Abstract:
An airbag arrangement for protecting at least one seat occupant in an aircraft of the type having a tandem seat arrangement with a rear seat for a seat occupant and a front seat in front of the rear seat. The front seat has an airbag subassembly mounted in the seat back. The airbag subassembly has an airbag inflating between the seat back and the rear seat and uses a gas generator connected to the airbag and configured to inflate the airbag. The airbag is secured to the seat back under a cover with a tear seam and has a compacted state in which the airbag is rolled up or folded about a horizontal axis inside the seat back.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to an airbag arrangement for the protection of seat occupants in a vehicle with seats arranged in tandem, so that at least one seat is located behind another. 
       BACKGROUND OF THE INVENTION 
       [0002]    Airbags have been credited for saving lives by damping the impact of a vehicle crash on a vehicle occupant. Not only frontal impact airbags are in use, but also side impact airbags, such as side curtain airbags expanding from the roof line of a vehicle or airbags arranged in seats, a center console, or an armrest between two car seats. After the gas generator is triggered, the airbag unfolds and provides energy absorption 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 passenger or motor 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 excursion 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, where a forward movement may result in high head accelerations and possibly head injuries from a seat back of a seat located in front of the seat occupant. 
       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 the event of a high longitudinal deceleration. 
         [0006]    According to the present invention, this object is achieved in tandem arrangements with a front seat and a rear seat for a seat occupant of the rear seat by an airbag arrangement on a rear surface of a seat back of the front seat. The front seat of the tandem arrangement may be the rear seat of a different tandem arrangement. The airbag inflates in front of the seat occupant in a direction configured to make a contact with the seat occupant&#39;s head or chest before the seat occupant contacts the seat back of the front seat during an impact sequence. 
         [0007]    In a normal, deflated state, the airbag is stowed in a rolled or folded bundle at a location in the seat back of the front seat. Upon activation of a pyrotechnical gas generator or compressed gas source, the airbag emerges from the seat back through a horizontal tear seam and unfolds in front of the seat occupant. A preferred location on a typical aircraft seat back is below the hinge of a fold-up table and above a seat pocket of the front seat of the tandem arrangement. When the seat occupant&#39;s head and torso, due to inertia, approach the seat back of the front seat, the first contact is made with the airbag by the face or the chest 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 avoids contact with any hard surface, or the severity of such impact can be reduced. The airbag also controls acceleration of the occupant in an effort to reduce related forces to a level below the limits of human tolerance. 
         [0008]    The airbag has an inherent shape that expands it upward toward the head of the seat occupant. 
         [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 first embodiment of an aircraft seating space with an inflated airbag and a seat occupant after a frontal impact; 
           [0012]      FIG. 2  shows a second embodiment of an aircraft seating space with an inflated airbag and a seat occupant after a frontal impact; 
           [0013]      FIG. 3  shows a cross-sectional view of the airbag of  FIG. 1  before deployment; 
           [0014]      FIG. 4  shows the cross-sectional view of  FIG. 3  after deployment of the airbag; 
           [0015]      FIG. 5  shows a first view of an airbag subassembly configured for the seating space of  FIG. 1 ; 
           [0016]      FIG. 6  shows a second view of the airbag subassembly of  FIG. 5 ; 
           [0017]      FIG. 7  shows a third view of the airbag subassembly of  FIG. 5 ; 
           [0018]      FIG. 8  shows a seat back with an enclosed airbag according to  FIG. 1 ; and 
           [0019]      FIG. 9  shows a top view through an opened tear seam onto an airbag mounted in a seat back according to  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]      FIG. 1  shows a first aircraft seat  50  located behind a second aircraft seat  52 . 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 relative to the aircraft 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. 
         [0021]    The seat back  60  of the front seat  52  includes an airbag  10  that is inflated toward the seat occupant  64  during a deceleration event before the head  66  has engaged the seat back  60 . Accordingly, the head  66  contacts the inflated airbag  10  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 a situation with a bare seat back  60 . In the embodiment of  FIG. 1 , the airbag  10  is mounted in the lower half of the seat back  60  and expands upward to a height that at least partially covers a head rest portion  54  of the seat back  60 . 
         [0022]    In a second embodiment according to  FIG. 2 , an airbag  110  is mounted in an upper portion of the seat back  60 , in or near the headrest portion  54 . The airbag  110  of  FIG. 2  is smaller than the airbag  10  of  FIG. 1  because it inflates only at a height that corresponds to the head  66  and the upper torso  68  of the seat occupant  64 . 
         [0023]      FIGS. 3   a  and  3   b  illustrate an example of a physical arrangement of the airbag  10  of  FIG. 1  or of a similar device in the seat  52 .  FIG. 3   b  represents an enlarged detail view of a portion of  FIG. 3   a . The seat back  60  has a rear-facing, generally vertical surface  70  covered with a seat cover  14 . A foldable tray table  56  is arranged adjacent to the surface  70 . In the shown position, the tray table  56  is folded up and extends generally parallel to the surface  70 . Below the tray table  56 , a seat pocket  58  extends generally along the surface  70 . Between the tray table  56  and the seat pocket  58 , the seat cover  14  has a horizontal tear seam  16 . An airbag subassembly  30  is mounted in the seat back  60  and hidden behind the seat cover  14  proximate the tear seam  16   
         [0024]    The airbag subassembly  30  comprises the airbag  10 , an airbag wrapper  12 , a mounting bracket  18 , and a gas generator  20 . While a pyrotechnical gas generator is depicted in the drawings, the term gas generator is intended to include any device suitable for inflating the airbag. The airbag  10  is in a compacted state, in which it is rolled up about a horizontal axis Y (see  FIG. 6 ). In the embodiment shown, the airbag  10  is rolled in an orientation that points upward on the side facing the seat occupant  64  and downward on the opposite side. It may also be folded along fold lines extending parallel to the horizontal axis Y. The gas generator  20  has a substantially cylindrical shape with the cylindrical axis extending generally parallel to the horizontal axis Y. The wrapper  12  surrounds both the gas generator  20  and the rolled up airbag  10 . Proximate the height of the tear seam  16 , the wrapper  12  has a perforation  22  or a tear seam, configured to tear open upon inflation of the airbag  10 . 
