Stock material or miscellaneous articles – Structurally defined web or sheet – Including stitching and discrete fastener – coating or bond
Reexamination Certificate
2000-05-17
2003-10-07
Juska, Cheryl A. (Department: 1771)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including stitching and discrete fastener, coating or bond
C428S012000, C428S577000, C428S033000, C428S034100, C428S034300, C428S034500, C428S034600, C428S034700, C428S035200, C428S035700, C428S035900, C428S036100, C428S059000, C428S061000, C428S066400, C428S066600, C428S066700, C428S068000, C428S069000, C428S121000, C428S130000, C428S131000, C442S064000, C442S065000, C442S066000, C442S164000, C442S168000, C280S728100, C280S743100
Reexamination Certificate
active
06630220
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to inflatable automotive vehicle safety restraint devices such as air bags, side air curtains or the like. More particularly, the invention relates to a process that combines sewing and thermoplastic fusion of knitted, woven and non-woven coated textile fabric in the manufacture of these safety devices. When the coated textile fabric is sewn and heat sealed in the process, a portion of the coating material flows into the stitch holes and seals them, thus providing a strong, airtight air bag structure. The process also provides a means for an improved, more efficient and semi-continuous manufacturing process for stitching and sealing the air bags and side air curtains.
2. Description of the Related Art
Present safety restraint devices for automotive vehicles include driver and passenger side air bags that are rapidly inflated by a gas—sometimes referred to herein as “air”—which is produced by explosion of a pyrotechnic material at the time of a collision. The devices provide a protective barrier between the vehicle occupants and the vehicle structure. Much of the impact of a collision is absorbed by the air bag, thus preventing or, in many cases, lessening the possibility of serious bodily injury to the vehicle occupants. Air bags are typically stored in a collapsed, folded condition in the steering wheel to protect the driver, and in the dashboard to protect a front seat passenger., The automotive industry has recently introduced side air bags that are stored in the back of the front seats or in the rear seats to protect the cabin occupants in the event of a collision occurring on either side of the vehicle. More recently still, a further safety feature that has been made available for passenger vehicles, especially the so-called sport utility vehicles (SUVs), and minivans, is the side-impact protective inflatable side air curtain that is designed to provide a cushioning effect in the event of side collisions or rollover accidents. These side air curtains are stored uninflated along the roof of the vehicle or in one of the main support pillars of the vehicle. In the event of a collision the side air curtain deploys along the interior side walls of the vehicle cabin, protecting the occupants from serious bodily injury from contact with the vehicle structure and from broken glass.
Each of these various types of air bags has different design and physical property requirements, such as gas (air) holding permeability, air pressure and volume, and puncture resistance. For example, driver and front passenger air bags, which inflate and deflate almost immediately thereafter, must have little or no permeability; passenger side air bags require a controlled permeability. Side air curtains, on the other hand, must retain air pressure for relatively longer periods of time than other types of air bags. Moreover, all vehicle air restraint devices must have superior packageability and anti-blocking properties. Packageability refers to the ability of a relatively large device such as an air bag to be packed in a relatively small space, such as within a steering wheel or within a vehicle support pillar. Anti-blocking properties refers to the ability of the device to deploy instantaneously when needed without any resistance caused by the material sticking to itself, particularly after being stored for relatively long periods of time. These and other physical properties are determined in large part by the type of fabric and weave used in the air bag, whether the fabric is knitted, woven or non-woven, and, importantly, the nature of the coatings that are used on the fabric.
The air holding capability of side air curtains is critical since they must remain inflated for extended periods of time to protect passengers in multiple rollover accidents. Unlike air bags, which are designed to inflate instantaneously and to deflate almost immediately after inflation to avoid injury to the driver and front seat passenger, side air curtains used in SUVs, or in ordinary passenger vehicles must be capable of remaining inflated from about 3 to about 12 seconds depending upon the size of the air curtain and the size and type of vehicle involved. An average passenger vehicle would require a side air curtain of from about 60 inches to about 120 inches in length measured along the side of the vehicle. A larger vehicle, such as a minivan, would require an even longer side air curtain. The inflation period of a side air curtain should be sufficient to protect the cabin occupants during at least three rollovers, the maximum usually experienced in such. incidents.
When side air curtains are deployed they may be subjected to extreme pressures within a relatively broad range depending upon their specific location or application. For example, air bag deployment pressures are generally in the range of from about 50 kilopascals (kpa) to about 450 kpa, which corresponds generally to a range of from about 7.4 psi (pounds per square inch) to about 66.2 psi. Since sewing or stitching is used in the manufacture of the air bag structure, air can easily escape at these pressures through the stitch holes unless the stitches are sealed or fused by RF welding or other types of sealing.
Accordingly, there is a need for fabric products and methods of construction for air bags that will be relatively impermeable to fluids under such anticipated pressures while also being relatively light in weight.
One means of improving air holding capability in vehicle restraint devices has been through coatings such as chloroprene and silicone rubber coatings applied to a textile (e.g., nylon) fabric. U.S. Pat. No. 5,110,666 discloses a woven nylon fabric coated with polyurethane to provide the desired permeability and retention of inflation gas. Nevertheless, wherever coated fabrics are used the problems of controlling air permeability, air pressure, and volume remain. Insufficiency of adhesion of the coating material to the textile fabric substrate also is a serious problem that must be addressed. For example, the smoother the textile fabric surface generally the more difficult it is to obtain strong adhesion of the coating material to the fabric. With some coatings such as silicone rubber (polysiloxane), radio frequency (RF) heat sealing techniques cannot be used to form the air bag because this material will not flow at heat sealing temperatures. In such instances, air bags are usually made by stitching, a process that requires the addition of an adhesive sealant in the stitched areas. Even so, leakage of air occurs at the stitching, which lessens the protective capability of the air bag.
U.S. Pat. No. 5,863,644 discloses woven or laid structures using hybrid yams comprising reinforcing filaments comprised of thermoplastic polymers to form textile sheet materials of adjustable gas and/or liquid permeability. During the formation of textile fabrics in accordance with the disclosure, polyester fibers in the weaves are melted by the application of heat to form textile sheet materials that are stated to have predetermined gas and/or liquid permeability.
Improved polyurethane, acrylic, polyamide, and silicone coatings that are coated in layers on the fabrics have recently been developed. It has been found that adhesion and heat sealing characteristics are greatly improved with such layered coatings. Examples of such coated fabrics and methods of coating such fabrics are disclosed in copending commonly assigned applications Ser. Nos. 09/327,243, filed Jun. 7, 1999, now U.S. Pat. No. 6,239,046 B1, 09/327,244, filed Jun. 7, 1999, abandoned in favor of 09/956,639, filed Sep. 19, 2001, and 09/327,245 filed Jun. 7, 1999, abandoned in favor of 09/956,640, filed Sep. 19, 2001, the disclosures of which are incorporated herein by reference and made a part of this disclosure. Another example of a greatly improved bonding system is a polyurethane epoxy resin and polysiloxane beaded heat seal, that is disclosed in copending commonly assigned application Ser. No. 09/452,030, filed Nov. 30
Bradford Industries, Inc.
Hollander Law Firm, P.L.C.
Juska Cheryl A.
Singh Arti R.
LandOfFree
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