Abstract:
A vehicle interior assembly includes a class A visible surface material having a first layer formed from a thermal plastic olefin and a second layer formed from a foam. The vehicle interior assembly also includes a substrate supporting the class A visible surface material. The substrate defines an opening for receiving a drop-in chute having an outer surface. In addition, the vehicle interior assembly includes a retention mechanism for securing the outer surface of the drop-in chute to the substrate.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This U.S. National Stage Patent Application claims the benefit of International Patent Application Serial No. PCT/US2011/036015 filed May 11, 2011, entitled “Vehicle Interior Assembly” which claims the benefit of U.S. Provisional Patent Application Ser. No. 61/333,534 filed May 11, 2010, entitled “Vehicle Interior Assembly,” the entire disclosure of these applications being considered part of the disclosure of this application, and hereby incorporated by reference. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention is directed to a vehicle interior assembly and more specifically to a vehicle interior assembly that includes airbags and a method of forming thereof. 
     2. Related Art 
     As more and more manufacturers strive to enhance the interior design of vehicles to differentiate their products, one such differentiation has been the removal of visible airbag seams from the vehicle interior assemblies such as the dashboard. Manufacturers have been trying to produce a class A interior surfaces on vehicle dashboards that is free of visible airbag lines, seams or any other markers that denotes the location of the airbag. Even though the class A surface may originally be formed without seams, many times unintentional seams around the drop-in chute including a cover over the airbag assembly result over time. 
     To eliminate many of these previously intended seams as well as unintended visible seams in soft instrument panels, manufacturers have developed two basic techniques. The first technique is to place the drop-in chute into an opening in the substrate of the vehicle interior assembly and then apply urethane foam between the assembly and the class A visible skin. One cause of unintended lines on the class A surface is the movement of the cover relative to the substrate, and these lines typically occur unless at least 6 mm foam-in-place skin on a class A surface is provided. The second method is to securely and permanently affix a cover over the airbag from movement relative to the substrate before applying a thinner class A surface. In the second method the cover is typically securely vibration welded or adhered to the substrate, and then a less than 5 mm by bilaminate material may be applied. 
     Each of the above methods provides a suitable method for ensuring against unintended lines or other visible markers showing where the airbag cover of the drop-in chute is located relative to the substrate. However, each of the above methods is relatively expensive and time consuming. More specifically, in the first method, the typical 6-8 mm foam-in-place class A surface requires additional material as well as the foam-in-place process. In regards to the second method, it requires a vibration weld process or other method of bonding or adhering the drop-in chute semi-permanently to the substrate. These vibration weldings as well as adhesion or bonding processes are time consuming and raise the manufacturing costs of the end assembly. 
     In view of the above, Applicants have developed a more cost-effective manufacturing process that uses less material and reduces the manufacturing time. 
     SUMMARY 
     The present invention is directed to a vehicle interior assembly and more specifically to a vehicle interior assembly that includes airbags and a method of forming thereof. 
     The present invention is configured to use a drop-in chute that while substantially affixed to the substrate is not permanently affixed against movement of the drop-in chute relative to the substrate until the airbag intentionally ruptures the drop-in chute. In addition, the present invention uses a 5 mm or less bilaminate material as the class A surface. To further improve assembly and manufacturing process, the drop-in chute is formed using a retention assembly that locks the drop-in chute relative to the substrate. The retention assembly is configured to minimize movement of the drop-in chute relative to the substrate. Through careful selection of the retention assembly as well as the bilaminate material and the thickness of the bilaminate material, the visibility of unintended lines at seams illustrating the location of the drop-in chute on the class A surface is minimized. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various exemplary embodiments of the systems and methods according to the present disclosure will be described in detail, with reference to the following figures, wherein: 
         FIG. 1  illustrates a partial cross-sectional view of a prior art interior assembly having a drop-in chute that is vibration welded to the substrate; 
         FIG. 2  is an enlarged cross-sectional view of the weld joint in  FIG. 1 ; 
         FIG. 3  is an enlarged cross section of a tear seam; 
         FIG. 4  is a different view of the tear seam in  FIG. 3 , along lines A-A; 
         FIG. 5  is a cross-sectional view of an anti-lift edge nib design; 
         FIG. 6  is an enlarged cross-sectional view of the anti-lift edge nibs in  FIG. 5 , along lines B-B; 
         FIG. 7  is an enlarged cross-sectional view of an edge lock design; 
         FIG. 8  is an enlarged cross-sectional view of a stake design; 
         FIG. 9  is a cross-sectional view showing the sequence of deployment of the airbag; 
         FIG. 10  is a picture of an exemplary interior assembly showing issues with the outline of the drop-in chute visible on the class A surface; 
         FIG. 11  is a picture of a cross section of the drop-in chute; 
         FIG. 12  is a picture of an exemplary interior assembly showing reduced markings of the location of the drop-in chute on the class A surface as compared to  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION 
     The present invention is directed generally to an interior assembly  10  having a substrate  20  forming an opening into which a drop-in chute  40  is placed. The drop-in chute retention assembly  50  positions and holds in place the drop-in chute  40 . 
