| 摘要 |
PROBLEM TO BE SOLVED: To sufficiently achieve energy saving performance by restricting useless consumption of energy in a pump in a non-actuation condition of an actuator when required pressure of hydraulic fluid is low. SOLUTION: In hydraulic fluid introduced into a first pressure chamber 15, necessary flow is introduced through a control orifice to a discharge passage 8, while excessive flow is let to bypass to a drain passage 19 which is opening- controlled by move of a spool valve 14. A cylindrical movable sleeve 37 provided with through holes 42, 43 to be respectively communicated with the drain passage 19 and an introducing passage 20 is provided between a spool valve containing hole 5 and the spool valve 14, one end 37a of the movable sleeve 37 is put to face the first pressure chamber 15, and the other end 37b is set to face a low pressure chamber 38. In addition, biased force to the first pressure chamber 15 side is given to the movable sleeve 37, and a spring member 38 to obtain spring force in stages by move of the movable sleeve 37 is provided. |
