Abstract:
An integrated air bag chute structure that provides means for providing automatic interlocking attachment of the chute to the substrate of an instrument panel. By inserting the air bag chute into a substrate aperture and utilizing slots, depressions and notches formed in the chute structure beneath a surrounding flange, the aperture edges are captured and retained to thereby lock the chute in place.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is related to the commonly assigned application filed contemporaneously herewith and entitled: AIR BAG CHUTE SEAL, U.S. Ser. No. 12/404,410. 
     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 an air bag chute structure. 
     2. Description of the Related Art 
     In this technology field, there have been several methods of providing attachment of a passenger air bag chute to a vehicle interior panel. In cases where there is a foam-in-place process used to provide the foam layer between the air bag deployment door of a chute that is mounted on the instrument panel substrate and the outer skin layer, a seal element is typically employed to prevent leakage of the foam material during the process. In addition, the air bag chute is typically clamped in place to the instrument panel substrate by the use of screws or bolts. 
     U.S. Pat. No. 6,644,685 describes an air bag chute with a base reinforcement portion that surrounds a deployment door. When foam is injected as a liquid between the instrument panel substrate and the outer skin, a gasket or adhesive tape is described as being used to prevent leakage of the liquid foam from gaps formed between the reinforcement portion and the substrate. In the disclosed configuration, the adhesive tape layer is placed over the door panel and has its hinge edge clamped against the chute support structure with fasteners such as bolts. The entire air bag chute structure is attached to the instrument panel substrate by the use of fasteners which extend through an outer compression frame, the adhesive layer, the instrument panel substrate and the upper flange of the air bag support frame. 
     U.S. Pat. No. 6,709,007 describes an embodiment of an air bag deployment chute attached to the substrate of an instrument panel with bolts. A layer of masking tape or a die cut polymer with an adhesive on each surface is applied between the reinforcing ring and the instrument panel substrate to prevent the foam from penetrating between those elements. 
     U.S. Pat. No. 6,716,519 shows the use of a urethane sealing layer to prevent foam migration through mating lower surface of an air bag chute flange against the upper surface of an instrument panel substrate. The air bag chute is an integrated molding that attaches to the instrument panel substrate in a generally flush manner. 
     U.S. Pat. No. 7,237,797 shows the use of a masking tape sealing layer to prevent foam migration through mating surfaces on the instrument panel. The tape is folded over the edge of the door panel and the air bag chute frame to keep the door in the closed position. Studs and nuts are used to attach the air bag chute to the instrument panel substrate. 
     SUMMARY OF THE INVENTION 
     The inventive concept is directed to an improved method and apparatus, for use in an air bag deployment system that includes an air bag deployment chute formed to have an encircling flange member that seals itself against the upper surface of an instrument panel substrate to prevent foam migration during the foam-in-place injection process. The air bag chute structure is configured with a plurality of elements that interlock with the edge of the substrate aperture during installation of the chute into the aperture. The interlocking elements serve to retain the chute in place. One interlocking element is an elongated single tab (or series of tabs) that defines a slot beneath the flange on a first side wall of the chute skirt to capture the edge of an air bag aperture formed in the instrument panel substrate when the chute structure is inserted into the aperture. A series of indentations on the opposite side wall of the air bag chute skirt reside below the flange and are disposed to catch corresponding tab elements protruding from the instrument panel aperture as the air bag chute becomes fully inserted into the aperture. Flexible gussets that function to support the flange on the other two side walls of the air bag chute skirt contain notches that engage the instrument panel substrate when it is fully engaged into the aperture. 
     The inventive concept includes an integrated air bag deployment chute structure with a support base for attachment to an opening in a vehicle interior substrate. The support base is configured with a flange that surrounds a door support panel and overlays the opening in the vehicle interior substrate when inserted therein. The flange has outer edges that are flexible and tapered to lie flat against the substrate surface to both seal the interface and minimize interference to the flow of foam during the foam-in-place injection process employed after the chute structure is inserted into the aperture of an instrument panel substrate and locked in place. 
