Clutch structure

1. A clutch structure comprising:

a clutch input shaft including an input shaft portion defined by a single unitary component and connected to a drive shaft, and a first flange portion extending outward in a radial direction from the input shaft portion;

a clutch output shaft located coaxially with the clutch input shaft and including a cylindrical portion surrounding the first flange portion in a circumferential direction, a second flange portion extending inward in the radial direction from the cylindrical portion, and an output shaft portion coupled to the second flange portion;

a weight member supported by the first flange portion so as to be movable in the radial direction that frictionally contacts an inner circumferential surface of the cylindrical portion by centrifugal force to transmit a rotational power from the clutch input shaft to the clutch output shaft when a rotational frequency of the clutch input shaft exceeds a predetermined value, and that separates from the inner circumferential surface of the cylindrical portion to disconnect transmission of the rotational power from the clutch input shaft to the clutch output shaft when the rotational frequency of the clutch input shaft becomes not more than the predetermined value;

an annular one-way clutch located between the input shaft portion and the output shaft portion to link the input shaft portion and the output shaft portion when the weight member separates from the inner circumferential surface of the cylindrical portion and the rotational frequency of the clutch input shaft falls below a rotational frequency of the clutch output shaft; and

an annular first bearing located between the input shaft portion and the output shaft portion and supporting the input shaft portion and the output shaft portion so as to be relatively rotatable; wherein

both an inner circumferential portion of the annular one-way clutch and an inner circumferential portion of the annular first bearing contact the input shaft portion.

2. The clutch structure according to claim 1 , wherein the one-way clutch and the first bearing contact an outer circumferential surface of the input shaft portion.

3. The clutch structure according to claim 1 , wherein the one-way clutch and the first bearing contact an inner circumferential surface of the output shaft portion.

4. The clutch structure according to claim 1 , wherein the one-way clutch is located adjacent to the first bearing in an axial direction of the clutch input shaft.

5. The clutch structure according to claim 4 , further comprising:

a second bearing surrounding and rotatably supporting the output shaft portion; wherein

the first bearing is located between the one-way clutch and the second bearing in the axial direction.

6. The clutch structure according to claim 5 , wherein at least a portion of the first bearing overlaps with the second bearing when viewed from the radial direction.

7. The clutch structure according to claim 1 , wherein an inner diameter of the one-way clutch and an inner diameter of the first bearing are the same or substantially the same.

8. The clutch structure according to claim 1 , further comprising a connector that connects the input shaft portion to the drive shaft.

9. The clutch structure according to claim 8 , wherein the connector includes a bolt, and at least a portion of the bolt is located inside the input shaft portion.

10. The clutch structure according to claim 1 , wherein the first bearing is a needle bearing.

11. The clutch structure according to claim 1 , wherein the drive shaft is a crankshaft of an engine.

12. The clutch structure according to claim 1 , wherein the output shaft portion is linked to an input shaft of a shiftable transmission that transmits a rotational power from the drive shaft to a vehicle wheel.