Patent Description:
Rubber-coated gaskets of the present state of the art typically include a core that is coated with nitrile rubber. A gasket, in many applications, must be capable of sealing two separable mating surfaces of flanges forming a mechanical seal between the surfaces, and be impervious and resistant to the sealed media. Gaskets also must be able to withstand the application of elevated temperature and pressure in many applications.

Rubber-coated gaskets are typically used for pumps and semi-hermetic compressors, oil pans, valve covers, and other applications where oil and grease are present, pressures that must be sealed are relatively low, and/or sealing surfaces are not uniform. Rubber-coated gaskets may also be used in high-pressure applications, such as head gaskets in automotive applications.

While rubber-coated and rubber-on metal gaskets are advantageous to use under certain conditions, alternatives to these materials have advantages in certain applications. Thermoplastic elastomer (TPE) is an alternative to rubber that provides advantages such as easy processing and application using thermoplastic technologies such as spraying, injection molding, 2D molding, extrusion, direct application, sintering, baking, overlaying, and laminating. Furthermore, TPEs have proven themselves extremely reliable when in contact with otherwise corrosive materials such as natural and synthetic oils, greases, and lubricants, making them excellent for use in gaskets. Additionally, cracking does not occur with TPE. When cracks form, due to extreme application conditions including fluctuations in temperature and pressure, leak paths can form between the sealed fluid central opening of the gasket and the outer environment, reducing the sealing effectiveness of the gasket. Cracking does not occur with TPE, which minimizes the risk of a compromised seal due to the formation of leak paths.

As an alternative to metal, other non-compressible materials can be used to form the gasket core. Composite material, for example, has a low coefficient of thermal expansion and contraction, which helps to preserve the quality of the gasket seal over time. Composite material is also resistant to oxidation and corrosion when exposed to hostile or corrosive conditions for long periods.

In use, a compressible coated gasket is clamped between two separable mating surfaces of flanges forming a mechanical seal between the surfaces. The flanges may be secured together with bolts tightened to a specified torque to form a joint. When the bolts of a joint are torqued or tightened, the force imparted to one flange by the other becomes significantly greater around the bolt holes than in the mid-spans of the flanges between the bolt holes. Further, the flanges deform or curve slightly in response to the tightening of the bolts. The distance between the flange mating surfaces in the mid-spans can, as a consequence, be greater than the distance between the mating surfaces in the vicinities of the bolt holes. As a result of the varying distances between different location on mating surfaces, gaskets of the prior art have failed to create a pressure-resistant seal to enclose the sealed media.

Prior art compressible gaskets can take several forms. <FIG> illustrate examples of three compressible gaskets of the prior art. <FIG> shows an edge-coated gasket <NUM> of the prior art in which a fiber gasket <NUM>, which is slightly compressible, is provided with a polymer edge coating <NUM>. The fiber gasket <NUM> conforms somewhat to varying distances between flange mating surfaces, and the polymer edge coating <NUM> forms an adhesive seal around a fluid opening. <FIG> shows another prior art gasket <NUM> wherein a sheet of gasket material <NUM> is embossed as shown to form a surface with depressions and projections defined by a ridge <NUM>. The ridge <NUM> functions to concentrate sealing force and to conform somewhat to varying distances between mating surfaces in different regions of a flange to increase the integrity of the seal. <FIG> shows another gasket <NUM> of the prior art used for sealing and compensating for varying distances between mating surfaces. Here, a gasket <NUM> has a core <NUM>, which may be a non-compressible core made of metal, for example, having a rubberized coating <NUM> on the top and bottom surfaces of the non-compressible core <NUM>. The coatings <NUM> include compressible surface projections <NUM>, the purpose of which is to concentrate sealing force and compensate for flange warp when the gasket <NUM> is tightened between the mating surfaces of flanges.

