WO2007100377A1

WO2007100377A1 - Woven airbag with integrally woven tethers

Info

Publication number: WO2007100377A1
Application number: PCT/US2006/048220
Authority: WO
Inventors: Xiaofeng Ma
Original assignee: Key Safety Systems, Inc.
Priority date: 2006-02-27
Filing date: 2006-12-19
Publication date: 2007-09-07
Also published as: US20070200329A1

Abstract

A woven airbag (20) has separable fabric layers (40, 42) that are integrally woven together at selected locations using warp threads (82) and weft threads (80). One or more integrally woven tethers (70, 70a) extend between the fabric layers at selected locations. Each tether is formed of a plurality of threads (72, 72a). The tether threads (72, 72a) can be either additional threads, different from the warp or weft threads, additional warp threads, additional weft threads or any combination thereof.

Description

WOVEN AIRBAG WITH INTEGRALLY WOVEN TETHERS

The present invention relates to airbags and in particular woven airbags.

Fig. 10 is a prior art curtain airbag 200. Fig. 11 is a cross-section view of the prior art airbag 200 taken along line 11 - 11 of Fig. 10. Many airbags including curtain airbags are divided into inflatable and non-inflatable regions. The non-inflatable regions limit the inflatable volume of the airbag, permitting the use a smaller capacity inflator. Historically, the non-inflatable regions were realized by sewing together the opposing panels of fabrics forming the airbag. Non-inflatable regions have also been produced in integrally woven airbags by inter-weaving the weft or fill threads of the opposing panels. The largest of the non-inflatable regions is typically located at, or behind the B-pillar of the vehicle because a vehicle occupant will not often interact with this non-inflatable region. Other non-inflatable regions control the shape and volume of the inflated airbag. Another type of volume control in an airbag uses a tethering concept in which the distance between opposing panels of the airbag is controlled by a strap or tether. Tethers that are physically sewn into the airbag as disclosed in US 6 886 858 B2 and interwoven tethers are disclosed in US 6 296 276 B1.

One of the deficiencies in forming a tether by interweaving is that a number of weft or warp threads are caused to move from one panel to the other forming an X-shaped cross-link. This construction causes a lessening of the threads and a diminishing of the strength of the airbag between the legs of the X-shaped cross-link. This deficiency is corrected in a woven airbag according to claim 1 and the claims depending from claim 1.

A woven airbag according to the present invention has at least one inflatable chamber. A fabric layer is integrally woven using warp threads and weft threads. The fabric layer has an inner side and an outer side. One or more chamber boundary regions are located where two fabric layers are woven together. One or more tethers are made of a plurality of threads, the threads being either additional threads that are different from the warp or weft threads, additional warp threads, additional weft threads or any combination thereof. The tethers are located in the inflatable chamber and are woven into the fabric along two or more localized woven attachment locations. The woven fabric layer has the same number of warp threads per centimeter and weft threads per centimeter throughout the fabric layer except at the localized woven tether attachment locations and the chamber boundary regions.

Fig. 1 is a plan view of an inflated head or side airbag of the invention.

Fig. 2 is a cross-section of the inflated airbag taken along line 2-2.

Fig. 3 shows a weaving loom adapted to form the airbag of Fig. 1.

Fig. 4 shows a portion of the airbag illustrating the weaving at a first boundary region and tether attachment.

Fig. 5 shows the portion of the attachment location and the tethers.

Fig. 6 shows the attachment location wherein the tether from the lower fabric layer crosses and attaches to the upper fabric layer.

Fig. 7 shows an alternative attachment of the tether.

Fig. 8 shows another alternative attachment of the tether.

Fig. 9 shows an alternative embodiment airbag according to the invention.

Fig. 10 is a prior art curtain airbag.

Fig. 11 is a cross-section of the prior art airbag taken along line 11 - 11.

Fig.'s 12A, 12B, 12C, 12D and 12E show alternative embodiments.

