| 摘要 |
<P>PROBLEM TO BE SOLVED: To suppress the occurrence of erroneous operation in a power transmission device 1 in which a permanent magnet 2 is used. Ž<P>SOLUTION: This power transmission device 1 includes a magnet attitude changing means for changing the attitude of the permanent magnet 2. A clutch is changed over between ON and OFF by changing the attitude of the permanent magnet 2 by the magnet attitude changing means to change over between a first magnetic circuit for flowing a magnetic flux to a rotor 4 and an armature 7 and a second magnetic circuit for flowing a magnetic flux weaker than that in the first magnetic circuit to the rotor 4 and the armature 7. Since the magnetic attractive force between the rotor 4 and the armature 7 is reduced when the clutch is OFF (attitude in which the second magnetic circuit is formed), the occurrence of such an erroneous operation that the rotor 4 and the armature 7 are intentionally connected to each other can be suppressed without allowing the armature 7 to be attracted to the rotor 4 even if a gap 6 is reduced by vibration and external force. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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