Abstract:
A tether assembly attachable to an inflatable cushion airbag module is disclosed that is usable in vehicles including trucks, SUVs, and other vehicles with abrupt rear surfaces. The tether assembly does not require that the rear tether be extended back from the rear edge of the airbag. The tether assembly may be used in connection with an inflatable cushion airbag secured to the front portion of the vehicle using a standard front tether system. The tether assembly is attached via a sliding mechanism to a rear tether used to secure an inflatable cushion module airbag to an anchoring point within the vehicle. The sliding mechanism is also connected to a retractor, preferably through a flexible connector made of the webbing material used in seat belts. The tether assembly is configured so that when the inflatable cushion airbag deploys during an accident, the retractor supplies rearward tension on the airbag by causing the sliding mechanism to move along the path of the tether. This tension on the airbag prevents it from shifting from the position designated to give the occupant optimal protection against lateral impact and rollover. Preferably, the retractor does not supply tension to the airbag until after it has deployed. A locking mechanism can be attached to the retractor to prevent a reduction in the tension applied to the inflatable cushion by restraining motion of the sliding mechanism in a direction away from the retractor.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to inflatable safety cushion, or airbags, for vehicles. More specifically, the present invention relates to a method and apparatus for restraining side impact airbags to enhance protection against impact and occupant excursion.  
           [0003]    2. Description of Related Art  
           [0004]    The inclusion of inflatable safety restraint devices, or airbags, is now a legal requirement for many new vehicles. Airbags are typically installed in the steering wheel and in the dashboard on the passenger side of a car. In the event of an accident, an accelerometer within the vehicle measures the abnormal deceleration and triggers the explosion of pressurized gas from an inflator. Expanding gases from the inflator fill the airbags, which immediately inflate to protect the driver and/or a passenger from impact against the windshield, dashboard, and steering wheel.  
           [0005]    Side impact airbags have also been developed in response to the need for protection from impact against the side of the vehicle (also known as lateral impact). These airbags, which are commonly referred to as “inflatable cushions” or “inflatable curtains,” may be mounted in the vehicle over the doors, and may inflate during an accident to cover the windows, doors, and lateral surfaces of the vehicle. The inflatable cushion may also be connected to tethers that extend from the ends of the airbag to anchoring points within the vehicle. These tethers may exert tension on the inflated cushions to keep the cushions generally between the occupant and the lateral surface of the vehicle.  
           [0006]    However, tether systems known in the art have a number of disadvantages. First of all, many known tether systems require that the tether be extended longitudinally away from both ends of the inflatable cushion. Consequently, the front tether must be extended from the front end of the inflatable cushion toward the front of the vehicle and the rear tether must be extended from the rear end of the inflatable cushion toward the rear of the vehicle. Such a design is incompatible with most trucks and sport utility vehicles (“SUVs”) in which the passenger compartment of the vehicle ends abruptly behind a lateral surface over which it would be desirable to position a cushion. In these vehicles, there is typically insufficient space for tether extension rearward from the edge of the inflatable cushion.  
           [0007]    One of the main purposes in attaching a tethering system to an inflatable cushion is to protect the occupant by applying tension to the inflatable cushion so as to secure the inflatable cushion in the proper position. Without such tension, there is an inherent risk that the inflatable cushion will improperly inflate and injure the occupant. Additionally, during rollover conditions, if the inflatable cushion is not secured into the proper position via tethers, the motion of the occupant may force the inflatable cushion out of an open window, thereby eliminating any possible safety benefits of the inflatable cushion.  
           [0008]    While the tethering systems previously known in the art may mitigate some of these problems by tensioning the inflatable cushion, the tensioning force supplied by these systems is sufficient to disjoin the inflatable cushion from its mountings or cause that the inflatable cushion be positioned in a location that does not render the occupant with maximum impact protection.  
           [0009]    Using a force sufficient to disjoin or improperly move the inflatable cushion creates various problems. An obvious example of this is that if the inflatable cushion is disjoined from its mountings or improperly positioned, it will no longer be covering the lateral surface of the vehicle, thereby allowing the occupant to sustain injury due to impact against the surface of the vehicle. Likewise, if the inflatable cushion is disjoined from its mountings, it will likely fall on or near the occupant, possibly exposing the occupant to hot gases or toxic substances.  
