Pleated filter element and integral shield and method for making same

Claim 1

An integral filter element comprising: a sheet of filtering media, said filtering media sheet having a multiplicity of substantially parallel elongated folds therein, said folds being successively disposed in opposite directions to provide a plurality of elongated V-shaped pleats in said filtering media sheet, said pleats defining like-disposed folds, said sheet being joined at its ends and rolled to define an annular filter having inner and outer diameters with its pleats parallel to the axis of the annulus so that the pleats define inner and outer apexes at respectively the inner and outer diameters of said annular filter; and a fluid-permeable, shape-retaining, structurally self-supporting shield circumscribing the outside of said annular filter and integrally bonded to the like-disposed folds of said filtering media sheet, said shield being formed of a shape-retaining, structurally self-supporting, fluid permeable cellular plastic and laterally extending from one like-disposed fold to the next adjacent like-disposed fold so as to space apart said folds, said shield further extending longitudinally along said like-disposed folds and providing a substantially continuous bond between said shield and said like-disposed folds to restrain like-disposed folds from movement relative to said shield, said bond being formed by partially embedding the outer apex of each V-shaped pleat into said shield during the transition of the shield from a foamed liquid to said shape-retaining solid, the portion of each pleat between the inner and outer apexes thereof being unsupported by said shield.

Claim 4

The method of making a filter element characterized by the steps of: providing a cylindrical receptacle having inwardly facing annular flanges to define a circumferentially extending basin; placing liquid plastic material of a foamable character in said receptacle; rotating said cylindrical receptacle about its longitudinal axis to distribute said plastic material evenly about the inner cylindrical surface of said basin; suspending a paper filter media having a plurality of V-shaped pleats radially within said receptacle and spaced a selected distance from said liquid plastic material; foaming said plastic material and expanding its volume so that said plastic material contacts said filter media at the apex of each V-shaped pleat to embed each pleat therein; and solidifying said plastic material into an annular shape-retaining solid such that said filter media is integrally bonded to said plastic and forms a unitary structure.

Claim 5

The method of making a filter element characterized by the steps of: providing a cylindrical receptacle having inwardly facing annular flanges to define a circumferentially extending basin; placing liquid plastic material of a foamable character in said receptacle; rotating said cylindrical receptacle about its longitudinal axis to distribute said plastic material evenly about the inner cylindrical surface of said basin; suspending a paper filter media having a plurality of V-shaped pleats radially within said receptacle and spaced a selected distance from said liquid plastic material; foaming said plastic material and expanding its volume so that said plastic material contacts said filter media at the apex of each V-shaped pleat to embed each pleat therein; and solidifying said plastic material into an annular shape-retaining solid such that said filter media is integrally bonded to said plastic and forms a unitary structure.