WO2006048147A1 - Motor vehicle front airbag module - Google Patents

Abstract

The invention relates to a motor vehicle front airbag module, comprising a gas generator (12) and an inflatable bag which is fillable by said gas generator and provided with an outer envelop (14) encompassing the entire gas chamber. When the inflatable bag is completely expanded, the outer envelop consists of an impact area (14a), a lower support area (14c) disposed in front of an instrument panel (A) and a top support area (14b) disposed in front of a windscreen (W). An internal envelop (16) encompassing a partial gas chamber (17) is arranged inside the outer envelop (14), at least the great amount of gas received from the gas generator (12) comes first to said partial gas chamber (17) and, afterwards therefrom to a main gas chamber (15) through openings (18) disposed in the internal envelop (16) between said internal envelop (16) and the outer envelop (14). In order to improve the protection of a forwardly bent child, the opening (18) is embodied in the form of a gas guiding element which guides the gas in an area situated between the impact area (14a) and the lower support area (14c). For this purpose, at least one tubular section (19) begins from the central section (16a) of the internal envelop (16) and the open end thereof forming the opening (18) is arranged in the impact section oriented towards a passenger when the inflatable bag is entirely expanded.

Description

 Front airbag module for a motor vehicle

description

Technical field of the invention

The invention relates to a front airbag module for a motor vehicle according to the preamble of claim 1.

The module for a passenger airbag is usually in Armaturen¬ board above the glove compartment. In the fully expanded state, the airbag cover has a pointing in the direction of the passenger impact area and a support area, which rests on components of the vehicle. The gas bag cover can in this case be designed such that one part of the support region rests against the inside of the windshield and another part on the dashboard.

A fundamental problem with the use of gas bags is that occupants not sitting in standard sitting position (out of position - OoP -) may not be loaded too heavily by the outgoing gas bag. A particularly critical case in this case is the situation in which a child of, for example, 6 years bent forward sitting in the passenger seat and whose head is located directly in front of the dashboard.

The problem of protecting out-of-position occupants is further aggravated by the fact that, for example, US law requires improved protection of unguarded occupants, which as a rule can only be achieved by increasing the gas generator capacity , Increasing inflator performance, in turn, negatively impacts the protection of the out-of-position occupant. Therefore, a reduction of the gas generator power introduced into the airbag in the case of an out-of-position occupant is obvious. For this purpose, there are a variety of solutions, which is essentially a gas discharge from the gas bag or the module housing provide. These solutions are largely based on active systems that require sensing the out-of-position situation. The weak point of such systems is the reliability of out-of-position sensing.

State of the art

From EP 1 415 868 A2 a two-layered gas bag is known. The inner gas bag is used here to open a cover of the airbag housing in unfolding gas bag.

Subject of the invention

On this basis, it is an object of the invention to provide a passive working system that improves in particular the protection of a child bent forward.

This object is achieved by a front airbag module with the features of An¬ claim 1.

The gas bag of the gas bag module according to the invention is formed in two parts with an outer shell and an inner shell. In this case, the inner shell immediately adjoins the inflow region of the gas, so that all the gas or at least a large part of the gas must first flow through the partial gas space enclosed by the inner shell before it enters the main gas space, which is located between inner shell and outer shell , The maximum volume of the partial gas space is relatively small compared to the maximum volume of the total gas space, that is, the maximum extent of the inner shell into the passenger compartment is small in proportion to the maximum extent of the outer shell.

At least one opening in the inner shell is designed as a guide element, which directs the gas into a region between the impact area and a lower support area of the outer shell. This is achieved by moving from a central Section of the inner shell at least one hose-like portion (19) extends, the open end, which forms the opening is located in fully expanded airbag in the region of the occupant facing the end of Prallab¬ section.

Due to the fact that all gas, or at least a large part of the gas, flows through the part-gas space enclosed by the inner shell, the greatest pressure prevails here within the total gas space. With suitable ventilation, the pressure in the partial gas space can be significantly higher than the pressure in the main gas space. The fact that the expansion of the inner shell is relatively small, the risk of injury to a bent over child is low even if the head rests on a front portion of the dashboard. Nevertheless, the inner shell can prevent the child's head from coming into contact with the windshield.

The fact that a contact of the head of the child can be excluded even if the child is unglued, the unfolding of the outer shell can be done with relatively little force, so that the upper body of the child with verhält¬ tively low introduction of force line pressed into an upright position can be. This is achieved in particular in that the gas is wholly or partly first directed into a lower region of the unfolding outer shell. By appropriate shaping of the inner shell, in this case the gas flow can be deflected so that the unfolding of the outer shell takes place in a manner which is gentle on the OoP occupant. For this purpose, it is particularly preferred that two gas-conducting openings are present in the inner shell, which introduce the gas left and right of a central region in the main gas space. If there is no out-of-position situation, the gas bag can thus develop freely, the presence of the Innenhülie from the outside is not noticeable.

Further advantageous embodiments will become apparent from the other subclaims as well as from the Aus¬ guide example now shown in more detail with reference to the figures. Hereby show: - A -

Brief description of the drawings

FIGS. 1 to 5 show the deployment of an airbag having an inner shell in the presence of a dumbbell which has been bent over in front of an approximately 6-year-old child;

5a shows a section along the plane B-B of Figure 5.

FIGS. 6-10 show a front airbag module according to the described exemplary embodiment in a representation corresponding to FIGS. 1-5 and FIG. 11 a section along the plane A-A from FIG. 10.

Figures 1 to 5 show a front airbag module, the gas bag has an Au¬ ßenhülle and an inner shell, and its mode of operation in the presence of a 6-year-old representing dummies D, which sits bent over front in the passenger seat. First, the components of the front gas bag module will be explained with reference to FIG. 5:

The gas bag module has an airbag housing 10 accommodated in the dashboard A with a gas generator 12. The gas bag consists of an outer shell 14 and an inner shell 16. The inner shell 16 adjoins the gas bag housing 10 directly, so that all gas coming from the gas generator 12 has to flow through the gas compartment 17 enclosed by the inner shell 16. From there, the gas flows through gas-conducting openings 18 in the located between the inner shell 16 and outer shell 14 main gas space 15. The total gas space is thus divided into the main gas chamber 15 and the partial gas chamber 17.

The outer shell 14 generally has at least one ventilation opening, through which the gas flows. As a result, the pressure in the main gas space 15 is limited. Because the gas first flows into the partial gas space 17 and from there into the main gas space 15, from which it can only escape again, the pressure in the partial gas space 17 is higher than in the main gas space 15 Gas generator power and ventilation opening are usually dimensioned such that the pressure in the main gas space 15 corresponds to that of a "normal" passenger gas bag. If, in a standard situation, the strapped or unbelted occupant falls into the fully expanded airbag, it reacts like a normal airbag. The presence of the inner shell 16 is not felt.

The improvement comes in out-of-position situations, especially in out-of-child positions. The behavior of the system is shown in FIGS. 1 to 5 when a dummy representing a 6-year-old child rests bent over the armature board at the beginning of the gas bag deployment.

As shown in FIG. 1, the inner shell 16, which encloses the relatively small partial gas space 17, unfolds very quickly. As a result, an impact of the head of the dummy D on the windshield W is reliably prevented. Da¬ by that the partial gas space 17 is relatively small, the force of the unfolding inner shell 16 on the head despite the high internal pressure is low. The partial gas space has a substantially circular cross-section.

As shown in FIG. 1, the head rests against the inner shell 16 and thus also against the outer shell 14 and clamps the outer shell 14. As a result, the outer casing 14 can not expand upwards and therefore initially begins to expand forwards and downwards, as can be seen in particular in FIGS. 2 and 3. As a result, the outer shell 14 unfolds between dashboard A and the dummy D, so that the upper body of the dummy is pressed gradually into an upright position with relatively little force. This type of deployment is essentially supported by the position of the gas-conducting openings 18. The gas-conducting openings are located at a location of the inner shell 16, which is adjacent to the lower support portion 14c of the outer shell. As a result, the gas flow is directed into an area which is located between the impact area 14a and the lower support area 14c. The main gas space is thereby filled in a certain way from bottom to top. In the illustrated embodiment There are still more openings 18a in the inner shell, which allow a portion of the gas to flow laterally into the main gas space.

As can be seen with reference to FIG. 5 a, two gas-conducting openings 18 are present in the inner shell 16. These are arranged so that two gas streams spread to the left and right of a central region 15a in the main gas space 15. This causes an additional relief of the head and chest area of the dummy or the occupant, since the dummy / inmate is not flowing directly.