           [0010]    Furthermore, side impact inflatable cushions are often classified according to the compaction process used to compact the inflatable cushion. In general, there are two different categories of cushions: those that are compacted by rolling and those that are compacted by accordion folding. However, many previously known tethering systems are designed for use with a specific compaction process and consequently, cannot be used with either a rolled or an accordion-folded inflatable cushion. Rather, a specific tethering system must often be designed for each type of inflatable cushion. As a result, the cost-effectiveness and interchangeability of known inflatable cushions have suffered somewhat.  
           [0011]    Additionally, many known inflatable cushions and tethering systems are not suitable to prevent occupant excursion. “Occupant excursion” occurs when the vehicle occupant is ejected from the vehicle, usually through an open door or window, during an accident. Obviously, occupant excursion can be very dangerous, especially during rollover conditions. However, since many known tethering systems can cause the inflatable cushion to be disjoined from its mountings, thereby exposing the window and door of the vehicle, these systems may not provide maximum protection against occupant excursion.  
           [0012]    Accordingly, a need exists for a novel tethering system that is suitable for use in vehicles that do not have sufficient interior space behind the inflatable cushion to extend a rear tether. Furthermore, a need exists for such a tethering system that does not require a volatile tensioning device that could improperly deploy and cause injury or impair operation of the inflatable cushion as well as provide maximum protection against occupant excursion.  
         SUMMARY OF THE INVENTION  
         [0013]    The apparatus of the present invention has been developed in response to the present state of the art of side impact airbags, and more particularly, in response to the problems associated with inclusion of rear tether systems in vehicles such as trucks and SUVs. In accordance with the invention embodied and broadly described herein, novel tether assemblies along with methods of installing and using such tether assemblies to provide enhanced side impact and rollover protection are disclosed.  
           [0014]    The novel systems and methods of the present invention may operate to allow tether systems to be used with side impact airbags in trucks and SUVs. Current tethering systems typically require that the rear tether be extended rear-ward from the rear edge of the window. However, in vehicles such as trucks and SUVs, there is often insufficient space to extend such a tether because the vehicle has an abrupt rear surface immediately rearward of the position at which the airbag is to be installed. By contrast, the current invention enables a manufacturer to use a tethering system for side impact airbags in trucks and SUVs because the rear tether does not have to be extended rearward from the rear edge of the airbag. Through the use of a sliding mechanism, a retractor, and a locking mechanism, the present invention may allow the rear tether to be extended in any direction, while providing the necessary tension.  
           [0015]    In one embodiment of the invention, a rear tether is attached at one end to the cushion and at the other end to a rear anchoring point within the vehicle. An intermediate portion of the tether may pass through a sliding mechanism. The intermediate portion of the tether may be configured such that the sliding mechanism can slide along the intermediate portion. The sliding mechanism may also be attached to a retractor configured to exert tension on the sliding mechanism, thereby pulling the intermediate portion toward the retractor. A locking mechanism adjacent to the retractor may ensure that the sliding mechanism cannot move away from the retractor and thereby release the tension on the airbag. The retractor and locking mechanism may thus operate in concert to supply the rear tether with the tension necessary to hold the deployed airbag in its proper place.  
           [0016]    In one embodiment of the invention, the retractor is connected to the sliding mechanism via a flexible connector. The retractor may draw the sliding mechanism toward the retractor taking up the flexible connector through simple winding or a similar process. The length of the flexible connector may be selected so that during deployment of the inflatable cushion, there is still slack in the flexible connector. It is only after deployment that the retractor fully removes the slack in the flexible connector. This configuration of the flexible connector may prevent the retractor from exerting a magnitude of force on the airbag that could damage the inflatable cushion during normal operation of the vehicle, disjoin the inflatable cushion from its mountings, or pull the inflatable cushion out of the position designed by the manufacturers to give maximum impact protection. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    In order that the manner in which the above-recited and other advantages and objects of the invention are obtained will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings only depict typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:  
         [0018]    [0018]FIG. 1 is a perspective view of a vehicle with a deployed inflatable cushion module according to the present invention including a rear tethering assembly configured to keep a cushion properly positioned for lateral impact protection.  
