VARIABLE CAPACITY VANE PUMP WITH DUAL CONTROL CHAMBERS

摘要

A variable capacity vane pump includes a pump casing having a pump chamber with an inlet and an outlet port. A pump control ring is moveable within the pump chamber to alter the capacity of the pump. A vane pump rotor is rotatably mounted within the pump control ring and includes a plurality of slidably mounted vanes engaging the inside surface of the pump control ring. First and second control chambers between the pump casing and the pump control ring are operable to receive pressurized fluid to urge the pump control ring to reduce the volumetric capacity of the pump. A return spring biases the pump ring toward a position of maximum volumetric capacity against the force of the first and second control chambers to establish an equilibrium pressure. The supply of pressurized fluid to the second control chamber may be varied to change the equilibrium pressure of the pump.