Filter elements, associated filter assemblies and filter packages

Abstract

The present disclosure relates to a flexible filter media pack tubularly arranged about an axis, a first open end cap fluid-tightly connected to a first axial end of the filter media pack, and a second open end cap fluid-tightly connected to a second axial end of the filter media pack, wherein the first end cap is flexible, e.g., capable of being non-destructively transformed between a first shape and a different second shape, and the present disclosure relates to related filter packages and filter assemblies.

Description

[Technical Field]

[0001] (Reference to Related Application) This application was filed as a PCT International application on February 14, 2024, and claims the benefit of U.S. Provisional Patent Application No. 63 / 484,835, filed February 14, 2023, and claims priority to European Patent Application No. 23159264.3, filed February 28, 2023, both of which are incorporated by reference herein in their entireties.

[0002] (Technical field) The present disclosure relates to the field of gas filtration, such as, for example, air filtration. The present invention relates to the field of filter assemblies that include a filter element hermetically disposed within a filter housing such that air passing from an inlet of the housing to an outlet of the housing is filtered by the filter element. Preferably, the assembly is used to filter air that is subsequently directed, for example, to a vehicle engine. [Background technology]

[0003] Filter elements, also called filter cartridges, are used for a wide variety of filtering applications, and the fluid being filtered can be a liquid or a gas, such as air.

[0004] In practice, it is often desirable to filter contaminants from fluid streams. For example, airflow to engines for motor vehicles, power generation equipment, construction equipment, or other equipment, airflow to gas turbine systems, and airflow to various combustion furnaces carry particulate contaminants therein. For such systems, it is preferable that contaminants be removed or at least reduced from the fluid.

[0005] The filter element includes a filter medium for removing contaminants as fluid flows through the filter medium. Commonly used and commercially available filter media are, for example, pleated or fluted media. When the filter medium becomes loaded with dust and / or particles above a certain threshold load, the filter element needs to be replaced. The filter element is typically delivered in a replaceable manner within the housing.

[0006] There is a need in the industry for new solutions that allow for easy installation of the correct filter element within a filter housing, particularly within a complex filter housing design, which may be the result of boundary conditions imposed by, for example, the geometry and positioning of other vehicle / engine components.

[0007] There is also a need in the industry for compact packaging of filter elements and filter housings.

[0008] And there is a need in the industry for filter elements with increased filter media volume to internal housing volume ratios.

[0009] Additionally, solutions to reduce the weight of filter elements and the amount of material used are being realized in the industry.

[0010] There is also a need for a filter housing and assembly that allows for easy removal of the housing cover and facilitates accurate positioning of the housing cover on the housing.

[0011] It is generally important to mount the correct filter element in the correct manner for a particular filter housing to avoid damage to the equipment or engine utilizing the filtered air / gas.

[0012] There is also a need in the industry for a filter assembly that allows the installed filter element to be inspected from the inside without having to remove the element.

[0013] There is also a need in the industry for a filter assembly that allows for inspection of the installed filter element with reduced risk of damaging the filter element's seal towards the main housing. Summary of the Invention [Problem to be solved by the invention]

[0014] It is an object of embodiments of the present disclosure to provide filter elements, packages including such filter elements, and assemblies including such filter elements. [Means for solving the problem]

[0015] The invention is defined in the accompanying independent claims. The dependent claims define advantageous embodiments.

[0016] In a first aspect of the present disclosure, a filter element is disclosed that includes (or consists of) a flexible filter media pack tubularly arranged about an axis, a first open end cap fluid-tightly connected to a first axial end of the filter media pack, and a second open end cap fluid-tightly connected to a second axial end of the filter media pack, wherein the first end cap is flexible and can be non-destructively deformed, for example, between a first shape (or state) (corresponding to a first configuration of the element) and a different, preferably substantially different, second shape (or state) (corresponding to a second configuration of the element).

[0017] It is an advantage that a filter housing can be designed that allows for the installation of the disclosed filter elements but does not allow for the installation of standard filter elements, thereby avoiding the use or incorrect installation of the incorrect filter elements. A further advantage is that the disclosed filter elements can be used in relatively complex and compact housing configurations. Furthermore, the disclosed filter elements can be packaged in a more compact manner. Because at least the first end cap and the filter media can be non-destructively deformed, the filter media can be placed in a twisted configuration for use in the associated housing, which increases the ratio of filter media volume to internal housing volume.

[0018] For purposes of this disclosure, a filter element, end cap, or filter media pack may be non-destructively deformed if the deformation of the respective item does not affect its integrity or performance. Preferably, each item is flexible, and even more preferably, each item is elastically deformable within the boundaries required to perform its function, for example, to be reduced in size to fit into a filter housing service opening that is initially too small, or to mold itself to a filter housing cavity that has sufficient volume but is shaped differently. An item is elastically deformable if it returns to its original, undeformed state after being deformed within the boundaries to perform its function.

[0019] It should be understood that the filter media pack can be non-destructively deformed while maintaining a fluid-tight connection with the first and second end caps. The fluid media pack can include, for example, a pleated media pack. The sheet material pleated to form the pleated media can be single-layered or multi-layered. It can include, for example, one, two, or more filtration and / or coalescence layers. It may further include inner and / or outer support layers. The composite and pleated media must remain deformable in a non-destructive manner. Preferably, it is flexible. Preferably, it is elastically deformable. Preferably, the pleated media is arranged in a tubular shape with the pleat direction parallel to the longitudinal filter element axis in at least the first configuration of the element. The end pleats of the pleated media are preferably longer than the length of a single pleat and are preferably permanently connected to each other by adhesive (e.g., polyurethane), embedding, or other state-of-the-art techniques without loss of filtration capacity. The flutes are the first and last flutes on a sheet of paper to be pleated. Preferably, there are no intermediate axially extending connecting structures between each flute to connect the flutes.

[0020] According to certain embodiments, the portion of the filter element that can be non-destructively deformed can be deformed in a continuous manner, for example, without using a hinge-type configuration. According to certain embodiments, the filter element as a whole can be non-destructively deformed in a continuous manner. According to certain embodiments, the filter element as a whole is elastically deformable.

[0021] Each of the first and second open end caps of the filter element is preferably made from a single piece. They can be formed by potting, for example, by polyurethane (PU) or foam polyurethane potting. Alternatively, they can be manufactured separately and sealingly attached to the first or second end of the media pack by state-of-the-art techniques, for example, by gluing, potting, or injection. Preferably, the end caps are end disks, such as uninterrupted annular rings.

[0022] According to certain embodiments, the first end cap includes or is made of a flexible material. According to certain embodiments, the second end cap includes or is made of a flexible material. According to certain embodiments, both the first and second end caps include or are made of a flexible material.

[0023] According to preferred embodiments, the minimum radial cross-sectional dimension of the second shape of the first open end cap is at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 40%, at least 50%, or at least 75% smaller than the minimum radial cross-sectional dimension of the first shape.

[0024] According to preferred embodiments, the minimum radial cross-sectional dimension of the second shape of the first open end cap is at least 5 mm, at least 10 mm, at least 15 mm, at least 20 mm, at least 25 mm, or at least 5 cm smaller than the minimum radial cross-sectional dimension of the first shape of the first open end cap.

[0025] According to preferred embodiments, the maximum radial cross-sectional dimension of the second shape of the first open end cap is at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 40%, at least 50%, or at least 75% smaller than the maximum radial cross-sectional dimension of the first shape.

[0026] According to preferred embodiments, the maximum radial cross-sectional dimension of the second shape of the first open end cap is at least 5 mm, at least 10 mm, at least 15 mm, at least 20 mm, at least 25 mm, or at least 5 cm smaller than the maximum radial cross-sectional dimension of the first shape of the first open end cap.

[0027] According to a preferred embodiment, the first end cap is elastically deformable.

[0028] Advantageously, such end caps automatically return to their original position, resulting in the corresponding first configuration of the filter element after the end cap and filter element are deformed, for example, to insert or remove the filter element through a small insertion opening in the air purifier housing or packaging means. In these cases, the first configuration of the filter element and the first state of the end cap are the end cap or filter element in an undeformed state, i.e., the state to which the end cap would return even without an external force being applied to the end cap.

[0029] According to a preferred embodiment, the first configuration of the media pack can have a cross-section along a plane perpendicular to the filter element that can be circular, rectangular, rounded rectangular, oval, or have any other regular shape.

[0030] According to a preferred embodiment, the first end cap is connected to the filter media and is possibly manufactured (for example, by polyurethane (PU)) potting).

[0031] According to a preferred embodiment, the first end cap includes a first circumferential seal, preferably integrally formed with the first end cap. For example, the seal can be formed from a polyurethane material, e.g., the same material as the material of the first end cap. Alternatively, the first circumferential seal can be manufactured separately or in a separate step of the manufacturing process and sealingly attached to the first end cap by state-of-the-art technology. An alternative embodiment of the first seal is a TPE (thermoplastic plastic) seal.

[0032] For purposes of this disclosure, a (e.g., first or second) circumferential seal (or sealing surface) is a seal (or sealing surface) that circumferentially surrounds or is located around a respective opening, such as a central opening or a first or second end cap, respectively. The circumferential seal and associated circumferential surface cooperate to provide a gas-tight seal. The orientation of such a circumferential seal or circumferential sealing surface can generally be radially inward, radially outward, or axial, or a combination thereof. The seal between the circumferential seal and the circumferential sealing surface can generally be oriented radially inward, radially outward, or axially, or a combination thereof.

[0033] The first seal is preferably non-destructively deformable, preferably resiliently deformable.

[0034] According to a preferred embodiment, the first circumferential seal includes an N-fold, e.g., one-fold, rotational symmetry about the filter media pack axis. Implementing N-fold rotational symmetry in the first circumferential seal and corresponding sealing surface on the housing cover has the advantage of helping to align the filter element relative to the cover.

[0035] For purposes of this disclosure, an object or projection is said to have N-fold rotational symmetry about an axis of rotation if the object or projection can be mapped onto itself by N different rotations of 360° or less about that axis of rotation. An object or projection with 1-fold rotational symmetry is an object that contains no rotational symmetry other than 360°.

[0036] According to a preferred embodiment, the first circumferential seal is disposed along a plane that is inclined relative to a plane perpendicular to the filter media pack axis.

[0037] According to a preferred embodiment, the first end cap can be radially deformed (e.g., by more than 10%) by a radial force component of less than 40N, less than 30N, less than 20N, or less than 10N.

[0038] According to a preferred embodiment, the first end cap further comprises at least one operating means, such as a handle, adapted and positioned radially inwardly or for pulling a portion of the first end cap.

[0039] According to a preferred embodiment, the operating means includes handle bars or structures bridging opposite sides of the open end cap over a central opening in the first end cap.

[0040] According to a preferred embodiment, the operating means comprises at least one radially inwardly or outwardly directed flap or ear structure, for example, it may comprise two radially inwardly directed flaps or ear structures arranged on opposite sides, e.g., diametrically opposite sides, of the central opening.

[0041] According to a preferred embodiment, the filter media packs are of the conical type, i.e., arranged in a conical shape, with the cross section of each cone decreasing from a first axial end of the media pack to a second axial end of the media pack, the second end cap having a smaller outer diameter than the first end cap.

[0042] This provides the advantage that a filter media support means, such as a tower structure protruding from the inner surface of the housing cover, can be easily inserted into the filter media pack. It is even more advantageous if the filter media pack is at least partially molded during mounting by the filter media support means or tower.

[0043] Preferably, the outer diameter of the second end cap is more than 5%, 10%, 15%, 20%, 25%, or 30% smaller than the outer diameter of the first end cap, and preferably, the outer diameter of the second end cap is within the range of 80% to 90% of the outer diameter of the first end cap.

[0044] According to a preferred embodiment, the second end cap is flexible, eg, capable of being non-destructively deformed between a first shape and a different, preferably substantially different, second shape.

[0045] According to preferred embodiments, the minimum radial cross-sectional dimension of the second shape of the second open end cap is at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 40%, at least 50%, or at least 75% smaller than the minimum radial cross-sectional dimension of the first shape.

[0046] According to preferred embodiments, the minimum radial cross-sectional dimension of the second shape of the second open end cap is at least 5 mm, at least 10 mm, at least 15 mm, at least 20 mm, at least 25 mm, or at least 5 cm smaller than the minimum radial cross-sectional dimension of the first shape of the second open end cap.

[0047] According to preferred embodiments, the maximum radial cross-sectional dimension of the second shape of the second open end cap is at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 40%, at least 50%, or at least 75% smaller than the maximum radial cross-sectional dimension of the first shape.

[0048] According to preferred embodiments, the maximum radial cross-sectional dimension of the second shape of the second open end cap is at least 5 mm, at least 10 mm, at least 15 mm, at least 20 mm, at least 25 mm, or at least 5 cm smaller than the maximum radial cross-sectional dimension of the first shape of the first open end cap.

[0049] According to a preferred embodiment, the second end cap can be deformed radially (e.g., by more than 10%) by a radial force component of less than 40 N, less than 30 N, less than 20 N, or less than 10 N.

[0050] According to a preferred embodiment, the second end cap is elastically deformable.

[0051] Advantageously, such end caps automatically return to their original positions, thereby assuming the corresponding first configuration of the filter element after the end cap and filter element are deformed, for example, to insert or remove the filter element through a small insertion opening in the air purifier housing or packaging means. This is even more advantageous in combination with an elastically deformable first end cap. In these cases, the first configuration of the filter element and the first state of the second end cap are the end caps or filter elements in their undeformed states, i.e., the states to which the end caps or filter elements would return without any external force being applied to them.

[0052] According to a preferred embodiment, a second end cap is connected to the filter media and is possibly manufactured (eg, by polyurethane (PU) potting).

[0053] According to an alternative preferred embodiment, the second end cap is substantially rigid and preferably smaller than the first end cap in the first configuration of the filter element.

