The invention concerns a packaging method for an airbag, an airbag and a device for folding or rolling an airbag with the features of the preambles of one of the claims 1, 5 or 8.

Airbags are used in vehicles to cover the interior side sur ^¬ face in a vehicle in case of an accident to prevent severe in ^¬ juries of the occupant. The airbag is mounted above the side windows at a rim of the vehicle structure under the roof- lining. As the installation space for the airbag is very limited especially in small cars, the airbag is rolled or folded to a long thin tube-shaped package.

For pedestrian protection, airbags are further located at the lower edge of the windshield, which in the event of an acci ^¬ dent deploy on the windshield and in the inflated state cover the windshield as well as the pillars of the motor vehicle to ^¬ wards the outside.

One possible embodiment of an airbag, in this case a curtain airbag, and a device for folding or rolling an airbag is known from the WO 2009/083056 Al . The airbag is rolled from a flat structure to a thin tube in a device comprising several de ^¬ flection pulleys and a traction mechanism. The traction mechanism consists of several belts arranged in distances on a ba ^¬ sis, wherein the arrangement and the number of the belts de ^¬ pend on the individual shape and dimension of the airbag. The tightness of the airbag in the tube shape depends on the trac- tion mechanism and especially on the design and arrangement of the deflection pulleys.

The object of the invention is to provide an improved packa ^¬ ging method to roll or fold the airbag to a thin tight tube, to provide an airbag which is rolled or folded to a thin tube with a higher tightness and an improved device for folding or rolling an airbag to a thin tight tube.

According to claim 1 a packaging method is suggested, in which the airbag is stretched during the rolling or folding process in length direction. The advantage of the suggested solution is that any folds in length direction are pulled out of the airbag during the rolling or folding process, so that the air- bag can be rolled or folded to a thin tube having a greater tightness .

The folds can be pulled out very efficiently, when the airbag is stretched in an angle, preferably perpendicular, to the folding direction, or when the airbag is stretched in a direc ^¬ tion essentially parallel to the rolling axis.

Furthermore, it is suggested that the airbag is stretched be ^¬ tween two end sections defining a stretch-line, and the airbag comprises several attachment points for a fixation of the air- bag at a vehicle structure, and the stretch-line is arranged in the opposite half of the airbag with respect to the attach ^¬ ment points. The stretch-line defines the centre from where the folding or rolling of the airbag starts. Because the stretch-line is arranged in the opposite half, the rolling or folding process of the airbag starts first with the opposite half of the airbag, so that the attachment points are not folded or rolled into the airbag and are therefore afterwards freely accessible.

Furthermore, an airbag is suggested which is rolled or folded to a thin tube according to one of the suggested packaging methods, wherein the airbag comprises two end sections between which the airbag is stretched. The advantage of the proposed airbag is that the connecting line between the end sections defines a stretch-line for a controlled rolling or folding process. Depending on the geometry of the airbag, the end sec ^¬ tions may be arranged in such a way that any folds are pulled out to a maximum over the length extension of the airbag. A very efficient rolling or folding process can be provided when the end sections are arranged in such a way that the distance between the end sections is as big as possible.

Furthermore, it is suggested that the end sections are located in side areas of the airbag, wherein at least one of the side areas protrudes sidewise from the airbag. The advantage of the suggested embodiment is that the end section which is arranged in the protruding side area is not folded or rolled between the layers of the folded or rolled airbag, so that the end section is freely accessible after the rolling or folding process. Furthermore, the airbag is stretched along the total or a maximum length, so that any folds in not stretched areas are avoided or at least reduced to a minimum.

The end sections are provided in another preferred embodiment with attachment sections, by which the stretching forces can be easily applied to the airbag. The attachment sections may be designed for example as cut-out holes. One important aspect for designing the attachment sections is that they comprise the necessary strength to transmit the force applied to the airbag during the folding or rolling process. Furthermore, a device for folding or rolling an airbag to a thin tight tube according to one of the suggested packaging methods is suggested, wherein the device comprises a stretch ^¬ ing unit consisting of at least two lateral displaceable fixa ^¬ tion devices between which the airbag is attachable at two op ^¬ posing end sections. The advantage of the suggested device is that the device can be used to roll or fold airbags having different lengths. Furthermore, it is possible to install the airbag in a first step in the device and apply the stretching forces in a second step by displacing the fixation devices.

