| 摘要 |
PROBLEM TO BE SOLVED: To provide a small-sized electrostrictive element driving actuator with good responsiveness. SOLUTION: A housing 2 comprises an electrostrictive element 3, a first piston 10 operated by the element 3, and a second hydraulic chamber 31 located under it. It further comprises a second cylinder 12 smaller in diameter than the first piston 10 and opened to the second hydraulic chamber 31, and a second piston 13 equipped with an opening and closing valve 20 opened and closed by the operation of the first piston 10 is slidably fitted thereto and energized to the closing side by an opening and closing valve spring 22. A reciprocating piston 26 is slidably fitted into a reciprocating cylinder 25 opened to the lower part of the housing 2. A fifth hydraulic chamber 34 is provided on the head part of the reciprocating piston 26, and allowed to communicate with a drain circuit 15 through the opening and closing valve 20. A hydraulic source 37 is allowed to communicate with the second hydraulic chamber 31 through a first restriction 45 by a second conduit 41, and further allowed to communicate with the fifth hydraulic chamber 34 through a second restriction 46 by a third conduit 42. |
