WO2009024299A1

WO2009024299A1 - Front passenger airbag module

Info

Publication number: WO2009024299A1
Application number: PCT/EP2008/006728
Authority: WO
Inventors: Karl-Heinz Sommer; Thomas Reiter; Marcus Weber; Jörg ALBERT
Original assignee: Autoliv Development Ab
Priority date: 2007-08-18
Filing date: 2008-08-15
Publication date: 2009-02-26
Also published as: DE102007039113A1

Abstract

A front passenger airbag module with a housing (10) mounted into the instrument panel (40) of a motor vehicle, with an exit opening (14), an airbag folded into housing (10) which can be filled by means of an inflation device, a cover and guide element (20) consisting of fabric, which in quiescent state at least partially covers exit opening (14), and which guides the airbag during expansion, and a door (42) consisting of plastic, which spans over exit opening (14) is described. The surface of door (42) forms a part of the surface of instrument panel (40). In order to prevent the windscreen from being damaged during expansion of the airbag, the cover and guide element (20) is connected to door (42).

Description

Front passenger airbag module

Description

Technical field of the invention

The invention relates to a front passenger airbag module according to the intro- ductory section of Claim 1.

Front passenger airbag modules of the generic type are widespread and are currently installed in almost every new car. The housing of such a front passenger airbag module - hereinafter referred to in brief as airbag module - is installed in the instrument panel on the passenger side of the instrument panel. Within this, the outlet opening of the housing is frequently located in a horizontal section of the instrument panel near to the windscreen. Because of this geometry, the expanding airbag often transfers high forces to the windscreen directly or indirectly, which, under unfavourable conditions, can lead to breakage of the windscreen, which is naturally undesirable. Different solutions have become known as to how a too-strong transfer of force from the expanding airbag to the windscreen can be avoided:

Prior art

EP 0 940 300 B1 proposes supplying a hinge strap made of woven ribbon, which connects the door which covers the housing in quiescent state and which is opened by means of the expanding airbag, with a part of the instrument panel which is fixed to the vehicle. The opening angle of the door is limited by means of such a hinge strap and in particular, it can be prevented that the door strikes against the windscreen. The design which is proposed is, however, relatively complicated. US 5 306 042 proposes a similar design, but with rigid components. Here again, the design is complicated and of not inconsiderable weight.

Generic patent application JP 08-72657 proposes a cover and guide element consisting of fabric, which is connected to the housing and which covers the exit opening of the housing when in quiescent state. On expansion of the airbag, this cover and guide element is folded up and forms a kind of hood with an opening pointing in the direction of the passenger. This hood diverts the expanding airbag during an early phase of its expansion and therefore at least softens the shock to the windscreen. In the case of the airbag module described in this patent application, however, it cannot be prevented that the door which is opened by the expanding airbag strikes against the windscreen with a high force, which under unfavourable circumstances can be sufficient to damage the windscreen.

Summary of the invention

Starting from this point, the present invention sets itself the task of creating a front passenger airbag module which is simply constructed, which is not of considera- bly higher weight in comparison to traditional front passenger airbags and by means of which damage of the windscreen by the expanding airbag is effectively prevented.

This task is solved by a passenger airbag module with the characteristics of Claim 1.

According to the invention, the cover and guide element which covers the exit opening of the housing when in quiescent state and which guides the airbag when it expands is connected with the door consisting of plastic, which spans over the exit opening of the housing, whereby the surface of the door forms a part of the surface of the instrument panel. By means of this connection it can reliably be prevented that the door strikes the windscreen when the airbag expands. In addition, this connection means that a relatively large amount of energy can be dissi- pated, which not only softens the shock which effects the windscreen, but also softens the force influence on an object which may be near to the exit opening.

In a first preferred embodiment in accordance with Claim 2, an upper section of the cover and guide element is moulded into the door. It is true that this slightly increases the amount of work to be performed during the manufacturing process; however, this embodiment has the advantage that the connection between cover and guide element and door cannot be separated, even if surrounding or environmental conditions are unfavourable, and that incorrect assembly is not possi- ble. However, as an alternative, it is also possible to glue the cover and guide element to the door or to supply "Velcro" type tape for the connection. If "Velcro" type fastenings are used, it is possible that the door separates from the cover and guide element when the airbag expands. However, in this process, so much energy is lost that damage to the windscreen by the door is excluded.

