Manufacturing container or tube from paper; or other manufacturi – Bending – Folding
Reexamination Certificate
1997-10-23
2004-04-27
Rada, Rinaldi I. (Department: 3721)
Manufacturing container or tube from paper; or other manufacturi
Bending
Folding
C493S244000, C493S450000, C493S451000, C493S458000, C280S728100, C280S743100
Reexamination Certificate
active
06726615
ABSTRACT:
The invention relates to a method of-folding a gas bag for a vehicle occupant restraint system, a folded gas bag for a vehicle occupant restraint system and also a device for performing the method.
BACKGROUND OF THE INVENTION
A restraint system for a vehicle occupant usually consists of a compressed gas source, a triggering system for this and also a gas bag which is in flow connection with the compressed gas source and after ignition of the compressed gas source can be transferred from a space-saving, folded state into an unfolded state in which it can provide a restraint effect for a vehicle occupant.
Several requirements are set for the type of folding of the gas bag. Firstly, it is to make possible as quick a transfer of the gas bag as possible from the folded into the unfolded state. Furthermore, the folding is preferably to be possible automatically. This reduces the manufacturing costs of the vehicle occupant restraint system.
BRIEF DESCRIPTION OF THE INVENTION
The invention provides a method of folding a gas bag, which method can be carried out firstly automatically without manual steps, and secondly leads to a folded gas bag which can be unfolded in a particularly advantageous manner. The method according to the invention is intended for folding a gas bag for a vehicle occupant restraint system. This gas bag has a wall delimiting a chamber and having an inflation opening, the inflation opening having a rim. The method comprises the following steps: First, the gas bag is spread out on a base. Then, the rim of the inflation opening of the gas bag is held fixed. Thereafter, a plate is arranged parallel to the base and at a distance therefrom, so that the gas bag extends between the base and the plate. Subsequently, the chamber of the gas bag is exposed to a pressurized medium, so that the gas bag unfolds between the base and the plate. Finally, the wall of the gas bag is pressed inwards at a plurality of sites distributed over a circumference of the gas bag. In this way, a gas bag is obtained which is folded together very compactly, but which nevertheless is easy to unfold. Compared with conventional folding methods, an improvement in the unfolding time of the gas bag was able to be observed. In addition, a more uniform unfolding of the gas bag and also an improved opening behavior of a cover protecting the folded gas bag, was observed. A gas bag folded by the method according to the invention has a particularly symmetrical unfolding, whereby the positioning of the gas bag during the unfolding process is improved. Due to the particularly uniform unfolding of the gas bag, its seams and its fabric are stressed less than in gas bags which are folded by conventional methods. Owing to the improved behavior on unfolding, an impact of wall parts of the unfolding gas bag onto a vehicle occupant who is to be restrained was only observed to a distinctly lesser extent and with distinctly less energy than in gas bags which are folded by conventional methods. The method according to the invention is suitable both for gas bags on the driver's side, i.e. for gas bags which are two-dimensional in the unpressurized initial state, and also for gas bags on the passenger's side, which usually have a three-dimensional form in the unpressurized initial state.
According to a preferred embodiment of the invention, provision is made that the wall is pressed inwards by a plurality of fold tongues spaced apart from each other, which each engage along a line at the wall of the gas bag, so that wall flaps lying between the fold tongues are formed. Fold tongues represent a particularly simple means to press the wall of the gas bag inwards at a plurality of locations spaced apart from each other, so that the gas bag is folded together compactly.
According to a preferred embodiment of the invention, provision is made that the wall is pressed inwards in two steps, in which in the second step the wall flaps which were formed in the first step are pressed inwards. In this way, a particularly compact, folded gas bag is achieved, the wall of which nevertheless is folded very uniformly.
According to a preferred embodiment of the invention, provision is further made that the fold tongues are pressed towards the interior of the gas bag along a straight line. In this way, the method according to the invention can be carried out in a particularly simple manner.
Furthermore, provision can be made that the fold tongues are displaced in a parallel manner on being pressed towards the interior of the gas bag. This method is advantageous in particular in gas bags on the passenger side, because by means of the parallel displacement of the fold tongues, even a gas bag which has an elongated initial shape can be folded together particularly compactly.
According to a preferred embodiment of the invention, provision is further made that the wall of the gas bag is pressed in along lines which are perpendicular to the base and the plate. In this way, it is ensured that the wall of the gas bag, on unfolding, must merely move outwards substantially without changing its direction, so that the gas bag reaches its completely unfolded form.
According to a preferred embodiment of the invention, provision can be made that after the wall of the gas bag has been pressed inwardly by means of the fold tongues, the wall is pushed together by fold sliders towards the interior of the gas bag. Due to the combination of fold tongues and fold sliders, the method according to the invention can be carried out with a particularly small effort. The fold tongues which are firstly moved into the wall of the gas bag basically determine the folding pattern to be achieved. However, instead of folding together compactly the entire wall of the gas bag by means of a plurality of fold tongues, the wall can be pushed together compactly by means of less fold sliders in a simple manner.
According to a preferred embodiment of the invention, provision can be made that the wall is pushed towards the interior of the gas bag by means of four fold sliders, in which every two fold sliders lie opposite each other in pairs and in which four fold tongues are used which lie opposite each other in pairs. The use of four fold tongues and four fold sliders represents a good compromise in which, on the one hand, a reproducible folding of the gas bag is obtained, whilst, on the other hand, the effort to carry out the method is kept small.
According to a preferred embodiment of the invention, provision is made that the chamber of the gas bag is exposed to an excess pressure of less than 100000 Pa for unfolding between the base and the plate. This pressure is sufficient, on the one hand, to ensure a complete unfolding of the gas bag between the base and the plate, and, on the other hand, is not so high that the penetration of the fold tongues into the wall of the gas bag is opposed with an excessively high resistance. Preferably, provision is made that the chamber of the gas bag is exposed to a pressure of approximately 50000 Pa. This value has proved to be sufficient in tests.
According to a preferred embodiment of the invention, provision can further be made that after the gas bag has been exposed to pressure, the pressurized gas contained in the chamber of the gas bag can escape during the fold tongues or fold sliders being pressed in. In this way, the energy to be applied on pressing in the fold tongues or fold sliders into the wall of the gas bag is kept at a low value.
Furthermore, provision can be made that after folding the gas bag, a partial vacuum is applied to its chamber. In this way, the folded gas bag can be transferred into an even more compact form, whilst at the same time it is ensured that the folded gas bag, in particular after the removal of the fold elements, maintains its folded form before it is fixed elsewhere.
Preferably, provision is made that the base is arranged at a distance from the plate which corresponds approximately to the packing height of the folded gas bag. The packing height represents the height which the folded gas bag has in
Aich Josef
Berger Jürgen
Dannenhauer Reiner
Kuhn Adolf M.
Lang Norbert
Harmon Christopher
Rada Rinaldi I.
Tarolli, Sundheim Covell & Tummino L.L.P.
TRW Occupant Restraint Systems GmbH
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