A woven airbag has at least one inflatable chamber, and preferably more than one inflatable chamber when used as a side curtain airbag. The airbag has a fabric layer integrally woven using warp threads and weft threads. The fabric layer has an inner side and an outer side. The fabric layer has a first, front or top layer or panel, and a second, rear or bottom layer or panel. Attached to the fabric layer are one or more tethers. The tethers comprise a plurality of tether threads. The tether threads can be either additional threads, different from the warp or weft threads, additional warp threads, additional weft threads or any combination thereof. The tethers are located in the inflatable chamber and attached to chamber walls by being woven into the fabric along two or more localized woven attachment locations. Around the inflatable chamber are one or more chamber boundary regions where two fabric layers are woven together. The woven fabric layer has the same number of warp threads per centimeter and weft threads per centimeter throughout the fabric layer except at the localized woven tether attachment locations and the one or more chamber boundary regions.

Fig. 1 shows an inflated side curtain airbag 20 according to the present invention, which typically extends in the inflated state in the vehicle from the A to B pillars, A to C pillars or A to D pillars depending on the vehicle. In a typical side curtain airbag extending from the A to C pillars of a vehicle, the airbag extends from the A pillar across the B pillar and continues from the B pillar to the C pillar and completely covers the side windows of the vehicle. In the inflated state the side curtain airbag 20 has a woven fabric that includes two fabric layers or panels 40, 42, which is shown in cross section in Fig. 2. The fabric layers or panels 40, 42 form the outer walls of the side curtain airbag. The fabric layers or panels 40, 42 comprise warp and weft threads 82, 80. In Fig. 1 several weft threads 80 and warp threads 82 are shown.

In Fig. 1 the side curtain airbag 20 has one or more inflatable chambers 50. The illustrated side curtain airbag 20 comprises a plurality of inflatable chambers 50a - 50c, which are connected to one another through internal flow passages 54. The two fabric layers or panels 40, 42 are interwoven into one piece in the boundary regions 60, 62 of the side curtain airbag 20. The boundary regions 60 lie around the perimeter of the side curtain airbag 20 while the boundary regions 62 are partitions separating the inflatable chambers 50a - 50c. The side curtain airbag 20 may be coated on the outside of both fabric layers, or panels, 40, 42 by a film 41 that lessens the permeability of the woven fabric and in some applications ensures that the side curtain airbag is gas-tight, which is especially useful in a vehicle rollover event. Fig. 2 is a cross-section of the inflated airbag taken along line 2-2 of Fig. 1 and illustrates how the region of each inflatable chamber 50 of the side curtain airbag has only a small thickness and bulges outward only slightly. In each inflatable chamber 50a, 50b, 50c there is arranged at least one strap or tether 70 that limits the fabric layers or panels 40, 42 movement away from each other. The tethers 70 are formed by non-connected or non- woven tether threads 72 that, as shown, extend in the direction of the warp threads 82 of the fabric layers or panels 40, 42, which depart from the fabric woven borders 62 and extend over a predetermined length under each panel and finally go back into the fabric of the original (i.e. their corresponding) fabric layer or of the opposite fabric layer. The tethers 70, 70a and tether threads 72, 72a are integrated into one of the fabric layers or panels 40, 42 and transition to the other fabric layer.

Fig. 1 shows, by way of example, several weft threads 80 and warp threads 82, which are interwoven and crisscross each other to form the first or upper fabric layer 40 in a conventional manner. The second or lower fabric layer 42 includes another set of weft and warp threads 80, 82 respectively. Layer 40 also includes a set of tether threads 72 and layer 42 includes another set of threads 72a. Each of the tether threads 72, 72a is integrated into the fabric layers or panels 40, 42 and is interwoven with weft threads 80. In, for example, a section y of the boundary region 60 the warp threads 82 and tether threads 72 of the fabric layers 40, 42 are woven about the same weft threads 80. Similarly, also in this location y, the warp threads 82 and the tether threads 72a are woven about the same weft threads 80. In the tethered inflatable chambers 50a - 50c the tether threads 72 can depart from the fabric 40 at the attachment location x and extend at an angle, when inflated and viewed in cross section, toward the opposite fabric layer 42 to which they then are attached at a location z¹ by being woven into the fabric layer 42. At a location x¹ the tether threads 72a depart from the fabric layer 42 and extend at an angle toward the opposite fabric layer 40 into which they then go toward a location z and are attached by interweaving. The inflatable chamber 50a, when viewed in cross-section, shows the tether threads 72, 72a form an "X." The tether threads 72, 72a lie adjacent to one another in the flat or uninflated side curtain airbag within a region defined by the "X" and are not connected to each other in this region. Since only individual tether threads 72, 72a extend from the fabric layers or panels 40, 42 no partition is created. The tethers 70, 70a extend generally linearly and parallel to the warp threads 82 over almost the entire length of the side curtain airbag 20 in the uninflated airbag.

