Abstract:
A baffle assembly for a hollow cavity is disclosed. The baffle assembly includes a labyrinth that defines a tortuous drain passageway. The baffle assembly includes a vertical portion that abuts an expandable material to reduce the transmission of noise and other vibrations.

Description:
BACKGROUND  
       [0001]     Various products have bodies or housings with hollow cavities therein. For example, automobiles, trucks and other vehicles, as well as some consumer appliances have hollow cavities formed between inner and outer panels that form their respective bodies or housings. In many instances, those cavities are sealed or sectioned off to prevent or minimize the transmission of noise therethrough. It is known to use an acoustic baffle to completely seal or partition portions of hollow cavities. These baffles effectively minimize noise transmission. However, sometimes, various fluids can accumulate in the hollow cavities. When that occurs it may be desirable in certain applications for the fluid to drain out of the hollow cavity so as to prevent or minimize the potential for corrosion or other undesirable effects of the trapped fluid. Many conventional acoustic baffles do not include a mechanism to allow trapped fluid to escape the hollow cavity through the baffle.  
         [0002]     The embodiments described herein were developed in light of these and other drawbacks associated with conventional acoustic baffles.  
       SUMMARY  
       [0003]     In one embodiment, a baffle assembly includes a substantially planar carrier having an upper surface and a lower surface, and a drain housing extending from said upper surface, wherein said drain housing includes a cavity interconnecting a fluid inlet and a fluid outlet, and a generally vertically oriented web portion that extends from an interior surface of the drain housing to define at least a portion of a drain path through said cavity.  
         [0004]     In a further embodiment, a drain housing for dissipating sound therein includes a generally vertically oriented planar web portion that extends from an interior surface of said drain housing to define at least a portion of a drain path through said drain housing, wherein said web portion defines two legs of said drain path, wherein said two legs of said drain path flow in opposite directions.  
         [0005]     In yet a further embodiment, a method of reducing noise propagation through a partially enclosed cavity includes positioning a baffle assembly in a desired location within the partially enclosed cavity, wherein said baffle assembly includes a fluid inlet, positioning an expandable material adjacent said baffle assembly, and expanding said expandable material such that said expandable material at least partially encloses said baffle assembly. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]     Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:  
         [0007]      FIG. 1  is a perspective view of an automobile body, illustrating various pillars within which an acoustic baffle apparatus incorporates a drain assembly in accordance with an embodiment of the present invention;  
         [0008]      FIG. 2  is a perspective view of an embodiment of a baffle assembly in accordance with the present invention;  
         [0009]      FIG. 3  is a sectional view taken along line  3 - 3  of  FIG. 2 , with the sealing material removed for clarity;  
         [0010]      FIG. 4  is a sectional view taken along line  4 - 4  of  FIG. 2 ;  
         [0011]      FIG. 5  is a sectional view similar to  FIG. 4 , illustrating the baffle assembly after the expansion of the expandable foam, with the foam slightly separated from the baffle assembly for clarity;  
         [0012]      FIG. 6  is an end view of the cut-away view of the baffle assembly according to  FIG. 5   
         [0013]      FIG. 7  is a phantom view of the baffle assembly of  FIG. 2 , illustrating the drain flow path.  
     
    
     DETAILED DESCRIPTION  
       [0014]     An automobile body  10  is illustrated in  FIG. 1 . The automobile body  10  has several interconnected, frame elements that define an engine compartment  12 , trunk  14 , doorways  16 , firewall  18 , wheel wells  20 , structural pillars  22 , and rocker panels  24 . Acoustic drains, or baffle assemblies,  28  are illustrated within pillars  22  and rocker panels  24 . Pillars  22  and rocker panels  24  are examples of hollow cavities in which the embodiments of the baffle assembly  28  described below can be used. Moreover, though the baffle assembly  28  is described herein in the context of an automobile, it is understood that the described baffle assembly  28  can also be used in connection with a variety of other articles of manufacture to generally seal or section off hollow cavities to minimize noise transmission, while at the same time permitting the passage of fluid.  
         [0015]     An exemplary baffle assembly  28  is shown in  FIGS. 2 through 7 . The baffle assembly  28  includes a support element  30 , a sealing material  32 , and a carrier portion  36 , which are configured to fit within a pillar, cavity, or other hollow space. The support element  30  is a portion of a vehicle body panel ( FIGS. 4-6 ) that provides a structural support for carrier portion  36 , as discussed below. As best seen in  FIG. 4 , the carrier portion  36  has an upper surface  38  and a lower surface  40 . The carrier portion  36  is shaped and sized to fit snugly between the panels that define the rocker panel  24  so as to substantially prevent sound from traveling through the hollow space past the carrier portion  36 . The carrier portion  36  may be made from a variety of materials, including hard plastic. The sealing material  32  is configured to cause the carrier portion  36  to adhere to and seal against the panels that define the hollow space and provide more sound dissipation, as discussed below.  
