Abstract:
An air bag assembly utilizing a releasable anchoring structure operatively connected to one or more extendible tethering elements and providing adjustable cushion depth. A displaceable support element selectively engages or disengages the anchoring structure during operation of the vehicle taking into account steady-state inputs such as vehicle velocity, occupant size, seating position, and seat-belt use. The displaceable support element may be automatically engaged or disengaged from the anchoring structure as occupant and/or driving conditions change prior to actual air bag deployment.

Description:
TECHNICAL FIELD 
     The present invention relates generally to an air bag assembly. More specifically, the present invention relates to an air bag assembly utilizing one or more extendible tethering elements providing adjustable cushion depth. The tethering elements are held in anchored relation to a support structure adapted to be selectively secured against withdrawal during air bag deployment depending upon vehicle and occupant conditions. 
     BACKGROUND OF THE INVENTION 
     It is well known to provide an air bag assembly including an inflatable cushion for protecting one or more occupants of a transportation vehicle. In an automotive vehicle, such air bag assemblies are typically positioned within the hub of the steering wheel and within a recess in the instrument panel so as to protect occupants seated in opposing relation to such assemblies. Additional air bag assemblies may be positioned within the seats and/or door panels of the vehicle for protecting the occupants during a side-impact event. It is also known to use inflatable curtain-like structures for deployment from the structural pillars and/or roof-area of the vehicle, promoting the restraint and protection of the occupants during a roll-over event. 
     An air bag assembly typically includes an inflatable cushion in fluid communication with a gas-emitting inflator. Upon sensing predetermined vehicle conditions, such as a given level of vehicle deceleration, the inflator discharges a fixed amount of gas, thereby forcing the cushion into a deployed position. The gas occupies the available volume within the cushion, thereby forcing the cushion to expand outwardly to the extent permitted by its construction. As an occupant comes into contact with the inflated cushion, the gas is forced out of the air bag, thereby dissipating the kinetic energy of the occupant and achieving a so-called “ride-down” effect. 
     It has been recognized that in some instances it may be desirable to adjust the inflation characteristics of the air bag to reflect the nature of the impact event, the size of the occupant (height and/or weight), the seating position of the occupant, and/or the seat-belt use/non-use of the occupant to be protected. In order to provide a degree of control over the pressure within the air bag, it is known to use an inflator that has varying levels or stages of gas output associated with the sensing of different vehicle and/or occupant conditions. Thus, it is known to utilize so-called “dual-stage” inflators. These dual-stage inflators, however, are more complex than typical inflators and are capable of providing only discrete levels of gas output. 
     In order to provide additional control over the inflation characteristics of the air bag it has been suggested to utilize extendible tethering elements in the form of straps or webs spanning the surfaces of the air bag that may be released from a first restrained operative length to a second extended operative length upon the occurrence of vehicle and/or occupant conditions warranting an increased air bag profile. It has also been suggested to utilize cushions that incorporate sewn or woven seams to control the expanded geometry of the air bag, wherein the seams may separate upon the introduction of pressures exceeding a predetermined level, thereby freeing the cushion from restraints imposed by the seams at lower pressures. 
     SUMMARY OF THE INVENTION 
     The present invention provides advantages and alternatives over the prior art by providing an air bag assembly utilizing a releasable bracket structure operatively connected to one or more extendable tethering elements and providing adjustable cushion depth. A release element selectively engages or disengages the bracket structure during operation of the vehicle taking into account steady-state inputs such as occupant size, seating position, and seat-belt use. The release element may be automatically engaged or disengaged from the bracket as occupant and/or driving conditions change prior to actual air bag deployment. 
     According to one aspect of the invention, an air bag assembly operable for providing the cushioning restraint of a vehicle occupant during an impact event is provided. The air bag assembly includes an inflatable air bag cushion having a first expanded profile and a second expanded profile, wherein the first expanded profile is characterized by relatively less air bag cushion depth than the second expanded profile. The air bag assembly also includes a tethering element coupled to the air bag cushion, wherein the tethering element has a first configuration associated with the first expanded profile of the air bag cushion and a second configuration associated with the second expanded profile of the air bag cushion. The air bag assembly further includes a restraining assembly operatively coupled to the tethering element, wherein the restraining assembly is operable for selectively enabling/disabling the first configuration and the second configuration of the tethering element based upon steady state conditions of the vehicle and occupant to be protected. 
