Patent ID: 7780221

Claim:
A clutch arranged between a drive shaft and a driven shaft, in which the driven shaft is arranged coaxially with the drive shaft, the clutch couples the drive shaft to the driven shaft when the drive shaft is in a drive state, the clutch shuts off the driven shaft from the drive shaft when the drive shaft is in a non-drive state, the clutch comprises: a first drive rotor which is integrally rotatable with the drive shaft, the first drive rotor being arranged coaxially with the drive shaft; a second drive rotor provided coaxially with the first drive rotor; an urging member arranged between the first drive rotor and the second drive rotor, the urging member holding the second drive rotor at a predetermined relative rotational position with respect to the first drive rotor; a driven rotor which is integrally rotatable with the driven shaft, the driven rotor being arranged coaxially with the driven shaft; and a power transmitting member arranged between the first drive rotor and the driven rotor, and between the second drive rotor and the driven rotor, with respect to a radial direction, the power transmitting member being movable among a first clamping position, a second clamping position, and a non-engaging position, the non-engaging position in an inner side in a radial direction than the first clamping position and the second clamping position, the first drive rotor and the driven rotor clamping the power transmitting member located at the first clamping position, the second drive rotor and the driven rotor clamping the power transmitting member located at the second clamping position, the first drive rotor and the driven rotor not clamping the power transmitting member located at the non-engaging position, and the second drive rotor and the driven rotor not clamping the power transmitting member located at the non-engaging position, wherein when the drive shaft is in a non-drive state, the power transmitting member exists at the non-engaging position, so that the second drive rotor is in a non-engaging state with the driven rotor with respect to its own rotating direction, and wherein when the drive shaft is in a drive state, a rotating force of the first drive rotor is transmitted to the second drive rotor through the urging member, so that the second drive rotor is rotated, and the power transmitting member revolves accordingly, a centrifugal force caused by the revolution arranges the power transmitting member at the second clamping position, the second drive rotor receives a reaction force from the driven rotor via the power transmitting member, so that the second drive rotor is relatively rotated in an opposite direction to the rotating direction of the first drive rotor with respect to the first drive rotor, against the urging force of the urging member, and the power transmitting member is arranged at the first clamping position, so that the first drive rotor is engaged with the driven rotor with respect to its own rotating direction.