Seal for a joint or juncture – Seal between fixed parts or static contact against... – Contact seal between parts of internal combustion engine
Reexamination Certificate
2001-07-25
2004-03-09
Knight, Anthony (Department: 3676)
Seal for a joint or juncture
Seal between fixed parts or static contact against...
Contact seal between parts of internal combustion engine
C277S627000, C277S652000
Reexamination Certificate
active
06702296
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to gaskets and more specifically to gaskets with seal enhancement zones positioned at selected locations within a web or webs of the gasket.
BACKGROUND
A typical gasket for use in, for example, internal combustion engines comprises a base sheet that is die cut from gasket material and has one or more internal apertures surrounded by a web or webs of the gasket. As described in substantial detail in the incorporated U.S. patent application, an enhanced seal can be achieved in gaskets by forming a polymer coating on the cut interior edges that surround and bound the interior apertures of the gasket. These edge coatings can take on a variety of configurations including edge-wrapped and non edge-wrapped coatings, coatings that define raised lips surrounding internal apertures, and even coatings on exterior edges of the gaskets. Such gaskets generally are referred to herein as “edge-coated gaskets.”
While edge-coated gaskets form an improved seal as compared to traditional gaskets in a wide variety of gasketing situations, there are nevertheless some cases in which an improved seal may not be required or desired around the entire surrounding edge of a gasket aperture. For example, an adequate seal may exist with no edge coating at all in regions adjacent to bolt holes where clamping pressures on a gasket are high, while an enhanced seal still may be needed in other regions spaced from bolt holes where clamping pressures can be significantly lower. In other cases, a coating on the interior edge of a gasket may not be feasible, such as, for instance, in gaskets with relatively narrow webs. Nevertheless, an enhanced seal in certain regions of the gasket still may be needed. In still other cases, a gasket with an edge coating surrounding an interior aperture may nevertheless require an enhanced seal in other selected regions of the gasket, such as in regions of the gasket's web between widely spaced bolt holes. In these and other cases, aperture only edge-coated gaskets such as those disclosed in the incorporated disclosure are not always optimal.
In the past, attempts to provide an enhanced seal within selected regions or zones of a gasket web have included simply applying a bead of a rubber or polymer based sealant to the surface of the gasket web. The theory is that when the gasket is clamped between a pair of flanges, the bead of sealant will be compressed between the gasket web and a flange to provide an enhanced seal within the region of the gasket where the bead is located. While such solutions can be somewhat successful, they nevertheless have certain inherent problems and shortcomings. For instance, beads of sealant applied to a gasket's surface increase the effective thickness of the gasket in the region of the bead. This can result in less than optimal distribution of clamping forces when the gasket is clamped between a pair of flanges, which can degrade rather than enhance the resulting seal. Further, surface applied sealant beads generally have not been proven to provide a completely satisfactory barrier against interfacial migration of fluid across the web faces of the gasket.
Thus, a need exists for a gasket that provides an enhanced seal in selected regions or zones where additional sealing is required without the problems and shortcomings inherent in surface sealant beads and other methods used in the past to provide such selectively positioned seal enhancement zones. It is to the provision of such a gasket and a unique method of forming the gasket that the present invention is primarily directed.
SUMMARY OF THE INVENTION
Briefly described, the present invention, in a configuration that is simplified for clarity of discussion, comprises a generally rectangular gasket characterized by a single interior aperture surrounded by a web of gasket material having a predetermined width. The interior edge that bounds the aperture of the gasket may or may not be provided with a polymer edge coating as described in the incorporated disclosure, or, alternatively, only portions of the interior edge may be coated. Seal enhancement zones are strategically located in selected regions within the web of the gasket such as, for instance, in regions between widely spaced bolt holes where an enhanced seal is needed. Within each seal enhancement zone, a relatively narrow slot is cut in the web where an enhanced seal is desired. The position of the slot may correspond, for example, to the position where a bead of sealant would be applied to the surface of the gasket in the prior art methods discussed above. The cut edges that bound the slot are then coated with a polymer edge coating in the manner described in the incorporated disclosure with the edge coating preferably defining raised lips that rim the slot. In any event, when the gasket is clamped between a pair of flanges, the polymer edge coating of the slot is compressed to provide a reliable enhanced seal along the length of the slot within the seal enhancement zone. Because the polymer edge seal surrounds the slot, the polymer material itself is able to bulge or deform into the slot rather than being flattened or smashed between the flange and the surface of the gasket web when the gasket is clamped in place. Thus, an enhanced seal is provided within the seal enhancement zone without affecting the distribution of clamping forces on the gasket. Further, since the polymer coating on the edges of the slot is compressed rather than smashed, an improved, more reliable, and more permanent seal is created at the location of the seal enhancement zone.
The gasket base sheet in the present invention may be formed of any suitable gasket material, such as a fibrous porous gasket material, that is die or otherwise cut to form a desired gasket shape. The edge coating that lines each slot in the seal enhancement zone may take on any of a variety of configurations including a wrapped edge coating, a coating that defines raised rims, or a variety of others as dictated by application-specific sealing requirements. The polymer material of the edge coating preferably intrudes or penetrates a predetermined distance into the porous material of the gasket base sheet to form an intrusion zone that seals against interstitial leakage and that binds the edge coating securely to the edge of the slot. Gaskets according to the present invention may include a plurality of seal enhancement zones selectively positioned and configured within any region of the gasket where an enhanced seal is desired.
The present invention also is directed to methods of making gaskets having one or more seal enhancement zones. One embodiment of the method includes the steps of providing a plurality of base sheets each having opposed faces and a slot bounded by an edge located in a seal enhancement zone, stacking the plurality of base sheets together with their slots aligned to define the walls of a narrow cavity, contacting the walls of the cavity with a coating material to deposit a layer of coating material on the aligned slot edges, and separating individual base sheets from the stack to form edge-coated slots with raised rims. The coating material may be applied to the cavity walls in a variety of ways, some of which are set forth herein. The present invention also includes a gasket formed by such a process.
The invention further includes an engine incorporating one or more gaskets with edge-coated slots located in selected seal enhancement zones. Such an engine may include a block with at least one fluid conduit formed therein that is sealed at a junction by a gasket having selectively positioned seal enhancement zones.
Thus, an improved gasket with selectively positioned seal enhancement zones is now provided. The gasket offers strategically positioned enhanced seals in situations where gaskets having only edge-coated internal apertures, such as those of the incorporated disclosure, may not be desirable or feasible, and also in situations where such gaskets are employed but an enhanced seal in selected regions is neverthe
Interface Solutions, Inc.
Knight Anthony
Patel Vishal
Womble Carlyle Sandridge & Rice PLLC
LandOfFree
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