Abstract:
A vehicle body panel having an outer skin and an inner skin. The inner skin and outer skin are connected by an intermediate spacer. A urethane foam is provided between the intermediate spacer and each of the inner and outer skins.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an engine hood assembly and, more particularly, to a body panel having an inner and outer skin interconnected by a light weight spacer in order to provide sufficient structural support to the body panel. 
     2. Discussion 
     Present automotive vehicle body panels typically include inner and outer skins each stamped of a sheet metal. The outer skin provides a decorative appearance to the vehicle, while the inner skin provides additional structural support. Typically, the inner and outer skins are interconnected by hemming the outer skin over the edges of the inner skin, thereby forming a unitary vehicle body panel. Although such body panel construction has been utilized for an extensive period, automotive designers continuously strive to reduce vehicle weight and cost and to improve the structural capabilities of the body panels. 
     Thus, it is an object of the present invention to provide a vehicle body panel which reduces the weight of a comparably sized conventional body panel. 
     It is a further object of the present invention to provide a body panel having an outer skin formed of a metal or composite material interconnected to an inner skin formed of a thin, flexible material, where the inner and outer skins are joined by a honeycombed spacer. 
     SUMMARY OF THE INVENTION 
     This invention is directed to a body panel for a vehicle. The body panel includes an outer skin and an inner skin. A structural spacer interconnects the inner and the outer skins and is bonded to both the inner skin and the outer skin. The structural spacer is formed of a material which is lighter in weight than both the inner and the outer skins. A foam bonding material is interposed between the structural spacer and the inner and outer skins. The foam bonding material bonds the structural spacer to the inner and outer skins. 
     These and other advantages and features of the present invention will become readily apparent from the following detailed description, claims and drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawings, which form an integral part of the specification. are to be read in conjunction therewith, and like reference numerals are employed to designate identical components in the various views: 
     FIG. 1 is a perspective view of a portion of a vehicle and hood arranged in accordance with the principles of the present invention; 
     FIG. 2 is a cross-sectional view through line  2 — 2  of FIG. 1; 
     FIG. 3 is an exploded view of the interconnection between a hinge pivot bracket and the outer skin of the body panel; 
     FIG. 4 is a cross-sectional view of the interconnection between the latch bracket and the outer skin; 
     FIG. 5 is a cross-sectional view of an exemplary configuration for the flange portion of the hood; 
     FIG. 6 is a perspective view of the outer skin configured in a first embodiment for regaining the latch bracket; 
     FIG. 7 is a perspective view of the outer skin configured in a second embodiment for retaining the latch bracket; and 
     FIG. 8 is a perspective view of a third embodiment of the flange for retaining the latch bracket. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to FIGS. 1-8, the engine hood assembly  10  will be described. The engine hood assembly  10  will be described as an exemplary configuration for any of a number of vehicle body panels, include a deck lid, roof front and rear fenders, and vehicle doors. Engine hood assembly  10  attaches to a vehicle  12  via a hinge assembly  14 . The hinge assembly  14  enables the engine hood assembly  10  to pivot between an open position, as shown in FIG. 1, and a closed position. A tie-down latch assembly  16  retains engine hood assembly  10  in a generally closed position, and release of a latch mechanism enables engine hood assembly  10  to pivot to an open position 
     FIG. 2 depicts a cross-sectional view of a portion of engine hood assembly  10 . Engine hood assembly  10  comprises a multi layer structure including an outer skin  18  and an inner skin  20 . Outer skin  18  and inner skin  20  are interconnected by an intermediate layer or intermediate spacer  22 . A bonding medium  24  is introduced between outer skill  18  and intermediate layer  22 . Similarly, a bonding medium  24  is introduced between inner skin  20  and intermediate layer  22 . FIG. 2 also depicts an exemplary poise button  26  which is inserted between inner skin  20  and intermediate layer  22  and bonded in position via bonding medium  24 . Poise button  26  disperses an applied load across a greater surface area of intermediate layer  22 , thereby providing greater support to place the hood in a poised position. 
