Brake Dust Particle Filter and Disc Brake Assembly Comprising a Brake Dust Particle Filter

Abstract

A brake dust particle filter, for catching particles produced when braking, for a disc brake assembly with a brake disc and a brake caliper has a ring segment-shaped housing with a housing interior that accommodates the brake disc. The housing has two housing sidewalls that are axially spaced apart and a housing peripheral wall extending radially outwardly in a circumferential direction of the housing. The housing peripheral wall is arranged between the two housing sidewalls. At least one tongue projects with at least one radial component from the housing peripheral wall into the housing interior. The tongue has a flat cross-sectional shape and at least one base surface facing the housing peripheral wall, a cover surface projecting into the housing interior, and at least one side surface. The tongue supports a filter medium and is covered at least at the at least one side surface with the filter medium.

Claims

1. A brake dust particle filter for a disc brake assembly with a brake disc and a brake caliper, wherein the brake dust particle filter is configured for catching particles produced when braking, the brake dust particle filter comprising: a ring segment-shaped housing comprising a housing interior and configured to at least partially accommodate the brake disc in the housing interior; the ring segment-shaped housing comprising housing walls, including two housing sidewalls that are axially spaced apart from each other and further including a housing peripheral wall extending radially outwardly in a circumferential direction of the ring segment-shaped housing, wherein the housing peripheral wall is arranged between the two housing sidewalls; at least one first tongue arranged in the housing interior and projecting at least in sections with at least one radial component from the housing peripheral wall inwardly, wherein the at least one first tongue comprises a flat cross-sectional shape and comprises at least one base surface facing the housing peripheral wall, a cover surface projecting into the housing interior, and at least one side surface; at least one filter medium; wherein the at least one first tongue supports the at least one filter medium and is covered at least at the at least one side surface with the at least one filter medium.

2. The brake dust particle filter according to claim 1, wherein the flat cross-sectional shape of the at least one first tongue has a substantially rectangular cross section with a wide side and a narrow side, wherein a ratio of the wide side to the narrow side is between 15 and 60.

3. The brake dust particle filter according to claim 1, wherein the at least one first tongue is arranged or embodied at one of the housing walls such that the at least one filter medium is connected indirectly or directly to said housing wall.

4. The brake dust particle filter according to claim 1, further comprising a filter element with a filter element support structure, wherein the filter element includes the least one filter medium, wherein the filter element support structure includes the at least one first tongue, and wherein the filter element is arranged in the ring segment-shaped housing.

5. The brake dust particle filter according to claim 4, wherein the at least one filter medium is fastened to one or more elements selected from the group consisting of the at least one first tongue; the housing walls; and the filter element support structure.

6. The brake dust particle filter according to claim 1, further comprising at least one second tongue projecting into the housing interior from at least one the two housing sidewalls.

7. The brake dust particle filter according to claim 6, wherein the at least one first tongue and the at least one second tongue form a continuous tongue which has an L-shaped or U-shaped basic form.

8. The brake dust particle filter according to claim 1, wherein the at least one filter medium forms a fold into which the at least one first tongue projects at least partially.

9. The brake dust particle filter according to claim 1, wherein the at least one first tongue comprises one or more through openings covered by the at least one filter medium.

10. The brake dust particle filter according to claim 1, wherein the at least one filter medium in a region of the at least one first tongue forms a catching pocket for particles, wherein the catching pocket in a mounted state of the brake dust particle filter is closed in a downward direction to prevent escape of the particles due to gravity acting on the particles.

11. The brake dust particle filter according to claim 1, wherein the at least one filter medium comprises a first region and a second region, wherein the first region is a first filter layer and the second region is a second filter layer, wherein the second filter layer comprises a larger porosity than the first filter layer, wherein the first filter layer is arranged between the second filter layer and the at least one first tongue.

12. The brake dust particle filter according to claim 1, further comprising an additional filter medium comprising a porosity that is larger than a porosity of the at least one filter medium, wherein the at least one filter medium is arranged as a first filter layer between the at least one first tongue and the additional filter medium forming a second filter layer.

13. The brake dust particle filter according to claim 1, wherein a plurality of the at least one first tongue project inwardly into the housing interior and are spaced apart from each other in the circumferential direction.

14. The brake dust particle filter according to claim 13, wherein two or more of the plurality of the first tongues are positioned at a different angle relative to the housing peripheral wall, respectively.

