Patent ID: 6328128
Filing Date: 2001-12-11
Classification: B62D,G01L

Abstract:
An electric power steering apparatus comprising:a housing;an output shaft for outputting a steering force so as to steer vehicle wheels;an input shaft for transmitting the steering force from a steering wheel to said output shaft;a torsion member for connecting said input shaft to said output shaft while being resiliently twisted in correspondence with a steering torque applied to said input shaft;a motor attached to said housing for imparting an auxiliary steering force to said output shaft;a power transmitting mechanism, which couples a rotating shaft of said motor with said output shaft so as to transmit the auxiliary steering force from said motor to said output shaft;a detecting device for detecting a torsion amount of said torsion member and also outputting a detection signal corresponding to said torsion amount;a control unit for controlling said motor on the basis of the detection signal from said detecting device; anda limiting member for limiting a relative rotation between said output shaft and said input shaft so as to inhibit the torsion of said torsion member from becoming a limit angle or more,wherein said detecting device outputs a first detection signal converted by a first conversion ratio with respect to the torsion when the torsion of said torsion member is within a predetermined angle which is smaller than the limit angle, and said detecting device outputs a second detection signal converted by a second conversion ratio which is lower than the first conversion ratio when the torsion of said torsion member has exceeded the predetermined angle.