         [0019]    [0019]FIG. 2 is a side elevation view of the vehicle of FIG. 1, depicting the inflatable cushion module is in the stowed configuration.  
         [0020]    [0020]FIG. 3 is an enlarged view of one possible embodiment of the tethering assembly which may include the retractor, the locking mechanism, the flexible connector, and the sliding mechanism of FIG. 1.  
         [0021]    [0021]FIG. 4 is a side elevation view of the vehicle of FIG. 1 depicting the inflatable cushion module in a partially deployed configuration immediately after inflation, prior to complete take-up of the flexible connector.  
         [0022]    [0022]FIG. 5 is a side elevation view of the vehicle of FIG. 1 depicting the inflatable cushion module in a fully deployed configuration in which substantially all slack in the flexible connector has been removed to fully restrain the cushion in the proper position.  
         [0023]    [0023]FIG. 6 is a side elevation view of a vehicle depicting an embodiment of the invention in which a tether assembly similar to that of FIG. 5 is utilized in a front tethering system. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]    The presently preferred embodiments of the present invention will be best understood by reference to the drawings, wherein like parts are designated by numerals throughout. It will be readily understood that the components of the present invention, as generally described and illustrated in the Figures herein, may be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the apparatus, system, and method of the present invention, as represented by FIGS. 1 through 6, is not intended to limit the scope of the invention, as claimed, but is merely representative of presently preferred embodiments of the invention.  
         [0025]    Referring to FIG. 1, one possible embodiment of a tether assembly  10  incorporating the novel features of the present invention is shown. The tether assembly  10  may be situated within vehicle  11 , which need not be as shown, but may be any type of vehicle. The vehicle in the embodiment illustrated in the Figures is a truck of the type known in the art having a longitudinal direction  17 , a lateral direction  19 , and a transverse direction  21 . Specifically, FIG. 1 shows the tether assembly  10  attached to a vehicle that has a window  12 , a door  13 , a roof  14 , a lateral surface  15  encompassing window  12  and door  13 , an abrupt rear surface  16 , a floor (not shown), and a front portion  18 . A vehicle with “an abrupt rear surface” is a vehicle similar in shape to a truck or a SUV in that the rear surface of the vehicle is positioned proximate the rear edge of the windows.  
         [0026]    A “lateral surface” of a vehicle is the side portion of the vehicle which houses the doors and windows.  
         [0027]    Referring to FIG. 2 the tether assembly  10  is depicted as viewed from the inside of the vehicle  11 . A roof rail  20  may be positioned at the junction of door  13  with the roof  14 . A “roof rail” is a post or beam and positioned on the inside of the vehicle&#39;s roof. Also, within vehicle  1 , there may be an armrest  26  and a latch  28  that opens the door  13 , both positioned on the door  13 . Adjacent to the door  13  is a seat  30 , which has an upright portion  31 , and a bottom portion  32 . In the embodiment of the invention depicted in FIG. 2 the seat  30  is shown is a bucket seat as known in the art. However, the invention is not limited to this embodiment as different embodiments will use the invention with other types of seats known in the art, including, but not limited to benches, bucket seats, and child seats.  
         [0028]    Trim  36  is placed on lateral surface  15  above and forward of window the  12  to improve the appearance of the interior of vehicle  11 . If desired, multiple trim segments may be positioned above and forward of the window  12 , in place of trim  36 . Corresponding trim  37  may be placed on lateral surface  15  behind window  12 . The trim  36 ,  37  may be made of plastic, vinyl, or other materials known or used in the art. Various airbag components may be concealed behind the trim  36 ,  37  in a manner that will be described subsequently.  
         [0029]    An inflatable cushion  44  may be attached to lateral surface  15  proximate the roof rail  20  via fasteners  46  above window  12  and door  13 . The inflatable cushion  44  may be of any kind known in the art and may be constituted of any flexible substantially gastight material. This cushion  44  may have two distinct configurations: a stowed configuration as depicted in FIG. 2 and a deployed configuration as shown by FIGS. 3 and 4 in which the cushion  44  is disposed to cover a portion of the lateral surface  15  beside a vehicle occupant.  
