Torque and high pressure limiting control for variable displacement pumps
AssigneeCaterpillar Tractor Co.
InventorsWalter Z. Ruseff, James E. Schimpf
Life of this patent
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Abstract
It is common practice to provide the servo-system for a variable displacement pump with a "load-plus" valve to maintain pump discharge pressure above a minimum pressure level and above a load pressure in a fluid actuator connected to the pump in response to the load pressure in the actuator. Systems of this type are normally lacking in a device for ensuring that the prime mover for the pump functions at maximum efficiency. This invention is directed to a pressure and horsepower limiting valve (24) for ensuring such efficiency by modulating a load pressure signal (P.sub.L) communicated to the "load-plus" valve (23).
Claims14
In a fluid circuit (10) having a fluid actuator (13), a variable displacement pump (11) including a control member (28) movable between first and second displacement positions, first biasing means (30) for urging said control member (28) towards its first displacement position, and second biasing means (31) for urging said control member (28) towards its second displacement position in opposition to said first biasing means (30) and in response to a load pressure signal communicated thereto from said fluid actuator (13), the improvement comprising:
- modulating means (24) for modulating said load pressure signal in said second biasing means (31) to vary the displacement of said pump (11) in response to the magnitude of said load pressure signal and the position of said control member (28).
Dependencies are inferred from the claim text.