Abstract:
An air bag assembly having an inflatable cushion selectively deployable to a controlled geometry with a controlled venting character. The venting characteristics are adjusted by selective displacement of vent blocking elements based upon measured occupant and/or crash severity characteristics such that an air bag cushion of desired volume and venting capacity is available to protect a range of occupants under different conditions during impact events of various levels of severity.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority from U.S. Provisional Application No. 60/305,004 filed Jul. 12, 2001 the contents of which are incorporated by reference as is fully set forth herein. 
     
    
     
       TECHNICAL FIELD  
         [0002]    This invention relates to an air bag assembly, and more particularly to an air bag assembly including an inflatable air bag cushion and one or more selectively actuated vents within the air bag cushion. The vents are selectively actuated in conjunction with control of the inflated profile of the air bag cushion such that venting is matched in a predefined manner to the inflated profile characteristics of the air bag cushion.  
         BACKGROUND OF THE INVENTION  
         [0003]    It is well known to provide an air bag assembly including an inflatable air bag cushion for protecting the occupant of a transportation vehicle. In an automotive vehicle, such air bag assemblies are typically located within the hub of the steering wheel and in a recess in the vehicle instrument panel for protection of the vehicle occupants seated in opposing relation to such assemblies. Additional air bag assemblies may be located within the seats and/or door panels for protection of the occupants during a side impact event.  
           [0004]    Air bag assemblies typically include an inflatable cushion, and a gas emitting inflator mounted in fluid communication with the inflatable cushion. In a driver side air bag module, a base plate typically supports the inflator at the interior of the vehicle steering wheel or other appropriate location opposing the occupant to be protected. The mouth of the air bag is disposed in surrounding relation to the inflator with a perimeter portion of the mouth being held between the base plate and an overlying retainer to effect a secure relation between the inflator and the cushion. In a passenger side assembly, the inflator is typically held within a trough-like housing with the air bag cushion being held along the walls of the housing such that inflation gas passes from the inflator into the cushion upon activation of the inflator. Both driver side air bag modules and passenger side air bag modules are well known.  
           [0005]    In the past it has been advocated to adjust the inflated profile of air bag cushions by the selective extension of tethering elements. By way of example only, representative systems for use in effecting a controlled deployment depth by selective release of tethering elements are disclosed in U.S. Pat. Nos. 5,887,894 to Castagner et al., and 6,390,501 to Greib et al. the teachings of which are incorporated by reference as is fully set forth herein.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention provides advantages and alternatives over the prior art by providing an air bag assembly including one or more selectively activateable vents which may be opened on command during deployment of the air bag cushion such that venting is selectively controlled in a predefined manner. The control of such venting characteristics thus provides an additional degree of control over the deployment characteristics of the air bag cushion.  
           [0007]    According to one aspect of the present invention, an air bag assembly is provided having an inflatable cushion selectively deployable to a controlled geometry with a controlled venting character. The venting characteristics are adjusted in view of crash severity and/or the position of the occupant and/or the size of the occupant and/or seat belt usage by the occupant to be protected such that an air bag cushion of desired volume and venting capacity is available to protect a range of occupants under different conditions during impact events of various levels of severity. The air bag assembly of the present invention provides a simple, cost effective and highly reproducible mechanism for controlling the venting character of the air bag cushion. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    The present invention will now be described by way of example only, with reference to the accompanying drawings which constitute a part of the specification herein and in which:  
         [0009]    [0009]FIG. 1 is a view of the interior of an automotive vehicle incorporating driver side and passenger side air bag modules;  
         [0010]    [0010]FIG. 2 is a side view of an exemplary air bag cushion;  
         [0011]    [0011]FIG. 3 is a view taken generally along line  3 - 3  in FIG. 2;  
         [0012]    [0012]FIG. 4 is a hemispherical sectional view of a driver side air bag module incorporating a selectively activateable venting arrangement with a displaceable patch element in a vent covering orientation operatively connected to a release assembly at the interior of an air bag cushion;  
