Patent ID: 11905948
Assignee: HITACHI ASTEMO, LTD.
Field: Engines, pumps, turbines (Mechanical engineering)
Classification: CPC F | IPC F

Claim 0:
1. A variable displacement oil pump comprising:
a pump forming member accommodated in a pump housing, and structured to be rotationally driven so as to change a volumetric capacity of each of a plurality of pump chambers, and suck working oil through a suction part, and discharge working oil through a discharge part;
a swing member accommodated in the pump housing, and structured to accommodate the pump forming member inside of the swing member, and swing about a swing fulcrum so as to vary a quantity of change of the volumetric capacity of each of the plurality of pump chambers opened to the discharge part, wherein the swing fulcrum is set at an outer periphery of the swing member;
a biasing member accommodated in the pump housing, and mounted with application of a setting load so as to bias the swing member in a direction to increase the quantity of change of the volumetric capacity of each of the plurality of pump chambers, the biasing member including a single spring;
a first control oil chamber formed in the pump housing between an inner peripheral surface of the pump housing and a first pressure-receiving surface of the swing member, and structured to be supplied with the discharged working oil from the discharge part such that the supplied discharged working oil in the first control oil chamber applies a first torque to the swing member via the first pressure-receiving surface in a direction to reduce the quantity of change of the volumetric capacity of each of the plurality of pump chambers;
a second control oil chamber formed in the pump housing between the inner peripheral surface of the pump housing and a second pressure-receiving surface of the swing member, and structured to be supplied with the discharged working oil via a switching mechanism from the discharge part such that the supplied discharged working oil in the second control oil chamber applies a second torque to the swing member via the second pressure-receiving surface in a direction to increase the quantity of change of the volumetric capacity of each of the plurality of pump chambers, wherein the second pressure-receiving surface of the swing member has a larger area than the first pressure-receiving surface of the swing member; and
the switching mechanism structured to switch between supply of the discharged working oil from the discharge part to the second control oil chamber and drain of the supplied discharged working oil from the second control oil chamber.