Drum brake

Abstract

A drum brake (1), in particular for a commercial vehicle, has a brake drum (2) mounted so as to be rotatable about an axis of rotation (D), a plurality of brake pads (3) mounted in a receiving space (22) of the brake drum (2), each having a friction pad carrier (32) and a friction pad (31) arranged thereon, an application device (4) arranged so as to be non-rotatable on an armature housing (5), with which application device the brake pads (3) can be pressed against an inner surface (21) of the brake drum (2) designed as a friction surface, and a cover element (6) covering an open end face of the brake drum (2) and mounted so as to be contactless with the brake drum (2), wherein a brake dust-collecting material (7) is arranged on or near an end edge (23) of the brake drum (2), wherein the collection material (7) is arranged between the brake drum (2) and the cover element (6).

Description

The present invention relates to a drum brake according to the preamble of claim 1.Drum brakes of the aforementioned type have a cylinder-drum-shaped rotor with friction surfaces arranged on an inner side of the rotor, also referred to as a brake drum. A braking force is generated with brake pads which are pressed against the inner friction surface of the brake drum.Friction brakes of this type generate abrasion of brake lining material on the brake lining and on the inner friction surface of the brake drum, which material, if the latter is not suctioned off, escapes into the environment in the form of fine particles.In order to avoid such particulate matter loads caused by the abrasion of such friction materials, it is desirable to develop technical solutions for friction brakes for utility vehicles which are capable of minimizing brake dust, in particular the particulate matter content of brake dust, and ideally of preventing its emission into the environment.Drum brakes have the advantage, in contrast to disc brakes, that the brake shoes are located in the interior of the brake drum and are therefore easy to encapsulate. As a result, the largest amount of the predominantly coarser fraction of the abrasion remains in the drum brake and can be removed from the interior of the brake drum and disposed of in the event of service. This removal is usually carried out with commercially available vacuum cleaners.Since gaps between components moving relative to one another necessarily occur on account of the relative rotational movement also in the case of the drum brake, particles, in particular fine particles, can furthermore escape from the interior of the brake drum through these gaps.A drum brake of the generic type is known, for example, from DE 10 2016 117 778 A1. In this drum brake, an open end side of the brake drum is covered with a cover. In this cover, an opening is provided, into which a suction device provided with a dust removal unit is connected, which has proven itself in practice.It is an object of the present invention to provide a drum brake with which a further improvement in terms of preventing the escape of brake dust can be achieved.This object is achieved by a drum brake having the features of claim 1.The drum brake according to the invention, in particular for a commercial vehicle, has a brake drum mounted rotatably about an axis of rotation and a plurality of brake pads mounted in a receiving space of the brake drum, having a respective friction pad carrier and a friction pad arranged on said friction pad.On an armature housing of the drum brake, a brake application device is arranged in a rotationally fixed manner, with which the brake pads can be pressed against a casing inner surface of the brake drum, which inner surface is designed as a friction surface.The drum brake furthermore has a cover element covering at least a partial surface of an open end face of the brake drum and mounted in the region of the open end face of the brake drum without contact, forming an air gap with respect to the brake drum.A collecting material collecting brake dust is arranged at or near an end edge of the brake drum, wherein the collecting material is arranged between the brake drum and the cover element.With a drum brake configured in this way, an improvement with regard to the prevention of a escape of brake dust is now achieved by the arrangement of the collecting material at or near an end edge of the brake drum, since the brake dust sets in the collecting material and thus an escape of the brake dust into the environment is at least largely prevented.The particle size of the fine dust formed during braking, which should not be released from environmental and health aspects, is in the range from 2.5 nm to 10 nm. In the case of solid particles of this size, dipole interactions (vander-Waals forces) can occur at very small distances (<100 nm) from adjacent surfaces. These adhesive forces are many times greater than the weight of the particles. The present invention takes advantage of this effect to collect brake dust within a drum brake.Advantageous embodiment variants of the invention are the subject matter of the dependent claims.According to an advantageous embodiment variant, a recess is formed on or near an end edge of the brake drum, in which recess the brake dust-collecting material is arranged.The recess with the collecting material arranged therein is covered by the cover element.Such a cover plate is, on the one hand, suitably stable, simple and cost-effective to produce in accordance with the harsh environment and can be fastened in a simple manner to the brake drum or to the armature housing.According to an advantageous embodiment variant, the cover element is designed as an annular cover plate.According to a further preferred embodiment variant, the cover element has a cover region which extends radially with respect to the axis of rotation from the end edge of the brake drum in the direction of the axis of rotation, and a collecting region which partially surrounds the collecting material.This collecting region simultaneously serves for directing the particle flow of brake dust which collects in the collecting material accommodated there after entering the collecting region of the cover element.Furthermore, the kinetic energy of the particles is also braked in the collecting region.According to a further preferred embodiment variant, the cover element has a radially inwardly bent region which adjoins the collecting region and is shaped parallel to an outer contour of the brake drum.According to a preferred embodiment variant, the recess receiving the collecting material is formed as a groove introduced in the front edge of the brake drum.Such a groove can be easily formed in the front side of the brake drum.According to a further embodiment variant, the recess is designed as a material recess which is introduced in a transition region between the front edge of the brake drum and an outer