DE19837749A1 - Air bag module used in vehicles has a catch band running inside a gas sack connected to the front inner side of the sack - Google Patents

Abstract

Air bag module comprises a gas generator and a gas sack (2). A catch band (4) running inside the sack is connected to the front inner side of the sack. The catch band is anchored by its rear side via an apparatus (8) introducing a force opposing the expansion of the sack into the band.

Description

The present invention relates to an airbag module that has a special Device for at least braking the propagation process of the Gas bag in the event that the vehicle occupant in the so-called "out-of-position" sitting position, so for example too tight sits on the airbag module.

It is known that airbags after physical deployment are severe May cause impairment if the vehicle occupant is not is in a predefined seating position. Even fatal accidents due to a broken neck caused by the airbag in the vehicle occupants been registered.

In the present case, an airbag module is assumed, which at least has a gas generator and a gas bag, in which the at least one Gas generator suddenly initiates gas upon a trigger signal. Internally of the gas bag runs a band that is connected to the front inside of the Gas bag is connected.

Such an airbag module is known from DE 196 11 384 A1. That in it described tape serves as a scanning medium to the Propagation speed of the gas bag after the module has triggered sense. Depending on the determined speed of propagation then only a certain number of gas generators or stages of one  multi-stage gas generator ignited. With lowered Propagation speed is assumed that the Motor vehicle occupant is in an "out-of-position" sitting position, so that the Airbag must not be inflated to full size, because of the premature Contact between the occupant and the airbag's unhindered spread with special needs.

The effort involved in the system according to the cited document is quite high. It is therefore the object of the present invention to provide a Airbag module to specify in which the "out-of-position" loads or the Airbag aggressiveness can be reduced with reasonable expenditure on equipment.

This task is solved by the airbag module with the features according to Claim 1. Alternative solutions are in claims 4 and 8 specified. Advantageous further developments of the respective proposals are in the Subclaims listed.

According to the first proposal, an airbag module is provided, which has at least one gas generator and a gas bag, in which the at least one gas generator in response to a trigger signal suddenly gas initiates. With the front inside of the airbag at least one in Intermediate tether connected to the airbag. This is on the back anchored in a fixed position over a spread of the gas bag counteracting force in the tether initiating device. The Counterforce that is introduced by the device has one Course that the deployment speed of the gas bag initially stronger is reduced than if the airbag unfolds further.

By the characteristic which the device in the tether or gives the tethered forces, it is achieved that the Total deployment time of the airbag is extended as little as possible.  

Each time the airbag module is triggered, the unhindered spread of the front airbag front by the introduction of counterforce into the tether counteracted. However, the total development time is not inadmissible extend, the initiated counterforce with a certain Provide characteristic. In addition to the force curves given below, the use of the alternative solutions is special following the passive system according to the first proposed solution switched off:

According to an advantageous development, it is provided that the counterforce, which initiates the device into the tether, initially kept constant and then from a predetermined measure of the length of the Tether is suddenly reduced to a low level, if necessary. until Zero.

This can advantageously be achieved, for example, if the Device which introduces the force is an attenuator that the Tether of a certain length is wrapped around the attenuator. The length of the tape determines the time from which no further Counterforce is introduced more into the band because it is from the attenuator is completely unwound during the spreading of the gas bag. This Embodiment is very inexpensive, but already offers the essential ones Advantages of the invention.

According to a first alternative proposed solution, it is provided that the tether attached on the back into one Brake mechanism leads, the speed of propagation of the Airbag is sensed and depending on the sensed Preparation speed an actuator is operated. This actuator brakes in the event of a detected reduced propagation speed the further spread of the gas bag by the brake mechanism.  

The starting point here is the sensed rate of propagation of the Gas bags. If a vehicle occupant is in the "out-of-position" Sitting position, the gas bag can not spread freely and the The speed of propagation is therefore reduced. At a given The threshold for reducing the speed of propagation becomes the Actuator operated by means of the brake mechanism of the other Spread the gas bag in the direction of the not optimally positioned Counteracts motor vehicle occupants.

The degree of braking of the further spreading of the gas bag can according to a preferred embodiment, stepped through the sensed reduced propagation speed can be controlled. The default is be that the sensing phase and the braking phase do not overlap, otherwise the system would be in an unstable state.