         [0016]     The baffle assembly  28  further includes a drain housing  42  configured to permit fluid to flow therethrough and past the baffle assembly  28 , while substantially preventing sound from traveling threrethrough. The drain housing  42  includes a top surface  44  with a fluid inlet  46  formed therein, a fluid outlet opening  48  adjacent the lower surface  40 , and a substantially hollow cavity, which is shown generally at  50  in  FIG. 3 .  
         [0017]     As seen more clearly in  FIGS. 3 through 7 , the drain housing  42  further includes staggered web portions  52  that perpendicularly extend from an interior surface  54  of the drain housing  42 . As such, the staggered web portions  52  seat against support element  30  and form the substantially hollow cavity  50  into a labyrinth that permits the flow of fluid therethrough. The cavity  50  forms a generally horizontal labyrinth drain path through drain housing  42 , which is illustrated in  FIG. 7  by an arrow, P. Drain path P is defined by segments L that are separated by web portions  52 . As such, a fluid (not shown) that enters the fluid inlet  46  may be diverted within the drain housing  42  and flow in the direction of the arrow, P, in a generally horizontal path to the opening  48 .  
         [0018]     With reference to  FIG. 4 , the carrier  36  may include a plurality of bosses  60  that are received by receiving-holes  62  formed in the sealing element  32 . Thus provided, carrier  36  secures sealing material  32  thereto during assembly of both baffle assembly  28  and automobile body  10 .  
         [0019]     As best seen in  FIG. 6 , the carrier  36  abuts an upper surface  66  of the support element  30  such that the fluid outlet opening  48  of the drain housing  42  permits fluid evacuation. Additionally, the drain housing  42  may be secured to the support element  30  by an adhesive or other suitable means.  
         [0020]     Referring specifically to  FIGS. 4 and 5 , the sealing material  32  is discussed in greater detail. A preselected thickness T of sealing material  32  is located over the upper surface  38  of the carrier  36 . As discussed below, sealing material  32  is expanded after installation of the baffle assembly  28  in body  10 .  FIG. 4  illustrates the sealing material  32  after installation in body  10  and before expansion of sealing material  32 . Sealing material  32  is illustrated in  FIG. 4  to include an upper surface  70 , and a lower surface  72 .  FIG. 5  illustrates the resulting expansion of sealing material  32  wherein sealing material  32  is defined, in part, by an expanded upper surface  74  that is separated from the lower surface  72  by a height H. The original thickness T and other properties of sealing material  32 , such as coefficient of expansion and baking temperature, are determined in order to provide a desired height H after expansion of sealing material  32 . As illustrated, a vertical distance is provided between the fluid inlet  46  and the lower surface  72  of sealing material  32 . In this manner, a vertical component of the drain housing  42  is provided such that the fluid inlet  46  will not be covered or clogged by the expansion of sealing material  32 .  
         [0021]     As can be seen in  FIG. 5 , moisture or liquids that collect in rocker panel  24  are directed to fluid inlet  46 . Liquids may flow directly to fluid inlet  46  as expanded upper surface  74  is in a generally horizontal orientation, or may be directed to fluid inlet  46  as the automobile is operated, resulting in a recurrent tilting of expanded upper surface  74  through a generally horizontal orientation. The connection between bosses  60  and sealing material  32  will not be eliminated by the expansion of sealing material  32 .  
         [0022]     The sealing material  32  is preferably die cut into a desired shape, and includes an upper surface  70  and an opposing, lower surface  72  that are separated by a thickness, T, of the sealing material  32 . The receiving-holes  62  are molded or otherwise formed in the sealing material  32 . The sealing material  32  is formed of a dry, initially non-tacky material that becomes tacky upon expansion so that the sealing material  32  adheres to the rocker panel  24  when the baffle assembly  28  is heated to the activation temperature at which the sealing material  32  expands as seen in  FIG. 5 . An exemplary sealing material is disclosed in U.S. Pat. No. 5,266,133, to Hanley et al., which is hereby incorporated by reference in its entirety. Such a material is marketed under the name SIKALASTOMER 240 by Sika Corporation of Lyndhurst, N.J.; however, any other suitable sealing material may be employed that is able to expand sufficiently upon activation to seal the hollow cavity within which the baffle assembly  28  is positioned.  
         [0023]     One necessary characteristic of the sealing material  32  is that the sealing material must possess an activation temperature lower than or equal to the temperature at which the automobile body is baked during manufacture. For example, it is conventional to employ a bake temperature of about 177 .degree. C. (350 .degree. F.) in the manufacture of automobiles. Accordingly, the preferred sealing material for use in the manufacture of automobiles must possess an activation temperature lower than this value, e.g. 149 .degree. C. (300 .degree. F.).  
