POWER STEERING DEVICE FOR VEHICLE

摘要

PROBLEM TO BE SOLVED: To suppress steep steering when the vehicle speed is high by controlling a power source for running so that a force required to make steep steering on a steering wheel is enlarged. SOLUTION: A hydraulic pump 19 is driven by an electric motor 20 furnished separately from a motor for running, and a working fluid is supplied to a hydraulic cylinder 21 which steers the rear wheels 13. A steering control unit 22 controls the revolving speed of the electric motor 20 so as to enlarge the steering assist force in compliance with the steering torque TS on a steering when the vehicle speed (v) is under the reference speed. Further the control unit 22 controls the revolving speed of the electric motor 20 so that the steering assist force does not increase any more if the steering torque TS corresponding to the reference speed is exceeded by the steering torque TS when the vehicle speed (v) is over the reference value.