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 bolded 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 and 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 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 and slots 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, and a central aperture between the flanges. The surfaces are bounded by an outer perimeter portion. At least two foldable tabs are nested within the outer perimeter portion with a cut-out on each side of the foldable tab. 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, and a central aperture between the flanges, and at least two internal slots. 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 slots. The surfaces are bounded by an outer perimeter portion.
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 block;
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, 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 128, a first inner layer 66, and a second inner layer 96. It is also within the scope of the invention for there to be more or fewer layers. The two outer layers 20, 128 and the two inner layers 66, 96 may 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, and a central aperture 34 between the flanges 26, 28.
The surfaces 22, 24 of the first outer layer 20 are bounded by an outer perimeter portion 36, wherein unitary foldable tabs 38, 40, 42, 44 are nested within the outer perimeter portion 36. A rectangular shaped cut-out 46, 48, 50, 52, 54, 56, 58, 60 is adjacent each side of each foldable tab 38, 40, 42, 44, and an outer edge 62 of each of the foldable tabs 38, 40, 42, 44 is substantially even with an outer edge 64 of the outer perimeter portion 36. While as depicted in FIGS. 7 and 8 four foldable tabs are shown, it is within the scope of the invention for there to be more or fewer tabs. The foldable tabs 38, 40, 42, 44 are generally located toward the narrow ends of the oval outer perimeter portion 36 between the bolt hole flanges 26, 28 and the central aperture 34. The rectangular shaped cut-outs 46, 48, 50, 52, 54, 56, 58, 60 extend inward from the outer perimeter portion 36, and are parallel and coplanar to the inner surface 24 and outer surface 22. As depicted in FIG. 8 there are eight cut-outs 46, 48, 50, 52, 54, 56, 58, 60 one on either side of each foldable tab 38, 40, 42, 44.
As depicted in FIGS. 7, 9 and 10, the first inner layer 66 and the second inner layer 96 each comprise an outer surface 68, 98, an inner surface 70, 100, two bolt hole flanges 72, 74, 102, 104 with bolt holes 76, 78, 106, 108 therethrough, a central aperture 80, 110 between the flanges 72, 74, 102, 104, and at least two internal slots 81, 82, 84, 86, 112, 114, 116, 118.
The surfaces 68, 70, 98, 100 of each of the inner layers 66, 96 are bounded by an outer perimeter portion 88, 120. The outer perimeter portion 88, 120 is generally oval in shape and includes locator tabs 90, 92, 122, 124. As shown in FIGS. 9 and 10, the locator tabs 90, 92, 122, 124 extend unitarily outward from the outer perimeter portion 88, 120. Locator tabs 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 90, 92, 122, 124 are shown on each of the inner layers 66, 96, 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 90, 92, 122, 124 on each of the inner layers 66, 96 are located on opposite sides, diagonally across from each other. The locator tabs 90, 92, 122, 124 are generally located toward the narrow ends of the oval outer perimeter portion 88, 120 between the bolt hole flanges 72, 74, 102, 104 and the central aperture 80, 110.
As shown in FIGS. 4 and 7, the internal slots 81, 82, 84, 86, 112, 114, 116, 118 on each of the first and second inner layers 66, 96 are aligned with one another. The internal slots 81, 82, 84, 86, 112, 114, 116, 118 are located inboard of the outer perimeter portion 88, 120, and generally located toward the narrow ends of the oval outer perimeter portion 88, 120 between the bolt hole flanges 72, 74, 102, 104 and the central aperture 80, 110. The internal slots 81, 82, 84, 86, 112, 114, 116, 118 are oriented parallel with and adjacent the outer perimeter portion 88, 120. The width of each internal slot 81, 82, 84, 86, 112, 114, 116, 118 is less than the length.
As depicted in FIGS. 2 and 3, the first inner layer 66 and the second inner layer 96 each comprise a bead 94, 126 which circumferentially extends about the central aperture 80, 110 and is inboard of the outer perimeter portion 88, 120. The two inner layers 66, 96 are a mirror image of one another, as shown in FIGS. 9 and 10.
As depicted in FIGS. 7 and 11, the second outer layer 128 comprises an outer surface 130, an inner surface 132, two bolt hole flanges 134, 136 with bolt holes 138, 140 therethrough, a central aperture 142 between the flanges 134, 136, and at least two internal slots 144, 146, 148, 150. The surfaces are bounded by an outer perimeter portion 152, which is generally oval in shape.
The internal slots 144, 146, 148, 150 are located inboard of the outer perimeter portion 152, and generally located toward the narrow ends of the oval outer perimeter portion 151 between the bolt hole flanges 134, 136 and the central aperture 142. The internal slots 144, 146, 148, 150 are oriented parallel with and adjacent the outer perimeter portion 152. The width of each internal slot is less than the length. As depicted in FIG. 7, the internal slots 144, 146, 148, 150 on the second outer layer 128 are also aligned with the internal slots 81, 82, 84, 86, 112, 114, 116, 118 on each of the first and second inner layers 66, 96. As shown in FIG. 3, the inner surface 24, 132 and the outer surface 22, 130 of each of the outer layers 20, 128 are planar and parallel to one another, and define between them a substantially constant thickness.
As shown in FIGS. 2, 6 and 7, the central aperture 34, 80, 110, 142 on all the layers 20, 66, 96, 128 are aligned with one another and have a complimentary shape when the layers 20, 66, 96, 128 are placed together for assembly. When all the layers 20, 66, 96, 128 are aligned, the beads 94, 126 of the inner layers 66, 96 are also radially aligned with one another. Once the layers 20, 66, 96, 128 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 38, 40, 42, 44 on the first outer layer 20 align with and fit into the internal slots 81, 82, 84, 86, 112, 114, 116, 118, 144, 146, 148, 150 in each of the first and second inner layers 66, 96 and the second outer layer 128.
As can also be depicted from FIGS. 5, 6 and 7 when the layers 20, 66, 96, 128 are assembled, the inner surface 70 of the first inner layer 66 is directly adjacent the inner surface 24 of the first outer layer 20, and the outer surface 98 of the second inner layer 96 is directly adjacent the inner surface 132 of the second outer layer 128. The outer surface 68 of the first inner layer 66 is directly adjacent the inner surface 100 of the second inner layer 96 when assembled.
As depicted in FIGS. 4 and 5, in their original position the foldable tabs 38, 40, 42, 44 on the first outer layer 20 are parallel and coplanar to the inner surface 24 and outer surface 22. For assembly, the foldable tabs 38, 40, 42, 44 are folded at a 90 degree so that they are transverse to the inner and outer surfaces 24, 22 of the first outer layer 20. The remaining layers 66, 96, 128 are stacked onto the first outer layer 20, so that the foldable tabs 38, 40, 42, 44 extend through the internal slots 81, 82, 84, 86, 112, 114, 116, 118, 144, 146, 148, 150 of each of the layers 66, 96, 128. The foldable tabs 38, 40, 42, 44 are then folded again, so that they are parallel and non-planar to the inner and outer surfaces 24, 22 of the first outer layer 20, as depicted in FIG. 4. This configuration ensures that the layers 20, 66, 96, 128 remain in alignment and in direct contact with each other.
The use of the series of foldable tabs and internal slots in the various gasket layers that align during assembly eliminates the ability of the layers to slide independently 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 slots 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.
Patent Application
20120139188