[0054] According to a preferred embodiment, the second end cap includes a second circumferential seal, preferably integrally formed therewith. For example, the second circumferential seal can be formed of a polyurethane material, and can include, for example, the same material as the material of the second end cap.

[0055] Alternatively, the seal can be manufactured separately or in a separate step of the manufacturing process and attached to the second end cap in a sealing manner according to the state of the art. An alternative embodiment for the second seal is a TPE (thermoplastic) seal.

[0056] The second circumferential seal is preferably non-destructively deformable, and preferably resiliently deformable.

[0057] According to a preferred embodiment, the second circumferential seal includes an N-fold, e.g., a single-fold rotational symmetry about the filter media pack axis. Introducing an N-fold rotational symmetry in the second circumferential seal and corresponding sealing surface on the housing has the advantage of helping to align the filter element relative to the (second end) of the housing.

[0058] According to a preferred embodiment, the second circumferential seal is disposed along a plane that is inclined relative to a plane perpendicular to the filter media pack axis.

[0059] According to a preferred embodiment, the second open end cap includes a central opening, and the second circumferential seal is embodied as a radially inwardly extending portion of the second end cap. The radially inwardly extending portion includes at least one axially extending circumferential, e.g., V- or U-shaped, groove, trench, or recess disposed adjacent to the central opening, the groove, trench, or recess preferably projecting into the interior volume of the filter media pack in a direction parallel to the axis of the filter media pack. Preferably, the sealing direction of the second circumferential seal is radial, more preferably radially inward.

[0060] According to a preferred embodiment, the filter media pack comprises pleated media, the media comprising one or more layers selected from the group of a media layer and a support layer.

[0061] According to a preferred embodiment, the filter media pack and / or filter element are self-supporting. According to a preferred embodiment, the filter media pack is self-supporting at least axially.

[0062] According to an alternative embodiment, the filter media pack, and thus the filter element, is not self-supporting, e.g., it may be such that while positioned vertically on the first end cap, the filter media pack, and thus the filter element, deforms due to its own weight in the Earth's gravity.

[0063] In a second aspect of the present disclosure, a package is disclosed that includes a box, bag, or sleeve that includes a filter element according to any of the embodiments of the first aspect, wherein the filter element is held in an elastically deformed configuration by an inner sidewall of the box, bag, or sleeve.

[0064] In a third aspect of the present disclosure, a filter assembly is disclosed that includes a filter housing having a housing axis and a filter element according to any of the embodiments of the first aspect, wherein the filter housing includes a filter insertion opening (often referred to as a maintenance opening), the filter insertion opening being too small to allow insertion of a first end cap into the filter housing in a first shape of the first end cap (or a first configuration of the filter element) and being large enough to allow insertion of the first end cap into the filter housing in a second shape of the first end cap (or a second configuration of the filter element).

[0065] According to a preferred embodiment, the insertion opening includes at least one undercut section, and a protrusion of the filter element along the housing axis intersects a protrusion of the undercut section along the housing axis, the intersection corresponding to a protruding overlap region. The protrusion can, for example, lie in a plane perpendicular to the housing axis.

[0066] According to preferred embodiments, the projecting overlap area is greater than 1%, 2%, 3%, 4%, 5%, 10%, or 20% of the projecting area of ​​the filter element along the housing axis. In the case of multiple undercut sections, the projecting overlap area relates to the sum of the overlap areas associated with the individual intersections.

[0067] According to a preferred embodiment, the housing includes a housing cover that covers the insertion opening, the housing cover being substantially complementary or of a complementary shape to the one or more undercut sections. For example, the one or more undercut sections can be defined by one or more flats in the insertion opening, and the housing cover can have one or more corresponding flats along its sidewalls.

[0068] According to a preferred embodiment, the filter assembly includes a housing cover covering the insertion opening, and the housing cover and the filter housing are adapted to meet along an inclined plane such that the housing length on the side corresponding to the protruding overlap area is longer than the housing length on the opposite side of the housing.

[0069] According to a preferred embodiment, the filter assembly includes a housing cover covering the insertion opening, and the housing cover includes a filter media pack inner support structure, such as a tower structure, preferably having a conical shape, protruding from an inner surface from a proximal end toward a distal end of the cover.

[0070] According to a preferred embodiment, the filter assembly includes a housing cover covering the insertion opening, the housing cover including a sensor mount for a sensor, such as a MAF sensor, a temperature sensor, a pressure sensor, an RFID sensor or tag, and optionally the respective sensor. Advantageously, a central region of the filter housing volume below the housing cover is part of the clean air side of the filter housing, allowing the sensor to be located on the housing cover and visible in the line of sight during maintenance.

[0071] According to a preferred embodiment, the filter assembly includes a housing cover covering the insertion opening, the housing cover including a sealing surface for sealingly receiving the first circumferential seal when the cover is attached to the filter housing.

[0072] According to a preferred embodiment, the filter assembly includes a housing cover covering the insertion opening, the filter housing including a first end and a second end, the first end including the filter insertion opening and adapted to receive the cover, the second end disposed opposite the first end and including the outlet opening, and the second end further including a sealing surface complementary to the second circumferential seal for sealingly receiving the second circumferential seal.

[0073] According to a preferred embodiment, the filter assembly includes a housing cover that covers the insertion opening. The second open end cap of the filter element includes a central opening, and the second circumferential seal is embodied as a portion extending radially inward into the central opening of the second end cap. The radially inward extending portion includes at least one axially extending circumferential, e.g., V- or U-shaped, groove, trench, or recess located adjacent to the central opening, and the groove, trench, or recess preferably projects into the interior volume of the filter media pack in a direction parallel to the axis of the filter media pack. The housing cover preferably includes a filter media pack inner support structure, such as a tower structure, having a conical shape that projects from the inner surface from the proximal end to the distal end of the cover. The distal end of the support structure is preferably positioned and adapted to be received by an axially extending circumferential, e.g., V- or U-shaped groove, trench, or recess, of the second circumferential seal of the filter element, to provide radially inward back pressure to the circumferential seal against the sealing surface of the filter housing when the cover is attached to the housing.

[0074] The distal end of the support structure may be axially and / or radially sealed within a V- or U-shaped groove, trench, or recess in the second circumferential seal.

[0075] According to a preferred embodiment, the housing further includes at least one partial volume for receiving a portion of the first end cap within the housing, the partial volume preferably being located adjacent to the insertion opening and below, preferably immediately below or adjacent to, the undercut location within the housing.

[0076] According to a preferred embodiment, the filter media packs of the filter element are mounted in a twisted configuration.

[0077] The deformable filter element can have a maximum length greater than the height of the mounting cavity in the housing, and by twisting the media, the length of the filter element can be reduced to fit the housing, thereby advantageously allowing more filter media to be introduced into the same internal housing volume.

[0078] According to a preferred embodiment, the housing includes a housing sidewall that is open and disposed generally along an outer radial surface of the filter media pack that includes the grid structure.

[0079] According to a preferred embodiment, the radial sidewall of the cover is open and includes a grid structure.

[0080] According to a preferred embodiment, at least one of the grid structures of the housing sidewall or cover includes one or more flow guiding means, such as flow guiding ribs, fins or vanes.

[0081] It is advantageous to be able to position flow guides such as ribs, fins, or vanes in a predetermined configuration to provide optimal flow direction, for example, for the pleat positioning of the filter media pack or the expected media dust loading. Flow distribution per pleat is crucial for good filtration performance and optimal use of pleated filter media. In prior art installations, dust settles on one portion of the element, causing uneven loading, resulting in higher restrictions and suboptimal use of the filter media. By controlling either or any combination of the position, spacing, and / or angle of the ribs / fins / vanes, the airflow around the pack can be controlled to provide good, uniform flow distribution across all pleats. The fins, ribs, or vanes can also serve acoustic damping purposes or provide flow straightening, for example, for flow measurement purposes.

[0082] In a fourth aspect of the present disclosure, a filter housing is disclosed, the filter housing including an inlet and an outlet and adapted to sealingly receive a replaceable filter element such that air passing from the housing inlet to the housing outlet is filtered by the filter element, the housing including a maintenance opening for receiving the filter element within a main portion of the housing, the housing including a housing cover closing the maintenance opening, the housing inlet being provided in the main portion and / or the housing cover, and the inlet including a grid-like inlet structure.

[0083] According to a preferred embodiment, the housing includes a housing sidewall disposed generally along an outer radial surface of the filter media pack when installed within the housing, the outer radial surface including a grid structure.

[0084] According to a preferred embodiment, the radial sidewall of the cover includes a grid structure.

[0085] According to a preferred embodiment, at least one of the grid structures of the housing sidewall or cover includes one or more flow guiding means, such as flow guiding ribs or vanes, with the advantages similar to those described for the flow guiding means of the main housing.

[0086] According to a preferred embodiment, the main part of the housing and / or the housing cover comprises plastic.

[0087] According to a preferred embodiment, the main part of the housing and / or the housing is formed by injection molding.

[0088] In a fifth aspect of the present disclosure, a filter element is disclosed that includes a flexible filter media pack tubularly arranged about an axis, a first open end cap fluid-tightly connected to a first axial end of the filter media pack, and a second open end cap fluid-tightly connected to a second axial end of the filter media pack, the second open end cap including a central opening and a portion extending radially inward into the central opening of the second end cap, the radially inward extending portion including at least one circumferential groove, trench, or recess disposed adjacent to the central opening, the groove, trench, or recess projecting into an interior volume of the filter media pack or filter element.

[0089] According to a preferred embodiment, the circumferential grooves, trenches or recesses are oriented in a direction parallel to the axis of the filter media pack.

[0090] According to a preferred embodiment, the filter media packs are of the conical type, i.e., arranged in a conical shape, the cross section of each cone decreasing from a first axial end of the media pack to a second axial end of the media pack, the second end cap having a smaller diameter than the first end cap.

[0091] According to a preferred embodiment, the second end cap is flexible, eg, capable of being non-destructively transformed between a first shape and a different second shape.

[0092] According to preferred embodiments, the minimum radial cross-sectional dimension of the second shape of the second open end cap is at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 40%, at least 50%, or at least 75% smaller than the minimum radial cross-sectional dimension of the first shape.

[0093] According to preferred embodiments, the minimum radial cross-sectional dimension of the second shape of the second open end cap is at least 5 mm, at least 10 mm, at least 15 mm, at least 20 mm, at least 25 mm, or at least 5 cm smaller than the minimum radial cross-sectional dimension of the first shape of the second open end cap.

[0094] According to preferred embodiments, the second end cap can be radially deformed by a radial force component of less than 40N, less than 30N, less than 20N, or less than 10N.

[0095] According to a preferred embodiment, the second end cap is elastically deformable.

[0096] According to a preferred embodiment, the second end cap is substantially rigid.

[0097] According to a preferred embodiment, the second circumferential seal is integrally formed with the second end cap.

[0098] According to a preferred embodiment, the second circumferential seal includes an N-fold, eg, 1-fold, rotational symmetry about the filter media pack axis.

[0099] According to a preferred embodiment, the second circumferential seal includes at least one radially, inwardly or outwardly projecting lobe.

[0100] According to a preferred embodiment, the second circumferential seal includes at least one lobe that projects axially, inwardly or outwardly.

[0101] According to a preferred embodiment, the second circumferential seal is disposed along a plane that is inclined relative to a plane perpendicular to the filter media pack axis.

[0102] According to a preferred embodiment, the filter media pack comprises pleated media, the media comprising one or more layers selected from the group of a media layer and a support layer.

[0103] According to a preferred embodiment, the second end cap is connected to the filter media by potting, and possibly manufactured by potting.

[0104] In a sixth aspect of the present disclosure, a filter assembly is disclosed, including a filter housing having a housing axis and a filter element according to any of the embodiments of the fifth aspect disposed within the housing along the housing axis, the filter housing including a housing cover, the housing cover preferably having a conical shape and including a filter media pack inner support structure, such as a tower structure, protruding from an inner surface of the cover from a proximal end toward a distal end of the filter housing, the filter housing including a first end and a second end, the first end including a filter insertion opening and adapted to receive the cover, the second end disposed opposite the first end and including an outlet opening, and the second end further including a sealing surface complementary to the second circumferential seal for sealingly receiving the second circumferential seal.

[0105] According to a preferred embodiment, the distal end of the support structure is positioned and adapted to be received by an axially extending circumferential groove, trench, or recess in the second circumferential seal of the filter element and to provide radially outward back pressure on the circumferential seal against the sealing surface of the filter housing when the cover is attached to the housing.

[0106] According to a preferred embodiment, the second circumferential seal includes at least one radially projecting lobe, and the distal end of the support structure includes at least one radially inwardly projecting lobe corresponding to the at least one radially projecting lobe of the second circumferential seal.

[0107] According to a preferred embodiment, the second circumferential seal includes at least one axially projecting lobe, and the distal end of the support structure includes at least one axially inwardly projecting lobe corresponding to the at least one axially projecting lobe of the second circumferential seal.

[0108] In a seventh aspect of the present disclosure, a housing cover for a filter housing is disclosed, comprising an axial end wall connected to a circumferential side wall arranged about a longitudinal axis, wherein a projection of the axial end wall (or its contour) along the longitudinal axis on a plane perpendicular to the longitudinal axis comprises a 1-fold rotational symmetry about the longitudinal axis.

[0109] According to a preferred embodiment, the protrusion is generally rotationally symmetric, e.g., circular, but is rendered rotationally asymmetric by one, two or more flats or arc segments arranged as cut chord lines.

[0110] According to a preferred embodiment, the sidewall includes or defines a lower rim surrounding the housing interface opening, and the circumferential sidewall is interrupted (or includes one or more annular gaps), or is straight, or is substantially straight within one or more angular ranges about the longitudinal axis (in another view, the circumferential sidewall includes straight segments).

