Seal for a joint or juncture – Seal between fixed parts or static contact against... – Contact seal between parts of internal combustion engine
Reexamination Certificate
1998-06-08
2001-06-05
Knight, Anthony (Department: 3626)
Seal for a joint or juncture
Seal between fixed parts or static contact against...
Contact seal between parts of internal combustion engine
C277S627000, C277S650000
Reexamination Certificate
active
06241253
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
Gaskets having an edge coating on at least one vertical edge (lying between the two faces of the gasket) of the gasket is provided. The edge coating provides a much greater sealing ability to soft gasket material. The present invention offers gasket edge coatings which are optimized and thus improved. Edge coatings can be put on gaskets to intentionally obtain a total seal against fluids.
The sealing ability of soft gasket materials is extremely important, and has been the focus of considerable development effort. The edge coating is one feature which has recently been developed to provide a greater sealing ability to the gasket. Advantageously, the edge coating allows the remainder of the gasket to optionally and preferably have no coating. When the gasket is uncoated, or has only a release coating, the compression failure resistance of the gasket is preserved.
Many features have been used with gaskets in order to provide good or better sealing ability, particularly against fluids.
Beading on the face of the gasket is known. Such beading is a raised area put on the face. Beading, however, does not extend past the edge, and does not extend onto the edge. Although the beading is used to enhance sealing ability, the beading fails to consistently provide a perfect seal.
One gasket material which is offered to provide a good seal at high temperatures is described in U.S. Pat. No. 5,240,766. This reference describes a soft gasket sheet material having fiber, filler and binder. According to the reference, the filler component provides a desirable sealability.
Another reference which describes gasket sheet materials that provides good sealing properties is U.S. Pat. No. 5,437,767. This reference describes a gasket sheet material with fiber and filler. The filler component must include a gel-forming mineral. This filler gives the gasket good sealing properties, especially against polar liquids.
Yet another type of gasket reference relies on coatings to provide or enhance the sealing ability of the gasket. For example, U.S. Pat. No. 4,499,135 impregnates the gasket with a silicone resin to improve resistance to water/antifreeze mixtures; U.S. Pat. No. 3,661,401 requires that the gasketing is given a coating which covers the entire gasket, vertical edges included; and U.S. Pat. No. 4,600,201 impregnates the gasket mat with a polymerizable liquid impregnating agent and applying to at least one part of at least one mat face, a coating containing a polymerizable polymer material. Gasketing which is completely coated, however, in general will perform poorly at higher pressures, which severely limits the field of use of the gaskets.
It has been discovered that by edge-coating the vertical edges of gaskets, especially the vertical edges around an aperture, and optionally the outer edge of the gasket, the resulting gasket will give a good and even a total seal against fluids. The present invention, however, describes how these edge coatings can be optimized to provide better sealing ability and to more consistently provide total seals.
Accordingly, it is an object of the present invention to describe an optimized edge coating for the vertical edges of a soft gasket material.
SUMMARY OF THE INVENTION
A soft gasket material comprises two opposed surfaces (faces), and at least one edge which is substantially perpendicular to these surfaces; the edge (referred to herein as the perpendicular edge of the gasket) further has a coat thereon which extends directly from the edge at its center point and going to the coat's outer surface (referred to herein as “thickness length B”). The center point of the edge is the middle of the edge length. The edge length is the shortest distance on the edge going between the two faces in a straight line.
The coat is also required to have a width in the direction parallel to the edge such that the coat covers the edge from side to side and extends past at least one corner of the edge in an amount effective to form a barrier against the passage of fluids onto the face of the gasket. (The corner being where the edge meets one of the opposed surfaces, i.e. the end of the edge). The length or distance that the coating extends past the corner of the edge (or the end of the edge) in a direction perpendicular to the opposed surfaces is referred to herein as a “lip”, the “extended coating”, “extended coating”, the “protruding length”, the “protruding distance” and is also called “protruding length A”. The “coat thickness” or “thickness length B” refers to the length or distance in the coating which extends directly from the gasket edge at its middle point between the opposed surfaces and ending at the outer surface of the coat.
When the coating on the edge is formed so that the lip or the extended coating barrier sits partially on the gasket face the gasket provides support to the protruding lip (or extended coating). In such a case the ratio of A:B must be a minimum of about 0.6 and preferably it is a minimum of about 0.9. In such a case the thickness length B is a distance of at least about 2 mils. When, however, the protruding length A is not supported by the face, the thickness length B is a minimum length of about 3 mils and the ratio of A:B is a minimum of about 0.8 and preferably is a minimum of about 1.25. The thickness length B provides a base for the coating which forms protruding length A.
When the coated edge is around an aperture in the gasket sheet material, the coating forms a “primary seal” against the passage of fluids going from the aperture and across the face of the gasket. When the coated edge is around the outside or the perimeter of the gasket, the coating forms a secondary seal against fluids. The coated edge can be either around an aperture or it can be around the outside of the gasket.
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Dempsey Dennis M.
Morris Christopher L.
Beres John L.
Interface Solutions, Inc.
Knight Anthony
Womble Carlyle Sandridge & Rice PLLC
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