         [0013]    [0013]FIG. 5 illustrates a displaceable vent patch arrangement for operative connection to a release assembly at the exterior of an air bag cushion;  
         [0014]    [0014]FIG. 6 is a view illustrating an alternative arrangement for a displaceable patch element;  
         [0015]    [0015]FIG. 7 is a view similar to FIG. 4 illustrating the vent in an open flow through condition;  
         [0016]    [0016]FIG. 8 illustrates an exemplary inflator and pin release assembly for releasing a displaceable patch element with the air bag cushion not shown;  
         [0017]    [0017]FIG. 9A is a cut-away view of the pin release assembly of FIG. 8 holding the displaceable patch element in an anchored condition;  
         [0018]    [0018]FIG. 9B is a view similar to FIG. 9A with the pin release assembly disengaged from the displaceable patch element;  
         [0019]    [0019]FIG. 10 is a view similar to FIG. 4 illustrating a selectively deployable tube vent construction;  
         [0020]    [0020]FIG. 11A is a schematic view of an air bag assembly incorporating a tube vent as shown in FIG. 10 with the tube vent held in a gas blocking position;  
         [0021]    [0021]FIG. 11B is a view similar to FIG. 9A with the tube vent released to a flow-through orientation for emission of inflation gas;  
         [0022]    FIGS.  12 A- 12 C illustrate various tube vent constructions; and  
         [0023]    [0023]FIG. 13 is an elevation plan view of an air bag cushion arrangement incorporating an integral tube vent structure.  
         [0024]    While the invention has been illustrated and generally described above, and will hereinafter be described in connection with certain exemplary embodiments, constructions, and procedures, it is to be understood that in no event is the invention to be limited to such illustrated and described embodiments, constructions, and procedures. On the contrary, it is intended that the present invention shall extend to all alternatives and modifications as may embrace the principles of this invention within the true spirit and scope thereof. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0025]    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. In FIG. 1, there is illustrated the interior of a vehicle  10  for transporting an operator  12  and a passenger  14 . As illustrated, the vehicle  10  may include a passenger side air bag assembly  16  mounted within the dash panel in substantially opposing relation to the vehicle passenger  14 . The vehicle  10  will also preferably include a driver side air bag assembly  17  mounted within the steering wheel  18  for protection of the vehicle operator  12 . According to a potentially preferred practice, the air bag assembly mounted within the steering wheel  18  is stored in hidden relation below a cover  20  which opens along tear seams  22  upon activation of the air bag assembly in a manner as will be well known to those of skill in the art. Such activation typically takes place upon the occurrence and measurement of predetermined vehicle conditions such as deceleration at a rate exceeding a predetermined value.  
         [0026]    As shown, the vehicle  10  may incorporate one or more sensors  24  such as optical sensors for measuring the dimensions of the vehicle occupants  12 ,  14 . Likewise, mass and/or position sensors (not shown) may be incorporated within the seating structure or at other suitable locations to provide further information upon the characteristics of the vehicle occupants. A sensor may also be provided to register whether or not the occupants are utilizing recommended seat belts. Data from the various sensors measuring occupant parameters as well as data from sensors measuring vehicle conditions may be translated to an on-board computer which in turn relays deployment activation signals to the driver side air bag assembly  17  and the passenger side air bag assembly  16  during a collision event.  
         [0027]    Referring to FIGS. 2 and 3, a typical inflatable air bag cushion  30  such as may be useful in a driver side assembly is illustrated. While the invention will hereinafter be illustrated and described in relation to a cushion  30  of a construction normally used in a driver side air bag assembly, the actual geometry of the cushion itself is in no way critical to the invention. Thus, it is to be understood that the invention will have equal applicability in a passenger side cushion as well as driver side cushions of other geometries.  
         [0028]    As shown, the air bag cushion  30  may be formed by seaming together panels of substantially pliable material so as to form a gas containment chamber of suitable size and shape. By way of example only and not limitation, one configuration for an inflatable air bag cushion  30  is formed by seaming together two substantially disk shaped pieces of material to achieve a configuration substantially as illustrated in FIG. 3. As shown therein, the inflatable air bag cushion  30  incorporates a gas inlet opening  32  for introduction of inflation gas. The gas inlet opening  32  is preferably of a size and shape to permit clamping around a gas generating inflator as discussed further hereinafter.  
