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:
Aug. 29, 1995
Filed:
Aug. 01, 1994
Randy S Miller, Frankenmuth, MI (US);
Brian J Magnus, Saginaw, MI (US);
General Motors Corporation, Detroit, MI (US);
Abstract
A motor vehicle power steering system including a hydraulic pump, a fluid motor, and an electronic control valve which regulates boost pressure independent of pump discharge flow rate so that the pump does not require a constant flow valve. The flow area of a throttling orifice which determines the magnitude of boost pressure depends on the magnitude of a pilot pressure in a pilot pressure chamber behind a valve spool of the electronic control valve. The pilot pressure is regulated by a solenoid controlled pintle. The duty cycle of the solenoid is controlled in open-loop fashion by an electronic control module of the power steering system in response to signals from a steering wheel torque sensor of the power steering system. Fluctuations in the discharge flow rate of the hydraulic pump attributable to changes in engine speed induce spool movements to increase or decrease the flow area of the throttling orifice to maintain boost pressure consistent with the scheduled pilot pressure. A direction control valve responds to the direction of steering wheel torque to expose either a right turn or left turn working chamber of the fluid motor to boost pressure.