Patent Application
20120118881
The present invention relates to the field of transportation, and, more particularly, to cargo containers having a fabric closure formed of high strength yarns, with an easy access opening, that functions both as a cut-resistant cargo curtain and a load retainer.
Cargo containers of many forms have been used for transporting land, sea, and air cargo for many years. For example, one type of cargo container is box-like, with at least two side walls, a top, and a flat bottom. Another type of cargo container has opposed side walls and a rounded back and top. From the side, this type of container resembles a quadrant of a circle, and is shaped in this matter to conform to the shape of the cargo bay of cargo transport aircraft. Typically, and regardless of the shape or geometry of the container, one end or side of the cargo container is open for loading and unloading cargo.
Various door closures have been used for opening and closing the open ends of such containers. One type of closure has been a rigid door closure which covers the opening to reduce tampering, to prevent the loss of small items, and to prevent the cargo from being exposed to dirt, moisture, and ultraviolet light. Another type of closures includes the combination of a webbing and a fabric closure. This type of closure has been generally preferred over rigid door closures because it tends to be much lighter and less expensive. The fabric covers have typically been formed from canvas, or vinyl coated nylon or polyester. However, each of these fabrics lacks the durability to withstand physical stresses or lacks resistance to environmental conditions or harsh chemicals common to the transportation industry. For example, exposure to ultraviolet light, diesel and jet fuels, and oils, tends to rapidly degrade such fabric covers. Accordingly, the durability of a cargo cover is ultimately determined by its tear-strength, abrasion resistance, cut-and-stab resistance and ability to withstand environmental and chemical exposure. Otherwise, the product life is very limited and replacement costs are high. Because fabric covers lack the durability to also serve as load retainers, a separate webbing or netting is required to keep the cargo restrained so that it cannot pass through the covered end or fall out.
In more recent years, as shown in U.S. Pat. No. 5,395,682, fabric closures have been developed of a woven fabric formed of yarns of the fabric are constructed of long-chain extended (ultra-high molecular weight) polyethylene fibers. Such closures have exhibited increased strength and durability, while being considerably lighter than fabrics previously available. More specifically, as shown in U.S. Pat. No. 6,755,232, the fabric closures have been formed as a unitary panel, having web straps spaced apart and attached to the panel for releasable attachment to existing fasteners on the cargo container. In a further improvement to eliminate the need to completely remove the fabric closure from the cargo container for loading and unloading purposes, a fabric closure was developed comprising a single panels, or two panels, having an access opening for loading, unloading, and inspecting cargo, with the loosening or removal of a minimal number of straps and fasteners.
The inventors have discovered that, while having an access opening in the fabric closure facilitates less labor and time intensive requirements for loading and unloading of cargo, including such an access opening creates problems in and of itself, such as vulnerability of exposure of the cargo to contaminants and environmental elements, as well as possible penetration by cargo handling equipment are serious drawbacks.
The present invention is directed to a closure for covering the openings of cargo containers, baggage trailers, or trucks that accomplishes both of the above-described functions. Thus, the closure described hereinafter functions as both a cut-resistant cargo curtain and a load retainer for preventing cargo from falling out of the cargo container or otherwise penetrating the closure. Further, the closure described herein may be installed or removed in a fraction of the time required to install separate covers and nets or webbing and is not subject to the entanglement problems inherent in the prior art. Additionally, an easy access is provided in the unitary panel to facilitate loading, unloading, and inspection of the contents of a cargo container without having to completely remove the unitary cover.
Accordingly, one aspect of the present invention is to provide a cut resistant fabric curtain and load retainer for enclosing at least one open end or side of cargo containers having side walls, a top, and a bottom. As used here, “cargo containers” include uniform load devices (ULDs), air cargo containers, sea-land containers, over-land trailers, and the like. Also as used herein, “wall” refers to any of various upright constructions having a length much greater than the thickness and presenting a continuous surface except where pierced by doors, windows, etc. A wall may be planar or have curvature in its construction.
