HYDRAULIC CONTROL VALVE SYSTEM WITH SPLIT PRESSURE COMPENSATOR

摘要

An improved pressure-compensated hydraulic system for feeding hydraulic fluid to one or more hydraulic actuators (20). A remotely located, variable displacement pump (18) provides an output pressure equal to a control input pressure plus a constant margin. A pressure compensation system requires that a load-dependent pressure be provided to the pump input through a load sense circuit. An isolator (92) transmits the load-dependent pressure to the pump control input, while preventing fluid from leaving the load sense circuit and flowing to the remotely located pump (18). A valve section (13, 14, 15) which controls the fluid flow between the pump (18) and actuator (20) has a pressure compensating valve (48) with a piston (64) and a spool (60) controlling a pressure differential across a main control valve orifice (44) by moving within a bore (62) in response to a pressure differential between a pump supply pressure and the load sense pressure. The piston (64) and the spool (60) also separate to shut off fluid to the actuator (20) when the back pressure from the load exceeds the pump supply pressure.