| 主权项 |
1. An airbeam comprising:
a pair of resilient inner tubes, a pair of inner sleeves, a pair of middle sleeves, and an outer cover, wherein, when laid flat, each of said inner tubes, each sleeve, and said outer cover are substantially rectangular, each having a corresponding longitudinal dimension and a lateral dimension orthogonal to said longitudinal dimension, and wherein each of said inner tubes has opposite ends which are sealed, so that each of said inner tubes is air-tight, said opposite ends are sealed by being folded over along a fold-line and bonded to an adjacent outer surface of one of said pair of inner tubes that is adjacent to said fold-line, so as to form a folded-over end, and wherein each inner and middle sleeve and said outer cover are formed of an overlaid pair of substantially rectangular sheets of flexible fabric sheeting, wherein said overlaid pair of fabric sheeting has opposite ends and substantially linear side edges that extending between said opposite ends, wherein each of said overlaid pair of fabric sheeting is stitched by side edge stitching along and inset from each linear side edge to form a flat side seam that extends completely along each linear side edge to form a corresponding cavity therebetween that is flexibly bounded by said overlaid pair of fabric sheeting and said side edge stitching, and wherein each of said overlaid pair of fabric sheeting is inverted so that each of said flat side seams extends cantilevered inwardly into said cavity from said side edge stitching, and wherein said outer cover further includes a linear common seam that is parallel to said side edge stitching along each linear side edge and substantially bisecting said overlaid pair of fabric sheeting between said linear side edges, said linear common seam thereby forming a pair of parallel, adjoining substantially identical outer sleeves having said linear common seam therebetween, wherein a pair of outer sleeves are thereby formed along the length of said outer cover, and wherein one of said middle sleeves is nested within an outer sleeve of said pair of outer sleeves, and wherein one of said inner sleeves is nested within a corresponding middle sleeve of said pair of middle sleeves, and wherein one of said inner tubes is nested within a corresponding inner sleeve, of said pair of inner sleeves, so as to form a parallel adjoining pair of inflatable beams adjoining along said common seam, and wherein said longitudinal dimension of each of said inner sleeves, said middle sleeves and said outer sleeves are substantially the same, and wherein said lateral dimension of said inner sleeves, said middle sleeves and said outer sleeves are incrementally larger than one another respectively so that said nesting of said inner, middle and outer sleeves is tight nesting causing each corresponding flat side seam to be folded over so that said flat side seams of each of said side edges of said outer sleeves are folded over and compressed between each of said outer sleeve and the corresponding middle sleeve, and so that said flat side seams of each middle sleeve are folded over and compressed between said corresponding middle sleeve and the corresponding inner sleeve, and wherein each of said inner tubes is journalled so as to be nested in the corresponding inner sleeve so that, when inflated, each inner tube compresses said flat side seams of each of said inner sleeves between each inner sleeve and the corresponding inner tube, and wherein said nesting is arranged so that said flat side seams of said inner and middle sleeves and said flat side seams of said outer cover, upon inflation of said inner tubes, are compressed and form re-enforced sidewalls. |