     Advantageously, the air bag assembly of the present invention provides a relatively simple, cost-effective, and highly reproducible mechanism for controlling and adjusting the inflation characteristics of an air bag cushion. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will now be described by way of example only, with reference to the accompanying drawings which constitute a portion of the specification herein and in which: 
     FIG. 1 is a cut-away view of a vehicle interior showing an exemplary embodiment of an air bag cushion in an undeployed, stored state in opposing relation to a vehicle occupant; 
     FIG. 2 illustrates an exemplary embodiment of an arrangement of profile-restricting tethers of variable effective length in an air bag cushion held in a shortened operative condition; 
     FIG. 2A is a view similar to FIG. 2 with the tethers in an extended operative condition; 
     FIG. 3 illustrates an embodiment of the air bag assembly of the present invention, including a solenoid-actuated pin that selectively anchors a releasable bracket assembly relative to a module housing; 
     FIG. 4 is a cross-sectional view taken trough the module housing showing the releasable bracket assembly positioned within a wall of the housing; 
     FIG. 5 is a view taken generally along line  5 — 5  in FIG. 3, illustrating the releasable bracket assembly in anchored position; 
     FIG. 6 illustrates an alternative bracket release assembly for use in selectively adjusting venting through the module housing in conjunction with bracket release wherein the bracket is secured in place and with vents open; and 
     FIG. 7 is a view similar to FIG. 6 with the bracket assembly in a released condition and with vents closed. 
    
    
     While the present invention has been illustrated and generally described above and will hereinafter be described in conjunction with certain potentially preferred embodiments, procedures, and practices, it is to be understood that in no case is the invention to be limited to such illustrated and described embodiments, procedures, and practices. On the contrary, it is intended that the present invention shall extend to all alternatives, modifications, and equivalents as may embrace the principles of the present invention within the true scope and spirit thereof. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Reference will now be made to the drawings, wherein, to the extent possible, like reference numerals are utilized to designate like components throughout the various views. 
     Referring to FIG. 1, it is seen that a vehicle  10  may include a seating structure  12  that supports an occupant  14  positioned in generally opposing relation to a dashboard panel  16 . An inflatable air bag cushion  20  may be positioned partially or wholly within the dashboard panel  16  for outward deployment towards the occupant  14  in the event of a collision or the like. 
     While the air bag cushion  20  is illustrated for descriptive purposes in relation to a vehicle passenger, it is to be understood that the present invention is in no way intended to be limited to a passenger-side configuration. On the contrary, it is contemplated that the present invention may have equal applicability to air bag deployment in opposing relation to a vehicle operator (not shown) from a steering column (not shown), as well as in relation to air bags deployed from other regions within the interior of the vehicle  10 , including, by way of example, side-impact air bags and inflatable curtain structures. 
     It is contemplated that the interior of the vehicle  10  may include a seat position sensor  22  operable for detecting the position of the seating structure  12  and the occupant  14  relative to the dashboard panel  16 . It is also contemplated that the interior of the vehicle  10  may include additional position sensors, such as an optical sensor  24  or the like, operable for measuring the volume and/or position of the occupant  14  to be protected. It is further contemplated that the interior of the vehicle  10  may include a scale  26  disposed within the seating structure  12  operable for providing additional data regarding the mass of the occupant  14  and thus the load to which the inflatable air bag cushion  20  may be subjected. The seating structure  12  may also include one or more sensors (not shown) operable for measuring the degree to which the seating structure  12  is reclined. The interior of the vehicle  10  may still further include one or more sensors (not shown) operable for determining and communicating whether or not the occupant  14  is utilizing recommended seatbelt structures  28 . The data so collected may be communicated to a controller  27  to determine desirable expanded profile and venting characteristics for the air bag cushion  20 . 
     According to one embodiment of the present invention, the air bag cushion  20  has at least a first expanded profile and a second expanded profile that is characterized by relatively greater depth and volume than the first expanded profile. One or more extendible tethering elements  30  (FIG. 2) in the form of straps, cords or webs may be utilized to control the inflated profile of the air bag cushion  20 . 
     Referring to FIG. 2, the air bag cushion  20  is housed in fluid communication with a gas emitting inflator  40  such that upon expulsion of inflation gas by the inflator  40 , the air bag cushion  30  inflates to an expanded cushioning condition. In order to contour the shape of the air bag cushion  30 , one or more extendible tethering elements  30  are disposed across the interior of the air bag cushion  20  and may extend in a travel path between one or more fixed points of connection  25  at the surface of the air bag cushion  20 . The tethering elements  30  may also be connected to the surface of the air bag cushion  20  at one or more predetermined positions along the travel path by one or more guide elements  29 , such as at an impact face portion  31  of the air bag cushion  20 . As illustrated in FIG. 2, the operative length of the tethering elements  30  may be shortened by drawing a portion of the tethering elements  30  intermediate the fixed points of connection  25  towards an anchoring structure  80  normally held at a supported fixed position remote from the air bag cushion  20 . 
