.

[0038] As Figure 4 and Figure 6 shown, the omnidirectional wheel 1 has a pair of hub members 20 and 30 supported on the axle 10 via a pair of bearings 10a in the width direction. Therefore, the hub members 20 and 30 function as a rotating part that rotates around the rotation axis RL.

[0039] In addition, as Figure 1 , Figure 2 , Figure 4 etc. shown, the outer peripheral surface of the omnidirectional wheel 1 is formed by a plurality of small-diameter rollers (first rollers) 40 and a plurality of large-diameter rollers (second rollers) 50, and the plurality of rollers 40 and 50 are supported by a plurality of support portions 60. The outer diameter of the large-diameter roller 50 is larger than the outer diameter of the small-diameter roller 40, and the plurality of large-diameter rollers 50 and the plurality of small-diameter rollers 40 are alternately arranged along the circumferential direction of the hub members 20 and 30. Each of the plurality of support portions 60 is attached to the hub members 20 and 30 by bolts (fastening members) B.

[0040] In the present embodiment, the hub members 20 and 30 are formed by blanking a metal plate-like member. Instead of the hub members 20 and 30, a block in a disc shape made of aluminum or the like can also be used. In this case, the block functions as a rotating part that rotates around the rotation axis RL, and the plurality of support portions 60 are respectively attached to the outer peripheral side of the block by bolts (fastening members) B. In addition, instead of bolts, rivets (fastening members) can be used, or an axis (fastening member) fixed to the hub members 20 and 30 by welding can be used, and other known fastening members can also be used.

[0041] As Figure 1 shown, each small-diameter roller 40 has a substantially cylindrical core member 41, an outer peripheral member 42 bonded to the outer peripheral surface of the core member 41, and a shaft 43 disposed in a hole 41a formed in the core member 41. The hole 41a extends along the axial direction of the small-diameter roller 40. The core member 41 can be made of a metal such as aluminum or iron, or can be made of plastic. In the present embodiment, the outer peripheral member 42 is formed of a material having rubber-like elasticity such as rubber or silicon, and is vulcanized and bonded to the outer peripheral surface of the core member 41 in one example.

[0042] The shaft 43 is made of a metal such as iron or aluminum. The core member 41 is supported on the shaft 43 via a bearing 44, so that the core member 41 can rotate around the rotation axis RL with respect to the shaft 43. A step for abutting the bearing 44 is formed on the inner peripheral surface of the hole 41a of the core member 41, and a step for abutting the bearing 44 is also formed on the outer peripheral surface of the shaft 43. A structure in which a sleeve is disposed on the outer peripheral surface of the shaft 43 and the bearing 44 abuts against the sleeve can also be adopted.

[0043] As Figure 1 shown, each large-diameter roller 50 has: a core member 51 having an outer peripheral portion 51b with a substantially cylindrical shape; an outer peripheral member 52 bonded to the outer peripheral surface of the outer peripheral portion 51b; and a shaft 53 disposed in a hole 51a formed in the core member 51. The hole 51a extends along the axial direction of the large-diameter roller 50. The core member 41 can be made of a metal such as aluminum or iron, or can be made of plastic. In the present embodiment, the outer peripheral member 52 is formed of a material having rubber-like elasticity such as rubber or silicon, and is vulcanized and bonded to the outer peripheral surface of the outer peripheral portion 51b of the core member 51 in one example.

[0044] In the present embodiment, the core member 51 has an outer peripheral portion 51b, an inner peripheral portion 51c disposed radially inward of the outer peripheral portion 51b, and an intermediate portion 51d connecting the outer peripheral portion 51b and the inner peripheral portion 51c. The intermediate portion 51d extends along the radial direction of the large-diameter roller 50. In addition, a plurality of ribs (not shown) are provided on the inner peripheral surface of the outer peripheral portion 51b, and each rib is connected to the intermediate portion 51d and / or the inner peripheral portion 51c. The hole 51a is formed in the inner peripheral portion 51c.

[0045] The shaft 53 is made of a metal such as iron or aluminum. The core member 51 is supported by the shaft 53 via a bearing 54, so that the core member 51 can rotate relative to the shaft 53 about a rotation axis RL2. A step for the bearing 54 to abut against is formed on the inner peripheral surface of the hole 51a of the core member 51, and a step for the bearing 54 to abut against is also formed on the outer peripheral surface of the shaft 53. A structure in which a sleeve is disposed on the outer peripheral surface of the shaft 53 and the bearing 54 abuts against the sleeve can also be adopted.

[0046] As Figure 1 shown, each support portion 60 has: a first arm member 70 that supports one axial end side of a corresponding small-diameter roller 40 among a plurality of small-diameter rollers 40; and a second arm member 80 that supports the other axial end side of the corresponding small-diameter roller 40. In the present embodiment, the first arm member 70 supports one axial end side of the shaft 43 of the corresponding small-diameter roller (corresponding first roller) 40, and the second arm member 80 supports the other axial end side of the shaft 43 of the corresponding small-diameter roller 40.

[0047] In addition, as Figure 1 shown, a corresponding large-diameter roller (corresponding second roller) 50 among a plurality of large-diameter rollers 50 is supported by the first arm member 70 of one of two support portions 60 adjacent to each other in the circumferential direction of the hub members 20 and 30 and the second arm member 80 of the other. In the present embodiment, the second arm member 80 supports one axial end side of the shaft 53 of the corresponding large-diameter roller 50, and the first arm member 70 supports the other axial end side of the shaft 53 of the corresponding large-diameter roller 50.

[0048] In addition, in some cases, the shaft 43 is not provided on the small-diameter roller 40. In this case, the bearing 44 corresponding to one axial end side of the small-diameter roller 40 is supported by the first arm member 70, and the bearing 44 corresponding to the other axial end side of the small-diameter roller 40 is supported by the second arm member 80.

[0049] In addition, in some cases, the shaft 53 is not provided on the large-diameter roller 50. In this case, the bearing 54 corresponding to one axial end side of the large-diameter roller 50 is supported by the second arm member 80, and the bearing 54 corresponding to the other axial end side of the large-diameter roller 50 is supported by the first arm member 70.

[0050] The arm members 70 and 80 are formed of a metal such as aluminum and are formed by casting. The arm members 70 and 80 can also be formed by sintering metal powder. The arm members 70 and 80 can also be formed of a metal plate such as iron and are formed by stamping. The arm members 70 and 80 can also be formed of metal, plastic, or a combination of plastic and metal. The arm members 70 and 80 can also be formed of a metal such as aluminum or iron and are formed by forging.

[0051] As Figure 9 shown, a small-diameter roller support portion 71 for supporting one end side of the corresponding small-diameter roller 40 is provided on one end side of the first arm member 70, and a first mounted portion 72 to be mounted on the hub members 20 and 30 is provided on the other end side of the first arm member 70.

[0052] As Figures 7 - 10 shown, the first arm member 70 further has: a base end side portion 73 that extends mainly along the axial direction of the corresponding small-diameter roller 40 from the first mounted portion 72; a large-diameter roller support portion 74 for supporting the large-diameter roller 50; and a connecting portion 75 that connects the large-diameter roller support portion 74 and the small-diameter roller support portion 71.

[0053] A hole 71a for screwing a small-diameter roller bolt (fastening member) B1 described later is provided in the small-diameter roller support portion 71, and a hole 74a through which a large-diameter roller bolt (fastening member) B2 described later passes is provided in the large-diameter roller support portion 74.

[0054] In the present embodiment, the plane CL including the center line of the hole 71a and the center line of the hole 74a is the center of the first arm member 70 in the specified direction along the rotation axis RL. The first mounted portion 72 is not arranged at a position centered with respect to this center, but is arranged at a position offset in the specified direction with respect to this center (see Figure 10 ). In the present embodiment, the position of the end portion in the specified direction in the first mounted portion 72 coincides with the position of the plane CL.

[0055] In addition, the center in the width direction of the base end side portion 73 may also be the center of the first arm member 70 in the specified direction along the rotation axis RL.

[0056] In the present embodiment, the base end side portion 73 is substantially plate-shaped, and the position of the center of the base end side portion 73 in the specified direction also coincides with the position of the center line CL. In the present embodiment, at least one of the thickness dimension and the width dimension of the base end side portion 73 gradually decreases toward the one end side of the first arm member 70.

[0057] The end portion of the base end side portion 73 is bent in a direction along the rotation axis RL2 of the corresponding large-diameter roller 50, and a large-diameter roller support portion 74 is provided at the end of the base end side portion 73. In the present embodiment, the large-diameter roller support portion 74 has: a base portion 74b that extends radially outward from the end of the base end side portion 73 toward the hub members 20, 30; and a cylindrical portion 74c that extends from the base portion 74b or near the base portion 74b in a direction along the rotation axis RL2 of the corresponding large-diameter roller 50. The cylindrical portion 74c protrudes from the base portion 74b in a direction away from the first mounting portion 72. In the present embodiment, the radial direction of the hub members 20, 30 coincides with the radial direction of the omnidirectional wheel 1.

[0058] The inner diameter of the cylindrical portion 74c is slightly larger than the outer diameter of the other end side in the axial direction of the shaft 53 of the large-diameter roller 50. Or the inner diameter of the cylindrical portion 74c is equal to the outer diameter of the other end side in the axial direction of the shaft 53.

[0059] If the other end side in the axial direction of the shaft 53 of the corresponding large-diameter roller 50 is inserted into the cylindrical portion 74c, the end face of the cylindrical portion 74c is pressed against the inner ring of the bearing 54, whereby the inner ring of the bearing 54 is pressed against the step of the other end side of the shaft 53 of the corresponding large-diameter roller 50.

[0060] In addition, in some cases, the cylindrical portion 74c is not formed in the large-diameter roller support portion 74. In this case, a counterbore is provided in the base portion 74b, and the end portion of the shaft 53 is fitted into the counterbore. In some cases, the large-diameter roller support portion 74 has other structures capable of supporting the other end side of the corresponding large-diameter roller 50.

[0061] In addition, a structure in which the outer peripheral surface of the cylindrical portion 74c of the large-diameter roller support portion 74 is fitted into the inner peripheral surface of the shaft 53 of the large-diameter roller 50 may also be adopted. In this case, the inner ring of the bearing 54 is fitted into the outer peripheral surface of the cylindrical portion 74c. Or the inner ring of the bearing 54 is fitted into the outer peripheral surface of the shaft 53. At this time, the end face of the shaft 53 is axially pressed against the inner ring of the bearing 54, and the outer ring of the bearing 54 is fitted into the inner peripheral surface of the inner peripheral portion 51c, or the outer ring of the bearing 54 may be fitted into the inner peripheral surface of the inner peripheral portion 51c without providing the shaft 53.

