Filter housing cover and associated filter assembly

Abstract

The present disclosure relates to 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 edge of the side wall surrounding a filter housing interface opening, the lower edge being defined by a plane inclined relative to a direction perpendicular to the longitudinal axis, and an associated filter assembly.

Description

[Technical Field]

[0001] [Related Applications] This application claims priority to European Patent Application No. 23156667.0, filed February 14, 2023, filed as a PCT international application on February 14, 2024, the disclosure of which is incorporated herein by reference in its entirety.

[0002] The present disclosure relates to the field of gas filtration, such as air filtration. The present disclosure relates to a filter assembly including a filter element disposed in a sealing manner within a filter housing such that air passing through the filter element from an inlet 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 in a wide variety of filtering applications, and the fluid being filtered can be a liquid or a gas, such as air.

[0004] Indeed, it is often desirable to filter contaminants from fluid streams. For example, airflow to engines for motor vehicles or power generation equipment, construction equipment, or other devices, gas flows to gas turbine systems, and airflow to various combustion furnaces retain particulate contaminants therein. For such systems, it is preferable to remove or at least reduce contaminants 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 include pleated media and grooved media. When the filter medium is loaded with dust and / or particles above a certain threshold load, the filter element must be replaced. The filter element is typically attached to the housing in a replaceable manner.

[0006] There is a need in the industry for new solutions that allow for the correct and easy installation of filter elements and prevent the installation of incorrect filter elements, particularly in filter housings with complex filter housing designs that may be the result of boundary conditions imposed by, for example, the shape and placement of other vehicle / engine components.

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

[0008] There is a need in the industry for filter elements that have an increased ratio of filter media volume to internal housing volume.

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

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

[0011] In general, it is important to install the correct filter element in the correct manner for a particular filter housing to avoid damage to the equipment or engine that utilizes the filtered air / gas.

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

[0013] There is also a need in the industry for a filter assembly that allows for inspection of an installed filter element with a low risk of breaking the seal of the filter element to the main housing. Summary of the Invention

[0014] An embodiment of the present disclosure aims to provide a filter housing cover as set forth in claim 1 and a filter housing assembly including such a housing cover.

[0015] The invention is defined in the accompanying independent claims, the dependent claims defining 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 around 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, for example, capable of non-destructively transforming between a first shape (or state) (corresponding to a first configuration of the filter element) and a different, preferably substantially different, second shape (or state) (corresponding to a second configuration of the filter element).

[0017] The filter housing can be designed to allow installation of the disclosed filter elements but not standard filter elements, advantageously avoiding the use or incorrect installation of the incorrect filter element. The disclosed filter elements have the further advantage of being able to be used in relatively complex and compact housing configurations. Furthermore, the disclosed filter elements can be packaged in a more compact manner. At least the first end cap and filter media can be non-destructively deformed, allowing the filter media to be configured in a twisted manner during use within the associated housing, increasing the ratio of filter media volume to housing interior volume.

[0018] For purposes of this disclosure, a filter element, end cap, or filter media pack can be non-destructively deformed if deformation of the respective item does not affect its integrity or performance. Preferably, each item is flexible, and more preferably, each item is elastically deformable within the boundaries necessary to perform its function, such as reducing its size to fit into a filter housing service opening that is initially too small, or to shape itself to conform to a filter housing cavity of sufficient volume but different shape. An item is elastically deformable if it returns to its original, undeformed state after being deformed, within the boundaries of performing 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 filter media pack can include, for example, a pleated filter media pack. The sheet material pleated to form the pleated media can be single-layered or multi-layered. For example, it can include one, two, or more filtration and / or coalescing layers. It can further include inner and / or outer support layers. The composite and pleated media should be non-destructively deformable. It is preferably flexible. It is preferably elastically deformable. The pleated media, at least in the first configuration of the filter element, is preferably arranged in a tubular shape with the pleat direction parallel to the longitudinal axis of the filter element. The end pleats of the pleated media are preferably permanently connected to each other by adhesive (e.g., polyurethane) embedding or other modern techniques, preferably without loss of filtration capacity beyond a single pleat length. The end pleats are the first and last pleats of the pleated paper. Preferably, there are no axially extending intermediate connecting structures in each of the end pleats to connect the end pleats.

[0020] According to certain embodiments, the portion of the filter element that is non-destructively deformable is continuously deformable, e.g., without a hinge-type mechanism. According to certain embodiments, the entire filter element can be continuously non-destructively deformable. According to certain embodiments, the entire filter element is elastically deformable.

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

[0022] According to certain embodiments, the first end cap comprises or consists of a flexible material. According to certain embodiments, the second end cap comprises or consists of a flexible material. According to certain embodiments, both the first end cap and the second end cap comprise or consist 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%, or at least 10%, or at least 15%, or at least 20%, or at least 25%, or at least 30%, or at least 40%, or 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, or at least 10 mm, or at least 15 mm, or at least 20 mm, or 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%, or at least 10%, or at least 15%, or at least 20%, or at least 25%, or at least 30%, or at least 40%, or 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, or at least 10 mm, or at least 15 mm, or at least 20 mm, or 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] Such end caps have the advantage that 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 cleaner housing or packaging means, they automatically return to their original state, resulting in the corresponding first configuration of the filter element. In these cases, the first state of the end cap and the first configuration of the filter element are the end cap or filter element in their undeformed state, i.e., the state in which they would return without any external force being applied.

[0029] According to a preferred embodiment, the first configuration of the filter media pack can have a cross section along a plane perpendicular to the filter element that is circular, rectangular, rounded rectangular, oval, elliptical, or other regularly shaped.

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

[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 of 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 elastomer) 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 forms a periphery or periphery of 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 an airtight seal. The orientation of such a circumferential seal or circumferential sealing surface may be generally radially inward, radially outward, or axially, or a combination thereof. The seal between the circumferential seal and the circumferential sealing surface may be generally 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 N-fold, e.g., 1-fold, rotational symmetry about the axis of the filter media pack. Introducing N-fold rotational symmetry in the first circumferential seal and the corresponding sealing surface on the housing cover has the advantage of helping to align the filter element relative to the cover.

[0035] For the purposes of this disclosure, an object or protrusion is said to have N-fold rotational symmetry about an axis of rotation if the object or protrusion can be mapped onto itself by N different rotations of 360° or less about that axis of rotation. An object or protrusion with 1-fold rotational symmetry is an object that has 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 axis of the filter media pack.

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

[0039] According to a preferred embodiment, the operating means includes a handle bar or structure bridging the two sides of the open end cap over the central opening of 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 either side, e.g., diametrically opposite sides, of the central opening.

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

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

[0043] Preferably, the outer diameter of the second end cap can be more than 5%, 10%, 15%, 20%, 25%, or 30% smaller than the outer diameter of the first end cap. 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, non-destructively deformable between a first shape and a second, preferably substantially different, 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%, or at least 10%, or at least 15%, or at least 20%, or at least 25%, or at least 30%, or at least 40%, or 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, or at least 10 mm, or at least 15 mm, or at least 20 mm, or 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%, or at least 10%, or at least 15%, or at least 20%, or at least 25%, or at least 30%, or at least 40%, or 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, or at least 10 mm, or at least 15 mm, or at least 20 mm, or 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 40N, or less than 30N, or less than 20N, or less than 10N.

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

[0051] Such end caps have the advantage that after the end caps and filter element are deformed, for example to insert or remove the filter element through a small insertion opening in the air cleaner housing or packaging means, they automatically return to their original state, resulting in the corresponding first configuration of the filter element. This is even more advantageous when combined with an elastically deformable first end cap. In these cases, the first state of the second end cap and the first configuration of the filter element are the end caps or filter elements in their undeformed state, i.e., the state in which they return without any external force being applied.

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

[0053] According to an alternative preferred embodiment, the second end cap is substantially rigid and preferably smaller than said 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 may be formed of a polyurethane material, and may include, for example, the same material as the material of the second end cap.

[0055] Alternatively, the seal is manufactured separately or in a separate step in the manufacturing process and sealingly attached to the second end cap by state-of-the-art techniques. An alternative embodiment of the second seal is a TPE (thermoplastic elastomer) seal.

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

[0057] According to a preferred embodiment, the second circumferential seal comprises an N-fold, e.g., 1-fold, rotational symmetry about the axis of the filter media pack. Introducing an N-fold rotational symmetry in the second circumferential seal and the corresponding sealing surface on the housing has the advantage that it helps 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 axis of the filter media pack.

[0059] According to a preferred embodiment, the second open end cap includes a central opening, and the second circumferential seal is implemented radially inward within the central opening extension of the second end cap. The radially inward extension includes at least one axially extending circumferential, e.g., V- or U-shaped, groove, trench, or recess disposed adjacent to the central opening, and preferably the groove, trench, or recess projects into the inner 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 a 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 the filter element are self-supporting. According to a preferred embodiment, the filter media pack is self-supporting at least in the axial direction.

