Abstract:
A rollover cushion and system for a motor vehicle is fabricated from a lightweight, low denier material having its inside surface coated with a gas retention material. A gas generator responsive to a sensor generates an inflation fluid that fills the sealed curtain causing the curtain to deploy over the side windows of the vehicle. In this position, the head and upper torso of an occupant are protected from striking or going through an open window during a rollover or side impact collision. Several styles of tethers are used to maintain the desired shape of the cushion. A manifold system directs the flow of the inflation fluid from the gas generator to the gas inlets in each individual cylindrical tube of the curtain. The cushion is folded either in a “Z” fold or in a tuck fold and at one end fastened to the structure of the vehicle and at the other end extending in a direction down the window. A pair of curtain tethers secured to the cushion and to the pillars maintain the cushion taut when inflated.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     An inflatable vehicular occupant safety restraint system in general and more particularly an inflatable rollover cushion for motor vehicles prone to rollover situations. 
     2. Description of the Related Art 
     U.S. Pat. No. 5,588,672 issued on Dec. 31, 1996 to Karlow et al and entitled “Side Impact Head Restraint With Inflatable Deployment” shows a side curtain that is attached to the roof rail and has a slide that slides down the “B” pillar. When the system is to be deployed, a gas generator generates gas to inflate the curtain. As the gas fills the curtain, a slide moves along a track on the “B” pillar to a position immediately below the centerline of the side glass. This is the only movable point in the curtain because along the roof rail the curtain is secured. When the slide comes to the end of track, it locks in place securing the curtain along the “B” pillar. Depending upon the shape of the curtain, the curtain will extend from the end of the track to a fixed point along the roof rail above the door. An occupant&#39;s head will strike the curtain that absorbs the head impact either by rebounding the head or giving way toward the glass. 
     U.S. Pat. No. 5,788,270 issued on Aug. 4, 1998 to HÅland and entitled “Side Impact and Roll Over Inflatable Head Protector” describes an elongated curtain that has a slide that moves along a track on the “B” pillar. The curtain has a plurality of equally spaced inflatable tubes, that when inflated extend from the roofline to a position intermediate the height of the glass. An occupant&#39;s head will strike the inflated curtain and be prevented from going through or out the window. The curtain in this embodiment has a web or a sheet that is not inflated, but rides with an inflatable portion as it is being inflated. The web extends from a point intermediate the length of the window to the “A” pillar so that only the rearward portion of the curtain is inflated. Several different size configurations are illustrated wherein each configurations extends from the roof rail to a point intermediate the height of the window. 
     At lest one major American car manufacturer has shown, at the Year 2000 International Auto Show in Detroit, Michigan, a mock-up of a potential side airbag curtain for some of its sport utility vehicles. The curtain extends from a position near the “A” pillar to a point adaptable to restrain the head of a rear passenger. Another American Car manufacturer has an article on page in the Automotive News, May 15, 2000, that it will install head curtain airbags manufactured by Autoliv Inc. on its 2001 cars. 
     SUMMARY OF THE INVENTION 
     It is a principal advantage is to manufacture a curtain from a lightweight material that is coated on the inside to retain the inflatable fluid. 
     It is yet another advantage to have a material that when formed into a gas-filled curtain will require less gas than similar curtains of substantially the same size because the material has less permeability. 
     It is still yet another advantage to provide a curtain that has a plurality of inflatable tubes extending either longitudinal or parallel to the upper door panel of the vehicle. 