     Preferably, outer skin  18  is formed of a metal of a preferred thickness of 0.7 to 1.0 mm or composite material having 2.0 to 3.0 mm thickness, such as through injection molding. Inner skin  20  is preferably formed of a thin sheet of flexible material such as sheet stock, aluminum or steel stamping, foil stock of between 0.005″ to 0.018″ thickness, or plastic injection molding. Poise button  26  is formed of aluminum material having a thickness between 0.040″ and 0.060″. Intermediate layer  22  is preferably a one inch phenolic impregnated paper spacer having a honeycomb structure, but may be a plastic or metal material (honeycomb). Intermediate layer  22  preferably is formed to provide adequate structural support to engine hood assembly  10 , for resisting denting or other deformation under load. Bonding medium  24  preferably is a polyurethane foam material. 
     During assembly of engine hood assembly  10 , bonding medium  24  is sprayed on both interior surfaces of outer skin  18  and inner skin  20 . Outer skin  18 , inner skin  20 , and intermediate layer  22  are then placed in a fixture for assembly. The polyurethane foam free rises into the paper honeycomb to fuse and secure the phenolic impregnated paper honeycomb or other plastic or metal materials to both the inner surfaces of outer skin  18  and inner skin  20 . Further, use of free rise urethane foam provides a dead air space which functions as an insulator for engine hood assembly  10 . 
     FIG. 3 depicts an interconnection between outer skin  18  and a hinge bracket  28  of hinge assembly  14 . Hinge bracket  28  interconnects directly to the inner surface of outer skin  18  via an adhesive layer  30 . A locating line or rib  32  may be formed on the inner surface of outer skin  18  to facilitate positioning of hinge bracket  28 . Preferably hinge bracket  28  is formed of an extruded aluminum material and includes a pivot hole  34  which enables hinge bracket  28  to pivot about the pivot point for engine hood assembly  10 . 
     FIG. 4 depicts a cross-sectional view of an interconnection between tie down bracket  36  of hinge assembly  14  and outer skin  18 . Tie down bracket  36  and outer skin  18  are preferably interconnected using an adhesive bond  38 . Preferably, one or a plurality of ribs  40  are formed on an inner surface of outer skin  18 . The ribs  40  provide separation between tie down bracket  36  and the surface of outer skin  18  in order to prevent the adhesive material forming adhesive bond  38  from being squeezed out from between tie down bracket  36  and outer skin  18 . Preferably, tie down bracket  36  is a die cast piece or steel stamping. 
     As best seen in FIGS. 2 and 4, outer skin  18  includes a flange  44  which projects generally downward from outer skin  18 . Flange  44  includes a hole  46  which receives a stud  48  projecting from tie down bracket  36 . Stud  48  prevents a peal type breakdown of the adhesive bond. Alternatively, a fastener  49  can be employed alternatively or in conjunction with stud  48  to prevent such breakdown. As best seen in FIG. 5, flange  44  may be formed thicker in proximity to a center line  50  of the vehicle in order to augment the retaining force of hole  46 . For example, flange  44  may taper from 0.050″ along the center line to 0.030″ at its end. 
     FIG. 6 depicts a second configuration for outer skin  18  and flange  44  to receive a tie down bracket  36 . Flange  44  is formed with an undercut  52  which provides a channel for receiving tie down bracket  36 . As shown in FIG. 7, flange  44  of outer skin  18  may include a rectangular undercut  54 . Alternatively, undercut  54  may be formed in a circular manner. As best seen in FIG. 8, flange  44  in outer skin  18  may include a circular through hole  56 . 
     It should be noted that tie down bracket  36  must be configured so that stud  48  aligns with the respective undercuts and holes described in FIGS. 6-8. It should also be noted that in FIGS. 6-8, flange  44  has a thickness greater than the decorative portion of outer skin  18 . 
     In view of the foregoing, one skilled in the art will recognize that the engine hood assembly  10  described herein meets the objects of the subject invention. In particular, engine hood assembly defines a body panel which is light in weight, but provides sufficient structural support required of body panels. Further, engine hood assembly  10  provides greater vehicle insulation, both thermal and acoustical, for the vehicle. 
     While specific embodiments have been shown and described in detail to illustrate the principles of the present invention, it will be understood that the invention may be embodied otherwise without departing from such principles. For example, one skilled in the art will readily recognize from such discussion and from the accompanying drawings and claims that various changes, modifications and variations can be made therein without departing from the spirit and scope of the invention as described in the following claims.