Exhaust Manifold Gasket

Abstract

An exhaust manifold gasket assembly having at least two layers and a series of tabs and recesses. The gasket has a first outer layer with an outer surface, an inner surface, two bolt hole flanges, a central aperture, and internal square cut-outs. The surfaces are bounded by an outer perimeter portion, with foldable tabs. A first inner layer and a second inner layer each with an outer surface, an inner surface, two bolt hole flanges, a central aperture, and pairs of internal slits. The surfaces are surfaces bounded by an outer perimeter portion, with locator tabs. Each inner layer has a bead circumferentially around the central aperture. A second outer layer may be provided having an outer surface, an inner surface, two bolt hole flanges, a central aperture, and internal square cut-outs. The surfaces are bounded by an outer perimeter portion, with recesses.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional application filed off of U.S. patent application Ser. No. 61/458,852 filed on Dec. 2, 2010, which is incorporated by reference in its entirety herein. This non-provisional application is being filed during the pendency of U.S. patent application Ser. No. 61/458,852.

FIELD OF THE INVENTION

The present invention relates to an exhaust manifold gasket for use in internal combustion engines.

BACKGROUND OF THE INVENTION

Gaskets essentially are used to seal and prevent leakage between two parts. Exhaust manifold gaskets for internal combustion engines seal any gaps and prevent leakage when the mating surfaces of the cylinder head and the exhaust manifold are bolted together. The gaskets may be made of layers and one or more of the layers may include a bead. Sealing the joined area between the parts can be difficult because the cylinder head, manifold and gasket all move due to pressure and temperature fluctuations. There are also problems due to thermal expansion and thermal contraction, which occurs when the temperature varies in the cylinder head and the manifold.

Thermal motion, resulting from hot exhaust gases, increasing combustion pressure, steep thermal swings, and sheer stresses are created in the joined area between the cylinder head and the exhaust manifold increasing the risk of horizontal motion and shifting of the gasket layers, such as in a multi-layer steel (MLS) gasket. When this occurs, the layers shift and the mechanical beads in the gasket layers can become misaligned. This reduces the sharing capabilities of the beads located on the various layers, and the misaligned beads may induce unusual stress concentrations.

There are also multiple openings in the cylinder head and the manifold for exhaust gases and bolts holes. The areas around these openings are known to be put under additional stresses and leakage is common due to movement and misalignment of the gasket layers.

Traditionally, the various gasket layers are aligned and held in place during gasket assembly by welding, eyeleting or form-locking. The eyeleting and form-locking methods both add thickness to the gasket and therefore must be located outside of the joined area, which is not ideal. While welding does not necessarily add thickness to the gasket, the weld spots may crack and/or break due to horizontal hardware motion which allows the gasket layers to shift.

In view of the foregoing disadvantages of the prior art, it would be advantageous for a MLS gasket to be able to prevent or resist horizontal motion and misalignment of the layers to the extent that it negatively affects performance of the gasket.

SUMMARY OF THE INVENTION

The present invention is directed toward an exhaust manifold gasket assembly having at least two or more layers, and utilizing a series of tabs, recesses, square cut-outs and pairs of slits to maintain alignment of the layers. The exhaust manifold gasket assembly has a first outer layer comprising an outer surface, an inner surface, two bolt hole flanges with bolt holes therethrough, a central aperture between the flanges, and at least two internal square cut-outs. The surfaces are bounded by an outer perimeter portion, wherein at least two foldable tabs extend from the outer perimeter portion. A first inner layer and a second inner layer each comprise an outer surface, an inner surface, two bolt hole flanges with bolt holes therethrough, a central aperture between the flanges, and at least two pair of internal slits. The surfaces are bounded by an outer perimeter portion, wherein at least one locator tab is located. Each of the inner layers also has a bead circumferentially extending about the central aperture inboard the outer perimeter portion of each of the inner layers. A second outer layer may be provided and comprises an outer surface, an inner surface, two bolt hole flanges with bolt holes therethrough, a central aperture between the flanges, and at least two internal square cut-outs. The surfaces are bounded by an outer perimeter portion, wherein at least two recesses are located.

