Abstract:
An inflatable curtain airbag can be used to cushion an occupant during a vehicle collision as well as retaining the occupant within the vehicle during a rollover event. Curtain airbags that do not extend to the vehicle&#39;s waist line may allow the occupant to fit between the bottom of the curtain airbag and the waistline, and thereby be ejected from the vehicle. This risk is increased with vehicles that do not have vertical pillars between the doors and windows of the vehicle. Increasing an inflation gas volume capacity of a lower portion of the airbag, may mitigate the risk of occupant ejection, if the increased volume portion of the curtain overlaps the vehicle pillars. The lower portion of the curtain airbag may have a first chamber and a separate second chamber.

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to the field of automotive protective systems. More specifically, the present disclosure relates to inflatable curtain airbags, which may provide improved cushioning for an occupant during a collision event and improve retention of the occupant within the vehicle during a rollover event. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present embodiments will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that the accompanying drawings depict only typical embodiments, and are, therefore, not to be considered to be limiting of the disclosure&#39;s scope, the embodiments will be described and explained with specificity and detail in reference to the accompanying drawings. 
         FIG. 1  is a side elevation view of an inflatable curtain airbag assembly. 
         FIG. 2  is a side elevation cross-sectional view of the inflatable curtain airbag assembly of  FIG. 1 . 
         FIG. 3  is another side elevation cross-sectional view of the inflatable curtain airbag assembly of  FIG. 1 . 
         FIG. 4  is a top elevation cross-sectional view of the inflatable curtain airbag assembly of  FIG. 1 . 
         FIG. 5  is another top elevation cross-sectional view of the inflatable curtain airbag assembly of  FIG. 1 . 
         FIG. 6  is a side elevation view of another embodiment of an inflatable curtain airbag assembly. 
         FIG. 7  is a side elevation cross-sectional view of the inflatable curtain airbag assembly of  FIG. 6 . 
         FIG. 8  is a side elevation view of another embodiment of an inflatable curtain airbag assembly. 
         FIG. 9  is a side elevation cross-sectional view of the inflatable curtain airbag assembly of  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     It will be readily understood that the components of the embodiments, as generally described and illustrated in the figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of various embodiments, as represented in the figures, is not intended to limit the scope of the disclosure, as claimed, but is merely representative of various embodiments. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated. 
     The phrases “connected to,” “coupled to” and “in communication with” refer to any form of interaction between two or more entities, including mechanical, electrical, magnetic, electromagnetic, fluid, and thermal interaction. Two components may be coupled to each other even though they are not in direct contact with each other. The term “abutting” refers to items that are in direct physical contact with each other, although the items may not necessarily be attached together. 
     Inflatable airbag systems are widely used to minimize occupant injury in a collision scenario. Airbag modules have been installed at various locations within a vehicle, including, but not limited to: the steering wheel, the instrument panel, within the side doors or side seats, adjacent to the roof rail of the vehicle, in an overhead position, or at the knee or leg position. In the following disclosure, “airbag” may refer to an inflatable curtain airbag, overhead airbag, front airbag, or any other airbag type. 
     Inflatable curtain airbags may be used to protect the passengers of a vehicle during a side collision or roll-over collision. Inflatable curtain airbags typically extend longitudinally within the vehicle and are usually coupled to or next to the roof rail of the vehicle. The inflatable curtain airbag may expand in a collision scenario along the side of the vehicle between the vehicle passengers and the side structure of the vehicle. In a deployed state, an inflatable curtain airbag may cover at least a portion of the side windows and the B-pillar of the vehicle. In some embodiments, inflatable curtain airbags may extend from the A-pillar to the C-pillar of the vehicle. In alternative embodiments, inflatable curtain airbags may extend from the A-pillar to the D-pillar of the vehicle. 