         [0025]    The mounting bracket  18  has a profile shaped like an inverted L in the shown vertical cross-section. It flanks the top of the gas generator  20  and the side of the gas generator remote from the seat occupant  64 . A subassembly fastener  24  secures the gas generator  20  along with the wrapper  12  and the airbag  10  to the mounting bracket  18 . In the shown embodiment, two of threaded bolts extend from the gas generator  20  and are fastened with corresponding threaded nuts. 
         [0026]    If the gas generator  20  is triggered and inflates the airbag  10 , the resulting force exerted by the airbag  10  on the wrapper  12  and on the seat cover  14  tears the perforation  22  of the wrapper  12  and the tear seam  16  of the seat cover  14  as shown in  FIG. 4 . During the inflation, the airbag  10  unrolls to extend toward the seat occupant  64  and upward. 
         [0027]    In one embodiment, the airbag  10  may have an inherent shape that causes it to extend upward along the surface  70  rather than toward the seat occupant  64 . The airbag  10  is assembled from a top panel  26  and a bottom panel  28 . The top panel  26  and the bottom panel  28  are named after their position in the area where the airbag  10  exits the seat back  60 . The top panel  26  may, for example be a planar piece of airbag fabric, while the bottom panel  28  may be made from a piece of airbag fabric that is larger than the top panel  26 , at least in the direction perpendicular to the axis Y. In order to fit the edges of the bottom panel  28  with the edges of the top panel along a connecting seam  32 , the bottom panel may have folds  34  or darts reducing the length of the edge of the bottom panel  28 . Due to the greater length of the bottom panel, the airbag inflates into a bent cross-section as illustrated in  FIG. 4 . 
         [0028]      FIGS. 5 ,  6 , and  7  show the airbag subassembly  30  in greater detail from different perspectives and will be described by the following in a synopsis. In each of the  FIGS. 5 ,  6 , and  7 , a stick figure indicates the position of the seat occupant  64  relative to the airbag assembly after installation in the seat back  60 . 
         [0029]    The rolled airbag  10  and the gas generator  20  are wrapped into the wrapper  12  that extends around at least a portion of the width of airbag  10 . The airbag  10 , the wrapper  12 , and the gas generator  20  form the subassembly  30  that is preassembled before installation in the seat back  60 . In  FIG. 6 , the perforation  22  is visible that weakens the wrapper along a horizontal tear line that generally extends at the same height as the tear seam  16  in the seat cover  14 . 
         [0030]    The L-shaped profile shown in  FIGS. 3 and 4  is formed by a rail  36  extending in the horizontal direction in a vertical plane. Three tabs  38 ,  40 , and  42  extend from the rail  36 . Tab  40  extends centrally from the top of rail  36  in a horizontal direction toward the seat occupant  64 . Two fastening bolts extending from the gas generator and two threaded nuts form the subassembly fasteners  24  that attach the gas generator  20 , the wrapper  12 , and the airbag  10  to the tab  40 . Tabs  38  and  42  extend from the sides of rail  36  at a right angle toward the seat occupant  64  and form flanges for fastening the subassembly  30  to a seat frame  72  (shown in  FIG. 8 ). One of the tabs  38  and  42  has a slot for easier placement inside the seat back  60 . 
         [0031]      FIG. 8  illustrates a view onto the surface  70  of the seat back  60 . Broken lines indicate elements hidden behind the seat cover  14 . The tray table  56  has two hinge arms  74  on laterally opposite sides. The hinge arms  74  are hingeably secured with frame fasteners  76  ( FIG. 9 ) to two vertical struts of the seat frame  72 . 
         [0032]    The seat pocket  58  is arranged below the tray table  56 . Between the tray table  56  and the seat pocket  58  extends a gap where the seat cover  14  is visible. the tear seam  16  extends laterally across the gap. Behind the tear seam  16 , the airbag subassembly  30  is mounted inside the seat back  60  in a position where the perforation  22  of the wrapper extends in close vicinity of the tear seam  16 . The rail  36  of the mounting bracket  18  connects the two vertical struts of the seat frame  72 . The tabs  38  and  42  are secured to the seat frame  72  with the same frame fasteners  76  that secure the hinge arms  74 . The frame fasteners  76  may be threaded bolts and nuts or other suitable fasteners. 
         [0033]      FIG. 9  shows a top view onto the airbag subassembly  30  after opening the tear seam. Visible are the subassembly  30 , and the frame fasteners  76 . The wrapper  12  extends beyond the tab  40 . The gas generator  20  and the airbag  10  emerge sideways from the wrapper  12 . The subassembly fasteners  24  at the top of the subassembly  30  attach the gas generator  20  to the tab  40  of the mounting bracket  18 . Tab  38  of the mounting bracket  18  is secured to the vertical strut of seat frame  72  with frame fastener  76 . On the other side of the strut, opposite the tab  38 , one of the hinge arms  74  (not visible) of the tray table  56  is also secured with the same frame fastener  76 . 
         [0034]    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.