In accordance with the present invention, it has been discovered that once the layers are assembled together, horizontal movement between the layers is significantly decreased, and the beads located on the inner layers remain aligned reducing unusual stress concentrations.

BRIEF DESCRIPTION OF THE DRAWINGS

The above, as well as other advantages of the present invention, will become readily apparent to those skilled in the art from the following detailed description when considered in the light of the accompanying drawings in which:

FIG. 1 is a partial perspective exploded view of the present invention with an exhaust manifold gasket, an exhaust manifold and cylinder head;

FIG. 2 is a top view of the assembled exhaust manifold gasket in FIG. 1;

FIG. 3 is a cross-sectional view of a portion of the embodiment of FIG. 2 along line 3-3;

FIG. 4 is a cross-sectional view of a portion of the embodiment of FIG. 2 along line 4-4;

FIG. 5 is a cross-sectional view of a portion of the embodiment of FIG. 2 along line 5-5;

FIG. 6 is a perspective assembled view of the embodiment of FIG. 2;

FIG. 7 is a perspective exploded view of the layers of the embodiment of FIG. 2;

FIG. 8 is a top view of a layer of the embodiment of FIG. 2;

FIG. 9 is a top view of a layer of the embodiment of FIG. 2;

FIG. 10 is a top view of a layer of the embodiment of FIG. 2;

FIG. 11 is a top view of a layer of the embodiment of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It is to be understood that the invention may assume various alternative orientations and step sequences, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions, directions or other physical characteristics relating to the embodiments disclosed are not to be considered as limiting, unless the claims expressly state otherwise.

As shown in FIG. 1, an exhaust manifold gasket assembly 10 is positioned between a cylinder head 12 and an exhaust manifold 14, so as to create an air tight seal between the two parts when they are bolted together. Both the cylinder head 12 and the exhaust manifold 14 are parts of an internal combustion engine (not shown.) The cylinder head 12 sits on top of a cylinder block (not shown.) It closes in the top of the cylinder, to form a combustion chamber. The exhaust manifold 14 collects exhaust gases from the cylinder combustion chamber, and delivers the gases to an exhaust pipe. Both the cylinder head 12 and the exhaust manifold 14 have bolt apertures 12a, 12b, 14a, 14b which align with each other, and each has a flat surface 16, 18 for receiving an exhaust manifold gasket assembly between them, as shown in the figure.

Exhaust manifold gasket assemblies are manufactured in accordance with the various shapes of cylinder heads and exhaust manifolds, and include numerous openings, such as exhaust gasket openings and bolt holes. FIG. 1 depicts one embodiment of an exhaust manifold gasket assembly 10; however, other shapes, sizes and designs are permissible. Various sealing means are provided in the gasket assembly for sealing around the respective openings.

The embodiment of the exhaust manifold gasket assembly 10, as depicted in FIGS. 2-11, comprises a first outer layer 20, a second outer layer 118, a first inner layer 54 and a second inner layer 86. It is also within the scope of the invention for there to be more or fewer layers. The two outer layers 20, 118 and the two inner layers 54, 86 may each be made of a metallic material, such as steel.

As shown in FIGS. 6, 7 and 8, the first outer layer 20 comprises an outer surface 22, an inner surface 24, two bolt hole flanges 26, 28 with bolt holes 30, 32 therethrough, a central aperture 34 between the flanges 26, 28, and at least two internal square cut-outs. While as depicted in the figures four internal square cut-outs 36, 38, 40, 42 are shown, it is also within the scope of the invention for there to be more or fewer internal square cut-outs.

The surfaces 22, 24 of the first outer layer 20 are bounded by an outer perimeter portion 44, wherein foldable tabs 46, 48, 50, 52 are formed from the outer perimeter portion 44. The foldable tabs 46, 48, 50, 52 extend unitarily outward from the outer perimeter portion 44. While as depicted in FIGS. 7 and 8 four foldable tabs 46, 48, 50, 52 are shown, it is also within the scope of the invention for there to be more or fewer tabs. The foldable tabs 46, 48, 50, 52 and internal square cut-outs 36, 38, 40, 42 are generally located toward the narrow ends of the oval outer perimeter portion 44 between the bolt hole flanges 26, 28 and the central aperture 34.

