Hollow filter element, filter housing, and filter

Abstract

A hollow filter element, including: a filter medium for filtering a fluid; wherein the filter element is a conical-oval rounded filter element; wherein the filter medium circumferentially surrounds an interior flow space of the filter element, wherein the filter medium circumferentially encloses around an element axis such that filter medium at least in one direction radial to the element axis is smaller on a first of the end sides of the filter medium than on a second of the end sides of the filter medium; wherein the filter medium has a first end body arranged at least on the smaller end side; wherein the first end body has at least one leveling element in the at least one direction of the smaller extent with respect to the element axis in a radially outer segment with respect to the element axis.

Claims

1. A hollow filter element, comprising: a filter medium for filtering a fluid; wherein the filter element is a conical-oval rounded filter element; wherein the filter medium circumferentially surrounds an interior flow space of the filter element, wherein the filter medium circumferentially encloses around an element axis such that filter medium at least in one direction radial to the element axis is smaller on a first of the end sides of the filter medium than on a second of the end sides of the filter medium; wherein the filter medium has a first end body arranged at least on the smaller end side; wherein the first end body has at least one leveling element in the at least one direction of the smaller extent with respect to the element axis in a radially outer segment with respect to the element axis; wherein the first end body has a leveling element arranged on opposite peripheral sides that are diagonally opposite in the at least one direction of the smaller extent with respect to the element axis; wherein a base area of the hollow filter element is elongated as an oval, at least in a region of the smaller end side; wherein an imaginary center point of the at least one leveling element is located on a minor axis of an imaginary plane that extends parallel to the base area of the hollow filter element; wherein center points of the opposite leveling elements are each located on the minor axis; wherein the at least one leveling element projects radially outward beyond the radial outer peripheral side of the filter medium, and projections axially outward beyond an axial outer end face of the end body, projecting in an axial direction away from the filter medium; a hollow cylindrical support element formed on and projecting axially outwardly from a central portion of the first end body; when the hollow filter element is assembled into or removed from a filter housing, the at least one leveling element slides along at least one guide track in the filter housing; when the at least one leveling element slides further along the at least one guide track of the filter housing, the hollow cylindrical support element is automatically inserted into a counter support groove of a supporting pillar in the filter housing.

2. The hollow filter element according to claim 1, wherein wherein a distance of a radially outer peripheral side of the at least one leveling element from the element axis corresponds approximately to a distance of the corresponding radially outer peripheral side of the hollow filter element from the element axis on the larger end side.

3. The hollow filter element according to claim 1, wherein the at least one leveling element is arranged spatially at the bottom of the filter element in a final installation position of the hollow filter element in a filter housing of a filter and in a typical operating position of the filter housing.

4. The hollow filter element according to claim 1, wherein the hollow filter element has at least one supporting element on an outer face on the smaller end side, which outer face faces away from the element interior space.

5. A filter housing of a filter for fluid, comprising an openable filter housing including a housing pot having an installation opening, a circumferentially closed outer wall and a bottom wall defining an interior chamber in the housing pot; a housing cover which closes over the installation opening; at least one inlet for fluid to be cleaned; and at least one outlet for cleaned fluid; wherein the filter housing is configured and adapted to receive a hollow filter element into the interior chamber of the filter housing such that the filter element is exchangeably arranged within the interior chamber of the filter housing, the hollow filter element having: a filter medium; wherein the filter medium circumferentially surrounds an interior flow space of the filter element, wherein the filter medium circumferentially encloses around an element axis such that filter medium at least in one direction radial to the element axis is smaller on a first of the end sides of the filter medium than on a second of the end sides of the filter medium; wherein the filter medium has a first end body arranged on the smaller end side: and wherein the first end body has at least one leveling element in the at least one direction of the smaller extent with respect to the element axis in a radially outer segment with respect to the element axis; wherein the filter housing is configured such that the filter element, when installed, seals to the housing to separate the at least one inlet from the at least one outlet; wherein the installation opening of the housing pot is sized and adapted for the filter element to be installed therethrough into the interior chamber; wherein the installation opening is crossed by and coaxial to the filter axis in an installed state of the hollow filter element; wherein the installation opening is at least as large as a greatest outside dimension of the hollow filter element radial to the filter axis; wherein the housing cover has a circumferentially closed outer wall and includes at least one guide track arranged on a radially inner surface of the circumferentially closed outer wall of the housing cover, the at least one guide track guiding and supporting at least one leveling element arranged radially outside with respect to the filter axis on a first end body of the hollow filter element; wherein the guide track extends at least by means of at least one imaginary main guide line in a plane having an installation axis of the installation of the hollow filter element into an interior space surround by the circumferentially closed outer wall of the housing cover; wherein the at least one guide track extends into a region outside the interior space of the housing cover.