[0062] According to an alternative embodiment, the filter media pack and filter element are not self-supporting. For example, while positioned vertically on the first end cap, the filter media pack and filter element may deform under their 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 containing a filter element according to any of the embodiments of the first aspect, wherein the filter element is maintained in an elastically deformed configuration by an inner wall 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 embodiment of the first aspect, wherein the filter housing includes a filter insertion opening (often referred to as a service opening), the filter insertion opening being too small to allow insertion of a first end cap (or a first configuration of the filter element) in a first shape into the filter housing and being large enough to allow insertion of a first end cap (or a second configuration of the filter element) in a second shape into the filter housing.

[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 with a protrusion of the undercut section along the housing axis, the intersection corresponding to a protrusion overlap region. The protrusion may, for example, lie on a plane perpendicular to the housing axis.

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

[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 that covers the insertion opening, the housing cover and the filter housing adapted to meet along an inclined surface, and the inclined surface adapted so that the housing length on the side corresponding to the protrusion overlap region 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 that covers the insertion opening, the housing cover preferably having a conical shape and including a filter media pack inner support structure, such as a tower structure, that protrudes from the inner surface from the proximal end toward the 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 sensors, such as MAF sensors, temperature sensors, pressure sensors, RFID sensors or tags, and optionally sensor mounts for the respective sensors. The central area of ​​the filter housing volume below the housing cover being part of the clean air side of the filter housing is advantageous in that it allows the sensors to be located on the housing cover and within visual line of sight during service.

[0071] According to a preferred embodiment, the filter assembly includes a housing cover covering the insertion opening, the housing cover including a sealing surface that sealingly receives 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 at an end 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.

[0073] According to a preferred embodiment, the filter assembly includes a housing cover covering the insertion opening. The second open end cap of the filter element includes a central opening, and a second circumferential seal is embodied radially inward within the central opening extension of the second end cap. The radially inward extension includes at least one axially extending circumferential groove, e.g., a V- or U-shaped groove, trench, or recess, located adjacent to the central opening. The groove, trench, or recess protrudes into the interior volume of the filter media pack, preferably in a direction parallel to the axis of the filter media pack. The housing cover preferably has a conical shape and includes a filter media pack inner support structure, such as a tower structure, protruding from the inner surface from the proximal end to the distal end of the cover. The distal end of the support structure is received by the axially extending circumferential groove, e.g., a V- or U-shaped groove, trench, or recess of the second circumferential seal of the filter element, and is preferably positioned and adapted to provide radially inward back pressure on the circumferential seal toward 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 comprises at least one partial volume for receiving a portion of the first end cap within the housing, the partial volume being arranged below, preferably directly below or adjacent to, an undercut location in the housing, preferably adjacent the insertion opening.

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

[0077] A deformable filter element can have a maximum length greater than the height of the installation cavity in the housing, and by twisting the media, the length of the filter element can be reduced to fit the housing, thereby providing the advantage of 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 the 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 on the cover or housing side wall includes one or more air flow guiding means, such as air flow guiding ribs, fins or vanes.

[0081] Airflow guides, such as ribs, fins, or vanes, can be advantageously arranged in a predetermined configuration to provide optimal flow direction, for example, depending on the pleat position of the filter media pack or the expected media dust load. Airflow distribution per pleat is crucial for good filtration performance and optimal use of pleated filter media. In prior art devices, dust can settle in one part of the element, causing uneven loading, resulting in higher media restriction and suboptimal use. By controlling the position, spacing, and / or angle of the ribs / fins / vanes, or any combination thereof, 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 sound-damping purposes or straighten the flow, 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 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 includes a service opening in a main portion of the housing for receiving the filter element, the housing includes a housing cover for closing the service opening, the housing inlet is provided in the main portion and / or the housing cover, and the inlet includes a lattice-like inlet structure.

[0083] According to a preferred embodiment, 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, 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 on the cover or housing side wall includes one or more air flow guiding means such as air flow guiding ribs or vanes, with the advantages being similar to those described for the air flow guiding means on the main housing.

[0086] According to a preferred embodiment, the housing main body and / or the housing cover comprise plastic.

[0087] According to a preferred embodiment, the housing body and / or the housing are formed by injection molding.

[0088] In a fifth aspect of the present disclosure, a filter element is disclosed, the filter element including a flexible filter media pack tubularly arranged around 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 second circumferential seal radially inwardly within a central opening extension of the second end cap, the radially inward extension including at least one circumferential groove, trench, or recess disposed adjacent to the central opening, the groove, trench, or recess projecting into an internal 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 cone-shaped, i.e., arranged in a cone shape, with the cross section of each cone decreasing from a first axial end of the filter media pack to a second axial end of the filter media pack, and the second end cap having a smaller outer 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%, or at least 10%, or at least 15%, or at least 20%, or at least 25%, or at least 30%, or at least 40%, or 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, or at least 10 mm, or at least 15 mm, or at least 20 mm, or 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 a preferred embodiment, the second end cap can be radially deformed by a radial force component less than 40N, or less than 30N, or 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 axis of the filter media pack.

[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 axis of the filter media pack.

[0102] According to a preferred embodiment, the filter media pack comprises a 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 medium by potting and is optionally manufactured by potting.

[0104] In a sixth aspect of the present disclosure, a filter assembly is disclosed, the filter assembly including: a filter housing having a housing axis; and a filter element according to any one of the fifth aspects, 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 to a distal end thereof; 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 at an end 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 when the cover is attached to the housing, and to provide radially outward back pressure on the circumferential seal toward the sealing surface of the filter 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, the housing cover including an axial end wall connected to a circumferential side wall arranged about a longitudinal axis, and a protrusion of the axial end wall (or a profile thereof) along the longitudinal axis on a plane perpendicular thereto includes one-fold rotational symmetry about the longitudinal axis.

[0109] According to a preferred embodiment, the projection is generally rotationally symmetric, eg circular, but is made rotationally asymmetric by one, two or more flat or arcuate portions arranged as cutting chord lines.

[0110] According to a preferred embodiment, the sidewall includes or defines a lower edge surrounding the housing interface opening, and the circumferential sidewall is interrupted (or includes one or more annular gaps) within one or more angular ranges about the longitudinal axis, and is straight or substantially straight (in other figures, 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, the one or more subsequent sections being connected by one or more chord lines of a circular shape between the circular sections, and the circumferential side wall being 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, a circumferential sealing surface projects axially from the axial end wall on said inner surface.

[0115] According to a preferred embodiment, the circumferential sealing face includes 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, axial end wall outlet openings radially disposed within the circumferential sealing surface.

[0118] According to a preferred embodiment, the housing cover includes 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, e.g., centrally located, axial end wall inlet openings located radially within the second circumferential sealing surface.

[0119] According to a preferred embodiment, the second circumferential sealing face 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 filter media support structure comprises a tower structure, preferably a conical tower structure, extending axially from a proximal end on the inner surface of the cover to a distal end remote from the cover. The tower can be manufactured separately from the cover and later 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 has N-fold rotational symmetry about the longitudinal axis.

[0123] According to a preferred embodiment, the lower edge 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 is applied to the cover (e.g., by hand or by manipulation with 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 extends from a minimum width at a minimum axial distance between the lower edge and the axial end wall to a maximum width at a maximum axial distance between the lower edge 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 comprises at least one subcomponent of a cover closure means or device disposed in or adjacent to a position where said circumferential side wall is interrupted (or includes one or more gaps), straight, or substantially straight. Examples of such closure means or devices are, for example, latch and hook structures, finger locks, rubber bands, clips, bolts and nuts, wing nuts, etc. Preferably, the subcomponent interacts with a counterpart on the housing, for example, preferably a counterpart disposed on or adjacent to an undercut section of the housing entrance opening.

[0127] In an eighth aspect of the present disclosure, a filter assembly is disclosed, the filter assembly including: a main housing having a service opening for receiving a filter element within the housing; and a housing cover according to any of the seventh aspects for covering the service opening, the service opening including at least one or more undercut sections 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, including an axial end wall connected to a circumferential side wall arranged about a longitudinal axis and defining a lower edge of the side wall surrounding a filter housing interface opening, the lower edge 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 from a minimum width at a minimum axial distance between the lower edge and the axial end wall to a maximum width at a maximum axial distance between the lower edge 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 on the inner surface.

[0134] According to a preferred embodiment, the circumferential sealing face includes 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 located radially within the circumferential sealing surface.

[0137] According to a preferred embodiment, the housing cover further 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 located, axial end wall inlet openings located radially within the second circumferential sealing surface.

[0138] According to a preferred embodiment, the second circumferential sealing face 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 filter media support structure includes a tower structure, preferably a conical tower structure, extending axially from a proximal end on the inner surface of the cover to a distal end remote 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 discontinuous (or includes one or more annular gaps) or 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 predetermined circular shape, the one or more subsequent sections being connected by one or more chord lines of a 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).