     Inflatable curtain airbags are typically installed adjacent the roof rail of a vehicle in an undeployed state, in which the inflatable curtain airbag is rolled or folded or a combination thereof and retained in the rolled and/or folded configuration by being wrapped at certain points along the airbag. The rolled and/or folded configuration may be called a “packaged” configuration. When deployed, the airbag exits the packaged state and assumes an extended state, wherein the airbag is inflated. The extended and inflated state may be called a “deployed” state or configuration. Thus, an airbag mounting apparatus typically allows for a secure connection between the vehicle and the airbag, yet allows the airbag to change configurations from the packaged configuration to the deployed configuration. 
     Inflatable curtain airbags may include attachment tabs at the top edge and at various locations along the longitudinal length of the inflatable curtain airbag. In some embodiments, the inflatable curtain may not have tabs, but rather the curtain may have an uninflatable portion that is on the top edge of the curtain. During a conventional installation, bolts or other fasteners are used to attach the curtain to the roof rail via the tabs or uninflatable areas. Often, a mounting bracket is employed to couple the curtain to the roof rail. 
       FIG. 1  is a side elevation view of an inflatable curtain airbag assembly  100 . Airbag assembly  100  may comprise an inflatable airbag membrane  110 , and an inflator  140 . Assembly  100  is configured to provide impact protection and ejection mitigation for occupants of a vehicle  10 . Vehicle  10  has a roof rail  12 , a waist line  13 , an A-pillar  14 , a B-pillar  15 , a C-pillar  16 , a D-pillar  17 , and windows  18 . Waist line  13  may also be known as a “belt line” and is defined as a substantially horizontal line formed by the junction of vehicle windows  13  and tops of vehicle door panels. In other words, the waist line may be formed by the window sills of the vehicle doors. 
     According to the embodiment depicted in  FIG. 1 , airbag  110  has an upper portion  111 , a lower portion  112 , a front face  113 , a rear face (not visible), an outer seam  115 , inflation cells  116 , inner seams  117 , uninflatable portions  118 , and an inflatable void (not visible). The various faces of airbag membrane  110  define the inflatable void, which is in fluid communication with an inflator  140 . The various faces of airbag  110  may be attached to each other using an outer seam  115  that comprise stitching. Likewise, inner seams  117  may comprise stitching and may couple the front and rear faces together, as well as forming uninflatable portions  118  and inflation cells  116 . In the depicted embodiment, airbag  110  is an inflatable curtain airbag, which extends from an A-pillar  14  to a D-pillar  17 . Airbag  110  also extends past a B-pillar  15  and a C-pillar  16  such that in a deployed configuration, the airbag at least partially covers the B- and C-pillars. 
     Upper portion  111  of airbag  110  is the portion of the airbag that is closest to the headliner of a vehicle when the airbag is in a deployed state. Lower portion  112  is below upper portion  111  when airbag  110  is in a deployed state, and is closest to a floor of the vehicle. The term “lower portion” is not necessarily limited to the portion of airbag  110  that is below a horizontal medial plane of the airbag, but may include less than half, more than half or exactly half of the bottom portion of the airbag. Likewise, the term “upper portion” is not necessarily limited to the portion of airbag  110  that is above a horizontal medial plane of the airbag, but may include less than half, more than half or exactly half of the top portion of the airbag. 
     Inflator  140  may be attached to roof rail  12 , or any other suitable vehicle structure. Upon activation, inflator  140  rapidly generates or releases inflation gas, which forces airbag  110  through a cosmetic cover on roof rail  12  and rapidly inflates the airbag. The inflator may be one of several types, such as pyrotechnic, stored gas, or a combination inflator and may comprise a single stage or multistage inflator. 
