Bicycle power transmission device

Abstract

The invention provides a bicycle power transmission device which can stably perform riveting processing. The crank arm rotates integrally with the first rotating body. The first rotating body has a hub portion and a flange portion. The hub portion extends in an axial direction. The flange portion extends radially outward from the hub portion. The crank arm has a mounting portion and an arm body portion. The attachment portion is attached to the hub portion. The arm body portion extends radially outward from the attachment portion. The mounting portion has a mounting body portion and a tip portion. The mounting body portion is in contact with the hub portion in the axial direction. The front end portion extends in the axial direction from the mounting body portion. The front end portion has an outer diameter smaller than an outer diameter of the mounting body portion. The front end portion is riveted to the hub portion. The mounting body portion has an outer diameter larger than an outer diameter of the hub portion.

Description

Technical Field

[0001] This invention relates to a power transmission device for bicycles. Background Technology

[0002] Patent Document 1 discloses a power transmission device for bicycles. The power transmission device for bicycles includes a first rotating body and a second rotating body. The first rotating body and the second rotating body are elastically connected by a coil spring. A crank arm is mounted on the hub of the first rotating body.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2024-084007 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] The crank arm is riveted to the hub of the first rotating body. The technical problem of this invention is to provide a bicycle power transmission device capable of stable riveting.

[0008] Technical solutions for solving technical problems

[0009] The first embodiment relates to a bicycle power transmission device comprising a first rotating body, a second rotating body, an elastic member, and a crank arm. The second rotating body is configured to rotate relative to the first rotating body. The elastic member elastically connects the first rotating body and the second rotating body. The crank arm rotates integrally with the first rotating body. The first rotating body has a hub and a flange. The hub extends axially. The flange extends radially outward from the hub. The crank arm has a mounting portion and an arm body portion. The mounting portion is mounted to the hub. The arm body portion extends radially outward from the mounting portion. The mounting portion has a mounting body portion and a front end portion. The mounting body portion abuts against the hub axially. The front end portion extends axially from the mounting body portion. The front end portion has an outer diameter smaller than the outer diameter of the mounting body portion. The front end portion is riveted to the hub. The mounting body portion has an outer diameter larger than the outer diameter of the hub.

[0010] According to this structure, since the outer diameter of the mounting body is larger than the outer diameter of the hub, when the front end of the mounting part is riveted to the hub, the mounting body becomes a base, and the riveting process for riveting the front end to the hub can be performed stably.

[0011] The second embodiment of the bicycle power transmission device is configured as follows in the first embodiment: The hub has a hub body and a small-diameter portion. The hub body extends axially. The hub body is cylindrical. The small-diameter portion is cylindrical. The small-diameter portion has an inner diameter smaller than the inner diameter of the hub body. The front end of the mounting portion is riveted to the small-diameter portion.

[0012] The third embodiment of the bicycle power transmission device is configured in the second embodiment as follows: The hub has a plurality of protrusions and a plurality of clearance portions. Each protrusion extends axially on the inner circumferential surface of the small-diameter portion. Each clearance portion is formed at at least one end of each protrusion along its axial direction.

[0013] The fourth embodiment of the bicycle power transmission device, in any of the first to third embodiments, further includes a fastening member. The second rotating body has a first plate and a second plate. The first plate is disposed on a first side of the axial direction relative to the flange portion. The second plate is disposed on a second side of the axial direction relative to the flange portion. The fastening member detachably fastens the first and second plates. The arm body portion is configured not to overlap with the fastening member when viewed axially.

[0014] The bicycle power transmission device according to the fifth embodiment is configured as follows, in accordance with the bicycle power transmission device according to the fourth embodiment: The fastening member has a stop portion, a first screw portion, and a second screw portion. The stop portion is disposed between a first plate and a second plate. The first screw portion is disposed on a first side in the axial direction relative to the first plate. The second screw portion is disposed on a second side in the axial direction relative to the second plate.

[0015] Invention Effects

[0016] According to the present invention, riveting processes can be performed stably. Attached Figure Description

[0017] Figure 1 This is a cross-sectional view of the power transmission device for a bicycle.

[0018] Figure 2 This is a front view of the power transmission device for a bicycle.

[0019] Figure 3 This is the front view of the first solid of revolution.

