Patent Publication Number: US-2004041370-A1

Title: Slide attachment for air bag canister to instrument panel

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] This invention relates generally to an air bag support for a vehicle air bag which provides a seamless instrument panel.  
       [0003] 2. Background Art  
       [0004] Incorporation of air bags into vehicles has created many design challenges for automotive designers. It is desirable to incorporate an air bag into an instrument panel in front of the vehicle passenger seat. When incorporating an air bag into an instrument panel it is necessary to provide an air bag cover that will reliably and safely tear so that the air bag can deploy and protect the passenger. Tear seams have been provided to ensure that the air bag will deploy properly.  
       [0005] Vehicle designers prefer to have a continuous visible surface on the front face of the instrument panel whenever possible and would therefore avoid having a visible tear seam in the instrument panel. Thus, recently there has been an effort to achieve a “seamless” design wherein there is no indication on the front face of the instrument panel that the air bag is behind the instrument panel. To achieve this design, tear seams provided in the instrument panel are only provided on the under face, and not on the front face of the instrument panel.  
       [0006] A major design challenge with such “seamless” designs has been to provide an appropriate air bag support assembly for supporting the air bag before, during and after deployment through the instrument panel. Typically the air bag support assembly has been tailored to specific instrument panel configurations because the air bag support assembly is an integral part of the instrument panel itself. The instrument panel often requires additional support members near the air bag support assembly and the air bag support assembly must fit between these additional support members. Another challenge is that when the configuration of an instrument panel is changed, frequently the air bag support assembly must also be redesigned to fit in the new instrument panel.  
       [0007] Thus, it is desirable to create an air bag support assembly for an air bag that is independent of the instrument panel and that is standardized so that it can be incorporated in the “seamless” design of a variety of instrument panel configurations. Preferably, such an air bag support assembly would be simpler in design than current air bag support assemblies and permit a reduction in the number of additional support members currently used to support instrument panels adjacent to the air bag. Such a design would be readily adaptable to changes in the styling and configuration of the instrument panel.  
       SUMMARY OF THE INVENTION  
       [0008] The present invention discloses an instrument panel comprising an instrument panel body having a visible surface and an under surface. The instrument panel has brackets that extend rearwardly from the under surface comprising one of a plurality of axially spaced sections or axially spaced slots. The instrument panel also having a door circumscribed by at least one flexible hinge and at least one tear seam. The brackets provide support for an air bag module that includes a plurality of the other of the axially spaced sections or axially spaced slots sized to be received in one of the plurality of axially spaced sections or axially spaced slots spaced sections. The air bag module is secured to the brackets by inserting one of the axially spaced sections or axially spaced sections of the bracket into the other of the axially spaced sections or the axially spaced slots in the support structure and sliding the air bag module relative to the brackets.  
       [0009] The present invention also discloses an instrument panel comprising an instrument panel body having a visible surface and an under surface. The under surface has a tear seam to facilitate deployment of an air bag. The instrument panel also includes an air bag support assembly having an outer rim, a hinge member, a support structure, a door flap having a plurality of outer edges, and brackets that extend rearwardly from the outer rim comprising one of a plurality of axially spaced sections or axially spaced slots. The hinge member connects one of the plurality of outer edges to the outer rim. The support structure is secured to the outer rim and provides a support for an air bag module. The air bag module includes a plurality of the other of the axially spaced sections or axially spaced slots sized to be received in one of the plurality of axially spaced sections or axially spaced slots spaced sections. The outer rim and the door flap is secured to the under surface of the instrument panel body. The air bag module is attached to the air bag support assembly by inserting one of the axially spaced sections or axially spaced sections of the bracket rim into the other of the axially spaced sections or the axially spaced slots in the support structure and sliding the air bag module relative to the support structure.  
       [0010] These and other features and advantages of this invention will become more apparent to those skilled in the art from the following detailed description of the presently preferred embodiment. The drawings that accompany the detailed description can be described as follows. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0011]FIG. 1 is a front view of an instrument panel having an air bag support designed according to the present invention;  
     [0012]FIG. 2 is a cross-sectional view along line  3 - 3  of FIG. 1;  
     [0013]FIG. 3 is a perspective view of one method of attaching the air bag module to the instrument panel;  
     [0014]FIGS. 4 a - 4   f  are cross-sectional views of various axially spaced sections and slots; and  
     [0015]FIG. 5 is a plan view of one embodiment of air bag channel according to the present invention.  
     [0016]FIG. 6 is a cross sectional view of another embodiment of the present invention along line  3 - 3  of FIG. 1. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)  
     [0017] A vehicle instrument panel is shown generally at  20  in FIG. 1. The vehicle instrument panel  20  includes an instrument panel body  22  having a visible surface  24 .  
     [0018]FIG. 2 depicts a cross-sectional view of the instrument panel  22  along line  3 - 3 . The instrument panel  22  includes a visible surface  24  and an under surface  48 . A second layer of material (not shown) can be applied over the visible surface  24  to enhance the visual appearance of the instrument panel. Preferably, the instrument panel  22  is injection molded having a support structure  52  extending back from the under surface  48 . In the embodiment shown in FIG. 2, the support structure  52  has T-shaped brackets  54  disposed at the ends of the support structure.  
     [0019] The instrument panel  22  has a door  32  through which an air bag deploys. The door  32  is circumscribed by a flexible hinge  36  and tear seams  38   a ,  38   b , and  38   c . The tear seams  38   a ,  38   b , and  38   c  rupture to allow the door to open and pivot along the flexible hinge. One skilled in the art could devise a door  32  having a different shape and therefore have differently shaped hinges and tear seams. A restraining member  37  may be secured to the door  32  and support structure  52  to assist in maintaining the door to the instrument panel  22 .  