     As will be appreciated by those skilled in the art, a variety of types and configurations of airbag membranes can be utilized without departing from the scope and spirit of the present disclosure. For example, the size, shape, and proportions of the airbag membrane may vary according to its use in different vehicles. Also, the airbag membrane may comprise one or more materials that are well known in the art, such as a woven nylon fabric. Additionally, the airbag may be manufactured using a variety of techniques such as one piece weaving, cut and sew, or a combination of the two techniques. Further, the airbag membrane may be manufactured using sealed or unsealed seams, wherein the seams are formed by stitching, adhesive, taping, radio frequency welding, heat sealing, or any other suitable technique or combination of techniques. 
     One skilled in the art will also appreciate that the size, shape and distribution of the inflation cells depicted in  FIG. 1  are for exemplary purposes and may vary from the depiction. Further, in order for the fully inflated airbag to adopt a predetermined shape, internal and/or external tethers may be used, wherein the tethers limit the expansion of the airbag and restrict it to the predetermined shape or apply tension to predetermined portions of the airbag. Tethers are typically coupled to one or more surfaces of an airbag membrane and extend to another surface of the airbag, the airbag housing, or a vehicle structure. 
       FIGS. 2-3  are side elevation cross-sectional views of portions of vehicle  10  and airbag assembly  100  depicting roof rail  12 , waist line  13 , window  18  ( FIG. 2 ) or B-pillar  15  ( FIG. 3 ), and a space between the vehicle and the airbag  19 . Also depicted in  FIGS. 2-3  is inflatable airbag  110  and its upper portion  111 , lower portion  112 , front face  113 , rear face  114 , uninflatable portions  118 , and the inflatable void  119 . 
       FIG. 2  depicts a side elevation cross-sectional view of vehicle  10  and assembly  100  at window  18 , which is between the B-pillar and the C-pillar. In this depiction, bottom portion airbag  110  does not overlap waistline  13 . Window  18  is not perpendicular to the ground; rather the window is slanted out from top to bottom. At cross section line  2 - 2  of  FIG. 1 , airbag  110  has two inflatable voids  119 , wherein the inflatable void portion of the airbag that is on upper portion  111  has a smaller volume than the inflatable void portion of the airbag that is on lower portion  112 . As such, airbag  110  may be said to have an asymmetrical side elevation cross-section. In other words the side elevation cross-section of airbag  110  may be said to be pear-shaped. In another embodiment, the inflatable airbag curtain airbag may be said to be tear-drop shaped. The lower portion may be configured such that the lower portion lacks inflation cells, or has a fewer number of inflation cells than the top portion. In this way, the volume of the lower portion may not be as constrained as the top portion. Airbag  110  is configured such that a distance D 1  from inflatable void  119  of top portion  111  to window  18  is similar to the distance D 2  from the inflatable void  110  of bottom portion  112  to window  18 . 
     By way of example, and not limitation, in various embodiments, a cross-sectional width of the upper inflation chamber of upper portion  111 , as shown in  FIG. 2 , has a magnitude of about 0 mm to about 250 mm, and a cross-sectional width of the lower inflation chamber of lower portion  112  has a magnitude of about 350 mm to about 400 mm upper portion. However, as one skilled in the art will recognize, the actual widths of the inflatable curtain cushion may be varied for use in different vehicle environments. 
       FIG. 3  depicts a side elevation cross-sectional view of vehicle  10  and assembly  100  at B-pillar  15 . B-pillar  15  is not perpendicular to the ground or to a horizontal axis of vehicle  10 . Also, B-pillar is not perpendicular to a vertical axis of vehicle  10 . At cross section line  3 - 3  of  FIG. 1 , airbag  110  has a single inflatable void  119  that spans the top portion and the bottom portion of the airbag, and the airbag does not overlap waist line  13 . The side elevation cross-sectional shape of the inflatable void is pear-shaped, such that bottom portion  112  of the airbag has a larger cross-section than top portion  111 . It may also be said that the bottom portion has a larger volume than the top portion. Since B-pillar is not perpendicular to the ground, but rather extends outwardly from the top of the pillar to the bottom, airbag  110  is configured to be pear-shaped so that the distance between B-pillar  15  and rear face  114  of airbag  110  is similar from top portion  111  to bottom portion  112 . In other words, the airbag curtain has a surface facing the pillars that follows the contours of the pillars such that the surface is located at an approximately equal distance from the top to the bottom of each pillar. Space  19  between an inner surface of B-pillar  15  and airbag  110  may be the same for the C-pillar as the B-pillar. Also, space  19  may not exist as airbag  110  may be configured such that rear face  114  abuts the inner surface of B-pillar  15 . 
     An inflatable curtain airbag that does not overlap the waistline of a vehicle may swing outwardly when an occupant impacts the airbag during a collision and/or rollover event. This is especially true when a non-waistline overlapping airbag is used in a vehicle with windows or pillars that extend outwardly. When in a deployed state, the asymmetrical side elevation cross-section of airbag  110  allows more tension to be placed on bottom portion  112  than would occur if the airbag were symmetrical. As such, the extra volume of the lower portion of airbag  110  allows the airbag to mitigate the risk of occupant ejection. 
     One skilled in the art will recognize that the size and distribution of the larger volume portions of the airbag may vary. For example, the entire side elevation cross-sectional shape of the airbag may not be pear-shaped. For example, at some portions of the airbag, the airbag may not comprise an upper inflatable void. At other portions of the airbag, the airbag may not have any inflatable voids. At some portions of the airbag, the airbag may have a symmetrical side elevation cross-section. Further, one skilled in the art will recognize that in some embodiments, the inflatable void of the bottom portion may run the entire length of airbag  110  and may not have a larger cross-section than other inflatable voids within the airbag. 
     By way of example, and not limitation, in various embodiments, a cross-sectional width of the upper inflation chamber of upper portion  111 , as shown in  FIG. 3 , has a magnitude of about 0 mm to about 250 mm, and a cross-sectional width of the lower inflation chamber of lower portion  112  has a magnitude of about 350 mm to about 400 mm. However, as one skilled in the art will recognize, the actual widths of the inflatable curtain cushion may be varied for use in different vehicle environments. 
       FIGS. 4-5  are top elevation cross-sectional views of portions of vehicle  10  and assembly  100 . Vehicle  10  is depicted at B-pillar  15  and C-pillar  16 , wherein a window  18  is visible between the pillars as well as the side of each pillar. Airbag  110  is depicted at top portion  111  ( FIG. 4 ) and bottom portion  112  ( FIG. 5 ) wherein front face  113 , rear face  114  and inflatable void  119  are visible. Space  19  between vehicle  10  and airbag  110  is about equal between top portion  111  and bottom portion  112 . In the depiction of  FIG. 4 , top portion  111  of airbag  110  has two inflatable voids  119 . In the depiction of  FIG. 5 , bottom portion  112  of airbag  110  has a single inflatable void that runs continuously along airbag  110 . In the depictions of  FIGS. 4-5 , a distance between front face  113  and rear face  114  of the inflatable voids of airbag  110  is smaller for upper portion  111  than lower portion  112 . 
       FIG. 6  is a side elevation view of another embodiment of an inflatable airbag assembly  200  that is configured to mitigate the risk of occupant ejection. Airbag assembly  200  may be configured similarly to, and may function similarly as airbag assembly  100 , described herein. Inflatable airbag assembly  200  may comprise an inflatable airbag  200 , a second chamber  230 , and an inflator  240 . Assembly  200  is configured to impact protection and ejection mitigation for occupants of a vehicle  10 . Vehicle  10  has a roof rail  12 , a waist line  13 , an A-pillar  14 , a B-pillar  15 , a C-pillar  16 , a D-pillar  17 , and windows  18 . Waist line  13  may also be known as a belt line and is defined as a substantially horizontal line formed by the junction of vehicle windows  13  and tops of vehicle door panels. In other words, the waist line may be formed by the window sills of the vehicle doors. 
     According to the embodiment depicted in  FIG. 6 , airbag  210  has an upper portion  211 , a lower portion  212 , a front face  213 , a rear face (not visible), an exterior seam  215 , inflation cells  216 , interior seams  217 , uninflatable portions  218 , an inflatable void (not visible), and a first chamber  220 . The various faces of airbag membrane  210  define the inflatable void, which is in fluid communication with an inflator  240 . The various faces of airbag  210  may be attached to each other using an outer seam  215  that comprise stitching. Likewise, inner seams  216  may comprise stitching and may couple the front and rear faces together, as well as forming uninflatable portions  218  and inflation cells  215 . In the depicted embodiment, airbag  210  is an inflatable curtain airbag, which extends from an A-pillar  14  to a D-pillar  17 . Airbag  210  also extends past a B-pillar  15  and a C-pillar  16  such that in a deployed configuration, the airbag at least partially covers the B- and C-pillars. Second chamber  230  is configured to cover predetermined vehicle pillars, such as B-pillar  15  and C-pillar  16 , in a longitudinal manner. 
     Upper portion  211  of airbag  210  is the portion of the airbag that is closest to the headliner of a vehicle when the airbag is in a deployed state. Lower portion  212  is below upper portion  211  when airbag  210  is in a deployed state, and is closest to a floor of the vehicle. The term “lower portion” is not necessarily limited to the portion of airbag  210  that is below a horizontal medial plane of the airbag, but may include less than half, more than half or exactly half of the bottom portion of the airbag. Likewise, the term “upper portion” is not necessarily limited to the portion of airbag  210  that is above a horizontal medial plane of the airbag, but may include less than half, more than half or exactly half of the top portion of the airbag. 
       FIG. 7  depicts a side elevation cross-sectional view of vehicle  10  and assembly  200  at B-pillar  15 . At cross section line  7 - 7  of  FIG. 6 , airbag  210  has an inflatable void  219  defined by front and rear faces  213  and  214 . Inflatable void  219  spans top portion  211  and bottom portion  212  of the airbag. Airbag  210  does not overlap waist line  13 . First chamber  220  may comprise an entirety of inflatable void  219 , or the first chamber may comprise one or more inflation cells located on bottom portion  212  of airbag  210 . The side elevation cross-sectional shape of inflatable void  219  is substantially symmetrical, such that top portion  211  of airbag  210  has a cross-section width that is similar to bottom portion  212 . Since B-pillar  15  is not perpendicular to the ground, but rather extends outwardly from the top of the pillar to the bottom, airbag  210  is closer to B-pillar  15  at top portion  211  than bottom portion  212 . As such, the space  19  between bottom portion  212  of airbag  210  is greater than the space  19  between top portion  211  and B-pillar  15 . 
     As indicated above, an inflatable curtain airbag that does not overlap the waistline of a vehicle may swing outwardly when an occupant or object impacts the airbag during a collision and/or rollover event, which is especially true when a non-waistline overlapping airbag is used in a vehicle with windows or pillars that extend outwardly. As such, a second chamber  230  may be used in conjunction with airbag  210 , which has a symmetric side elevation cross-section. Second chamber  230  is located between an inner surface of B-pillar  15  and first chamber  230 . Second chamber  230  has a front face  233  and a rear face  234 , which may be coupled together at an outer seam. Second chamber  230  may be considered an extension of lower portion  212 , wherein the second chamber comprises one or more additional inflation cells. Alternatively, second chamber  230  may be considered a separate inflatable airbag that is fluidly coupled to airbag  210 . When in a deployed state, second chamber  230  allows more tension to be placed on bottom portion  212  of airbag  210  than would occur if the second chamber were not present. As such, second chamber  230  and airbag  210  mitigate the risk of occupant ejection. 
