Abstract:
A multi-use gasket assembly includes at least two lobes each having a fluid-conveying opening with an associated axis. Four mounting holes are formed in each of the lobes about the openings. The gasket has symmetry across a plane of symmetry containing the axes of the openings.

Description:
[0001]     This application claims priority to U.S. Provisional Patent Application Ser. No. 60/563,497, filed Apr. 19, 2004. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The subject invention generally relates to an exhaust manifold gasket for use in an automotive exhaust system. More specifically, the subject invention relates to an exhaust manifold gasket that is adaptable for installation on a variety of engines.  
         [0004]     2. Description of the Related Art  
         [0005]     It is known that automotive exhaust systems interface with an engine to convey exhaust gas away from cylinders in the engine. More specifically, an exhaust manifold is mounted to a cylinder head of the engine, and receives the exhaust gas as the exhaust gas exits the cylinder head.  
         [0006]     Exhaust manifold gaskets are known in the art. Exhaust manifold gaskets seal the exhaust manifold to the cylinder head. The exhaust manifold gaskets prevent the exhaust gas from escaping, which could create noise, cause heat damage to components in the engine compartment, and/or create environmental issues. The exhaust manifold gaskets, which are also characterized as hot static seals due to the high temperatures that the exhaust manifold gaskets are required to withstand (up to 600° C. and higher), are often made of one or more layers of steel. Some auto manufacturers impose additional specification requirements. For example, some manufactures require that an anti-friction coating, which is also heat resistant, be applied on a side of the exhaust manifold gasket that is in contact with the exhaust manifold. The anti-friction coating enables slight movement of the exhaust manifold with respect to the engine to optimize the seal between the exhaust manifold and the cylinder head.  
         [0007]     For engines having a V-shaped structure, two cylinder heads are arranged on opposite sides of the engine, due to the location of the cylinders. Thus, the exhaust system is required to have two separate exhaust manifolds on opposite sides of the engine, which requires two respective exhaust manifold gaskets. Fasteners are configured for the exhaust manifolds on the opposite sides of the engine to be generally mirror images of each other, which presents a number of problems for manufacturers of components for the exhaust system, in particular the exhaust manifold gaskets. For example, as described in further detail below, the exhaust manifold gasket must be flipped to be installed on the opposite sides of the engine, i.e., a different surface of the gasket faces the exhaust manifold on the opposite sides of the engine. As a result, both sides of the exhaust manifold gasket must be coated with the anti-friction coating.  
         [0008]     Exhaust manifold gaskets are generally configured to have a series of mounting holes, each for receiving a fastener on the engine. Referring to  FIG. 1 , a conventional exhaust manifold gasket is disclosed. With this prior art exhaust manifold gasket, the mounting holes are diagonally spaced on each side of the exhaust manifold gasket and match a configuration of fasteners on the engine. More specifically, the exhaust manifold gasket defines multiple openings. The openings are defined along an axis A. One mounting hole is defined on each side of each opening. The mounting holes for each opening are arranged diagonally across the opening such that an axis B between the mounting holes intersects the axis A between the openings at a non-perpendicular angle. Because no complementary set of holes exist, the exhaust manifold gasket must be flipped during installation to fit the opposite side of the engine.  
         [0009]     However, for the exhaust manifold gasket described above, one surface of the exhaust manifold gasket faces the exhaust manifold on one side of the V-shaped engine, and an opposite surface of the exhaust manifold gasket faces the exhaust manifold on the other side of the engine. As such, the entire exhaust manifold gasket must be coated with the anti-friction coating, even though the coating is only required for the surface that is in contact with the exhaust manifold. Anti-friction coatings are relatively costly. Therefore, coating both sides of the exhaust manifold gasket is more expensive than coating only one side of the exhaust manifold gasket.  
         [0010]     Thus, there is an opportunity to overcome the deficiencies of the related art and lower the cost of the exhaust manifold gasket. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:  
         [0012]      FIG. 1  is a plan view of a exhaust manifold gasket of the prior art;  
         [0013]      FIG. 2  is a partially exploded perspective view of an engine, an exhaust manifold, and an exhaust manifold gasket of the subject invention;  
         [0014]      FIG. 3   a  is a plan view of a first embodiment of the exhaust manifold gasket;  
         [0015]      FIG. 3   b  is a cross-sectional side view of a portion of the exhaust manifold gasket of  FIG. 3   a;    
         [0016]      FIG. 4  is another plan view of the exhaust manifold gasket of  FIG. 1 ; and  
         [0017]      FIG. 5  is a plan view of another embodiment of the exhaust manifold gasket. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]     Referring to the Figures, wherein like numerals indicate like or corresponding parts throughout the several views, an exhaust manifold gasket is shown generally at  10 . The exhaust manifold gasket  10  is adaptable for installation on engines  12  preferably having a V-shaped configuration. However, it is also to be appreciated that the exhaust manifold gasket  10  may be installed on engines that have various other configurations, including, but not limited to, in-line engines.  