[0111] According to a preferred embodiment, the contour of the axial end wall generally corresponds to one or more subsequent sections of a predetermined circular shape, connected by one or more chord lines of the circular shape between adjacent circular sections, and the circumferential side wall is interrupted or straight in the area corresponding to the chord lines (defining one or more flat portions of the housing cover).

[0112] According to a preferred embodiment, the housing cover further includes a sensor port opening in the axial end wall.

[0113] According to a preferred embodiment, the housing cover includes an inner surface and a circumferential sealing surface disposed on the inner surface for receiving the filter element seal.

[0114] According to a preferred embodiment, the circumferential sealing surface projects axially from the axial end wall of the inner surface.

[0115] According to a preferred embodiment, the circumferential sealing surface includes an N-fold rotational symmetry.

[0116] According to a preferred embodiment, the housing cover includes one or more axial end wall openings in the axial end wall.

[0117] According to a preferred embodiment, the housing cover includes one or more, for example, centrally located, end wall outlet openings radially positioned within the circumferential sealing surface.

[0118] According to a preferred embodiment, the housing cover includes a second circumferential sealing surface disposed on the inner surface for receiving a second filter element seal, radially disposed within the first circumferential sealing surface, and one or more, e.g., centrally positioned, axial end wall inlet openings positioned radially within the second circumferential sealing surface.

[0119] According to a preferred embodiment, the second circumferential sealing surface includes an N-fold rotational symmetry.

[0120] According to a preferred embodiment, the housing cover includes a filter media support structure that projects axially or primarily axially from the inner surface from the axial end wall.

[0121] According to a preferred embodiment, the media support structure includes a tower structure, preferably a conical tower structure, extending axially from a proximal end of the inner surface of the cover to a distal end away from the cover. The tower can be manufactured separately from the cover and then joined, or the end cap and housing cover can be manufactured in a single step.

[0122] According to a preferred embodiment, the distal end of the tower structure includes an N-fold rotational symmetry about the longitudinal axis.

[0123] According to a preferred embodiment, the lower rim is defined by a plane inclined relative to a direction perpendicular to the longitudinal axis, which has the advantage that the cover automatically aligns with the housing when a force on the cover is applied (for example by manual manipulation or by the cover closing means).

[0124] According to a preferred embodiment, the axial end wall is disposed perpendicular to the longitudinal axis, and the circumferential side wall evolves between a minimum width at a minimum axial distance between the lower rim and the axial end wall and a maximum width at a maximum axial distance between the lower rim and the axial end wall.

[0125] According to a preferred embodiment, the housing cover sidewall includes one or more housing cover sidewall openings.

[0126] According to a preferred embodiment, the housing cover further includes at least a subcomponent of a cover closure means or device located at or near where the circumferential sidewall is interrupted (or includes one or more gaps) or is straight or substantially straight. Examples of such closure means or devices are, for example, latch and hook arrangements, finger locks, rubber bands, clips, bolts and nuts, wing nuts, etc. Preferably, the subcomponent interacts with a counterpart on the housing, and thus preferably interacts with a counterpart located on or adjacent to the undercut section of the housing entrance opening.

[0127] In an eighth aspect of the present disclosure, a filter assembly is disclosed having a main housing having a maintenance opening for receiving a filter element within the housing, and a housing cover covering the maintenance opening according to any of the embodiments of the seventh aspect, wherein the maintenance opening includes at least one or more undercut sections that are complementary to the interrupted or straight sections of the housing cover when the cover is disposed on the main housing.

[0128] In a ninth aspect of the present disclosure, a housing cover for a filter housing is disclosed, the housing cover including an axial end wall connected to a circumferential side wall arranged about a longitudinal axis and defining a lower rim of the side wall surrounding a filter housing interface opening, the lower rim being defined by a plane inclined relative to a direction perpendicular to the longitudinal axis.

[0129] According to a preferred embodiment, the axial end wall is disposed perpendicular to the longitudinal axis, and the circumferential side wall extends between a minimum width at a minimum axial distance between the lower rim and the axial end wall and a maximum width at a maximum axial distance between the lower rim and the axial end wall.

[0130] According to a preferred embodiment, the housing cover sidewall includes one or more housing sidewall openings.

[0131] According to a preferred embodiment, the housing cover further includes a sensor port opening in the axial end wall.

[0132] According to a preferred embodiment, the housing cover further includes an inner surface and a circumferential sealing surface disposed on the inner surface for receiving the filter element seal.

[0133] According to a preferred embodiment, the circumferential sealing surface projects axially from the axial end wall of the inner surface.

[0134] According to a preferred embodiment, the circumferential sealing surface includes an N-fold rotational symmetry.

[0135] According to a preferred embodiment, the housing cover further includes one or more axial end wall openings in the axial end wall.

[0136] According to a preferred embodiment, the housing cover includes one or more, for example, centrally located, axial end wall outlet openings radially positioned within the circumferential sealing surface.

[0137] According to a preferred embodiment, the housing cover further includes a second circumferential sealing surface disposed on an inner surface thereof for receiving a second filter element seal, radially disposed within the first circumferential sealing surface, and one or more centrally positioned axial end wall inlet openings positioned radially within the second circumferential sealing surface.

[0138] According to a preferred embodiment, the second circumferential sealing surface includes an N-fold rotational symmetry.

[0139] According to a preferred embodiment, the housing cover further includes a filter media support structure projecting axially from the inner surface from the axial end wall.

[0140] According to a preferred embodiment, the media support structure includes a tower structure, preferably a conical tower structure, extending axially from a proximal end of the inner surface of the cover to a distal end away from the cover.

[0141] According to a preferred embodiment, the distal end of the tower structure includes an N-fold rotational symmetry about the longitudinal axis.

[0142] According to a preferred embodiment, the circumferential sidewall is interrupted (or includes one or more annular gaps) or is straight within one or more angular ranges about the longitudinal axis.

[0143] According to a preferred embodiment, the contour of the axial end wall generally corresponds to one or more subsequent sections of a given circular shape connected by one or more chord lines of the circular shape between adjacent circular sections, and the circumferential side wall is straight or interrupted in the area corresponding to the chord lines (defining one or more flat portions of the housing cover).

[0144] In a tenth aspect of the present disclosure, an assembly includes a main housing having a servicing opening for receiving a filter element into the main housing, and a housing cover covering the servicing opening according to any of the embodiments of the ninth aspect, wherein the servicing opening includes a rim that lies in a plane that is inclined relative to a direction perpendicular to the longitudinal axis of the housing cover, corresponding to the inclined plane of the lower rim of the housing cover.

[0145] Any embodiment and configuration of an embodiment described with respect to any of the above aspects is also intended to be disclosed mutatis mutandis with respect to any of the other aspects. For example, any configuration described with respect to the filter element, assembly, packaging, or housing cover itself is intended to be disclosed with respect to the other aspects as well.

[0146] For example, the location of the undercut section in the insertion or maintenance opening of the housing can be as in any of the disclosed housing examples.

[0147] When the assembly is installed / in use, it may be advantageous to position at least one undercut section on the bottom or underside of the filter maintenance opening or filter housing. Such an undercut section creates the need to lift the filter element over the undercut section when removing the filter element / filter media pack, so that dust accumulated within the air purifier housing is not pulled out by sliding the filter element / filter media pack over the lower inner wall of the filter housing. The presence of an undercut section on the bottom or underside of the filter maintenance opening or filter housing when the assembly is installed / in use also provides the advantage that any liquid used to clean the inner wall of the housing can be contained within the housing by the undercut section. The undercut section on the bottom or underside of the filter maintenance opening or filter housing may also advantageously include a dust discharge opening or a dust discharge valve.

[0148] For example, in the case of a single undercut section, it may be advantageous to have the undercut section at the filter maintenance opening or the top surface of the filter housing when the assembly is installed / used. If the assembly receives the filter element in a horizontal orientation, the first end cap of the filter element can be positioned adjacent to or against the undercut section to hold the filter element in place and prevent downward tilting of the filter element within the housing, which could break the housing seal at the second end of the filter element.

[0149] Regardless of whether there is only one undercut section or multiple undercut sections, the presence of the undercut section is advantageous in that it can hold the filter element in place, i.e., it can prevent axial movement of the filter element within the housing along the housing axis.

[0150] These and further aspects of the present disclosure will now be described in more detail, by way of example, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0151] [Figure 1] 1 illustrates schematically a first preferred embodiment of the present disclosure; [Figure 2] 1 illustrates schematically a first preferred embodiment of the present disclosure; [Figure 3] 1 illustrates schematically a first preferred embodiment of the present disclosure;

[0152] [Figure 4] 2 shows a second preferred embodiment of the present disclosure. [Figure 5] 2 shows a second preferred embodiment of the present disclosure. [Figure 6] 2 shows a second preferred embodiment of the present disclosure.

[0153] [Figure 7] 1 shows a variation of the second preferred embodiment.

[0154] [Figure 8] 10(a)-10(c) show a third preferred embodiment of the present disclosure having open housing sidewalls and a sloped housing / cover interface. The concepts described are not limited to assemblies including the disclosed filter elements having flexible and / or resilient configurations, but may be applied more generally.

[0155] [Figure 9] 1 illustrates the concept of a flexible first end cap.

[0156] [Figure 10] 10(a) and (b) show a modification of the third preferred embodiment shown in FIG.

[0157] [Figure 11] 10(a)-(c) show modifications of the third preferred embodiment shown in FIG.

[0158] [Figure 12] (a) to (c) show a fourth preferred embodiment of the present disclosure. [Figure 13] 1 shows a fourth preferred embodiment of the present disclosure. [Figure 14] 1 shows a fourth preferred embodiment of the present disclosure.

[0159] [Figure 15] 10 illustrates a variation of the fourth preferred embodiment for, but not limited to, use in combination with an embodiment including a media pack support structure that protrudes from the inner surface of the housing cover. [Figure 16] 10 illustrates a variation of the fourth preferred embodiment for, but not limited to, use in combination with an embodiment including a media pack support structure that protrudes from the inner surface of the housing cover.

[0160] [Figure 17] 10(a) to 10(c) show a fifth embodiment of the present disclosure in which there is no medium support means protruding from the inner surface of the housing cover.

[0161] [Figure 18] 10(a) and 10(b) show a housing cover configuration for use with any of the embodiments of the present disclosure. [Figure 19] 10(a) and 10(b) show a housing cover configuration for use with any of the embodiments of the present disclosure. [Figure 20] 10(a) and 10(b) show a housing cover configuration for use with any of the embodiments of the present disclosure.

[0162] [Figure 21] 1(a)-(c) show some examples of first and second circumferential seal configurations and associated sealing surfaces on the housing cover and housing. [Figure 22]1(a)-(c) show some examples of first and second circumferential seal configurations and associated sealing surfaces on the housing cover and housing. [Figure 23] 1(a)-(c) show some examples of first and second circumferential seal configurations and associated sealing surfaces on the housing cover and housing. [Figure 24] (Several examples of first and second circumferential seal configurations and associated sealing surfaces on the housing cover and housing are shown.

[0163] [Figure 25] 10(a) and 10(b) show examples of housing cover locking mechanisms for use with embodiments of the present disclosure.

[0164] [Figure 26] (a)-(c) show further preferred embodiments of the present disclosure in which the first and / or second end caps and their corresponding circumferential seals are angled relative to the longitudinal axis of the filter element / filter media pack.

[0165] [Figure 27] 10(a) to 10(c) show aspects of elastic deformation of an end cap of a filter element according to an embodiment of the present disclosure.

[0166] [Figure 28] 10(a) and 10(b) show a further preferred embodiment of the present disclosure in which the filter media pack is modified by a media support structure that protrudes from the housing cover.

[0167] [Figure 29] (a) shows a sixth preferred embodiment of the present disclosure, including first and second main filter elements, the second filter element being not a safety filter element but filtering unfiltered airflow in parallel with the first filter element, and (b) shows a seventh preferred embodiment of the present disclosure.

[0168] [Figure 30] FIG. 10 illustrates a sixth preferred embodiment of the present disclosure, including first and second primary filter elements, the second filter element being not a safety filter element but filtering the unfiltered airflow in parallel with the first filter element.

[0169] [Figure 31] (a) and (b) show a modification of the sixth preferred embodiment of the present disclosure. [Figure 32] 10 illustrates a modification of the sixth preferred embodiment of the present disclosure.

[0170] [Figure 33] 10 illustrates a variation of the seventh preferred embodiment.

[0171] [Figure 34] (a) to (c) show modifications of the seventh preferred embodiment of the present disclosure.

[0172] [Figure 35] 1(a) and 1(b) show advantageous packaging associated with the filter elements associated with the present disclosure.

[0173] [Figure 36] 1 shows the integration of a dust exhaust valve in the undercut section.

[0174] [Figure 37] (a) and (b) show examples of a first end cap equipped with an operating means.

[0175] [Figure 38] (a) illustrates a potential problem that arises when the distal end of the support structure is received by a trench in the circumferential seal, and (b) illustrates a further preferred embodiment for the configuration of the distal end of the inner support structure and the second circumferential seal.

[0176] [Figure 39](a) illustrates a potential problem that arises when the distal end of the support structure is received by a trench in the circumferential seal, and (b) illustrates a further preferred embodiment for the configuration of the distal end of the inner support structure and the second circumferential seal. [Figure 40] (a) and (b) illustrate potential problems that arise when the distal end of the support structure is received by a trench in the circumferential seal, and (b) illustrates a further preferred embodiment for the configuration of the distal end of the inner support structure and the second circumferential seal. [Figure 41] (a) and (b) illustrate potential problems that arise when the distal end of the support structure is received by a trench in the circumferential seal, and (b) illustrates a further preferred embodiment for the configuration of the distal end of the inner support structure and the second circumferential seal.