     Second chamber  230  may be coupled to rear face  214  of airbag  210  at uninflatable portions of airbag  210  and the second chamber. Second chamber  230  may only be coupled to airbag  210  at a vent  231 , which is configured to allow inflation gas to pass from inflatable void  219  of airbag  210  to inflatable void  239  of the second chamber. As such, airbag  210  and second chamber  230  may be said to be in fluid communication. Also, inflatable void  219  and inflatable void  239  may be said to be in fluid communication. In one embodiment, vent  231  comprises a one-way valve. 
     Inflation gas may enter airbag  210  first and then enter second chamber  230 , or alternatively, the inflation gas may enter the second chamber first and then enter airbag  210 . Airbag  210  and second chamber  230  may be inflated by a single inflator or by multiple inflators. Second chamber  230  may comprise a single inflation cell, or alternatively, the chamber may be divided into more than one inflation cell via interior seams, which may comprise stitching. Second chamber  230  may be anchored to one or more vehicle structures via one or more tethers, independently of airbag  210 , or alternatively, chamber  230  may only be coupled to vehicle structures via airbag  210 . In one embodiment, chamber  230  is anchored to vehicle structures both independent of airbag  210  and via airbag  210 . 
     Upon activation of an inflator and airbag  210  deployment, second chamber  230  assumes a predetermined location, which may be said to be predominantly along bottom portion  212  of airbag  210 . Second chamber  230  is configured to cover predetermined vehicle pillars, such as B-pillar  15  and C-pillar  16 , in a longitudinal manner (as depicted in  FIG. 6 ). Second airbag  230  may be configured such that it does not overlap waist line  13 . The size and shape of second chamber  230 , as depicted in  FIGS. 6-7  are for exemplary purposes only, and one skilled in the art will recognize that a variety of configurations of second chambers may be employed. For example, the height to which the second chamber achieves relative to the curtain airbag may be higher or lower than depicted. Further, the side elevation cross-sectional shape may vary from that depicted. 
       FIG. 8  is a side elevation view of another embodiment of an inflatable airbag assembly  300  that is configured to mitigate the risk of occupant ejection. Airbag assembly  300  may be configured similarly to, and may function similarly as airbag assemblies  100  and  200 , described herein. Inflatable airbag assembly  300  may comprise an inflatable airbag  310 , a second chamber  330 , a first inflator  340  and a second inflator  350 . Assembly  300  is configured to impact protection and ejection mitigation for occupants of a vehicle  10 . Vehicle  10  has a roof rail  12 , a waist line  13 , an A-pillar  14 , a B-pillar  15 , a C-pillar  16 , a D-pillar  17 , and windows  18 . Waist line  13  may also be known as a belt line and is defined as a substantially horizontal line formed by the junction of vehicle windows  13  and tops of vehicle door panels. In other words, the waist line may be formed by the window sills of the vehicle doors. 
     According to the embodiment depicted in  FIG. 8 , airbag  310  has an upper portion  311 , a lower portion  312 , a front face  313 , a rear face (not visible), an exterior seam  315 , inflation cells  316 , interior seams  317 , uninflatable portions  318 , an inflatable void (not visible), and a first chamber  320 . The various faces of airbag membrane  310  define the inflatable void, which is in fluid communication with an inflator  340 . The various faces of airbag  310  may be attached to each other using an outer seam  315  that comprise stitching. Likewise, inner seams  316  may comprise stitching and may couple the front and rear faces together, as well as forming uninflatable portions  318  and inflation cells  315 . In the depicted embodiment, airbag  310  is an inflatable curtain airbag, which extends from an A-pillar  14  to a D-pillar  17 . Airbag  310  also extends past a B-pillar  15  and a C-pillar  16  such that in a deployed configuration, the airbag at least partially covers the B- and C-pillars. 
     Second chamber  330  is configured to cover predetermined vehicle pillars, such as B-pillar  15  and C-pillar  16 , in a longitudinal manner. Second chamber  330  is inflated by inflator  350  via an inflator tube  351 . Inflator  350  comprises a different inflator than inflator  340 , and second chamber  330  is configured such that inflation gas may not pass between the first and second chambers. 