[0144] In a tenth aspect of the present disclosure, an assembly is disclosed, the assembly including: a main housing including a service opening for receiving a filter element within the main housing; and a housing cover according to any embodiment of the ninth aspect for covering the service opening, wherein the service opening includes an edge that lies in a plane that is inclined relative to a direction perpendicular to a longitudinal axis of the housing cover, corresponding to the inclined surface of the lower edge of the housing cover.

[0145] Any of the embodiments and features of embodiments described with respect to any of the above aspects are meant to be disclosed mutatis mutandis with respect to any of the other aspects, for example, any feature described with respect to the filter element, assembly, packaging, or housing cover itself is meant to be disclosed with respect to the other aspects.

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

[0147] It may be advantageous to place at least one undercut section on the filter service opening or the bottom or underside of the filter housing when the assembly is installed / in use. Such an undercut section prevents dust that may have accumulated inside the air purifier housing from being drawn out by the filter element / media pack being lifted over the undercut section and sliding along the lower inner wall of the filter housing when it is removed. The presence of an undercut section on the filter service opening or the bottom or underside of the filter housing when the assembly is installed / in use also has the advantage that the undercut section can contain liquid used to clean the inner walls of the housing. The undercut section on the filter service opening or the bottom or underside of the filter housing may also advantageously include a dust exhaust opening or a dust exhaust valve.

[0148] For example, if there is a single undercut section, it may also be advantageous for the undercut section to be in the filter service opening or the top surface of the filter housing when the assembly is installed / in use. 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 element in place and block downward tilting movement of the filter element within the housing that could break the housing seal at the second end of the filter element.

[0149] Whether there is only one undercut section or multiple undercut sections, the presence of the undercut sections always has the advantage of holding the filter element in place, i.e. blocking axial movement of the filter element within the housing along the housing axis. [Brief explanation of the drawings]

[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: [Figure 1] FIG. 1 shows a schematic diagram of a first preferred embodiment of the present disclosure. [Figure 2] FIG. 2 shows a schematic diagram of a first preferred embodiment of the present disclosure. [Figure 3] FIG. 3 shows a schematic diagram of a first preferred embodiment of the present disclosure. [Figure 4] FIG. 4 shows a second preferred embodiment of the present disclosure. [Figure 5] FIG. 5 shows a second preferred embodiment of the present disclosure. [Figure 6] FIG. 6 shows a second preferred embodiment of the present disclosure. [Figure 7] FIG. 7 shows a variation of the second preferred embodiment. [Figure 8]8(a)-(c) show a third preferred embodiment of the present disclosure having open housing sidewalls and a sloped housing / cover interface. The described concepts are not limited to assemblies including the disclosed filter elements having flexible and / or resilient characteristics, but are more generally applicable. [Figure 9] FIG. 9 shows the flexible first end cap concept. [Figure 10] 10(a) and (b) show a modification of the third preferred embodiment shown in FIG. [Figure 11] 11(a)-(c) show a modification of the third preferred embodiment shown in FIG. [Figure 12] FIG. 14 illustrates a fourth preferred embodiment of the present disclosure. [Figure 13] FIG. 13 illustrates a fourth preferred embodiment of the present disclosure. [Figure 14] FIG. 14 illustrates a fourth preferred embodiment of the present disclosure. [Figure 15] FIG. 15 shows a variation of the fourth preferred embodiment that may be used in combination with, but is not limited to, embodiments that include a media pack support structure that protrudes from the inner surface of the housing cover. [Figure 16] FIG. 16 shows a variation of the fourth preferred embodiment that may be used in combination with, but is not limited to, embodiments that include a media pack support structure that protrudes from the inner surface of the housing cover. [Figure 17] 17(a) to (c) show a fifth embodiment of the present disclosure that does not have a medium support means protruding from the inner surface of the housing cover. [Figure 18] 18(a) and (b) show features of a housing cover for use with any of the embodiments of the present disclosure. [Figure 19] 19(a) and (b) show features of a housing cover for use with any of the embodiments of the present disclosure. [Figure 20] 20(a) and (b) show features of a housing cover for use with any of the embodiments of the present disclosure. [Figure 21]Figures 21(a)-(c) show some examples of first and second circumferential seal configurations and associated sealing surfaces on the housing cover and housing. [Figure 22] Figures 22(a)-(c) show some examples of first and second circumferential seal configurations and associated sealing surfaces on the housing cover and housing. [Figure 23] Figures 23(a)-(c) show some examples of first and second circumferential seal configurations and associated sealing surfaces on the housing cover and housing. [Figure 24] FIG. 24 shows some examples of first and second circumferential seal configurations and associated sealing surfaces on the housing cover and housing. [Figure 25] 25(a) and (b) show an example of a housing cover locking mechanism for use with embodiments of the present disclosure. [Figure 26] 26(a)-(c) illustrate 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 / media pack. [Figure 27] 27(a) to 27(c) show aspects of elastic deformation of a filter element end cap according to an embodiment of the present disclosure. [Figure 28] 28(a) and (b) show a further preferred embodiment of the present disclosure in which the filter media pack is modified with a media support structure protruding from the housing cover. [Figure 29(a)] FIG. 29(a) shows a sixth preferred embodiment of the present disclosure, which includes first and second main filter elements, the second filter element being not a safety filter element but filtering the unfiltered airflow in parallel with the first filter element. [Figure 29(b)] FIG. 29(b) shows the seventh preferred embodiment of the present disclosure. [Figure 30]FIG. 30 illustrates 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 the unfiltered airflow in parallel with the first filter element. [Figure 31] 31(a) and (b) show a modification of the sixth preferred embodiment of the present disclosure. [Figure 32] FIG. 32 shows a modification of the sixth preferred embodiment of the present disclosure. [Figure 33] FIG. 33 shows a variation of the seventh preferred embodiment. [Figure 34] 34(a) to (c) show a modified example of the seventh preferred embodiment of the present disclosure. [Figure 35] 35(a) and (b) illustrate advantageous packaging associated with the filter elements associated with the present disclosure. [Figure 36] Figure 36 shows the integration of a dust exhaust valve on the undercut section. [Figure 37] Figures 37(a) and (b) show examples of a first end cap equipped with an operating means. [Figure 38(a)] FIG. 38(a) illustrates a problem that can occur when the distal end of the support structure is received by the trench in the circumferential seal. [Figure 38(b)] FIG. 38(b) shows a further preferred embodiment for the configuration of the distal end of the second circumferential seal and inner support structure. [Figure 39] FIG. 39 shows a further preferred embodiment for the configuration of the distal end of the second circumferential seal and inner support structure. [Figure 40] 40(a) and (b) show a further preferred embodiment for the configuration of the distal end of the second circumferential seal and inner support structure. [Figure 41] 41(a) and (b) show a further preferred embodiment for the configuration of the distal end of the second circumferential seal and inner support structure. [Figure 42] FIG. 42 illustrates a housing and a housing cover according to the eighth preferred embodiment of the present disclosure. [Figure 43] FIG. 43 illustrates a housing and a housing cover according to the eighth preferred embodiment of the present disclosure. [Figure 44] FIG. 44 illustrates a filter element usable with the housing and housing cover according to the eighth preferred embodiment of the present disclosure and its installation process.

[0151] The drawing figures are not drawn to scale and proportion, and in the drawings, identical elements are generally designated by identical reference numerals. DETAILED DESCRIPTION OF THE INVENTION

[0152] The present disclosure will be described with reference to specific embodiments. The specific embodiments are illustrative of the present disclosure and should not be construed as limiting. The present disclosure is not limited by what is particularly shown and / or described, and those skilled in the art will understand 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 not limiting.

[0153] Use of the verb "to comprise" and its respective conjugations 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.

[0154] Furthermore, terms such as first, second, etc. in the specification and claims are used to distinguish between similar elements and are not necessarily used to describe an order, whether temporal, spatial, ranking, or otherwise. The terms so used are interchangeable under appropriate circumstances, and it should be understood that the embodiments of the disclosure described herein are capable of operating in orders other than those described or illustrated herein.

[0155] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in one or more embodiments of the present disclosure. Thus, the appearances of the phrase "one embodiment" or "an embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment, and may. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

[0156] Although many of the figures presented and discussed below specifically address embodiments of filter elements for filtering air, the present disclosure is not limited thereto.

[0157] Although the present description refers to a main housing portion 1 and a housing cover 3, this is really a matter of choice. These portions could alternatively be referred to as a first housing portion 1 and a second housing portion 3. Indeed, if, for example, the housing cover 3 is relatively large so as to include most of the complete filter housing, it may be appropriate to refer to it as the main housing portion 1, and the remainder of the housing may be considered 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 cleaner.

[0158] 1 to 3 schematically show a first preferred embodiment of the present disclosure.

[0159] The filter element 2, including the flexible filter media pack 20, is tubularly arranged around 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 end cap 21 and the second end cap 22 are formed and attached to the filter media pack 20, for example, by a polyurethane potting process. In such a case, the first circumferential seal 27 of the first end cap 21 and the 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 conical in its undeformed state.

