CLUTCH MECHANISM

In a clutch mechanism, non-magnetic portions of an armature and non-magnetic portions of a pulley are offset from one another in a radial direction of a rotating shaft. For this reason, in an attracting magnetic circuit, magnetic flux passes between an outer cylindrical portion and an inner cylindrical portion so as to avoid the non-magnetic portions of the armature and the non-magnetic portions of the pulley. Accordingly, magnetic flux passes through a boundary between the armature and the pulley six times. The number of poles of the attracting magnetic circuit is increased. The physical size of a permanent magnet can be reduced. For this reason, the physical size of the clutch mechanism is reduced. As a result, the power consumption of an electromagnetic coil can be reduced by increasing the cross-sectional areas of coil portions. The physical size of the clutch mechanism is reduced and the power consumed is reduced.