Abstract:
The present invention is directed to a seamless airbag door assembly for a motor vehicle. A panel having an inner surface and an outer surface. The inner surface of the panel has predetermined breaking lines that are not visible when the panel is viewed from the outside surface. A scrim is connected to the inner surface of the panel and has a cut-line operable aligned with the predetermined breaking lines of the inner surface of the panel. An airbag chute is connected to the scrim and inner surface of the panel in order to connected the airbag chute to the panel.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/779,529, filed Mar. 6, 2006. The disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to the use of a metal scrim on a passenger airbag door panel on the interior of an automobile. 
       BACKGROUND OF THE INVENTION 
       [0003]    Airbags are a common safety device used in automobiles to prevent injury to the vehicle passengers when an accident occurs. Typically, airbags are integrated into the steering wheel or the dashboard and deploy when the vehicle is in a collision; if the vehicle is hit head-on, the momentum of the driver and passenger will be absorbed by the airbag, and the driver and passenger will avoid hitting the steering wheel and dashboard, respectively. 
         [0004]    As technology has developed, airbags are also being used in other areas of the vehicle besides the steering wheel and dashboard. It has become commonplace for airbags to be used in door panels and overhead panels in the interior of the vehicle. 
         [0005]    When the airbag is installed in the vehicle, it is placed in an area that will provide a minimal amount of interference with the use of the vehicle because the airbag is only necessary when there is a collision. It is common for aesthetic reasons for the airbag to be covered by a panel that follows a similar contour to, for example, the rest of the instrument panel of the vehicle and is similar in color. The modern trend with airbags is to have a seamless panel covering the airbag so as to disguise the location of the airbag completely. The airbag is typically located in a chute, and a door behind the panel aids in holding the airbag in place. It is important to prevent any panels or breakaway structures from being propelled toward the driver or passengers when deployed. 
         [0006]    The processes of either the heat-staking or vibration welding are expensive, both in capital and required labor costs. Accordingly, there exists a need for an improved assembly of a plastic airbag door in an instrument panel. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention is directed to a seamless airbag door assembly for a motor vehicle. A panel having an inner surface and an outer surface. The inner surface of the panel has predetermined breaking lines that are not visible when the panel is viewed from the outside surface. A scrim is connected to the inner surface of the panel and has a cut-line operable aligned with the predetermined breaking lines of the inner surface of the panel. An airbag chute is connected to the scrim and inner surface of the panel in order to connected the airbag chute to the panel. 
         [0008]    Upon deployment of an airbag through the airbag chute, the panel ruptures along the predetermined breaking lines, and the door assembly opens outward away from the panel along with the ruptured portion of the panel and the area of the scrim connected to the door. 
         [0009]    The scrim acts as a hinge to prevent the door assembly and the ruptured portion of the panel from detaching from rest of the panel. 
         [0010]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0012]      FIG. 1  is a sectional side view of a seamless passenger airbag door, according to the present invention; 
           [0013]      FIG. 2  is a plan view of the back side of a seamless passenger airbag door according to the present invention; and 
           [0014]      FIG. 3  is a front view of a scrim having a pre-cut breaking line, according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0015]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
         [0016]    A seamless passenger airbag door assembly  10  in the interior of an automobile is generally shown in  FIGS. 1 and 2 . A panel  12  has an exterior surface  14  and an interior surface  16 . The panel  12  can be any type of interior structure of a vehicle where it is desirable to place an airbag. For example the panel  12  can be a instrument panel, door panel, steering wheel, pillar, headliner, headrest, etc. Connected to the interior surface  16  of the panel  12  is a scrim  18 . The scrim  18  is a coarse mesh that can be made of metal or other suitable conductive material. In applications where resistive implant welding is not used to assemble the airbag  10 , the scrim  18  can be made of a non-conductive, non-metallic material. 
         [0017]    Operably connected to the scrim  18  is an airbag chute  20  formed by an upper support  22 , a lower support  24 , a first side support  26 , and a second side support  28  that can be separate components or integrated into a single piece. The airbag chute  20  surrounds a door assembly  30 ; in the embodiment shown, the door assembly  30  and airbag chute  20  are connected to the scrim  18 . The door assembly  30  and airbag chute  20  can be separate components or they can be formed together. The scrim  18  is larger in area that the airbag chute  20  and the door assembly  30 . The scrim  18  is also pre-cut on three sides as shown in  FIG. 3 . An uncut side forms a hinge  38  portion that allows the scrim  18  to fold. 
