Abstract:
An airbag system for a vehicle includes an inflatable rear curtain airbag configured to deploy adjacent a rear window positioned between rear pillars in the vehicle, a housing for the rear curtain airbag, and an inflator to inflate the rear curtain airbag. The housing, rear curtain airbag, and inflator are mounted to a roof of the vehicle. The rear curtain airbag is configured to deploy to prevent ejection of an occupant out of the rear window and to prevent objects intruding through the rear window from contacting an occupant.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application No. 61/064,040, filed Feb. 12, 2008, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     The present disclosure relates generally to the field of vehicle airbags. More specifically, the present disclosure relates to a vehicle rear window curtain airbag. 
     Vehicle airbags are used to help protect vehicle occupants from injury in the event of a vehicle crash. Head Side Airbags (HSABs) or Side Curtain Airbags (SCABs) are provided in vehicles for protection of occupants during side impact collisions and are generally mounted in a vehicle through attachments to sheet metal at a roof rail location at either side of the vehicle, i.e., driver side and/or passenger side. 
     Many vehicles (i.e., minivans, sport utility vehicles, crossover vehicles, city cars, hatchbacks, pick-up trucks, etc) have substantially flat rear ends and include seating that is provided in close proximity to a rear window. In a rear collision, a vehicle or other object may intrude into the passenger compartment of the vehicle being struck. In such a collision, occupants of the rear-ended vehicle risk being struck with debris or objects entering the vehicle interior through the rear window, being struck by glass from a broken rear window, or may collide with the rear window, causing injuries to the head or upper extremities. Further, in collisions or rollover events, occupants may be ejected out of the vehicle through the rear window. 
     It would be advantageous to provide a curtain airbag proximate to the rear window of a vehicle to reduce the likelihood of injury to the occupant and reduce the likelihood the occupant will be ejected through the rear window. 
     SUMMARY 
     One embodiment of the disclosure relates to an airbag system for a vehicle. The airbag system comprises an inflatable rear curtain airbag configured to deploy adjacent a rear window positioned between rear pillars in the vehicle. The rear curtain airbag includes a plurality of vertical inflatable chambers. The airbag system further includes a housing for the rear curtain airbag and an inflator configured to provide inflation gas for inflating the rear curtain airbag. The rear curtain airbag is configured to extend between the rear pillars and cover the rear pillars and at least a majority of the rear window when fully deployed. 
     Another embodiment of the disclosure relates to an airbag system for a vehicle. The airbag system comprises an inflatable rear curtain airbag configured to deploy adjacent a rear window positioned between rear pillars in the vehicle. The rear curtain airbag includes a plurality of vertical inflatable chambers. The airbag system further includes a housing for the rear curtain airbag and an inflator configured to provide inflation gas for inflating the rear curtain airbag. 
     Another embodiment of the disclosure relates to an airbag system for a vehicle. The airbag system comprises an inflatable rear curtain airbag configured to deploy adjacent a rear window positioned between rear pillars in the vehicle. The rear curtain airbag includes an inflatable central region positioned between the rear pillars and first and second inflatable pillar lobes. Each of the first and second pillar lobes are positioned adjacent one of the rear pillars. The airbag system further includes a housing for the rear curtain airbag and an inflator configured to provide inflation gas for inflating the rear curtain airbag. The housing, rear curtain airbag, and inflator are mounted to a roof of the vehicle. The rear curtain airbag is configured to bend along a substantially vertically extending first bend line dividing the central region from the first pillar lobe. The rear curtain airbag is configured to bend along a substantially vertically extending second bend line dividing the central region from the second pillar lobe. 
