An air filter cartridge

Abstract

An air filter cartridge (1002) comprising a filter body (1002a) and a threaded arrangement (1, 101, 201) for connection with a thread (20, 120, 220) of a filter housing (1003), the threaded arrangement (1, 101, 201) having a leading end (1a, 101a, 201a), a trailing end (1b, 101b, 201b) opposite to the leading end (1a, 101a, 201a) and at least a first thread (10, 110, 210) extending helically along a longitudinal axis (A) from the leading end (1a, 101a, 201a) to the trailing end (1b, 101b, 201b), the first thread having a crest (11, 111), a root (12, 112), a pitch (p), a thread height (H) extending in the direction from the root (12, 112) to the crest (11, 111), a leading flank (13, 113) facing the leading end (1a, 101a, 201a) for leading the connection, and a trailing flank (14, 114) facing the trailing end (1, 101b, 201b) and having an engagement portion (14', 114'), wherein a steepness of the engagement portion (14', 114') of the trailing flank (14, 114) with regards to the longitudinal axis (A) is smaller than an average steepness of the leading flank (13, 113) with regards to the longitudinal axis (A), the engagement portion (14', 114') extending along at least 65 % of the thread height (H) and being inclined (β) between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis (A).

Description

AN AIR FILTER CARTRIDGETECHNICAL FIELD

[0001] The disclosure relates generally to air filter systems. In particular aspects, the disclosure relates to an air filter cartridge. The disclosure can be applied to heavy-duty vehicles, such as trucks, buses, and construction equipment, among other vehicle types including marine vessels. Although the disclosure may be described with respect to a particular vehicle, the disclosure is not restricted to any particular vehicle.BACKGROUND

[0002] Vehicles equipped with a combustion engine comprise several filters which need to be changed during maintenance operations. These filters are usually contained in disposable cartridges, which are directly fixed to the combustion engine through a base, or placed in a bowl or a filter housing which is fixed to the engine. In most cases, the filter cartridge is threaded in such a way that it can be screwed onto, or into, the filter housing. Threaded connections are usually formed using metric ISO standard thread. Those standard thread connections allow the manual tightening of the filter cartridge to the filter housing. However, such standard thread connections are not adapted to resist high ripping-out forces. In case of prolonged internal pressure, or overpressure, or in case the filter cartridge is not properly tightened, then the filter cartridge can be ripped out and detached from the filter housing. Therefore, it is desirable to prevent unintentional rip out of the filter cartridge from the filter housing, while maintaining the easiness of the manual tightening. This is particularly true for an air filter cartridge or an air-dryer filter cartridge for compressed air systems of a truck. Given these challenges, there exists a need for an improved air filter cartridge and air filter system that addresses at least some of the limitations of current systems.SUMMARY

[0003] An object of the present invention is to at least partly overcome the above problems, and to provide an air filter cartridge which is improved compared to prior art solutions. The air filter cartridge comprises a filter body having a threaded arrangement forconnection with a thread of a filter housing. The threaded arrangement has a leading end, a trailing end opposite to the leading end and at least a first thread extending helically along a longitudinal axis from the leading end to the trailing end. The first thread comprises a crest, a root, a pitch, a thread height extending in the direction from the root to the crest, a leading flank facing the leading end for leading the connection, and a trailing flank facing the trailing end and having an engagement portion. By arranging the first thread with a steepness of the engagement portion of the trailing flank which is smaller than an average steepness of the leading flank, a threaded structure which achieves a well-balanced distribution between shear forces (typically the radial force of the shear forces) and the potential contact area is provided, as well as a tight sealing at the trailing flank when being subject to a pressure from the leading end to the trailing end (i.e. under operational load), e.g. when the air filter cartridge is connected to a pressurized vessel, the pressurized vessel comprising or constituting the filter housing. Hence, the threaded arrangement provides for an advantageous thread design which may be used for attaching a disposable filter to a pressurized vessel, in particular an air filter cartridge to a filter housing. The engagement portion of the trailing flank is typically the portion of the trailing flank which is intended to be brought into contact with the corresponding flank of the thread of the filter housing under operational load. Typically, the engagement portion makes up a majority of the trailing flank, such as a substantial portion of the trailing flank, and therefore a satisfying contact area with the corresponding flank of the thread of the filter housing can be achieved when a pressure is applied from the leading end to the trailing end (e.g. a pressure, such as a prolonged internal pressure or overpressure, which otherwise may cause the air filter cartridge to be ripped out and detached from the filter housing). Hereby, a strong thread, or at least a thread that does not prematurely break or prematurely wear out, and which provides a sufficient sealing between the filter housing and air filter cartridge, can be achieved. In other words, the stress induced by the radial force may be balanced with the size of the engagement portion, or the intended associated contact area between the engagement portion and the corresponding flank of the thread of the filter housing. The engagement portion may e.g. make up at least 65 %, or at least 80 %, of the trailing flank. The steepness of the engagement portion of the trailing flank and the average steepness of the leading flank are referring to a corresponding inclination with regards to the longitudinal axis. That is, the average steepness of the leading flank may be correspondingly to the inclination, or average inclination, of the leading flankwith regards to the longitudinal axis. Additionally or alternatively, the steepness of the engagement portion of the trailing flank may be correspondingly to the inclination, or average inclination, of the engagement portion relative to the longitudinal axis. The air filter cartridge may e.g. be an air-dryer filter cartridge, and the filter housing an air-dryer filter housing.

[0004] According to a first aspect of the disclosure, an air filter cartridge comprising a filter body and a threaded arrangement for connection with a thread of a filter housing is provided. The threaded arrangement has a leading end, a trailing end opposite to the leading end and at least a first thread extending helically along a longitudinal axis from the leading end to the trailing end, the first thread having a crest, a root, a pitch, a thread height extending in the direction from the root to the crest, a leading flank facing the leading end for leading the connection, and a trailing flank facing the trailing end and having an engagement portion, wherein a steepness of the engagement portion of the trailing flank with regards to the longitudinal axis is smaller than an average steepness of the leading flank with regards to the longitudinal axis, the engagement portion extending along at least 65 % of the thread height and being inclined between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis. The first aspect of the disclosure may seek to overcome problems with unintentional detachment of the air filter cartridge from the filter housing (e.g. by the air filter cartridge being ripped out) while providing a tight sealing at the trailing flank when being subject to a pressure from the leading end to the trailing end. By the first aspect of the disclosure, an improved threaded arrangement is provided. Typically, the threaded arrangement may provide for a strong thread, or at least a thread that does not prematurely break or prematurely wear out, and which provides a sufficient sealing between the filter housing and air filter cartridge. In other words, the combination of having an engagement portion of the trailing flank which is less steep than the average steepness of the leading flank, and wherein the engagement portion is inclined by between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis, may provide for a threaded arrangement which achieves a well-balanced distribution with regards to at least the radial force of the shear forces (resulting in induced stresses in the thread) on one hand, and the size of the engagement portion or the intended associated the contact area between the engagement portion and the thread of the filter housing, on the other hand, while providing a tight sealing at the trailing flank when being subject to a pressure from the leading end to the trailing end. By providingan engagement portion extending along at least 65 % of the thread height, the engagement portion will make up a majority of the trailing flank, such as a substantial portion of the trailing flank. For example, the engagement portion may make up at least 65 % of the trailing flank, such as e.g. 80 % of the trailing flank. A technical benefit may include improved distribution with regards to shear forces (at least the radial force thereof) between the engagement portion of the first thread and the corresponding thread of the filter housing. Another technical benefit may include reduced wear of the threaded arrangement. Another technical benefit may include a tight sealing at the trailing flank when the air filter cartridge is subject to a pressure from the leading end to the trailing end, typically when the air filter cartridge is connected to filter housing of a pressurized vessel, e.g. an air-dryer housing. In other words, by the above mentioned design of the first thread, a satisfying size of the engagement portion, and hence intended associated contact area between the engagement portion of the trailing flank with the corresponding flank of the thread of the filter housing, when a pressure is applied from the leading end to the trailing end, may be achieved. By arranging the first thread with a steepness of the engagement portion of the trailing flank which is smaller than an average steepness of the leading flank, the first thread is an asymmetrical thread with regards to the leading and trailing flanks.

[0005] It should be understood that the engagement portion of the trailing flank is typically the portion of the trailing flank which is intended, by the design of the air filter cartridge, to provide a surface for engagement with a corresponding flank of the thread of the filter housing under operational load. The definition of the engagement portion is thus based on the geometry of the trailing flank itself, independently of the specific geometry of the thread of the filter housing. The engagement portion is typically the portion of the trailing flank which is shaped for enabling contact with the corresponding flank of the thread of the filter housing during operational load. This is e.g. in contrast to the portion of the trailing flank which is not shaped for such purposes, e.g. the portion closes to the root. The engagement portion may be flat or essentially flat. Alternatively, the engagement portion is slightly curved, and the steepness is referred to the average steepness of the engagement portion (i.e. the inclination with regards to the longitudinal axis is the average inclination of the engagement portion). Thus, the engagement portion is typically the portion of the trailing flank which is flat (or essentially flat) or slightly curved, and which is intended to, or is configured to, establish surface contact with the corresponding flank of the thread of the filterhousing (under operational load). Under operational load, when the engagement portion is brought into contact with a flat corresponding flank of the thread of the filter housing, it may undergo slight elastic or plastic deformation if it is not entirely flat, for example, if the engagement portion is essentially flat or slightly curved. In such cases, the resulting surface contact area is effectively equivalent to that which would be achieved by a flat engagement portion. Thus, despite minor deviations from flatness or perfect planarity such as protrusions or ripples (under the definition “essentially flat”) or convex or concave curvature (under the definition “slightly curved”), the engagement portion still ensures a high and reliable contact area under load conditions, functionally corresponding to that of a flat engagement portion. Stated differently, the engagement portion may be either flat or slightly non-flat, wherein the slightly non-flat engagement portion encompasses both the essentially flat and the slightly curved configurations.

[0006] Optionally in some examples, including in at least one preferred example, the engagement portion is flat or essentially flat. An essentially flat engagement portion may be defined by a maximum offset in relation to the average steepness of the trailing flank below Y mm, Y being e.g. 3% of the thread height. Thus, for a 1 mm thread height, Y is 0.03 mm. Alternatively, the essentially flat engagement portion is defined by a predefined maximum offset in relation to a straight line (chord or median line) connecting the root and crest along the trailing flank. Such straight line may be defined as a straight line following shortest distance between the root and crest along the trailing flank, or alternatively the shortest distance between the root region and the crest region (e.g. between the end of the root region to the beginning of crest region, as seen from the root to the crest). Such predefined maximum offset may be the previously mentioned Y mm. Thus, an “essentially flat” engagement portion may be defined by the described maximum offset Y mm. Such deviations may include, for example, minor surface irregularities such as protrusions or ripples or localized undulations extending at most Y mm from said straight line or from the average steepness of the trailing flank. In contrast, the engagement portion may be considered “flat” if this maximum offset is substantially negligible, far below Y mm. typically below 1% of the thread height (e.g. below 0.01 mm).

[0007] Optionally in some examples, including in at least one preferred example, the flat or essentially flat engagement portion may be defined with reference to the surface of the engagement portion. The surface may be regarded as “essentially flat” if its maximumdeviation from a reference plane spanning the engagement portion (from root or root region to crest or crest region, as previously described) does not exceed Z, where Z is preferably less than or equal to 3% of the thread height. For instance, with a thread height of 1 mm, a deviation of up to 0.03 mm may still fall within the definition of “essentially flat.” By contrast, a surface is considered “flat” if this deviation from the reference plane is substantially negligible, far below Y mm, typically below 1% of the thread height.

[0008] Stated differently, the term “flat” may refer to that the surface of the engagement portion is planar across its extension in the direction from root to crest, while “essentially flat” includes surfaces with minor deviations from perfect planarity, such as local irregularities or surface features such as protrusions, ripples, ribs, or similar microstructures, provided that such deviations do not materially significantly reduce the intended surface contact area under operational load. The use of “essentially flat” therefore allows for manufacturing tolerances or design adaptations that maintain functional equivalence to a flat engagement surface.