[0020] Figure 4 yes Figure 3 Sectional view along line IV-IV.

[0021] Figure 5 This is a side view of the stop component.

[0022] Figure 6 It is an enlarged sectional view of the first rotating body and crank arm before riveting.

[0023] Figure 7 It is an enlarged sectional view of the first rotating body and crank arm after riveting. Detailed Implementation

[0024] Hereinafter, a bicycle power transmission device 100 (hereinafter also simply referred to as power transmission device 100) according to this embodiment will be described with reference to the accompanying drawings. It should be noted that, in the following description, axial direction refers to the direction in which the rotation axis O of the power transmission device 100 extends. Furthermore, circumferential direction refers to the circumferential direction of the circle centered on the rotation axis O, and radial direction refers to the radial direction of the circle centered on the rotation axis O. The first side of the axial direction is indicated by... Figure 1 The left side, the second side of the axis represents Figure 1 The right side. Additionally, the rotation direction R refers to the direction in which the power transmission device 100 rotates when the bicycle equipped with the power transmission device 100 is in motion. The rotation direction R is... Figure 2 The clockwise direction.

[0025] Figure 1 This is a cross-sectional view of the power transmission device 100. (For example...) Figure 1 As shown, the power transmission device 100 includes a first rotating body 2, a second rotating body 3, a plurality of helical springs 4 (an example of elastic components), a plurality of stop components (an example of fastening components) 5, a sprocket 6, a crank arm 7, a plurality of first nuts 8, and a plurality of second nuts 9. The power transmission device 100 is configured to rotate about a rotation axis O.

[0026] The power transmission device 100 is mounted on a bicycle. The power transmission device 100 is mounted, for example, on a bicycle without an electric motor, i.e., a bicycle driven solely by human power. It should be noted that the power transmission device 100 can also be mounted on a bicycle with an electric motor. In this case, for example, the bicycle may have an electric mode driven solely by the electric motor and a human-powered mode driven solely by human power. It should be noted that the bicycle may have an auxiliary mode driven by both an electric motor and human power, or it may not have an auxiliary mode. The power transmission device 100 is configured to transmit torque input to the pedal (not shown) mounted on the front end of the crank arm 7 to the drive wheel (not shown).

[0027] Figure 2 This is a front view of the power transmission device 100 with several helical springs 4, crank arms 7, and the second plate 32 of the second rotating body 3 (described later) removed. Figure 2 As shown, the power transmission device 100 is configured to operate along the rotational direction R ( Figure 2 (rotate clockwise).

[0028] <First Rotational Body>

[0029] Figure 3 This is the front view of the first rotating body 2. Figure 4 yes Figure 3 A cross-sectional view along line IV-IV. (See attached image.) Figure 3 as well as Figure 4 As shown, the first rotating body 2 has a plurality of receiving holes 21. It should be noted that, in this embodiment, the first rotating body 2 has three receiving holes 21. Each receiving hole 21 extends axially. Each receiving hole 21 is spaced apart circumferentially. Each receiving hole 21 is equally spaced.

[0030] The first rotating body 2 has a plurality of abutting surfaces 27. Abutting surfaces 27 are surfaces that abut against the coil spring 4. Specifically, the abutting surfaces 27 are the surfaces that define the receiving holes 21 and abut against the end face of the coil spring 4. That is, each receiving hole 21 of the first rotating body 2 has a pair of abutting surfaces 27. The pair of abutting surfaces 27 are circumferentially oriented and opposite each other.

[0031] The first rotating body 2 is configured to rotate in the direction of rotation R. The first rotating body 2 receives torque from the crank arm 7. The first rotating body 2 is configured to rotate integrally with the crank arm 7. The first rotating body 2 has a hub 22 and a flange 23.

[0032] The hub 22 is a cylindrical shape that extends axially. When the power transmission device 100 is mounted on the bicycle, the crankshaft (not shown) extends within the hub 22.

[0033] The hub portion 22 has a hub body portion 221 and a small-diameter portion 222. The hub body portion 221 is a cylindrical shape extending axially. The small-diameter portion 222 is disposed at the end of the hub portion 22. Specifically, the small-diameter portion 222 is disposed at the end of the hub portion 22 on a second axial side. The small-diameter portion 222 is a cylindrical shape extending axially. The small-diameter portion 222 has an inner diameter smaller than the inner diameter of the hub body portion 221.

