Airbag unit with active ventilation arrangement

Abstract

An airbag unit is described. This airbag unit comprises an airbag having an outer skin (50), an inflator for inflating said outer skin (50), and a structure comprising an accommodation for the airbag, wherein the un-deployed airbag is accommodated in said accommodation. For ventilation of the outer skin of the airbag, an active ventilation arrangement comprising a first state and an activated second state is additionally provided. This active ventilation arrangement comprises a hole (52) in the outer skin (50), a covering element (10) having an initial state, in which it covers the hole (52) in the outer skin when the active ventilation arrangement is in its first state, a tether element extending from a first end section (40a) being attached to the covering element (10) to a second end section, and an holding feature to which the second end section of the tether element is attached. This holding feature comprising an active release arrangement that releases or destroys the tether element upon activation. When the outer skin (50) is fully deployed and the second end section of the tether element (40) is not released or destroyed, the tether element is under tension and holds the covering element (10) in its initial state, such that the active ventilation arrangement is in its first state. In order to provide an active ventilation arrangement which has only little or no leakage in the initial first state and provides strong ventilation in the activated second state, the following measures are taken: The covering element (10) is attached to the outer surface of the outer skin (50) by means of a connection (54) having a first section (55) and a second section (56). Further, a free edge (11) of the covering element (10) extends between the two sections (55, 56) of the connection (54). Finally, the covering element (10) is folded along at least a first pair of folding lines such that it comprises in its initial state a first side portion (14), a main portion (12) and at least one first sandwiched portion sandwiched between the first side portion (14) and the main portion (12), wherein the first section (55) of the connection (54) connects the first side portion (14) to the outer skin (50) (Fig. 16).

Description

[0001] Airbag unit with active ventilation arrangement

[0002] Description

[0003] The invention relates to an airbag unit comprising an active ventilation arrangement according to the preamble of claim 1 .

[0004] Airbag units with active ventilation arrangements are known in the art. As every airbag unit, such an airbag unit comprises an airbag having an outer skin, an inflator for inflating said outer skin and an accommodation for that airbag (usually a housing). An active ventilation arrangement of the generic type comprises an initial first state and an activated second state in such a way that in the activated second state, the ventilation is stronger than in the initial first state. Usually it is intended that in the initial first state no gas is ventilated and that in the second state the ventilation arrangement has its full ventilation capacity.

[0005] An active ventilation arrangement of the generic type comprises a hole in the outer skin and a covering element having an initial state in which it covers the hole in the outer skin (when the active ventilation arrangement is in its initial first state), a tether element extending from a first end section being attached to the covering element to the second end section and a holding feature to which the second end section of the tether element is attached. This holding feature comprises an active release arrangement that releases or destroys the tether element upon activation. Just to give one example: Such a holding feature can comprise a cutter.

[0006] The length of the tether element is chosen such that when the outer skin is fully deployed and the tether element is intact, the tether element is under tension and holds the covering element in its initial state such that it covers the hole in the outer skin. When the release arrangement is activated, the tether element is de-attached or destroyed, such that it loses its tension and the covering element moves completely or partially away from the hole in the outer skin due to the pressure inside the outer skin, such that ventilation can take place.

[0007] Especially for active ventilation arrangements that are used as additional ventilation for several load cases which might include “emergency ventilations” (for example when a so-called out of position scenario occurs), it is often desired to provide strong ventilation, meaning that the hole in the outer skin is rather large. On the other hand it is usually desired that in the first initial state there is no or only very little leakage meaning that the covering element must close the hole in the outer skin tightly.

[0008] Starting from this prior art, it is an object of the invention to provide an active ventilation arrangement which has only little or no leakage in the initial first state and provides strong ventilation in the activated second state.

[0009] This task is solved by an airbag unit having the features of claim 1 .

[0010] According to the invention, the covering element is attached to the outer surface of the outer skin by means of a connection having a first connection section and a second connection section, such that a free edge of the covering element extends between the two connection sections. Further, the covering element is folded along at least a first pair of folding lines such that it comprises in its initial state a first side portion, a main portion and at least one first sandwiched portion sandwiched between the first side portion and the main portion. The first connection section connects the first side portion to the outer skin. For this reason, a section of the first side portion preferably extends over the main portion, such that it can be connected - especially sewn - to the outer skin by means of the first connection section without also sewing the main portion.

