Patent ID: 8579072
Filing Date: 2013-11-12
Classification: B62D

Abstract:
1. An electric power steering system comprising: a steering mechanism having an input shaft side rotation angle sensor provided at an input shaft side and detecting a rotation angle of the input shaft; an output shaft side rotation angle sensor provided at an output shaft side and detecting or estimating a rotation angle of the output shaft; an electric motor providing a steering assist force to the steering mechanism; an operation circuit calculating, on the basis of a vehicle driving condition, a command current value that is sent to the electric motor; a rotation direction judging circuit provided in the operation circuit and judging whether or not a rotation direction of the input shaft and a rotation direction of the output shaft are identical; an advanced-phase judging circuit provided in the operation circuit and judging which phase of an input shaft side rotation angle signal that is an output signal of the input shaft side rotation angle sensor and an output shaft side rotation angle signal that is an output signal of the output shaft side rotation angle sensor is advanced; a normal/reverse input judging circuit provided in the operation circuit and judging that a command current correcting circuit provided in the operation circuit and correcting the command current value for the electric motor so that when the normal input is judged by the normal/reverse input judging circuit, a generation torque in the same direction as the rotation direction of the input shaft by the electric motor is greater than that of a case where the reverse input is judged by the normal/reverse input judging circuit.