Patent ID: 9518484
Filing Date: 2016-12-13
CPC Classification: F01L,F04C

Claim Text:
1. A variable displacement pump for an internal combustion engine, to supply oil to a hydraulic variable valve actuation device, an oil jet and a crankshaft bearing, comprising: a rotor adapted to be driven by the internal combustion engine; a plurality of vanes slidably received in an outer circumference of the rotor; a cam ring which includes an inside circumferential surface enclosing the rotor and the vanes, having a center line eccentric from a rotation axis of the rotor, and defining a plurality of operating oil chambers, and which is arranged to move to vary an eccentricity and thereby to vary a pumping volume; an intake portion opening into the operating oil chambers in a volume increasing region in which volumes of the operating oil chambers are increased with rotation of the rotor; a discharge portion opening into the operating oil chambers in a volume decreasing region in which the volumes of the operating oil chambers are decreased with rotation of the rotor; an urging mechanism including first and second spring members provided with respective spring loads, and arranged to apply an urging force to the cam ring in an eccentric direction with a spring force produced by the first and second spring members, and to increase the urging force of the first and second spring members stepwise when the cam ring is rotated in a concentric direction from a maximum eccentric position and the eccentricity of the cam ring becomes smaller than or equal to a predetermined value; a first control chamber arranged to receive oil discharged from the discharge portion and to apply a force to the cam ring in a direction decreasing the eccentricity; a second control chamber arranged to receive the oil discharged from the discharge portion and to apply a force smaller than the force produced by the first control chamber, to the cam ring in a direction increasing the eccentricity; a thermosensitive mechanism disposed in a passage connecting the discharge portion with the second control chamber, to connect the second control chamber with the discharge portion in a higher oil temperature state and to connect the second control chamber with a low pressure portion in a low oil temperature state; and a control valve to be operated by a discharge pressure of the discharge portion and to decrease a pressure in the second control chamber when the discharge pressure of the discharge portion becomes higher than or equal to a predetermined pressure.