The invention relates to a curtain airbag for a vehicle com ^¬ prising the features of the preamble of claim 1.

The curtain airbag is located in the vehicle at the upper edge of the inner side structure of the vehicle and, in the event of an accident, is inflated in such a way that in the inflated state it covers the inner side structure of the vehicle and thereby prevents the occupant from directly hitting the same and sustaining severe injuries or being thrown out of an open window .

For the protection of the occupant, an airbag, which is de ^¬ signed as most often a round bag and in the inflated state co ^¬ vers the steering wheel, is further provided in the steering wheel of the vehicle as well. As the steering wheel naturally is arranged to perform a rotational movement, with a steering wheel hub not being fixed the airbag as well performs this ro ^¬ tational movement, so that the airbag itself needs to be de ^¬ signed to be symmetric and in particular to be round, in order that it can fulfill its protective function independent of the position of the steering wheel.

Thus, in the event of an accident, during the occurring for ^¬ ward movement the occupant generally is protected by the side curtain airbag and the airbag in the steering wheel.

In tests it has turned out that in the event of a frontal im ^¬ pact with a small overlap only, for example of 10-25 % of the front end of the vehicle, or a corner or angled impact, the A- pillar already at low impelling forces is dislocated very far into the passenger compartment. Furthermore, the dashboard of the vehicle is dislocated from its side edge obliquely to the center and the lower part of the A-pillar is intruding into the compartment of the vehicle, so that an enlarged gap be ^¬ tween the side edge of the dashboard and the inner side struc ^¬ ture of the vehicle is generated. Owing to the impact direc ^¬ tion the occupant further is accelerated directly in the di ^¬ rection of the gap existent between the curtain airbag and the airbag of the steering wheel, so that owing to the non ^¬ existent connection of the airbags the occupant may hit the A- pillar moving in or from above may hit the side door frame through the airbags, or the occupant slides of the frontal airbag into the gap.

For the above-mentioned reasons, an enhanced risk of injury for the occupant even results from accidents with low impel ^¬ ling forces and a small lateral overlap.

It is the object of the invention to provide a curtain airbag, with which the risk of injury for the occupant which is enhanced due to the above-mentioned reasons can be reduced.

For the solution of the object it is proposed that the curtain airbag comprises an additional chamber which, in the mounting position, is located on the in driving direction of the vehicle front portion of the main chamber, and deploys in the di ^¬ rection of the interior of the vehicle when the curtain airbag is inflated, wherein a extended section is provided which con ^¬ nects the additional chamber and the main chamber at a rim section at the same side and which limits the movement of the additional chamber during the inflation process. Thus, the ad ^¬ vantage of the curtain airbag improved according to the inven- tion is that the curtain airbag is inflated together with the additional chamber to form a curved structure, in which the occupant is caught during the forward displacement, so that he cannot pass through the gap between the curtain airbag and the airbag in the steering wheel. The additional chamber deploying into the interior of the vehicle owing to its direction of de ^¬ ployment covers the A-pillar and the front section of the up ^¬ per door frame, so that the surface of the interior of the ve ^¬ hicle as a whole is covered by the curved curtain airbag even in an area, the occupant would be very likely to hit during the obliquely directed forward displacement, whereby the risk of severe injuries in the event of accidents with a small overlap can be reduced significantly. The term "deploys in the direction of the interior of the vehicle" means, that the ad ^¬ ditional chamber is extending from the plane inner side struc ^¬ ture of the vehicle into the interior of the compartment, which results finally to an L-shaped design of the curtain airbag. The extended section is dimensioned and arranged in a position at the rim of the additional chamber in that way that the additional chamber moves automatically towards the inte ^¬ rior of the vehicle. An important feature of the design is that the extended section connects the additional chamber and the main chamber at the same side, so either at the upper or at the lower rim of the additional and the main chamber, so that the extended section does not cross the main chamber and the additional chamber. Furthermore a very effective shape of the main chamber and the additional chamber for the restraint function can be provided when the additional chamber and the opposing section of the main chamber are forming a shape like a catching baseball glove without crossing tethers, in which the occupant may dive. The advantage is that the occupant may not displace the additional chamber to the side when moving with high velocity in the direction of the additional chamber. The occupant is catched in the cavity between the main chamber and the additional chamber, where he is protected in front di ^¬ rection and side direction as well from hitting onto the vehicle structure.

