Electric power steering apparatus

Claim 1

An electric power steering apparatus comprising: an electric motor for assisting steering force; a torque sensor detecting a steering torque and producing a steering torque signal representative thereof; a broken line function circuit outputting an analog signal of a value corresponding to a broken line function based on the steering torque signal from the torque sensor; a target value generator producing a target value of motor current for driving the motor on the basis of said analog signal; a vehicle speed sensor producing a pulse signal representing detected vehicle speed; a digital vehicle speed--broken point characteristic processor determining a value of the steering torque signal corresponding to a broken point of the broken line function on the basis of the pulse signal from the vehicle speed sensor, and outputting a PWM signal corresponding to the determined steering torque signal value; and an analog broken point voltage control circuit converting said PWM signal outputted from said vehicle speed--broken point characteristic processor into an analog signal, and outputting said analog signal to said broken line function circuit as a broken point determining signal, wherein said broken line function circuit determines the broken line function in accordance with the broken point determining signal.