air filter cartridge

Abstract

Air filter cartridge (1002) comprising a filter body (1002a) and a threaded assembly (1, 101, 201) for connection to a thread (20, 120, 220) of a filter housing (1003), wherein the threaded assembly (1, 101, 201) has a front end (1a, 101a, 201a), a rear end (1b, 101b, 201b) opposite the front end (1a, 101a, 201a) and at least one first thread (10, 110, 210) extending helically along a longitudinal axis (A) from the front end (1a, 101a, 201a) to the rear end (1b, 101b, 201b), wherein the first thread has a threaded crown (11, 111), a threaded root (12, 112), has a thread pitch (p) and a thread height (H) extending in the direction from the thread root (12, 112) to the thread crown (11, 111), a front flank (13, 113) facing the front end (1a, 101a, 201a) for initiating the connection and a rear flank (14, 114) facing the rear end (1, 101b, 201b) with an engagement section (14', 114'),wherein the steepness of the engagement section (14', 114') of the rear flank (14, 114) with respect to the longitudinal axis (A) is less than an average steepness of the front flank (13, 113) with respect to the longitudinal axis (A), wherein the engagement section (14', 114') extends over at least 65% of the thread height (H) and is inclined with respect to the longitudinal axis (A) at an angle (β) between 42° and 57°, and wherein the average steepness of the front flank (13, 113) is between 6° and 45° steeper than the engagement section (14', 114') of the rear flank (14, 114).

Description

TECHNICAL AREA

[0001] The invention relates generally to air filter systems. In certain aspects, the invention relates to an air filter cartridge. The invention can be applied to heavy-duty vehicles such as trucks, buses, and construction machinery, as well as to other types of vehicles, including seagoing vessels. Although the invention can be described with respect to a particular vehicle, it is not limited to any specific vehicle. BACKGROUND

[0002] Vehicles equipped with an internal combustion engine include several filters that must be replaced during maintenance. These filters are typically housed in disposable cartridges, which are attached directly to the engine via a base or placed in a tray or filter housing that is mounted to the engine. In most cases, the filter cartridge is threaded so that it can be screwed onto or into the filter housing. Threaded connections are usually made using a standard ISO metric thread. These standard threaded connections allow the filter cartridge to be manually tightened to the filter housing. However, such standard threaded connections are not designed to withstand high pull-out forces.If internal pressure or overpressure is sustained, or if the filter cartridge is not properly tightened, it can be pulled out and detached from the filter housing. Therefore, it is desirable to prevent the filter cartridge from being unintentionally pulled out of the filter housing while maintaining easy manual fastening. This is especially true for an air filter cartridge or an air dryer filter cartridge for a truck's compressed air system. Given these challenges, there is a need for an improved air filter cartridge and an improved air filtration system that address at least some of the limitations of current systems. SUMMARY

[0003] The object of the present invention is to at least partially overcome the aforementioned problems and to provide an air filter cartridge that is improved upon prior art solutions. The air filter cartridge comprises a filter body with a threaded assembly for connection to a thread of a filter housing. The threaded assembly has a front end, a rear end opposite the front end, and at least one first thread extending helically or spirally along a longitudinal axis from the front end to the rear end. The first thread comprises a thread crown, a thread root, a thread pitch, a thread depth extending from the thread root to the thread crown, a front flank facing the front end for initiating the connection, and a rear flank facing the rear end with an engagement section.By designing the first thread with a rear flank engagement steepness that is less than the average steepness of the front flank, a thread structure is provided that achieves a balanced distribution between shear forces (typically the radial shear force) and the potential contact area, as well as a tight seal at the rear flank when subjected to front-to-rear pressure (i.e., under operating load), for example, when the air filter cartridge is connected to a pressure vessel, where the pressure vessel includes or forms the filter housing. Thus, the thread arrangement provides an advantageous thread design that can be used to attach a disposable filter to a pressure vessel, in particular an air filter cartridge to a filter housing.The engagement section of the rear flank is typically the portion of the rear flank intended to come into contact with the corresponding flank of the filter housing thread under operating load. Typically, the engagement section comprises a significant portion of the rear flank, such as a substantial part of it, and therefore a satisfactory contact area with the corresponding flank of the filter housing thread can be achieved when pressure is applied from the front end to the rear end (e.g., pressure such as sustained internal pressure or overpressure, which might otherwise cause the air filter cartridge to be pulled out and detached from the filter housing). This allows for the creation of a strong thread, or at least one that does not break or wear prematurely and provides a sufficient seal between the filter housing and the air filter cartridge.In other words, the stress induced by the radial force can be compensated by the size of the engagement section or the intended associated contact area between the engagement section and the corresponding flank of the filter housing thread. The engagement section can, for example, comprise at least 65% or at least 80% of the trailing flank. The steepness of the engagement section on the trailing flank and the average steepness of the leading flank are related to a corresponding inclination with respect to the longitudinal axis. That is, the average steepness of the leading flank can correspond to the inclination or the average inclination of the leading flank relative to the longitudinal axis. Additionally or alternatively, the steepness of the engagement section on the trailing flank can correspond to the inclination or the average inclination of the engagement section relative to the longitudinal axis.The air filter cartridge can be, for example, an air dryer filter cartridge, and the filter housing can be an air dryer filter housing.

[0004] An air filter cartridge according to the invention is defined by claim 1. Dependent claims relate to preferred embodiments. The air filter cartridge according to the invention comprises a filter body and a threaded arrangement for connection to a thread of a filter housing.The threaded arrangement has a front end, a rear end opposite the front end, and at least one first thread extending helically along a longitudinal axis from the front end to the rear end, the first thread having a thread crown, a thread root, a thread pitch, a thread height extending in the direction from the thread root to the thread crown, a front flank facing the front end for initiating the connection, and a rear flank facing the rear end with an engagement section, wherein the steepness of the engagement section of the rear flank with respect to the longitudinal axis is less than the average steepness of the front flank with respect to the longitudinal axis, the engagement section extending over at least 65% of the thread height and being inclined with respect to the longitudinal axis between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51°.The average steepness of the front flank is between 6° and 45° steeper than the engagement section of the rear flank. A technical advantage includes a further improved force distribution with respect to shear forces. The comparison between the front flank and the engagement section of the rear flank can refer here to the average steepness of the engagement section. The invention aims to overcome problems with the unintentional detachment of the air filter cartridge from the filter housing (e.g., by tearing the air filter cartridge out) and simultaneously ensure a tight seal at the rear flank when pressure is exerted from the front end to the rear end. The invention provides an improved thread arrangement.Typically, the thread arrangement can provide a strong thread, or at least a thread that will not break or wear out prematurely and that ensures a sufficient seal between the filter housing and the air filter cartridge.In other words, the combination of an engagement section of the rear flank that is less steep than the average steepness of the front flank, and wherein the engagement section is inclined with respect to the longitudinal axis by between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51°, can provide a thread arrangement that creates a well-balanced distribution with respect to at least the radial force of the shear forces (leading to stresses in the thread) on the one hand and the size of the engagement section or the intended associated contact area between the engagement section and the thread of the filter housing on the other, while at the same time ensuring a tight seal on the rear flank when pressure is exerted from the front end to the rear end.By providing an engagement section extending over at least 65% of the thread height, the engagement section forms a substantial portion of the trailing flank, for example, a significant portion of the trailing flank. For instance, the engagement section can comprise at least 65% of the trailing flank, such as 80%. A technical advantage may be an improved distribution of shear forces (at least their radial force) between the engagement section of the first thread and the corresponding thread of the filter housing. Another technical advantage may include reduced wear of the thread assembly. A further technical advantage may be a tight seal at the trailing flank when the air filter cartridge is subjected to front-end to trailing pressure, typically when the air filter cartridge is connected to the filter housing of a pressure vessel, such as an air dryer housing.In other words, the aforementioned design of the first thread allows for a satisfactory size of the engagement section, and thus the intended contact area, between the engagement section of the rear flank and the corresponding flank of the thread on the filter housing when pressure is applied from the front end to the rear end. By designing the first thread with a pitch of the engagement section on the rear flank that is smaller than the average pitch of the front flank, the first thread is asymmetrical with respect to the front and rear flanks.

[0005] It is understood that the engagement section of the rear flank is typically that section of the rear flank which, due to the design of the air filter cartridge, is intended to provide a surface for engagement with a corresponding flank of the thread on the filter housing under operating load. The definition of the engagement section is thus based on the geometry of the rear flank itself, independent of the specific geometry of the thread on the filter housing. The engagement section is typically the portion of the rear flank shaped to allow contact with the corresponding flank of the thread on the filter housing under operating load. This contrasts, for example, with the portion of the rear flank not shaped for such purposes, such as the portion near the thread root. The engagement section may be flat or essentially flat.Alternatively, the engagement section is slightly curved, and the steepness refers to the average steepness of the engagement section (i.e., the inclination with respect to the longitudinal axis is the average inclination of the engagement section). Thus, the engagement section is typically the portion of the trailing flank that is flat (or essentially flat) or slightly curved and that is designed or configured to make surface contact (under operating load) with the corresponding flank of the thread of the filter housing. Under operating load, when the engagement section 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 completely flat, for example, if the engagement section is essentially flat or slightly curved.In such cases, the resulting surface contact area effectively corresponds to that which would be achieved by a flat engagement section. Thus, despite minor deviations from flatness or perfect flatness, such as protrusions or waves (under the definition of "essentially flat") or convex or concave curvatures (under the definition of "slightly curved"), the engagement section still ensures a large and reliable contact area under load conditions, functionally equivalent to that of a flat engagement section. In other words, the engagement section can be either flat or slightly non-flat, with the slightly non-flat engagement section encompassing both the essentially flat and the slightly curved configurations.

[0006] Optionally, in some embodiments, including at least one preferred embodiment, the engagement section is flat or substantially flat. A substantially flat engagement section can be defined by a maximum offset with respect to the average steepness of the trailing flank below Y mm, where Y is, for example, 3% of the thread height. Thus, for a thread height of 1 mm, Y is 0.03 mm. Alternatively, the substantially flat engagement section is defined by a predefined maximum offset with respect to a straight line (chord or centerline) connecting the thread root and the thread crest along the trailing flank. Such a straight line can be defined as following the shortest distance between the thread root and the thread crest along the trailing flank, or alternatively, the shortest distance between the thread root region and the thread crest region (e.g.,(between the end of the thread root region and the beginning of the thread crown region, viewed from the thread root to the thread crown). Such a predefined maximum offset can be the previously mentioned Y mm. Thus, an "essentially flat" engagement section can be defined by the described maximum offset Y mm. Such deviations can include, for example, minor surface irregularities such as protrusions or waves, or local unevenness, extending at most Y mm from the aforementioned straight line or from the average steepness of the trailing flank. Conversely, the engagement section can be considered "flat" if this maximum offset is essentially negligible and well below Y mm, typically less than 1% of the thread height (e.g., less than 0.01 mm).

[0007] Optionally, in some embodiments, including at least one preferred embodiment, the flat or substantially flat engagement section can be defined with reference to the surface of the engagement section. The surface can be considered "substantially flat" if its maximum deviation from a reference plane spanning the engagement section (from the thread root or root region to the thread crown or crown region, as previously described) does not exceed Z, where Z is preferably less than or equal to 3% of the thread height. For example, with a thread height of 1 mm, a deviation of up to 0.03 mm may still fall within the definition of "substantially flat." Conversely, a surface is considered "flat" if this deviation from the reference plane is substantially negligible, well below Y mm, typically less than 1% of the thread height.

