Patent Application
20080296875
The invention relates to an airbag to protect a vehicle occupant according to the preamble of claim 1.
Conventional airbags having several chambers are usually manufactured out of two cuttings which are sewn along their edge regions and which demonstrate in darts to separate the chambers. In some airbags, the respective chambers have the task of protecting individual body areas of an occupant. Because of the different masses of the individual body areas, forces of different strength act upon them during an accident. Moreover, the weaker body areas, such as the rib cage, may not be stressed too strongly. This makes it necessary to inflate the chambers at different rates to some extent using different gas pressures.
U.S. Pat. No. 6,349,964 suggests a side airbag having an upper chamber assigned to projecting the thorax of the occupant and a lower chamber assigned to protect the pelvis of the occupant, the chambers being separated by a dividing seam. Because of the requirements imposed on the respective chambers in a side impact, it is provided that different gas pressures are used to fill the chambers. Thus in particular, the chamber assigned to the pelvic region is supposed to be filled with a higher pressure than that which fills the chamber assigned to the thoracic region of the occupant.
One disadvantage of this conventional arrangement of the side airbag consists of the fact that the dividing seam is subjected to high stresses because of the different pressures in the chambers, so that there exists the danger of crack formation or other leakage formation.
Proceeding from this prior art, it is the object of the invention to create an airbag in which no crack formation occurs in the region of the dividing seam between the two chamber regions during the inflation process and which is simple to manufacture.
The object is achieved by an airbag having the features of claim 1.
The airbag comprises a first and a second material layer, which are sewn to one another along their edge regions. The airbag demonstrates an opening which can be connected to a gas generator so that the gas generator can inflate the airbag during an accident. The airbag furthermore demonstrates a first and a second chamber region, which are separated from one another by a dividing seam. Each of the two material layers of the airbag comprises at least two material sections, each of which is respectively assigned to the first or second chamber region. The material layers overlap in the region of the dividing seam, which fixes them.
Because of the overlapping in the region of the dividing seam, the dividing seam extends through four layers of the material sections. In this way, this region of the airbag is reinforced in such a manner that it survives force applied during the inflation process without any leakage formation or crack formation occurring.
The separate material sections provide the possibility of introducing different fabric layers for the different application regions. Thus, very tear-resistant fabrics can be used for particularly stressed regions whereas light, cost-effective fabrics can be introduced for the remaining regions. In addition, particular material sections can be coated to minimize permeability and to additionally strengthen the fabric.
Pursuant to the embodiment according to claim 15, the airbag demonstrates another material layer which is fixed by the dividing seam in the same way and which additionally protects the region around the dividing seam in the event of particularly high stresses from very different gas pressures in the two chamber regions.
Pursuant to the embodiment according to claim 16, the airbag is a side airbag to protect the vehicle occupants during a side impact. To this end, the chamber regions are assigned to the pelvic region and thoracic region of the occupant and can be filled with different gas pressures. In general, the chamber assigned to the pelvic region will be filled with a higher gas pressure than the chamber assigned to the thoracic region. To this end, the airbag in the pelvic region is supposed to position itself particularly quickly and fix the center of gravity located in the pelvic region of the occupant in order to prevent the occupant from moving toward the side of the vehicle.
In order to maintain this high pressure in the airbag for the required time interval, the material sections assigned to the pelvic chamber region demonstrates a particularly heavy fabric and can additionally be coated with a silicone layer or a film, so that the material sections are characterized by high tear resistance in addition to low gas permeability.
The material sections assigned to the thoracic region are manufactured out of a more permeable fabric. Such a fabric is less expensive and has a lower weight.
Pursuant to another embodiment according to claim 18, the airbag is a curtain airbag and demonstrates at least one additional chamber region and an additional dividing seam. In the curtain airbag, the central region below the opening, which can be connected to a gas generator, is particularly stressed by the inflowing high-energy gases. The central chamber region therefore demonstrates material sections made of a very heavy fabric, whereas the two external chamber regions are manufactured out of less-heavy fabric sections.
