Abstract:
An integrated air bag support structure that functions to dissipate excessive energy from a door panel during air bag deployment includes a support base configured to surround a door support panel. An air bag chute tube extends downward from the support base and contains a plurality of skirt walls. The door support panel separated from the support base by a gap on all four sides. A hinge element extends between one of the skirt walls of the air bag chute tube and one edge of the door support panel, and includes a plurality of pivoting elements and an arm extension to absorb energy during deployment.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is related to the commonly assigned application Ser. No. 12/264304, filed Nov. 4, 2008, and entitled “AIR BAG DEPLOYMENT CHUTE.” 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to the field of air bag deployment systems for an automotive vehicle and more particularly to the area of a door support panel structure that has an energy absorbent hinge formed integral with an air bag chute. 
     2. Description of the Related Art 
     In this technology field, there have been several attempts to provide a passenger air bag chute with a deployment door hinge that is an integral part of the underlying support structure. 
     U.S. Pat. No. 6,076,851 describes an air bag deployment chute assembly for the passenger side of an instrument panel of a vehicle. An air bag support assembly is described as having an outer rim, a support structure, a door flap and a hinge member. The hinge member is connected between the door flap and the outer rim of the support assembly that is attached to the underside of the instrument panel. 
     U.S. Pat. No. 6,467,801 describes an air bag deployment chute similar to that in the &#39;851 patent, and also shows a hinge member that is attached between the door and the base reinforcement portion that surrounds the door. 
     U.S. Pat. No. 7,178,825 describes an air bag deployment door in which the hinge is configured to extend upwardly from the upper portion of a back up member that is attached to the underside of an instrument panel. The back up member includes a back up section, that is integrally formed with a door plate section, and a hinge. The hinge is formed with a dual curved configuration that allows the hinge to straighten out (“first and second curve portions of the hinge section are each extended”) as the air bag is deployed. 
     BRIEF SUMMARY OF THE INVENTION 
     The inventive concept is directed to an improved method and apparatus for use in an air bag deployment system that employs an air bag deployment structure formed to manage (partially dissipate) the deployment forces applied to the cover door in such a way as to allow minimum resistance to the air bag as it is being deployed, while controlling the opening action of the cover door and prevent its separation from the hinge. 
     The inventive concept includes an integrated structure with a support base for attachment to the rear side of a substrate. The support base is configured to surround a door support panel for attachment to the rear side of the substrate in an area that is pre-weakened to define an air bag deployment door in a vehicle instrument panel or a steering wheel air bag module. An air bag chute tube extends downward from the support base and contains a plurality of skirt walls for surrounding an air bag container and to define the path for deployment of the air bag from beneath the substrate. The door support panel is generally co-planar with the support base when attached to the substrate, but is separated from the support base by a gap on all four sides. A hinge element extends between one of the skirt walls of the air bag chute tube and one edge of the door support panel, and includes a pair of pivoting elements and an arm extension. A first pivoting element is formed with a downwardly directed curve having one end connected to the inner side of one of the skirt walls and the other end connected to the second pivot element. The second pivot element is formed with an upwardly directed curve having one end connected to the first pivot element and the other end connected to an extension arm that extends upwards to the edge of the door support panel. 
     During deployment of the associated air bag, the integrated structure allows energy forces presented to the door support panel to be partially dissipated into the structure via the hinge element. The result being that the dissipated forces are absorbed by the integrated structure which in turn causes the skirt wall, to which the hinge element is attached, to deform inwards towards the air bag container. 
     Therefore, it is an object of the inventive concept to provide an improved energy management method and system for an air bag deployment system that reduces the energy present on the door member during air bag deployment. 
     It is another object of the inventive concept to provide an improved hinge element for an air bag support structure that is configured to extend from a side wall of an air bag chute in such a way as to transfer energy from the door to the sidewall of the chute. 
     It is a further object of the inventive concept to provide an integrated structure that embodies the claimed features. 
     A more complete description of an embodiment of the inventive concept is presented below. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a perspective view of a vehicle instrument panel illustrating air bag deployment areas. 
         FIG. 2  is a cross-sectional view of an embodiment of the inventive concept connected to a substrate with an air bag container assembly. 