[0062] Alternatively, the inner peripheral surface of the inner peripheral portion 51c of the large-diameter roller 50 can be formed to be smaller, and the shaft 53 of the large-diameter roller 50 can be fixed to the inner peripheral portion 51c by fitting or the like. In such a structure, the shaft 53 can also be omitted and the inner peripheral portion 51c can be formed into a shape in which the shaft 53 is integrated.

[0063] In this structure, the outer ring of the bearing 54 can also be fitted to the inner peripheral surface of the cylindrical portion 74c of the large-diameter roller support portion 74, and the inner ring of the bearing 54 can be fitted to the outer peripheral surface of the shaft 53 or the outer peripheral surface of the inner peripheral portion 51c. In such a case, the large-diameter roller 50 is also rotatably supported by the large-diameter roller support portion 74.

[0064] In the present embodiment, the small-diameter roller support portion 71 has a base portion 71b extending radially outward of the hub members 20, 30, and a cylindrical portion 71c extending from the base portion 71b or near the base portion 71b in a direction along the rotation axis RL1 of the corresponding small-diameter roller 40. The cylindrical portion 71c protrudes from the base portion 71b toward the direction approaching the first mounting portion 72.

[0065] The inner diameter of the cylindrical portion 71c is slightly larger than the outer diameter of one axial end side of the shaft 43 of the small-diameter roller 40. Alternatively, the inner diameter of the cylindrical portion 71c is equal to the outer diameter of one axial end side of the shaft 43.

[0066] If one axial end side of the shaft 43 of the corresponding small-diameter roller 40 is inserted into the cylindrical portion 71c, the end face of the cylindrical portion 71c is pressed against the inner ring of the bearing 44, whereby the inner ring of the bearing 44 is pressed against the step of one end side of the shaft 43 of the corresponding small-diameter roller 40.

[0067] Alternatively, in some cases, the cylindrical portion 71c is not formed in the small-diameter roller support portion 71. In this case, a counterbore is provided in the base portion 71b, and the end portion of the shaft 43 is fitted into the counterbore. In some cases, the small-diameter roller support portion 71 has another structure capable of supporting the other end side of the corresponding small-diameter roller 40.

[0068] Alternatively, a structure in which the outer peripheral surface of the cylindrical portion 71c of the small-diameter roller support portion 71 is fitted to the inner peripheral surface of the shaft 43 of the small-diameter roller 40 can also be adopted. In this case, the inner ring of the bearing 44 is fitted to the outer peripheral surface of the cylindrical portion 71c. Alternatively, the inner ring of the bearing 44 is fitted to the outer peripheral surface of the shaft 43. At this time, the end face of the shaft 43 is axially pressed against the inner ring of the bearing 44, and the outer ring of the bearing 44 is fitted to the inner peripheral surface of the core member 41, or the outer ring of the bearing 44 can be fitted to the inner peripheral surface of the core member 41 without providing the shaft 43.

[0069] Alternatively, the inner peripheral surface of the core member 41 of the small-diameter roller 40 can be formed to be smaller, and the shaft 43 of the small-diameter roller 40 can be fixed to the core member 41 by fitting or the like. In such a structure, the shaft 43 can also be omitted and the core member 41 can be formed into a shape in which the shaft 43 is integrated.

[0070] In this structure, the outer ring of the bearing 44 can be fitted to the inner peripheral surface of the cylindrical portion 71c of the small-diameter roller support portion 71, and the inner ring of the bearing 44 can be fitted to the outer peripheral surface of the shaft 43 or the outer peripheral surface of the core member 41. In these cases, the small-diameter roller 40 is also rotatably supported by the small-diameter roller support portion 71.

[0071] The connecting portion 75 connects the large-diameter roller support portion 74 and the small-diameter roller support portion 71. In the present embodiment, the connecting portion 75 connects the base portion 74b of the large-diameter roller support portion 74 and the base portion 71b of the small-diameter roller support portion 71. Alternatively, the connecting portion 75 can also connect other portions of the large-diameter roller support portion 74 and other portions of the small-diameter roller support portion 71.

[0072] When viewed in the direction extending from the rotation axis RL, that is, as Figure 1 or Figure 9 when the first arm member 70 is viewed, the connecting portion 75 mainly extends in the direction extending along the rotation axis RL2 of the corresponding large-diameter roller 50. In the present embodiment, when the first arm member 70 is viewed as Figure 9 the direction in which the connecting portion 75 extends is the direction in which a straight line connecting the center point P1 on the small-diameter roller support portion 71 side of the connecting portion 75 and the center point P2 on the large-diameter roller support portion 74 side of the connecting portion 75 extends.

[0073] When viewed in the direction extending from the rotation axis RL, when the angle formed by the direction in which the connecting portion 75 extends and the direction in which the rotation axis RL2 extends is 30° or less, it can be said that the connecting portion 75 mainly extends in the direction extending along the rotation axis RL2. Preferably, when the angle formed by the direction in which the connecting portion 75 extends and the direction in which the rotation axis RL2 extends is 20° or less, it can be said that the connecting portion 75 mainly extends in the direction extending along the rotation axis RL2. More preferably, when the angle formed by the direction in which the connecting portion 75 extends and the direction in which the rotation axis RL2 extends is 15° or less, it can be said that the connecting portion 75 mainly extends in the direction extending along the rotation axis RL2.

[0074] As Figure 9 shown, a small-diameter roller support portion 81 that supports the other end side of the corresponding small-diameter roller 40 is provided on one end side of the second arm member 80, and a second mounted portion 82 that is mounted on the hub members 20, 30 is provided on the other end side of the second arm member 80.

[0075] As Figures 7 - 10As shown, the second arm member 80 further has: a proximal end side portion 83 that extends mainly along the axial direction of the corresponding small-diameter roller 40 from the second mounting portion 82; a large-diameter roller support portion 84 for supporting the large-diameter roller 50; and a connecting portion 85 that connects the large-diameter roller support portion 84 and the small-diameter roller support portion 81.

[0076] A hole 81a through which a small-diameter roller bolt B1 described later passes is provided in the small-diameter roller support portion 81, and a hole 84a for threaded connection of a large-diameter roller bolt B2 described later is provided in the large-diameter roller support portion 84.

[0077] In the present embodiment, a plane CL including the center line of the hole 81a and the center line of the hole 84a is the center of the second arm member 80 in a specified direction along the rotation axis RL. The second mounting portion 82 is not disposed at a position centered with respect to this center, but is disposed at a position offset in the specified direction with respect to this center (see Figure 10 ). In the present embodiment, the position of the end portion of the second mounting portion 82 in the specified direction coincides with the position of the plane CL. The first mounting portion 72 and the second mounting portion 82 are arranged along the specified direction, and the first mounting portion 72 and the second mounting portion 82 are disposed on opposite sides of the center.

[0078] In addition, the center in the width direction of the proximal end side portion 83 may also be the center of the second arm member 80 in a specified direction along the rotation axis RL.

[0079] In the present embodiment, the proximal end side portion 83 is substantially plate-shaped, and the position of the center of the proximal end side portion 83 in the specified direction also coincides with the position of the center line CL. In the present embodiment, at least one of the thickness dimension and the width dimension of the proximal end side portion 83 gradually decreases toward one end side of the second arm member 80.

[0080] The end portion of the proximal end side portion 83 is bent in a direction along the rotation axis RL2 of the corresponding large-diameter roller 50, and the large-diameter roller support portion 84 is provided at the end of the proximal end side portion 83. In the present embodiment, the large-diameter roller support portion 84 has: a base portion 84b that extends radially outward from the end of the proximal end side portion 83 toward the hub members 20, 30; and a cylindrical portion 84c that extends in a direction along the rotation axis RL2 of the corresponding large-diameter roller 50 from the base portion 84b or near the base portion 84b. The cylindrical portion 84c protrudes from the base portion 84b in a direction away from the second mounting portion 82.

[0081] The inner diameter of the cylindrical portion 84c is slightly larger than the outer diameter of one axial end side of the shaft 53 of the large-diameter roller 50. Or the inner diameter of the cylindrical portion 84c is equal to the outer diameter of one axial end side of the shaft 53.

[0082] If one axial end side of the shaft 53 corresponding to the large-diameter roller 50 is inserted into the cylindrical portion 84c, the end face of the cylindrical portion 84c is pressed against the inner ring of the bearing 54, whereby the inner ring of the bearing 54 is pressed against the step on one end side of the shaft 53 corresponding to the large-diameter roller 50.

[0083] In addition, in some cases, the cylindrical portion 84c is not formed in the large-diameter roller support portion 84. In this case, a counterbore is provided in the base portion 84b, and the end portion of the shaft 53 is fitted into the counterbore. In some cases, the large-diameter roller support portion 84 has another structure capable of supporting the other end side of the corresponding large-diameter roller 50.

[0084] In the present embodiment, the small-diameter roller support portion 81 has: a base portion 81b extending radially outward of the hub members 20, 30; and a cylindrical portion 81c extending from the base portion 81b or near the base portion 81b in a direction along the rotation axis RL1 of the corresponding small-diameter roller 40. The cylindrical portion 81c projects from the base portion 81b in a direction approaching the second mounted portion 82.

[0085] The inner diameter of the cylindrical portion 81c is slightly larger than the outer diameter of the other axial end side of the shaft 43 of the small-diameter roller 40. Or the inner diameter of the cylindrical portion 81c is equal to the outer diameter of the other axial end side of the shaft 43.

[0086] If the other axial end side of the shaft 43 corresponding to the small-diameter roller 40 is inserted into the cylindrical portion 81c, the end face of the cylindrical portion 81c is pressed against the inner ring of the bearing 44, whereby the inner ring of the bearing 44 is pressed against the step on the other end side of the shaft 43 corresponding to the small-diameter roller 40.

[0087] In addition, in some cases, the cylindrical portion 81c is not formed in the small-diameter roller support portion 81. In this case, a counterbore is provided in the base portion 81b, and the end portion of the shaft 43 is fitted into the counterbore. In some cases, the small-diameter roller support portion 81 has another structure capable of supporting the other end side of the corresponding small-diameter roller 40.

[0088] The connecting portion 85 connects the large-diameter roller support portion 84 and the small-diameter roller support portion 81. In the present embodiment, the connecting portion 85 connects the base portion 84b of the large-diameter roller support portion 84 and the base portion 81b of the small-diameter roller support portion 81. In addition, the connecting portion 85 may also connect other portions of the large-diameter roller support portion 84 and other portions of the small-diameter roller support portion 81.