15. The brake dust particle filter according to claim 1, configured such that an increase of a filter action on air being moved by the brake disc in the circumferential direction of the ring segment-shaped housing is provided in the circumferential direction.

16. The brake dust particle filter according to claim 15, wherein the increase of the filter action is provided in that a porosity of the at least one filter medium decreases, beginning at a bearing region of the brake dust particle filter provided for bearing against the brake caliper, in the circumferential direction of the ring segment-shaped housing.

17. The brake dust particle filter according to claim 16, wherein a plurality of the at least one first tongue project inwardly into the housing interior and are spaced apart from each other in the circumferential direction, wherein the porosity of the at least one filter medium is larger at one of the plurality of the first tongues closer to the bearing region than at a neighboring one of the plurality of the first tongues farther removed from the bearing region.

18. The brake dust particle filter according to claim 15, wherein the increase of the filter action is provided in that a thickness of the at least one filter medium increases, beginning at a bearing region of the brake dust particle filter provided for bearing against the brake caliper, in the circumferential direction of the ring segment-shaped housing.

19. The brake dust particle filter according to claim 15, wherein the increase of the filter action is provided in that a plurality of the at least one first tongue project inwardly into the housing interior and are spaced apart from each other in the circumferential direction in a direction away from a bearing region of the brake dust particle filter provided for bearing against the brake caliper, wherein one of the plurality of the first tongues closer to the bearing region is positioned at a smaller angle relative to the housing peripheral wall than a neighboring one of the plurality of tongues farther removed from the bearing region.

20. The brake dust particle filter according to claim 15, wherein the increase of the filter action is provided in that a plurality of the at least one first tongue project inwardly into the housing interior and are spaced apart from each other in the circumferential direction in a direction away from a bearing region of the brake dust particle filter provided for bearing against the brake caliper, wherein one of the plurality of the first tongues closer to the bearing region comprises more and/or larger through openings than a neighboring one of the plurality of the first tongues farther removed from the bearing region.

21. The brake dust particle filter according to claim 15, wherein the increase of the filter action is provided in that a plurality of the at least one first tongue project inwardly into the housing interior and are spaced apart from each other in the circumferential direction in a direction away from a bearing region of the brake dust particle filter provided for bearing against the brake caliper, wherein a free end of one of the plurality of the first tongues projects less far radially inwardly into the housing interior of the ring segment-shaped housing than a free end of a neighboring one of the plurality of the first tongues farther removed from the bearing region.

22. The brake dust particle filter according to claim 15, wherein the increase of the filter action is provided in that a plurality of the at least one first tongue project inwardly into the housing interior and are spaced apart from each other in the circumferential direction in a direction away from a bearing region of the brake dust particle filter provided for bearing against the brake caliper, wherein a surface of one of the plurality of first tongues closer to the bearing region is smaller than a surface of a neighboring one of the plurality of the first tongues farther removed from the bearing region.

23. The brake dust particle filter according to claim 1, further comprising one or more openings disposed in one of the housing walls and configured to discharge filtered air.

24. The brake dust particle filter according to claim 23, wherein the one or more openings are disposed in the housing peripheral wall.

25. The brake dust particle filter according to claim 1, further comprising a housing end region, viewed in the circumferential direction of the ring segment-shaped housing, configured to at least partially cover the brake caliper at an outer circumference thereof, wherein in the housing end region one or more openings configured to discharge filtered air are provided.

26. The brake dust particle filter according to claim 1, further comprising one or more outwardly projecting ribs arranged or embodied at one of the housing walls.

27. The brake dust particle filter according to claim 26, wherein said one of the housing walls is the housing peripheral wall, wherein the one or more outwardly projecting ribs each are arranged adjacent to an opening and cover the opening at least partially relative to a predetermined inflow direction of air.

28. The brake dust particle filter according to claim 1, wherein the at least one filter medium comprises at least one material selected from the group of a metal, a metal fiber nonwoven, glass, ceramic, and a high temperature-resistant plastic material, wherein the at least one filter medium is preferably still resistant at a temperature of more than 600 C.

29. The brake dust particle filter according to claim 28, wherein the high temperature-resistant plastic material is polyether ether ketone.

30. The brake dust particle filter according to claim 1, wherein the ring segment-shaped housing extends about a ring segment angle of at least 45.

31. A disc brake assembly comprising a brake disc, a brake caliper, and a brake dust particle filter according to claim 1.