     [0020] An air bag module  56  having an air bag inflator  58  and an air bag  60  is located behind the instrument panel  22 . The shape of the air bag module  56 , air bag inflator  58  and air bag  60  may vary from that shown, as is known in the art. The air bag module  56  includes a pair of channels  62 . The channels  62  are shaped to slidably cooperate with a portion of the T-shaped brackets  54 .  
     [0021] When the air bag  60  is inflated, it will deploy against the underside of the door  32  and the flexible hinge  36 . The air bag  60  ruptures the tear seams  38   a ,  38   b ,  38   c  of the instrument panel body  22 . The flexible hinge  36  maintains the door  32  to the instrument panel body  22  and allows the door to rotate outwardly so that the air bag  60  can be deployed into the passenger compartment.  
     [0022] Referring now to FIG. 3, the support structure  52  is shown having a plurality of axially spaced sections  70  having a T-shaped cross-section. The length of each axially spaced section  70  can vary. The air bag module is shown as having first  72  and second  74  walls making up the channel  62  and a plurality of axially spaced slots  76  therein. According to this embodiment, first  78  and second lips  80  extend inwardly from first and second walls  72 ,  74  leaving a channel  82  therebetween. Between the axially spaced slots are a plurality of openings  84 . To assemble the air bag module  56  to the support structure rail, the air bag module is positioned such that the axially spaced sections  70  are in the openings  84 . The air bag module  56  is then slid as indicated by the arrows such that the axially spaced sections  70  are in the axially spaced slots  76  thereby retaining the air bag module to the instrument panel.  
     [0023] Although the axially spaced sections  70  are shown on the support structure  52  and the axially spaced slots  76  are shown on the air bag module  56 , the axially spaced slots may be on the support structure and the axially spaced sections may be on the air bag module.  
     [0024] The axially spaced sections  70  and the axially spaced slots  76  can of course be shaped otherwise. FIG. 4 a  shows a rectangular axially spaced section  70   a  and a rectangular shaped slot  76   a . FIG. 4 b  shows a circular cross-section of a axially spaced section  70   b  and a circular slot  76   b . FIG. 4 c  shows a L-shaped axially shape section  70   c  and a rectangular spaced slot  76   c . FIGS. 4 d ,  4   e , and  4   f  show variations of a Y-shaped axially spaced sections  70   d ,  70   e ,  70   f  and assorted slots  76   d ,  76   e ,  70   f.    
     [0025]FIG. 5 shows a plan view of a section showing another embodiment of the axially spaced slots  76 . In this embodiment, the axially spaced section (not shown) would be positioned into the openings and slid as shown by the arrows so that portions of the axially spaced section would be underneath flaps  86  of the axially spaced section. Flaps  86  on the bracket would prevent the axially spaced sections from dislodging from the axially spaced slots.  
     [0026] Another embodiment of the present invention is shown in FIG. 6. In this embodiment, an air bag support assembly  30  is provided that includes the support structure  52  and a door flap  33 . A welded joint  50  secures the air bag support assembly  30  to the under surface  48 . Alternatively, adhesive could be used to secure the air bag support assembly  30  to the instrument panel  22 .  
     [0027] The air bag support assembly  30  has a hinge member  136  and a gap  39  to create a door flap  33  which aligns with the door  32  in the instrument panel  22 . The gap  39  and the hinge member  136  circumscribe the door flap such that the door flap can freely pivot about the hinge member. The door  32  in the instrument panel  22  may be completely circumscribed by tear seams  38  or, alternatively, the door may have a flexible hinge  36  that aligns with the hinge member  136 . The gap  39  is positioned proximate at least some of the tear seams  38  on the instrument panel such that the door panel  32  can pivot freely with the door  32  when the tear seams  38  in the instrument panel  22  are ruptured.  
     [0028] When the air bag  60  deploys, it exerts force against the door flap  33  and the door  32  causing the tear seams  38  to rupture. The force of the deployment causes the door flap  33  and the door  32  to flex outwardly about the hinge member  136  thereby providing a passageway for the deploying air bag  60  into the passenger compartment. The weld joint  50  maintains the contact between the under surface  48  and the door flap  33 .  
     [0029] Preferably, the air bag support assembly  30  is formed of material that is molecularly compatible with the instrument panel  22 . For example, if the instrument panel  22  is made from a PC/ABS blend, then the air bag support structure  30  may be formed from a TPU material. One skilled in the art could readily determine other combinations of compatible materials. Also, it is most preferable that the air bag support assembly  30  including the door flap  32  be vibration welded to the under face  48  of the instrument panel body  22  to form the welded joint  50 . The vibration weld provides a very strong connection between the air bag support assembly  30  and the instrument panel body  22 . Forming the air bag support assembly  30  from a thermoplastic also enables the air bag support assembly  30  including the door flap  32  to conform to the shape of the under face  48  so the same standardized design can be used in instrument panels having a variety of configurations.  
     [0030] By having a plurality of axially spaced sections  70  and axially spaced slots  71 , the air bag module can be attached to the instrument panel in a much simpler and efficient manner. For example, prior applications required that the air bag module be slid approximately 12-24 inches to fully engage the support structure of the instrument panel. By using a plurality of axially spaced sections  70  and axially spaced slots  76 , the air bag module may be attached to the support structure by merely sliding the air bag module several inches. Further, the air bag module can be attached from either the right or left direction to allow for more assembly flexibility and compensate for part variances and expansion rates.  
     [0031] While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.