     Yet another embodiment of the disclosure relates to an airbag system for a vehicle. The airbag system comprises an inflatable rear curtain airbag configured to deploy adjacent a rear window positioned between rear pillars in the vehicle, a housing for the rear curtain airbag, an inflator configured to provide inflation gas for inflating the rear curtain airbag, and an external deployment strap connected at one end to the rear curtain airbag. The deployment strap is configured to control a position of the rear curtain airbag when deployed. The airbag system further comprises a rear tether rod fixed to one of the rear pillars in the vehicle. A second end of the external deployment strap is connected to the rear tether rod and configured to slide along the rear tether rod during deployment of the rear curtain airbag. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects, and advantages of the present invention will become apparent from the following description, appended claims, and the accompanying exemplary embodiments shown in the drawings, which are briefly described below. 
         FIG. 1  is a perspective view of a vehicle illustrating support pillars for a frame of the vehicle, windows, and a storage location for a rear window curtain airbag according to an exemplary embodiment. 
         FIG. 2  is a front perspective view of a vehicle interior illustrating a rear window curtain airbag following deployment, according to an exemplary embodiment. 
         FIG. 3  is a top partial cross-section of the vehicle of  FIG. 2  taken along line  3 - 3  showing the rear window curtain airbag following deployment. 
         FIG. 4  is a detail cross-section of a left rear C-pillar for a vehicle showing a tether rod provided to control the deployment of a rear curtain airbag according to an exemplary embodiment. 
         FIG. 5  is an elevation view of a C-pillar for a vehicle according to an exemplary embodiment showing an external deployment strap and a tether rod. 
     
    
    
     DETAILED DESCRIPTION 
     Referring in general to  FIGS. 1-4 , a vehicle  10  is shown including a rear curtain airbag module  30  according to an exemplary embodiment. The rear curtain airbag module  30  is provided to help protect the occupants of the vehicle  10  in a collision or rollover event. Referring to  FIG. 1 , the vehicle  10  includes a plurality of vertical frame members located on both sides of the vehicle  10  that provide structural support for the windshields and windows. A first member (e.g., pillar, column, etc.), shown as A-pillar  12 , supports the front vehicle window; a second member, shown as B-pillar  14 , supports the side windows  22 ; and a third member, shown as C-pillar  16 , supports the rear window  20  of the vehicle. 
     The following disclosure uses “C-pillar” for convenience as a general term to refer to the rear-most vertical support pillar of the vehicle  10 . Some exemplary vehicles may have fewer than three support pillars on either side (i.e., a microcar) in which the B-pillar is the rear-most pillar. Some other exemplary vehicles may have more than three support pillars on either side (i.e., minivans, sport utility vehicles, etc.) in which the D-pillar or another additional pillar is the rear-most vertical support pillar. It should be understood by one skilled in the art that the rear curtain airbag module  30  described in the following disclosure may be used to provide protection for the rear-most support vertical support pillar in a wide variety of vehicles. 
     The airbag module  30  includes an inflator  32  and an inflatable curtain airbag or cushion  40 . The curtain airbag  40  is preferably stored along the roof  24  of the associated vehicle  10 , for example, along the vehicle roof rail  26  above the rear window  20  opening, in a conventional manner. According to an exemplary embodiment, the curtain airbag  40  includes a plurality of fabric tabs  42  ( FIG. 2 ) with which it is coupled to the rear roof rail  26 . The curtain airbag  40  is preferably secured in a folded state beneath a trim panel such as a headliner panel  18 . A weather strip trim piece may be provided to cover a gap between the headliner panel  18  and the rear roof rail  26 . According to another exemplary embodiment, the inflator  32  of the airbag module  30  is configured to be integrally mounted onto an interior vehicle part such as the automobile headliner panel  18 . 
     The inflator  32 , such as a conventional gas-filled inflator, supplies gas for inflation/deployment of the restraint curtain airbag  40 . An impact sensor (not shown in the FIGURES) located within the vehicle&#39;s control system is used to sense impact collisions. During a vehicle collision or rollover event, the inflator  32  is activated to supply pressurized gas to inflate the curtain airbag  40 . The inflation gas enters the curtain airbag  40  via the inflator&#39;s  32  outflow opening  33 , causing the curtain airbag  40  to emerge from underneath the headliner panel and be driven away from a storage position and downward into a deployed position. The outflow opening  33  and/or the inflator  32  is positioned approximately midway between the rear pillars of the vehicle proximate a lateral center of the rear curtain airbag  40 . 
