Patent ID: 7818966
Filing Date: 2010-10-26
Classification: F15B

Abstract:
1. In a hydraulic system having an array of valve sections that control flow of fluid from a supply line to a plurality of hydraulic actuators, wherein pressure of the fluid in the supply line is regulated in response to a control signal, and each valve section has a workport to which one hydraulic actuator connects and having a spool with a metering orifice that is variable to control flow of the fluid from the supply line to the one hydraulic actuator; a pressure compensation apparatus comprising: each valve section having a pressure compensating valve that comprises: (a) a compensator bore having a pre-compensator gallery in fluid communication with the metering orifice, a preload gallery from which fluid flows to the workport, an auxiliary supply passage connected to the supply line, and a load sense passage that is connected to all the valve sections and in which the control signal is produced; (b) a compensator spool slideably located in the compensator bore wherein pressure in the pre-compensator gallery exerts a first force that tends to move the compensator spool in one direction and pressure in the load sense passage exerts a second force that tends to move the compensator spool in an opposite direction, in response to the first and second forces the compensator spool having a first position that provides a first path between the pre-compensator gallery and the preload gallery and a second path between the auxiliary supply passage and the load sense passage, a second position in which the first path is provided and the second path is not provided, and a third position in which neither the first path nor the second path is provided; and a main spring biasing the compensator spool into the third position.