Multiple actuator hydraulic system and rotary control valve therefor

A hydraulic system has a rotary valve which controls multiple hydraulic devices such as double-acting piston type actuators and which prevents deactivated devices from creeping. The valve has an outer housing and a rotatable inner member which form high pressure inlet, low pressure outlet, and control stages. The control stages utilize partial commutators (part circumferential grooves) and ports on the valve member selectively to couple control ports of the housing respectively to the inlet stage or the outlet stage by rotating the inner valve member (the control ports being connected to the hydraulic devices). At the inlet and outlet stages, the valve member has full annular commutators which communicate continuously with a high pressure inlet port and a low pressure vent port of the housing as the valve member is rotated. The valve member also has internal passageways which connect each control stage partial commutator and fluid port to either the inlet commutator or the outlet commutator. The control stages are arranged such that control ports not selected for coupling to the inlet stage will be coupled to the outlet stage and therefore vented to low pressure. This prevents any high pressure fluid leakage within the valve from flowing to non-selected devices, which therefore cannot creep. Thrust loads on the rotatable valve member are prevented by porting the inner end of the valve member to the outlet commutator in order to vent fluid from the closed inner end of the housing.

Abstract

A hydraulic system has a rotary valve which controls multiple hydraulic devices such as double-acting piston type actuators and which prevents deactivated devices from creeping. The valve has an outer housing and a rotatable inner member which form high pressure inlet, low pressure outlet, and control stages. The control stages utilize partial commutators (part circumferential grooves) and ports on the valve member selectively to couple control ports of the housing respectively to the inlet stage or the outlet stage by rotating the inner valve member (the control ports being connected to the hydraulic devices). At the inlet and outlet stages, the valve member has full annular commutators which communicate continuously with a high pressure inlet port and a low pressure vent port of the housing as the valve member is rotated. The valve member also has internal passageways which connect each control stage partial commutator and fluid port to either the inlet commutator or the outlet commutator. The control stages are arranged such that control ports not selected for coupling to the inlet stage will be coupled to the outlet stage and therefore vented to low pressure. This prevents any high pressure fluid leakage within the valve from flowing to non-selected devices, which therefore cannot creep. Thrust loads on the rotatable valve member are prevented by porting the inner end of the valve member to the outlet commutator in order to vent fluid from the closed inner end of the housing.

1. Drawings

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