Abstract:
An airbag module assembly includes a module housing that defines a storage chamber. A thrust neutral inflator device is at least in part disposed within the storage chamber. The inflator device releases airbag inflation gas within the storage chamber in a cross-car manner. In specific embodiments, the cross-car release of the airbag inflation gas involves substantially all the airbag inflation gas being released at an angle of no more than ±60° and preferably at an angle of no more than ±50° from horizontal when viewed in a top planar view of the inflator device disposed within the housing.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates generally to inflatable vehicular safety restraint assemblies such as airbag installations for automotive vehicles and, more particularly, to inflatable vehicular safety restraint assemblies that discharge or provide inflation gas to an airbag cushion in a cross-car manner. 
         [0003]    2. Discussion of Related Art 
         [0004]    It is well known to protect a vehicle occupant by means of safety restraint systems which self-actuate from an undeployed or static state to a deployed state without the need for intervention by the operator, i.e., “passive restraint systems.” Such systems commonly contain or include an inflatable vehicle occupant restraint or element, such as in the form of a cushion or bag, commonly referred to as an “airbag cushion.” In practice, such airbag cushions are typically designed to inflate or expand with gas when the vehicle encounters a sudden deceleration, such as in the event of a collision. Such airbag cushion(s) may desirably deploy into one or more locations within the vehicle between the occupant and certain parts of the vehicle interior, such as the doors, steering wheel, dashboard or the like, to prevent or avoid the occupant from forcibly striking such parts of the vehicle interior. 
         [0005]    Various types or forms of such passive restraint assemblies have been developed or tailored to provide desired vehicle occupant protection based on either or both the position or placement of the occupant within the vehicle and the direction or nature of the vehicle collision. Automotive passenger side airbag installations generally incorporate an airbag module assembly having an inflator device within a module housing or canister and an inflatable airbag cushion adapted to inflate out a side of the module housing. In one currently used passenger side airbag module assembly configuration the inflatable airbag cushion is adapted to inflate out a top side of the module canister, often referred to as a “top mounted” airbag cushion. Such a module assembly is installed in the dashboard of the automobile close to the windshield. Upon activation, the inflator device releases inflation gas which inflates the airbag cushion. The top mounted airbag cushion initially inflates toward the windshield and then rapidly rolls down the dashboard in a direction toward the passenger. 
         [0006]    One common form of inflator device stores or contains a pyrotechnic, propellant or other type of gas generant material which, upon actuation of the device, ignites or reacts to rapidly form or produce large volumes of inflation gas used to inflate an associated airbag cushion to protect vehicle occupants. 
         [0007]    As will be appreciated, the manufacture of such reactant gas generant material-containing inflator devices necessitate the taking of special care, not only during the manufacturing process but also during subsequent storage, handling, shipping and transportation, for example, to ensure avoidance of inadvertent ignition or reaction of the gas generant material contained within the inflator device. Moreover, in view of the widespread use of such inflator devices, large numbers of gas generant material-containing inflator devices are routinely shipped and transported, such as to various vehicle assembly plants. 
         [0008]    The risk of inadvertent reaction of a gas generant material-containing inflator device is generally very small in view of currently applied safety practices. 
         [0009]    In the past, gas generant material-containing inflator devices have raised a concern, such as in the event of a fire during the shipping or storage of the devices, that the gas generant material contained within the device would ignite or react to produce or result in the release of gases which could cause a condition of high thrust such that an unrestrained inflator can form or act as a projectile that may create a risk to personnel standing nearby or those trying to put out the fire. 
         [0010]    As a result of such possible risk, the United States Department of Transportation requires that inflator devices be subjected to a bonfire test wherein an inflator device even when placed directly in a fire cannot become a projectile upon ignition of the stored gas generant material. 
         [0011]    To satisfy such test requirements, inflator manufacturers have developed methods and techniques to balance the gases exiting or discharging from an inflator device to create a “thrust neutral” or “zero thrust” inflator. 
