Airbag module with wrapped tether

Abstract

An airbag module comprising an airbag cushion having an impact area, a structure to which the airbag cushion is attached, and a tether (30) having a first end (31) attached to the impact area by a first connection and a second end (32) attached to the structure or the airbag cushion in an area other than the impact area. The tether (30) is made from a flat tether element extending from a first end forming the first end (31) of the tether (30) to a second end forming the second end (32) of the tether (30). To obtain a relatively flat impact area and to avoid force peaks, at least a first section of the tether element extending from the first end is rolled to form a rolled section (35) of the tether (30).

Description

[Technical Field]

[0001] The invention relates to an airbag module according to the preamble of claim 1.

[0002] The present invention is particularly directed to driver airbag modules, but is also applicable to other types of airbag modules, particularly other types of front airbag modules such as passenger airbag modules. [Background technology]

[0003] In the prior art, airbag modules are known that comprise an airbag cushion having an impact area, a structure (in particular a housing) to which the airbag cushion is attached, and a tether inside the airbag cushion. The tether has a first end that is attached to the impact area of ​​the airbag cushion by a first connection (usually a seam) and a second end that is attached to the structure in a releasable / detachable manner so that the deployment depth of the airbag cushion can be controlled. In the simplest case, the tether is in the form of a single flat strap.

[0004] From general publication WO 2018 / 84479(A1) an airbag module is known in which the tether is "split" so that the first end has multiple end sections, each of which is connected to the impact area. A similar concept is described in application publication 2009-154655A1. This structure distributes the tether's pulling force over a wider area of ​​the impact area. Summary of the Invention

[0005] Starting from this prior art, the object of the present invention is to improve upon the typical airbag module that comprises a tether attached to the impact area of ​​the airbag cushion.

[0006] This problem is solved by an airbag module having the features of claim 1.

[0007] Although splitting the tether into multiple end sections has been found to provide improvements, there remains a need for further improvements, particularly in terms of obtaining a relatively flat impact area and avoiding force peaks.

[0008] As is commonly known, a tether is made from a flat tether element that extends from a first end forming a first end of the tether to a second end forming a second end of the tether, and in order to achieve uniform force transmission between the tether and the impact area, at least a first section of the tether element extending from the first end is coiled to form a coiled section of the tether.

[0009] By this means, the first connection is typically non-linear or curvilinear so that the force transmission is two-dimensional, rather than point-like or linear. This provides the desired even force distribution and relatively flat impact area, even though the tether element from which the tether is made is a flat piece of material.

[0010] The advantages of the present invention are greatest when the first connecting portion is closed, which is usually an ellipse or, more particularly, a circle. In such a situation, the connecting portion is in fact closed, i.e., it defines at least one closed area.

[0011] To save material, weight, and packaging space, it is preferred that the first section of the tether element widens, especially toward the first end, so that the first section of the tether element has an essentially fan-shaped configuration. In this case, the first section of the tether is conical in shape, and, as mentioned, the first connection portion is elliptical, e.g., circular. This shape provides ideal force distribution.

[0012] As described, the second end of the tether is typically connected to a structure, such as a housing or another area of ​​the airbag cushion. In most cases, this connection consumes a lot of space, which is a disadvantage, so it is typically preferred for the tether to additionally include an unwound section extending from the second end to the wound section. This additionally makes it easier to fold the tether and guide it, for example, through a hole in the airbag cushion.

[0013] This unwound section of the tether is made from a second section of the tether element extending between the second end of the tether element and the first section, and this second section preferably has a substantially constant width.

[0014] To minimize the assembly (sewing) step, the tether element can be one piece, but to minimize the area of ​​wasted material, it may also be preferable for a first section of the tether element to be made from a first cut portion, a second section of the tether element to be made from a second cut portion, and the first and second cut portions attached to each other to form the tether element.

[0015] To prevent uneven gas distribution within the airbag cushion, the tether element (particularly the first section thereof) preferably includes at least one hole that provides a passageway for inflation gas within the tether.

[0016] To further improve the even force distribution, it may be preferable for the two lateral edges of the tether element to be at least partially connected to each other to form a closed generating surface for the wound section of the tether.

[0017] It should be noted that although the present invention is particularly useful for so-called dual depth airbag modules, meaning that the tether is attached to a structure in such a way that the second end can be released from the structure or the tether can be broken near the second end so that at least a major portion of the tether can be released from the structure or other areas of the airbag cushion, other uses for the tether of the present invention are also contemplated. For example, the second end of the tether can be permanently connected to the structure or airbag cushion.