[0089] When viewed in the direction extending from the rotation axis RL, that is, as Figure 1 or Figure 9 when the second arm member 80 is viewed, the connecting portion 85 mainly extends in the direction extending along the rotation axis RL2 of the corresponding large-diameter roller 50. The definition of the direction in which the connecting portion 85 extends is the same as the definition of the direction in which the connecting portion 75 of the first arm member 70 extends.

[0090] As Figure 1 and Figure 3 shown, the large-diameter roller bolt B2 passes through the hole 74a of the first arm member 70 and the shaft 53 of the large-diameter roller 50, and is threadedly connected to the hole 84a of the second arm member 80. Thus, the corresponding large-diameter roller 50 is supported by a pair of adjacent support portions 60. In addition, when the hole 84a is not a female threaded hole, a nut is provided near the hole 84a.

[0091] In addition, the small-diameter roller bolt B1 passes through the hole 81a of the second arm member 80 and the shaft 43 of the small-diameter roller 40, and is threadedly connected to the hole 71a of the first arm member 70. Thus, the corresponding small-diameter roller 40 is supported by the support portion 60. In addition, when the hole 71a is not a female threaded hole, a nut is provided near the hole 71a. If the nut is formed of a material having a higher strength than aluminum, such as iron, the small-diameter roller 40 can be reliably fixed by the small-diameter roller bolt B1. The nut may also be embedded in the hole provided in the first arm member 70.

[0092] The first mounted portion 72 is provided with a hole 72a penetrating in the direction along the rotation axis RL, and the second mounted portion 82 is also provided with a hole 82a penetrating in the direction along the rotation axis RL.

[0093] As Figure 4 shown, holes 21 and 31 are formed at positions corresponding to the small-diameter roller 40 in the hub members 20 and 30. The bolt B passes through the hole 21 of the hub member 20, the hole 72a of the first mounted portion 72, the hole 82a of the second mounted portion 82, and the hole 31 of the hub member 30, and is threadedly connected to the female threaded hole of the nut N. Thus, the plurality of support portions 60 are respectively mounted on the hub members 20 and 30. The female threaded hole may also be formed in the hub member 30. Figure 3 The state where the shafts 43 and 53 are fixed to the support portion 60 is shown.

[0094] In addition, in the direction along the rotation axis RL1 corresponding to the small-diameter roller 40, the positions of the first mounted portion 72 and the second mounted portion 82 are aligned with the central position of the corresponding small-diameter roller 40.

[0095] In the present embodiment, as described above, the portion of the base end of the base end side portion 83 of the second arm member 80 that is not provided with the second mounted portion 82 contacts or approaches the first mounted portion 72 or the base end side portion 73 of the first arm member 70 (see Figure 7 and Figure 9 ). Therefore, when a large force in the wheel radial direction, the wheel width direction, etc. is applied to the second arm member 80, the deformation of the base end side portion 83 of the second arm member 80 is suppressed by the first mounted portion 72 or the base end side portion 73.

[0096] In addition, a portion of the proximal end of the proximal end side portion 73 of the first arm member 70 that is fixed as described above and does not have the first mounting portion 72 contacts or approaches the second mounting portion 82 or the proximal end side portion 83 of the second arm member 80. Therefore, when a large force in the wheel radial direction, the wheel width direction, etc. is applied to the first arm member 70, the deformation of the proximal end side portion 73 of the first arm member 70 is suppressed by the second mounting portion 82 or the proximal end side portion 83.

[0097] In the present embodiment, the first arm member 70 is different from the second arm member 80 in that the hole 71a is a female threaded hole while the hole 81a is a through hole, and the hole 74a is a through hole while the hole 84a is a female threaded hole, and the other structures are the same. That is, compared with the second arm member 80, at least the shapes other than the holes 71a, 74a, 81a, and 84a of the first arm member 70 are the same, and if the first arm member 70 is turned over, it becomes the shape of the second arm member 80. This structure is beneficial to reducing the manufacturing cost.

[0098] When manufacturing the omnidirectional wheel 1, after the large-diameter roller 50 is supported between a pair of support portions 60 by the large-diameter roller bolt B2, the small-diameter roller 40 is supported by the large-diameter roller bolt B1 on one of the pair of support portions 60, and then the large-diameter roller 50 is supported in the same way. By repeating such operations, a plurality of rollers 40 and 50 are connected along the circumferential direction of the omnidirectional wheel 1.

[0099] In addition, as Figure 1 shown, recesses 55 into which a part of the axial ends of the small-diameter roller 40 enter are formed at both axial ends of the large-diameter roller 50. By respectively arranging a part of the axial ends of the small-diameter roller 40 in the recesses 55 of the large-diameter roller 50, the circumferential distance between the small-diameter roller 40 and the large-diameter roller 50 becomes closer.

[0100] As described above, when connecting a plurality of rollers 40 and 50 along the circumferential direction, when the last roller 40 among the plurality of rollers 40 is mounted on the support portion 60 by the small-diameter roller bolt B1, the head of the small-diameter roller bolt B1 cannot be rotated by a tool. This situation is obvious according to Figure 1 etc.

[0101] To solve this problem, for example, Figure 11 shown, a first roller group G1 and a second roller group G2 each having at least one small-diameter roller 40 and at least one large-diameter roller 50 are manufactured. In each of the roller groups G1 and G2, the large-diameter roller 50 and the small-diameter roller 40 are supported by bolts B1 and B2 on the support portion 60. More than three roller groups can be manufactured.

[0102] Moreover, as Figure 1 and Figure 11As shown, in order to connect multiple roller groups G1 and G2 to each other, holes 40a extending from the outer peripheral surface of the small-diameter roller 40 to the inner peripheral surface of the shaft 43 of the small-diameter roller 40 are formed at the ends of each roller group G1 and G2. Further, on the outer peripheral surface of the small-diameter roller bolt B1 for the small-diameter roller 40, a chamfer (engagement portion) 90 is formed at a position corresponding to the hole 40a.

[0103] As Figure 1 and Figure 12 shown, the chamfer 90 has a first flat portion 91, a second flat portion 92, and a curved surface portion 93. The second flat portion 92 is different in position in the circumferential direction of the outer peripheral surface of the small-diameter roller bolt B1 from the first flat portion 91, and the curved surface portion 93 connects the first flat portion 91 and the second flat portion 92.

[0104] The hole 40a penetrates the outer peripheral member 42, the core member 41, and the shaft 43 of the small-diameter roller 40. In the hole 40a, for example, an internal thread is formed in a portion provided on the core member 41 or the shaft 43.

[0105] Thread the threaded member 94 onto this internal thread, and engage a screw turning tool with a groove formed in the end face of the threaded member 94, thereby screwing the threaded member 94 into the small-diameter roller bolt B1. As a result, the threaded member 94 engages with the chamfer 90. In this state, by rotating the small-diameter roller 40 in a predetermined direction using a tool, hand, etc., the small-diameter roller bolt B1 rotates together with the small-diameter roller 40, and the small-diameter roller bolt B1 is threaded into the hole 71a of the first arm member 70. Thus, the shaft 43 of the small-diameter roller 40 is fixed to the first arm member 70 and the second arm member 80 by the small-diameter roller bolt B1. This operation can be performed in a state where a part of the support portion 60 is already installed on the hub members 20 and 30, or the support portion 60 can be installed on the hub members 20 and 30 after the connection of the rollers 40 and 50 is completed.

[0106] Next, use a screw turning tool to move the threaded member 94 radially outward of the small-diameter roller 40. As a result, the small-diameter roller 40 can rotate. In some cases, the threaded member 94 functions as a bolt member for plugging the hole 40a. On the other hand, after removing the threaded member 94 from the hole 40a, as Figure 1 shown, a bolt member 95 can be installed in the hole 40a( Figure 12 ).

[0107] On the other hand, it is also possible to sequentially connect multiple small-diameter rollers 40 and multiple large-diameter rollers 50 using multiple first arm members 70, multiple second arm members 80, multiple small-diameter roller bolts B1, and multiple large-diameter roller bolts B2, and thread the small-diameter roller bolt B1 of the last small-diameter roller 40 into the first arm member 70.

[0108] In addition, when the small-diameter roller bolt B1 is screwed into the hole 71a of the first arm member 70, the small-diameter roller 40 and the threaded member 94 rotate in the direction of arrow A Figure 12 and the threaded member 94 engages with the first flat portion 91. Here, a second flat portion 92 and a curved surface portion 93 are formed on the chamfer 90. Therefore, if the small-diameter roller 40 is rotated in the direction opposite to arrow A, the threaded member 94 moves from the first flat portion 91 to the second flat portion 92 via the curved surface portion 93.

[0109] In some cases, when the screwing-in of the small-diameter roller bolt B1 by rotating the small-diameter roller 40 in the direction of arrow A is completed, the hole 40a is disposed on the support portion 60 side. In this state, the threaded member 94 cannot be separated from the small-diameter roller bolt B1 and the small-diameter roller 40 cannot be rotated. If the second flat portion 92 and the curved surface portion 93 are provided, after the screwing-in of the small-diameter roller bolt B1 is completed, the small-diameter roller 40 can be moved in the direction opposite to arrow A. Therefore, the hole 40a can be moved to a position not corresponding to the support portion 60, and the threaded member 94 can be separated from the small-diameter roller bolt B1.

[0110] As Figure 13 shown, a hole 96 can also be provided in the small-diameter roller bolt B1 instead of the chamfer 90. In this case, the hole 40a can also penetrate the small-diameter roller 40 in the radial direction. The threaded member 94 passes through the hole 96 and the hole 40a and is threadedly connected to, for example, an internal thread provided in the core member 41 or the shaft 43 in the hole 40a. In this state, the small-diameter roller bolt B1 can be screwed into the first arm member 70 by rotating the small-diameter roller 40. Preferably, grooves for engaging a screw driving tool are formed at both ends of the threaded member 94.

[0111] As Figure 14 shown, a hole 50a extending from the outer peripheral surface of the large-diameter roller 50 to the recess 55 of the large-diameter roller 50 can also be formed in the large-diameter roller 50 near the head of the last-screwed-in small-diameter roller bolt B1. In this case, the bolt driving tool passes through the hole 50a, and the small-diameter roller 40 can be screwed into the hole 71a of the first arm member 70 using the bolt driving tool. The hole 50a can also be blocked by a bolt member 50b.

