DE102014001782B4 - Airbag unit with an adaptive ventilation device - Google Patents

Abstract

A gas bag unit for a motor vehicle having a first casing (10) enclosing a first gas space (13), the first casing (10) having at least one ventilation opening (12), a throttle element connected to the first casing (10), which controls the gas flow through the at least one ventilation opening (12) throttles more strongly in a first state than in a second state, a tension element (60) extending from a first end (62) to a second end (64), which is connected to the throttle element at least in the first state and which, when under tension, holds the throttle element in its first state, and an actuatable retainer (40) which connects the traction element (60) in an initial state to a vehicle-fixed component and which actuates the traction element (60) in one State releases, wherein the second end (64) of the tension element (60) in the initial state with the holding device (40) is connected, characterized g ekennzeichnet that the first end (62) of the tension element (60) with the first shell (10), with the vehicle-fixed component or with another vehicle-fixed component is connected and that the throttle element has at least one opening (18, 18 ') through which the tension element (60) extends at least in the first state, so that the tension element (60) is subdivided into two sections in the first state and thus a kind of pulley is formed.

Description

The invention relates to an airbag unit with an adaptive ventilation device according to the preamble of claim 1.

Almost every airbag, in particular each front airbag, has a ventilation device, through which gas from the gas space enclosed by the outer shell of the airbag-also referred to below as the first shell-also referred to below as the first gas space, escapes when the person to be protected strikes can, so that kinetic energy of the person to be protected is dissipated and the person to be protected does not simply bounce back from the airbag cover of the airbag. In the simplest case, such a ventilation device is simply a ventilation opening, in particular a ventilation opening in the gas bag envelope.

In order to be able to take account of different accident situations and / or the weight of the person to be protected, adaptive ventilation devices for influencing the pressure in the first gas chamber are known in the prior art. Such adaptive ventilation devices generally have, in addition to the ventilation opening, a throttle element which, in a first state, throttles the gas flow through the ventilation opening more strongly than in a second state. The ventilation opening and the throttle element in this case form a ventilation unit. As a rule, in this case the first state is the throttled or even closed state and the second state is the less throttled, for example fully opened state. Furthermore, such an adaptive ventilation device has a control device which influences the state of the throttle element in response to an external (mostly electrical) signal.

An example of such an active control device shows the generic US 6 648 371 B2 , The active control device here has a pyrotechnically operating actuator as a holding device and a tension band serving as a tension element. Here, the first end of a tension band is connected to the flap formed as a throttle element and the second end of this tension band with a pin of the actuator. The actuator is in this case held in particular on the housing bottom of the gas bag module. As long as the actuator is not actuated, thus the throttle element is connected via the drawstring to the housing bottom. The tension band comes with fully expanded airbag shell in a tensioned state, which holds the throttle element in its first state. If the actuator is actuated, the bolt which holds the second end of the tension element is blasted off by means of a pyrotechnic charge, the tension element loses its tension and the throttle element changes into its second, namely its unthrottled state. This technique works very well, in particular, very large holding forces can be applied. However, a disadvantage may be that within the gas space of the airbag shell parts, such as the bolt, can fly around, and that within the airbag shell open flames by the pyrotechnic charge occur. Furthermore, the pyrotechnic charge feeds additional gas into the gas space of the airbag shell, which is not always desirable.

The WO 2014/001 317 A1 shows a similar working, serving as a holding element actuator. Here is a primer surrounded by a tube. The actuator facing away from the (usually upper end) of the tube is closed by a tear seam. This tear seam also holds the second end of a drawstring. If the primer ignited due to an electrical signal, the tear seam breaks, causing the initially closed end of the tube opens and the second end of the drawstring is released. The advantage here is that no bolt or the like can fly around inside the airbag. However, here too the gas of the primer is fed into the gas space of the gas bag. Another disadvantage compared to a control device, as in the US 6 648 371 B2 is shown, is that the holding forces, which are transmitted by means of the tear seam, are limited. This is due to the fact that the tear seam can of course not be too strong, as it would then not break upon actuation of the associated primer.

The DE 10 2005 039 418 B4 proposes an airbag module with an adaptive ventilation device, in which the control device has a "small airbag module inside the airbag module" with a shell (second shell) and a gas source. Here, the throttle element can be influenced by the second shell. The shell of this second airbag - hereinafter referred to as the second shell - encloses a second gas space, which can be filled with gas by a gas source, which is designed in particular as a primer. If this happens, then the second shell, which is then filled with gas, lifts the throttle element, which is in the form of a flap, away from the ventilation opening, so that the ventilation device changes into its second, unthrottled state. It is particularly advantageous here that the gas generated by the squib remains in the second gas space. The disadvantage of this is that the second shell and the ventilation opening must be immediately adjacent to each other, which is often very difficult to implement. In particular, it is hardly possible to provide the ventilation opening in the gas bag envelope.

