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

摘要

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.