The fabric curtain and load retainer includes at least one panel of fabric formed of at least one layer of fabric woven with yarns formed from fibers sufficiently cut and tear resistant to prevent cargo from penetrating the curtain. The fabric is desirably also resistant to heat, cold, ultraviolet (UV) radiation, and chemicals such as diesel and jet fuels and oils. Two high strength yarns formed from long chain polyethylene fibers are available from Honeywell under the trademark SPECTRA® or from DSM under the trademark DYNEEMA®. The term “high strength yarns” means yarns formed from fibers having a tenacity exceeding 7 grams/denier and initial tensile moduli of at least about 150 g/d. Other suitable high-strength yarns having the characteristics described above also may include ultra high molecular weight aramids, and ultra high molecular weight polypropylene, and those formed of blends of such compositions. Aramids are intended also to include para-aramids such as KEVLAR® by DuPont. The fabric should further be coated or laminated with a thermoplastic film.
The fabric closure is formed so that it substantially covers the open end of the cargo container. Preferably, at least some portion overlaps the peripheral edges of the cargo container side walls and top. The overlap portion provides an additional barrier to environmental or other anticipated undesirable elements, and this barrier may be further enhanced by securing the overlap portion around the periphery of the cargo container with a cable or the like that is inserted through a hem formed in the edge of the overlap portion and fastened to the lower front corners of the container. Alternatively, the fabric closure may be secured around the periphery of the open end of the cargo container with riveted fasteners, as such fasteners are well known in the art.
Once the fabric closure has been secured around the periphery of the cargo container, it must be drawn taut to restrain cargo stowed in the container. One way of tensioning the fabric panel is by means of web straps and fasteners that are attached around at least part of the periphery of the fabric closure. For example, it may be desirable to attach the fabric cover along one side and along either the top or bottom of the cargo container with hooks that are attached to the outer edges of the fabric. Adjustable fasteners attached along the opposite side and top or bottom of the fabric closure may then serve the dual function of attaching the fabric closure to those sides of the cargo container as well as drawing the fabric taut, thereby restraining cargo stowed in the cargo container, while preventing items of cargo from slipping around or through the fabric closure. Preferably, the fabric closure is constructed so that opposed pairs of web straps are attached around the periphery of the fabric panel. The term “opposed pair” means that each strap of a pair is positioned at a point on the opposite side of the panel from the other so that the pair form a “load path”. The straps are located to correspond with fasteners attached to the cargo container around the open end thereof. Again, each pair should include one member that is adjustable so that the cover can be made taut. When the strap pairs are attached co-linearly to a high-strength fabric panel such as that described herein, the straps and fabric combination provide load restraint at least equivalent to separately formed webbing or nets. The straps are formed of nylon, but any suitable high strength webbing material may be used. The term “high strength webbing” material means webbing having a tear strength of about 900 pounds or more per linear inch of webbing width. Desirably the straps are sewn to the fabric panel with a high strength thread such as SPECTRA® or DYNEEMA®. The web straps are secured to fasteners, such as hooks and buckles, for securing the top and opposed bottom portions of the fabric panel to the cargo container.
A selectively closeable opening is formed in the fabric panel for access therethrough, and includes at least a vertical opening and sometimes a horizontal opening. A slide fastener is attached along adjacent edges of the length of the vertical opening and the horizontal opening, wherein the fabric panel prevents passage of cargo items which may be stowed in the container around and through the fabric closure.
In some embodiments, the fabric closure further includes web closure straps that are attached adjacent to and on both sides of the substantially vertical opening, the web closure straps having attached fasteners for further securing together both sides of the substantially vertical opening and insuring stability of the load contained therein. The slide fastener, or zipper, attached along the substantially vertical opening may include a tab that is moveable to open from the bottom upwardly and to close from the top downwardly. A flap may be provided to extend along the substantially vertical opening, the substantially horizontal opening, or both to overly and protect the slide fasteners from contamination and exposure to the elements.