Instead of the tether thread running parallel to the warp threads 82, the tether thread can be configured to run parallel to the weft threads 80, but this is not the most efficient use of the loom.

In Fig. 3 a side curtain airbag 20 of the present invention is formed using a modified Dobby Loom 100. The exemplary loom 100 has the weft threads 80 traveling in the direction shown and the warp threads 82 traveling perpendicularly relative to the weft threads. A separate beam 102 parallel to the warp threads 82 is provided to feed the tether threads 72, 72a to form the tethers 70, 70a. The choice of weaving equipment can be varied. The tether threads 70, 70a can be the same material as the weft and warp threads, which facilitates simply locally increasing the number of threads in the locations of the tether on either from the weft package 104 or on the warp beams 106. In this method of manufacture the modifications to the equipment can be minor or simply not required. In practice, if the tether threads 72, 72a are different from either the warp or weft threads, the use of a separate feed or creel arrangement on beam 102 may be more practical as is shown in the Fig. 3.

In the locations of the tether 70, 70a as the fabric panels 40, 42 are being assembled, especially in the case where many tether threads are needed to form a strong tether, the thread number of the beam 106 is locally increased. This causes some difficulty in keeping the beam surface flat when threads are being wound onto the beam during beaming process. The use of separate tether feed beams 102 seems desirable. The beams 102 can be above, below, in front of or behind the beam 106 of the parallel warp threads being loomed. The threads 80, 82 of woven airbags typically comprise synthetic polymeric yarns such as polyamide, polyester, and polyolefins, such as polyethylene and polypropylene. Other fibers such as aramid, carbon, glass and ceramic, as well as material fibers appropriately treated can be used. The tethers 70 can comprise threads 72 using any of these materials, but are not necessarily limited to yarns commonly used in woven airbag fabrics. As long as the tether threads 72, 72a can be woven into the fabric, the tether threads can be made from virtually any material. The advantage of this is that various distinct properties can be utilized that enhance the strength, the elongation resistance and heat resistance of the tether yarns or threads 72, 72a without degrading the woven airbag fabric 40, 42 performance. In one embodiment of the invention the woven fabric layers 40, 42 may have warp and weft threads 82, 80 having a percent elongation which is less than the percent elongation of the tether threads 72, 72a. In such a configuration the tether threads 72, 72a will have more resiliency than the woven weft and warp threads. This will enable the stretch in the tethers to absorb some of the energy of inflation by stretching prior to pulling on the woven fabric at attachment locations x, x¹, y, y\ z or z¹. These and other arrangements of tether thread are made possible by not limiting the tether threads to be the same as the woven weft threads 80 or warp threads 82.

In one example a woven side curtain airbag 20 in accordance with the present invention was made with fabric layers 40, 42 woven together using warp threads 82 of 420 denier no-twist nylon 66 yarn and weft threads 80 of 420 denier no-twist nylon 66 yarn; each of the warp and weft threads used 18 ends per centimeter. Each fabric layer 40, 42 had an inner side 43 and an outside 45.

Tethers 70, 70a were used in the construction of the side curtain airbag 20 of Figs. 1 and 2. One or more tethers 70, 70a were made of a plurality of threads 72, 72a. The side curtain airbag 20 was tested using tether threads 72, 72a of 630 denier and 840 denier twisted nylon 66 in the warp direction. In each case the tethers had 4 ends per centimeter and in total used 96 ends or threads 72, 72a; the 630 denier threads having a strength of 5338 Newtons while the 840 denier threads had a strength of 6939 Newtons. The tether threads72, 72a were different from the warp threads 82 of 420 denier and different from the weft threads 80 of 420 denier. The tether threads 72, 72a were woven into the fabric layer 40, 42 at two or more attachment locations x, x\ y, y\ z or z¹ and extended internally of the formed inflatable chambers 50a - 50c.

The tethers 70, 70a could comprise a plurality of threads 72, 72a that are either additional warp threads 82, additional weft threads 80 or any combination thereof, which are preferably located inside the inflatable chambers 50a - 50c and attached thereto at two or more attachment locations x, x¹ and z, z¹.

