Motor-driven type power assisted steering control apparatus

Claim 1

A motor-driven type power assisted steering control apparatus in a steering system having a rack which comprises: a speed sensor for detecting car speed; a torque sensor comprising torque-displacement converting means disposed on a steering shaft for converting a torque of steering into an amount of displacement of said torque-displacement converting means, at least one displacement conveying means for mechanically transmitting the amount of displacement of said torque-displacement converting means, and first and second displacement-electric signal converting means for converting the amount of displacement given by said displacement conveying means into electric signals; a d.c. motor; an electromagnetic clutch directly connected to the output shaft of said d.c. motor and operatively connected to said rack; and control unit having means for receiving electric output signals from said speed sensor and said first and second displacement-electric signal converting means, means for judging whether a difference in value between the electric output signals from said first and second displacement-electric signal converting means is higher than a predetermined signal value, and means for deenergizing said d.c. motor and said electromagnetic clutch based on the judgment that said torque sensor is abnormal, when said difference in value is higher than said predetermined value, whereby an auxiliary torque of said d.c. motor is disconnected from said steering shaft.