In particular, if, in accordance with Claim 2, the cover and guide element is moulded into the door, according to Claim 5 it is preferred that side sections of the cover and guide element are moulded into the section of the instrument panel which surrounds the door. This makes final assembly easier and assembly faults are excluded.

According to Claim 8, fold sections of the cover and guide element, when in folded state, can be connected with each other by dissipative means - for example by tear seams. This measure makes it possible to reduce the energy which is trans- ferred to an obstacle which may be present at an early time using simple means

Further preferred embodiments of the invention result from the other subclaims and also from the embodiments described now in relation to the figures. The figures show: - A -

Brief description of the drawings

Figure 1 A housing of an airbag module with a cover and guide element folded in quiescent state in a three-dimensional view, Figure 2 The housing from Figure 1 with an unfolded cover and guide element,

Figure 3 The housing from Figure 1 in a state when it is mounted into an instrument panel, whereby a complete airbag module is formed, in a view from direction A from Figure 1, Figure 4 A second embodiment of an airbag module in a view corresponding to Figure 3,

Figure 5 A section of an instrument panel with a door, whereby a folded cover and guide element is moulded into the instrument panel,

Figure 6 A third embodiment of the airbag module according to the invention with the instrument panel from Figure 5 in a view corresponding to

Figure 3,

Figure 7 Airbag module from Figure 6 in activated state.

Detailed description of preferred embodiments

Figure 1 shows a housing 10 and a gas generator 30 serving as an inflation device of a front passenger airbag module (hereinafter referred to as airbag module). The majority of exit opening 14 of housing 10 is covered by a cover and guide element 20 made of woven fabric. An airbag (not shown) is folded into the hollow space which is enclosed by housing 10 and cover and guide element 20. In the complete airbag module, the exit opening 14 is spanned over by a door. This door is, however, part of the instrument panel and is therefore not shown in Figure 1. Gas generator 30 is a so-called submarine gas generator with a generation area 32 and a connecting piece 34 standing vertical to generation area 32 (cannot be seen in Figures 1 and 2), which extends into the inside of the housing. A flange 12 extends round exit opening 14, which serves to screw housing 10 together with the instrument panel from below. Edge strips 23 of cover and guide element 20 lie on this flange 12, so that, following connection of housing 19 with the instrument panel, they are held between flange and instrument panel. In order to hold these edge strips 23 safely in position, including during assembly, the edge strips can be glued to flange 12.

As can be seen from Figure 1 , cover and guide element 20 is folded when in quiescent state, namely in such a way that two fold sections 22 located at the side are folded to the middle in the direction of an upper section 21. The expression "upper section" is related to the unfolded state that can be seen for example in Figure 2. Fold sections 22 are folded on upper section 21 in the fashion of a Z- folding pattern. The three layers of the Z-folding pattern which come into being in this way are designated in Figure 1 with reference numbers 22a and 22b - these belong to fold section 22 - and 21a - this layer belongs to upper section 21. Preferably, dissipative means are provided between two or all three layers respectively. The following text describes several design possibilities for these dissipa- tive means:

On the one hand it is possible to provide tear seams, which connect the two layers 22a, b or all three layers 22a, 22b and 21a with one another.

Furthermore, it is possible to provide "Velcro" elements, which are provided between layers 22a and 22b or between layers 22b and 21a. It is also possible to provide elements with a high level of friction between the layers.

Figure 2 shows the items shown in Figure 1 , whereby cover and guide element 20 is in its open position. In this position, there is an opening 28 pointing in the direction of the passenger, from which the airbag, not shown here, exits. If gas generator 30 is ignited, its gas fills the airbag, which first presses against folded cover and guide element 20, until it unfolds into the position shown in Figure 2. The above-described dissipative means have the effect that during the unfolding of cover and guide element 20, energy is dissipated, so that the airbag exits from opening 28 with relatively low kinetic energy, so that at his moment, it cannot transfer very great energy to an object which is immediately in front of this open- ing. This serves in particular to protect a vehicle occupant who is leaning forward and who has his head near to opening 28.