In a central region 15a, lower support region 14c and impact region 14a are sewn together via sacrificial seams 20. These break up during the gas pocket unfolding, dissipating energy in this section. This leads to a further protection especially of the chest area of the occupant.

Due to the two-shell construction, it is thus achieved that, despite the provision of the high retention force in an initial phase, the introduction of force into the occupants takes place comparatively smoothly.

Description of a preferred Ausführunαsbeispiels

Figures 6 to 11 show an embodiment of the invention. Here is the low-load application of force in the case of an out-of-position situation compared to what has been described even better. The inner shell 16 has a central portion 16a and two hose-like portions extending from this central portion 16a, hereinafter referred to as hose portions 19. The two tube sections 19 extend to the left and to the right of the central region 15a of the main gas space 15. The tube sections 19 whose end faces are open and thus form the gas-conducting openings 18 of the inner envelope 16 end in the vicinity of the impact area 14a of the outer envelope 14 in a transition region between the impact area 14a and the lower Ab¬ support area 14c, which rests on the dashboard A. As a result, as can be seen in particular in FIGS. 8 and 9, the unfolding of the outer shell 14 of FIG particularly supported below, so that the head of the occupant is additionally discharged.

Because the two tube sections 19 extend to the left and right of the central region of the main gas chamber, the occupant's chest region only senses the internal pressure of the main gas chamber and not the higher pressure of the partial gas chamber 17. A direct flow of the occupant does not take place.

It may be useful to connect the hose sections to the outer shell 14, in particular to the lower support area 14, for example to sew it.

Again, sacrificial sutures 20 may be present as described above.

Since the presence of the inner shell 16 should not be noticeable when the outer shell 14 is fully expanded, the volume of the partial gas space 17 must be substantially less than the volume of the entire gas space. Preferably, the volume is less than 25% of the total volume.

LIST OF REFERENCE NUMBERS

10 airbag housing

12 gas generator

14 outer shell

14a impact area

14b upper support area

14c lower support area

15 main gas room

15a central area

16 inner shell

16a central section

17 partial gas chamber

18 opening

18a further opening

19 hose section

20 sacrificial seams

A dashboard

W windshield

D dummy

Claims

claims 1. Front airbag module for a motor vehicle having a gas generator (12) and a gas bag which can be filled by the gas generator with an outer casing (14) enclosing a total gas space, which in the case of a fully expanded gas bag has a baffle region (14a), a lower supporting region ( 14c), which rests on the dashboard (A) and an upper support region (14b) which rests against the windshield (W), wherein within the outer shell (14) a partial gas space (17) enclosing the inner shell (16) arranged is, wherein at least a majority of the Gasgenere¬ generator (12) coming gas first in the partial gas space (17) and from there via openings (18) in the inner shell (16) in the main gas space (15) between the inner shell (16) and outer shell (14), characterized in that at least one opening (18) is designed as a gas-conducting element which directs the gas into a region between impact area (14a) and lower support area (14c), where at least one hose-like section (19) extends from a central section (16a) of the inner casing (16), the open end of which forms the opening (18) being in the area of the end facing the occupant when the gas bag is fully expanded Impact section is located. 2. Front gas bag module according to claim 1, characterized in that at fully expanded gas bag, the volume of the partial gas space is maxi¬ times 25% of the volume of the total gas space. 3. Front gas bag module according to one of the preceding claims, characterized in that the inner shell is connected directly to the gas generator, and the entire gas stream first passes into the partial gas space (17). 4. Front airbag module according to one of the preceding claims, characterized in that at least the central portion (16 a) of the inner shell has a substantially kreisför¬ shaped cross section in the fully expanded state. 5. Front gas bag module according to one of the preceding claims, characterized in that in the resting state baffle surface and lower Abstützflä¬ che at least in sections via sacrificial sutures (20) verbun¬ are the, which are destroyed in fully expanded airbag. 6. Front gas bag module according to claim 5, characterized in that the sacrificial seams are provided only in the region of the breast. 7. Front gas bag module according to one of the preceding claims, characterized in that there are two hose-like sections (19) which extend to the left and right of a central region (15a) of the main gas chamber. 8. Front gas bag module according to one of the preceding claims, characterized in that the tubular portion (19) with the outer shell (14) is connected. 9. front air bag module according to claim 8, characterized in that the tubular portion is connected to the lower support region.