     A rectangular air bag chute skirt extends downward from the support base. The chute side walls are made up of two opposing major walls that run parallel with each other and two opposing minor walls that join the two major walls. The major walls are also parallel to the hinge and leading edge of a door support panel defined in the upper portion adjacent to the flange. The four walls form a skirt for surrounding a separate air bag container and define the path for deployment of the air bag from the air bag container. In the described embodiment, the door support panel is generally co-planar with the support base flange and has defined door edges formed on three sides by pre-weakened molding or scoring. The door support edges remain attached to the support base prior to deployment of the air bag. A door support hinge element is formed to extend along one side of the defined door. In the described embodiment, the entire upper surface of the air bag deployment chute that includes the door support panel and the flange is continuously closed without gaps or openings so that there is no potential path for foam leakage during the foam-in-place injection process. 
     The chute side walls on the lower portion of chute form a rectangular cross-sectional chute having first and second generally parallel and opposed major walls that are longer than third and fourth generally parallel and opposed minor walls oriented generally perpendicular to the first and second walls. 
     On the outer surface of a first side wall and below the flange, a single elongated tab (or a plurality of short tabs) is located to extend outwardly from the wall and define a corresponding slot between the tab and the underside of the flange. The slot is arranged in a line that corresponds to the edge of the substrate aperture into which the structure will be mounted. When the chute is inserted into the aperture from the upper side of the instrument panel substrate, the slot becomes engaged with the edge of the aperture and holds the tapered edge of the flange adjacent thereto, against the upper surface of the substrate. 
     The third and fourth side side walls contain gussets or braces to provide support to the flange extending above those walls. The gussets are of the same flexible material as the remainder of the integrally molded chute and because they extend beyond the substrate aperture, are slightly deformed during the insertion process. Notches are provided in the upper portions of the gussets to accommodate the side edges of the aperture in the instrument panel substrate. When the chute is fully inserted into the aperture, the gussets resume their original shapes and the notches capture and hold the chute and the flange in place for maintaining the seal. 
     The second skirt wall contains a series of individual notches or depressions that extend substantially the length of the wall beneath the flange and are sized to accept tab like extensions from the aperture edge, when the chute is fully inserted into the aperture. These depressions, along with the notches in the side gussets, retain the three sides of the chute and maintain the seal between the flange edges extending from those three sides and the upper surface of the instrument panel substrate. 
     Therefore, it is an object of the inventive concept to provide an improved air bag deployment chute that is held in place within the instrument panel of an automotive vehicle by merely inserting the chute into a corresponding aperture in the substrate. 
     It is another object of the inventive concept to provide an improved air bag chute that is an integrated structure with a surrounding flange having a tapered edge that seals against the upper surface of the instrument panel to which the air bag chute is mounted prior to performing a foam-in-place process and an attachment configuration that maintains the seal without the need for additional components such as fasteners. 
     It is a further object of the inventive concept to provide an air bag chute structure used in an air bag deployment system of an automotive vehicle wherein the structure is configured to be installed in an aperture of an instrument panel substrate; the structure contains an upper portion with a flange surrounding the structure; the flange is formed to engage the upper surface of the substrate surrounding the aperture when the structure is inserted into the aperture; and retaining slots and notches are provided in the lower portion of the chute structure to engage and interlock with the edges of the aperture formed in the instrument panel substrate during its insertion therein and to permanently retain the chute in the aperture. 
     It is a still further object of the inventive concept to provide a method of retaining an air bag deployment chute structure in an aperture formed in the substrate of an automotive instrument panel as a result of inserting the chute into the aperture from the upper surface side of the substrate and subjecting the chute to downward pressure to engage the retaining mechanism. The steps include providing the chute structure with a flange that extends around a defined deployment door support panel sufficiently to exceed the dimensions of the aperture; providing the outer side skirt walls of the chute below the flange with notches and slots that will engage the edges of the aperture when inserted into the aperture; insert the air bag deployment chute structure into the aperture in the substrate so that the flange engages the upper surface of the substrate; and fully depress the flange against the substrate until all the notches and slots engage the edges of the aperture. 
     It is a still further object of the inventive concept to provide an air bag chute structure for use in an instrument panel air bag deployment system of an automotive vehicle, comprising: a generally planer deployment door support panel portion integrated in the structure and defined by a plurality of pre-weakened edges and a flexible hinge with an upper surface and a lower surface; a generally planar flange member portion with an upper surface and a lower surface extending from the area surrounding the door support panel; an air bag chute portion extending from an area adjacent the lower surfaces at a junction of the door panel and the flange for insertion into a corresponding aperture formed in the substrate of an instrument panel; a single elongated tab (or series of tabs) that defines a slot (or series of aligned slots) beneath the flange along the hinge side of the chute portion between the lower surface of the flange and having a slot width that is substantially equal to the thickness of the aperture edge to engage the aperture edge when the chute is inserted into the aperture; and a plurality of notches disposed below the lower surface of the flange on the other sides of the chute portion to engage portions of the aperture edge when the air bag chute is fully inserted into the aperture. 
