# US 10,478,759 B2 · Filter element > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,478,759 B2 - Document ID: US10478759B2 - Status: Granted - Kind: B2 - Application number: 16/245,403 - Filed: 2019-01-11 - Published: 2019-05-16 - Granted: 2019-11-19 - Earliest claimed: 2012-11-14 - Assignees: Rt-Filtertechnik GmbH - Applicants: Rt-Filtertechnik GmbH - Inventors: Frank Oberli; Dirk Schoenfeld - Web page: https://patentgrep.com/patent/US10478759B2 ## CPC - B01D 29/21: with corrugated, folded or wound sheets - B01D 29/333: {with corrugated, folded filtering elements} - B01D 29/56: in series connection - B01D 2201/122: with pleats of different length - 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) ## Abstract A filter element has a preferably multilayer structure of a pleated filter medium (3) with a plurality of individual filter pleats (5, 7). Due to an alternating sequence of filter pleats (5) with a first pleat height (h1) and filter pleats (7) with a second pleat height (h2), more effective filter surfaces are available than with filter pleats with a uniform pleat height. Upon throughflow by a fluid to be filtered, a lower surface load for the filter medium (30 and lower passage speed of the fluid are present during filtration. A static loading of the filter medium (3) during operation of the filter is then reduced. A hydraulic circuit has such a filter element (1). ## Claims ### Claim 1 A filter element, comprising: a tubular and pleated filter medium having a central longitudinal axis; first filter pleats having a first pleat height; second filter pleats having a second pleat height less than said first pleat height, said first and second filter pleats being arranged in an alternating sequence providing a greater effective filtering surface than if said pleated filter medium had filter pleats having a uniform pleat height of said first pleat height, providing a corresponding flow-through of a fluid to be filtered resulting in an overall lower surface load to said filter medium and providing a lower flow-through velocity of fluid during filtration, thereby resulting in a reduced static charge of said filter medium during filter element operation; and planar sections of said filter pleats each extending in a plane containing an entire length of said central longitudinal axis. ### Claim 2 (depends on 1) A filter element according to claim 1 wherein said second pleat height is 90 percent of said first pleat height. ### Claim 3 (depends on 1) A filter element according to claim 1 wherein said second pleat height is 70 percent of said first pleat height. ### Claim 4 (depends on 1) A filter element according to claim 1 wherein said filter pleats have transitions with curvature radii of a uniform size. ### Claim 5 (depends on 1) A filter element according to claim 1 wherein said planar sections of each of said first and second filter pleats are spaced apart from one another. ### Claim 6 (depends on 1) A filter element according to claim 1 wherein said filter medium comprises multiple layers of filter material having at least one of varying electron releasing properties or varying electron receiving properties. ### Claim 7 (depends on 1) A filter element according to claim 1 wherein each said second filter pleat is delimited on each side thereof by an adjacent one of said first filter pleats defining a w-shaped pleat configuration as viewed from an axial top and one of an inner side or an outer side of said filter medium. ### Claim 8 (depends on 7) A filter element according to claim 7 wherein open holding spaces are formed on at least one of said inner or outer side of said filter medium of a virtual cylindrical segment between two adjacent ones of said first filter pleats, said holding spaces equalizing and reducing flow velocity of fluid through said filter medium during filtering operation. ### Claim 9 (depends on 1) A filter element according to claim 1 wherein said planar sections are spaced uniformly apart from one another. ### Claim 10 (depends on 1) A filter element according to claim 1 wherein said planar sections of each of said first and second pleats each extend in a plane containing an entire length of said central longitudinal axis.