Air filter element having a circumferentially protruding clean air seal, filter housing and air filter

An air filter element for an air filter for an internal combustion engine is provided with a filter medium surrounding annularly a longitudinal axis of the air filter element. A first end disk is provided at a first end face of the air filter element, wherein the filter medium is embedded in the first end disk at the first end face. A clean air seal is configured to seal a raw side of the air filter against a clean side of the air filter. The clean air seal and the first end disk are embodied together as one piece. The clean air seal protrudes continuously radially past the filter medium. A filter housing for the air filter element is provided with a filter pot and a cover and has a clean air outlet and a raw air inlet arranged at a side wall of the filter pot.

BACKGROUND OF THE INVENTION

The invention concerns an air filter element for an air filter for an internal combustion engine. Furthermore, the invention concerns a filter housing for an air filter. Finally, an air filter with an air filter element and a filter housing is subject matter of the invention.

The intake air of internal combustion engines is typically purified prior to entering a combustion chamber of the internal combustion engine by removing contaminants by means of an air filter. Air filter elements used for this purpose can comprise a star-shaped folded filter medium which surrounds a longitudinal axis in an annular shape. For internal combustion engines of commercial vehicles, for example, heavy trucks, such a filter element can have a length of more than 300 mm, in particular of more than 500 mm. It is important that the filter elements are attached securely in their filter housing. Since the filter media in operation become clogged with particles filtered out of the air, a regular exchange of the filter elements is required.

WO 2011/045220 A2 discloses a filter insert comprising a filter element with a frame circumferentially extending along the lateral surfaces of the filter element, wherein the frame carries an axial seal. The seal can be brought into contact with a sealing surface of a filter housing. The frame comprises at two oppositely positioned lateral surfaces of the filter insert a first and second contact surface for clamping the filter element by means of a first and a second clamping element. The filter insert can be inserted through a lateral mounting opening into the filter housing. The clamping elements can be embodied as clamping blades at a cover for closing the mounting opening.

It is the object of the invention to provide an air filter element, a filter housing, and an air filter that enable a simple exchange of the filter element.

SUMMARY OF THE INVENTION

The object is solved by an air filter element for an air filter for an internal combustion engine, with a filter medium that surrounds a longitudinal axis of the filter element annularly, wherein the filter element comprises a clean air seal for sealing a raw side of the air filter against a clean side of the air filter, wherein the clean air seal is embodied as one piece, in particular monolithically, with a first end disk into which the filter medium is embedded at a first end face of the filter element, and wherein the clean air seal is embodied so as to continuously radially protrude past the filter medium.

The object is further solved by a filter housing, in particular for receiving a filter element according to the invention, comprising a filter pot and a cover, wherein the filter pot comprises at a side wall a clean air outlet for filtered air, and preferably moreover comprises at the side wall a raw air inlet for air to be filtered, which is preferably arranged adjacent to the clean air outlet, in particular in the same angular orientation in relation to a housing center axis.

The object is further solved by an air filter comprising a filter element according to the invention and a filter housing according to the invention, wherein the clean air seal is arranged, held by being clamped, between the filter pot and the cover.

Preferred embodiments are disclosed in the dependent claims.

