| 摘要 |
PURPOSE:To prevent cavitation by constituting a change-over valve in such a manner that a third opening and closing part is closed in preference to a first opening and closing part, and a second opening and closing part is opened after the first opening and closing part is closed, when an actuator is reduced in speed. CONSTITUTION:In a first opening and closing part 29, a second opening and closing part 31 and a third opening and closing part 32 of a change-over valve 4, dimensions represented by x1 to x4 and y1 to y4 in the drawing are selected so as to satisfy the equations y2>x2, y4>x4 and y3>x3 when y1<x1 holds, the equations x2>y2 and x2-y2>y1-x1 when y1>=x1 holds, and the equations x4>y4, y3>x3 and ¦y4-x4¦+¦x3-y3¦> ¦x2-y2¦ when x2>=y2 holds. Accordingly, relief pressure of a hydrauric pump can be enclosed in passages connected to an actuator, when the speed of the actuator for driving inertia mass is reduced. Therefore, the supply of oil is unnecessary and the generation of cavitation can be surely prevented.
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