[0011] In other words: A Z-folded part of the covering element is provided, such that the covering element is flat in its initial state and unfolds to a sort of hood when the active ventilation arrangement is activated. Due to this deployment to a sort of hood, the covering element can be attached to the outer skin by a permanent connection which does only not connect the free edge of the covering element to the outer skin neither directly nor indirectly such that the covering element and the hole covered by the covering element can have a large size. It is generally desired that the hood provides a large free cross-section and thus it is preferred that the covering element is in its initial state symmetrical and is additionally folded along a second pair of folding lines such that in its initial state it further comprises a second sandwiched portion sandwiched between the main portion and a second side portion. This second side portion is connected to the outer skin by means of the second connection section.

[0012] Preferably, the first sandwiched portion and the second sandwiched portion overlap in the initial state. This helps to improve the gas-tightness in the initial state and additionally, this makes the “deployed hood” large.

[0013] It is further preferred that the first end section of the tether element is attached to the outer surface of the main portion, such that the tether extends over - and thus from - the free edge of covering element when the covering element is in its initial state. This helps to press the free edge towards the outer skin, especially when the tether element extends into the interior of the outer skin (the gas space).

[0014] In order to provide a secure attachment of the tether element to the covering element, at least a section of the first end section of the tether element can be sandwiched between the outer surface of the main portion and an additional attachment element.

[0015] As has been mentioned above, it is often preferred that the tether element extends into the interior of the outer skin. In order to provide a sub-assembly that can easily be attached to the outer skin, a guiding element for the tether element can be provided, said guiding element spanning over a section of the hole in the outer skin and comprising at least one opening (usually a hole) through which the tether element extends, such that this at least one opening defines a guiding feature for the tether element

[0016] The guiding element and the covering element can be made from a joint cutting, such that the number of parts is reduced. In other embodiments, another type of guiding feature for the tether element can be provided, for example in form of a loop, a flap or a tunnel which is attached to a tether guiding element or directly to the outer skin. Such kind of a guiding feature can especially be used if the whole tether element is located on the outside of the outer skin. In order to hold the free edge tight to the outer skin (or to a tether guiding element as will be described later), it is usually preferred that this guiding feature is located in close proximity to the free edge of the covering element in its initial state.

[0017] In order to further improve the gas-tightness in the initial state, the attachment element - or if no attachment element is used, the main portion of the covering element - can comprise a protrusion extending over the free edge of the main portion and being secured to the guiding element by means of a tear seam. This protrusion is preferably arranged in a symmetrical manner (meaning in the middle of the free edge). In case that no separate guiding element is used, this protrusion could also be connected to the outer skin by means of a tear seam. But generally, the use of a separate covering element is preferred.

[0018] Especially in case that such a protrusion is present, it can be preferred to design the tether element such that it comprises to strands that extend from the free edge left and right from the protrusion. A further advantage of such a two-stranded tether element is that it can be loop-shaped which can enhance its connection to the covering element.

[0019] In order to further improve the gas-tightness in the initial state, it can further be preferred that the free edge is formed at least in sections as a fold, such that at least one tucked-in portion extends from the free edge and a sort of self-sealing pouch is formed.

[0020] The invention will now be described by means of preferred embodiments in view of the figures. The figures show:

[0021] Figure 1 a schematic representation of the fully deployed airbag comprising an embodiment of the active ventilation arrangement according to one embodiment of the invention as well as a passenger sitting in front of this airbag, Figure 2 a cutting for a cover element,

[0022] Figure 3 an attachment element,

[0023] Figure 4 a tether element,

[0024] Figure 5 a tether guiding element,

[0025] Figure 6 the tether element of Figure 4 extending through holes in the tether guiding element,

[0026] Figure 7 the cutting of Figure 2, the tether element of Figure 4 and the attachment element of Figure 3, wherein the first end section of the tether element is sewn to a main portion of the cutting for the cover element with the aid of the attachment element of Figure 3,

[0027] Figure 8 the sub-assembly of Figure 7 being turned around,

[0028] Figure 9 the sub-assembly of Figure 8, after the to-be-tucked-in border portions have been folded,

[0029] Figure 10 the sub-assembly of Figure 9 after a further folding step,

[0030] Figure 11 what is shown in Figure 10 after another folding step,

[0031] Figure 12 the sub-assembly of Figure 11 after another two folding steps symmetrical to the folding steps of Figure 10 and 1 1 ,

[0032] Figure 13 the sub-assembly of Figure 12 turned around,

[0033] Figure 13a a sectional view taken along line A-A in Figure 13, Figure 14 the sub-assembly of Figure 6 (the tether guiding element and the tether element, after the tether guiding element has been attached to the covering element shown in Figure 13),

[0034] Figure 15 a section of the outer skin of the airbag with a hole therein,

[0035] Figure 16 what is shown in Figure 15, after the assembly of Figure 14 has been sewn to the outer skin, and

[0036] Figure 17 a joint cutting for a covering element and a tether guiding element according to a second embodiment of the invention.

