Patent ID: 9683587
Date: 2017-06-20
CPC Classifications: F15B

Claim:
1. A fluid pressure control device which makes a cylinder expand and contract with a working fluid supplied from a pump to be able to drive a load and in which the cylinder includes a pressure chamber on which a load pressure by the load acts in a state where supply and discharge of the working fluid are interrupted, the fluid pressure control device comprising: a first control valve that is configured to switch to supply the working fluid to the pressure chamber so as to control an extension operation of the cylinder; a second control valve that is configured to switch to discharge the working fluid in the pressure chamber so as to control a contraction operation of the cylinder; an operate check valve that is interposed between the pressure chamber and the second control valve and that interrupts the discharge of the working fluid from the pressure chamber when the operate check valve is switched to a closed state; and a pilot valve that is configured to perform, with a pilot pressure, a pilot operation on the second control valve and that is configured to switch, with the pilot pressure, the operate check valve to an opened state, wherein the operate check valve includes: when the pilot pressure guided to the switch pressure chamber exceeds a set pressure, the valve member is switched to an opened state by movement of the spool to discharge the working fluid in the back pressure chamber.