WO2019209950A1

WO2019209950A1 - A method and an apparatus for folding an airbag

Info

Publication number: WO2019209950A1
Application number: PCT/US2019/028912
Authority: WO
Inventors: Holger Maul
Original assignee: Key Safety Systems, Inc.
Priority date: 2018-04-26
Filing date: 2019-04-24
Publication date: 2019-10-31

Abstract

It is disclosed a method and an apparatus for folding an airbag (2). The method comprises the steps of providing an airbag (2) connected to an inflator (40), connecting the airbag (2) to a straightening ram (10), generating relative movement between the airbag (2) connected to the straightening ram (10) and a guide sleeve (18), the guide sleeve (18) being provided with a radial ram group (60), compressing axially the airbag (2) against an abutment surface (30) of the guide sleeve (18), compressing radially the airbag (2) by activating a radial ram group (60) until the radial dimensions of the airbag (2) are reduced; and pushing the straightening ram (10) in order to insert the folded airbag (2) into an airbag module (80).

Description

A METHOD AND AN APPARATUS FOR FOLDING AN AIRBAG

TECHNICAL FIELD

[0001] The present invention relates to an airbag folding method and to an airbag folding apparatus.

BACKGROUND

[0002] Airbags in driver airbag modules are usually arranged in a folded state in an airbag housing behind a covering. In the event of a crash the airbag is inflated, i.e. filled with a gas by effect of an inflator attached to the airbag. The airbag is deployed to form a gas-filled cushion that can dampen the impact of the vehicle occupants.

[0003] In the most remote prior art, airbags were folded in a meticulous manner and the folded airbag, connected with an inflator, was placed into a cover.

[0004] Some more recent prior art solutions use a series of vertically movable pistons to push the airbag directly into the cover. For example, a method of folding an airbag is described in document US 6,250,675.

[0005] Such method comprises the steps of spreading out an unfolded airbag and constricting the spread-out airbag at least once on at least one side perpendicular to the plane of the spread-out airbag by means of a sword-like tool.

[0006] In an embodiment described, first sliders then compress the airbag in the direction of the constriction and further sliders subsequently compress the airbag along a direction which is at right angles with respect to the compression direction of the first sliders.

[0007] In this way, the airbag is folded to the size required for storage in an airbag module while the constriction remains set, and the airbag is folded separately in areas which are separated by a constriction.

[0008] Another method of folding an airbag is described in document US

6,171 ,228. In this method, the airbag has an inner main fold and an outer main fold in a folded state. The airbag is fixed to a working surface and extended along a longitudinal axis away from the working surface. To extend the airbag, a shaping body, in the form of a hollow cylinder, is inserted into the airbag until the latter is completely stretched, the shaping body having numerous through openings.

[0009] The hollow cylinder is then biased with compressed air that enters the airbag from the through openings and presses the airbag away from the outer surface of the hollow cylinder in the area of the outer main folds provided. The hollow cylinder is then pushed together with folding plates and a pressure plate towards a generator support plate. The folding of the airbag is thereby carried out whereby the site of the main folds is fixed through the position of the folding plates and through the compressed air. During folding the compressed air is let out of the airbag until the folding process is possible.

[0010] Still another method of folding an airbag is described in document US 6,327,838. This method involves straightening the airbag out in the direction of a straightening axis, by means of straightening ram, starting from a gas inlet opening of the airbag. The airbag in the straightened-out state, or during the straightening-out operation, is pushed into a guide sleeve in the direction of the straightening axis. The airbag is then pushed together, and in the method folded, within the guide sleeve in the longitudinal direction thereof, in the direction of the straightening axis.

[0011] In particular, the straightening ram is pushed into the airbag in the direction of a straightening axis by way of a gas inlet opening which has a guide sleeve. The guide sleeve is arranged coaxially with respect to the straightening ram and the straightening ram can be pushed along the straightening axis. The inner cross-sectional surface area of the guide sleeve is greater than the cross-sectional surface area of the straightening ram, and has a folding ram which, for the purpose of pushing the airbag together, can be moved within the guide sleeve, along the straightening axis.

[0012] In this last method, the inflator is installed after the airbag folding process is completed.

[0013] It is an aim of the present invention to overcome the drawbacks of the prior art by means of an airbag folding method and apparatus that allows the installation of the inflator before the start of the folding process.

[0014] A further aim of the invention is to provide an airbag folding method and apparatus that reduces the number of apparatus and components needed to perform the folding operation and reduces the space required.

