Abstract:
A side impact air bag with a self-tensioned lower edge to prevent the occupant from ejection during a rollover event or subsequent impact, A side air bag is secured to the vehicle roof rail between the front and rear pillars. A pair of tethers are secured to the air bag at a lower portion thereof and one each in turn secured to the front and rear pillars. A plurality of substantially inverted V-shaped zero length tethers extend from the lower portion to define a plurality of chambers, which when inflated cause the lower portion of the air bag to shrink and induce tension therein and to the tethers. When the side impact air bag is inflated the air bag positions itself between the occupant and vehicle window and is held in place by the tension created by the inflated sections.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an inflatable air bag for an automotive vehicle and more particularly to a self-tensioning side impact air bag. 
     2. Description of the Related Art 
     Air bags mounted in an instrument panel or steering wheel to protect an occupant from a front impact have become standard in the automotive industry. Numerous variations of these air bags, deployment systems and housing devices have evolved over the years. However, these frontal air bags do not provide protection to the occupant during a side impact. Recent developments have focussed on technology directed to side impact air bags and related systems. 
     Side impact air bag systems are also known in the art. These side impact air bags are often mounted adjacent the vehicle&#39;s roof rail, doorframe or center pillars, or in some instances within the side door. It is desirable to have tensioning that positions the bag during side impact as well as any secondary events. 
     FIGS. 6A,  6 B, and  7  depict a side impact air bag  1  of the related art. The air bag  1  includes an inflatable element  2  having a top edge  3  and a lower edge  4 . A front tether  5  and rear tether  6  connect the inflatable element  2  to corresponding front and rear pillars of an automotive vehicle. The top edge  3  has a plurality of mounting connections  7  for connection to the vehicle&#39;s roof rail. The inflatable element  2  has a plurality of straight substantially square zero length tethers  8  extending from the lower edge  4  to the top edge  3 . FIG. 6B depicts the air bag of FIG. 6A in an inflated state. The inflatable element  2  shrinks when inflated and induces tension in the lower edge  4  and the tethers  5 ,  6 . This tension holds the air bag  1  in place relative to the vehicle. When the air bag  1  is mounted to the vehicle, the top edge  3  is fixed and cannot shrink in the horizontal direction when inflated and therefore the lower edge  4  tends to shrink as the top edge  3  retains its original shape. Thus the chambers  9 , created by the straight zero length tethers  8  tend to push against each other on the lower corners  10 , and tend to overlap. The amount of overlap, however, is restricted by the width of the zero length tethers  8 . Therefore, the amount the lower edge  4  is allowed to shrink is limited, thereby limiting the amount of tension induced during inflation. The air bag  1  of FIGS. 6A &amp; 6B suffers from the drawback in that tension is created between the mounting connections  7  between the top edge  3  of the inflatable element  2  and the corner  11  of the chambers  9  as generally depicted by tension lines  12 . The tension lines  12  restrict the shrinkage potential along the lower edge  4  of the inflatable element  2 . Therefore, it is desirable to improve this arrangement. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide an improved side impact air bag that overcomes the drawbacks of and improves upon the prior art and other related art. 
     The present invention is directed to a side impact air bag with a self-tensioned lower edge to position the air bag during a side impact, rollover event, or subsequent impact. A side air bag is secured to the vehicle along the roof rail between the front and rear pillars. A pair of tethers is secured to the air bag at a lower portion thereof and one each in turn secured to the front and rear pillars. A plurality of substantially inverted V-shaped zero length tethers extend from the lower portion to define a plurality of chambers, which when inflated, cause the lower portion of the air bag to shrink and induce tension therein as well as to the tethers. When the side impact air bag is inflated it positions itself between the occupant and vehicle window and is held in place by the tension created by the inflated chambers. The side impact airbag may also prevent an occupant from being ejected during a roll over event or subsequent impact. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an elevation view of a side impact air bag of the present invention mounted to an automotive vehicle in a stored position. 