6. The filter housing according to claim 5, wherein at least two guide tracks are located on diagonally opposite radially inner surfaces of the circumferentially closed outer wall of the housing cover with respect to the element axis.

7. The filter housing according to claim 5, wherein the housing pot or the housing cover has at least one connecting tab connecting to the other part of the filter housing.

8. The filter housing according to claim 6, wherein a base area of the installation opening is elongate or oval, and the main guide line of the at least one guide track is located in a minor plane having a minor axis of the base area of the installation opening and having the installation axis, and the main guide lines of the opposite guide tracks are each located in the minor plane.

9. The filter housing according to claim 5, wherein at least one supporting segment is arranged centrally in or on the filter housing with respect to a housing axis, which coincides with the element axis when the hollow filter element is in the installed state.

10. A filter for filtering air, water, fuel, oil, or urea-water solution for an internal combustion engine comprising an openable filter housing including a housing pot having an installation opening, a circumferentially closed outer wall and a bottom wall defining an interior chamber in the housing pot; a housing cover which closes over the installation opening; at least one inlet for fluid to be cleaned; and at least one outlet for cleaned fluid; a exchangeable hollow conical-oval rounded filter element, including: a filter medium; wherein the filter medium circumferentially surrounds an interior flow space of the filter element, wherein the filter medium circumferentially encloses around an element axis such that filter medium at least in one direction radial to the element axis is smaller on a first of the end sides of the filter medium than on a second of the end sides of the filter medium; wherein the filter medium has a first end body arranged on the smaller end side; wherein the first end body has at least one leveling element in the at least one direction of the smaller extent with respect to the element axis in a radially outer segment with respect to the element axis; wherein the filter element is exchangeably arranged within the interior chamber of the filter housing; wherein the filter element seals to the housing to separate the at least one inlet from the at least one outlet; wherein the installation opening of the housing pot is sized and adapted for the filter element to be installed therethrough into the interior chamber; wherein the installation opening is crossed by and coaxial to the filter axis in an installed state of the hollow filter element; wherein the installation opening is at least as large as a greatest outside dimension of the hollow filter element radial to the filter axis; wherein the housing cover has a circumferentially closed outer wall and includes at least one guide track arranged on a radially inner surface of the circumferentially closed outer wall of the housing cover, the at least one guide track guiding and supporting at least one leveling element arranged radially outside with respect to the filter axis on a first end body of the hollow filter element; wherein the at least one guide track extends at least by means of at least one imaginary main guide line in a plane having an installation axis of the installation of the hollow filter element into an interior space surround by the circumferentially closed outer wall of the housing cover; wherein the at least one guide track extends into a region outside the interior space of the housing cover.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages, features, and details of the invention result from the following description, in which an embodiment example of the invention is explained in more detail on the basis of the drawing. A person skilled in the art will advantageously also consider individually the features disclosed in combination in the drawing, the description and the claims and combine the said features into sensible further combinations.