The extended section is designed preferably as a strap ar ^¬ ranged at the side rim of the additional chamber. The advan ^¬ tage of the proposed embodiment is that the extended strap in ^¬ fluences the inflation characteristic of the additional cham ^¬ ber in a very easy manner. As the extended section is arranged at the side rim without changing the protecting surface of the airbag there is no disadvantage regarding the restraint func ^¬ tion and the occupant may not collide for example with cross ^¬ ing tether straps, which are usually used when the inflation geometry should be changed. Furthermore it is possible to con ^¬ trol or influence the inflation characteristic by extending the extended section in the maximum case over its full length of the additional chamber.

In the following, the invention is described on the basis of preferred embodiments with reference to the accompanying fi ^¬ gures. The figures show in detail:

Fig. 1: Top view of vehicle interior with occupant and curtain airbag;

Fig. 2: Curtain airbag with an additional chamber separated by a vertical running separation line in an unfolded status ;

Fig. 3: Curtain airbag with an additional chamber separated by a vertical running separation line in a folded status ;

Fig. 4: Curtain airbag with an additional chamber and a triangular extended section in an unfolded status;

Fig. 5: Curtain airbag with an additional chamber and an extended section with a sidewise extending tongue in an unfolded status;

Fig. 6: Curtain airbag with an additional chamber and an extended section with a sidewise extending tongue in a folded status;

Fig. 7: Curtain airbag with an extended section arranged at the additional chamber before the folding process;

Fig. 8: Curtain airbag from Fig. 7 after folding the additional chamber onto the main chamber;

Fig. 9: Curtain airbag from Fig. 8 in view to cross section

A-A in the inflated status;

Fig. 10: Curtain airbag with a V-shaped extended section arranged along the rim sides of the main chamber and of the additional chamber;

Fig. 11: Curtain airbag from Fig.10 after folding the additional chamber onto the main chamber;

Fig. 12: Curtain airbag from Fig.11 in view to cross section

B-B in the inflated status. Fig. 1 shows a curtain airbag 100 in the inflated state in the interior 1 of the vehicle which is currently being decelerated by an object 6 intruding frontally with a small overlap. An A- pillar 17 is pushed into the interior 1 of the vehicle and a dashboard 4 is displaced from its edge in the direction of the center of the interior 1 by the intruding object 6. Due to the dashboard 4 being displaced obliquely inwards a gap 20 is gen ^¬ erated between the edge of the dashboard 4 and the inner side structure 10 of the vehicle. Furthermore, an occupant 7 sit ^¬ ting in a vehicle seat 19 can be seen, which owing to the suddenly acting vehicle deceleration performs a forward movement in the direction of the gap 20 or the A-pillar 17, which is located beneath a steering wheel 5 and an airbag in the steering wheel 5. As the additional chamber 11 of the curtain air- bag 100 according to the invention is located on the main chamber 3 in such a way that it deploys in the direction of the interior 1 of the vehicle, the curtain airbag 100 with the additional chamber 11 covers the gap 20 and/or the intruding A-pillar 17 and/or the upper edge of the door frame, so that the occupant 7 cannot hit one of these parts in a non ^¬ protected manner or intrude into the gap 20. In fact, a catch ^¬ ing structure, which laterally as well as frontally protects the occupant 7 and in particular the head 8 of the occupant 7, is provided by the additional chamber 11 and the main chamber 3 in this area. Provided that the occupant 7 is wearing a safety belt 9, the obliquely directed forward movement already results from the safety belt 9 engaging asymmetrically over a shoulder of the occupant 7 and/or from the angled direction of the impact, which results in diagonal acceleration forces act ^¬ ing on the occupant 7. The additional chamber 11 is connected to the main chamber 3 via a triangular extended section 12, also called "sail", which limits the movement of the addi ^¬ tional chamber 11 to the interior 1 of the vehicle. The move- ment without the sail is shown as a dashed line B. As the ad ^¬ ditional chamber 11 is hold by the sail in that position the driver airbag may not push the additional chamber 11 to the out- or front side when inflated. The additional chamber 11 and the driver airbag are inflated therefore face to face cre ^¬ ating a stiff structure to restrain the occupant 7.

