Abstract:
A gasket is provided having a body including at least one service aperture and an integrally formed sealing bead portion. In an embodiment, the sealing bead portion includes a first outwardly extending bead and a first concave channel opposite the first outwardly extending bead. The first concave channel is defined by a second outwardly extending bead and a third outwardly extending bead. In an alternative embodiment, the sealing bead portion includes an annular sealing member molded to the body, and the annular sealing member is opposite an outwardly projecting sealing bead. In a second alternative embodiment, the sealing bead portion includes an internal chamber filled with a pressurized gas. In a third alternative embodiment, the sealing bead portion defines a chamber filled a polymeric material.

Description:
FIELD OF THE INVENTION 
   The present invention relates to gaskets, and more particularly, to a molded plastic gasket. 
   BACKGROUND OF THE INVENTION 
   Gaskets have been used for many years for providing a sealed connection between two relatively static members. Gaskets typically require a compressive load between the members being sealed in order for the gasket to provide an effective seal. For example, a gasket placed between two stationary members, such as an engine block and an oil pan or an engine cylinder head and a valve/cam cover, is compressed between these elements. 
   One gasket design includes a molded plastic body having a solid molded sealing bead surrounding a central service aperture. The use of a solid molded sealing bead requires a large clamping force to ensure a good seal. The high clamping force results in a high compression force which in turn may cause the plastic to deform over time and thus reduce the effectiveness of the seal. 
   Accordingly, a need exists for a gasket having a sealing bead with a reduced propensity to deformation. 
   SUMMARY OF THE INVENTION 
   The present invention provides a gasket including a body defining at least one service aperture. A sealing bead is formed integral to the body and surrounds the service aperture. The sealing bead includes a first outwardly extending segment and a first concave channel opposite the first outwardly extending segment. The first concave channel is defined by a second outwardly extending segment and a third outwardly extending segment. 
   The present invention further provides an alternative embodiment in which a gasket has a body defining at least one service aperture and including an integrally formed sealing bead. The sealing bead includes an annular sealing member molded to the body, and the annular sealing member is opposite an outwardly projecting sealing bead segment. 
   In a second alternative embodiment, the present invention provides a gasket having a body defining at least one service aperture and a sealing bead integrally formed with the body. The sealing bead includes an internal chamber filled with a pressurized gas. 
   A third alternative embodiment of the gasket includes a body composed of a first polymeric material and defining at least one service aperture. The body has an integrally formed sealing bead. The sealing bead defines a chamber filled with a second polymeric material. 
   Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
       FIG. 1  is a perspective view of a molded plastic gasket according to the principles of the present invention; 
       FIG. 2  is a cross sectional view taken along line  2 — 2  of  FIG. 1 ; 
       FIG. 3  is a perspective view of a molded plastic gasket according to an alternative embodiment of the present invention; 
       FIG. 4  is a cross sectional view taken along line  4 — 4  of  FIG. 3 ; 
       FIG. 5  is a perspective view of a molded plastic gasket according to a second alternative embodiment of the present invention; 
       FIG. 6  is a cross sectional view taken along line  6 — 6  of  FIG. 5 ; 
       FIG. 7  is a perspective view of a molded plastic gasket according to a third alternative embodiment of the present invention; and 
       FIG. 8  is a cross sectional view taken along line  8 — 8  of  FIG. 7 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
   Referring now to  FIG. 1 , a gasket  10  according to the principles of the present invention is shown. It will be understood that the shape of the gasket  10  is for illustrative purposes only and does not limit the scope of the present application. The gasket  10  will now be described as depicted in  FIGS. 1–8 , wherein common reference numbers are utilized to represent the same or similar elements. In overview, the gasket  10  has a body  12  including a service aperture  14  and a sealing bead portion  16 . 