     These and other advantages will become apparent from the inflatable rollover cushion for motor vehicles having a bag member formed from a single piece of lightweight material. The material is folded over and sealed along the mating open edges forming an enclosed member. Along each open seam is a “Y” shaped tether member joining the bag edges together. The “Y” shaped tether has displaceable upper arms joined together along a trunk. One open edge of the enclosed member lies along the upper arm of the “Y” and along one side of the trunk and the other open edge lies along the other upper arm of the “Y” and along the other side of the trunk. A bonding is used to secure the mating open edges along the “Y” shaped tether member forming an enclosed member forming an elongated cylindrical member. An opening at one end of the bag member is adapted to receive inflation fluid for inflating the bag member. The inside surface of the folded bag member is coated with a gas retention material. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a view of the left had side of a motor vehicle from the inside having an inflated cushion with a section exposed showing the “B” pillar; 
     FIG. 2 is a partial cross-sectional view of one embodiment of joining the sections of an inflated cushion; 
     FIG. 3 is a partial cross-sectional view of another embodiment of joining the sections of an inflated cushion; 
     FIG. 4 is a plan view of a strip of “X” shaped tethers; 
     FIG. 5 is a sectional view taken along line  5 — 5  of FIG. 4; 
     FIG. 6 is an isometric view of the tether of FIG. 4; 
     FIG. 7 is an isometric view of a “Y” shaped tether sheet as manufactured prior to the operation of slitting; 
     FIG. 8 is a “Y” tether; 
     FIG. 9 is a double “Y” tether; 
     FIG. 10 is a view of the left had side of a motor vehicle from the inside having another embodiment of inflated cushion; 
     FIG. 11 is a plan view similar to FIG. 1 for the purposes of illustrating the tethers; 
     FIG. 12 is a sectional view taken across the curtain folded in the roof rail above the door prior to inflating illustrating a folding pattern for the cushion; and 
     FIG. 13 is a sectional view similar to FIG. 12 illustrating another folding pattern for the cushion. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to figures by the characters of reference there is illustrated in FIG. 1 an inflatable rollover cushion for motor vehicles. The view is from the inside of the motor vehicle  10  looking at the left side of the vehicle. From right to left in FIG. 1 there is illustrated the windshield  12  of the vehicle  10  and the adjacent “A” pillar  14 . The inflated rollover cushion or curtain  16  is illustrated as covering the front door  18  and extending past the “C” pillar  20  to the “C” pillar  22  covering the windows  23  of both the front door  18  and the back door  24 . The rollover cushion  16  extends from the roof rail  26  to below the window  23 , hidden by the cushion, and along the door panels  28 . 
     In this embodiment, the inflated cylindrical tubes  30  of the curtain  16  extend in a direction that is normal to door panels  28 . The curtain has a plurality of cylindrical tubes  30  that are of a size and length as indicated by the designer of the curtain or cushion  16 . The smaller the cross-sectional area of the tubes  30 , the more tubes are needed to cover a given area. The larger the cross-sectional area of the tubes  30  will decrease the travel of the occupant&#39;s head, not shown, during a side-impact or rollover of the vehicle  10 . A first curtain tether  31  is attached to the curtain  16  and to the “A” pillar  14 . A second curtain tether  33  is attached to the curtain and to the “C” pillar  22  to keep the curtain  16  taut against the windows  23 . 
     The upper ends  32  of the cylindrical tubes, that is the ends nearest the roof rail  26 , each have an inlet  34  that along with a passageway  36  forms a manifold system  37 . The manifold system  37  conducts the inflation fluid from the gas generator  38  to each tube  30 . The gas generator  38  can be positioned substantially any place in the vehicle  10  and has tubes  40  extending from the gas generator  38  to the passageway  36  in the manifold system for conducting the inflation fluid. Typically, the gas generator  38  will be placed in the roof  42  of the vehicle  10  very close to the curtain  16 . 
     In the normal position, the curtain  16  is rolled or folded in a space along the roof rail  26  and is concealed by the interior headliner  39  material of the vehicle  10 , as illustrated in FIGS. 12 and 13. The inflation gas has sufficient pressure along with the design of the curtain container to cause the curtain  16  to break through the headliner  39  material and deploy. A sensor  74  is positioned in or around the vehicle  10  in such an orientation that is sensitive to any roll or yaw moments on the vehicle  10 . The sensor  74  sends a signal to the gas generator  38  to initiate “firing” of the gas generator. The gas generator  38  generates a gas that flows through the tubes  40  to the manifold system  37  and then through the inlet  34  into each cylindrical tube  30 . The gas generator  38  generates a gas pressure that is less than twenty-five psig, 170 Kpa, and the curtain or cushion  16  inflates and deploys in less than twenty-five milliseconds. This causes the tubes  30  to unwind, burst through the headliner  39  and extend down along the glass of the doors  18 ,  24 . By proper design of the manifold system  37 , all of the cylindrical tubes  30  fill substantially at the same time. As each tube  30  elongates, it tends to “pull” the adjacent tubes  30  down as well as having the gas drive them down along the windows  23  of the doors  18 ,  24 . 