[0112] In addition, as Figure 15 shown, a fixing member 97 can also be used to fix one end side of the shaft 43 of the small-diameter roller 40 finally mounted on the first arm member 70 to the first arm member 70. In this case, a hole penetrating the shaft 43 in the radial direction is provided on one end side of the shaft 43, and a hole is also provided at a position corresponding to the hole of the shaft 43 in the first arm member 70. In a state where the fixing member 97 passes through the hole of the first arm member 70 and the hole of the shaft 43, the fixing member 97 is fixed to the first arm member 70. Thereby, one end side of the shaft 43 of the small-diameter roller 40 is fixed to the first arm member 70.

[0113] In this case, as Figure 15 shown, the other end side of the shaft 43 of the small-diameter roller 40 is fixed to the second arm member 80 by a short small-diameter roller bolt B1.

[0114] In addition, the fixing member 97 is a metal pin, bolt, threaded member, rivet, or the like.

[0115] In addition, as Figure 16 shown, an adhesive may also be used to fix one end side of the shaft 43 of the small-diameter roller 40 finally mounted on the first arm member 70 to the first arm member 70.

[0116] In addition, in each of the above-described embodiments, part or all of the length direction of the shaft 43 may be solid as Figure 15 shown, and all of the length direction of the shaft 43 may also be hollow.

[0117] The omnidirectional wheel 1 configured as described above is used, for example, as a front wheel of an electric mobile device 100 for one person to sit and ride (see Figure 5 ). The omnidirectional wheel 1 may also be used as a rear wheel or other wheels of the electric mobile device 100. In addition, in some cases, the omnidirectional wheel 1 is used as a wheel of other devices such as a robot, or as a wheel of other vehicles.

[0118] For example Figure 5 and Figure 6 shown, the electric mobile device 100 includes a mobile device main body 110, and the mobile device main body 110 has an omnidirectional wheel 1 as a front wheel, a rear wheel 120, and a body 130 supported by the omnidirectional wheel 1 and the rear wheel 120. In addition, the electric mobile device includes: a seat unit (seat) 140 detachably mounted on the mobile device main body 110; and a drive device 150 such as a motor mounted on the mobile device main body 110 for driving at least one of the omnidirectional wheel 1 and the rear wheel 120.

[0119] When such an electric mobile device uses the omnidirectional wheel 1, the rollers 40 and 50 of the omnidirectional wheel 1 are subjected to a large force. The weight of the electric mobile device is often 50 kg or more, and in some cases, it is close to 100 kg. In addition, the weights of the drivers of the electric mobile devices are different. In addition, the electric mobile device sometimes needs to cross steps and sometimes needs to travel on a road with many unevennesses. Therefore, the rollers 40 and 50 are often subjected to a force of 300 N or more, and sometimes a force exceeding 500 N. In addition, such an electric mobile device is used for a long time every day. Therefore, the omnidirectional wheel 1 needs to have a high level of strength and durability.

[0120] In the present embodiment, each corresponding small-diameter roller 40 is supported by each supporting portion 60. One axial end side of the corresponding small-diameter roller 40 is supported by the first arm member 70, and the other axial end side of the corresponding small-diameter roller 40 is supported by the second arm member 80. Further, the corresponding large-diameter roller 50 is supported by the first arm member 70 of one of the two circumferentially adjacent supporting portions 60 and the second arm member 80 of the other. Thus, the small-diameter roller 40 is not supported by a single member, but by the first arm member 70 and the second arm member 80. Further, one end side of the large-diameter roller 50 is supported by the second arm member 80 and the other end side is supported by the first arm member 70.

[0121] Therefore, compared with the case where the small-diameter roller 40 is supported by a single member, the connection between adjacent components becomes closer, and the force applied to the small-diameter roller 40 due to contact with the road surface can be more easily transmitted to the adjacent large-diameter roller 50. Further, the force applied to the large-diameter roller 50 can be more easily transmitted to the adjacent small-diameter roller 40. In addition, the force applied to the large-diameter roller 50 due to contact with the road surface can be more easily transmitted to the adjacent small-diameter roller 40. With this structure, not only can the wall thickness of the first arm member 70 and the second arm member 80 be reduced, but also the force applied to each of the rollers 40, 50 can be effectively blocked by the adjacent rollers 40, 50 and arm members 70, 80.

[0122] In addition, compared with the case where the small-diameter roller 40 is supported by a single member, when each of the rollers 40, 50 and each supporting portion 60 are mounted on the hub members 20, 30, one end side of the small-diameter roller 40 is easily disposed at an appropriate position relative to the first arm member 70. Further, the other end side of the small-diameter roller 40 is also easily disposed at an appropriate position relative to the second arm member 80. This structure is advantageous for effectively blocking the force applied to each of the rollers 40, 50 by the adjacent rollers 40, 50 and arm members 70, 80. Thereby, an increase in the force borne by each of the rollers 40, 50 and weight reduction can be achieved at a high level simultaneously.

[0123] In the present embodiment, one axial end side of the corresponding small-diameter roller 40 is supported by one end side of the first arm member 70, and the other end side of the first arm member 70 is mounted on the hub members 20, 30. Further, one axial end side of the corresponding small-diameter roller 40 is supported by one end side of the second arm member 80, and the other end side of the second arm member 80 is mounted on the rollers 40, 50. Thus, in the first arm member 70, since the portion supporting the corresponding small-diameter roller 40 is separated from the portion mounted on the hub members 20, 30, the force applied to the small-diameter roller 40 is easily transmitted to the adjacent large-diameter roller 50, and the force applied to the large-diameter roller 50 is also easily transmitted to the adjacent small-diameter roller 40.

[0124] In addition, in the first arm member 70, since the portion supporting the corresponding small-diameter roller 40 is separated from the portion mounted on the hub members 20 and 30, when the rollers 40 and 50 and the respective support portions 60 are mounted on the hub members 20 and 30, one end side of the first arm member 70 is easily disposed at an appropriate position relative to one end side of the corresponding small-diameter roller 40, and one end side of the second arm member 80 is easily disposed at an appropriate position relative to the other end side of the corresponding small-diameter roller 40.

[0125] In the present embodiment, each support portion 60 supports the corresponding small-diameter roller 40, and one end side and the other end side in the axial direction of the corresponding small-diameter roller 40 are fixed to the first arm member 70 and the second arm member 80 by a single small-diameter roller bolt (fastening member) B1 extending along the axial direction of the corresponding small-diameter roller 40. With this structure, the force applied to the small-diameter roller 40 or the large-diameter roller 50 is easily transmitted to the adjacent plurality of small-diameter rollers 40 and large-diameter rollers 50 in sequence.

[0126] In addition, in the present embodiment, a pair of support portions 60 support the corresponding large-diameter roller 50, and the corresponding large-diameter roller 50 is fixed to the first arm member 70 and the second arm member 80 by a single large-diameter roller bolt B2 (fastening member) extending along the axial direction of the corresponding large-diameter roller 50. With this structure, the force applied to the small-diameter roller 40 or the large-diameter roller 50 is more easily transmitted to the adjacent plurality of small-diameter rollers 40 and large-diameter rollers 50.

[0127] In the present embodiment, when viewed in the direction extending from the rotation axis RL, the connecting portion 75 connecting the small-diameter roller support portion 71 and the large-diameter roller support portion 74 in the first arm member 70 extends mainly in the direction extending along the rotation axis RL2 of the corresponding large-diameter roller 50. With this structure, the force applied to the small-diameter roller 40 or the large-diameter roller 50 is more easily transmitted to the adjacent plurality of small-diameter rollers 40 and large-diameter rollers 50. In addition, this structure is beneficial to reducing the wall thickness of the connecting portion 75. In the present embodiment, the connecting portion 85 of the second arm member 80 also has the same structure and can achieve the same effect.

[0128] In the present embodiment, the other end side of the first arm member 70 and the other end side of the second arm member 80 overlap in a specified direction along the rotation axis RL. In addition, in the present embodiment, the first mounted portion 72 on the other end side of the first arm member 70 and the second mounted portion 82 on the other end side of the second arm member 80 overlap in a specified direction along the rotation axis RL, and the first mounted portion 72 and the second mounted portion 82 are mounted on the hub members 20 and 30. In addition, as described above, the force applied to the small-diameter roller 40 or the large-diameter roller 50 is more easily transmitted to the adjacent plurality of small-diameter rollers 40 and large-diameter rollers 50. Therefore, the omnidirectional wheel 1 of the present embodiment can not only reduce the number of components, but also withstand the forces applied to the small-diameter roller 40 and the large-diameter roller 50.

[0129] In addition, in the present embodiment, the single first mounted portion 72 and the single second mounted portion 82 overlap in a specified direction along the rotation axis RL. Therefore, even if the end faces of the first mounted portion 72 in the specified direction and the end faces of the second arm member 80 in the specified direction are not machined, the first mounted portion 72 and the second mounted portion 82 can be reliably mounted on the hub members 20 and 30. This results in a reduction in the manufacturing cost of each arm member 70 and 80.

[0130] Alternatively, a plurality of first mounted portions 72 may be provided on the first arm member 70, and a plurality of second mounted portions 82 may be provided on the second arm member 80, and the plurality of first mounted portions 72 and the plurality of second mounted portions 82 are alternately arranged along the specified direction.

[0131] In the present embodiment, the first mounted portion 72 is formed at a position offset in one direction in the specified direction from the center in the direction along the rotation axis RL in the first arm member 70. In addition, the second mounted portion 82 is formed at a position offset in the other direction in the specified direction from the center in the direction along the rotation axis RL in the second arm member 80. With this structure, not only can the size of the omnidirectional wheel 1 in the direction along the rotation axis RL be reduced, but also the strength of the first arm member 70 and the second arm member 80 mounted on the hub members 20 and 30 can be ensured.

[0132] In the present embodiment, holes 40a and 50a extending from the outer peripheral surface to the inner peripheral surface are formed in at least one of the plurality of rollers 40 and 50. In the present embodiment, the plurality of rollers 40 and 50 are connected in a ring shape by using the holes 40a and 50a.

[0133] The holes 40a and 50a may also be closed by bolt members 95 and 50b for plugging the holes 40a and 50a.

[0134] In the present embodiment, the at least one roller is the small-diameter roller 40, and one axial end side and the other axial end side of the small-diameter roller 40 are mounted on the support portion 60 by a single small-diameter roller bolt B1 extending along the axis of the small-diameter roller. A chamfer (engagement portion) 90 or a hole (engagement portion) 96 is formed at an axial position on the outer peripheral surface of the small-diameter roller bolt B1 corresponding to the hole 40a. Therefore, if the threaded member 94 is inserted into the hole 40a and the threaded member 94 engages with the chamfer 90 or the hole 96, the first roller bolt B1 is screwed into the first arm member 70 by rotating the first roller 40.