The braking mechanism preferably consists of a clamping mechanism. At The clamping mechanism is steplessly controlled by the actuator accordingly driven differently. Of course, this is also conceivable digital control, in which the clamping mechanism from a certain Worth the tether with full force while it is free can unfold.

Alternatively, it is provided that the brake mechanism as a switchable Damper is formed. Here, too, the specification of a force curve can be specified, for example, by the length of the tape.

According to a third proposed solution, in which the The speed of propagation of the gas bag is in turn sensed again a tether attached to the front inside of the gas bag provided, which leads into a pulling mechanism on the back. In Depending on the sensed speed of propagation, the  Pull mechanism operated so that it is reduced in the event of a detected Spreading speed at least the spreading of the gas bag partially reversed. In this case, the airbag becomes active pulled away from the vehicle occupant again to increase the load to reduce.

The pulling mechanism can preferably be a pyrotechnic tensioner like it otherwise is commercially available for use as a belt tensioner.

It is particularly preferred for the two proposed solutions with sensed Speed of expansion of the gas bag, if as an additional measure to prevent or complicate the further spreading of the gas bag with sensed reduced speed of propagation the actuator Gas discharge flaps in the module housing open. So in this case not only the further spreading of the gas bag by braking the Tether straps counteracted, but rather actively ensured that the Gas pressure in the gas bag is not increased further.

In the case of the aforementioned further training, it can also be provided that by opening the gas discharge flaps the flow cross section between Gas generator and gas bag is reduced. This means that through targeted Folding down individual gas discharge flaps into the flow cross section for the Gas between the gas generator and gas bag a reduction in Flow cross section can be achieved. As a result, the activation of the The amount of gas flowing into the airbag module is further reduced.

According to a preferred development it is provided that at least a band in cooperation with a scanner and one Electronics unit as a sensor for the speed of propagation of the Gas bag serves. This in itself is known from the already mentioned DE 196 11 384 A1.  

It can advantageously be provided for the two active (sensing) systems be constant to the braking forces introduced into the at least one band hold. This is recommended for the passive (non-sensing) system less according to the first proposal, since the time period for the complete Inflation of the gas bag could be affected so that the gas bag never is able to develop its full protective function.

According to all proposed solutions, i. H. even with the passive system, it can According to a further development, the at least one The braking forces introduced depend on the extended length of the belt. This is a training of the already in connection with the passive System explained solution proposal, namely the tether simply from Allow attenuator to roll until it is unwound, so that none Force application more follows. According to the proposed further training the counterforce depends in another way on the length of the tape.

Alternatively, it can be provided that the braking forces introduced by the Depending on the speed of the belt.

Finally, there is also a combination of both of the above-mentioned further training courses possible, according to which the braking forces introduced depend both on the extension length, as well as the speed at which the tape is pulled out.

The invention is based on three exemplary embodiments according to the figures explained in more detail. Here shows:

Fig. 1 shows an airbag module according to the first proposed solution during the expansion phase of the airbag (a), after immersing the vehicle occupant in the airbag (b) and when the airbag (c) is fully deployed, as seen from above, and the course of the counter forces introduced in Depending on the extension length of the tether ( 1 d),

Fig. 2 shows the airbag module according to the second solution, during the expansion phase of the airbag (a) and after immersing the vehicle occupant in the airbag (b), each seen from the side, and

Fig. 3 shows the airbag module according to the third solution during the expansion phase of the airbag (a), after immersing the vehicle occupant in the airbag (b) and opening the gas discharge flaps, and after triggering the pulling mechanism (c), also seen from the side.

The same parts are given the same reference numerals below.

In sequence from a to c, FIG. 1 shows the course of the expansion of an airbag 2 of a module according to the first proposed solution, in each case viewed from above, in the direction of a vehicle occupant 11 sitting in front of the module.