[0034] Flange 23 extends radially outward from hub 22. A receiving hole 21 is formed in this outer flange 23. The receiving hole 21 extends axially through flange 23. Flange 23 is formed at the axial center of hub 22. The position of flange 23 differs axially from the position of minor diameter portion 222. That is, when viewed axially, minor diameter portion 222 overlaps with flange 23.

[0035] Flange 23 is inclined axially. Specifically, flange 23 is inclined to a second axial side. Flange 23 is inclined in such a way that the closer it is to the radially outer side, the closer it is to the second plate 32. Flange 23 is inclined away from the first plate 31 on which the sprocket 6 is mounted. In addition, flange 23 is inclined toward the crank arm 7.

[0036] The flange portion 23 has a flange body portion 231 and an inclined portion 232. The flange body portion 231 extends radially outward from the hub portion 22. The flange body portion 231 is not inclined axially. That is, the flange body portion 231 extends substantially parallel to a plane orthogonal to the rotation axis O. The flange body portion 231 is annular in the circumferential direction.

[0037] The inclined portion 232 extends radially outward from the outer peripheral end of the flange body portion 231. The inclined portion 232 is inclined axially. More specifically, the inclined portion 232 is inclined to a second axial side. Thus, in the flange portion 23, the flange body portion 231 is not inclined, while the inclined portion 232 is inclined axially. The inclined portion 232 corresponds to the outer peripheral portion of the flange portion 23. The inclined portion 232 is annular, extending circumferentially. The inclination angle α of the inclined portion 232 is not particularly limited, and can be, for example, approximately 1 to 5°. It should be noted that the inclination angle α is the angle formed between the plane orthogonal to the rotation axis O and the inclined portion 232.

[0038] Figure 4 Line L indicates the boundary between the flange body 231 and the inclined portion 232. A receiving hole 21 is formed throughout the flange body 231 and the inclined portion 232. Therefore, the abutment surface 27 extends throughout the flange body 231 and the inclined portion 232. The end face of the helical spring 4 abuts against the flange body 231 and the inclined portion 232.

[0039] The hub portion 22 has a plurality of protrusions 24 and a plurality of clearance portions 28. Each protrusion 24 is formed on the inner circumferential surface of the small-diameter portion 222 of the hub portion 22. That is, the small-diameter portion 222 has each protrusion 24. Each protrusion 24 extends axially. Each protrusion 24 is arranged circumferentially. Each protrusion 24 forms a spline hole 241 in the hub portion 22.

[0040] Each clearance portion 28 is formed at the end of the corresponding protrusion 24 on the second side of the axial direction. The clearance portion 28 is formed by cutting off the end of the protrusion 24 on the second side of the axial direction. The clearance portion 28 is configured to accommodate burrs generated during the formation of each protrusion 24. That is, the clearance portion 28 is configured to accommodate space. Since the clearance portion 28 accommodates the burrs generated during the formation of each protrusion 24, it is possible to suppress the generation of burrs from the hub portion 22 on the second side of the axial direction.

[0041] The first rotating body 2 has a plurality of stop surfaces 25. Specifically, the first rotating body 2 has a plurality of cutouts 26. Each cutout 26 is arranged at intervals along the circumference. The cutouts 26 are arranged circumferentially between a pair of receiving holes 21. Each cutout 26 opens radially outward. The surface of the inner wall of the cutout 26 facing the direction of rotation R is defined as the stop surface 25.

[0042] The stop surface 25 faces circumferentially. More specifically, the stop surface 25 faces the rotation direction R. The stop surface 25 is circumferentially spaced from the stop portion 51.

[0043] The first rotating body 2 can be constructed, for example, from iron, stainless steel, carbon fiber reinforced plastic (CFRP), etc.

[0044] <Second Rotational Body>

[0045] like Figure 1 As shown, the second rotating body 3 is configured to rotate in the rotation direction R. The second rotating body 3 is configured to rotate relative to the first rotating body 2. The second rotating body 3 has a first plate 31 and a second plate 32. The first plate 31 and the second plate 32 are configured to rotate integrally with each other. The first plate 31 and the second plate 32 are configured to rotate relative to the flange portion 23.

