Patent Application
20190039554
The invention relates to a method of manufacturing an airbag, especially a side airbag, for a vehicle occupant restraint system. Furthermore, the invention relates to an airbag, especially a side airbag, for a vehicle occupant restraint system comprising a textile airbag cushion which is formed especially from at least one textile pre-cut by joining one or more edge portions by sewing and comprising at least one tab for vehicle-side fastening of the airbag.
Airbags, especially large-area window bags, are installed in vehicle occupant restraint systems in a folded or rolled state along the roof rail so that they can be stored in a space-saving manner and in the event of release have a defined expansion. Accordingly, the airbags folded or rolled to form an airbag package have to be safely retained. For this purpose, the upper portion of the airbag in the mounted state is usually provided with plural tabs by which it is fixed to the vehicle via appropriate fastening devices.
In currently common airbags the tabs frequently are in the form of an integral part of the airbag pre-cut and, where necessary, are manually reinforced by reinforcing layers cut before. Moreover, it is known to completely attach the tabs as the airbag pre-cuts then may be nested more efficiently on the textile fabric from which they are cut. In this case, the tabs are separately and completely cut out of the textile fabric, are manually arranged at the intended airbag position and are attached thereto by sewing.
Said known methods are comparatively complicated.
Therefore, it is the object of the invention to provide a method of manufacturing an airbag and, resp., to provide an airbag which excels by reduced manufacturing time while being of high quality.
In order to achieve this object, a method of the afore-mentioned type provides the following steps of:
The method according to the invention thus provides to use strip-shaped textile fabric which already has the desired width of the finished tab for forming the tabs, thus allowing a lateral pre-cut for forming the tab to be omitted. In particular, to this end pre-tailored fabric strip is used the longitudinal edges of which are finished by weaving, i.e. which are free from cut edges. The strip merely is cut to the required length. In this way and by automated feeding of the tab to the sewing machine, with the provision of the tab being integrated in the sewing process, significantly shorter process time will be achieved than in prior art. In addition, the use of strip material is definitely less expensive than manual cutting of specific tabs out of a flat textile fabric.
It is pointed out that the afore-mentioned vehicle-side fastening may also be indirect, such as by fixing, e.g. sewing, the airbag to an airbag module housing which in turn is connected to the vehicle body. It is further noted that the given method steps need not necessarily be carried out in the given order; for example, feeding of the airbag cushion to the sewing machine may take place only after cutting the strip-shaped textile fabric to length.
Preferably, at least the steps c) to f) are automated. In this way, airbags of constantly high quality can be manufactured as the risk of confusion of the tab pre-cuts as well as faulty positioning thereof is almost excluded due to the automated provision. In addition, short process times can be achieved.
An especially easy handling is achieved when the strip-shaped textile fabric is made available on one or more rolls.
Cutting to length may be carried out by means of a punching knife and/or a hot knife and/or a laser.
According to a preferred embodiment, at least one retaining hole is introduced to the tab, especially wherein the at least one retaining hole is introduced prior to feeding the tab to the sewing machine or in parallel to attaching the tab. In said retaining hole for example a vehicle-side fastening element may engage so as to safely fix the airbag to the vehicle.
In order to enable exact manufacture of the retaining holes, preferably the tab is fixed in a clamping device when the at least one retaining hole is introduced. In this way, the tab is prevented from inadvertently getting out of place.
The at least one retaining hole may also be introduced by means of a punching knife and/or a hot knife and/or a laser.
Of preference, the strip-shaped textile fabric is folded at least once in an automated manner for forming the tab. Advantageously the fold is arranged at the end of the tab facing away from the airbag cushion, which increases the bearing strength of the retaining hole being under tensile stress upon deployment of the airbag.
Preferably, the airbag cushion includes plural tab positions which show a standardized fitting geometry. Hence, a kind of standard airbag-tab interface is provided so that the process times can be further reduced.
According to a preferred embodiment, the sewing machine is a CNC machine. In this way, the required seams can be automatically produced with high precision and very quickly.
