Gm Global Technolgoy Operations, Inc.

John F Yonker

Albert C Wong

Paul O Wendler

Michael T Masica

Kenneth John Hill

Brian D Brasier

Rack and pinion steering gear with hydraulic power assist that is reduced as the vehicle wheels approach their positive wheel stops so that hydraulic loads on the steering gear and linkage are reduced and the power steering pump is not forced to excessive operation in relief.

Hydraulically power assisted steering gear with pressure relief stop

An auxiliary pump system for providing detent pressure in a detent-type variable effort power steering system. The auxiliary pump system includes a gerotor-type auxiliary pump mounted on the transmission of the vehicle and driven at a speed proportional to vehicle speed. The primary power steering pump supplies power steering fluid to the power steering gear and all of the power steering fluid exhausting from the steering gear is directed to the intake of the auxiliary pump. The auxiliary pump produces detent pressure when the vehicle is in motion proportional to vehicle speed and the overage of power steering fluid is directed back to the power steering pump reservoir. From a cold start, the power steering fluid consumed by the auxiliary pump heats faster due to passage through the power steering pump than if drawn directly from the reservoir thereby to minimize the duration during which detent pressure is susceptible to viscosity induced pressure instability.

Auxiliary pump system for variable effort power steering

A method of regulating the flow of hydraulic fluid to a hydraulic assist power steering system for providing assist capability which decreases with increasing vehicle speed but which is prevented from falling below a predetermined level in response to handwheel rotation regardless of vehicle speed.

Flow regulated power assist steering system with evasive maneuver

A demand responsive flow regulator valve for use with a power steering pump and steering mechanism has a valve spool slidably disposed in a housing and responsive to a pressure differential across an orifice for the purpose of bypassing excess pump flow. The flow control orifice establishes pressure signals proportional to pump flow to the steering mechanism. The pressure signals are operative on the valve spool to control the bypassing of excess pump flow. A spring loaded metering rod disposed in the flow control orifice increases the effective area of the orifice when pressure demand at the steering mechanism increases thereby increasing the fluid flow to the steering mechanism while simultaneously decreasing the bypass flow.

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Frankenmuth, MI, United States of America

John F Yonker