[0177] [Figure 42] 13 illustrates a housing and a housing cover according to an eighth preferred embodiment of the present disclosure. [Figure 43] 13 illustrates a housing and a housing cover according to an eighth preferred embodiment of the present disclosure.

[0178] [Figure 44] 13 illustrates a filter element and its installation process for possible use with a housing and housing cover according to an eighth preferred embodiment of the present disclosure.

[0179] The drawings of the figures are not drawn to scale or to proportion, and generally, identical components are designated by the same reference numerals in the figures. DETAILED DESCRIPTION OF THE INVENTION

[0180] The present disclosure is described with reference to particular embodiments that are illustrative of the disclosure and should not be construed as limiting. Those skilled in the art will understand that the disclosure is not limited to what is specifically shown and / or described, and that alternative or modified embodiments may be developed in light of the overall teachings of the present disclosure. The drawings described are only schematic and are non-limiting.

[0181] The use of the verb "to comprise" and its respective conjunctions does not exclude the presence of elements other than those stated. The use of the article "a", "an" or "the" preceding an element does not exclude the presence of a plurality of such elements.

[0182] Furthermore, terms such as first, second, and the like in this specification and claims are used to distinguish between similar elements and are not necessarily intended to describe a sequence temporally, spatially, in order, or in any other way. Terms so used are interchangeable under appropriate circumstances, and it should be understood that the disclosed embodiments described herein are capable of operating in sequences other than those described or illustrated herein.

[0183] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular configuration, structure, or feature described in connection with an embodiment is included in one or more embodiments of the present disclosure. Thus, appearances of the phrase "in one embodiment" or "in an embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment, although they may. Furthermore, particular configurations, structures, or features may be combined in any suitable manner in one or more embodiments, as will be apparent to one of ordinary skill in the art from this disclosure.

[0184] Although many of the figures presented and discussed below specifically depict embodiments of filter elements for filtering air, the present disclosure is not limited thereto.

[0185] Although reference is made herein to a main housing portion 1 and a housing cover 3, the actual selection should be made. Alternatively, these portions can be referred to as a first housing portion 1 and a second housing portion 3. In fact, when the housing cover 3 is relatively large, for example, such that the housing cover 3 includes most of the complete filter housing, it may be appropriate to refer to the housing cover 3 as the main housing portion 1, while the remainder of the housing can be viewed as the housing cover 3. In certain embodiments, the main portion of the housing is the portion that includes the mounting means 112 for the air purifier.

[0186] 1 to 3 schematically show a first preferred embodiment of the present disclosure.

[0187] A filter element 2 including a flexible filter media pack 20 is tubularly disposed about an axis. A first open end cap 21 is fluid-tightly connected to a first axial end 25 of the filter media pack 20. A second open end cap 22 is fluid-tightly connected to a second axial end 26 of the filter media pack 20. The first and second end caps 21, 22 can be formed and attached to the filter media pack 20 by, for example, a polyurethane potting process. In such a case, a first circumferential seal 27 of the first end cap 21 and a second circumferential seal 28 of the second end cap 22 can be formed during the same process. The first circumferential seal 27 is a portion of the first end cap 21 that extends radially inward. The second circumferential seal 28 is a portion of the second end cap 22 that extends radially outward, for example. Both circumferential seals 27, 28 are generally cylindrical. The filter media pack 20 is conically shaped in its undeformed state.

[0188] The first end cap 21 is flexible, e.g., capable of being non-destructively deformed between a first shape and a different second shape. Preferably, it is elastically deformable.

[0189] The filter element 2 is disposed within a primary filter housing 1 having a housing sidewall 11, a first end 15, and a second end 16. The first end 15 includes a filter insertion opening 13. The second end 16 is disposed at an end opposite the first end 15 and includes an outlet opening 121 or an outlet tube 12 with the outlet opening 121. The second end 16 further includes a sealing surface 19 complementary to the second circumferential seal 28 for sealingly receiving the second circumferential seal 28 about the outlet opening 121 when the filter element 2 is inserted into the housing 1.

[0190] A servicing opening 13 at a first end 15 includes two undercut sections 14 that extend radially inward from the side wall 11 of the housing 1 .

[0191] For example, because the filter element 2 is essentially conical, the second end cap 22, which may not be non-destructively deformable, can be guided toward the second end 16 of the housing 1 to enter and be installed in the maintenance opening 13. However, the first end cap 21 is too large to pass through the undercut section 14 of the insertion opening 13. Because the first end cap 21 is non-destructively deformable, e.g., elastically deformable, the first end cap 21 can be reshaped into a second shape or state that is smaller and can enter the maintenance opening 13. Deformation of the first end cap is shown, for example, in FIG. 9. Optionally, a manipulation device or means, such as a handle, can be provided that fits and is positioned radially inward or that pulls a portion of the first end cap radially inward (see, for example, FIGS. 37(a) and (b)). The manipulation means or device can include a handle bar or structure that bridges both sides of the open end cap over a central opening in the first end cap. Alternatively, the optional operating means may include at least one radially inwardly or outwardly directed flap or ear structure.

[0192] When the first end cap 21 passes through the maintenance opening 14, the first end cap 21 returns to its original shape and is positioned partially below the undercut section 14 within the sub-volume 131 of the interior volume of the filter housing 1. It can be seen that the protrusion of the filter element 2 along the housing axis intersects with the protrusion of the undercut section 14 along the housing axis, the intersection corresponding to the protruding overlap region.

[0193] Next, a housing cover 3 is provided to close the housing insertion or maintenance opening 13 (FIG. 3). The housing cover 3 preferably includes a filter media pack inner support structure 31, such as a tower structure 31, having a conical shape projecting from a proximal end to a distal end at an inner surface 301. The tower structure 31 is open in nature and may include a rib or grid structure 32, which may function as an inner liner for the filter media pack 20. When the cover 3 is attached to the main housing 1, the proximal end of the tower structure 31 is closed, forming a sealing surface 37 for the first circumferential seal 27. In this case, the cover 3 also covers the undercut section 14 of the maintenance opening 13.

[0194] The housing also includes an inlet 17. One or more inlet openings may be provided in the side wall 11 of the housing 1, for example.

[0195] Figures 4-6 show a second preferred embodiment of the present disclosure, which is very similar to the first preferred embodiment. It includes a housing inlet tube positioned to allow filtered air to enter the filter housing perpendicular to the housing and filter axis. The air then passes through a filter media pack 20 into the filter's internal volume and exits the air purifier through an outlet opening 12. Two diametrically opposed undercut sections 14 are present within the maintenance opening 13.

[0196] At least one of the undercut sections 14 includes alignment features 141 for aligning with corresponding alignment features on the cover 3. A plurality of closure means or devices, such as latches 302, are provided on the outer surface 300 of the housing cover 3 to lock the cover 3 to the main housing 1. The latches 302 on the cover 3 are configured to lock behind locking features 18 located on the side wall 11 of the main housing 1 at corresponding locations. The first circumferential seal 27 seals against one or more sealing surfaces 37 on the inner surface 301 of the housing cover.

[0197] Preferably, one of the closure means, such as latch 302, is positioned on or adjacent flat 3F and interacts with a counterpart on the housing, preferably adjacent flat 14F or adjacent undercut 14 below flat 14F. Of course, other closure means may be utilized, such as, for example, a finger lock, rubber band, clip, bolt, and nut.

[0198] 7 shows a variation of the second preferred embodiment. The air cleaner includes an additional element 4 for interacting with the fluid or air flow, such as a safety filter element or a chemical filtration element. The additional element 4 is disposed within the media pack support structure or tower 31 and extends from the second end 16 of the housing partially toward the first end 15. The additional element may include, for example, a circumferential seal directed radially outward to seal against the inner sealing surface of the outlet tube 12.

[0199] 8(a)-8(c) show a third preferred embodiment of the present disclosure, which is similar to the previously described preferred embodiment but includes a sloped housing / cover interface S. The described concepts are not limited to assemblies including the disclosed filter elements having a flexible and / or resilient configuration, but can be more generally applied to non-destructively deformable filter elements 2. Moreover, the housing cover 3 includes a single flat portion 3F that is complementary to the single undercut section 14 of the service opening 13.

[0200] The housing cover 3 and the filter housing 1 are configured so that they meet along an inclined plane S, with the inclined plane S being such that the housing length L of the main housing 1 on the side corresponding to the undercut section 14 is longer than the housing length L on the opposite side of the housing. This provides the advantage of allowing some tilting of the filter element 2, for example, away from the undercut section 14, before removing the filter element from or inserting the filter element into the maintenance opening 13 in the main housing 1, which allows the use of filter elements 2 having a relatively less deformable or non-deformable first end cap 21 or the use of relatively more deformable elements.

[0201] The housing cover 3 includes an axial end wall 30e connected to a circumferential side wall 30 disposed about the longitudinal axis, and includes a lower rim 30r of the side wall 30 that surrounds the filter-housing interface opening. The lower rim 30r is defined by a plane that is inclined relative to a direction perpendicular to the longitudinal axis.

[0202] The axial end wall 30e of the cover 3 is arranged perpendicular to the longitudinal axis, and the circumferential side wall 30 evolves between a minimum width at a minimum axial distance between the lower rim 30r and the axial end wall 30e and a maximum width at a maximum axial distance between the lower rim 30r and the axial end wall 30e.

[0203] The contour (or protrusion in a plane perpendicular to the axis) of the axial end wall 30e of the housing cover 3 corresponds to one predetermined circular section (or possibly more subsequent sections) connected by one (or more) circular chord lines between adjacent circular sections, and the circumferential side wall 30 is interrupted or straight within the area corresponding to the chord lines. The interrupted or straight sections correspond to the flat portion 3F. The flat portion 3F and the undercut section 14 (e.g., the straight chord surface 14F of the undercut section 14) of the cover 3 function as an alignment feature between the cover 3 and the main housing 1 so that they abut each other when the cover 3 is placed on the main housing 1.

[0204] The maintenance opening in the main housing includes a rim 1311 that lies in a plane that is inclined relative to a direction perpendicular to the longitudinal axis of the housing or housing cover, corresponding to the inclined plane of the lower rim 30r of the housing cover 3.

[0205] 10(a)(b) show a variation of the third preferred embodiment shown in FIG. 8, which includes an open housing sidewall 11 including a grid structure, preferably including openings 111 separated by flow guide blades or fins 110 (which can be an inlet, or alternatively a closed sidewall with a separate inlet opening). It further includes a latch connection toward the housing cover 3 arranged on the undercut section 14, and the housing cover 3 includes a catch surface for the latch adjacent to the flat portion 3F (or vice versa). The undercut section 14 is positioned on the side of the housing attachment means 112, which is often the side that is difficult to reach during maintenance. Compared to a latch attached to the housing sidewall 11 at the side of the housing attachment means 112, it has the advantage that it is easier to reach the latch on the undercut section 14 when performing maintenance.

[0206] 11(a)-(c) show a variation of the third preferred embodiment shown in FIG. 8 which also has a closed housing side wall 11 of the housing 1 and includes a catch surface connection and latch between the side walls 30, 11 of the housing cover 3 and the main housing side wall 11.

[0207] 12(a)-(c), 13, and 14 illustrate a fourth preferred embodiment of the present disclosure, which is similar to the third preferred embodiment, variations of which are disclosed in connection with FIGS. 8, 10, and 11.

[0208] According to a fourth preferred embodiment, when the filter element 2 is mounted in the main housing 1 and the main housing 1 is closed by the cover 3, the distal end 303 of the support means or tower 31 of the cover 3 interacts with the second circumferential seal 28 of the filter element 2.

[0209] The filter element 2 includes a (preferably, but not necessarily, flexible) filter media pack 20 tubularly arranged about an axis, a first open end cap 21 fluid-tightly connected to a first axial end 25 of the filter media pack 20, and a second open end cap 22 fluid-tightly connected to a second axial end 26 of the filter media pack 20. The filter element 2 and media pack 20 are conical in shape. The cross section of the filter media pack cone decreases from the first axial end 25 of the media pack to the second axial end 26 of the media pack 20. The second end cap 22 has a smaller outer diameter than the first end cap 21.

[0210] The second open end cap 22 includes a central opening and a second circumferential seal 28. The second circumferential seal 28 is disposed radially inward within a central opening extension of the second end cap 22. The radially inward extending portion includes at least one circumferential (e.g., U-shaped or V-shaped) groove, trench, or recess 281 disposed adjacent to the central opening. The groove, trench, or recess projects into the interior volume of the filter media pack 20 (or into the interior volume of the filter element), for example, in a direction parallel to the axis of the filter media pack 20 or filter element 2.

[0211] The filter housing includes a first end 15 and a second end 16, where the first end 15 includes a filter insertion opening 13 and is configured to receive the cover 3 on the tower 31. The second end 16 is disposed opposite the first end 15 and includes an outlet opening 121. The second end 16 further includes a sealing surface 19 complementary to the second circumferential seal 28 for sealingly receiving the second circumferential seal 28 when the filter element 2 is properly installed within the housing.

[0212] In this disclosure, the terms inlet and outlet are used to refer to openings in the housing through which airflow passes "from the inlet to the outlet." Those skilled in the art know that in certain assembly configurations, reverse flow may be applicable, and this reverse flow may be in the opposite direction from the outlet to the inlet. This does not affect the essence of the inventive concept of the present disclosure.

[0213] The distal end 303 of the support structure 31 is positioned and adapted to be received by the axially extending circumferential groove, trench, or recess 281 of the second circumferential seal 28 of the filter element 2 and to provide radially outward back pressure on the circumferential seal 28 toward the sealing surface 19 of the filter housing 1 when the cover 3 is attached to the housing 1.

[0214] 15 and 16 show variations of the fourth preferred embodiment, possibly for use in combination with embodiments including a media pack support structure 31 that protrudes from the inner surface 301 of the housing cover 3, but are not limited thereto.