[0008] In other words, the term "flat" can refer to the fact that the surface of the engagement section is flat over its entire extent from the thread root to the thread crest, while "essentially flat" encompasses surfaces with minor deviations from perfect flatness, such as local irregularities or surface features like protrusions, waves, ribs, or similar microstructures, provided that such deviations do not substantially reduce the intended surface contact area under operating load. The use of "essentially flat" therefore allows for manufacturing tolerances or design adjustments that maintain functional equivalence to a flat engagement surface.

[0009] Optionally, in some embodiments, including at least one preferred embodiment, the engagement section is slightly curved. Thus, as an alternative to an substantially flat engagement section that deviates only slightly from a flat configuration, the engagement section can instead be slightly curved, representing a further controlled deviation from an ideal flat surface. The slightly curved engagement section can be either convex or concave, including configurations that follow a gently curved profile or a polygonal shape that approximates such curvature. A slightly curved engagement section can have an average inclination, defined as the angle formed between a straight line (chord or centerline) connecting the thread root and the thread crown along the trailing flank and the longitudinal axis.As previously described, such a straight line can be defined as the straight line following the shortest distance between the thread root and the thread crown along the trailing flank, or alternatively, the shortest distance between the thread root region and the thread crown region (e.g., between the end of the thread root region and the beginning of the thread crown region, as seen from the thread root to the thread crown). The average inclination of such a slightly curved engagement section corresponds to the previously mentioned steepness or inclination of the engagement section and can thus be between 42° and 57° with respect to the longitudinal axis, preferably between 43° and 54°, and more preferably between 45° and 51°. In certain embodiments, the engagement section can be slightly curved, wherein the maximum deviation from the chord or centerline does not exceed a threshold of X mm, where X is, for example, 3% of the thread height.With a thread height of 1 mm, X is therefore 0.03 mm. In this way, the slightly curved engagement section is still shaped in such a way that it provides a sufficient and reliable contact area with the corresponding flank of the thread of the filter housing, especially under operating load. In contrast, the engagement section can be considered "non-curved" if this maximum offset is essentially negligible and well below X mm, typically less than 1% of the thread height (e.g., less than 0.01 mm).

[0010] Optionally, in some embodiments, including at least one preferred embodiment, the slightly curved engagement section can be defined with reference to the surface of the engagement section. The surface can be considered "slightly curved" if its maximum deviation from a reference plane spanning the engagement section (from the thread root or root region to the thread crown or crown region, as previously described) does not exceed T, where T is preferably less than or equal to 3% of the thread height. For example, with a thread height of 1 mm, a deviation of up to 0.03 mm may still fall within the definition of "slightly curved." Conversely, a surface is considered "not curved" if this deviation is essentially negligible, well below X mm, typically less than 1% of the thread height.

[0011] In other words, the term "slightly curved" encompasses slightly curved surfaces with minor deviations from perfect flatness, provided that such deviations do not significantly reduce the intended surface contact area under operating load. The use of "slightly curved" therefore allows for manufacturing tolerances or design adjustments that maintain functional equivalence to a flat engagement surface.

[0012] Thus, engagement sections with identical average inclination (measured as the inclination of a chord between the thread root and thread crest, as previously described) can vary in shape, for example, being flat, essentially flat, or slightly curved (e.g., concave). These shape variations can be due to design features or manufacturing tolerances, while still achieving comparable average inclination values.

[0013] For the purposes of this disclosure, the term “average inclination” of the engagement section 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 centerline) connecting the thread root and thread crest (or their respective regions) of the engagement section of the trailing flank, relative to the longitudinal axis. This definition applies regardless of whether the engagement section is flat, substantially flat, or slightly curved.

[0014] For example, suppose that the segment of engagement extends from a foot point located 1.0 mm radially inward and 0.8 mm axially posteriorly from a vertex situated at a reference position (i.e., 0 mm radially and 0.0 mm axially). The chord can thus span a vertical (radial) difference of 1.0 mm and an axial difference of 0.8 mm. The average inclination θ is then calculated as follows: θ=arcutangens(1,0 / 0,8)≈51.3°

[0015] This representative inclination corresponds to the angle β and can be used to characterize the section of action independently of local curvature or irregularities.

[0016] Optionally, in some examples, including at least one preferred example, the steepness of the engagement section (the flat, essentially flat or slightly curved surface) is defined as the average steepness of the chord or centerline connecting the thread root and the thread vertex along the trailing flank (e.g., shortest distance between thread root and thread vertex) and the longitudinal axis.

[0017] Within the scope of this disclosure, the term “average steepness” of a flank refers to a representative inclination value for the entire flank or a defined section thereof. This average may be determined, for example, by the angle formed between a straight line (chord or centerline) connecting the thread root and the thread crest (or their respective regions) of the flank and the longitudinal axis, analogous to the definition of average inclination. Average steepness is used to characterize the general orientation of a flank for comparative purposes, for example, in determining whether the engagement section of the trailing flank is steeper or less steep than the leading flank. In contrast, the term “steepness” may refer to the local inclination angle of a flank section, such as the leading or trailing flank, relative to the longitudinal axis of the thread assembly.The steepness can vary along the height of the flank, especially in the case of non-flat or curved geometries.

[0018] In addition to the definitions given above, an engagement section may also be considered “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 (such as the corresponding flank of the thread of the filter housing) under operating load, results in distributed surface contact (as opposed to isolated point loads) and the cumulative width of the contact strips or areas exceeds a defined threshold, preferably more than 65% of the distance from the thread root to the thread apex along the trailing flank.This definition includes surfaces where intentional design features such as multi-angled facets, engineered ribbing, or shallowly curved segments have been introduced, provided that the total surface contact under load is functionally equivalent to that of a flat engagement section. In such cases, the contact area can be evaluated using a test surface (e.g., a flat reference surface) and taking into account the load-induced deformation. The "average slope" of such surfaces can alternatively be defined as the mean angle of all contact segments or sub-areas, measured with respect to the longitudinal axis when in contact with a flat reference surface. The average slope, in this context, can be measured as the mean slope of the contact sections 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 section of engagement and not just an idealized geometry, and allows for a reliable distinction between flat, essentially flat and curved configurations.

[0019] Optionally, in some embodiments, including at least one preferred embodiment, the engagement section is inclined with respect to the longitudinal axis by 45° to 57°, preferably by 45° to 55°, and more preferably by 46° to 50° or by 46° to 48°. A technical advantage may include a further improved force distribution with respect to the shear forces described above.

[0020] Optionally, in some embodiments, including at least one preferred embodiment, the thread root is defined as the first 10% of the thread height and the thread crest as the last 10% of the thread height, with the trailing flank being defined as extending from the thread root to the thread crest over 80% of the thread height. A technical advantage may include a satisfactory size of the engagement section and the associated intended contact area between the engagement section of the trailing flank and the corresponding flank of the thread of the filter housing when pressure is applied from the front end to the trailing end. The thread height may, for example, be defined as the height of the thread from the thread root to the thread crest. For instance, the thread height may be defined as the distance, such as the greatest distance, from the thread root to the thread crest.For example, the thread root or thread root region may comprise the first 10% of the thread height, typically extending from the lowest position of the thread root for 10% of the thread length in the direction of the thread height. Similarly, the thread crest or thread crest region may comprise the last 10% of the thread height, typically extending the last 10% of the thread to the highest position of the thread crest in the direction of the thread height. However, according to an alternative example, including at least one preferred example, the trailing flank is defined as extending from the thread root to the thread crest for at least 80%, for example, at least 90%, or for example, at least 95% of the thread height. The direction of the thread height may be defined as perpendicular or orthogonal to the longitudinal axis.For example, for a cross-section of the thread arrangement along the longitudinal axis, the longitudinal axis can be defined as the y-axis in a two-dimensional Cartesian coordinate system, and the thread height can extend along the x-axis of the two-dimensional Cartesian coordinate system, with the y-axis and the x-axis being orthogonal to each other.

[0021] Optionally, in some embodiments, including at least one preferred embodiment, the center point of the thread crown is offset by at least 0.05 pitch lengths, preferably at least 0.10 pitch lengths, from a position at 0.5 pitch lengths. A technical advantage may include an advantageous asymmetric structure of the first thread. The thread pitch can be defined as the distance between two adjacent thread crowns or two adjacent thread roots, e.g., between corresponding points of the two adjacent thread crowns or roots. The position of the center point of the thread crown relative to the pitch can be defined with respect to a thread pitch extending from corresponding centers of the two thread roots surrounding the thread crown.Thus, a thread crown center located at a position corresponding to 0.5 thread pitch, relative to a thread pitch extending from the corresponding centers of the two troughs surrounding the thread crown, corresponds to a symmetrically positioned thread crown (i.e., a thread crown that is symmetrical at least with respect to the position of said center point). By arranging the center point of the thread crown offset relative to the position corresponding to 0.5 thread pitch (i.e., for a thread pitch extending from the corresponding centers of the two thread roots surrounding the thread crown, which corresponds to a symmetrical thread crown), an asymmetric structure is achieved for the first thread, allowing for a less steep back flank compared to the average steepness of the front flank.Optionally, in some embodiments, including at least one preferred embodiment, the center point of the thread vertex is offset by at least 0.15 pitch length, preferably by at least 0.20 pitch length, from a position at 0.5 pitch length.

[0022] Optionally, in some embodiments, including at least one preferred embodiment, the engagement section of the rear flank has an axial extension of at least 0.30 thread pitch, preferably at least 0.35 thread pitch, and more preferably at least 0.40 thread pitch. A technical advantage may include a satisfactory size of the engagement section and the associated intended contact area between the engagement section of the rear flank and the corresponding flank of the thread of the filter housing when pressure is exerted from the front end to the rear end. The axial extension is typically defined as extending along the longitudinal axis.

[0023] Optionally, in some embodiments, including at least one preferred embodiment, the thread root and / or the thread crown are pointed. Optionally, in some embodiments, including at least one preferred embodiment, the thread root and / or the thread crown are flat or "flattened." For example, the thread crown may have an axial extension of at least 0.10 thread pitches, e.g., about 0.15 thread pitches, and / or the thread root may have an axial extension of at least 0.15 thread pitches, e.g., about 0.30 thread pitches. Additionally or alternatively, the trailing flank may have an axial extension greater than the axial extension of the leading end, e.g., by at least 0.10 thread pitches.

[0024] Optionally, in some embodiments, including at least one preferred embodiment, the front flank has a first axial extension, the rear flank a second axial extension, the thread crown a third axial extension, and the thread root a fourth axial extension, the sum of the first, second, third, and fourth axial extensions being equal to the thread pitch. As previously described, the thread pitch can be defined as the axial distance between two adjacent thread crowns or two adjacent thread roots.

[0025] Optionally, in some embodiments, including at least one preferred embodiment, the second axial extension is larger than the first axial extension. A technical advantage may include an advantageous structure to provide an engagement section of the rear flank that is less steep compared to the average steepness of the front flank with respect to the longitudinal axis. Since the axial extension of the rear flank is larger than the axial extension of the front flank, the engagement section of the rear flank can thus be more easily designed to be less steep than the average steepness of the front flank with respect to the longitudinal axis. Optionally, in some embodiments, including at least one preferred embodiment, the average steepness of the rear flank is less than the average steepness of the front flank.In other words, the steeper anterior flank may have an axial extent that is less than that of the less steep posterior flank.

[0026] Optionally, in some embodiments, including at least one preferred embodiment, the sum of the first axial extension, half of the third axial extension, and half of the fourth axial extension is less than 0.5 thread pitch, preferably less than 0.45 or less than 0.35 thread pitch, and the sum of the second axial extension, half of the third axial extension, and half of the fourth axial extension is greater than 0.5 thread pitch, preferably greater than 0.55 or greater than 0.65 thread pitch. A technical advantage may include an advantageous distribution of the axial extension (with respect to the thread pitch) between the rear flank and the front flank. This may provide an advantageous structure for a rear flank engagement section that, compared to the average steepness or...The slope of the front flank is less steep in relation to the longitudinal axis.