In order to increase the tear strength of the tab especially at the strongly loaded points, at least one bar tack can be produced when attaching the tab by sewing to the airbag cushion.
According to a second aspect of the invention, an airbag of the type mentioned in the beginning is provided in which the at least one tab is made from strip-shaped textile fabric and is attached to the airbag cushion by sewing. In this way, the process times can be significantly reduced as compared to the individual pre-cut of the tabs of textile fabric.
Preferably, the tab is multi-layered, especially with the airbag cushion being interposed between two layers of the tab. Hence the tab includes at least two layers which “encompass” the airbag cushion, thus allowing to achieve especially high stability.
The tab may include at least one folded strip-shaped textile fabric, which increases its tear strength in the case of tensile stress, especially for a retaining hole introduced to the tab.
Of preference, the tab includes at least one bar tack so as to increase the points loaded most strongly by the tensile stresses occurring upon deployment of the airbag. Preferably, in the longitudinal direction of the tab on both sides of a possibly present retaining hole a respective bar tack, i.e. a reinforcing seam is provided.
The strip material of the tabs thus may be advantageously adapted specifically to the characteristics of the fastening. In the case of woven strip material, a thread material different from that of the airbag may be used. Especially, the weaving density or the thread size may be different from that of the airbag.
Moreover, all developments and advantages mentioned with reference to the method according to the invention are applicable analogously to the airbag according to the invention and vice versa.
Further features and advantages will be resulting from the following description of a preferred embodiment by way of the enclosed drawings, wherein:
Furthermore, a schematically illustrated automatic feeding unit 15 is provided which is shown further enlarged in
The feeding unit 15 moreover comprises a cutting device 18 which may be a punching knife, a hot knife or a laser. The cutting device 18 is used to cut the strip-shaped textile fabric 14 to a desired length and to subsequently fold it once in an automated manner so as to form a tab 20.
After that, by means of a piercing device 22, which again may be a punching knife, a hot knife or a laser, at least one retaining hole 24 is introduced to the folded tab 20, with the tab 20 being fixed in a clamping device 26.
Upon request, the tab 20 prepared in this way is fed in an automated manner by the feeding unit 15 to the sewing machine 10 which attaches the tab 20 at a desired tab position 28 to the airbag cushion 11 appropriately positioned already before.
When attaching the tab 20 to the airbag cushion 11 by sewing, bar tacks 30 are produced so as to increase the stability of the tab 20 and, resp., of the seams. As is evident from
The tabs 20 serving for vehicle-side fastening of the airbag 32 are multi-layered, four-layer in this case, wherein the airbag cushion 11 is interposed between two layers of the tabs 20 such that on each side of the airbag cushion 11 two layers of the strip-shaped textile fabric 14 are located.
The fold 34 of the once-folded strip-shaped textile fabric 14 is arranged at the outwardly pointing end of the tab 20 facing away from the airbag cushion 11 so as to increase the bearing strength of the retaining hole 24 which upon deployment of the airbag 32 is under tensile stress.
The bar tacks 30 are disposed in the longitudinal direction of the tab 20 on both sides of the retaining hole 24.
The method according to the invention enables the tabs 20 to be quickly attached to the airbag cushion 11 by sewing in an automated manner, as especially the steps of providing the strip-shaped textile fabric 14, cutting the strip-shaped textile fabric 14 to length, folding the strip-shaped textile fabric 14, feeding the tab 20 to the sewing machine 10 as well as attaching the tab 20 to the airbag cushion 11 by the sewing machine 10 are carried out in an automated manner. Accordingly, process times of few seconds for each tab 20 are possible.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2016 001 505.5 | Feb 2016 | DE | national |
This application corresponds to PCT/EP2017/051350, filed Jan. 24, 2017, which claims the benefit of German Application No. 10 2016 001 505.5, filed Feb. 11, 2016, the subject matter of which are incorporated herein by reference in their entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2017/051350 | 1/24/2017 | WO | 00 |