[0009] Optionally in some examples, including in at least one preferred example, the engagement portion is slightly curved. Thus, as an alternative to an essentially flat engagement portion, which deviates only slightly from a flat configuration, the engagement portion may instead be slightly curved, representing another controlled deviation from an ideal flat surface. The slightly curved engagement portion may be either convex or concave, including configurations that follow a smoothly curved profile or a polygonal form approximating such curvature. A slightly curved engagement portion may have an average inclination defined as the angle formed between a straight line (chord or median line) connecting the root and crest along the trailing flank, and the longitudinal axis. As previously described, such straight line may be defined as a straight line following shortest distance between the root and crest along the trailing flank, or alternatively the shortest distance between the root region and the crest region (e.g. between the end of the root region to the beginning of crest region, as seen from the root to the crest). The average inclination of such slightly curved engagement portion corresponds to the previously referred-to steepness or inclination of the engagement portion and may thus be between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis. In certain embodiments, the engagement portion may be slightly curved with a maximum deviation from the chord, or median line, not exceeding a threshold value of Xmm, X being e.g. 3% of the thread height. Thus, for a 1 mm thread height, X is 0.03 mm. In this way, the slightly curved engagement portion is still shaped to provide a sufficient and reliable contact area with the corresponding flank of the thread of the filter housing, particularly under operational load. In contrast, the engagement portion may be considered “non-curved” if this maximum offset is substantially negligible, far below X mm. typically below 1% of the thread height (e.g. below 0.01 mm).

[0010] Optionally in some examples, including in at least one preferred example, the slightly curved engagement portion may be defined with reference to the surface of the engagement portion. The surface may be regarded as “slightly curved” if its maximum deviation from a reference plane spanning the engagement portion (from root or root region to crest or crest region, as previously described) does not exceed T, where T is preferably less than or equal to 3% of the thread height. For instance, with a thread height of 1 mm, a deviation of up to 0.03 mm may still fall within the definition of “slightly curved”. By contrast, a surface is considered “non-curved” if this deviation is substantially negligible, far below X mm, typically below 1% of the thread height.

[0011] Stated differently, the term “slightly curved” includes slightly curved surfaces with minor deviations from perfect planarity, provided that such deviations do not materially significantly reduce the intended surface contact area under operational load. The use of “slightly curved” therefore allows for manufacturing tolerances or design adaptations that maintain functional equivalence to a flat engagement surface.

[0012] Thus, engagement portions with identical average inclination (measured as the inclination of a chord between root and crest as previously described) may differ in shape, such as being flat, essentially flat or slightly curved (e.g., concave). These shape variations may result from design features or manufacturing tolerances, while still yielding comparable average inclination values.

[0013] For the purposes of this disclosure, the term “average inclination” of the engagement portion refers to a representative angle formed between a reference line and the longitudinal axis. In the simplest embodiment, this average inclination is defined as the angle formed by a straight line (chord or median line) connecting the root and the crest (or their respective regions) of the engagement portion of the trailing flank, relative to the longitudinal axis. This definition applies regardless of whether the engagement portion is flat, essentially flat, or slightly curved.

[0014] For example, assume the engagement portion extends from a root point located 1.0 mm radially inward and 0.8 mm axially backward of a crest point located at a reference position (i.e. 0 mm radially and 0.0 mm axially). The chord may thus span a vertical (radial) difference of 1.0 mm and an axial difference of 0.8 mm. The average inclination 9 is then calculated as:9 = arctangent (1.0 / 0.8) ~ 51.3°This representative inclination corresponds to the angle P, and may be used to characterize the engagement portion regardless of local curvature or irregularities.

[0015] Optionally in some examples, including in at least one preferred example, the steepness the engagement portion (of the flat, or essentially flat, or slightly curved) is defined as the average steepness for the chord or median line connecting the root and crest along the trailing flank (e.g. shortest distance between root and crest), and the longitudinal axis.

[0016] In the context of this disclosure, the term “average steepness” of a flank refers to a representative inclination value for the entire flank or a defined portion thereof. This average may be determined, for example, by the angle formed between a straight line (chord or median line) connecting the root and the crest (or their respective regions) of the flank and the longitudinal axis, analogous to the definition of average inclination. The average steepness serves to characterize the general orientation of a flank for comparison purposes, such as when determining whether the engagement portion of the trailing flank is steeper or less steep than the leading flank. In contrast, the term “steepness” may refer to the local angle of inclination of a flank portion, such as the leading flank or trailing flank, relative to the longitudinal axis of the threaded arrangement. The steepness may vary along the height of the flank, particularly in the case of non-flat or curved geometries.

[0017] In addition to the definitions previously provided, an engagement portion may also be regarded as “essentially flat” if it comprises a combination of angled, slightly curved, or polygonal segments, provided that such a surface, when brought into contact with a flat reference surface (as e.g. the corresponding flank of the thread of the filter housing) under operational load, results in distributed surface contact (as opposed to isolated point loads), and the cumulative width of contact bands or regions exceeds a defined threshold, preferably more than 65% of the distance from root to crest along the trailing flank. This definition includes surfaces where intentional design features, such as multi-angled facets, engineered ripples, or shallow curved segments, have been introduced, as long as the overall surfacecontact remains functionally equivalent to that of a flat engagement portion under load. In such cases, the contact area may be evaluated using a test surface (e.g., a planar comparator surface) and accounting for load-induced deformation. The “average inclination” of such surfaces may alternatively be defined as the mean angle of all contacting segments or subsurfaces, measured in relation to the longitudinal axis, when engaged against a flat reference surface. The average inclination in this context may be measured as the mean inclination of the contacting portions of the engagement surface when brought into contact with a flat planar surface under load. This alternative definition ensures that the measured inclination reflects the functional behavior of the engagement portion, rather than idealized geometry alone, and supports a robust distinction between flat, essentially flat, and curved configurations.

[0018] Optionally in some examples, including in at least one preferred example, the engagement portion is inclined between 45° and 57°, preferably between 45° and 55°, more preferably between 46° and 50° or between 46° and 48° with regards to the longitudinal axis. A technical benefit may include further improved force distribution with regards to shear forces previously described.

[0019] Optionally in some examples, including in at least one preferred example, the root is defined as the first 10 % of the thread height and the crest is defined as the last 10 % of the thread height, wherein the trailing flank is defined to extend from the root to the crest along 80 % of the thread height. A technical benefit may include a satisfying size of the engagement portion and associated intended contact area between the engagement portion of the trailing flank with the corresponding flank of the thread of the filter housing, when a pressure is applied from the leading end to the trailing end. The thread height may e.g. be defined as height of the thread from the root to the crest. For example, the thread height may be defined as the distance, such as the largest distance, from the root to the crest. For example, the root, or root region, may make up the first 10 % of the thread height, typically from the lowest position of the root and extending 10 % along the thread in a direction of the thread height. Correspondingly, the crest, or crest region, may make up the last 10 % of the thread height, typically the last 10 % of the thread up to the highest position of the crest in a direction of the thread height. However, according to one alternative example, including in at least one preferred example, the trailing flank is defined to extend from the root to the crest along at least 80 %, such as along at least 90 %, such as along at least 95 % of the threadheight. The direction of the thread height may be defined as being perpendicular, or orthogonal, to the longitudinal axis. For example, for a cross-section of the threaded arrangement along the longitudinal axis, the longitudinal axis may be defined as the y-axis in a two-dimensional Cartesian coordinate system, and the thread height to extend along the x- axis of the two-dimensional Cartesian coordinate system, wherein the y-axis and x-axis are orthogonal.

[0020] Optionally in some examples, including in at least one preferred example, a midpoint of the crest is arranged off-set from a position at 0.5 pitch by at least 0.05 pitch, preferably by at least 0.10 pitch. A technical benefit may include an advantageous asymmetrical structure of the first thread. The pitch may be defined as the distance from two adjacent crests or two adjacent roots, e.g. between corresponding locations of the two adjacent crests or adjacent roots. The position of the mid-point of the crest relative to the pitch may be defined with regards to a pitch extending from corresponding mid-points of the two roots surrounding the crest. Thus, a mid-point of the crest at a position at 0.5 pitch with regards to a pitch extending from corresponding mid-points of the two roots surrounding the crest corresponds to a symmetrically positioned crest (i.e. a crest which is symmetrical at least with regards to the position of said mid-point. By arranging the mid-point of the crest off-set with regards to the position at 0.5 pitch (i.e. for a pitch extending from corresponding mid-points of the two roots surrounding the crest correspond to a symmetrical crest), an asymmetrical structure for the first thread is achieved which facilitates the structure of having a less steep trailing flank compared to the average steepness of the leading flank. Optionally in some examples, including in at least one preferred example, a mid-point of the crest is arranged off-set from a position at 0.5 pitch by at least 0.15 pitch, preferably by at least 0.20 pitch.

[0021] Optionally in some examples, including in at least one preferred example, the engagement portion of the trailing flank has an axial extension of at least 0.30 pitch, preferably at least 0.35 pitch, more preferably at least 0.40 pitch. A technical benefit may include a satisfying size of the engagement portion and associated intended contact area between the engagement portion of the trailing flank with the corresponding flank of the thread of the filter housing, when a pressure is applied from the leading end to the trailing end. The axial extension is typically defined as extending along the longitudinal axis.

[0022] Optionally in some examples, including in at least one preferred example, the root and / or the crest are pointy. Optionally in some examples, including in at least one preferred example, the root and / or the crest are flat, or are “topped of’. For example, the crest may have an axial extension of at least 0.10 pitch, e.g. about 0.15 pitch and / or the root may have an axial extension of at least 0.15 pitch, e.g. about 0.30 pitch. Additionally or alternatively, the trailing flank may have an axial extension which is greater than an axial extension of the leading end, e.g. by at least 0.10 pitch.

[0023] Optionally in some examples, including in at least one preferred example, the leading flank has a first axial extension, the trailing flank has a second axial extension, the crest has a third axial extension and the root has a fourth axial extension, wherein the sum of the first, second, third and fourth axial extensions is equal to the pitch. As previously described, the pitch may be defined as the axial distance between two adjacent crests or two adjacent roots.

[0024] Optionally in some examples, including in at least one preferred example, the second axial extension is larger than the first axial extension. A technical benefit may include an advantageous structure for providing an engagement portion of the trailing flank which is less steep compared to the average steepness of the leading flank with regards to the longitudinal axis. Thus, as the axial extension of the trailing flank is greater than the axial extension of the leading flank, the engagement portion of the trailing flank is more easily made less steep than the average steepness of the leading flank with regards to the longitudinal axis. Optionally in some examples, including in at least one preferred example, the average steepness of the trailing flank is smaller than the average steepness of the leading flank. Stated differently, the steeper leading flank may have an axial extension which is smaller than the less steep trailing flank.

[0025] Optionally in some examples, including in at least one preferred example, the sum of the first axial extension, half of the third axial extension and half of the fourth axial extension is smaller than 0.5 pitch, preferably smaller than 0.45 pitch or smaller than 0.35 pitch and the sum of the second axial extension, half of the third axial extension and half of the fourth axial extension is larger than 0.5 pitch, preferably larger than 0.55 pitch or larger than 0.65 pitch. A technical benefit may include an advantageous distribution of the axial extension (with regards to the pitch) between the trailing flank and the leading flank. Hereby, an advantageous structure for providing an engagement portion of the trailing flank which isless steep compared to the average steepness of the leading flank with regards to the longitudinal axis may be achieved.

[0026] Optionally in some examples, including in at least one preferred example, the third axial extension is equal to or smaller than 0.25 pitch, preferably equal to or smaller than 0.15 pitch, and / or the fourth axial extension is equal to or smaller than 0.20 pitch, preferably equal to or smaller than 0.15 pitch. A technical benefit may include a well distributed axial extension between the trailing and leading flanks on one hand, and the axial extension of the crest and / or root on the other hand. In general, the crest may be referred to as the crest region and the root may be referred to as the root region.

[0027] Optionally in some examples, including in at least one preferred example, the average steepness of the leading flank is between 6° and 45°, preferably between 13° and 42°, more preferably between 20° and 39° steeper than the engagement portion of the trailing flank. A technical benefit may include further improved force distribution with regards to shear forces as previously described. For example, the average steepness of the leading flank is between 27° and 33° steeper than the engagement portion of the trailing flank. The comparison between the leading flank and the engagement portion of the trailing flank may here be referring to the average steepness of the engagement portion.