Air Filter Elements According to the Invention

According to the invention, an air filter element for an air filter for an internal combustion engine is provided. The filter element comprises a filter medium that surrounds in an annular shape the longitudinal axis of the filter element. The filter medium can surround the longitudinal axis in a circular ring shape. Preferably, the filter medium is not arranged with rotational symmetry in relation to the longitudinal axis. In this way, the flow through an air filter can be improved with the filter element and/or the effective surface of the filter element can be enlarged. Typically, the filter element can be flowed through in radial direction from the exterior to the interior. Typically, a length of the filter element, measured along the longitudinal axis, amounts to at least 500 mm. The filter element comprises a clean air seal for sealing a raw side of the air filter against a clean side of the air filter. The clean air seal in the mounted state of the filter element is resting seal-tightly at a filter housing of the air filter. The clean air seal can be embodied to seal axially or radially. The clean air seal is embodied as one piece, in particular monolithically, with a first end disk in which the filter medium is embedded at a first end face of the filter element. By means of the clean air seal, one piece together with the end disk, the configuration of the filter element is simplified. The filter medium can be embedded by casting in the end disk. Preferably, the clean air seal and the end disk are manufactured in a single common working step by primary shaping. The clean air seal is embodied to protrude continuously radially past the filter medium. This enables at the same time a simple configuration of the filter housing for the filter element and a simple exchange of the filter element. Due to the radial protrusion, the sealing action at the clean side of the air filter relative to the raw side can be realized at a housing wall of the filter housing. The protrusion of the clean air seal past the filter medium can be configured to be uniform in circumferential direction. Preferably, the amount of protrusion varies in the circumferential direction. In this way, additional degrees of freedom for the configuration of the filter housing are provided. In summary, the filter element in other words comprises a first end disk into which the filter medium is embedded at the first end face. A radial protrusion of the first end disk past the filter medium forms a clean air seal for sealing a raw side of the air filter against a clean side of the air filter. The clean air seal in circumferential direction extends continuously circumferentially and is embodied to protrude in this context continuously in radial direction.

Preferably, at the first end disk a bead is formed which projects axially past the first end disk and which partially surrounds a central opening in the first end disk. In other words, the bead can be embodied to partially surround the opening or partially circumferentially extend about the opening. Due to the bead, the support of the filter element in the filter housing, in particular at a cover of the filter housing, can be improved. In particular, the filter element can be guided by the bead in radial direction. The bead can center the filter element at the first end face in the filter housing. Particularly preferred, the bead is embodied monolithically with the first end disk.

A support structure can be embedded in the first end disk. The support structure is preferably embodied monolithically with a central tube of the filter element. By means of the support structure, the mechanical stability of the filter element can be improved. The above-described bead can be slightly displaced outwardly in radial direction relative to the central tube. An axial holding force for the filter element can then be introduced directly, in particular on a straight path, into the central tube.

The first end disk and the clean air seal are preferably manufactured with polyurethane. Particularly preferred, they are comprised of polyurethane. Polyurethane is a suitable material for sealing purposes which can be processed easily, in particular by casting. The end disk can comprise a first polyurethane material in a radially inner region. The clean air seal can comprise in a radially outer region a second polyurethane material that is softer than the first polyurethane material. In this way, the mechanical stability, in particular the stiffness, can be increased (radially inwardly) and the sealing ability can be improved (radially outwardly) at the same time.

At a second end face of the filter element, a second end disk can be arranged. Preferably, the filter medium is embedded at the second end face in the second end disk. Particularly preferred, the second end disk is of a closed configuration. Due to the closed configuration, flow through the second end disk is prevented. The second end disk can be embodied monolithic and without openings passing through (in axial direction). Alternatively, the second end disk can be of a multi-part configuration and comprise a closure element which is closing off in axial direction a through opening in a base body of the second end disk.

At the second end disk, two cams can be formed which project radially past the filter element and past an outer contour of the second end disk. By means of the cams, the orientation of the filter element in the filter housing can be defined. In particular, the projecting cams at the second end face can support the filter element in radial direction at the filter housing. By an engagement of the cams in corresponding depressions of the filter housing, the rotational orientation of the filter element relative to the longitudinal axis can be defined. Additionally, due to the projecting cams, elements that are arranged at the filter housing can be protected from contact with the filter element upon removal of the filter element from the filter housing and upon insertion of the filter element into the filter housing. In these working steps, the cams can rest at a housing wall and can keep the second end disk and the filter medium spaced apart from the housing wall. In particular, it can be prevented that a water outlet valve arranged in the housing wall can become damaged or does damage the filter element upon exchange of the filter element. The cams are preferably formed monolithically with the second end disk. A surface area of the (smallest) convex envelope of an axial projection of the second end disk with the two cams can be greater than the surface area of the axial projection. In addition to the two cams, further radially projecting cams can be present at the second end disk.