[0046] The first plate 31 and the second plate 32 are arranged with a gap between them in the axial direction. A first rotating body 2 is disposed between the first plate 31 and the second plate 32. That is, the first plate 31 and the second plate 32 are arranged to sandwich the first rotating body 2 in the axial direction. Specifically, the flange portion 23 of the first rotating body 2 is disposed in the axial direction between the first plate 31 and the second plate 32. The first plate 31 is disposed on a first side in the axial direction relative to the flange portion 23. The second plate 32 is disposed on a second side in the axial direction relative to the flange portion 23.

[0047] The first plate 31 is circular and has an opening in the center. The hub 22 of the first rotating body 2 extends axially within the opening of the first plate 31.

[0048] The first plate 31 has a plurality of first windows 311. In this embodiment, the first plate 31 has three first windows 311. The first windows 311 extend through the first plate 31 axially. The first windows 311 are arranged circumferentially spaced apart from each other.

[0049] The first plate 31 has a plurality of first through holes 312. The first through holes 312 are arranged at intervals from each other in the circumferential direction. In the circumferential direction, the first windows 311 and the first through holes 312 are arranged alternately.

[0050] The second plate 32 is circular and has an opening in the center. The hub 22 of the first rotating body 2 extends axially within the opening of the second plate 32. The second plate 32 is configured to rotate integrally with the first plate 31. Specifically, the first plate 31 and the second plate 32 are fastened to each other by a plurality of stop members 5.

[0051] The second plate 32 has a plurality of second windows 321. In this embodiment, the second plate 32 has three second windows 321. The second windows 321 extend through the second plate 32 axially. The second windows 321 are spaced apart from each other in the circumferential direction. When viewed axially, each second window 321 overlaps with its corresponding first window 311.

[0052] The second plate 32 has a plurality of second through holes 322. The second through holes 322 are arranged at intervals from each other in the circumferential direction. In the circumferential direction, the second windows 321 and the second through holes 322 are arranged alternately. When viewed in the axial direction, each second through hole 322 overlaps with the corresponding first through hole 312.

[0053] The first plate 31 and the second plate 32 can be constructed, for example, from iron, stainless steel, carbon fiber reinforced plastic (CFRP), etc.

[0054] <Helical Spring>

[0055] A helical spring 4 is housed within a receiving hole 21, a first window portion 311, and a second window portion 321. The helical spring 4 elastically connects the first rotating body 2, the first plate 31, and the second plate 32 in the rotational direction R. That is, the torque from the first rotating body 2 is transmitted to the first plate 31 and the second plate 32 via the helical spring 4. Furthermore, the helical spring 4 rotates together with the first rotating body 2, the first plate 31, and the second plate 32. When the helical spring 4 contracts during torque transmission, the first rotating body 2 and the second rotating body 3 twist relative to each other. When the helical spring 4 is not contracted, the first rotating body 2 and the second rotating body 3 do not twist, and the twist angle is zero degrees.

[0056] <Sprocket>

[0057] The sprocket 6 is mounted on the first plate 31. The sprocket 6 is mounted on the first plate 31 via a stop member 5, a first nut 8, and a second nut 9. The sprocket 6 rotates integrally with the first plate 31 and the second plate 32. The sprocket 6 has multiple teeth at its outer peripheral end. A chain (not shown) is attached to the sprocket 6, and torque is transmitted from the sprocket 6 to the drive wheel (not shown) via the chain, etc.

[0058] The sprocket 6 has multiple engagement holes 61. The engagement holes 61 are spaced apart from each other in the circumferential direction. When viewed in the axial direction, each engagement hole 61 overlaps with the corresponding first through hole 312 and second through hole 322.

[0059] <Stop component>

[0060] Figure 5 This is a side view of the stop component 5. (As shown) Figure 1 as well as Figure 5 As shown, the stop member 5 is linked with the first nut 8 and the second nut 9 to detachably fasten the first plate 31 and the second plate 32. Additionally, the sprocket 6 is fastened to the first plate 31 via the stop member 5 and the first nut 8. The stop member 5 is mounted on the second rotating body 3. The stop member 5 is configured to rotate integrally with the second rotating body 3.