     FIG. 2A is an elevation view of a side impact air bag according to one embodiment of the present invention mounted to a vehicle in a deployed non-inflated state. 
     FIG. 2B is an elevation view of the side impact air bag of FIG. 2A in an inflated state. 
     FIG. 3A is an elevation view of a side impact air bag according to an alternate embodiment of the present invention mounted to a vehicle in a deployed non-inflated. 
     FIG. 3B is an elevation view of the side impact air bag of FIG. 3A in an inflated state. 
     FIG. 4 is a sectional view of the side impact air bag of FIG.  3   b  taken along line  4 — 4 . 
     FIG. 5A is an elevation view of a side impact air bag according to the preferred embodiment of the present invention mounted to a vehicle in a deployed non-inflated state. 
     FIG. 5B is an elevation view of the side impact air bag of FIG. 4A in an inflated state. 
     FIG. 6A is an elevation view of a side impact air bag of the related art in a non-inflated stated. 
     FIG. 6B an elevation view of the side impact air bag of FIG. 6A in an inflated state 
     FIG. 7 is a section view side impact air bag of FIG. 6B taken along line  7 — 7 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is directed to an air bag of the present invention mounted to an automotive vehicle in a stored non-deployed state. An automobile  20 , has a front pillar  21 , a rear pillar  22  and a center pillar  23 . An air bag  1  is stored and mounted to the vehicle roof rail  24 . A first tether  25  connects a front portion  27  of the air bag  1  to the front pillar  21 . A second tether  26  connects a rear portion  28  of the air bag  1  to the rear pillar  22 . The rear portion  28  of the air bag  1  is connected to a gas generator  29 , or a duct leading from a gas generator to facilitate ingress of gas to the airbag  1 . 
     FIG. 2 is directed to a side impact air bag  101  of the present invention. Preferably tethers  125 ,  126  secure the inflatable element  102  between the A-pillar  121  and C-pillar  122  spanning the B-pillar  123 . However, the air bag  101  may be made to extend more rearwardly and secured to a D-pillar of a longer vehicle. Furthermore, the airbag  101  may be employed only in the forward compartment of the vehicle and connected to the A-pillar and B-pillars. It is preferred, however, to employ a single air bag  101  for both the front and rear passenger compartments, and therefore connect the inflatable element to the A-pillar (or front pillar  121 ) and the C-pillar (rear pillar  122 . 
     The inflatable element  102  may be made of any suitable air bag material for holding gas, but is preferably made of two sheets of woven nylon fabric lined with urethane or other substantially impervious material such as silicone. The two urethane coated nylon sheets are secured to one another along an outer periphery thereof to define the overall air bag shape. A plurality of inverted substantially V-shaped zero length tethers  108  also connect the two nylon sheets to provide the inverted substantially V-shaped zero length tethers  108 . The two sheets are connected along the pattern shown in dotted lines in FIG.  2 A. Preferably, the nylon sheets are secured to one another by heating selected portions of the fabric dialectrically. The urethane or silicone coating of each of the two nylon sheets is laid against each other and together line the interior of the inflatable element  102 . The inflatable element is then dialectrically treated to heat the outer periphery and zero length tethers  108  causing the coating to adhere to one another. This forms a gas tight seal along the outer peripheral surface and zero length tethers  108 . The two coated nylon sheets may also be stitched along the outer periphery and zero length tethers  108  to increase structural integrity sufficient to tolerate loads during inflation. When stitching is employed, it is preferred to treat the stitched area with a gas impervious substance to minimize gas leakage. Otherwise, the stress induced during inflation causes small holes in the stitching to widen and permit gas to escape thereby increasing deflation time. 