[0037] Figure 1 shows schematically an embodiment of the inventive airbag unit. As can be seen, this airbag unit is a passenger frontal airbag unit and this is also the most important embodiment of the invention. This airbag unit comprises a structure comprising an accommodation for the airbag, namely a housing 60, an inflator 62 inside the housing 60, an outer skin 50 of the airbag which is folded into the housing in the resting state of the airbag, and an active ventilation arrangement. This active ventilation arrangement comprises a hole in the outer skin of the airbag 50, a covering element 10 (which will be described in detail later), a tether element 40 and a holding feature 65 for this tether element 40, wherein this holding feature comprises an active release arrangement. This general setup is known in the prior art and the active ventilation arrangement has an initial first state in which the covering element covers the hole and blocks a ventilation through that hole and an activated second state in which a ventilation through the hole in the outer skin is provided, because the covering element does not cover it any longer. This is controlled by the tether element 40 that holds the covering element in its initial first state when the airbag is fully deployed and the tether element 40 is under tension (as shown in Figure 1 ). The first end section of this tether element is attached to the covering element and the second end section to the holding feature 65 and when the second end section is released or the tether element is partially destroyed by the release arrangement, the tether element loses its tension and the gas pressure can press the covering element away from the hole in the outer skin, such that gas can stream through the hole to the outside. The covering element 10 is thus attached to the outer surface of the outer skin. This concept is generally known.

[0038] In view of Figures 2 to 16 the structure of the covering element as well as the attachment of the tether element to the covering element and the attachment of the covering element to the outer skin are described by means of the production process.

[0039] Figure 2 shows a cutting 5 for a covering element 10. As can easily be seen from Figure 2, this cutting 5 is symmetrical along a middle axis (not shown) such that also the covering element folded from this cutting is also symmetrical.

[0040] This cutting 5 can be made from a standard airbag fabric material and comprises a plurality of portions being separated by folding lines which do not have to be physically present and which are indicated in Figure 2 by lines with patterns dash-dot-dot-dash. Those portions are: A main portion 12 which could also be denoted as “central portion”, on each side of the main portion a sandwiched portion 16, 16’ and next to each sandwiched portion 16, 16’ a side portion 14, 14'. The main portion 12 is “separated” from the sandwiched portions 16, 16' by the first folding lines 21 , 21 ’ and the sandwiched portions 16, 16’ are separated from the side portions 14, 14’ by the second folding lines 22, 22’. The main portion 12 is a rectangle and the sandwiched portions 16, 16’ are triangles. Along one end of each of those portions, a folding line 19 separates so-called “to be tucked-in border portions” 18 from the above described portions. As will be seen later, the folding line 19 defines the free edge of the covering element when it is completely folded and mounted (the free edge is the edge which is not connected to the outer skin of the airbag).

[0041] Figure 3 shows an attachment element 20 for a tether element which is intended to be sewn to the main portion 12. In this embodiment, the attachment element 20 has a basically semi-circular tether attachment portion 21 and a protrusion 22 extending from this tether attachment portion 21 , namely from its not curved edge.

[0042] Figure 4 shows a tether element extending from a first end section 40a to a second end section 40b. The tether element 40 is looped such that it comprises two strands and the first end section is in form of two end sections of strands. Figure 5 shows a tether guiding element 30 for the tether of Figure 4 which is substantially a rectangle made from a flexible flat material, like a typical airbag material with two holes 32 for the tether element provided therein.

[0043] Figure 6 shows the tether element 40 of Figure 4 with the two strands extending through the holes 42 of the tether guiding element 40. This is the outcome of the initial assembly step.