The internal square cut-outs 36, 38, 40, 42 are oriented parallel with and adjacent the outer perimeter portion 44. The internal square cut-outs 36, 38, 40, 42 insure that there are only four layers overlapping at any one point. This feature ensures that when the gasket is installed, the total gasket thickness is never greater than the original number of layers in the gasket assembly, as depicted in FIG. 4. The foldable tabs 46, 48, 50, 52 are located outboard of the internal square cut-outs 36, 38, 40, 42 and are slightly narrower in width than the internal square cut-outs 36, 38, 40, 42. The foldable tabs 46, 48, 50, 52 also have a length longer than the thickness of the first outer layer 20.

As depicted in FIGS. 7, 9 and 10, the first inner layer 54 and the second inner layer 86 each comprise an outer surface 56, 88, an inner surface 58, 90, two bolt hole flanges 60, 62, 92, 94 with bolt holes 64, 66, 96, 98 therethrough, a central aperture 68, 100 between the flanges 60, 62, 92, 94, and at least two pair of internal slits 70, 72, 74, 76, 102, 104, 106, 108.

The surfaces 56, 58, 88, 90 of each of the inner layers 54, 86 are bounded by an outer perimeter portion 78, 110. The outer perimeter portion 78, 110 is generally oval in shape and includes locator tabs 80, 82, 112, 114. As shown in FIGS. 9 and 10, the locator tabs 80, 82, 112, 114 extend unitarily outward from the outer perimeter portion 78, 110. Locator tabs 80, 82, 112, 114 are generally utilized during assembly of the gasket between two parts to ensure that it is in the correct position to obtain optimum sealing capabilities. While as depicted in the figures two locator tabs 80, 82, 112, 114 are shown on each of the inner layers 54, 86, it is also within the scope of the invention for there to be more or fewer locator tabs. As depicted in the figures, the locator tabs 80, 82, 112, 114 on each of the inner layers 54, 86 are located on opposite sides, diagonally across from each other. The locator tabs 80, 82, 112, 114 are generally located toward the narrow ends of the oval outer perimeter portion 78, 110 between the bolt hole flanges 60, 62, 92, 94 and central aperture 68, 100.

As shown in FIGS. 4 and 7, the pairs of internal slits 70, 72, 74, 76, 102, 104, 106, 108 on each of the first and second inner layers 54, 86 are aligned with one another. The pairs of internal slits 70, 72, 74, 76, 102, 104, 106, 108 are located parallel to and internally inboard of the outer perimeter portion 78, 110, and generally located toward the narrow ends of the oval outer perimeter portion 78, 110 between the bolt hole flanges 60, 62, 92, 94 and central aperture 68, 100. The individual slits in each pair 70, 72, 74, 76, 102, 104, 106, 108 are the same and parallel one another. One slit in each pair 70, 72, 74, 76, 102, 104, 106, 108 is adjacent the outer perimeter portion 78, 110. The two inner layers 54, 86 are a mirror image of one another, shown in FIGS. 9 and 10.

The first inner layer 54 and the second inner layer 86 each also comprise a bead 84, 116 which circumferentially extends about the central aperture 68, 100 and is inboard of the outer perimeter portion 78, 110, as depicted in FIGS. 2 and 3.

As depicted in FIGS. 7 and 11, the second outer layer 118 comprises an outer surface 120, an inner surface 122, two bolt hole flanges 124, 126 with bolt holes 128, 130 therethrough, a central aperture 132 between the flanges 124, 126, and at least two internal square cut-outs. While as depicted in the figures four internal square cut-outs 134, 136, 138, 140 are shown, it is also within the scope of the invention for there to be more or fewer internal square cut-outs.

The surfaces 120, 122 of the second outer layer 118 are bounded by an outer perimeter portion 142. The outer perimeter portion 142 is generally oval in shape and includes recesses 144, 146, 148, 150. As depicted in the figures, the recesses 144, 146, 148, 150 extend inward from the outer perimeter portion 142. While as depicted in the figures four recesses 144, 146, 148, 150 are shown, it is also within the scope of the invention for there to be more or fewer recesses.

