Patent ID: 9670926
Date: 2017-06-06
CPC Classifications: F01M,F04C

Claim:
1. A variable displacement pump comprising: a rotationally driven rotor, a plurality of vanes movable out from and into the rotor, a cam ring, wherein the rotor, the plurality of vanes, and the cam ring form a plurality of pump chambers and are configured to suck and discharge oil by volume variations of the plurality of pump chambers; a pump body housing the rotor, the plurality of vanes, and the cam ring; at least three control oil chambers configured to move the cam ring within the pump body by a supply of oil discharged from the plurality of pump chambers to change rates of the volume variations of the plurality of pump chambers, wherein the at least three control oil chambers include at least one reduction-side control oil chamber provided to move the cam ring in a direction that reduces the rates of the volume variations of the plurality of pump chambers and two increase-side control oil chambers configured to move the cam ring in a direction that increases the rates of the volume variations of the plurality of pump chambers; a spring provided to have a set load and to bias the cam ring in the direction that increases the rates of the volume variations of the plurality of pump chambers; and two electromagnetic changeover valves, each of the two electromagnetic changeover valves being configured to control each quantity of oil supplied to the two increase-side control oil chambers.