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. 08, 1998
Filed:
Aug. 12, 1996
Alan Crary Davis, Saginaw, MI (US);
Dennis Charles Eckhardt, Saginaw, MI (US);
Randy Scott Miller, Frankenmuth, MI (US);
General Motors Corporation, Detroit, MI (US);
Abstract
A closed center power steering gear having a spool shaft connected to a steering wheel of the motor vehicle, a pinion head connected to steered wheels of the motor vehicle, and a control valve between a fluid accumulator and a working chamber of a steering assist fluid motor. The control valve includes a poppet on the spool shaft having closed and open positions blocking and permitting, respectively, flow from the accumulator to the fluid motor working chamber, a cam on the pinion head, a cam follower on the spool shaft, and a pressure control spring between the cam follower and the poppet. The cam, the cam follower, and the pressure control spring cooperate during relative rotation between the spool shaft and the pinion head to shift the poppet to its open position. Boost pressure in the fluid motor working chamber increases and reacts against the poppet to compress the pressure control spring and shift the poppet to its closed position. The contour of the cam is calculated to cause steering assist boost pressure in the working chamber to increase at a rate faster than applied torque increases thereby to achieve a nonlinear relationship between boost pressure and applied torque.