         [0029]    The inflatable air bag cushion  30  includes one or more vent holes  34  for the expulsion of inflation gas following impact by the occupant to be protected. A seam  36  may be used to adjoin the panels of material forming the inflatable air bag cushion  30 . Such an adjoining seam may be formed by traditional industrial sewing techniques as well as by adhesive bonding or welding techniques including RF (radio frequency) welding and ultrasonic welding as will be well known to those of skill in the art. In the illustrated construction the panel of material  38  projects towards the occupant to be protected so as to define an impact surface while the panel of material  40  faces generally away from the occupant to be protected. As best illustrated in FIG. 3, a number of vent holes  34  may be arranged across the panel  40  facing away from the occupant to promote the discharge of inflation gas as the occupant impacts the panel  38 . An arrangement of mounting holes  42  may be disposed around the perimeter of the gas inlet opening  32  to permit the secure attachment of the gas inlet opening  32  around a gas generating inflator  44  (FIG. 4).  
         [0030]    In FIG. 4, one-half of an inflator  44  is illustrated with an air bag cushion  30  held in gas communicating surrounding relation to the inflator  44 . As will be appreciated, the inflator  44  may include an outwardly projecting mounting flange  46  which may be secured to a base plate  48 . Bolts  47  or other suitable fasteners extend through a clamping ring  49  (FIG. 8) having a configuration generally corresponding to the geometry of the gas inlet opening  32 . The bolts  47  extend through aligned mounting holes  42  surrounding the cushion mouth such that the perimeter of the cushion mouth is clamped in place around the inflator  44 . In the illustrated embodiment a cover plate  51  having a configuration adapted to accept a tether release mechanism  64  to be described further hereinafter is disposed between the clamping ring  49  and base plate  48 . Of course, the illustrated arrangement is to be understood to be exemplary only and that the air bag cushion  30  may be arranged in fluid communication with the inflator  44  using any suitable attachment arrangement.  
         [0031]    As illustrated, in the air bag arrangement illustrated in FIG. 4 at least one of the vent holes  34  is normally closed by an elongate patch element  50  which is secured at its distal end to a surface of the air bag cushion at an attachment location  52 . The proximal end of the patch element  50  is normally secured in releasable anchored relation at a displaceable pin element  54 . As shown, the proximal end of the patch element  50  may include a loop structure  56  disposed in sliding relation around the pin element  54 .  
         [0032]    As illustrated, according to one contemplated arrangement, the distal end of the patch element  50  is held at the exterior of the air bag cushion  30  at an attachment location  52  formed from a pattern of secure stitches arranged in a pattern such as a box-X seam or the like. The patch element  50  which is of elongate construction extends away from the attachment location  52  and is threaded through the vent hole  34  so as to enter the interior of the air bag cushion  30 . If desired, a break-away tacking seam  58  may be used to join the patch element  50  to the interior surface of the air bag cushion  30  at a position between the vent hole  34  and the pin element  54  so as to maintain the position of the patch element in blocking relation across the vent hole  34  between the attachment location  52  and the break-away tacking seam  58 . The proximal end may then extend away from the tacking seam  58  to the pin element  54  at a position inboard of the clamping ring  49  as shown.  
         [0033]    It is also contemplated that the releasable attachment between the pin element and the patch element may be outside of the air bag cushion  30 . An arrangement for disposition of the patch element across a vent hole for releasable attachment outside the air bag cushion is illustrated in FIG. 5, wherein elements corresponding to those previously described are designated by like reference numerals with a prime. As shown, in this arrangement the distal end of the patch element  50 ′ is held at the exterior of the air bag cushion  30 ′ at an attachment location  52 ′ formed from a pattern of secure stitches arranged in a pattern such as a box-X seam or the like. The patch element  50 ′ which is of elongate construction extends away from the attachment location  52 ′ and is threaded through the vent hole  34 ′ so as to enter the interior of the air bag cushion  30 ′. If desired, a break-away tacking seam  58 ′ may be used to join the patch element  50 ′ to the interior surface of the air bag cushion  30 ′ at a position between the vent hole  34 ′ and the pin element  54 ′ so as to maintain the position of the patch element in blocking relation across the vent hole  34 ′ between the attachment location  52 ′ and the break-away tacking seam  58 ′. The patch element  50 ′ then extends back through an exit slot  60 ′ at a position below the break-away tacking seam for engagement with a displaceable pin element (not shown).  
