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:
Sep. 11, 1990
Filed:
Jan. 10, 1989
Hiroshi Ooishi, Osaka, JP;
Koyo Seiko Co., Ltd., Osaka, JP;
Abstract
A hydraulic power steering apparatus having a hydraulic cylinder as a source for generating a force assisting a steering force, and comprising a directional control valve which switches the feeding direction of pressured oil to the hydraulic cylinder, and a constraining device which constrains its switching operation responsive to the vehicle speed, characterized in that an oil pressure control valve for controlling oil pressure fed to the directional control valve and constraining device is controlled by pressure of a vehicle speed sensor pump which develops oil pressure corresponding to the vehicle speed, and in that a sudden change of a constraining force caused by external disturbance signals such as electromagnetic waves is prevented and the constraining force corresponding to the vehicle speed can be obtained, by introducing oil pressure, which becomes higher or lower responsive to changes of the vehicle speed, into the constraining device to generate the constraining force responsive to the oil pressure.