     As shown best in  FIG. 2 , in the deployed position, the curtain airbag  40  is disposed between the occupant and the rear of the vehicle  10  and generally covers at least a portion of the opening for the rear window  20 . The curtain airbag  40  preferably covers the entire rear window  20 . 
     The curtain airbag  40  is generally formed from a first panel  44  (e.g., inboard panel, inner panel, front panel, etc.) and a second panel  46  (e.g., outboard panel, outer panel, rear panel, etc.) that are coupled together by a plurality of seams  48  and  50 . According to an exemplary embodiment, the first panel  44  and the second panel  46  are a nylon fabric or any other suitable material. The seams  48  and  50  may be formed as a sewn connection (e.g., with a thread), a woven connection, an adhesive connection, or any other suitable connection known in the art for coupling together two fabric panels. The curtain airbag  40  may be divided into two or more vertical compartments or chambers. Passages or ports are generally provided between individual chambers such that the chambers are in fluid communication with each other. Referring especially to  FIGS. 2-3 , the curtain airbag  40  comprises a first group of central (vertical) lobes or chambers  54  that are configured to cover the rear window  20  of the vehicle  10 , and at least two (vertical) side lobes or chambers  56  that are disposed to the side of the vehicle  10 , generally along the vehicle C-pillars  16 . The central vertical chambers  54  are arranged approximately symmetrical along the rear curtain airbag  40 . The seams  50  separating each side lobe  56  from the adjacent central chamber  54  are sometimes referred to as “zero depth tethers.” 
     The curtain airbag  40  also includes an inflation flow path (e.g.  55 ) at a top of the curtain airbag  40 . The inflation flow path  55  is a path for inflation gases to flow to inflate (fill) the vertical chambers  54  and side pillar lobes  56 . 
     The curtain airbag  40  may also have a multitude of un-inflated portions such as un-inflated portions that generally separate the chambers. One such un-inflated portion may comprise a panel  52  (e.g., sail panel) proximate to the side of the vehicle  10  (e.g., proximate to the C-pillar  16 ). The sail panel  52  is coupled, on one end, to the side roof rail  28  above the side window  22  and, on the opposite end, to the main body of the curtain airbag  40 . The sail panel  52  may be a separate fabric panel or may be integrally formed with one or both of the first panel  44  or second panel  46 . 
     Sail panels  52  help to stabilize the side chambers  56 . According to an exemplary embodiment, the sail panel  52  is coupled to the vehicle side roof rail  28  at one or more attachment points  53  (e.g., with fabric tabs). The sail panels  52  may be separate panels coupled to the side chambers  56  or may be formed integrally with the first panel  44  and/or the second panel  46  comprising the curtain airbag cushion  40 . In an alternative embodiment, the sail panels  52  can include inflatable chambers. 
     According to other exemplary embodiments, the side chambers  56  may be extended such that the side chambers  56  are disposed between the occupant and the side window  22 . The side chambers  56  then provide side impact and rollover protection for occupants seated in the rear row by being disposed both between the occupant and the C-pillar  16  and between the occupant and the side window  22 . Extending the side chambers  56  to provide coverage over the side windows  22  proximate to the rear row seating eliminates the need for a separate side curtain airbag to be extended to provide protection for occupants in the rear row. Extending the side chambers  56  may be desirable in vehicles with a longer wheelbase such as vans and sport utility vehicles. 
     In the event the impact sensor(s) detects a collision such as a rear impact or a rollover, the curtain airbag  40  deploys from behind the rear of the headliner  18  downward and across the rear window  20 . Additionally, the side lobes  56  extend to cover the C-pillars  16  of the vehicle  10  to provide additional protection for the vehicle occupants. The central chambers  54  and the side chambers  56  are arranged vertically. The central chambers  54  extend downward past the lower edge of the rear window  20 . 
