Hitachi Automotive Systems, Ltd.

Makoto Tada

Satoshi Nonaka

Makoto Kimura

Shigeaki Yamamuro

Hiroyoshi Gomi

A variable displacement vane pump includes: a plate side high pressure introduction groove formed in the pressure plate or in the cam ring, formed so that an entire is positioned within a radial width of the cam ring, and a part is positioned in a circumferential region between the suction port and the discharge port, and arranged to receive a hydraulic pressure larger than a suction pressure; and a housing side high pressure introduction groove formed in the second housing or in the cam ring, formed so that an entire is positioned within the radial width of the cam ring, that a radial center is positioned radially outside the radial center of the plate side high pressure introduction groove, and that a part is overlapped with the plate side high pressure introduction groove in the circumferential direction, and arranged to receive the hydraulic pressure larger than the suction pressure.

Variable displacement vane pump

A variable displacement pump including a drive shaft, a cam ring eccentrically moveable with respect to an axis of the drive shaft, and a solenoid drivingly controlled on the basis of variation in electric current amount to be supplied to the solenoid which is controlled in accordance with an operating condition of a vehicle. The solenoid is configured such that a rate of change in the specific discharge amount relative to the electric current amount to be supplied to the solenoid under a condition that the specific discharge amount is smaller is reduced as compared to a rate of change in the specific discharge amount relative to the electric current amount to be supplied to the solenoid under a condition that the specific discharge amount is larger.

Variable displacement pump and power steering apparatus using the variable displacement pump

A variable displacement pump includes: a rotor mounted in a body; a cam ring mounted radially outside of the rotor, and arranged to move with a change in an eccentricity of the cam ring with respect to the rotor, wherein change of the eccentricity causes a change in a specific discharge rate; and an electromagnetic actuator arranged to actuate the cam ring for regulating the eccentricity. During control of operation of the electromagnetic actuator, a first response is set slower than a second response, wherein the first response is a response of movement of the cam ring to a change of an input signal in a direction to request a decrease in the specific discharge rate, and the second response is a response of movement of the cam ring to a change of the input signal in a direction to request an increase in the specific discharge rate.

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Zama, Japan

Makoto Tada