[0027] Optionally, in some embodiments, including at least one preferred embodiment, the third axial extension is equal to or less than 0.25 thread pitches, preferably equal to or less than 0.15 thread pitches, and / or the fourth axial extension is equal to or less than 0.20 thread pitches, preferably equal to or less than 0.15 thread pitches. A technical advantage may include a well-distributed axial extension between the trailing and leading flanks on the one hand, and the axial extension of the thread crown and / or root on the other. Generally, the thread crown may be referred to as the crown region and the thread root as the root region.

[0028] Optionally, in some embodiments, including at least one preferred embodiment, the average steepness of the front flank is between 13° and 42°, more preferably between 20° and 39°, steeper than the engagement section of the rear flank. A technical advantage may include a further improved force distribution with respect to shear forces, as described above. For example, the average steepness of the front flank is between 27° and 33° steeper than the engagement section of the rear flank. The comparison between the front flank and the engagement section of the rear flank can refer here to the average steepness of the engagement section.

[0029] Optionally, in some embodiments, including at least one preferred embodiment, the leading flank extends from a first thread crest to a first thread root, and the trailing flank extends from the first thread crest to a second thread root located axially behind the first thread root, the average steepness of the leading flank being determined from the first thread crest to the first thread root. Both the first thread crest and the first and second thread roots can be defined as described above.

[0030] In some embodiments, including at least one preferred embodiment, the average steepness of the leading edge with respect to the longitudinal axis is between 63° and 87°, preferably between 67° and 85°, and even more preferably between 71° and 81°. A technical advantage can be a further improved force distribution with respect to shear, as described above. For example, the average steepness of the leading edge with respect to the longitudinal axis is between 75° and 79°. Optionally, in some embodiments, including at least one preferred embodiment, the average steepness of the leading edge is between 63° and 79°, preferably between 67° and 79°, and even more preferably between 71° and 79°.

[0031] In some embodiments, including at least one preferred embodiment, the engagement section is optionally inclined between 42° and 57°, and the average steepness of the leading edge is between 63° and 87°; preferably, the engagement section is inclined between 43° and 54°, and the average steepness of the leading edge is between 67° and 85°; even more preferably, the engagement section is inclined between 45° and 51°, and the average steepness of the leading edge is between 71° and 81°, with respect to the longitudinal axis. For example, the engagement section is inclined between 46° and 48° or 50°, and the average steepness of the leading edge is between 75° and 79°.Optionally, in some embodiments, the engagement section is inclined between 42° and 57°, and the average steepness of the leading edge is between 63° and 79°; preferably, the engagement section is inclined between 43° and 54°, and the average steepness of the leading edge is between 67° and 79°; even more preferably, the engagement section is inclined between 45° and 51°, and the average steepness of the leading edge is between 71° and 79°, relative to the longitudinal axis. For example, the engagement section is inclined between 46° and 48° or 50°, and the average steepness of the leading edge is between 75° and 79°.

[0032] In some embodiments, including at least one preferred embodiment, the combined value of the inclination of the engagement section of the rear flank relative to the longitudinal axis and the inclination or average inclination of the front 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 between 123° and 125°.

[0033] Optionally, in some embodiments, including at least one preferred embodiment, the combined axial distance of the rear flank and the front flank (and optionally the thread crown and / or the thread root) is predetermined and fixed, independent of the steepness of the engagement section and the average steepness of the front flank.

[0034] Optionally, in some embodiments, including at least one preferred embodiment, the engagement section of the rear 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 flank corresponding to the rear flank. The engagement surface can, for example, extend along the entire engagement section. According to one example, the engagement section forms the entire rear flank. The engagement surface can therefore correspond to the previously described surface of the "flat," "substantially flat," and "slightly curved" engagement section.

[0035] Optionally, in some embodiments, including at least one preferred embodiment, the engagement surface of the rear flank is configured to contact the corresponding flank of the thread of the filter housing when the air filter cartridge is subjected to pressure in a direction from the front end to the rear end. Thus, when pressure is applied in the front-to-rear-end direction, the engagement surface described above can be brought into contact with a corresponding surface of the thread of the filter housing. This applies pressure in a direction opposite to the direction of the connection.

[0036] Optionally, in some embodiments, including at least one preferred embodiment, the thread arrangement is a multiple thread arrangement, further comprising a second thread extending helically along the longitudinal axis from the front end to the rear end and offset from the first thread, wherein the second thread is shaped according to the first thread or differs in shape from the first thread. A technical advantage may include improved positioning of the air filter cartridge relative to the filter housing, resulting, for example, in a simplified assembly process. The second thread may be offset relative to the first thread by a predefined value, e.g., by 180°. Thus, the starts of the first and second threads may be offset by a correspondingly predefined value, e.g., by 180°. This can improve the correct positioning for mounting the air filter cartridge on the filter housing (e.g.,This simplifies and / or speeds up the assembly process. Therefore, the assembly process can be improved in terms of time efficiency and user-friendliness.

[0037] Optionally, in some embodiments, including at least one preferred embodiment, the second thread comprises a thread crown, a thread root, a thread pitch, a thread height extending in the direction from the thread root to the thread crown, a front flank facing the front end for guiding the connection and having a contact section, and a rear flank facing the rear end, wherein the steepness of the contact section of the front flank with respect to the longitudinal axis is less than the average steepness of the rear flank with respect to the longitudinal axis, wherein the contact section extends over at least 65% of the thread height and is inclined with respect to the longitudinal axis between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51°.The effects and characteristics relating to the second thread of the threaded assembly are largely analogous to those described above in connection with the first thread, but for a pressure acting in the opposite direction to that described for the first thread (i.e., for a pressure acting from the rear end to the front end). This makes the threaded assembly particularly suitable for connection to low-pressure vessels, e.g.with pressure fluctuations, such as certain low-pressure air filters and oil filters. Thus, for embodiments mentioned with respect to the first thread and the rear flank, corresponding embodiments apply to the front flank of the second thread; for embodiments mentioned with respect to the first thread and the front flank, corresponding embodiments apply to the rear flank of the second thread; and for embodiments mentioned with respect to the first thread and the engagement section, corresponding embodiments apply to the contact section of the second thread. Thus, the contact section can be flat, substantially flat, or slightly curved, with a corresponding definition as a flat, substantially flat, or slightly curved engagement section.

[0038] It should be noted that the engagement section is defined as a section of the trailing flank. Furthermore, the trailing flank is defined as a section of the first thread that extends helically along a longitudinal axis from the front end to the trailing end, with the trailing flank facing the trailing end. In this context, the trailing flank and its engagement section naturally extend in at least two orthogonal directions: (i) longitudinally (i.e., along the longitudinal axis), following the helical course of the thread, and (ii) in a direction perpendicular or orthogonal to the longitudinal axis, in particular in the direction from the thread root to the thread crest, which is referred to as the "thread height". In other words, the trailing flank and its engagement section inherently have at least two components, a first component in the longitudinal direction (i.e.,along the longitudinal axis), which follows the helical path of the thread, and a second component in the direction perpendicular or orthogonal to the longitudinal axis, in particular in the direction from the thread root to the thread crest, which is referred to as the “thread height”. Therefore, when it is stated in the context of this disclosure that the engagement section extends over at least 65% of the thread height, this is to be understood as referring to the extent or component of the engagement section in the direction from the thread root to the thread crest, i.e., in the direction of the thread height. The stated percentage of the extent (at least 65%) refers to the extent or proportion of the engagement section that extends in the direction of the thread height.Since the trailing flank, and thus the engagement section, is part of a helically extending thread, it necessarily exhibits extensions in both the axial (longitudinal) and radial (height) directions. The specified minimum 65% therefore refers to the extension of the engagement section along the thread height. For example, in a cross-section of the thread assembly along the longitudinal axis and using the previously described two-dimensional Cartesian coordinate system, the component of the engagement section extending from the thread root to the thread crown, i.e., along the thread height, runs along the x-axis, and the component extending along the longitudinal axis runs along the y-axis.

[0039] It should be noted that the thread height refers to the distance between the thread root and the thread crown, measured in a direction perpendicular to the longitudinal axis of the thread assembly. In other words, the thread height extends radially outward from the thread root to the thread crown, not along the axial (longitudinal) direction of the thread.

[0040] The invention also relates to an air filter system according to claim 17. It comprises a filter housing and an air filter cartridge according to the invention. The invention with respect to the air filter system can aim to solve the same problem as described with respect to the air filter cartridge. Thus, the effects and features of the air filter system according to the invention are largely analogous to those described above in connection with the air filter cartridge according to the invention. The filter housing is typically an air filter housing. Thus, the filter housing comprises a corresponding first thread configured to engage with the first thread of the air filter cartridge, and optionally a corresponding second thread configured to engage with the second thread of the air filter cartridge.Thus, the filter housing can include a single-threaded arrangement configured to engage with the single-threaded arrangement of the air filter cartridge, or the filter housing can include a multi-threaded arrangement configured to engage with the multi-threaded arrangement of the air filter cartridge. As mentioned in relation to the first aspect, the first thread of the filter housing includes a flank that, during operational load, comes into contact with the engagement portion of the rear flank. Such a flank can be referred to as the engagement flank, the engagement flank being configured to engage with the engagement portion of the rear flank of the air filter cartridge.

[0041] Optionally, in some embodiments, including at least one preferred embodiment, a clearance of 0.001 to 0.1 thread pitches is provided at least between the first thread of the air filter cartridge and the thread of the filter housing. For example, the clearance may be between the corresponding thread root and thread crown pair of the first thread of the air filter cartridge and the thread of the filter housing. It is understood that when pressure is applied from the front end toward the rear end, there is typically no clearance between the engagement portion of the rear end of the air filter cartridge and the corresponding flank of the thread of the filter housing.

[0042] Furthermore, a filter housing is described. The filter housing comprises a threaded assembly for connection to a thread of an air filter cartridge, wherein the threaded assembly has a first end, a second end opposite the first end, and at least one first thread extending helically along a longitudinal axis from the first end to the second end, wherein the first thread has a thread crown, a thread root, a thread pitch, a thread height extending in the direction from the thread root to the thread crown, a first flank facing the first end, and a second flank facing the second end, which has a thread engagement section of the housing, wherein the steepness of the thread engagement section of the second flank with respect to the longitudinal axis is less than the average steepness of the first flank with respect to the longitudinal axis.wherein the threaded engagement section of the housing extends over at least 65% of the thread height and is inclined with respect to the longitudinal axis between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51°. The disclosure regarding filter housings may aim to solve the same problem as described for the air filter cartridge and air filter system according to the invention. Thus, the effects and features of this further aspect of the disclosure are largely analogous to those described above in connection with the devices according to the invention. The filter housing can be the one contained in the air filter system according to the invention. However, according to at least one example, the filter housing can be threaded in engagement with an air filter cartridge.which differs from the one according to the invention. Such an air filter cartridge should at least be compatible with the filter housing according to this disclosure. This compatibility allows at least the first thread of the threaded assembly of the air filter cartridge to engage with the first thread of the threaded assembly of the filter housing, e.g., by ensuring that, during operation or under operating load, at least 65% of the rear flank or the engagement section thereof of the first thread of the threaded assembly of the air filter cartridge is in contact with at least 65% of the thread engagement section of the second flank of the housing.

[0043] The invention further comprises a vehicle comprising any embodiment of the air filter system or any embodiment of the air filter cartridge according to the invention. The vehicle according to the invention may aim to solve the same problem as described for the air filter system, the air filter cartridge, or the filter housing. Thus, the effects and features of the vehicle are largely analogous to those described above in connection with the air filter system, the air filter cartridge, or the filter housing.

