Abstract:
A substantially acoustically transparent speaker grille is bonded or molded to a rear shelf panel located between the cabin and trunk of a vehicle. The grille is pressed into and laminated between a pair of resin impregnated sheets of fibrous material during a hot press molding operation. The grille and shelf panel is overlaid with a layer of covering fabric so as to present a smooth aesthetic appearance within the vehicle cabin.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates in general to a mounting arrangement for vehicle speakers and in particular to such an arrangement having one or more wire mesh grilles insert molded over a speaker aperture formed in a rear trim panel. 
     2. Description of Prior Developments 
     Numerous mounting arrangements have been used to secure a speaker to the rear trim panel located between the trunk and passenger compartment of a vehicle. Trim panels are typically formed of a sound deadening material in order to minimize the transmission of road noise from the trunk or rear portion of a vehicle into the vehicle interior. 
     This sound absorbing material presents a problem when a speaker is mounted to or adjacent the underside of the trim panel. In some cases the trim panel is perforated in the area of the speaker to allow for the transmission of sound. In other cases, a single aperture is formed through the trim panel and separate mounting hardware including perforated covers and grilles is provided to allow for sound transmission. 
     Although these prior designs function adequately, the perforated trim panel tends to absorb a significant amount of the speaker&#39;s output and the separate mounting hardware can be unsightly as it protrudes above the plane of the trim panel. 
     What is needed is a rear shelf trim panel which provides a substantially acoustically transparent surface for accommodating a vehicle speaker and which allows for a smooth planar rear shelf surface which is unbroken by any unsightly speaker mounting hardware. Another need exists for such as a trim panel which provides adequate support to a surface covering material such as a fabric or sheet covering applied over the surface of the panel facing the vehicle interior. 
     SUMMARY OF THE INVENTION 
     The present invention has been developed to fulfill the needs noted above and therefore has as an object the provision of a rear shelf trim panel for an auto or truck cabin which provides a virtually acoustically transparent speaker grille structure and which supports a shelf covering fabric without any visible grille or mounting hardware. 
     These and other objects are met by the present invention which is directed to a rear shelf trim panel having one or more wire mesh grilles bonded, molded or insert molded into a fibrous semi-rigid fabric material. The wire grille, which can take the form of a standard metal screen have ½ inch openings, is virtually acoustically transparent. No sound absorbing panel material is present between the speaker and the vehicle cabin. In accordance with the invention, the speaker or speakers are not mounted to the trim panel, but rather are mounted to a metal shelf on the vehicle body, which supports and underlies the trim panel. The bonded or insert molded grilles are aligned directly over and slightly separated from the speakers. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a perspective view of a rear shelf trim panel having insert molded speaker grilles constructed in accordance with the invention; 
     FIG. 2A is a view in section taken through section line  2 — 2  of FIG. 1 showing the relative alignment of the grille with a car stereo speaker; 
     FIG. 2B is an enlarged view of the heat bonded portion of FIG. 2A; 
     FIG. 3 is a schematic exploded view of the trim panel components of FIG. 1 before molding; 
     FIG. 4 is a view of the trim panel components of FIG. 3 being molded together; 
     FIG. 5 is a fragmental view of another embodiment of the invention showing a wire grille bonded to the underside of a trim panel with a bead of adhesive glue; and 
     FIG. 6 is a fragmental view of a speaker grille formed by perforating a fibrous trim panel according to the prior art. 
     In the various figures of the drawings, like reference characters designate like or similar parts. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will now be described in conjunction with the drawings, beginning with FIG. 1,  2 A, and  2 B which show a substantially planar rear shelf trim panel  10  constructed in accordance with the invention. Panel  10  is typically located between the rear seat and rear window of a vehicle and extends generally horizontally over the rear trunk compartment. 