     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 the air bag chute structure of the present invention. 
         FIG. 2  is a perspective view of the same air bag chute shown in  FIG. 1 , but rotated upwards to reveal the detail of the sidewall below the door support panel hinge. 
         FIG. 3  is a perspective view of the same air bag chute shown in  FIG. 1 , viewed from the opposite side to reveal the detail of the sidewall below the door support panel opening edge. 
         FIG. 4  is a top plan view of the instrument panel substrate aperture into which the air bag chute of the present invention is inserted. 
         FIG. 5  is a cross-sectional view of the air bag chute of the present invention taken along lines  5 - 5  in  FIGS. 2-4  as it is being inserted into the instrument panel aperture and having one side initially engaged with the instrument panel substrate. 
         FIG. 6  is a cross-sectional plan view of the air bag chute structure of  FIG. 5  after it has been fully installed in the instrument panel substrate and subjected to the foam-in-place process. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The perspective view of the air bag chute  100  of the present invention is shown in  FIG. 1  with the forward or windshield side in the foreground and the rear or passenger side in the background. The air bag chute  100  is embodied as a unitary structure  110  that is molded of a plastic material preferably having some flexibility to prevent fracturing during air bag deployment in all expected temperatures of operation. The upper portion of the structure  110  includes a door support panel  120  that is defined by a pre-weakened seam  122  at the outermost (initially rupturing) edge and a pair of pre-weakened seams on side edges  121  and  123 . A hinge  124  defines the fourth side of the door support panel  120 . 
     When installed on the instrument panel of a passenger vehicle, the hinge is closest to the windshield of the vehicle and the initially rupturable seam  122  is located closest to the passenger seating position. 
     The air bag chute 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. Materials such as TPO (Thermoplastic Olefin), TPE (Thermoplastic Elastomer) or TEO (Thermoplastic Elastomer Olefin) could be substituted. 
     In the shown embodiment, door support panel  120  is surrounded by a mounting flange  108  that is generally rectangular in shape and has flexible and tapered edges  112 ,  114 ,  116  and  118  of mounting flange  108 . The tapered edges are formed to be biased slightly downward so that when installed in the aperture of an instrument panel substrate  50 , the flange will provide a compression seal with respect to the substrate surface. 
     A plurality of windows  150  and  154  with retainer tabs  152  and  156  are located on lower chute side walls  126  and  128 , and reinforcement bars  130  and  132  are located at the lowest edge of the chute walls  126  and  128  ( FIGS. 2 and 3 ). Retainer tabs  152  and  156  function to contact hooks extending through the windows  150  and  154  from the air bag container module (not shown) to reduce vibration/rattling in a conventional manner. 
     On sidewall  126 , a single tab like protrusion  140  is shown in  FIG. 2  that runs over most of the sidewall length. The guide tab  140  is supported by a series of gussets  141  that are anchored to the side wall  126  between window locations. The guide tab  140  is located just below the flange  108  and above the windows  150  to form a slot  142  therebetween. The slot has a height measured between the guide tab  140  and flange  108  that is approximately equal to the thickness of the edge of the aperture  51  in the instrument panel substrate  50 . The guide tab  140  and slot  142  serve to engage the edge of the aperture  51  during insertion of air bag chute  100  therein. Following the completion of insertion of air bag chute  100  into the aperture  51 , the tab  140  functions to retain the air bag chute in aperture  51 . 
     Other features pertinent to the present invention include the support gussets  160  shown in  FIGS. 2 and 3 . These support gussets are located on the outer sides of both side walls  127  and  129  to provide a degree of rigidity between the flange  108  and the sidewalls. Notches  162  are provided just below the flange  108  to have a size that corresponds to the thickness of and to engage the edges  55  and  56  of aperture  51  ( FIG. 4 ) when air bag chute  100  is inserted therein. 