[0215] In the embodiment shown in FIG. 15 , the distal end 303 of the support structure 31 includes at least one radially inwardly projecting lobe 303r that corresponds to the at least one radially inwardly projecting lobe 28r of the second circumferential seal 28 and that corresponds to the at least one radially inwardly projecting lobe 19r of the second circumferential seal face 19.

[0216] In the embodiment shown in FIG. 16 , the distal end 303 of the support structure 31 includes at least one axially inwardly projecting lobe 303s that corresponds to at least one axially inwardly projecting lobe 28s of the second circumferential seal 28 and that corresponds to at least one axially inwardly projecting lobe 19s of the second circumferential seal face 19.

[0217] The embodiment of FIGS. 15 and 16 allows for rotational locking of the filter element and a predetermined clocking or angular orientation of the filter element 2 within the housing 1 .

[0218] In further embodiments, the support structure or tower 31 is not present. The interactions at the distal end of the support structure or tower 31 as described in connection with FIGS. 12-16 can then be replaced by similar interactions between a separate attachment device (not shown), for example, inserted into at least one circumferential (e.g., U-shaped or V-shaped) groove, trench, or recess 281 positioned adjacent the central opening, performing the same function as described for the distal end 303. The attachment device can, for example, generally include a ring structure and can have similar radially and axially inwardly projecting lobes as disclosed for the distal end of the tower 31. This may also be true for the embodiment described in connection with FIG. 44.

[0219] 17(a)-(c) show a fifth preferred embodiment of the present disclosure, which does not have a media support means protruding from the inner surface of the housing cover. This embodiment is similar to all of the previous embodiments except for the presence of the media support means or tower 31 and the possible interaction of the tower (distal end 303) with the second circumferential seal. In fact, when the filter element 2 does not include flexible or resiliently deformable portions for, for example, the first end cap 21, the media pack 20, and the second end cap 22, the same advantages exist regarding the interaction between the main housing 1, the housing cover 3, and the filter element 2, for example, regarding having a sloped interface S between the housing cover 3 and the main housing 1, and regarding having an undercut section 14 in the housing inlet opening 13 and a complementary flat portion 3F on the housing cover 3.

[0220] 18(a)(b), 19(a)(b), and 20(a)(b) show housing cover configurations for use with any of the embodiments of the present disclosure.

[0221] 18(b) shows that the housing cover 3 can be flat, which can further include the disclosed flat section 3F (interrupted or straight) for alignment and other disclosed purposes.

[0222] 18(a) shows a housing cover 3, as disclosed with respect to, for example, FIGS. 8, 10-12, and 17, including an upper or outer surface 300 oriented along a plane P1 perpendicular to the housing cover axis. A lower rim 30r of a side wall 30 of the housing cover 3 is disposed along a second plane P2 inclined relative to the plane perpendicular to the housing cover axis. The angle α between the planes can be, for example, between 10° and 45°, more preferably between 5° and 30°.

[0223] 19(a) shows a top view of a housing cover 3 according to an embodiment of the present disclosure, having a single flat portion 3F. * The virtual complement is marked with a dotted line which corresponds to the undercut section 14 in the associated housing.

[0224] 19(b) shows a top view of a housing cover 3 according to an embodiment of the present disclosure, having two flat portions 3F and 3F'. * , 14 *’ are marked with dotted lines corresponding to the respective undercut sections 14, 14' in the associated housing. The flats 3F and 3F' may be parallel or may be less than the angle β.

[0225] 20 shows an advantageous configuration for the disclosed housing cover 3 and filter assembly, in which a sensor port 5, for example, having a pressure sensor 50, is provided in the center of the housing cover 3 with a small associated opening toward the clean side of the filter assembly. Advantageously, the pressure sensor can be visually inspected on the maintenance side of the housing 1 since there is access to the clean side.

[0226] 21-24 show some examples of first and second circumferential seal configurations and associated sealing surfaces on the housing cover and housing.

[0227] One or both of the first and second circumferential seals 27 and 28 can have a rotationally symmetric profile or can include rotational asymmetry. The same is true for their corresponding seal faces 37, 19.

[0228] Both circumferential seals 27 and 28 and their corresponding sealing surfaces 19 and 37 may be adapted for rotational positioning and locking of the filter element relative to the housing or relative to the housing cover, for example.

[0229] For example, as shown in Figures 21(a)(b), the first circumferential seal 27 and corresponding seal surface 37 can include a gear-type configuration, for example, as described in EP 3413993. The second circumferential seal 28 can be a rotationally symmetric radially (inwardly or outwardly) oriented seal to seal on the second circumferential seal surface 19, which is, for example, cylindrical.

[0230] 21(c) shows another embodiment in which first circumferential seal 27 includes a rotationally symmetric radially (inwardly or outwardly) oriented seal for sealing on cylindrical first circumferential seal surface 37. Second circumferential seal 28 can include an inwardly oriented gear-type configuration, as described, for example, in EP 3413993. Second circumferential seal surface 19 can have a corresponding outwardly oriented gear-type configuration, as described, for example, in EP 3413993.

[0231] 22(a)(b), the first circumferential seal 27 and corresponding seal surface 37 can include a flower-type configuration, for example, as described in EP 2771092. The second circumferential seal 28 can be a rotationally symmetric radially (inwardly or outwardly) oriented seal to seal on the second circumferential seal surface 19, which is, for example, cylindrical.

[0232] 22(c) shows another embodiment in which first circumferential seal 27 includes a rotationally symmetric radially (inwardly or outwardly) oriented seal for sealing on cylindrical first circumferential seal surface 37. Second circumferential seal 28 can include an inwardly oriented flower-type configuration, for example, as described in EP 2771092. Second circumferential seal surface 19 can have a corresponding outwardly oriented gear-type configuration, for example, as described in EP 2771092.

[0233] 23(a)(b) disclose a further embodiment in which the first circumferential seal 27 and corresponding first circumferential seal surface 37 are elliptical. The second circumferential seal 28 can be a rotationally symmetric radially (inwardly or outwardly) oriented seal to seal over the second circumferential seal surface 19, which is, for example, cylindrical.

[0234] 23(c) shows a further embodiment in which the first circumferential seal 27 comprises a rotationally symmetric radially (inwardly or outwardly) oriented seal for sealing on a cylindrical first circumferential seal surface 37. The second circumferential seal 28 can be, for example, an elliptical seal that is radially (inwardly or outwardly) oriented for sealing on a corresponding elliptical second circumferential seal surface 19.

[0235] 24 is a projection view of another embodiment of the present disclosure, which is a combination of the embodiments of FIGS. 23(a), (b), and (c), in which both the first and second circumferential seals 27, 28 are elliptical and seal on corresponding elliptical sealing surfaces 37, 19. The elliptical shape may have its major axis subtending an angle, for example, a 90° angle or an angle between 15° and 19°.

[0236] Generally, examples are described with reference to Figures 21-23. Having first seal 27 and second seal 28 of different shapes is advantageous because it allows the user to install the cone in the correct orientation. Installing the cone in the wrong orientation can cause damage to the filter element.

[0237] Other combinations of the disclosed first and second circumferential seals 27, 28 and their corresponding sealing surfaces 37, 19 are contemplated and are contemplated as disclosed.

[0238] In embodiments where both the first and second circumferential seals have respective rotational locking features relative to the longitudinal axis of the filter element or filter housing, and the filter media pack 20 of the filter element is flexible, an advantageous configuration of the filter assembly is provided, in which the tubular filter media pack is twisted and therefore contains relatively more media per housing interior volume. Such a configuration of the assembly can be achieved as follows: The second circumferential seal 28, and thus the second end cap 22, can be inserted into the housing 1 in a fixed / locked angular position relative to the housing 1 (e.g., relative to the housing outlet 12). The filter element extends beyond the housing cavity and protrudes from the maintenance opening 13. The first circumferential seal 27 then mates with the sealing surface 37 of the housing cover 3 in a fixed / locked angular position relative to the cover 3. One or more flats 3F, 3F' of cover 3 and one or more complementary undercut sections 14, 14' of housing inlet 13 can then be aligned by rotating the cover relative to the housing through a predetermined angle, thereby twisting media pack 20 in a predetermined manner and shortening media pack 20 so that filter element 2 can refit into the housing cavity and the housing cover can be closed. This principle is shown schematically in Figure 25. Figure 25 also shows an example of a locking mechanism 333 of housing cover 3 to housing 1 for use with embodiments of the present disclosure, which can be, for example, a bayonet type or any other cutting-edge type.

[0239] 26(a)-(c) show further preferred embodiments of the filter element of the present disclosure in which the first and / or second end caps 21, 22 and their corresponding circumferential seals 27, 28 are inclined relative to a plane perpendicular to the longitudinal axis of the filter element 2 / filter media pack 20.

[0240] 26(a) and 26(b), the second end cap 22 is perpendicular to the filter axis, while the first end cap 21 is inclined relative to a plane perpendicular to the longitudinal axis. Respective circumferential seals 27, 28 are oriented along the plane defined by the end caps 21, 22.

[0241] In Figure 26(c), both the first end cap 21 and the second end cap 22 are inclined relative to a plane perpendicular to the longitudinal axis. Respective circumferential seals 27, 28 are oriented along the plane defined by the end caps 21, 22.

[0242] 27(a)-(c) illustrate, in a projection view along the filter element axis, an embodiment of elastic deformation of a first end cap 21 of a filter element according to an embodiment of the present disclosure. The filter media pack and first circumferential seal 27, as well as the central opening of the filter media pack 20, are elliptical. Although the service opening 13 is elliptical, the first end cap 21 cannot pass through the inlet opening 13 without deforming, primarily due to the presence of two undercut sections 14, 14' on either side of the service opening. In FIG. 27(b), the first end cap 21 (including the first circumferential seal 27) and media pack are elastically deformed to allow the second end cap 21 to pass through the service opening in a deformed state. In FIG. 27(c), the filter element 2 passes through the service opening 13 and elastically returns to its initial configuration, occupying the space below the undercut sections 14, 14'.

[0243] 28(a) and 28(b) show a further preferred embodiment of the present disclosure, in which a filter media pack 20 is deformed by a media support structure 31 protruding from a housing cover 3. The filter element 2 is elastically deformable and has a cylindrical or conical shape. It is inserted into a filter housing 1 whose sidewalls have a different shape (e.g., a constant cross-section, D-shaped in projection). The maintenance opening 13 has, for example, the same shape as the housing cross-section. The elastically deformable filter element 2 is inserted into the housing 1 and guided in its deformed state by the maintenance opening and the housing sidewall. After installation, the elastically deformable filter element 2 is adapted to or assumes the shape of the filter housing volume. Next, when the housing cover 3 is placed on the housing 1, a filter media support means or tower protruding from the housing cover 3 is inserted inside the filter media pack 20 to support the filter media pack 20 from the inside.

[0244] 29(a) and 30 illustrate a sixth preferred embodiment of the present disclosure, including first and second primary filter elements 2, 6, where the second filter element 6 is not a safety filter element and filters unfiltered airflow in parallel with the first filter element 2. The cover 3 includes a second circumferential sealing surface 37' disposed on the inner surface 301 for receiving an additional circumferential seal 67 of the second filter element 6, radially disposed within the first circumferential sealing surface 37. The cover further includes one or more inlet openings O3A, e.g., centrally located in the axial end wall of the housing cover 3, radially positioned within the second circumferential sealing surface 67. The second filter element may be, e.g., conical, contain a tubular arrangement or pleated media, and have a closed end cap opposite the seal 67. Air O3A entering the openings then enters the clean air side of the first filter element and is filtered by the second filter element 6 before exiting the filter assembly through the outlet 12.

[0245] Figures 31(a)(b) and 32 show variations of the sixth preferred embodiment of the present disclosure. In Figures 31(a)(b), a second filter element 6 is provided that includes a grooved media type media 60, e.g., wound grooved media. The cover includes a centrally positioned inlet opening O3A within the axial end wall of one or more housing covers 3, radially positioned within the second circumferential sealing surface 67. Air entering the opening O3A then enters the clean air side of the first filter element 2 and is filtered by the second grooved filter element 6 before exiting the filter assembly through the outlet 12. Figure 32 shows a variation in which the inlet opening O3A further includes a vane or waffle arrangement O3AW that includes airflow-guiding ribs that enable increased uniformity of the inlet airflow. The airflow-guiding ribs are preferably parallel to the axis of the grooved media pack 60.

[0246] 29(b) shows a seventh preferred embodiment of the present disclosure. The cover 3 includes one or more centrally positioned axial end wall outlet openings O3B, for example, radially positioned within the first circumferential sealing surface 37 and the first circumferential seal 27. The outlet openings O3B thereby form second outlets 12' for the clean air of the housing 1, which can be directed to a second air consuming means, such as a compressor.

[0247] 33 shows a variation of the seventh preferred embodiment, in which a single, centrally positioned second outlet opening O3B is provided, which can, for example, be part of a second outlet conduit of the housing 1 (in the outlet cover 3).

[0248] 34(a)-(c) show a variation of the seventh preferred embodiment of the present disclosure. It includes a single, centrally positioned second outlet opening O3B, as in the embodiment of FIG. 33. It further includes a set of openings 33t in the housing cover 3, radially outward of the first circumferential sealing surface 37 and distributed circumferentially around the peripheral region of the housing cover 3. One or more or all of the set of openings 33t extend from the axial end face of the housing cover to the radial sidewall 30 of the housing cover 3. The openings then function as additional air inlets for the filter assembly. The radial sidewall 30 of the housing cover 3 may further include openings 33, optionally defined in a grid structure between flow guides or devices 34, such as ribs, fins, or blades, as previously described, and also between inlet openings.