On the front inside of the airbag 2 , tether straps 4 are fastened, which are anchored at the rear in the module housing 6 in a stationary manner via a device 8 which introduces a force counteracting the expansion of the airbag into the tether straps 4 . In the present case, the device 8 is an attenuator, which initiates opposing forces with a characteristic according to FIG. 1d. At the beginning of the expansion of the airbag after the module has been ignited ( FIG. 1a), the counterforce introduced is greatest, as can be seen from FIG. 1d. In the further course ( FIG. 1 b ) , the gas bag 2 is unfolded laterally until the vehicle occupant comes into contact with the gas bag 2 . From this moment on, the airbag 2 will deploy more to the right and to the left due to the counter-forces introduced in the tether 4 , that is to say upward and downward in FIG . This results in a small safety reserve between the vehicle occupant 11 and the gas bag 2 that continues to unfold. This safety reserve is completely used up after the gas bag 2 has been fully inflated ( FIG. 1c) and the image practically no longer differs from an image of a conventional airbag system. However, due to the reluctance of the foremost front of the airbag 2 ( FIG. 1b), the goal set, namely the aggressiveness of the airbag, is weakened.

In the present case, the tether straps 4 are dimensioned in their length such that, after reaching a predetermined extension length L ₀ ( FIG. 1d), they no longer develop any counterforce against a further spreading of the gas bag 2 . This can be achieved, for example in einfachster manner that the tethers with the length of L ₀ are completely unwound from the attenuator 8, and so no generated in the damping member 8 retaining force 4 can act on the front side of the airbag 2 more.

The system is timed so that the time for the full deployment of the airbag 2 is not significantly impaired compared to conventional systems without tether.

In FIG. 2, an airbag module is shown according to the second proposed solution. Fig. 2a shows diagrammatically the air bag module during inflation phase of the gas sack 2. The gas generator 1 conducts gas into the gas bag 2 , which then unfolds and spreads in the direction of a vehicle occupant 11 .

In the interior of the airbag 2 , two straps 4 are fastened to its front inside, which are guided in a brake mechanism 5 on the rear. In the present case, the tapes 4 are also measuring tapes which, together with a scanning device 10, sense the speed of propagation of the gas bag 2 . In the present case, it is one of the two systems with a sensed rate of expansion of the airbag 2 . If the vehicle occupant 11 is in particular in the so-called “out of position” seating position, the airbag 2 will hit the body earlier than if the vehicle occupant were sitting in the correct seating position.

The early first contact of the vehicle occupant with the gas bag is sensed by the reduction in the speed of propagation of the gas bag 2 by means of the belts 4 and the scanning device 10 . If the reduction in the rate of expansion of the airbag 2 exceeds a certain value, an actuator 3 is activated ( FIG. 2b), which then actuates the brake mechanism 5 . This braking mechanism 5 can be a clamping mechanism that clamps the straps 4 to an increasing extent, for example, so that the straps 4 make it more difficult or prevent the further expansion of the gas bag 2 in the direction of the vehicle occupants 11 . The force introduced into the ligaments can follow various guidelines. It can range from constancy to a dependency on the length of the tapes and their pulling speed. In this way, the aggressiveness of the airbag in an "out-of-position" sitting position of the motor vehicle occupant 11 is considerably reduced, thereby reducing the risk of injury.

In addition, in the exemplary embodiment according to FIG. 2, the actuator 3 is designed such that it opens 2 gas outflow flaps (not shown) in the housing 6 when the gas bag senses a reduced propagation speed, which is symbolized in the present case by reference number 12 . As a result, the further gas flow from the gas generator 1 is not conducted into the gas bag 2 , but instead, for example, into the vehicle interior without increasing the dimensions of the gas bag 2 . The gas discharge flaps ensure that the pressure in the gas bag 2 is not increased any further.

Finally, FIG. 3 shows a further development of the system according to FIG. 2. In the present case, only the distinctive features are dealt with.

FIG. 3a shows a situation similar to that in FIG. 2a, namely the phase during which the airbag 2 is spreading in the direction of a vehicle occupant 11 . The straps 4 fastened to the front inside lead via a scanning device 10 to an evaluation unit in which the speed of propagation of the gas bag 2 is sensed. After the reduction in the rate of expansion of the gas bag has exceeded a preset threshold value, namely after the motor vehicle occupant 11 comes into contact with the gas bag 2 , the actuator 3 is actuated in a similar manner as in the exemplary embodiment according to FIG. 2 b, whereupon this gas discharge flap in the housing 6 opens, as this is to be illustrated again with reference number 12 .

