Gm Global Technolgoy Operations, Inc.

Stanley E Anderson, Jr

Leonard N Franklin, Jr

Gary G Hegler

John H Christ

James Michael Shea

Michael F Tobin

Robert P Rohde

A demand responsive flow control valve mechanism has a valve member which receives fluid flow from a power steering pump and delivers a predetermined amount of fluid to an operating system such as the power steering gear. The excess fluid delivered by the pump is directed by the valve member to a bypass port from which the excess fluid is returned to the pump or a reservoir. The fluid flow to the operating system is controlled by differential areas disposed on a spool valve and a flow regulating orifice sensitive to system flow from determining the pressure differential to be applied to the differential areas. The operating system has a variable orifice which serves as a demand regulator for establishing the pressure level requirements for the pump. The valve spool responds to the pressure differential and system pressure level to bypass fluid as required. A pair of check valves are disposed in the spool valve and are operable to provide two stages of pressure relief for the operating system.

Demand responsive flow control valve

A combined power steering pump and vacuum pump assembly is disclosed wherein a vented reservoir is connected to receive the discharge of the vacuum pump as well as supply the fluid for circulation by and lubrication of the power steering pump. A sealing arrangement seals the vacuum pump from the power steering pump when the pumps are stopped but provides limited delivery of the fluid from the power steering pump to the vacuum pump when the pumps are running whereby the fluid in the power steering system is prevented from draining into the vacuum pump when stopped and is delivered thereto when running to lubricate same and is then delivered with the discharge air to the reservoir so that there is no loss of the fluid from the power steering system in lubricating the vacuum pump.

Combined vacuum pump and power steering pump assembly

A hydraulic power steering system has a vane type pump which is operable to supply fluid to a power steering gear at a volumetric rate determined in part by the system pressure requirement or system demand. The pump flow is partially bypassed through an aperture in the cam ring at low system pressures. The bypass flow is controlled by a sleeve valve surrounding the cam ring and being subjected to system pressure to incrementally close the aperture and reduce bypass flow and simultaneously increase the output flow. At a predetermined system pressure, the valve is moved sufficiently to control reopening of the aperture for controlled bypass flow to limit the maximum system pressure.

Demand responsive hydraulic pump

A hydraulic power steering system has a vane type pump which is operable to supply fluid to a power steering gear at a volumetric rate determined in part by the system pressure or system demand. The pump flow is partially bypassed through a valve member which is slidably disposed in the thrust plate of the pump. The thrust plate has a bypass aperture which communicates between the pump discharge and the pump inlet. The valve member is spring loaded to permit fluid communication through the apertures and is pressure biased by increasing system pressure to reduce the bypass flow and thereby increase system discharge flow.

A remote reservoir power steering type pump has a shaft seal which prevents shaft bearing lube flow from leaking to atmosphere. The lube flow is derived from internal pump leakage along the shaft. This fluid must be returned to the main system fluid. In remote reservoir type pumps, the pressure inside the pump housing is greater than atmospheric pressure due to the supercharge gained through aspiration. The shaft seal area is maintained at substantially atmospheric pressure by bleeding or draining this area to the supply port which is not subjected to the supercharge pressure thereby maintaining the seal area at the lower pressure.

Power steering pump drive shaft seal area drain structure

A power steering gear having a piston nut fed with pressure fluid from a source through a rotary valve. The construction includes a special one-way valve assembly in the high pressure port which is formed by a plunger which seats into the end of the steel tube of the power steering hose. The plunger tube and external O-ring provides for improved sealing of the power steering gear to prevent external leaks and to provide for improved control of flow into the housing from the source and to block flow from the housing into the high pressure port so that road excited vibrations are not fed back to the vehicle handwheel.

Power steering gear with flow check valve

This power steering gear has steering travel limiter for controlling the input rotation so that the hydraulic valve of the gear cannot be moved to a closed position previously established by contact of the wheel stop or internal stop in the gear. The limiter in the preferred embodiment employs a series of rings which are engaged in series in response to handwheel input and which prevent rotation of the input beyond a certain point at or inboard of internal stops or the wheel stops so that the valving of the gear cannot close to a point requiring the power steering pump to operate in relief.

Steering travel limiter for power steering gear

The piston nut of this compact steering gear telescopes over the valve assembly and into an adjuster plug at opposite ends of its stroke to provide for a foreshortened gear housing. The piston nut screw is connected to the valve assembly and the input stub shaft by a special retainer means to prevent their axial separation to maintain the integrity of the mechanical drive of the piston nut. The adjuster plug provides a thrust bearing adjustment, a closure for the gear and a travel stop for the piston nut when telescoping therein. The stepped bore in the housing provides for improved assembly of the parts from one end of the housing through the opening for the adjuster plug.

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Saginaw, MI, United States of America

Stanley E Anderson, Jr