         FIG. 3  is a top plan view of an embodiment of the inventive concept prior to installation in a vehicle air bag deployment system. 
         FIG. 4  is a cross-sectional perspective view taken along section line  4 - 4  in  FIG. 3   
         FIG. 5  is a cross-sectional plan view taken along section line  4 - 4  in  FIG. 3  and showing the door section in both a closed and partially opened condition. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  represents a typical vehicle instrument panel  10  into which the inventive concept is to be installed. Additionally, the inventive concept is suitable for inclusion in a steering wheel air bag module  20 . 
     The air bag deployment structure  100  is represented by a support base  101  for shown as being attached to the lower surface of a substrate that forms part of the instrument panel  10 . A door support panel  104  is shown as also attached to the lower surface of the substrate, but positioned below an air bag deployment door that is defined by pre-weakened door seam  12  and hinge seam  13 . 
     In  FIGS. 2 ,  3  and  4 , the support base  101  is shown to have upper and lower surfaces. The upper surface of support base  101  contains a plurality of welding ribs  118  to facilitate attachment to the lower surface  11  of substrate  14  with a vibration welding process. (Of course other types of attachment such as ultrasonic welding, adhesives and other commonly known techniques may be acceptable substitutes, provided they preserve the energy absorbing characteristics described herein.) A door support panel  104 , also containing welding ribs, is attached to the lower surface  11  of substrate  14  within an area defined as the air bag deployment door by the pre-weakened seams  12  and  13 . In this configuration, the door tear seam  12  is pre-weakened to the extent that the outer surface of instrument panel  10  and the substrate  14  will completely rupture upon deployment of the air bag. Seam  13  is a hinge seam and is only required to provide a pivot point for the substrate and outer skin of the instrument panel  10 . Therefore it may be pre-weakened to a lesser extent than door seam  12 . 
     The air bag deployment structure  100  is formed as a one piece molding of a flexible material such as Dexflex™ or other material that exhibits equivalent or superior ductility at very cold temperatures at least to −30° C. and good toughness at high temperatures at least to 90° C. Other materials such as TPO (Thermoplastic Olefin), TPE (Thermoplastic Elastomer or TEO (Thermoplastic Elastomer Olefin) could be substituted. It is believed that various pieces could be separately formed and joined together to replicate the one piece molded embodiment. If that is done, care will have to be made in order to obtain the energy management that is offered by the integration of the various elements that make up the disclosed structure. 
     Support base  101  is a generally planar flange that is substantially coplanar with the door support panel  104 . As shown in the figures, there is a slight curvature that is intended to correspond to the substrate surface to which the structure  100  attaches. Such a substrate could be curved or perfectly planar. For purposes of this discussion, the support base  101  and the door support panel  104  are described as generally planar to mean that they are configured to be attached to the underside of the substrate  12  that is generally smooth and continuous. 
     In the depicted embodiment, an alignment slot  137  is provided in an extension from support base  101 . Although not shown, the substrate  12  may have a protrusion formed therein and extending from its lower surface to provide a keying feature to assist in the placement of the support structure  100  prior to being welded to the substrate. Apertures  135  on tabs extending from support base  101  are used to perform the same function as alignment slot  137  with protrusions extending from the lower surface of substrate  12 . 
     A test tab extension  139  is shown as having deformable ribs  136  that are identical in content to deformable ribs  118  on support base  101  for attachment to the corresponding lower surface area of the substrate  12  during the same vibration welding process. The test tab extension  139  allows the welding vendor or subsequent customer to perform non-destructive quality control testing by applying a pull pressure to the tab and thereby ensure that the entire weld of the support structure  100  to the substrate is acceptable. 
     Door support panel  104  and support base  101  are separated by a gap  112  so that door support panel  104  is not directly attached to the support base  101 . The support base  101  extends under the pre-weakened door seams  12  and  13  and therefore provides resistance to inward pressures that may be applied to the outer surface of the instrument panel. In the depicted embodiment, several apertures  110  are shown in door support panel  104 . Apertures  110  are positioned to reduce the mass of the door support panel  104  without affecting its support or attachment properties. 