     When the air bag  102  inflates, the zero length tethers  108  cause the air bag  101  to inflate defining a plurality of separate chambers  109 . The zero length tethers  108  are preferably zero length between the two sheets of the air bag  101  Specifically, the two sheets are secured directly adjacent to one another thereby interconnecting opposite sides of the inflatable element  2 . In the embodiment of FIG. 2A, four inverted substantially V-shaped zero length tethers  108  are formed to define five separate chambers  109  and four separate zero length tethers  108 . The substantially V-shaped zero length tethers  108  are wider along the lower edge  104  than at a top portion thereof. Such an arrangement facilitates greater shrinkage of the lower edge  104  of the inflatable element  102  when inflated, thereby inducing tension along the lower edge  104  as well as to the first and second tethers  125 ,  126 . 
     The inflatable element is stored in a compartment mounted to the roof rail  24  as shown in FIG.  1 . Tethers  125  and  126  are also stored in a compartment in a corresponding pillar  121 ,  122 . When a side impact is detected, the air bag  101  is inflated by gas from generator  29 . The inflatable element  101  extends downward and is positioned and retained by the tethers  125 ,  126  as well as the point-wise mounting connections  107 . As gas fills the inflatable element  102 , the lower edge  104  shrinks by virtue of the inflation of the separate chambers  109  as shown in FIG.  2 B. Tension is thereby induced in the lower edge  104  as well as the tethers  125 ,  126 . Note that the tethers  125 ,  126  are taut in the inflated state shown in FIG.  2 B. The inflatable element  102  is thereby positioned between the occupant and the door or window opening to protect the occupant from side impacts and subsequent events, such as rollover or secondary impact. The inverted V-shape of the zero length tethers  108  allow the lower edge  104  of the inflatable element  102  to shrink more at the lower edge  104  for generating greater tension on the tethers  5 ,  6  and enhancing the ability to retain the inflatable element  102  relative to the vehicle  20 . 
     The inverted V-shaped zero length tethers  108  are superior to the straight substantially square zero length tethers  8  depicted in FIGS. 6A &amp; B. The inverted substantially V-shaped zero length tethers  108  allow the chambers  109  to fit together and enhance the ability of the lower edge to shrink generating greater tension on the tethers  125 ,  126 . Therefore, the arrangement depicted in FIGS. 2A &amp; 2B is preferred to that depicted in FIGS. 6A &amp; 6B. 
     FIGS. 3A,  3 B, and  4  depict an alternate embodiment of the inflatable element employing an alternative inverted substantially V-shaped zero length tether  208 . The lower portion  230  of the zero length tethers  208  are curved outwardly to provide a smooth contoured transition between the zero length tethers  208  and the lower edge  204  as shown by reference numeral  230 . Placing a radius or outwardly directed curve  230  reduces the tendency of the chambers  209  to overlap while allowing the lower edge to shrink more. FIG. 4 is a cross section of the lower portion  230  of the inflated element  202  of FIG.  3 B. The separate chambers  209  to do not overlap while the lower edge  204  is allowed to shrink greatly. FIG. 3B shows chambers  209  positioned adjacent one another without limitation of the zero length tethers  208 . The tethers  225  and  226  are taut. Contrary to the embodiment of FIGS. 3A &amp; 3B, the arrangement of FIGS. 6A &amp; 6B tend to cause the chambers  9  to overlap and restrict the ability of the lower edge  4  to shrink. Thus, the embodiment of FIGS. 3A &amp; 3B is much preferred to provide a smooth lower edge for occupant interaction. 
     FIGS. 5A &amp; 5B depict the air bag  301  according to another preferred embodiment of the present invention. The vehicles seat has been cutaway to demonstrate the relative position of the air bag  302  relative to the vehicle  320 . A substantially fan-shaped inflatable element  302  has a curved lower edge  304 , whose radius of curvature generally converges on pivot point  333 . The inflatable element  302  is secured to the vehicle  320  in a manner similar to that of the embodiment depicted in FIG. 1. A top edge  303  is secured to the roof rail  324 , or other opening adjacent the vehicle roofline at several point-wise mounting connections  307 . The point-wise mounting connections  307 , may be rivets, screws, bolts or other fasteners that will adequately retain the air bag during inflation. 
