EXTENSIBLE FABRIC DESCRIPTION OF THE INVENTION
The present invention relates to an expandable fabric having first and second warp threads and first and second weft threads. It is known fabrics that are used for the production of air bags for people restraint systems and that are installed without coating. An air bag provided with such a cloth is inflated at once with an inflation gas in the case of application, the fabric being subjected to stretching due to the pressure in the air pocket arising therefrom with the consequence that the structure of the tissue is opened, that is, the permeability of the fabric increases by the separation of the tissue structure and the inflating gas can exit in the case of corresponding use. This can seriously affect the efficiency of the airbag, for example, by a slower deployment of the airbag due to the continued loss of air, with the consequence that the air cushion is ready with delay for the application and can unfold its protective action for a passenger with only a delay. It is also possible that the passenger may suffer health damages due to the exit of the inflating gas. Attempts have been made to counteract the greater loss of
inflate gas through more powerful generators. But this results in higher costs for the finished module. Another option to avoid the adverse consequences just described is to coat or laminate the fabrics for the air bags. This in effect makes it possible to produce a substantially better and almost optimum fabric in terms of air permeability. But the production costs for such a cloth rise immensely because of it. In principle, manufacturing in general becomes more extensive and, therefore, necessarily more critical because of the additional stage of production "coating or lamination". The invention is based on the objective of proposing a fabric that avoids or, at least, strongly reduces the disadvantages referred to and known from the state of the art. The objective is achieved firstly by a fabric according to claim 1. This fabric, having first and second warp yarns and first and second weft yarns, is characterized in that the first warp yarns and the first weft yarns form a woven fabric. The substrate and the second warp yarns together with the second weft yarns together form a covering fabric adjacent to the substrate fabric, the second warp yarns being woven together with the first yarns of the yarn.
the first weft threads and the second weft threads are laid out and arranged in such a way that they are located essentially side by side in an alternating manner when expanding the fabric, so that a second weft thread is always located next to a first one. raster thread. The inventive fabric offers the advantage that, if the fabric is used for the production of an air bag so that the two covering fabrics face each other, an air cushion can be manufactured such that the first air is produced. pressure exposure of the airbag with the gas by the generator in the respective covering fabric of the latter. The construction of the inventive fabric has the consequence that, upon receiving a load during the inflation of the air bag, the first warp yarns and the first weft yarns expand according to the load, pulling the second warp yarns in this way. second weft threads to the interstices between the first weft threads, created because of the expansion of the substrate fabric. They close thanks to this, as the pressure increases, the "holes" or "holes" in the fabric, simultaneously with its emergence, "covering" them by the second weft threads, which could be designated as sealing threads, thus avoiding an increase in air permeability or at least delaying it a lot. The consequence is that the
Inflation gas outlet thanks to the fabric that seals itself under load, respectively, retains its tightness. The objective is achieved, on the other hand, also by a fabric according to claim 2. This fabric with first and second warp yarns and first and second weft yarns is characterized, because the modulus of elasticity of the first warp yarns is more low that the modulus of elasticity of the second warp yarns, and because the second warp yarns are woven with a warp tension less than the first warp yarns, and because the first warp yarns are located in a substrate plane and the second weft yarns in a covering plane adjacent to the substrate plane, the first weft yarns and the second weft yarns being arranged in such a way that they essentially lie next to one another in an alternating fashion after expanding the fabric, so that always a second weft thread is located next to a first weft thread. The advantages of this inventive fabric are the same as those of the fabric according to claim 1. In the second fabric solution, however, a different behavior of the fabric occurs in the case of application of the inventive fabric in an air pocket. But the result is, in principle, the same as in the first fabric, namely, that the