[0160] The first end cap 21 is flexible, for example, capable of being non-destructively transformed between a first shape and a different second shape, preferably elastically deformable.

[0161] The filter element 2 is disposed within a primary filter housing 1 having a housing sidewall 11 and first and second ends 15, 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 having 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 around the outlet opening 121 when the filter element 2 is inserted into the housing 1.

[0162] The service opening 13 at the first end 15 includes two undercut sections 14 that extend radially inward from the side wall 11 of the housing 1 .

[0163] Because the filter element 2 is essentially conical, for example, the second end cap 22, which cannot be non-destructively deformed, can enter the service opening 13 and be guided toward the second end 16 of the housing 1 for installation. 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, it can be reshaped into a second shape or condition that is smaller and allows it to enter the service 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, adapted and positioned to pull a portion of the first end cap radially inward (see, for example, FIGS. 37(a) and (b) ) can be provided. The manipulation device or device can include a handle bar or structure bridging both sides of the open end cap through the central opening of the first end cap. Alternatively, the optional manipulation means can include at least one radially inwardly or outwardly directed flap or ear structure.

[0164] When the first end cap 21 passes through the service opening 14, it returns to its original shape and is positioned partially below the undercut section 14 in a partial volume 131 of the interior volume of the filter housing 1. Note 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, and this intersection corresponds to the protrusion overlap region.

[0165] A housing cover 3 is then provided to close the housing insertion or service opening 13 (FIG. 3). The housing cover 3 preferably has a conical shape and includes an inner support structure 31 for the filter media pack, such as a tower structure 31, protruding from the proximal end toward the distal end of the 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. The proximal end of the tower structure 31 is closed when the cover 3 is attached to the main housing 1, 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 service opening 13.

[0166] The housing also includes an inlet 17. For example, one or more inlet openings may be provided in the side wall 11 of the housing 1.

[0167] 4-6 show a second preferred embodiment of the present disclosure that is very similar to the first preferred embodiment. It includes a housing inlet tube positioned so that air to be filtered can enter the filter housing perpendicular to the filter housing and filter line. The air then passes through a filter media pack 20 into the filter's internal volume and exits the air cleaner through outlet opening 12. Two diametrically opposed undercut sections 14 are present at service opening 13.

[0168] At least one of the undercut sections 14 includes an alignment portion 141 that mates with a corresponding alignment portion 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 for locking the cover 3 to the main housing 1. The latches 302 on the cover 3 are adapted to lock behind locking portions 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.

[0169] Preferably, one of the closure means, such as latch 302, is located on or adjacent flat 3F and interacts with a counterpart on the housing adjacent undercut 14, preferably adjacent or below flat 14F. Other closure means, such as finger locks, rubber bands, clips, bolts and nuts, etc., can of course also be used.

[0170] 7 shows a variation of the second preferred embodiment. The air cleaner includes an additional element 4 for interacting with the fluid or airflow, such as a safety filter element or a chemical filter element. The additional element 4 is disposed within the media pack support structure or tower 31 and extends partially from the second end 16 toward the first end 15 of the housing. The additional element may include, for example, a circumferential seal oriented radially outward to seal onto the inner sealing surface of the outlet tube 12.

[0171] 8(a)-(c) illustrate a third preferred embodiment of the present disclosure. The third preferred embodiment of the present disclosure is similar to the previous preferred embodiment, but includes a sloped housing / cover interface S. The described concepts are not limited to assemblies including the disclosed filter elements having flexible and / or elastic properties, but are more generally applicable to non-destructively deformable filter elements 2. Additionally, the housing cover 3 includes a single flat section 3F that is complementary to the single undercut section 14 of the service opening 13.

[0172] The housing cover 3 and the filter housing 1 are adapted to meet along an inclined surface S. The inclined surface is configured so 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 that the filter element 2 can be tilted to some extent, for example away from the undercut section 14, before being removed or inserted through the service opening 13 of the main housing 1, thereby allowing the use of a filter element 2 with a relatively resistant or non-deformable first end cap 21 or the use of a relatively large deformable element.

[0173] The housing cover 3 includes an axial end wall 30e connected to a circumferential side wall 30 disposed around the longitudinal axis, and includes a lower edge 30r of the side wall 30 surrounding the filter housing interface opening. The lower edge 30r is defined by a plane inclined relative to a direction perpendicular to the longitudinal axis.

[0174] The axial end wall 30e of the cover 3 is disposed perpendicular to the longitudinal axis, and the circumferential side wall 30 extends from a minimum width at a minimum axial distance between the lower edge 30r and the axial end wall 30e to a maximum width at a maximum axial distance between the lower edge 30r and the axial end wall 30e.

[0175] The contour of the axial end wall 30e of the housing cover 3 (or the protrusion on a plane perpendicular to the axis) corresponds to one (or more) predetermined circular section connected by one (or more) circular chord lines between adjacent circular sections, and the circumferential side wall 30 is interrupted or straight in the area corresponding to the chord line. The interrupted or straight section corresponds 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 abut against each other when the cover 3 is placed on the main housing 1, thereby serving as an alignment portion between the cover 3 and the main housing 1.

[0176] The service opening in the main housing includes an edge 1311 that lies in a plane inclined relative to a direction perpendicular to the longitudinal axis of the housing or housing cover, corresponding to the inclined surface of the lower edge 30r of the housing cover 3.

[0177] 10(a) and (b) show a variation of the third preferred embodiment shown in FIG. 8 , including an open housing side wall 11 including a grid structure, preferably including openings 111 (as inlets) separated by flow guide blades or fins 110. Alternatively, it can be a closed side wall with separate inlet openings. It further includes a latch connection to the housing cover 3 located in the undercut section 14, where 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 located on the side of the housing attachment means 112, which is often the side that is more difficult to reach during servicing. This has the advantage that the latch in the undercut section 14 is easier to reach during servicing compared to a latch attached to the housing side wall 11 on the side of the housing attachment means 112.

[0178] 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 including a latch and catch surface connection between the side walls 30 and 11 of the housing cover 3 and the main housing side wall 11.

[0179] 12(a)-(c), 13 and 14 show 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.

[0180] According to a fourth preferred embodiment, 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 when the filter element 2 is installed in the main housing 1 and the main housing 1 is closed by the cover 3.

[0181] The filter element 2 includes a (preferably, but not necessarily, flexible) filter media pack 20 tubularly disposed 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 outer diameter of the second end cap 22 is smaller than the outer diameter of the first end cap 21.

[0182] Second open end cap 22 includes a central opening and second circumferential seal 28. Second circumferential seal 28 includes a portion that extends radially inward into the central opening of 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 filter media pack 20 (or the interior volume of the filter element), e.g., in a direction parallel to the axis of filter media pack 20 or filter element 2.

[0183] The filter housing includes a first end 15 and a second end 16, with the first end 15 including a filter insertion opening 13 and adapted to receive a cover 3 having a tower 31. The second end 16 is disposed at an end 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.

[0184] In this disclosure, the terms inlet and outlet are used to refer to openings in the housing through which airflow passes "from inlet to outlet." Those skilled in the art will understand that in certain assembly configurations, reverse flow may apply, where the flow may be in the opposite direction from the outlet to the inlet. This does not affect the nature of the inventive concept of the present disclosure.

[0185] The distal end 303 of the support structure 31 is received by an axially extending circumferential groove, trench or recess 281 in the second circumferential seal 28 of the filter element 2 and is positioned and adapted 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.

[0186] 15 and 16 show variations of the fourth preferred embodiment that may be used in combination with, but are not limited to, embodiments that include a media pack support structure 31 that protrudes from the inner surface 301 of the housing cover 3.

[0187] 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 at least one radially inwardly projecting lobe 28r of the second circumferential seal 28 and that corresponds to at least one radially inwardly projecting lobe 19r of the second circumferential seal face 19.

[0188] 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.

[0189] The embodiment of FIGS. 15 and 16 allows for rotational locking of the filter element and a predetermined clock or angular orientation of the filter element 2 within the housing 1.

[0190] In further embodiments, the support structure or tower 31 is not present. The interactions of the distal end of the support structure or tower 31 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- or V-shaped) groove, trench, or recess 281 located adjacent the central opening and performing the same function as described for the distal end 303. The attachment device can generally include, for example, a ring structure and can have radially and axially inwardly projecting lobes similar to those disclosed for the distal end of the tower 31. This also applies to the embodiment described in connection with FIG. 44.

[0191] 17(a)-(c) show a fifth preferred embodiment of the present disclosure that 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 a media support means or tower 31 and the possibility of interaction between the tower (distal end 303) and the second directional seal. Indeed, if the filter element 2 does not include flexible or resiliently deformable portions, for example, in any of the first end cap 21, media pack 20, and second end cap 22, the same advantages exist regarding the interaction between the main housing 1, housing cover 3, and filter element 2, for example, with respect to having a sloped interface S between the housing cover 3 and the main housing 1, and having an undercut section 14 at the housing inlet opening 13 and a complementary flat portion 3F on the housing cover 3.