         [0012]    One approach has been to design an inflator device to have a plurality of gas discharge holes or openings radially disposed around the circumference of the inflator device. This technique is relatively easy and simple to employ in passenger side inflators and other applications such as where the inflator device is stored in a module housing assembly. For example, many current passenger side airbag module assemblies incorporate inflator devices having inflation gas exit areas, from the inflator device itself or, if used, an associated or included diffuser element, which are dispersed about the inflator device or the associated diffuser to provide or result in 360° gas diffusion to create a device that is thrust neutral. 
         [0013]    Moreover, in the past, inertia welding has been a typical or standard welding technique applied to or with inflator device production. Unfortunately, inertia welding typically results in random placement of the discharge openings of the inflator device or, if present, the associated diffuser. The random placement of the discharge openings results in inflators, such as typical disk type inflators, having or providing 360° gas diffusion to ensure thrust neutrality. 
         [0014]    One such disk type inflator device is shown in  FIG. 1  and generally designated by the reference numeral  20 . The inflator device  20  has a generally flat cylindrical shape, sometimes referred to as a “disk” shape, with a plurality of gas discharge holes or openings  22  radially disposed around the circumference of the inflator device. As shown in  FIG. 1 , the inflator device  20  may include or have joined thereto an attachment collar flange or bracket  24  such as having a plurality of fastener openings  26  disposed thereabout such as to permit the inflator device to be appropriately fastened into place in an associated module housing. 
         [0015]    While such 360° gas diffusion can desirably serve to result in a device that is thrust neutral, the use of inflator devices that produce or result in such inflation gas diffusion has frequently necessitated other modification to module assemblies. For example, module assemblies have required the inclusion of rings or deflectors such as to redirect the inflation gas in order to appropriately fill the airbag cushion to provide desired protection to the vehicle occupant. 
         [0016]    In practice, such 360° gas diffusion creates at least two additional major concerns for module development. Firstly, the 360° gas diffusion can create severe stresses on the car-forward &amp; car-rearward walls of the passenger airbag module housing. Secondly, the 360° gas diffusion can cause or result severe deformations such that can damage instrument panel components and the cover door over the passenger module housing. 
         [0017]    Efforts to address such concerns have included modifying the module housing such as through the inclusion of significant features such as to stiffen the car-forward &amp; car-rearward walls of the passenger airbag module housing such as to prevent this deformation (such deformation being commonly referred to as “bell-mouthing”). 
         [0018]    Reference is now made to  FIGS. 2-5  which illustrate a prior art airbag module assembly  30  including the prior art inflator device  20 . 
         [0019]    The airbag module assembly  30  includes a generally rectangular module housing  32  having a first pair of opposed walls including a car-forward wall or edge  34  and an opposed car-rearward wall or edge  36  and a second pair of opposed walls including first side wall  40  and a second side wall  42 . 
         [0020]    The housing  32  also includes a base wall  44  such as having an opening  46  therethrough for placement of the inflator device  20 . 
         [0021]    The airbag module assembly  30  further includes an appropriately shaped, sized and positioned deflector ring  50  such as forming or including a vertical deflector wall  52  extending about the inflator device  20  such that gas thrust neutrally exiting from the inflator device  20  through the plurality of gas discharge holes or openings  22  is directed vertically out of the housing (such as represented by the arrows  60 ) such as to appropriately inflate an associated airbag cushion. 
         [0022]    As will be appreciated, the need for the inclusion of such added structural features, such as to deflect or redirect the inflation gas and/or to strengthen or modify the module housing such as to prevent this bell-mouthing deformation can significantly increase product cost as well as undesirably increase the weight and size of the module assembly. 
         [0023]    Further, such turning of inflation gas to come out of the housing can act to create a column of gas that may undesirably be directly directed towards a vehicle occupant. This can be particularly significant in the event of an out-of-position (OOP) vehicle occupant, such as where an OOP vehicle occupant may be in close proximity to the airbag cushion. In such a situation, if not otherwise addressed, such an assembly operation can create an undesirable risk of injury to an OOP vehicle occupant. Thus, such assembly operation has been commonly addressed via inclusion, either in or with the module and/or otherwise in or by the safety restraint system, of additional countermeasures to minimize and avoid such risk. These countermeasures may, for example, involve a second turning of the inflation gas, such as turn the inflation gas after exiting the module housing. 
