Search International and National Patent Collections

1. (WO2005105548) ELECTRIC POWER STEERING APPARATUS

Pub. No.:    WO/2005/105548    International Application No.:    PCT/JP2005/007943
Publication Date: Nov 10, 2005 International Filing Date: Apr 20, 2005
IPC: B62D 5/04
B62D 6/00
Applicants: NSK LTD.
日本精工株式会社
NSK STEERING SYSTEMS CO., LTD.
NSKステアリングシステムズ株式会社
SAKAGUCHI, Toru
坂口 徹
FUKUDA, Mitsuhiro
福田 充宏
NOMURA, Yasuhide
野村 康継
Inventors: SAKAGUCHI, Toru
坂口 徹
FUKUDA, Mitsuhiro
福田 充宏
NOMURA, Yasuhide
野村 康継
Title: ELECTRIC POWER STEERING APPARATUS
Abstract:
An electric power steering apparatus comprising a controller for judging whether or not a motor current detector fails from the difference between the motor current estimate and the motor current detected value and having a high safety. A current command value operating unit (22) operates a current command value Ir which is the control target value of the motor current to supply an assisting torque according to the inputted torque signal. An abnormality detecting unit (30) is composed of a motor current estimator (31) and an abnormality judger (32). The motor current estimator (31) operates a motor current estimate Ie according to the current command value Ir computed from a steering torque value. The abnormal judger (32) computes the absolute value j (=|Ie-id|) of the difference between the motor current estimate Ie and a motor current detected value id, counts the number of times n that the absolute value j of the difference exceeds a predetermined threshold S for a predetermined time, and counts the cumulative number N of the number of times n that the absolute value exceeds the threshold S for a predetermined period. When the cumulative number N exceeds a predetermined abnormality judgment reference number of times Z, the motor current detector (42) is judged to be abnormal.