     One embodiment of the cushion  16  is fabricated from a single panel of lightweight, low denier material  44 . One side  45  of the material  44  is coated with a gas retention material  46  for keeping the cushion  16  inflated for a desired period. The coated material  46  is a low permeability material and therefore the cushion  16  requires less gas than a higher permeability material that allows the gas to quickly escape through the material  44 . The inflation time is long enough so that cushions  16  stay inflated to protect the occupant, but short enough so that the cushion  16  is deflated quickly to allow the occupant to leave the vehicle  10 . 
     In one embodiment of the cushion  16 , the denier of the material  44  is not greater than  420  but, material  44  having denier not greater than  210  is contemplated. This lightweight material  44  reduces the overall weight of the curtain  16  in its rolled or folded position and reduces the storage volume necessary to retain the curtain  16 . 
     Typically, the curtain  16  is “Z” folded when it is stored behind the headliner  39 . The first curtain tether  31  is attached at one end to the last folded panel and the other end is positioned down along the “A” pillar. The second curtain tether  33  is attached at one end to the last folded panel and the other end is positioned down along the “C” pillar  22 . 
     The “Y” shaped tether  48  is illustrated in FIG.  8 . This tether  48  is typically used around the edges of the curtain  16  to form an enclosed bag as illustrated in section in FIGS. 2 and 3. The bag is enclosed with the sole exception that the manifold system  37  has an inlet  34  for receiving the inflation fluid from the gas generator  38 . In FIGS. 2 and 3, the sheet of material can be either a single sheet  44  or two  51 ,  52  separate sheets as hereinafter described. 
     To make a curtain of a multiple of cylindrical tubes  30 , one or more “X” shaped tethers  50  such as illustrated in FIGS. 4-6 are used. These “X” shaped tethers  50  are positioned on the inside surface  45  of the sheet  44  at the desired spacing required to have the desired number of tubes  30  for safety. In short, the number of tubes  30  and the spacing of the “X” shaped tethers  50  are a matter of design choice. 
     In one embodiment of the “Y” and “X” tethers  48 ,  50 , the denier of the material  44  is not greater than  420  but material having denier not greater than  210  is contemplated. 
     The “X” shaped tethers  50  are formed by first having a pair of sheet members  51 ,  52  overlying each other forming a strip  53 . The outside surfaces  54  of the sheet members  51 ,  52 , the surfaces not adjacent to each other, are coated with the gas retention material  46 . The sheet materials  51 ,  52  are a thermoplastic material compatible with ultrasonic or radio frequency welding. As illustrated in FIG. 4, a distance  56  from each edge is an area  58  that has a predetermined width. In this area  58  of material, the two sheets  51 ,  52  are bound together either by weaving, sewing or by bonding. When this process is completed, the cross-sectional view of the material is shown in FIG. 5 with an isometric view shown in FIG.  6 . The strips  53  are cut to length and are typically equally placed spaced between the folded panel  44  or overlying sheets, as hereinafter described, of the curtain  16 . Once in place, the curtain sheet member is then bonded to the arms of the “X” shaped tether  50 . 
     Referring to FIG. 7, the space  60  between the “X” shaped tethers defines the size of the cylindrical tubes. The “X” shaped tethers extend the complete length of the cushion or bag so that each cylindrical tube is sealed except for the inflation fluid inlet. 
     The “Y” shaped tethers are formed by bonding two pieces of material together forming the trunk portion of the “Y” and having the upper arms of the “Y” free. The material is first coated on the outside with the gas retention material in the same manner as the “X” shaped tether. As stated above, the edges of the sheet member are welded or bonded to the trunk and the top sheet is bonded or welded to one arm and the bottom sheet to the other arm. 
     Referring to FIG. 7, there is illustrated a pair of sheet members  51 ,  52  that overlie each other. In this embodiment, a plurality of different styles of tether members, both “X”  50  and “Y”  48  is fabricated. Each sheet has a gas retention material  46  coated on the outside surfaces. Starting from one edge  62 , a bonding  64  is formed to hold both sheets  51 ,  52  together. At a predetermined distance from this bonding  64 , a cut-line  66 A is formed on the outside of the sheets  51 ,  52 . Next, another bonding  64 B is made a second predetermined distance from the first cut-line  66 A. This distance is then replicated on the material downstream from bonding and another cut-line  66 B is formed. As we proceed downstream on the material, changing the widths of the boding and the distance from the bonding to the cut-lines can form different styles. Next the sheets  51 ,  52  are cut along the cut-lines  66 A,  66 B forming strips  53  of tether members  48 ,  50 . As illustrated in FIG. 9 if the bonding  64  is wide, this will provide large spaces between the cylindrical tubes  30  which is also usable in the fabrication of aircraft slides. 