[0028] Optionally in some examples, including in at least one preferred example, the leading flank extends from a first crest to a first root, and the trailing flank extends from the first crest to a second root trailing the first root in the axial direction, wherein the average steepness of the leading flank is determined from the first crest to the first root. Each one of the first crest and of the first and second roots may be defined as previously described.

[0029] Optionally in some examples, including in at least one preferred example, the average steepness of the leading flank is between 63° and 87°, preferably between 67° and 85°, more preferably between 71° and 81° with regards to the longitudinal axis. A technical benefit may include further improved force distribution with regards to shear as previously described. For example, the average steepness of the leading flank is between 75° and 79° with regards to the longitudinal axis. Optionally in some examples, including in at least one preferred example, the average steepness of the leading flank is between 63° and 79°, preferably between 67° and 79°, more preferably between 71° and 79°.

[0030] Optionally in some examples, including in at least one preferred example, the engagement portion is inclined between 42° and 57° and the average steepness of the leadingflank is between 63° and 87°, preferably the engagement portion is inclined between 43° and 54° and the average steepness of the leading flank is between 67° and 85°, more preferably the engagement portion is inclined between 45° and 51° and the average steepness of the leading flank is between 71° and 81°, with regards to the longitudinal axis. For example, the engagement portion is inclined between 46° and 48° or 50° and the average steepness of the leading flank is between 75° and 79°. Optionally in some examples, the engagement portion is inclined between 42° and 57° and the average steepness of the leading flank is between 63° and 79°, preferably the engagement portion is inclined between 43° and 54° and the average steepness of the leading flank is between 67° and 79°, more preferably the engagement portion is inclined between 45° and 51° and the average steepness of the leading flank is between 71° and 79°, with regards to the longitudinal axis. For example, the engagement portion is inclined between 46° and 48° or 50° and the average steepness of the leading flank is between 75° and 79°.

[0031] Optionally in some examples, including in at least one preferred example, the combined value of the inclination of the engagement portion of the trailing flank relative to the longitudinal axis and the inclination, or average inclination, of the leading flank relative to the longitudinal axis may be between 120° and 129°, preferably between 121° and 128° and more preferably between 122° and 126°, such as e.g. between 123° and 125°.

[0032] Optionally in some examples, including in at least one preferred example, the combined axial distance of the trailing flank and the leading flank (and optionally the crest and / or the root) is predetermined, and fixed, regardless of the steepness of the engagement portion and the average steepness of the leading flank.

[0033] Optionally in some examples, including in at least one preferred example, the engagement portion of the trailing flank forms an engagement surface for a corresponding flank of the thread of the filter housing. Thus, the corresponding flank of the thread of the filter housing is a corresponding flank to the trailing flank. The engagement surface may e.g. extend along the whole engagement portion. According to one example, the engagement portion makes up the whole trailing flank. The engagement surface may thus correspond to the previously described surface of the “flat”, “essentially flat” and “slightly curved” engagement portion.

[0034] Optionally in some examples, including in at least one preferred example, the engagement surface of the trailing flank is configured to be brought into contact with thecorresponding flank of the thread of the filter housing when the air filter cartridge is subject to a pressure in a direction from the leading end to the trailing end. Thus, the previously described engagement surface may be brought into contact with a corresponding surface of the thread of the filter housing upon a pressure in a direction from the leading end to the trailing end. Thus, the pressure is applied in an opposite direction to the direction leading the connection.

[0035] Optionally in some examples, including in at least one preferred example, the threaded arrangement is a multi-screw thread arrangement further comprising a second thread extending helically along the longitudinal axis from the leading end to the trailing end offset compared to the first thread, and wherein the second thread is correspondingly shaped to the first thread, or is shaped differently to the first thread. A technical benefit may include improved positioning of the air filter cartridge relative to the filter housing, e.g. resulting in a facilitated assembly process. The second thread may be offset relative to the first thread by a predefined value, e.g. by 180°. Thus, the start of the first and second threads may be offset by a correspondingly predefined value, e.g. by 180°. Hereby, the correct position for assembling the air filter cartridge to the filter housing may be improved (e.g. be made easier and / or faster). Hence, the assembly process may be enhanced with respect to time efficiency and user-friendliness.

[0036] Optionally in some examples, including in at least one preferred example, the second thread comprises a crest, a root, a pitch, a thread height extending in the direction from the root to the crest, a leading flank facing the leading end for leading the connection and having a contacting portion, and a trailing flank facing the trailing end, wherein a steepness of the contacting portion of the leading flank with regards to the longitudinal axis is smaller than an average steepness of the trailing flank with regards to the longitudinal axis, the contacting portion extending along at least 65 % of the thread height and being inclined between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis. Effects and features related to the second thread of the threaded arrangement are largely analogous to those described above in connection with the first thread, but for an applied pressure in the opposite direction to that described with reference to the first thread (i.e. for an applied pressure from the trailing end to the leading end). Hereby, the threaded arrangement is particularly suited for connection to low pressure vessels, e.g. with pressure variations, such as certain low pressure air filters and oil filter,Thus, for embodiments mentioned in relation to the first thread and with regards to the trailing flank, corresponding embodiments apply for the leading flank of the second thread, for embodiments mentioned in relation to the first thread and with regards to the leading flank, corresponding embodiments apply for the trailing flank of the second thread, and for embodiments mentioned in relation to the first thread and with regards to the engagement portion, corresponding embodiments apply for the contacting portion of the second thread. Thus, the contacting portion may be flat, essentially flat, slightly curved, with a corresponding definition as the flat, essentially flat or slightly curved engagement portion.

[0037] It should be noted that the engagement portion is defined as a portion of the trailing flank. Moreover, the trailing flank is defined as a portion of the first thread, which extends helically along a longitudinal axis from the leading end to the trailing end, with the trailing flank facing the trailing end. In this context, the trailing flank and its engagement portion, inherently extends in at least two orthogonal directions: (i) in the longitudinal direction (i.e., along the longitudinal axis), following the helical path of the thread, and (ii) in the direction perpendicular, or orthogonal, to the longitudinal axis, specifically in the direction from the root to the crest, which is referred to as the "thread height.". In other words, the trailing flank and its engagement portion, inherently has at least two components, a first component in the longitudinal direction (i.e., along the longitudinal axis), following the helical path of the thread, and a second component in the direction perpendicular, or orthogonal, to the longitudinal axis, specifically in the direction from the root to the crest, which is referred to as the "thread height." Thus, in the context of the present disclosure, when it is stated that the engagement portion extends along at least 65% of the thread height, this is to be understood as referring to the extension, or component, of the engagement portion in the direction from the root to the crest, i.e., in the direction of the thread height. The specified percentage of extension (at least 65%) pertains to the extension, or component, of the engagement portion that extends in the direction of the thread height. Given that the trailing flank, and hence the engagement portion, forms part of a helically extending thread, it necessarily has extensions in both the axial (longitudinal) direction and the radial (height) direction. The stated proportion of at least 65% thus relates to the extension of the engagement portion along the thread height. For example, for a cross-section of the threaded arrangement along the longitudinal axis, and the previously described two-dimensional Cartesian coordinate system, the component of the engagement portion in the direction fromthe root to the crest, i.e., in the direction of the thread height is along the x-axis, and the component of the engagement portion in the direction of the longitudinal axis is along the y- axis.

[0038] It should be noted that the thread height refers to the distance between the root and the crest of the thread, measured in a direction normal (i.e., perpendicular) to the longitudinal axis of the threaded arrangement. In other words, the thread height extends radially outward from the root to the crest, not along the axial (longitudinal) direction of the thread.

[0039] According to a second aspect of the disclosure, an air filter system comprising a filter housing and an air filter cartridge according to the first aspect of the disclosure is provided. The second aspect of the disclosure may seek to solve the same problem as described for the first aspect of the disclosure. Thus, effects and features of the second aspect of the disclosure are largely analogous to those described above in connection with the first aspect of the disclosure. The filter housing is typically an air filter housing. Thus, the filter housing comprises a corresponding first thread configured to threadingly engage with the first thread of the air filter cartridge, and optionally a corresponding second thread configured to threadingly engage with the second thread of the air filter cartridge. Thus, the filter housing may comprise a single-screw threaded arrangement configured to threadingly engage with the single-screw threaded arrangement of the air filter cartridge, or the filter housing may comprise a multi-screw thread arrangement configured to threadingly engage with the multiscrew thread arrangement of the air filter cartridge. As mentioned with reference to the first aspect, the first thread of the filter housing comprises a flank for being brought into contact with the engagement portion of the trailing flank during the operational load. Such flank may be referred to as an engagement flank, wherein the engagement flank is configured to be brought into contact with the engagement portion of the trailing flank of the air filter cartridge.

[0040] Optionally in some examples, including in at least one preferred example, a play of 0.001 to 0.1 pitch is present at least between the first thread of the air filter cartridge and the thread of the filter housing. For example, the play my be present between the corresponding root and crest pair of the first thread of the air filter cartridge and the thread of the filter housing. It should be understood that when a pressure is applied from the leading end towards the trailing end, there is typically no play between the engagement portion of thetrailing end of the air filter cartridge and the corresponding flank of the thread of the filter housing.

[0041] According to a third aspect of the disclosure, a filter housing is provided. The filter housing comprises a threaded arrangement for connection with a thread of an air filter cartridge, the threaded arrangement having a first end, a second end opposite to the first end and at least a first thread extending helically along a longitudinal axis from the first end to the second end, the first thread having a crest, a root, a pitch, a thread height extending in the direction from the root to the crest, a first flank facing the first end, and a second flank facing the second end and having a housing thread engagement portion, wherein a steepness of the housing thread engagement portion of the second flank with regards to the longitudinal axis is smaller than an average steepness of the first flank with regards to the longitudinal axis, the housing thread engagement portion extending along at least 65 % of the thread height and being inclined between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis. The third aspect of the disclosure may seek to solve the same problem as described for the first and second aspects of the disclosure. Thus, effects and features of the third aspect of the disclosure are largely analogous to those described above in connection with the first and second aspects of the disclosure. The filter housing of the third aspect may be that included in the air filter system of the second aspect of the disclosure. However, according to at least one example, the filter housing may threadingly engage with an air filter cartridge different to that of the first aspect of the disclosure. Such air filter cartridge should be at least compatible with the filter housing of the third aspect of the disclosure. By being compatible, at least the first thread of the threaded arrangement of the air filter cartridge is able to threadingly engage with the first thread of the threaded arrangement of the filter housing, e.g. by that, in use or during operational load, at least 65 % of the trailing flank, or of the engagement portion thereof, of the first thread of the threaded arrangement of the air filter cartridge is in contact with at least 65 % of the housing thread engagement portion of the second flank.

[0042] According to a fourth aspect of the disclosure, a vehicle comprising the air filter system of any the second aspect of the disclosure, or an air filter cartridge of the first aspect of the disclosure is provided. The fourth aspect of the disclosure may seek to solve the same problem as described for the first to third aspects of the disclosure. Thus, effects and featuresof the fourth aspect of the disclosure are largely analogous to those described above in connection with the first to third aspects of the disclosure.

[0043] According to a fifth aspect of the disclosure, use of an air filter cartridge in a filter housing is provided. The air filter cartridge comprises a filter body and a threaded arrangement for connection with a first thread of the filter housing, the threaded arrangement having a leading end, a trailing end opposite to the leading end and at least a first thread extending helically along a longitudinal axis from the leading end to the trailing end, the first thread having a crest, a root, a pitch, a thread height extending in the direction from the root to the crest, a leading flank facing the leading end for leading the connection, and a trailing flank facing the trailing end and having an engagement portion, wherein a steepness of the engagement portion of the trailing flank with regards to the longitudinal axis is smaller than an average steepness of the leading flank with regards to the longitudinal axis, the engagement portion extending along at least 65 % of the thread height and being inclined between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis. The fifth aspect of the disclosure may seek to solve the same problem as described for the first to fourth aspects of the disclosure. Thus, effects and features of the fifth aspect of the disclosure are largely analogous to those described above in connection with the first to fourth aspects of the disclosure, of which some embodiments are mentioned below typically without repeating the associated technical effect. The air filter cartridge may be that of the first aspect of the disclosure. The filter housing may be that of the third aspect, and the air filter cartridge and filter housing may be those of the air filter system of the second aspect of the disclosure. Thus, any of the examples and embodiments mentioned with regards to the air filter cartridge and / or the filter housing applies to the fifth aspect of the disclosure.