         [0030]    In the stowed configuration, the inflatable cushion  44  may have a thin shape that can be stored compactly above door  13 ; the length of the bag may span most of the longitudinal length of the lateral surface  15 . In the deployed configuration, the inflatable cushion  44  may be filled with gas and may extend to cover a portion of the lateral surface  15 , including a portion of the door  13  and the window  12  to provide lateral impact protection to the occupant during an accident by tending to keep the occupant from passing through a protection plane. A “protection plane” is an imaginary vertical plane extending from the roof rail  20  to the floor of the vehicle parallel and adjacent to the lateral surface  15 . Specifically, the protection plane of vehicle  11  lies between the lateral surface  15  and the inflatable cushion  44  in the deployed configuration. If an occupant positioned on the seat  30  passes through the protection plane during an accident or rollover, he or she will impact the lateral surface  15 , including the door  13  or the window  12 . Hence, the purpose of the inflatable cushion  44  is to inflate during an accident or rollover so that the occupant impacts the inflatable cushion  44  and does not reach, let alone pass through, the protection plane.  
         [0031]    The dimensions and positioning of inflatable cushion  44  my be selected so as to render maximum lateral impact protection for the occupant when the cushion  44  deploys. Those of skill in the art will recognize that the dimensions, placement, and deployment characteristics of the cushion  44  may be altered in a number of ways to provide optimal protection for occupants of the vehicle  11 .  
         [0032]    The inflatable cushion module  10  deploys to move from the stowed configuration. Specifically, if the vehicle  11  is in an accident, a rapid change of acceleration will occur. This change may be detected by an accelerometer  47  which signals an inflator  48  to deploy. The inflator  48  is attached to inflatable cushion  44  at inflation point  49 . In the example of FIG. 2, the inflator  48  may be disposed partially within an inlet port of the inflatable cushion  44 . Accelerometer  47  can signal inflator  48  through various ways known in the art. One possible method of signaling is by using an electric signal carried by an electric wire  50 , as depicted in FIG. 2.  
         [0033]    The inflator  48  may be of the type known in the art. Specifically, the inflator  48  may take the form of any device that can rapidly produce sufficient gas to fill inflatable cushion  44 . Thus, when the inflator  48  receives the signal from the accelerometer  47 , the inflator  48  produces gases that enter the inflatable cushion  44  through the inflation point  49 . The entering gases cause inflatable cushion  44  to inflate and expand into the deployed configuration, which inflatable cushion  44  tends to keep the occupant from passing through the protection plane.  
         [0034]    The inflation point  49  can be located anywhere on inflatable cushion  44 . In the configuration of FIG. 2, the inflation point  49  is located proximate the rear edge of inflatable cushion  44 . However, in different embodiments of the invention, the location of the inflation point  49  my be different. All of these embodiments are contemplated by the present invention.  
         [0035]    The fasteners  46  used to attach the inflatable cushion  44  to the lateral surface  15  can be selected from any of the types of fasteners The fasteners  46  may for example, be tabs, tethers, wire restraints, screws, nails, bolts, clips, clamps, rivets, and/or other members designed to connect the inflatable cushion  44  to the vehicle  11 . FIG. 2 depicts the use of tabs in conjunction with rigid fasteners such as screws or bolts. The number and arrangement of fasteners  46  used to attach the inflatable cushion  44  to the vehicle  11  is not restricted to the embodiment of FIG. 2 which depicts five fasteners  46  securing the inflatable cushion  44  to the roof rail  20 . Other embodiments will attach the inflatable cushion  44  with a different number arrangement, and/or type of fasteners.  
         [0036]    A front attachment point  53  is also located on the inflatable cushion  44 . The front attachment point  53  connects the inflatable cushion  44  to the front tether  54 . The front attachment point  53  may be positioned anywhere on the forward portion of the inflatable cushion  44 . Alternative embodiments of the invention may position the front attachment point  53  differently than shown in FIG. 2.  
         [0037]    A front tether  54  may be attached at one end to the front attachment point  53 . The other end of the front tether  54  is attached to a front anchoring point  56 , which may be positioned at various locations in the interior of the vehicle  11 . The embodiment of FIG. 2 has the front anchoring point  56  in a position forward of the inflatable cushion  44  on the lateral surface  15 .  
         [0038]    Moreover, as shown in FIG. 2, the front tether  54  and the front anchoring point  56  may be positioned so as to be covered by trim  36  when the inflatable cushion  44  is in the stowed configuration.  