The two cams, in relation to the longitudinal axis, can be displaced relative to each other by at most 180°, preferably by at most 120°, particularly preferred by at most 100°. Moreover, the two cams, in relation to the longitudinal axis, can be displaced relative to each other by at least 30°, preferably by at least 45°, particularly preferred by at least 60°. Cams that are spaced apart from each other in this way are particularly effective for the aforementioned purposes.

At the second end disk, at least one axial projection can be formed. Due to the axial projection, the filter element can be supported at a bottom of the filter housing. Preferably, the axial projection is arranged in axial direction in extension of a central tube of the filter element. In this way, a direct force flow of an axial holding force for the filter element can be provided from the bottom of the filter housing through the at least one axial projection into the central tube.

Filter Housing According to the Invention

The filter housing according to the invention for a filter element according to the invention comprises a filter pot and a cover. The cover is detachably fastenable at the filter pot. Preferably, the cover is detachable from the filter pot and attachable to the filter pot in axial direction relative to a longitudinal axis of the filter pot. The cover can be screwable onto the filter pot. The filter pot comprises at a side wall a clean air outlet for filtered air. In other words, the clean air outlet can be oriented substantially radially to the longitudinal axis of the filter pot. When the filter element is inserted in the filter housing, preferably the longitudinal axes of the filter element and of the filter pot coincide with each other. The side wall can surround annularly the longitudinal axis of the filter housing. Due to the lateral clean air outlet, a compact construction of the filter housing in axial direction is enabled. Because the clean air outlet is formed at the filter pot, an air hose that guides the filtered air away from the clean air outlet can remain mounted at the filter housing when exchanging the filter element. In this way, the exchange of the filter element is simplified. Preferably, the filter pot furthermore has a raw air inlet for the air to be filtered at the side wall. This can further improve the compact construction of the air filter. The raw air inlet and the clean air outlet can point in the same direction. In particular, they can be oriented parallel to each other. This simplifies mounting of the filter housing at devices for air supply and air discharge. Between the clean air outlet and the raw air inlet, a contact surface for the clean air seal of the filter element can be embodied at the inner side at the side wall of the filter housing.

The filter pot is preferably closable at the clean side by the cover. In this way, the cover can be configured such that it interacts with the clean air seal of the filter element. In particular, the filter pot can comprise a large service opening that can be closed off by the cover. Through the service opening, the filter element can be inserted into the filter pot and removed from the filter pot.

Preferably, a secondary seal for sealing the cover relative to the filter pot is provided. In this way, an escape of filtered air from the clean side of the filter housing can be prevented. Also, it can be prevented that unfiltered air from the environment can reach the clean side. The secondary seal can comprise an O-ring. Preferably, the secondary seal comprises a 3D profile seal, in particular of foam rubber. A 3D profile seal is to be understood as a seal that is not completely arranged in a plane but, in sections thereof, projects from a plane in which another section of the seal extends. The secondary seal can be arranged in particular in a groove of the cover.

An air guide can be formed in the cover in order to guide filtered air from an interior of the filter element to the clean air outlet. This can reduce a flow resistance of the air filter. Preferably, the air guide interacts with a bead which is projecting past the first end disk and which partially surrounds a central opening in the first end disk of the filter element. In this way, the filter element can be aligned and held in the filter housing in the mounted state of the air filter.

At the cover, a projection can be formed in order to engage a central opening of the first end disk of the filter element. Preferably, the projection in the mounted state of the air filter engages partially circumferentially the central opening of the first end disk. In particular, the projection can project through the first end disk in axial direction. The projection is preferably arranged at the bottom in the installation position of the air filter. The projection can guide water that passes from the clean air outlet into the filter housing past the first end disk so that it can flow through the filter medium of the filter element to a water outlet valve of the filter housing. The projection is preferably embodied at an air guide of the cover. This simplifies the configuration of the cover.

The filter pot can comprise, preferably at the bottom side, two depressions for engagement of the cams of a filter element that comprises two radially projecting cams at the second end disk. The cams can be supported in the depressions in axial direction, radial direction, and in particular in circumferential direction. In this way, a correct orientation of the filter element in the filter housing can be ensured.