[0061] The stop member 5 includes a stop portion 51, a first screw portion 52, a first intermediate portion 53, a second screw portion 54, and a second intermediate portion 55. The stop portion 51, the first screw portion 52, the first intermediate portion 53, the second screw portion 54, and the second intermediate portion 55 are integrally formed with each other. Specifically, the stop portion 51, the first screw portion 52, the first intermediate portion 53, the second screw portion 54, and the second intermediate portion 55 are integrally formed by a single component. The stop member 5 is solid and does not have any internal openings.

[0062] The stop portion 51 is cylindrical. The stop portion 51 extends axially. The stop portion 51 is circumferentially opposed to the stop surface 25. The stop portion 51 is axially positioned between the first plate 31 and the second plate 32. The stop portion 51 is sandwiched between the first plate 31 and the second plate 32. The stop portion 51 is disposed within the cutout portion 26 of the first rotating body 2.

[0063] The first screw portion 52 and the stop portion 51 are integrally formed. The first screw portion 52 extends axially. The first screw portion 52 has threads formed on its outer peripheral surface. The outer diameter of the first screw portion 52 is smaller than the outer diameter of the stop portion 51.

[0064] The first screw portion 52 is disposed on a first side in the axial direction relative to the stop portion 51. The first screw portion 52 is disposed on a first side in the axial direction relative to the first plate 31. In addition, the first screw portion 52 is disposed on a first side in the axial direction relative to the sprocket 6.

[0065] The first intermediate portion 53 is axially disposed between the stop portion 51 and the first screw portion 52. Specifically, the first intermediate portion 53 extends from the stop portion 51 toward a first axial direction. Furthermore, the first screw portion 52 extends from the first intermediate portion 53 toward a first axial direction.

[0066] The first intermediate portion 53 is cylindrical. The first intermediate portion 53 extends axially. The length of the first intermediate portion 53 is less than the combined thickness of the first plate 31 and the sprocket 6. Furthermore, the length of the first intermediate portion 53 is greater than the thickness of the first plate 31. It should be noted that the length of each part of the stop member 5 refers to the axial dimension.

[0067] The outer diameter of the first intermediate portion 53 is smaller than the outer diameter of the stop portion 51, but larger than the outer diameter of the first screw portion 52. The first intermediate portion 53 is disposed within the first through hole 312 and the engaging hole 61. The first intermediate portion 53 does not protrude axially to the first side from within the first through hole 312 and the engaging hole 61.

[0068] The second screw portion 54 is integrally formed with the stop portion 51. The second screw portion 54 extends axially. The second screw portion 54 has threads formed on its outer peripheral surface. The outer diameter of the second screw portion 54 is smaller than the outer diameter of the stop portion 51. The second screw portion 54 has an outer diameter that is approximately the same as that of the first screw portion 52.

[0069] The second screw portion 54 is disposed on the second side in the axial direction relative to the stop portion 51. The second screw portion 54 is disposed on the second side in the axial direction relative to the second plate 32.

[0070] The second intermediate portion 55 is axially disposed between the stop portion 51 and the second screw portion 54. Specifically, the second intermediate portion 55 extends from the stop portion 51 toward a second axial side. Furthermore, the second screw portion 54 extends from the second intermediate portion 55 toward a second axial side.

[0071] The second intermediate portion 55 is cylindrical. The second intermediate portion 55 extends axially. The length of the second intermediate portion 55 is shorter than the length of the first intermediate portion 53. The length of the second intermediate portion 55 is less than the thickness of the second plate 32.

[0072] The outer diameter of the second intermediate portion 55 is smaller than the outer diameter of the stop portion 51, but larger than the outer diameter of the second screw portion 54. The second intermediate portion 55 has an outer diameter that is approximately the same as that of the first intermediate portion 53. The second intermediate portion 55 is disposed within the second through hole 322. The second intermediate portion 55 does not protrude axially to a second side from within the second through hole 322.

[0073] <First and second nuts>

[0074] The first nut 8 is screwed into the first screw part 52. The first nut 8 and the stop part 51 clamp the sprocket 6 and the first plate 31 in a linkage manner. The first nut 8 is a flange nut.