     The anchoring structure  80  may be selectively released or retained at its normal supported fixed position at the time of deployment of the air bag cushion  20  based upon the preferred profile of the air bag cushion  20  in light of the measured occupant and vehicle conditions. That is, if the physical character and position of the occupant  14  in combination with the nature of the impact are such that a deep profile is desired, then the anchoring structure  80  and attached tethering elements  30  are released from their supported fixed position thereby permitting the air bag cushion  20  to assume an expanded profile of increased depth (FIG.  2 A). Conversely, if the physical character and position of the occupant  14  in combination with the nature of the impact are such that a shallow profile is desired, then the anchoring structure  80  and attached tethering elements remain in a static anchored position thereby restraining the air bag cushion  20  to a final profile of decreased depth (FIG.  2 ). 
     As indicated, the selective enabling/disabling of the increased and decreased profiles is preferably carried out taking into account steady-state inputs such as vehicle velocity, occupant size, occupant mass, seating position, and seat-belt use. According to the potentially preferred practice, it is contemplated that the tethering elements  30  may remain connected to the one more points of connection  25  across the surface of the air bag cushion  20 . Likewise, the anchoring structure  80  may be held by a mooring line  35  secured to a fixed position of attachment remote from the anchoring structure. Such connections provide for the continued restraint of the air bag cushion  20  by the tethering elements  30  even if the anchoring structure  80  is released. That is, even with an increased operating depth, the tethering elements  30  may continue to contour the profile of the air bag cushion  20 . In addition, the anchoring structure is also prevented from moving into contact with the face portion  31 . 
     Referring simultaneously to FIGS. 3 and 4, in one embodiment of the present invention, a tethering element  30  is connected to an anchoring structure  80  including a first plate  82 , a second plate  84 , and a third plate  86 . The first plate  82 , the second plate  84 , and the third plate  86  may be made of, for example, a metal, a plastic, rubber, a composite material, or the like. The first plate  82  is positioned adjacent to a slot  88  (FIG. 3) disposed within the side portion  90  of a module housing  92 . The second plate  84  is disposed within a fold in the tethering element  30  and the third plate  86  is positioned adjacent to the tethering element  30  distal to the inner surface  94  of the module housing  92  (FIG.  4 ). The first plate  82 , the second plate  84 , and the third plate  86  are connected via one or more fasteners  96  such as pins or the like inserted through the three structures and, optionally, through the tethering element  30 . In the illustrated arrangement, a portion of the tethering element extends away from the anchoring structure  80  to define a mooring line  35  held at a fixed position remote from the anchoring structure  80 . Of course, a separate element such as a strap, cord, wire or the like operatively secured to the tethering element and/or the anchoring structure may likewise be used to form the mooring line  35  if desired. As will be appreciated, while one exemplary attachment arrangement has been shown, any arrangement suitable for anchoring the tethering element  30  may be used. 
     According to the illustrated exemplary configuration, the anchoring structure  80  includes an outwardly projecting planar release bracket  98  normally protruding through the slot  88  disposed within the side portion  90  of the module housing. As best seen in FIG. 5, in the illustrated embodiment the release bracket  98  is connected to the first plate  82  in a substantially “T” shaped geometric arrangement. The release bracket  98  may be made of a structural material such as plastic, metal or the like. The release bracket  98  preferably includes a plurality of holes  100 ,  104  suitable for receiving one or more pins, as described in greater detail hereinafter. By way of example only, in the exemplary embodiment illustrated, the release bracket  98  includes a primary pin hole  100  suitable for receiving a selectively extendible and retractable primary pin  102  and one or more shear pin holes  104  suitable for receiving one or more shear pins  106 . Preferably, the release bracket  98  is shaped such that it may freely pass in sliding relation through the slot  88  disposed within the side portion  90  of the module housing  92 . 
     As best seen in FIGS. 3 and 5, the slot  88  is adapted to accept the release bracket  98  between a first retention bracket  108  and a second retention bracket  10  fixedly attached to the side portion  90  of the module housing  92 . The first retention bracket  108  and the second retention bracket  110  may be, for example, L-shaped brackets, each including a plurality of holes arranged for substantial alignment with the pin holes in the release bracket  98  such that the extendible and retractable primary pin  102  and the shear pins  106  may pass through the first retention bracket  110 , the release bracket  98  and the second retention bracket  110 . 
