Abstract:
An improved combustion gasket is disclosed incorporating a self-energizing combustion seal flange. The flange includes at least one valley that serves to redistribute combustion explosion forces acted upon the gasket during operation of the engine to provide improved combustion sealing and to extend flange life.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a cylinder head gasket for an internal combustion engine. More particularly, the invention relates to cylinder head gasket having a self-energizing combustion seal flange. 
     BACKGROUND OF THE INVENTION 
     Gaskets  10  are often used to provide a seal between an engine block  12  and a cylinder head  14  of an internal combustion engine. As shown in FIGS. 1-3, known cylinder head gaskets  10  typically include a flange  16  that extends around the periphery  18  of cylinder bores formed in the gasket  10  to provide a combustion seal for maintaining the high temperature gases of combustion within the cylinder bores. A typical combustion flange  16  has a generally semicircular cross-sectional shape with the outmost portion  20  of the flange  16  extending away from the periphery  18  and into the combustion bore. 
     Referring to FIGS. 1 and 2, during operation of the engine, combustion explosion forces (represented by arrows A) act upon the flange  16 . As can be seen in FIG. 3, the combustion forces A C  try to pass between the overlap of the flange  16  and the cylinder head  14  and heel of the flange  16  and the engine block  12 . The tangential forces A T  acting on the flange  16  pushes ends  22  of the flange  16  downward and way from the engine block  12  and cylinder head  14 , thereby reducing sealing and promoting combustion leaks between the flange  16  and the hardware  12  and  14 . Accordingly, more durable combustion seals are required to reduce the opportunity for combustion leaks and increase flange life. 
     SUMMARY OF THE INVENTION 
     The present invention provides a gasket having a core and a self-energizing seal flange. The core includes at least one gasket plate, wherein the plate has at least first apertures for mating with cylinder bores of an engine block. 
     In accordance with the invention, the self-energizing seal flange has a generally convex center face that directly addresses a flame front of a combustion bore opening in an otherwise generally concave combustion flange cross-sectional profile. Such a design produces a generally flatter medial profile or face to address the flame front of the combustion zone, thereby minimizing deleterious tangential forces that operate to create gasket leaks and to shorten the life of the flange. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features and inventive aspects of the present invention will become more apparent upon reading the following detailed description, claims, and drawings, of which the following is a brief description: 
     FIGS. 1-3 are cross-sectional views of a prior art gasket. 
     FIG. 4 is a partial planar view of a gasket in accordance with the present invention. 
     FIG. 5 is a cross-sectional view of an embodiment of the present invention positioned between mating components taken along line  5 — 5  of FIG. 4 shown with combustion explosion forces acting upon a combustion seal flange. 
     FIG. 6 is a cross-sectional view of the embodiment of FIG. 5 with the combustion explosion forces broken down into its respective tangential and normal components. 
     FIG. 7 is another cross-sectional view of the embodiment of FIG. 5 illustrating the effect of normal forces exerted on the combustion seal flange. 
     FIG. 8 is a cross-sectional view of the embodiment of FIG. 5 in an unloaded condition. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIGS. 4-7 illustrate a gasket  100  that is adapted to be positioned between an engine block  102  and a cylinder head  104  of a combustion engine. Gasket  100  has a plurality of bolt holes  106  and first apertures  108  that are adapted to mate with cylinder bores of engine block  102 . Gasket  100  may also provided with second apertures (not shown) that serve as fluid flow openings for engine coolant and the like. Gasket  100  is constructed so as to provide at least one combustion seal around the periphery  110  of each first aperture  108 . 
     Referring to FIGS. 5-7, gasket  100  includes a core  112  that has at least one gasket plate and a combustion seal flange  114 . Core  110  may be constructed of any suitable material, but is preferably constructed of metal. Combustion seal flange  114  is preferable constructed of metal to resist the high temperatures of combustion gases passing through combustion bores  108 . 
     In accordance with one aspect of the invention, flange  114  includes a head leg  116  and a block leg  118 . Head leg  116  and block leg  118  are connected together by a bridge segment  120  that extends around periphery  110  of combustion bore opening  108 . Bridge segment  120  has a generally concave cross-sectional profile face. However, unlike known gasket flanges, bridge segment  120  further includes at least one slightly inwardly extending portion that forms a shallow and generally convex-shaped valley  122  between adjacent peaks  124  or a generally flatter profile face than the rounded profile faces of the prior art. 
     In the preferred embodiment, bridge segment  120  includes only one valley  122 . It is also preferred that valley  122  is positioned at approximately the center of bridge segment  120 . Referring to FIG. 8, in one preferred embodiment, valley  122  has a radius R in the range of about 0.40-0.80 inches and the distance D from an outermost profile face  126  of peaks  124  to the outermost profile face  128  of valley  122  is within the range of about 0.000-0.010 inches. 
     Referring to FIGS. 5-7, the operation of gasket  100  will be explained in greater detail. As can be seen in FIG. 5, during operation of a combustion engine, combustion explosion forces C F  act upon the outer profile face  130  of flange  114 . The combustion explosion forces C F , are shown broken down into their respective tangential components F CT  and normal components F CN  in FIG.  6 . Due to the inclusion of valley  122 , most of the combustion forces C F  are transferred into valley  122 , rather than the corners formed between the cylinder head  104  and flange  114  and the engine block  102  and flange  114 . 
     Referring to FIG. 7, in accordance with the invention, the normal force component F CN  acts perpendicularly to the outer profile face  130  of flange  114 , causing head and block legs  116 ,  118  to push against cylinder head  104  and engine block  102 , respectively. Thus, the normal force component F CN  contributes to increase the pressure of flange  114  against head and block legs  116 ,  118  to reduce the opportunity for combustion leaks, and to increase flange life. 
     Preferred embodiments of the present invention have been disclosed. A person of ordinary skill in the art would realize, however, that certain modifications would come within the teachings of this invention. Therefore, the following claims should be studied to determine the true scope and content of the invention.