[0075] The second nut 9 is screwed into the second screw part 54. The second nut 9 and the stop part 51 clamp the second plate 32 in a linkage manner. The second nut 9 is a flange nut.

[0076] <Crank arm>

[0077] like Figure 1 As shown, the crank arm 7 is configured to rotate integrally with the first rotating body 2. That is, the crank arm 7 is configured to rotate about the rotation axis O. The crank arm 7 is mounted on the end of the hub 22 of the first rotating body 2 on the second side of the axial direction. In detail, the crank arm 7 is configured to be splined into a spline hole 241 formed by a plurality of protrusions 24 on the inner circumferential surface of the hub 22.

[0078] The crank arm 7 has an arm body portion 71 and a mounting portion 72. The arm body portion 71 extends radially outward from the mounting portion 72. The arm body portion 71 is configured not to overlap with the stop member 5 when viewed axially (see reference). Figure 2 The main body 71 of the arm is configured to overlap with the helical spring 4 when viewed along the axial direction.

[0079] Mounting part 72 is connected to one end of the two ends of arm body part 71. Mounting part 72 extends axially. It should be noted that a pedal (not shown) is installed at the other end of the two ends of arm body part 71. Mounting part 72 is mounted on hub part 22. Mounting part 72 has mounting body part 723, front end part 721, and mounting hole 722.

[0080] Figure 6 This is an enlarged sectional view showing the mounting portions of the crank arm 7 and the first rotating body 2. It should be noted that... Figure 6 The description of parts other than the crank arm 7 and the first rotating body 2 is omitted. For example... Figure 6 As shown, the mounting body 723 abuts against the hub 22 in the axial direction. The mounting body 723 is cylindrical. The mounting body 723 extends axially. The mounting body 723 has a first end face 724 facing a first side in the axial direction. The hub 22 has a second end face 223 facing a second side in the axial direction. The first end face 724 of the mounting body 723 abuts against the second end face 223 of the hub 22.

[0081] The mounting body 723 has an outer diameter larger than that of the hub 22. Specifically, the outer diameter of the first end face 724 of the mounting body 723 is larger than the outer diameter of the second end face 223 of the hub 22. Therefore, the entire second end face 223 of the hub 22 abuts against the first end face 724 of the mounting body 723.

[0082] The front end portion 721 extends axially to a first side from the mounting body portion 723. Specifically, the front end portion 721 extends axially to a first side from the first end face 724 of the mounting body portion 723. The outer diameter of the front end portion 721 is smaller than that of the mounting body portion 723. The front end portion 721 extends within the hub portion 22. The front end portion 721 splines into a spline hole 241 formed by a plurality of protrusions 24.

[0083] The front end portion 721 extends axially through the spline hole 241. Furthermore, the front end portion 721 is riveted to the hub portion 22. More specifically, the front end portion 721 is riveted to the small diameter portion 222. More specifically, the front end portion 721 is riveted to each of the protrusions 24 formed in the small diameter portion 222.

[0084] The front end 721 is riveted to each protrusion 24, such as Figure 7 As shown, the front end portion 721 and each protrusion 24 are in close contact. Furthermore, the outer diameter of the portion of the front end portion 721 that protrudes axially from each protrusion 24 towards the first side is increased by riveting, becoming larger than the inner diameter of the spline hole 241. As a result, the front end portion 721 will not detach from the spline hole 241, preventing the crank arm 7 and the first rotating body 2 from moving axially in a direction of separation from each other.

[0085] The mounting part 72 has a mounting hole 722. The mounting hole 722 is rectangular when viewed axially. A crankshaft (not shown) is fitted into the mounting hole 722, and the crank arm 7 rotates integrally with the crankshaft.

[0086] <Action>

[0087] The operation of the power transmission device 100 with the structure described above will be explained. First, if torque is input to the first rotating body 2 via the crank arm 7 by the user pressing the pedal, the first rotating body 2 rotates in the rotational direction R. Then, torque is transmitted from the first rotating body 2 to the second rotating body 3 via the coil spring 4. As a result, the second rotating body 3 rotates in the rotational direction R, transmitting torque to the drive wheel.