(2) FIG. 1 schematically shows a top view of an air filter of an internal combustion engine having a filter housing assembled from a housing pot and from a housing cover, in which filter housing an exchangeable conical-oval rounded filter element is arranged;

(3) FIG. 2 schematically shows a transverse-side section of the air filter from FIG. 1 along the section line II-II;

(4) FIG. 3 schematically shows a longitudinal-side section of the air filter from FIG. 1 along the section line III-III;

(5) FIG. 4 schematically shows a first isometric angled view of the air filter from FIGS. 1 to 3;

(6) FIG. 5 schematically shows a second isometric angled view of the air filter from FIGS. 1 to 4;

(7) FIG. 6 schematically shows an isometric illustration of the open housing pot of the air filter from FIGS. 1 to 5, with the rounded filter element;

(8) FIG. 7 schematically shows an isometric illustration of the open housing pot of the air filter from FIGS. 1 to 6, here without the rounded filter element;

(9) FIG. 8 schematically shows an isometric illustration of the open housing pot of the air filter from FIGS. 1 to 7, without the rounded filter element, from a different prospective;

(10) FIG. 9 schematically shows an isometric illustration of the housing cover of the air filter from FIGS. 1 to 5, with the rounded filter element and without the housing pot;

(11) FIG. 10 schematically shows an isometric illustration of the housing cover of the air filter from FIGS. 1 to 5, without the rounded filter element;

(12) FIG. 11 schematically shows the isometric illustration of the housing cover from FIG. 10 from a different perspective;

(13) FIG. 12 schematically shows a side view of the air filter from FIGS. 1 to 5 in an early mounting phase of the mounting of the housing cover onto the housing pot;

(14) FIG. 13 schematically shows a top view of the air filter in the mounting phase from FIG. 12;

(15) FIG. 14 schematically shows a top view of the air filter in a mounting phase following the mounting phase illustrated in FIG. 13;

(16) FIG. 15 schematically shows an isometric illustration of the rounded filter element of the air filter from FIGS. 1 to 5;

(17) FIG. 16 schematically shows a transverse-side longitudinal section of the rounded filter element of the air filter from FIGS. 1 to 5;

(18) FIG. 17 schematically shows a longitudinal-side side view of the rounded filter element of the air filter from FIGS. 1 to 5;

(19) FIG. 18 schematically shows a transverse-side side view of the rounded filter element of the air filter from FIGS. 1 to 5;

(20) FIG. 19 schematically shows a top view of an inlet-side end plate of the rounded filter element of the air filter from FIGS. 1 to 5.

(21) In the figures, the same parts are provided with the same reference signs.

EMBODIMENT(S) OF THE INVENTION

(22) In FIGS. 1 to 14, an air filter 10 of an internal combustion engine of a utility vehicle is shown in different illustrations and assembly phases. The air filter 10 is arranged in an air intake tract of the internal combustion engine. The air filter 10 is used to clean combustion air, which is fed to the internal combustion engine for combustion.

(23) The air filter 10 comprises an openable filter housing 12. The filter housing 12 is flat-oval. The filter housing 12 is flattened in the direction of the short transverse axis of the filter housing 12 in relation to an oval filter housing having an approximately elliptical cross-section. In FIG. 3, a section along a short transverse axis of the filter housing 12 is shown. The filter housing 12 has a housing pot 14, on the left in FIGS. 1 and 3. The housing pot 14 has an installation opening 16, which, for example in FIGS. 6 to 8, is shown in the foreground, for installing a filter element 18. The installation opening 16 is closed by means of a housing cover 20, on the right in FIG. 1.

(24) The housing pot 14 has an outlet 22 for the filtered air, which outlet 22 leads into an outlet space segment 24 of the housing pot 14. The outlet 22 is connected to the internal combustion engine outside the filter housing 12 by means of air lines not shown.

(25) The housing cover 20 has an inlet 26 for air to be filtered, which inlet 26 leads into an inlet space segment 28 of the housing cover 20 and is connected to the environment outside the filter housing 12. Alternatively, the inlet 26 can also be arranged in a side wall of the housing pot 14.

(26) The filter element 18 is arranged in an element space segment 30 of the housing pot 14 in such a way that the filter element 18 separates the inlet 26 from the outlet 22. The element space segment 30 is located in a linear arrangement between the inlet space segment 28 and the outlet space segment 24.