         [0034]    Yet another arrangement for placement of the patch element is illustrated in FIG. 6 wherein reference numerals correspond generally to those in FIG. 5 but with a double prime. As shown in FIG. 6, the elongate patch element  50 ″ is secured to the exterior surface of the air bag cushion  30 ″ at a secure attachment location  52 ″. The patch element  50 ″ is normally held over an arrangement of vent holes  34 ″ by a break-away seam  58 ″ extending at least partially along the length of the patch element  50 ″ adjacent to and outboard of the vent holes  34 ″. In such an arrangement, when the patch element  50  is held at the anchoring pin (not shown), a covering relation is maintained across the vent holes  34 . Of course, this may be on either the interior or exterior of the air bag cushion  30 ″. However, when the elongate patch element  50 ″ is released, the pressure acting from the interior of the air bag cushion  30 ″ causes the break-away seam  58 ″ to begin failing thereby progressively opening the vent holes  34 ″.  
         [0035]    As shown, the patch element  50 ″ may be tapered from a broader width at the secure attachment location  52 ″ to a more narrow width extending towards the loop structure  56 ″. Such a structure is believed to concentrate the initial tearing force at the more narrow regions of the patch element  50 ″. This concentration of tearing force is believed to facilitate the progressive failure of the break-away seam  58 ″ such that failure is initiated at the vent hole  34 ″ farthest away from the secure attachment location  52 ″ and thereafter progresses towards the secure attachment location  52 ″ as pressure is increased. It is believed that such a progressive development of venting may be desirable in some instances.  
         [0036]    According to the contemplated practice of the invention, the pin element  54  is displaceable relative to the patch element  50  on command based upon input data from the various sensors measuring the conditions of the occupant to be protected and/or crash severity. By way of example only, and not limitation, in the event that the inflator  44  is a dual stage inflator, it is contemplated that the patch element  50  may be released in conjunction with the activation of the second inflator stage (i.e. when additional gas is discharged into the air bag cushion  30 ). It is contemplated that this may occur when the crash is severe and/or when the occupant to be protected is large and/or when the occupant is seated an extended distance away from the air bag cushion  30  and/or when the occupant is not using the recommended seat belt. Of course, it is to be understood that the actual activating conditions will likely vary from vehicle to vehicle based upon factors such as vehicle type and air bag cushion placement location.  
         [0037]    Upon the achievement of disengagement, the patch element  50  is free to move out of covering relation relative to the vent hole  34  as pressure is applied by the inflating gas. In the arrangement illustrated in FIGS. 4 and 7, the patch element  50  slides out through the vent hole  34 . If the patch element is arranged as illustrated in FIG. 6, it will progressively tear away from the vent holes  34 ″ as pressure increases. As will be appreciated, a higher activating pressure may be required to effect the movement of the patch element with higher strength break-away tacking seams. Thus, it is contemplated that strength of any break-away tacking seams may provide an additional degree of control over the venting characteristics of the cushion. That is, stronger break-away seams may be utilized if higher activating pressures are desired.  
         [0038]    It is contemplated that the patch element  50  may be disengaged from the pin element  54  by any number of mechanisms resulting in the relative movement of the patch element and the pin element. By way of example only, and not limitation, one potential arrangement for use in moving the pin element  54  out of engagement with the patch element  50  is illustrated in FIGS. 8, 9A and  9 B. In the Illustrated arrangement, the pin element  54  normally projects out of a chamber  64  which is in fluid communication with a pressure generating squib  62 . In operation the squib  62  which is selectively activateable when occupant and/or vehicle conditions indicate that enhanced venting is desired. Thus, in instances such as an impact involving an extremely large occupant, the squib  62  is activated by a signal from an on-board computer causing surge in pressure within the chamber  64 .  
