| 摘要 |
PROBLEM TO BE SOLVED: To provide a pulley unit which prevents the occurrence of an abnormal high speed rotation state leading to the deterioration of durability by adjusting power transmission efficiency in a high speed rotation region. SOLUTION: When rotation speed of an alternator pulley 2 exceeds the set value, centrifugal force acting on a weight 6 of a rotation adjustment mechanism 4 is increased so that the weight 6 moves radially outward against biasing force of a compression coil spring 6a. A slide member 7 follows to move to a wall part 3d side in an axial direction by biasing force of a tension coil spring 7d. As the slide member 7 moves to the wall part 3d side, the clearance S between a fixed transmission plate 9A and movable transmission plate 9B is increased to the maximum clearance S2. In a viscous fluid V for filling the clearance S2, the clearance shearing stress in a transverse direction to a pressing force acting between the transmission plates 9A, 9B is reduced with increasing the clearance S2 between a fixed transmission plate 9A and movable transmission plate 9B so that a power transmission efficiency from the alternator pulley 2 to the alternator shaft 3 by the rotation adjustment mechanism 4 is deteriorated. COPYRIGHT: (C)2008,JPO&INPIT
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