         [0039]    A rear tether attachment point  60  of the inflatable cushion  44  may also be connected to a rear tether  61  at first end  62 . Rear attachment point  60  may be positioned anywhere on the rear portion of the inflatable cushion  44 . In the configuration of FIG. 2, the rear attachment point  60  is located proximate a bottom edge of the inflatable cushion  44 . Since the inflatable cushion  44  gas been compacted along the roof rail  20 , the rear attachment point  20  is also located along the roof rail  20  when the inflatable cushion  44  is in the stowed configuration, as shown in FIG. 2.  
         [0040]    The rear tether  61  extends along a tether path  66  to a second end  63 , which is connected to rear anchoring point  64 . The “tether path” refers to the pathway along which the length of the tether  61  is disposed between the rear attachment point  60  and the rear anchoring point  64 . The rear anchoring point  64  may be located at a variety of positions inside of the vehicle  11  rearward of the inflatable cushion  44 . In the embodiment of FIG. 2, the rear anchoring point  64  is located on a surface  69  substantially rearward of the lateral surface  15  and is covered by the trim  37  that covers the rear tether  61 . A “surface substantially rearward” means a majority of the surface is positioned closer to the abrupt rear surface of the vehicle than is lateral surface  15 . Other embodiments include positioning the rear anchoring point  64  proximate the roof rail  20  or on the abrupt rear surface  16 .  
         [0041]    The rear tether  61  may have an intermediate portion  65  between first end  62  and second end  63  of rear tether  61 . The intermediate portion  65  may be coupled to a tensioning system  68  configured to exert pressure on the intermediate portion  65  of the rear tether  61  such that a substantial portion of the tension transmitted by the rear tether  61  to the inflatable cushion  44  is in the longitudinal direction  17 . Thus in one embodiment of the invention, when the inflatable cushion  44  is in the deployed configuration, the tension transmitted by the rear tether  61  is directed rearward of the occupant approximately the height of the occupant&#39;s waistline. The front tether  54  may similarly exert a force in the longitudinal direction at the height of the occupant&#39;s waistline, so that the front and rear tethers  54 ,  61  cooperate to keep the inflatable cushion  44  in place.  
         [0042]    The tensioning system  68  comprises a sliding mechanism  70  that slidably engages the intermediate portion  65  of the rear tether  61  and a retractor  76 . “Slidably connected” or “slidably engaged” means that sliding mechanism  70  can slide or move along the tether path  66  of the rear tether  61 .  
         [0043]    The sliding mechanism  70  may comprise any device that can slide or move along the tether path  66 . In one embodiment, the sliding mechanism  70  comprises a series of rollers (not shown) configured so that intermediate portion  65  passes between the rollers and allows the rollers to slide along the rear tether  61 . In another embodiment of the invention, sliding mechanism  70  comprises a flexible loop (not shown) that encircles the intermediate portion  65  with clearance so that the flexible loop is along the rear tether  61 . In the embodiment FIG. 2, the sliding mechanism  70  is a ring through which the intermediate portion  65  passes relatively freely to allow the ring to move along the rear tether  61 . Additionally, the ring accommodates twisting of the rear tether  61 .  
         [0044]    By employing a sliding mechanism  70  configured to permit twisting of the rear tether  61 , the rear tether assembly  10  overcomes a weakness of known tethering systems in that the rear tether assembly  10  can be used with various types of side impact airbags. The use of the sliding mechanism  70  compensates for any twisting of the rear tether  61  that occurs during deployment. Thus, as depicted in FIG. 2, the inflatable cushion  44  may be compacted by rolling or may be compacted by accordion folding or in some other manner.  
         [0045]    The sliding mechanism  70  may be attached to the retractor  76  such that the retractor  76  exerts tension on the sliding mechanism  70  to urge the sliding mechanism  70  away from the inflatable cushion  44 . The retractor  76  is connected to a surface of the vehicle  11 , such as the surface  69 , via fasteners (not shown) that may provide rigid attachment or may pivotally attach the retractor  76  to the surface  69  so that the retractor  76  is able to rotate during deployment of the inflatable cushion  44 .  