The DE 603 04 267 T2 shows an airbag unit whose shell has a ventilation opening. A first end of a hose is sewn around the ventilation opening with the sleeve. In the initial state, this hose, which forms a throttle element, extends into the gas space enclosed by the casing and is held by a holder. In response to an external signal, the holder releases the tube, which is then pushed outward through the ventilation opening, as a result of which it is no longer throttled by the tube.

On this basis, the present invention has the object to further develop a generic airbag module such that the holding forces that must be transmitted between tension element and holding device are reduced.

This object is achieved by an airbag module having the features of claim 1.

According to the invention, the first end of the tension element is connected to the airbag shell or to a vehicle-fixed component, and the throttle element has at least one opening through which the tension element extends at least in the first state. It is thus formed a kind of pulley, whereby the applied by the tension element holding force is distributed to two portions of the tension element. It follows that the force which is transmitted between the tension member and the holding device, is substantially halved compared to the prior art.

Often it will be preferable that the second end of the tension member in the initial state is immovably connected to the holding device or a part thereof.

By reducing the holding force to be applied, it is in particular easily possible to form the holding device as a second shell enclosing a second gas space, with which the second end of the tension element is sewn in the initial state by means of at least one tear seam. In this case, furthermore, a gas source for filling the second shell is provided, such that when the second shell is filled, the tear seam tears and releases the second end of the tension element. In this case, it is particularly preferable for the second gas space, which is enclosed by the second shell, to remain closed even after it has been filled.

In order to obtain a high holding force and yet ensure that the tear seam is destroyed when filling the second gas space, it may be advantageous that the second gas space is divided in the initial state by a tear seam in two areas. This tear seam may be the tear seam connecting the tension member to the second shell, or it may be a tear seam other than this. In this way, the force which acts on filling the second gas space to the tear seam, which connects the tension element with the second shell, is increased.

A further advantage of the embodiment of the adaptive ventilation device according to the invention is that the retaining element can be arranged both inside and outside the first gas space.

Further preferred embodiments will become apparent from the other dependent claims and from the embodiments now shown in more detail with reference to figures.

1 An embodiment of a gas bag module according to the invention in a schematic sectional view at rest,

2 this in 1 Shown after ignition of the gas generator and filling of the first gas space, which is enclosed by the airbag shell - here referred to as the first shell - but the ventilation device is still in a throttled state,

3 this in 2 Shown after operating a holding device, whereby the ventilation unit has passed into an unthrottled state,

4 a blank for producing a second shell,

5 the cut out 4 after two first processing steps,

6 this in 5 Shown after completion of the second shell,

7 this in 6 Shown after sewing a drawstring,

7a a section along the plane AA in 7 .

8th this in 7 Shown after arranging a second squib, so essentially the detail D from 2 in a plan view from the direction R,

9 this in 8th Shown after ignition of the primer and release of the tension band,

10 all components of the adaptive ventilation device in one of the state corresponding 2 .

11 this in 10 Shown with an alternative embodiment of the second shell,

12 An embodiment of the invention, in which the holding element is arranged outside of the first gas space,

13 this in 12 Shown in one of the 3 appropriate condition,

14 an embodiment of the invention which is similar to that in 12 shown embodiment, wherein the throttle element is formed as a single-layered flap,

15 this in 14 Shown in one of the 13 appropriate condition,

16 an embodiment which the the 14 is similar, but wherein the holding member is located within the first gas space, and

17 this in 16 Shown in one of the 15 appropriate condition.

The invention will first be described in detail with reference to an embodiment, then further embodiments will be briefly explained.