[0135] Next, the omnidirectional wheel 1 according to the second embodiment of the present invention will be described with reference to the drawings.

[0136] As Figure 17As shown, the omnidirectional wheel 1 of the second embodiment integrates the first arm member 70 and the second arm member 80 of the support portion 60 in the first embodiment. The same reference numerals are assigned to the same structural elements as in the first embodiment, and the description thereof is omitted.

[0137] In the omnidirectional wheel 1 of the first embodiment, the support portion 60 includes two components, namely, the first arm member 70 and the second arm member 80. Instead, in the omnidirectional wheel 1 of the second embodiment, the support portion 60 is a single component, and the support portion 60 includes the first arm 70 and the second arm 80. The first arm member 70 and the first arm 70 differ only in the shape of the base end side and a part of the shape of the distal end side, so they are denoted by the same reference numeral. In addition, the second arm member 80 and the second arm 80 differ only in the shape of the base end side and a part of the shape of the distal end side, so they are denoted by the same reference numeral.

[0138] The support portion 60 is formed of a metal such as aluminum and is formed by casting. The support portion 60 can also be formed by sintering metal powder. The support portion 60 can also be formed of a metal plate such as iron and is formed by stamping. The support portion 60 can also be formed of metal, plastic, or a combination of plastic and metal. The support portion 60 can also be formed of a metal such as aluminum or iron and is formed by forging.

[0139] As Figure 17 shown, in order to support one end side of the corresponding small-diameter roller 40 on one end side of the first arm 70, a small-diameter roller support portion 71 having the same holes 71a and base portions 71b as in the first embodiment is provided. An installation portion 61 for installing on the hub members 20 and 30 is provided on the other end side of the first arm 70.

[0140] The first arm 70 further includes: a base end side portion 73 that extends mainly along the axial direction of the corresponding small-diameter roller 40 from the installation portion 61; a large-diameter roller support portion 74 for supporting the large-diameter roller 50; and a connection portion 75 that connects the large-diameter roller support portion 74 and the small-diameter roller support portion 71.

[0141] The small-diameter roller bolt B1 is threadedly connected to the hole 71a provided in the small-diameter roller support portion 71, and a hole 74a through which the large-diameter roller bolt B2 passes is provided in the large-diameter roller support portion 74.

[0142] In the present embodiment, the plane including the center line of the hole 71a and the center line of the hole 74a passes through the center in a specified direction along the rotation axis RL in the first arm member 70. The installation portion 61 is disposed at a central position with respect to this center. In addition, the center in the width direction of the base end side portion 73 can also be the center in a specified direction along the rotation axis RL in the first arm member 70.

[0143] The end portion of the proximal end side portion 73 is mainly bent in a direction along the rotation axis RL2 of the corresponding large-diameter roller 50, and a large-diameter roller support portion 74 is provided at the end of the proximal end side portion 73. In the present embodiment, the large-diameter roller support portion 74 has: a base portion 74b that extends radially outward from the end of the proximal end side portion 73 toward the hub members 20 and 30; and a cylindrical portion 74c that extends from the base portion 74b or near the base portion 74b in a direction along the rotation axis RL2 of the corresponding large-diameter roller 50. The cylindrical portion 74c protrudes from the base portion 74b in a direction away from the mounted portion 61. In the present embodiment, the radial direction of the hub members 20 and 30 coincides with the radial direction of the omnidirectional wheel 1.

[0144] The inner diameter of the cylindrical portion 74c is slightly larger than the outer diameter on the other end side in the axial direction of the shaft 53 of the large-diameter roller 50. Or the inner diameter of the cylindrical portion 74c is equal to the outer diameter on the other end side in the axial direction of the shaft 53.

[0145] If the other end side in the axial direction of the shaft 53 of the corresponding large-diameter roller 50 is inserted into the cylindrical portion 74c, the end face of the cylindrical portion 74c is pressed against the inner ring of the bearing 54, whereby the inner ring of the bearing 54 is pressed against the step on the other end side of the shaft 53 of the corresponding large-diameter roller 50.

[0146] In addition, in some cases, the cylindrical portion 74c is not formed in the large-diameter roller support portion 74. In this case, a counterbore is provided in the base portion 74b, and the end portion of the shaft 53 is fitted into the counterbore. In some cases, the large-diameter roller support portion 74 has other structures capable of supporting the other end side of the corresponding large-diameter roller 50.

[0147] In the second embodiment, the small-diameter roller support portion 71 has: a base portion 71b that extends radially outward from the hub members 20 and 30; and a semi-cylindrical portion 71d that extends from the base portion 71b or near the base portion 71b in a direction along the rotation axis RL1 of the corresponding small-diameter roller 40. The semi-cylindrical portion 71d protrudes from the base portion 71b in a direction approaching the mounted portion 61. In the second embodiment, the semi-cylindrical portion 71d is provided instead of the cylindrical portion 71c in the first embodiment.

[0148] The inner diameter of the semi-cylindrical portion 71d is slightly larger than the outer diameter on one end side in the axial direction of the shaft 43 of the small-diameter roller 40. Or the inner diameter of the semi-cylindrical portion 71d is equal to the outer diameter on one end side in the axial direction of the shaft 43.

[0149] If the one end side in the axial direction of the shaft 43 of the corresponding small-diameter roller 40 is inserted into the semi-cylindrical portion 71d, the end face of the semi-cylindrical portion 71d is pressed against the inner ring of the bearing 44, whereby the inner ring of the bearing 44 is pressed against the step on one end side of the shaft 43 of the corresponding small-diameter roller 40.

[0150] In addition, in some cases, a semi-cylindrical portion 71d is not formed in the small-diameter roller support portion 71. In this case, a counterbore is provided in the base portion 71b, and the end portion of the shaft 43 is fitted into the counterbore. In some cases, the small-diameter roller support portion 71 has another structure capable of supporting the other end side of the corresponding small-diameter roller 40.

[0151] The connecting portion 75 connects the large-diameter roller support portion 74 and the small-diameter roller support portion 71. In the present embodiment, the connecting portion 75 connects the base portion 74b of the large-diameter roller support portion 74 and the base portion 71b of the small-diameter roller support portion 71. In addition, the connecting portion 75 may also connect other portions of the large-diameter roller support portion 74 and other portions of the small-diameter roller support portion 71.

[0152] When observed in the direction extending from the rotation axis RL, that is, when observing the first arm 70 as Figure 17 such, the connecting portion 75 mainly extends in the direction extending from the rotation axis RL2 of the corresponding large-diameter roller 50. The definition of the direction in which the connecting portion 75 extends is the same as that in the first embodiment.

[0153] When observed in the direction extending from the rotation axis RL, when the angle formed by the direction in which the connecting portion 75 extends and the direction in which the rotation axis RL2 extends is 30° or less, it can be said that the connecting portion 75 mainly extends in the direction extending from the rotation axis RL2. Preferably, when the angle formed by the direction in which the connecting portion 75 extends and the direction in which the rotation axis RL2 extends is 20° or less, it can be said that the connecting portion 75 mainly extends in the direction extending from the rotation axis RL2. More preferably, when the angle formed by the direction in which the connecting portion 75 extends and the direction in which the rotation axis RL2 extends is 15° or less, it can be said that the connecting portion 75 mainly extends in the direction extending from the rotation axis RL2.

[0154] As Figure 17 shown, on one end side of the second arm 80, a small-diameter roller support portion 81 for supporting one end side of the corresponding small-diameter roller 40 is provided, and on the other end side of the second arm 80, a mounting portion 61 common to the first arm 70 is provided.

[0155] The second arm 80 further has: a proximal end side portion 83 that mainly extends along the axial direction of the corresponding small-diameter roller 40 from the mounting portion 61; a large-diameter roller support portion 84 for supporting the large-diameter roller 50; and a connecting portion 85 that connects the large-diameter roller support portion 84 and the small-diameter roller support portion 81.

[0156] A hole 81a through which a small-diameter roller bolt B1, which will be described later, passes is provided in the small-diameter roller support portion 81, and a hole 84a for threadedly connecting a large-diameter roller bolt B2, which will be described later, is provided in the large-diameter roller support portion 84. In addition, when the hole 84a is not a female threaded hole, a nut is provided near the hole 84a. If the nut is formed of a material with a higher strength than aluminum, such as iron, the large-diameter roller 50 can be reliably fixed by the large-diameter roller bolt B2. The nut may also be inserted into a hole provided in the second arm member 80.

[0157] In the present embodiment, the plane including the center line of the hole 81a and the center line of the hole 84a passes through the center in the specified direction along the rotation axis RL in the second arm member 80. The mounted portion 61 is arranged at a position centered with respect to this center. In addition, the center in the width direction of the proximal end side portion 83 may also be the center in the specified direction along the rotation axis RL in the second arm member 80.

[0158] The end portion of the proximal end side portion 83 mainly bends in the direction along the rotation axis RL2 of the corresponding large-diameter roller 50, and a large-diameter roller support portion 84 is provided at the end of the proximal end side portion 83. In the present embodiment, the large-diameter roller support portion 84 has: a base portion 84b that extends radially outward from the end of the proximal end side portion 83 toward the hub members 20, 30; and a cylindrical portion 84c that extends in the direction along the rotation axis RL2 of the corresponding large-diameter roller 50 from the base portion 84b or near the base portion 84b. The cylindrical portion 84c projects from the base portion 84b in a direction away from the mounted portion 61.

[0159] The inner diameter of the cylindrical portion 84c is slightly larger than the outer diameter of one axial end side of the shaft 53 of the large-diameter roller 50. Or the inner diameter of the cylindrical portion 84c is equal to the outer diameter of one axial end side of the shaft 53.

[0160] If one axial end side of the shaft 53 corresponding to the large-diameter roller 50 is inserted into the cylindrical portion 84c, the end face of the cylindrical portion 84c is pressed against the inner ring of the bearing 54, whereby the inner ring of the bearing 54 is pressed against the step of one end side of the shaft 53 of the corresponding large-diameter roller 50.

[0161] In addition, in some cases, the cylindrical portion 84c is not formed in the large-diameter roller support portion 84. In this case, a counterbore is provided in the base portion 84b, and the end portion of the shaft 53 is inserted into the counterbore. In some cases, the large-diameter roller support portion 84 has another structure capable of supporting the other end side of the corresponding large-diameter roller 50.

