Patent Publication Number: US-2006001221-A1

Title: Gasket seal

Description:
FIELD OF THE INVENTION  
      The present invention relates to gaskets, and more particularly to a gasket seal having improved noise, vibration, and handling characteristics.  
     BACKGROUND OF THE INVENTION  
      Gaskets are used in a wide variety of applications to form a seal between two matched parts. Typically, a bead arrangement is formed on a portion of the gasket that elastically deflects when compressed. The internal spring force within the bead under elastic compression provides a seal between the parts.  
      Perimeter gaskets are defined by a bead arrangement that is designed to encircle the area to be sealed between the matched components. Typically, the matched components are coupled together, with the perimeter seal therebetween, using conventional bolts. These bolts extend through bolt holes formed in the matched components.  
      The purpose of the gasket is to seal the two components together and therefore sealing forces must be maintained on the bead in order to maintain the internal spring force, and hence the seal. In this regard, conventional gaskets have been designed to elastically deflect sufficiently to maintain this seal.  
      While these conventional gaskets are useful for their intended purpose, there is room in the art for improvement. Specifically, noise, vibration, and handling characteristics (NVH) of one matched component are often transferred directly through the gasket onto the matching part and gasket through the bolts. In the case of an automobile, for example, this NVH can be highly undesirable.  
      Accordingly, the present invention provides the art with a gasket having a bead arrangement that reduces NVH transmitted through the gasket without substantially increasing manufacturing costs and without diverting sealing loads.  
     SUMMARY OF THE INVENTION  
      A gasket for use in sealing a first component to a second component includes a first portion having a first shape factor. The first portion is adapted to seal the first component to the second component. A second portion has a second shape factor, the second portion is adapted to minimize vibration transmission between the first and second components. The first shape factor is designed to maximize sealability of the first portion and the second shape factor is designed to minimize vibration transmission of the second portion.  
      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 bottom view of an exemplary cam cover and a gasket constructed according to the principles of the present invention;  
       FIG. 2  is an enlarged view of the exemplary cam cover and gasket of the area enclosed by circle  2 - 2  in  FIG. 1 ;  
       FIG. 3  is a cross-sectional view of a portion of the gasket of the present invention viewed in the direction of arrow  3 - 3  in  FIG. 2 ; and  
       FIG. 4  is a cross-sectional view of a portion of the gasket of the present invention viewed in the direction of arrow  4 - 4  in  FIG. 2 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
      With reference to  FIG. 1 , a gasket  10  constructed according to the principles of the present invention is shown in operative association with an exemplary cam cover  12 . The gasket  10  is a perimeter gasket and is operable to seal the cam cover  12  to a cylinder head (not shown). However, it should be appreciated that the gasket  10  may be of any type and may be used to seal any first component to any second component. Accordingly, the shape and size of the gasket  10  are defined by the requirements of providing an effective seal between these components. It should be appreciated, therefore, that the shape and design of the gasket  10  illustrated in the present invention is not limited to the particular arrangement illustrated in  FIG. 1 .  
      The cam cover  12  generally includes a body  14  having a plurality of cylinder head apertures  16  formed therethrough. Each cylinder head aperture  16  is adapted to align and couple with the cylinder head (not shown) of an engine (not shown). The cylinder head apertures  16  are circumferentially surrounded by a bead  18 . The bead  18  is operable to seal the gasket  12  to the cylinder head.  
      The body  14  of the cam cover  12  further includes a plurality of flange portions  20  that extend out from the body  14 . The flange portions  20  are formed along the perimeter of the cam cover  12 . Each flange portion  20  includes a bolt hole formed therethrough, including corner bolt holes  22  and body bolt holes  24 . The corner bolt holes  22  are positioned along the perimeter through a flange portion  20  wherever there is a corner formed in the body  14 . In the particular example provided, the cam cover  12  includes seven corner bolt holes  22 . The plurality of body bolt holes  24  are also along the perimeter of the cam cover  12  through a flange portion  20 . The body bolt holes  24  are positioned along straight sections of the perimeter of the cam cover  12 . In the particular example provided, the cam cover  12  includes four body bolt holes  24 .  
      Turning now to  FIG. 2 , the gasket  10  will be described in further detail. As noted above, in the particular example provided the gasket  10  is a perimeter gasket sized to extend along the perimeter of the cam cover  12 . The gasket  10  generally includes a perimeter bead portion  26  and a reinforcement bead portion  28 .  
      With reference to  FIG. 3 , the perimeter bead portion  26  has a generally rectangular shaped body portion  30  with an enlarged truncated triangular head  32  extending therefrom. A pair of ribs  34  are formed on opposite sides of the perimeter bead portion  26 , i.e., a pair of ribs  34  are formed on an end of the rectangular body  30  and on an end of the truncated triangular head  32 . The ribs  34  deflect when the gasket  10  is compressed between the cam cover  12  and the cylinder head (not shown). The ribs  34  retain an internal spring force upon deflection that acts to seal the perimeter bead portion  26  to the two components. In this regard, the perimeter bead portion  26  is designed to maximize the seal between these two components. Returning to  FIG. 2 , the perimeter bead portion  26  extends around a portion of the flange portion  20  and around a portion of the bolt holes  22 ,  24 . In the example provided, the perimeter bead portion  26  extends around a portion of the bolt holes  22 ,  24  inwardly from the bolt holes  22 ,  24  (i.e., on the side of the bolt holes  22 ,  24  towards the center of the cam cover  12 ).  
      With reference to  FIG. 4 , the reinforcement bead portion  28  is designed to reduce the NVH transmitted through bolts (not shown) that couple the cam cover  12  ( FIGS. 1 and 2 ) to the cylinder head (not shown). The actual shape and design of the reinforcement bead portion  28  will be, therefore, dependent on the specific environment to which it is applied. In the particular example provided, the reinforcement bead portion  28  includes a similar cross section to that of the perimeter bead portion  26  in  FIG. 3 , however, the reinforcement bead portion  28  does not include the ribs  34 . Instead, the reinforcement portion  28  includes flat surfaces  36  on opposite sides thereof. In this regard, under an identical compression load, the reinforcement bead portion  28  is compressed less than the perimeter bead portion  26 . For any given application, the shape of the reinforcement bead portion  28  will be largely defined by its shape factor (i.e. its ratio of surface area under compression to surface area not under compression). The shape factor will be tuned to minimize the NVH transmission between any two components, or multiple components, that will compress the gasket  10  when in use. In this regard, the bead portions  26 ,  28  may be tuned to their respective tasks separately (i.e., the perimeter bead portion  26  tuned for maximum sealing, the reinforcement bead portion  28  tuned for maximum NVH transmission prevention).  
      Returning to  FIG. 2 , the reinforcement bead portion  28  extends out from the perimeter bead portion  26  in a loop to surround any given bolt hole  22 ,  24 . In the particular example provided, the reinforcement bead portion  28  extends around the corner bolt holes  22  supported by the flange portion  20  and intersects the perimeter bead portion  26  at an opposite end thereof. Preferably, the perimeter bead portion  26  and reinforcement bead portion  28  are formed from a single unitary material.  
      The gasket  10  reduces NVH transmission by controlling the flange portions  20  which may or may not include stiffening the flange portions  20  surrounding the bolt holes  22 ,  24  to thereby lessen vibration transmission. As noted above, the gasket  10  provides dual functions by effectively sealing the two components together using the perimeter bead portion  26  while reducing NVH transmission using the reinforcement bead portion  28 . Added benefit is achieved by employing substantially similar cross sectional areas within the gasket  10 , thereby limiting any increases to manufacturing costs.  
      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.