(27) The inlet space segment 28, the element space segment 30, and the outlet space segment 24 are arranged one behind the other axially to a filter axis 32. For better understandability, the filter axis 32 is shown in FIG. 3, although the filter axis 32 lies outside of section plane II-III from FIG. 1, namely in front of the drawing plane.

(28) In the embodiment example shown, the filter axis 32 coincides with a housing axis of the filter housing 12 and, when the filter element 18 is in the installed state, coincides with an element axis of the filter element 18. In the present case, the filter axis 32 also coincides with an installation axis, along which the filter element 18 can be inserted into the housing pot 14 and removed from the housing pot 14. The filter axis 32 additionally coincides with an assembly axis, along which the housing cover 20 is mounted onto the housing pot 14. In the embodiment example explained in the description, the axes listed above are briefly referred to as the filter axis 32 for better clarity and understandability. When the terms axial/axially, radial/radially, peripheral/peripherally, or coaxial/coaxially are used below, these terms relate to the filter axis 32, unless otherwise stated.

(29) The installation opening 16 peripherally surrounds the filter axis 32. In the installed state of the filter element 18, the filter axis 32 crosses the installation opening 16. The inside dimension of the installation opening 16 is greater than the greatest outside dimension of the filter element 18 radial to the filter axis 32. A base area of the installation opening 16 is flat-oval in an elongate manner.

(30) The housing pot 14 has a peripherally closed sealing surface 34 axially between the element space segment 30 and the outlet space segment 24. The sealing surface 34 extends in the radial direction. The sealing surface 34 faces the housing cover 20. A seal 36 of the filter element 18 lies tightly against the sealing surface 34 in a peripherally closed manner.

(31) The radially inner cross-section of the element space segment 30 is larger than a radially outer cross-section of the sealing surface 34.

(32) An inflow annular space 38 is realized between a radially outer peripheral side of the filter element 18 and the radially inner peripheral side of the element space segment 30. The inflow annular space 38 is separated from the outlet space segment 24 by means of the seal 36.

(33) On the side facing the housing cover 20, the inflow annular space 38 is connected to the inlet space segment 28 by means of a peripheral gap 40. The inlet space segment 28 and the inflow annular segment 38 are located on the raw-air side of the filter element 18.

(34) A supporting pillar 42 is arranged on the housing cover 20. The supporting pillar 42 is integrally connected to the housing cover 20. The supporting pillar 42 is approximately coaxial to the filter axis 32. The supporting pillar 42 is arranged centrally with respect to the filter axis 32. The supporting pillar 42 extends in the inlet space segment 28 from an inner face of the housing cover 20 facing the filter element 18 to an inlet-side end side 66 of the filter element 18. The supporting pillar 42 is located on the raw-air side of the filter medium 64.

(35) A coaxial counter supporting groove 44, which extends peripherally with respect to a main axis of the supporting pillar 42, i.e., with respect to the filter axis 32, and which is shown for example in FIGS. 10 and 11, is arranged on the free end side of the supporting pillar 42 facing the filter element 18. The counter supporting groove 44 is an annular cavity in the supporting pillar 42 that is open toward the free end side of the supporting pillar 42.

(36) The housing pot 14 also has two connecting tabs 46 for connecting to the housing cover 20. The connecting tabs 46 are located on the flattened peripheral sides of the housing pot 14 lying opposite with respect to the filter axis 32. The connecting tabs 46 are each integrally fastened by means of one end to the free peripheral edge of the housing pot 14 that surrounds the installation opening 16. The connecting tabs 46 extend parallel to the assembly axis of the assembly of the housing cover 20 with the housing pot 14, i.e., parallel to the filter axis 32. Imaginary center axes of the connecting tabs 46 lies in an imaginary plane having the filter axis 32. This imaginary plane, as viewed in the direction of the filter axis 32, is tilted in relation to another imaginary plane having a minor axis of the oval installation opening 16. The imaginary center axes of the connecting tabs 46 are thus each laterally offset with respect to the minor axis on opposite sides, as can be seen in FIG. 2 for example.

