Power steering apparatus

摘要

A power steering apparatus which generates a steering assist force by a hydraulic pressure generated by a pump (26) driven by an electric motor (27). The power steering apparatus actuates the electric motor in its off state, on condition that a change amount of a steering angle exceeds an actuation threshold (d&thetas;). A first actuation threshold (d&thetas;1) which is to be employed when a steering wheel (2) is operated away from a steering angle midpoint (&thetas;0) and a second actuation threshold (d&thetas;2) which is to be employed when the steering wheel (2) is operated toward the steering angle midpoint (&thetas;0) are determined in accordance with a sensed steering angle (&thetas;) so that the sum (2A) of the first and second actuation thresholds (d&thetas;1, d&thetas;2) is virtually constant. <IMAGE>