Electric power steering system for vehicles

Claim 1

An electric power steering system for vehicles comprising: an input shaft connected to a steering wheel; an output shaft connected to a steered wheel; an interconnected member mechanically interconnecting said input shaft and said output shaft with each other; a direct-current motor operatively supplying auxiliary torque to said steering linkage; a torque detection means for detecting steering torque acting on said steering linkage; and a driving control circuit feeding and direct-current motor with a driving control signal in accordance with at least an output signal from said torque detection means, said driving control signal determining an armature voltage of said direct-current motor, said driving control circuit comprises a torque-representative signal producing circuit receiving said output signal from said torque detection means and producing, based on said output signal from said torque detection means, a torque magnitude signal representing a magnitude of said steering torque acting on said steering linkage, and a motor drive circuit having a differential amplifier and a feedback circuit, said feedback circuit feeding back said armature voltage from said direct-current motor to obtain a feedback signal, and said differential amplifier receiving said torque magnitude signal from said torque representative signal producing circuit and said feedback signal from said feedback circuit, and amplifying a difference therebetween for determining said driving control signal.