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EP-4741271-A1 - BICYCLE POWER TRANSMISSION DEVICE

EP4741271A1EP 4741271 A1EP4741271 A1EP 4741271A1EP-4741271-A1

Abstract

It is intended to inhibit first and second plates from being abraded. A coil spring is disposed in a first window portion of a first plate, a second window portion of a second plate, and an accommodation hole of a first rotor. The first plate includes a first contact surface and a first cutout portion. The first contact surface is in contact with an end surface of a coil spring. The first cutout portion is provided in the first contact surface. The second plate includes a second contact surface and a second cutout portion. The second contact surface is in contact with the end surface of the coil spring. The second cutout portion is provided in the second contact surface.

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 including an accommodation hole; a first plate including a first window portion, the first plate disposed to be rotatable relative to the first rotor; a second plate including a second window portion, the second plate configured to be rotated unitarily with the first plate, the second plate disposed to interpose the first rotor together with the first plate therebetween in an axial direction; and a coil spring disposed in the first window portion, the second window portion, and the accommodation hole, the coil spring elastically coupling the first rotor and both the first and second plates therethrough to each other, wherein the first plate includes a first contact surface being in contact with an end surface of the coil spring, and a first cutout portion provided in the first contact surface, and the second plate includes a second contact surface being in contact with the end surface of the coil spring, and a second cutout portion provided in the second contact surface.
  2. The bicycle power transmission device according to claim 1, wherein the first plate includes a first offset portion, the first offset portion disposed radially inside the first cutout portion, the first offset portion being offset toward the first rotor.
  3. The bicycle power transmission device according to claim 2, wherein the second plate includes a second offset portion, the second offset portion disposed radially inside the second cutout portion, the second offset portion being offset toward the first rotor.
  4. The bicycle power transmission device according to claim 2, wherein the coil spring is not in contact with the first offset portion.
  5. The bicycle power transmission device according to claim 1, wherein the first rotor includes a third contact surface, the third contact surface being in contact with the coil spring, the first rotor not provided with a cutout portion in the third contact surface.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is based on and claims the priority benefit of Japanese application No. 2024-194360 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 A bicycle power transmission device includes a first rotor, a first plate, and a second plate (see e.g., Japan Laid-open Patent Application Publication No. 2024-084007). The first and second plates are configured to be rotated unitarily with each other. The first rotor and both the first and second plates are elastically coupled to each other through coil springs. When described in detail, the coil springs are disposed in accommodation holes of the first rotor, window portions of the first plate, and window portions of the second plate, respectively. SUMMARY OF THE INVENTION When the bicycle power transmission device is used, it is concerned that the coil springs are rotated in the window portions of the first plate and those of the second plate, respectively, whereby the first and second plates are abraded. In view of this, it is an object of the present invention to inhibit the first and second plates from being abraded. A bicycle power transmission device according to a first aspect includes a first rotor, a first plate, a second plate, and a coil spring. The first rotor includes an accommodation hole. The first plate includes a first window portion. The first plate is disposed to be rotatable relative to the first rotor. The second plate includes a second window portion. The second plate is configured to be rotated unitarily with the first plate. The second plate is disposed to interpose the first rotor together with the first plate therebetween in an axial direction. The coil spring is disposed in the first window portion, the second window portion, and the accommodation hole. The coil spring elastically couples the first rotor and both the first and second plates therethrough to each other. The first plate includes a first contact surface and a first cutout portion. The first contact surface is in contact with an end surface of the coil spring. The first cutout portion is provided in the first contact surface. The second plate includes a second contact surface and a second cutout portion. The second contact surface is in contact with the end surface of the coil spring. The second cutout portion is provided in the second contact surface. According to the configuration, the first contact surface is provided with the first cutout portion; hence, on the first contact surface, a part disposed radially outside the first cutout portion and that disposed radially inside the first cutout portion become likely to deform to follow the rotation of the coil spring. As a result, the coil spring is inhibited from being rotated relative to the first contact surface, whereby it is made possible to inhibit the first plate from being abraded. Likewise, the second contact surface is provided with the second cutout portion as well; hence, it is made possible to inhibit the second plate from being abraded. 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 first plate includes a first offset portion. The first offset portion is disposed radially inside the first cutout portion. The first offset portion is offset toward the first rotor. 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 second plate includes a second offset portion. The second offset portion is disposed radially inside the second cutout portion. The second offset portion is offset toward the first rotor. A bicycle power transmission device according to a fourth aspect relates to the bicycle power transmission device according to the second or third aspect and is configured as follows. The coil spring is not in contact with the first offset portion. A bicycle power transmission device according to a fifth aspect relates to the bicycle power transmission device according to any of the first to fourth aspects and is configured as follows. The first rotor includes a third contact surface. The third contact surface is in contact with the coil spring. The first rotor is not provided with a cutout portion in the third contact surface. Overall, according to the present invention, it is made possible to inhibit the first and second plates from being abraded. 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 device.FIG. 3 is a front view of a first rotor.FIG. 4 is a front view of a first plate.FIG. 5 is a cross-sectional view of the first plate taken along line V-V in FIG. 4.FIG. 6 is a f