[0018] In a particularly preferred embodiment, an additional tether having a tether distal end extends from the tether, and at least one of the tether distal end of the additional tether and the second end of the tether is releasably / breakably connected to the structure such that the impact region of the airbag cushion remains tethered at both deployment depths. [Brief explanation of the drawings]

[0019] The invention will now be described by way of preferred embodiments with reference to the drawings, in which: [Figure 1] FIG. 1 shows all the cuts from which the airbag cushion and tethers are made according to the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view of the cut section of FIG. 1 sewn together to form a precursor assembly. [Figure 3] FIG. 3 is the view shown in FIG. 2 after the airbag cushion has been turned over so that the airbag cushion and tether are connected to the housing. [Figure 4] FIG. 4 is a perspective view of the tether shown in FIGS. 2 and 3. [Figure 5] FIG. 5 shows the completed airbag module of the representation according to FIG. 3 with the airbag deployed to a first deployment depth. [Figure 6]6 illustrates the configuration shown in FIG. 5 after a main portion of the tether has been released from the housing and the tether has been threaded and cut near its second end so that the airbag cushion is deployed to a second deployment depth. [Figure 7] 7 illustrates the tether element of FIG. 1 and a tether element to which an additional tether has been sewn to form a tether assembly precursor. [Figure 8] FIG. 8 is a second embodiment of the present invention using a tether assembly made from the tether assembly precursor of FIG. 7 in a representation according to FIG. [Figure 9] 9 shows the second embodiment shown in FIG. 8 in a second state according to FIG. 6. DETAILED DESCRIPTION OF THE INVENTION

[0020] 1 shows all of the cutouts for the airbag cushion as well as the tether elements, which in this embodiment are in the form of one-piece cutouts. All of the cutouts can be made from conventional airbag materials, particularly woven plastic materials.

[0021] It should be noted that, of course, additional cuts, such as reinforcing layers, may be provided as is known in the art, but such additional elements are not shown as they are not necessary for understanding the present invention.

[0022] The airbag cushion consists of three sections that form the impact areas: a front panel 12, a side panel 14, and a back panel 16. In the embodiment shown, the front panel 12 and the back panel 16 are both circular and have the same diameter. The difference between these two panels is that the back panel 16 includes multiple holes: a central hole 16c, attachment holes 16a around the central hole 16c, and holes 16b for tethers.

[0023] The tether element 20 in this embodiment has two sections: a first section 25 having a sector shape and a second section 26 having a substantially rectangular shape and extending from the second end 22 of the tether element to the first section 25. The first section 25 widens toward the first end 21 of the tether element 20 (having the shape of an arc of a circle), which is in the form of a section of a circle. Starting from the second section 26, the lateral edges 25a and 25b of the first section 25 extend to the first end 21 of the tether element 20. A hole 28 is provided in the first section 25. In other embodiments, the first end 21 can have a different curved shape, such as a non-circular elliptical arc shape, such that the first section has the shape of an elliptical section, rather than the shape of an arc of a circle.

[0024] In the assembly step, tether element 20 is formed into tether 30 by wrapping first section 25 around the longitudinal direction (X direction) to form conically wrapped section 35 of tether 30, such that first end 21 of tether element 20 forms circular first end 31 of tether 30 (see particularly FIG. 4 ). This first end 31 is connected (typically sewn) to front panel 12 by first connection 51, which, of course, also forms a circle. Asymmetric embodiments are contemplated in which first end 31 and first connection 51 are not circular but rather non-circular ellipses. While closing the first connection is not strictly required, it is preferred in either case. Second section 26 of tether element 20 remains unwound, forming unwound section 36 of tether 30.

[0025] After this assembly step, side panel 14 is attached to front panel 12 by joints (seams) 40, and back panel 16 is attached to side panel 14 by joints (seams) 42. The result of these assembly steps is shown diagrammatically in FIG.

[0026] Now, the airbag cushion 10, consisting of the front panel 12, side panels 14, and back panel 16, is turned inside out and the unwrapped section 36 of the tether 30 is tucked through the tether hole 16b in the back panel 16 (FIG. 3).

