Abstract:
An airbag mounted on a bulkhead wall of an aircraft inflates downward in front of bulkhead seat occupants in a direction configured to make a first contact with a seat occupant&#39;s head. In a normal, deflated state, the airbag is mounted in a roll or folded bundle at a location on a bulkhead wall that approximately corresponds to an average seat occupant&#39;s chest or head height. Upon detonation of a pyrotechnical gas generator, the airbag unfolds initially downward. With increasing volume of the airbag, its increasing thickness pressing against the wall makes the airbag protrude from the wall toward a seat occupant&#39;s face so that the first contact with the airbag is made by the face of the seat occupant. The airbag may extend across a seat row and have adjacent chambers providing protection for seat occupants in adjacent seats.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to an airbag arrangement in an aircraft for the protection of bulkhead seat occupants. 
       BACKGROUND OF THE INVENTION 
       [0002]    Airbags have been credited for saving lives by damping impact of a vehicle crash on a vehicle occupant. Not only frontal airbags are in use, but also side impact airbags, such as curtain airbags expanding from the roof line of a vehicle or airbags arranged in a center console or armrest between two car seats. After the gas generator is triggered, the airbag unfolds and provides padding for the seat occupant. An airbag arranged in an armrest pushes itself between the seats and between seat occupants sitting next to each other. Another known airbag design provides an airbag in the vicinity of the center tunnel of the vehicle that inflates above the heads of the vehicle occupants to protect the occupants in the event of a vehicle rollover or of an “off-side” impact. 
         [0003]    Airbags are designed to provide a synergetic effect with seat belts that restrain seat occupants in a defined position. At least the front seats of a vehicle and increasingly also the rear seats are provided with three-point seatbelts comprising a lap belt and a shoulder harness extending diagonally across a seat occupant&#39;s chest. The shoulder harness limits the forward movement of a seat occupant&#39;s upper body in the event of a frontal impact. 
         [0004]    In contrast, aircraft passenger seats are usually only equipped with a two-point seatbelt, which is a lap belt without shoulder harness. In the event of a high deceleration of an aircraft, for instance during an emergency landing or a collision, the torso of a passenger is catapulted forward absent a shoulder harness. This constitutes a potentially dangerous situation, especially for passengers seated behind a wall in so-called bulkhead seats, where a forward movement is not limited by a padded seat back in front of the passenger. The passenger head may hit the wall or be flung downward without restraint. 
       SUMMARY OF THE INVENTION 
       [0005]    The object of the present invention is to provide an apparatus that improves the safety of aircraft seat occupants in bulkhead seats in the event of a high longitudinal deceleration. 
         [0006]    According to the invention, this object is achieved by an airbag arrangement on a bulkhead wall that inflates in front of bulkhead seat occupants in a direction configured to make a first contact with a seat occupant&#39;s head. In a normal, deflated state, the airbag is mounted in a roll or folded bundle at a location on a bulkhead wall that approximately corresponds to an average seat occupant&#39;s seated chest or head height. Upon detonation of a pyrotechnical gas generator, the airbag unfolds in front of the seat occupant. With increasing volume of the airbag, its increasing thickness pressing against the wall makes the airbag protrude from the wall toward a seat occupant&#39;s face. When the seat occupant&#39;s head and torso, due to inertia, approach the wall, the first contact with the airbag is made by the face of the seat occupant. Any further forward and downward movement of the seat occupant&#39;s head and upper torso is dampened by the inflated airbag that acts like a voluminous pillow. The occupant&#39;s head sinks into the airbag and is prevented from whipping downward. 
         [0007]    When several adjacent seats are arranged facing the wall, a plurality of airbag segments may be joined to a multi-seat airbag, each segment dimensioned to protect one seat occupant. The airbag segments may be inflated by one gas generator feeding all segments. Alternatively, each segment can feature its own gas generator with a discrete gas volume for each occupant. 
         [0008]    In order to position the airbag relative to a seat occupant&#39;s head, an upper and a lower portion of each airbag section may be connected with a tether creating a horizontal fold that bends the lower portion toward the seat occupant for effective cushioning of the seat occupant&#39;s upper torso. 