         [0019]     Referring to  FIG. 2 , an exhaust manifold  16  is mounted to a cylinder head  14  of the engine  12 , and receives the exhaust gas as the exhaust gas exits the cylinder head  14 . The exhaust manifold  16  conveys the exhaust gas through the exhaust system. The V-shaped engine  12  also includes a second cylinder head that is not shown. A second exhaust manifold, also not shown, is mounted to the second cylinder head. Fasteners  30  are configured on each side of the engine  12  for mounting the exhaust manifold  16  and the second exhaust manifold to the engine  12 . Preferably, the fasteners  30  are bolts, with a nut  31  securing the exhaust manifold gasket  10  and the exhaust manifold  16  to the engine  12 . The configuration of fasteners  30  on one side of the engine  12  may be a mirror image of the configuration of fasteners (not shown) on the other side of the engine  12 . Due to the design of the exhaust manifold gasket  10 , however, the same side of the exhaust manifold gasket  10  will face the exhaust manifold  16  no matter which side of the engine  12  the exhaust manifold gasket  10  is installed on. The significance of this feature of the exhaust manifold gasket  10  of the present invention will be discussed in further detail below.  
         [0020]     The exhaust manifold gasket  10 , also known as a hot static seal  10 , has an anti-friction coating  11 . The anti-friction coating  11 , which is heat resistant, is preferably applied to a surface  13  of the exhaust manifold gasket  10  that is to be in contact with the exhaust manifold  16 . The anti-friction coating  11  preferably includes molybdenum or compounds including molybdenum, such as molybdenum disulfide, which provides excellent anti-friction properties. However, other anti-friction coatings may be used.  
         [0021]     The exhaust manifold gasket  10  may be made of embossed steel, high-temperature fiber material, graphite, ceramic composites, or any other type of material commonly used for exhaust manifold gaskets in the exhaust system. Furthermore, the exhaust manifold gasket  10  may include multiple layers.  
         [0022]     Referring to  FIGS. 3   a  and  4 , the exhaust manifold gasket  10  defines an opening  20  having an axis  21  for allowing the exhaust gas to pass from the cylinder head  14  to the exhaust manifold  16 . The opening  20  lies along an axis A of the gasket  10 . Preferably, the exhaust manifold gasket  10  has at least two lobes  18 , with each lobe defining one opening  20 . However, it is to be appreciated that the exhaust manifold gasket  10  may only include one lobe  18 . The lobes  18  may be separated by relatively narrower neck regions  19 .  
         [0023]     As shown in  FIG. 2 , two separate exhaust manifold gaskets  10  may be installed on the engine  12 . Alternatively, as shown in  FIG. 4 , another exhaust manifold gasket  110  defining four openings  20  may be installed on the engine  12 .  
         [0024]     Each lobe  18  includes an apron  22  that surrounds each opening  20  for facilitating attachment of the exhaust manifold gasket  10  to the engine  12 . More specifically, the exhaust manifold gasket  10  is produced from a blank. The blank is preferably stamped out of a sheet of material and has an outer perimeter  24 , which preferably remains unchanged in the final exhaust manifold gasket  10 , which is shown in  FIG. 3   a . Alternatively, excess portions  21  of the apron  22 , which are crosshatched in  FIG. 4 , may be trimmed off, leaving tabs  26  extending from the openings  20 . However, since the excess portions  21  do not affect attachment of the exhaust manifold gasket  10  to the engine  12  and require additional processing to remove, it is preferred that the excess portions  21  remain on the exhaust manifold gasket  10 .  
         [0025]     Referring to  FIG. 3   b , a cross-section of the exhaust manifold gasket  10  is shown. The exhaust manifold gasket  10  preferably has two layers which separate around the opening  20 .  
         [0026]     A first set of mounting holes  28  is defined in the apron  22  surrounding each opening  20 . The mounting holes  28  receive a stud or a fastener (e.g., a bolt)  30 . The mounting holes  28  are diagonally spaced on each side of the opening  20 , i.e., with one hole  28  defined on each side of each opening  20 . The mounting holes  28  correspond to the configuration of studs  30  on one side of the engine  10 . The mounting holes  28  are spaced such that a line B between the mounting holes  28  intersects the axis A between the openings  20  at a non-perpendicular angle.  
         [0027]     A second set of mounting holes  32  is also defined in the apron  22  surrounding each opening  20 . Like the first set of mounting holes  28 , the second set of mounting holes  32  are diagonally spaced on each side of the opening  20 . The second set of mounting holes  32  are symmetrical to the first set of mounting holes  28  about an axis D passing through a center of the opening  20 . Furthermore, the mounting holes  32  are spaced such that a line C between the mounting holes  32  intersects the axis A at a non-perpendicular angle. The position of the second set of mounting holes  32  enables the same exhaust manifold gasket  10  to be installed on the other side of the engine  12  such that the surface  13  of the exhaust manifold gasket  10  in contact with the exhaust manifold  16  remains the same on each side of the engine  12 . In other words, the exhaust manifold gasket  10  may be simply installed on each side of the engine  12  without flipping the exhaust manifold gasket  10 . As such, the gasket  10  has reflective symmetry across a longitudinal plane of symmetry containing the axis.  
         [0028]     Due to the two distinct sets of mounting holes  28 ,  32 , and also due to the diagonal spacing of each mounting hole  28 ,  32 , the exhaust manifold gasket  10  is designed such that the surface  13  is in contact with the exhaust manifold  16  regardless of whether the configuration of studs  30  is identical or a mirror image from one side of the engine  12  to the other. As a result, the relatively expensive anti-friction coating is only required on one side  13  of the exhaust manifold gasket  10  to reduce the cost of manufacturing the exhaust manifold gasket. In addition, the exhaust manifold gasket  10  provides for ease of installation on the engine  12  since flipping is not required to install the exhaust manifold gasket  10  on the engine  12 .  
         [0029]     Obviously, many modifications and variations of the present invention are possible in light of the above teachings. The invention may be practiced otherwise than as specifically described within the scope of the appended claims.