| 摘要 |
PURPOSE:To obtain a compact hydraulic shut-off valve having stable characteristics by providing a spool valve adapted for changing the flow rate in response to the differential pressure between an inlet port and an outlet port and driven by an electrostrictive actuator. CONSTITUTION:There is provided between an inlet port 11 and an outlet port 12 an axially slidable spool valve 13. The spool valve 13 is axially moved by activation of an electrostrictive actuator 17 so as to complete communication between both ports 11, 12, and as the pressure of the fluid entering through the inlet port 11 acts on the spool valve 13 in the axial direction, the opening degree of the flow passage to be opened and closed by the movement of the spool valve 13 is set according to the pressure of the entering fluid and resiliency of the spring 25. Therefore, the flow rate through the valve can be kept constant, irrespective of the differential pressure between the inlet and outlet ports, and furthermore, the characteristics of the electrostrictive actuator assures good responsibility of the hydraulic shut-off valve.
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