         [0046]    In the embodiment of FIG. 2, the retractor  76  is positioned on the surface  69  below the sliding mechanism  70  and is covered by the trim  37 . However, the retractor  76  may be located at different positions within the vehicle  11  so long as the retractor  76  retains its capacity to exert tension on the sliding mechanism  70  to keep the inflatable cushion  44  in the proper position.  
         [0047]    The sliding mechanism  70  may be attached to the retractor  76  via a flexible connector  80 . The flexible connector  80  can be composed of various materials including chains, braided fiber or polymer based ropes, a webbing material known in the art as the material used to make seatbelts, or cables substantially composed of metallic material. FIG. 2 shows use of the webbing material.  
         [0048]    The flexible connector  80  may be attached to the retractor  76  in such a way that the retractor  76  can exert rearward tension on flexible connector  80 , which in turn exerts rearward tension on the sliding mechanism  70 . The retractor  76  may be any device capable of exerting tension on the flexible connector  80 . As will be demonstrated subsequently, the retractor  76  need not provide a force large enough to pull the inflatable cushion  44  into the deployed configuration. Thus the retractor  76  may be substantially composed of a comparatively lightweight material such as plastic.  
         [0049]    Referring to FIG. 3, the retractor  76  of FIGS. 1 and 2 is illustrated. The flexible connector  80  may be attached to a rotationally biased spindle  82  that is configured to rotate and wind the flexible connector  80  onto itself. The rotationally biased spindle  82  may be driven by any biasing member (not shown) including linear springs, torsional springs, leaf springs, gas springs and the like. As the rotationally biased spindle  82  winds the flexible connector  80 , the effective length of the flexible connector  80  is shortened, thereby drawing the sliding mechanism  70  towards the retractor  76 .  
         [0050]    As shown in FIG. 3, a locking mechanism  88  is also provided. The locking mechanism  88  may be located anywhere along the flexible connector  80 ; as shown, the locking mechanism  88  may be positioned directly adjacent to the retractor  76  so that the locking mechanism  88  and the retractor  76  are attached together. If desired, the retractor  76  and the locking mechanism may even share a common housing.  
         [0051]    The locking mechanism  88  may act to prevent sliding mechanism  70  from moving away from the retractor  76  by preventing withdrawal of the flexible connector  80  from the retractor  76 . In the embodiment shown in FIG. 3, the locking mechanism  88  comprises engagement members  90  and  91  positioned such that the flexible connector  80  passes between and makes contact with the engagement members  90  and  91 . The engagement member  91  may have gripping teeth  92  that allow the flexible connector  80  to move in a direction that corresponds to movement of sliding mechanism  70  towards retractor  76 , but does not allow the flexible connector  80  to move in the opposite direction. In this embodiment, the locking mechanism  88  may only allow the flexible connector  80  to extend away from the retractor  76  a short distance, such as about 10 millimeters or less.  
         [0052]    In place of the locking mechanism  88  shown in FIG. 3, alternative structures that provide similar function may be used. For example, a ratchet mechanism may be used in place of the engagement members  90 ,  91 . The ratchet mechanism may include a gear (not shown) coupled to the rotationally biased spindle  82  and a blocking member (not shown) adjacent to the gear. The blocking member may mesh with teeth of the gear to impede rotation of the rotationally biased spindle  82  in a direction that would permit withdrawal of the flexible connector  80  from the retractor  76 .  
         [0053]    Referring to FIG. 4, the inflatable cushion  44  is shown in a partially deployed configuration. More specifically, the inflatable cushion  44  has inflated fully so that part of front thether  54  is not covered by the trim  36 . However the flexible connector  80  has not yet been fully taken up by the retractor  76 . The length of flexible connector  80  and the take up force of the retractor  76  are configured so that directly after deployment of the inflatable cushion  44  some slack is still present in the flexible connector  80 . “Deployment” of the inflatable cushion  44  is defined to be the process, triggered by the inflation event, in which the inflatable cushion  44  expands, fills with gases, and becomes properly positioned so as to prevent the occupant from passing through the protection plane of the vehicle  11 . Only after the inflatable cushion  44  fully inflates does the retractor  76  finish winding the flexible connector  80  so that the slack is removed from the flexible connector  80 .  