<FIG> illustrates a prior art embossed gasket <NUM> such as that shown in <FIG> including the sheet of gasket material <NUM> and the embossed ridge <NUM>. <FIG> is a photo of a Fujifilm pressure map showing the pressure distribution of an embossed gasket <NUM> such as that illustrated in <FIG>. The pressure map shows less than reliable seals formed in the regions of the gasket <NUM> outside the embossments. The dark red lines on the pressure map show that the ridge <NUM> formed from the embossment creates a thin contact area forming a concentrated pressurized reliable seal along the embossment perimeter. However, the ridge <NUM> formed by the embossment prevents contact and pressurized sealing between the flange surface and the non-embossed portions of the gasket material <NUM>. This sealing configuration is prone to failure if the concentrated sealing area is compromised, for example if the embossment is improperly or incompletely formed or the ridge <NUM> otherwise fails to establish a sealing configuration on the gasket sheet <NUM>. The United States patent application published as <CIT> discloses a gasket for creating a seal between two surfaces, according to the preamble of claim <NUM>. The gasket may include a pervious base sheet and a permeating material applied to or incorporated into the base sheet. The gasket may include a base sheet, a primary sealing material covering the base sheet, and a secondary sealing material covering the primary sealing material. The United States patent application published as <CIT> discloses an edge coated gasket with a base sheet made of compressible gasket material and having opposed faces and an interior edge surrounding and defining an aperture. An edge coating of polymer or other material is disposed on and seals the interior edge of the base sheet and may project beyond the facial planes of the base sheet to define protruding rims extending around the aperture. Face coatings may also be applied to one or more of the faces extending in relatively narrow strips around the aperture of the base sheet. The United States patent application published as <CIT> discloses a gasket assembly with a gasket layer and a separately formed shim layer. The shim layer and gasket layer are formed with at least one media-conveying opening that correspond to media-conveying passages communicating between first and second members to be clamped together and sealed by the gasket at the joint between members. The shim layer has an adhesive layer applied to its back surface to enable the shim layer to be adhered to original clamping face of the one of the first or second members in order to build up the surface or to cover up damage on the clamping face that could impair proper sealing with the gasket.

While the prior art illustrates solutions to certain sealing scenarios, the sealing gaskets of the prior art require dedicated presses and molds for their fabrication, are expensive to manufacture, difficult to prototype quickly, and are not ideally suited to provide an evenly distributed surface sealing effect. In view of the disadvantages associated with currently available sealing gaskets, there is a need for a new gasket configuration that is relatively inexpensive to manufacture, easy to prototype and modify quickly during research, self-conforming to varying distances between mating surfaces without embossments or ridges, and that is customizable to a degree not heretofore possible with prior art gaskets. It is to the provision of such a new gasket configuration that the present disclosure is primarily directed.

Accordingly, there is a need for a coated gasket that exhibits superior sealing characteristics when compared to natural rubber or nitrile rubber-coated gaskets that uses acoating material that is fabrication-friendly, easily stored and applied, and less expensive than natural and synthetic rubber products.

There is also a need for a gasket having an incompressible, rigid, non-porous substrate with a coating or coatings or surfaces or edges that are preferable to rubber-based coatings of the past. A need also exists for a gasket having an incompressible and non-porous core that is not metal but that performs like a metal without the undesirable properties of metal. There is also a need for a gasket with a non-metal substrate having surface and/or edge coatings of rubber or a polymeric material. There is a need for a compressible gasket configuration that is relatively inexpensive to manufacture, easy to prototype and change during research, self-conforming to varying distances between mating surfaces without embossments or ridges, and that is customizable to a degree not heretofore possible with prior art gaskets.

According to an aspect of the invention, the exemplary embodiments include a gasket for forming a seal between a first mating surface and a second mating surface, including a non-compressible substrate with a first surface, a second surface, and a central opening, a first compressible layer configured to cover the entire first surface and to contact the first mating surface in a surface-to- surface abutting relationship, and a second compressible layer configured to cover the entire second surface and to contact the second mating surface in a surface-to-surface abutting relationship, wherein at least one of the first compressible layer and second compressible layer is conformed to fill at least one defect in at least one of the first mating surface and the second mating surface upon compression of the gasket. The non-compressible substrate is a non-compressible gridded core having ribs forming spaces therebetween, the ribs being of a varied height.

In a further aspect, the exemplary embodiments include a method of sealing a first mating surface and a second mating surface, the method including providing a gasket having a non-compressible substrate, a first compressible layer conformed to sealingly engage with the first mating surface, and a second compressible layer conformed to sealingly engage with the second mating surface, wherein the non-compressible substrate is configured between the first compressible layer and the second compressible layer, positioning the gasket between the first mating surface and the second mating surface, compressing the gasket, conforming at least one of the first compressible layer and the second compressible layer to distribute compression forces evenly across the surface area of the gasket, and uniformly sealing the first compressible layer and the first mating surface and the second compressible layer and the second mating surface. The non-compressible substrate is a non-compressible gridded core having ribs forming spaces therebetween, the ribs being of a varied height.

A more particular description will be rendered by reference to exemplary embodiments that are illustrated in the accompanying drawings. Understanding that these drawings depict exemplary embodiments and do not limit the scope of this disclosure, the exemplary embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:.

Various features, aspects, and advantages of the exemplary embodiments will become more apparent from the following detailed description, along with the accompanying drawings in which like numerals represent like components throughout the drawings and detailed description. The various described features are not necessarily drawn to scale in the drawings but are drawn to emphasize specific features relevant to some embodiments.