In some embodiments the vertical opening terminates at a point near, but not all the way at the top. In other embodiments, the fabric panel extends entirely from the bottom to the top, in which case the panel is essentially formed of two sections joined along adjacent edges where closed. In some embodiments, the horizontal opening intersects the vertical opening to create a T-shaped selectively closeable opening. Alternatively, the horizontal opening may extend from a point spaced apart from one of the opposed side edges of the fabric panel and terminates at the intersection with the vertical opening, to form an inverted L-shape.
These and other aspects of the present invention will become apparent to those skilled in the art after a reading of the following description of the preferred embodiment when considered with the drawings.
Referring now to the drawings in general and to
As best seen in
Closure 10 is formed from at least one panel 22 with at least one layer of a fabric woven with high strength yarns formed substantially from high tenacity fibers sufficiently cut resistant to prevent penetration by cargo, or cargo handling equipment. While minor amounts of other fibers (less than 50%) might be blended herewith, the yarns should be primarily from yarns having a tenacity of at least 20 grams/denier.
As used herein, the term “high tenacity fibers” means fibers which have tenacities equal to or greater than about 7 g/d. Preferably, these fibers have initial tensile moduli of at least about 150 g/d and energies-to-break of at least about 8 J/g as measured by ASTM D2256. As used herein, the terms “initial tensile modulus”, “tensile modulus” and “modulus” mean the modulus of elasticity as measured by ASTM 2256 for a yarn and by ASTM D638 for an elastomer or matrix material.
Preferably, the high tenacity fibers have tenacities equal to or greater than about 10 g,/d, more preferably equal to or greater than about 15 g/d, even more preferably equal to or greater than about 20 g/d, and most preferably equal to or greater than about 25 g/d.
The yarns and fabrics of the invention may be comprised of one or more different high strength fibers. The yarns may be in essentially parallel alignment, or the yarns may be twisted, over-wrapped or entangled. The fabrics of the invention may be woven with yarns having different fibers in the warp and weft directions, or in other directions.
The cross-sections of fibers useful herein may vary widely. They may be circular, flat or oblong in cross-section. They may also be of irregular or regular multi-lobal cross-section having one or more regular or irregular lobes projecting from the linear or longitudinal axis of the fibers. It is preferred that the fibers be of substantially circular, flat or oblong cross-section, most preferably substantially circular.
High tenacity fibers useful in the yarns and fabrics of the invention include highly oriented high molecular weight polyolefin fibers, particularly high modulus polyethylene fibers, aramid fibers, polybenzazole fibers such as polybenzoxazole (PBO) and polybenzothiazole (PBT), polyvinyl alcohol fibers, polyacrylonitrile fibers, liquid crystal copolyester fibers, basalt or other mineral fibers, as well as rigid rod polymer fibers, and mixtures and blends thereof. Preferred high strength fibers useful in this invention include polyolefin fibers, aramid fibers and polybenzazole fibers, and mixtures and blends thereof. Most preferred are high modulus polyethylene fibers, aramid fibers and polybenzoxazole fibers, and blends and mixtures thereof. The yarns may comprise a single type of fiber or blends of two or more fibers. Additionally, different fibers may be employed in the fiber network.
U.S. Pat. No. 4,457,985 generally discusses such high molecular weight polyethylene and polypropylene fibers, and the disclosure of this patent is hereby incorporated by reference to the extent that it is not inconsistent herewith. In the case of polyethylene, suitable fibers are those of weight average molecular weight of at least about 150,000, preferably at least about one million and more preferably between about two million and about five million. Such high molecular weight polyethylene fibers may be spun in solution (see U.S. Pat. No. 4,137,394 and U.S. Pat. No. 4,356,138), or a filament spun from a solution to form a gel structure (see U.S. Pat. No. 4,413,110, German Off. No. 3,004, 699 and GB Patent No. 2051667), or the polyethylene fibers may be produced by a rolling and drawing process (see U.S. Pat. No. 5,702,657). As used herein, the term polyethylene means a predominantly linear polyethylene material that may contain minor amounts of chain branching or comonomers not exceeding about 5 modifying units per 100 main chain carbon atoms, and that may also contain admixed therewith not more than about 50 wt % of one or more polymeric additives such as alkene-l-polymers, in particular low density polyethylene, polypropylene or polybutylene, copolymers containing mono-olefins as primary monomers, oxidized polyolefins, graft polyolefin copolymers and polyoxymethylenes, or low molecular weight additives such as antioxidants, lubricants, ultraviolet screening agents, colorants and the like which are commonly incorporated.