SUMMARY OF THE INVENTION

[0015] These and other aims are achieved by a method of folding an airbag comprising the steps of:

- providing an airbag connected to an inflator;

- connecting the airbag to a straightening ram;

- providing a guide sleeve configured to be arranged coaxially with respect to an axis of the straightening ram, the guide sleeve being provided with a radial ram group;

- generating relative movement between the airbag connected to the straightening ram and the guide sleeve;

- compressing axially the airbag against an abutment surface of the guide sleeve;

- compressing radially the airbag by activating the radial ram group of the guide sleeve until the radial dimensions of the airbag are reduced; and - pushing the straightening ram in order to insert the folded airbag into an airbag module.

[0016] An advantage of this invention is that the method can be performed by an associated apparatus that occupies reduced space.

[0017] According to an embodiment of the method, the airbag is connected to an inflator before being connected to the straightening ram.

[0018] According to a further embodiment of the method, the compression action of the straightening ram is continued until the airbag reaches a dimension in an axial direction which is substantially equal to the axial dimension of the radial ram group.

[0019] This embodiment allows compressing the airbag in a manner sufficient to allow it to be pushed into the cavity defined by the cover of the guide sleeve in a final step of the method.

[0020] The invention also comprises an apparatus for folding an airbag comprising:

- a straightening ram suitable to straighten the airbag in an axial direction;

- a guide sleeve arranged coaxially with respect to an axis of the straightening ram,

- a folding ram to generate a relative movement between the airbag connected to the straightening ram and the guide sleeve;

- the guide sleeve being further provided with a radial ram group for compressing radially the airbag.

[0021] This inventive apparatus further allows reducing the amount of module components.

[0022] In a further embodiment of the apparatus for folding an airbag, the cover of the guide sleeve is dome-shaped and is configured to create a cavity in which the folded airbag may be housed. [0023] In still another embodiment of the apparatus, the radial ram group comprises at least two radially movable pistons that are used to compress the airbag in a radial direction thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The invention will now be described in greater detail, by way of example, with reference to the accompanying non-limiting drawings, wherein like numerals denote like elements, and in which:

- Figure 1 represents an airbag in an unfolded state and connected to an inflator;

- Figure 2 represents the airbag-inflator group of Figure 1 connected to a straightening ram;

- Figure 3 represents the airbag-inflator group of Figure 1 in a further unfolded state;

- Figure 4 represents the airbag-inflator group of Figure 1 and a guide sleeve;

- Figure 5 represents the airbag-inflator group of Figure 1 during a first step of the folding method according to an embodiment of the invention;

- Figure 6 represents the airbag-inflator group of Figure 1 during a second step of the folding method;

- Figure 7 represents the airbag-inflator group of Figure 1 during a third step of the folding method;

- Figure 8 represents the airbag-inflator group of Figure 1 during a fourth step of the folding method; and

- Figure 9 represents the airbag-inflator group of Figure 1 during a fifth step of the folding method;

- Figure 10 represents the folded airbag inside the cover with a housing or plate secured to the cover; - Figure 1 1 represents a complete airbag module obtained by the previous method;

- Figures 12-17 represent various steps of a folding method according to a further embodiment of the invention;

- Figure 18 represents an airbag, folded according to the method of Figures 12-17, inside the cover with a housing or plate secured to the cover and;

- Figure 19 represents a complete airbag module obtained by the method of Figures 12-17.

DETAILED DESCRIPTION OF THE DRAWINGS

[0025] Considering initially Figure 1 , an airbag 2 in an unfolded state is represented.

[0026] An inflator or gas generator 40 is mounted to an opening or inlet of the airbag 2 in a known manner, the inflator 40 being provided with an inflator support 42 which is typically in the form of a set of fasteners 43, thus forming an airbag-inflator group 50. The inflator support 42 might be of the type that includes, as is known in the art, a mounting flange through which the fasteners are received.

[0027] In Figure 2, the group composed of the airbag 2 and the inflator 40 is represented as connected to a straightening ram 10, while in Figure 3 the airbag 2 is represented in a further unfolded configuration in which it is placed adjacent to the external walls of the straightening ram 10.

[0028] The straightening ram 10 comprises an external section that operates as a folding ram 20 which itself is movable and acts as another ram.

[0029] In this configuration, the group composed of the airbag 2 and the inflator 40 are shown apart from a guide sleeve 18 ready to be relatively moved together relative to the guide sleeve 18 (Figure 4).