The 1 to 3 show a front airbag module, namely a driver's airbag module for installation in the hub region of a steering wheel. This is basically constructed as usual: It has a housing 20 with a housing wall 20b and a caseback 20a on, in which at rest here as the first shell 10 designated airbag shell is folded. This first case 10 encloses a first gas space 13 , The first shell 10 is by a retaining ring 26 at the bottom of the case 20a held. To fill the first gas space is a first inflator, namely a gas generator 30 , which in the embodiment shown by an opening 22 in the case back 20a inside the case 20 and thus in the first gas space 13 extends. This gas generator 30 has a propellant charge in the usual way 32 on, which by a first primer 34 is ignited as soon as this via an ignition cable 36 is ignited electrically. In the upper area of the gas generator 30 there are outlet openings for the generated gas; this area of the gas generator 30 is from a diffuser 24 spans. The connection between gas generator 30 and caseback 20a takes place in the embodiment shown via a flange 38 of the gas generator and damper 39 ,

At the first shell 10 is a ventilation unit 11 provided, over which the first gas space 13 can be vented. There may be a second, in particular a non-adaptive ventilation unit, in particular in the form of a hole in the first shell. This is not shown. The ventilation unit 11 has a ventilation opening 12 and a throttle element. In the first embodiment, this throttle element is a spout 14 which the ventilation opening 12 surrounds and whose one end is fixed to the first shell 10 connected is. This spout 14 has in its lateral surface at least one opening, preferably two openings 18 . 18 ' (as shown).

Furthermore, a tension element in the form of a drawstring 60 provided, whose first end 62 permanently on the first shell or a vehicle-mounted component, in particular the housing or an element connected thereto, is held. In the first embodiment shown, this first end 62 on the retaining ring 26 held. From the first end, the drawstring extends 60 through the two openings 18 . 18 ' the spout 14 to an actuatable Halteeleeinrichtung 40 with which the second end 64 of the drawstring 60 is connected in an initial state. Here is the drawstring 60 not rigid with the spout 14 connected. According to the definitions made here form the ventilation unit 11 , the drawstring 60 and the actuatable holding device 40 the adaptive ventilation device. In principle, it would also be possible to provide only one opening in the grommet, through which the drawstring 60 extends. In this case, it may be advantageous to form the region of the spout in which the aperture is located somewhat longer. This means that the spout would not be rotationally symmetric in this case.

When the first gas space 13 is filled with gas and the actuatable holding device 40 is in its initial state, so is the tieback 60 under tension, causing the spout to escape little or no gas through the ventilation opening ( 2 ). The force required for this purpose is distributed (generally in substantially half) to the two sections of the drawstring 60 that is the section between the first end 62 and the openings 18 . 18 ' and the section between the second end 64 and the openings 18 . 18 ' , It follows that also the force which is the second end of the drawstring 64 on the holding device 40 transmits, only about half of the total force is (pulley principle). Will the actuated holding device 40 actuated, it releases the tension element (here namely the second end of the tension element) and with the expanded first shell 10 then go the ventilation unit 11 (that is, the spout 14 ) from a first, namely a throttled, in a second, namely an unthrottled, state over, since the spout then by the first Gas space prevailing overpressure is put outwards ( 3 ).

The adaptive holding device 40 is constructed in the illustrated embodiment as follows: It is a second primer 48 provided, from which also an ignition cable, namely the ignition cable 50 , extends. The second primer 48 serves as a gas source of the actuatable holding device 40 , Furthermore, a second shell 42 provided, which a second gas space 43 encloses. This second gas space 43 is in flow communication with the gas source, which is achieved in the embodiment shown in that the second squib 48 at least partially included in the second gas space. It would also be possible, for example, to provide a gas supply element in the form of a tube. In any case, the second shell and gas source should form a gas-tight unit. The second shell 44 can consist of ordinary airbag fabric. Thus, the holding device forms 40 in a sense, a small gas bag module within the actual gas bag module. The second end 64 of the band 60 is so with the second shell 42 sewed that seam, namely the tear seam 49 , two layers of the second shell 42 sews. There are thus sections of three layers, namely the second end 64 of the drawstring 60 , as well as two layers of the second shell 42 , This will be repeated later with reference to the 7a see better. On the exact structure of the second shell 42 and on their connection with the drawstring 60 will be later with reference to the 4 to 8th again received.

Will now be the gas generator 30 ignited, gas flows into the first gas space 13 and the first shell 10 expands in the usual way. Here, the tension band spans 60 , causing the spout 14 is contracted and no, or little gas through the ventilation opening 12 can escape, so that the ventilation device is in a first, throttled state ( 2 ).

Will now the second primer 48 ignited, the gas generated by it fills the second gas space 43 , creating the second shell 42 expanded, but remains closed. This expansion makes the tear seam 49 torn and thus the second end 64 of the drawstring 60 from the second shell 42 separated. This allows the tape 60 no more pulling forces and the grommet 14 is pushed outward by the pressure prevailing in the first gas space, whereby the ventilation opening 12 is released and the ventilation device and thus the spout 14 in a second, namely an unthrottled state passes. The second shell 42 remains, as already mentioned, closed, leaving the second primer 48 and the gas produced by it can not interact with other elements of the gas bag module ( 3 ).