[0044] In a next step the first end section 40a of the tether element (meaning the two end sections of the strands) are sewn to the main portion 12 and the tether attachment portion 21 of the attachment element 20 in such a way that the first end section - or at least a part of the same - is sandwiched between the main portion 12 and the tether attachment portion 21 . First, the end sections of the strands are placed on the main portion 12 near the folding line 19 for the border portions. The tether attachment portion 21 is placed on top of the first end section 40a of the tether element in such a way, that the straight edge of the semi-circular tether attachment portion 21 is substantially flush with the folding line 19. Then, a seam 34 is applied.

[0045] In a next step, the so manufactured sub-assembly is turned around (Figure 8) and then, the to-be-tucked-in border portions 18 are tucked-in. This is shown in Figure 9. In the final assembly state, the tucked-in portions 18 form pouches that are open towards the gas space such that the overpressure inside the gas space expands the pouches and thus seals the free edge towards the structure it abuts.

[0046] In a next step (Figure 10) the cutting 5 is folded along one of the first folding lines, here the first folding line 21 and then again along the second folding line 22. The outcome of this is shown in Figure 1 1 .

[0047] The same is repeated for the first folding line 21 ’ and the second folding line 22’. The outcome of this is shown in Figure 12. The folding process is now finished and the outcome is now described in view of Figures 13 and 13a. Figure 13 shows the subassembly of Figure 12 turned around and 13a is a sectional view taken along line A-A in Figure 13. One can see a double Z-folded structure with the two side portions 14, 14’, the main portion 12 and the so-called sandwiched portions 16, 16’ extending between the side portions 14, 14’ and the main portion 12. One can see that the sandwiched portions 16, 16’ (and thus the side portions 14, 14’) overlap such that the so folded covering element 10 is in sections five-layered.

[0048] In a next step, the tether guiding element 20 (with the guided-through strands of the tether) is attached to the side portions 14, 14’ of the now folded covering element 10 by means of seams 34. One can see that the holes 32 through which the strands of the tether element extend are substantially flush with the free edge 11 of the now completely folded covering element 10.

[0049] Additionally, the protrusion 22 which extends from the tether attachment portion 21 and thus over the free edge 1 1 of the covering element 10 is sewn to the tether guiding element 30 by means of a tear seam 24.

[0050] The so created sub-assembly is sewn to the outer skin 50 of the airbag which shows a hole 52 such that this hole is covered by the sub-assembly comprising the covering element and the tether guiding element. A closed (O-shaped) connection seam 54 connecting the side portions 14, 14’ and the tether guiding element 30 to the outer skin 50 is applied, wherein this connection seam 54 comprises a first section 55 connecting the first side portion 14 of the covering element 10 to the outer skin and a second section 56 connecting the second side portion 14’ to the outer skin 50. The free edge 1 1 extends between the first section 55 and the second section 56. The tether element (the two strands of the tether) extend thus from the outside of the outer skin to the inside of the airbag and the second end section of the tether element is attached to the holding feature 65 (see Figure 1 ).

[0051] Because of the described structure, almost perfect gas tightness is achieved as long as the cover element is held by the tether element and / or the tear seam 24.

[0052] When the release arrangement is activated and the tether element loses its tension due to this event, the tear seam breaks due to the gas pressure inside the outer skin and the covering element unfolds such that strong ventilation is provided. Figure 17 shows a joint cutting 7 for the covering element 10 and the tether guiding element 30, such that the number of cuttings is reduced.

[0053] In an alternative embodiment, it would also be possible to guide the tether element on the outer surface of the outer skin. In this case, the tether element must be guided by a tunnel (which could even be a short tunnel) provided on the outer surface of the outer skin.

[0054] List of reference numbers

[0055] 5 cutting for cover element

[0056] 7 joint cutting for cover element and tether guiding element

[0057] 10 covering element

[0058] 11 free edge

[0059] 12 main portion (central portion)

[0060] 14, 14’ side portion

[0061] 16, 16’ sandwiched portion

[0062] 18 to be tucked-in border section

[0063] 19 folding lines of border sections

[0064] 21 , 21 ’ first folding line

[0065] 22, 22’ second folding line

[0066] 20 attachment element

[0067] 21 tether attachment portion

[0068] 22 protrusion

[0069] 24 tear seam connecting protrusion to tether guiding element

[0070] 30 tether guiding element

[0071] 32 hole for tether (opening)

[0072] 34 seam connecting tether guiding element to covering element

[0073] 40 tether element (tether)

