Brakes – Internal-resistance motion retarder – Valve structure or location
Reexamination Certificate
1999-08-31
2001-07-17
Oberleitner, Robert J (Department: 3613)
Brakes
Internal-resistance motion retarder
Valve structure or location
C188S315000, C188S322130
Reexamination Certificate
active
06260678
ABSTRACT:
TECHNICAL FIELD
This invention relates to fluid dampers for vehicles, and more specifically, to a blow-off valve for use on a base valve assembly to provide digressive performance during compression of the damper.
BACKGROUND OF THE INVENTION
Fluid vehicle dampers, such as hydraulic shock absorbers and struts, provide a smooth ride by absorbing forces that are generated by an uneven road surface. Two common types of vehicle fluid dampers are mono-tube and twin tube shock absorbers, each of which have a cylinder and piston. Twin tube shock absorbers have a valve body located at an end of the piston, commonly referred to as a piston valve, and at a cylinder end, commonly referred to as a base valve. The piston valve moves toward the base valve during compression of the shock absorber and moves away from the base valve during rebound. The valve bodies divide the shock absorbers into several fluid chambers and regulate the flow of fluid from one chamber to another thereby achieving particular ride handling characteristics. Typically, each valve body has a compression and rebound valve assembly located on opposing surfaces of the valve body that regulate fluid flow during the compression and rebound strokes. By modifying the valve assemblies, the ride handling characteristics may be calibrated.
It is desirable to have different rates of piston damping depending on vehicle ride condition. For example, during vehicle cornering maneuvers in which the piston undergoes low speed compression, it is desirable to have stiff ride handling characteristics. Conversely, when the vehicle travels over pot holes at relatively high vehicle speeds in which the piston undergoes high speed compression, it is desirable to have soft ride handling characteristics. The base valve assembly is the primary control of damping during compression. One way to best achieve different rates of damping is to provide a base valve assembly having digressive performance, that is, a base valve which provides generally independent and distinct damping rates during low and high speed piston compression. Prior art base valve assemblies have only provided low and high piston speed damping rates which are dependent on one another thereby compromising ride handling characteristics at low and high vehicle speeds. Therefore, what is needed is a base valve assembly that provides digressive performance.
SUMMARY OF THE INVENTION
The present invention provides a base valve assembly for regulating the flow of fluid through a twin-tube fluid vehicle damper. The base valve assembly has opposing compression and rebound surfaces. Inner and outer annular seats extend from the compression surface and define an annular channel therebetween. At least one fluid passageway connects the annular channel and the rebound surface for providing fluid communication therebetween. A connector secures a blow-off valve to the cylinder end. The blow-off valve has a hollow cylindrical portion with a flange extending transversely from an end thereof. The flange is adjacent the annular seats when the blow-off valve is in a closed position. The blow-off valve is movable from the closed position to an open position away from the compression surface. A helical spring is interposed between the connector and the blow-off valve for biasing the blow-off valve to the closed position. A low speed compression bypass valve is interposed between the annular channel and the blow-off valve for permitting fluid to exit the annular channel past the blow-off valve when the blow-off valve is in the closed position. The blow-off valve provides performance during compression of the damper.
Accordingly, the present invention provides a base valve assembly that provides digressive performance with generally independent and distinct damping rates during low and high speed piston compression.
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Moradmand Jamshid Kargar
Neal Robert Alan
Nunke William R.
Delphi Technologies Inc.
Kramer Devon
Oberleitner Robert J
Sigler Robert M.
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