[0162] In the second embodiment, the small-diameter roller support portion 81 has: a base portion 81b that extends radially outward of the hub members 20 and 30; and a semi-cylindrical portion 81d that extends from the base portion 81b or near the base portion 81b in a direction along the rotation axis RL1 of the corresponding small-diameter roller 40. The semi-cylindrical portion 81d protrudes from the base portion 81b in a direction approaching the mounting portion 61. In the second embodiment, the semi-cylindrical portion 81d is provided instead of the cylindrical portion 81c of the first embodiment.

[0163] The inner diameter of the semi-cylindrical portion 81d is slightly larger than the outer diameter on the other axial end side of the shaft 43 of the small-diameter roller 40. Or the inner diameter of the semi-cylindrical portion 81d is equal to the outer diameter on the other axial end side of the shaft 43.

[0164] If the other axial end side of the shaft 43 of the corresponding small-diameter roller 40 is inserted into the semi-cylindrical portion 81d, the end face of the semi-cylindrical portion 81d is pressed against the inner ring of the bearing 44, whereby the inner ring of the bearing 44 is pressed against the step on the other end side of the shaft 43 of the corresponding small-diameter roller 40.

[0165] In addition, in some cases, the semi-cylindrical portion 81d is not formed in the small-diameter roller support portion 81.

[0166] The connecting portion 85 connects the large-diameter roller support portion 84 and the small-diameter roller support portion 81. In the present embodiment, the connecting portion 85 connects the base portion 84b of the large-diameter roller support portion 84 and the base portion 81b of the small-diameter roller support portion 81. In addition, the connecting portion 85 may also connect other portions of the large-diameter roller support portion 84 and other portions of the small-diameter roller support portion 81.

[0167] When viewed in the direction extending from the rotation axis RL, that is, when viewing the second arm 80 as Figure 17 shown, the connecting portion 85 mainly extends in the direction along the rotation axis RL2 of the corresponding large-diameter roller 50. The definition of the direction in which the connecting portion 85 extends is the same as the definition of the direction in which the connecting portion 75 of the first arm 70 extends.

[0168] In the second embodiment, also when viewed in the direction extending from the rotation axis RL, the connecting portion 75 that connects the small-diameter roller support portion 71 and the large-diameter roller support portion 74 in the first arm member 70 mainly extends in the direction along the rotation axis RL2 of the corresponding large-diameter roller 50. With this structure, the force received by the small-diameter roller 40 or the large-diameter roller 50 is more easily transmitted to the adjacent plurality of small-diameter rollers 40 and large-diameter rollers 50. In addition, this structure is beneficial for reducing the wall thickness of the connecting portion 75. In the present embodiment, the connecting portion 85 of the second arm member 80 also has the same structure and can achieve the same effect.

[0169] In addition, in the first embodiment, as Figure 18As shown, the first mounted portion 72 of the first arm member 70 and the second mounted portion 82 of the second arm member 80 may not overlap in the direction along the rotation axis RL. In this case, the first mounted portion 72 and the second mounted portion 82 are respectively mounted to the hub members 20 and 30 using bolts B.

[0170] In addition, in the first embodiment, as Figure 19 shown, instead of the two hub members 20 and 30, a single hub member H may be used. In this case, the first mounted portion 72 of the first arm member 70 is disposed on one side in the thickness direction of the hub member H, and the second mounted portion 82 of the second arm member 80 is disposed on the other side in the thickness direction of the hub member H. Further, the first mounted portion 72 and the second mounted portion 82 are mounted to the hub member H using bolts B. Additionally, the first mounted portion 72 of the first arm member 70 and the second mounted portion 82 of the second arm member 80 may be disposed on one side in the thickness direction of the hub member H. In this case, the first mounted portion 72 and the second mounted portion 82 are also mounted to the hub member H using bolts B.

[0171] In addition, in the first embodiment, a mode in which each support portion 60 supports one small-diameter roller 40 is shown. Instead, it is also possible to configure the first arm member 70 and the second arm member 80 in such a way that each support portion 60 supports the small-diameter roller 50 as shown in Figure 20 and Figure 21 shown. In this case, the first arm member 70 supports one axial end side of the shaft 53 corresponding to the large-diameter roller 50, and the second arm member 80 supports the other axial end side of the shaft 53 corresponding to the large-diameter roller 50.

[0172] In addition, the corresponding small-diameter roller 40 among the plurality of small-diameter rollers 40 is supported by the first arm member 70 on one side and the second arm member 80 on the other side of two circumferentially adjacent support portions 60. For example, the first arm member 70 supports one axial end side of the shaft 43 corresponding to the small-diameter roller 40, and the second arm member 80 supports the other axial end side of the shaft 43 corresponding to the small-diameter roller 40.

[0173] As Figure 21As shown, in this modification, the first mounting portion 72 on the other end side of the first arm member 70 is longer, and the other structure of the first arm member 70 is the same as that of the first embodiment. That is, a hole 72a is provided in the first mounting portion 72, the proximal end side portion 73 extends along the axial direction of the small-diameter roller 40 from the first mounting portion 72, the large-diameter roller support portion 74 is provided at the end of the proximal end side portion 73, the small-diameter roller support portion 71 is provided on one end side of the first arm member 70, and a connecting portion 75 that connects the large-diameter roller support portion 74 and the small-diameter roller support portion 71 is formed. In addition, when viewed in the direction extending from the rotation axis RL, the connecting portion 75 extends mainly along the direction extending along the rotation axis RL2 of the corresponding large-diameter roller 50 in the same manner as in the first embodiment.

[0174] In addition, the second mounting portion 82 on the other end side of the second arm member 80 is longer, and the other structure of the second arm member 80 is the same as that of the first embodiment. That is, a hole 82a is provided in the second mounting portion 82, the proximal end side portion 83 extends along the axial direction of the small-diameter roller 40 from the second mounting portion 82, the large-diameter roller support portion 84 is provided at the end of the proximal end side portion 83, the small-diameter roller support portion 81 is provided on one end side of the second arm member 80, and a connecting portion 85 that connects the large-diameter roller support portion 84 and the small-diameter roller support portion 81 is formed. In addition, when viewed in the direction extending from the rotation axis RL, the connecting portion 85 extends mainly along the direction extending along the rotation axis RL2 of the corresponding large-diameter roller 50 in the same manner as in the first embodiment.

[0175] In addition, similar to the first embodiment, a hole 71a for screwing the small-diameter roller bolt B1 is formed in the small-diameter roller support portion 71, and a hole 74a through which the large-diameter roller bolt B2 passes is provided in the large-diameter roller support portion 74. Moreover, similar to the first embodiment, a hole 81a through which the small-diameter roller bolt B1 passes is provided in the small-diameter roller support portion 81, and a hole 84a for screwing the large-diameter roller bolt B2 is provided in the large-diameter roller support portion 84.

[0176] In the case of this modification, the large-diameter roller 50 is supported by the support portion 60 as the first roller, and the small-diameter roller 40 is supported by the support portion 60 as the second roller.

[0177] In the case of this modification, the large-diameter roller 50 is also supported not by a single component but by the first arm member 70 and the second arm member 80. In addition, for the small-diameter roller 40, one end side is supported by the second arm member 80 and the other end side is supported by the first arm member 70.

[0178] Therefore, compared with the case where the small-diameter roller 40 and the large-diameter roller 50 are supported by a single component, the force applied to the small-diameter roller 40 due to contact with the road surface can be easily transmitted to the adjacent large-diameter roller 50, and the force applied to the large-diameter roller 50 can be easily transmitted to the adjacent small-diameter roller 40. In addition, this modification can also achieve the other effects of the first embodiment.

[0179] In addition, in the first embodiment, as Figure 1 and Figure 13 shown, a part 76 of one end of the first arm member 70 is disposed between the axial end face 41b of the core member 41 of the small-diameter roller 40 and the axial end face 51e of the outer peripheral portion 51b of the core member 51 of the large-diameter roller 50.

[0180] In some cases, power cables, LAN cables, and other cables, as well as line bodies similar to these cables, exist on the ground in offices, indoor corridors, indoor passages, etc. In particular, these cables or line bodies exist under desks and the like.

[0181] Figure 5 As shown, the electric mobile device 100 is highly likely to travel on the ground where such cables and line bodies exist. Especially when the rider is working facing the desk, if the omnidirectional wheel 1 serving as the front wheel or the rear wheel is rotated, the omnidirectional wheel 1 may sometimes press on the cable or line body.

[0182] At this time, since a part 76 of the first arm member 70 is disposed between the end face 41b of the core member 41 of the small-diameter roller 40 and the end face 51e of the core member 51 of the large-diameter roller 50, it is not easy for a cable or line body to be caught between the small-diameter roller 40 and the large-diameter roller 50. If such a catching occurs, the cable or line body may be wound around the small-diameter roller 40 or the large-diameter roller 50. The above structure is advantageous for preventing or reducing such a failure.

[0183] In addition, as Figure 13 shown, a part 86 of one end of the second arm member 80 is also disposed between the end face 41b of the core member 41 of the small-diameter roller 40 and the end face 51e of the outer peripheral portion 51b of the core member 51 of the large-diameter roller 50.

[0184] In addition, in each of the above embodiments, as Figure 22 shown, in the inner side surface in the radial direction of the wheel of the base end side portion 83 of the second arm member 80, the central portion 83a in the width direction of the wheel bulges inward in the radial direction of the wheel. In the present embodiment, the radial direction of the wheel coincides with the radial direction of the hub members 20 and 30. In addition, in the present embodiment, the entire inner side surface bulges inward in the radial direction of the wheel. In addition, in the present embodiment, as Figure 9 shown, the central portion 83a bulges as described above over the entire length direction of the base end side portion 83.

[0185] A part of the inner side surface faces the inner peripheral surface of the outer peripheral part 51b of the large-diameter roller 50. Further, in the inner side surface, the distance between the central part 83a in the wheel width direction and the inner peripheral surface of the outer peripheral part 51b of the large-diameter roller 50, and the distance between the end part 83b in the wheel width direction and the inner peripheral surface of the outer peripheral part 51b are 1 mm or less. The central part 73a of the proximal end side part 73 of the first arm member 70 also bulges similarly to the central part 83a of the proximal end side part 83 of the second arm member 80, and the distance between the inner side surface of the proximal end side part 73 and the inner peripheral surface of the outer peripheral part 51b of the large-diameter roller 50 is also the same.

