Motor-driven power steering unit

Claim 1

A motor-driven power steering unit for use in a motor vehicle said motor-driven power steering unit comprising: a body, a steering wheel, steerable wheels, and a steering linkage including tie rods coupled to said steerable wheels and interconnecting said steering wheel and said steerable wheels, said steering linkage further including a steering shaft rotating in unison with said steering wheel, a drag link operatively coupled to said steering shaft to move in the longitudinal direction thereof, and means for coupling said steering shaft with said drag link and for conveying rotational movement of said steering shaft to linear movement of said drag link; a case fixed to said body; a first shaft rotatably supported in said case; a second shaft rotatably supported in said case coaxially with said first shaft; a first lever having one end connected to said first shaft and the other end coupled to said drag link; a second lever having one end connected to said second shaft and the other end coupled to said tie rods; a torsion bar interposed between said first and second shafts and interconnecting said first and second shafts; torque detecting means interposed between said first and second shafts for detecting the steering torque applied from said steering wheel to said first shaft to generate a signal indicative of the detected torque; a motor disposed in said case for applying an assistive torque to said second shaft; a power supply for energizing said motor; and control means responsive to the signal from said torque detecting means for controlling the torque generated by said motor.