[0088] Here, if the helical spring 4 is compressed and the torsional angle of the first rotating body 2 and the second rotating body 3 reaches a predetermined angle, then the stop surface 25 abuts against the stop portion 51. By abutting the stop portion 51 against the stop surface 25 in this way, further relative rotation of the first rotating body 2 relative to the second rotating body 3 is restricted. That is, the first rotating body 2 and the second rotating body 3 rotate relative to each other until the stop member 5 abuts against the stop surface 25. Furthermore, after the stop portion 51 abuts against the stop surface 25, the first rotating body 2 and the second rotating body 3 rotate as a unit. The torsional angle of the first rotating body 2 and the second rotating body 3 when the stop surface 25 abuts against the stop portion 51 is called the maximum torsional angle. It should be noted that when no torque is input to the power transmission device 100, the torsional angle of the first rotating body 2 and the second rotating body 3 is zero degrees.

[0089] [Variation Example]

[0090] The embodiments of the present invention have been described above, but the present invention is not limited thereto, and various modifications can be made without departing from the spirit of the present invention. It should be noted that the following variations can be applied simultaneously.

[0091] (a) In the above embodiment, the crank arm 7 is mounted on the first rotating body 2 so that the arm body 71 does not overlap with the stop member 5 when viewed axially, but the structure of the power transmission device 100 is not limited to this. For example, the arm body 71 may overlap with the stop member 5 when viewed axially.

[0092] (b) In the above embodiment, the clearance portion 28 is formed at the end of the second side of the axial direction of the protrusion 24, but the clearance portion 28 may be formed at the end of the first side of the axial direction of the protrusion 24, or at both the end of the first side and the end of the second side of the axial direction of the protrusion 24.

[0093] (c) In the above embodiment, the flange portion 23 is inclined axially, but the flange portion 23 may not be inclined axially. That is, the flange portion 23 may also extend along a surface orthogonal to the rotation axis O.

[0094] Explanation of reference numerals in the attached figures

[0095] 2: First rotating body; 22: Hub; 221: Hub body; 222: Small diameter part; 23: Flange; 24: Protrusion; 28: Clearance part; 3: Second rotating body; 31: First plate; 32: Second plate; 5: Stopping component; 51: Stopping part; 52: First screw part; 54: Second screw part; 7: Crank arm; 71: Arm body; 72: Mounting part; 721: Front end; 723: Mounting body; 100: Bicycle power transmission device.

Claims

1. A power transmission device for bicycles, comprising: First body of revolution; The second rotating body is configured to rotate relative to the first rotating body; An elastic component elastically connects the first rotating body and the second rotating body; and The crank arm rotates integrally with the first rotating body. The first rotating body has a hub and a flange, the hub extending axially and the flange extending radially outward from the hub. The crank arm has a mounting portion and an arm body portion, the mounting portion being mounted on the hub portion, and the arm body portion extending radially outward from the mounting portion. The mounting part has: The mounting body abuts against the hub in the axial direction; and The front end extends axially from the mounting body portion, has an outer diameter smaller than the outer diameter of the mounting body portion, and is riveted to the hub portion. The mounting body has an outer diameter larger than that of the hub.

2. The power transmission device for bicycles according to claim 1, wherein, The hub has a cylindrical hub body and a cylindrical small-diameter portion, the hub body extending axially, and the small-diameter portion having an inner diameter smaller than the inner diameter of the hub body. The front end of the mounting part is riveted to the small diameter part.

3. The power transmission device for bicycles according to claim 2, wherein, The hub portion has: Multiple protrusions extend axially on the inner circumferential surface of the small-diameter portion; as well as Multiple clearance portions are formed at at least one end of each of the convex portions along their axial direction.

4. The power transmission device for bicycles according to claim 1, wherein, The bicycle power transmission device also includes fastening components. The second rotating body has: The first plate is disposed on a first side in the axial direction relative to the flange portion; as well as The second plate is disposed on the second side of the axial direction relative to the flange portion. The fastening components secure the first plate and the second plate in a detachable manner. The main body of the arm is configured not to overlap with the fastening component when viewed along the axial direction.

5. The power transmission device for a bicycle according to claim 4, wherein, The fastening component has: A stop portion is disposed between the first plate and the second plate; The first screw portion is disposed on a first side in the axial direction relative to the first plate; and The second screw portion is disposed on the second side in the axial direction relative to the second plate.

Images