Hydraulic control valve system with isolated pressure compensation

In a hydraulic system having an array of valve sections that control flow of fluid from a pump to a plurality of hydraulic actuators, wherein pressure of the fluid from the pump is regulated by a mechanism 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 pump to the one hydraulic actuator;

• a pressure compensation apparatus comprising:
• each valve section having compensator spool slideably located in a bore thereby defining a pressure chamber at a first end of the compensator spool and a pre-compensator gallery at a second end of the compensator spool, wherein a preload gallery, an auxiliary supply passage and a load sense passage all open into the bore with fluid flowing from the preload gallery to the workport, the auxiliary supply passage connected to an outlet of the pump, and the load sense passage extending into to all the valve sections and providing a pressure signal that is employed to control pressure at the outlet of the pump, an orifice connects the load sense passage to the pressure chamber, 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.

In a hydraulic system having an array of valve sections that control flow of fluid from a pump to a plurality of hydraulic actuators, wherein pressure of the fluid from the pump is regulated by a mechanism 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 pump to the one hydraulic actuator;

• a pressure compensation apparatus comprising:
• each valve section having compensator spool slideably located in a bore thereby defining a pressure chamber at a first end of the compensator spool and a damping chamber at a second end of the compensator spool, wherein a pre-compensator gallery, a preload gallery, an auxiliary supply passage and a load sense passage all open into the bore with fluid flowing from the preload gallery to the workport, the auxiliary supply passage connected to an outlet of the pump, and the load sense passage extending into all the valve sections and providing a pressure signal that is employed to control pressure at the outlet of the pump, a first orifice connects the pre-compensator gallery to the pressure chamber and a second orifice connects the load sense passage to the damping chamber, 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.