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:
Feb. 20, 1990
Filed:
Nov. 16, 1988
Michael A Ferguson, Birmingham, MI (US);
General Motors Corporation, Detroit, MI (US);
Abstract
A bypass type variable effort power steering system including a bypass valve in a bypass duct connected at opposite ends to the working chambers of a steering assist fluid motor and a throttling valve in the bypass duct in series flow relationship with the bypass valve. The throttling valve has a valve element spring biased to a centered position between valve seats of the throttling valve. When the bypass valve is open, the springs hold the valve element in the centered position until bypass flow exceeds a transition flow rate characteristic of substantial pressure differences between the working chambers of the fluid motor. At bypass flow rates above the transition flow rate, a pressure force is induced on the valve element which overcomes the spring force and moves the valve element to a seated position on one of the valve seats. When the valve element is seated, bypass flow is blocked and power assist is maximized.