| 摘要 |
PROBLEM TO BE SOLVED: To prevent the enlargement of a solenoid valve by supplying a fixed flow rate preferentially to a back pressure regulating valve and solenoid valve side by a sub flow control valve, and supplying the surplus flow rate directly to a power steering circuit. SOLUTION: When the set flow rate of the preferential flow port 2 of a main flow control valve 1 is set to 30 l/min, for example, in the use of a large power steering circuit PS requiring a maximum flow rate of 30 l/min, the flow rate of 30 l/min is supplied to a sub flow control valve R. However, since the flow rate supplied to the preferential port 2 side is 5 l/min when the set flow rate on the control flow port 22 side is set to 5 l/min in the sub flow control valve R, enlargement of a solenoid valve 17 or a back pressure regulating valve 14 is not required. When the solenoid valve 17 is closed, a back pressure is generated on the upstream side of the back pressure valve 14, so that a prescribed pressure can be guided to a pilot pressure line 12 to prevent the interference of the solenoid valve 17 with another apparatus. |