[0192] 18(a), (b), 19(a), (b) and 20(a), (b) show features of a housing cover for use with any of the embodiments of the present disclosure.

[0193] 18(b) shows that the housing cover 3 can be flat. The housing cover 3 can further include the disclosed flat portions 3F (intermittent or straight) for alignment and other disclosed purposes.

[0194] 18(a) shows a housing cover 3, e.g., as disclosed in connection with FIGS. 8, 10-12, and 17, including an upper or outer surface 300 oriented along a plane P1 perpendicular to the housing cover axis. The lower edge 30r of the 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 both planes may be, for example, between 10° and 45°, more preferably between 5° and 30°.

[0195] 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. *is shown in dashed lines, which corresponds to an undercut section 14 in the associated housing.

[0196] 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 * 3F′ are shown in dashed lines, which correspond to the respective undercut sections 14, 14′ in the associated housing. The flats 3F and 3F′ may be parallel or may be under an angle β.

[0197] 20 shows an advantageous configuration of the disclosed housing cover 3 and filter assembly, where a sensor port 5 with, for example, a pressure sensor 50 is located in the center of the housing cover 3, with a small associated opening towards the clean side of the filter assembly. The pressure sensor has the advantage that it can be visually inspected on the service side of the housing 1, since there is access to the clean side.

[0198] 21-24 show some example first and second circumferential seal configurations and associated sealing surfaces on the housing cover and housing.

[0199] One or both of the first circumferential seal 27 and the second circumferential seal 28 can have a rotationally symmetric profile or can include rotationally asymmetric profiles, as is true for their corresponding seal faces 37 and 19.

[0200] 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, for example, the housing or housing cover.

[0201] 21(a) and 21(b), the first circumferential seal 27 and corresponding seal surface 37 may include a gear-type configuration, such as that described in EP 3413993. The second circumferential seal 28 may be a rotationally symmetric radially (inwardly or outwardly) oriented seal for sealing onto the second circumferential seal surface 19, which may be cylindrical, for example.

[0202] 21(c) shows another embodiment in which the first circumferential seal 27 includes a rotationally symmetric radially (inwardly or outwardly) oriented seal for sealing onto a cylindrical first circumferential seal surface 37. The second circumferential seal 28 may include an inwardly facing gear-type configuration, such as that described in EP 3413993. The second circumferential seal surface 19 may have an outwardly facing corresponding gear-type configuration, such as that described in EP 3413993.

[0203] 22(a)-(b), the first circumferential seal 27 and corresponding seal surface 37 can include a flower-shaped configuration, such as that described in EP 2771092. The second circumferential seal 28 can be a rotationally symmetric, radially (inwardly or outwardly) oriented seal for sealing onto the cylindrical second circumferential seal surface 19.

[0204] 22(c) shows another embodiment in which first circumferential seal 27 includes a rotationally symmetric radially (inwardly or outwardly) oriented seal for sealing onto cylindrical first circumferential seal surface 37. Second circumferential seal 28 may include an inwardly oriented flower-type configuration, for example, as described in EP 2771092. Second circumferential seal surface 19 may have a corresponding outwardly oriented gear-type configuration, for example, as described in EP 277109.

[0205] 23(a) and (b) disclose another 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 for sealing onto the second circumferential seal surface 19, which is cylindrical, for example.

[0206] 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 onto a cylindrical first circumferential seal surface 37. The second circumferential seal 28 can be, for example, a radially (inwardly or outwardly) oriented elliptical seal for sealing onto a corresponding elliptical second circumferential seal surface 19.

[0207] Figure 24 is a perspective view of another embodiment of the present disclosure, which is in some sense a combination of the embodiments of Figures 23(a), (b), and (c). Both the first circumferential seal 27 and the second circumferential seal 28 are elliptical and seal onto corresponding elliptical sealing surfaces 37, 19. The ellipse may have its major axis lying at an angle, for example, a 90° angle or an angle between 15° and 19°.

[0208] It is generally advantageous to have first seal 27 and second seal 28 of different shapes to allow the user to install the cone in the correct orientation, examples of which have been described in connection with Figures 21-23. Installing the cone in the wrong orientation can damage the filter element.

[0209] Other combinations of the disclosed first circumferential seal 27 and second circumferential seal 28 and their corresponding sealing surfaces 37, 19 are contemplated and are contemplated and disclosed.

[0210] 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 element's media pack 20 is flexible, an advantageous filter assembly configuration is provided, where the tubular media pack is twisted and therefore contains a relatively large amount of media per housing interior volume. Such an assembly configuration is achieved as follows: The second circumferential seal 28 and 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 is longer than the housing cavity and protrudes through the service opening 13. The first circumferential seal 27 is then coupled to 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 the cover 3 and one or more complementary undercut sections 14, 14' of the housing inlet 13 can then be aligned by rotating the cover relative to the housing by a predetermined angle, thereby twisting the media pack 20 in a predetermined manner and shortening the filter element 2 so that it can again fit into the housing cavity and close the housing cover. This principle is shown schematically in Figure 25. Figure 25 also shows an example of a locking mechanism 333 of the housing cover 3 to the housing 1 for use with embodiments of the present disclosure, which may be, for example, of a bayonet type or any other state-of-the-art type.

[0211] 26(a)-(c) show further preferred embodiments of the filter element of the present disclosure, in which the first end cap 21 and / or second end cap 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.

[0212] 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.

[0213] 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, and the respective circumferential seals 27, 28 are oriented along the plane defined by the end caps 21, 22.

[0214] 27(a)-(c) illustrate the elastic deformation of the first end cap 21 of a filter element according to an embodiment of the present disclosure, shown in projected views along the filter element line. 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 deformation, primarily due to the presence of two undercut sections 14, 14' on opposite sides 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'.

[0215] 28(a) and (b) show a further preferred embodiment of the present disclosure in which the filter media pack 20 is deformed by a media support structure 31 protruding from the housing cover 3. The filter element 2 is elastically deformable and has a cylindrical or conical shape. The filter element 2 is inserted into a filter housing 1 having a sidewall with a different shape (e.g., a constant cross-section, D-shaped in projection). The service 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, in its deformed state, is guided by the sidewall of the service opening and the sidewall of the housing. After installation, the elastically deformable filter element 2 is adapted to or takes the shape of the filter housing volume. Then, 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 into the interior of the filter media pack 20 and is supported from the inside.

[0216] 29(a) and 30 illustrate a sixth preferred embodiment of the present disclosure, including a first primary filter element 2 and a second primary filter element 6, where the second filter element 6 is not a safety filter element but instead 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 to receive 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, for example, centrally located in the axial end wall of the housing cover 3, radially disposed within the second circumferential sealing surface 67. The second filter element may be, for example, conical, contain a tubular array or pleated media, and have a closed end cap opposite the seal 67. Air entering the openings O3A 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.

[0217] 31(a), (b), and 32 illustrate a variation of the sixth preferred embodiment of the present disclosure. In FIGS. 31(a) and 31(b), a second filter element 6 is provided that includes a grooved media type media 60, such as wound grooved media. The cover includes one inlet opening O3A located centrally in the axial end wall of the housing cover 3, radially positioned within the second circumferential sealing surface 67. Air entering the opening O3A enters the clean air side of the first filter element 2 and is filtered by the second grooved filter element 6 before leaving the filter assembly through the outlet 12. FIG. 32 illustrates a variation in which the inlet opening O3A further includes a vane or waffle structure O3AW that includes airflow-guiding ribs that facilitate increasing the uniformity of the incoming airflow. The airflow-guiding ribs are preferably parallel to the axis of the grooved media pack 60.

[0218] 29(b) shows a seventh preferred embodiment of the present disclosure. The cover 3 includes a first circumferential seal 27 and one or more centrally located axial end wall outlet openings O3B, e.g., located radially within the first circumferential seal surface 37. The outlet openings O3B thereby form second outlets 12' for clean air from the housing 1 that can be directed to a second air consuming means, such as a compressor.

[0219] 33 shows a variation of the seventh preferred embodiment, in which a single centrally located second outlet opening O3B is provided, which may for example be part of a second outlet conduit of the housing 1 (in the outlet cover 3).

[0220] 34(a)-(c) show a variation of the seventh preferred embodiment of the present disclosure. Similar to the embodiment of FIG. 33, this variation includes a single, centrally located second outlet opening O3B. This variation includes a set of openings 33t in the housing cover 3, radially outward of the first circumferential sealing surface 37 and circumferentially distributed over 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. As mentioned above, the radial sidewall 30 of the housing cover 3 may further include openings 33, optionally defined in a grid structure between air flow guiding means or devices 34, such as ribs, fins, or blades, as inlet openings.

[0221] As described in various embodiments, for example in connection with the embodiments relating to Figures 1-16 and 30-31, alternative configurations for the interaction of the distal end 303 of the inner support structure or tower 31 with the circumferential groove, trench or recess 281 are shown in Figures 38(b), 39, 40(a)(b), and 41(a)(b).