     The substrate  20  may be any interior substrate such as a vehicle dashboard, door panels and the like. The substrate may be formed out of any known material that is used for dashboards or other desired panels and surfaces. The substrate  20  provides basic structural support for the dashboard or other vehicle interior component. Other structural members may attach the vehicle interior assembly  10  particularly the substrate  20  to the body of the vehicle and are not illustrated herein. The substrate  20  may also form other interior components of the vehicle as the base such as for interior door panels, side panels, and any other place in the vehicle where it is desirable to have a cover over an airbag assembly. 
     The substrate  20  generally includes an opening  24  to receive the drop-in chute  40 . The opening  24  includes an opening perimeter  26  and a support area  22  configured such that the drop-in chute  40  overlaps a portion of the substrate  20 . The opening  24  may be configured in any desired size and shape so long as it releases the airbag easily and repeatably as desired and in the direction desired. The support area  22  may vary depending upon the selected retention assembly  50 . The profile of the support area  22  between the upper surface  28  of the substrate  20  and the opening perimeter  26  is discussed in more detail below in relation to the retention assembly  50 . 
     The drop-in chute  40  may be formed in a variety of desired sizes, shapes and styles. The drop-in chute  40  may be configured to have one side release in a hinge fashion, split in the center or any other method that allows the airbag assembly  60  to deploy safely through or around the drop-in chute  40 . The drop-in chute  40  may be formed out of a single molded piece. The drop-in chute  40  generally includes an outer surface  44  which engages the class A surface material  12  that extends over the drop-in chute  40 . The drop-in chute  40  also includes an outer perimeter  42  and is in the relative proximity to the outer perimeter  42  which has an outer profile  48  that is configured to match or to gauge the profile of the substrate  20  relative to the opening  24 . The drop-in chute  40  is generally made out of similar materials to the substrate  20  but may be made out of any other desirable materials. The drop-in chute  40  may have a tear seam  49  to allow for easy release. The gap between the substrate  20  and drop-in chute around the perimeter of the drop-in chute  40  is generally a distance less than 1.2 mm. 
     The airbag assembly  60  may be any desirable airbag assembly, configured to fit within the selected location. The airbag assembly  60  generally includes an airbag canister  62  which holds the charge for activating the airbag  64 . The airbag assembly  60  may be varied in desired size, shape and configuration dependent upon the location of the vehicle, type of vehicle and desired size. For example, the configuration of the airbag assembly  60  may vary greatly depending upon whether it is a passenger side airbag located in the front dashboard, driver side airbag in the steering wheel, or a side impact airbag located in a rear door panel. The airbag assembly  60  is assembled into the drop-in chute. 
     As illustrated in  FIGS. 5-8 , the drop-in chute  40  and substrate  20  may include a retention assembly  50 . The retention assembly  50  may vary in size, shape and style configuration; however, the retention assembly must substantially constrain the drop-in chute  40  from moving relative to the substrate  20 . An edge lock design is illustrated in  FIG. 7 , which is easy to manufacture and allows for efficient repeatable deployment of the airbag. During the assembly operation, the drop-in chute  40  is simply press fit into the opening  24  on the substrate  20 . During deployment, the drop-in chute  40  tears along the tear seam  49  and bends at hinge line  61  during a deployment to provide a door through which air bag  24  is deployed. The edges of either the substrate opening or drop-in chute outer perimeter  42  may be applied with a light adhesive or bonding material and then quickly pressed into place to further minimize relative movement between the drop-in chute  40  and the substrate  20 . An approximately 6 mm or less, preferably 5.5 mm bilaminate material may be applied over the outer surfaces  28 ,  48  of the substrate  20  and drop-in chute  40 , respectively. As illustrated in  FIGS. 5-6 , a variation of the edge lock, described as anti-lift edge nibs  31  inserted into cavities  33  on the substrate  20  may also be used. A caulk also may be used as the retention mechanism. The substrate may also be melted to the drop-in chute. 
     As illustrated in  FIG. 8 , a plurality of heat stakes  56  may be used as part of the retention assembly  50 . The heat stakes  56  generally fit into a cavity  52  or opening to securely locate drop-in chute  40  relative to the substrate  20 . To enhance the retention of the drop-in chute  40  as well as reduce the amount of movement of the drop-in chute  40  relative to the substrate, the number of heat stakes  56  may be increased as desired. The heat stakes  56  may be formed in any desired size, shape or configuration as well as being formed out of different materials than the drop-in chute  40 . For example, the stake  56  may be formed in a mushroom shape, multi-prong or any other desired style that allows for easy insertion into the opening  52  and then retention relative to the substrate thereby minimizing movement of the drop-in chute  40  relative to the substrate. 
     The class A surface  12  is formed from a 6 mm or less, preferably a 5.5 mm or less, or more preferably a 5 mm or less, bilaminate material. The bilaminate is normally formed from a thermal plastics olefin as the visible surface with a layer of polypropylene or expanded polypropylene foam. Vinyl or polyurethane may be used also typically in combination with this foam or polyurethane with this foam. The substrate  20  is normally polypropylene or thermal plastics olefin, but also could be made of any suitable plastic. The drop-in chute  40  is normally high rubber content thermal plastics olefin. A trilaminate may also be used in place of the bilaminate film. The bilaminate or trilaminate material is not scored. The foam used generally has a density of about 32 kg/m 3 -72.1 kg/m 3 , preferable 40 kg/m 3 -64.1 kg/m 3 . 
     The foregoing invention has been described in accordance with the relevant legal standards, thus the description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiment may become apparent to those skilled in the art and fall within the scope of the invention.