Fig. 2 shows a curtain airbag 100 designed according to the invention comprising a main chamber 3 and an additional chamber 11 which, in the mounting position, is located on the in driving direction front portion of the main chamber 3. The additional chamber 11 is separated from the main chamber 3 by a separation line 13 and is flow-connected to the main chamber 3 via a flow channel 25, so that the additional chamber 11 is automatically inflated, when the main chamber 3 is inflated. The separation line 13 runs as a loop 13d with an enlarged ex ^¬ tended section acting as a hinge during the inflation.

Furthermore, at the lower rim of the additional chamber 11, an extended section 12, also called dead fabric, is provided. The extended section 12 extends with a tongue 15 towards the main chamber 3. The extended section 12 is connected before folding the additional chamber 11 onto the main chamber 3 with the tongue at a lower preferably also extended section of the main chamber 3 to pull the additional chamber 11 towards the main chamber 3. The tongue 15 is dimensioned shorter than the dis ^¬ tance to the extended section of the main chamber 3 to pull the additional chamber 11 towards the main chamber 3 when the tongue is connected.

The extended section 12 may be also designed as an extra strap which is sewn onto the rim sections of the additional chamber 11 and the main chamber 3. The sections where the strap is connected at the rim sections are arranged in a distance which is greater than the length of the strap.

The extended section 12 acts as a tightening strap which does not cross the main chamber 3 and the additional chamber 11 since the extended section 12 is arranged at the rim sections of the main chamber 3 and the additional chamber 11 at the same side.

The additional chamber 11 is provided with an attachment tab

103 which is folded backwards onto the main chamber 3 like shown in Fig. 3. The attachment tab 103 of the additional chamber 11 is arranged after the folding on an attachment tab

104 of the main chamber 3. The attachment tabs 103 and 104 are fixed together with a not shown fixation element, which can be also used for fixing the attachment tabs 103 and 104 at the inner side structure 10 of the vehicle. When the curtain air- bag 100 is inflated in the folded status shown in Fig.l the additional chamber 11 will be inflated into the interior of the vehicle as the additional chamber 11 is fixed during the inflation with the attachment tab 103 at the attachment tab 104 at least at the upper rim of the curtain airbag 100. This effect supports the three dimensional shape of the main cham ^¬ ber 3 and the additional chamber 11.

In the figures 5 and 6 it is shown an enlarged section of the additional chamber 11 and the main chamber 3. The extended section 12 is provided with a tongue 15 directed towards the main chamber 3 as a prolongation of the non inflatable section 12 at the rim of the additional chamber 11. The tongue 15 is not connected sidewise to the additional chamber 11, so that it may be connected at a extended rim section 16 of the main chamber 3. The extended rim section 16 of the main chamber 3 where the tongue is attached is located with a greater dis ^¬ tance in the unfolded status compared to the length of the tongue 15, so that the tongue 15 and the additional chamber 11 are pulled towards the main chamber 3. The additional chamber 11 and the front section of the main chamber 3 are shaped like a baseball glove when unfolded, to catch the occupant 7 when moving like shown in figure 1.

The advantage of this embodiment is that no extra part is needed and only one attachment step is needed to pull the ad ^¬ ditional chamber 11 towards the main chamber 3 by attaching the tongue 15 at the rim section 16 of the main chamber 3 in one step. The same advantage can be achieved when the tongue 15 is designed as a prolongation of a extended rim section of the main chamber 3 and connected at a section of the rim of the additional chamber 11.