The air permeability of the fabric during the application step does not increase and, consequently, it also does not significantly increase the exit of the inflating gas during the splitting and the necessary resistance time of the air bag. Thanks to the construction of the inventive fabric according to claim 2, a stronger warp of the second warp yarns is produced, since they have a higher modulus of elasticity compared to the first warp yarns and are knitted with a warp tension less. If, in the case of an application of the fabric in an air pocket, traction is applied to the fabric, then the first warp yarns having a lower modulus of elasticity are more stretched than the second warp yarns with the greater modulus of elasticity , so that the increasing distance between the first weft yarns under tensile load in the fabric is compensated because the second weft yarns, which are previously located in the coating plane, are arranged more or less in the increasing gaps between the layers. first weft threads, and the absolute distance between two adjacent weft threads remains approximately the same. In this way it is advantageously possible to keep the gap constant and thus also the air permeability between the warp and weft yarns, respectively, individually controlling on the load curve by
the gas pressure that occurs in the air bag. Throughout the description, first and second warp and weft threads are continuously referenced. It is emphasized that this does not refer exclusively to individual threads, but also multiple or bent threads, i.e. threads placed side by side multiple times. In the writing, v. gr., "a first warp thread" the word "a" has a functional sense, not a numerical one. The inventive fabric can be provided in both solution variants as a section, for example as part of the filter or gas outlet mechanism in an air bag, both made as well as in "one piece woven" air bags (OPW, for its acronym in English). It is also possible that the air bag consists entirely of such a fabric. It should be emphasized that it is possible to inventively apply yarns in the warp and / or weft direction with a different construction and / or material expansion on a fabric. This is not intended exclusively for use in vehicle passenger protection systems, but can be used in many fields of technical textiles. It is also possible inventively to use in the weft direction a strongly textured material for the first weft yarns (weave yarns) and to load
the first warp yarns (sealing yarns) with a very high warp tension, so that the second warp yarns (sealing yarns) are high during the production of the union of the substrate fabric, thanks to the ability to expand of the textured material, and thus are more likely disposed above the tissue rather than in the plane of the substrate fabric. The invention is explained below by means of examples with the help of figures 1 to 6 for a better understanding. Fig. 1 schematically shows a fabric of the state of the art in the non-loaded state. Fig. 2 shows schematically the fabric according to Fig. 1 in the loaded state, as it is presented in the case of application of an air bag. Fig. 3 schematically shows an embodiment of the inventive fabric in the unloaded state. Fig. 4 schematically shows the fabric according to Fig. 3 in the loaded state. Fig. 5 schematically shows a different embodiment of the inventive fabric in the no-load state. Fig. 6 shows schematically the fabric according to Fig. 5 in the loaded state.
Fig. 1 shows, with a sharp increase, weft threads 3 represented as circles which are interlaced by warp threads 1 and 2 in the usual manner of a L 1/1 taffeta weave, the distance between two threads being defined frame with the reference symbol 6. The upper representation in Fig. 1 shows a section through a fabric along a first warp yarn in which a first warp yarn 1 undulates by weft yarns 3. The lower representation of a section of a fabric known from the state of the art in taffeta weave shows a cut by the fabric along a second warp yarn 2. The distance 6 between the weft threads 3 (the behavior between the warp threads is the same) is given by the construction. Fig. 2 now shows the tissue sections according to Fig. 1 in the loaded state, ie, for example, in case of application of the fabric in an air pocket, during or after it has been inflated. The loading of the air bag (not shown) with gas by a generator (not shown) and / or the immersion of a passenger in the airbag cushion produces a tensile load of the fabric, so the distance 6 between the weft threads -in Fig. 2 the reference symbols are provided for the state loaded in each case with a small a- increases. The
