Abstract:
A lighter, low-cost inflatable restraint module is disclosed. The inflatable restraint module may include an inflator positioned within a heat shield. The heat shield and inflator may be disposed within an inflatable cushion. A portion of the cushion containing the inflator and heat shield is situated within a chamber. The chamber may include an opening in the chamber and an extension that projects away from the opening. Attachment of a portion of the inflatable cushion to the extension keeps the portion of the cushion away from the opening of the chamber and, thus, away from potentially damaging heat generated by the inflator. Alternatively, the portion of the cushion may be kept away from the opening by attachment to a cover which is, in turn, attached to the extension. The inflator, heat shield, chamber, and cushion may be secured within an interior region of a canister.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to inflatable restraints. More specifically, the present invention relates to an inflatable restraint module that is lighter and less expensive than conventional airbag modules. 
     2. Technical Background 
     The inclusion of inflatable safety restraints, or airbags, is now a legal requirement for many new vehicles. In addition to this, inflatable airbags enjoy widespread acceptance for use in motor vehicles and are credited with preventing numerous deaths and injuries. Some studies estimate that the use of frontally placed airbags reduces the number of fatalities in head-on collisions by 25% among drivers using seat belts and by more than 30% among unbelted drivers. Other research suggests that in a frontal collision, the combination of a seat belt and an airbag can reduce serious chest injuries by 65% and serious head injuries by up to 75%. These numbers, and the thousands of prevented injuries they represent, demonstrate the life-saving potential of airbags and the need to encourage their use, production, and development. 
     As a result, in part, of benefits such as those described above, automakers are now required to install airbags in most new vehicles sold in the United States. Furthermore, many automobile manufacturers have turned airbag technology into a marketing tool. Enticed by the promise of added safety, many vehicle purchasers seek out vehicles with sophisticated airbag systems. 
     Airbags are often installed in the steering wheel and in the dashboard on the passenger side of a vehicle. In the event of an accident, an accelerometer situated within the vehicle measures the abnormal deceleration caused by the accident and triggers the expulsion of expanding gases from an inflator into each of the airbags. The expanding gases rapidly fill the airbags, which immediately inflate in front of the driver and passenger to protect them from impacts against the windshield, dashboard, or steering wheel. 
     As a result of the success of front-installed airbags, other airbags designed to protect occupants in various types of vehicular collisions have been developed. For instance, side impact airbags, often in the form of inflatable curtains, were developed in response to the need for protection from impacts in a lateral direction, or against the side of the vehicle. Such curtains are placed along the side of a vehicle in places such as the ceiling or roof rails. An inflatable curtain may be composed of one or more separately inflated cushions that protect individual passengers in different positions within the vehicle. 
     Automobile manufacturers may install airbags in their vehicles by securing an airbag module to an appropriate location within the vehicle and connecting an inflator within the module to an accelerometer of the vehicle. The airbag module may include structures for securing the module within the vehicle and an interface for connecting the inflator to the accelerometer. 
     One type of conventional airbag module may include an inflatable cushion. The inflatable cushion may have two openings for receiving the inflator. However, the inflator cannot be placed immediately adjacent to the inflatable cushion. If so, heat generated during activation of the inflator could damage the cushion and prevent proper deployment. 
     To avoid damage to the cushion, a diffuser is often interposed between the inflator and the cushion. The diffuser surrounds the inflator and separates the inflator from the cushion. The diffuser is often made from metal. Consequently, the diffuser is quite heavy. Also, the diffuser typically includes a number of openings to allow gas from the inflator to move from the inflator into the cushion. As such, the diffuser is intricate and is made by a relatively complex manufacturing process. This process can become quite expensive, particularly when a large number of airbag modules are manufactured. The diffuser may also include protrusions for securing and orienting the diffuser within a canister, again increasing the complexity of the airbag module. 
     The canister protects the inflatable cushion and inflator and may be used to secure the airbag module to the vehicle. Although various configurations exist, the protrusions generally pass through apertures in the inflatable cushion and interlock with the canister. Unfortunately, the apertures increase the cost and complexity of manufacturing the cushions. 
     The canister must also include openings, mechanisms, and/or structures for interlocking with the protrusions of the diffuser. These interlocking mechanisms are often complex and intricate. The manufacturing process must be precise to ensure a smooth interaction between the protrusions and the locking mechanisms. Thus, the manufacturing costs are high. 
     In view of the foregoing, it would be an advancement in the art to provide an airbag module having lighter and less intricate components. It would be a further advancement in the art to provide an airbag module that is less expensive to manufacture than conventional airbag modules. 
     SUMMARY OF THE INVENTION 
     The apparatus and methods of the present invention have been developed in response to the present state-of-the-art, and, in particular, in response to problems and needs in the art that have not yet been fully resolved by currently available airbag modules. To achieve the foregoing, and in accordance with the invention as embodied and broadly described in the preferred embodiments, an inflatable restraint module that is lighter and less expensive to manufacture than conventional airbag modules is disclosed. 
     The inflatable restraint module may include an inflator that generates gas or foam to inflate an inflatable cushion. The gas or foam may exit the inflator through one or more gas exit ports. The inflator may be generally cylindrical in shape and have a first and a second end. The first end of the inflator may include inclined threads. A mating nut may be attached to the incline threads. The second end of the inflator includes an expanded portion. 
     The inflatable restraint module may also include a heat shield disposed around the inflator. The heat shield is shaped to surround the inflator. For instance, if an inflator is cylindrical in shape, the heat shield may be a rectangular piece of fabric that can be positioned around the inflator. The heat shield may be made from various materials, including a heat-resistant fabric. 
     The heat shield does not necessarily encompass the entire inflator. Instead, the heat shield, when disposed around the inflator, may define a gap. The exit gas ports of the inflator may be aligned with the gap in the heat shield. 
     The inflatable restraint module may include an inflatable cushion disposed around the heat shield and inflator. More specifically, the cushion may include a loop defining two orifices. The orifices may be shaped to receive an inflator such that the cushion surrounds the inflator. The cushion may also include an expandable portion that expands when a foam or gas from the inflator is rapidly injected into the inflatable cushion. 
     The inflatable restraint module may also include a chamber positioned around the inflator, heat shield, and loop of the cushion. The chamber may be generally cylindrical and may be shaped to receive the inflator, heat shield, and loop. More specifically, the chamber may include an interior compartment having two open ends. Thus, the loop of the cushion having the inflator and heat shield disposed therein is positioned within the interior compartment. The chamber is shorter than the inflator such that the first and second ends of the inflator may protrude out of each of the open ends of the chamber when an inflator is positioned in the chamber. 
     The open ends of the interior compartment should be sufficiently large, such that the inflator, heat shield, or both may be inserted through one of the open ends into the interior compartment. Of course, the open ends may be partially enclosed and still permit an inflator to be inserted into the interior compartment. 
     An opening may be formed in the chamber. The loop of the cushion extends from the interior compartment through the opening of the chamber. The expandable portion of the cushion is positioned in a folded state on a lip of the chamber. Accordingly, the opening may be configured in various shapes to achieve this purpose. The gap of the heat shield may be aligned with the opening in the chamber so that gas may rapidly exit the inflator through the gap of the heat shield into the inflatable portion of the cushion. 
     The chamber may also include an outward extension. The extension may be positioned proximate the opening and projects away from the opening. The extension is coupled to the cushion. In this embodiment, the extension may be coupled to the cushion by attachment to the cushion. More specifically, a portion of the cushion is attached to the extension of the chamber. The portion of the cushion may be sewn to the extension. Alternatively, the portion may be attached to the extension using adhesives, rivets, a nut and bolt, or the like. Being attached to the extension, the portion of the cushion is kept away from the opening in the chamber and, as a consequence, is kept away from the inflator. If the portion of the cushion were not kept away from the inflator, the cushion could be damaged by heat generated by the inflator during inflation. Thus, the extension is shaped to keep a portion of the cushion away from the opening. The extension may be configured in various ways to achieve this purpose. 
     The chamber is simple in design and may be made from various materials, including plastic or metal. When made from plastic, the chamber is very light and inexpensive to manufacture. 
     The inflatable restraint module may also include a canister at least partially disposed around the inflator, heat shield, cushion and chamber. More specifically, the canister may include an interior region in which the inflator, heat shield, cushion and chamber may be positioned. The canister may also define an open side through which the cushion and chamber may be inserted into the interior region. The cushion may deploy through the open side of the canister. 
     The canister also includes a first and a second mouth. The first and second mouths may be formed in opposing ends of the canister. The first and second mouths may be shaped and positioned so that the first end of the inflator is disposed within the second mouth of the canister, and a second end of the inflator is disposed within the first mouth of the canister. The first mouth is shaped to receive the inflator so that the inflator may be inserted into the canister through the first mouth. 
     A mating nut is attached to the inclined threads on the first end of the inflator. The mating nut is wider than the second mouth of the canister. As stated above, the second end of the inflator includes the expanded portion that is wider than the first mouth of the canister. Thus, the canister is positioned between the expanded portion of the inflator and the nut, which is attached to the inflator. The nut is tightened down on the inclined threads so that the nut and expanded portion are pulled towards each other to secure the inflator within the canister. When secured in the canister and positioned in through the loop of the cushion, the inflator aids in securing the cushion to the canister, such that the cushion is tethered to the inflatable restraint module at the time of inflation. 
     Like the first embodiment, a second embodiment of the inflatable restraint module includes a cushion, inflator, and heat shield. As will be explained below, the second embodiment also includes a chamber and a canister which may be slightly different than those of the first embodiment. The second embodiment also includes a cover that is not used in the first embodiment of the inflatable restraint module. 
     In the second embodiment, just as in the first embodiment, a heat shield is positioned around the inflator. The heat shield and inflator are positioned within a loop of the cushion. The loop of the cushion is situated within an interior compartment of a chamber. The cushion extends out of the interior compartment through an opening in the chamber. An expandable portion of the cushion may be folded and placed on a lip of the chamber. 
     As in the first embodiment, an outward extension of the chamber is coupled to the cushion. More specifically, a portion of the cushion is attached to the outward extension of the chamber. The outward extension may be situated proximate the opening and projects away from the opening. Attachment of the portion of the cushion to the extension keeps the portion of the cushion away from the opening of the chamber and the inflator to prevent damage to the cushion at the time of inflation. 
     In the second embodiment, the inflator, cushion, and chamber are also positioned within an interior region of a canister. The inflator, cushion, and chamber may be inserted into the interior region of the canister through an open side of the canister. 
     Like the first embodiment, the second embodiment also includes a canister having a first and second mouth. A first end of the inflator may be positioned within the second mouth of the canister, and a second end of the inflator may be situated within the first mouth of the canister. The second end of the inflator includes an expanded portion that is wider than the first mouth of the canister. As with the first embodiment, a mating nut, which is wider than the second mouth, may be attached to inclined threads on the first end of the inflator to secure the inflator within the canister. 
     Unlike the first embodiment, the second embodiment includes a cover that extends from the extension of the chamber, across the open side of the canister, and is attached to the canister. The cover is shaped to cover the cushion and thus to prevent damage to the cushion. The cover may be integrally formed with the extension of the chamber or may be attached to the chamber. For instance, the cover may be sewn to the extension. Alternatively, adhesives, rivets, or a nut and bolt may be used to attach the cover to the extension. 
     The cover is also attached to the canister. Again, various techniques may be used to do so. For instance, the cover may include a set of tabs that interlock with mating apertures in the canister. 
     At the time of inflation, the cushion deploys through the cover. Thus, the material from which the cover is made may, for instance, include frangible seams so that the cover does not impede deployment of the inflatable cushion. 
     Like the first embodiment, a third embodiment includes an inflator, heat shield, cushion, and canister. As will be explained below, the third embodiment includes a chamber which is slightly different from the chamber of the first embodiment and further includes a cover that is different than the cover of the second embodiment. 
     In the third embodiment, just as in the first embodiment, a heat shield is positioned around the inflator. The heat shield and inflator are positioned within a loop of the cushion. The loop of the cushion is situated within an interior compartment of the chamber. The cushion extends out of the interior compartment through an opening in the chamber. An expandable portion of the cushion may be folded and placed on a lip of the chamber. In the third embodiment, the inflator, cushion, and chamber are also positioned within an interior region of the canister. The inflator, cushion, and chamber may be inserted into the interior region of the canister through an open side of the canister. 
     Like the first embodiment, the third embodiment also includes a canister having a first and second mouth. The inflator is positioned in the canister such that a first end of the inflator is positioned within the second mouth of the canister, and a second end of the inflator is situated within the first mouth of the canister. The second end of the inflator includes an expanded portion that is wider than the first mouth of the canister. As with the first and second embodiments, a mating nut, which is wider than the second mouth, may be attached to inclined threads on the first end of the inflator to secure the inflator within the canister. 
     The cushion is coupled to the outward extension of the chamber. However, unlike the first embodiment, the cushion is coupled to the outward extension by attachment to a cover, which is attached to the outward extension. More specifically, a portion of the cushion is attached to a cover and the cover is attached to the outward extension of the chamber to keep the portion of the cushion away from the opening of the chamber and the inflator to prevent damage to the portion of the cushion at the time of inflation. The cover may be attached to the cushion using various techniques. For instance, the cover may be sewn to the cushion. 
     The cover may be attached to the extension using various techniques. For example, a first set of apertures in the cover may mate with a set of tabs on the extension of the chamber. The cover of the third embodiment then wraps around, or surrounds, the chamber and the expandable portion of the cushion. As explained above, the inflator, heat shield, and loop of the cushion are disposed within the chamber. 
     After being wrapped around the chamber and expandable portion of the cushion, the cover attaches once again to the extension. For instance, tabs on the extension may mate with a second set of apertures in the cover. Of course, various techniques may be used to attach the cover to the extension. For instance, the cover may be sewn to the extension. Alternatively, rivets, a nut and a bolt, or adhesives may be used to attach the cover to the extension. The cover may be sewn to the inflatable cushion. The cover may be made from various materials, including fabrics and plastics, as will be understood by those skilled in the art. 
     In view of the foregoing, the inflatable restraint module provides substantial advantages over conventional airbag modules. The individual components of the inflatable restraint module are simple in design and, as a consequence, are less expensive to manufacture than conventional module components. Many of the components may be made from plastic or fabric rather than metal, further diminishing the cost and weight of the module. 
     These and other advantages of the present invention will become more fully apparent from the following description and appended claims, or maybe learned by the practice of the invention as set forth hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order that the manner in which the advantages and features of the invention are obtained, a more particular description of the invention summarized above will be rendered by reference to the appended drawings. Understanding that these drawings illustrate only selected embodiments of the invention and are not therefore to be considered limiting in scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
     FIG. 1 is an exploded perspective view of an inflatable cushion, chamber, heat shield, inflator, and canister of a first embodiment of the inflatable restraint module; 
     FIG. 2 is a cross-sectional view of the first embodiment of the inflatable restraint module; 
     FIG. 3 is an exploded perspective view of a second embodiment of the inflatable restraint module; 
     FIG. 4 is a cross-sectional view of the second embodiment of the inflatable restraint module; 
     FIG. 5 is an exploded perspective view of a third embodiment of the inflatable restraint module; and 
     FIG. 6 is a cross-sectional view of the third embodiment of the inflatable restraint module. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The preferred embodiments of the invention are now described with reference to FIGS. 1-6. The members of the present invention, as generally described and illustrated in the Figures, may be implemented in a wide variety of configurations. Thus, the following more detailed description of the embodiments of the system and method of the present invention, as represented in the Figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of presently preferred embodiments of the invention. 
     Referring to FIG. 1, there is shown a perspective view of a first embodiment of the inflatable restraint module  10 . The inflatable restraint module  10  may include an inflatable cushion  12 . The inflatable cushion  12  includes an expandable portion  13  that expands when a gas or foam is rapidly injected into the inflatable cushion  12 . The expandable portion  13  is shown in an inflated state in FIG.  1 . However, the expandable portion  13  may be placed in a folded state prior to inflation, as illustrated in FIG.  2 . 
     The inflatable cushion  12  may be shaped to receive an inflator  14  that produces gas or foam to inflate the cushion  12 . More specifically, the cushion  12  may include a loop  16 . The loop  16  defines two orifices  18  within the cushion  12 . The orifices  18  may be shaped to receive an inflator  14  such that the cushion  12  surrounds the inflator  14 . The orifices  18  may be slightly smaller or approximately the same size as the inflator  14  so that the inflator  14  may be snugly positioned within the two orifices  18 . 
     The inflatable restraint module  10  may also include a chamber  20 . The illustrated chamber  20  is generally cylindrical in shape. However, the chamber  20  may be configured in other shapes. For example, the chamber  20  may have a rectangular or square cross-sectional shape. The chamber  20  is simple in design and, thus, is easy and inexpensive to manufacture. The chamber  20  may be formed from various materials including plastics. When the chamber  20  is made from plastic, it is not only inexpensive to manufacture, but is lightweight. 
     The chamber  20  is hollow and defines an interior compartment  22  having open ends  24 . The interior compartment  22  is designed to receive the inflator  14  and, as a consequence, may be similar in shape to the inflator  14 . The interior compartment  22  is slightly shorter in length than the inflator  14 . As such, the inflator  14  may protrude slightly out of the chamber  20  when the inflator  14  is positioned therein. 
     The open ends  24  of the chamber  20  may be slightly wider than or about the same size as the inflator  14  to allow the inflator  14  to be inserted into the interior compartment  22 . The open ends  24  may be partially enclosed and still permit an inflator  14  to be inserted into the interior compartment  22 . 
     The chamber  20  may also include an opening  26 . As illustrated, the opening  26  extends along the length of the chamber  20 . The opening  26  is shaped to receive the loop  16  of the cushion  12 . In particular, the loop  16  may be inserted through the opening  26  into the interior compartment  22 . The opening  26  may be embodied in various shapes and positioned at various locations on the chamber  20  to permit the loop  16  to be inserted into the interior compartment  22 . 
     When the loop  16  is positioned within the interior compartment  22 , the cushion  12  may be oriented such that each orifice  18  is positioned within one of the open ends  24  of the compartment  22 . When the cushion  12  is so oriented, an inflator  14  may be inserted into the cushion  12  through the orifices  18 . Also, the expandable portion  13  of the cushion  12  may be folded and placed on a lip  27  of the chamber  20 . 
     The chamber  20  may also have an outward extension  28 . The outward extension  28  may be located on the chamber  20  adjacent to the opening  26 . The outward extension  28  projects away from the opening  26 . The function of the outward extension  28  will be discussed in connection with FIG.  2 . 
     The inflatable restraint module  10  may also include a canister  60 . The canister  60  is hollow and may have an open side  62 . The open side  62  may be shaped to receive the chamber  20  and inflatable cushion  12  so that the chamber  20  and cushion  12  may be positioned within an interior region  64  of the canister  60 . In particular, the interior region  64  of the canister  60  is shaped to receive the chamber  20  when the loop  16  of the cushion  12  is positioned within the interior compartment  22  of the chamber  20 . The canister  60  may be used to attach the inflatable restraint module  10  to a vehicle (not shown). 
     The canister  60  may include a first and a second mouth  66 ,  68 . The mouths  66 ,  68  may be positioned on opposing ends  70  of the canister  60 , as illustrated in FIG.  1 . The first and second mouths  66 ,  68  are dimensioned to receive the inflator  14 . In particular, a first end  72  of the inflator  14  may be inserted through the first mouth  66  of the canister  60  and through the interior region  64  of the canister  60 . The first end  72  of the inflator  14  may then be inserted into the second mouth  68  of the canister  60  at the same time that a second end  74  of the inflator  14  moves into the first mouth  66  of the canister  60 . As a consequence, the first mouth  66  of the canister  60  is shaped to be positioned around the second end  74  of the inflator  14 , and the second mouth  68  of the canister  60  is shaped to be positioned around the first end  72  of the inflator  14 . 
     The second end  74  of the inflator  14  includes an expanded portion  75  that is wider than the first mouth  66  of the canister  60 . The first end  72  of the inflator  14  may also include inclined threads  76  for receiving a mating nut  78 . The mating nut  78  is wider than the second mouth  68  of the canister  60 . When the inflator  14  is positioned within the canister  60 , the mating nut  78  may be attached to the inclined threads  76  on the first end  72  of the inflator  14 . As the nut  78  is tightened down on the inclined threads  76 , the nut  78  and expanded portion  75  of the inflator  14  are pulled towards each other to secure the inflator  14  within the canister  60 . Other mechanisms besides inclined threads  76  and a mating nut  78  may be used to secure the inflator  14  within the canister  60 . For example, it is possible to employ a hole (not shown) in the first end  72  of the inflator  14  and an interlocking pin (not shown) to lock the inflator  14  within the canister  60 . 
     As stated above, the inflator  14  generates gas or foam for inflating the inflatable cushion  12 . The inflator  14  may use various techniques to do so. For instance, compressed gas may be released to inflate the cushion  12 . Alternatively, a pyrotechnic may generate gas to inflate the cushion  12 . Also, a combination of both pyrotechnics and compressed gas may be used to inflate the cushion  12 . The gas or foam may exit the inflator  14  via a gas exit port  80 . 
     The inflatable restraint module  10  may also include a heat shield  82 . The heat shield  82  is shaped to receive and surround the inflator  14 . The heat shield  82  may have open ends  83 . The shape of the heat shield  82  may be adapted to surround an inflator  14  of a particular size and shape in use in the inflatable restraint module  10 . For instance, when the inflator  14  is cylindrical in shape, the heat shield  82  may be a rectangular piece of fabric that can be folded to surround the inflator  14 . The heat shield  82  is designed to protect the inflatable cushion  12  from heat generated by the inflator  14  when an inflator  14  positioned within the cushion  12  is activated, as will be illustrated below. In addition, the heat shield  82  may be slightly shorter than a circumference of the inflator  14  so that, when the heat shield  82  is positioned around the inflator  14 , the heat shield  82  defines a gap  84  that provides a convenient exit route for gas exiting the inflator  14 , as illustrated in FIG.  2 . The heat shield  82  may be made from various materials that resist conducting heat, including certain fabrics, which are known to those skilled in the art. 
     Those skilled in the art will recognize that the inflatable restraint module  10  may be adapted to deploy from various locations within a vehicle (not shown). For instance, the module  10  may be embodied as a driver-side, passenger-side, side-impact, and knee bolster inflatable restrain module  10 . Also, the expandable portion  13  of the cushion  12  may be shaped to provide appropriate protection to a passenger of a vehicle from each of these deployment locations. 
     FIG. 2 is a cross-sectional view of the assembled first embodiment of the inflatable restraint module  10 . The inflator  14  is shown in a side view rather than a cross-sectional view. As illustrated, the inflator  14  is positioned within the heat shield  82 . As explained above, the heat shield  82  may define a gap  84  that provides a convenient exit route for gas leaving the inflator  14 . The gap  84  may be aligned with the opening  26  in the chamber  20  so that gas may rapidly exit the inflator  14  through the gap  84  and the opening  26  into the cushion  12 . The exit gas port or ports  80  of the inflator  14  may also be aligned with the gap  84  in the heat shield  82 . 
     The inflator  14  and heat shield  82  are positioned within the loop  16  of the cushion  12 . More specifically, as illustrated in FIG. 2, the heat shield  82  may be sewn into, or otherwise secured within, the loop  16  of the cushion  12 . The heat shield  82  may also be integrally formed with the cushion  12 . The expandable portion  13  of the cushion  12  is placed in a folded state outside of the chamber  20 . More specifically, the expanded portion  13  is folded and placed on a lip  27  of the chamber  20 . 
     As illustrated, the outward extension  28  is coupled to the cushion  12 . In this embodiment, the outward extension  28  is coupled to the cushion  12  by attachment to the cushion  12 . More specifically, a portion  86  of the cushion  12  is attached to the outward extension  28  of the chamber  20 . The portion  86  of the cushion  12  may be sewn to the outward extension  28 , as illustrated in FIG.  2 . Alternatively, the portion  86  of the cushion  12  may be attached to the extension  28  using adhesives, rivets, a nut and bolt, or the like. As such, the portion  86  of the cushion  12  is kept away from the opening  26  in the chamber  20  and is simultaneously kept away from the inflator  14 . If the portion  86  of the cushion  12  were not kept away from the inflator  14 , the cushion  12  could be damaged by heat generated by the inflator  14  during inflation. 
     The assembled inflator  14 , heat shield  82 , chamber  20 , and cushion  12  may be positioned within the canister  60 . As stated, the assembled inflator  14  and heat shield  82  may be inserted through the open side  62  of the canister  60  into the interior region  64  of the canister  60 . Thereafter, the inflator  14  is inserted into the canister  60  through the first mouth  66  such that the inflator  14  may be positioned within the interior compartment  22  of the chamber  20  and the loop  16  of the cushion  12 . 
     The heat shield  82  could be wrapped around the inflator  14  before the inflator  14  is inserted through the first mouth  66  of the canister  60 , or could simply be inserted into the first mouth  66  of the canister  60  before the inflator  14  is inserted therein. Alternatively, the heat shield  82  could be positioned within the loop  16  of the cushion  12  before the cushion  12  and chamber  20  are inserted into the canister  60  through the open side  62  of the canister  60 . 
     The inflatable restraint module  10  may operate in the following manner. A signal indicating that accident conditions exist is received by the inflator  14 . In response to the received signal, inflator gas is generated by the inflator  14 . The inflator gas exits the inflator  14  through the gas exit port  80 . The inflator gas moves through the gap  84  in the heat shield  82  and through the opening  26  in the chamber  20  into the expandable portion  13  of the cushion  12  to inflate the cushion  12 . The cushion  12  is tethered to the module  10  by the loop  16  which is positioned around the inflator  14 . Attachment of the portion  86  of the cushion  12  to the outward extension  28  keeps the portion  86  away from heat generated by the inflator  14  to prevent damage to the cushion  12 . 
     FIG. 3 is an exploded perspective view of a second embodiment of the inflatable restraint module  110 . Like the first embodiment, the second embodiment also includes a cushion  12 , inflator  14 , and heat shield  82 . The cushion  12  may again have an expandable portion  13  that expands in response to the injection of gas into the cushion  12 . A loop  16  of the cushion  12  defines orifices  18  into which the inflator  14  may be inserted. 
     The inflator  14  includes a first and a second end  72 ,  74 . The second end  74  includes an expanded portion  75 . The first end  72  of the inflator  14  may have inclined threads  76 . Inflator gas may exit the inflator  14  through one or more gas exit ports  80 . The heat shield  82  may be shaped to surround the inflator  14 , and when the heat shield  82  is positioned around the inflator  14 , the shield  82  may define a gap  84  that provides a convenient exit route for gas leaving the inflator  14 . 
     The second embodiment of the inflatable restraint module  110  includes a chamber  120 . Like the chamber  20  of the first embodiment, the chamber  120  of the second embodiment defines an interior compartment  22  having open ends  24 . The inflator  14  may be inserted into the interior compartment  22  through one of the open ends  24 . The chamber  120  may likewise define an opening  26  through which the loop  16  of the cushion  12  may be inserted. An outward extension  28  of the chamber  120  projects away from the opening  26 . 
     The chamber  120  may also include a cover  140  shaped to cover the cushion  12 . The cover  140  may be attached to or integrally formed with the outward extension  28 . A set of tabs  142  on the cover  140  may be used to secure the cover  140  over the cushion  12 , as illustrated in FIG.  4 . The set of tabs  142  may include one or more tabs. Each tab  142  may include a head  144  and a narrow stem  146 . The cover  140  may be made from various materials, such as fabric or plastic. The cover  140  will be explained in greater detail below. 
     The second embodiment of the inflatable restraint module  110  may also include a canister  160 . Like the canister  60  of the first embodiment, the canister  160  of the second embodiment includes an open side  62  through which the cushion  12  and chamber  120  may be inserted into an interior region  64  of the canister  160 . The canister  160  also includes a first and a second mouth  66 ,  68  positioned on opposing ends  70  of the canister  160  for receiving the inflator  14 . As with the first embodiment  10 , a threaded nut  78 , which is wider than the second mouth  68 , may be used to secure the inflator  14  within the canister  160 . 
     The canister  160  may include a set of apertures  161  for receiving and securely retaining the set of tabs  142  of the cover  140 . The apertures  161  may be spaced at the same distance apart as each of the tabs  142  of the cover  140 . Each aperture  161  may be slightly smaller than each head  144  of a tab  142  so that the head  144  may deform slightly when being pushed through an aperture  161 . The heads  144  may be resilient so that after deforming to fit through an aperture  161 , the heads  144  return to their former shape to prevent inadvertent removal of the set of tabs  142  from the set of apertures  161 . 
     Various techniques and mechanisms may be used to attach the cover  140  to the canister  160 . For instance, rivets, a nut and bolt, or adhesives may be used to secure the cover  140  to the canister  160 . If the cover  140  and extension  28  are not integrally formed, similar techniques and mechanisms may be used to attach the cover  140  to the outward extension  28 . Also, a separate cover  140  may be sewn to the extension  28 . Of course, material from which the cover  140  is made may be of limited strength or may include frangible seams (not shown) so that the cover  140  does not impede deployment of the inflatable cushion  12  through the cover  140 . 
     FIG. 4 is a cross-sectional view of the assembled second embodiment of the inflatable restraint module  110  with a side view of the inflator  14 . As with the first embodiment of the inflatable restraint module  10 , a heat shield  82  is positioned around the inflator  14 . The assembled heat shield  82  and inflator  14  are positioned within a loop  16  of the cushion  12 . As illustrated in FIG. 4, the heat shield  82  may be sewn into, or otherwise secured within, the loop  16  of the cushion  12 . The loop  16 , heat shield  82 , and inflator  14  are positioned within the interior compartment  22  of the chamber  120 . The expandable portion  13  of the cushion  12  is folded and placed on a lip  27  of the chamber  120 . 
     As illustrated, the outward extension  28  is coupled to the cushion  12 . In this embodiment, the outward extension  28  is coupled to the cushion  12  by attachment to the cushion  12 . More specifically, a portion  86  of the cushion  12  is attached to the extension  28  of the chamber  120  and is thus kept away from the opening  26  of the chamber  120  and the inflator  14  to prevent damage to the cushion  12  at the time of inflation. 
     The cover  140  is shaped to extend from the extension  28  across at least a portion of the open side  62  of the canister  160  to cover the cushion  12 . The set of tabs  142  on the cover  140  interface or interlock with apertures  161  on the canister  160  to secure the cover  140  over the inflatable cushion  12 . As illustrated in FIG. 4, a head  144  of a tab  142  has been pushed through the aperture  161 , and the narrow stem  146  is positioned within the aperture  161 . Alternatively, tabs (not shown) on the canister  160  may be positioned within apertures (not shown) in cover  140  to secure the cover  140  to the canister  160 . Again, other techniques and mechanisms may be used to secure the cover  140  to the canister  160 . 
     FIG. 5 is an exploded perspective view of a third embodiment of the inflatable restraint module  210 . Like the first embodiment, the third embodiment also includes a cushion  12 , inflator  14 , a canister  60 , and heat shield  82 . Again, the cushion  12  may have an expandable portion  13  that expands in response to the injection of gas into the cushion  12 . A loop  16  of the cushion  12  defines orifices  18  into which the inflator  14  may be inserted. 
     The inflator  14  includes a first and a second end  72 ,  74 . The second end  74  also includes an expanded portion  75 . The first end  72  of the inflator  14  may include inclined threads  76 . Inflator gas may exit the inflator  14  through a gas exit port  80 . 
     The heat shield  82  may be shaped to surround the inflator  14  and when the heat shield  82  is positioned around the inflator  14 , the heat shield  82  may define a gap  84  that provides a convenient exit route for gas leaving the inflator  14 . 
     The third embodiment of the inflatable restraint module  210  may also include a canister  60 . Like the canister  60  of the first embodiment, the canister  60  of the third embodiment includes an open side  62  through which the cushion  12  and chamber  220  may be inserted into an interior region  64  of the canister  60 . The canister  60  also includes a first and a second mouth  66 ,  68  positioned on opposing ends  70  of the canister  60  for receiving the inflator  14 . As with the first and second embodiments, a threaded nut  78 , which is wider than the second mouth  68  on the canister  60 , may be used to secure the inflator  14  within the canister  60 . 
