| 摘要 |
PROBLEM TO BE SOLVED: To suppress the useless expense of energy of a pump when an actuator is in the non-operating condition and the necessary operating oil pressure is low, by providing a low pressure chamber communicating to a drain passage through a damper orifice, between the cylinder inner periphery of an outer spool and the small bore outer periphery of an inner spool. SOLUTION: A spool valve 50 is composed of an outer spool 52 of a tubular form with bottom having a through hole 53 at the bottom 52b; and an inner spool 51 having a large bore part 51a inserted to the inner periphery of the cylinder 52a of the outer spool 5, and a small bore part 51b inserted in the through hole 53. And the bottom 52b of the outer spool 52 is faced to the second pressure chamber 17. At the same time, a low pressure chamber 56 communicating to a drain passage 20 through a damper orifice 55 is formed between the inner periphery of the cylinder 52a of the outer spool 52, and the outer periphery of the small bore part 51b of the inner spool 51. On the other hand, a control spring 18 is operated to the inner spool 51. Furthermore, a spring member 58 to energize the outer spool 52 to the second pressure chamber 17 side is attached. |