[0027] The already mentioned Figure 4 shows the tether 30 again, but now in a schematic perspective view. The conical shape of the wound section 35 can be seen, together with the circular shape of its first end 31. In the embodiment shown, the lateral edges 25a and 25b are not connected to one another, although this is also possible. Naturally, they can overlap, but are not connected to one another. In the embodiment shown, there is a slight gap between these two lateral edges 25a and 25b. The holes 28 in the tether element 20 are now located on the resulting surface of the cone and form passages 38 for the inflation gas.

[0028] FIG. 5 shows an assembly consisting of an airbag cushion 10 and a tether 30 attached to a structural element, namely, a housing 60, to form an airbag module. In the state shown in FIG. 5, the airbag cushion deploys after a gas generator 62 in the airbag module is triggered. The second end 32 of the tether 30 can be seen attached to a mounting unit 64 on the housing 60 so that the tether 30 is under tension, thus limiting the deployment depth (X direction) of the airbag cushion 10. This mounting unit 64 includes a permanent attachment feature 66 and a cutter 68 designed to cut through the unwound section 36 of the tether 30 near the second end 32 of the tether 30 so that a main portion of the tether 30 is releasably connected to the housing 60. Of course, other types of releasable tether attachments can also be used, such as those described in WO 2014 / 029473 A1. In another alternative, the second end 32 of the tether 30 can be released or slid from the anchor point by an actuatable mechanism.

[0029] As long as the tether remains connected to the housing without being severed, it remains under tension during airbag deployment, thus limiting the deployment depth to the first deployment depth. After triggering cutter 68 (or otherwise severing the tether or a major portion thereof from the housing), the tether loses its tension and reaches the second deployment depth (FIG. 6). Because unwrapped section 36 is single-layered, it can be easily severed and threaded through the holes in the housing and hole 16b in the airbag cushion.

[0030] As long as the tether is under tension, its entire circular second end transmits force to the impact area (front panel 12), resulting in the desired even force distribution and a relatively flat impact surface 12a.

[0031] 7 shows a tether assembly precursor of a second embodiment of the present invention. This tether assembly precursor consists of the tether element 20 described above and an additional tether 70, which may be in the form of, for example, a rope or strap (a rope is preferred in most cases). A tether end 71 is attached (e.g., sewn) to the tether element 20 by a tether-to-tether connection 74 (e.g., a seam), and the additional tether extends therefrom to a distal end 72. The tether-to-tether connection 74 is preferably located in the second section 26 near the first section 25.

[0032] The next assembly steps are as described in relation to the first embodiment, with the following exceptions: the second end 32 of the tether 30 is attached (typically by sewing) to the airbag cushion 10 by a second connection 52. This second connection 52 is typically near the central hole 16c where at least one reinforcing layer (not shown) is provided, and is preferably in an area that will experience minimal movement during inflation of the cushion 10. The tether distal end 72 of the additional tether 70 is connected to an attachment unit.

[0033] This geometry is selected so that when the cutter 68 is not triggered and the airbag cushion 10 deploys, the additional tether 70 is under tension, but the section of the tether 30 extending between the tether-tether connection 74 and the second connection 52 is not under tension, so that the airbag cushion 10 deploys to the first deployment depth (FIG. 8).

[0034] After actuating the cutter 68, the additional tether 70 loses its tension and the airbag cushion deploys to a second deployment depth, which, in contrast to the first embodiment, is limited by the tether 30 because its second end 32 remains connected to the back panel 16 of the airbag cushion 10, providing an essentially flat impact surface 12a at both deployment depths (FIG. 9).

[0035] As with the first embodiment, the breakable or detachable connection of the additional tether 70 to the housing (structure) may be obtained via other types of releasable attachment means; for example, the tether distal end 72 of the additional tether 70 may be released or slid from the anchor point by an actuatable mechanism. Furthermore, it will generally be possible (even if not generally preferred) to change the roles of the additional tether and the unwound section of the tether. Finally, it will generally be possible to releasably attach both the additional tether and the unwound section to the structure so that three deployment depths of the airbag cushion can be reached. [Explanation of symbols]