[0044] Optionally in some examples, including in at least one preferred example, the first thread of the filter housing is threadingly engaging with the first thread of the air filter cartridge.

[0045] Optionally in some examples, including in at least one preferred example, the first thread of the filter housing comprises an engagement flank which is configured to be brought into contact with the engagement portion of the trailing flank of the air filter cartridge.

[0046] Optionally in some examples, including in at least one preferred example, when the air filter cartridge is subject to a pressure acting from the leading end toward the trailingend, the engagement portion of the trailing flank is brought into contact with the engagement flank of the first thread of the filter housing to provide sealing.

[0047] Optionally in some examples, including in at least one preferred example, the engagement flank is flat and inclined between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis.

[0048] Optionally in some examples, including in at least one preferred example, the engagement portion of the trailing flank is flat and inclined between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis.

[0049] Optionally in some examples, including in at least one preferred example, when the air filter cartridge is subject to a pressure acting from the leading end toward the trailing end the contact between the engagement flank and the flat, or essentially flat, or slightly curved engagement portion of the trailing flank is spanning along at least 65 % of the thread height.

[0050] According to a sixth aspect of the disclosure, use of an air filter cartridge in a filter housing is provided. The filter housing comprises a threaded arrangement for connection with a thread of the air filter cartridge, the threaded arrangement having a first end, a second end opposite to the first end and at least a first thread extending helically along a longitudinal axis from the first end to the second end, the first thread having a crest, a root, a pitch, a thread height extending in the direction from the root to the crest, a first flank facing the first end, and a second flank facing the second end and having a housing thread engagement portion, wherein a steepness of the housing thread engagement portion of the second flank with regards to the longitudinal axis is smaller than an average steepness of the first flank with regards to the longitudinal axis, the housing thread engagement portion extending along at least 65 % of the thread height and being inclined between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis. The sixth aspect of the disclosure may seek to solve the same problem as described for the first to fifth aspects of the disclosure. Thus, effects and features of the sixth aspect of the disclosure are largely analogous to those described above in connection with the first to fifth aspects of the disclosure, of which some embodiments are mentioned below typically without repeating the associated technical effect. The air filter cartridge may be that of the first aspect of thedisclosure. The filter housing may be that of the third aspect, and the air filter cartridge and filter housing may be those of the air filter system of the second aspect of the disclosure.

[0051] Optionally in some examples, including in at least one preferred example, the air filter cartridge is compatible with the filter housing. By being compatible, at least the first thread of the threaded arrangement of the air filter cartridge is able to threadingly engage with the first thread of the threaded arrangement of the filter housing, e.g. by that, in use or during operational load, at least 65 % of the trailing flank (or of the engagement portion thereof) of the first thread of the threaded arrangement of the air filter cartridge is in contact with at least 65 % of the housing thread engagement portion of the second flank of the threaded arrangement of the filter housing.

[0052] Optionally in some examples, including in at least one preferred example, the first thread of the filter housing is threadingly engaging with the first thread of the air filter cartridge.

[0053] Optionally in some examples, including in at least one preferred example, the second flank is an engagement flank configured to be brought into contact with an engagement portion of a trailing flank of a threaded arrangement of the air filter cartridge.

[0054] Optionally in some examples, including in at least one preferred example, when the air filter cartridge is subject to a pressure acting from the second end toward the first end, the engagement portion of the trailing flank is brought into contact with the engagement flank of the first thread of the filter housing to provide sealing.

[0055] Optionally in some examples, including in at least one preferred example, the housing thread engagement portion of the second flank is flat, or essentially flat.

[0056] According to a seventh aspect of the disclosure, any of the first to sixth aspects of the disclosures are provided for a filter cartridge, including but not limited to, an air filter cartridge. Thus, for any of the first to sixth aspect of the disclosure, the feature “air filter cartridge” may be exchanged with the feature “filter cartridge”. For example, the filter cartridge may be an oil filter cartridge. For example, the filter cartridge and / or the filter housing of the seventh aspect may be particularly suited for connection to low pressure vessels, e.g. with pressure variations, such as certain low pressure air filters and oil filters.

[0057] The disclosed aspects, examples (including any preferred examples), and / or accompanying claims may be suitably combined with each other as would be apparent to anyone of ordinary skill in the art. Additional features and advantages are disclosed in thefollowing description, claims, and drawings, and in part will be readily apparent therefrom to those skilled in the art or recognized by practicing the disclosure as described herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Examples are described in more detail below with reference to the appended drawings.

[0059] FIG. 1 is an exemplary, partly schematic, side view of a vehicle comprising an air filter system according to one example.

[0060] FIG. 2 is an exemplary, partly schematic, side view of the air filter system comprising an air filter cartridge and a filter housing of Fig. 1 according to one example.

[0061] FIG. 3 is a cross-sectional view of a portion of threaded arrangements of the air filter cartridge and filter housing according to one example.

[0062] FIG. 4 is a cross-sectional view of a portion of threaded arrangements of the air filter cartridge and filter housing according to one example.

[0063] FIG. 5 is an exemplary, partly schematic, perspective view of a threaded arrangement of the air filter cartridge according to one example.

[0064] FIG. 6 are cross-sectional views of portions of threaded arrangements of the air filter cartridge and filter housing according to one example.

[0065] FIG. 7 are cross-sectional views of different examples of the threaded arrangement of the air filter cartridge.

[0066] FIG. 8 is a cross-sectional view of an example of the threaded arrangement of the air filter cartridge.

[0067] FIG. 9 is a cross-sectional view of an example of the threaded arrangement of the air filter cartridge.

[0068] FIG. 10 is a cross-sectional view of an example of the threaded arrangement of the air filter cartridge.

[0069] FIG. 11 is a cross-sectional view of an example of the threaded arrangement of the air filter cartridge.DETAILED DESCRIPTION

[0070] The detailed description set forth below provides information and examples of the disclosed technology with sufficient detail to enable those skilled in the art to practice the disclosure.

[0071] The disclosed technology may solve the problem related to unintentional detachment of the air filter cartridge from the filter housing. The disclosed technology provides an improved threaded arrangement in which the first thread is arranged to provide a well-balanced distribution of at least the radial force of the shear forces on one hand, and the size of the engagement portion, and intended associated contact area between the engagement portion and the thread of the filter housing, on the other hand. Typically, the threaded arrangement provides an engagement portion which is large enough for providing a strong thread, or at least a thread that does not prematurely break or prematurely wear out, and which provides a sufficient sealing between the filter housing and air filter cartridge. In other words, the combination of having an engagement portion of the trailing flank which is less steep than the average steepness of the leading flank, and wherein the engagement portion is inclined by between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis, a threaded arrangement which achieves a well-balanced distribution with regards to at least the radial force of the shear forces on one hand (and associated induced shear forces), and the potential contact area between the engagement portion and the thread of the filter housing on the other hand, may be provided. A technical benefit may include improved balance between the radial force of the shear forces and the size of the engagement portion (and associated resulting contact area between the engagement portion and the thread of the filter housing). Another technical benefit may include reduced wear of the threaded arrangement. Another technical benefit may include a tight sealing at the trailing flank when the air filter cartridge is subject to a pressure from the leading end to the trailing end.

[0072] FIG. 1 is an exemplary vehicle 1000, here embodied as a heavy duty truck 1000, according to one example. The vehicle 1000 comprises an internal combustion engine 1010, such as e.g. a hydrogen combustion engine or a diesel combustion engine, for propelling the vehicle 1000, and an air filter system 1001 for filtrating air. The air filter system 1001 comprises a filter housing 1003 and an air filter cartridge 1002. Typically, the air filter cartridge 1002 comprises an air filter that has to be changed during maintenance operations,and thus, the air filter cartridge 1002 is removably attached to the filter housing 1003 by corresponding threaded arrangements. The air filter system 1001 is only schematically shown in Fig. 1. It should be mentioned that the vehicle 1000 may be a hybrid vehicle further comprising an electric traction machine (optionally) for propelling the vehicle 1000. The internal combustion engine 1010 and the optional electric traction machine are typically arranged and configured to individually propel the vehicle 1000 by being separately coupled to other parts of the powertrain of the vehicle 1000, such as a transmission, drive shafts and wheels (not shown in detail). The operation of the internal combustion engine 1010 and the optional electric traction machine may be controlled by a control unit 1117, such as an ECU.

[0073] In FIG. 2, the air filter system 1001 comprising the filter housing 1003 and the air filter cartridge 1002 is shown in greater detail. The air filter cartridge 1002 comprises a filter body 1002a and a threaded arrangement 1 for connection with a corresponding threaded arrangement 1’ of the filter housing 1003. The filter body 1002a typically comprises a disposable air filter. The threaded arrangement 1 of air filter cartridge 1002 is configured to be threaded onto the threaded arrangement 1’ of the filter housing 1003 following a longitudinal axis A, here also being a screwing axis. As also shown in Fig. 2, a pressure P (such as a prolonged internal pressure or overpressure), or any other corresponding ripping out forces, can be applied to the air filter cartridge 1002, resulting in a force directed inwardly from the filter housing 1003 towards the air filter cartridge 1002, risking the air filter cartridge 1002 to be ripped out and detached from the filter housing 1003.

[0074] In FIG. 3, a cross-sectional view of a portion of the threaded arrangement 1 of air filter cartridge 1002 and the threaded arrangement 1’ of the filter housing 1003 are shown. The two threaded arrangements 1, 1’ are shown separated from each other for increased comprehensibility.

[0075] The threaded arrangement 1 extends from a leading end la to a trailing end lb arranged opposite to the leading end la. The threaded arrangement 1 comprises a first thread 10 extending helically along the longitudinal axis A from the leading end la to the trailing end lb. The first thread 10 is configured to threadingly engage with a corresponding thread 20 (e.g. a corresponding first thread 20) of the threaded arrangement 1 ’ of the filter housing 1003.

[0076] As shown in Fig. 3, the first thread 10 of the threaded arrangement 1 of the air filter cartridge 1002 is built up by structure including a crest 11, a root 12, a pitch p, a threadheight H extending in the direction from the root 12 to the crest 11, a leading flank 13 facing the leading end la for leading the connection of the air filter cartridge 1002 to the filter housing 1003, and a trailing flank 14 facing the trailing end lb. The trailing end has a flat engagement portion 14’, which will be described in more detail later. In more detail, the first thread 10 comprises a first crest I la, a first root 12a, a second crest 1 lb being adjacent the first crest I la and trailing the first crest I la in the axial direction (i.e. being arranged closer to the trailing end lb as compared to the first crest I la, and along the longitudinal axis), and a second root 12b adjacent the first root 12a and trailing the first root 12a. Correspondingly, a first leading flank 13a extends from the first crest 1 la to the first root 12a, and a first trailing flank 14a extends from the first crest 1 la to the second root 12b. Thus, the leading flank 13 leads the insertion of the first thread 10 relative to the thread 20 of the filer housing 1003 when the air filter cartridge 1002 is screwed onto the filter housing 1003.

[0077] The first thread 10 may be built up by consecutive leading flanks 13 and trailing flanks 14 corresponding to the described first leading and trailing flanks 13a, 14a. For example, as shown in Fig. 3, a second leading flank 13b extends from the second root 12a to the second crest 1 lb. In the example of Fig. 3, the pitch p is extending from first crest I la to the second crest 1 lb. For simplicity, reference will be made to “the crest 11”, the “root 12”, “the leading flank 13” and “the trailing flank 14” in the following, indicating any one of, or all of, the corresponding crest 11, roots 12, leading flanks 13 and trailing flanks 14 of the thread 10, or at least indicating the first crest I la, the first root 12a, the first leading flank 13a and the first trailing flank 14a, respectively.

