[0001] The present invention is directed to fabrics used in the automotive industry in the production of car seats and accessory car seat covers, While the present invention will be described with reference to its use in car seat covers, it is to be appreciated that the invention is also applicable for use on the car seat itself.

BACKGROUND OF THE INVENTION

[0002] The use of airbags in cars and other passenger vehicles helps to reduce injuries and prevent death from the external collision, and also helps to limit passenger collisions with the inside of the car. Airbags were first introduced in passenger cars by Ford in 1971 to protect the driver and front passenger in frontal collisions. Since then, the number of airbags in modern cars has increased to 5 and in some cases even 9, covering a wide range of accident scenarios.

[0003] In recent years, the automotive industry has seen the introduction of car seat covers which are installed over the seats to protect the upholstery, Several manufacturers have introduced car seat covers with a vertical sift joined by an easily-rupturable seam known as a tear seam' in the side of the seat cove to allow the deployment of the integrated side afrbag. However, many of these seat cover designs have been identified as having reliability issues, especially during airbag deployment, due to several technical and design deficiencies,

[0004] Popular side airbag seat covers require a tear seam technology to allow deployment. In this mechanism, the side airbags generally depfoy by rupturing a moulded plastic enclosure in the seat, followed by bursting of the tear seam of any fitted seat cover, The tear seam within the car seat cover must not prevent the full deployment of the airbag. The airbag deployment is executed with an enormous force of 200 kPa, and a velocity of 200 - 320 km/hr. It is this force and velocity that are responsible for the seam tearing. This mechanism has been adopted commercially in most seat cover designs. However, the behaviour of tear seams in seat covers can be unpredictable. Several factors such as seat cover material, type of sewing thread used at the tear seam, length of the tear seam, placement of the tear seam, and the type of stitch, affect the behaviour of airbag deployment.

[0006] Various problems can impact seam tear performance such as;

(a) the occurrence of ballooning of the seat cover material prior to the failure of the seam. This increases the time taken for the airbag deployment and hence reduces the effectiveness of the airbags,

(b) the improper and unsafe deployment of the airbag due to minor faults present in the seat-cover materia! such as holes, tears, rips or snags, which cause the inappropriate and incomplete exit of the airbag.

[0006] It would therefore be advantageous to provide an alternative means to facilitate reliable airbag deployment in a car seat having an Integrated airbag.

SUMMARY OF THE INVENTION

[0007] According to one aspect of the present invention there is provided car seat fabric for facilitating reliable airbag deployment, the fabric including, at least one weakened failure zone within the fabric, wherein the failure zone is adapted to split and allow passage of an airbag therethrough when a force from expansion of the airbag is applied to the weakened failure zone.

[0008] The failure zone within the fabric may preferably be pre-treated using laser ablation to weaken the fabric at the failure zone. Alternatively, if the car seat fabric is of woven or knitted construction, then the failure zone may be woven or knitted with a relatively weak yarn. The weak yarn will have a tensile strength lower than the yarn used for the rest of the car seat fabric. For example, a thinner yarn may be used as the weak yarn compared with the yarn used for the rest of the fabric. [0009] The fabric may preferably also include a transfer print on the fabric over the failure zone, This facilitates identification of the location of the failure zone on the fabric. This will help to ensure that the car seat or car seat cover is correctly manufactured with the weakened failure zone located in the correct location over the side airbag deployment area.

[0010] The weakened failure zone may preferably be elongated in shape. This will facilitate in particular the production of car seat covers suitable for use on a variety of different car seats from different manufacturers. The elongate shape of the weakened failure zone will then hel to ensure that the car seat cover can take into account the variations in the location of the side airbag in different car seats, and will help to ensure that a part of the weakened failure zone is located over the airbag deployment area.

[0011] According to another aspect of the present invention, there is provided a car seat cover made from a fabric Including at least one weakened zone within the fabric, wherein the weakened failure zone Is located over an airbag

deployment area of a car seat when the car seat cover is installed thereon, such that the failure zone is adapted to split and alow passage of an airbag

therethrough when a force from expansion of the airbag is applied to the weakened failure zone,

[0012] A predetermined elongate pattern may preferabl be laser ablated to a side of the seat cover. The pattern may be in the form of a generally vertical strip extending along the side of the car seat cover when installed on a car seat. The strip may preferably be approximately 700mm in length and ?mm in width. The strip may be located at a gap of approximately 10mm to 20mm from a front edge of the car seat cover, and less than 50mm to 100mm from a bottom edge of the car seat cover when installed on the car seat.