[0036] 10 Airbag cushion 12 Impact Area / Front Panel 12a Impact Surface 14 Side Panel 16 Back Panel 16a mounting hole 16b Tether hole 20 Tether Elements 21 first end 22 second end 25 Unfold the first section of the tether element (having a sector shape) 25a first lateral edge of first section 25b second lateral edge of first section 26 Second Section 28 holes 30 Tether 31 first end 32 Second end 35 Cone-shaped rolled section of tether 36 Unwrapped Sections 38 Passage 40 Connection between front panel and side panel 42 Connection between back panel and side panel 51 First connection part 52 Second connection 60 Housing 62 Gas Generator 64 Mounting Unit 66 Permanent Mounting Features 68 Cutter 70 additional tether sections (rope) 71 Tether end of additional tether 72 Tether distal end of additional tether 74 Connection for connecting additional tethers to the tether

Claims

1. An airbag module comprising: an airbag cushion (10) having an impact area (12); a structure to which the airbag cushion (10) is attached; a tether (30) having a first end (31) attached to the impact area (12) by a first connection (51) and a second end (32) attached to the structure or the airbag cushion in an area other than the impact area (12), the tether (30) being made from a flat tether element (20) extending from a first end (21) forming the first end (31) of the tether to a second end (22) forming the second end (32) of the tether (30); At least a first section (25) of the tether element (20) extending from the first end (21) is wound to form a wound section (35) of the tether (30); the first section (25) of the tether element (20) widens towards the first end (21); 1. An airbag module, wherein the tether (30) additionally comprises an unwound section (36) extending between the second end (32) and the wound section (35).

2. An airbag module, an airbag cushion (10) having an impact area (12); a structure to which the airbag cushion (10) is attached; a tether (30) having a first end (31) attached to the impact area (12) by a first connection (51) and a second end (32) attached to the structure or the airbag cushion in an area other than the impact area (12), the tether (30) being made from a flat tether element (20) extending from a first end (21) forming the first end (31) of the tether to a second end (22) forming the second end (32) of the tether (30); At least a first section (25) of the tether element (20) extending from the first end (21) is wound to form a wound section (35) of the tether (30); 1. An airbag module comprising: an airbag module having a tether (30) attached to a structure in such a manner that the second end (32) can be released from the structure or the tether can be broken near the second end (32) so that at least a major portion of the tether (30) can be released from the structure.

3. 3. An airbag module according to claim 1 or 2, characterized in that the first connection (51) is non-linear.

4. 4. Airbag module according to claim 3, characterized in that the first connection (51) is closed.

5. 2. The airbag module according to claim 1, wherein the first section (25) of the tether element (20) has an essentially sectorial shape.

6. 6. An airbag module according to claim 5, characterized in that the rolled section (35) of the tether (30) is conical in shape, such that the first connection portion (51) is elliptical, in particular circular.

7. 2. The airbag module of claim 1, wherein the tether element (20) further comprises a second section (26) extending between the second end (22) and the first section (25) and forming the unwound section (35) of the tether (30).

8. 8. The airbag module of claim 7, wherein said second section (26) has a substantially constant width.

9. 8. The airbag module of claim 7, wherein the unwound section of the tether is substantially flat when the airbag cushion is fully deployed and the tether is at least indirectly attached to the structure or the airbag cushion via its second end such that the tether is under tension.

10. 3. An airbag module according to claim 1 or 2, characterized in that the tether element (20) is of one piece type.

11. 8. The airbag module of claim 7, wherein the first section of the tether element (20) is made from a first cut and the second section of the tether element is made from a second cut, the first and second cuts being attached to one another to form the tether element.

12. 3. An airbag module according to claim 1 or 2, characterized in that the tether element (20) comprises at least one hole (28) for forming a passage (38) for inflation gas within the tether.

13. 3. An airbag module according to claim 1 or 2, characterized in that two lateral edges (25a, 25b) of the tether element (20) are at least partially connected to each other to form a closed generating surface of the wrapped section (35) of the tether (30).

14. 3. The airbag module of claim 2, wherein an additional tether (70) extends from the tether (30), the additional tether having a tether distal end (72) and permanently connected to the structure or the airbag cushion (10).

15. an additional tether (70) extending from said tether (30), said additional tether having a tether distal end (72); the additional tether (70) is attached to the structure in such a way that the tether distal end (72) can be released from the structure or the additional tether (70) can be broken near the tether distal end (72) such that at least a major portion of the additional tether (70) is releasable from the structure; 3. The airbag module according to claim 1 or 2, characterized in that the second end (32) of the tether (30) is connected, preferably in a permanent manner, to the structure or to the airbag cushion (10).

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