Turning now to <FIG>, an embodiment of a gasket <NUM> is illustrated. The gasket <NUM> is formed with a non-compressible core or carrier <NUM> that may be made of a metal such as steel, stainless steel, aluminum, or other appropriate materials such as a thin carbon fiber composite with properties similar to steel. The non-compressible core <NUM> may be formed of any material that is relatively rigid and incompressible and can serve as a carrier or core for a gasket. The non-compressible core <NUM> is stamped or otherwise formed to define appropriate apertures (e.g. fluid passageway) <NUM> and bolt holes <NUM> that extend through the non-compressible core <NUM> and conform to features of the flanges to be sealed.

According to an embodiment, a first compressible layer <NUM> is applied to one side of the non-compressible core <NUM> and/or a second compressible layer <NUM> is applied to the other side of the non-compressible core <NUM>. The gasket <NUM> has a surface <NUM> defined by the exposed surface of the first compressible layer <NUM>, and a surface <NUM> defined by the exposed surface of the second compressible layer <NUM>. In use, the top surface <NUM> and bottom surface <NUM> contact exposed surfaces of two mating flanges to be sealed and the first compressible layer <NUM> and the second compressible layer <NUM> can compress significantly to fill defects in the mating surfaces, thereby forming a reliable seal.

The sealing material from which the first compressible layer <NUM> and second compressible layer <NUM> can be formed may be a polymeric material or any other material with appropriate rheology for a particular sealing application. In each case, the specific sealing material can be formulated or engineered to exhibit desired properties for a specific sealing task by varying additives such as oil and fillers and soft rubber materials that affect the performance of the sealing material. The sealing material may include, for example, thermoset elastomers or thermoplastic elastomers (TPE), including polysiloxane, acrylic, olefins, vulcanized propylene/ethylene-propylene-diene compounds, polyurethane, styrenic styrene-ethylene/butylene-styrene, copolyester compounds, or polyamide. TPE is a material that is impervious to cracking under the conditions to which gaskets are commonly exposed. When cracks form, a leak path is created, and the use of TPE prevents leak paths from the central fluid opening of the gasket <NUM>.

<FIG> illustrate gaskets <NUM> according to further embodiments. <FIG> is a perspective view of a rectangularly shaped gasket <NUM> according to an embodiment having a non-compressible core <NUM> formed of metal or metal alloy, such as steel, stainless steel, aluminum, copper, or other suitable material. While a rectangular shape has been used throughout to illustrate an exemplary gasket, it will be understood that gaskets made in accordance with the principles disclosed herein could take any shape. Bolt holes <NUM> are formed through the non-compressible core <NUM> near its comers to accommodate bolts that will clamp two mating surfaces together, compressing the gasket <NUM> between the surfaces to create a seal. A central opening <NUM> is formed through the non-compressible core <NUM> and is sized to encircle a fluid passageway extending through the mating surfaces. The central opening <NUM> is surrounded and defined by a surrounding edge <NUM> of the metal non-compressible core <NUM>.

A first compressible layer <NUM> is applied to a first surface <NUM> of the non-compressible core <NUM>. A second compressible layer <NUM> is applied to a second surface <NUM> of the non-compressible core <NUM>. In this embodiment, the first compressible layer <NUM> and second compressible layer <NUM> include a first bead 121a and a second bead 121b, respectively. The bead is applied to the first surface <NUM> and second surface <NUM> to provide a seal in a specific area of the gasket <NUM> when the gasket <NUM> is compressed between the flanges (as shown, for instance, in <FIG>). In the illustrated embodiment, the first bead 121a and second bead 121b are shown as a simple circle outboard of or encircling the central opening <NUM>. It will be understood by the skilled artisan, and is depicted in more detail in <FIG>, that the first bead 121a and second bead 121b on a gasket <NUM> can be configured in a variety of complex shapes and even varying thicknesses as needed to provide the area-specific sealing capabilities needed. The first bead 121a and second bead 121b may be formed of any sealing material that the first compressible layer <NUM> and second compressible layer <NUM> may be formed from, such as those described in detail hereinabove.

An edge coating <NUM> may be adhered to and extend around the surrounding edge <NUM> that defines the central opening <NUM> of the non-compressible core <NUM>. The edge coating <NUM> is applied to the surrounding edge <NUM> and extends, in this particular example, both above and below the plane of the non-compressible core <NUM>. The edge coating <NUM>, like the first bead 121a and second bead 121b, is made of a sealing material that can be applied to the surrounding edge <NUM> in a number of ways. Examples of application of the sealing material onto the surfaces <NUM>, <NUM> of the non-compressible core <NUM>, or the surrounding edge <NUM> of the non-compressible core, include overlaying, laminating, coating, spraying, melting, dipping, curing, heat-welding, chemical bonding, or molding. In use, the edge coating <NUM> is compressible between two mating surfaces around the edges of the surfaces that encircle a fluid passageway. In this way, the edge coating <NUM> forms a seal at the fluid/gasket interface to prevent fluid from leaking past the edge coating <NUM> and into the regions between the non-compressible core <NUM> and mating surfaces.