[0013] According to a further aspect of the invention, there is provided a method of producing a car seat fabric for facilitating reliable airbag deployment, including manufacturing the fabric to include at least one weakened failure zone which is adapted to split and allow passage of an airbag therethrough when a force from expansion of the airbag is applied to the weakened failure zone

[0014] The method may preferably include pre-treaiing the fabric by laser ablation to weaken the fabric at the weakened failure zone. Alternatively, the method may include weaving or knitting the fabric using weak yarn at the weakened failure zone.

[0015] The method may also include applying a transfer print on the fabric over the failure zone. The method may further include forming the failure zone i an elongate shape.

[0016] The use of a weakened faiiure zone within the fabric itself eliminates the need to use conventional tear seam technology in the deployment of an integrated airbag thereby avoiding the various problems associated with such technology. The provision of a weakened failure zone within the fabric facilitates the full and timely deployment of side bags incorporated in a car seat. The force of deployment of the airbag is sufficient to break through the weakened failure zone within the fabric when located over the deployment area of the airbag on a car seat.

BRIEF DESCRIPTION OF THE DRAWING

[0017] It will be convenient to further describe the invention with respect to the accompanying drawings which illustrate a preferred embodiment of the method according to the present invention. Other embodiments of the invention are possible, and consequently, the particularity of the accompanying drawings is not to be understood as superseding the generality of the preceding description of the invention. in the drawings: [0018] Figure 1 is an image showing the surface of fabric that has been modified using laser ablation according to the present invention;

[0019] Figure 2 is a diagram showing details of the laser etching pattern;

[0020] Figure 3 is an image showing tearing of the surface of fabric that has been modified using laser ablation according to the present invention;

[0021] Figure 4 is a graph showing airbag deployment time vs laser ablation intensity; and

[0022] Figure 5 is a side view of a car seat cover support on a car seat, and the position of the laser ablated line with respect to an edge of the car seat cover.

DETAILED DESCRIPTION OF THE INVENTION

[0023] The ear seat fabric according to the present invention provides a novel means for ensuring optimal and reliable airbag deployment in a car seat having an integrated side airbag. This is achieved according to the present invention by providing a weakened failure zone within the car seat fabric itself eliminating the need for tear seam technology.

[0024] The weakened failure zone within the car seat fabric may preferably be formed by using laser ablation as a means of precisely defining the failure zone within the car seat fabric. Alternatively, the fabric ma be woven or knitted, and the weakened failure zone may be formed using weak yarns within the knitted or woven fabric construction to precisely define a failure zone within the car seat fabric.

[0025] The car seat fabric produced by the chosen yarn {preferably with a weight of 80 to 120 denier) may be laser ablated by an appropriately selected laser taking into account the following features such as wavelength, power, beam intensity, scanning rate, and time, m order to define a suitable ablation rate,

[0026] The fabric used for laser ablation In experiments conducted on behalf of the Applicant was knitted from 100 D textured polyester yarn that comprised of 36 monofilaments.

[0027] Laser ablation technologies may differ based on key parameters such as, power, speed, dpi, distance between the etching lines and depth of colour and are subject to change depending on the manufacture of the laser ablation technology,

[0028] According to one of the laser ablation method used , the failure zone on the fabric surface was created by weakening the fabric b laser ablation. The intention was to create a selective weakening of the fabric by ablating a section of the fabric with a specific pattern design. A Legend 36 EXT Epilog laser machine was used for this method . The fabric was positioned on the working table of the laser machine and a laser beam was concentrated on the fabric, A desired levelling of the beam was performed in order to get uniform ablation across the pattern design. The optimal conditions used for the developed fabrics were 100% speed and 40% power ablated at 400dpi using a K40 shade.

[0029] According to another laser ablation method using an alternative laser machine, ie a Dongtei Laser cutter. The required design was created using an Adobe illustrator 6, The height and width of the ablated patent design were 7mm and 740mm respectively. In order to create a continuous weakening zone, and to facilitate uninterrupted deployment of the airbag, a specific band pattern of 7mm by height was created. The optimal conditions used for the developed fabrics were 100 % speed and 13% at 0,5mm distance between etching lines.

