Patent ID: 7669275

Claim:
A clutch device comprising: an output shaft rotatably supported in a housing; an input disk that is supported on the output shaft rotatably about an axis of the output shaft to be rotated by an input of a rotational driving force; a clutch disk that is supported on the output shaft non-rotatably about the axis and movably in an axial direction of the output shaft to face the input disk in the axial direction to come into an engagement with the input disk in the axial direction; an elastic member that exerts resistive force on the clutch disk when the clutch disk is about to come out of the engagement with the input disk, wherein: one of the input disk and the clutch disk has a trailing surface inclined by a predetermined angle from the axis, and the other of the input disk and the clutch disk has a curved control surface to face the trailing surface in a circumferential direction of the output shaft to come in a line contact with the trailing surface; the curved control surface has a gradually varied curvature to decrease a component force of a surface pressure at a contact line with the trailing surface in a transmission direction of the rotational driving force as the input disk and the clutch disk rotate against each other to disengage them from each other; the input disk has an outer circumferential surface that is circularly curved to be coaxial with the output shaft; and the outer circumferential surface of the input disk is rotatably supported by the housing.