Patent ID: 6286621
Filing Date: 2001-09-11
Classification: B62D

Abstract:
An electric power steering apparatus comprising:an electric motor applying an assist torque to a steering system;a steering torque detecting sensor detecting the magnitude and direction of a manual steering torque acted on said steering system;a control unit outputting a motor control signal for controlling said electric motor on the basis of a signal fed from said steering torque detecting sensor, said control unit having an assist inhibitor inhibiting the drive of said electric motor when the magnitude of the output from said steering torque detecting sensor is equal to or larger than a predetermined torque value and when the direction of the output of said steering torque detecting sensor and the direction of the assist torque of said electric motor are different for at least a predetermined time period, said assist inhibitor including a torque direction determining section determining the consistency/inconsistency between the direction of the manual steering torque detected by said steering torque detecting sensor and the direction of the assist torque by said electric motor, a timer timing the duration of inconsistency determination output from said torque direction determining section, a time comparator comparing the inconsistency duration from said timer with a predetermined time period to obtain a first inhibit signal, a torque comparator comparing the magnitude of the manual steering torque detected by said steering torque detecting sensor with a predetermined torque value to obtain a second inhibit signal, and an AND operator making an AND operation between the first inhibit signal of said time comparator and the second inhibit signal of said torque comparator to obtain an assist inhibit signal, and a motor controller which receives the assist inhibit signal and a signal based on the signal fed from said steering torque detecting sensor and which outputs the motor control signal; anda motor drive driving said electric motor on the basis of the motor control signal from said control unit.