| 摘要 |
PROBLEM TO BE SOLVED: To suppress wasteful energy consumption of a pump, when and operating oil pressure is low required with an actuator in an inoperative condition. SOLUTION: Of 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 50. The control orifice 9 is constituted by a main orifice 44 and a suborifice 46. The spool valve 50 is constituted by an inner side spool 51 and an outer side spool 52, a low pressure chamber 56 is formed in an internal peripheral side of this outer side spool 52, on the other hand, a control spring 17 is made to act in the inner side spool 51. A spring member 61, energizing the inner side spool 51 to a side of the first pressure chamber 15 and the outer side spool 52 to a side of the second pressure chamber 16, is made to belong between the inner/outer side spools 51, 52. |