It will now be the concrete structure of the actuatable holding device 40 described, wherein the structure of the second shell will first be described by their preparation. The second shell 42 has two layers, namely a first layer 42a and a second location 42b , on (see later 7a ). These two layers may consist of two separate blanks, but it is preferable that they are made from a single blank 41 be obtained by wrinkles.

In a first process step, the blank 41 folded symmetrically so that the two layers 42a . 42b be formed. Subsequently, a permanent seam 47 arranged, which has a second gas space 43 encloses, with an opening 46 remains free. The permanent seam 47 forms the permanent edge connection of the second gas space 43 It would also be possible for the fold line to form a portion of this permanent edge connection (this possibility is not shown). In the next step ( 6 ) is a tear seam, which as a second tear seam 80 is designated arranged. Preferably, the second tear seam goes 80 (as shown) from the permanent edge joint (here the permanent seam 47 ) or cut them. In this case, it is particularly preferable (this is also shown) that the two starting points of the second tear seam (or their intersections with the permanent seam 47 ) are adjacent to the opening. Thus divides the second tear seam 80 the second gas space 43 in a first area 43a and a second area 43b , where the first area 43a in direct connection to the opening 46 stands and the second area 43b through the second tear seam 80 from the opening 46 is disconnected.

Now this will serve as a control tieback 60 by means of at least a first tear seam 49 - Here are three first tear seams 49 provided - with the second shell 42 sewn, with the first tear seam 49 or the first tear seams 49 the second gas space 43 , here the first area 43a of the second gas space 43 pierced, as this particular in 7a you can see. The first tear seam 49 or the first tear seams 49 can basically extend over the entire width of the two layers of the second shell, but they do not have to, as shown. Because the second tear seam 80 the drawstring 60 not with the second shell 42 should connect, the production order shown is preferred, although not mandatory.

Now the second gas chamber 43 still connected to the associated gas source. This gas source is in the illustrated embodiment by a second squib 48 formed, which themselves is completely located in the second gas space, or, as shown, protrudes into this. Alternatively, it would also be possible to provide a gas conducting element in the form of a tube which connects the gas source to the second gas space 43 combines. After completion of this assembly step, the second gas space should 43 (ie here the first area 43a of the second gas space 43 ) be closed gas-tight as possible, this can for example by placing a clamp or by gluing the second squib 48 in the opening 46 respectively. A clamping of the opening area of the second shell 42 between second primer and housing 20 by suitable shaping of the primer, housing and opening area of the second casing (eg with primer clipped into the casing) is also possible. This also applies if a Gaszuführrohr is provided. In principle, it would also be possible a second primer completely in the second gas space 43 arrange so that only the second ignition cable 50 through the opening 46 pass. In this case, there would even be the possibility of opening 46 to close by a seam.

The 9 shows the situation after ignition of the second squib 48 and release of the drawstring 60 , Here, by the gas of the second squib (or other gas source) first, the first area 43a of the second gas space 43 filled, which here initially creates a fairly high pressure, which tearing the first tear seam 49 and then tearing the second tear seam 80 leads. It is preferable that the two aforementioned tear seams 49 . 80 are coordinated with each other so that the first tear seam 49 before the second tear seam 80 breaks. After breaking the second tear seam 80 unite the first area 43a and the second area 43b to the common second gas space 43 , which then receives all the gas from the gas source, so that this is not in the first gas space 13 escapes. The second tear seam 80 Relieves hereby also the permanent edge connection (the permanent seam 47 ), because the force acting on them is reduced. It is essential, however, above all, that initially a reduced volume of the second gas space is made available, so that the first tear seam 49 acting force is maximized. It does not always have to be imperative that the second tear seam 80 the two areas 43a . 43b of the second gas space 43 However, this is generally preferable because it gives the maximum effect. Furthermore, the second tear seam does not necessarily have to be destroyed when the second gas space is filled. Depending on the tolerance position of the parameters which influence the pressure within the second gas space, it may also happen that the second tear seam 80 remains completely closed. Parameters that affect the (over) pressure are z. For example: temperature, gas space volume tolerances due to the sewing process, gas source tolerances and air pressure (weather and altitude).

In principle, it would also be possible to weave the second sheath in one piece (OPW), so that the edge joint is an integral part of the second sheath. It should also be emphasized at this point that the edge connection could also be produced by welding or gluing, with sewing being generally preferred.