(37) The inner faces of the connecting tabs 46 facing each other are smooth. The inner faces of the connecting tabs 46 each form a starting segment of corresponding guide ramps 48. The guide ramps 48 continue on the inner face of the housing pot 14. Respective radially outer peripheral sides of an outlet-side end plate 50 of the filter element 18 are guided on the guide ramps 48, for example at leveling elements 58, during the installation of the filter element 18 into the housing pot 14.

(38) The outer faces of the connecting tabs 46 facing away from each other are equipped with stabilizing profiles.

(39) On free edges of the connecting tabs 46 facing away from the free peripheral edge of the housing pot 14, the connecting tabs 46 are tapered in a wedge-like manner. This simplifies the insertion of the connecting tabs 46 into corresponding tab receptacles 52 of the housing cover 20 for connecting the housing pot 14 to the housing cover 20.

(40) The housing cover 20 has two tab receptacles 52. The tab receptacles 52 each match one of the connecting tabs 46 of the housing pot 14.

(41) The tab receptacles 52 are located on the flattened peripheral sides of the housing cover 20 lying opposite with respect to the filter axis 32. The tab receptacles 52 are each integrally arranged in the region of the free peripheral edge of the housing cover 20. The tab receptacles 52 are integrated in the peripheral wall of the housing cover 20.

(42) The tab receptacles 52 each extend parallel to the assembly axis of the assembly of the housing cover 20 with the housing pot 14, i.e., parallel to the filter axis 32. Imaginary center axes of the tab receptacles 52 lie in a plane having the filter axis 32. This plane, as viewed in the direction of the filter axis 32, is tilted in relation to an imaginary plane having a minor axis of the oval installation opening 16. The center axes of the tab receptacles 52 are thus laterally offset with respect to the minor axis on opposite sides, analogously to the center axes of the connecting tabs 46.

(43) The tab receptacles 52 are recesses that are peripherally closed with respect to the respective center axes of the tab receptacles 52, which center axes extend parallel to the filter axis 32. The connecting tabs 46 are each retained on all peripheral sides in the corresponding tab receptacle 52. The tab receptacles 52 have a corresponding insertion opening 54 for the corresponding connecting tab 46 on the side of the tab receptacles 52 facing the housing pot 14.

(44) When the housing cover 20 is in the mounted state, the connecting tabs 46 stabilize the peripheral-wall segments of the housing cover 20 mechanically and vice versa. The connecting tabs 46 support the peripheral-wall segments radially to the filter axis 32, i.e., radially to the element axis and to the housing axis.

(45) The housing cover 20 also has two guide tracks 56 for guiding and supporting corresponding leveling elements 58 of the filter element 18. The guide tracks 56 can be seen for example in FIGS. 9 to 11. The guide tracks 56 are located on diagonally opposite, radially inner peripheral sides of the housing cover 20 with respect to the filter axis 32.

(46) The guide tracks 56 are each realized on a guide arm 60. The guide arms 60 are integrally connected by means of a longitudinal side to the corresponding radially inner peripheral side of the peripheral wall of the housing cover 20 within an interior space of the housing cover 20, which interior space contributes to the formation of the inlet space segment 28. The opposite longitudinal sides of the guide arms 60 form the corresponding guide tracks 56.

(47) The guide arms 60 each protrude from the interior of the housing cover 20, for example. Particularly outside the housing cover 20, the guide arms 60 are each beveled on the radially inner longitudinal sides having the guide tracks 56. The corresponding guide tracks 56 thus extend toward the filter axis 32, as viewed in the direction filter axis 32 toward the interior of the housing cover 20.

(48) The guide tracks 56 each extend by means of an imaginary main guide line 62 in a plane having the assembly axis, i.e., the filter axis 32, of the assembly of the housing cover 20 with the housing pot 14 and the filter element 18. The main guide lines 62 specify a path of a contact region of the corresponding leveling element 58 during the sliding on the corresponding guide track 56 during the placement of the housing cover 20 onto the filter element 18. During the closing of the housing cover 20, the guide arms 60 thus touch the leveling elements 58 from radially outside in the region of the main guide line 62 and continuously raise the filter element 18 until the filter element 18 has reached the central end position thereof in the completely closed state. The main guide lines 62 are located in an imaginary minor plane, which is spanned by the minor axis of the flat-oval base area of the installation opening 16 and the filter axis 32.