[0030] The guide sleeve 18 has a substantially cylindrical shape and terminates in an upper portion thereof provided with a dome-shaped cover 24 that is configured to create a cavity 28 in which to house the folded airbag 2 in the final stage of the folding method as hereinafter described. The dome-shaped covering is more specifically described as the driver side cover or simply a cover, which protectively houses the folded airbag 2 and inflator 40. The cover is operatively secured to the inflator via the inflator support 42 with the folded airbag therein. The terms dome-shaped covering or driver side cover or cover are used interchangeably herein.

[0031] Furthermore, the guide sleeve 18 is provided with a radial ram group 60 (Figure 4) whose function will be explained in more detail in the following description.

[0032] Also, the guide sleeve 18 is provided with an abutting surface 30 that is placed just below the dome-shaped covering or cover 24. The cover 24 includes a top 24a and contiguous sides 24b which may continue the dome shape of the top 24a or be of some other shape. The cover includes a vertical contiguous wall 24c which has a cross-section that forms a cylindrical structure and in cooperation with the cover top 24a assists in forming the cavity 28. The diameter across the walls 24c is larger than the diameter of the inflator 40 thereby providing room for the compacted airbag 2, as can be seen for example in Figure 9.

[0033] The radial ram group 60 is provided with radially movable pistons 32, 33 that are used to compress the airbag 2 in a radial direction.

[0034] The radially movable pistons 32, 33 can be two or more, such as three or four radially movable pistons.

[0035] In Figure 5 a first step of the airbag folding method according to an embodiment of the invention is represented.

[0036] In such first step, as shown in Figure 5, the guide sleeve 18 and the group composed of the airbag 2 and the inflator 40 are moved relative to one another such that portions of the airbag 2 are placed between the exterior of the straightening ram 10 and the inside of the guide sleeve 18, and the inflator 40 is positioned below the abutting surfaces 30. As the guide sleeve 18 moves over the downwardly positioned airbag 2, any friction between the airbag and the sleeve keeps the airbag 2 in this position.

[0037] In a second step of the folding method (Figure 6), the folding ram 20 is pushed in such a way as to axially compress the airbag 2 between the inside of the guide sleeve 18 and the outside of the straightening ram 10.

[0038] In particular, the folding ram 20 acts upon the airbag 2 in cooperation with the abutting surface 30 of the guide sleeve 18 in such a way as to compress the airbag 2 in an axial direction thus reducing its volume, while the airbag 2 itself and the inflator 40 are pushed towards the cavity 28 defined by the cover 24.

[0039] In a third step of the folding method (Figure 7), the compression action of the folding ram 20 is continued until the folding arm 2 reaches an axial direction just below the radially movable pistons 32 and 33.

[0040] In this configuration, the airbag 2 is compressed to form a substantially annular shape around and in the vicinity of the inflator 40 and within the radial ram group 60 comprising pistons 32 and 33.

[0041] In a fourth step of the folding method (Figure 8) the radial ram group 60 is activated and the airbag 2 is radially compressed toward the center of the sleeve 18 in a radial inward direction.

[0042] The amount of compression of the airbag 2 is such as to reduce the radial dimensions of the airbag 2 of a quantity sufficient to allow performance of the fifth, and last, step the folding method (Figure 9).

[0043] In the fifth step, the airbag 2 is further pushed by means of the straightening ram 10 inside the cavity 28 defined by the cover 24 and partially by the inflator 40.

[0044] Subsequently, the cover 24 with airbag 2 and the inflator 40 within the cover 24 are removed from the straightening arm 18 as shown in Figure 10.

[0045] Figure 1 1 represents a final step in which a housing or plate 70 is placed under the inflator 40: The housing or plate 70 has openings 72 to receive the fasteners 43. Additionally the housing 70 may include hooks 74 which are received in slots 76 near the bottom of the wall 24c defining a complete airbag module 80.

[0046] Reference is made to Figure 12 which illustrates an alternate folding apparatus that is a variant of the folding apparatus illustrated in Figure 4. In Figure 4 numeral 24 denotes a dome-shaped cover positioned above and adjacent to the abutment surfaces 30. This dome-shaped cover 24 in this alternate embodiment is replaced by a plate 224 which acts as a cover mechanism secured to a piston 226. The plate 224 and cover are movable vertically. In its illustrated position the plate 224 is positioned within the opening between opposing abutment surfaces 30.

[0047] A large piece of fabric 230 typically circular or square is slid underneath the plate 224 and between the spaces between each abutment surface 30 and the plate 224. Ends of this fabric are designated by numerals 230a and extend outwardly beyond the edge of the guide sleeve 18.

