Package making – Methods – With contents treating
Reexamination Certificate
1999-09-07
2001-12-11
Kim, Eugene (Department: 3721)
Package making
Methods
With contents treating
C280S728100, C280S743100, C493S449000
Reexamination Certificate
active
06327838
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for folding an airbag.
BACKGROUND OF THE INVENTION
Airbags in 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. The airbag is deployed to form a gas-filled cushion that can damp the impact of the vehicle occupant. Up until now, folding of the airbag has been performed such that the airbag has been spread out flat and then folded specifically at predetermined points resulting in a folded arrangement. This folded arrangement is then arranged in the airbag module near the gas generator, or a gas-supply device, such that it is located in the direction of deployment of the airbag, i.e. the folded airbag is located between the gas generator and the vehicle occupant.
The methods which have been used heretofore for folding an airbag have a number of disadvantages. For example, a very large amount of space is necessary for the purpose of folding the airbag, since the entire airbag must first of all be spread out flat. Furthermore, for automated folding of the airbag, there is a need for a relatively complicated installation, which has to be adapted individually in each case to different airbag shapes and the specific folding sequences thereof. Moreover, such complicated folding can only be performed at a limited speed.
An object of the invention is to provide a method and an apparatus for folding an airbag for an airbag module and permit simplified and quicker folding of the airbag and a smaller amount of installation space for the apparatus.
In the method according to the invention, the airbag is first of all straightened out in the direction of a straightening axis, starting from a gas inlet opening of the airbag. In the straightened-out state or during the straightening-out operation, the airbag is pushed or drawn into an outer guide device in the direction of the straightening axis, and then the airbag is pushed together, and in the method folded up, within the outer guide device in the longitudinal direction thereof, i.e. in the direction of the straightening axis. In this method, for the folding operation, the airbag is straightened out along an axis rather than being spread out flat resulting in a three-dimensional arrangement. The subsequent folding operation does not take place in a specific manner, i.e. the airbag is not folded along precisely predetermined folding lines. Rather, folding is brought about arbitrarily by the airbag being pushed together in the outer guide device. The airbag is folded in the manner of an accordion, the fold lines being produced arbitrarily. This folding method permits the airbag to be folded considerably more easily and quickly since it is possible to dispense with numerous individual, precisely defined folding operations along predetermined folding lines. Furthermore, the method does not require much space since the airbag does not have to be spread out flat, but rather is straightened out along a line instead.
This folding method produces a folding pattern with main folding lines that start from a central region, which is located in the vicinity of the straightening axis, and run essentially radially outwards in a straight line to the periphery of the airbag. It is also possible to achieve folding in the case of which the main folding lines run essentially radially on the front layer of the material, which is directed toward the vehicle occupant, while they run essentially concentrically, preferably parallel to the periphery of the airbag and/or of the gas inlet opening, on the rear layer of material, which is directed away from the vehicle occupant.
The straightening axis advantageously runs essentially perpendicularly with respect to a front surface of the airbag. The front surface of the airbag in this case is the impact surface of the airbag, which, when the airbag is installed in a motor vehicle, is directed toward a vehicle occupant when the airbag is inflated. Since the straightening axis runs essentially perpendicularly with respect to said front surface, it is possible to ensure, on the one hand, a straightforward folding operation and, on the other hand, at a later stage, when the airbag is filled with gas by a gas generator, also a specific and reliable deployment operation of the airbag, in the case of which first of all the front surface moves toward and comes into contact with the vehicle occupant.
During the folding operation, the airbag is expediently fixed preferably in the region of its gas inlet opening. This makes it possible to ensure, during the folding operation, that the gas inlet opening remains free and is later accessible to be fitted on a gas-supply device or a gas generator.
The airbag is preferably pushed together in the outer guide device by means of a folding ram. In this case, the folding ram moves within the outer guide device along the longitudinal axis thereof, i.e. in the direction of the straightening axis, and pushes the straightened-out airbag together such that it folds up in the manner of an accordion. In this case, the individual folds or creases are produced of their own accord during the folding operation without precise folding lines being predetermined. Despite folding lines that are not precisely predetermined, a satisfactory, precisely controlled deployment of the airbag at a later stage can nevertheless be ensured.
For the purpose of straightening out the airbag, a straightening ram is advantageously pushed into the latter in the direction of the straightening axis, starting from the gas inlet opening, and comes into abutment, by way of its end surface, against the inside of a section of the airbag which is located opposite the gas inlet opening. This allows the airbag to be straightened out to the full extent. The airbag is straightened, by the straightening ram being pushed in, until further movement of the straightening ram is restricted as a result of limiting bands, tear seams, etc. arranged in the airbag or by the outer sheath of the airbag itself. In this case, the straightening ram advantageously moves in a straightening direction, which corresponds, to the later main deployment direction of the airbag. This means that the airbag is straightened in its main deployment direction. This makes it possible to ensure, during the later pushing-together operation, that the folding-up operation of the airbag takes place in reverse order to the operation in which the airbag has to unfold again at a later stage when being inflated.
In the folding pattern produced during the subsequent folding operation, the central region from which the main folding lines, i.e. the creases produced during folding, extend radially outwards essentially in a straight line is that region of the airbag which butts against the end surface of the straightening ram. Essentially no folding lines are then formed in this region. The folding lines may run in a precisely radial manner toward the center point of this region. However, it is also possible for them to run such that they border tangentially on the periphery of said abutment surface, which in the case of a circular end surface of the straightening ram is likewise essentially circular, and, starting from the periphery of the abutment surface, extends essentially in a straight line to the outer circumference of the airbag.
During the straightening-out operation of the airbag, the straightening ram is preferably simultaneously pushed into the outer guide device. This allows the time required for the folding-up operation to be reduced since the operations of straightening out the airbag and pushing it into the sleeve take place, at least in part, at the same time. Furthermore, the action of the straightening ram being pushed into the outer guide device with the airbag surrounding it achieves the situation where even regions of the airbag which cannot straighten out to the full extent as a result of, for example, limiting bands or seams, these are the peripheral or outer regi
Doelfel Michael
Jost Markus
Maul Holger
Staub Andreas
Breed Automotive Technology Inc.
Drayer Lonnie
Kim Eugene
LandOfFree
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