High tenacity polyethylene fibers (also referred to as extended chain or high modulus polyethylene fibers) are preferred and are sold under the trademark SPECTRA® by Honeywell International Inc. of Morristown, N.J., U.S.A.
Depending upon the formation technique, the draw ratio and temperatures, and other conditions, a variety of properties can be imparted to these fibers. The tenacity of the fibers are at least about 7 g/d, preferably at least about 15 g/d, more preferably at least about 20 g/d and most preferably at least about 25 g/d. Similarly, the initial tensile modulus of the fibers, as measured by an Instron tensile testing machine, is preferably at least about 300 g/d, more preferably at least about 500 g/d, still more preferably at least about 1,000 g/d and most preferably at least about 1,200 g/d. These highest values for initial tensile modulus and tenacity are generally obtainable only by employing solution grown or gel spinning processes. Many of the filaments have melting points higher than the melting point of the polymer from which they were formed. Thus, for example, high molecular weight polyethylene of about 150,000, preferably about one million and more preferably about two million molecular weight generally have melting points, in the bulk of 138° C. The highly oriented polyethylene filaments made of these materials have melting points of from about 7° C. to about 13° C. higher. Thus, a slight increase in melting point reflects the crystalline perfection and higher crystalline orientation of the filaments as compared to the bulk polymer.
Similarly, highly oriented high molecular weight polypropylene fibers of weight average molecular weight at least about 200,000, preferably at least about one million and more preferably at least about two million may be used. Such extended chain polypropylene may be formed into reasonably well oriented filaments by the techniques prescribed in the various references referred to above, and especially by the technique of U.S. Pat. No. 4,413,110. Since polypropylene is a much less crystalline material than polyethylene and contains pendant methyl groups, tenacity values achievable with polypropylene are generally substantially lower than the corresponding values for polyethylene. Accordingly, a suitable tenacity is preferably at least about 8 g/d, more preferably at least about 11 g/d. The initial tensile modulus for polypropylene is preferably at least about 160 g/d, more preferably at least about 200 g/d. The melting point of the polypropylene is generally raised several degrees by the orientation process, such that the polypropylene filament preferably has a main melting point of at least 168° C., more preferably at least 170° C. The particularly [referred ranges for the above described parameters can advantageously provide improved performance in the final article. Employing fibers having a weight average molecular weight of at least about 200,000 coupled with the preferred ranges for the above-described parameters (modulus and tenacity) can provide advantageously improved performance in the final article.
In the case of aramid fibers, suitable fibers formed from aromatic polyamides are described in U.S. Pat. No. 3,671,542, which is incorporated herein by reference to the extent not inconsistent herewith. Preferred aramid fibers will have a tenacity of at least about 20 g/d, an initial tensile modulus of at least about 400 g/d and an energy-to-break at least about 8 J/g, and particularly preferred aramid fibers will have a tenacity of at least about 20 g/d and an energy-to-break of at least about 20 J/g. Most preferred aramid fibers will have a tenacity of at least about 20 g/d, a modulus of at least about 900 g/d and an energy-to-break of at least about 30 J/g. For example, polyp-phenylene terephthalamide) filaments which have moderately high moduli and tenacity values are particularly useful in forming ballistic resistant composites. Examples are Kevlar® 29 which has 500 g/d and 22 g/d and Kevlar® 49 which has 1000 g/d and 22 g/d as values of initial tensile modulus and tenacity, respectively. Examples are Twaron® T2000 from Teijin which has a denier of 1000. Other examples are Kevlar® 29 which has 500 g/d and 22 g/d as values of initial tensile modulus and tenacity, respectively, as well as Kevlar® 129 and KM2 which are available in 400, 640 and 840 deniers from du Pont. Aramid fibers from other manufacturers can also be used in this invention. Copolymers of poly(p-phenylene terephthalamide) may also be used, such as co-poly(p-phenylene terephthalamide 3,4′ oxydiphenylene terephthalamide). Also useful in the practice of this invention are poly(m-phenylene isophthalamide) fibers sold by du Pont under the trade name Nomex®.