Air Filter According to the Invention

The air filter according to the invention comprises a filter element according to the invention and a filter housing according to the invention. According to the invention, it is provided that the clean air seal of the filter element is arranged, held by being clamped, between the filter pot and the cover. In this way, it can be reliably ensured that the clean air seal in the mounted state rests seal-tightly at the filter housing. Typically, the clean air seal seals against the filter pot. The clean air seal can rest at the filter pot to seal radially or axially. The clean air seal seals in the mounted state the raw side of the air filter against the clean side of the air filter. The cover can fix the filter element in the filter housing. In particular, the filter element in axial direction can be clamped between a bottom of the filter housing and the cover. Preferably, the force flow of an axial holding force for the filter element, as described above, passes through a central tube of the filter element. The first end disk and a second end disk of the filter element can establish an elastic deformation in longitudinal direction of the filter element in order to obtain a defined holding force in axial direction and permit a complete closure of the cover. In radial direction, the filter element can be supported with form fit at the filter pot and/or at the cover. In particular, a second end disk and/or radially projecting cams at the second end disk can be supported at the bottom side at the filter pot. A bead at the first end disk of the filter element that projects in axial direction can be supported at the cover with form fit in order to fix the filter element at the first end face in radial direction. The clean air seal is preferably decoupled from the force flow. In other words, the clean air seal does not participate in supporting the filter element in the filter housing. This improves the sealing action and avoids damage of the clean air seal by mechanical loads in operation.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG.1shows an air filter10according to the invention. The air filter10comprises an air filter element12according to the invention and a filter housing14according to the invention. The filter element12is arranged in the filter housing14. A cover16of the filter housing14is placed onto a filter pot18of the filter housing14. A clean air seal20of the filter element12is arranged, held by being clamped, between the cover16and the filter pot18. The clean air seal20seals a raw side22of the air filter10against a clean side24of the air filter10. The cover16is arranged at the clean side24of the air filter10. In the mounted state of the air filter10, a central longitudinal axis26aof the filter element12coincides with a central longitudinal axis26bof the filter pot18. For a more detailed explanation of the details according to the invention, reference is being had in addition to the followingFIGS.2to9b.

FIG.2shows an exploded illustration of the air filter10ofFIG.1. The cover16is lifted off the filter pot18. The filter element12projects partially out of the filter pot18. For detachable attachment of the cover16at the filter pot18, screws28are provided of which one is provided with a reference character inFIG.2. The screws28in the mounted state can be support, on the one hand, at the cover16and, on the other hand, engage the filter pot18. In order to be able to insert the filter element12into the filter pot18or remove it from the filter pot18, the cover16(with the screws28loosened) can be removed in axial direction from the filter pot18. The filter element12can then be inserted in axial direction into the filter pot18or pulled out of the filter pot18.

At a side wall30of the filter pot18, a clean air outlet32and a raw air inlet34are formed. The side wall30surrounds the longitudinal axis26ain an annular shape. In particular, the longitudinal axis26bdoes not intersect the side wall30. The clean air outlet32and the raw air inlet34are designed parallel to each other here and point in the same direction. They extend substantially radially relative to the longitudinal axis26b. An outlet axis36aand an inlet axis36bare positioned at an angle of approximately 85° relative to the longitudinal axis26b. Since the clean air outlet32and the raw air inlet34are formed at the side wall30of the filter pot18, they can remain connected to hoses (not illustrated) of an air guiding system upon exchange of the filter element12. By means of the air guiding system, in particular air to be filtered can be supplied to the raw air inlet34and filtered air can be guided from the clean air outlet32to an internal combustion engine.

InFIG.3aandFIG.3b, the air filter element12according to the invention is illustrated in two perspective views.FIG.4ashows a longitudinal section of the filter element12. InFIG.4b, a detail of the right upper region ofFIG.4ais illustrated enlarged.FIG.4cshows a detail of the left upper region ofFIG.4ain an enlarged view.

The filter element12comprises a filter medium38. The filter medium38surrounds the longitudinal axis26ain an annular shape. The filter medium38here is not embodied in a circular ring shape but is laterally flattened. The filter medium38is formed here by a star-shaped folded filter bellows.