[0186] Therefore, even if the proximal end side parts 73 and 83 break at the Figure 22 section position shown or at a position closer to the large-diameter roller support parts 74 and 84 than this position, since the inner peripheral surface of the outer peripheral part 51b of the large-diameter roller 50 contacts the inner side surfaces of the proximal end side parts 73 and 83, the movement of the large-diameter roller 50 relative to the first arm member 70 and the second arm member 80 in the wheel radial direction and the movement in the wheel circumferential direction are restricted. For example, even after the proximal end side parts 73 and 83 break due to an unexpected load, a state where the fracture surfaces face each other is formed. In this way, the movement of the large-diameter roller 50 relative to the first arm member 70 and the second arm member 80 in the wheel circumferential direction can be restricted. If the distance between the central part 83a in the wheel width direction and the inner peripheral surface of the outer peripheral part 51b of the large-diameter roller 50 is 2 mm or less, this effect can be expected, but preferably the distance is 1.5 mm or less.

[0187] Further, the large-diameter roller support parts 74 and 84 sides of the proximal end side parts 73 and 83 are arranged in the concave part 55 of the large-diameter roller 50. Therefore, the large-diameter roller 50 is hooked on the proximal end side parts 73 and 83, and the large-diameter roller 50 can be prevented from coming off the omnidirectional wheel. In this case, even if the proximal end side parts 73 and 83 break due to an unexpected load, the omnidirectional wheel can be used for traveling.

[0188] Further, arranging a part of the large-diameter roller 50 between the hub members 20 and 30 as in the present embodiment also helps to prevent the large-diameter roller 50 from coming off the omnidirectional wheel.

[0189] Further, the large-diameter roller support parts 74 and 84 sides of the proximal end side parts 73 and 83 are arranged in the concave part 55 of the large-diameter roller 50, and the weakest parts of the proximal end side parts 73 and 83 are arranged in the concave part 55. In the present embodiment, the weakest part is the part with the smallest cross-sectional area in the proximal end side parts 73 and 83. With this structure, in the case where the proximal end side parts 73 and 83 break due to an unexpected load, it is beneficial to prevent the large-diameter roller 50 from coming off the omnidirectional wheel.

[0190] Description of reference numerals

[0191] 1 Omnidirectional wheel

[0192] 10 Axle

[0193] 20 and 30 Hub Components (Rotating Parts)

[0194] 40 Small-diameter Rollers (First Rollers)

[0195] 40a Hole

[0196] 41 Core Component

[0197] 43 Shaft

[0198] 50 Large-diameter Rollers (Second Rollers)

[0199] 50b Bolt Component

[0200] 51 Core Component

[0201] 53 Shaft

[0202] 60 Support Portion

[0203] 61 Mounted Portion

[0204] 70 First Arm Component, First Arm

[0205] 71 Small-diameter Roller Support Portion

[0206] 72 First Mounted Portion

[0207] 73 Base End Side Portion

[0208] 73a Central Portion

[0209] 73b End Portion

[0210] 74 Large-diameter Roller Support Portion

[0211] 75 Connection Portion

[0212] 80 Second Arm Component, Second Arm

[0213] 81 Small-diameter Roller Support Portion

[0214] 82 Second Mounted Portion

[0215] 83 Base End Side Portion

[0216] 83a Central Portion

[0217] 83b End Portion

[0218] 84 Large-diameter Roller Support Portion

[0219] 85 Connection Portion

[0220] 90 Chamfer (Engagement Portion)

[0221] 91 First Flat Portion

[0222] 92 Second planar part

[0223] 93 Curved surface part

[0224] 94 Threaded part

[0225] 95 Bolt part

[0226] 96 Hole

[0227] 97 Fixing part

[0228] RL, RL1, RL2 Rotation axes.

Claims

1. An omnidirectional wheel, the outer peripheral surface of which is formed by a plurality of rollers and rotates around the axis of rotation of the axle, wherein, The omnidirectional wheel includes: A rotating part that rotates around the axis of rotation of the axle; and A plurality of supporting parts arranged along the circumferential direction of the rotating part and respectively mounted on the rotating part to support the plurality of rollers on the rotating part, The plurality of rollers include a plurality of small-diameter rollers and a plurality of large-diameter rollers, and the outer diameter of the large-diameter rollers is larger than the outer diameter of the small-diameter rollers, The small-diameter rollers and the large-diameter rollers are alternately arranged along the circumferential direction, Each of the supporting parts has a first arm and a second arm. The first arm supports one axial end side of the corresponding small-diameter roller among the plurality of small-diameter rollers, and the second arm supports the other axial end side of the corresponding small-diameter roller, The corresponding large-diameter roller among the plurality of large-diameter rollers is supported by the first arm of one of the two adjacent supporting parts along the circumferential direction and the second arm of the other, In the first arm, the large-diameter roller supporting part that supports the corresponding large-diameter roller is arranged closer to the inner side in the radial direction of the rotating part than the small-diameter roller supporting part that supports the one axial end side of the corresponding small-diameter roller, In at least one of the plurality of rollers, a hole extending from the outer peripheral surface to the inner peripheral surface of the roller is formed, One axial end side and the other axial end side of the corresponding small-diameter roller are mounted on the supporting part by a bolt extending along the axial direction of the corresponding small-diameter roller, An engaging part is formed at an axial position on the outer peripheral surface of the bolt corresponding to the hole.

2. The omnidirectional wheel according to claim 1, wherein, The hole is closed by a bolt member for plugging the hole.

3. The omnidirectional wheel according to claim 1, wherein, On the outer peripheral surface of the bolt, a first flat portion, a second flat portion and a curved surface portion are formed as the engaging part. The second flat portion and the first flat portion are different in the circumferential position on the outer peripheral surface of the bolt, and the curved surface portion connects between the first flat portion and the second flat portion.

4. The omnidirectional wheel according to claim 1, wherein, Internal threads are formed in the hole.

5. An omnidirectional wheel, the outer peripheral surface of which is formed by a plurality of rollers and rotates around the axis of rotation of the axle, wherein, The omnidirectional wheel includes: A rotating part that rotates around the axis of rotation of the axle; and A plurality of supporting parts arranged along the circumferential direction of the rotating part and respectively mounted on the rotating part to support the plurality of rollers on the rotating part, The plurality of rollers include a plurality of small-diameter rollers and a plurality of large-diameter rollers, and the outer diameter of the large-diameter rollers is larger than the outer diameter of the small-diameter rollers, The small-diameter rollers and the large-diameter rollers are alternately arranged along the circumferential direction, Each of the supporting parts has a first arm and a second arm. The first arm supports one axial end side of the corresponding small-diameter roller among the plurality of small-diameter rollers, and the second arm supports the other axial end side of the corresponding small-diameter roller, The corresponding large-diameter roller among the plurality of large-diameter rollers is supported by the first arm of one of the two adjacent supporting parts along the circumferential direction and the second arm of the other, In the first arm, the large-diameter roller support portion that supports the corresponding large-diameter roller is arranged closer to the inner side in the radial direction of the rotating portion than the small-diameter roller support portion on the one axial end side that supports the corresponding small-diameter roller. In at least one of the plurality of rollers, a hole extending from the outer peripheral surface to the inner peripheral surface of the roller is formed. At both axial ends of the large-diameter roller, recesses are formed for respectively receiving a part of both axial ends of the small-diameter roller. One axial end side and the other axial end side of the corresponding small-diameter roller are mounted on the support portion by a single bolt extending along the axial direction of the corresponding small-diameter roller. A hole extending from the outer peripheral surface of the large-diameter roller to the recess of the large-diameter roller is formed near the head of the bolt.

6. An omnidirectional wheel, the outer peripheral surface of which is formed by a plurality of rollers and rotates around an axle rotation axis, wherein the omnidirectional wheel includes: a rotating portion that rotates around the axle rotation axis; and a plurality of support portions that are arranged along the circumferential direction of the rotating portion and are respectively mounted on the rotating portion to support the plurality of rollers on the rotating portion, the plurality of rollers include a plurality of small-diameter rollers and a plurality of large-diameter rollers, and the outer diameter of the large-diameter roller is larger than the outer diameter of the small-diameter roller, the small-diameter rollers and the large-diameter rollers are alternately arranged along the circumferential direction, each of the support portions has a first arm and a second arm, the first arm supports one axial end side of the corresponding small-diameter roller among the plurality of small-diameter rollers, and the second arm supports the other axial end side of the corresponding small-diameter roller, the corresponding large-diameter roller among the plurality of large-diameter rollers is supported by the first arm of one of the two adjacent support portions along the circumferential direction and the second arm of the other, In the first arm, the large-diameter roller support portion that supports the corresponding large-diameter roller is arranged closer to the inner side in the radial direction of the rotating portion than the small-diameter roller support portion on the one axial end side that supports the corresponding small-diameter roller. In at least one of the plurality of rollers, a hole extending from the outer peripheral surface to the inner peripheral surface of the roller is formed. One axial end side and the other axial end side of the corresponding small-diameter roller are mounted on the support portion by a single bolt extending along the axial direction of the corresponding small-diameter roller. An engaging portion is formed at an axial position on the outer peripheral surface of the bolt corresponding to the hole. The first arm has a connecting portion that connects the large-diameter roller support portion and the small-diameter roller support portion. The direction in which the connecting portion of the first arm extends forms an angle of 20° or less with the direction in which the rotation axis of the corresponding large-diameter roller extends.

7. An omnidirectional wheel, the outer peripheral surface of which is formed by a plurality of rollers and rotates around an axle rotation axis, wherein the omnidirectional wheel includes: a rotating portion that rotates around the axle rotation axis; and a plurality of support portions that are arranged along the circumferential direction of the rotating portion and are respectively mounted on the rotating portion to support the plurality of rollers on the rotating portion, the plurality of rollers include a plurality of small-diameter rollers and a plurality of large-diameter rollers, and the outer diameter of the large-diameter roller is larger than the outer diameter of the small-diameter roller, the small-diameter rollers and the large-diameter rollers are alternately arranged along the circumferential direction, Each of the support portions has a first arm and a second arm. The first arm supports one axial end side of a corresponding small-diameter roller among the plurality of small-diameter rollers, and the second arm supports the other axial end side of the corresponding small-diameter roller. A corresponding large-diameter roller among the plurality of large-diameter rollers is supported by the first arm of one of the two support portions adjacent to each other along the circumferential direction and the second arm of the other. In the first arm, a large-diameter roller support portion that supports the corresponding large-diameter roller is arranged closer to the radially inner side of the rotating portion than a small-diameter roller support portion that supports the one axial end side of the corresponding small-diameter roller. At least one of the plurality of rollers has a hole extending from the outer peripheral surface of the roller to the inner peripheral surface. The one axial end side and the other axial end side of the corresponding small-diameter roller are mounted on the support portion by a single bolt extending along the axial direction of the corresponding small-diameter roller. An engaging portion is formed at an axial position on the outer peripheral surface of the bolt corresponding to the hole. The first arm has a proximal end side portion mainly extending along the axial direction of the corresponding small-diameter roller. The proximal end side portion connects a mounted portion mounted on the rotating portion to the large-diameter roller support portion. A part of the radially inner side surface in the proximal end side portion faces the inner peripheral surface of the corresponding large-diameter roller. The central portion in the wheel width direction of the part of the inner side surface bulges toward the radially inner side.