[0044] The disclosure further includes the use of an air filter cartridge in a filter housing. The air filter cartridge comprises a filter body and a threaded assembly for connection to a first thread of the filter housing, the threaded assembly having a front end, a rear end opposite the front end, and at least one first thread extending helically along a longitudinal axis from the front end to the rear end, the first thread having a thread crown, a thread root, a thread pitch, a thread height extending in the direction from the thread root to the thread crown, a front flank facing the front end for initiating the connection, and a rear flank facing the rear end with an engagement section, wherein the steepness of the engagement section of the rear flank with respect to the longitudinal axis is less than the average steepness of the front flank with respect to the longitudinal axis.wherein the engagement section extends over at least 65% of the thread height and is inclined with respect to the longitudinal axis between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51°. The use of an air filter cartridge in a filter housing according to the disclosure may aim to solve the same problem as described for the preceding aspects of the disclosure. Thus, the effects and features are largely analogous to those described above in connection with the preceding aspects of the disclosure, some embodiments of which are typically mentioned below without repeating the associated technical effect. The air filter cartridge can be the air filter cartridge according to the invention. The filter housing can be the filter housing designed according to the disclosure.The air filter cartridge and the filter housing can be those of the air filter system according to the invention. Thus, each of the examples and embodiments mentioned with regard to the air filter cartridge and / or the filter housing also applies to the use of an air filter cartridge in a filter housing.

[0045] Optionally, in some examples, including at least one preferred example, the first thread of the filter housing is screwed to the first thread of the air filter cartridge.

[0046] Optionally, in some embodiments, including at least one preferred embodiment, the first thread of the filter housing comprises an engagement flank configured to engage with the engagement section of the rear flank of the air filter cartridge.

[0047] Optionally in some embodiments, including at least one preferred embodiment, when pressure is applied to the air filter cartridge from the front end towards the rear end, the engagement section of the rear flank is brought into contact with the engagement flank of the first thread of the filter housing to ensure a seal.

[0048] In some embodiments, including at least one preferred embodiment, the engagement flank is flat and inclined with respect to the longitudinal axis by 42° to 57°, preferably by 43° to 54°, more preferably by 45° to 51°.

[0049] Optionally, in some embodiments, including at least one preferred embodiment, the engagement section of the rear flank is flat and inclined with respect to the longitudinal axis between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51°.

[0050] Optionally, in some embodiments, including at least one preferred embodiment, the contact between the engagement flank and the flat, substantially flat or slightly curved engagement section of the rear flank extends over at least 65% of the thread height when the air filter cartridge is subjected to pressure acting from the front end to the rear end.

[0051] The disclosure further relates to the use of an air filter cartridge in a filter housing. The filter housing comprises a threaded assembly for connection to a thread of the air filter cartridge, the threaded assembly having a first end, a second end opposite the first end, and at least one first thread extending helically along a longitudinal axis from the first end to the second end, the first thread having a thread crown, a thread root, a thread pitch, a thread height extending in the direction from the thread root to the thread crown, a first flank facing the first end, and a second flank facing the second end, which has a thread engagement section of the housing, wherein the steepness of the thread engagement section of the second flank with respect to the longitudinal axis is less than the average steepness of the first flank with respect to the longitudinal axis.wherein the thread engagement section of the housing extends over at least 65% of the thread height and is inclined with respect to the longitudinal axis between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51°. The use of an air filter cartridge in a filter housing according to the disclosure can aim to solve the same problem as described for the preceding aspects of the disclosure. Therefore, the effects and features of using an air filter cartridge in a filter housing according to the disclosure are largely analogous to those described above in connection with the preceding aspects of the disclosure, some embodiments of which are typically mentioned below without repeating the associated technical effect. The air filter cartridge can be the one according to the invention. The filter housing can be the filter housing designed according to the disclosure.and the air filter cartridge and the filter housing can be those of the air filter system according to the invention.

[0052] Optionally, in some examples, including at least one preferred example, the air filter cartridge is compatible with the filter housing. This compatibility allows at least the first thread of the threaded assembly of the air filter cartridge to engage with the first thread of the threaded assembly of the filter housing, for example, by ensuring that, during operation or under operating load, at least 65% of the rear flank (or the engagement portion thereof) of the first thread of the air filter cartridge threaded assembly is in contact with at least 65% of the thread engagement portion of the second flank of the threaded assembly of the filter housing.

[0053] Optionally, in some embodiments, including at least one preferred embodiment, the first thread of the filter housing engages with the first thread of the air filter cartridge.

[0054] Optionally, in some embodiments, including at least one preferred embodiment, the second flank is an engagement flank configured to come into contact with an engagement section of a rear flank of a threaded assembly of the air filter cartridge.

[0055] Optionally in some embodiments, including at least one preferred embodiment, when pressure is applied to the air filter cartridge from the second end towards the first end, the engagement section of the rear flank is brought into contact with the engagement flank of the first thread of the filter housing to ensure a seal.

[0056] In some embodiments, including at least one preferred embodiment, the thread engagement section of the second flank is flat or substantially flat.

[0057] According to a further aspect of the disclosure, the foregoing aspects of the disclosure (including the air filter cartridge and the air filter system according to the invention) are provided for a filter cartridge, including, but not limited to, an air filter cartridge. Thus, for each of the foregoing aspects of the disclosure, the feature "air filter cartridge" can be replaced by the feature "filter cartridge." For example, the filter cartridge can be an oil filter cartridge. For example, the filter cartridge and / or the filter housing of the further aspect can be particularly suitable for connection to low-pressure vessels, e.g., with pressure fluctuations, such as certain low-pressure air filters and oil filters.

[0058] The disclosed aspects, examples (including any preferred examples) and / or the attached claims can be combined in a suitable manner as would be obvious to a person skilled in the art. Further features and advantages are disclosed in the following description, the claims, and the drawings, and some will be immediately apparent to a person skilled in the art or will be recognized through practical application of the disclosure described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Examples are described in more detail below with reference to the attached drawings. Fig. Figure 1 is an exemplary, partially schematic side view of a vehicle that includes an air filter system according to an example. Fig. 2 is an exemplary, partially schematic side view of the air filter system, which consists of an air filter cartridge and a filter housing made of Fig. 1 according to an example. Fig. Figure 3 is a cross-sectional view of a section of the threaded arrangements of the air filter cartridge and filter housing according to an example. Fig. Figure 4 is a cross-sectional view of a section of the threaded arrangements of the air filter cartridge and the filter housing according to one embodiment. Fig. Figure 5 is an exemplary, partially schematic perspective view of a thread arrangement of the air filter cartridge according to an example. Fig. Figure 6 shows cross-sectional views of sections of the threaded arrangements of the air filter cartridge and filter housing according to an example. Fig. Figure 7 shows cross-sectional views of various examples of the thread arrangement of the air filter cartridge. Fig. Figure 8 is a cross-sectional view of an example of the thread arrangement of the air filter cartridge. Fig. Figure 9 is a cross-sectional view of an example of the thread arrangement of the air filter cartridge. Fig. Figure 10 is a cross-sectional view of an example of the thread arrangement of the air filter cartridge. Fig. Figure 11 is a cross-sectional view of an example of the thread arrangement of the air filter cartridge. DETAILED DESCRIPTION

[0060] The detailed description below contains information and examples of the disclosed technology, which are so comprehensive that it is possible for a person skilled in the art to put the disclosure into practice.

[0061] The disclosed technology can solve the problem associated with the unintentional detachment of the air filter cartridge from the filter housing. The disclosed technology offers an improved thread arrangement in which the first thread is designed to ensure, on the one hand, a balanced distribution of at least the radial shear forces and, on the other hand, a balanced size of the engagement section and the intended associated contact area between the engagement section and the thread of the filter housing. Typically, the thread arrangement provides an engagement section large enough to ensure a strong thread, or at least a thread that will not break or wear prematurely, and that ensures a sufficient seal between the filter housing and the air filter cartridge.In other words, the combination of an engagement section of the rear flank that is less steep than the average steepness of the front flank, and wherein the engagement section is inclined at an angle between 42° and 57°, preferably between 43° and 54°, better still between 45° and 51° with respect to the longitudinal axis, provides a thread arrangement that achieves a balanced distribution with respect to at least the radial force of the shear forces on the one hand (and the associated induced shear forces) and the potential contact area between the engagement section and the thread of the filter housing on the other. A technical advantage may include an improved balance between the radial force of the shear forces and the size of the engagement section (as well as the associated resulting contact area between the engagement section and the thread of the filter housing).Another technical advantage can be reduced wear on the threaded assembly. A further technical advantage can be a tight seal at the rear flank when the air filter cartridge is subjected to pressure from the front end to the rear end.

[0062] Fig. Figure 1 shows an exemplary vehicle 1000, here designed as a heavy-duty truck 1000, according to an example. The vehicle 1000 comprises an internal combustion engine 1010, such as a hydrogen combustion engine or a diesel combustion engine, for powering the vehicle 1000, as well as an air filter system 1001 for filtering air. The air filter system 1001 comprises a filter housing 1003 and an air filter cartridge 1002. Typically, the air filter cartridge 1002 includes an air filter that must be replaced during maintenance work, and thus the air filter cartridge 1002 is detachably attached to the filter housing 1003 by appropriate threaded connections. The air filter system 1001 is in Fig. Figure 1 is shown schematically only. It should be noted that the vehicle 1000 can be a hybrid vehicle, which further includes an electric drive motor (optional) for propelling the vehicle 1000. The internal combustion engine 1010 and the optional electric drive motor are typically arranged and configured to propel the vehicle 1000 individually by being coupled separately to other parts of the vehicle 1000's powertrain, such as a transmission, drive shafts, and wheels (not shown in detail). The operation of the internal combustion engine 1010 and the optional electric drive motor can be controlled by a control unit 1117, such as an ECU.

[0063] In Fig. Figure 2 shows the air filter system 1001, comprising the filter housing 1003 and the air filter cartridge 1002, in more detail. The air filter cartridge 1002 comprises a filter body 1002a and a threaded assembly 1 for connection with a corresponding threaded assembly 1' of the filter housing 1003. The filter body 1002a typically comprises a disposable air filter. The threaded assembly 1 of the air filter cartridge 1002 is designed such that it can be screwed onto the threaded assembly 1' of the filter housing 1003 along a longitudinal axis A, which here also serves as the screw axis. As also shown in Figure 2, the air filter system 1001 comprises a filter body 1002a and a threaded assembly 1 for connection with a corresponding threaded assembly 1' of the filter housing 1003. Fig. As shown in Figure 2, a pressure P (such as sustained internal pressure or overpressure) or any other corresponding pull-out force can be exerted on the air filter cartridge 1002, resulting in a force directed inwards from the filter housing 1003 towards the air filter cartridge 1002, creating a risk that the air filter cartridge 1002 will be torn out and detached from the filter housing 1003.

[0064] In Fig. Figure 1 shows a cross-sectional view of a section of the threaded assembly 1 of the air filter cartridge 1002 and the threaded assembly 1' of the filter housing 1003. The two threaded assemblies 1 and 1' are shown separately for clarity.

[0065] The threaded assembly 1 extends from a front end 1a to a rear end 1b, which is opposite the front end 1a. The threaded assembly 1 includes a first thread 10 that extends helically along the longitudinal axis A from the front end 1a to the rear end 1b. The first thread 10 is configured to engage with a corresponding thread 20 (e.g., a corresponding first thread 20) of the threaded assembly 1' of the filter housing 1003.