distance 6a is greater than distance 6, and the weft yarns in position 3a have, correspondingly, greater distances. The aforementioned increase in distance 6a between the weft threads 3a causes an increase in air permeability through the fabric. There is an expansion of the construction and the substance. In the course of substance expansion the yarns (warp yarns and weft yarns) also become thinner. Fig. 3 now shows an embodiment of an inventive fabric in which first weft threads 13 and second weft threads 15 (so-called sealing threads) are placed on top of them. Analogously to the representation of Fig. 1 and 2, again the upper part of Fig. 3 shows the weft insertion of the first 13 and second 15 weft yarns in relation to the warp yarns 11 and 14. In this case, the first weft threads 13 form a substrate fabric 17 on top of which an adjacent covering fabric 19 is arranged, which is not really "authentic". The lower representation of Fig. 3 shows warp threads 12 and 14. As can be clearly seen in FIG. 3, the first warp threads 11 and 12 undulate only by the first weft threads 13, while the second warp threads 14, which here practically have the function of a weft yarn, link the second frame threads 15
with the substrate fabric 17, forming a covering fabric 19. The second weft threads 15, that is, the sealing wiresare not arranged in this, but rather on top of the substrate fabric 17 and form a "cover fabric" 19. In fact, the cover fabric 19 is not a fabric of its own, but a region 19 of fabric, superimposed on the substrate fabric 17, that being represented by the weft yarns 15 and the second warp yarns 14 (weave yarns). While the fabric according to Fig. 3 is shown in the unloaded state, Fig. 4 now shows the fabric of Fig. 3 in the loaded state. The first and second warp threads 11, 12 have been stretched under the load extending in Fig. 4 to the left and right. The distance between the weft threads 13a has increased to the extent 16a, and the interstice between the threads 13a the second weft threads 15a (sealing threads) are pulled by the weft threads (the second warp threads 14a) to the threads. interstices 16a. Thanks to this, it is possible to keep the gap between the yarns constant and to keep the air permeability of the cloth even in the charged state almost constant with it. Thanks to the particular construction of the inventive fabric it is now possible to reduce the gap 16, which arises with stretching under load, as the
loading, and thereby also keeping the air permeability between the yarns of the fabric constant, by pre-adjusting the length of the second warp yarn (weft yarn 14) by the weft yarns 13 and 15, or increasing it as required the requirements, respectively, to be controlled individually by the load curve. It is thus possible, for example, to set the narrowest distance in each case in Fig. 3 and 4 of two sealing weft yarns (in Fig. 3 the distance 16 and in Fig. 4 the distance 16b). In the embodiment shown here by way of example, the distance in Fig. 3 between two weft threads 13 (= distance 16) remains equal to the distance 16b in Fig. 4 between two weft threads 13a and 15a. In this case an air permeability is assumed that remains constant. If a longer length of the second warp yarn 14 (weft yarn) of the variant shown in Fig. 3 is selected, then a distance 16b greater than the distance 16 according to Fig. 3 is presented, with a load of the fabric analogous to the representation according to Fig. 4. In the knitted construction according to Fig. 3 the distance between the fabric layers 17 and 19 would then be in each case larger. Conversely, the distance between the fabric layers 17 and 19 could also be reduced, which would result in the distance 16b being smaller than the
distance 16 according to Fig. 3 in a load on the fabric analogous to Fig. 4, and thereby reducing the air permeability as the load is reduced. Of course, it is possible to apply the fabric construction described in FIGS. 3 and 4 also in an inverted direction, that is, by exchanging the warp and weft yarns. For this purpose, for example, a strongly textured material for the weft yarns could be used in the weft direction and the analogous sealing yarns loaded with a very large warp load, so that the sealing yarns are high during the production of the union of the substrate fabric, thanks to the stretchability of the textured material, and are therefore arranged rather above the fabric (covering fabric) than in the fabric. Fig. 5 now shows a second embodiment of an inventive fabric in the non-loaded state, having a similar behavior as in the first embodiment, but without separate weave and sealing yarn. According to FIG. 5, two different warp yarn materials are used, namely first warp yarns 21 and second warp yarns 24, the second warp yarns 24 having a higher modulus of elasticity compared to the modulus. of elasticity of the first warp threads 21. Is according
