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. 16, 2001
Filed:
Nov. 06, 1998
Frederick D. Venable, Lafayette, IN (US);
Bernard C. Hudgens, West Lafayette, IN (US);
Lowell D. Stingley, Clarks Hill, IN (US);
Gary L. Vandermolen, Fort Wayne, IN (US);
TRW Inc., Lyndhurst, OH (US);
Abstract
A switching valve (,) for a hydraulic power steering system (,) includes a longitudinally movable valve spool (,). A spring (,) biases the spool (,) to a neutral position. The switching valve (,) is configured to direct hydraulic fluid from a primary pump (,) to a steering control valve (,) when the spool (,) is in a primary position, and to direct hydraulic fluid from an auxiliary pump (,) to the control valve (,) when the spool (,) is in an auxiliary position. The spool (,) is movable against a bias of the spring (,) from the neutral position to the primary position under the influence of a hydraulic fluid pressure differential between the opposite ends of the spool (,). The switching valve (,) defines a flow path for directing hydraulic fluid from the primary pump (,) to an end of the spool (,) when the spool (,) is in the neutral position. The flow path extends axially over a flat portion (,) of an outer surface of the spool (,).