   With reference generally to  FIGS. 1–8 , the service aperture  14  is typically formed in the center of the body  12 , along a centerline C. Preferably the body  12  is generally molded from a heat resistant polymer, such as, for example, glass fiber filled polyamide  12  (or other nylons) or glass fiber filled polyphenylene sulfides (PPS), which exhibit good flexibility, resistance to automotive fluids, and resistance to engine temperatures. The body  12  further has a first end  18 , a second end  20  and a thickness T. The first end  18  and second end  20  may each further include a mounting aperture  22  for receipt of a fastening mechanism (not shown), such as, for example, a bolt or screw, therethrough. The body  12  also has a first surface  24  and a second surface  26 . Although the body  12  is shown as being ring-shaped and the service aperture is illustrated as circular, it should be understood that other shapes can be utilized depending upon the size and shape of the surfaces to be sealed. Furthermore, the number of mounting apertures may also be varied depending upon the size and shape of the surfaces to be sealed. 
   In one embodiment, with specific reference to  FIGS. 1 and 2 , the sealing bead portion  16  surrounds the service aperture  14  and is integrally formed with the body  12 . With reference to  FIG. 2 , the sealing bead portion  16  includes a first outwardly extending bead  28  which projects beyond the first surface  24  of the body  12 . The first outwardly extending segment  28  has a height H 1  which may be approximately equivalent to the thickness T of the body  12 . The first outwardly extending bead  28  is opposite a first concave channel  30  formed in the second surface  26  of the body  12 . The first concave channel  30  is defined in part by a second outwardly extending bead  32  and a third outwardly extending bead  34 . Channel  30  may include a depth that is greater than a height of either or both of the second and third outwardly extending beads  32 ,  34 . Both the second and the third outwardly extending beads  32 ,  34  are formed on the second surface  26  of the body  12 . The second outwardly extending bead  32  has a height H 2  and the third outwardly extending bead  34  has a height H 3 . Typically, the height H 2  and height H 3  are substantially the same, but it should be noted that the heights H 2  and H 3  can be varied according to the particular application. In this embodiment, the heights H 2  and H 3  are generally equivalent in size to the thickness T of the body  12 . 
   The second and third outwardly extending beads  32 ,  34  are also generally opposite a second concave channel  36  and a third concave channel  38 , respectively. The second and third concave channels  36 ,  38  are formed in the first surface  24  of the body  12  on opposite sides of the first outwardly extending bead  28 . The sealing bead portion  16  of this embodiment ensures a tight seal through the first, second and third channels  30 ,  36 ,  38  which enable the sealing bead portion  16  to slightly deform under pressure without altering the effectiveness of the seal. Any of the outwardly extending beads  28 ,  32  or  34  can be of generally triangular, rounded, rectangular, or any of a wide variety of other cross-sectional shapes that will occur to those skilled in the art. Any or all of such beads can be of the same height relative to the body  12 , or one or more of these beads can have a height relative to the body  12  that is different from that of any one or more of the other beads. 
   An alternative embodiment of the gasket  10 ′ is shown in  FIGS. 3 and 4 . In this embodiment, the sealing bead portion  16 ′ includes an annular channel  100  for receipt of a compressible ring  102  therein. The compressible ring  102  may be integrally formed with the sealing bead portion  16 ′ or affixed to the annular channel  100  in a post processing step. The compressible ring  102  may be formed of any elastomeric material, such as natural or nitrile rubber, for example, which exhibit a low degree of compressive stress relaxation. 
   Opposite the compressible ring  102  is an outwardly extending bead  104 . The outwardly extending bead  104  includes a first angled sidewall  106  and a second angled sidewall  108  extending from a generally planar top portion  110 . The outwardly extending bead  104  extends from the second surface  26  of the body  12 . The sealing bead portion  16 ′ is generally symmetric about a Y-axis Y 100  of the sealing bead portion  16 ′. Although the outwardly extending bead  104  is shown in a polygonal shape, it shall be noted that the shape of the outwardly extending bead  104  can be varied according to the particular sealing application. The configuration of this sealing bead portion  16 ′ provides resistance against deflection through the use of the compressible ring  102 . Specifically, the compressible ring  102  provides a stress resilient surface for clamping against, thus ensuring the effectiveness of the seal over time. 