The filter element12comprises a first end disk40at a first end face42. The filter medium38is embedded in the first end disk40. The clean air seal20is embodied monolithically with the first end disk40. The clean air seal20protrudes in radial direction relative to the longitudinal axis26acontinuously circumferentially about the filter medium38. In other words, the clean air seal20is formed by the section of the first end disk42that radially protrudes past the filter medium38. Here, the amount of protrusion of the clean air seal20is variable in circumferential direction, see in particularFIG.3b. For manufacture-technological reasons, in the first end disk40, there are embossments44of spacers of a casting mold (not illustrated) in which the first end disk40with the clean air seal20has been cast onto the filter medium. The first end disk40and the clean air seal20are comprised here of polyurethane.

A support structure46is embedded in the first end disk40. The support structure46here is embodied monolithically with a central tube48of the filter element12. The filter medium38is positioned radially inwardly at the central tube48. The support structure46is embodied here in the region of the first end disk40in a grid shape with radial stays46aand rings46bextending circumferentially in circumferential direction.

The first end disk40comprises a central opening50. The central opening50opens an interior52of the filter element12to the exterior. At the first end disk40, an axially outwardly projecting bead54is embodied here. The bead54projects in axial direction past the first end disk40. In other words, the bead54projects away from the first end disk40in the direction of the longitudinal axis26a. The bead54is here monolithically embodied with the first end disk40and the clean air seal20. In the mounted state of the air filter10, the bead54can interact with the cover16. In particular, the bead54can be supported at the cover16in radial direction.

As shown inFIGS.2and3a, the bead54is arranged at an outer circumference of the central opening50on the first end disk40and surrounds at least half of the outer circumference of the central opening50Here, the bead54is arranged at and surrounds approximately three fourths of the outer circumference of the central opening50. As is shown inFIG.3a, the axially outwardly projecting bead54is a U-shaped bead having two free ends54A. As shown inFIG.3a, the U-shaped bead at the free ends54A curves radially outwardly away from the longitudinal axis26a.

At a second end face56of the filter element12, a second end disk58is arranged. The filter medium38is embedded at the second end face56in the second end disk58. The second end disk58is embodied of a closed configuration in axial direction. The second end disk58comprises here a closure element60. By means of the second end disk58, an inflow or outflow of air into or out of the interior50is prevented at the second end face56. A base body of the second end disk58is manufactured here of polyurethane; the closure element60can be manufactured of a different material, in particular of a non-elastomer plastic material.

At the second end disk, two cams62(seeFIGS.3a,3b) are formed here. The cams62project in radial direction relative to the longitudinal axis26apast the filter medium38and an outer contour63of the second end disk58. The two cams62can be arranged displaced relative to each other in relation to the longitudinal axis26aby an angle of 70°, for example. This means that connecting lines (not illustrated) of the cams62to the longitudinal axis26aare positioned at an angle of 70° relative to each other.

At the second end disk58, furthermore four axial projections64are formed here of which inFIG.3btwo are provided with a reference character. The axial projections64project in axial direction past the second end disk58. The axial projections64are arranged in axial direction in extension of the central tube48. By means of the axial projections64, the filter element12can be supported at a bottom66(seeFIG.1) of the filter pot18.

For manufacture-technological reasons, the second end disk58comprises—like the first end disk40—an embossments68that has been caused by a spacer of a casting mold (not illustrated). The embossment68of the second end disk58is here embodied to continuously extend circumferentially.

FIG.5shows the cover16of the filter housing14in a perspective view of the inner side. A groove70is formed externally at the cover16so as to extend circumferentially. A secondary seal72(seeFIG.1) can be inserted into the groove70. The secondary seal72can comprise an O-ring. By means of the secondary seal72, the cover16is sealed against the filter pot18in the mounted state of the air filter10. Here, the secondary seal72seals the clean side24of the air filter10against the environment of the air filter10. Upon attachment of the cover16at the filter pot18, the secondary seal72is compressed between a circumferential collar74of the filter pot18and the groove70of the cover16.

An air guide76is embodied in the cover16. The air guide76serves for guiding the filtered air out of the interior52of the filter element12to the clean air outlet32of the filter housing14. The air guide76comprises here two outlet openings78which communicate with the clean air outlet32in the side wall30of the filter pot18in the mounted state.

