Abstract:
A gasket includes a fist sealing portion, a second sealing portion, and an elastic arm sealingly connecting between the two. The first sealing portion sealingly engages a first member and the second sealing portion sealingly engages a second member. The elastic arm is not highly compressed between the members, allowing the gasket to vibrationally decouple the first member from the second member.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This clams the benefit of U.S. provisional patent application identified as Application No. 60/349,024, filed Jan. 15, 2002. 

   BACKGROUND OF INVENTION 
   This invention relates in general to fluid seals. More specifically, this invention relates to gaskets that connect two sealing portions, which prevent fluid leakage between the two, while reducing the transmission of vibrations through the gasket. 
   In general, conventional gaskets require a relatively high 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. However, while producing an effective seal, these highly compressed gaskets can become a medium for transmitting vibrations, creating poor noise, vibration and harshness (NVH) isolation characteristics between the two members. That is, the vibration load input from one member is easily transferred through the gasket to the other member. Moreover, in these applications that require the high compressive sealing load, the number and placement of fasteners must compensate for deflections caused by the high loading conditions in order to assure a good seal all of the way around the gasket. 
   Examples of such conventional gaskets requiring a high sealing load between the members include an elastomeric gasket, shaped as an O-ring or similar shape, as well as an edge bond gasket, a carrier gasket, and a rubber coated metal (RCM) gasket. All of these conventional gaskets require a high compressive sealing load to assure an effective seal between the members, so the effectiveness of vibrational isolation of one member from the other is poor. Another example of a conventional gasket is one formed from a room temperature vulcanite (RTV) located between the two members. The RTV is applied as a liquid in a thin layer and cures when exposed to air. For effective sealing with the RTV, however, it requires a hard mount between the members, which also provides poor vibration isolation. 
   In many applications, including automotive applications, it is desirable to reduce the transmission of vibrations. A reduction of the transmission of vibrations can result in a reduction in noise and harshness, so it is desirable to reduce the transmission of vibrations between two sealed elements, such as an engine block and an oil pan—or engine head and rocker/cam cover. 
   Thus, it is desirable to have a gasket that will properly seal between two members while allowing for vibration isolation between the two members. 
   SUMMARY OF INVENTION 
   In its embodiments, the present invention contemplates a gasket adapted for sealing between a first member and a second member. The gasket includes a first sealing portion adapted to be in sealing engagement with the first member, and a second sealing portion adapted to be in sealing engagement with the second member, and spaced from the first sealing portion. The gasket also includes an elastic arm sealingly connecting the first sealing portion to the second sealing portion, with the elastic arm being in a less than fully compressed state and a less than fully expanded state between the first sealing portion and the second sealing portion, whereby the gasket is adapted to allow the first member to be generally vibrationally decoupled from the second member. 
   An advantage of the present invention is that effective sealing is achieved between two members while providing for vibrational isolation between the two members. 
   Another advantage of the present invention is that a surface of each member can be sealed independently of the surface on the other member, with a membrane sealingly connected between the sealing surface of each member. This allows for effective sealing without requiring high compressive loading between surfaces of the members. By avoiding the high compressive loading, the gasket provides for good vibrational isolation between the members. 
   A further advantage of the present invention is that the number of fasteners can be reduced since balancing of the gasket compressive sealing load is significantly reduced. For example, the number of fasteners used to fasten an oil pan to an engine block can be reduced. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  is a partial, sectional view of a gasket mounted between two members in accordance with a first embodiment of the present invention; 
       FIG. 2  is a partial sectional view, similar to  FIG. 1 , but on an enlarged scale and with the section cut taken through a fastener location; 
       FIG. 3  is a partial, sectional view similar to  FIG. 1 , but illustrating a second embodiment of the present invention; 
       FIG. 4  is a partial, sectional view of a gasket mounted between two members in accordance with a third embodiment of the present invention; 
       FIG. 5  is a partial, sectional view of a gasket mounted between two members in accordance with a fourth embodiment of the present invention; 
       FIG. 6  is a partial, sectional view of a gasket mounted between two members in accordance with a fifth embodiment of the present invention; 
       FIG. 7  is a partial, sectional view of a gasket mounted between two members in accordance with a sixth embodiment of the present invention; 
       FIG. 8  is a partial, sectional view of a gasket mounted between two members in accordance with a seventh embodiment of the present invention; 
       FIG. 9  is a partial, sectional view of a gasket mounted between two members in accordance with an eighth embodiment of the present invention; 
       FIG. 10  is a partial, sectional view of a gasket mounted between two members in accordance with a ninth embodiment of the present invention; 
       FIG. 11  is a partial, sectional view of a gasket mounted between two members in accordance with a tenth embodiment of the present invention; and 
       FIG. 12  is a partial, sectional view of a gasket mounted between two members in accordance with an eleventh embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
     FIGS. 1 and 2  illustrate a first embodiment of the present invention. A gasket  10  is shown that includes a first sealing portion  12 , a second sealing portion  14 , and an elastic arm  16  extending between the first portion  12  and the second portion  14 . The first sealing portion  12  is in sealing engagement with a first member  18 , while the second sealing portion  14  is in sealing engagement with a second member  20 . The first member  18  and second member  20  may be, for example, an engine block and an oil pan, or a rocker/cam cover and an engine block—although, the gasket  10  of the present invention may be used to seal between other types of components where a fluid is sealed in (or out) and a reduction in vibration transmission between two components is desired. In  FIGS. 1 and 2 , if the first member  18  is an engine block and the second member  20  is an oil pan, then the oil side is preferably to the right as seen in  FIGS. 1 and 2 , with the atmosphere side to the left. 
   The first sealing portion  12  includes an elastomeric portion  22 , which surrounds a flange  24 . The flange  24  is preferably formed of a relatively stiff material, such as plastic or metal, in order to provide reinforcement and increase the strength of the first sealing portion  12 . Preferably, the elastomeric portion  22  includes a pair of sealing ribs  26 , which increase the effectiveness of sealing the first sealing portion  12  against the first member  18 . The ribs  26  can be integrally molded with the elastomeric portion  22 . The second sealing portion  14  includes an elastomeric portion  28 , which surrounds a flange  30 , similar to the first sealing portion. Again, preferably, the elastomeric portion  28  includes a pair of integral sealing ribs  32 , which increase the effectiveness of sealing the second sealing portion  14  against the second member  20 . 
   The elastic arm  16  is preferably formed integrally with the first sealing portion  12  and the second sealing portion  14 , and made of an elastomeric material such as rubber. The elastic arm  16  is not in a fully compressed state nor in a fully expanded state, so it can relatively easily flex. Since the elastic arm  16  is relatively flexible and not subjected to relatively high compressive forces, with the first sealing portion  12  spaced from the second sealing portion  14 , the first portion  12  and the second portion  14  are essentially vibrationally decoupled. And yet, a complete seal between the two members  18 ,  20  is achieved. The elastic arm  16  may be relatively smooth, acting like a membrane, as is illustrated in the  FIGS. 1 and 2 , or, alternatively, may be formed as a bellows, as illustrated in  FIG. 4 , discussed below. 
   The distance between the members  18 ,  20  is generally established at the fastener locations. Each fastener assembly  36  acts to limit the compression in the elastic arm  16  by maintaining a spacing between the members  18 ,  20 , and to assure that the vibration isolation between the members  18 ,  20  is maintained, (one fastener assembly location shown in  FIG. 2 ). While only one fastener assembly  36  is shown, the others can be essentially the same. The number of fastener locations and spacing depends upon the particular members being joined, the pressure difference of the fluids, as well as other typical factors considered for sealing between two members. However, by employing gaskets according to this invention, it is likely that the number of fasteners needed to join two members, such as an engine block and oil pan, can be reduced since the balancing of a relatively high gasket load is significantly reduced. 
   Each fastener assembly  36  preferably includes a compression limiter  38  surrounding a fastener  40 , which abuts and seals against the first sealing portion  12 . The first sealing portion  12  may include an additional sealing rib  42  that seals against a surface of the compression limiter  38 . The compression limiter  38  may have a flange  44  that abuts the first sealing portion  12 . The fastener assembly  36  also includes a grommet  46  that is received on a lip  48  formed within a bolt hole  50  of the second member  20 . A grommet support  52  surrounds the grommet  46  and abuts against the compression limiter  38 . The grommet  46  is preferably formed of an elastomeric material in order to maintain the vibration isolation between the first and second members  18 ,  20 , while the grommet support  52  is preferably made of a relatively stiffer material in order to support the grommet while providing a spacing between the compression limiter  38  and the bolt head  54 . Of course, the arrangement and shape of the compression limiters and grommets at the various fastener locations can be modified to suit the particular members being joined. 
   In the prior art, the sealing load was established by the two members being compressed together, with a gasket between them. This resulted in any elastomeric portion of the gasket being essentially fully compressed, so it cannot provide any type of vibrational isolation between the members. On the other hand, as discussed above, in the embodiments of the present invention, each sealing portion creates most of its own sealing load against a portion of the particular member against which it is sealing—this allows the elastic arm to be less than fully compressed or fully expanded. Since the gasket  10  is not highly compressed with a compression sealing load between the members  18 ,  20 , there is minimal transfer of vibration between the members  18 ,  20  via the gasket  10 , (vibrationally decoupling the first and second members). Moreover, the fastener assemblies  36  help to maintain the vibration isolation. 
     FIG. 3  illustrates a second embodiment of a gasket indicated generally at  110  according to this invention. Elements in this embodiment that are similar to elements in the first embodiment will be similarly designated, but with a 100-series number. The gasket  110  again includes a first sealing portion  112 , a second sealing portion  114 , and an elastic arm  116  that connects the sealing portions  112 ,  114 . In this embodiment, the elastic arm  116  is located on the opposite side of the sealing portions  112 ,  114 , thus illustrating that the concave surface of the elastic arm  116  may face either way relative to the fluid being sealed, if so desired. 
     FIG. 4  illustrates a third embodiment of a gasket  210  according to this invention. Elements in this embodiment that are similar to elements in the first embodiment will be similarly designated, but with a 200-series number. The gasket  210  includes a first sealing portion  212 , a second sealing portion  214 , and a flexible bellows  216  connected between them. Alternatively, the bellows  216  can be in the form of a membrane, if so desired. While the other embodiments disclosed herein illustrate a membrane for the elastic arm, a bellows may be employed instead, if so desired. 
   The first sealing portion  212  has a generally U-shaped cross section that surrounds a flange  260  of the first member  218 , with the flange  224  now forming a clip surrounded by the elastomeric portion  222 . Preferably, a series of sealing ribs  226  extend from the elastomeric portion  222  toward the member flange  260 . The flange  224  is shaped to create an opening between the sealing ribs  226  that is smaller than the thickness of the member flange  260  and is made of a material that will spring back to its original shape. So, when the first sealing portion  212  is assembled to the member flange  260 , the flange  224  will create a sealing force on the ribs  226  against the member flange  260 . The sealing ribs  226  will cause the sealing force to peak at those locations, thus creating an effective seal along the surface of the member, as is known to those skilled in the art. Moreover, the sealing force will secure the first sealing portion  212  to the member flange  260 . Consequently, the first sealing portion  212  seals against and is secured to the first member  218  without requiring any compression force applied by the second member  220 . 
   Likewise, the second sealing portion  214  has a generally U-shaped cross section, with the flange  230  forming a clip surrounded by the elastomeric portion  228 , and sealing ribs  232  protruding from the elastomeric portion  228 . The sealing ribs  232  are pressed against the member flange  262  with a sealing force sufficient to create a seal between the second sealing portion  214  and the second member  220 . The sealing force will secure the second sealing portion  214  to the member flange  262 . 
   The elastic arm  216 , in this embodiment shown as a bellows, spans the distance between the first and second sealing portions  212 ,  214 , and seals between them without the need for high compressive loads. Thus, the first and second members  218 ,  220  are vibrationally decoupled from each other. 
     FIG. 5  illustrates a fourth embodiment of the present invention. Elements in this embodiment that are similar to elements in the previous embodiments will be similarly designated, but with a 300-series number. The gasket  310  includes a first sealing portion  312  that mounts to a flange  360  of a first member  318 , and a second sealing portion  314  that mounts to a flange  362  of a second member  320 , in the same way as in the third embodiment. In this embodiment, however, the elastic arm  316  is much shorter. The shorter elastic arm  316  creates a more compact assembly, but likely does not allow for as much vibrational isolation as with the third embodiment. 
     FIG. 6  illustrates a fifth preferred embodiment of a gasket  410  according to this invention. Elements in this embodiment that are similar to elements in the previous embodiments will be similarly designated, but with 400-series numbers. The gasket  410  includes a first sealing portion  412 , a second sealing portion  414 , and an elastic arm  416 . The sealing portions  412 ,  414  again have generally U-shaped cross sections with a curved flange  424 ,  430 , respectively, for creating sealing forces. The sealing portions  412 ,  414  in this embodiment, however, are oriented to accommodate laterally offset flanges  460 ,  462 , of members  418 ,  420 , respectively, which each extend toward the opposite member. Since the sealing force acting against the first member  418  is created by the first sealing portion  412  and the sealing force acting against the second member  420  is created by the second sealing portion  414 , the sealing portions  412 ,  414  and member flanges  460 ,  462  can have various orientations while still creating a good seal and vibrationally decoupling the members. 
     FIG. 7  illustrates a sixth preferred embodiment of a gasket  510  according to this invention. Elements in this embodiment that are similar to elements in the previous embodiments will be similarly designated, but with 500-series numbers. This embodiment is similar to the embodiment of  FIG. 6 , but with a different sealing and retaining arrangement for the first and second sealing portions (only the second sealing portion  514  illustrated), but with a similar elastic arm  516 . The flange  562  of the second member  520  includes a retaining protrusion  566  extending therefrom. The elastic portion  528  surrounds the flange  530 , but preferably does not include sealing ribs. Instead, the elastic portion  528  catches on and abuts against the retaining protrusion  566  to create a seal. The flange  530  still creates the sealing and retaining force for the second sealing portion  514 . The retaining protrusion may be cast, molded, or formed in some other preferred way on the flange  562 . 
     FIG. 8  illustrates a seventh preferred embodiment of a gasket  610  according to this invention. Elements in this embodiment that are similar to elements in the previous embodiments will be similarly designated, but with 600-series numbers. A second sealing portion  614  is similar to the second sealing portion in the fifth embodiment of the present invention, with a generally U-shaped flange  630  creating a sealing and retaining force for sealing ribs  632  abutting a flange  662  of a second member  620 . The first sealing portion  612  is now shaped similar to an O-ring and fits into a recess  668 , with an interference fit between the two in order to create a sealing and retaining force between them. Again, the first seal portion  612  forms a seal against the first member  618  without requiring any compressive force contributed by the second member  620 . An elastic arm  616  extends between and is preferably formed integral with the first and second sealing portions  612 ,  614 . As with the previous embodiments, the gasket  610  provides a good seal while vibrationally decoupling the members  618 ,  620 . 
     FIG. 9  illustrates an eighth preferred embodiment of a gasket  710  according to this invention. Elements in this embodiment that are similar to elements in the previous embodiments will be similarly designated, but with 700 series numbers. The gasket  710  includes a first sealing portion  712  that is similar in shape to an O-ring, a second sealing portion  714  that is also similar in shape to an O-ring, and an elastic arm  716  extending between them. The elastic arm  716  can be integrally formed with the first and second sealing portions  712 ,  714 , or alternatively, it can be formed separately and then attached in a subsequent operation, such as a bonding operation. Each sealing portion  712 ,  714  fits into a corresponding recess  768 ,  770  in a first and second member  718 ,  720 , respectively. Each sealing portion  712 ,  714  is press fit into its corresponding recess  768 ,  770  in order to create the sealing and retention forces. Again, the compression forces are not created by compressing the first and second members  718 ,  720  together, allowing for vibrational decoupling between the two. 
     FIG. 10  illustrates a ninth preferred embodiment of a gasket  810  according to this invention. Elements in this embodiment that are similar to elements in the previous embodiments will be similarly designated, but with 800-series numbers. This embodiment is similar to the eight embodiment, except that the first and second sealing portions  812 ,  814  are rectangular shaped in cross section. Each sealing portion  812 ,  814  fits into a corresponding recess  868 ,  870 , in a first and second member  818 ,  820 , respectively. An elastic arm  816  extends between the two sealing portions  812 ,  814 . The elastic arm  816  will be slightly compressed during assembly in order to provide a sealing force for the first and second sealing portions  812 ,  814 , but is much less than fully compressed in order to maintain vibration isolation between the members  818 ,  820 . 
     FIG. 11  illustrates a tenth preferred embodiment of a gasket  910  according to this invention. Elements in this embodiment that are similar to elements in the previous embodiments will be similarly designated, but with 900-series numbers. The first and second sealing portions  912 ,  914  are essentially the same as in the ninth embodiment, but the elastic arm  916  is longer. 
     FIG. 12  illustrates an eleventh preferred embodiment of a gasket  1010  according to this invention. Elements in this embodiment that are similar to elements in the previous embodiments will be similarly designated, but with 1000-series numbers. A first sealing portion  1012  has a pair of sealing extensions  1026  that fit into a corresponding pair of recesses  1068  in the first member  1018 . A second sealing portion  1014  has a pair of sealing extensions  1032  that fit into a corresponding pair of recesses  1070 , with a membrane extending between the first and second sealing portions  1012 ,  1014 . This gasket  1010  also includes a permeation membrane  1074  secured to one surface of the gasket  1010 . Although not shown in the other embodiments, a permeation membrane can also be employed with those embodiments, if so desired. Each sealing portion  1012 ,  1014  can, as an alternative, include a stiffening flange, if so desired. Moreover, as an alternative, the permeation membrane  1074  can be located on the opposite surface of the gasket  1010 —depending upon which side of the seal is sealing against an aggressive fluid. 
   While certain embodiments of the present invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.