   With particular reference now to  FIGS. 5 and 6 , a second alternative embodiment of the gasket  10 ″ is shown. In this embodiment, the sealing bead portion  16 ″ includes a first outwardly extending bead  200  and a second outwardly extending bead  202  integrally formed with the body  12 . The sealing bead portion  16 ″ is generally symmetrical about a Y-axis Y 200  of the sealing bead portion  16 ″. The first and second outwardly extending beads  200 ,  202  each include a first angled sidewall  204  and a second angled sidewall  206  extending from a generally planar top portion  208 . The first outwardly extending bead  200  extends from the first surface  24  of the body  12  while the second outwardly extending bead  202  extends from the second surface  26  of the body  12 . The first outwardly extending bead  200  has a height H 200  and the second outwardly extending bead  202  has a height H 202 . The heights H 200  and H 202  are approximately the same as the thickness T of the body  12 , but can also be greater than or less than the thickness T, depending upon a particular application. Although the first and second outwardly extending beads  200 ,  202  are shown in a polygonal shape, it shall be noted that the shape of the first and second outwardly extending beads  200 ,  202  can be varied according to the particular sealing application. 
   The first outwardly extending bead  200  and second outwardly extending bead  202  are generally positioned opposite each other and define an annular channel  210  in a center  212  of the body  12 . The annular channel  210  is configured for receipt of a pressurized gas  214 . The pressurized gas  214  retained in the annular channel  210  may comprise nitrogen, argon, or other inert gases. The pressurized gas  214  located in the sealing bead 
   A third alternative of the gasket  10 ′″ present invention is illustrated in  FIGS. 7 and 8 . The sealing bead portion  16 ′″ of this embodiment is integrally formed with the body  12  and includes a first outwardly extending bead  300  and a second outwardly extending bead  302 . The first and second outwardly extending beads  300 ,  302  are generally symmetric with respect to a Y-axis Y 300  of the sealing bead portion  16 ′″. The first outwardly extending bead  300  extends from the first surface  24  of the body  12  and the second outwardly extending bead  302  extends from the second surface  26  of the body  12 . The first and second outwardly extending beads  300 ,  302  each include a top segment  304  extending between a first angled sidewall  306  and a second angled sidewall  308 . The first outwardly extending bead  300  has a height H 300  and the second outwardly extending bead  302  has a height H 302 . The heights H 300  and H 302  are generally larger than the thickness T of the body  12 , although shorter heights may also be utilized according to a specific application. Although the first and second outwardly extending beads  300 ,  302  are shown in a polygonal shape, it shall be noted that the shape, as well as the size, of the first and second outwardly extending beads  300 ,  302  can be varied according to the particular sealing application. 
   The first and second outwardly extending beads  300 ,  302  define an inner chamber  308  for receipt of a core material  310  therein. The core material  310  may be comprised of a microcellular foam, including, for example, glass fiber filled polyamide  12  (or other nylons) or glass fiber filled polyphenylene sulfides (PPS), with microcellular pockets of nitrogen gas providing flexibility and elasticity or any other similar suitable material. The core material  310  is shown in the inner chamber  308 , however, it shall be noted that the core material  310  could be located substantially throughout the body  12 . The core material  310  provides a resilient clamping point, enabling the seal to maintain its integrity over time. 
   The gaskets  10 ,  10 ′,  10 ″,  10 ′″ of the present invention generally ensure a tight seal over time by providing a resilient clamping point. In particular, the three concave channels  30 ,  36 ,  38 , enable slight deformation without a decrease in seal strength while the compressible ring  102 , the pressurized gas  214  and the core material  310  in  FIGS. 5 through 8  create a sealing bead which are resilient. 
   The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.