(49) The filter element 18 described in more detail below is shown in different perspectives and sections in FIGS. 15 to 19. The filter element 18 is a flat conical-oval rounded filter element. The filter element 18 is coaxial to the element axis, i.e., to the filter axis 32.

(50) The filter element 18 has a flat-oval cross-section. The short transverse axis, i.e., the minor axis, of the oval lies in the drawing plane of FIG. 15, and the long transverse axis, i.e., the major axis, is perpendicular to the drawing plane. The filter element 18 is additional flattened in the direction of the short transverse axis, thus the designation flat conical-oval. In contrast thereto, oval refers to an approximately elliptical cross-section. A radially outer peripheral side and a radially inner peripheral side of the filter element 18 each have a conical course in the direction of the filter axis 32. The outside cross-section and the inside cross-section of the filter element 18 are tapered from the outlet-side end side 68 of the filter element 18 facing the outlet space segment 24 to the inlet-side end face 66.

(51) The direction of the minor axis of the flat-oval filter element 18 extends spatially vertically in the final installation position in the typical operating position. The filter axis 32 extends spatially horizontally in the installation position in the typical operating position.

(52) The filter element 18 comprises a filter medium 64 that is folded into a filter bellows in a zig-zag shape and that is peripherally closed with respect to the element axis, i.e., the filter axis 32. The filter medium 64 is a filter nonwoven suitable for filtering air.

(53) The extent of the filter bellows composed of filter medium 64 in a direction radial to the element axis, i.e., to the filter axis 32, is less on the inlet-side end side 66 of the filter medium 64 than on the outlet-side end side 68 of the filter medium 64.

(54) On the outlet-side end side 68 of the filter medium 64, the filter medium 64 is connected to the outlet-side end plate 50. The outlet-side end plate 50 is coaxial to the filter axis 20. The outlet-side end plate 50 is made of a plastic. The outlet-side end plate 50 is tightly adhesively bonded to the end side 68 of the filter medium 64. The radially outer peripheral side of the outlet-side end plate 50 lies against the radially inner peripheral side of the housing pot 14 there with minimal play.

(55) The outlet-side end plate 50 has a central, coaxial outflow opening 70. The outflow opening 70 extends over the entire radially inner cross-section of the filter medium 64. An element interior space 72 of the filter element 18, which element interior space 72 is surrounded by the filter medium 64, is connected to the outlet space segment 24 by means of the outflow opening 70.

(56) The seal 36 is arranged on the outer face of the outlet-side end plate 50 that axially faces away from the filter medium 64. The seal 36 is composed of elastic polyurethane foam. The seal 36 is foamed onto the outlet-side end plate 50. The seal 36 is coaxial to the element axis, i.e., to the filter axis 32, and peripherally surrounds the outflow opening 70. The seal 36 extends in the axial direction. The seal 36 is supported in the axial direction on the sealing surface 34 of the housing pot 14.

(57) On the inlet-side end side 66, the filter medium 64 is tightly connected to an inlet-side end plate 74. The inlet-side end plate 74 is composed of polyurethane. The inlet-side end plate 74 closes the element interior space 72 toward the inlet space segment 28. The inlet-side end plate 74 is tightly connected to the filter medium 64 similarly to the outlet-side end plate 50.

(58) A coaxial supporting tube 76 extends in the element interior space 72, between the inlet-side end plate 74 and the outlet-side end plate 50. The supporting tube 76 is composed of plastic. The supporting tube 76 has a lattice-like construction. The peripheral side of the supporting tube 76 is permeable to air. The supporting tube 76 has a flat conical-oval shape that corresponds to the filter medium 64. The radially inner peripheral side of the filter medium 64 can be supported on the radially outer peripheral side of the supporting tube 76.