Figure 3 shows the assembly consisting of gas generator 30 and housing 10 which is screwed together with the inner side of an instrument panel 40, so that a complete airbag module in the sense of this application comes into being. The section of instrument panel 40 located above exit opening 14 forms door 42, which is connected with section 41 of instrument panel 40 surrounding the door by means of a set break line 44 and a hinge area which is not shown. The hinge area is generally located on the edge of the door facing away from the passenger, in other words near to the windscreen. Instrument panel 40 is generally a one-piece plastic part which is manufactured by the injection moulding process. Despite this one-piece structure, door 42 is considered to belong to the airbag module.

Upper section 21 of cover and guide element 20 is connected with door 42 by means of a connection 46. This connection 46 can be in the form of a glued location or as a "Velcro"- type fastening. This connection 46 achieves the result that door 42 also remains connected with cover and guide element 20 during expansion of the airbag, so that its flap-open angle is limited and it cannot strike the windscreen.

Figure 4 shows an alternative to the items shown in Figure 3. Here, the upper section 21 of cover and guide element 20 is moulded into door 42, so that instrument panel 40 and cover and guide element 20 form a one-piece component. In this case, the connection between cover and guide element 20 and housing 10 occurs not until final assembly of housing 10 on instrument panel 40. With regard to the function, this second embodiment does not differ from the first embodiment. As can be seen by comparison of Figures 3 and 4, the folding of cover and guide element 20 in the second embodiment is orientated differently than in the first em- bodiment.

Figure 5 shows the section of instrument panel 40 in which door 42 and section 41 surrounding the door are located in accordance with a third embodiment of the invention. Here, not only upper section 21 is moulded into instrument panel 40 - namely the door -, but also an edge section 25. Fold sections 22 are naturally not moulded in. This means, that cover and guide element 20 is completely assigned to instrument panel 40 and does not have any direct connection with housing 10. Nevertheless, cover and guide element 20, as can be seen from Figure 6, covers opening 14 of housing 10, when it is mounted on the instrument panel. This embodiment of the invention makes the mounting of housing 10 on instrument panel 40 particularly simple and excludes the possibility of assembly faults.

Figure 7 shows the elements shown in Figure 6 following actuation of gas generator 30, whereby the airbag which is not shown opens the cover and guide element 20 together with door 42.

List of reference numbers

10 Housing

12 Flange

14 Exit opening

16 Side wall

20 Cover and guide element

21 Upper section

22 Fold section

23 Side strips

25 Edge section

28 Opening

30 Gas generator

32 Generation area

34 Connecting piece

40 Instrument panel

41 Surrounding section

42 Door

44 Set break line

46 Connection

50 Screw

Claims

Patent claims

1. Front passenger airbag module with a housing (10) mounted into the instrument panel (40) of a motor vehicle, with an exit opening (14), an airbag folded into the housing (10) which can be filled by means of an inflation device, a cover and guide element (20) consisting of fabric, which in quiescent state at least partially covers the exit opening (14), and which guides the airbag during expansion, and a door (42) consisting of plastic, which spans over the exit opening (14), whereby the surface of the door (42) forms a part of the surface of instrument panel (40), characterised in that cover and guide element (20) is connected with the door (42).

2. Front passenger airbag module according to Claim 1 , characterised in that an upper section of the cover and guide element (20) is glued to the door

(42).

3. Front passenger airbag module according to Claim 1 , characterised in that an upper section (21 ) of the cover and guide element is bonded together with the door (42).

4. Front airbag passenger module according to Claim 1 , characterised in that an upper section (21 ) of the cover and guide element is connected with the door (42) by means of "Velcro" fastenings.

5. Front passenger airbag module according to one of the previous claims, characterised in that the door (42) is formed in one piece with the section (41 ) of the instrument panel (40) surrounding the door (42).

6. Front passenger airbag module according to Claims 2 and 5, characterised in that edge sections (25) of the cover and guide element (20) are moulded into the section (41 ) of the instrument panel surrounding the door (42).

7. Front passenger airbag module according to one of the preceding claims, characterised in that the cover and guide element is folded when in quiescent state.

8. Front passenger airbag module according to Claim 7, characterised in that fold sections (22) of the cover and guide elements are connected with each other by dissipative means in folded quiescent state.

9. Front passenger airbag module according to Claim 8, characterised in hat the dissipative means are tear seams.

10. Front passenger airbag module according to Claim 8, characterised in that the dissipative means are fabric sections with high friction.

11. Front passenger airbag module according to Claim 8, characterised in that the dissipative means are detachable "Velcro" -type connections.