Abstract:
An inflatable side impact airbag for a vehicle occupant protection device comprises an upper edge to attach it in the area of an A-column and of a roof frame of a motor vehicle. The upper edge of the airbag is straight. Further, there is proposed a method of installing such an airbag.

Description:
TECHNICAL FIELD 
     The invention relates to an inflatable side impact airbag for a vehicle occupant protection means. 
     BACKGROUND OF THE INVENTION 
     Conventional side impact airbags (e.g. DE 296 16 904) comprise an upper edge to attach it in the area of an A-column and of a roof frame of a motor vehicle. The invention also relates to a method of installing such a side impact airbag in the area of the A-column and of the roof frame of the motor vehicle. The upper edge is attached in the area of the A-column and of the roof frame in a vehicle. In this arrangement, the airbag is designed such that the upper edge of its contour is adapted to the shape of the A-column. In the non-activated state of the protective device, the airbag is stowed folded along the roof frame and the A-column. However, such folding is relatively complicated to realize. It would be simpler to roll up the airbag all the way to its upper edge. However, due to the curvature of the upper edge, this is not possible without also rolling up a part of the edge. Since the airbag, however, has to be attached to the vehicle across the entire length of the edge, the edge must not be rolled up together with the airbag. 
     The object of the invention is to provide a side impact airbag that can be rolled up crease-free all the way to its upper edge and that can be attached with this edge in the area of the A-column and of the roof frame of a motor vehicle. 
     BRIEF SUMMARY OF THE INVENTION 
     According to the invention, an inflatable side impact airbag for a vehicle occupant protection device comprises an upper edge to attach it in the area of an A-column and of a roof frame of a motor vehicle. The upper edge of the airbag is straight. The airbag proposed can be rolled up straight and without creasing all the way to its upper edge, resulting in an elongated tube. On installation, this tube can be curved without any problem in such a way that it adapts to the curvatures of the A-column and of the roof frame. Nevertheless, the side impact airbag can easily be unrolled by means of inflation so that it covers, for example, the side windows in the area between the A-column and the C-column. 
     According to another aspect, the invention also provides a method of installing a side impact airbag according to the invention in the area of the A-column and of the roof frame of the motor vehicle. Through the method, the side impact airbag is rolled up towards the upper edge to form a roll which has an axis that is parallel to the upper edge. The roll is adapted to the curvature of the A-column and of the roof frame, and the upper edge of the roll is attached to the A-column and to the roof frame. Since the airbag is not folded but rather only rolled up and can be easily adapted to the curvatures of the A-column and of the roof frame, installation is much faster and easier to carry out. 
     Additional advantageous embodiments of the invention will be apparent from the subordinate claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a view of the side impact airbag according to the invention in a state spread out flat; 
     FIG. 2 is a view of the side impact airbag of FIG. 1 in a rolled-up state; 
     FIG. 3 shows a cross-section through the airbag of FIG. 2 along the line III—III in FIG. 2; 
     FIG. 4 is a perspective view of a motor vehicle with a side impact airbag according to the invention in the rolled-up state; 
     FIG. 5 is a perspective view of the vehicle from FIG. 4 with the side impact airbag according to the invention in the inflated state; and 
     FIG. 6 is a view of the side impact airbag of FIG. 4 in the unrolled state. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows a side impact airbag  10  that is spread out flat and that covers a surface area that essentially has the shape of a pentagon which was made of a rectangle with one corner cut off. The side impact airbag  10  has an upper edge  12 , a lower edge  14 , a front end  16  (in the Figures on the left) and a back end  18 . The side impact airbag  10  can be made, for example, of a double-layered piece of fabric and can be provided with stitched seams  20  and non-inflatable areas  22  as shown in FIG. 1, as is well known to the person skilled in the art. The upper edge  12  runs in a straight line, whereas the lower edge  14  runs from the back end  18  to about the front third  19  of the side impact airbag  10  essentially parallel towards the upper edge  12 , and in the front third  19  in an arc towards the upper edge  12 , so that, at the front end  16 , the upper edge  12  and the lower edge  14  meet at an acute angle. At the upper edge  12 , attachment tabs  24  are formed which are provided with holes and which serve to attach the side impact airbag  10  in a motor vehicle. At the back end  18 , there is an inflow opening  26  through which the side impact airbag  10  can be filled with gas from a source of pressurized gas. A further attachment hole  28  is situated at the front end  16  in the gusset between the upper edge  12  and the lower edge  14 . 
     The side impact airbag  10  is part of a vehicle occupant protective means that is installed in a vehicle  32  (FIGS.  4  and  5 ). In order to install the side impact airbag  10 , it can be rolled up from the lower edge  14  in a simple manner parallel towards the upper edge  12 , straight and without creasing, so that a uniform roll is formed whose axis is parallel towards the upper edge  12 , as can be seen clearly in FIGS. 2 and 3. The rolled-up airbag  10 , as shown in FIG. 4, can be attached by means of the attachment tabs  24  and the attachment hole  28  to the roof frame  30 , and in the front third  19  to the A-column  34  of the vehicle  32 . In so doing, the rolled-up side impact airbag  10 , due to its flexibility, adapts like a tube to the curvature of the roof frame, especially in the area of the A-column  34  and at the transition to the C-column  36 . The side impact airbag is mounted in such a way that its front end  16  lies at the front, as seen in the driving direction, and is attached through the attachment hole  28  to the lower end of the A-column. 
     When the vehicle occupant protective means is actuated, the side impact airbag  10  is inflated by gas from a gas generator  38 , thereby unrolling downwards over the side windows  40  and  42  of the vehicle. In the unrolled and inflated state, the upper edge  12  of the side impact airbag  10  follows the curvature of the roof frame  30  from the A-column  34  to the C-column  36  (FIGS.  5  and  6 ). Characteristically, through the curvature of the upper edge  12  in the front third of the side impact airbag  10 , a slack region  44  is formed at the lower edge  14 , but this does not impair the function of the side impact airbag  10 . 
     As can be clearly seen in FIGS. 5 and 6, the side impact airbag  10  advantageously covers the entire area of the side window  40  up to the A-column  34 , so that it can also fulfill its protective effect for a vehicle occupant who is, for example, leaning forward. Nevertheless, the side impact airbag  10  does not have to be folded in a complicated manner, but rather can advantageously be simply rolled up. This advantageous possibility of rolling up arises merely from the fact that the upper edge  12  runs in a straight line when the airbag is spread out flat. If the upper edge of the airbag were cut to fit the contour of the roof frame  30 , then the attachment hole  28  and the attachment tabs  24  would be rolled up as well in the area of the A-column  34 , which, however, would make it impossible to unfold the side impact airbag  10  in the front area. 
     Aside from the fact that it is simpler to do, rolling the side impact airbag  10  has the additional advantage over folding that the side impact airbag  10  unrolls along the side windows  40  and  42  when it is being inflated and cannot, for example, due to unfavorable flow conditions or stuck folds, move into the passenger compartment. 
     Advantageously, the side impact airbag  10  is rolled up in such a way that the side of the airbag facing the vehicle interior when the airbag is in the installed and inflated state forms the outside of the roll. This has the advantage that a whiplash effect is avoided during inflation when the roll expands into the interior of the vehicle. Rather, the roll slides downward along the side windows  40  and  42  when it unrolls, so that the head of a vehicle occupant, even if he/she is not seated in the optimal sitting position, cannot end up between the side impact airbag  10  and the side window  40 ,  42 . 
     In order to better stabilize the side impact airbag  10  in the inflated state, the airbag in the area of the C-column  36  can also be attached to the C-column by a tether  46  fastened to the back end  18 .