Moreover, it is suggested that the fixation devices are pro ^¬ vided with pivotable mounted fixation elements. The pivotable fixation elements enable a stretching of the airbag with not rotating fixation devices without twisting the end sections of the airbag during the rolling or folding process.

Furthermore, it is suggested that the fixation elements are pivotable with respect to one common rotation axis. The common rotation axis enables a rolling or folding process with a clearly defined orientation with a minimum amount of folds and therefore a rolling or folding of the airbag as tight as pos ^¬ sible .

Furthermore, it is suggested that the device comprises at least two rolling or folding units which are laterally dis ^¬ placeable. The arrangement of the rolling or folding units can be therefore adjusted to the individual design of the airbag like total length, or rolling or folding length, so that the airbag can be rolled or folded as equal as possible along the total length. Additionally, the rolling or folding units can be arranged with respect to cut-outs like for example for dif- ferent pillars of the vehicle.

Another preferred embodiment of the invention can be seen in that the rolling or folding units having a common driving unit. The use of one common driving unit facilitates the de ^¬ sign of the device itself and the controlling of the rolling or folding units.

A very simple design of the rolling or folding units can be realised, when the rolling or folding units consist of at least three deflection pulleys and an endless traction ele ^¬ ment, which is looped around the deflection pulleys, wherein the airbag is inserted into a loop of the traction element be ^¬ tween two deflection pulleys. The suggested design of the rolling or folding units is so far advantageous since the de ^¬ sign is independent of the airbag itself. The rolling or fol ^¬ ding process is performed with an endless traction element, which comprises a loop between two deflection pulleys in which the airbag is inserted during the rolling or folding process. Therefore, the possible rolling or folding length of the air- bag is not limited to a special length, and there is no need to change the design, if an airbag with a bigger length needs to be rolled or folded with the device. The movement of the traction element is transmitted to the abutting airbag which is inserted into the loop, while the movement of the traction element in the section of the loop supports the rolling or folding process of the airbag to the thin tight tube.

Furthermore, at least one pulley is mounted on a pivotable arm which performs a pivoting movement to tension the traction element. The tensioning of the traction element is performed after the airbag is inserted into the loop, so that a certain slack in the traction element, which is needed to create the loop, is pulled out after the insertion of the airbag by ten ^¬ sioning the traction element. Because the loop defines the cross shape of the rolled or folded tube shaped airbag, it is possible to roll or fold the airbag by tensioning the traction element to a tighter tubular shape.

Furthermore, at least one of the pulleys is driven rotation- ally. The rotational movement of the pulley is transmitted to the traction element, which pulls finally the abutting airbag into the loop.

Furthermore, at least one pulley is mounted on a pivotable arm, wherein the arm performs a pivoting movement to close the loop, in which the airbag is inserted. By closing the loop the airbag is rolled or folded with a greater tightness in the closed loop, without the risk of being widened up during the rolling or folding process. Furthermore, it is avoided that the airbag which is pulled into the loop escapes out of the loop .

In the following the invention is described more detailed with respect to one preferred embodiment. The figures show in de ^¬ tail :

Fig.l: Airbag with a stretch-line;

Fig.2: Device for rolling or folding an airbag;

Fig.3 : Rolling or folding unit;

Fig.4: Airbag rolled to a tube in a closed loop of the

traction element. In figure 1 it is shown an inflatable airbag 1 before the rolling or folding process. The rolling or folding process might consist of a pure rolling or folding process or also of a combination of a rolling and folding process. In the following the process is entitled rolling process, but it is not limited to a pure rolling process. In the sense of the inven ^¬ tion, airbags are meant to be in particular large-surface air- bags, like for example curtain airbags or pedestrian protec ^¬ tion airbags, which have a relatively long length.

The airbag 1 comprises several attachment points 2 at the up ^¬ per edge defining the final attachment line at the vehicle structure. In the lower half opposite to the attachment points 2 are provided two end sections 5 and 6, each of which com ^¬ prises an attachment section in the form of a cut-out hole. The end section 6 protrudes sidewise from the airbag 1, so that the distance between the end section 5 and 6 complies ap ^¬ proximately with the maximum length of the airbag 1. Further ^¬ more, there are two stretching units in the form of fixation devices 3 and 8 visible, which comprise fixation elements in the form of hooks 4 and 7 engaging into the cut-out holes in the end sections 5 and 6. The hooks 4 and 7 are mounted pivo ^¬ tably at the fixation devices 3 and 8.

