Patent ID: 9109596
Filing Date: 2015-08-18
Classification: F04C

Abstract:
1. A variable displacement pump comprising: a rotationally driven rotor; a plurality of vanes provided in an outer periphery of the rotor and arranged to be moved in a radially inward direction and to be moved in a radially outward direction; a cam ring in an inside of which the rotor and the vanes are housed, in an inner part of which a plurality of pump chambers are formed, and configured to be moved to vary an eccentricity of the cam ring with respect to a rotary center of the rotor; a housing including: a biasing member configured to bias the cam ring toward the one direction toward which the eccentricity of the cam ring with respect to the rotary center of the rotor becomes large; a first control oil chamber configured to move the cam ring toward the other direction against a biasing force of the biasing member when a discharge pressure is introduced into the first control oil chamber; a second control oil chamber configured to act a hydraulic pressure upon the cam ring by cooperating with the biasing force of the biasing member when hydraulic oil is introduced into the second control oil chamber; a switching mechanism configured to switch between a first state in which hydraulic oil whose pressure is decreased with respect to a discharge pressure is introduced to the second control oil chamber from the discharge section and a second state in which hydraulic oil is discharged from the second control oil chamber; and a control mechanism configured to discharge hydraulic oil within the second control oil chamber as the discharge pressure becomes larger and to adjust the pressure within the second control oil chamber in a pressure decrease direction when the switching mechanism introduces hydraulic oil whose pressure is decreased with respect to the discharge pressure to the second control oil chamber during a high revolution of the pump.