High molecular weight polyvinyl alcohol (PV-OH) fibers having high tensile modulus are described in U.S. Pat. No. 4,440,711 to Kwon et al., which is hereby incorporated by reference to the extent it is not inconsistent herewith. High molecular weight PV-OH fibers should have a weight average molecular weight of at least about 200,000. Particularly useful PV-OH fibers should have a modulus of at least about 300 g/d, a tenacity preferably at least about 10 g/d, more preferably at least about 14 g/d and most preferably at least about 17 g/d, and an energy to break of at least about 8 J/g. PV-OH fiber having such properties can be produced, for example, by the process disclosed in U.S. Pat. No. 4,599,267.
In the case of polyacrylonitrile (PAN), the PAN fiber should have a weight average molecular weight of at least about 400,000. Particularly useful PAN fiber should have a tenacity of preferably at least about 10 g/d and an energy to break of at least about 8 J/g. PAN fiber having a molecular weight of at least about 400,000, a tenacity of at least about 15 to 20 g/d and an energy to break of at least about 8 J/g is most useful; and such fibers are disclosed, for example, in U.S. Pat. No 4,535,027.
One preferred material is a woven fabric formed from SPECTRA® polyethylene fibers. In one embodiment, the fabric preferably has between about 15 and about 45 ends per inch (about 5.9 to about 17.7 ends per cm) in both the warp and fill directions, and more preferably between about 17 and about 33 ends per inch (about 6.7 to about 13 ends per cm). The yarns are preferably each between about 650 and about 1200 denier. The result is a woven fabric weighing preferably between about 2 and about 15 ounces per square yard (about 67.8 to about 508.6 g/m2), and more preferably between about 5 and about 11 ounces per square yard (about 169.5 to about 373.0 g/m2). The following table provides fabric constructions that are suitable for use in the present invention, As those skilled in the art will appreciate, the fabric constructions described here are exemplary only and not intended to limit the invention thereto. Each of these uncoated fabrics is available from Hexcel of Anderson, S.C., and is made from SPECTRA® fiber:
As shown in the table, a plain weave fabric having 17 ends per inch of 1200 denier SPECTRA® 900 fiber in both the warp and fill directions weighs only about 5.5 ounces per square yard (about 186.5 g/m2), but has a breaking strength of greater than 800 pounds force per inch (1401 N/cm) in both directions. Other weaves than a plain weave may be employed, such as a basket weave.
The fabric should further be coated or laminated with a thermoplastic film, to provide additional protection from the elements, including waterproofing. As used herein, the terms “coated” and “laminated” may be used interchangeably to describe one or more protective layers applied to a fabric substrate. Exemplary coated fabrics for providing such protection are described in U.S. Pat. Nos. 6,280,546 and 7,820,570, the contents of which are incorporated herein in their entirety. This coated fabric includes: (a) a fabric in which high performance yarns are a major constituent and have a denier between about 360 and 1,200; (b) a thermoplastic film bonded to at least one side of the fabric. The thermoplastic film comprising ethylene vinyl acetate, or low density polyethylene, or a combination of the two.
