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US 8,297,943 B2Granted
Pump control using overpressure source
AssigneeMAGNA Powertrain AG & Co KG
InventorsDavid R. Shulver, Matthew Williamson, Adrian C. Cioc
Life of this patent
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Abstract
A rotary positive displacement pump employs the higher pressure available at a region within the rotor chamber after the outlet port to augment the force of a biasing spring in a control system. A biasing spring with a lower spring force can thus be employed in the control system, resulting in a pump pressure output characteristic which can more closely match the operating speed varying working fluid requirements for devices supplied by the pump.
Claims6
A rotary positive displacement pump for supplying pressurized working fluid to a driving device, the pump comprising:
- a control valve comprising a piston moveable in a bore and a biasing spring for biasing the piston to act against a force created by pressurized working fluid from a first outlet port of the pump to reduce output pressure of the pump;
- and
- a second outlet port wherein a pressure of the working fluid exiting the second outlet port is greater than a pressure of the working fluid at the first outlet port of the pump and varies with the speed of the pump, the greater pressure working fluid exiting the second outlet port is supplied to the control valve, creating a force which augments and combines with a force of the biasing spring acting on the control valve to counter the force of the pressurized working fluid from the first outlet port acting on the piston, and wherein the entire working fluid output of the second outlet port is supplied to the control valve.
Dependencies are inferred from the claim text.