[0222] 38(a) illustrates a problem that can occur when the distal end of a support structure is received by a trench in circumferential seal 28. If trench 281 in seal 28 contains localized deformations and / or distal end 303 of support structure 31 is not perfectly aligned with trench 28 upon insertion, distal end 303 may press against seal 28 adjacent trench 281, which typically results in deformation of seal 28 and at least localized deformation or closure of trench 281, preventing distal end 303 from being received by trench 281.

[0223] FIG. 38(b) illustrates a trench 281 having a radially inner wall 2813 and a radially outer wall 2812 connected by a bottom wall 2815. The radially outer wall 2812 includes a beveled or chamfered portion or surface 2814 adjacent the opening of the trench 281, thereby widening the trench 281 adjacent its opening. The beveled portion of the surface 2814 facilitates positioning and / or receipt of the distal end 303 of the inner support structure 31 by the trench 281. At a height below the beveled portion 2814, the width of the trench 281 is preferably 2 to 10 mm or 3 to 8 mm. At the opening of the trench 281, the width of the trench 281 may increase by approximately 1 to 6 mm or approximately 3 to 5 mm due to the beveled portion or surface 2814. The beveled portion 2814 preferably forms an angle with the radially inner wall 2813 within a range of 10° to 45°. Apart from the inclined portion 2814, there may be a small angle between the non-inclined portion of the radially inner sidewall 2813 and the radially outer sidewall 2812. That is, these sidewalls are not perfectly parallel. They may be at an angle of, for example, 0° to 10°, preferably 1° to 7°, e.g., 2°. The depth of the circumferential trench 281 may be, for example, in the range of 5 mm to 40 mm or 10 mm to 40 mm.

[0224] It has been found that, in some cases, when the distal end 303 of the inner support structure 31 is received within 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 can form within the trench 281. During reception, this air pocket can provide resistance to the insertion process. Also, during removal, the air pocket can provide under pressure during the removal process, thereby preventing easy removal of the inner support structure 31. FIG. 39 illustrates an embodiment that solves the above problem. The radially outer sidewall 2812 (or the radially inner sidewall 2813) includes one, two, or more axially extending fluid communication channels 2811. These channels preferably connect the cavity formed by the sidewalls (2812, 2813, 2815) of the trench 281 and the distal end 303 of the inner support structure 31 to the interior volume of the filter element 2.

[0225] 40(a) and (b) show a trench 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 ramp or inclined surface 2814 adjacent the opening of the trench 281, as previously described. The second circumferential seal 28 further includes a plurality of, preferably regularly spaced, spacing ribs 2816 that connect and bridge the radially inner and outer sidewalls (2813, 2812), preferably in a direction perpendicular to the circumferential direction of the trench 281. This provides the advantage of allowing for a more consistent groove width. Pockets 2817 are thereby formed in the trench 281 between adjacent spacing ribs 2816. These pockets 2817 can receive distal axial extensions 3031 ("teeth") of the distal end 303 of the associated inner support structure 31. In another illustration, the distal end 303 may include a series of regularly spaced axial cuts into which spacing ribs 2816 are received when the inner support structure 31 is received by the trench 281 in one of a number of relative angular alignment positions.

[0226] 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.

[0227] 41(a), one pocket 2817' of the preferably regularly spaced pockets 2817 is deeper than the others and is located on the axially extending portion 2819 of the circumferential seal 28. The pocket 2817' can receive a corresponding tooth 3031' that is longer than the other teeth 3031 on the distal end 303. Only when the longer tooth 3031' is aligned with the deeper pocket will the inner support structure 31 be properly received by the trench 281.

[0228] 41(b), the portion of the seal 28 that preferably corresponds to the location of one of the regularly spaced pockets 2817 does not include a pocket 2817 (or includes a closed pocket). The distal end 303 does not have a corresponding tooth 3031 (gap 3032). Only when the location of the closed pocket aligns with the location of the gap 3032 will the inner support structure 31 be properly received by the trench 281.

[0229] 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. Alternatively, the filter element 2 can be maintained in a deformed state by a retaining means (not shown) prior to insertion into the packaging container 9. For example, the filter element 2 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 adapted and has sufficient strength to deform all or a portion of the filter element 2 (e.g., optionally selected from the first end cap 21, the filter media pack 20, and the second end cap 22) when the filter element 2 is inserted into the packaging container 9.

[0230] 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 located at the lower end of the housing inlet opening when the air filter housing is in use.

[0231] 37(a) and (b) show an example of a first end cap equipped with an operating means.

[0232] 37(a) illustrates an embodiment in which the protruding structure 270 surrounding the central opening of the first end cap and supporting or forming the first, preferably inward-facing, circumferential radial seal 27 also includes a handle portion 271 extending radially outward from the remainder of the structure 270. The handle portion is configured to be grasped by an adult's fingers.

[0233] 37(b) shows another embodiment. The protruding structure 270 surrounding the central opening of the first end cap and supporting or forming the first, e.g., inwardly facing, circumferential 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 a parallel exposed surface 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 parallel to the flat portion 14F, for example.

[0234] 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.

[0235] 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 edge 30r' of the side wall 30 that surrounds the interface opening of the filter housing. The lower edge 30r' is at least partially or completely defined by a plane that is inclined relative to a direction perpendicular to the longitudinal axis.

[0236] 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 edge 30r' and the axial end wall 30e and a maximum width at a maximum axial distance between the lower edge 30r' and the axial end wall 30e.

[0237] 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 airflow guide vanes 34 and / or ribs.

[0238] The housing cover 3 further includes a filter media or outer support structure 35 that protrudes axially from the inner surface of the axial end wall 30e. The media support structure 35 includes a tower structure that extends axially from a proximal end at the inner surface of the cover 3 to a distal end 351 away 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.

[0239] 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 .

[0240] The main housing 1 includes a service opening, an outlet 12, and mounting means 112 for receiving the filter element 2 within the main housing 1. The service opening includes an edge 1311 located on a plane inclined relative to a direction perpendicular to the longitudinal axis of the main housing 1, corresponding to the inclined surface of the lower edge 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, and are embodied, for example, as a grid structure including airflow guide vanes or ribs 110.

[0241] 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 internally support the filter media pack 20.

[0242] FIG. 44 illustrates a filter element 2 used with a housing 1 and a housing cover 3 and its installation process according to the eighth preferred embodiment of the present disclosure.

[0243] Contrary to the configurations of the embodiments associated with Figures 12-16, 30-31 and 38-41, the second circumferential seal 28 is configured to seal radially inward, whereas the filter element 2 of Figure 44 is configured to seal radially outward.

[0244] The second end cap 22 of the filter element 2 includes a portion of a second circumferential seal 28 disposed about the outer periphery of the second end cap 22 and the filter media 20. 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.

[0245] 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 to the seal 28, improving and securing the sealing of the seal 28 against the sealing surface 19.

[0246] As described for the embodiment having a radially inward sealing direction of the second circumferential seal 28, similar improvements can be applied to the trench 281 and / or the distal end 351. For example, the side surface (here, the radially outward surface) of the trench 281 can include a sloped portion.

