System for allocating fluid from multiple pumps to a plurality of hydraulic functions on a priority basis

摘要

A valve assembly (40) has a flow summation node (74) coupled to a displacement control (39) port of the first pump (50). Each valve (41-47) in the assembly has a variable metering orifice (75) controlling flow from an inlet (70) to a hydraulic actuator and has a variable source orifice (64) conveying fluid from a supply conduit (58) to a flow summation node. The source orifice enlarges as the metering orifice shrinks. Each valve includes a variable bypass orifice (80) and the bypass orifices of all the control valves are connected in series forming a bypass passage (85) between a bypass node (55) and a tank (53). The bypass node is coupled to the flow summation node and receives fluid from a second pump (51). At each valve, a source check valve (68) conveys fluid from the supply conduit to the inlet and a bypass supply check valve (89) conveys fluid from the bypass passage to the inlet.