The recesses 144, 146, 148, 150 and internal square cut-outs 134, 136, 138, 140, as depicted in FIGS. 7 and 11, are generally located toward the narrow ends of the oval outer perimeter portion 142 between the bolt hold flanges 124, 126 and the central aperture 132. The internal square cut-outs 134, 136, 138, 140 are oriented parallel with and adjacent the outer perimeter portion 142. The internal square cut-outs 134, 136, 138, 140 insure that there are only four layers overlapping at any one point. This feature ensures that when the gasket is installed, the total gasket thickness is never greater than the original number of layers in the gasket assembly, as depicted in FIG. 4. The recesses 144, 146, 148, 150 are parallel with and located outboard of the internal square cut-outs 134, 136, 138, 140 and are substantially the same width as the internal square cut-outs 134, 136, 138, 140.

As shown in FIGS. 3 and 5, the inner surfaces 24, 122 and the outer surfaces 22, 120 of each of the outer layers 20, 118 are planar and parallel to one another, and define between them a substantially constant thickness.

As shown in FIGS. 6 and 7, the central aperture 34, 68, 100, 132 in all the layers 20, 54, 86, 118 are aligned with one another and have a complimentary shape when the layers 20, 54, 86, 118 are placed together for assembly. When all the layers 20, 54, 86, 118 are aligned, the beads 84, 116 of each of the inner layers 54, 86 are also radially aligned with one another. Once the layers 20, 54, 86, 118 are placed together they may be welded to hold them together, although with this embodiment welding is not necessary.

It can be appreciated from FIGS. 2, 6 and 7 that the foldable tabs 46, 48, 50, 52, internal square cut-outs 36, 38, 40, 42, 134, 136, 138, 140 and recesses 144, 146, 148, 150 of the outer layers 20, 118 are in alignment with one another, and the pairs of internal slits 70, 72, 74, 76, 102, 104, 106, 108 of the inner layers 54, 86 are in alignment with one another. For example, the foldable tabs 46, 48, 50, 52 on the first outer layer 20 align with and engage the recesses 144, 146, 148, 150 on the second outer layer 118.

As can also be appreciated from FIGS. 5, 6 and 7 when the layers 20, 54, 86, 118 are assembled, the inner surface 58 of the first inner layer 54 is directly adjacent the inner surface 24 of the first outer layer 20, and the outer surface 88 of the second inner layer 86 is directly adjacent the inner surface 122 of the second outer layer 118. The outer surface 56 of the first inner layer 54 is directly adjacent the inner surface 90 of the second inner layer 86 when assembled.

Ultimately when the layers 20, 54, 86, 118 are assembled, as depicted in FIGS. 4 and 6, the foldable tabs 46, 48, 50, 52 on the first outer layer 20 are folded into a C-shape which encloses around the outer perimeter portion 78, 110, 142 of each of the first inner layer 54, second inner layer 86 and the second outer layer 118. The internal square cut-outs 36, 38, 40, 42, 134, 136, 138, 140 on each of the outer layers 20, 118 insure that there are only four layers overlapping at any one point. This feature ensures that when the gasket is installed, the total gasket thickness is never greater than the original number of layers in the gasket assembly, as depicted in FIG. 4. This configuration ensures that the layers remain in alignment and in direct contact with each other.

The use of the series of foldable tabs, recesses, and square cut-outs and pairs of slits in the various gasket layers that align during layer assembly eliminates the ability of the layers to slide indecently if the welds or other means of attachment that may have been used fails. The foldable tabs act as limiters to the horizontal movement of the layers within the joint. This combination of tabs and recesses does not add additional thickness to the gasket in the region between the joint. The ability to locate these features within the joint eliminates the horizontal motion from “unfolding” the tabs that are acting as the motion limiters.

