The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 05, 2010
Filed:
Aug. 28, 2007
Kenichi Hamada, Kanagawa, JP;
Tamotsu Yamaura, Kanagawa, JP;
Atsushi Matsuoka, Kanagawa, JP;
Yutaka Makino, Kanagawa, JP;
Kenichi Hamada, Kanagawa, JP;
Tamotsu Yamaura, Kanagawa, JP;
Atsushi Matsuoka, Kanagawa, JP;
Yutaka Makino, Kanagawa, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A power steering apparatus includes an electric motor, a temperature sensor, and a control unit. The electric motor produces an assist steering effort in a steering system. The temperature sensor measures a temperature of a first portion subject to thermal influence of operation of the electric motor. The control unit determines an estimated temperature of a second portion in accordance with a value of a motor current, the second portion being subject to thermal influence of operation of the electric motor. The control unit determines a first upper limit value in accordance with the measured temperature; determines a second upper limit value in accordance with the estimated temperature; limit the motor current to a smaller one of the first and second upper limit values, when determining that the temperature sensor is normal; limit the motor current to the second upper limit value, when determining that the temperature sensor is abnormal.