Electric power steering apparatus

An electric power steering apparatus for use with an automotive vehicle, comprising:

• an electric motor for applying an electric steering assist to a steering system of the vehicle;
• a steering angle sensor for detecting a steering angle in the steering system;
• a steering torque sensor for detecting steering torque in the steering system;
• a vehicle velocity sensor for detecting a velocity of the vehicle;
• a control unit for setting a motor control signal to control operation of said electric motor on the basis of at least the steering torque detected by said steering torque sensor and the vehicle velocity detected by said vehicle velocity sensor;
• a motor drive for driving said motor on the basis of the motor control signal set by said control unit;
• and
• a steering torque estimating section provided in said control unit for estimating the steering torque on the basis of the vehicle velocity detected by said vehicle velocity sensor and the steering angle detected by said steering angle sensor and not on the basis of the steering torque detected by the said steering torque sensor,
• whereby when said steering torque sensor is judged to be malfunctioned, said control unit controls the operation of said electric motor on the basis of the steering torque estimated by said steering torque estimating section.