The 10 again shows the just described adaptive ventilation device. The 11 shows an alternative embodiment in which the subdivision of the second gas space into two areas by the second tear seam 49 done, which is also possible.

It is at this point to emphasize that the subdivision of the second gas space 43 Although preferred in two areas, it is not mandatory. Furthermore, it should be emphasized that other actuatable holding devices, for example, such as those in the US 6,648,371 B2 are described, can be used in the context of the present invention. However, the use of a second shell holding unit (as described above) is preferred. The above also applies to the alternative embodiments now described:
As in the 12 and 13 shown, the actuatable holding device 40 also outside the first gas space 13 be arranged so that the throttle element, here the spout 14 , also in the first state (initial state - 12 ) outside the first gas space 13 located. Due to the construction according to the invention of the adaptive ventilation device, a good gas-tightness in the initial state is also given in this case. An advantage over the first embodiment is that the spout is in transition from the first, throttled state ( 12 ) in the second, unthrottled state ( 13 ) not through the ventilation opening 12 must pass through. Otherwise the function is as described above. As mentioned earlier, the first end 62 of the drawstring 60 also with the airbag cover (first cover 10 ), in particular sewn, as also shown.

In principle, it is also possible, instead of a spout a single-layered rag 16 use as a throttle element. This is possible both when the holding device is outside the first gas space ( 14 and 15 ), So even if the holding device within the first gas space 13 located ( 16 and 17 ). In most cases, with a spout, however, a better throttling can be achieved.

LIST OF REFERENCE NUMBERS

10

first shell

11

ventilation unit

12

vent

13

first gas space

14

spout

16

cloth

18, 18 '

perforation

20

casing

20a

caseback

20b

housing wall

22

opening

24

diffuser

26

retaining ring

30

inflator

32

propellant

34

first primer

36

Ignition cable of the gas generator

38

flange

39

damper

40

holder

41, 41 '

cut

42

second shell

42a

first location

42b

second location

43

second gas space

43a

first area

43b

second area

46

opening

47

permanent seam

48

second primer

49

first tear seam

50

Ignition cable of the second primer

60

tieback

62

first end

64

second end

70

perforation

80

second tear seam

Claims (8)

Airbag unit for a motor vehicle having a first gas space ( 13 ) enclosing first envelope ( 10 ), the first envelope ( 10 ) at least one ventilation opening ( 12 ), one with the first shell ( 10 ) connected throttle element, which the gas flow through the at least one ventilation opening ( 12 ) throttles more in a first state than in a second state, one from a first end ( 62 ) to a second end ( 64 ) extending tension element ( 60 ), which is connected at least in the first state with the throttle element and which, when it is under tension, the throttle element holds in its first state, and an operable holding device ( 40 ), which the tension element ( 60 ) connects in an initial state with a vehicle-fixed component and which the tension element ( 60 ) in an actuated state, the second end ( 64 ) of the tension element ( 60 ) in the initial state with the holding device ( 40 ), characterized in that the first end ( 62 ) of the tension element ( 60 ) with the first shell ( 10 ), with the vehicle-fixed component or with another vehicle-fixed component is connected and that the throttle element at least one opening ( 18 . 18 ' ), through which the tension element ( 60 ) extends at least in the first state, so that the tension element ( 60 ) divided in the first state into two sections and thus a kind of pulley is formed. Airbag unit according to claim 1, characterized in that the holding device ( 40 ) a second gas space ( 43 ) enclosing second envelope ( 42 ), with which the second end ( 64 ) of the tension element ( 60 ) in the initial state by means of at least one first tear seam ( 49 ), wherein a gas source for filling the second gas space ( 43 ) is provided. Airbag unit according to claim 2, characterized in that the second gas space ( 43 ) in the initial state by a tear seam in at least two areas ( 43a . 43b ) is divided. Airbag unit according to one of the preceding claims, characterized in that the throttle element has a nozzle extending from a first to a second end ( 14 ) whose first end is about the ventilation opening ( 12 ) around with the first shell ( 10 ) connected is. Airbag unit according to claim 4, characterized in that the grommet ( 14 ) two openings ( 18 . 18 ' ) in its lateral surface through which the tension element ( 60 ) extends in the first state. Airbag unit according to one of claims 1 to 3, characterized in that the throttle element with a first shell ( 10 ) associated flaps ( 16 ). Airbag unit according to one of the preceding claims, characterized in that the holding device ( 40 ) within the first gas space ( 13 ) is arranged. Airbag unit according to one of claims 1 to 6, characterized in that the holding device ( 40 ) outside the first gas space ( 13 ) is arranged.

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