Pressure compensated hydraulic system having differential pressure control

摘要

A hydraulic control valve assembly (10), method and system, characterized by control valves (26) each having a variable metering orifice; a compensator (28) that controls flow of fluid from the variable metering orifice to a work port (A,B) in response to a differential in pressures acting on opposite first and second sides of the compensator, wherein a first side receives a pressure at the downstream side of the variable metering orifice; a load sense passage (34) providing a load sense pressure; and a differential pressure controller (40) having a first inlet connected to a pump supply port and a second inlet connected to the load sense passage, the controller having a first operational mode in which load sense pressure at the second inlet is supplied to an outlet of the controller and a second operational mode in which flow from the first inlet is metered to the outlet of the controller to provide a differential control output pressure, and wherein an outlet of the differential pressure controller is connected to a pump control port and/or to the second side of the pressure compensating valve of at least one of the control valves.

主权项

1. A hydraulic control valve assembly comprising
plural control valves each having a variable metering orifice through which hydraulic fluid flows between an inlet port providing for connection to a load sense margin pressure source and a respective work port providing for connection to a respective actuator; a compensator that receives flow of fluid from the variable metering orifice and directs it to the work port of each control valve in response to a differential in pressures acting on opposite first and second sides of the compensator, wherein the first side receives a pressure at the downstream side of the variable metering orifice; a load sense passage connected to the control valves to provide a load sense pressure corresponding to the greatest pressure amongst the work ports; and a differential pressure controller having a first inlet connected to the inlet port and a second inlet connected to the load sense passage, the differential pressure controller having a first operational mode in which load sense pressure at the second inlet is supplied to an outlet of the differential pressure controller and a second operational mode in which flow from the first inlet is metered to the outlet of the differential pressure controller to provide a differential control output pressure at the outlet of the differential pressure controller, and wherein the outlet of the differential pressure controller is connected to (a) a control port to which can be connected the control port of the load sense margin pressure source that produces an output pressure of the source that is a predefined amount greater than the pressure supplied to the control port of the source, and/or (b) the second side of the pressure compensating valve of at least one of the plural control valves.