     Upper portion  311  of airbag  310  is the portion of the airbag that is closest to the headliner of a vehicle when the airbag is in a deployed state. Lower portion  312  is below upper portion  311  when airbag  310  is in a deployed state, and is closest to a floor of the vehicle. The term “lower portion” is not necessarily limited to the portion of airbag  310  that is below a horizontal medial plane of the airbag, but may include less than half, more than half or exactly half of the bottom portion of the airbag. Likewise, the term “upper portion” is not necessarily limited to the portion of airbag  310  that is above a horizontal medial plane of the airbag, but may include less than half, more than half or exactly half of the top portion of the airbag. 
       FIG. 9  depicts a side elevation cross-sectional view of assembly  300  at B-pillar  15 . At cross section line  9 - 9  of  FIG. 8 , airbag  310  has an inflatable void  319  defined by front and rear faces  313  and  314 . Inflatable void  319  spans top portion  311  and bottom portion  312  of the airbag, and may be called a first chamber  320 . First chamber  320  may comprise one or more inflation cells. Airbag  310  does not overlap waist line  13 . The side elevation cross-sectional shape of inflatable void  319  is substantially symmetrical, such that top portion  311  of airbag  310  has a cross-section width that is similar to bottom portion  312 . Since B-pillar  15  is not perpendicular to the ground, but rather extends outwardly from the top of the pillar to the bottom, airbag  310  is closer to B-pillar  15  at top portion  311  than bottom portion  312 . As such, the space  19  between bottom portion  312  of airbag  310  is greater than the space  19  between top portion  311  and B-pillar  15 . 
     Second chamber  330  may comprise a front face  333 , a rear face  334 , and an inflatable void  339 . Second chamber  330  may be configured similarly to second chamber  230 , described herein, except that second chamber  330  is not in fluid communication with inflatable void  319  of airbag  310 . Second chamber  330  is in fluid communication with a second inflator, which is distinct from the inflator that inflates first chamber  320 . As such, an inflator tube  351  may be employed in some embodiments such that interior void  339  is fluidly coupled to the second inflator. Therefore, second chamber  330  may be considered a separate airbag from curtain airbag  310 . Alternatively, inflatable void  339  may be inflated by the same inflator as inflatable void  319 , wherein inflation gas flowing into inflatable void  319  follows a different path than inflation gas that flows into inflatable void  329 . In such an embodiment, inflator tube  351  may be coupled to the first inflator. 
     Any methods disclosed herein comprise one or more steps or actions for performing the described method. The method steps and/or actions may be interchanged with one another. In other words, unless a specific order of steps or actions is required for proper operation of the embodiment, the order and/or use of specific steps and/or actions may be modified. 
     Reference throughout this specification to “an embodiment” or “the embodiment” means that a particular feature, structure or characteristic described in connection with that embodiment is included in at least one embodiment. Thus, the quoted phrases, or variations thereof, as recited throughout this specification are not necessarily all referring to the same embodiment. 
     Similarly, it should be appreciated that in the above description of embodiments, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure. This method of disclosure, however, is not to be interpreted as reflecting an intention that any claim require more features than those expressly recited in that claim. Rather, as the following claims reflect, inventive aspects lie in a combination of fewer than all features of any single foregoing disclosed embodiment. Thus, the claims following this Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment. This disclosure includes all permutations of the independent claims with their dependent claims. 
     Recitation in the claims of the term “first” with respect to a feature or element does not necessarily imply the existence of a second or additional such feature or element. Elements recited in means-plus-function format are intended to be construed in accordance with 35 U.S.C. §112 ¶6. It will be apparent to those having skill in the art that changes may be made to the details of the above-described embodiments without departing from the underlying principles of the invention. Embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.