Claims

1. An exhaust manifold gasket, comprising:

a first outer layer comprising an outer surface, an inner surface, two bolt hole flanges with bolt holes therethrough, a central aperture between said flanges, and at least two internal square cut-outs, said surfaces bounded by an outer perimeter portion, wherein at least two foldable tabs extend from said outer perimeter portion;

a first inner layer and a second inner layer each comprising an outer surface, an inner surface, two bolt hole flanges with bolt holes therethrough, a central aperture between said flanges, and at least two pair of internal slits, said surfaces bounded by an outer perimeter portion, wherein at least two locator tabs extend from said outer perimeter portion of each of said first inner layer and said second inner layer, and a bead circumferentially extending about said central aperture inboard said outer perimeter portion of said first inner layer and said second inner layer; and

a second outer layer comprising an outer surface, an inner surface, two bolt hole flanges with bolt holes therethrough, a central aperture between said flanges, and at least two internal square cut-outs, said surfaces bounded by an outer perimeter portion, wherein at least two recesses extend inward from said outer perimeter portion outboard of each of said internal square cut-outs.

2. An exhaust manifold gasket according to claim 1, wherein said foldable tabs on said first outer layer are aligned with said recesses on said second outer layer.

3. An exhaust manifold gasket according to claim 1, wherein said pairs of internal slits on each of said first inner layer and said second inner layer are aligned with one another.

4. An exhaust manifold gasket according to claim 1, wherein said locator tabs on each of said first inner layer and said second inner layer are opposite and diagonal from each other.

5. An exhaust manifold gasket according to claim 1, wherein said internal square cut-outs on each of said first outer layer and said second outer layer are aligned with one another.

6. An exhaust manifold gasket according to claim 1, wherein said central apertures of all said layer are aligned with one another and have a complimentary shape to one another.

7. An exhaust manifold gasket according to claim 1, wherein said beads of said inner layers are radially aligned with one another.

8. An exhaust manifold gasket according to claim 1, wherein said inner and outer surfaces on each of said outer layers are planar and parallel and define between them a substantially constant thickness.

9. An exhaust manifold gasket according to claim 1, wherein four foldable tabs extend from said outer perimeter portion of said first outer layer.

10. An exhaust manifold gasket according to claim 1, wherein two locator tabs extend from said outer perimeter portion of each of said first inner layer and said second inner layer.

11. An exhaust manifold gasket according to claim 1, wherein said inner surface of said first inner layer is directly adjacent said inner surface of said first outer layer.

12. An exhaust manifold gasket according to claim 1, wherein said outer surface of said second inner layer is directly adjacent said inner surface of said second outer layer.

13. An exhaust manifold gasket according to claim 1, wherein said outer surface of said first inner layer is directly adjacent said inner surface of said second inner layer.

14. An exhaust manifold gasket according to claim 1, wherein said foldable tabs on said first outer layer are folded into a C-shape and enclose around said outer perimeter portion of each of said first inner layer, said second inner layer and said second outer layer.

15. An exhaust manifold gasket, comprising:

a first layer comprising an outer surface, an inner surface, two bolt hole flanges with bolt holes therethrough, a central aperture between said flanges, and at least two internal square cut-outs, said surfaces bounded by an outer perimeter portion, wherein at least two foldable tabs extend from said outer perimeter portion; and

a second layer comprising an outer surface, an inner surface, two bolt hole flanges with bolt holes therethrough, a central aperture between said flanges, and at least two pair of internal slits, said surfaces bounded by an outer perimeter portion, wherein two locator tabs extend from said outer perimeter portion, and a bead circumferentially extending about said central aperture inboard said outer perimeter portion.

16. An exhaust manifold gasket according to claim 15, wherein said internal square cut-outs on said first layer are aligned with said pairs of internal slits on said second layer.

17. An exhaust manifold gasket according to claim 15, wherein said locator tabs on said second layer are opposite and diagonal from each other.

18. An exhaust manifold gasket according to claim 15, wherein said central apertures of said both layers are aligned with one another and have a complimentary shape to one another.

19. An exhaust manifold gasket according to claim 15, wherein four foldable tabs extend from said outer perimeter portion of said first layer.

20. An exhaust manifold gasket according to claim 15, wherein said foldable tabs on said first outer layer are folded into a C-shape and enclose around said outer perimeter portion of said second layer.