[0048] In Figure 13, as in Figure 5, the guide sleeve 18 and the ram 10 which supports the inflator 40 and airbag 2 are moved relative to one another with the interior of the guide sleeve 18 covering the downwardly positioned airbag 2. The steps of vertically compressing the airbag 2 previously described in Figures 6 and 7 are repeated by Figures 14 and 15. Subsequently, with the compressed airbag 2 in its position shown in Figure 15 the radially movable pistons 32 and 33 radially compress the annular configuration or size of the airbag 2 around the inflator 40 so that the compressed dimension of the airbag 2 falls within the overall dimension of plate 224 which also corresponds to the diameter of the straightening ram 10. This condition is substantially as illustrated in Figure 16.

[0049] In Figure 17 the piston 226 and plate 224 are shown as ready to be retracted moving away from the compressed airbag 2 and inflator 40 group. An enlarged view of the top of Figure 17 is shown in Figure 18. With regard to Figure 18 once the piston 226 and plate 224 are positioned away from the compressed airbag 2, the airbag 2 and inflator 40 are removed from the folding apparatus and the fabric material 230 is pulled downwardly toward the inflator supports 42 and toward the fasteners 43. The fabric material 230 includes a plurality of openings 230b. These openings are arranged so that each fastener 43 can pass through a corresponding opening 230b, thereby securing the material 230 creating a protective enclosure about the folded and compressed airbag 2. As can be appreciated, the fabric material 230 functions as a dust cover to keep particulates away from the folded airbag 2 and to also protect the inflator 40. While not illustrated in the figures, the folded airbag 2 with its dust cover in place is then placed within a dome shaped driver side airbag cover which is secured in place by a housing or plate 72 providing another form of a driver side airbag module.

[ 0050 ] While at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.

Claims

1. A method of folding an airbag (2) comprising the steps of:

- providing an airbag (2) connected to an inflator (40);

- connecting the airbag (2) to a straightening ram (10);

- providing a guide sleeve (18) configured to be arranged coaxially with respect to an axis of the straightening ram (18), the guide sleeve (18) being provided with a radial ram group (60);

- generating relative movement between the airbag (2) connected to the straightening ram (10) and the guide sleeve (18);

- compressing axially the airbag (2) against an abutment surface (30) of the guide sleeve (18);

- compressing radially the airbag (2) by activating the radial ram group (60) of the guide sleeve (18) until the radial dimensions of the airbag (2) are reduced; and

- pushing the straightening ram (10) in order to insert the folded airbag (2) into an airbag module (80).

2. The method of folding an airbag (2) as in claim 1 , wherein the airbag (2) is connected to an inflator (40) before being connected to the straightening ram (10).

3. The method of folding an airbag (2) as in claim 1 , wherein the relative movement between the airbag (2) and the guide sleeve (18), is generated by a compression action of a folding ram (20) acting upon the airbag (2) in cooperation with the abutting surface (30) of the guide sleeve (18).

4. The method of folding an airbag (2) as in claim 3, wherein the relative movement between the airbag (2) and the guide sleeve (18), is generated by a compression action of a folding ram (20) acting upon the airbag (2) in cooperation with a plate (224) secured by a piston (226).

5. The method of folding an airbag (2) as in claim 3, wherein the relative movement between the airbag (2) and the guide sleeve (18) is continued until the airbag (2) reaches a dimension in an axial direction which is substantially equal to the axial dimension of the radial ram group (60).

6. An apparatus for folding an airbag (2) comprising:

a straightening ram (10) suitable to straighten the airbag (2) in an axial direction;

a guide sleeve (18) arranged coaxially with respect to an axis of the straightening ram (18),

a folding ram (20) adapted to generate a relative movement between the airbag (2) connected to the straightening ram (10) and the guide sleeve (18);

the guide sleeve (18) being further provided with a radial ram group (60) for compressing radially the airbag (2).

7. The apparatus for folding an airbag (2) as in claim 6, wherein a cover (24) of the guide sleeve (18) is dome-shaped and is configured to create a cavity (28) in which the folded airbag (2) may be housed.

8. The apparatus for folding an airbag (2) as in claim 6, wherein the radial ram group (60) comprises at least two radially movable pistons (32,33) that are used to compress the airbag (2) in a radial direction.

9. The apparatus for folding an airbag (2) as in claim 6, further comprising a plate (224) secured by a piston (226) suitable to cooperate with the folding ram (20) to generate a relative movement between the airbag (2) and the guide sleeve (18).