[0074] 40a first end section

[0075] 40b second end section

[0076] 42 connecting seam connecting tether element to main portion

[0077] 50 outer skin of airbag

[0078] 52 hole in outer skin

[0079] 54 connection seam connecting covering element and tether guiding element to outer skin

[0080] 55 first section

[0081] 56 second section

[0082] 60 housing

[0083] 62 inflator

[0084] 65 holding feature with active release arrangement

Claims

Claims1 . Airbag unit comprising: an airbag having an outer skin (50), an inflator (62) for inflating said outer skin (50), a structure comprising an accommodation for the airbag, wherein the undeployed airbag is accommodated in said accommodation, an active ventilation arrangement comprising a first state and an activated second state, said active ventilation arrangement comprising: a hole (52) in the outer skin (50), a covering element (10) having an initial state, in which it covers the hole in the outer skin at least partially when the active ventilation arrangement is in its first state, a tether element (40) extending from a first end section (40a) being attached to the covering element (10) to a second end section (40b), a holding feature (65) to which the second end section (40b) of the tether element (40) is attached, said holding feature (65) comprising an active release arrangement, said active release arrangement releasing or destroying the tether element (40) upon activation, wherein, when the outer skin (50) is fully deployed and the second end section (40b) of the tether element (40) is not released or destroyed, the tether element (40) is under tension and holds the covering element (10) in its initial state, such that the active ventilation arrangement is in its first state, characterized in that the covering element (10) is attached to the outer surface of the outer skin (50) by means of a connection (54) having a first section (55) and a second section (56), a free edge (1 1 ) of the covering element (10) extends between the two sections (55, 56) of the connection (54), the covering element (10) is folded along at least a first pair of folding (21 , 22) lines such that it comprises in its initial state a first side portion (14), a mainportion (12) and at least one first sandwiched portion (16) sandwiched between the first side portion (14) and the main portion (12), and the first section (55) of the connection (54) connects the first side portion (14) to the outer skin (50).

2. Airbag unit according to claim 1 , characterized in that the covering element (10) is additionally folded along a second pair of folding lines (21 ’, 22’) such that in its initial state it further comprises a second sandwiched portion (16’) sandwiched between the main portion (12) and a second side portion (14’), wherein the second side portion (14’) is connected to the outer skin (50) by means of the second section (56) of the connection (54).

3. Airbag unit according to claim 1 , characterized in that the first sandwiched portion (16) and the second sandwiched portion (16’) overlap in the initial state.

4. Airbag unit according to any one of the preceding claims, characterized in that the first end section (40a) of the tether element (40) is attached to the outer surface of the main portion (12).

5. Airbag unit according to claim 4, characterized in that at least a section of the first end section (40a) of the tether element (40) is sandwiched between the outer surface of the main portion (12) and an attachment element (20).

6. Airbag unit according to any one of the preceding claims, characterized in that the tether element (40) extends from the free edge of the covering element.

7. Airbag unit according to any one of the preceding claims, characterized in that the tether element (40) comprises two strands which extend from the covering element (10).

8. Airbag unit according to any one of the preceding claims, characterized in that a guiding feature for the tether element (40) is provided, preferably in close proximity to the free edge (1 1 ) of the covering element (10).

9. Airbag unit according to claim 8, characterized in that the guiding feature comprises at least one opening (32) through which the tether element (40) extends into the gas space enclosed by the outer skin (50).

10. Airbag unit according to claims 8 or 9, characterized in that a guiding element (30) for the tether element (40) is provided, said guiding element (30) spanning over a section of the hole (52) in the outer skin (50) the guiding feature, such that the covering element (10) and the guiding element (30) together cover the hole (52) in the outer skin (50).1 1 . Airbag unit according to claim 10, characterized in that the guiding element (30) and the covering element (10) are made from a joint cutting (7).

12. Airbag unit according to claim 5 and to any one of claims 10 or 1 1 , characterized in that the attachment element (20) comprises a protrusion (22) extending over the free edge (11 ) of the covering element (10), said protrusion (22) being secured to the guiding element (30) by means of a tear seam (24).

13. Airbag according to any one of the preceding claims, characterized in that the free edge (11 ) is formed at least in sections as a fold (19), such that at least one tucked-in section (18) extends from the free edge.

14. Airbag unit according to any one of the preceding claims, characterized in that the connection (54) is U-shaped, or closed (O-shaped).

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