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EP-4741268-A1 - BICYCLE POWER TRANSMISSION DEVICE

EP4741268A1EP 4741268 A1EP4741268 A1EP 4741268A1EP-4741268-A1

Abstract

It is intended to perform swaging in a stable condition. A crank arm is rotated unitarily with a first rotor. The first rotor includes a hub portion and a flanged portion. The hub portion extends in an axial direction. The flanged portion extends radially outward from the hub portion. The crank arm includes an attachment portion and an arm body. The attachment portion is attached to the hub portion. The arm body extends radially outward from the attachment portion. The attachment portion includes an attachment body and a distal end. The attachment body is contacted with the hub portion in the axial direction. The distal end extends from the attachment body in the axial direction. The distal end is smaller in outer diameter than the attachment body. The distal end is swaged to the hub portion. The attachment body is larger in outer diameter than the hub portion.

Inventors

  • HARIMA, KENJI
  • OHSHIMA, HIROSHI

Assignees

  • Exedy Corporation

Dates

Publication Date
20260513
Application Date
20251017

Claims (5)

  1. A bicycle power transmission device comprising: a first rotor; a second rotor disposed to be rotatable relative to the first rotor; an elastic member elastically coupling the first rotor and the second rotor therethrough to each other; and a crank arm rotated unitarily with the first rotor, wherein the first rotor includes a hub portion extending in an axial direction, and a flanged portion extending radially outward from the hub portion, the crank arm includes an attachment portion attached to the hub portion, and an arm body extending radially outward from the attachment portion, the attachment portion includes an attachment body contacted with the hub portion in the axial direction, and a distal end extending from the attachment body in the axial direction, the distal end smaller in outer diameter than the attachment body, the distal end swaged to the hub portion, and the attachment body is larger in outer diameter than the hub portion.
  2. The bicycle power transmission device according to claim 1, wherein the hub portion includes a hub body extending in the axial direction, the hub body having a cylindrical shape, and a small diameter portion having a cylindrical shape, the small diameter portion smaller in inner diameter than the hub body, and the distal end of the attachment portion is swaged to the small diameter portion.
  3. The bicycle power transmission device according to claim 2, wherein the hub portion includes a plurality of protruding portions extending on an inner peripheral surface of the small diameter portion in the axial direction, and a plurality of relief portions, each of the plurality of relief portions provided on at least one of both axial ends of each of the plurality of protruding portions.
  4. The bicycle power transmission device according to claim 1, further comprising: a fastening member, wherein the second rotor includes a first plate disposed on a first side of the flanged portion in the axial direction, and a second plate disposed on a second side of the flanged portion in the axial direction, the fastening member fastens the first plate and the second plate therethrough to each other such that the first plate and the second plate are made detachable from each other, and the arm body is disposed not to overlap with the fastening member as seen in the axial direction.
  5. The bicycle power transmission device according to claim 4, wherein the fastening member includes a stopper portion disposed between the first plate and the second plate, a first screw portion disposed on the first side of the first plate in the axial direction, and a second screw portion disposed on the second side of the second plate in the axial direction.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is based on and claims the priority benefit of Japanese application No. 2024-194363 filed on November 6, 2024, the contents of which are incorporated herein by reference. TECHNICAL FIELD The present invention relates to a bicycle power transmission device. BACKGROUND Japan Laid-open Patent Application Publication No. 2024-084007 discloses a bicycle power transmission device. The bicycle power transmission device includes a first rotor and a second rotor. The first and second rotors are elastically coupled to each other through coil springs. A crank arm is attached to a hub portion of the first rotor. SUMMARY OF THE INVENTION The crank arm is attached to the hub portion of the first rotor by swaging. It is an object of the present invention to provide a bicycle power transmission device, for which swaging is enabled to be performed in a stable condition. A bicycle power transmission device according to a first aspect includes a first rotor, a second rotor, an elastic member, and a crank arm. The second rotor is disposed to be rotatable relative to the first rotor. The elastic member elastically couples the first rotor and the second rotor therethrough to each other. The crank arm is rotated unitarily with the first rotor. The first rotor includes a hub portion and a flanged portion. The hub portion extends in an axial direction. The flanged portion extends radially outward from the hub portion. The crank arm includes an attachment portion and an arm body. The attachment portion is attached to the hub portion. The arm body extends radially outward from the attachment portion. The attachment portion includes an attachment body and a distal end. The attachment body is contacted with the hub portion in the axial direction. The distal end extends from the attachment body in the axial direction. The distal end is smaller in outer diameter than the attachment body. The distal end is swaged to the hub portion. The attachment body is larger in outer diameter than the hub portion. According to the configuration, the attachment body is larger in outer diameter than the hub portion; hence, the attachment body serves as a base when the distal end of the attachment portion is swaged to the hub portion, whereby swaging is enabled to be performed for fixing the distal end to the hub portion in a stable condition. A bicycle power transmission device according to a second aspect relates to the bicycle power transmission device according to the first aspect and is configured as follows. The hub portion includes a hub body and a small diameter portion. The hub body extends in the axial direction. The hub body has a cylindrical shape. The small diameter portion has a cylindrical shape. The small diameter portion is smaller in inner diameter than the hub body. The distal end of the attachment portion is swaged to the small diameter portion. A bicycle power transmission device according to a third aspect relates to the bicycle power transmission device according to the second aspect and is configured as follows. The hub portion includes a plurality of protruding portions and a plurality of relief portions. The plurality of protruding portions extend on an inner peripheral surface of the small diameter portion in the axial direction. Each of the plurality of relief portions is provided on at least one of both axial ends of each of the plurality of protruding portions. A bicycle power transmission device according to a fourth aspect relates to the bicycle power transmission device according to any of the first to third aspects and further includes a fastening member. The second rotor includes a first plate and a second plate. The first plate is disposed on a first side of the flanged portion in the axial direction. The second plate is disposed on a second side of the flanged portion in the axial direction. The fastening member fastens the first plate and the second plate therethrough to each other such that the first plate and the second plate are made detachable from each other. The arm body is disposed not to overlap with the fastening member as seen in the axial direction. A bicycle power transmission device according to a fifth aspect relates to the bicycle power transmission device according to the fourth aspect and is configured as follows. The fastening member includes a stopper portion, a first screw portion, and a second screw portion. The stopper portion is disposed between the first plate and the second plate. The first screw portion is disposed on the first side of the first plate in the axial direction. The second screw portion is disposed on the second side of the second plate in the axial direction. Overall, according to the present invention, swaging is enabled to be performed in a stable condition. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a bicycle power transmission device.FIG. 2 is a front view of the bicycle power transmission d