Air pad

Abstract

An inflatable air pad, or fluid impervious pad, is provided having three layers, the top and bottom being joined together to form an enclosed envelope with a middle layer interposed between defining an upper and lower chamber. Fluid is allowed to flow from one side of the middle layer to the other, such that there is uniform pressure throughout. A sealable port is provided in the enclosed envelope for the injection of fluid under pressure. The middle layer is attached to the top layer in a series of seals or attachment points in a rectangular array and is similarly sealed to the bottom layer in a similar rectangular pattern; however, the two patterns are positioned 180 degrees out of phase with each other. These patterns form a series of small cushion areas in the upper and lower chambers respectively and the cushion areas are nested within each other on an offset basis. The individual seals or attachment points are preferably square and are oriented such that lines of maximum stress in the sealed layers are perpendicular to the sides of the square pattern. A number of further seals are formed within the body of the pad, specifically, a preferred pad is divided into three sections with a series of seal lines joining all three layers running lengthwise of the pad parallel to the sides of the pad, thus creating a middle section and two side sections. Interruptions are provided in those seals so that fluid can flow between the sections and the pressure remain uniform throughout.