Land vehicles – Wheeled – Attachment
Reexamination Certificate
1999-05-25
2001-01-23
Rice, Kenneth R. (Department: 3611)
Land vehicles
Wheeled
Attachment
C280S743100
Reexamination Certificate
active
06176514
ABSTRACT:
The invention relates to an inflatable side airbag with duct-shaped forming chambers, which has a fastening side which is provided for the fastening of the airbag along a substantially curvilinear fastening section along a roof spar of a motor vehicle as well as a free side which is unfoldable through the inflation of the airbag, which is fastened to the fastening section, along a main development direction extending substantially downwardly in the vertical direction and which free side in the thus inflated state of the airbag is provided at the lower side of the airbag as well as lying substantially opposite to the fastening side.
A side airbag of this kind, in the following designated merely as an “airbag”, serves for the protection of passengers of the motor vehicle in the event of an accident. For this the airbag is inflated where appropriate so that it—starting at the fastening section at the roof spar—unfolds in particular in the main development direction and thus forms a protective cushioning between the relevant passenger and the side wall of the motor vehicle. In this the forming chambers serve on the one hand for the formation of protective cushionings, on the other hand for the stabilisation of the orientation of the inflated airbag as well as for the shortening of the airbag during its inflation so that the airbag is tensioned.
A disadvantage of the known airbags is that their shortening, which accompanies the inflation, often produces twistings or the formation of folds at the airbag surface, and indeed above all in the region of the fastening side.
An object of the invention is to provide an airbag of the initially named kind which can be inflated to a shape which is matched to the outline of a roof spar so that the inflated airbag takes on the desired shape, tension and orientation, but that in this however no undesirable twistings or folds arise at the airbag surface. The invention should also show a suitable method for the provision of an airbag of this kind.
This object is satisfied in accordance with the invention by an airbag of the initially named kind, the cut, or tailoring, of which—i.e. the shape of which in the unfolded or outspread, non inflated state—has a substantially rectilinear border along the fastening side which has substantially the same length as the total length of the curvilinear fastening section, and the cut of which has a substantially curvilinear border along the free side.
In the airbag in accordance with the invention the fastening side is formed in the cut—in contrast to the desired curve shape of the fastening side in the inflated state—with a substantially rectilinear border and a length which corresponds to the length integrated over the entire curve path of the fastening section. The border of the fastening side is still to be seen as substantially rectilinear in the sense of this invention even if it has several local discontinuities, which for example result from the matching of the fastening side to the course of a gas tube. In accordance with the invention the border of the free side is formed curvilinearly in cut in such a manner that its course corresponds to the greatest extent to the curvilinear course of the fastening section and to the course of the border of the desired operating shape of the airbag.
The airbag in accordance with the invention can advantageously be inflated in such a manner that its lower, free side is tensioned through shortening, with no twistings or folds arising at the airbag surface. This can be attributed in particular to the following properties of the airbag in accordance with the invention:
Since in the cut the border of the fastening side is formed substantially rectilinearly and the border of the free side substantially curvilinearly, the latter has a greater total length than the former so that the free side has a certain excess length in the state of the airbag which is fastened inside the motor vehicle but is however not yet inflated. In contrast the total length of the fastening side corresponds in the cut to the total length of the fastening section. During the inflation of the airbag the correspondingly arranged forming chambers effect a shortening of the airbag along the free side, with the greatest shortening taking place in the region of the free side, whereas the shortening takes on an increasingly lesser extent in the direction towards the fastening side. Along the border of the fastening side, at which the total lengths of the airbag and the fastening section agree, no shortening takes place. Thus the invention enables a substantially continuous compensation of the shortening required for the tensioning of the airbag, through which disadvantageous twistings or folds are effectively avoided.
Within the framework of the invention it was recognised that, in contrast, in a usual forming of the border of the cut as a centric stretching of the outline of the desired operating shape, a shortening along the lower, free side also makes a corresponding shortening of the same extent at the fastening side necessary. Since the fastening side is guided along the curvilinear roof spar, however, the previously usual cut shape leads to undesirable twistings and folds at the inflated airbag.
A further advantage of the airbag in accordance with the invention is that it can be manufactured in a particularly simple manner. For example the cut can consist of two sides which need not be expressly connected to one another along the particularly stressed fastening side during the inflation of the airbag, but rather, as a result of the rectilinear forming of the border of the fastening side, can be chosen from a single piece of material which is folded over along the fastening side.
In a preferred embodiment of the airbag the latter has a border which is substantially rectilinear and which extends in the horizontal direction at the free side in its operating shape.
It can be achieved in a particularly effective manner that the airbag has the desired operating shape in the inflated state if in the cut the cut height, i.e. the distance from the border of the fastening side to the border of the free side, is in each case chosen as large as the desired airbag height for a plurality of sections along the fastening side, thus as the corresponding extent of the desired operating shape (cf. FIGS.
4
a
and
4
b
).
The design of the airbag in accordance with the invention with the duct-like forming chambers serves—as mentioned—among other things for achieving the desired shortening of the airbag during its inflation. In this a particularly goal-directed shortening of the airbag can be achieved through a corresponding arrangement of the forming chambers and an orientation of their respective duct shape. Basically, one obtains the greatest shortening of the airbag along the free side when the duct shapes of the forming chambers in the cut are formed perpendicular to the border of the free side or to the tangent at this border. The narrowing of a forming chamber during its inflation fundamentally takes place namely to the greatest extent along a plane which stands perpendicular to the duct shape of the forming chamber.
It is however also possible to provide the forming chambers in a different orientation than in the explained manner. The duct shape of the forming chambers preferably extends at the free side perpendicular to its border and in the region of the fastening side at an angle with respect to its border which is matched to the inflow direction of the gas which is provided for the inflation of the airbag or to the support and cushioning function of the airbag, for example at an angle of 30° to 60° to the border of the fastening side.
The duct shapes of the forming chambers are thus not necessarily formed rectilinearly, but can also be formed to be curved in accordance with an arbitrary curve function in particular in the region of the fastening side.
The excess length of the free side of the cut can be shortened with high precision to the length which is desired for the corresponding border of the operatin
Foley & Lardner
Rice Kenneth R.
Takata (Europe) Vehicle Safety Technology GmbH
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