[0066] As in Fig. As shown in Figure 3, the first thread 10 of the threaded assembly 1 of the air filter cartridge 1002 consists of a structure comprising a threaded crown 11, a threaded root 12, a thread pitch p, a thread height H extending from the threaded root 12 to the threaded crown 11, a front flank 13 facing the front end 1a for initiating the connection of the air filter cartridge 1002 to the filter housing 1003, and a rear flank 14 facing the rear end 1b. The rear end has a flat engagement section 14', which will be described in more detail later. More precisely, the first thread 10 comprises a first threaded crown 11a, a first threaded root 12a, and a second threaded crown 11b that adjoins and trails the first threaded crown 11a in the axial direction (i.e.,(compared to the first threaded vertex 11a, which is located closer to the rear end 1b and along the longitudinal axis), and a second threaded root 12b, which adjoins and trails behind the first threaded root 12a. Accordingly, a first front flank 13a extends from the first threaded vertex 11a to the first threaded root 12a, and a first rear flank 14a extends from the first threaded vertex 11a to the second threaded root 12b. Thus, the front flank 13a guides the screwing in of the first thread 10 relative to the thread 20 of the filter housing 1003 when the air filter cartridge 1002 is screwed onto the filter housing 1003.

[0067] The first thread 10 can be constructed from successive front flanks 13 and rear flanks 14, corresponding to the first front flanks and rear flanks 13a, 14a described above. For example, as shown in Fig. Figure 3 shows a second front flank 13b from the second threaded base 12a to the second crest 11b. In the example of Fig. 3 The thread pitch p extends from the first thread vertex 11a to the second thread vertex 11b. For the sake of simplicity, reference is made below to "the thread vertex 11", the "thread root 12", "the front flank 13" and "the rear flank 14", which in each case means one or all of the corresponding thread vertex 11, thread root 12, front flank 13 and rear flank 14 of the thread 10, or at least the first thread vertex 11a, the first thread root 12a, the first front flank 13a and the first rear flank 14a.

[0068] The thread root 12 can be referred to as the thread root region and defined, for example, as the first 10% of the thread height H. Similarly, the thread crest 11 can be referred to as the thread crest region and defined, for example, as the last 10% of the thread height H. Thus, the trailing flank 14 can be defined as extending over 80% of the thread height H from the thread root 12 to the thread crest 11. Similarly, the leading flank 13 can be defined as extending over 80% of the thread height H from the thread crest 11 to the thread root 12. As in Fig. As shown in Figure 3, the thread crown 11 and the thread root 12 are tapered and have minimal axial extension, but can also be shaped differently, e.g. with associated flat sections extending along the longitudinal axis (as in Figure 3). Fig. 4 shown). The thread crown and thread root can alternatively be slightly curved or have slightly curved sections.

[0069] The one in relation to Fig. The pressure P described in section 2 is also in Fig. Figure 3 shows the threaded assembly extending in one direction from the front end 1a to the rear end 1b, typically along the longitudinal axis A of the threaded assembly (but opposite to the direction of the threaded connection). When such a pressure P is applied, the resulting force brings the first thread 10 of the threaded assembly 1 of the air filter cartridge 1002 into contact with the corresponding thread 20 of the threaded assembly 1' of the filter housing 1003. This brings the engagement section 14' of the rear flank 14 into contact with a flank 24 of the thread 20 of the filter housing 1003 that corresponds to that of the rear flank 14. More precisely, the engagement section 14' of the rear flank 14 forms an engagement surface 14a' that is brought into contact with the flank 24 of the filter housing 1003. This causes the threaded arrangements 1, 1' to seal the air filter cartridge 1002 against the filter housing 1003. However, if the pressure P is too high, e.g.Above a predetermined threshold, the resulting force can cause the first thread 10 to disengage from the thread 20 of the filter housing 1003, resulting in the unintentional detachment of the air filter cartridge 1002 from the filter housing 1003. Therefore, the engagement section 14', which is designed to contact the corresponding flank 24 of the filter housing 1003, is preferably large enough to ensure a tight thread engagement to prevent the air filter cartridge 1002 from unintentionally detaching from the filter housing 1003, and / or to prevent premature breakage or wear of the first thread 10, which can also lead to the unintentional detachment of the air filter cartridge 1002 from the filter housing 1003.

[0070] Typically, the resulting force P of the pressure exerted on the air filter cartridge 1002 leads to shear forces between the engagement section 14' and the corresponding flank 24 of the filter housing 1003. These shear forces can be divided into an axial component (i.e., along the longitudinal axis A, also referred to as the vertical force) and a component transverse to the axial direction (i.e., radially along the thread height H), the latter being referred to as the radial force. To ensure a satisfactory seal between the air filter cartridge 1002 and the filter housing 1003, to prevent unintentional loosening of the air filter cartridge 1002 from the filter housing 1003 as previously described, and to guarantee a tight seal at the rear flank when pressure is exerted from the front end to the rear end, these force components should be balanced or at least matched.

[0071] As in Fig. As can be seen in Figure 3, the steepness of the flat engagement section 14' of the rear flank 14 with respect to the longitudinal axis A is less than the average steepness of the front flank 13 with respect to the longitudinal axis A. Since the engagement section 14' extends over at least a large part of the rear flank 14, defined here as at least 65% of the thread height H, the first thread 10 is designed to ensure a balanced distribution of shear forces (at least the radial force) and contact area between the engagement section 14' and the flank 24 of the filter housing 1003. This prevents, or at least reduces, the risk of, the air filter cartridge 1002 unintentionally detaching from the filter housing 1003, for example, due to premature breakage or premature wear of the first thread 10.Furthermore, an advantageous tight seal is achieved at the rear flank 14, which is based on the contact between the engagement section 14' and the flank 24 of the filter housing 1103 when the air filter cartridge is subjected to pressure from the front end 1a to the rear end 1b. The inventor(s) have recognized that a suitable angle of inclination β between the engagement section 14' of the rear flank 14 and the longitudinal axis A lies between 42° and 57°, preferably between 43° and 54°, and more preferably between 45° and 51°. For example, the inclination β can 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 shallow engagement section 14' of the rear flank 14 is approximately 48°.

[0072] The threaded arrangement 1' of the filter housing 1003 is thus designed for connection to the thread 10 of the air filter element 1002. The threaded arrangement 1' can comprise a first end 1'a, a second end 1'b opposite the first end 1'a, and at least the first thread 20, which extends helically along the longitudinal axis A' from the first end 1'a to the second end 1'b. When the air filter cartridge 1002 is screwed to the filter housing 1003, as shown in Fig. As shown in Figure 2, the two longitudinal axes A and A coincide and can simply be referred to as longitudinal axis A. Corresponding to the first thread 10 of the air filter cartridge 1002, the first thread 20 of the filter housing 1003 comprises a thread crest 11', a thread root 12', a thread pitch p', a thread height H' extending from the thread root 12' to the thread crest 11', a first flank 23 facing the first end 1'a, and a second flank 24 facing the second end 1'b, which has a thread engagement section 24' of the housing. The second flank 24 is thus the previously described "corresponding flank 24". As in Fig. As shown in Figure 11, the steepness of the housing thread engagement section 24' of the second flank 24 with respect to the longitudinal axis A' is less than the average steepness of the first flank 23 with respect to the longitudinal axis A'. The housing thread engagement section 24' extends over at least 65% of the thread height H and is inclined with respect to the longitudinal axis A' by β' between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51°. It should be noted that, in order for the air filter cartridge 1002 to 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 can be defined, for example, by the fact that, in use or under operating load, at least 65% of the rear flank or engagement section of the same of the first thread of the thread arrangement 1 of the air filter cartridge 1002 is in contact with at least 65% of the housing thread engagement section 24' of the second flank 24.

[0073] In Fig. Figure 4 shows a cross-sectional view of a section of an alternative thread arrangement 101 of the air filter cartridge 1002 and an alternative thread arrangement 101' of the filter housing 1003. The two thread arrangements 101 and 101' are shown separately for clarity and essentially correspond to the two thread arrangements 1 and 1' from [reference missing]. Fig. 3. For identical features, the same reference symbols are used, but with an additional value of "100" for each feature, i.e., "thread arrangement 1" from Fig. 3 refers to “thread arrangement 101” from Fig. 4 etc.

[0074] The threaded assembly 101 extends from a front end 101a to a rear end 101b and includes a first thread 110 that extends helically along the longitudinal axis A from the front end 101a to the rear end 101b. The first thread 110 is configured to engage with a corresponding thread 120 (e.g., a corresponding first thread 120) of the threaded assembly 101' of the filter housing 1003.

[0075] As in Fig. As shown in Figure 4, the first thread 110 of the threaded assembly 101 of the air filter cartridge 1002 consists of a structure comprising a threaded crown 111, a threaded root 112, a thread pitch p, a thread height H extending from the threaded root 112 to the threaded crown 111, a front flank 113 facing the front end 101a for inserting the air filter cartridge 1002 into the filter housing 1003, and a rear flank 114 facing the rear end 101b, the rear end having a flat engagement section 114' similar to that of the first thread 10 of the threaded assembly 1. Fig. 3, which is why it will not be described in detail again here.

[0076] As in Fig. As shown in Figure 4, the front flank 113 has a first axial extension d1, the rear flank 114 a second axial extension d2, the thread crown 111 or thread crown region a third axial extension d3, and the thread root 112 or thread root region a fourth axial extension d4. Corresponding axial distances are also shown in Fig. 3, but as previously described, the thread crown 11 and the thread root 12 are tapered here with a minimal axial extension for the third and fourth axial extensions d3, d4. The sum of the first, second, third, and fourth axial extensions d1, d2, d3, d4 corresponds to the thread pitch p. The third axial extension d3 can, for example, be equal to or less than 0.25 thread pitch p, preferably equal to or less than 0.15 thread pitch p, and / or the fourth axial extension d4 can, for example, be equal to or less than 0.20 thread pitch p, preferably equal to or less than 0.15 thread pitch p. In the non-restrictive example of Fig. 4. Each of the third and fourth axial extensions d3, d4 is approximately 0.13 thread pitch p. The third and fourth axial extensions d3, d4 can be the same or different from each other.

[0077] According to the first thread 10 from Fig. 3 and with respect to the pressure P in a direction from the front end 101a to the rear end 101b, the steepness of the flat engagement section 114' of the rear flank 114 with respect to the longitudinal axis A of the first thread 110 is Fig. 4 smaller than an average steepness of the front flank 113 with respect to the longitudinal axis A. As with the first thread 10, this extends from Fig. 3, the engagement section 114' along at least a major part of the rear flank 114, which here is defined as along at least 65% of the thread height H, is the first thread 110 made of Fig. 4 is designed to ensure a balanced distribution of shear forces (e.g., radial force) and contact area between the engagement section 114' and the flank 124 of the filter housing 1003. This prevents or at least reduces the risk of unintentional detachment of the air filter cartridge 1002 from the filter housing 1003, e.g., due to premature breakage or premature wear of the first thread 110. The inclination β between the flat engagement section 114' of the rear flank 114 and the longitudinal axis A can be the same as in the one described in Fig. 3. Example shown, i.e., between 42° and 57°, preferably between 43° and 54°, even more preferably between 45° and 51°. In the non-restrictive example of Fig. 4 the shallow engagement section 114' of the rear flank 114 is approximately 42°.

[0078] Referring to both Fig. 3 as well Fig. 4 The first thread 10, 110 is asymmetrical in that the first thread 10, 110 is arranged with a pitch of the engagement section 14', 114' of the rear flank 14, 114 that is smaller than the average pitch of the front flank 13, 113. Thus, the first thread 10, 110 differs from a standard metric ISO thread. For example, the engagement section 14', 114' of the rear flank 14, 114 can have an axial extent of at least 0.30 thread pitch p, preferably at least 0.35 thread pitch p, and more preferably at least 0.40 thread pitch p.