With regard to fluid sealing, the sealing material of any of the edge coating <NUM>, first bead 121a, second bead 121b, or first compressible layer <NUM> and second compressible layer <NUM> can be formulated to be specific to a fluid to which the gasket <NUM> will be exposed in use. For example, thermoplastic elastomers can be formulated that are resistant to oils, heat, gasses, grease, or caustic chemicals depending upon the intended use of the gasket. Furthermore, thermoplastic elastomer edge coatings can be engineered with varying thicknesses and dimensions as needed to provide a customized seal between two mating surfaces at the specific location where fluid encounters the gasket.

<FIG> is a cross-sectional view of the gasket <NUM> of <FIG> illustrating the first compressible layer <NUM> as a first bead 121a, and the second compressible layer <NUM> as a second bead 121b, applied respectively to the first surface <NUM> and second surface <NUM> of the non-compressible core <NUM>. Beads are often associated with embossed regions in the non-compressible core <NUM>, which can help conform the gasket to slightly curved or rough mating surfaces when the gasket <NUM> is compressed between the surfaces. In <FIG>, the first bead 121a and second bead 121b are respectively applied to the embossment <NUM> shown as a projection from both surfaces of the non-compressible core <NUM>. The first bead 121a and second bead 121b are applied to cover the embossment <NUM> on both sides of the non-compressible core <NUM>. <FIG> also illustrates the height to which the edge coating <NUM> projects from the planar first surface <NUM> and second surface <NUM> of the non-compressible core <NUM>.

<FIG> illustrate another embodiment of the gasket <NUM> wherein the non-compressible core <NUM> is provided as a thin composite substrate, such as carbon fiber or epoxy sheet. Such composites provide the shape and rigidity of metal gasket substrates, but also provide strength, lower thermal expansion and contraction coefficients, and better resistance to corrosion and oxidation. In <FIG>, the non-compressible core <NUM> formed of a thin composite material may have fibers or ribbons of carbon laid in the epoxy carrier in at least three different and crisscrossing directions. This arrangement provides strength and rigidity to the sheet that is similar to the strength of a metal substrate or core of the same thickness.

As with the embodiment of <FIG>, a first bead 121a and a second bead 121b are applied to the first surface <NUM> and second surface <NUM> of the non-compressible core <NUM> in <FIG>. The edge coating <NUM> is also depicted in <FIG> as extending above the first surface <NUM> and below the second surface <NUM> of the non-compressible core <NUM> to provide a targeted and precise seal at the location where the gasket is exposed to a fluid being contained thereby.

The gasket <NUM> of <FIG> are basic rectangular gaskets in accordance with an embodiment. However, the gasket <NUM>, as well as its individual components, can take any shape needed to form a seal between two mating surfaces. For example, <FIG> show embodiments of the gasket <NUM> in different configurations with central opening <NUM>, first bead 121a, second bead 121b, and non-compressible core <NUM> having different shapes. Additionally, for example, the first compressible layer <NUM> and the second compressible layer <NUM> may be spaced apart from the edge coating <NUM>. Alternatively, the compressible layers <NUM>, <NUM> may be adjacent to the edge coating <NUM>. In some embodiments, the first compressible layer <NUM> and second compressible layer <NUM> form circles that are concentric to the edge coating <NUM> of the central opening <NUM> which is also circular. The first compressible layer <NUM>, second compressible layer <NUM>, and central opening <NUM> may be of any shape that is conducive for the particular sealing needs of the gasket <NUM>. The gasket <NUM> may also take any shape needed for effective sealing of the mating surfaces between which it is placed.

<FIG> illustrates a self-conforming gasket <NUM> according to an embodiment that has a central layer, or non-compressible core <NUM>, and a first compressible layer <NUM> and/or a second compressible layer <NUM> positioned on opposing surfaces of the non-compressible core <NUM>. According to an embodiment, the non-compressible core <NUM> may be coated on one side or on both sides with a first compressible layer <NUM> and a second compressible layer <NUM>, formed of the sealing material described in detail hereinabove.

According to an embodiment, the non-compressible core <NUM> is composed of a metal, a thermoset plastic material, and/or a thermoset composite material. As such, the non-compressible core <NUM> may be formed of a mechanical member such as a perforated metal sheet. Such a sheet also may be formed of expanded metal that has subsequently been flattened with appropriate rollers, or by the punching and drawing of expanded sheet metal. The flattening of the non-compressible core <NUM> eliminates portions of the material that may project up or down from the plane of the mechanical member. Such protrusions tend to penetrate the upper and lower sealing material coatings when the gasket is placed under compression between mating surfaces, which can destroy the gasket seal. The non-compressible core <NUM> formed from the flattened mechanical member may then be coated with a first compressible layer <NUM> and a second compressible layer <NUM> according to an embodiment.

