Variable displacement vane pump with improved pressure control and range

Abstract

An arrangement of a variable capacity vane pump for an automobile is provided that includes a pump housing having an outlet and inlet. A pump control ring is provided having a cavity. The control ring is positioned within the housing to move about a pivot. A vane pump rotor is positioned within the cavity of the pump control ring. A position of the pump control ring determines an offset between a center of the pump control ring cavity and an axis of rotation of the vane pump rotor. Vanes are provided that are driven by the rotor and which engage an interior surface of the pump control ring. The vanes and the engaged surface defining working fluid chambers. A first control chamber is provided. The first control chamber is exposed to a first side of the pivot between the pump housing and the outer surface of the pump control ring. The first control chamber is operable to receive pressurized fluid to create a force to move the pump control ring to reduce a volumetric capacity of the pump. A second control chamber, positioned between the pump inlet and outlet is provided that provides a hydraulic force to increase the volumetric capacity of the pump.