In a side curtain airbag 20 according to the present invention, the woven fabric can be made with the same number of warp threads 82 having a given number of threads per centimeter and the same number of weft threads 80 having a given number of threads per centimeter, typically 20 - 40 threads per centimeter throughout the fabric layers 40, 42 except at the woven tether attachment locations x, x¹ or z, z¹ and at the boundary regions 60, 62. The boundary regions 60, 62 are made of the two fabric layers interwoven, similarly having double the number of threads per centimeter in both the weft and warp directions except at attachment locations y, y¹ wherein the tether threads 72, 72a are positioned. In those attachment locations the tether thread count per centimeter increased locally the warp or weft thread count. The fabric layers 40, 42 can have virtually any thread count sufficient to meet the side curtain airbag performance standards and the use of 20 or less threads per centimeter can be employed when used with appropriate coating films 41.

In Fig. 2 various attachment x, x¹, y, y¹, z, z¹ locations are shown.

Fig. 4 shows a portion of an airbag illustrating the weaving at a first boundary region and tether attachment. In Fig. 4 at the location marked y the two fabric layers are woven together making a boundary partition region 62 between two adjacent inflatable chambers. In this boundary region 62 there is a doubling of the weft and warp threads 80, 82. At one or more locations y, y¹ approximating the width of a tether 70, 70a additional tether threads 72, 72a pass, crossing the boundary partition region 62. Threads 72a from a first tether 70 are interlaced into the partition region 62 and then pass along the inside of the top fabric panel toward an attachment location x. Threads 72 from a second tether 70a are also interlaced into this partition region 62 and pass across it at the same location or at a different location and then pass along the inside of the lower fabric panel towards an attachment location x¹. In these locations the tether threads 72, 72a need not be woven into the fabric layers 40, 42, but simply pass alongside until they are attached as shown in Fig. 5 by being woven into a fabric layer across one or more weft or warp cords 80, 82, depending on the orientation of the tethers 70, 70a. The tethers 70, 70a are running parallel with the warp cords 82 and thus are interlaced with the weft cords 80 at the locations x and x¹.

In Figs. 2 and 5, at the attachment locations x the first tether 70 departs from the top fabric layer and the second tether 70a similarly departs from the lower fabric layer at location x\ each tether 70, 70a extending to the opposite fabric layer to a second attachment location z or z¹ respectively. At the second attachment location z or z¹ the threads 72, 72a of the tether 70, 70a are again interlaced with the weft cords 82 to secure the tether 70, 70a. Between the attachment locations x, z¹ and x\ z the tether threads 72, 72a span across the two fabric layers and thus can limit the amount the two fabric layers can spread apart upon inflation. In Fig. 2 the first tether threads 72 and the second tether threads 72a cross to form an "X" pattern inside an inflation chamber. The tether threads 72 or 72a, once attached at the attachment locations z and z¹, can freely extend inside the inflatable chamber formed by the two opposing fabric layers until it gets to the next boundary partition region 62 at y¹.

In Fig. 7 an alternative method of weaving the tethers 70, 70a is shown wherein the threads 72, 72a of the tether can be interlaced not only at the attachment locations y and x and y and x\ but also all the way in between y to x or y to x¹. The tether 70, 70a itself would be a woven member as opposed to simply lying free inside the adjacent fabric layer. This arrangement can occur as well crossing each boundary region 62 including z to y¹ and z¹ to y¹ as well.

In Fig. 8 another alternative has the threads 72, 72a of the tether 70 or 70a attached to the fabric layer 40, 42 between attachment locations y and x or y and x¹ at one or more points 74 and, as before, this use of point attachments 74 can be used between each attachment location and a boundary region 62 in z to y¹ and z¹ to y¹.

In each of these alternatives the fabric layer 40, 42 is never reduced in thread count, but may have increased thread counts because of the addition of the tether threads at or optionally between the various attachment locations x, x\ y, y\ z, z¹.

In Fig. 9 another alternative embodiment is illustrated wherein the first tether 70 and second tether 70a cross at two locations 75, 76 inside a single inflatable chamber. The tethers 70, 70a form two crossovers in the shape of two "X's."