At the cover16, here in the region of the air guide76, a projection80is formed. In the mounted state of the air filter10, the projection80engages the central opening50in the first end disk40of the filter element12, seeFIG.1. In particular, the projection80can pass through the first end disk40in the central opening50in axial direction.

FIG.6shows the filter pot18in a first perspective view. At the bottom side, i.e., in the region of a bottom66of the filter pot18, two depressions82are formed in the filter pot18. The depressions82are embodied to correspond with the cams62(compareFIG.3a,3b) at the second end disk58of the filter element12. In the mounted state of the air filter10, the cams62engage the depressions82. In this way, a defined orientation of the filter element12in the filter pot18is established.

In the filter pot18, a water outlet valve84is provided. The water outlet valve84is arranged here in relation to the longitudinal axis26boppositely positioned to the clean air outlet32and the raw air inlet34in the side wall30of the filter pot18.

FIG.7shows the filter pot18in a second perspective view. The filter pot18comprises a circumferentially extending shoulder86. The shoulder86extends between the clean air outlet32and the raw air inlet34circumferentially at the side wall30of the filter pot18. In the mounted state of the air filter10, the clean air seal20of the filter element12is resting on the shoulder86of the filter pot, compareFIG.1.FIG.1andFIG.8show that the clean air seal20is arranged between the raw air inlet34and the clean air outlet32so that it separates the clean side24of the air filter10from the raw side22of the air filter10.

In order to ensure the seal-tight contact of the clean air seal20at the filter pot18, the clean air seal20is held by being clamped in the mounted state between the circumferentially extending shoulder86of the filter pot18and the cover16. The cover16comprises a circumferentially extending pressure ring88(seeFIG.9a). In the mounted state of the air filter10, the pressure ring88forces the clean air seal20against the filter pot18, in particular against its circumferentially extending shoulder86.

FIG.9ashows an enlarged detail of the air filter10ofFIG.1in the region of the clean air outlet32and of the raw air inlet34. It can be seen well that the clean air seal20is compressed between the circumferentially extending shoulder86of the filter pot18and the circumferentially extending pressure ring88of the cover16. The cover is resting seal-tightly, presently with the pressure ring88axially, against the clean air seal20or the first end disk40. In other words, the clean air seal20is clamped between the cover16and the filter pot18. Due to the elastic deformation of the clean air seal20produced thereby, it is achieved that it is contacting seal-tightly the filter pot18. It is conceivable alternatively or additionally that an annularly circumferentially extending sealing contact surface of the cover is resting preferably radially against a corresponding (radial) sealing surface at the end disk40so that the cover16, in particular separating the raw side and the clean side, provides an air guide to the clean air outlet32. In this case, it is expedient that the cover16comprises a wall section that seal-tightly connects the sealing contact surface with the side wall30, preferably extends radially away from the sealing contact surface outwardly to the side wall30of the filter pot18, and/or continues the separation plane formed by the end disk40.

Moreover, inFIG.9ait can be seen that the secondary seal72is forced by the circumferentially extending collar74of the filter pot18into the circumferentially extending groove70of the cover16. In this way, it is ensured that the cover16is sealed relative to the filter pot18.

FIG.9bshows an enlarged detail of the air filter ofFIG.1in a region oppositely positioned to the clean air outlet32and the raw air inlet46in relation to the longitudinal axis26a. In this region, the water outlet valve84is also arranged in the side wall30of the filter pot18. Here, it can be seen also that the secondary seal72is forced by the collar74of the filter pot18into the groove70of the cover16.

The clean air seal20is clamped between the shoulder86of the filter pot18and the pressure ring88of the cover16.

InFIG.9b, it can also be seen clearly that the projection80of the cover16engages the central opening50of the filter element12and passes through the first end disk40in axial direction. The cover16in addition interacts in a region of the air guide76in which also the projection80is formed with the bead54which projects in axial direction away from the first end disk40. Due to the projection80, water which has passed from the clean air outlet32into the air filter10can be guided past the first end disk40. The water flows then through the filter medium38to the water outlet valve84. There, it can be discharged from the filter housing14.