32. The disc brake assembly according to claim 31, wherein the brake dust particle filter is arranged stationarily relative to the brake caliper or is fastened to the brake caliper.

33. The disc brake assembly according to claim 31, further comprising a wheel bearing housing, wherein the brake dust particle filter is stationarily arranged relative to the wheel bearing housing or is fastened to the wheel bearing housing.

34. The disc brake assembly according to claim 31, further comprising a splash guard, wherein the brake dust particle filter is stationarily arranged relative to the splash guard; is fastened to the splash guard; or a first housing part of the ring segment-shaped housing forms the splash guard.

35. The disc brake assembly according to claim 31, wherein the brake dust particle filter adjoins flush the brake caliper in the circumferential direction of the ring segment-shaped housing.

36. The disc brake assembly according to claim 35, wherein the brake dust particle filter is arranged downstream of the brake caliper, viewed in a rotational direction of the brake disc for intended forward travel.

37. The disc brake assembly according to claim 31, wherein the brake dust particle filter covers an outer side of the brake caliper at least partially.

38. The disc brake assembly according to claim 37, wherein the ring segment-shaped housing of the brake dust particle filter comprises a housing end region, wherein the housing end region covers the outer side of the brake caliper, wherein the outer side of the brake caliper is a circumferential outer side.

39. The disc brake assembly according to claim 31, wherein the at least one first tongue of the brake dust particle filter comprises a free end oriented toward the brake caliper.

40. The disc brake assembly according to claim 39, wherein the brake dust particle filter comprises a plurality of the at least one first tongue, wherein the free ends of the plurality of the at least one first tongue are oriented toward the brake caliper.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0051] FIG. 1 shows a side view of a disc brake assembly according to the invention with a first embodiment of the brake dust particle filter.

[0052] FIG. 2 shows a cross section of the brake dust particle filter according to FIG. 1.

[0053] FIG. 3 is an isometric view of the brake dust particle filter according to FIG. 1.

[0054] FIG. 4 is an isometric view of a first housing part and of a second housing part of the housing of a brake dust particle filter in a second embodiment of the disc brake assembly.

[0055] FIG. 5 is an isometric view of the first housing part of the housing of the brake dust particle filter of a third embodiment of the disc brake assembly with inwardly projecting tongues and a second housing part with openings and outwardly projecting ribs.

[0056] FIG. 6 is an isometric view of the connection of a first housing part and of a second housing part of a fourth embodiment of the disc brake assembly by a pivot mechanism and/or a folding mechanism.

[0057] FIG. 7 is an isometric view of the connection of the first housing part and of the second housing part by a pivot mechanism and/or a folding mechanism along a further pivot axis in a fifth embodiment of the disc brake assembly.

[0058] FIG. 8 is an isometric view of a brake dust particle filter according to a further embodiment with tongues at a housing peripheral wall as well as at a housing sidewall.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0059] FIG. 1 shows a side view of a disc brake assembly 10 with a disc brake 12 which comprises an axis of rotation or rotary axis 13, with a brake caliper 14 and a brake dust particle filter 16 in a first embodiment. In this context, the brake dust particle filter 16 is stationarily arranged in its position relative to the brake caliper 14 and/or attached to the brake caliper 14. The disc brake assembly 10 comprises moreover a wheel bearing housing (not illustrated) to which the brake caliper 14 is fastened, and the brake dust particle filter 16 can be stationarily arranged in its position relative to the wheel bearing housing and/or fastened to the wheel bearing housing. Alternatively or additionally thereto, the disc brake assembly 10 can comprise a splash guard (not illustrated) in the form of a splash guard plate, and the brake dust particle filter 16 can be arranged stationarily in its position relative to the splash guard and/or can be fastened to the splash guard.

[0060] The brake dust particle filter 16 comprises a first housing sidewall 17 which forms a part of a ring segment-shaped housing 18. A second housing sidewall 19 (see FIG. 2) is arranged, spaced apart axially along the rotary axis 13 of the brake disc 12, relative to the first housing sidewall 17 and also forms a part of the ring segment-shaped housing 18, and between them the brake disc 12 is received in the housing interior 20.

[0061] The brake dust particle filter 16 can be arranged downstream of the brake caliper 14, in particular in rotation direction R of the brake disc 12 upon forward travel of a vehicle at which the disc brake assembly 10 can be arranged.