         [0024]    The inclusion of such countermeasures can also have an undesirable impact on assembly and system size and weight as well as cost. 
         [0025]    Thus there is a need and a demand for module assemblies and techniques that can desirably remove the need for turning the inflation gas multiple times during a crash event, yet still be able to satisfy inflator level thrust neutrality requirements for shipping. Further, there is a need and a demand for module assemblies and techniques that reduce the risk of inducing occupant injury in OOP conditions. Yet further, there is a need and a demand for module assemblies and techniques that remove the need for module level content to achieve inflation gas turning and to make the product more efficient. Yet still further, there is a need and a demand for module assemblies and techniques that reduce the need for the use of techniques and inclusion of module features such as added module housing stiffening features and thus can act to improve product features such as package size, weight, etc. 
       SUMMARY OF THE INVENTION 
       [0026]    A general object of the invention is to provide improved inflatable vehicular safety restraint assemblies such as airbag installations for automobiles. 
         [0027]    A more specific objective of the invention is to overcome one or more of the problems described above. 
         [0028]    One aspect of the invention relates to an airbag module assembly that includes a module housing and a thrust neutral inflator device. The module housing defines a storage chamber. The thrust neutral inflator device is at least in part disposed within the storage chamber such that the inflator device desirably releases airbag inflation gas in a cross-car manner within the storage chamber. 
         [0029]    In another aspect of the invention, there is provided an airbag module assembly that includes a module housing, an inflator device and a diffuser. The module housing desirably defines a storage chamber. The inflator device is at least in part disposed within the storage chamber. Upon actuation, the inflator device serves to provide inflation gas to inflate an associated vehicle occupant inflatable restraint device. The diffuser is in inflation gas flow communication with the inflator device. The diffuser includes inflation gas discharge openings on first and second opposed sides thereof to thrust neutrally discharge at least 90% of the inflation gas exiting from the diffuser cross-car within the storage chamber. 
         [0030]    In another aspect of the invention, there is provided an airbag module assembly. The airbag module assembly includes a module housing that defines a storage chamber. The module housing has or includes first and second pairs of opposed edges, the first pair of opposed edges includes a car-forward edge and an opposed car-rearward edge, the second pair of opposed edges includes a first lateral side edge and an opposed second lateral side edge. 
         [0031]    The module assembly further includes an inflator device at least in part disposed within the storage chamber. The inflator device, upon actuation serves or acts to provide inflation gas to inflate an associated vehicle occupant inflatable restraint device. 
         [0032]    The module assembly further includes a diffuser in inflation gas flow communication with the inflator device. The diffuser is centrally positioned between both the first and second pairs of housing opposed edges. The diffuser has or includes inflation gas discharge openings to release inflation gas within the storage chamber at an angle of no more than ±60° from horizontal when viewed in a top planar view of the diffuser within the housing. 
         [0033]    As used herein, references to inflators devices that is “thrust neutral” or that releases inflation gas in a “thrust neutral” manner or the like are to be understood to refer to inflator devices that thrust neutrally discharge at least 90%, and, preferably, substantially all, the inflation gas discharged or exiting from the inflator device. 
         [0034]    Other objects and advantages will be apparent to those skilled in the art from the following detailed description taken in conjunction with the appended claims and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0035]      FIG. 1  is a perspective view showing a prior art inflator device. 
           [0036]      FIG. 2  is a top planar view of a prior art airbag module assembly, including the prior art inflator device shown in  FIG. 1 . 
           [0037]      FIG. 3  is a perspective view of the prior art airbag module assembly shown in  FIG. 2 . 
           [0038]      FIG. 4  is a perspective sectional view of the prior art airbag module assembly shown in  FIGS. 2 and 3 . 
           [0039]      FIG. 5  is a side sectional view of the prior art airbag module assembly shown in  FIGS. 2-4 . 
           [0040]      FIG. 6  is a perspective view showing an inflator device in accordance with one aspect of the invention. 