     As previously indicated, the primary pin  102  is preferably selectively retractable from an extended position engaging the release bracket and retention brackets to a withdrawn position which is out of engagement with the release bracket and retention brackets. The primary pin  102  may also be selectively reinserted through the release bracket and retention brackets. The insertion or retraction of the primary pin  102  may be achieved by the actuation of a solenoid or step motor  112  fixedly attached to the surface of the module housing  92  or at such other location as may be convenient. This actuation may be controlled by a controller  27  (FIG. 1) such as an onboard computer or the like based upon steady-state inputs such as vehicle velocity, occupant size, occupant mass, seating position, and seat-belt use acquired during driving conditions. 
     In operation, the presence or absence of the primary pin  102  through the release bracket  98  may be used to selectively control whether or not the anchoring structure  80  (and the associated tethering element  30 ) is held in place or is carried through the slot  88  and away from the housing wall. By way of example only, in the event that the measurements taken of vehicle speed, occupant size/mass, seating position, and seat-belt use characteristics dictate that a decreased air bag profile configuration is warranted, the controller  27  directs the solenoid or step motor  112  to insert the primary pin  102  through the first retention bracket  108 , the release bracket  98 , and the second retention bracket  110 . The inserted condition of the primary pin  102  causes the anchoring structure  80 , and the tethering element  30  to be held secure, and in a restrained configuration as shown in FIG. 2 despite the application of a tensioning force through the tethering element  30  as the air bag cushion  20  is inflated. 
     In the event that the measurements of vehicle speed, occupant size/mass, seating position, and seat-belt use characteristics dictate that an increased air bag profile configuration is warranted, the controller  27  directs the solenoid or step motor  112  to withdraw the primary pin  102  from the release bracket  98 . With the primary pin  102  in the withdrawn position, the anchoring structure is supported by the shear pins  106 . Under normal conditions, the support provided by the shear pins  106  is adequate to hold the release bracket  98  in place. However, in the event that the air bag cushion  20  is inflated, the tension generated through the tethering elements  30  causes the shear pins  106  to break thereby permitting the release bracket  98  to be carried away from its initial position (FIG.  2 A). Due to the simplicity of insertion and withdrawal of the primary pin  102  it is contemplated that variations in occupant and/or vehicle conditions may be subject to substantially constant monitoring with insertion or withdrawal taking place as changing conditions dictate during operation over the life of the vehicle  14 . Such monitoring and associated adjustment permits the air bag deployment parameters to be set and reset numerous times as conditions change in anticipation of cushion deployment thereby ensuring proper deployment character at such time as cushion deployment may be required. 
     It is contemplated that the present invention may be adaptable to a wide variety of alternative constructions. By way of example only, one alternative construction is illustrated in FIGS. 6 and 7 wherein elements corresponding to those previously illustrated and described are designated by like reference numerals with a prime. As shown, in this construction the primary pin  102 ′ is operatively connected to a sliding vent  120 ′ so as to adjust gas venting through the module housing  92 ′. As illustrated, the sliding vent  120 ′ includes a multiplicity of vent openings  122 ′ which are alignable with corresponding openings  123 ′ in the module housing  92 ′. However, as best seen in FIG. 7, upon retraction of the primary pin  102 ′, the vent openings  122 ′ are shifted out of alignment with the openings  123 ′ in the module housing thereby reducing venting capacity and directing an increased amount of inflation gas into the air bag cushion. Of course, it is also contemplated that the vent openings  122 ′ may be initially out of alignment with the openings  123 ′ in the module housing such that upon retraction of the primary pin  102 ′ alignment is achieved and venting is increased. Thus, it is contemplated that venting capacity may be substantially matched to desired deployment characteristics based upon measured operational and occupant conditions. 
     It is to be understood that while the present invention has been illustrated and described in relation to potentially preferred embodiments, constructions and procedures, such embodiments, constructions and procedures are illustrative only and that the present invention is in no event to be limited thereto. Rather, it is contemplated that modifications and variations embodying the principles of the present invention will no doubt occur to those of ordinary skill in the art. In particular, it is to be understood that the present invention is in no way limited to any particular mechanism for the retention and/or release of extendible tethering elements and that all description of such mechanisms is exemplary and explanatory only. It is therefore contemplated and intended that the present invention shall extend to all such modifications and variations as may incorporate the broad aspects of the present invention within the true scope and spirit thereof.