Other preferred embodiments result from the further dependent claims and from the explanations to the following figures. The drawing shows:
a that which is depicted in
The construction of an airbag, which here is configured in the form of a side airbag, will be described in more detail on the basis of
The airbag 1 comprises of two material layers 2, 3, which are manufactured out of fabric. These material layers 2, 3 are sewn to one another by a seam 16 along their external contour. The circumferential seam 16 leaves open the fastening region 4 of the side airbag, so that an opening 23 for connecting to a gas generator (not illustrated) is formed, Gas generators frequently demonstrate fastening bolts, which are guided through the fastening holes 21, 22 from inside when the gas generator is inserted into the airbag and thereby fasten the airbag to the housing components.
A dividing seam 7, which divides the inflatable region into two chamber regions 5, 6, is configured in an approximately central region of the airbag. The dividing seam 7 is configured as a double seam, which extends from the edge region on the front side to the fastening region and is guided back to the front edge region in a curved course. As seen in
The dividing seam 7 is arranged in such a manner that the gas flowing from the gas generator is guided directly into the two chamber regions 5, 6. To this end, it is possible to introduce a deflector or a gas guide housing, for example, to selectively guide the gas jet. This is illustrated in
Following the sewing of the surrounding seam, side airbags are usually turned inside out so that the seam is disposed inside the airbag. The side airbag can thus be tucked through the opening 23 in the fastening region 4 so that the dividing seam 7 can then be added.
As illustrated particularly clearly in
overlap in the central region and are fixed by the dividing seam 7. The material sections 8 and 9 of the first material layer 2 are held together by the seam 19 whereas the material sections 10 and 11 of the second material layer 3 are held together by the seam 18.
Within the overlapping region of the four material sections 8, 9, 10, 11, the upper material sections 8 and 10 are disposed inside the lower material sections 9 and 11. Pursuant to another embodiment (not illustrated), the lower sections 9 and 11 are disposed inside the upper sections 8 and 10.
The chamber 6 assigned to the pelvic region of a vehicle occupant comprises a relatively heavy fabric, which is preferably coated. Fabrics in the range of 580 to 700 dtex can be used, for example.
The chamber 5 assigned to the thoracic region of the occupant comprises a relatively permeable fabric and must not be coated. Fabrics in the range of 235 to 580 dtex can be used here.
The two material sections 8 and 10 are formed from a single material layer, which Hi has a butterfly-like shape. The fold axis, around which the material layer is folded, extends along axis of symmetry S. The two remaining material sections 9 and 11 are configured as separate pieces and are sewn onto the associated material sections in each material layer by means of the seams 18, 19.
Pursuant to the exemplary embodiment according to
The invention also includes other embodiments that are not illustrated in the figures. Thus all material sections 8, 9, 10, 11 can consist of separate parts and be fastened to one another.
To this end, the term “axis of symmetry” should not be understood in a very narrow sense. Slight deviations, caused by manufacture, in the shaping of an airbag and the individual material sections may exist so that the material sections assigned to one another are generally symmetric but can deviate from one another.
The curtain airbag demonstrates a first material layer 2 and a second material layer, which are sewn along their external contour. To this end, the seam leaves open the region of the opening 23 so that a gas generator and/or a gas guide element can be inserted into the opening.
The chamber regions 5, 6 and 15 are delimited by dividing seams 7 and 17 so that two external and one central chamber are formed. In accordance with the preceding exemplary embodiment, the material sections 8, 10 and 9, 11 and 13, 14 assigned to one another are connected by seams, of which the seams 18 and 20 are visible here.
Because of the relatively high stresses when the gas enters, the centrally arranged chamber 6 is provided with a relatively heavy and therefore stable fabric, which can still be coated for extra reinforcement, whereas the external chambers 5 and 15 are manufactured out of plainer fabric to reduce weight and cost. Pursuant to one embodiment, a coated fabric having 700 dtex is chosen for the centrally arranged chamber, whereas an uncoated fabric in the range of 235 to 580 dtex suffices for the external chamber regions.
The invention described above is can of course also be applied to other types of airbags and should not be restricted to side airbags and curtain airbags.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2004 040 090.3 | Aug 2004 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP05/08129 | 7/27/2005 | WO | 00 | 11/15/2007 |