     FIG. 2 illustrates a sectional view of the cushion  16  having the tethers  48 ,  50  formed by sewing  68  the tether material together and bonding the arms of the tethers to the outside surface  54  of the material  44 . FIG. 3 illustrates the cushion  16  having the tethers  48 ,  50  formed by bonding or welding the tether material together and bonding or welding the arms of the tethers to the outside surface  54  of the material. 
     FIG. 10 is another embodiment of the curtain  16  wherein the cylindrical tubes  30  are parallel to the door panel  28 . This is matter of design choice. 
     In FIGS. 1,  10  and  11 , the curtain  16  extends from the “A” pillar  14  to the “C” pillar  22 . It is obvious that such a curtain  16  can be fabricated to extend beyond the “C”  16  pillar to the next pillar or pillars. Around the “B”  20  and each pillar between the outside pillars, as far of material  44  are bonded together forming a flat member  70  to clear each pillar. In FIG. 10 depending on the design of the interior of the vehicle, a cylindrical tube  30  may be positioned along the roof rail  26 . 
     In FIG. 1, the vertical arrangement of the cylindrical tubes  30  aids to restrict the movement of the occupant toward the instrument panel  72 . 
     Typically, the curtain  16  is “Z” folded  76  when it is put into its stored location behind the headliner  39 . This is illustrated in FIG. 12, that is a sectional view from the roof, through the roof rail  26  and down along the glass  23  on the door  18 . The curtain is folded either by a “Z” fold  76  as illustrated in FIG. 12 or by a tuck-fold  78  as illustrated in FIG.  13 . The curtain  16  is fastened by means of a fastener  80  through a reinforced curtain-mounting flap  82  to the structure  86  of the vehicle. 
     Both folds, and any other folds used that are not a “Z” fold  76  or a tuck-fold  78 , have a similar characteristic in that the last fold  84  is facing downward toward the door  18 . In the “Z” fold, the last fold  84 , the outermost fold, is facing in the down position to ensure the proper downward and outward deployment. In the tuck-fold  78 , the last fold  84  is in the middle and it too is facing downward and outward to be directed along the glass  23  of the door  18 . 
     The curtain tethers  31 ,  33  have one end attached to the last folded panel  84  and the other end is positioned down along the outside pillars, located on the adjacent the ends of the inflated curtain  16 . As the inflation fluid fills the tubes  30 , the “Z” fold causes the bottom edge to deploy down the glass  23  of the doors  18 ,  24 , pulling the rest of the curtain. As the bottom edge moves downward, the curtain tethers  31 ,  33  are pulled from behind the covering of the pillars. As the tubes  30  fill with gas, covering of the pillars. As the tubes  30  fill with gas, the vertical curtain edges pull away from the pillars, in the direction of the arrows  88  in FIG. 11, and the curtain tethers  31 ,  33  begin to pull taut. As the tubes fill with gas, they expand and circumference of the tubes causes the length of the curtain, in the direction  88  of front to back, to shorten. The curtain tethers  31 ,  33  pull from the behind the covering of the pillars  14 ,  22  and remain taut keeping the curtain  16  in place. 
     There has thus been illustrated and explained an inflatable rollover curtain or cushion  16  for motor vehicles  10 . The curtain or cushion  16  is deployed according a predetermined amount, typically in degrees from the normal vertical axis of the vehicle  10 , of rollover or yaw as sensed by a crash sensor  74  in the vehicle. The crash sensor  74  senses a crash or a rollover of the vehicle and generates an activation signal. The activation signal activates the gas generator  38  to inflate and deploy the curtain  16  to protect the vehicle&#39;s occupants from extending out of or leaving the vehicle. 
     In addition, there is described a method to manufacture the curtain or cushion  16  and the “X”  50  and “Y”  48  shaped tethers. The materials of the cushion or curtain  16  and the tether members  48 ,  50  inside the cushion or curtain are described.