[0030] The intensity of laser ablation using the alternative laser machine, was optimised by; 1. changing the scale of power incrementally from 1 to 20%; where higher the power more the intensity of ablation.

2. altering the speed on an incremental scale of 1%, from 1 to 100; where lower the speed more the intensity of ablation.

3. adjusting the distance between etching lines form 0,1mm to Q.5mm _r where lower the distance more the intensity of ablation,

4. modifying the depth of colour; grey colour shade ranges from K5 (iighter) to K60 (darker), the darker the shade, the more the intensity of ablation,

[0031] Figure 1 shows the surface modification on fabric after laser ablation. Figure 2 shows the dimensions of the ablation line pattern that was etched along the length of a side panel of a car seat cover. Tests were conducted on behalf of the Applicant by installing the car seat cover over a car seat having an internal side airbag,

[0032] The position of the ablation line pattern relative to the car seat cover is shown in Figure 5. Once the ca seat cover is installed on a car seat having an internal airbag, the laser ablation line position was as follows:

« A gap of less than 2cm should be provided between the laser ablated line and front edge of the seat cover along th length of edge till bottom of the car seat cover.

• The distance between end point of the laser ablated line and bottom edge of the side panel should be less than 10cm.

[0033] This thereby locates the ablated line over the location on the car seat where the airbag Is deployed following actuation. The airbag was then actuated to investigate the performance of the laser ablated failure zone on. the car seat cover that has been modified using laser ablation according to the present invention. Deployment of the atrbag resulted in a tear being propagated through the laser ablation line thereby facilitating reliable deployment of the side airbag.

[0034] Figure 3 shows the tearing at the laser ablated area following airbag deployment. Figure 4 is a graph that shows the effect that the laser ablation intensity applied to the fabric had on th airbag deployment time. The graph shows that ther is generally a reduction in the airbag deployment time with increasing laser ablation intensity.

[0035] In tests conducted on behalf of the Applicant, the bursting strength of the laser abiated area was reduced by 70% compared with the bursting strength of the fabric that has not been laser abiated. This resuits in improved reliability in the airbag deployment,

[0036] In an alternative aspect of the present invention, the car seat fabric may be provided by using one or more natural or synthetic yarns with thin and thick design structure in order to create the weakened failure zone,

[0037] Where used herein the term 'yarn' is intended to refer to one or more continuous, often plied fibres of natural or man-made materia! suitable for use in weaving and knitting to form fabric. The insert yarn should be of a lower tenacity than that of the body of the fabric.

[0038] The fineness of the fabric is dependent on the gauge of the knitting machine and the desired design of the seat cover.

[003S] The fabric used in the alternative aspect of the present invention was knitted from 100 D textured polyester yarn that comprised of 36 monofilaments. The weakened failure zone was created using a 30 D textured pofyester yarn that comprised of 24 monofilaments. [0040] Textured yarns were selected primarily for two reasons;

1 , when the fabrics are relaxed after knitting the textured yarns have the ability to add buikiness to the fabric and for this reason, when it is dyed it provides better colour coverage; and

2. a higher level of cover can be achieved with lowe fabric weight using textured yarns compared to non- textured yarns,

[0041 ] These yarns were fed in specific order during the knitting process (described below).

[0042] A 28 gauge Santons circular knitting machine with 8 feeders was used to make fabrics. The knitting machine was a single jersey weft knitting machine, The main body of the fabric system was knitted using 100 D polyester yarn which is technically stronger when compare to 30 D polyester yarn. The 30 D polyester yam was fed through one of the feeders, to knit 2 courses of the 30 D polyester yam. A diamond knit structure was used to produce the entire fabric system, The courses per cm and the ales per cm were set at 15 and 11 respectively. The fabric weight was 100 grams per square meter.

[0043] When compared with tear seam technology of the prior art the car seat fabric of the present inventio has up to 100% airbag deployment results and provides superior protection against damage from friction, cuts, scrapes, grazes resulting from motion related activity by passenger or driven Also the car seat fabric of the present invention has sufficient elasticity to provide a correct fit,

[0044] Modification and variations as would be deemed obvious to the person skilled in the art are included within the ambit of the present invention as claimed in the appended claims.