[0078] The root 12 may be referred to as a root region, and may e.g. be defined as the first 10 % of the thread height H. Correspondingly, the crest 11 may be referred to as a crest region, and may e.g. be defined as the last 10 % of the thread height H. Thus, the trailing flank 14 may be defined to extend from the root 12 to the crest 11 along 80 % of the thread height H. Correspondingly, the leading flank 13 may be defined to extend from the crest 11 to the root 12 along 80 % of the thread height H. As shown in Fig. 3, the crest 11 and the root 12 are pointy, with a minimum axial extension, but may be shaped differently, e.g. with associated flat portions extending along the longitudinal axis (as e.g. shown in Fig. 4). The crest and root may alternatively be slightly curved, or comprise slightly curved portions.

[0079] The pressure P described with reference to Fig. 2 is also shown in Fig. 3, indicated to extend in a direction from the leading end la to the trailing end lb, typically along thelongitudinal axis A (but opposite the direction of the threaded connection). When such pressure P is applied, the resulting force will bring the first thread 10 of the threaded arrangement 1 of the air filter cartridge 1002 into contact with the corresponding thread 20 of the threaded arrangement 1’ of the filter housing 1003. Hereby, the engagement portion 14’ of the trailing flank 14 will be brough into contact with a flank 24 of the thread 20 of the filter housing 1003 corresponding to that of the trailing flank 14. In more detail, the engagement portion 14’ of the trailing flank 14 forms an engagement surface 14a’ which will be brought into contact with the flank 24 of the filter housing 1003. Hereby, the threaded arrangements 1, 1’ will seal the air filter cartridge 1002 to the filter housing 1003. However, if the pressure P is too high, e.g. above a predetermined threshold value, the resulting force may cause the first thread 10 to be ripped out of the engagement with the thread 20 of the filter housing 1003, whereby the air filter cartridge 1002 is unintentionally detached from the filter housing 1003. Thus, the engagement portion 14’ configured to be in contact with the corresponding flank 24 of the filter housing 1003, is preferably large enough for providing a threaded engagement which is strong, to prevent the air filter cartridge 1002 from unintentionally detach from the filter housing 1003, and / or to prevent prematurely breakage or prematurely wearing out of the first thread 10, which also may result in unintentionally detachment of the air filter cartridge 1002 from the filter housing 1003.

[0080] Typically, resulting force of the applied pressure P to the air filter cartridge 1002 results in shear forces between the engagement portion 14’ and the corresponding flank 24 of the filter housing 1003. The shear forces can be divided into a component in the axial direction (i.e. along the longitudinal axis A also referred to as a vertical force) and a component traverse the axial direction (i.e. in the radial direction along the thread height H), the latter being referred to as a radial force. In order to provide a satisfying sealing between the air filter cartridge 1002 and the filter housing 1003, and to avoid unintentionally detachment of the air filter cartridge 1002 from the filter housing 1003 as previously described, and providing a tight sealing at the trailing flank when being subject to a pressure from the leading end to the trailing end, these force components should be balanced, or at least be adapted with regards to each other.

[0081] As seen in Fig. 3, the steepness of the flat engagement portion 14’ of the trailing flank 14 with regards to the longitudinal axis A is smaller than an average steepness of the leading flank 13 with regards to the longitudinal axis A. Hereby, and as the engagementportion 14’ extends along at least a majority of the trailing flank 14, here being defined as along at least 65 % of the thread height H, the first thread 10 is structured to provide a well- balanced distribution with regards to the shear forces (at least the radial force) and the contact area between the engagement portion 14’ with the flank 24 of the filter housing 1003. Thus, unintentional detachment of the air filter cartridge 1002 from the filter housing 1003, e.g. due to prematurely breakage or prematurely wearing out of the first thread 10, can be avoided or the risk thereof at least reduced. Moreover, an advantageous tight sealing at the trailing flank 14, owing to the contact between the engagement portion 14’ with the flank 24 of the filter housing 1103, when the air filter cartridge is subject to a pressure from the leading end la to the trailing end lb is achieved. The inventor(s) has / have realized that a suitable inclination p between the engagement portion 14’ of the trailing flank 14 and the longitudinal axis A is between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51°. For example, the inclination P may be at least 42°, or at least 44°, and not more than 50°, or not more than 52°. In the non-limiting example of Fig. 3, the flat engagement portion 14’ of the trailing flank 14 is approximately 48°.

[0082] The threaded arrangement 1’ of the filter housing 1003 is thus configured for connection with the thread 10 the air filter cartridge 1002. The threaded arrangement 1’ may be comprise a first end l’a, a second end l’b opposite to the first end l’a and at least the first thread 20 extending helically along the longitudinal axis A’ from the first end l’a to the second end l’b. When the air filter cartridge 1002 is threadingly engaging the filter housing 1003, as shown in Fig. 2, the two longitudinal axis A, A’ are coinciding and may simply be referred to as the longitudinal axis A. Correspondingly to the first thread 10 of the air filter cartridge 1002, the first thread 20 of the filter housing 1003 comprises a crest 11’, a root 12’, a pitch p’, a thread height H’ extending in the direction from the root 12’ to the crest 11’, a first flank 23 facing the first end l’a, and a second flank 24 facing the second end l’b and having a housing thread engagement portion 24’. The second flank 24 is thus the previously described “corresponding flank 24”. As shown in Fig. 11, a steepness of the housing thread engagement portion 24’ of the second flank 24 with regards to the longitudinal axis A’ is smaller than an average steepness of the first flank 23 with regards to the longitudinal axis A’. The housing thread engagement portion 24’ extends along at least 65 % of the thread height H and is inclined P’ between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis A’. It should be notedfor the air filter cartridge 1002 to threadingly engage with the first thread 20’ of the threaded arrangement 1’ of the filter housing 1003, the air filter cartridge should be compatible with the filter housing. This may e.g. be defined by, in use or during operational load, at least 65 % of the trailing flank, or of the engagement portion thereof, of the first thread of the threaded arrangement 1 of the air filter cartridge 1002 is in contact with at least 65 % of the housing thread engagement portion 24’ of the second flank 24.

[0083] Turning to FIG. 4, a cross-sectional view of a portion of an alternative threaded arrangement 101 of air filter cartridge 1002 and an alternative threaded arrangement 101’ of the filter housing 1003 are shown. The two threaded arrangements 101, 101’ are shown separated from each other for increased comprehensibility, and corresponds in large to the two threaded arrangements 1, 1’ of Fig. 3. Like reference numbers are used for like features, but with an additional value of “100” for each feature, i.e. “threaded arrangement 1” of Fig 3 relates to “threaded arrangement 101” of Fig. 4, etcetera.

[0084] The threaded arrangement 101 extends from a leading end 101a to a trailing end 101b and comprises a first thread 110 extending helically along the longitudinal axis A from the leading end 101a to the trailing end 101b. The first thread 110 is configured to threadingly engage with a corresponding thread 120 (e.g. a corresponding first thread 120) of the threaded arrangement 101’ of the filter housing 1003.

[0085] As shown in Fig. 4, the first thread 110 of the threaded arrangement 101 of the air filter cartridge 1002 is built up by structure including a crest 111, a root 112, a pitch p, a thread height H extending in the direction from the root 112 to the crest 111, a leading flank 113 facing the leading end 101a for leading the connection of the air filter cartridge 1002 to the filter housing 1003, and a trailing flank 114 facing the trailing end 101b, the trailing end having a flat engagement portion 114’, similar to that of the first thread 10 of the threaded arrangement 1 of Fig. 3, why it is not described in detail here again.

[0086] As shown in Fig. 4, the leading flank 113 has a first axial extension dl, the trailing flank 114 has a second axial extension d2, the crest 111, or crest region, has a third axial extension d3 and the root 112, or root region, has a fourth axial extension d4. Corresponding axial distances are included in Fig. 3 as well, but as previously described, the crest 11 and the root 12 are here pointy with a minimum axial extension for the third and fourth axial extensions d3, d4. The sum of the first, second, third and fourth axial extensions dl, d2, d3, d4 is equal to the pitch p. The third axial extension d3 may e.g. be equal to or smaller than0.25 pitch p, preferably equal to or smaller than 0.15 pitch p, and / or the fourth axial extension d4 may e.g. be equal to or smaller than 0.20 pitch p, preferably equal to or smaller than 0.15 pitch p. In the non-limiting example of Fig. 4, each one of the third and fourth axial extensions d3, d4 is approximately 0.13 pitch p. The third and fourth axial extensions d3, d4 may be equal, or may be different compared to each other.

[0087] Correspondingly to the first thread 10 of Fig. 3, and with regards to the pressure P in a direction form the leading end 101a to the trailing end 101b, the steepness of the flat engagement portion 114’ of the trailing flank 114 with regards to the longitudinal axis A of the first thread 110 of Fig. 4 is smaller than an average steepness of the leading flank 113 with regards to the longitudinal axis A. Hereby, as for the first thread 10 of Fig. 3, the engagement portion 114’ extends along at least a majority of the trailing flank 114, here being defined as along at least 65 % of the thread height H, the first thread 110 of Fig. 4 is structured to provide a well-balanced distribution with regards to the shear forces (e.g. the radial force) and the contact area between the engagement portion 114’ with the flank 124 of the filter housing 1003. Thus, unintentionally detachment of the air filter cartridge 1002 from the filter housing 1003, e.g. due to prematurely breakage or prematurely wearing out of the first thread 110, can be avoided or the risk thereof at least reduced. The inclination p between the flat engagement portion 114’ of the trailing flank 114 and the longitudinal axis A may be the same as for the example shown in Fig. 3, i.e. between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51°. In the non-limiting example of Fig. 4, the flat engagement portion 114’ of the trailing flank 114 is approximately 42°.

[0088] With reference to both Fig. 3 and Fig. 4, by arranging the first thread 10, 110 with a steepness of the engagement portion 14’, 114’ of the trailing flank 14, 114 which is smaller than an average steepness of the leading flank 13, 113, the first thread 10, 110 is asymmetrical. Thus, the first thread 10, 110 is different to a metric ISO standard thread. For example, the engagement portion 14’, 114’ of the trailing flank 14, 114 may have an axial extension of at least 0.30 pitch p, preferably at least 0.35 pitch p, more preferably at least 0.40 pitch p.

[0089] As shown in Fig. 4, the first thread 110 may be asymmetrically defined by other features than the steepness of the engagement portion 114’ relative to the average steepness of the leading flank 113. For example, a mid-point m of the crest 111 may be arranged off-set from a position at 0.5 pitch p by at least 0.05 pitch p, preferably by at least 0.10 pitch p. Theposition of the mid-point m of the crest 111 relative to the pitch p may e.g. be defined with regards to a pitch extending from corresponding mid-points of the two roots 112 surrounding the crest 111. Thus, with such definition, a mid-point of the crest at a position at 0.5 pitch would correspond to a symmetrical crest, at least with regards to the position of the mid-point thereof, which would be the case for a metric ISO standard thread. By arranging the midpoint m of the crest 111 off-set with regards to the position at 0.5 pitch p, an asymmetrically for the first thread 110 is achieved which facilitates the structure of having a less steep engagement portion 114’ of the trailing flank 114 compared to the average steepness of the leading flank 113. As shown in Fig. 4, the mid-point m of the crest 111 is offset relative to a position at 0.5 pitch p by approximately 0.20 pitch p.

[0090] As shown both in Fig. 3 and Fig. 4, the second axial extension d2 is larger than the first axial extension dl. Thus, the trailing flank 14, 114 extends along the longitudinal axis A for a larger distance as compared to the leading flank 13, 113. Hereby, an advantageous structure for providing a flat engagement portion 14’, 114’ of the trailing flank 14, 114 which is less steep compared to the average steepness of the leading flank 13, 113 with regards to the longitudinal axis A is achieved.

[0091] For example, the sum of the first axial extension dl, half of the third axial extension d3 and half of the fourth axial extension d4 is smaller than 0.5 pitch p, preferably smaller than 0.45 pitch p or smaller than 0.35 pitch p and the sum of the second axial extension d2, half of the third axial extension d3 and half of the fourth axial extension d4 is larger than 0.5 pitch p, preferably larger than 0.55 pitch p or larger than 0.65 pitch p. As shown in both Fig. 3 and Fig. 4, the second axial extension d2 is at least twice as large as the first axial extension dl, and as shown in Fig. 4, the second axial extension d2 may even be three times as large as the first axial extension dl.