         [0009]    Further details and advantages become apparent from the following description of an embodiment of the invention. The drawings are provided solely for illustrative purposes and are not intended to limit the invention to the details shown. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    In the drawings, 
           [0011]      FIG. 1  shows a an aircraft bulkhead seat with an inflated airbag and a seat occupant after a frontal impact; 
           [0012]      FIG. 2  shows the same situation as  FIG. 1  without an airbag; 
           [0013]      FIG. 3  shows a fabric pattern for an airbag extending across three seat widths with three airbag segments; 
           [0014]      FIG. 4  shows the airbag of  FIG. 3  in an inflated state; and 
           [0015]      FIGS. 5   a - e  shows a sequence of events in the time window between a frontal impact and the situation shown in  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]      FIG. 2  shows an ordinary aircraft seat  50  located behind a bulkhead wall  60 . The seat  50  features a lap belt  62  securing a seat occupant  64  in the seat  50 . After a frontal impact or large longitudinal deceleration of the aircraft, the head  66  and the upper torso  68  of the seat occupant  64  are thrown forward by inertia, causing the head  66  and upper torso  68  to move to the front and around the lap belt  62  that produces a hinging motion. Depending on the deceleration magnitude, the head  66  may in incur a whipping movement downward when the upper torso  68  is stopped from moving further by the seat occupant&#39;s legs  72 . This head movement exerts high forces on the seat occupant&#39;s neck  70  and may lead to injuries. 
         [0017]    In contrast to the prior art configuration of  FIG. 2 ,  FIG. 1  shows an arrangement according to the present invention. The aircraft seat  50 , the lap belt  62 , and the bulkhead wall  60  are shown in the same positions relative to each other as in  FIG. 2 . The seat occupant  64  has been exposed to the same longitudinal deceleration as in  FIG. 2 . The bulkhead wall  60 , however, features a bulkhead airbag  10  that is inflated during a deceleration event before the head  66  has approached the bulkhead wall  60 . Accordingly, the head  66  contacts the inflated airbag  66  instead of continuing to move downward. The head  66  and the upper torso  68  retain an angle between each other that reduces the risk of neck injuries compared to the situation with a bare bulkhead wall  60  shown in  FIG. 2 . 
         [0018]      FIG. 3  shows an exemplary airbag  10  in a deflated, unfolded state. As is evident from  FIG. 3 , the airbag  10  can be constructed as a multi-passenger airbag. The airbag  10  of  FIG. 3  features a face layer  30  and a wall layer  32  of fabric forming three chambers  12 ,  14 , and  16  aligned next to each other. The face layer  30  faces the seat occupant  64  when inflated, and the wall layer  32  faces the bulkhead wall  60 . The three chambers  12 ,  14 , and  16  are each assigned to one seat occupant  64 , respectively, sitting in adjacent seats  50 . In an inflated state as further discussed in connection with  FIG. 4 , each of the chambers  12 ,  14 , and  16  has a width that corresponds to the width of seat  50  so that each chamber  12 ,  14 , and  16  extends across the front of one seat  50 . The chambers  12  and  14  are connected through an upper channel  18  and a lower channel  20 . Likewise, the chambers  14  and  16  are connected through an upper channel  22  and a lower channel  24 . The channels  18  and  20  are formed by a first barrier  26 , and the channels  22  and  24  are formed by a second barrier  28 . The barriers  26  and  28  may be seams or baffles and connect the face layer  30  with the wall layer  32 . The barriers leave the upper channels  18  and  22  with a smaller opening than the lower channels  20  and  24 . 
         [0019]    Each chamber  12 ,  14 , and  16  has a port  34 ,  36 , and  38 , respectively, arranged along the same top edge of the airbag. Each port  34 ,  36 , and  38  is connected to a respective gas generator  74 ,  76 , or  78  for inflating the airbag  10  during a deceleration event. Accordingly, while each chamber  12 ,  14 , and  16  is individually inflated primarily by a designated gas generator  74 ,  76 , or  78 , the chambers can also communicate and exchange inflation gas through the channels  18  through  24 . 
         [0020]    Notably, due to the small diameter of the upper channels  18  and  22 , most of the gas generated by the gas generator  74 ,  76 , or  78  associated with a given chamber  12 ,  14 , or  16  fills the associated chamber first before reaching the lower channels  20  and  24  that provide a large diameter for communication. Thus, should one of the gas generators fail, the two remaining gas generators provide inflation gas for the chamber associated with the failing gas generator. Alternatively, one single gas generator, for example the centrally located gas generator  76 , may be dimensioned to inflate all connected chambers. Such an arrangement sames costs by replacing the three gas generators  74 ,  76 , and  78 , with only one gas generator  76 . 