[0062] In FIG. 2, a cross section of the brake dust particle filter 16 for filtering air that is provided with brake dust is illustrated. By means of the ring segment-shaped housing 18, the brake dust particle filter 16 can accommodate the brake disc 12 (see FIG. 1) at least partially in the housing interior 20. The ring segment-shaped housing 18 can extend about a ring segment angle of more than 90 in this embodiment. The brake dust particle filter 16 is arranged flush at the brake caliper 14 (see FIG. 1) so that, when braking, air moved by the brake disc 12 (see FIG. 1) can flow from the brake caliper 14 into the brake dust particle filter 16.

[0063] The housing 18 comprises a housing peripheral wall 26 which extends radially outwardly in circumferential direction of the brake dust particle filter 16. The housing sidewalls 17 (see FIG. 1), 19 are connected to each other by the housing peripheral wall 26.

[0064] The brake dust particle filter 16 comprises moreover tongues 28a, 28b, 28c, 28d. These tongues 28a-28d are arranged at the housing peripheral wall 26 of the brake dust particle filter 16 or embodied as in FIG. 2. They project in the housing interior 20 of the brake dust particle filter 16 from the housing peripheral wall 26 inwardly. In this context, they are positioned relative to the housing peripheral wall 26 at an angle .sub.1, .sub.2, .sub.3, .sub.4, respectively. At these tongues 28a-28d, the air which flows into the brake dust particle filter 16 can be guided in the direction toward the housing peripheral wall 26. The tongues 28a-28d are oriented with their respective free ends 30a, 30b, 30c, 30d toward the brake caliper 14 (see FIG. 1).

[0065] A filter medium 32 for cleaning the air from particles is arranged at the tongues 28a-28d and covers the tongues 28a-28d. The filter medium 32 extends across the side of the respective tongue 28a-28d which is facing the housing peripheral wall 26 as well as across the side which is facing away from the housing peripheral wall 26 so that the tongues 28a-28d are covered by the filter medium 32, respectively. The filter medium is a continuous material strip which extends across all tongues 28a-28d as well as across the inner side of the housing peripheral wall 26 in the housing end region 52.

[0066] In an exemplary fashion, the facing side is here identified at the tongue 28a by 34 and the side that is facing away by 36. The effective filter surface is thus enlarged by the tongues 28a-28d in circumferential direction of the housing interior 20. The filter medium 32 is moreover arranged at the sections 38a, 38b, 38c of the housing peripheral wall 26 between the tongues 28a-28d. In this way, the filter medium 32 is connected immediately to the housing peripheral wall 26. In particular, it is attached to the housing peripheral wall 26 and/or to the tongues 28a-28d. Alternatively, it can be connected also indirectly to the wall of the housing 18 by means of further intermediate layers. The tongues 28a-28d can comprise one or a plurality of through openings (not shown) which are covered by the filter medium 32.

[0067] The tongues 28a-28d form a support structure 40 for the filter medium 32. For this purpose, the tongues 28a-28d project into folds 42a, 42b, 42c, 42d of the filter medium 32.

[0068] The filter medium 32 can comprise at least a first region and a second region (not shown). The first region can be embodied between the respective tongues 28a-28d and the second region. In this context, for coarse filtration the first region can comprise a larger porosity than the second region. The filter medium in addition can also comprise a third and/or further such regions of different porosities. As an alternative thereto, the transition from a larger porosity of the filter medium to a smaller porosity in the direction of the tongue 28a-28d can also be continuously realized (gradient).

[0069] In a further embodiment, the brake dust particle filter comprises, in addition to the filter medium 32, an additional filter medium (not illustrated). In this context, the filter medium 32 is arranged between the respective tongue 28a-28d and the additional filter medium. The additional filter medium comprises a larger porosity than the first filter medium. In an alternative embodiment, the brake dust particle filter 16 can comprise additional filter media with different porosity.