     On the passenger side of air bag chute  100 , shown in  FIG. 3 , a series of indented depressions  144  are formed in sidewall  128  in correspondence to the locations of tab like protrusions  53  extending from the edge of the aperture  51  in the instrument panel substrate  50  ( FIG. 4 ). The depressions  144  are spaced apart so that they are separated by the window openings  154 . This separation and location serves to retain the strength integrity of the sidewall  128  that may be compromised if the depressions  144  were to be located above the windows or were formed as a single continuous depression that extended over the windows  154 . 
       FIG. 5  illustrates how guide tab  140  and slot  142  of air bag chute  100  (taken along section lines  5 - 5  in  FIGS. 2 ,  3  and  4 ) are used to engage edge  52  of aperture  50  during the initial part of the installation of air bag chute  100  therein. As can be seen, the lower chute skirt made up of sidewalls  126 ,  127 ,  128  and  129  is inserted into aperture  51  from above. As the forward portion of flange  108  containing tapered edge  114  is pressed against substrate  50 , flange  108  is flexed upwards to allow edge  52  to slide into slot  142 . Once edge  52  is fully engaged in slot  142 , the passenger side of chute  100  is depressed into aperture  51 . During that depression, gussets  160  are flexibly deformed inwards by side edges  55  and  56  until slots  162  engage. When slots  162  engage, gussets  160  are restored to their normal shapes. Further depression of chute  100  into aperture  51  allows depression  144  in sidewall  128  to engage tab protrusions  53  (see  FIG. 6 ). At that point, air bag chute  100  is fully inserted into aperture  51  and secured in instrument panel substrate  50 . 
     In  FIG. 6 , a cross-sectional view of air bag chute structure  110  is shown taken along section lines  5 - 5  in  FIGS. 2 ,  3  and  4 , fully mounted on instrument panel substrate  50 . The drawing illustrates air bag chute  100  in its finished condition mounted on the instrument panel  50  and covered with a foam interlayer  70  and a “class A” outer skin  60 . It should be noted that many choices of outer skin layers or laminations can be used that are both conventional and yet to be invented. The actual materials used for the outer skin are not pertinent to the present invention except for the property of containing the initially injected foam in its liquid form, and later the foam flow back as it approaches its solid form during the foam-in-place process described above. 
     The air bag chute structure  110  is inserted into the aperture  51  defined in the instrument panel substrate  50 . Guide tab  140  is located under flange  108  and extends from the outside of side wall  126  towards the tapered outer edge  114 . Slot  142  is shown formed between guide tab  140  and the underside of flange  108  below and in the vicinity of hinge  124 . Slot  142  is only slightly larger than the thickness of the substrate  50 , at that location, and allows the chute structure to positively engage edge  52  of aperture  51 . When installed, the tapered edge  114  of flange  108  sealingly engages the upper surface of substrate  50 . 
     At the rear passenger side of the air bag chute structure  110 , depressions  144  formed in sidewall  128  below and in the vicinity of the leading edge  122  of the support door panel  120  are shown engaging edge tab protrusion  53  of aperture  51 . Tapered edge  112  of flange  108  sealingly engages the upper surface of substrate  50 . Although not shown, the other tapered edges  116  and  118  of flange  108  also sealingly engage the upper surface of substrate  50 . When installed, as shown in  FIG. 6 , tapered edges  112 ,  114 ,  116 ,  118  provide a complete seal of the opening  52  in substrate  50  without the requirement for masking tape or other add-on sealers. 
     An alternative embodiment of the present invention (not shown) duplicates the retention mechanism pictured on the passenger side of the air bag chute structure  110  on the forward or windshield. Instead of using a guide tab  140  below the underside of flange  108  in the vicinity of hinge  124  to define slot  142 , depressions  144  are formed in sidewall  126  below and in the vicinity of hinge  124 . Edge tab protrusions  53  of aperture  51  on the passenger side of the substrate aperture are duplicated on the forward side of the substrate aperture to accommodate and engage with the depressions on that side of the air bag chute structure  110 . Installation of this embodiment allows for a straight or angled insertion of the air bag chute structure  110  into the aperture  51 . Retention is completed when the tab protrusions  53  engage the depressions  144  in both side walls  126  and  128 . 
     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 installation. And while the embodiments described here are preferred, they shall not be considered to be a restriction on the scope of the claims set forth below.