| 摘要 |
An electromagnetic clutch according to the invention includes a first rotatable member having an axial end plate of magnetic material and a second rotatable member. The second rotatable member includes a drive shaft, and a hub mounted on an end of the shaft. An annular armature plate is disposed on an outer peripheral portion of the hub facing the axial end plate of the first rotatable member with an axial air gap therebetween. An electromagnetic device is disposed within the first rotatable member for attracting the armature plate to the axial end surface of the first rotatable member. The armature plate is elastically connected with the hub by a plurality of leaf springs. A self-return type temperature switch is fixedly disposed within the first rotatable member and closely placed to the axial end plate of the first rotatable member for controlling the energization of the electromagnetic device according to the temperature on the axial end plate. The temperature switch disconnects the electromagnetic device if a predetermined temperature is exceeded. Meltable elements are disposed on the armature plate to define the axial air gap between the first rotatable member and the armature plate. When the elements are heated sufficiently due to frictional heat, they melt and the air gap between the first rotatable member and the armature plate increases to a point where the clutch cannot be engaged. Therefore, if the temperature switch reconnects the electromagnetic device, the clutch will still not function to prevent any further device damage.
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