Internal-combustion engines – Valve – Rotary
Reexamination Certificate
1999-09-10
2001-05-15
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Valve
Rotary
Reexamination Certificate
active
06230679
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to valve stem seals utilized in intake and exhaust manifolds of internal combustion engines.
BACKGROUND OF THE INVENTION
Valve stem seals having resilient seal bodies supported within rigid cylindrical casings are available in many designs and configurations. Most designs address the efficiency of the actual sealing lip portions of the seals which determine a controlled flow of oil between the seal lip and the valve stem.
Generally, the rigid cylindrical casing is supported on a valve stem guide with the inside diameter of the casing frictionally engaging the outside diameter of the guide. Previous designs have utilized tangs on the casing to grip the exterior surface of the guide to resist removal of the valve stem seal from the valve guide. However, the tangs of the prior art do not accommodate wide tolerance variations that are typically encountered with manufacturing valve stem guides. Thus, the tangs of the prior art require more precise valve stem guides to ensure that the tangs will adequately grab the outer diameter of the guide and resist pulling off of the seal. In addition, the tangs in cylindrical casings of the previous designs tend to have engagement along an entire edge of the tang that creates difficulties for aligning the valve stem seal relative to the valve guide and negatively impacts the resistance to removal.
SUMMARY OF THE INVENTION
The present invention is directed to a valve stem seal assembly having a resilient seal member with an outer periphery and an inner sealing surface and a generally cylindrical shell body having a longitudinal central axis and an end wall connected to a downwardly extending skirt. A first aperture is provided in the end wall for accommodating the resilient seal member and at least one alignment pad is provided in the skirt of the shell body wherein the alignment pad includes an inwardly projecting ramp portion connected to a generally longitudinally extending land portion and further including an inwardly projecting tang adjacent the land portion. Optionally, but preferably, the skirt is perforated at a predetermined location to form the at least one alignment tab. Also, the alignment tab terminates with the inwardly projecting tang for helping prevent unwanted removal of the valve stem seal assembly from a valve guide. Moreover, the at least one alignment tab can be a plurality of alignment tabs. Preferably, there are three alignment tabs circumferentially spaced apart around the skirt to provide increased contact area for alignment with valve guides having a greater variation in their outer diameter yet still provide improved positive retention of the valve stem seal assembly on the valve guide without substantially increasing the required installation force.
The present invention is also directed to a valve stem seal assembly having a resilient seal member with an outer periphery and an inner sealing surface and further including a first circumferential groove provided in the outer periphery. A generally cylindrical shell body having a longitudinal central axis and an end wall connected to a downwardly extending skirt is also provided. A first aperture provided in the end wall accommodates the first circumferential groove in the resilient seal member. In addition, a plurality of alignment pads are provided in the skirt of the shell body wherein each of the alignment pads includes an inwardly projecting ramp portion connected to a land portion that extends generally parallel to the central axis and further includes an inwardly projecting tang adjacent the land portion for improved positive retention of the valve stem seal assembly on a valve guide without substantially increasing required installation force.
Still further, the present invention is directed to a valve stem seal assembly having a resilient seal member mounted on a generally cylindrical shell body that includes a longitudinal central axis and an end wall connected to a downwardly extending skirt. A first aperture is provided in the end wall for accommodating the resilient seal member and at least one tang is provided in the skirt of the shell body wherein the tang includes a free end having a generally arcuate region that is generally perpendicular to the radius of curvature of the inner cylindrical surface of the skirt. In one embodiment, the arcuate region is located between a pair of spaced apart upwardly extending shoulders for gripping a valve guide.
Accordingly, the present invention provides an improved valve stem seal assembly having alignment pads that accommodate a wide variety of manufacturing tolerances for the outer diameter of a valve stem guide while maintaining positive retention of the valve stem seal assembly to the valve guide without substantially increasing the required installation force.
In addition, the present invention provides an improved valve stem seal assembly having tangs with a pair of upwardly extending shoulders for improved gripping of a valve guide to better resist unwanted removal of a valve stem seal assembly.
REFERENCES:
patent: 3771800 (1973-11-01), Wilson et al.
patent: 4502696 (1985-03-01), Kammeraad
patent: 4509473 (1985-04-01), Hamparian
patent: 4773363 (1988-09-01), Stritzke
patent: 4811704 (1989-03-01), Boehmer et al.
patent: 4909202 (1990-03-01), Binford et al.
patent: 4947811 (1990-08-01), Binford
patent: 5237971 (1993-08-01), Worsley
Hegernier Timothy A.
Lehmann Robert W.
Stamback Mark A.
Ali Hyder
Dana Corporation
Kamen Noah P.
Rader & Fishman & Grauer, PLLC
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