In the alternative configurations shown in Figs. 12A, 12B₁ 12C, 12D and 12E, one or more tethers 70, 70a are oriented between tether attachment locations to extend across an inflatable chamber in the form of an "I", "U", "V", "X", "Y" or "W" to provide the restraint needed to keep the fabric layers from separating too far. In the locations wherein the tethers depart the fabric layer 40, 42, it is further possible to weave the tether threads 72, 72a together at a simple point location or across the entire transition between layers. This interweaving can further enhance the tether strength if that is deemed desirable.

Claims

CLAIMS:

1. A woven airbag (20) comprising: first and second fabric layers (40, 42) woven to one another and comprising warp threads and weft threads (82, 80), the fabric layers (40, 42) each having an inner side and an outer side; boundary regions (60, 62) where the two fabric layers (40, 42) are woven together; at least one inflatable chamber (50a, 50b, 50c) defined by the fabric layers (40, 42) and boundary regions (60, 62); at least one tether (70, 70a) made of a plurality of tether threads (72, 72a), the tether threads (72, 72a) being either additional threads different from the warp or weft threads (82, 80) of the fabric layers (40, 42), additional warp threads (82), additional weft threads (80) or any combination thereof which are located in an inflatable chamber (50a, 50b, 50c) and woven into at the fabric layers (40, 42) at two or more tether attachment locations (x, x¹ , y, y\ z, z¹); and each fabric layer (40, 42) has the same number of warp threads (82) per centimeter and weft threads (80) per centimeter throughout the fabric layer (40, 42) except at the tether attachment locations (x, x¹, y, y¹, z, z¹) and the boundary regions (60, 62).

2. A woven airbag (20) according to claim 1 wherein a first tether (70, 70a) extends across the inflatable chamber (50a, 50b, 50c) from a first tether attachment location (x, x\ y, y\ z, z¹) on the first fabric layer (40) to a second attachment location (x, x\ y, y\ z, z¹) on the second fabric layer (42).

3. A woven airbag (20) according to claim 1 wherein a second tether (70, 70a) extends across the inflatable chamber (50a, 50b, 50c) from a first tether attachment location (x, x\ y, y\ z, z¹) on the second fabric layer (42) to a second tether attachment location (x, x¹, y, y¹, z, z¹) on the first fabric layer (40).

4. A woven airbag (20) according to claim 1 wherein the tether threads (72, 72a) are woven together to one another along the entire lengths of the tethers(70, 70a).

5. A woven airbag (20) according to any of claims 1 - 4 wherein one or more tethers (70, 70a) are oriented between tether attachment locations (x, x¹, y, y\ z, z¹) to extend across an inflatable chamber (50a, 50b, 50c) in the form of an "I", "U", "V", "X", "Y" or "W".

6. A woven airbag (20) according to any of claims 1 - 4 wherein one or more tethers (70, 70a) have a tether attachment location (x, x\ y, y¹, z, z¹) at a boundary region (60, 62) and departs from on of the fabric layers (40, 42) adjacent the inner side of the fabric layer (40, 42) to another tether attachment location (x, x\ y, y¹, z, z¹).

7. A woven airbag (20) according to any of claims 1 — 4 wherein one or more tethers (70, 70a) are interwoven with the fabric layers (40, 42) between and including a boundary region (60, 62) to one of the tether attachment locations (x, x\ y, y\ z, z¹).

8. A woven airbag (20) according to any of claims 1 - 4 wherein one or more tethers (70, 70a) have tether attachment locations (x, x¹, y, y¹, z, z¹) at a boundary region (60, 62) and are interwoven with one or more weft (80) or warp cords (82) of one of the fabric layers (40, 42) between the boundary region (60, 62) and another tether attachment location (x, x\ y, y¹, z, z¹).

9. A woven airbag (20) according to any of claims 1 — 4 wherein the tether threads (72, 72a) extend or run substantially parallel to the warp threads (82) of one of the fabric layers (40, 42) and are interwoven around the weft threads (80) of one of the fabric layers (40, 42) at the tether attachment locations (x, x¹, y, y\ z, z¹).

10. A woven airbag (20) according to any of claims 1 - 4 wherein the tether threads (72, 72a) extend or run substantially parallel to the weft threads (80) of one of the fabric layers (40, 42) and are interwoven around warp cords (82) of one of the fabric layers (40, 42) at the tether attachment locations (x, x¹, y, y¹, z, z¹).