In further embodiments, the non-compressible core <NUM> is formed from a thermoset composite material that has been molded or otherwise shaped to be flat on its upper and lower surfaces with ribs that define the openings of the core. Alternatively, the middle layer may be 3D printed from a CAD design. In such an embodiment, the composite gridded core may be coated on one or two sides with the first compressible layer <NUM> and/or the second compressible layer <NUM>, formed of a sealing material in the form of the thermoset elastomer or the thermoplastic elastomer (TPE), such as a UV silicone or acrylic TPE.

With reference to, for instance <FIG> and in its simplest form, the gridded non-compressible core <NUM> (the middle layer of <FIG>) is formed from a plurality of crisscrossing, or interconnected, elements/ribs <NUM> that forms an array of openings <NUM>. Depending on the conformation of the interconnected elements, the openings can be square (shown in the various figures), rectangular, diamond-shaped (see, for instance, <FIG> and <FIG>), or hexagonal openings. However, as discussed below, the openings of the grid need not be shaped as one of those listed above, but can take on any shape and can be varied across the gasket to provide maximized sealing performance at all locations on the mating surfaces to be sealed. The configuration of the gridded core and its forming elements can thus be specifically engineered for a particular sealing application.

Turning now to <FIG>, the gasket <NUM> may be made of a flat metal, thermoset plastic, or thermoset composite non-compressible core <NUM> sandwiched between a first compressible layer <NUM> of sealing material and a second compressible layer <NUM> of sealing material. The first compressible layer <NUM> and second compressible layer <NUM> may be applied to the gridded non-compressible core <NUM> or attached by other means depending on the compositions and dimensions of the first compressible layer <NUM>, the second compressible layer <NUM>, and the non-compressible core <NUM>. For example, the layers may be attached by overlaying, laminating, coating, spraying, melting, dipping, curing, heat-welding, chemical bonding, or molding. The first compressible layer <NUM> includes a surface <NUM> facing away from the non-compressible core <NUM> configured to engage and form a seal with a mating surface (e.g., a flange of a pipe to be joined to another pipe flange). The second compressible layer <NUM> includes a surface <NUM> facing away from the non-compressible core <NUM> configured to engage and form a seal with a respective mating surface. The gasket <NUM> has a first bolt hole <NUM>, a second bolt hole <NUM>, and a central fluid opening <NUM>. (The gasket shown in <FIG> shows two additional bolt holes opposite the first and second bolt holes, but these have not been labeled. ) The bolt holes and central fluid opening <NUM> are each defined by apertures extending through each of the first compressible layer <NUM>, non-compressible core <NUM>, and second compressible layer <NUM>. In certain embodiments, the first bolt hole <NUM>, second bolt hole <NUM>, and central fluid opening <NUM> may extend through only at least one of a first compressible layer <NUM> and a second compressible layer <NUM> depending on the formation of the gasket <NUM> at the hole location. The non-compressible core <NUM> may be configured such that there are a plurality of ribs <NUM> extending in any direction away from the central fluid opening <NUM>. The ribs <NUM> may be configured so that the spaces <NUM> are diamond-shaped, as a result of the method of manufacture used to form the non-compressible core <NUM>. As shown in <FIG>, the ribs extend tangentially from the central fluid opening <NUM> and form a diamond-shaped pattern. While this is a simplified gasket for illustrative purposes, gaskets of highly complex shapes with alternative bolt hole configurations are common and are within the scope contemplated herein.

<FIG> is an orthogonal view of a gasket <NUM> according to an embodiment, wherein the non-compressible core <NUM> is a flat gridded core that may be made of punched or extruded and flattened metal. The gridded non-compressible core <NUM> includes a plurality of the interconnected ribs <NUM> that define the array of openings, apertures, or spaces <NUM>, which in this embodiment are square. The spaces <NUM> according to an embodiment of the gasket <NUM> are of a substantially uniform shape. In addition, the pattern of the ribs <NUM> and spaces <NUM> is predetermined to ensure that there is at least one rib <NUM>, and in some embodiments several ribs <NUM>, between a fluid opening in the gasket and the outside edges of the gasket. Each rib concentrates the pressure between the compressible sealing material and the adjacent mating surface to enhance the seal. Thus, with a properly designed grid pattern, there is no leakage path between the fluid opening of the flanges and the outside of the flange and a very reliable seal is formed.

