초록 ▼

An improved pressure-compensated hydraulic system for feeding hydraulic fluid to one or more hydraulic actuators. A remotely located, variable displacement pump provides an output pressure equal to input pressure plus a constant margin. A pressure compensation systems requires that a load-dependent

An improved pressure-compensated hydraulic system for feeding hydraulic fluid to one or more hydraulic actuators. A remotely located, variable displacement pump provides an output pressure equal to input pressure plus a constant margin. A pressure compensation systems requires that a load-dependent pressure be provided to the pump input through a load sense circuit. A reciprocally spooled, multi-ported isolator transmits the load-dependent pressure to the pump input but prevents fluid in the load sense circuit from leaving the load sense circuit and flowing through a relatively long conduit leading to the remotely located pump. In a multi-valve array, at least one valve section has a backflow-preventing shuttle valve which prevents backflow through the pressure compensation system if a main relief valve is operative.

대표청구항 ▼

[ I claim:] [1.] In a hydraulic system having an array of valve sections for controlling flow of hydraulic fluid from a pump to a plurality of hydraulic actuators, each valve section having a workport to which one of the plurality of hydraulic actuators connects, the pump being of the type which pro

[ I claim:] [1.] In a hydraulic system having an array of valve sections for controlling flow of hydraulic fluid from a pump to a plurality of hydraulic actuators, each valve section having a workport to which one of the plurality of hydraulic actuators connects, the pump being of the type which produces an output pressure that is a constant amount greater than a pressure at a control input, the array of valve sections being of the type in which the greatest pressure among the workports is sensed to provide a load sense pressure which is transmitted to the control input; the improvement comprising:within each valve section, a pressure compensating valve that provides the load sense pressure at one side of a metering orifice which sees on the other side the output pressure of the pump so that the pressure drop across the metering orifice is substantially equal to the constant amount, the pressure compensator having a poppet slidably located in a bore thereby defining first and second chambers of the bore, the first chamber being in communication with the metering orifice and the second chamber being in communication with the load sense pressure wherein a pressure differential between the first and second chambers determines a position of the poppet with in the bore, the bore having an output port through which fluid is supplied to one of the hydraulic actuators, the poppet having a passage through which fluid can flow between the metering orifice and the output port when the poppet is at a first position in response to pressure in the first chamber being greater than pressure in the second chamber; anda check valve within the poppet and controlling communication of pressure between the first chamber and one of the output port and the second chamber.