[0070] The brake dust particle filter 16 can be designed such that the filter action on the air moved in the circumferential direction by the brake disc 12 increases. For this purpose, the porosity of the filter medium 32 can decrease in circumferential direction of the housing, beginning at a bearing region 44 of the brake dust particle filter 16 provided for bearing against the brake caliper 14 (see FIG. 1). Alternatively or in addition thereto, the thickness of the filter medium 32 can increase in the circumferential direction of the housing 18, beginning at the bearing region 44 of the brake dust particle filter 16 provided for bearing against the brake caliper 14 (see FIG. 1). Alternatively or additionally thereto, a tongue 28a-28d can be positioned at a smaller angle .sub.1, .sub.2, .sub.3, .sub.4 relative to the housing peripheral wall 26 than a neighboring tongue 28a-28d which is located farther away from the aforementioned bearing region 44. Alternatively or additionally thereto, the free end 30a-30d of a tongue 28a-28d can project less far radially inwardly into the interior 20 of the housing 18 than a neighboring tongue 28a-28d which is located farther away from this bearing region 44. Alternatively or additionally thereto, the surface of at least one tongue 28a-28d that projects into the housing interior 20 can be smaller than the surface of a neighboring tongue 28a-28d which projects into the housing interior 20 and which is farther removed from this bearing region 44.

[0071] The brake dust particle filter 16 comprises in its housing peripheral wall 26 openings 46a, 46b (see FIG. 3). Through these openings 46a, 46b the purified air can escape to the exterior space. A part of the openings 46a, 46b is completely covered by the tongues 28a-28d covered by the filter medium 32 in the direction away from the housing interior 20 perpendicular to the circumferential direction of the brake dust particle filter 16. Another part of the openings 46a, 46b is covered only by the filter medium 32. In this way, it is ensured that as a whole only purified air can escape through the openings 46a, 46b to the exterior space.

[0072] Moreover, ribs are arranged and/or embodied outward at the housing peripheral wall 26 at the exterior side 48 and two of them are identified in an exemplary fashion by 50a, 50b. The ribs 50a, 50b are arranged at the openings 46a, 46b so that the air that escapes outwardly is guided by the ribs 50a, 50b in a desired direction. The ribs 50a, 50b prevent a flow through the filter medium from the clean side to the raw side by a dynamic pressure that is generated by the travel speed.

[0073] The brake dust particle filter 16 comprises a housing end region 52. The housing end region 52 can comprise at least partially the housing sidewalls 17, 19 and the housing peripheral wall 26. Also, it comprises the filter medium 32 arranged at the housing peripheral wall 26. Outwardly projecting ribs 50a, 50b and openings 46a, 46b in the housing peripheral wall 26 at the ribs 50a, 50b are also arranged and/or embodied in the housing end region 52. The housing peripheral wall 26 extends into the housing end region 52. The housing end region 52 covers in circumferential direction of the brake dust particle filter 16, beginning at the radial outer side of the brake dust particle filter 16, the brake caliper 14, in particular a gap 56 of the brake caliper 14 (see FIG. 4). The housing end region 52 comprises for this purpose a cutout which can be matched to the respective shape of the brake caliper, here a brake caliper with at least two pistons.

[0074] FIG. 3 shows an isometric view of the brake dust particle filter 16. In particular, the outwardly oriented ribs 50a, 50b as well as the openings 46a, 46b can be seen. The housing 18 can be embodied as one part, i.e., one piece.

[0075] As illustrated in FIG. 4, the housing 18 of the brake dust particle filter 16 in a second embodiment of the disc brake assembly 10 can comprise a first housing part 58 and a second housing part 60. The first housing part 58 comprises in this context the first housing sidewall 17. The second housing part 60 comprises the second housing sidewall 19 which is axially displaced relative to the first housing sidewall 17. Thus, the first housing sidewall 17 can be arranged axially displaced along the rotary axis 13 of the brake disc 12 relative to the brake disc 12, and the second housing sidewall 19 can be arranged at the side of the brake disc 12 facing away from the first housing sidewall 17. The first housing part 58 comprises openings 46a, 46b. The second housing part 60, in particular the second housing sidewall 19, can be embodied in the form of a splash guard plate so that, in case of doubt, a separate splash guard plate of the brake disc can be omitted, which is in particular of interest for OE applications.

[0076] As illustrated in FIG. 5, in a third embodiment of the disc brake assembly 10 the first housing part 58 of the housing 18 can comprise the inwardly projecting tongues 28a-28d. The second housing part 60 can comprise the openings 46a, 46b and the outwardly oriented ribs 50a, 50b. The inwardly projecting tongues 28a-28d can be formed by punching out of the housing peripheral wall 62 of the first housing part 58. The outwardly projecting ribs 50a, 50b can be embodied together with the openings 46a, 46b by punching out the ribs 50a, 50b out of the housing peripheral wall 64 of the second housing part 60. Punching out the ribs 50a, 50b and the tongues 28a-28d in circumferential direction of the brake dust particle filter 16 in the mounted state at the respective housing peripheral wall 62, 64 can be realized for each pair of associated tongues 28a-28d and ribs 50a, 50b at the same location. Then by pushing on the first housing part 58 onto the second housing part 60 it can be ensured in a simple way that the openings 46a, 46b are formed at the correct locations between a respective tongue 28a-28d and rib 50a, 50b, i.e., the openings 46a, 46b are positioned with precise fit above the intermediate spaces between the respective neighboring tongues 28a-28d.