     An air bag chute tube is formed by skirt walls  105  and  108  which extend downward from support base  101 . In this embodiment, the air bag chute tube has a rectangular configuration defined by end skirt walls  105  and side skirt walls  108 . Angle gussets  127  and  128  are spaced along the skirt walls  105  and  108  to provide added strength and some rigidity between the support base  101  and the air bag chute tube. 
     A hinge element  200  extends between one of the side skirt walls  108  and hinge edge  107  of door support panel  104 . Hinge element  200  includes respective first and second pivoting elements “A” and “B” and an arm extension  103 . From the end, it can be seen that the first pivoting element A is formed with a downwardly directed curve having one end connected to the inner side  109  of side skirt wall  108  and the other end connected to said second pivot element B. The second pivot element B is formed with an upwardly directed curve having one end connected to the first pivot element A and the other end connected to extension arm  103 . Extension arm  103  extends upwards from second pivot element B to a hinge edge  107  of said door support panel  104 . Each pivot element is an axial extension substantially parallel to each other and to the edge of the door panel to which the arm extension  103  is connected. Each pivot element, as well as arm extension  103 , extends approximately the full length of the hinge edge  107 . 
     The longer side skirt walls  108  contain several window apertures  114  and  116  for engagement with a corresponding number of attachment hooks  304  and  306  extending from an air bag container  300 . Each window aperture  114  and  116  has a tab  115  and  117  that bear against the inserted hooks to tighten the engagement connections and prevent rattling from occurring between the air bag container and the air bag chute during vehicle operation prior to air bag deployment. 
     The lower portions of the side skirt walls  108 , below the windows  114  and  116 , contain reinforcement barriers  122  and  124 . Reinforcement barriers  122  and  124 , in the depicted embodiment, are formed as a doubled thickness of the side skirt wall material and are formed along the entire length of side skirt walls  108 . Reinforcement barriers act to prevent hooks  304  and  306  from completely tearing through the side skirt walls from their positions in the windows  114  and  116  when the air bag is deployed. When an air bag is deployed, there is severe pressure initially present within the air bag container and chute. Because the air bag container  300  is fixed to the structure of the vehicle at beam  350 , the hooks  304  and  306  prevent separation of the air bag support structure  100  and the instrument panel from their intended locations during air bag deployment. Hooks  304  and  306  interact with side skirt walls  108  below the windows  114  and  116  to contain the pressure and allow the chute to remain intact and direct the pressure to the door support panel  104 , which will force rupturing of the tear seams  12  and allow the air bag to deploy. Some prior art applications use metal side walls in air bag chutes to prevent tearing. In the present inventive concept where a thermoplastic material, such as noted above, is molded to form an integrated structure  100 , the double thickness reinforcement barriers  122  and  124  function to prevent the hooks from completely tearing through and allowing separation of the air bag support structure. 
     In  FIG. 5 , the energy management effects of the inventive concept are depicted. In the solid line cross-section portion of the drawing, the door support panel  104  is shown in its closed position, as it would normally be when installed in a vehicle and prior to air bag deployment. Upon deployment of the air bag, the forces applied against the underside of door support panel  104  cause the hinge to initially pivot around pivot element A that is attached to the inside surface  109  of side skirt wall  108 . As resistance builds a along pivot element A, the door continues to flex open and rotate about pivot point B. When fully open, the door reaches the position indicated as  104 ′ and due to energy dissipation through the hinge and into side skirt wall  108 , the side skirt wall flexes inward as  108 ′. Because the compound hinge with a plurality of pivot points is connected to the side skirt wall  108  at a position below the lower surfaces of the support base  101  and the door support panel  104 , this allows the energy to be transferred into the side skirt wall. It allows a substantial portion of the energy applied against the door support panel  104 , following rupture of the tear seams  12 , to be dissipated and therefore reduce the potential for having the door support panel become separated during air bag deployment. 
     It can be seen from the drawings and accompanying explanation, that the present inventive concept is a unique improvement over conventional air bag deployment support structures and methods of managing deployment energy. And while the embodiment shown here is a preferred embodiment, it shall not be considered to be a restriction on the scope of the claims set forth below.