     At least one and typically two or more speaker apertures  12  are formed in a planar portion of the panel  10  to allow for the passage of speaker sound. As seen in FIGS. 2A,  2 B and  3 , an open-weave fibrous or flocked cover material  14  is adhesively bonded to the upper surface of the trim panel  10  to provide a continuous smooth surface over the panel and speaker  15 . Cover material  14  efficiently passes sound waves yet provides an attractive surface on the interior of a vehicle. 
     As further seen in FIGS. 1,  2 A, and  2 B, a screen or mesh  16  is bonded or molded to the panel around the periphery of each aperture  12 . Screen  16  may be formed from wire screen material, such as thin wire mesh having ½ inch square openings. Of course, other mesh sizes may be used. 
     The main function of screen  16  is to support the generally limp cover material  14  overlying the apertures  12 . This keeps the cover material flat and smooth and provides support for any articles placed on the upper surface of the trim panel  10 . As shown in FIG. 2A, speaker  15  is bolted to a metal shelf  19  underlying panel  10  and aligned with each aperture  12 . 
     Although the wire screen  16  may be bonded to the underside of the trim panel  10  with an adhesive such as a hot melt glue as shown in FIG. 5, it has been found preferable to insert mold the wire screen  16  directly into the trim panel. As seen in FIG. 3, two sheets of trim panel material  18  are aligned with one another such that apertures  12  are superimposed one over the other. 
     A wire screen  16  is aligned between each pair of superimposed apertures  12  and placed in a hot mold press  20  as shown in FIG.  4 . The panel material  18  is preferably formed of a fibrous material known as “shoddy” which is produced from shredded cloth rags. The shoddy is preferably impregnated with heat-activated adhesive or glue, which when heated in a mold or the like, bonds to itself and other objects. Such bonding also adds rigidity to the shoddy. 
     When the hot mold press  20  of FIG. 4 compresses and heats the two layers of shoddy material  18 , the wire screens  16  are encapsulated and sandwiched between the layers. The adhesive within the shoddy material securely and permanently bonds the screens  16  to the trim panel  10 . The adhesive also bonds the two layers of shoddy material to one another along bond line  22  and rigidifies the resulting laminated panel assembly. 
     It should be noted that it is possible to eliminate the upper layer of shoddy material in FIG.  3  and simply press and bond the screens  16  into the single bottom layer of shoddy material  18  in the same manner as shown in FIG.  4 . In general, two layers of shoddy are preferred to provide increased sound isolation to the vehicle cabin and increased strength and rigidity to the trim panel  10 . 
     The pressure applied by the mold press  20  should be sufficient to extrude the shoddy material  18  around the edges of the wire mesh  16  where the shoddy material and wire mesh overlap so that the closed height of mold press  20  over and adjacent to screens  16  is about equal to the diameter of the metal wire rods forming the wire screens  16 . Thus, the finished molded panel  10  has a reduced thickness about equal to the diameter of the wires in the wire screens around the peripheral area  24  surrounding each aperture  12 . 
     As noted above, a bead of adhesive  26 , as shown in FIG. 5, may be used to bond each screen  16  to the underside of panel  10  around the border  24  of each aperture  12 . Alternatively, adhesive tape or other fasteners such as staples may be used to secure the screens directly to the panel  10 . 
     A comparison of the open substantially unobstructed speaker grille provided in the panel of FIG. 5 with the acoustically obstructed prior art panel of FIG. 6 emphasizes the improvement in speaker sound quality achievable with the present invention. In the grille of FIG. 6, a pattern of holes or perforations is formed directly through the shoddy panel material per se such that the sound absorbing shoddy panel material remaining between the perforations absorbs and distorts the speaker sound. A particular drawback to this prior art approach is the sound distortion produced by loose threads  30  projecting into the perforations from the surrounding shoddy material. The present invention obviates such loose threads. 
     It should be understood that while this invention has been discussed in connection with one particular example, those skilled in the art will appreciate that other modifications can be made without departing from the spirit of this invention after studying the specification, drawings, and the following claims.