[0249] Alternative configurations of the distal end 303 of the internal support structure or tower 31 having a circumferential groove, trench, or recess 281 as described with respect to various embodiments, e.g., the embodiments relating to Figures 1-16 and 30-31, are shown in Figures 38(b), 39, 40(a)(b), and 41(a)(b).

[0250] 38(a) illustrates a potential problem that arises when the distal end of a support structure is received by a trench in circumferential seal 28. When trench 281 in seal 28 includes localized deformation and / or when distal end 303 of support structure 31 is not perfectly aligned with trench 28 upon insertion, distal end 303 may press against seal 28 at a location adjacent trench 281, causing deformation of seal 28 such that trench 281 is at least locally deformed or closed and distal end 303 is not received in trench 281.

[0251] FIG. 38(b) shows a groove 281 having a radially inner sidewall 2813 and a radially outer sidewall 2812 connected by a bottom wall 2815. The radially outer sidewall 2812 includes a sloped or chamfered portion or surface 2814 adjacent the opening of the trench 281, resulting in a widening of the trench 281 adjacent its opening. The sloped portion of the surface 2814 simplifies positioning and / or receipt of the distal end 303 of the inner support structure 31 by the trench 281. Preferably, at a level below the sloped portion 2814, the width of the trench 281 is between 2 and 10 mm, or between 3 and 8 mm. At the opening of the trench 281, the width of the trench 281 may increase by about 1 to 6 mm, or by about 3 to 5 mm, due to the sloped portion or surface 2814. The angled portion 2814 preferably forms an angle with the radially inner sidewall 2813 within a range between 10° and 45°. Apart from the angled portion 2814, there may be a small angle between the non-angled portion of the radially inner sidewall 2813 and the radially outer sidewall 2812. That is, these sidewalls are not perfectly parallel. They may be angled, for example, between 0° and 10°, preferably between 1° and 7°, e.g., 2°. The depth of the circumferential trench 281 may be, for example, within a range between 5 mm and 40 mm or between 10 mm and 40 mm.

[0252] It has been found that in some cases, when the distal end 303 of the inner support structure 31 is received into the cavity formed by the sidewalls (2812, 2813, 2815) of the trench 281 and the distal end 303 of the inner support structure 31, a closed air pocket may be created within the trench 281. During reception, this air pocket may provide resistance to the insertion process. Also, during removal, the air pocket may jeopardize easy removal of the inner support structure 31 because the air pocket may result in underpressure during the removal process. FIG. 39 shows an embodiment that solves the above problem. The radially outer sidewall 2812 (or the radially inner sidewall 2813) includes one, two, or multiple axially extending fluid communication channels 2811. These channels preferably connect the cavity formed by the sidewalls ( 2812 , 2813 , 2815 ) of trench 281 and distal end 303 of inner support structure 31 to the interior volume of filter element 2 .

[0253] 40(a)(b) show a groove 281 having a radially inner sidewall 2813 and a radially outer sidewall 2812 connected by a bottom wall 2815. The radially outer sidewall 2812 may include a sloped portion or surface 2814 adjacent the opening of the trench 281, as previously described. The second circumferential seal 28 preferably further includes a plurality of, preferably regularly spaced, spacing ribs 2816 that bridge the radially inner and outer sidewalls (2813, 2812) by connecting them in a direction perpendicular to the circumferential direction of the trench 281. This provides the advantage that the trench width may be more constant. Pockets 2817 are thereby created in the trench 281 between adjacent spacing ribs 2816. These pockets 2817 can receive axially extending segments 3031 ("teeth") on the distal end of the distal end 303 of the associated inner support structure 31. In another view, the distal end 303 can include a series of regularly spaced axial cuts that receive the spacing ribs 2816 when the inner support structure 31 is received by the trenches 281 in one of a plurality of relative angular alignment positions.

[0254] 41(a)(b) show a variation of the embodiment of FIG. 40(a)(b) in which only a single relative angular alignment position between the inner support structure 31 and the trench 281 is possible.

[0255] 41(a), preferably, one pocket 2817' of the regularly spaced pockets 2817 is deeper than the other pockets and is provided in the axial extension 2819 of the circumferential seal 28. The pocket 2817' can receive a corresponding tooth 3031' that is longer than the other tooth 3031 on the distal end 303. Only when the longer tooth 3031' aligns with the deeper pocket will the inner support structure 31 be properly received by the trench 281.

[0256] 41(b), preferably, a portion of the seal 28 corresponding to the location of one of the regularly spaced pockets 2817 includes the pocket 2817 (or includes a closed pocket). The distal end 303 lacks a corresponding tooth 3031 (gap 3032). Only when the location of the closed pocket is aligned with the location of the gap 3032 will the inner support structure 31 be properly received by the trench 281.

[0257] 35 illustrates advantageous packaging for a filter element 2 according to the present disclosure. The elastically deformable filter element 2 can be maintained in a deformed state within a packaging container 9, such as a (e.g., cardboard) box, bag, or sleeve. It can also be maintained in a deformed state by a retaining means (not shown) and then inserted into the packaging container 9. For example, it can be maintained in a deformed state by an elastic or inelastic rope or band prior to insertion into the packaging container 9 through the insertion opening 90. In a preferred embodiment, the packaging container 9 is sufficiently strong and adapted to deform all or only some pieces of the filter element 2 (such as any selection of the first end cap 21, the filter media pack 20, or the second end cap 22) when the filter element 2 is inserted into the packaging container 9.

[0258] Figure 36 shows the integration of a dust exhaust valve 3V on at least one undercut section 14. In this case, the undercut section 14 is positioned at the lower end of the housing inlet opening when the air filter housing is in use.

[0259] Figures 37(a) and (b) show examples of a first end cap equipped with an operating means.

[0260] FIG. 37(a) shows an embodiment in which a protruding structure 270 surrounding the central opening of the first end cap and supporting or forming a preferably inwardly oriented first radial seal 27 also includes a handle portion 271 extending radially outward from the remainder of the structure 270, the handle portion adapted to be grasped by the fingers of an adult human being.

[0261] 37(b) shows another embodiment in which the protruding structure 270 surrounding the central opening of the first end cap and supporting or forming the first, e.g., inwardly oriented, radial seal 27 further includes a radially extending flap 275 extending parallel to the outer surface of the first end cap 21, e.g., having parallel exposed surfaces 273. The flap 275 includes one or two hook portions 274 adapted to hook behind a rib or fin 14r disposed on the housing, preferably disposed on the undercut section 14, e.g., parallel to the flat portion 14F.

[0262] 42 and 43 show a filter assembly according to an eighth preferred embodiment of the present disclosure, including a main housing 1 and a housing cover 3. A possible associated filter element is shown in FIG.

[0263] The housing cover 3 includes an axial end wall 30e connected to a circumferential side wall 30 disposed about the longitudinal axis and defining a lower rim 30r' of the side wall 30 that surrounds the filter-housing interface opening. The lower rim 30r' is defined at least partially or completely by a plane that is inclined relative to a direction perpendicular to the longitudinal axis.

[0264] The axial end wall is disposed perpendicular to the longitudinal axis, and the circumferential side wall extends between a minimum width at a minimum axial distance between the lower rim 30r' and the axial end wall 30e and a maximum width at a maximum axial distance between the lower rim 30r' and the axial end wall 30e.

[0265] The housing cover sidewall 30 includes one or more housing cover sidewall openings 33 that can function as housing inlets, embodied, for example, as a grid structure 32 including flow guide vanes 34 and / or ribs.

[0266] The housing cover 3 further includes a filter media or outer support structure 35 axially projecting from the inner surface from the axial end wall 30e. The media support structure 35 includes a tower structure extending axially from a proximal end on the inner surface of the cover 3 to a distal end 351 remote from the cover 3. The media support structure 35 includes a grid structure defined by openings 352 and ribs 353. The media support structure 35 can provide media support, for example, on the exterior of the filter media pack 20.

[0267] The axial length of the housing cover 3 including the media support structure 35 is greater than the axial length of the complementary main housing 1 .

[0268] The main housing 1 includes a maintenance opening for receiving the filter element 2 into the main housing 1, an outlet 12, and a mounting means 112. The maintenance opening includes a rim 1311 located in a plane inclined relative to a direction perpendicular to the longitudinal axis of the main housing 1, corresponding to the inclined plane of the lower rim 30r' of the housing cover 3. The sidewall of the main housing 1 includes one or more housing sidewall openings 111 that can function as housing inlets, for example, embodied as a grid structure including flow guide vanes or ribs 110.

[0269] The main housing 1 further includes a media support structure or tower 113 positioned adjacent to and surrounding the filter housing outlet 12 and projecting into the interior volume of the air cleaner. The tower 113 is positioned and adapted to support the filter media pack 20 from the inside.

[0270] FIG. 44 illustrates a filter element 2 and its installation process for use with a housing 1 and a housing cover 3 according to the eighth preferred embodiment of the present disclosure.

[0271] Contrary to the configuration of the embodiments associated with Figures 12-16, 30-31, and 38-41, the second circumferential seal 28 is configured to seal in a radially inward direction, and the filter element 2 of Figure 44 is configured to seal in a radially outward direction.

[0272] The second end cap 22 of the filter element 2 includes a portion of the filter media 20 and a second circumferential seal 28 disposed about the outer periphery of the second end cap 22. The circumferential seal 28 extends radially outward from the media pack 20, forming a circumferential trench, groove, or recess 281 that projects in a direction toward the first end cap 21, preferably parallel to the outer wall of the filter media 20.

[0273] When the filter element 2 is installed in the main housing 1, the seal 28 contacts a corresponding sealing surface 19 in the main filter housing 1. When the housing cover is installed, the distal end 351 of the outer support structure 35 is received in the trench 281. The trench 281 and the distal end 351 are further configured to provide back pressure against the seal 28 thereby improving and securing the seal of the seal 28 against the sealing surface 19.

[0274] Similar refinements as described for the embodiment having a radially inward sealing direction of second circumferential seal 28 may be applied, mutatis mutandis, to trench 281 and / or distal end 351. For example, the side surfaces (here, the radially outer surfaces) of trench 281 may include sloped portions.

