Patent ID: 8047822

Claim:
A vane pump with continuously variable output pressure, comprising: a variable displacement vane pump having a pump control ring which is moveable to alter the displacement of the pump and spring biased to a position of maximum displacement; a first control chamber operable to create a force on the pump control ring to urge the pump control ring towards a position of minimum displacement, the force resulting from pressurized working fluid in the first control chamber; a second control chamber operable to create a force on the pump control ring to urge the pump control ring towards the position of maximum displacement, the force resulting from pressurized working fluid in the second control chamber; a control means operable to vary supply of pressurized working fluid to at least one of the first and second control chambers to vary the displacement of the control ring during operation of the pump to achieve an output pressure selected from a continuously variable range of output pressures from the pump which are independent from an operating speed of the pump.