[0092] With reference to both Fig. 3 and Fig. 4, the average steepness of the leading flank 13, 113 may be between 63° and 87°, preferably between 67° and 85°, more preferably between 71° and 81° with regards to the longitudinal axis A, indicated by the angle a. Stated differently, the average steepness of the leading flank 13, 113 may be between 6° and 45°, preferably between 13° and 42°, more preferably between 20° and 39° steeper than the flat engagement portion 14’, 114’ of the trailing flank 14, 114. In the non-limiting example of Fig. 3, the average steepness of the leading flank 13 is approximately 72°, and in the nonlimiting example of Fig. 4, the average steepness of the leading flank 113 is approximately70°. The average steepness of the leading flank 13, 113 is typically defined as the average inclination of the leading flank 13 relative to the longitudinal axis A, from the crest 11, 111 to the root 12, 112. For example, with reference to the first crest I la and the first root 12a of Fig. 3, the average steepness of the first leading flank 13a may be determined from the first crest 1 la to the first root 12a.

[0093] Turning to Fig. 5, showing an alternative example of a threaded arrangement 201 of the air filter cartridge 1002. Thus, the air filter cartridge 1002 may be provided with threaded arrangement 201 instead of the threaded arrangement 1 of Fig. 3, or the threaded arrangement 101 of Fig. 4. The threaded arrangement 201 is a multi-screw thread arrangement 201 comprising a first thread 210 and a second thread 230 extending helically along a longitudinal axis A from a leading end 201a to a trailing end 201b. The first thread 210 may correspond to, or be the same as, to the first thread 10 of the example in Fig. 3 or of the first thread 110 of the example in Fig. 4. The second thread 230 is arranged offset compared to the first thread 210. The second thread 230 may be offset relative to the first thread 210 by a predefined value, e.g. by 180°. Thus, the start 210a of the first and second thread 210 and the start 230a of the second thread 230 may be offset by a correspondingly predefined value, e.g. by 180° as shown in Fig. 5..

[0094] The second thread 230 may be correspondingly shaped to the first thread 210, or may be shaped differently to the first thread 210. Thus, the second thread 230 may extend from the leading end 201a to the trailing end 201b in a corresponding manner as the first thread 210. Thus, the first thread 210 and the second thread 230 may be correspondingly shaped.

[0095] In the case the second thread 230 is differently shaped compared to first thread 210, the second thread 230 may be provided with a similar threaded structure but with opposite features for the trailing and leading flanks. Such threaded structure is shown in FIG. 6, wherein a cross-sectional view of a portion of the threaded arrangement 201 comprising the first thread 210 and a threaded arrangement 201’ of the filter housing 1003 comprising a corresponding first thread 220 is shown to the left, and a cross-sectional view of a portion of the threaded arrangement 201 comprising the second thread 230 and the threaded arrangement 201’ comprising a corresponding second thread 240 is shown to the right. The first thread 210 of the threaded arrangement 201 is configured to threadingly engage with the first thread 220 of the filter housing 1003 in a corresponding manner as described withreference to Fig. 3 and Fig. 4, and is thus not described in detail here again. Thus, the reference numerals of the first thread 210 is corresponding to those of the first thread 10 of Fig. 3. The second thread 230 of the threaded arrangement 201 is configured to threadingly engage with the second thread 240 of the filter housing 1003. The first threads 210, 220 of the two threaded arrangements 201, 201’, and the second threads 230, 240 of the two threaded arrangements 201, 201’, are shown separated from each other for increased comprehensibility.

[0096] The second thread 230 comprises a crest 231, a root 232, a pitch p, a thread height H extending in the direction from the root 232 to the crest 231, a leading flank 233 facing the leading end 201a for leading the connection and having a flat, or essentially flat, contacting portion 233’, and a trailing flank 234 facing the trailing end 201b. As shown in Fig. 5, a steepness of the flat, or essentially flat, contacting portion 233’ of the leading flank 233 with regards to the longitudinal axis A is smaller than an average steepness of the trailing flank 233 with regards to the longitudinal axis A, the flat, or essentially flat, contacting portion 233’ extending along at least 65 % of the thread height H and being inclined a2 between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis A. Thus, effects and features related to the second thread 230 of the threaded arrangement 201 are largely analogous to those described above in connection with the first thread 10, 110 but for an applied pressure P2 in the opposite direction to that described with reference to Fig.3 and Fig. 4, i.e. a pressure P2 from the trailing end 201b to the leading end 201a. Thus, threaded arrangements 201, 201’ will seal the air filter cartridge 1002 to the filter housing 1003 regardless of the direction of the pressure. As shown in the examples of Fig. 3 and Fig. 4, the leading flank 13, 113 may comprise a corresponding flat, or essentially flat, contacting portion 13’, 113’.

[0097] In any of the examples described herein, a play of 0.001 to 0.1 pitch p may be present at least between the first thread 10, 110, 210 of the air filter cartridge 1002 and the thread 20, 120, 220 of the filter housing 1003. For example, the play my be present between the corresponding root and crest pair 11, 111, 231 12, 112, 232 of the first thread 10, 110, 210 of the air filter cartridge 1002 and the thread 20, 120, 220 of the filter housing 1003.

[0098] FIG. 7 shows various alternatives of the inclination of the engagement portion 14’ and the average steepness (or average inclination) of the leading flank 13, with reference tothe first thread 10 of the threaded arrangement 1 described with reference to Fig. 3. All of the examples shown in Fig. 7 are example embodiments.

[0099] From the left to right and top to bottom, the inclination P between the engagement portion 14’ of the trailing flank 14 and the longitudinal axis A is decreasing from 57° to 42° while the inclination a (average inclination corresponding to the average steepness) of the leading flank 13 and the longitudinal axis A is increasing from 63° to 87°. With reference to the example in the top left corner, the shear forces F are indicated, the shear forces F being present when a pressure P is applied from the leading end la to the trailing end lb resulting in that the engagement portion 14’ is brought into contact with the corresponding flank 24 of the filter housing 1003 as previously described. The radial component of the shear forces F is indicated by Fl, and the vertical component of the shear forces F is indicated by F2. As is clear from Fig. 7, the radial component Fl of the shear forces F increases with decreasing inclination P, and increasing inclination a (the shear forces F, Fl, F2 are only shown in the example in the top left comer, the middle example in the middle, and the example in the bottom right corner, but is considered implicitly included for the other examples). The vertical component F2 of the shear forces F remains constant in the examples of Fig. 7. An increased radial force Fl typically corresponds to an increased stress on the thread 10. Thus, it is preferred to keep the radial force Fl low. However, as is also clear from Fig. 7, the size of the engagement portion 14’, and hence the contact area between the engagement portion 14’ and the corresponding flank 24 of the filter housing 1003, increases with increasing inclination P, and decreasing inclination a. An increased size of the engagement portion 14’ (and increased associated contact area) typically corresponds to an increased sealing effect. Thus, it is preferred to have a large engagement portion 14’.

[0100] Therefore, the choice of at least the inclination p between the engagement portion 14’ of the trailing flank 14 and the longitudinal axis A is important. The inventors have realized that a well-balanced distribution with regards to the radial force Fl of the shear forces F on one hand, and the size of the engagement portion 14’ (and associated intended contact area between the engagement portion 14’ and the thread 24 of the filter housing 1003) on the other hand, is achieved for an inclination P between 42° and 57°, which is further improved for an inclination P between 43° and 54°, and even further improved for an inclination p between 45° and 51°, e.g. between 46° and 48°. Thus, the stress of the thread 10is kept relatively low, while simultaneously providing a tight sealing at the trailing flank 14 when being subject to a pressure from the leading end la to the trailing end lb.

[0101] As also shown in Fig. 7, the combined axial distance of the trailing flank 14 and the leading flank 13 is equal for all of the examples in Fig. 7. Thus, as the inclination P between the engagement portion 14’ of the trailing flank 14 and the longitudinal axis A is decreasing, the inclination a of the leading flank 13 is increasing from 63° to 87°. Therefore, the shear section for all of the examples in Fig. 7 is the same.

[0102] FIG. 8 shows a cross-sectional view of an example of the first thread 410 of the threaded arrangement 1 of the air filter cartridge 1002. All features but the trailing flank 414 and the engagement portion 414’ are the same as those of the first thread 10 of Fig. 3, why the same reference numerals are used for corresponding feature. However, instead of being flat (with perfect planarity) as the engagement portion 14’ of the example shown in Fig. 3, the engagement portion 414’ here is essentially flat (i.e. with minor deviations from perfect planarity). The essentially flat engagement portion is here defined by a maximum offset in relation to the average steepness of the trailing flank, represented by the dashed line from the root 12 (12b) to the crest 11 (I la), i.e. the shortest distance between the root and crest, of below Y mm. As the pressure P described with reference to Fig. 2, is applied in a direction from the leading end to the trailing end, typically along the longitudinal axis A (but opposite the direction of the threaded connection), the resulting force will bring the first thread 410 of the threaded arrangement 1 of the air filter cartridge 1002 into contact with the corresponding thread 20 of the threaded arrangement of the filter housing 1003. Hereby, the engagement portion 414’ of the trailing flank 414 will be brough into contact with a flank 24 of the thread 20 of the filter housing 1003 corresponding to that of the trailing flank 414. This flank 24 may be referred to as an engagement flank 24 and is preferably flat. In more detail, the engagement portion 414’ of the trailing flank 414 forms an engagement surface 414a’ which will be brought into contact with the engagement flank 24 of the filter housing 1003. Hereby, the threaded arrangements will seal the air filter cartridge 1002 to the filter housing 1003. As the engagement portion 414’ is essentially flat, the portions deviating from the average steepness of the trailing flank, represented by the dashed line from the root 12 to the crest 11 may be slightly deformed, or will cause the engagement flank 24 to be slightly deformed, when the pressure P is applied as previously described. Thus, the whole, or at least themajority of, the engagement portion 414’ or engagement surface 414a’ will be brought into contact with the engagement flank 24.

[0103] The inclination P between 42° and 57°, or between 43° and 54°, or between 45° and 51°, e.g. between 46° and 48° is here shown as the inclination between the average steepness of the trailing flank, represented by the dashed line from the root 12 to the crest 11, and the longitudinal axis A.

[0104] Turning to FIG. 9, showing a cross-sectional view of yet another example of the first thread 510 of the threaded arrangement 1 of the air filter cartridge 1002. All features but the trailing flank 514 and the engagement portion 514’ are the same as those of the first thread 10 of Fig. 3, why the same reference numerals are used for corresponding feature. However, instead of being flat (with perfect planarity) as the engagement portion 14’ of the example shown in Fig. 3, the engagement portion 514’ here is slightly curved. In the example of Fig. 9, the curvature of the engagement potion 514’ is concave. The slightly curved engagement portion is here defined by a maximum offset in relation to the average steepness of the trailing flank, represented by the dashed line from the root 12 to the crest 11 (i.e. the shortest distance between the root 12b and crest I la), of below X mm. As the pressure P described with reference to Fig. 2, is applied in a direction from the leading end to the trailing end, typically along the longitudinal axis A (but opposite the direction of the threaded connection), the resulting force will bring the first thread 510 of the threaded arrangement 1 of the air filter cartridge 1002 into contact with the corresponding thread 20 of the threaded arrangement of the filter housing 1003. Hereby, the engagement portion 514’ of the trailing flank 514 will be brough into contact with a flank 24 of the thread 20 of the filter housing 1003 corresponding to that of the trailing flank 14. This flank 24 may again be referred to as an engagement flank 24 and is preferably flat. In more detail, the engagement portion 514’ of the trailing flank 514 forms an engagement surface 514a’ which will be brought into contact with the engagement flank 24 of the filter housing 1003. Hereby, the threaded arrangements will seal the air filter cartridge 1002 to the filter housing 1003. As the engagement portion 514’ is slightly curved, the portions deviating from the average steepness of the trailing flank, represented by the dashed line from the root 12 to the crest 11 may be slightly deformed, or will cause the engagement flank 24 to be slightly deformed, when the pressure P is applied as previously described. Thus, the whole, or at least the majority of, the engagement portion 514’ or engagement surface 514a’ will be brought into contact with the engagement flank 24.

[0105] Turning to FIG. 10, showing a cross-sectional view of yet another example of the first thread 610 of the threaded arrangement 1 of the air filter cartridge 1002. All features but the trailing flank 614 and the engagement portion 614’ are the same as those of the first thread 510 of Fig. 9, why the same reference numerals are used for corresponding feature. However, instead of a concave shape, the engagement portion 614’ here is slightly curved by a convex shape. The slightly curved engagement portion is here again defined by a maximum offset in relation to the average steepness of the trailing flank, represented by the dashed line from the root 12 to the crest 11 (i.e. the shortest distance between the root 12b and crest I la), of below X mm.

[0106] As an illustrative example, the average inclination of the engagement portion 614’ in FIG. 10, which is slightly curved in a convex manner, can be determined geometrically by reference to the dashed line representing the shortest distance between the root 12b and the crest I la of the trailing flank 614. Assuming that the horizontal projection (along the longitudinal axis A) between root and crest is 1.00 mm and the vertical projection (i.e., in the direction of the thread height H) is 1.20 mm, the average inclination p can be calculated using the arctangent function:P = arctan(l.20 / 1.00) 50.2°

[0107] This resulting angle P is interpreted as the average inclination of the engagement portion 614’, and in this example lies within the preferred range of 45° to 51° as previously defined. Despite the slightly curved convex shape, the use of a straight-line approximation from root to crest provides a means of defining the average inclination for both flat and nonflat (slightly curved) configurations. In this way, even slightly curved surfaces can be analytically compared and classified within the claimed inclination range.

[0108] For both Figs. 9 and 10, the inclination P between 42° and 57°, or between 43° and 54°, or between 45° and 51°, e.g. between 46° and 48° is shown as the inclination between the average steepness of the trailing flank, represented by the dashed line from the root 12 to the crest 11, and the longitudinal axis A.

[0109] For the examples in Figs. 8-10, it should be noted that the engagement portion, whether essentially flat or slightly curved, may result from minor shape deviations introduced during thread manufacturing, as well as from unavoidable tolerances or local deformations during threading. However, its function and related effects, as e.g. described for the examples in Figs. 2-7 typically applies for the examples in Figs. 8-10 as well. Thus, the use of“essentially flat” or “slightly curved” therefore allows for manufacturing tolerances or design adaptations that maintain functional equivalence to a flat engagement portion.

[0110] FIG. 11 is showing an alternative embodiment of the thread 410 of Fig. 8. The thread 710 of Fig. 11 may thus correspond to the previously described first thread of the threaded arrangement 1 of the air filter cartridge 1002. All features but the crest 711 and root 712 are the same, or essentially the same, as those of the thread 410 of Fig. 8, why similar reference numerals are used for corresponding features (but in the series of 700th hundred). Instead of providing crests 11 and roots 12 which are pointy, with a minimum axial extension, as for the thread 410 in Fig. 8, the crest 711 (711a, 711b) and root 712 (712a, 712b) are curved and associated with an axial extension larger than the minimum axial extension (for example corresponding to those described with reference to Fig. 4). In more detail, the root 712 may be referred to as a root region, and may e.g. be defined as between the first 1 % to the first 10 % of the thread height H, indicated by hl in Fig. 11. Correspondingly, the crest 711 may be referred to as a crest region, and may e.g. be defined as between the last 10% to the last 1 % of the thread height H, indicated by h3 in Fig. 11. Thus, the trailing flank 714 may be defined to extend from the root 712, or end of root region, to the crest 711, or beginning of crest region, along between 80 % to 98 % of the thread height H, indicated by h2 in Fig. 11. Correspondingly, the leading flank 713 (713a, 713b) may be defined to extend from the crest 11, or end of crest region, to the root 12, or beginning of root region, along between 80 % and 98 % of the thread height H. As for the example in Fig. 8, the engagement portion 714’ of the trailing flank 714 will be brough into contact with a flank 24 of the thread 20 of the filter housing 1003 corresponding to that of the trailing flank 414, during use, under operational load.

[0111] Example 1. An air filter cartridge comprising a filter body and a threaded arrangement for connection with a thread of a filter housing, the threaded arrangement having a leading end, a trailing end opposite to the leading end and at least a first thread extending helically along a longitudinal axis from the leading end to the trailing end, the first thread having a crest, a root, a pitch, a thread height extending in the direction from the root to the crest, a leading flank facing the leading end for leading the connection, and a trailing flank facing the trailing end and having an engagement portion, wherein a steepness of the engagement portion of the trailing flank with regards to the longitudinal axis is smaller than an average steepness of the leading flank with regards to the longitudinal axis, theengagement portion extending along at least 65 % of the thread height and being inclined between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis.

[0112] Example 2. The air filter cartridge of example 1, wherein the root is defined as the first 10 % of the thread height and the crest is defined as the last 10 % of the thread height, wherein the trailing flank is defined to extend from the root to the crest along 80 % of the thread height.

[0113] Example 3. The air filter cartridge of example 2, wherein a mid-point of the crest is arranged off-set from a position at 0.5 pitch by at least 0.05 pitch, preferably by at least 0.10 pitch.

[0114] Example 4. The air filter cartridge of any of examples 1-3, wherein the engagement portion of the trailing flank has an axial extension of at least 0.30 pitch, preferably at least 0.35 pitch, more preferably at least 0.40 pitch.

[0115] Example 5. The air filter cartridge of any of examples 1-4, wherein the leading flank has a first axial extension, the trailing flank has a second axial extension, the crest has a third axial extension and the root has a fourth axial extension, wherein the sum of the first, second, third and fourth axial extensions is equal to the pitch.

[0116] Example 6. The air filter cartridge of example 5, wherein the second axial extension is larger than the first axial extension.

[0117] Example 7. The air filter cartridge of any of examples 5-6, wherein the sum of the first axial extension, half of the third axial extension and half of the fourth axial extension is smaller than 0.5 pitch, preferably smaller than 0.45 pitch or smaller than 0.35 pitch and the sum of the second axial extension, half of the third axial extension and half of the fourth axial extension is larger than 0.5 pitch, preferably larger than 0.55 pitch or larger than 0.65 pitch.

[0118] Example 8. The air filter cartridge of any of examples 5-7, wherein the third axial extension is equal to or smaller than 0.25 pitch, preferably equal to or smaller than 0.15 pitch, and / or the fourth axial extension is equal to or smaller than 0.20 pitch, preferably equal to or smaller than 0.15 pitch.

[0119] Example 9. The air filter cartridge of any of examples 1-8, wherein the average steepness of the leading flank is between 6° and 45°, preferably between 13° and 42°, more preferably between 20° and 39° steeper than the engagement portion of the trailing flank.

[0120] Example 10. The air filter cartridge of any of examples 1-9, wherein the average steepness of the leading flank is between 63° and 87°, preferably between 67° and 85°, more preferably between 71° and 81° with regards to the longitudinal axis.

[0121] Example 11. The air filter cartridge of any of examples 1-10, wherein the engagement portion of the trailing flank forms an engagement surface for a corresponding flank of the thread of the filter housing, and wherein the engagement surface of the trailing flank is configured to be brought into contact with the corresponding flank of the thread of the filter housing when the air filter device is subject to a pressure in a direction from the leading end to the trailing end.

[0122] Example 12. The air filter cartridge of any of examples 1-11, wherein the threaded arrangement is a multi-screw thread arrangement further comprising a second thread extending helically along the longitudinal axis from the leading end to the trailing end offset compared to the first thread, and wherein the second thread is correspondingly shaped to the first thread, or is shaped differently to the first thread.

[0123] Example 13. The air filter cartridge of example 12, wherein the second thread comprises a crest, a root, a pitch, a thread height extending in the direction from the root to the crest, a leading flank facing the leading end for leading the connection and having a contacting portion, and a trailing flank facing the trailing end, wherein a steepness of the contacting portion of the leading flank with regards to the longitudinal axis is smaller than an average steepness of the trailing flank with regards to the longitudinal axis, the contacting portion extending along at least 65 % of the thread height and being inclined between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis.

[0124] Example 14. The air filter cartridge of any of examples 1-13, wherein the engagement portion is flat or essentially flat.

[0125] Example 15. The air filter cartridge of any of examples 1-13, wherein the engagement portion is slightly curved.

[0126] Example 16. The air filter cartridge of any of examples 1-15, wherein the steepness the engagement portion is defined as the average steepness for the chord or median line connecting the root and crest along the trailing flank, and the longitudinal axis.

[0127] Example 17. An air filter system comprising a filter housing and an air filter cartridge according to any one of examples 1-16.

[0128] Example 18. A filter housing comprising a threaded arrangement for connection with a thread of an air filter cartridge, the threaded arrangement having a first end, a second end opposite to the first end and at least a first thread extending helically along a longitudinal axis from the first end to the second end, the first thread having a crest, a root, a pitch, a thread height extending in the direction from the root to the crest, a first flank facing the first end, and a second flank facing the second end and having a housing thread engagement portion, wherein a steepness of the housing thread engagement portion of the second flank with regards to the longitudinal axis is smaller than an average steepness of the first flank with regards to the longitudinal axis, the housing thread engagement portion extending along at least 65 % of the thread height and being inclined between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis.

[0129] Example 19. A vehicle comprising an air filter cartridge of any of examples 1-17, an air filter system of example 17, or a filter housing of example 18.

[0130] Example 20. Use of an air filter cartridge in a filter housing, the air filter cartridge being that of any of examples 1-16, or defined to comprise: a filter body and a threaded arrangement for connection with a first thread of the filter housing, the threaded arrangement having a leading end, a trailing end opposite to the leading end and at least a first thread extending helically along a longitudinal axis from the leading end to the trailing end, the first thread having a crest, a root, a pitch, a thread height extending in the direction from the root to the crest, a leading flank facing the leading end for leading the connection, and a trailing flank facing the trailing end and having an engagement portion, wherein a steepness of the engagement portion of the trailing flank with regards to the longitudinal axis is smaller than an average steepness of the leading flank with regards to the longitudinal axis, the engagement portion extending along at least 65 % of the thread height and being inclined between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis.

[0131] Example 21. The use of example 20, wherein the first thread of the filter housing is threadingly engaging with the first thread of the air filter cartridge.

[0132] Example 22. The use of any of examples 20-21, wherein the first thread of the filter housing comprises an engagement flank which is configured to be brought into contact with the engagement portion of the trailing flank of the air filter cartridge.

[0133] Example 23. The use of example 22, wherein, when the air filter cartridge is subject to a pressure acting from the leading end toward the trailing end, the engagement portion of the trailing flank is brought into contact with the engagement flank of the first thread of the filter housing to provide sealing.

[0134] Example 24. The use of any of examples 22-23, wherein the engagement flank is flat and inclined between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis.

[0135] Example 25. The use of any of examples 22-24, wherein the engagement portion of the trailing flank is flat and inclined between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis.

[0136] Example 26. The use of any of examples 22-25, wherein, when the air filter cartridge is subject to a pressure acting from the leading end toward the trailing end, the contact between the engagement flank and the engagement portion of the trailing flank is spanning along at least 65 % of the thread height.

[0137] Example 27. Use of an air filter cartridge in a filter housing, the filter housing being that of example 18, or defined to comprise: a threaded arrangement for connection with a thread of the air filter cartridge, the threaded arrangement having a first end, a second end opposite to the first end and at least a first thread extending helically along a longitudinal axis from the first end to the second end, the first thread having a crest, a root, a pitch, a thread height extending in the direction from the root to the crest, a first flank facing the first end, and a second flank facing the second end and having a housing thread engagement portion,

[0138] wherein a steepness of the housing thread engagement portion of the second flank with regards to the longitudinal axis is smaller than an average steepness of the first flank with regards to the longitudinal axis, the housing thread engagement portion extending along at least 65 % of the thread height and being inclined between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis.

[0139] Example 28. The use of example 27, wherein the air filter cartridge is compatible with the filter housing.

[0140] Example 29. The use of any of examples 27-28, wherein the first thread of the filter housing is threadingly engaging with the first thread of the air filter cartridge.

[0141] Example 30. The use of any of examples 27-29, wherein the second flank is an engagement flank configured to be brought into contact with an engagement portion of a trailing flank of a threaded arrangement of the air filter cartridge.

[0142] Example 31. The use of example 30, wherein, when the air filter cartridge is subject to a pressure acting from the second end toward the first end, the engagement portion of the trailing flank is brought into contact with the engagement flank of the first thread of the filter housing to provide sealing.

[0143] Example 32. The use of any of examples 27-31, wherein a housing thread engagement portion of the second flank is flat, or essentially flat.

[0144] The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms "comprises," "comprising," "includes," and / or "including" when used herein specify the presence of stated features, integers, actions, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, actions, steps, operations, elements, components, and / or groups thereof.

[0145] It will be understood that, although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the scope of the present disclosure.

[0146] Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe a relationship of one element to another element as illustrated in the Figures. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present.

[0147] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0148] It is to be understood that the present disclosure is not limited to the aspects described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the present disclosure and appended claims. In the drawings and specification, there have been disclosed aspects for purposes of illustration only and not for purposes of limitation, the scope of the disclosure being set forth in the following claims.

Claims

ClaimsWhat is claimed is:

1. An air filter cartridge (1002) comprising a filter body (1002a) and a threaded arrangement (1, 101, 201) for connection with a thread (20, 120, 220) of a filter housing (1003), the threaded arrangement (1, 101, 201) having a leading end (la, 101a, 201a), a trailing end (lb, 101b, 201b) opposite to the leading end (la, 101a, 201a) and at least a first thread (10, 110, 210) extending helically along a longitudinal axis (A) from the leading end (la, 101a, 201a) to the trailing end (lb, 101b, 201b), the first thread having a crest (11, 111), a root (12, 112), a pitch (p), a thread height (H) extending in the direction from the root (12, 112) to the crest (11, 111), a leading flank (13, 113) facing the leading end (la, 101a, 201a) for leading the connection, and a trailing flank (14, 114) facing the trailing end (1, 101b, 201b) and having an engagement portion (14’, 114’), wherein a steepness of the engagement portion (14’, 114’) of the trailing flank (14, 114) with regards to the longitudinal axis (A) is smaller than an average steepness of the leading flank (13, 113) with regards to the longitudinal axis (A), the engagement portion (14’, 114’) extending along at least 65 % of the thread height (H) and being inclined (P) between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis (A).

2. The air filter cartridge (1002) of claim 1, wherein the root (12, 112) is defined as the first 10 % of the thread height (H) and the crest (11, 111) is defined as the last 10 % of the thread height (H), wherein the trailing flank (14, 114) is defined to extend from the root (12, 112) to the crest (11, 111) along 80 % of the thread height (H).

3. The air filter cartridge (1002) of claim 2, wherein a mid-point (m) of the crest (11,111) is arranged off-set from a position at 0.5 pitch by at least 0.05 pitch (p), preferably by at least 0.10 pitch (p).

4. The air filter cartridge (1002) of any of claims 1-3, wherein the engagement portion (14’, 114’) of the trailing flank (14, 114) has an axial extension of at least 0.30 pitch (p), preferably at least 0.35 pitch (p), more preferably at least 0.40 pitch (p).

5. The air filter cartridge (1002) of any of claims 1-4, wherein the leading flank (13, 113) has a first axial extension (dl), the trailing flank (14, 114) has a second axial extension (d2), the crest (11, 111) has a third axial extension (d3) and the root (12, 112) has a fourth axial extension (d4), wherein the sum of the first, second, third and fourth axial extensions (dl, d2, d3, d4) is equal to the pitch (p).

6. The air filter cartridge (1002) of claim 5, wherein the second axial extension is larger than the first axial extension.

7. The air filter cartridge (1002) of any of claims 5-6, wherein the sum of the first axial extension (dl), half of the third axial extension (d3) and half of the fourth axial extension (d4) is smaller than 0.5 pitch (p), preferably smaller than 0.45 pitch (p) or smaller than 0.35 pitch (p) and the sum of the second axial extension (d2), half of the third axial extension (d3) and half of the fourth axial extension (d4) is larger than 0.5 pitch (p), preferably larger than 0.55 pitch (p) or larger than 0.65 pitch (p).

8. The air filter cartridge (1002) of any of claims 5-7, wherein the third axial extension (d3) is equal to or smaller than 0.25 pitch (p), preferably equal to or smaller than 0.15 pitch (p), and / or the fourth axial extension (d4) is equal to or smaller than 0.20 pitch (p), preferably equal to or smaller than 0.15 pitch (p).

9. The air filter cartridge (1002) of any of claims 1-8, wherein the average steepness of the leading flank (13, 113) is between 6° and 45°, preferably between 13° and 42°, more preferably between 20° and 39° steeper than the engagement portion (14’, 114’) of the trailing flank (14, 114).

10. The air filter cartridge (1002) of any of claims 1-9, wherein the average steepness of the leading flank (13, 113) is between 63° and 87°, preferably between 67° and 85°, more preferably between 71° and 81° with regards to the longitudinal axis (A).

11. The air filter cartridge (1002) of any of claims 1-10, wherein the engagement portion (14’, 114’) of the trailing flank (14, 114) forms an engagement surface for a corresponding flank (24, 124) of the thread (20, 120) of the filter housing (1003), and wherein the engagement surface of the trailing flank (114) is configured to be brought into contact with the corresponding flank (24, 124) of the thread (20) of the filter housing (1003) when the air filter device (1002) is subject to a pressure (P) in a direction from the leading end (la, 101a, 201a) to the trailing end (lb, 101b, 201b).

12. The air filter cartridge (1002) of any of claims 1-11, wherein the threaded arrangement (201) is a multi-screw thread arrangement (201) further comprising a second thread (230) extending helically along the longitudinal axis (A) from the leading end (201a) to the trailing end (201b) offset compared to the first thread (210), and wherein the second thread (230) is correspondingly shaped to the first thread (210), or is shaped differently to the first thread (210).

13. The air filter cartridge (1002) of claim 12, wherein the second thread (230) comprises a crest (231), a root (232), a pitch (p), a thread height (H) extending in the direction from the root (232) to the crest (231), a leading flank (233) facing the leading end (201a) for leading the connection and having a contacting portion (233’), and a trailing flank (234) facing the trailing end (201b), wherein a steepness of the contacting portion (233’) of the leading flank (233) with regards to the longitudinal axis (A) is smaller than an average steepness of the trailing flank (233) with regards to the longitudinal axis (A), the contacting portion (233’) extending along at least 65 % of the thread height (H) and being inclined (a2) between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis (A).

14. The air filter cartridge (1002) of any of claims 1-13, wherein the engagement portion (14’) is flat or essentially flat.

15. The air filter cartridge (1002) of any of claims 1-13, wherein the engagement portion (14’) is slightly curved.

16. The air filter cartridge (1002) of any of claims 1-15, wherein the steepness the engagement portion is defined as the average steepness for the chord or median line connecting the root and crest along the trailing flank, and the longitudinal axis.

17. An air filter system (1001) comprising a filter housing (1003) and an air filter cartridge (1002) according to any one of claims 1-16.

18. A filter housing comprising a threaded arrangement (T) for connection with a thread (10, 110, 210) of an air filter cartridge (1002), the threaded arrangement (1’) having a first end (l’a), a second end (l’b) opposite to the first end (l’a) and at least a first thread (20) extending helically along a longitudinal axis (A’) from the first end (l’a) to the second end (l’b), the first thread (20) having a crest (11’), a root (12’), a pitch (p’), a thread height (H’) extending in the direction from the root (12’) to the crest (11’), a first flank (23) facing the first end (l’a), and a second flank (24) facing the second end (l’b) and having a housing thread engagement portion (24’), wherein a steepness of the housing thread engagement portion (24’) of the second flank (24) with regards to the longitudinal axis (A’) is smaller than an average steepness of the first flank (23) with regards to the longitudinal axis (A’), the housing thread engagement portion (24’) extending along at least 65 % of the thread height (H) and being inclined (P) between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis (A’).

19. A vehicle (1) comprising an air filter cartridge of any of claims 1-17, an air filter system (1001) of claim 17, or a filter housing of claim 18.

20. Use of an air filter cartridge (1002) in a filter housing (1003), the air filter cartridge being that of any of claims 1-16, or defined to comprise: a filter body (1002a) and a threaded arrangement (1, 101, 201) for connection with a first thread (20, 120, 220) of the filter housing (1003), the threaded arrangement (1, 101, 201) having a leading end (la, 101a, 201a), a trailing end (lb, 101b, 201b) opposite to the leading end (la, 101a, 201a) and at least a first thread (10, 110, 210) extending helically along a longitudinal axis (A) from the leading end (la, 101a, 201a) to the trailing end (lb, 101b, 201b), the first thread having a crest (11,111), a root (12, 112), a pitch (p), a thread height (H) extending in the direction from the root(12, 112) to the crest (11, 111), a leading flank (13, 113) facing the leading end (la, 101a, 201a) for leading the connection, and a trailing flank (14, 114) facing the trailing end (1, 101b, 201b) and having an engagement portion (14’, 114’), wherein a steepness of the engagement portion (14’, 114’) of the trailing flank (14, 114) with regards to the longitudinal axis (A) is smaller than an average steepness of the leading flank (13, 113) with regards to the longitudinal axis (A), the engagement portion (14’, 114’) extending along at least 65 % of the thread height (H) and being inclined (P) between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis (A).

21. The use of claim 20, wherein the first thread of the filter housing is threadingly engaging with the first thread of the air filter cartridge.

22. The use of any of claims 20-21, wherein the first thread of the filter housing comprises an engagement flank (24) which is configured to be brought into contact with the engagement portion of the trailing flank of the air filter cartridge.

23. The use of claim 22, wherein, when the air filter cartridge (1002) is subject to a pressure acting from the leading end (la, 101a, 201a) toward the trailing end (lb, 101b, 201b), the engagement portion (14’, 114’) of the trailing flank (14, 114) is brought into contact with the engagement flank (24, 124) of the first thread (20, 120, 220) of the filter housing (1003) to provide sealing.

24. The use of any of claims 22-23, wherein the engagement flank (24) is flat and inclined (P’) between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis (A’).

25. The use of any of claims 22-24, wherein the engagement portion (14’) of the trailing flank (14) is flat and inclined (P) between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis (A).

26. The use of any of claims 22-25, wherein, when the air filter cartridge (1002) is subject to a pressure acting from the leading end (la, 101a, 201a) toward the trailing end (lb, 101b, 201b), the contact between the engagement flank (24) and the engagement portion (14’, 114’) of the trailing flank (14, 114) is spanning along at least 65 % of the thread height (H).

27. Use of an air filter cartridge (1002) in a filter housing (1003), the filter housing (1003) being that of claim 18, or defined to comprise: a threaded arrangement (1’) for connection with a thread (10, 110, 210) of the air filter cartridge (1002), the threaded arrangement (T) having a first end (1 ’a), a second end (l’b) opposite to the first end (l’a) and at least a first thread (20) extending helically along a longitudinal axis (A’) from the first end (l’a) to the second end (l’b), the first thread (20) having a crest (11’), a root (12’), a pitch (p’), a thread height (H’) extending in the direction from the root (12’) to the crest (11’), a first flank (23) facing the first end (l’a), and a second flank (24) facing the second end (l’b) and having a housing thread engagement portion (24’), wherein a steepness of the housing thread engagement portion (24’) of the second flank (24) with regards to the longitudinal axis (A’) is smaller than an average steepness of the first flank (23) with regards to the longitudinal axis (A’), the housing thread engagement portion (24’) extending along at least 65 % of the thread height (H’) and being inclined (P’) between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with regards to the longitudinal axis (A’).

28. The use of claim 27, wherein the air filter cartridge is compatible with the filter housing.

29. The use of any of claims 27-28, wherein the first thread of the filter housing is threadingly engaging with the first thread of the air filter cartridge.

30. The use of any of claims 27-29, wherein the second flank is an engagement flank (24, 124) configured to be brought into contact with an engagement portion (14’, 114’) of a trailing flank (14, 114) of a threaded arrangement (1) of the air filter cartridge.

31. The use of claim 30, wherein, when the air filter cartridge (1002) is subject to a pressure acting from the second end (l’b) toward the first end (1 ’a), the engagement portion (14’, 114’) of the trailing flank (14, 114) is brought into contact with the engagement flank (24, 124) of the first thread (20) of the filter housing (1003) to provide sealing.

32. The use of any of claims 27-31, wherein a housing thread engagement portion (24’) of the second flank (24) is flat, or essentially flat.

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