Patent ID: 9611870
Date: 2017-04-04
CPC Classifications: E02F,F15B,F16K

Claim:
1. A pressure control valve for a construction machine, comprising: a holding valve block having a pilot signal pressure port and a drain flow path formed thereon and installed between a hydraulic actuator and a control valve; a holding poppet having a back pressure chamber formed therein to intercept leakage of hydraulic fluid from the hydraulic actuator to the control valve in a neutral state; a first elastic member pressing the holding poppet and elastically biasing an intercepted path between the hydraulic actuator and the control valve in an initial state; a piston sliding in the holding valve block when pilot signal pressure is input through the pilot signal pressure port; a pilot poppet shifted along an inner surface of a sleeve of the holding valve block to drain the hydraulic fluid in the back pressure chamber toward a first drain flow path of the control valve in response to movement of the piston; a second elastic member pressing the pilot poppet and elastically biasing an intercepted path between the back pressure chamber of the holding poppet and the first drain flow path of the control valve in an initial state; and an auxiliary drain path draining the leaking hydraulic fluid through a second drain path of the holding valve block after passing through the pilot poppet if the leakage of the hydraulic fluid occurs on a valve seat surface of a check valve that opens or closes the path between the back pressure chamber of the holding poppet and the first drain flow path of the control valve.