[0077] The first housing part 58 and the second housing part 60 can be connected to each other. In particular, they are connectable reversibly to each other in order to be able to perform servicing work quickly. This connection can be realized inter alia by a screw connection of the brake dust particle filter. For this purpose, a housing part 58, 60 can comprise a thread at its outer side and the other housing part 58, 60 a thread at its inner side such that one housing part 58, 60 can be screwed onto the other housing part 58, 60. Alternatively or additionally thereto, the first housing part 58 and the second housing part 60 can be connected by a weld connection, a clip connection, and/or a crimped connection.

[0078] As illustrated in FIG. 6, in a fourth embodiment of the disc brake assembly 10, the first housing part 58 and the second housing part 60 can be connectable and/or are connected to each other by a pivot mechanism and/or a folding mechanism in order to be able to open and close again quickly the brake dust particle filter 16. The pivot axis 66 of the pivot mechanism can extend in this context parallel to an axis 68 which connects the two housing sidewalls 17, 19 or extends through them, and in this case extends additionally parallel to the axis of rotation of the brake disc. Then, the housing peripheral wall 26 can be pivoted relative to the two housing sidewalls 17, 19.

[0079] Alternatively or additionally thereto, in a fifth embodiment of the disc brake assembly 10, the pivot axis 66 of the pivot mechanism can extend perpendicular to the outer circumferential side 70 of the housing peripheral wall 26 of the brake dust particle filter 16 in the mounted state, as illustrated in FIG. 7. Then, the first housing sidewall 17 can be pivoted relative to the second housing sidewall 19 and the housing peripheral wall 26.

[0080] When reviewing all Figures of the drawing, the invention in summary concerns a brake dust particle filter 16 for a disc brake assembly 10 with a brake disc 12 and a caliper 14. In the housing interior 20 of the housing 18 of the brake dust particle filter 16, at least one tongue 28a-28d is arranged or embodied wherein at least a section of this tongue 28a-28d projects radially inwardly. The tongue 28a-28d forms a support 40 for a filter medium 32 of the brake dust particle filter 16. Moreover, the filter medium 32 covers the surface of the tongue 28a-28d at least partially, in particular completely. The housing 18 has the shape of a ring segment. It can be used to accommodate at least partially the brake disc 12 in the housing interior 20. A first housing sidewall 17 and a second housing sidewall 19 as well as a housing peripheral wall 26, 62, 64 each form parts of the housing 18. The housing sidewalls 17, 19 are spaced apart from each other in axial direction. The housing peripheral wall 26, 62, 64 is arranged radially outwardly in the circumferential direction of the housing 18. The housing peripheral wall 26, 62, 64 is arranged or embodied between the first housing sidewall 17 and the second housing sidewall 19. The brake dust particle filter 16 is configured for catching particles that are produced when braking.

[0081] In FIG. 8, finally a further embodiment of the brake dust particle filter 16 is illustrated which comprises in its housing interior 20 the afore described tongues 28a-28d spaced apart from each other in circumferential direction which project from the housing peripheral wall 26 as well as additional tongues 28f which project from a housing sidewall 19. The tongues 28a-28f are embodied such that lateral tongues 28f and circumferential tongues 28a-28d that are located at a common circumferential angle form a continuous tongue, respectively. The resulting continuous tongue has in this context a substantially U-shaped basic form. In order to be able to better recognize the structure of the tongues 28a-28f, the filter medium is not shown in the isometric view. The tongues 28a-28f have each a plurality of through openings through which the air to be filtered which is laden with brake dust can be guided while passing through the filter medium. Due to the combination of the circumferential tongues with the lateral tongues, the separation performance can be further improved. The tongues 28a-28f in the illustrated embodiment are made of a mesh material, preferably a metal mesh, which comprises the through openings already as raw material, which simplifies manufacture.