In a method for producing two or more filter bellows, a bellows with a filter medium with fold edges is provided, wherein the filter medium is running in a running direction. A cutting path is carried out in the bellows with the filter medium in a direction that, at least in some regions, is transverse relative to the fold edges such that the filter bellows are produced in parallel and the cutting path creates end edge faces and/or side faces of the filter bellows and the filter bellows are embodied lying adjacent to each other and symmetrical or point-symmetrical relative to each other in the running direction and/or transverse to the running direction. A filter element with such a filter bellows and a filter system with such a filter element and filter bellows arranged in a filter housing are provided.

A method for manufacturing a filter (1) for gas masks includes providing a flat paper and folding the paper into a pleated preform. The filter element (2) is separated from the pleated preform (6) and is inserted into a housing (3). The inserted filter element (2) is connected to the housing (3) at least at some points. This filter elements (2) may have a polygonal outer contour, upon separating the element from the pleated filter preform (6). A foam and/or an adhesive is applied to an outer edge of the filter element (2), arranged on the circumference of the filter element, for an at least partial sealing of an edge (5). This establishes a connection to the housing (3) in at least some sections.

A reusable air filter and methods are provided for filtering air being conducted to an air intake of an internal combustion engine. The reusable air filter comprises a filter medium configured to pass an airstream and entrap particulates flowing within the airstream. The filter medium is comprised of cotton gauze disposed in a sinusoidal arrangement that provides a filtration surface area that is larger than a perimeter area of the filter medium. An end cap and base may be configured to retain the filter medium therebetween. The base provides an interface between the air filter and an air inlet of the engine. The filter medium may be disposed in a flat, panel shape that is bordered by a supportive tray. Support rods may be embedded within the tray to prevent bowing of the tray due to air pressure when coupled with an air box of the engine.

A filter device for a fume extraction device includes at least two filter elements arranged at an angle relative to one another, and a holding frame for holding the at least two filter elements. An edge of one of the at least two filter elements lies adjacent to an edge of the other one of the at least two filter element. Each of the at least two filter elements has a surface with a variable distance between opposite outer faces of the filter element.

An air filter element includes a filter arrangement, an elbow, and a filter element seal member. The filter arrangement includes a filter media pack having a dirty air inlet and a clean air outlet, wherein air flowing through the clean air outlet flows in a first axial direction and the clean air outlet defines a filter arrangement cross sectional area. The elbow has a first end constructed to extend from the filter arrangement clean air outlet, a second end wherein air flowing through the second end flows in a second axial direction, and an air flow enclosure extending from the elbow first end to the elbow second end. The air flow enclosure includes an air deflector constructed to direct air from the first axial direction to the second axial direction, wherein the second axial direction is different from the first axial direction, and an interior volume between the elbow first end and the elbow second end. The filter element seal member is located on the elbow second end, wherein the filter element seal member is constructed to seal to a clean air intake, the filter element seal member located on the elbow second end defining a seal member cross sectional area. The filter element can be characterized as having a ratio of the seal member cross sectional area to the filter arrangement cross sectional area of at least 0.5. The filter element can have a z-filter media pack for a pleated media pack. The air filter element can be arranged in an air cleaner.

A filter element comprising a filter media and an outer surface. The filter media is formed in a closed loop, the closed loop defining a hollow interior extending along a longitudinal axis between a first end of the filter media and a second end of the filter media. The outer surface surrounds a perimeter of the filter element and is defined by a substantially circular first portion and at least one second portion. The first portion is substantially circular at a selected height of the filter media, and the at least one second portion is depressed relative to a circle defined by the substantially circular first portion at the selected height.

A filter element including a throughflow-porous filter body extending between a head end and a longitudinally opposite foot end, wherein a head structure is formed at the head end of the filter element, the head structure having at least one seal configured to seal the filter element with respect to a filter element holder, wherein the head structure has a sidewall extending basically in the longitudinal direction and the seal is formed on the basically longitudinally extending sidewall of the head structure of the filter element.

A filter element has a filter bellows of filter medium laid into folds. The folds extend between oppositely positioned end edges of the filter bellows, respectively. The end edges form oppositely positioned end edge surfaces. The filter bellows is arranged in closed configuration about a longitudinal axis and encloses a hollow space. The filter bellows has opposed end faces sealed by an end disc. The filter bellows has a cut portion in at least one of the oppositely positioned end edge surfaces such that one or more regions of folds with shortened fold length are formed. A fold length of the folds with shortened fold length is substantially identical at an outer and inner circumference of the filter bellows. A filter system has a housing in which the filter element is arranged. One of the housing parts has a region corresponding to the cut portion of the filter bellows.

A filter system and a filter cartridge for use in the filter system is provided. The filter cartridge includes a primary media pack, a precleaner media and a housing engagement member. The primary media pack has an outer perimeter and opposite first and second primary flow faces. The precleaner media has an outer perimeter and opposite first and second precleaner flow faces. The first precleaner flow face extends in a first plane parallel to and adjacent to the first primary flow face of the primary media pack. The second precleaner flow face extends in a second plane non-parallel to the first precleaner flow face and the first plane. The housing engagement member surrounds, at least in part, the primary media pack and surrounds, at least in part, the precleaner media. The housing engagement member includes a seal portion and a seal support portion.

An outdoor air purifier includes a housing including at least one housing cover part, a mounting base, at least one flow inlet for outdoor air to be purified, at least one flow outlet for cleaned air, and an inner clean air space, a fan having a standing rotational axis and arranged within the housing, wherein the at least one flow inlet is arranged radially with regards to the standing rotational axis, and the at least one flow outlet is arranged axially with regards to the standing rotational axis, and at least one filter element at least partially surrounding the inner clean air space. The fan is displaced axially from the mounting base and is in fluid connection with the inner clean air space. The at least one filter element extends essentially parallel to the standing rotational axis.