     The third embodiment of the inflatable restraint module  210  includes a chamber  220 . Like the chambers  20 ,  120  of the first and second embodiments, the chamber  220  of the third embodiment defines an interior compartment  22  having open ends  24 . The inflator  14  may be inserted into the interior compartment  22  through one of the open ends  24 . The chamber  220  may likewise define an opening  26  through which the loop  16  of the cushion  12  may be inserted. An outward extension  228  of the chamber  220  projects away from the opening  26 . The extension to  28  includes a set of tabs  230 . Each tab  230  may include a head  232  and a narrow stem  234 . 
     The third embodiment includes a cover  240  shaped to cover the cushion  12 . However, the cover  240  of this embodiment is shaped differently than the cover  140  of the second embodiment. As illustrated in FIG. 5, the cover  240  has a rectangular shape. One end of the cover  240  is folded over on to itself to form a pocket  242 . The pocket is sewn to the cushion  12  along a first and a second peripheral sewn line  244   a-b  to the inflatable cushion  12 . Of course, other techniques and mechanisms for attaching the cover  240  to the inflatable cushion  12  come within the scope of this invention. For instance, adhesives, rivets, or a nut and bolt may be used to attach the cover  240  to the inflatable cushion  12 . Also, the cover  240  could be integrally formed with the cushion  12 . The cover  240  may be made from various materials, including fabrics and plastics, as will be understood by those skilled in the art. 
     The cover  240  includes a first and a second set of apertures  248 ,  250 . The first and a second set of apertures  248 ,  250  are shaped to receive the set of tabs  230  on the outward extension  228 . The set of tabs  230  includes one or more tabs  230  on the extension  228  for selectively interlocking with the first and second set of apertures  248 ,  250 . The first set of tabs  230  are positioned at a top of the pocket  242 . The technique by which the cover  240  may surround the inflatable cushion  12  will be illustrated and discussed in further detail in connection with FIG.  6 . 
     FIG. 6 is a cross-sectional view of the third embodiment of the inflatable restraint module  210 . As with the first and second embodiments, the inflator  14  is positioned within a heat shield  82 , both of which are positioned within the loop  16  of the cushion  12  and the interior compartment  22  defined by the chamber  220 . As illustrated in FIG. 6, the heat shield  82  may be sewn into, or otherwise secured within, the loop  16  of the cushion  12 . The expandable portion  13  of the cushion  12  is folded and placed on a lip  27  of the chamber  220 . 
     The outward extension  228  of the chamber  220  is coupled to the cushion  12 . In this embodiment, the outward extension  228  is coupled to the cushion  12  by attachment to the cover  240 , which is attached to the extension  228 . More specifically, a portion  86  of the cushion  12  is attached to the cover  240  and the cover  240  is attached to the extension  228  to keep the portion  86  of the cushion  12  away from the opening  26 . As a consequence, the portion  86  is kept away from heat generated by the inflator  14  during inflation of the cushion  12 . 
     As shown in FIG. 6, the extension  228  is positioned within the pocket  242  of the cover  240 . The cushion  12  and cover  240  are attached to the extension  228  by placing the first set of apertures  248  in the cover  240  on the tabs  230  of the extension  228 . Again, the heads  232  of the tabs  230  are wider than the apertures  248  in the cover  240  to securely retain the apertures  230  on the narrow stem  234  of the tabs  230 . The cover  240  is wrapped around the cushion  12  and chamber  220 . The second set of apertures  250  is then positioned on the set of tabs  230  to secure the cover  240  around the cushion  12  and chamber  220 . Thus, the cover  240  is attached to the extension  228  using the sets of apertures  248 ,  250  in the cover  240  and the mating set of tabs  230  on the extension  228 . In an alternative embodiment, the second set of apertures  250  could be positioned on tabs (not shown) on the canister  60  to secure the cover  240  over the cushion  12 . Other techniques may be used to attach the cover  240  to the extension  228 . For instance, the cover  240  may be sewn to the extension  228 . Alternatively, rivets, a nut and bolt, or the like may be used to secure the cover  240  to the extension  228 . 
     The assembled cover  240 , chamber  220 , cushion  12 , heat shield  82 , and inflator  14  may be positioned, or at least partially positioned, within the canister  60 . The canister  60  protects the cover  240 , chamber  220 , cushion  12 , heat shield  82 , and inflator  14  from damage and enables the module  210  to be attached to a vehicle. 
     In view of the foregoing, the inflatable restraint module provides substantial advantages over conventional airbag modules. The individual components of the inflatable restraint module are simple in design and, as a consequence, are less expensive to manufacture than conventional module components. Many of the components may be made from plastic or fabric rather than metal, further diminishing the cost and weight of the module. 
     The present invention may be embodied in other specific forms without departing from its scope or essential characteristics. The described embodiments are to be considered in all respects only illustrative, not 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.