         [0024]     Thus provided, sealing material  32  partially encloses drain housing  42  to form a tight fit of sealing material  32  adjacent the vertical outer surfaces of drain housing  42 . This enclosure of drain housing  42  reduces any resonate vibrations that the drain housing  42  may propagate through a pillar  22  or rocker panel  24 . In operation, vibrations that propagate upwards, due to vibrations in the automobile frame or the like, through a pillar  22  or rocker panel  24  reach the baffle assembly  28 . While the baffle assembly  28  may resonate with some of the frequencies of these vibrations, the sealing material  32  dissipates these vibrations by damping carrier  36 . The drain housing  42  may resonate with some of the frequencies of these vibrations, but the sealing material  32 , expanded to a tight fit with drain housing  42 , dampens the vibrations of drain housing  42 , thereby dissipating these frequencies. Any vibrations that enter fluid outlet opening  48  are reduced in magnitude as they follow drain path P by deflecting on the web portions  52  and other interior vertical surfaces of drain housing  42 . Again, any vibrations that may be induced into web portions  52  or drain housing  42  by vibrations that enter fluid outlet opening  48  are dissipated as described above with respect to drain housing  42 . An exemplary torturous path for sound dissipation is disclosed in U.S. Pat. No. 5,295,785, the disclosure of which is herein incorporated by reference in its entirety.  
         [0025]     The carrier  36  is formed of a material having a melting point that is higher than both the activation temperature of the sealing material  32  and the bake temperature to which the automobile body is to be exposed. Preferably, the temperature at which the material of the carrier  36  softens is also above the bake temperature. Thus, the carrier  36  is able to substantially maintain its shape before, during and after the baking operation, to support the  42  so that the sealing material  32  expands tightly fill a portion of the pillar  22  or rocker panel  24 .  
         [0026]     The carrier  36  is formed of a moldable material that is pliable so that special handling of the baffle assembly  28  is not required where applied bending forces would otherwise cause cracking or other permanent deformations. An exemplary material of the carrier  36  is a black, heat stabilized, lubricated 33% glass-reinforced 66-nylon having a heat deflection temperature at 1.8 MPa of 240 .degree. C. (464 .degree. F.), and a melting point of 262 .degree. C. (504 .degree. F.). Such a material is marketed as NYLIND 51HSL BK001 by DuPont. However, other similar materials may be used depending upon the desired physical characteristics thereof.  
         [0027]     The carrier  36  and drain housings  42  are preferably formed of a material having a melting point that is higher than both the activation temperature of the sealing material  32  and the bake temperature to which the automobile body is to be exposed. Preferably, the temperature at which the material of the drain housings  42  softens is also above the bake temperature. Thus, the drain housings  42  are able to substantially maintain their shape before, during and after the baking operation. As shown in  FIGS. 3-6 , the drain housings  42  and carrier  36  are preferably formed as a unitary piece of the same moldable material.  
         [0028]     Accordingly, during assembly of the automobile, the acoustic baffle assembly  28  is inserted into the pillar  22  of the automobile body  10  and remains in place during subsequent assembly operations. Any fluid that collects in the pillar  22  during assembly, washing, pre-preparation, or priming may be drained. When the automobile is subjected to a bake temperature, typically of about 177° C. (approximately 350° F.), the sealing material  32  is activated and expands as described herein and illustrated in  FIGS. 4 and 5 . Subsequent to manufacture, the acoustic baffle assembly  28  effectively serves as a baffle for muting sounds that would otherwise be transmitted through the pillar  22 . Concurrently, water or other fluids that encounter the baffle assembly  28  may be drained through the cavity  50 . As such, the baffle assembly  28  permits passage of fluids therethrough while presenting an acoustic baffle structure that mutes noise transmitted through the hollow cavities of body  10 . Thus, the baffle assembly  28  achieves two functions by allowing fluid drainage while functioning as a muting component.  
         [0029]     While the present invention has been particularly shown and described with reference to the foregoing preferred and alternative embodiments, it should be understood by those skilled in the art that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention without departing from the spirit and scope of the invention as defined in the following claims. It is intended that the following claims define the scope of the invention and that the method and apparatus within the scope of these claims and their equivalents be covered thereby. This description of the invention should be understood to include all novel and non-obvious combinations of elements described herein, and claims may be presented in this or a later application to any novel and non-obvious combination of these elements. The foregoing embodiments are illustrative, and no single feature or element is essential to all possible combinations that may be claimed in this or a later application. Where the claims recite “a” or “a first” element of the equivalent thereof, such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements.