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:
Nov. 06, 2007
Filed:
May. 18, 2005
Kohtaro Shiino, Kanagawa, JP;
Fumiyuki Yamaoka, Kanagawa, JP;
Tadaaki Fujii, Saitama, JP;
Toshiro Yoda, Saitama, JP;
Kohtaro Shiino, Kanagawa, JP;
Fumiyuki Yamaoka, Kanagawa, JP;
Tadaaki Fujii, Saitama, JP;
Toshiro Yoda, Saitama, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
An electric power steering system, includes a torque sensor disposed to a steering shaft to detect a steering torque. A first pinion is disposed to the steering shaft. A rack shaft is in mesh with the first pinion and connected with the steering shaft to change a rotational motion of the steering shaft to an axial motion of the rack shaft and provided to be operated in relation to the steering shaft. A first motor is connected with the first pinion to generate a steering assist torque in accordance with the steering torque detected by the torque sensor. A second pinion is disposed to be separate from the first pinion and in mesh with the rack shaft. A second motor is connected with the second pinion to generate a steering assist torque in accordance with the steering torque. A first control circuit is provided on a first control board for the first motor. A second control circuit is provided on the second control board for the second motor. The first control circuit monitors an abnormality in control state of the second control circuit and the second control circuit monitors an abnormality in control of the first control circuit.