[0247] Illustrative Embodiments For example, the following may be claimed: 1) A filter element comprising: a flexible filter media pack tubularly arranged around 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, for example, non-destructively deformable 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%, or at least 10%, or at least 15%, or at least 20%, or at least 25%, or at least 30%, or at least 40%, or 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) A filter element according to any of the preceding items, wherein the first end cap is connected to the filter medium and is 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 includes N-fold rotational symmetry, for example, 1-fold rotational symmetry, about the axis of the filter media pack. 7) The filter element according to item 5 or 6, wherein the first circumferential seal is disposed along a plane inclined relative to a plane perpendicular to the axis of the filter media pack. 8) The filter element of any preceding item, wherein the first end cap is capable of radial deformation by a radial force component of less than 40 N. 9) The filter element of any of the preceding items, wherein the first end cap further includes at least one operating means, such as a handle, adapted and arranged to pull 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 both sides of the open end cap through a central opening in the first end cap. 11) The filter element according to either item 9 or 10, wherein the operating means includes at least one flap or ear structure directed radially inward or outward. 12) The filter element of any preceding item, wherein the filter media packs are conical, i.e., arranged in a cone 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, and the second end cap has a smaller outer diameter than the first end cap. 13) The filter element of any preceding item, wherein the second end cap is flexible, e.g., incapable of being non-destructively deformed between a first shape and a different second shape. 14) The filter element of any preceding item, wherein the second open end cap's second shape has a minimum radial cross-sectional dimension that is at least 5%, or at least 10%, or at least 15%, or at least 20%, or at least 25%, or at least 30%, or at least 40%, or 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 preceding item, wherein the second end cap is capable of radial deformation by a radial force component of less than 40 N. 16) The filter element of any preceding item, wherein the second end cap is elastically deformable. 17) The filter element of any one 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 preferably includes a second circumferential seal integrally formed with the second end cap. 19) The filter element of item 18, wherein the second circumferential seal includes N-fold rotational symmetry, for example, 1-fold rotational symmetry, about the axis of the filter media pack. 20) The filter element according to item 5 or 6, wherein the second circumferential seal is disposed along a plane inclined relative to a plane perpendicular to the axis of the filter media pack. 21) A filter element according to any one of items 18 to 20, wherein the second open end cap includes a central opening, the second circumferential seal is embodied as a radially inward extension of the central opening extension of the second end cap, and the radially inward extension includes at least one axially extending circumferential, e.g., V-shaped or U-shaped, groove, trench, or recess disposed adjacent to the central opening, the groove, trench, or recess protruding into the interior volume of the filter media pack, preferably 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 comprises pleated media, the media comprising one or more layers selected from the group consisting of a media layer and a support layer. 23) A filter element according to any of the preceding items, comprising a free-standing filter media pack. 24) A package including a box, bag, or sleeve containing a filter element according to any of the preceding items, wherein the filter element is held in an elastically deformed form by the inner wall of the box, bag, or sleeve. 25) A filter assembly including a filter housing having a housing shaft and a filter element according to any one of items 1 to 23, wherein the filter housing includes a filter insertion opening (or service opening) that is too small to insert the first end cap into the filter housing when the first end cap has a first shape, but is large enough to insert the first end cap into the filter housing when the first end cap has a second shape. 26) The filter assembly described in item 25, wherein the insertion opening includes at least one undercut section, and a projection of the filter element along the housing axis intersects with a projection of the undercut section along the housing axis, the intersection corresponding to a projection overlap region. 27) The filter assembly of item 26, wherein the projected overlap area is greater than 1%, or greater than 2%, or greater than 3%, or greater than 5%, or greater than 10% of the projected area of ​​the filter element along the housing axis. 28) A filter assembly described in any of items 25 to 27, wherein the housing includes a housing cover for 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 described in any of items 25 to 28, further including a housing cover that covers the insertion opening, wherein the housing cover and the filter housing are adapted to meet along an inclined surface, and the inclined surface is configured so that the housing length on the side corresponding to the projected overlap area is longer than the housing length on the opposite side of the housing. 30) A filter assembly according to any one of items 25 to 29, further comprising a housing cover, the housing cover including a filter media pack inner support structure, preferably a conical tower structure, protruding from the inner surface from the proximal end towards the distal end of the cover. 31) A filter assembly according to item 25 or 30, including a housing cover, the housing cover including a pressure sensor mount and optionally a pressure sensor. 32) A filter assembly according to any one of items 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) A filter assembly according to any one 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 including a filter insertion opening and configured to receive the cover, the second end being disposed at an end 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) A filter assembly according to any one of items 25 to 33, wherein the filter element is dependent on item 21 and the cover is dependent on item 30, and wherein a distal end of the support structure is received by an axially extending, e.g., V-shaped or U-shaped, peripheral groove, trench, or recess of a second circumferential seal of the filter element, and is positioned and adapted to apply radially outward back pressure to the circumferential seal against 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 being located in an undercut section within the housing, preferably adjacent to, below, preferably directly below or adjacent to the insertion opening. 36) The filter assembly of any one of items 25 to 35, wherein the filter media packs of the filter element are installed in a twisted configuration. 37) A filter assembly according to any one of items 25 to 36, wherein the housing includes a housing sidewall that is disposed generally along an outer radial surface of the filter media pack, is open, and includes a grid structure. 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 air flow guides. 40) A filter housing including an inlet and an outlet, adapted to sealingly receive a replaceable filter element so that air flowing from the inlet of the housing to the outlet of the housing is filtered by the filter element, the filter housing including a service opening in a main portion of the housing for receiving the filter element, the housing including a housing cover for closing the service opening, the inlet of the housing being provided in the main portion and / or the housing cover, the inlet including a lattice-like inlet structure. 41) The filter housing of item 40, wherein the housing includes a housing sidewall that is generally positioned along an outer radial surface of the filter media pack when installed within the housing, the outer radial surface including a lattice structure. 42) The filter housing according to item 40 or 41, wherein the radial sidewall of the cover includes a lattice structure. 43) A filter housing according to any one of items 40 to 42, wherein at least one of the lattice structures of the cover or the housing side wall includes one or more air flow guiding means such as air flow guiding ribs, fins or vanes. 44) A filter housing according to any one of items 40 to 43, wherein the main body of the housing and / or the housing cover comprises plastic. 45) A filter housing according to any one of items 40 to 44, wherein the housing main portion and / or the housing is formed by injection molding.

[0248] For example, the following may also be claimed: 1) A filter element comprising: a flexible filter media pack tubularly disposed 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 second open end cap comprises a central opening and a second circumferential seal comprising a radially inward extension of the central opening extension of the second end cap, the radially inward extension comprising 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. 2) The filter element according to item 1, wherein the circumferential groove, trench or recess is oriented in a direction parallel to the axis of the filter media pack. 3) The filter element according to any of the preceding items, wherein the circumferential groove, trench, or recess includes a chamfer or a sloped portion. 4) The filter element according to any of the preceding items, wherein the groove, trench, or recess includes a radially inner wall and a radially outer wall connected by a bottom wall, and the second circumferential seal further includes a plurality of, preferably regularly spaced, spacing ribs bridging the radially inner wall and the radially outer wall. 5) The filter element according to item 4, wherein pockets are formed in the trench between adjacent spacing ribs. 6) The filter element of any of the preceding items, wherein the groove, trench, or recess includes a radially inner wall and a radially outer wall connected by a bottom wall, and the radially outer wall or the radially inner wall includes one, two, or more axially extending fluid communication channels. 7) The filter element of any preceding item, wherein the filter media packs are conical, i.e., arranged in a cone 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, and the second end cap has a smaller outer diameter than the first end cap. 8) The filter element of any preceding item, wherein the second end cap is flexible, e.g., incapable of being non-destructively deformed between a first shape and a different second shape. 9) The filter element of item 8, wherein the second open end cap's second shape has a minimum radial cross-sectional dimension that is at least 5%, or at least 10%, or at least 15%, or at least 20%, or at least 25%, or at least 30%, or at least 40%, or 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 preceding item, wherein the second end cap is capable of radial deformation 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 preceding item, wherein the second end cap is elastically deformable. 13) The filter element of item 9, 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 includes N-fold rotational symmetry, for example 1-fold rotational symmetry, about the axis of the filter media pack. 15) The filter element of item 14, wherein the second circumferential seal includes at least one radially projecting lobe. 16) The filter element of item 14, wherein the second circumferential seal includes at least one axially projecting lobe. 17) The filter element of any preceding item, wherein the second circumferential seal is disposed along a plane that is inclined relative to a plane perpendicular to the axis of the filter media pack. 18) The filter element of any of the preceding items, wherein the filter media pack comprises a pleated media, the media comprising one or more layers selected from the group consisting of a media layer and a support layer. 19) The filter element of any of the preceding items, wherein the second end cap is connected to the filter medium by potting and is optionally manufactured by potting. 20) A filter assembly including a filter housing having a housing axis and a filter element according to any one of items 1 to 19 disposed within the housing along the housing axis, wherein the filter housing includes 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 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 being disposed at an end 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 a distal end of the support structure is received by an axially extending peripheral groove, trench, or recess in a second circumferential seal of the filter element and is positioned and adapted to apply radially outward back pressure to the circumferential seal against a sealing surface of the filter housing when the cover is attached to the housing. 22) A filter assembly described in any of items 20 to 21, as long as it is dependent on item 15, wherein the distal end of the support structure includes at least one radially projecting lobe corresponding to at least one radially projecting lobe of the second circumferential seal. 23) A filter assembly according to any one of items 20 to 21, as long as it is dependent on item 15, wherein the distal end of the support structure includes at least one axially projecting lobe corresponding to at least one radially projecting lobe of the second circumferential seal.

[0249] For example, the following may also be claimed: 1) A filter element comprising: a preferably flexible filter media pack tubularly arranged around 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 second open end cap comprises a second circumferential seal, the second circumferential seal comprising a circumferential trench, groove, or recess extending radially outward from the filter media pack and protruding 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 of item 1, wherein the circumferential trench, groove, or recess is oriented in a direction parallel to the axis of the filter media pack. 3) The filter element according to any of the preceding items, wherein the circumferential trench, groove, or recess includes a chamfered or angled portion. 4) The filter element according to any of the preceding items, wherein the groove, trench, or recess includes a radially inner wall and a radially outer wall connected by a bottom wall, and the second circumferential seal further includes a plurality of, preferably regularly spaced, spacing ribs bridging the radially inner wall and the radially outer wall. 5) The filter element according to item 4, wherein a pocket is formed in the trench between adjacent spacing ribs. 6) The filter element of any of the preceding items, wherein the groove, trench, or recess includes a radially inner wall and a radially outer wall connected by a bottom wall, and the radially outer wall or the radially inner wall includes one, two, or more axially extending fluid communication channels.