8. An omnidirectional wheel, the outer peripheral surface of which is formed by a plurality of rollers and which rotates around an axle rotation axis, wherein the omnidirectional wheel includes: a rotating portion that rotates around the axle rotation axis; and a plurality of support portions arranged along the circumferential direction of the rotating portion and respectively mounted on the rotating portion to support the plurality of rollers on the rotating portion, the plurality of rollers include a plurality of small-diameter rollers and a plurality of large-diameter rollers, and the outer diameter of the large-diameter rollers is larger than the outer diameter of the small-diameter rollers, the small-diameter rollers and the large-diameter rollers are arranged alternately along the circumferential direction, each of the support portions has a first arm and a second arm. The first arm supports one axial end side of a corresponding small-diameter roller among the plurality of small-diameter rollers, and the second arm supports the other axial end side of the corresponding small-diameter roller. A corresponding large-diameter roller among the plurality of large-diameter rollers is supported by the first arm of one of the two support portions adjacent to each other along the circumferential direction and the second arm of the other. In the first arm, a large-diameter roller support portion that supports the corresponding large-diameter roller is arranged closer to the radially inner side of the rotating portion than a small-diameter roller support portion that supports the one axial end side of the corresponding small-diameter roller. At least one of the plurality of rollers has a hole extending from the outer peripheral surface of the roller to the inner peripheral surface. The one axial end side and the other axial end side of the corresponding small-diameter roller are mounted on the support portion by a single bolt extending along the axial direction of the corresponding small-diameter roller. An engaging portion is formed at an axial position on the outer peripheral surface of the bolt corresponding to the hole. The first arm has a proximal end side portion mainly extending along the axial direction of the corresponding small-diameter roller. The proximal end side portion connects a mounted portion mounted on the rotating portion to the large-diameter roller support portion. A part of the inner side surface in the radial direction in the proximal end side portion faces the inner peripheral surface of the corresponding large-diameter roller. The distance between the part of the inner side surface and the inner peripheral surface of the corresponding large-diameter roller is 2 mm or less.

9. An omnidirectional wheel, the outer peripheral surface of which is formed by a plurality of rollers and rotates around an axle rotation axis, wherein the omnidirectional wheel includes: a rotating part that rotates around the axle rotation axis; and a plurality of supporting parts that are arranged along the circumferential direction of the rotating part and are respectively mounted on the rotating part to support the plurality of rollers on the rotating part, the plurality of rollers include a plurality of small-diameter rollers and a plurality of large-diameter rollers, and the outer diameter of the large-diameter rollers is larger than the outer diameter of the small-diameter rollers, the small-diameter rollers and the large-diameter rollers are alternately arranged along the circumferential direction, each of the supporting parts has a first arm and a second arm, the first arm supports one axial end side of the corresponding small-diameter roller among the plurality of small-diameter rollers, and the second arm supports the other axial end side of the corresponding small-diameter roller, the corresponding large-diameter roller among the plurality of large-diameter rollers is supported by the first arm of one of the two adjacent supporting parts along the circumferential direction and the second arm of the other, in the first arm, the large-diameter roller supporting part that supports the corresponding large-diameter roller is arranged closer to the inner side in the radial direction of the rotating part than the small-diameter roller supporting part that supports one axial end side of the corresponding small-diameter roller, in at least one of the plurality of rollers, a hole is formed that extends from the outer peripheral surface of the roller to the inner peripheral surface, one axial end side and the other axial end side of the corresponding small-diameter roller are mounted on the supporting part by a single bolt that extends along the axial direction of the corresponding small-diameter roller, an engaging part is formed at an axial position on the outer peripheral surface of the bolt corresponding to the hole, the first arm has a proximal end side portion that mainly extends along the axial direction of the corresponding small-diameter roller, the proximal end side portion connects the mounted part mounted on the rotating part and the large-diameter roller supporting part, a part of the inner side surface in the radial direction in the proximal end side portion faces the inner peripheral surface of the corresponding large-diameter roller, the large-diameter roller supporting part side in the proximal end side portion is arranged in a recess formed at the end of the corresponding large-diameter roller, the weakest part in the proximal end side portion is arranged in the recess.

10. An omnidirectional wheel, the outer peripheral surface of which is formed by a plurality of rollers and rotates around an axle rotation axis, wherein the omnidirectional wheel includes: a rotating part that rotates around the axle rotation axis; and a plurality of supporting parts that are arranged along the circumferential direction of the rotating part and are respectively mounted on the rotating part to support the plurality of rollers on the rotating part, the plurality of rollers include a plurality of small-diameter rollers and a plurality of large-diameter rollers, and the outer diameter of the large-diameter rollers is larger than the outer diameter of the small-diameter rollers, the small-diameter rollers and the large-diameter rollers are alternately arranged along the circumferential direction, each of the supporting parts has a first arm and a second arm, the first arm supports one axial end side of the corresponding small-diameter roller among the plurality of small-diameter rollers, and the second arm supports the other axial end side of the corresponding small-diameter roller, the corresponding large-diameter roller among the plurality of large-diameter rollers is supported by the first arm of one of the two adjacent supporting parts along the circumferential direction and the second arm of the other, In the first arm, the large-diameter roller support portion that supports the corresponding large-diameter roller is disposed closer to the radially inner side of the rotating portion than the small-diameter roller support portion on the one axial end side that supports the corresponding small-diameter roller. In at least one of the plurality of rollers, a hole extending from the outer peripheral surface to the inner peripheral surface of the roller is formed. One axial end side and the other axial end side of the corresponding small-diameter roller are mounted to the support portion by a single bolt extending along the axial direction of the corresponding small-diameter roller. An engaging portion is formed at an axial position on the outer peripheral surface of the bolt corresponding to the hole. The small-diameter roller or the large-diameter roller has a substantially cylindrical core member, an outer peripheral member bonded to the outer peripheral surface of the core member, and a shaft disposed in a hole formed in the core member. The hole of the core member extends along the axial direction of the small-diameter roller or the large-diameter roller.

11. The omnidirectional wheel according to claim 10, wherein The core member is supported by the shaft via a bearing and rotates relative to the shaft about the rotation axis. Steps for abutting the bearing are respectively formed on the inner peripheral surface of the hole of the core member and the outer peripheral surface of the shaft.

12. An omnidirectional wheel, the outer peripheral surface of which is formed by a plurality of rollers and rotates about an axle rotation axis, wherein The omnidirectional wheel includes: A rotating portion that rotates about the axle rotation axis; and A plurality of support portions arranged along the circumferential direction of the rotating portion and respectively mounted to the rotating portion to support the plurality of rollers on the rotating portion, The plurality of rollers include a plurality of small-diameter rollers and a plurality of large-diameter rollers, and the outer diameter of the large-diameter roller is larger than the outer diameter of the small-diameter roller. The small-diameter rollers and the large-diameter rollers are alternately arranged along the circumferential direction. Each of the support portions has a first arm and a second arm. The first arm supports one axial end side of the corresponding small-diameter roller among the plurality of small-diameter rollers, and the second arm supports the other axial end side of the corresponding small-diameter roller. The corresponding large-diameter roller among the plurality of large-diameter rollers is supported by the first arm of one of the two adjacent support portions along the circumferential direction and the second arm of the other. In the first arm, the large-diameter roller support portion that supports the corresponding large-diameter roller is disposed closer to the radially inner side of the rotating portion than the small-diameter roller support portion on the one axial end side that supports the corresponding small-diameter roller. In at least one of the plurality of rollers, a hole extending from the outer peripheral surface to the inner peripheral surface of the roller is formed. One axial end side and the other axial end side of the corresponding small-diameter roller are mounted to the support portion by a single bolt extending along the axial direction of the corresponding small-diameter roller. An engaging portion is formed at an axial position on the outer peripheral surface of the bolt corresponding to the hole. Holes for threadedly connecting fastening members are provided in the large-diameter roller support portion and the small-diameter roller support portion.

13. An omnidirectional wheel, the outer peripheral surface of which is formed by a plurality of rollers and rotates about an axle rotation axis, wherein The omnidirectional wheel includes: A rotating portion that rotates about the axle rotation axis; and A plurality of support portions arranged along the circumferential direction of the rotating portion and respectively mounted to the rotating portion to support the plurality of rollers on the rotating portion. The plurality of rollers includes a plurality of small-diameter rollers and a plurality of large-diameter rollers, and an outer diameter of the large-diameter rollers is larger than an outer diameter of the small-diameter rollers. The small-diameter rollers and the large-diameter rollers are alternately arranged along the circumferential direction. Each of the support portions has a first arm and a second arm. The first arm supports one axial end side of a corresponding small-diameter roller among the plurality of small-diameter rollers, and the second arm supports the other axial end side of the corresponding small-diameter roller. A corresponding large-diameter roller among the plurality of large-diameter rollers is supported by the first arm of one of two circumferentially adjacent support portions and the second arm of the other. In the first arm, a large-diameter roller support portion that supports the corresponding large-diameter roller is arranged closer to a radially inner side of the rotating portion than a small-diameter roller support portion that supports the one axial end side of the corresponding small-diameter roller. A hole extending from an outer peripheral surface to an inner peripheral surface of at least one roller among the plurality of rollers is formed. The one axial end side and the other axial end side of the corresponding small-diameter roller are mounted on the support portion by a single bolt extending along an axis of the corresponding small-diameter roller. An engaging portion is formed at an axial position on an outer peripheral surface of the bolt corresponding to the hole. A first hole through which a small-diameter roller bolt passes is provided in the small-diameter roller support portion of one of the first arm and the second arm, and a second hole for threaded connection of a large-diameter roller bolt is provided in the large-diameter roller support portion of one of the first arm and the second arm. The small-diameter roller bolt is threadedly connected to a third hole provided in the small-diameter roller support portion of the other of the first arm and the second arm, and a fourth hole through which the large-diameter roller bolt passes is provided in the large-diameter roller support portion of the other of the first arm and the second arm. The second hole and / or the third hole is a female threaded hole, or a nut is provided in the second hole and / or the third hole.

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