Patent ID: 9140313
Filing Date: 2015-09-22
Classification: F16D

Abstract:
1. An electromagnetic clutch comprising: a drive pulley having, on its outer circumference side, a cylindrical belt-entraining portion about which a length of a drive belt is entrained and having, on its inner circumference side, a tubular portion rotatable in unison with the belt-entraining portion and supported to a stationary system; a wrap spring wrapped around the outer circumference of the tubular portion and placed in pressure-contact therewith under a natural condition; a shaft rotatably supported to the stationary system and mounted coaxial with a rotational axis of the drive pulley, the shaft being rotatably driven when receiving a force from the drive pulley; a drive member fixed to the shaft, one end of the wrap spring being coupled to the drive member; an operational member formed of a magnetic matter, the operational member being coaxially rotatable relative to the shaft, with the other end of the wrap spring coupled to the operational member, the operational member being movable along an extending direction of the shaft; and an electromagnetic solenoid provided in the stationary system and configured to generate a magnetic force for fixingly attracting the operational member; wherein as the electromagnetic solenoid is energized to fixingly attract the operational member thereto, the drive member is rotated relative to the operational member by a frictional force relative to the drive pulley or a dynamic inertia, so that the pressure-contact of the wrap spring relative to the tubular portion is released and force transmission from the drive pulley to the shaft is blocked.