[0250] 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, the projection of the axial end wall along the longitudinal axis on a plane perpendicular thereto comprising one-fold rotational symmetry with respect to the longitudinal axis. 2) A housing cover according to item 1, comprising an axial end wall connected to a circumferential side wall arranged about a longitudinal axis, the cover defining a lower edge of the side wall surrounding a housing interface opening, the circumferential side wall being discontinuous (or including one or more, e.g., an annular gap) within one or more angular ranges about the longitudinal axis, or being straight or substantially straight. 3) The 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 a circular shape between adjacent circular sections, and the circumferential side wall is interrupted or straight in the area corresponding to the chord lines. 4) A housing cover according to any preceding item, further comprising a sensor port opening in the shaft 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 item 5 or 6, wherein the circumferential sealing surface includes N-fold rotational symmetry. 8) The housing cover according to 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 located axial end wall outlet openings located radially within the sealing surface. 10) The housing cover of any of the preceding items, including 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 centrally located axial end wall inlet openings located radially within the second circumferential sealing surface. 11) A housing cover according to any of the preceding items, wherein the second circumferential sealing surface includes N-fold rotational symmetry. 12) A housing cover according to any preceding item, further comprising a filter medium support structure (inner or outer) protruding axially or primarily axially from the inner surface to the axial end wall. 13) The housing cover of item 12, wherein the filter medium support structure includes a tower structure, preferably a conical tower structure, extending axially from a proximal end on the inner surface of the cover to a distal end remote from the cover. 14) The housing cover of item 13, wherein the distal end of the tower structure includes N-fold rotational symmetry about the longitudinal axis. 15) A housing cover according to any of the preceding items, wherein the lower edge is defined by a plane inclined with respect 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 edge and the axial end wall and a maximum width at a maximum axial distance between the lower edge and the axial end wall. 17) A housing cover according to any of the preceding items, wherein the housing side wall includes one or more housing cover side wall openings. 18) A housing cover according to any one of items 2 to 17, further comprising at least one subcomponent of a cover closure means or device disposed in or adjacent to a position in which the circumferential side wall is interrupted (or includes one or more gaps) or is straight or substantially straight. 19) An assembly comprising: a main housing having a service opening for receiving a filter element within the housing; and a housing cover according to any of the preceding items for covering the service opening, the service opening including at least one undercut section complementary to an interrupted or straight section of the housing cover when the cover is placed on the main housing.

[0251] 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, the housing cover defining a lower edge of the side wall surrounding a filter housing interface opening. 2) The housing cover described in 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 edge and the axial end wall and a maximum width at a maximum axial distance between the lower edge and the axial end wall. 3) A housing cover according to any of the preceding items, wherein the housing side wall includes one or more housing side wall openings. 4) A housing cover according to any preceding item, further comprising a sensor port opening in the axial end wall. 5) A housing cover as described in items 1 to 3, 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 item 5 or 6, wherein the circumferential sealing surface includes N-fold rotational symmetry. 8) The housing cover according to 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 located axial end wall outlet openings located radially within the circumferential sealing surface. 10) The housing cover of any one of items 1 to 8, including 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 centrally located axial end wall inlet openings located radially within the second circumferential sealing surface. 11) The housing cover according to item 10, wherein the second circumferential sealing surface includes N-fold rotational symmetry. 12) A housing cover according to any preceding item, further comprising a filter media support structure (internal or external) protruding axially from the inner surface to the axial end wall. 13) The housing cover of item 12, wherein the filter medium support structure includes a tower structure, preferably a conical tower structure, extending axially from a proximal end on the inner surface of the cover to a distal end remote from the cover. 14) The housing cover of item 13, wherein the distal end of the tower structure includes 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 (or includes one or more annular gaps) or straight within one or more angular ranges about the longitudinal axis. 16) 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 a circular shape between adjacent circular sections, and the circumferential side wall is interrupted or straight in an area corresponding to the chord lines (defining one or more flat portions of the housing cover). 17) An assembly including: a main housing having a service opening for receiving a filter element within the main housing; and a housing cover for covering the service opening described in any of the preceding items, the service opening including an edge lying in a plane inclined relative to a direction perpendicular to the longitudinal axis of the cover. [Explanation of symbols]

[0252] 1 Main filter housing or first housing part 2 filter elements 3 Housing cover or second housing part 3F, 3F' flat area 3V dust exhaust valve 4. Further Elements 5 Sensor Port 6 Second Main Filter Element 9 Packaging containers 11 Housing side wall 12, 12' outlet pipe or housing outlet 13 Filter insertion or service 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 Rock Club 19 Sealing surface 19r Lobes projecting radially inward 19s Axially inward projecting lobes 20 filter media packs 21 First end cap 22 Second end cap 25 First shaft end 26 Second shaft end 27 First circumferential seal 28 Second circumferential seal 28r Lobes projecting radially inward 28s Axially inward projecting lobes 30 Circumferential side wall 30e shaft end wall 30r, 30r' Lower edge of circumferential side wall 31 Inner support or tower structure 32 Rib or grid structure 33 Opening in circumferential side wall of cover 33t Housing cover opening 34 Air flow guide means 35 External support structure 37, 37' sealing surface 50 Pressure Sensor 60 Filter media 67 Second circumferential seal surface 90 Insertion opening 110 Airflow guide blade or fin 111 Openings separated by airflow guide blades 112 Mounting means 113 Supporting structures or towers 121 Exit opening 131 Subvolume of the internal volume of the filter housing 141 Alignment Section 270 Protruding structure 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 protruding lobe 303s Axially Protruding Lobe 333 Locking mechanism 351 distal end of outer support structure 352 Openings in outer support structures 353 Ribs / Gratings of Outer Support Structure 1311 Sloped housing edge 2811 Axially extending fluid communication channel 2812 Radial outer wall of 281 2813 Radial inner wall of 281 2814 Sloped or chamfered portion of 2813 2815 Lower wall of 281 2816 Spacing Rib 2817, 2817' pocket 2818 Closed Sealed Compartment 2819 Axial extension 3031, 3031' Axially extending segments or teeth at the distal end 3032 Distal end gap L Housing length O3A Cover entrance opening O3AW Vane or waffle arrangement O3B shaft end wall outlet opening P1 plane P2 Second plane S inclined plane

Claims

1. 1. A housing cover for a filter housing, comprising: a) an axial end wall connected to a circumferential side wall disposed about the longitudinal axis, the axial end wall defining a lower edge of the side wall surrounding the filter housing interface opening, the lower edge being defined by a plane inclined with respect to a direction perpendicular to the longitudinal axis; Including the housing cover.

2. 2. The housing cover of claim 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 edge and the axial end wall and a maximum width at a maximum axial distance between the lower edge and the axial end wall.

3. The housing cover of claim 1 or 2, wherein the housing side wall includes one or more housing side wall openings.

4. The housing cover of claim 1 , further comprising a sensor port opening in the shaft end wall.

5. 4. The housing cover of claim 1, further comprising an inner surface and a circumferential sealing surface disposed on the inner surface for receiving a filter element seal.

6. The housing cover of claim 5 , wherein the circumferential sealing surface projects axially from the axial end wall on the inner surface.

7. 7. The housing cover of claim 5 or 6, wherein the circumferential sealing surface includes N-fold rotational symmetry.

8. The housing cover of claim 1 , further comprising one or more axial end wall openings in the axial end wall.

9. 9. A housing cover according to claim 8, including one or more, for example centrally located, axial end wall outlet openings located radially within the circumferential sealing surface.

10. 9. A housing cover as described in any one of claims 1 to 8, including 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, for example centrally located, axial end wall inlet openings radially located within the second circumferential sealing surface.

11. The housing cover of claim 10 , wherein the second circumferential sealing surface includes N-fold rotational symmetry.

12. 12. The housing cover of claim 1, further comprising a filter media support structure (internal or external) projecting axially from the axial end wall from the inner surface.

13. 13. The housing cover of claim 12, wherein the filter media support structure comprises a tower structure, preferably a conical tower structure, extending axially from a proximal end to a distal end remote from the cover on an inner surface of the cover.

14. The housing cover of claim 13 , wherein the distal end of the tower structure includes an N-fold rotational symmetry about the longitudinal axis.

15. 15. A housing cover according to any preceding claim, wherein the circumferential side wall is discontinuous (or includes one or more annular gaps) or straight within one or more angular ranges about the longitudinal axis.

16. 16. The housing cover of claim 15, wherein the contour of the axial end wall generally corresponds to one or more subsequent sections of a predetermined circle, the one or more subsequent sections being connected by one or more chord lines of the circle between adjacent circular sections, and the circumferential side wall is interrupted or straight within areas corresponding to the chord lines (defining one or more flat portions of the housing cover).

17. 17. An assembly comprising: a main housing having a service opening for receiving a filter element within the main housing; and a housing cover according to any one of claims 1 to 16 for covering the service opening, the service opening including an edge that lies in a plane that is inclined relative to a direction perpendicular to a longitudinal axis of the housing cover, the plane corresponding to the inclined surface of a lower edge of the housing cover.

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