[0079] As in Fig. As shown, the first thread 110 can be defined asymmetrically by features other than the steepness of the engagement section 114' relative to the average steepness of the leading flank 113. For example, a center point m of the thread crown 111 can be offset by at least 0.05 thread pitch p, preferably at least 0.10 thread pitch p, from a position at 0.5 thread pitch p. The position of the center point m of the thread crown 111 relative to the thread pitch p can, for example, be defined with respect to a thread pitch extending from the corresponding centers of the two thread roots 112 surrounding the thread crown 111. With such a definition, a center point of the thread crown at a position at 0.5 thread pitch would thus correspond to a symmetrical thread crown, at least with respect to the position of its center point, which would be the case for a standard metric ISO thread.By positioning the center point m of the thread vertex 111 offset from the position at 0.5 thread pitch p, an asymmetry is achieved for the first thread 110, which allows for a less steep engagement section 114' of the rear flank 114 compared to the average steepness of the front flank 113. As in . Fig. As shown in Figure 4, the center point m of the thread vertex 111 is offset by approximately 0.20 thread pitch p relative to a position at 0.5 thread pitch p.

[0080] As in both Fig. 3 as well as in Fig. As shown in Figure 4, the second axial extension d2 is larger than the first axial extension d1. Thus, the rear flank 14, 114 extends along the longitudinal axis A over a greater distance compared to the front flank 13, 113. This results in an advantageous structure for providing a shallow engagement section 14', 114' of the rear flank 14, 114, which is less steep compared to the average steepness of the front flank 13, 113 with respect to the longitudinal axis A.

[0081] For example, the sum of the first axial extension d1, half of the third axial extension d3, and half of the fourth axial extension d4 is less than 0.5 thread pitch p, preferably less than 0.45 thread pitch p or less than 0.35 thread 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 greater than 0.5 thread pitch p, preferably greater than 0.55 thread pitch p or greater than 0.65 thread pitch p. As both in Fig. 3 as well as in Fig. As shown in Figure 4, the second axial extension d2 is at least twice as large as the first axial extension d1, and as shown in Figure 4. Fig. As shown in Figure 4, the second axial extension d2 can even be three times as large as the first axial extension d1.

[0082] Referring to both Fig. 3 as well Fig. 4. The average steepness of the front flank 13, 113 with respect to the longitudinal axis A, specified by the angle α, can be between 63° and 87°, preferably between 67° and 85°, more preferably between 71° and 81°. In other words, the average steepness of the front flank 13, 113 can be between 6° and 45°, preferably between 13° and 42°, more preferably between 20° and 39° steeper than the shallow engagement section 14', 114' of the rear flank 14, 114. In the non-restrictive example of Fig. 3 the average steepness of the front flank 13 is approximately 72°, and in the non-restrictive example of Fig. 4. The average steepness of the front flank 113 is approximately 70°. The average steepness of the front flank 13, 113 is typically defined as the average inclination of the front flank 13 relative to the longitudinal axis A, from the thread crest 11, 111 to the thread root 12, 112. This is based on the first thread crest 11a and the first thread root 12a in Fig. 3 For example, the average steepness of the first front flank 13a from the first thread crest 11a to the first thread root 12a can be determined.

[0083] Let us now turn Fig. Figure 5 shows an alternative example of a thread arrangement 201 for the air filter cartridge 1002. Thus, the air filter cartridge 1002 can be fitted with thread arrangement 201 instead of thread arrangement 1. Fig. 3 or the thread arrangement 101 from Fig. 4. The thread arrangement 201 is a multiple thread arrangement 201 comprising a first thread 210 and a second thread 230 extending helically along a longitudinal axis A from a front end 201a to a rear end 201b. The first thread 210 can be compared to the first thread 10 of the example in Fig. 3 or the first thread 110 of the example in Fig. 4 correspond to or be identical with these. The second thread 230 is offset from the first thread 210. The second thread 230 can 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 threads 210 and the start 230a of the second thread 230 can be offset by a corresponding predefined value, e.g., by 180°, as in Fig. 5 shown.

[0084] The second thread 230 can be shaped like the first thread 210 or differ in shape from the first thread 210. Thus, the second thread 230 can extend from the front end 201a to the rear end 201b in the same way as the first thread 210. Therefore, the first thread 210 and the second thread 230 can be shaped accordingly.

[0085] If the second thread 230 is shaped differently compared to the first thread 210, the second thread 230 can have a similar thread structure, but with opposite characteristics for the rear and front flanks. Such a thread structure is found in Fig. Figure 6 shows a cross-sectional view on the left of a section of the threaded assembly 201 comprising the first thread 210 and a threaded assembly 201' of the filter housing 1003 comprising a corresponding first thread 220, and a cross-sectional view on the right of a section of the threaded assembly 201 comprising the second thread 230 and the threaded assembly 201' comprising a corresponding second thread 240. The first thread 210 of the threaded assembly 201 is configured to engage with the first thread 220 of the filter housing 1003 in a threaded engagement as described in Figure 6. Fig. 3 and Fig. It was described in section 4 and will therefore not be described again in detail here. Thus, the reference numerals for the first thread 210 correspond to those for the first thread 10 from [reference missing]. Fig. 3. The second thread 230 of the threaded assembly 201 is designed such that it engages with the second thread 240 of the filter housing 1003. The first threads 210, 220 of the two threaded assemblies 201, 201' and the second threads 230, 240 of the two threaded assemblies 201, 201' are shown separately for clarity.

[0086] The second thread 230 comprises a thread crown 231, a thread root 232, a thread pitch p, a thread height H extending from the thread root 232 towards the thread crown 231, a front flank 233 facing the front end 201a, preceding the connection and having a flat or substantially flat contact section 233', and a rear flank 234 facing the rear end 201b. As shown in Fig. As shown in Figure 5, the steepness of the flat or substantially flat contact section 233' of the front flank 233 with respect to the longitudinal axis A is less than the average steepness of the rear flank 233 with respect to the longitudinal axis A, wherein the flat or substantially flat contact section 233' extends over at least 65% of the thread height H and is inclined with respect to the longitudinal axis A at an angle α2 between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51°. Thus, the effects and features with respect 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, except for an exerted pressure P2 in the opposite direction to that described above. Fig. 3 and Fig. 4 described, i.e., a pressure P2 from the rear end 201b to the front end 201a. Thus, the threaded arrangements 201, 201' seal the air filter cartridge 1002 against the filter housing 1003 regardless of the pressure direction. As in the examples of Fig. 3 and Fig. As shown in Figure 4, the front flank 13, 113 can have a corresponding flat or substantially flat contact section 13', 113'.

[0087] In each of the examples described here, there can be a clearance of at least 0.001 to 0.1 of the thread pitch p 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, there can be clearance between the corresponding pair of thread root and thread crown 11, 111, 231 or 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.

[0088] Fig. Figure 7 shows various alternatives of the inclination of the engagement section 14' and the average steepness (or average inclination) of the front flank 13 with reference to the first thread 10 of the Fig. 3 described thread arrangement 1. All in Fig. The 7 examples shown are embodiments.

[0089] From left to right and from top to bottom, the inclination β between the engagement section 14' of the rear flank 14 and the longitudinal axis A decreases from 57° to 42°, while the inclination α (average inclination corresponding to the average steepness) of the front flank 13 and the longitudinal axis A increases from 63° to 87°. Referring to the example in the upper left corner, the shear forces F are shown, where the shear forces F are present when a pressure P is exerted from the front end 1a to the rear end 1b, causing the engagement section 14' to come into contact with the corresponding flank 24 of the filter housing 1003, as previously described. The radial component of the shear forces F is denoted by F1, and the vertical component of the shear forces F is denoted by F2. As from Fig. As can be seen in Figure 7, the radial component F1 of the shear forces F increases with decreasing inclination β and increasing inclination α (the shear forces F, F1, F2 are only shown in the example in the upper left corner, in the middle example, and in the example in the lower right corner, but implicitly apply to the other examples as well). The vertical component F2 of the shear forces F remains constant in the examples of Fig. 7 constant. An increased radial force F1 typically corresponds to an increased load on the thread 10. Therefore, it is advantageous to keep the radial force F1 low. However, as also from Fig. As can be seen, the size of the engagement section 14', and thus the contact area between the engagement section 14' and the corresponding flank 24 of the filter housing 1003, increases with increasing inclination β and decreasing inclination α. ​​A larger engagement section 14' (and the associated larger contact area) typically corresponds to an increased sealing effect. Therefore, a large engagement section 14' is preferred.

[0090] Therefore, the choice of at least the angle of inclination β between the engagement section 14' of the rear flank 14 and the longitudinal axis A is important. The inventors have recognized that a balanced distribution with respect to the radial force F1 of the shear forces F on the one hand and the size of the engagement section 14' (as well as the associated intended contact area between the engagement section 14' and the thread 24 of the filter housing 1003) is achieved, and that this is further improved with an inclination β between 42° and 57°, is further improved with an inclination β between 43° and 54°, and is improved even further with an inclination β between 45° and 51°, e.g., between 46° and 48°. Thus, the load on the thread 10 is kept relatively low, while at the same time a tight seal on the rear flank 14 is ensured when pressure is exerted from the front end 1a to the rear end 1b.

[0091] As also in Fig. As shown in Figure 7, the combined axial distance of the rear flank 14 and the front flank 13 is the same in all examples. Fig. 7 is the same. Therefore, if the inclination β between the engagement section 14' of the rear flank 14 and the longitudinal axis A decreases, the inclination α of the front flank 13 increases from 63° to 87°. Therefore, the shear body is in all examples in Fig. even.

[0092] Fig. Figure 1 shows a cross-section of an embodiment of the first thread 410 of the threaded arrangement 1 of the air filter cartridge 1002. All features except the rear flank 414 and the engagement section 414' correspond to those of the first thread 10 from Figure 2. Fig. , which is why the same reference symbols are used for the corresponding features. However, instead of being flat (with perfect flatness) like the engagement section 14' of the in Fig. As in the example shown, the engagement section 414' is essentially flat (i.e., with minor deviations from perfect flatness). The essentially flat engagement section is defined here by a maximum offset with respect to the average steepness of the trailing flank, represented by the dashed line from the thread root 12 (12b) to the thread crest 11 (11a), i.e., the shortest distance between the thread root and thread crest, of less than Y mm. Since the Fig. When the pressure P described in section 2 is exerted in a direction from the front end to the rear end, typically along the longitudinal axis A (but opposite to the direction of the threaded connection), the resulting force brings the first thread 410 of the threaded assembly 1 of the air filter cartridge 1002 into contact with the corresponding thread 20 of the threaded assembly of the filter housing 1003. This brings the engagement section 414' of the rear flank 414 into contact with a flank 24 of the thread 20 of the filter housing 1003, which corresponds to the rear flank 414. This flank 24 can be referred to as the engagement flank 24 and is preferably flat. More precisely, the engagement section 414' of the rear flank 414 forms an engagement surface 414a' that is brought into contact with the engagement flank 24 of the filter housing 1003. This ensures that the threaded arrangements seal the air filter cartridge 1002 against the filter housing 1003.Since the engagement section 414' is essentially flat, the sections that deviate from the average steepness of the trailing flank—represented by the dashed line from the thread root 12 to the thread crown 11—can be easily deformed or cause the engagement flank 24 to be slightly deformed when the pressure P is applied as previously described. Thus, all or at least most of the engagement section 414' or the engagement surface 414a' is brought into contact with the engagement flank 24.