           [0041]      FIG. 7  is an angled top side view of the diffuser element of the inflator device shown in  FIG. 6  showing the inflation gas diffusion angle for the discharge openings of the inflator device. 
           [0042]      FIG. 8  is a top planar view, similar to  FIG. 2 , but now showing an airbag module assembly in accordance with one aspect of the invention. 
           [0043]      FIG. 9  is a perspective view, similar to  FIG. 3 , but now showing the airbag module assembly in accordance with one aspect of the invention shown in  FIG. 8 . 
           [0044]      FIG. 10  is a perspective sectional view of the airbag module assembly in accordance with one aspect of the invention shown in  FIGS. 8 and 9 . 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0045]    As detailed further below, the invention generally provides improved inflatable vehicular safety restraint assemblies such as airbag installations for automobiles. 
         [0046]    A significant aspect of the invention is the development of inflator devices having discharge openings that are specifically placed, positioned or otherwise appropriately disposed on or about the inflator device or, if present, an associated diffuser to provide or result in desired directional inflation gas discharge without necessarily requiring module inclusion of structural features such as a deflector to turn the inflation gas out of the housing and potentially burning through the cushion material in close proximity to the inflator or the need for inclusion of a feature such as a cushion loop diffuser to turn the inflation gas to the sides (e.g., left and right) in the cushion in the event of an OOP vehicle occupant. 
         [0047]    As will be appreciated, in particular in view of the discussion following herein, desired directional inflation gas discharge without necessarily requiring the inclusion of such added features can greatly reduce the deployment loads on the car-forward and car-rearward sides of air bag module housing and thus desirably results in savings on one or more of module packaging, weight and cost. Further, the avoidance of such added features desirably allows or results in increased allowable space between the lateral sides of the housing prior to the inflation gas impinging on the cushion fabric. This increased distance permits or allows for increased or further cooling of inflation gases prior to contacting the associated inflatable restraint device, e.g., airbag cushion fabric. 
         [0048]    Turning to  FIG. 6  is a perspective view showing an inflator device, generally designated by the reference numeral  120 , in accordance with one aspect of the invention. The inflator device  120  has a generally ellipsoid shape. 
         [0049]    While the illustrated ellipsoid shape may more specifically be an oblate spheroid shape, those skilled in the art and guided by the teachings herein provided will understand and appreciate that the broader practice of the invention is not necessarily so limited as other ellipsoid shaped inflator devices as well as inflator devices of other shapes can be appropriately utilized in, with or as a part of the invention. 
         [0050]    The inflator device  120  includes or has a central diffuser element  121  having inflation gas discharge openings  122  thrust neutrally disposed thereabout in cross-car inflation gas release placement, as further illustrated by reference to  FIG. 7 . 
         [0051]    Regarding the thrust neutral placement of the inflation gas discharge openings  122 , it is to be appreciated that while  FIG. 6  shows inflation gas discharge opening  122   a  on a first side  124  of the diffuser  121 , a similar corresponding inflation gas discharge opening  122   b  is disposed on the opposite second side  126  of the diffuser  121 , as shown in  FIG. 7 . 
         [0052]    Those skilled in the art and guided by the teachings herein provided will further appreciate that while each of the first and second sides  124  and  126  have been shown with a single inflation gas discharge opening, the broader practice of the invention is not necessarily so limited. For example, in alternative embodiments, the area of discharge opening provided on either or both sides can, if desired, be subdivided such as by comprising two or more openings. In some embodiments, such multiple openings can be of the same size or different size, as may be desired for a particular application. 
         [0053]    As shown in  FIG. 7 , the inflation gas discharge openings are desirably disposed at an angle ±α from horizontal or such as at a total arc of 2α, where generally α=60° and, preferably, α=50° and such as to provide sought and desired cross-car diffusion of inflation gas produced or resulting from the inflator device  120 . 
         [0054]    Reference is now made to  FIGS. 8-10  which illustrate an airbag module assembly in accordance with one aspect of the invention and generally designated by reference numeral  230  including an inflator device  220  in accordance with one aspect of the invention and similar to the inflator device  120  described above. 