         [0054]    Referring to FIG. 5, the inflatable cushion  44  is shown in the deployed configuration, in which all slack in the flexible connector  80  has been fully taken up by retractor  76 . As such, the tension supplied to the rear tether  61  will be at a height approximate the occupant&#39;s waistline. By placing the supplied tension at the occupant&#39;s waistline, the tensioning system  68  ensures that the inflatable cushion  44  covers all of window  12 . Moreover, supplying the tension at the occupant&#39;s waistline ensures that both the top and bottom of the inflatable cushion  44  are secured into proper position, thereby rendering optimum stability for the inflatable cushion  44  and preventing the inflatable cushion  44  from being disjoined from its mountings.  
         [0055]    The rear tether assembly  10  provides safer and more effective inflation by permitting slack to remain in the flexible connector  80  during inflation of the inflatable cushion  44 . If the rear tether  61  were tightly tensioned during inflation of the inflatable cushion  44 , the tension could pull on the inflating inflatable cushion  44  in such a way that the inflatable cushion  44  would be disjoined from its mounting or moved from the location at which it would provide maximum impact protection. Furthermore, if the inflatable cushion  44  were to inflate under tension in the longitudinal direction  17 , the inflatable cushion  44  could be pinched such that full inflation of inflatable cushion  44  would not occur. By allowing slack to remain in the flexible connector  80  until after the inflation event, the present invention is able to apply tension to the inflatable cushion  44  so as to hold it in the proper position while avoiding the problems described above.  
         [0056]    Although it is desirable for the retractor  76  to operate slowly enough to permit inflation prior to the application of tension, it is also desirable for the slack in the flexible connector  80  to be removed prior to impact of the occupant against the inflatable cushion  44 . Since the force applied by the retractor  76  is comparatively small, some mechanism is needed to ensure that the rear tether  61  is tightened prior to impact. The arrangement of the flexible connector  80  with respect to the rear tether  61  provides such a function.  
         [0057]    More specifically, the tension exerted by the retractor  76  on the flexible connector  80  causes the motion of the first end  62  toward the sliding mechanism  70  to be comparatively more rapid than the motion of the sliding mechanism  70  toward the retractor  76 .  
         [0058]    Thus, the effect of the connection between the sliding mechanism  70  and the rear tether  61  is to provide a mechanical disadvantage that operates between the retractor  76  and the first end  62 . A comparatively smaller force is exerted on the first end  62 , but a comparatively large displacement occurs. As a result, the retractor  76  is able to tighten the rear tether  61  prior to impact of the vehicle occupant against the inflatable cushion  44 . One of the effects of having the retractor  76  tighten the rear tether  61  prior to impact is that the tension on rear tether  61  is supplied by the occupant impacting the inflatable cushion  44 , which is useful to prevent kinks or closures from entering the inflatable cushion  44  which can prevent the inflatable cushion  44  from deploying properly.  
         [0059]    Referring to FIG. 6, a front tether assembly  110  may be incorporated into a vehicle such as the vehicle  11  of FIG. 1. The front tethering assembly may transmit tension from the front end of the inflatable cushion  44  in a forward direction at the height of the occupant&#39;s waistline. Front tether assembly  110  operates in a similarly to rear tethering assembly  10 . For example, after the inflatable cushion  44  deploys, slack remains in the flexible connector  80 . The retractor  76  then takes up this slack by winding flexible connector  80 , thereby permitting the occupant to supply tension to the front tether assembly  110  upon impact with the inflatable cushion  44 .  
         [0060]    Many of the problems associated with prior art tethering assemblies are addressed by the teachings of the present invention. From the above discussion, it will be appreciated that the present invention provides novel tether assemblies that allow side impact airbags to be more efficiently used especially in vehicles such as SUVs and trucks that have an abrupt rear surface that might otherwise inhibit airbag operation. The present tether assemblies also provide a mode whereby the airbag can be properly positioned such that the occupant receives maximum impact protection, without having the risk that the airbag will be disjoined from its mountings during the inflation event. Moreover, by positioning the airbag is properly positioned so as to provide the occupant with maximum impact protection, the present tether assemblies prevent occupant excursion during an accident.  
         [0061]    The present invention may be embodied in other specific forms without departing from its structures, methods, or other essential characteristics as broadly described herein and claimed hereinafter. The described embodiments are not to be considered in all respects only as illustrative, and not as restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.