         [0018]    The panel  12  also includes pre-determined breaking lines (not shown) which are located on the inner surface  16  and are of the same shape as the airbag chute  20 . Locating the pre-determined breaking lines on the inner surface  16  will allow them to be hidden from view of the passengers, thus concealing the position of the airbag (not shown) and providing a seamless airbag door  10  while still allowing the airbag to be deployed through the panel  12 . 
         [0019]    Assembly is achieved through a process known as resistive implant welding (RIW). The scrim  18  is positioned against the inner surface  16  of the panel  12 , and the airbag chute  20  is placed against the scrim  18 . The resistive implant welding process involves applying an electrical current to the scrim  18 , which in this particular application is made of metal or another suitable conductive material, while the scrim  18  is in contact with the airbag chute  20  and the panel  12 . The electrical current causes the scrim  18  to heat up. The heated scrim  18  will cause the panel  12  and the airbag chute  20  to melt. Upon cooling, the scrim  18  is firmly connected to the inner surface  16  of the panel  12  and the airbag chute  20 . The use of the resistive implant welding process has the advantage of connecting the scrim  18  to the panel  12  and the airbag chute  20  as a single step in the manufacturing process. Other ways of heating the scrim material which facilitates the melt can be used. For instance the scrim  18  can be heated by an induction heating process and achieve the same results. 
         [0020]    It is not necessary for the upper support member,  22 , lower support member  24 , first side support member  26  and second side support member  28  to all be attached to the inner surface  16 . It is possible to only connect two sides and still secure the panel  12  and airbag chute  20  together. 
         [0021]    The scrim  18  is bonded to the panel  12  in two ways. The scrim  18  is either post applied to the panel  12  or the scrim  18  is over molded with the panel  12 . When the scrim  18  is over molded with the panel  12 , the scrim  18  is either partially embedded in the panel  12  or fully embedded in the panel  12 . After the scrim  18  and panel  12  are attached to one another, the airbag chute  20  is placed on the panel  12  and scrim  18 . However, if the scrim  18  is fully embedded in the panel  12 , the airbag chute  20  is only placed on the panel  12 . After that, heat or electrical current is applied to the scrim  18  which in turn melts the thermo plastic of the panel  12  and/or the air bag chute  20  for melt bonding them together. For example, when the heat is applied to the scrim  18  the heat is transferred from the scrim  18  to the panel  12 , and the surface of the panel  12  melts in order to create a tacky or sticky surface which is capable of adhering to the surface of the airbag chute  20  as the surface of panel  12  cools. Furthermore, the heat or electric current applied to the scrim  18  can also be transferred to the panel  12  and the airbag chute  20  when the airbag chute  20  contacts the panel  12 . Thus, both the surface of the panel  12  and the surface of the airbag chute  20  melt in order to create a tacky or sticky surface which adhere together when the surfaces cool. 
         [0022]    In operation, an airbag device  36  is located in the airbag chute  20 , and remains there when not in use. Upon deployment, the airbag device  36  will apply pressure against the door assembly  30 , which will in turn apply pressure against the scrim  18 , and the panel  12 . The pre-determined breaking lines will allow the portion of the panel  12  covering the airbag chute  20  to breakaway forming a ruptured portion of the panel  12 , and the door assembly  30  will be pushed outward. The area of the scrim  18  covering the airbag chute  20  will also breakaway along the cut-lines  34 . Upon airbag deployment, the ruptured portion of the panel  12 , the portion of the scrim  18  covering the airbag chute  20 , and the door assembly  30  will open as a single unit, and the airbag will inflate. The hinge portion of the scrim  38  will act as a hinge, preventing the door  30  and the panel  12  from hitting the passengers during airbag deployment. 
         [0023]      FIG. 3  shows a pre-cut scrim  32 ; the pre-cut scrim  32  has a cut-line  34  which matches the dimensions of the airbag chute  20  shown in  FIGS. 1 and 2 . The cut-line  34  is added to the pre-cut scrim  32  to facilitate the deployment of the airbag from the airbag chute  20 . The cut-line  34  can be precut into the scrim  32  prior to assembly, or the cut-line  34  can be laser cut into the scrim  18  at the same time the pre-determined breaking lines are laser cut into the panel  12 . Any type of cut which achieves the necessary hinge feature can be used in the present invention. Thus serrations or living hinges can be provided by die cutting, laser cutting, knife cutting or saw cutting, or otherwise scoring the perforation or partial cutting of the thickness of the door assembly along the cut line  34  for creating the hinge. 
         [0024]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.