As shown, the first compressible layer <NUM> is applied to the first surface <NUM> of the non-compressible core <NUM>. The second compressible layer <NUM> is applied to the second surface <NUM> of the non-compressible core <NUM>. The flat gridded non-compressible core <NUM> in this example is formed of interconnected linear ribs <NUM> that form a grid pattern <NUM> and define an array of square spaces <NUM>. The interconnected ribs <NUM> of the grid <NUM> create an array of relatively incompressible regions that support the first compressible layer <NUM> or second compressible layer <NUM> composed of sealing material coated onto the surfaces of the non-compressible core <NUM>. As explained in more detail below, the sealing material of the first compressible layer <NUM> or second compressible layer <NUM> is able to flow or be extruded into the spaces <NUM> as the gasket <NUM> is compressed between two mating surfaces. Advantageously, the compressible layers can flow to a greater degree at high pressure locations <NUM> such as around bolt holes, as will be discussed in greater detail hereinbelow.

<FIG> illustrate a top view of a gridded non-compressible core <NUM> as generally described above. In the embodiment as illustrated, the spaces <NUM> will allow the sealing material of at least one of the first compressible layer <NUM> and the second compressible layer <NUM> to flow into the spaces <NUM>. This will occur to a greater degree at area <NUM> nearer to the first bolt hole <NUM>, and to a lesser degree at the midpoint area <NUM>. According to <FIG>, it is possible to provide ribs <NUM> of the core <NUM> with varying degrees of thickness. As shown herein, the ribs <NUM> closest to the area <NUM> are thinner than are ribs <NUM> away from the area <NUM>.

Turning to <FIG>, in this embodiment, the height H of the ribs <NUM> that define the grid <NUM> varies across the surface of the non-compressible core <NUM>. For example, the height H of the ribs <NUM> may vary from <NUM> inches to <NUM> inches. <FIG> further depicts an embodiment of the gasket <NUM> including a flat, gridded non-compressible core <NUM> that may be made of punched or extruded and flattened metal, thermoset plastic, thermoset composite material, or another appropriate material such as Teflon, PVC, or renewable PLA. The gridded non-compressible core <NUM> includes the plurality of ribs <NUM> that define the array of spaces <NUM>, which in this embodiment are square.

To provide additional detail, <FIG> is a cross-sectional expanded view of the ribs <NUM> marked by the arrow B-B in <FIG> illustrates the varying heights H<NUM>, H<NUM> (and varying heights therebetween) of the ribs <NUM> across the surface of the non-compressible core <NUM>. The ribs <NUM> may project to a greater height H<NUM> from the surface of the non-compressible core <NUM> in regions of the gasket <NUM> that will encounter lower compression forces and may project to a lower height H<NUM> in regions that will encounter higher compression forces. Lower compression forces will result on the gasket <NUM> at the midpoint <NUM> between a first bolt hole <NUM> and a second bolt hole <NUM>, as well as points near the midpoint of the opening <NUM>. Higher compression forces will result on the gasket <NUM> at locations adjacent to the first bolt hole <NUM> and the second bolt hole <NUM> (and the other bolt holes). Between locations of high compression force and low compression force, the height H of ribs <NUM> may increase as relative compression force decreases and the distance between mating surfaces subject to compressive force increases. Employment of a gridded non-compressible core <NUM> with ribs <NUM> of varied heights H depending on distance between flange mating surfaces and relative compressive forces facilitates the sealing capabilities of first compressible layer <NUM> and second compressible layer <NUM> having a uniform thickness across the surface of the gasket <NUM>. Alternatively, the thickness of the first compressible layer <NUM> or second compressible layer <NUM> may be modified at different locations on the gasket <NUM> surface (not shown).

The degree to which the first compressible layer <NUM> and second compressible layer <NUM> of sealing material can flow into the spaces <NUM> of the non-compressible core <NUM> can be varied across the area of the gasket <NUM>. The gasket <NUM> can thus be customized to provide a full surface-engaging seal at every location across mating surfaces between which it is clamped. Advantageously, as shown in <FIG>, the compressible layers can flow to a greater degree at high pressure locations <NUM> such as around bolt holes. Conversely, it can flow to a lesser degree into the spaces <NUM> at lower pressure locations such as the mid-span area between the bolt holes. (See, for instance, <FIG>. ) Thus, the sealing material automatically conforms itself to varying distances between mating surfaces as bolts are torqued thereby improving the seal created by the gasket <NUM>.

As shown in <FIG>, the non-compressible core <NUM> can be completely eliminated or not molded in at high compression load regions, designated as <NUM>, such as around the bolt hole <NUM>. In such an embodiment (not shown), there may be only a first compressible layer <NUM> present, or a first compressible layer <NUM> and a second compressible layer <NUM> in contact with one another through at least one of the spaces <NUM> of the non-compressible core <NUM> upon compression and sealingly engaged by compressive forces exerted by the flange bolt onto the gasket <NUM>. (See, for instance, <FIG>.