     A plurality of zero length tethers  340 ,  341  interconnecting opposite sides of the fan-shaped inflatable element extends from the lower edge  304  in a direction generally toward the pivot point  333 . Such an arrangement alleviates a drawback in the arrangement depicted in FIGS. 6A &amp; 6B. In the arrangement of FIGS. 6A &amp; 6B, tension is created between the mounting connections  7  along the top edge  3  of the inflatable element  2  and the corner of the chambers  9  as generally shown by tension lines  12 . This restricts the shrinkage potential along the lower edge  4  of the inflatable element  2 . 
     The fan-shaped inflatable element  302  and converging oriented zero length tethers  308  of the embodiment of FIGS. 5A &amp; 5B allow tension to be created at the lower edge  304  of the fan-shaped inflatable element  302  while creating little stress on the top edge  303  of the inflatable element  302 . This arrangement acts much like a folding fan that pivots about pivot point  333 . Tension is therefore not created between the mounting connections  307  and the lower edge  304  of the fan-shaped inflatable element  302 . The lower edge  304  of the fan-shaped inflatable element  302  can move upward and is not restricted by the mounting connections  307  as in the arrangement of FIGS. 6A &amp; 6B. As the fan-shaped inflatable element  302  inflates, it becomes thicker and shrinks in the horizontal direction and thereby induces tension in the tethers  325 ,  326 . 
     The fan-shaped inflatable element  302  preferably has two lengthened primary zero length tethers  340 , and three secondary zero length tethers  341  being shorter than the primary zero length tethers  340 . The secondary zero length tethers  341  are generally configured as inverted substantially V-shaped zero length tethers directed generally towards pivot point  333 . The primary zero length tethers  340  extend toward the top edge  303  beyond the secondary zero length tethers  341  and have a lateral portion  342  further extending laterally toward a forward chamber  350  positioned opposite the rear portion of the air bag connected to the gas generator  329 . A top seam portion  360  is positioned adjacent the pivot point  333  and disposed between the two primary zero length tethers  340  relative to the forward chamber  350 . The top seam  360  also interconnects opposite sides of the inflatable element  302 . During inflation the top seam  360  and lateral portions  342  of the primary zero length tethers  340  together and separately serve as a deflector to direct gas to the forward chamber  350 . Such an arrangement facilitates uniform inflation of the inflatable element  302 . The top seam  360  also serves to maintain a consistent overall thickness of the inflatable element  302  when inflated to enable deployment at substantially less pressure. 
     Each of the embodiments of the present invention provides an airbag tensioned along the lower edge to positively retain and position the air bag relative to the vehicle. The embodiment of FIGS. 2A &amp; 2B have a plurality inverted substantially V-shaped zero length tethers  108 . The V-shape promotes the ability of the lower edge  104  to restrict without limitation thereby increasing the amount of tension applied to the first and second tethers  125 ,  126 . In the embodiment of FIGS. 3A &amp; 3B, the inverted substantially V-shaped tethers  208  have outwardly directed curve  230  to provide a wide smooth transition between the lower edge  204  and the tethers  208 . This arrangement increases the ability of the tethers  208  to shrink and induce greater tension in the lower edge  204  and the first and second tethers  125 ,  126 , thereby increasing the ability to position and retain the inflatable element  202  in a deployed state. 
     The embodiment of FIGS. 5A &amp; 5B provide primary tethers  340  and secondary tethers  341  generally directed to a pivot point  333  adjacent the top edge  303  of the inflatable element  302 . This arrangement reduces tension between the mounting connections  307  which would otherwise reduce the ability of the lower edge  304  to shrink. Deflector portions in the form of lateral portions  342  and top seam  360 , further serve to direct air towards the forward chamber  350  to more uniformly inflate the inflatable element  302 . The top seam  360  further maintains a uniform thickness of the inflatable element  302  to facilitate inflation of the inflatable element at substantially reduced pressure. 
     Although the present invention has been fully described in connection with the preferred embodiment thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art. Such changes and modifications are to be understood as being included within the scope of the present invention as defined by the appended claims.