         [0021]    In  FIG. 3 , pairs of attachment points  40   a  and  40   b,    41   a  and  41   b,    42   a  and  42   b,    43   a  and  43   b,    44   a  and  44   b,  and  45   a  and  45   b  for tethers  40 ,  41 ,  42 ,  43 ,  44 , and  45  are indicated with dotted lines.  FIG. 4  illustrates the function of the attachment points  40   a  and  40   b,    41   a  and  41   b,    42   a  and  42   b,    43   a  and  43   b,    44   a  and  44   b,  and  45   a  and  45   b  in more detail. 
         [0022]      FIG. 4  shows the airbag  10  of  FIG. 3  in an inflated state. The tethers  40 ,  41 ,  42 ,  43 ,  44 , and  45  are each connected with a first end to a first attachment point,  40   a,    41   a,    42   a,    43 ,  44   a,  and  45   a,  located near a side of each chamber  12 ,  14 , and  16  at a height at which the barriers  26  and  28  divide the airbag  10  into the chambers  12 ,  14 , and  16  as shown in  FIG. 3 . A second end of each tether  40 ,  41 ,  42 ,  43 ,  44 , and  45  is connected to a second attachment point  40   a,    41   a,    42   a,    43 ,  44   a,  and  45   a  located at a height at which the chambers  12 ,  14 , and  16  communicate through the lower channels  20  and  24 . The tethers  40 - 45  are shorter than the distance between their associated attachment points on the face layer  30  of the airbag  10 . Accordingly the airbag  10  inflates in an angled state with a horizontal fold in the face layer indicated by reference numeral  46 . The fold  46  extends approximately near a lower end of the barriers  26  and  28 . As a result, the airbag  10  is mostly separated into chambers  12 ,  14 , and  16  in the area  48  above the fold  46 , while it forms a nearly uniform cushion extending across all three chambers  12 ,  14 , and  16  in the area  49  below the fold  46  due to the large opening cross-section of the lower channels  20  and  24 . 
         [0023]      FIGS. 5   a  through  e  illustrate and exemplary sequence of inflation when a high deceleration triggers the gas generators  74 ,  76 , and  78  of airbag  10 .  FIG. 5  shows the incremental stages of inflation resulting in the situation previously discussed in connection with  FIG. 1 . In a normal, non-emergency, state as shown in  FIG. 5   a , the airbag  10  is rolled up or folded into an elongated bundle extending horizontally across the row of seats  50 . The gas generators  74  through  78  (not shown) connected to the ports  34 ,  36 , and  38  are fixedly attached to the bulkhead wall  60  in the aircraft at a height corresponding to an average seat occupant&#39;s chest or head height. When a deceleration of the aircraft exceeds a trigger threshold, the gas generators start to inflate the airbag  10 . As shown in  FIG. 5   b , the airbag  10  unfolds downward. As more gas flows into the airbag, the airbag expands. Due to the barriers  26  and  28 , the area  48  above the fold  46  exhibits a more limited expansion in the direction of the deceleration than the area  49  below the fold  46  as shown in  FIG. 5   c . Eventually, however, as shown in  FIG. 5   d , the area  48  above the fold  46  expands enough to push the airbag  10  toward the seat occupant  64  by abutting the bulkhead wall  60 , thereby causing a rotation r about the gas generators  74  through  78  holding the ports  34 ,  36 , and  38  fixed to the bulkhead wall  60 . By the time the head  66  of the seat occupant  64  approaches the bulkhead wall  60 , the lower portion  48  is suitably placed to contact the seat occupant&#39;s facial region to cushion the further movement of the head  66 . As the head  66  moves downward as shown in  FIG. 5   e , the airbag  10  moves down with the head  66 , finally resulting in the situation shown in  FIG. 1 . 
         [0024]    As is evident from the shown example, the airbag  10  can be designed as an individual airbag for one seat occupant  64 . Also, the tethers  40  can be omitted if area  48  and area  49  are sewn to each other at the attachment points, thus forming the fold  46 . As different aircraft designs provide for different space between the aircraft seat  50  and the bulkhead wall  60 , the design of the airbag  10  can be varied according to given dimensions without leaving the scope of the present invention. 
         [0025]    Notably, the drawings show only an illustrative embodiment of the airbag. While the depicted airbag first unfolds downward and moves upward during inflation, variations of this design include individual or connected airbags that inflate directly toward the seat occupant&#39;s head and upper torso. Appropriate adaptable vents can be provided to reduce a risk of injury to the seat occupants, 
         [0026]    The foregoing description of various embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Numerous modifications or variations are possible in light of the above teachings. The embodiments discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.