Electromagnetic clutch

摘要

A compact-size electromagnetic clutch reaches a blocking state as an electromagnetic solenoid is switched from a non-driving state to a driving state and can save wasteful consumption of energy under this blocking state. This electromagnetic clutch includes a wrap spring in pressure-contact with an outer face of a cylindrical portion of a drive pulley provided on the center side thereof. One end of the wrap spring is coupled to a drive arm of a drive member operably connected to a shaft. The other end of the wrap spring is coupled to an operational member rotatable relative to the shaft and movable along the rotational axis thereof. An electromagnetic solenoid attracts the operational member. An operational mechanism permits realization of the blocking state by preventing rotation of the drive member after a twisting operation of the wrap spring subsequent to the attraction of the operational member by this electromagnetic solenoid.

主权项

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.