Panel 22 is sized to completely cover the open end of cargo container 12 and to overlap the side and top edges of container 12 with an edge portion 13. Edge portion 13 provides an additional barrier to environmental or other anticipated undesirable elements. As shown in
As shown in
Similarly, opposed web strap pairs 26 and 28 are attached to opposing side portions of panel 22. Web straps 24, 25, 26, and 28 are formed from nylon, but other high strength webbing materials may be substituted. The term “high strength webbing” material means webbing having a tear strength of about 900 pounds or more per linear inch of webbing width. Straps 24, 25, 26, and 28 are desirably sewn to panel 22 with high strength threads such as SPECTRA®, or DYNEEMA®, available from DSM.
As is standard in the transportation industry, some cargo container constructions 12 are already normally supplied with a plurality of straps with rings 32 affixed to the cargo container 12 for attaching web straps or separate webbing thereto. Web straps 24, 25, 26, and 28 are aligned to correspond with straps with rings 32 for convenient attachment thereto. A variety of fastener types are commercially available for attachment to the web straps. As shown in
Similarly,
As shown in
Optionally, to protect the slide fastener from contamination and exposure from the elements, a flap 129 may be affixed to the panel 122b by sewing, adhering, etc. to extend along the length of the vertical opening 123, the flap having one edge attached to the fabric panel and an opposed free edge overlying the slide fastener 128. To further protect the slide fastener 128 from contaminants and environmental exposure, the flap 129 may be secured to panel 122a with a hook and look fastener, such as VELCRO® 131.
Web strap pairs 140 and 142 are connected with adjustable fasteners 127 to secure opening 123 for transit. Adjustable fasteners 127 function to take-up the slack in panels 122a, 122b in the horizontal direction, while also providing additional load restraint for the cargo in container 12.
Turning now to
Optionally, to protect the slide fasteners from contamination and exposure from the elements, a flap 230 may be affixed to the panel 222 by sewing, adhering, etc. to extend along the length of the vertical opening 223a, the flap having one edge attached to the fabric panel and an opposed free edge overlying the slide fastener 128. Similarly, one or more flaps 232 may be affixed along the length of the horizontal openings 223b and 223c to overly the slide fasters 129 on those horizontal portions.
In the aspect shown in
Alternatively, as shown in
Again, optionally, to protect the slide fasteners from contamination and exposure from the elements, a flap 420 may be affixed to the panel 422 by sewing, adhering, etc. to extend along the length of the vertical opening 423a, the flap having one edge attached to the fabric panel and an opposed free edge overlying the slide fastener 125. Similarly, one or more flaps 329 may be affixed along the length of the horizontal opening 423b to overly and protect the slide faster 127 on that horizontal portion. To further protect the slide fasteners 128 and 129 from contaminants and environmental exposure, the flaps 420 and 432 may be secured to panel 422 with a hook and look fastener, such as VELCRO® 431.
Similar to the previous embodiments, non-adjustable web straps 124 and fasteners 134 or web straps 126 with adjustable fasteners 136 may be attached to spaced apart locations about the bottom of the panel 422 for secure attachment, and adjustment, as desired of the enclosure 400 to the bottom of the cargo container 312. Again, for addition strength and load restraint, web strap pairs 140 may be connected with adjustable fasteners 128 to further secure opening 423a for transit.
Turning lastly to
In the aspect shown in
Again, optionally, to protect the slide fasteners from contamination and exposure from the elements, flaps 519 may be affixed to the panel 522 by sewing, adhering, etc. to extend along the length of the vertical openings 523a, 523b, each flap having one edge attached to the fabric panel 522 and an opposed free edge overlying its respective slide fastener 128. Also, again, to further protect the slide fasteners 128 from contaminants and environmental exposure, the flaps 519 may be secured to panel 522 with a hook and look fastener material, such as VELCRO® 531.
Certain modifications and improvements will occur to those skilled in the art upon a reading of the foregoing description. It should be understood that all such modifications and improvements have been deleted herein for the sake of conciseness and readability but are properly within the scope of the following claims.
