Abstract: A variable capacity pump includes a housing and a rotatable rotor within the housing. The rotor includes radial slots to accommodate slidable vanes or rotor blades, wherein the vanes are urged outwards by centrifugal force into contact with the inner surface of a surrounding cam ring. The cam ring is surrounded on one end by a pressure chamber including a piston under hydraulic pressure, and on the other end by a seated spring. By controlling the pressure distributed to the pressure chamber, the position of the cam ring with respect to the rotor may be changed to automatically vary the displacement of the pump in response to a pressure differential across a restriction orifice, thereby regulating the output flow to be constant over a defined speed range.

Abstract: A variable capacity pump includes a housing and a rotatable rotor within the housing. The rotor includes radial slots to accommodate slidable vanes or rotor blades, wherein the vanes are urged outwards by centrifugal force into contact with the inner surface of a surrounding cam ring. The cam ring is surrounded on one end by a pressure chamber including a piston under hydraulic pressure, and on the other end by a seated spring. By controlling the pressure distributed to the pressure chamber, the position of the cam ring with respect to the rotor may be changed to automatically vary the displacement of the pump in response to a pressure differential across a restriction orifice, thereby regulating the output flow to be constant over a defined speed range.