[0093] The inclination β between 42° and 57°, or between 43° and 54°, or between 45° and 51°, e.g. between 46° and 48°, is shown here as the inclination between the average steepness of the rear flank, represented by the dashed line from the thread root 12 to the thread crown 11, and the longitudinal axis A.

[0094] In Fig. A cross-sectional view of another example of the first thread 510 of the thread arrangement 1 of the air filter cartridge 1002 is shown. All features except the rear flank 514 and the engagement section 514' correspond to those of the first thread 10 from Fig. 3, which is why the same reference symbols are used for the corresponding features. However, instead of being flat (with perfect flatness) like the engagement section 14' of the in Fig. In the example shown in Figure 3, the intervention section 514' is slightly curved. In the example of Fig. 9 is the curvature of the engagement section 514' concave. The slightly curved engagement section is defined here by a maximum offset with respect to the average steepness of the trailing flank, represented by the dashed line from the thread root 12 to the thread vertex 11 (i.e., the shortest distance between the thread root 12b and the thread vertex 11a), of less than X mm. Since the in relation to Fig. When the pressure P described in section 2 is exerted in a direction from the front end to the rear end, typically along the longitudinal axis A (but opposite to the direction of the threaded connection), the resulting force brings the first thread 510 of the threaded assembly 1 of the air filter cartridge 1002 into contact with the corresponding thread 20 of the threaded assembly of the filter housing 1003. This brings the engagement section 514' of the rear flank 514 into contact with a flank 24 of the thread 20 of the filter housing 1003, which corresponds to the rear flank 14. This flank 24 can in turn be referred to as the engagement flank 24 and is preferably flat. More precisely, the engagement section 514' of the rear flank 514 forms an engagement surface 514a' that is brought into contact with the engagement flank 24 of the filter housing 1003. This ensures that the threaded arrangements seal the air filter cartridge 1002 against the filter housing 1003.Since the engagement section 514' is slightly curved, the sections that deviate from the average steepness of the trailing flank – represented by the dashed line from the thread root 12 to the thread crest 11 – can be slightly deformed or cause the engagement flank 24 to be slightly deformed when the pressure P is applied as described above. Thus, all or at least most of the engagement section 514' or the engagement surface 514a' is brought into contact with the engagement flank 24.

[0095] Let us now turn Fig. Figure 10 shows a cross-sectional view of another example of the first thread 610 of the threaded arrangement 1 of the air filter cartridge 1002. All features except the rear flank 614 and the engagement section 614' are the same as those of the first thread 510 from Figure 10. Fig. 9, which is why the same reference numerals are used for corresponding features. However, instead of a concave shape, the engagement section 614' is slightly convexly curved here. The slightly curved engagement section is also defined here by a maximum offset with respect to the average steepness of the trailing flank, represented by the dashed line from the thread root 12 to the thread vertex 11 (i.e., the shortest distance between the thread root 12b and the thread vertex 11a), of less than X mm.

[0096] As a clear example, the average inclination of the intervention section 614' can be seen in Fig. Determine geometrically the slightly convexly curved thread 10 with reference to the dashed line representing the shortest distance between the thread root 12b and the thread apex 11a of the rear flank 614. Assuming that the horizontal projection (along the longitudinal axis A) between the thread root and thread apex 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 β can be calculated using the arctangent function: β=arctan(1,20 / 1,00)50.2°

[0097] The resulting angle β is interpreted as the average inclination of the engagement section 614' and, in this example, lies within the previously defined preferred range of 45° to 51°. Despite the slightly curved shape, the use of a straight-line approximation from the thread root to the thread crown provides a way to determine the average inclination for both flat and non-flat (slightly curved) configurations. In this way, even slightly curved surfaces can be analytically compared and classified within the claimed inclination range.

[0098] Both for Fig. 9 as well as for Fig. 10 The inclination β between 42° and 57°, or between 43° and 54°, or between 45° and 51°, e.g. between 46° and 48°, is represented as the inclination between the average steepness of the rear flank, represented by the dashed line from the thread root 12 to the thread crown 11, and the longitudinal axis A.

[0099] For the examples in the Fig. It should be noted that the engagement section, whether essentially flat or slightly curved, can result from minor shape deviations that occur during thread production, as well as from unavoidable tolerances or local deformations during thread cutting. Its function and the associated effects, as illustrated by the examples in the Fig. However, the examples described in 2-7 typically also apply to the examples in the Fig. 8-10. Thus, the use of the terms “essentially flat” or “slightly curved” allows for manufacturing tolerances or design adjustments that maintain functional equivalence to a flat engagement section.

[0100] Fig. shows an alternative embodiment of the thread 410 made of Fig. The 710 thread made of Fig. This can therefore correspond to the previously described first thread of the thread arrangement 1 of the air filter cartridge 1002. All features, with the exception of the thread crown 711 and the thread root 712, are identical or substantially identical to those of the thread 410 from Fig. 8, which is why similar reference numerals are used for corresponding features (however, in the 700 series). Instead of thread crests 11 and thread roots 12, which are pointed, with minimal axial extension, as in thread 410 in Fig. 8, the thread crown 711 (711a, 711b) and the thread root 712 (712a, 712b) are curved and have an axial extent that is greater than the minimum axial extent (for example, according to the values ​​in relation to Fig. 4 described). More precisely, the foot 712 can be referred to as the foot area and, for example, defined as the area between the first 1% and the first 10% of the thread height H, which is described in Fig. 11 with h1 is specified. Accordingly, the thread crest 711 can be referred to as the thread crest area and, for example, defined as the area between the last 10% and the last 1% of the thread height H, which is specified in Fig. 11 is designated with h3. Thus, the trailing flank 714 can be defined as extending from the thread root 712 or the end of the thread root region to the thread crown 711 or the beginning of the thread crown region, along 80% to 98% of the thread height H, in Fig. denoted by h2. Accordingly, the front flank 713 (713a, 713b) can be defined as extending from the thread crown 11 or the end of the thread crown region to the thread root 12 or the beginning of the thread root region along between 80% and 98% of the thread height H. As in the example in Fig. The engagement section 714' of the rear flank 714 is brought into contact with a flank 24 of the thread 20 of the filter housing 1003 during use under operating load, which corresponds to that of the rear flank 414.

[0101] Example 1. Air filter cartridge comprising a filter body and a threaded assembly for connection to a thread of a filter housing, the threaded assembly having a front end, a rear end opposite the front end, and at least one first thread extending helically along a longitudinal axis from the front end to the rear end, the first thread having a thread crown, a thread root, a thread pitch, a thread height extending in the direction from the thread root to the thread crown, a front flank facing the front end for initiating the connection, and a rear flank facing the rear end with an engagement section, wherein the steepness of the engagement section of the rear flank with respect to the longitudinal axis is less than the average steepness of the front flank with respect to the longitudinal axis.wherein the engagement section extends over at least 65% of the thread height and is inclined with respect to the longitudinal axis between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51°.

[0102] Example 2. The air filter cartridge according to Example 1, wherein the thread root is defined as the first 10% of the thread height and the thread crown as the last 10% of the thread height, wherein the rear flank is defined such that it extends from the thread root to the thread crown over 80% of the thread height.

[0103] Example 3. The air filter cartridge according to Example 2, wherein a center point of the thread apex is offset by at least 0.05 thread pitch, preferably by at least 0.10 thread pitch, from a position at 0.5 thread pitch.

[0104] Example 4. The air filter cartridge according to one of Examples 1 to 3, wherein the engagement section of the rear flank has an axial extension of at least 0.30 thread pitch, preferably at least 0.35 thread pitch, more preferably at least 0.40 thread pitch.

[0105] Example 5. Air filter cartridge according to one of Examples 1 to 4, wherein the front flank has a first axial extension, the rear flank a second axial extension, the thread crown a third axial extension and the thread root a fourth axial extension, wherein the sum of the first, second, third and fourth axial extensions corresponds to the thread pitch.

[0106] Example 6. The air filter cartridge according to Example 5, wherein the second axial dimension is larger than the first axial dimension.

[0107] Example 7. The air filter cartridge according to one of Examples 5 to 6, wherein the sum of the first axial extension, half of the third axial extension and half of the fourth axial extension is less than 0.5 thread pitch, preferably less than 0.45 thread pitch or less than 0.35 thread pitch, and the sum of the second axial extension, half of the third axial extension and half of the fourth axial extension is greater than 0.5 thread pitch, preferably greater than 0.55 thread pitch or greater than 0.65 thread pitch.

[0108] Example 8. Air filter cartridge according to one of Examples 5-7, wherein the third axial extension is equal to or less than 0.25 thread pitch, preferably equal to or less than 0.15 thread pitch, and / or the fourth axial extension is equal to or less than 0.20 thread pitch, preferably equal to or less than 0.15 thread pitch.

[0109] Example 9. Air filter cartridge according to one of Examples 1 to 8, wherein the average steepness of the front flank is between 6° and 45°, preferably between 13° and 42°, more preferably between 20° and 39° steeper than the engagement section of the rear flank.

[0110] Example 10. Air filter cartridge according to one of Examples 1 to 9, wherein the average steepness of the front flank is between 63° and 87°, preferably between 67° and 85°, more preferably between 71° and 81° with respect to the longitudinal axis.

[0111] Example 11. Air filter cartridge according to any one of Examples 1 to 10, wherein the engagement section of the rear flank forms an engagement surface for a corresponding flank of the thread of the filter housing and wherein the engagement surface of the rear flank is designed to be in contact with the corresponding flank of the thread of the filter housing when the air filter device is subjected to pressure in a direction from the front end to the rear end.

[0112] Example 12. Air filter cartridge according to any one of Examples 1 to 11, wherein the thread arrangement is a multiple thread arrangement, further comprising a second thread extending spirally along the longitudinal axis from the front end to the rear end and offset from the first thread, and wherein the second thread is shaped in the same way as the first thread or is shaped differently from the first thread.

[0113] Example 13. The air filter cartridge according to Example 12, wherein the second thread comprises a thread crown, a thread root, a thread pitch, a thread height extending in the direction from the thread root to the thread crown, a front flank facing the front end for inserting the connection with a contact section, and a rear flank facing the rear end, wherein the steepness of the contact section of the front flank with respect to the longitudinal axis is less than the average steepness of the rear flank with respect to the longitudinal axis, wherein the contact section extends over at least 65% of the thread height and is inclined with respect to the longitudinal axis between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51°.

[0114] Example 14. Air filter cartridge according to any of Examples 1-13, wherein the engagement section is flat or substantially flat.

[0115] Example 15. Air filter cartridge according to one of Examples 1-13, wherein the engagement section is slightly curved.

[0116] Example 16. Air filter cartridge according to any one of Examples 1 to 15, wherein the steepness of the engagement section is defined as the average steepness of the chord or centerline connecting the thread root and thread vertex to the longitudinal axis along the rear flank.

[0117] Example 17. An air filtration system comprising a filter housing and an air filter cartridge according to any one of Examples 1 to 16.

[0118] Example 18. A filter housing comprising a threaded assembly for connection to a thread of an air filter cartridge, wherein the threaded assembly has a first end, a second end opposite the first end, and at least one first thread extending helically along a longitudinal axis from the first end to the second end, wherein the first thread has a thread crown, a thread root, a thread pitch, a thread height extending in the direction from the thread root to the thread crown, a first flank facing the first end, and a second flank facing the second end, which has a thread engagement section of the housing, wherein the steepness of the thread engagement section of the housing of the second flank with respect to the longitudinal axis is less than the average steepness of the first flank with respect to the longitudinal axis.wherein the thread engagement section of the housing extends over at least 65% of the thread height and is inclined with respect to the longitudinal axis between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51°.

