Power steering system for motor vehicles

摘要

A power steering system for motor vehicles for assisting the manual steering effort includes an electromotive drive unit which acts upon the steering shaft in a sense corresponding to that of the manual steering. The operating mode of the drive unit is dependent on the vehicle speed and the instantaneous steering torque manually applied to the steering wheel. At low vehicle speeds and high manual steering torque the drive unit is caused to run at high speeds; at high vehicle speeds and low manual steering torque the drive unit is caused to run at low speeds. A fluid friction clutch is interposed between the drive unit and the steering shaft. In addition to transmitting force from the drive unit to the steering shaft, the fluid friction clutch assists in damping forces which are transmitted to the steering wheel by the steering system in the form of shocks or rotary oscillations.