Hydraulic systems for construction machinery
AssigneeJ.C. Bamford Excavators Limited
InventorJames Hewitt
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Abstract
The present invention relates to a hydraulic system comprising a first actuator, a first variable displacement pump fluidly connected to the first actuator via a first circuit and adapted to drive the first actuator. The system further comprises a second actuator and a second pump fluidly connectable to the second actuator via a second circuit and adapted to drive the second actuator, wherein the second pump is fluidly connectable to the first actuator via a first control valve, and wherein the second pump is fluidly connectable to the second actuator via a second control valve.
Claims20
A hydraulic system comprising:
- a first actuator;
- a first variable displacement pump fluidly connected to the first actuator via a first circuit and adapted to drive the first actuator;
- a second actuator;
- a second pump fluidly connectable to the second actuator via a second circuit and adapted to drive the second actuator,
- wherein the second pump is fluidly connectable to the first actuator via a first control valve, and wherein the second pump is fluidly connectable to the second actuator via a second control valve,
- wherein the second pump is selectively and simultaneously connectable to the second actuator and to the first actuator to provide a top up fluid flow to assist a fluid flow from the first variable displacement pump,
- wherein the second pump is also arranged to act as a charge pump maintaining the hydraulic system at an elevated fluid pressure, and
- wherein the first variable displacement pump is directly connected or connectable to the first actuator, and wherein the first control valve is a first proportional control valve adapted to variably restrict a fluid flow from the second pump provided to the first actuator.
A hydraulic system comprising:
- a first actuator;
- a first variable displacement pump fluidly connected to the first actuator via a first circuit and adapted to drive the first actuator;
- a second actuator;
- a second pump fluidly connectable to the second actuator via a second circuit and adapted to drive the second actuator,
- wherein the second pump is fluidly connectable to the first actuator via a first control valve and adapted to drive the first actuator, and wherein the second pump is fluidly connectable to the second actuator via a second control valve, and
- wherein the first variable displacement pump is configured as a bidirectional variable displacement pump and the second pump is configured as a unidirectional pump, and wherein the first and second control valves are directional control valves.
A hydraulic system comprising:
- a first actuator;
- a first variable displacement pump fluidly connected to the first actuator via a first circuit and adapted to drive the first actuator;
- a second actuator;
- a second pump fluidly connectable to the second actuator via a second circuit and adapted to drive the second actuator,
- wherein the second pump is fluidly connectable to the first actuator via a first control valve, and wherein the second pump is fluidly connectable to the second actuator via a second control valve, and
- wherein the first variable displacement pump is sized such that a maximum output flow rate of the first variable displacement pump equals 45% to 55% of a peak flow rate necessary to drive the first actuator at a predetermined minimal cycle time.
Dependencies are inferred from the claim text.