Servo steering control for automobile

摘要

A constantly running electric motor 3 drives the hydraulic pump 2 in the electrohydraulic system of fig. 1 or a pair of oppositely rotating output gears (8, 9) in the electromechanical system (fig. 2). The load against which the motor 3 has to work is detected by a control unit 7 eg on the basis of the internal resistance of the motor or the drop in voltage at the motor. The control unit 7 switches the motor to high output when the load is high so that if no servo power is required, the motor operates at very low output. Since only electrical parameters need to be monitored the extra cost of the motor control unit is low. <IMAGE>