If the gridded non-compressible core <NUM> is molded from thermoset plastic or another relatively incompressible polymer, then it can be formed in a clamshell mold in traditional ways. However, thermoset plastic can be printed and so the non-compressible core <NUM> can be created with a 3D printer from a mere CAD drawing. This possibility leads to very rapid prototyping, testing, and reconfiguration when designing a gasket <NUM> for a particular purpose.

<FIG> is a cross-sectional view showing the gasket <NUM> clamped between and self-conforming to varying distances between a first mating surface <NUM> of a first flange <NUM> and a second mating surface <NUM> of a second flange <NUM>. It will be understood that certain dimensions and curvatures are exaggerated in <FIG> for clarity of explanation. The gasket <NUM> is shown disposed between mating surfaces <NUM> and <NUM> of flanges <NUM> and <NUM>. Bolts <NUM> and <NUM> extend through bolt holes <NUM> and <NUM> in the flanges <NUM>, <NUM> and in the gasket <NUM> and are torqued to pull the mating surfaces <NUM>, <NUM> together and compress the gasket <NUM> between them. Since the clamping force is greater in the area <NUM> adjacent to the bolts <NUM>, <NUM> and bolt holes <NUM>, <NUM>, and less in the midpoint <NUM> between these holes, the flange <NUM> will tend to deform or bow away from the adjacent flange <NUM> across the mating surfaces <NUM>, <NUM> between bolt holes <NUM>, <NUM>. The mating surfaces <NUM>, <NUM> are thus slightly farther apart in the midpoint <NUM> than in the vicinities <NUM> of the bolts <NUM>, <NUM>. This is illustrated in <FIG> by the relative distances between mating surface <NUM> an, marked by D<NUM> (the distance between mating surfaces <NUM> and <NUM> at the midpoint <NUM>) and D<NUM> (the distance between mating surfaces <NUM> and <NUM> in the vicinity <NUM> of the bolts/bolt holes). Thus, the distance D<NUM> is greater than the distance D<NUM> when the bolts <NUM> and <NUM> are tightened.

As shown in <FIG>, the flat gridded non-compressible core <NUM> is provided with the first compressible layer <NUM> on the upper surface <NUM> and the second compressible layer <NUM> on the lower surface <NUM> of the core <NUM>. The first compressible layer <NUM> includes the planar outer surface <NUM> shaped and sized to sealingly engage in a surface-to-surface abutting relationship with the first mating surface <NUM> of the flange <NUM>, and the second compressible layer <NUM> includes the planar outer surface <NUM> shaped and sized to sealingly engage in a surface-to-surface abutting relationship with the second mating surface <NUM>. The first compressible layer <NUM> and second compressible layer <NUM> are formed of sealing materials which can be any material that can form a seal when clamped between mating surfaces but that has sufficient flow characteristics appropriate for the gasket environment and application to allow the material to flow or extrude at least partially into the spaces <NUM> when subjected to a compression load. Across the surface of the gasket <NUM>, the first compressible layer <NUM> sealingly engages the first mating surface <NUM> and the second compressible layer <NUM> sealingly engages the second mating surface <NUM>. It should be appreciated that the same engagement may occur in an embodiment having a single compressible layer coated onto one side of a non-compressible gridded non-compressible core <NUM> and a single mating surface. Under certain circumstances, one or both of the mating surfaces <NUM>, <NUM> may have a deformation <NUM> resulting in a non-planar mating surface. As shown in <FIG>, the first compressible layer <NUM> is able to flow into and fill the deformation <NUM> so that the seal between the mating surface <NUM> and the first compressible layer <NUM> is not compromised.