     To follow the contour of the rear window  20  and the C pillars  16  of the vehicle  10 , the curtain airbag  40  is formed to be generally U-shaped when inflated, such that the side chambers  56  are arranged at an angle relative to the central chambers  54  (e.g., bent, folded, etc.). 
     Several mechanisms may be used to arrange the side chambers  56  at an angle relative to the central chambers  54  and bend along the C-pillars  16 . For example, the seams  50  separating the chambers  54  and  56  from each other may be located such that they are generally aligned with the C-pillars  16 . Therefore, when the airbag cushion  40  is inflated, the seam  50  provides a natural bend line for the side chambers  56  to bend relative to the central chambers  54 . Further, external deployment straps or tethers  58  may be located proximate to the edge of the transition between the rear window  20  and the C-pillars  16  to create bend lines between the side chambers  56  and the central chambers  54 . 
     As shown best in  FIGS. 4 and 5 , tethers  58  may be provided to apply lateral tension to the curtain airbag  40  and to direct the unfolding and deployment of the curtain airbag  40 . The tethers  58  are coupled to the second (outboard) panel  46  of the curtain airbag  40  and are configured to slide along elongated members or tether rods  34 . The tethers  58  comprise closed loops of preferably substantially flat, flexible material. The tethers  58  may be formed from a conventional textile material, or formed from some other suitable material such as nylon webbing, etc. In a preferred embodiment, the tethers  58  are affixed to the curtain airbag proximate to a lower edge along the seam lines  50  separating the side chambers  56  from the central chambers  54 . According to other exemplary embodiments, the tethers  58  may be alternatively positioned for other applications, for instance along the side or near the bottom corner of the cushion  40 . 
     The elongated members  34  (cords, rods, etc.) are coupled to the frame of the vehicle  10 , such as along C-pillars  16 . The elongated member  34  is preferably a rigid member that is affixed to the C-pillar  16  with brackets at either end. The tether  58  slidably engages the elongated member  34  during deployment. As the cushion  40  moves outward, preferably downward from the roof rails  26  and  28 , the expanding cushion  40  is guided by the tether  58 , as it slides along the elongated member  34 . The engagement of the tethers  58  and the elongated members  34  resists the tendency of the inflated curtain airbag  40  to pull away from the elongated members  34  and, thus, remain in close proximity to the rear window  20 . Thus, cooperation between the tether  58  and elongated member  34  during deployment assists in both positioning and tensioning the curtain airbag  40 , and provides lateral support thereto. As shown in  FIG. 4 , the elongate member  34  and tether  58  can extend from (attached to) the C-pillar  16  such that a portion of the elongate member  34  and tether  58  are positioned behind a trim panel  60  and/or additional trim piece  62  covering the C-pillar  16 . 
     By orienting the chambers  54  and  56  vertically, the curtain airbag  40  is better able to retain occupants in the vehicle  10 . The curtain airbag  40  is coupled to the elongated members  34  (e.g., with tethers  58 ) in an uninflated state. As the chambers  54  and  56  inflate, they shrink horizontally relative to the uninflated state and therefore cause the elongated members  34  and tethers  58  to apply a horizontal tension on the curtain airbag  40 . Horizontally arranged chambers, on the other hand, do not shrink as much horizontally upon inflation. 
     In an exemplary embodiment, the deployment of the rear window airbag module  20  can help trap airborne debris occurring from the collision. Additionally, in the event of a rollover, the airbag module  20  can function to limit the ejection of the upper extremity, body parts, or the entire body of an occupant from the rear of the vehicle  10 . 
     It is important to note that the construction and arrangement of the rear window curtain airbag as shown in the various exemplary embodiments are illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited in the description. For example, elements shown as integrally formed may be constructed of multiple parts or elements, the position of the elements may be reversed or otherwise varied, and the nature of number of discrete elements or positions may be altered or varied. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments.