Abstract:
A generally planar baffle is disclosed. The baffle has an expandable layer coupled to an adhesive layer. The expandable layer has on its external surface a pattern of projections and a pattern of voids relative to the projections, such that the projections define a first thickness of the expandable layer and the voids define a second thickness of the expandable layer, wherein the first thickness is greater than the second thickness.

Description:
BACKGROUND 
       [0001]    Manufactured products commonly have various orifices and cavities that result from the manufacturing process and/or that are designed into the product for various purposes, such as weight reduction. Motor vehicles, for example, include several such orifices and cavities throughout the vehicle, including in the vehicle&#39;s structural pillars and in the sheet metal of the vehicle doors. It is often necessary to seal such orifices and cavities so as to control noise, fumes, dirt, water and the like from passing from one area to another within the vehicle. 
         [0002]    Various baffles and seals have been used to seal orifices and cavities in manufactured products, such as motor vehicles. One known baffle used for such purposes is illustrated in  FIGS. 1 and 2 . The baffle  10  is a generally-planar two-layer baffle, including an expandable layer  12  and an adhesive layer  14 . The baffle  10  is commonly manufactured using an extrusion process. The outer surfaces of the expandable layer  12  and the adhesive layer  14  are substantially smooth. The expandable layer  12  is comprised of material that expands upon being activated, typically by the application of elevated heat for a particular duration of time. For example, expandable materials used on baffles found in automotive vehicles are generally formulated to expand in response to the amount of heat and duration of time found in typical e-coat ovens used by automotive vehicle manufacturers. Upon activation (by application of heat or otherwise), the expandable material expands to fill and seal the orifice or cavity. 
         [0003]    The thickness of the pre-activated expandable material  12  may vary depending on the particular application. As the thickness of the expandable material increases, though, the performance of the baffle  10  may decrease because the interior portion of the expandable material is not exposed to the same temperature level for the same amount of time as the outer portions of the expandable material. In effect, the expandable material “self-insulates,” such that the inner portions of the expandable material may not expand as fully or as quickly as the outer portions of the expandable material. The inventors hereof have developed a new baffle with improved performance characteristics. 
       SUMMARY 
       [0004]    A generally planar baffle is disclosed. The baffle has an expandable layer coupled to an adhesive layer. The expandable layer has on its external surface a pattern of projections and a pattern of voids relative to the projections, such that the projections define a first thickness of the expandable layer and the voids define a second thickness of the expandable layer, wherein the first thickness is greater than the second thickness. The shape and configuration of the projections and voids may take different forms. In certain embodiments, the pattern of projections is a plurality of ridges and the pattern of voids is a plurality of voids relative to the ridges. 
         [0005]    Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0006]    The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
           [0007]      FIG. 1  illustrates a perspective view of known baffle. 
           [0008]      FIG. 2  illustrates a side view of the known baffle illustrated in  FIG. 1 . 
           [0009]      FIG. 3  illustrates a perspective view of an improved baffle according to a first embodiment. 
           [0010]      FIG. 4  illustrates a side view of the improved baffle illustrated in  FIG. 3 . 
           [0011]      FIG. 5  illustrates a perspective view of a second embodiment of an improved baffle. 
           [0012]      FIG. 6  illustrates a perspective view of a third embodiment of an improved baffle. 
       
    
    
       [0013]    Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0014]    Disclosed herein is an improved baffle, which demonstrates better performance and uses less material than known baffles used for similar applications. The improved baffle includes two layers, an expandable layer and an adhesive layer. The expandable layer includes on its outer surface a pattern of projections, such as ridges, and a pattern of voids relative to the projections, such as grooves or channels. The voids, e.g., grooves or channels, allow the applied heat to better penetrate into the interior portion of the expandable layer, which improves the expansion of the interior portion of the expandable layer. Additionally, the voids in the expandable layer reduce the amount of expandable material required in the baffle, which improves the cost-effectiveness of the product. 
         [0015]      FIGS. 3 and 4  illustrate one embodiment of the improved baffle.  FIG. 3  is a perspective view of the improved baffle  100 , which includes an expandable layer  105  and an adhesive layer  130 . The adhesive layer  130  is used to secure the baffle  100  in place in the manufactured product during the manufacturing process and prior to being activated and expanded. The expandable layer  105  is configured to expand in response to being activated, such as by application of a particular elevated temperature for a particular duration, and thereby seal an orifice or cavity. The orifice or cavity is typically defined by sheet metal or other panels, such as those found in automotive vehicles. 
         [0016]    The expandable layer has an interior portion  107  and an external surface  109 . The external surface  109  comprises multiple levels formed from a combination of voids and projections of the expandable layer  105 . The voids are illustrated in  FIGS. 3 and 4  as grooves or channels  110 . The projections are illustrated in  FIGS. 3 and 4  as ridges  120 , which alternate with and complement the grooves/channels  110 . As a result of the void/projection configuration—illustrated in  FIGS. 3 and 4  as grooves/channels  110  and ridges  120 —the expandable layer  105  has a primary thickness  140  defined by the thickness of ridges  120 , and the expandable layer  105  has a secondary thickness  150  defined by the thickness of the expandable layer  105  at the locations of the grooves/channels  110 . The primary thickness  150  is determined for the intended application, and, for example, may be 5 mm or 3.3 mm in certain applications. In one embodiment, the secondary thickness  150  is approximately one half of the primary thickness  140 . The expandable layer  105  and the adhesive layer  130  may be manufactured by extruding. 
         [0017]    The expandable layer may be formed from various expandable materials known to be useful for baffle and sealing applications. One example of a suitable expandable material is a heat-activated foam, such as the heat-activated foam sold by Sika Corporation of Madison Heights, Mich. under the name SIKABAFFLE® and described in the following U.S. Patents, all of which are incorporated herein by reference: U.S. Pat. Nos. 5,266,133; 5,373,027; 6,150,428; 6,368,438; and 6,387,470. Other expandable materials may also be used. The adhesive layer  130  may comprise any known adhesive suitable for securing a baffle in place prior to activation. 
         [0018]    The grooves/channels  110  in  FIGS. 3 and 4  permit activating heat applied to the baffle  100  to more quickly and effectively penetrate into the interior portion  107  of the expandable layer  105 , which results in more effective and efficient expansion. Further, the inclusion of the grooves/channels  110 —or any other types of voids in the expandable layer  105 —results in less expandable material being used in the baffle  100 . The reduction in expandable material makes the baffle less costly and lighter. 
         [0019]    The two levels in the expandable layer  105  may be created with many different shapes and configurations other than the grooves/channels and ridges illustrated in  FIGS. 3 and 4 .  FIG. 5  illustrates a baffle  500  wherein the projections and voids are created by a pattern of cylinders  510  (instead of ridges) that extend outward from the interior portion  520  of the expandable layer.  FIG. 6  illustrates a baffle  600  wherein the projections and voids are created by a pattern of complementary squares  610  that extend outward from the interior portion  620  of the expandable layer. Various other shapes and configurations of the projections and voids may be employed to create two levels on the exterior surface of the expandable layer. 
         [0020]    The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure. 
         [0021]    Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
         [0022]    The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.