         [0055]    Similar to the inflator device  120 , the inflator device  220  includes or has a central diffuser element  221  having inflation gas discharge openings  222  thrust neutrally disposed thereabout in cross-car inflation gas release placement. In inflator device  220 , however, rather than a single discharge opening disposed on each of the first side  224  and second side  226  of the diffuser  221 , the area of discharge opening provided on each side is composed of two similarly sized openings. 
         [0056]    The airbag module assembly  230  includes a generally rectangular module housing  232  having a first pair of opposed walls including a car-forward wall or edge  234  and an opposed car-rearward wall or edge  236  and a second pair of opposed walls including first side wall  240  and a second side wall  242 . 
         [0057]    The housing  232  also includes a base wall  244  such as having an opening  246  therethrough for placement of the inflator device  220 . 
         [0058]    The airbag module assembly  230  further includes an appropriately shaped, sized and positioned attachment flange, bracket or ring  250  such as having a plurality of fastener openings  252  disposed thereabout such as in respective corners of the bracket  250 . As shown, fasteners  254  can be secured through the openings  252  such as to serve to secure the inflator device  220  and/or an associated airbag cushion within the module housing  232 . As will be appreciated by those guided by the teachings herein provided, through the use of a thrust neutral inflator device such as herein described and which inflator device diffuses or releases inflation gas in a cross-car manner (e.g., left and right) within the module instead of 360°, the need for a deflector ring to turn the gas out of the housing and avoid potential burning through the airbag cushion material in close proximity to the inflator is effectively eliminated. Thus, the attachment ring  250  at least in part differs from the deflector ring  50  described above in connection with the prior art assembly in that the attachment ring  250  does not include a vertical deflector wall extending about the inflator device such as to vertically gas exiting from the inflator device out of the housing. 
         [0059]    In  FIGS. 8 and 9 , the arrows  260  represent the cross-car discharge or release of inflation gas from the inflator device  220 , with the arrows designated by the reference numeral  264  depicting the release of the inflation gas from the housing and ultimately to the airbag cushion. Such cross-car discharge or diffusion of the inflation gas desirably greatly reduces the deployment loads on the car-forward side  234  and car-rearward side  236  of the housing  232 . As a result, the need for the inclusion of significant features such as to stiffen the housings on these two sides to prevent this deformation (bell-mouthing) is desirably reduced or eliminated and thus results in significant savings on module packaging, weight and/or cost. 
         [0060]    Additionally, the greater allowable space within the housing between left and right sides of the housing before gas impingement upon an airbag cushion fabric desirably acts to allow greater cooling of the inflation gas prior to contacting the fabric. Such a feature can be particularly desirable in the context of module assemblies that include or incorporate inflator devices that produce or form inflation gas in whole or in significant part via an exothermic reaction such as via an exothermic reaction of a pyrotechnic gas generant or via an exothermic reaction of a stored fuel material such that the initially produced or formed inflation gas is at an elevated temperature, as compared to the ambient temperature condition. Thus while the broader practice and use of the invention is not necessarily limited to use with heat-producing or heat-forming inflator devices, at least certain features of the invention appear to have particular desirability or applicability in connection with such heat-producing or heat-forming inflator devices. 
         [0061]    Moreover, the subject invention development desirably serves to achieve one or more of the following:
       1. removes the need for multiple turning of inflation gas during a crash event, yet still be able to satisfy inflator level thrust neutrality requirements for shipping;   2. removes the need for added module level content to effect such turning, thus making the product more efficient;   3. reduces the risk of inducing occupant injury in an OOP vehicle occupant conditions; and   4. reduces the need for stiffening features in or as a apart of the housing, thus improving one or more of package size, weight, and/or cost.       
 
         [0066]    The invention illustratively disclosed herein suitably may be practiced in the absence of any element, part, step, component, or ingredient which is not specifically disclosed herein. 
         [0067]    While in the foregoing detailed description this invention has been described in relation to certain preferred embodiments thereof, and many details have been set forth for purposes of illustration, it will be apparent to those skilled in the art that the invention is susceptible to additional embodiments and that certain of the details described herein can be varied considerably without departing from the basic principles of the invention.