| 摘要 |
PROBLEM TO BE SOLVED: To suppress wasteful energy consumption of a pump, when an operating oil pressure is low required with an actuator in an inoperative condition. SOLUTION: Or operating oil introduced in the first pressure chamber 15, a necessary flow amount is guided to a delivery passage 8 through a control orifice 9, a surplus flow amount is bypass-guided to a drain passage 19 controlled to be opened/closed by moving a spool valve 14. A cylindrical movable sleeve 37, provided with through holes 40, 41 capable of respectively communicating with the drain passage 19 and an introducing passage 20, is provided between a spool valve receiving hole 5 and the spool valve 14, one end 37a and the other end 37 of the movable sleeve 37 are made to respectively appear in the first pressure chamber 15 and a low pressure chamber 39. A spring member 38 giving bias force to a side of the first pressure chamber 15 is made to belong to the movable sleeve 37. A control means 50, controlling moving of the movable sleeve 37 to a side of the second pressure chamber 16, is provided. |