At the same time or at a different time when the flap opening is actuated, a pulling mechanism 9 acting on the rear of the tether straps 4 is triggered, which is designed, for example, as a pyrotechnic tensioner. This situation is illustrated in Fig. 3c. Compared to FIG. 3b, the gas bag 2 already has a reduced volume due to the outflow of gas and is also actively pulled away from the vehicle occupant 11 by the pulling mechanism 9 , that is to say shifted to the right in FIG. 3c.

The three systems presented differ in their effects and mode of operation, but of course also in terms of costs. While the The first solution in the low-cost area has to be settled for the two sensing systems with active actuators allow for higher costs become.

Claims (16)

Airbag module, comprising at least one gas generator ( 1 ) and one gas bag ( 2 ), into which the at least one gas generator ( 1 ) suddenly introduces gas upon a trigger signal, in which at least one inside the gas bag with the front inside of the gas bag ( 2 ) extending tether ( 4 ) is connected, which is anchored at the back in a stationary manner via a force which counteracts the spreading of the gas bag ( 2 ) into the tether ( 4 ) and which initiates the device ( 8 ), the counterforce having such a force profile that the rate of deployment of the airbag ( 2 ) is initially reduced more than if the airbag ( 2 ) continues to unfold. 2. Airbag module according to claim 1, in which the counterforce is initially kept constant and is then suddenly reduced to a lower level from a predetermined degree of expansion of the gas bag ( 2 ). 3. Airbag module according to claim 1 or 2, wherein the device ( 8 ) is an attenuator. 4. Airbag module, comprising at least one gas generator ( 1 ) and a gas bag ( 2 ), into which the at least one gas generator ( 1 ) suddenly introduces gas upon a trigger signal, and in which at least one band ( 4 ) fastened to its front inside runs , which leads at the rear into a braking mechanism ( 5 ), the speed of propagation of the gas bag ( 2 ) being sensed and, depending on the sensed speed of propagation, an actuator ( 3 ) being actuated which, in the event of a determined reduced rate of propagation, the further spreading of the gas bag ( 2 ) braked or stopped by the braking mechanism. 5. Airbag module according to claim 4, in which the degree of braking of the further spreading of the gas bag ( 2 ) is steplessly controlled by the sensed, reduced spreading speed. 6. Airbag module according to claim 4 or 5, wherein the braking mechanism ( 5 ) consists of a clamping mechanism. 7. Airbag module according to claim 4 or 5, wherein the braking mechanism ( 5 ) is a switchable damper. 8. Airbag module, comprising at least one gas generator ( 1 ) and a gas bag ( 2 ), into which the at least one gas generator ( 1 ) suddenly introduces gas upon a trigger signal, and in which at least one band ( 4 ) attached to its front inside runs which leads at the rear into a pulling mechanism ( 9 ), the speed of propagation of the gas bag ( 2 ) is sensed and, depending on the sensed speed of spreading, the pulling mechanism ( 9 ) is actuated such that, in the event of a detected reduced spreading speed, the spreading of the gas bag ( 2 ) at least partially reverses. 9. Airbag module according to claim 8, wherein the pulling mechanism ( 9 ) is a pyrotechnic tensioner. 10. Airbag module according to one of claims 4 to 9, wherein the actuator ( 3 ) additionally opens gas outflow flaps in the housing ( 6 ) of the module at a sensed reduced propagation speed. 11. Airbag module according to claim 10, in which the flow cross-section between gas generator and gas bag ( 2 ) is reduced by opening the gas discharge flaps. 12. Airbag module according to one of claims 4 to 11, wherein the at least one band ( 4 ) in cooperation with a scanning device and an electronics unit serves as a sensor for the speed of propagation of the gas bag ( 2 ). 13. Airbag module according to one of claims 4 to 12, in which the braking forces introduced into the at least one band ( 4 ) are constant. 14. Airbag module according to one of claims 1 to 12, wherein the introduced into the at least one belt (4) braking forces depend on the extension length of the tape (4). 15. Airbag module according to one of claims 1 to 12, wherein the introduced into the at least one belt (4) braking forces depend on the withdrawal speed of the belt (4). 16. Airbag module according to one of claims 1 to 12, wherein the introduced into the at least one belt (4) braking forces depend on the extension length and extract speed of the belt (4).