[0275] For example, the following can be claimed: 1. A filter element comprising: a flexible filter media pack tubularly arranged about an axis; a first open end cap fluid-tightly connected to a first axial end of the filter media pack; and a second open end cap fluid-tightly connected to a second axial end of the filter media pack, wherein the first end cap is flexible and can be non-destructively transformed, e.g., between a first shape and a different second shape. 2. The filter element of item 1, wherein the minimum radial cross-sectional dimension of the second shape of the first open end cap is at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 40%, at least 50%, or at least 75% smaller than the minimum radial cross-sectional dimension of the first shape. 3. The filter element according to item 1 or 2, wherein the first end cap is elastically deformable. 4. The filter element of any of the preceding items, wherein the first end cap is connected to the filter media and, optionally, manufactured by potting. 5. The filter element of any of the preceding items, wherein the first end cap preferably includes a first circumferential seal integrally formed with the first end cap. 6. The filter element of item 5, wherein the first circumferential seal comprises an N-fold, eg, one-fold, rotational symmetry about the filter media pack axis. 7. The filter element of item 5 or 6, wherein the first circumferential seal is disposed along a plane inclined relative to a plane perpendicular to the filter media pack axis. 8. The filter element of any of the preceding items, wherein the first end cap is capable of being radially deformed by a radial force component of less than 40 N. 9. A filter element according to any of the preceding items, wherein the first end cap further comprises at least one operating means, such as a handle, adapted and positioned radially inward or for pulling a portion of the first end cap radially inward. 10. The filter element of item 9, wherein the operating means includes a handle bar or structure bridging opposite ends of the open end cap over the central opening of the first end cap. 11. The filter element of either item 9 or 10, wherein the operating means includes at least one radially inwardly or outwardly directed flap or ear structure. 12. The filter element of any of the preceding items, wherein the filter media packs are of the conical type, i.e., arranged in a conical fashion, the cross section of each cone decreasing from a first axial end of the media pack to a second axial end of the media pack, and the second end cap having a smaller outer diameter than the first end cap. 13. The filter element of any of the preceding items, wherein the second end cap is flexible, e.g., capable of being non-destructively transformed between a first shape and a different second shape. 14. The filter element of any of the preceding items, wherein the minimum radial cross-sectional dimension of the second shape of the second open end cap is at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 40%, at least 50%, or at least 75% smaller than the minimum radial cross-sectional dimension of the first shape. 15. The filter element of any of the preceding items, wherein the second end cap is capable of being radially deformed by a radial force component of less than 40 N. 16. The filter element of any of the preceding items, wherein the second end cap is elastically deformable. 17. The filter element of any of items 1 to 15, wherein the second end cap is substantially rigid. 18. The filter element of any of the preceding items, wherein the second end cap includes a second circumferential seal, preferably integrally formed with the second end cap. 19. The filter element of item 18, wherein the second circumferential seal comprises an N-fold, e.g., a 1-fold, rotational symmetry about the filter media pack axis. 20. The filter element of item 18 or 19, wherein the second circumferential seal is disposed along a plane inclined relative to a plane perpendicular to the filter media pack axis. 21. The filter element of any of items 18-20, wherein the second open end cap includes a central opening, the second circumferential seal is embodied as a portion extending radially inward into the central opening of the second end cap, the radially inward extending portion including at least one axially extending circumferential, e.g., V- or U-shaped, groove, trench, or recess disposed adjacent to the central opening, the groove, trench, or recess preferably protruding into the interior volume of the filter media pack in a direction parallel to the axis of the filter media pack. 22. The filter element of any of the preceding items, wherein the filter media pack includes pleated media, the media including one or more layers selected from the group of media layers and support layers. 23. A filter element according to any preceding item, comprising a self-supporting (free-standing) filter media pack. 24. A package comprising a box, bag, or sleeve containing a filter element according to any of the preceding paragraphs, wherein the filter element is held in an elastically deformed configuration by the inner wall of the box, bag, or sleeve. 25. A filter assembly including a filter housing having a housing axis and a filter element according to any one of items 1 to 23, wherein the filter housing includes a filter insertion opening (or maintenance opening), the filter insertion opening being too small to allow the first end cap to be inserted into the filter housing when the first end cap is in a first shape, and being large enough to allow the first end cap to be inserted into the filter housing when the first end cap is in a second shape. 26. A filter assembly according to item 25, wherein the insertion opening includes at least one undercut section, a protrusion of the filter element along the housing axis intersects with a protrusion of the undercut section along the housing axis, and the intersection corresponds to the protruding overlap region. 27. The filter assembly of item 26, wherein the projected overlap area is greater than 1%, greater than 2%, greater than 3%, greater than 5%, or greater than 10% of the projected area of ​​the filter element along the housing axis. 28. A filter assembly according to any one of items 25 to 27, wherein the housing includes a housing cover covering the insertion opening, the housing cover being substantially complementary or having a complementary shape to the one or more undercut sections. 29. A filter assembly housing according to any one of items 25 to 28, further comprising a housing cover covering the insertion opening, wherein the housing cover and the filter housing are adapted to meet along an inclined plane, and the inclined plane is adapted so that the housing length on the side corresponding to the protruding overlap region is longer than the housing length on the opposite side of the housing. 30. The filter assembly housing of item 25 or 29, further comprising a housing cover, the housing cover preferably comprising a filter media pack inner support structure, such as a tower structure, having a conical shape, protruding from the inner surface from the proximal end toward the distal end of the cover. 31. The filter assembly of item 25 or 30, including a housing cover, the housing cover including a pressure sensor mount and, optionally, a pressure sensor. 32. The filter assembly of any of items 25-31, including a housing cover, the housing cover including a sealing surface that sealingly receives the first circumferential seal when the cover is attached to the filter housing. 33. A filter assembly according to any of items 25 to 32, wherein the filter housing includes a housing cover, the filter housing includes a first end and a second end, the first end includes a filter insertion opening and is configured to receive the filter insertion opening, the second end is disposed at an end opposite the first end and includes an outlet opening, and the second end further includes a sealing surface complementary to the second circumferential seal for sealingly receiving the second circumferential seal. 34. A filter assembly according to any of items 25 to 33, wherein the filter element is dependent on item 21, the cover is dependent on item 30, and the distal end of the support structure is positioned and adapted to be received by an axially extending circumferential, e.g., V- or U-shaped groove, trench, or recess, of the second circumferential seal of the filter element, and to provide radially outward support pressure on the circumferential seal toward the sealing surface of the filter housing when the cover is attached to the housing. 35. A filter assembly according to any of items 25 to 34, wherein the housing further includes at least one partial volume for receiving a portion of the first end cap within the housing, the partial volume preferably being positioned below, preferably immediately below or adjacent to, an undercut section in the housing adjacent the insertion opening. 36. The filter assembly according to any one of items 25 to 35, wherein the filter media packs of the filter elements are mounted (installed) in a twisted configuration. 37. A filter assembly according to any of items 25-36, wherein the housing includes a housing sidewall that is open and includes a grid structure and is positioned generally along the outer radial surface of the filter media pack. 38. A filter assembly according to any one of items 25 to 37, wherein the radial sidewall of the cover is open and includes a grid structure. 39. A filter assembly according to either item 37 or 38, wherein at least one of the grid structures includes one or more flow directing means. 40. A filter housing including an inlet and an outlet and configured to sealingly receive a replaceable filter element such that air passing from the inlet of the housing to the outlet of the housing is filtered by the filter element, the housing including a maintenance opening in a main portion of a crawler section for receiving the filter element, the housing including a housing cover for closing the maintenance opening, the housing inlet being provided in the main portion and / or the housing cover, the inlet including a grid-like inlet structure. 41. The filter housing of item 40, wherein the housing includes a housing sidewall that is positioned generally along an outer radial surface of the filter media pack when installed within the housing, and the outer radial surface includes a grid structure. 42. The filter housing according to item 40 or 41, wherein the radial sidewall of the cover includes a grid structure. 43. A filter housing according to any of items 40 to 42, wherein at least one of the grid structures of the housing sidewall or cover includes one or more flow guiding means, such as flow guiding ribs, fins, or vanes. 44. The filter housing according to any one of items 40 to 43, wherein the housing main body and / or the housing cover comprise plastic. 45. A filter housing according to any one of items 40 to 44, wherein the main part of the housing and / or the housing is formed by injection molding.

[0276] For example, the following may also be claimed: 1. A filter element comprising: a flexible filter media pack tubularly arranged about an axis; a first open end cap fluid-tightly connected to a first axial end of the filter media pack; and a second open end cap fluid-tightly connected to a second axial end of the filter media pack, the second open end cap comprising a central opening and a second circumferential seal including a portion extending radially inward into the central opening of the second end cap, the radially inward extending portion including at least one circumferential groove, trench, or recess disposed adjacent the central opening, the groove, trench, or recess projecting into an interior volume of the filter media pack. 2. The filter element according to item 1, wherein the circumferential grooves, trenches, or recesses are oriented in a direction parallel to the axis of the filter media pack. 3. A filter element according to any of the preceding items, wherein the circumferential groove, trench, or recess includes a chamfered or beveled portion. 4. A filter element according to any of the preceding items, wherein the groove, trench, or recess includes a radially inner sidewall, a radially outer sidewall connected by a bottom wall, and the second circumferential seal further includes a plurality of, preferably regularly spaced, spacing ribs bridging the radially inner and outer sidewalls. 5. The filter element of item 4, wherein the pockets are formed in the trenches between adjacent spacing ribs. 6. A filter element according to any of the preceding items, wherein the groove, trench, or recess includes a radially inner sidewall and a radially outer sidewall connected by a bottom wall, the radially outer sidewall or the radially inner sidewall including one, two, or more axially extending fluid communication channels. 7. The filter element of any of the preceding items, wherein the filter media packs are of the conical type, i.e., arranged in a conical fashion, the cross section of each cone decreasing from a first axial end of the media pack to a second axial end of the media pack, and the second end cap having a smaller outer diameter than the first end cap. 8. The filter element of any of the preceding items, wherein the second end cap is flexible, e.g., capable of being non-destructively transformed between a first shape and a different second shape. 9. The filter element of item 8, wherein the minimum radial cross-sectional dimension of the second shape of the second open end cap is at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 40%, at least 50%, or at least 75% smaller than the minimum radial cross-sectional dimension of the first shape. 10. The filter element of any of the preceding items, wherein the second end cap is capable of being radially deformed by a radial force component of less than 30 N. 11. The filter element of any of the preceding items, wherein the second end cap is elastically deformable. 12. The filter element of any of items 1 to 7, wherein the second end cap is substantially rigid. 13. The filter element of any of the preceding items, wherein the second circumferential seal is integrally formed with the second end cap. 14. The filter element of any of the preceding items, wherein the second circumferential seal comprises N folds, e.g., 1 fold rotational symmetry about the filter media pack axis. 15. The filter element according to item 14, wherein the second circumferential seal includes at least one radially projecting lobe. 16. The filter element according to item 14, wherein the second circumferential seal includes at least one axially projecting lobe. 17. The filter element of any of the preceding items, wherein the second circumferential seal is disposed along a plane that is inclined relative to a plane perpendicular to the filter media pack axis. 18. The filter element of any of the preceding items, wherein the filter media pack includes pleated media, the media including one or more layers selected from the group of media layers and support layers. 19. A filter element according to any of the preceding items, wherein the second end cap is connected to the filter media by potting, and optionally manufactured by potting. 20. A filter assembly comprising a filter housing having a housing axis and a filter element of any of items 1-19 disposed within the housing along the housing axis, wherein the filter housing includes a housing cover, the housing cover including a filter media pack inner support structure, such as a tower structure, preferably having a conical shape, protruding from an inner surface at the cover from a proximal end toward a distal end thereof, the filter housing including a first end and a second end, the first end including a filter insertion opening and configured to receive the cover, the second end disposed opposite the first end and including an outlet opening, and the second end further including a sealing surface complementary to the second circumferential seal for sealingly receiving the second circumferential seal. 21. The filter assembly of item 20, wherein the distal end of the support structure is positioned and adapted to be received by an axially extending circumferential groove, trench, or recess in the second circumferential seal of the filter element and to provide radially outward back pressure on the circumferential seal toward the sealing surface of the filter housing when the cover is attached to the housing. 22. A filter assembly according to any one of items 20 to 21, insofar as it relies on item 15, wherein the distal end of the support structure includes at least one radially protruding lobe corresponding to the at least one radially protruding lobe of the second circumferential seal. 23. A filter assembly according to any of items 20 to 22, insofar as it relies on item 16, wherein the distal end of the support structure includes at least one axially protruding lobe corresponding to the at least one axially protruding lobe of the second circumferential seal.

[0277] For example, the following may also be claimed: 1. A filter element comprising: a preferably flexible filter media pack tubularly arranged about an axis; a first open end cap fluid-tightly connected to a first axial end of the filter media pack; and a second open end cap fluid-tightly connected to a second axial end of the filter media pack, the second open end cap including a second circumferential seal, the second circumferential seal including or forming a circumferential trench, groove, or recess extending radially outward from the media pack in a direction toward the first end cap, preferably in a direction parallel to an outer wall of the filter media pack. 2. The filter element according to item 1, wherein the circumferential grooves, trenches, or recesses are oriented in a direction parallel to the axis of the filter media pack. 3. A filter element according to any of the preceding items, wherein the circumferential groove, trench, or recess includes a chamfered or beveled portion. 4. A filter element according to any of the preceding items, wherein the groove, trench, or recess includes a radially inner sidewall and a radially outer sidewall connected by a bottom wall, and wherein the second circumferential seal further includes a plurality of, preferably regularly spaced, spacing ribs bridging the radially inner and outer sidewalls. 5. The filter element of item 4, wherein the pockets are formed in the trenches between adjacent spacing ribs. 6. A filter element according to any of the preceding items, wherein the groove, trench, or recess includes a radially inner sidewall and a radially outer sidewall connected by a bottom wall, the radially outer sidewall or the radially inner sidewall including one, two, or more axially extending fluid communication channels.

[0278] For example, the following may also be claimed: 1. A housing cover for a filter housing, comprising an axial end wall connected to a circumferential side wall arranged about a longitudinal axis, wherein a projection of the axial end wall along the longitudinal axis on a plane perpendicular to the longitudinal line comprises one fold of rotational symmetry about the longitudinal axis. 2. The housing cover of item 1, including an axial end wall connected to a circumferential side wall arranged about the longitudinal axis, the cover defining a lower rim of the side wall surrounding the housing interface opening, the circumferential side wall being interrupted (or including one or more, e.g., annular, gaps) or being straight or substantially straight within one or more angular ranges about the longitudinal axis. 3. A housing cover according to item 1 or 2, wherein the contour of the axial end wall generally corresponds to one or more subsequent sections of a predetermined circular shape, connected by one or more chord lines of the circular shape between adjacent circular sections, and the circumferential side walls are interrupted or straight in the areas corresponding to the chord lines. 4. A housing cover according to any of the preceding items, further comprising a sensor port opening in the axial end wall. 5. A housing cover according to any preceding item, including an inner surface and a circumferential sealing surface disposed on the inner surface for receiving a filter element seal. 6. The housing cover according to item 5, wherein the circumferential sealing surface protrudes axially from the axial end wall on the inner surface. 7. The housing cover according to either item 5 or 6, wherein the circumferential sealing surface includes an N-fold rotational symmetry. 8. The housing cover of any of the preceding items, further comprising one or more axial end wall openings in the axial end wall. 9. A housing cover as described in paragraph 8 including one or more centrally positioned axial end wall outlet openings radially positioned within the circumferential sealing surface. 10. A housing cover according to any of the preceding items, including a second circumferential sealing surface disposed on an inner surface for receiving a second filter element seal, radially disposed within the first circumferential sealing surface, and one or more centrally positioned axial end wall inlet openings positioned radially within the second circumferential sealing surface. 11. The housing cover of item 10, wherein the second circumferential sealing surface includes an N-fold rotational symmetry. 12. A housing cover according to any of the preceding items, further comprising a filter media support structure (internal or external) projecting axially or primarily axially from the inner surface of the axial end wall. 13. The housing cover of item 12, wherein the media support structure includes a tower structure, preferably a conical tower structure, extending axially from a proximal end of the inner surface of the cover to a distal end away from the cover. 14. The housing cover according to item 13, wherein the distal end of the tower structure includes an N-fold rotational symmetry about the longitudinal axis. 15. A housing cover according to any preceding item, wherein the lower rim is defined by a plane inclined relative to a direction perpendicular to the longitudinal axis. 16. The housing cover according to item 15, wherein the axial end wall is disposed perpendicular to the longitudinal axis, and the circumferential side wall extends between a minimum width at a minimum axial distance between the lower rim and the axial end wall and a maximum width at a maximum axial distance between the lower rim and the axial end wall. 17. The housing cover of any of the preceding items, wherein the housing side wall includes one or more housing cover side wall openings. 18. The housing cover according to any of items 2 to 17, further comprising at least a subcomponent of the cover closure means or device disposed at or adjacent to a location where the circumferential sidewall is interrupted (or includes one or more gaps) or is straight or substantially straight. 19. An assembly including a main housing having a maintenance opening for receiving a filter element in the housing, and a housing cover covering the maintenance opening according to any of items 1 to 18, wherein the maintenance opening includes at least one undercut segment that is complementary to an interrupted or straight segment of the housing cover when the cover is placed on the housing.