[0119] Example 19. A vehicle comprising an air filter cartridge according to any of Examples 1-17, an air filter system according to Example 17 or a filter housing according to Example 18.

[0120] Example 20. Use of an air filter cartridge in a filter housing, wherein the air filter cartridge is that of any one of Examples 1-16 or is defined as comprising: a filter body and a threaded assembly for connection to a first thread of the filter housing, the threaded assembly having a front end, a rear end opposite the front end, and at least one first thread extending helically along a longitudinal axis from the front end to the rear end, the first thread having a thread crown, a thread root, a thread pitch, a thread height extending in the direction from the thread root to the thread crown, a front flank facing the front end for initiating the connection, and a rear flank facing the rear end with an engagement section.wherein the steepness of the engagement section of the rear flank with respect to the longitudinal axis is less than the average steepness of the front flank with respect to the longitudinal axis, wherein the engagement section extends over at least 65% of the thread height and is inclined with respect to the longitudinal axis between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51°.

[0121] Example 21. The use of Example 20, wherein the first thread of the filter housing engages with the first thread of the air filter cartridge.

[0122] Example 22. Use of one of embodiments 20-21, wherein the first thread of the filter housing has an engagement flank designed to be able to come into contact with the engagement section of the rear flank of the air filter cartridge.

[0123] Example 23. Application of Example 22, wherein when pressure is applied to the air filter cartridge acting from the front end to the rear end, the engagement section of the rear flank is brought into contact with the engagement flank of the first thread of the filter housing to ensure a seal.

[0124] Example 24. Use of one of embodiments 22-23, wherein the engagement flank is flat and has an angle of inclination between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51° with respect to the longitudinal axis.

[0125] Example 25. The use of one of embodiments 22-24, wherein the engagement section of the rear flank is flat and is inclined with respect to the longitudinal axis between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51°.

[0126] Example 26. Use of one of embodiments 22-25, wherein, when pressure is applied to the air filter cartridge from the front end to the rear end, the contact between the engagement flank and the engagement section of the rear flank extends over at least 65% of the thread height.

[0127] Example 27. Use of an air filter cartridge in a filter housing, wherein the filter housing is that of Example 18 or is defined to comprise: a threaded assembly for connection to a thread of the air filter cartridge, the threaded assembly having a first end, a second end opposite the first end, and at least one first thread extending helically along a longitudinal axis from the first end to the second end, the first thread having a thread crown, a thread root, a thread pitch, a thread height extending in the direction from the thread root to the thread crown, a first flank facing the first end, and a second flank facing the second end, which has a thread engagement section of the housing.

[0128] wherein the steepness of the housing thread engagement section of the second flank with respect to the longitudinal axis is less than the average steepness of the first flank with respect to the longitudinal axis, wherein the housing thread engagement section extends over at least 65% of the thread height and is inclined between 42° and 57°, preferably between 43° and 54°, preferably between 45° and 51° with respect to the longitudinal axis.

[0129] Example 28. The use of Example 27, where the air filter cartridge is compatible with the filter housing.

[0130] Example 29. The use of one of Examples 27-28, wherein the first thread of the filter housing engages with the first thread of the air filter cartridge.

[0131] Example 30. Use of one of Examples 27-29, wherein the second flank is an engagement flank designed to engage with an engagement section of a rear flank of a threaded assembly of the air filter cartridge.

[0132] Example 31. Using Example 30, wherein when pressure is applied to the air filter cartridge from the second end towards the first end, the engagement section of the rear flank is brought into contact with the engagement flank of the first thread of the filter housing to ensure a seal.

[0133] Example 32. The use of one of Examples 27-31, wherein a thread engagement section of the second flank is flat or substantially flat.

[0134] The terminology used herein serves only to describe certain aspects and is not intended to limit disclosure. As used herein, the singular forms "a," "an," and "the" are to include the plural forms unless the context clearly indicates otherwise. As used herein, the term "and / or" encompasses any and all combinations of one or more of the elements listed. It is further understood that the terms "comprises," "comprehensive," "includes," and / or "including," when used herein, specify the presence of the features, elements, actions, steps, processes, components, and / or elements mentioned, but do not preclude the presence or addition of one or more other features, elements, actions, steps, processes, components, and / or groups thereof.

[0135] It is 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 used only to distinguish one element from another. For example, a first element could be called a second element, and likewise a second element could be called a first element, without departing from the scope of the present revelation.

[0136] Relative terms such as "below" or "above" or "above" or "under" or "horizontal" or "vertical" can be used here to describe a relationship of one element to another, as illustrated in the figures. It is understood that these terms, and those discussed above, are intended to encompass various orientations of the device in addition to the one illustrated in the figures. It is understood that when an element is described as "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or that intermediate elements may be present. In contrast, when an element is described as "directly connected" or "directly coupled" to another element, no intermediate elements are present.

[0137] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as generally understood by a person skilled in the art in the field to which this disclosure belongs. It is further understood that the terms used herein are to be interpreted in such a way that their meaning is consistent with their meaning in the context of this description and the relevant field, and that they are not to be interpreted in an idealized or overly formal sense, unless expressly defined herein.

[0138] It is understood that the present disclosure is not limited to the aspects described above and illustrated in the drawings; rather, the person skilled in the art will recognize that many changes and modifications can be made within the scope of the present disclosure and the accompanying claims. Aspects have been disclosed in the drawings and the description for illustrative purposes only and not for limiting purposes, the scope of which is set out in the following claims.

Claims

[1] Air filter cartridge (1002) comprising a filter body (1002a) and a threaded assembly (1, 101, 201) for connection to a thread (20, 120, 220) of a filter housing (1003), wherein the threaded assembly (1, 101, 201) has a front end (1a, 101a, 201a), a rear end (1b, 101b, 201b) opposite the front end (1a, 101a, 201a) and at least one first thread (10, 110, 210) extending helically along a longitudinal axis (A) from the front end (1a, 101a, 201a) to the rear end (1b, 101b, 201b), wherein the first thread has a threaded crown (11, 111), a threaded root (12, 112), has a thread pitch (p) and a thread height (H) extending in the direction from the thread root (12, 112) to the thread crown (11, 111), a front flank (13, 113) facing the front end (1a, 101a, 201a) for initiating the connection and a rear flank (14, 114) facing the rear end (1, 101b, 201b) with an engagement section (14', 114'),wherein the steepness of the engagement section (14', 114') of the rear flank (14, 114) with respect to the longitudinal axis (A) is less than an average steepness of the front flank (13, 113) with respect to the longitudinal axis (A), wherein the engagement section (14', 114') extends over at least 65% of the thread height (H) and is inclined with respect to the longitudinal axis (A) at an angle (β) between 42° and 57°, and wherein the average steepness of the front flank (13, 113) is between 6° and 45° steeper than the engagement section (14', 114') of the rear flank (14, 114). [2] Air filter cartridge (1002) according to claim 1, wherein the thread root (12, 112) is defined as the first 10% of the thread height (H) and the thread crown (11, 111) as the last 10% of the thread height (H), wherein the rear flank (14, 114) is defined such that it extends from the thread root (12, 112) to the thread crown (11, 111) along 80% of the thread height (H). [3] Air filter cartridge (1002) according to claim 2, wherein a center point (m) of the thread vertex (11, 111) is arranged offset from a position at 0.5 thread pitch by at least 0.05 thread pitch (p), preferably by at least 0.10 thread pitch (p). [4] Air filter cartridge (1002) according to one of claims 1 to 3, wherein the engagement section (14', 114') of the rear flank (14, 114) has an axial extent of at least 0.30 thread pitch (p), preferably at least 0.35 thread pitch (p), more preferably at least 0.40 thread pitch (p). [5] Air filter cartridge (1002) according to any one of claims 1 to 4, wherein the front flank (13, 113) has a first axial extension (d1), the rear flank (14, 114) has a second axial extension (d2), the thread crown (11, 111) has a third axial extension (d3) and the thread root (12, 112) has a fourth axial extension (d4), wherein the sum of the first, second, third and fourth axial extensions (d1, d2, d3, d4) is equal to the thread pitch (p). [6] Air filter cartridge (1002) according to claim 5, wherein the second axial extent is larger than the first axial extent. [7] Air filter cartridge (1002) according to one of claims 5-6, wherein the sum of the first axial extent (d1), half of the third axial extent (d3) and half of the fourth axial extent (d4) is less than 0.5 of the thread pitch (p), preferably less than 0.45 thread pitch (p) or less than 0.35 thread pitch (p), and the sum of the second axial extent (d2), half of the third axial extent (d3) and half of the fourth axial extent (d4) is greater than 0.5 thread pitch (p), preferably greater than 0.55 thread pitch (p) or greater than 0.65 thread pitch (p). [8] Air filter cartridge (1002) according to one of claims 5-7, wherein the third axial extent (d3) is equal to or less than 0.25 thread pitch (p), preferably equal to or less than 0.15 thread pitch (p), and / or the fourth axial extent (d4) is equal to or less than 0.20 thread pitch (p), preferably equal to or less than 0.15 thread pitch (p). [9] Air filter cartridge (1002) according to any one of claims 1 to 8, wherein the average steepness of the front flank (13, 113) is between 13° and 42°, preferably between 20° and 39° steeper than the engagement section (14', 114') of the rear flank (14, 114) and / or wherein the engagement section (14', 114') is inclined with respect to the longitudinal axis (A) by an angle (β) between 43° and 54°, preferably between 45° and 51°. [10] Air filter cartridge (1002) according to any one of claims 1 to 9, wherein the average steepness of the front flank (13, 113) is between 63° and 87°, preferably between 67° and 85°, more preferably between 71° and 81° with respect to the longitudinal axis (A). [11] Air filter cartridge (1002) according to any one of claims 1 to 10, wherein the engagement section (14', 114') of the rear 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 rear flank (114) is designed such that it is 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 subjected to a pressure (P) in a direction from the front end (1a, 101a, 201a) to the rear end (1b, 101b, 201b). [12] Air filter cartridge (1002) according to any one of claims 1 to 11, wherein the thread arrangement (201) is a multiple thread arrangement (201) which further comprises a second thread (230) which extends spirally along the longitudinal axis (A) from the front end (201a) to the rear end (201b) and is offset from the first thread (210), and wherein the second thread (230) is shaped in accordance with the first thread (210) or is shaped differently from the first thread (210). [13] Air filter cartridge (1002) according to claim 12, wherein the second thread (230) has a thread crown (231), a thread root (232), a thread pitch (p), a thread height (H) extending from the thread root (232) to the thread crown (231), a front flank (233) facing the front end (201a) to guide the connection, and a contact section (233'), as well as a rear flank (234) facing the rear end (201b), wherein the steepness of the contact section (233') of the front flank (233) with respect to the longitudinal axis (A) is less than the average steepness of the rear flank (233) with respect to the longitudinal axis (A), wherein the contact section (233') extends over at least 65% of the thread height (H) and is is inclined to the longitudinal axis (A) by an angle (α2) between 42° and 57°, preferably between 43° and 54°, more preferably between 45° and 51°. [14] Air filter cartridge (1002) according to any one of claims 1 to 13, wherein the engagement section (14') is flat or substantially flat. [15] Air filter cartridge (1002) according to any one of claims 1 to 13, wherein the engagement section (14') is slightly curved. [16] Air filter cartridge (1002) according to any one of claims 1 to 15, wherein the steepness of the engagement section is defined as the average steepness of the chord or centerline connecting the thread root and thread apex to the longitudinal axis along the rear flank. [17] Air filter system (1001) comprising a filter housing (1003) and an air filter cartridge (1002) according to any one of claims 1 to 16. [18] Vehicle (1) comprising an air filter cartridge according to any one of claims 1 to 16 or an air filter system (1001) according to claim 17.

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