         [0039]    As best seen through simultaneous reference to FIGS. 9A and 9B, the surge in pressure within the chamber  64  acts against a plunger  65  which is operatively connected to the pin element  54 . Upon the establishment of sufficient pressure within the chamber  64 , the plunger  65  is moved through the chamber  64  so as to compress a biasing spring  67  which normally serves to maintain the pin element in the outwardly projecting orientation shown in FIG. 9A. The pin element  54  is thus drawn into the chamber and out of engagement with the patch element  50 . The patch element is thereafter no longer anchored at the pin element and is thus free to move out of covering relation relative to vent openings within the air bag cushion. According to the illustrated construction, a male snap fit locking element  68  may project away from the plunger in the direction of plunger movement for locking engagement with a cooperating acceptance opening  69  so as to prevent the plunger  65  and pin element from springing back following compression. Of course, the relative orientation of the male and female locking elements may also be reversed if desired. Likewise, it is to be understood that virtually any alternative arrangement for moving the pin element  54  and/or the patch element  50  may be utilized to effect the desired disengagement.  
         [0040]    It is also contemplated that structures other than two dimensional patches may be utilized to selectively block venting within the cushion. By way of example only and not limitation one alternative arrangement is illustrated in FIG. 10 wherein elements corresponding to those previously described are designated by like reference numerals increased by 100. In the assembly illustrated in FIG. 10, the air bag cushion  130  includes a vent opening in the form of a hollow venting tube  170  which is normally held at the interior of the cushion  130  by a releaseable tethering strap  172  secured at a releasable anchor pin  154  displaceable as previously described.  
         [0041]    As illustrated in FIG. 11A, when the air bag cushion  130  is inflated, the walls of the air bag cushion  130  move outwardly thereby placing the venting tube  170  into tension as it strains against the tethering strap  172 . This tension causes the venting tube  170  to naturally pinch off thereby restricting the outward flow of inflation gas. However, as illustrated in FIG. 11B, when the tension between the venting tube  170  and the tethering strap  172  is released, the venting tube  170  is allowed to open up and can be pushed outwardly from the interior of the air bag cushion  130  thereby permitting the venting of inflation gas as pressure is built within the cushion.  
         [0042]    In an assembly which utilizes a tubular vent arrangement, it is contemplated that the venting tube may have a wide array of constructions. By way of example only, and not limitation, one contemplated construction for a venting tube  170  is illustrated in FIG. 12A. In this construction the venting tube  170  includes an elongate nozzle portion  174  which may be formed by running an adjoining elongate seam along opposing edges of a flat piece of pliable material such as fabric, film or the like. One end of the nozzle portion  174  may be adjoined to a base portion  178  such as a panel of fabric or film of generally annular geometry. The base portion  178  may in turn be seamed to the exterior of the air bag cushion  130  around a standard vent opening. If desired, the nozzle portion  174  may include one or more surface apertures  175  for attachment of the tethering strap. Preferably, the nozzle portion  174  is of sufficient pliability to permit it to be pushed in collapsing relation into the interior of the cushion  130  during packaging.  
         [0043]    Of course it is to be appreciated that the actual construction of the vent tube may be the subject of a wide range of alternatives. By way of example only, in FIG. 12B a cross section of a nozzle portion  174 ′ is shown formed from the joinder of two strips of material. In FIG. 12C, a cross section of a nozzle portion  174 ″ is shown formed from the joinder of three strips of material.  
         [0044]    It is also contemplated that the vent tube may be integral to the cushion rather than being formed separately and thereafter attached. One panel construction which provides such an integral tube vent is illustrated in FIG. 13. As will be appreciated, two mating panels  180  which each include a protrusion  182  may be adjoined around their perimeter by a seam  136  substantially as described in relation to the cushion illustrated in FIG. 2. However, the seam  136  is left open at the outwardly projecting ends of the protrusions  182 . The opposing protrusions which are adjoined along their edges thus define a venting nozzle with a gas emission opening  184  at the open end. Due to the substantially pliable nature of the fabric or other material forming the panels  180 , the nozzle formed may be pushed to the interior of the formed cushion for attachment to a releasable tether to effect controlled venting in the manner previously described.  
         [0045]    It is to be understood that while the present invention has been illustrated and described in relation to various exemplary embodiment, constructions, and practices, that such embodiments, constructions, and practices are intended to be 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 skill in the art and it is therefore contemplated and intended that the present invention shall extend to all such modifications and variations as may incorporated the broad principles of the invention within the full spirit and scope thereof.