(59) A supporting element 78 is arranged on the axial outer face of the inlet-side end plate 74 facing away from the element interior space 72. The supporting element 78 is located on the raw-air side of the filter medium 64. The supporting element 78 is firmly connected to the inlet-side end plate 74. The supporting element 78 is composed of an elastic polyurethane foam. The supporting element 78 is foamed onto the inlet-side end plate 74.

(60) The supporting element 78 is sleeve-like. The supporting element 78 has the shape of a hollow cylinder, the main axis of which extends coaxially to the filter axis 32, i.e., to the element axis, in the embodiment example shown. A cavity 80 of the supporting element 78 is open on the end side of the supporting element 78 facing away from the inlet-side end plate 74. The supporting element 78 has an approximately oval cross-section. The short transverse axis of the supporting element 78 lies in the drawing plane in FIG. 16, and the long transverse axis of the supporting element 78 is perpendicular to the drawing plane. When the filter element 18 is in the installed state, the orientation of the supporting element 78 with respect to the filter axis 32 corresponds to the orientation of the supporting pillar 42 of the housing cover 20.

(61) The segment of the supporting pillar 42 surrounded by the counter supporting groove 44 is inserted into the cavity 80 of the supporting element 78 when the filter element 18 is correctly mounted. The peripheral wall of the supporting element 78 is inserted into the counter supporting groove 44 of the supporting pillar 42.

(62) On the free side of the supporting element 78 facing away from the end plate 74, the wall thickness of the supporting element 78 decreases in a conical segment toward the free edge. The insertion of the supporting element 78 into the counter supporting groove 44 of the supporting pillar 42 can thus be simplified.

(63) By means of the supporting element 48, the filter element 18 is supported against the filter housing 12 via the supporting pillar 42. The support occurs radially, i.e., transversely to the filter axis 32, i.e., transversely to the element axis and to the housing axis, and axially. The interaction of the supporting element 48 with the supporting pillar 42 contributes to the radial and axial retention and positioning of the filter element 18 on the inlet side, i.e., on the raw-air side. A contribution to the retention of the filter element 18 in the filter housing 12 on the side facing the inlet space segment 28 can thus be made.

(64) Furthermore, two supporting webs 82 are arranged on the radially outer edges of the inlet-side end plate 74 in the region of each of the short transverse sides. The supporting webs 82 each protrude beyond the inlet-side end plate 74 both in the radial direction and in the axial direction. The supporting webs 82 are each supported at corresponding supporting points 83 on the inner face of the housing cover 20 in the radial direction, which supporting points 83 are shown, among other things, in FIGS. 3, 10, and 11.

(65) The leveling elements 58 mentioned above are located radially outside with respect to the element axis, i.e., the filter axis 32, on the inlet-side end plate 74. The leveling elements 58 are composed of polyurethane. The leveling elements 58 are integrally connected to the inlet-side end plate 74. The leveling elements 58 are arranged on a raw-air side of the filter element 18.

(66) The leveling elements 58 are arranged on peripheral sides of the inlet-side end plate 74 that are diagonally opposite with respect to the filter axis 32. Imaginary center points of the leveling elements 58 are located on a minor axis of a flat-oval cross-section of the filter element 18. In the direction of the minor axis, the filter bellows of the filter element 18 has a smaller radial extent on the inlet-side end side 66 than on the outlet-side end side 68. The minor axis lies in an imaginary plane that extends parallel to the flat-oval base area of the filter element 18. The minor axis is the short axis of the imaginary plane through the center point of the imaginary plane. In contrast thereto, the major axis is the long axis of the imaginary plane through the center point of the imaginary plane.

(67) The leveling elements 58 each extend radially and axially outward beyond the radially outer peripheral side of the filter bellows of the filter medium 64 and of the inlet-side end plate 74.

(68) Distances of the radially outer peripheral sides of the leveling elements 58 from the filter axis 32 correspond to distances of the corresponding radially outer peripheral side of the outlet-side end plate 50 from the filter axis 32.

(69) One of the leveling elements 58 is arranged spatially at the bottom in the final installation position of the filter element 18 in the filter housing 12 in the typical operating position of the filter housing 12.

