Motors: expansible chamber type – With motive fluid valve – To provide unequal inlet and exhaust flow rates to single...
Reexamination Certificate
2001-04-27
2003-03-25
Rivell, John (Department: 3753)
Motors: expansible chamber type
With motive fluid valve
To provide unequal inlet and exhaust flow rates to single...
C091S447000, C137S519500, C138S046000
Reexamination Certificate
active
06536328
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a damper valve for a hydraulic power-assisted steering system, and more particularly, to a damper valve located between a control valve and a power steering motor in a hydraulic power-assisted steering system.
BACKGROUND OF THE INVENTION
It is known to locate a damper valve between a control valve and a power steering motor in a hydraulic power-assisted steering system. Generally, a damper valve is associated with each hydraulic conduit that connects the control valve to the power steering motor.
U.S. Pat. No. 6,003,427 discloses a damper valve for use in a hydraulic power-assisted steering system. The damper valve includes axial bores that are covered by spring plates. Recesses allow fluid access to each axial bore and as fluid pressure within the respective axial bores increases, the spring plate opposite the recess flexes to allow fluid flow through the damper valve. The damper valve also includes a bolt with an axial duct. The axial duct acts as a fluid bypass allowing fluid flow through the damper valve without passing through an axial bore. An adjustable screw partially extends into the axial duct of the bolt to restrict the flow of the fluid bypass. The adjustable screw allows the bypass flow through the axial duct to be calibrated.
SUMMARY OF THE INVENTION
The present invention is a damper valve located between a control valve and a power steering motor in a hydraulic power-assisted steering system. The damper valve comprises a housing having axially opposite first and second end portions and an intermediate portion interposed between the first and second end portions. The first end portion is for fluid communication with the control valve and the second end portion is for fluid communication with the power steering motor. A flow restricting element is located within the housing and is movable through portions of the housing including the intermediate portion by fluid flow through the housing. The damper valve further includes a biasing element for restraining movement of the flow restricting element toward the first end portion of the housing. An orifice is formed between the flow restricting element and the housing for restricting fluid flow greater than a predetermined amount through the housing from the second end portion toward the first end portion.
REFERENCES:
patent: 3106226 (1963-10-01), Machen
patent: 3367362 (1968-02-01), Hoffman
patent: 3489172 (1970-01-01), Whitmore
patent: 3837362 (1974-09-01), Barnes
patent: 4022113 (1977-05-01), Blatt
patent: 4704947 (1987-11-01), Schneider
patent: 4770212 (1988-09-01), Wienck
patent: 4830046 (1989-05-01), Holt
patent: 5505276 (1996-04-01), Luibrand
patent: 5584226 (1996-12-01), Roemer et al.
patent: 5593004 (1997-01-01), Blain
patent: 6003427 (1999-12-01), Asbrand et al.
patent: 6202678 (2001-03-01), Hawkins
Rivell John
Tarolii, Sundheim, Covell & Tummino L.L.P.
TRW Inc.
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