InFIG.10aandFIG.10b, an alternative design of the secondary seal72is illustrated. The views ofFIG.10aandFIG.10bcorrespond to those ofFIG.9aandFIG.9b. Also, the air filter—aside from the differences in the region of the secondary seal72—is constructed like the air filter10according toFIG.1toFIG.9b. Therefore, only the differences will be explained.

The secondary seal72is formed here by a three-dimensional profile seal. The profile seal can be manufactured of foam rubber. The profile seal—like the O-ring of the first embodiment—is inserted into a circumferentially extending groove70in a cover16of a filter housing. A circumferentially extending collar74at a filter pot18of the filter housing projects in the mounted state into the profile seal. The profile seal is thereby compressed between the collar72and the groove70so that the cover16and the filter pot18are sealed relative to each other.

FIG.11shows a first variant of an axially sealing clean air seal20of an air filter element according to the invention. The clean air seal20is compressed between a shoulder86of a filter pot and a pressure ring88of a cover for the filter pot. At the shoulder86, a circumferentially extending protrusion90is formed here radially inwardly. The protrusion90is forced in the compressed state into the clean air seal20. In this way, in this region the contact area pressure is increased so that the sealable pressure difference increases.

FIG.12shows a second variant of an axially sealing clean air seal20of an air filter element according to the invention. The clean air seal20is shown here in the uncompressed state between a shoulder86of a filter pot and a pressure ring88of a cover for the filter pot. As inFIG.11, the shoulder86comprises a circumferentially extending protrusion90. The clean air seal20comprises radially outwardly at the top side (clean side) as well as at the bottom side (raw side) a circumferentially extending thicker portion92a,92b, respectively. This can further increase the contact area pressure that occurs in the compressed state. In addition, the hold of the clean air seal20between the shoulder86and the pressure ring88is improved.

FIG.13shows a third variant of an axially sealing clean air seal20of an air filter element according to the invention. The clean air seal20is illustrated here in the uncompressed state between a shoulder86of a filter pot and a pressure ring88of a cover for the filter pot. The shoulder86and the pressure ring88are here embodied respectively with a non-contoured (flat) surface for contacting the clean air seal20. The clean air seal20comprises at the bottom side (raw side) a distinct thicker portion94. In the region of the thicker portion94, the clean air seal20is here circumferentially approximately twice as thick as in the region not made thicker. This configuration also increases the contact area pressure occurring in the compressed state between the clean air seal20and the shoulder86for an improved sealing ability.

FIG.14shows a first variant of a radially sealing clean air seal20of an air filter element according to the invention. The clean air seal20is illustrated in the compressed state between a shoulder86of a filter pot and a pressure ring88of a cover for the filter pot. The pressure ring88is non-contoured at the sealing side. The shoulder comprises radially inwardly a circumferentially extending nose96. Between the nose96and a side wall30of the filter pot, a sealing groove98is formed which tapers in axial direction. The clean air seal20comprises at the bottom side (raw side) a circumferentially extending first sealing groove100that tapers in axial direction. A section of the clean air seal20, located radially outwardly of the sealing groove100, is forced in the mounted state by the pressure ring88into the sealing groove98so that this section of the clean air seal20is contacting seal-tightly walls of the sealing groove98.

FIG.15shows a second variant of a radially sealing clean air seal20of an air filter element according to the invention. The clean air seal20is illustrated in the compressed state between a shoulder86of a filter pot and a pressure ring88of a cover for the filter part. The shoulder86is embodied non-contoured. The pressure ring88is embodied radially outwardly with an annular contour101that is positioned at an acute angle relative to a common longitudinal axis of the filter element and of the filter pot. The clean air seal20comprises at the top side (clean side) a circumferentially extending second sealing groove102which tapers in the axial direction. A section of the clean air seal20, positioned radially outwardly of the sealing groove102, tapers therefore opposite to the sealing groove102. This section of the clean air seal20is pressed in the mounted state by the pressure ring88against a side wall30of the filter pot so that the clean air seal20is resting seal-tightly thereat.