already shown from the representation according to FIG. 5, the second warp yarns 24 are woven with a warp tension smaller than the first warp yarns 21. In this way, a weaving situation occurs in which the first weft threads 23 are located in a substrate plane 27 and the second weft threads 25 in a covering plane 29. The first warp yarns 21 with a lower modulus of elasticity compared to the second warp yarns 24 are prepared with a warp tension for the production of the fabric, and the second warp yarns 24 with a modulus of elasticity, which is greater that the modulus of elasticity of the first warp yarns 21 are prepared with a lower warp tension, compared to the first warp yarns 21. Because of this, it occurs in the state of the fabric shown in FIG. 5, in which the second weft threads 25, so to speak, rest on the first weft threads 23 and a covering plane 29 is presented which supports on a substrate plane 27. Fig. 6 now shows the fabric according to Fig. 5 in the loaded state. With an equal absolute load on the fabric, the first warp yarns 21a with the lower modulus of elasticity are stretched more than the second warp yarns 24a with a greater modulus of elasticity, so that the incremental distance (26 becomes
26a) between the first weft yarns 23a under tension load on the fabric is compensated because the weft yarns 25, located first on top, are placed in the recesses 26a that grow according to the load more or less, and the absolute distance 28 between two adjacent weft threads 23a, 25a remain the same. In this way it is possible to keep the gap 26/28 almost constant and thus also the air permeability between the weft yarns. In an advantageous embodiment of the invention, a fabric is woven, v. gr., as shown in Fig. 6, which is characterized in that it is woven in the non-loaded state with the same undulation of the first warp threads 21 and the second warp threads 24, the material expansion being of the second warp yarns. yarns 24, 24a of warp greater than the material expansion capacity of the first warp yarns 21, 21a. Advantageously, in this fabric, the second weft threads (sealing threads 25) can be raised in the loaded state of the plane of the first weft threads because of the different material expansion capacities of the warp threads. The distance can also be increased or reduced, however, in comparison with the unloaded fabric of Fig. 5. The inventive construction allows the air permeability to rise in a
overproportional if a fabric similar to the fabric is knitted according to Fig. 6, that is, with the same undulation of the warp threads 21 and 24, now in the non-loaded state. But the second weft yarns (sealing threads 25) can be raised, because of the different expansion capacity of the material (the material expansion of the second warp yarns 24, 24a is greater and the material expansion capacity of the first yarn 21, 21a of smaller warp), in the state of loading of the plane of the first weft threads 23 (analogously to the representation of Fig. 5, but with an even greater distance of planes 27 and 29, but in a loaded state ). In a further advantageous development of the invention, a fabric is proposed in which the contour of the expansion curve is individually adjusted, which is characterized in that it has predetermined warp yarns and weft yarns with parameters, such as moduli of elasticity, deliberately selected or also in a deliberately selected sequence. By means of fabric constructions of the inventive fabrics described, it is also possible to adjust other technical parameters individually, such as, for example, the contour of the expansion curve, which consequently also influences, for example, the splitting behavior of the bags. air through sections of
fabric that expand more or less or individually. In this way, it is possible in the future to adjust independently, thanks to these intelligent fabrics, the tissue parameters dependent on each other because of the construction. Reference symbols 1, First warp yarn 2, 2a First warp yarn 3, 3a Weft yarn 6, 6a Distance 11, First warp yarn 12, 12a First warp yarn 13, 13a First weft yarn 14, 14th Second warp yarn (weave thread)
15, 15a Second weft thread (sealing thread)
16, 16a Distance 16b Distance 17 Substrate fabric 19 Covering fabric 21, 21a First warp yarn 23, 23a First weft yarn 24, 24a Second warp yarn 25, 25a Second weft yarn (sealing yarn)
26, 26a Distance 27 Substrate plane
Distance Flat coating
5
10
fifteen
twenty
25