[0279] For example, the following may also be claimed: 1. A housing cover for a filter housing, the housing cover including an axial end wall connected to a circumferential side wall disposed about a longitudinal axis and defining a lower rim of the side wall surrounding a filter housing interface opening, the lower rim being defined by a plane inclined relative to a direction perpendicular to the longitudinal axis. 2. The housing cover according to item 1, wherein the axial end wall is disposed perpendicular to the longitudinal axis and the circumferential side wall extends between a minimum width at a minimum axial distance between the lower rim and the axial end wall and a maximum width at a maximum axial distance between the lower rim and the axial end wall. 3. The housing cover of any of the preceding items, wherein the housing side wall includes one or more housing side wall openings. 4. The housing cover of any of the preceding items, further including a sensor port opening in the axial end wall. 5. The housing cover according to items 1 to 3, including an inner surface and a circumferential sealing surface disposed on the inner surface for receiving a seal of the filter element. 6. The housing cover according to item 5, wherein the circumferential sealing surface protrudes axially from the axial end wall on the inner surface. 7. The housing cover according to either item 5 or 6, wherein the circumferential sealing surface includes an N-fold rotational symmetry. 8. The housing cover of any of the preceding items, further comprising one or more axial end wall openings in the axial end wall. 9. The housing cover of item 8, including one or more centrally positioned axial end wall outlet openings radially positioned within the circumferential sealing surface. 10. The housing cover of any of items 1-8, including a second circumferential sealing surface disposed radially within the first circumferential sealing surface and disposed on an inner surface thereof for receiving a second filter element seal, and one or more centrally positioned axial end wall inlet openings positioned radially within the second circumferential sealing surface. 11. The housing cover of item 10, wherein the second circumferential sealing surface includes an N-fold rotational symmetry. 12. The housing cover of any of the preceding items, further comprising a filter media support structure (inner or outer) projecting axially from the inner surface of the axial end wall. 13. The housing cover of item 12, wherein the media support structure includes a tower structure, preferably a conical tower structure, extending axially from a proximal end of the inner surface of the cover to a distal end away from the cover. 14. The housing cover of item 13, wherein the distal end of the tower structure includes an N-fold rotational symmetry about the longitudinal axis. 15. A housing cover according to any of the preceding items, wherein the circumferential side wall is interrupted within one or more angular ranges about the longitudinal axis (or includes one or more annular gaps), or is straight. 16. A housing cover according to item 15, wherein the contour of the axial end wall generally corresponds to one or more subsequent sections of a predetermined circular shape connected by one or more chord lines of the circular shape between adjacent circular sections, and the circumferential side walls are interrupted or straight in areas corresponding to the chord lines (defining one or more flat portions of the housing cover). 17. An assembly including a main housing having a maintenance opening for receiving a filter element into the main housing, and a housing cover covering the maintenance opening described in any of the preceding items, wherein the maintenance opening includes a rim that lies in a plane that is inclined relative to a direction perpendicular to the longitudinal axis of the housing cover, corresponding to the inclined plane of the lower rim of the housing cover. [Explanation of symbols]

[0280] 1 Main filter housing or first housing part 2 Filter Elements 3 Housing cover or second housing part 3F,3F' flat part 3V Dust Exhaust Valve 4. Further Elements 5 Sensor Port 6 Second Main Filter Element 9 Packaging container 11 Housing side wall 12,12' outlet pipe or housing outlet 13 Filter insertion or maintenance opening 14,14' Undercut Section 14 * , 14 *’ Virtual complement 14F flat area 14r Rib or Fin 15 first housing end 16 Second housing end 17 Entrance 18 Lock Configuration 19 Sealing surface 19r Radially inward projecting lobe 19s Lobes projecting inward in the axial direction 20 filter media packs 21 First end cap 22 Second end cap 25 first axial end 26 second axial end 27 First circumferential seal 28 Second circumferential seal 28s Radially inward projecting lobes 28s Axially inward projecting lobes 30 Circumferential sidewall 30e Axial end wall 30r, 30r' Lower rim on circumferential sidewall 31 Inner support or tower structure 32 Rib or grid structure 33 Opening in the circumferential side wall of the cover 33t Opening in the housing cover 34 Flow Guidance Means 35 External support structure 37,37' sealing surface 50 Pressure Sensor 60 filter media 67 Second circumferential seal face 90 Insertion opening 110 Flow guide blades or fins 111 Openings separated by flow guide blades 112 Mounting means 113 Supporting structure or tower 121 Exit opening 131 Subvolume of the internal volume of the filter housing 141 Alignment Configuration 270 Protruding configuration 271 Handle structure 273 Exposed surface of radially extending flap 274 Hook part 275 Radially extending flaps 281 Circumferential grooves, trenches or recesses 300 Top or outer surface of housing cover 301 Inside of housing cover 302 Closing means or devices such as latches 303 Distal end of inner support structure 303r Radially inward projecting lobes 303s Axially projecting lobes 333 Locking mechanism 351 distal end of outer support structure 352 Openings in outer support structures 353 Ribs / Grids of Outer Support Structure 1311 Sloped housing rim 2811 Axially extending fluid communication channel 2812 Radially outer sidewall of 281 2813 Radially inner sidewall of 281 2814 2813 Sloped or chamfered parts 2815 Bottom wall of 281 2816 Spacing Rib 2817,1817' Pocket 2818 Closed Seal Compartment 2819 Axial extension 3031, 3031' Axially extending segments or teeth at distal end 3032 Distal end gap L Housing length O3A Cover entrance opening O3AW Feather or wapple configuration O3B Axial end wall outlet opening P1 plane P2 Second plane S inclined plane

Claims

1. a flexible filter media pack disposed annularly about an axis; a first open end cap fluid-tightly connected to a first axial end of the filter media pack; a second open end cap fluid-tightly connected to a second axial end of the filter media pack; the first end cap is flexible and capable of being non-destructively transformed between a first shape and a different second shape; Filter element.

2. 10. The filter element of claim 1, wherein the minimum radial cross-sectional dimension of the second shape of the first open end cap is at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 40%, at least 50%, or at least 75% smaller than the minimum radial cross-sectional dimension of the first shape.

3. The filter element of claim 1 or 2, wherein the first end cap is elastically deformable.

4. The filter element of any one of claims 1 to 3, wherein the first end cap is connected to the filter media pack and is optionally manufactured by potting.

5. A filter element according to any preceding claim, wherein the first end cap includes a first circumferential seal, preferably integrally formed with the first end cap.

6. The filter element of claim 5 , wherein the first circumferential seal comprises an N-fold (or one-fold) rotational symmetry about the filter media pack axis.

7. 7. The filter element of claim 5 or 6, wherein the first circumferential seal is disposed along a plane that is inclined relative to a plane perpendicular to the filter media pack axis.

8. The filter element of any one of claims 1 to 7, wherein the first end cap can be radially deformed with a radial force component of less than 40N.

9. 9. The filter element of claim 1, wherein the first end cap further comprises at least one manipulation means, such as a handle, adapted and positioned radially inward or for pulling a portion of the first end cap radially inward.

10. 10. The filter element of claim 9, wherein the manipulation means comprises a handle bar or structure bridging opposite sides of the open end cap over a central opening in the first end cap.

11. 11. The filter element of claim 9 or 10, wherein the manipulation means comprises at least one radially inwardly or outwardly oriented flap or ear structure.

12. 12. The filter element of claim 1, wherein the filter media packs are conical (or arranged in a conical manner), each cone having a cross section that decreases from the first axial end of the media pack to the second axial end of the media pack, and the second end cap has a smaller outer diameter than the first end cap.

13. 13. The filter element of claim 1, wherein the second end cap is flexible and capable of being non-destructively transformed between a first shape and a different second shape.

14. 14. The filter element of claim 1, wherein the second shape of the second open end cap has a minimum radial cross-sectional dimension that is at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 40%, at least 50%, or at least 75% smaller than the minimum radial cross-sectional dimension of the first shape.

15. A filter element according to any preceding claim, wherein the second end cap can be radially deformed by a radial force component of less than 40N.

16. The filter element of any one of claims 1 to 15, wherein the second end cap is elastically deformable.

17. The filter element of any one of claims 1 to 15, wherein the second end cap is substantially rigid.

18. A filter element according to any preceding claim, wherein the second end cap includes a second circumferential seal, preferably integrally formed with the second end cap.

19. 20. The filter element of claim 18, wherein the second circumferential seal comprises an N-fold (or one-fold) rotational symmetry about the filter media axis.

20. 20. The filter element of claim 18 or 19, wherein the second circumferential seal is disposed along a plane that is inclined relative to a plane perpendicular to the filter media pack axis.

21. 21. The filter element of claim 18, wherein the second open end cap includes a central opening, the second circumferential seal is embodied as a radially inwardly extending portion within the central opening of the second end cap, the radially inwardly extending portion including at least one axially extending circumferential V- or U-shaped groove, trench, or recess disposed adjacent the central opening, the groove, trench, or recess preferably projecting into an interior volume of the filter media pack in a direction parallel to an axis of the filter media pack.

22. 22. The filter element of any one of claims 1 to 21, wherein the filter media pack comprises pleated media, the pleated media comprising one or more layers selected from the group of a media layer and a support layer.

23. The filter element of any one of claims 1 to 22, comprising a self-supporting filter media pack.

24. A package comprising a box, bag or sleeve containing a filter element according to any one of claims 1 to 23, the filter element is maintained in a resiliently deformed configuration by an inner sidewall of the box, bag, or sleeve; package.

25. A filter assembly comprising a filter housing having a housing axis and a filter element according to any one of claims 1 to 23, the filter housing includes a filter insertion opening (or maintenance opening), the filter insertion opening being too small to insert the first end cap into the filter housing in the first shape of the first end cap, and being large enough to insert the first end cap into the filter housing in the second shape of the first end cap; Filter assembly.

26. 26. The filter assembly of claim 25, wherein the insertion opening includes at least one undercut section, a protrusion of the filter element along the housing axis intersects a protrusion of the undercut section along the housing axis, the intersection corresponding to a protruding overlap region.

27. 27. The filter assembly of claim 26, wherein the protruding overlap area is greater than 1%, greater than 2%, greater than 3%, greater than 5%, or greater than 10% of the protruding area of ​​the filter element along the housing axis.

28. 28. The filter assembly of claim 25, wherein the housing includes a housing cover that covers the insertion opening, the housing cover being substantially complementary or complementarily shaped to the at least one undercut section.

29. 29. The filter assembly of claim 25, further comprising a housing cover covering the insertion opening, wherein the housing cover and the filter housing are adapted to meet along an inclined plane, and the inclined plane is configured such that a housing length of the housing on a side corresponding to the protruding overlap region is longer than a housing length on an opposite side of the housing.

30. 30. The filter assembly of any one of claims 25 to 29, further comprising a housing cover, the housing cover including a filter media pack inner support structure, such as a tower structure, preferably having a conical shape, protruding from an inner surface from a proximal end toward a distal end of the cover.

31. A filter assembly according to any one of claims 25 to 30, comprising a housing cover, said housing cover including a pressure sensor mount and optionally a pressure sensor.

32. 32. The filter assembly of any one of claims 25 to 31, including a housing cover, the housing cover including a sealing surface that sealingly receives the first circumferential seal when the cover is attached to the filter housing.

33. 33. The filter assembly of claim 25, wherein the filter housing includes a housing cover, the filter housing including a first end and a second end, the first end including the filter insertion opening and adapted to receive the cover, the second end disposed opposite the first end and including an outlet opening, and the second end further including a sealing surface complementary to the second circumferential seal for sealingly receiving the second circumferential seal.

34. 34. The filter assembly of claim 25, wherein the filter element is dependent on claim 21 and the cover is dependent on claim 30, and wherein the distal end of the support structure is positioned and adapted to be received by the axially extending circumferential V- or U-shaped groove, trench, or recess of the second circumferential seal of the filter element and to provide a radially outward back pressure on the circumferential seal against the sealing surface of the filter housing when the cover is attached to the housing.

35. 35. The filter assembly of claim 25, wherein the housing further includes at least one partial volume for receiving a portion of the first end cap within the housing, the partial volume preferably being located in the housing adjacent to the insertion opening and below the undercut section, preferably being located immediately below or adjacent to the undercut section.

36. The filter assembly of any one of claims 25 to 35, wherein the filter media packs of the filter element are mounted in a twisted configuration.

37. 37. The filter assembly of any one of claims 25 to 36, wherein the housing includes a housing sidewall that is open and includes a grid structure and that is positioned generally along an outer radial surface of the filter media pack.

38. A filter assembly according to any one of claims 25 to 37, wherein the radial sidewall of the cover is open and includes a grid structure.

39. 39. A filter assembly according to claim 37 or 38, wherein at least one of the grid structures includes one or more flow directing means.

40. Including entrances and exits, A filter housing, the housing is adapted to sealingly receive a replaceable filter element such that air passing from an inlet of the housing to an outlet of the housing is filtered by the filter element; the housing includes a maintenance opening for receiving the filter element within a main portion of the housing, the housing including a housing cover for closing the maintenance opening; The inlet of the housing is provided in the main part and / or the housing cover, and the inlet includes a grid-like inlet structure. Filter housing.

41. 41. The filter housing of claim 40, wherein the housing includes a housing sidewall that is positioned generally along an outer radial surface of the filter element when installed within the housing, the outer radial surface including a grid structure.

42. 42. The filter housing of claim 40 or 41, wherein the radial sidewall of the cover includes a grid structure.

43. 43. A filter housing according to any one of claims 40 to 42, wherein at least one of the grid structures of the housing sidewall or the cover includes one or more flow guiding means, such as flow guiding ribs, fins or vanes.

44. A filter housing according to any one of claims 40 to 43, wherein the housing main body and / or housing cover comprise plastic.

45. A filter housing according to any one of claims 40 to 44, wherein the main housing part and / or the housing is formed by injection moulding.

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