| 摘要 |
PROBLEM TO BE SOLVED: To provide a means for suppressing oscillation during operation of a piezoelectric element in a pre-load variable mechanism. SOLUTION: A pre-load variable mechanism is provided with oppositely-arranged angular ball bearings 2, a housing 12 having an inner peripheral face fitted with outer peripheral faces of outer rings 3 of the angular ball bearings 2, a piston 20 having an outer peripheral face fitted to the inner peripheral face of the housing 12, and a piezoelectric actuator 18 that axially displaces the piston 20 corresponding to the applied voltage. An O-ring groove 23 is provided in the outer peripheral face of the piston 20. An O-ring 22 made of an elastic resin material is provided in the O-ring groove 23 so as to press against the inner peripheral face of the housing 12. COPYRIGHT: (C)2009,JPO&INPIT
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