In the figure 4 it is shown the embodiment of the curtain air- bag 100 from figure 1 where the extended section 12 is de ^¬ signed as a triangular prolongation like a sail, which is attached at the rim section 16 of the main chamber 3. The additional chamber 11 is furthermore provided with an extended section 18, by which the additional chamber 11 is attached at an upper rim section 21 of the main chamber 3. The extended section 18 acts additionally to guide the gasflow from the main chamber 3 downwards and sidewise into the additional chamber 11. One important feature is in this case that the ex ^¬ tended section 12 and 18 are attached at rim sections 16 and 21 which are located at the same side of the main chamber 3. The upper extended section 18 is attached at an upper rim sec ^¬ tion 21 and the lower extended section 12 is attached at a lower rim section 16. The advantage of this design is that a clear cavity is created where the occupant 7 can dive in and the additional chamber 11 is attached with both rims at the main chamber 3.

The direction of deployment of the additional chamber 11 di ^¬ rected into the interior 1, is achieved by the extended sec ^¬ tion 12 limiting the movement of the additional chamber 11 relative to the main chamber 3 at one side. The extended sec ^¬ tion 12 does not cross the additional chamber 11 or the main chamber 3 as the connection is realized by a connection of the rim sections, so that an optimal restraint behavior can be re ^¬ alized without the risk an interference of the occupant with for example tethers.

The curtain airbag 100 can be manufactured by sewing up two fabric layers or by a fabric layer which is woven as one piece according to the "One Piece Woven (OPW) "-Technology, wherein the additional chamber 11 can be part of the fabric layer/s. In this case, the separation line 13 can be formed by a sepa ^¬ ration seam penetrating both fabric layers or, when the curtain airbag 100 is manufactured according to the OPW-Techno- logy, can be manufactured simultaneously during the weaving process. The extended section 12 can be realized by an exten ^¬ sion of one layer or as a sidewise extension of the extended rim of the airbag produced in the OPW technology.

In the figures 7 and 8 is shown another embodiment of the in ^¬ vention where the extended section 12 is designed as a flap, which is attached after folding the additional chamber 11 onto the main chamber 3 at an opposing side rim section 16 of the main chamber 3. The design after the folding with the attached flap is shown in the right cross section along the cutting line A-A. When the curtain airbag 100 is inflated in this sta ^¬ tus the main chamber 3 and the additional chamber as well will be inflated with a movement of the additional chamber 11 to ^¬ wards the interior 1 of the vehicle until the extended section 12 is tensioned and limits the further movement.

In figure 9 it is shown the same cross section A-A when the curtain airbag 100 is inflated. The extended section 12 is tensioned, so that the additional chamber 11 and the main chamber 3 are distanced with enclosing a cavity 22 where the occupant 7 may dive in.

In the figures 10-12 it is shown another preferred embodiment where the extended section 12 is extending along the rim side of the additional chamber 11 and as well along the rim side of the main chamber 3 where the additional chamber 11 is folded onto. In figure 11 it is shown the same curtain airbag 100 af ^¬ ter folding the additional chamber 11 onto the main chamber 3. As it can be seen the lower rim of the extended section 12 is running in an angle to the lower rim of the additional chamber 11 and of the main chamber 3 because the extended section 12 is shaped in the unfolded status shown in figure 10 like a V or an arrow with the peak directed to the top. The extended section 12 is sewn after the folding in a seam 23 at the rim sections. The advantage of this design can be seen therein that the distance of the additional chamber 3 to the main chamber 3 is continuously decreasing in forward direction of the curtain airbag 100 when inflated, which results in a cen ^¬ tralizing effect for the occupant 7 when he dives with the head 8 into the cavity 22.

In general the extended sections 12 and 18 may be inflatable, but using non-inflatable sections 12 and 18 is here advanta ^¬ geous as the extended sections 12 and 18 can be manufactured and sewn in an easier manner. Furthermore the extended sec- tions 12 and 18 got the only purpose to control the inflation characteristic of the additional chamber 11 with respect to the main chamber 3, so there is no disadvantage in the re ^¬ straint behavior if the extended sections 12 and 18 are non- inflatable. One advantage with inflating also the extended section 12 and 18 can be seen therein, that the extended sections 12 and 18 can be tensioned additionally by the inflation with a shortening effect.