Referring again to <FIG>, in the midpoint <NUM>, the first compressible layer <NUM> and second compressible layer <NUM> engage the respective mating surfaces <NUM>, <NUM> to form a seal. Either the first compressible layer <NUM> or the second compressible layer <NUM> or both the first compressible layer <NUM> and second compressible layer <NUM> may flow or extrude slightly into the spaces <NUM> of the gridded non-compressible core <NUM> as a result of the lower compression forces applied by the slightly outward-bowed mating surfaces <NUM>, <NUM> in midpoint region <NUM>. In the vicinities <NUM> of the bolt holes, however, the compression forces applied by the mating surfaces <NUM>, <NUM> are significantly higher and the resulting distance between the mating surfaces <NUM>, <NUM> is much less as compared to at midpoint region <NUM>. Under these conditions, the first compressible layer <NUM> and the second compressible layer <NUM> are squeezed or extruded by compressible force and as a result flow into the spaces <NUM> to accommodate for the narrower space around the bolt holes. The flowability of the first compressible layer <NUM> and second compressible layer <NUM> is illustrated by arrows <NUM> in <FIG>, showing the sealing material of the first compressible layer <NUM> and second compressible layer <NUM> flowing or extruding around the rib <NUM> and contacting each other between the rib <NUM> by partially or completely filling at least a portion of the spaces <NUM> surrounding the rib <NUM>. In alternative embodiments of the gasket <NUM>, the gridded non-compressible core <NUM> may be absent from locations adjacent to the first bolt hole <NUM> and the second bolt hole <NUM> on the gasket <NUM> to. accommodate the shorter distance and greater compressive force exerted on the first compressible layer <NUM> and second compressible layer <NUM>. In some embodiments, there may be present only the first compressible layer <NUM>, which may partially or completely fill at least a portion of the spaces <NUM>. In another embodiment, there may be a single compressible layer adjacent to the first bolt hole <NUM> and the second bolt hole <NUM>.

The elasticity and degree of stickiness of the sealing material used to form the first compressible layer <NUM> and second compressible layer <NUM>, and perhaps the configuration of the grid <NUM> are designed so that, for a particular flange or sealing requirement, the sealing material of the compressible layers <NUM>, <NUM> maintains superior and surface-wide sealing contact with the mating surfaces <NUM>, <NUM>, throughout the joint. It thus will be recognized that the gasket <NUM> in an embodiment compensates for the deformation or bowing of the first mating surface <NUM> or second mating surface <NUM> due to compression force, and thus may be said to be "self-conforming.

<FIG> show the results of a Fujifilm pressure test illustrating the effectiveness of the inventive concept described herein. A Fujifilm test of a gasket involves placing a sheet of pressure-sensitive film between a gasket and a flange mating surface and torqueing connecting bolts to a recommended specification. The pressure-sensitive film is embedded with microspheres filled with red dye. As the compression forces on the gasket, and the film, are increased, the microspheres are ruptured as a function of the pressure at various locations between the flanges. The result is a red imprint that records the pressure applied by the flange to the gasket across the entire surface area of the flange. It is a common and standard test well-known in the gasket industry to those of ordinary skill, and results in a pressure map.

<FIG> shows a Fujifilm pressure test for a standard fiber core gasket of the prior art placed between two flanges with the bolts torqued to specification. The Fujifilm pressure map reveals that while significant pressure was generated in the regions adjacent to the bolt holes, significantly less pressure was generated in the mid-spans of the test flange between the bolt holes. In fact, this pressure map would indicate the potential for leaks in the mid-span portions of this particular joint of the prior art due to the unequal distribution of pressure throughout the gasket at its contact points with the mating surfaces.

<FIG> shows the results of a Fujifilm test using the same joint and the same bolt tightness with the flat gridded core gasket according to an embodiment. The sealing improvement, due to the equal distribution of compression forces across the entire surface of the gasket, can be seen clearly. The Fujifilm imprint reveals that very consistent pressures were applied by the gasket to the mating surfaces across the flange joint. In fact, the results of this test indicate that a complete seal was formed with no path available for leakage either in the vicinities of the bolt holes or in the mid-span regions of the joint.

The same tests were carried out with the bolts torqued to a value less than specification. In other words, the bolts were torqued at different levels for the gaskets shown in <FIG>, than the torques applied for the gaskets shown in <FIG>. The results of this test are shown in <FIG>. As can be seen, the Fujifilm pressure test resulting from the standard fiber core gasket of the prior art in <FIG> indicates that a seal was not formed under these conditions. Specifically, in the mid-spans, there was barely enough pressure generated to be registered by the Fujifilm. This joint likely would have leaked.

Claim 1:
A gasket (<NUM>) for forming a seal between a first mating surface (<NUM>) and a second mating surface (<NUM>), comprising:
a non-compressible substrate (<NUM>) with a first surface (<NUM>), a second surface (<NUM>), and a central opening (<NUM>);
a first compressible layer (<NUM>) configured to cover the entire first surface (<NUM>) and to contact the first mating (<NUM>) surface in a surface-to-surface abutting relationship; and
a second compressible layer (<NUM>) configured to cover the entire second surface (<NUM>) and to contact the second mating surface (<NUM>) in a surface-to-surface abutting relationship,
wherein at least one of the first compressible layer (<NUM>) and second compressible layer (<NUM>) is conformed to fill at least one defect in at least one of the first mating surface (<NUM>) and the second mating (<NUM>) surface upon compression of the gasket (<NUM>), and characterised in that
the non-compressible substrate (<NUM>) is a non-compressible gridded core having ribs (<NUM>) forming spaces (<NUM>) therebetween, and in that the ribs (<NUM>) are of a varied height.