The fixation devices 3 and 8 are exerting during the rolling process a stretching force S, so that the airbag 1 is

stretched in length direction along a stretch-line 9, which is identical with the connection-line between the end sections 5 and 6. Since the hooks 4 and 7 are mounted pivotably at the fixation devices 3 and 8, it is possible to roll or fold the airbag 1 with non rotating fixation devices 3 and 8. Because the stretch-line 9 is not identical with the lower edge of the airbag 1, there is also a section la of the airbag 1 in the form of a thin tab below the stretch-line 9.

In figure 2 it is shown a cut-out of a device for rolling the airbag 1, here shown as a tight rolled tube 29 after the roll ^¬ ing process. The fixation device 3 is attached at a displace- able flange 10, which is arranged on a basis 11 of the device. The flange 10 is displaced to adjust the device for rolling an airbag 1 having a predetermined length or it can be also dis ^¬ placed after the airbag 1 is fixed via the end section 5 and the engaging hook 4 to stretch the airbag 1 along the stretch- line 9 before the rolling process starts. The fixation device 3 can be also provided with a driving unit like an electric motor for driving the hook 4 rotationally during the rolling process of the airbag 1. Furthermore, the device comprises several rolling units 12 and 13, which are displaceable in di ^¬ rections E and F with respect to the basis 11.

In figure 3 it is shown one rolling unit 12 in side view. The rolling unit 12 comprises three deflection pulleys 23,24 and 25 and a traction element 26 in the form of a belt, which is looped around the deflection pulleys 23,24 and 25. The trac ^¬ tion element 26 comprises in the section between the deflec ^¬ tion pulley 24 and the deflection pulley 25 a loop 28 in which the airbag 1 is inserted with the stretch-line 9. When the airbag 1 is inserted with the stretch-line 9 into the loop 28, the section la is folded backwards onto the part of the airbag 1 above the stretch-line 9 in figure 1. The stretch-line 9 separates the section la from the rest of the airbag 1.

The deflection pulleys 23,24 and 25 are mounted on arms 20,21 and 22, which comprise bushes 17,18 and 19 at their ends. The bushes 17,18 and 19 are designed with openings having a po ^¬ lygonal profile. The device further comprises three parallel bars 14,15 and 16, from which the bar 14 is also visible in figure 2. The bars 14,15 and 16 are provided with a profile in cross-section which is identical to the polygonal profile of the openings in the bushes 17,18 and 19. The bars 14,15 and 16 are driven individually by a driving unit 27, wherein each bar 14,15,16 is connected via one bush 17,18 or 19 and one arm 20,21 or 22 with one deflection pulley 23,24 and 25 of one function in the rolling units 12 and 13. The bars 14,15 and 16 are arranged in parallel, so that the rolling units 12 and 13 are displaceable with respect to the basis 11 and the deflec ^¬ tion pulleys 23,24 and 25 can be driven independently of the rolling units 12 and 13.

After the airbag 1 is inserted with the stretch-line 9 into the loop 28, the deflection pulley 24 is driven via the pivo- table arm 21 which performs a pivoting movement in arrow di ^¬ rection "B" and the loop 28 is closed by moving the deflection pulley 24 towards the deflection pulley 25 in arrow direction "C" until the airbag 1 is clamped between the deflection pul ^¬ leys 24 and 25 with the traction element 26 arranged in be ^¬ tween. At the same time or with a short time delay, the de ^¬ flection pulley 23 performs a pivoting movement in arrow di ^¬ rection "A" to tension the traction element 26 and to minimise the dimension of the loop 28.

When the loop 28 is closed and the traction element 26 is ten- sioned, as shown in figure 4, the deflection pulley 25 is driven to a rotational movement in direction of arrow "D" and pulls therefore the airbag 1 into the loop 28. As the traction element 26 performs in the section of the loop 28 a movement defined by the shape of the loop 28 itself, the airbag 1 is rolled in the loop 28 to a tight tube 29. The rotational move ^¬ ment for winding the airbag 1 might be supported by a rota- tional drive of the hooks 4 and 7