(70) By means of the leveling elements 58, a uniform radial distance with respect to the filter axis 32 between the radially outer periphery of the inlet-side end plate 74 and a facing radially inner periphery of the housing cover 20 is realized in order to form the gap 40.

(71) When the filter housing 12 is in the assembled state, the tab receptacles 52 having the connecting tabs 46 are each arranged approximately on the same peripheral side of the filter housing 12 as one of the guide tracks 56 for one of the leveling elements 58. The tab receptacles 52/connecting tabs 46 and the corresponding leveling elements 58/guide tracks 56 are arranged peripherally at an offset from each other, wherein the tab receptacles 52/connecting tabs 46 overlap with the corresponding leveling elements 58/guide tracks 56 as viewed in the radial direction.

(72) The guide tracks 56 are each arranged between one of the leveling elements 58 and one of the tab receptacles 52/connecting tabs 46. The guide tracks 56 are supported against a pressure of the leveling elements 58 by means of the connecting tabs 46/tab receptacles 52. The leveling elements 58 press from inside against the corresponding peripheral-wall segment of the housing cover 20. The connecting tabs 46 and the corresponding tab receptacles 52 each counter from outside.

(73) During the operation of the air filter 10, the air to be filtered flows through the inlet 26, indicated by an arrow 84 in FIG. 1, into the inlet space segment 28. From there, the air passes substantially in the axial direction through the gap 40 into the inflow annular space 38 on the inflow side of the filter medium 64. The air flows through the filter medium 64 from radially outside to radially inside and is cleaned. The cleaned air flows through the peripheral side of the supporting tube 76 and enters the element interior space 72. The cleaned air leaves the element interior space 72 substantially in the axial direction and enters the outlet space segment 24. From there, the filtered air leaves the filter housing 12 through the outlet 22, indicated by an arrow 86 in FIG. 1.

(74) The filter housing 12 can be opened for maintenance purposes, for example for cleaning or exchanging the filter element 18. For this purpose, the housing cover 20 is removed from the housing pot 14 in the axial direction. In the process, the supporting element 78 is automatically pulled out of the counter supporting groove 44 at the end of the supporting pillar 42. The connecting tabs 46 are pulled out of the tab receptacles 52. The leveling elements 58 slide along the guide tracks 56. The filter element 18 is pulled out of the element space segment 30 of the housing pot 14 in the axial direction. The filter element 18 can be replaced with a new filter element 18 or reinstalled after the cleaning.

(75) For installation, the filter element 18 is inserted with the outlet-side end plate 50 first into the housing pot 14 in the axial direction until the seal 36 lies against the sealing surface 34. Then the housing cover 20 is set with the open side thereof first onto the installation opening 16 of the housing pot 14 in the axial direction. For this purpose, the connecting tabs 46 are inserted into the respective tab receptacles 52. The housing cover 20 is thus pre-adjusted on the housing pot 14.

(76) As the housing cover 20 is slid onto the housing pot 14 in the axial direction, the connecting tabs 46 and the tab receptacles 52 interact as a guiding aid. As soon as the free ends of the guide arms 60 of the housing cover 20 reach the leveling elements 58, the guide arms 60 encompass the leveling elements 58 from outside on radially opposite sides. As the housing cover 20 is slid on further, the leveling elements 58 are then guided along the main guide lines 62 of the guide tracks 56 of the guide arms 60. The side of the filter element 18 having the inlet-side end plate 74 is continuously raised into the end position of the filter element 18 by means of the lower guide tracks 56 as the housing cover 20 is slid further. The filter element 18 is positioned and centered in the housing cover 20. Finally, during the further sliding, the supporting element 78 of the housing cover 20 is automatically inserted into the counter supporting groove 44 of the supporting pillar 42. In the process, the radially inner segment at the end of the supporting pillar 42 is inserted into the cavity 80 of the supporting element 78. The element axis extends coaxially to the housing axis in the correct installed state. The housing cover 20 is finally fastened to the housing pot 14 in a manner that is of no further interest here.