# US 4,464,263 A · Pleated filter element and integral shield and method for making same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,464,263 A - Document ID: US4464263A - Status: Granted - Kind: A - Application number: 06/349,899 - Filed: 1982-02-18 - Granted: 1984-08-07 - Earliest claimed: 1980-09-20 - Assignees: Fram Corporation - Inventors: Peter Brownell - Web page: https://patentgrep.com/patent/US4464263A ## CPC - B01D 46/523: {with means for maintaining spacing between the pleats or folds} - B01D 27/005: {Making filter elements not provided for elsewhere} - B01D 27/06: with corrugated, folded or wound material - B01D 46/2411: {Filter cartridges} - B29C 44/1271: {the preformed parts being partially covered} - B01D 2201/0407: Perforated supports on both sides of the filtering element - B01D 2265/06: Details of supporting structures for filtering material, e.g. cores - Y10T 156/1057: Subsequent to assembly of laminae - Y10T 428/24322: Composite web or sheet - Y10T 428/249981: Plural void-containing components - Y10T 428/249984: Adhesive or bonding component contains voids - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A pleated paper filter element (10) has a fluid-permeable foamed-plastic shield (16) formed on one of its faces to firmly and accurately position the adjacent folds of filter media. The shield (16) is formed in situ and bonds to the filter media without the use of an intermediate adhesive so as to form a unitary structure. A method of making such a filter involves disposing a foamable liquid plastic (34) near a pleated paper filter unit and foaming the plastic. Prior to solidification, the plastic is effective to bond directly to the filter media. A mold (22) for making such a filter element includes a receptacle (28) for receiving a quantity of liquid plastic and a filter unit and for holding them in the proper relation while the plastic is foamed. The mold receptacle includes projections (30) which form perforations (18) in the solidified plastic and which provide for fluid flow communication through the filter element. The plastic may be of the open-cell fluid-permeable type to permit fluid flow communication through the shield to the filter element. ## Claims ### 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 2 (depends on 1) The invention of claim 1 wherein said cellular plastic is a polyurethane compound. ### Claim 3 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 4 (depends on 3) The invention of claim 3 including the step of forming multiple perforations through the plastic material. ### Claim 5 (depends on 3) The invention of claim 3 wherein said receptacle includes a multiplicity of projections for spacing said filter media away from said foamable liquid plastic, said projections forming perforations in the solidified plastic so that the solidified plastic is fluid-permeable. ### Claim 6 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 with its pleats parallel to the axis of the annulus; 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, fluidpermeable 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 apex of each V-shaped pleat into said shield during the transition of the shield from a foamed liquid to said shape-retaining solid, said shield being of a closed-cell character, said shield including a multiplicity of perforations therethrough.