Patent ID: 6983817
Filing Date: 2006-01-10
Classification: B62D

Abstract:
1. A power steering device wherein a steering torque applied to a handle shaft through a steering handle is detected by torque detection means which is provided with a torsion bar and a pair of angle detection sensors arranged apart from each other in an axial direction of said torsion bar and wherein a command signal is issued from a steering control section for applying a drive power corresponding to said steering torque from an electric motor as assist power generating means to steerable wheels, said power steering device comprising: initial torque detection command means including: (a) first torque detection means for rotating said steering handle a predetermined rotational angle in one direction about the handle axis to a first position after said steering handle is held stationarily at a neutral position in the steering direction and for detecting a first torque value by said torque detection means with said steering handle being stopped at said first position, said first torque value including a residual torque which exists as hysteresis between said steering handle and said torque detection means; (b) second torque detection means for rotating said steering handle by said electric motor from said neutral position the same rotational angle in the other direction and for detecting a second torque value, also including another residual torque, by said torque detection means with said steering handle being stopped at said second position; and (c) initial torque setting means for calculating an average value of said first and second torque values to cancel positive and negative-going residual torques included said first and second torque values and for setting said calculated average value as an initial torque which is generated by the cause of the difference between origin positions of said pair of angle sensors; and initial torque storage command means for issuing a command to store said initial torque as a compensation value for said steering torque in initial torque storage means of said steering control section.