surface of the outer shell thereof. The collecting material is accommodated in the material recess, wherein the collecting material is accommodated in a space delimited by the collecting region of the cover element and an abutment surface of the brake drum.The introduction of such a material cutout can also be introduced in a simple manner into the brake drum.According to a further preferred embodiment variant, the radially inwardly bent region of the cover element extends into a groove-shaped cutout of the material cutout of the brake drum. The catch region and the holding region are preferably designed as tongues extending radially with respect to the axis of rotation of the brake drum.Preferably, an annular bead extends radially outwards from the contact surface of the brake drum. This bead serves primarily for guiding the flow of the air stream enriched with the brake dust.The cover element is preferably fastened to the anchor housing.According to a further preferred embodiment variant, at least one suction connection is arranged on the cover element.It is also conceivable in principle to fasten the cover element to the brake drum.According to a further preferred embodiment variant, the collecting material is fixed, in particular glued, to the cover element.According to a further embodiment variant, the collecting material covers a surface facing the front edge of the brake drum at least partially, in particular completely.The object is also achieved by a drum brake in which, as an alternative or in addition to the arrangement of the collecting material in the recess covered by the cover element, brake dust-collecting collecting material is arranged at or near the end edge of the brake drum, as viewed in the circumferential direction, between adjacent brake linings.According to an advantageous embodiment variant, the collecting material is held in holders fastened to the armature housing. In an advantageous further development, these holders are configured as wire mesh.In a preferred embodiment variant, the collecting material consists of one or more of the following materials: metal wool, wire braid, porous metal foam, in particular foamed aluminum, woven hose filled with granules.In the embodiment variant as metal wool, the latter preferably has a wire thickness of between 30 μm and 120 μm, with a specific weight of between 800 g / m 2 and 1300 g / m 2.By means of an advantageous embodiment of the geometric design of the interface between brake drum and cover element, the air flow is converted into a turbulent flow. Thus, the particles line up in contact with the collecting material. When bridging the critical distance from the metal wool or from particles already attached to the metal wool, the enormous adhesive forces in relation to the weight of the particles act and the particles are deposited on the surface of the metal wool or form agglomerates with the particles already attached. Metal wool is a particularly advantageous material because its metal, in particular steel, threads themselves have a very small diameter as described above. The material can therefore provide a very large surface area with a small volume by means of multilayer construction.Preferred exemplary embodiments are explained in more detail below with reference to the attached drawings. The following are shown: FIG. 1 shows a schematic isometric illustration of an embodiment variant of a drum brake according to the invention, FIG. 2 is a sectional view through a preferred embodiment of the drum brake, FIG. 3 is an isometric detail enlargement of a wall of a brake drum of the drum brake according to FIG. 1 with a cover element and collecting material arranged thereon, FIGS. 4 to 6 show further alternative embodiment variants of such a cover element and embodiments of the wall of the brake drum, FIG. 7 shows a schematic isometric illustration of a further embodiment variant of a drum brake according to the invention with the brake drum left out, FIG. 8 is a side view of the drum brake shown in FIG. 7 to show the arrangement of brake pads and collecting material arranged therebetween, FIG. 9 shows a sectional illustration through a region of the wall of the brake drum with the cover element and collecting material arranged thereon, FIG. 10 shows a sectional illustration through the drum brake through a sectional plane denoted by X in FIG. 9, FIG. 11 is a side view of the drum brake for displaying a sectional plane for FIG. 12, FIG. 12 is a sectional view through the sectional plane indicated in FIG. 11 for illustrating the collecting material arranged between brake pads, FIG. 13 is a view corresponding to FIG. 10 of a further embodiment of a drum brake according to the invention, FIGS. 14 and 15 are views corresponding to FIGS. 9 and 10 of the drum brake according to FIG. 13, FIG. 16 is a further sectional view of the drum brake according to FIG. 12. FIG. 13, FIG. 17 shows a schematic isometric illustration of the cover element with holders received therein and holders for collecting material arranged between the brake pads, FIG. 18 is an isometric individual view of a holder designed as a wire mesh for fixing the collecting material between the brake pads; and FIG. 19 is an isometric view of an annular wire mesh for use on the inside of the cover member.In the following description of the figures, terms such as top, bottom, left, right, front, rear, etc. refer exclusively to the exemplary illustration and position of the drum brake, brake drum, collecting material, covering element and the like selected in the respective figures. These terms are not to be understood as limiting, i.e. these references can change due to different working positions or the mirror-symmetrical design or the like.In FIG. 1, reference numeral 1 designates overall an embodiment variant of a drum brake according to the invention, which is preferably driven pneumatically or electromechanically, in particular for use in a commercial vehicle. The drum brake 1 has a brake drum 2 which is mounted rotatably about an axis of rotation D and is connected in a rotationally fixed manner via an armature housing 5 to a hub, preferably a commercial vehicle, which is not illustrated here.In a space radially inside the outer wall of the brake drum 2, a plurality of brake pads 3 are arranged, which are mounted in a receiving space of the brake drum 2 and have a respective friction pad carrier 32 and a friction pad 31 arranged on the latter. The brake linings 3 are arranged with their friction linings 31 facing a casing inner surface 21 of the brake drum 2, as is illustrated by way of example in FIG. 2.As is further shown in FIG. 2, a brake application device 4 with a wedge ring 41 which can be displaced on a cylinder sleeve 51 of the armature housing 5 parallel to the axis of rotation D of the brake drum 2 and by means of which the brake pads 3 can be pressed onto the inner jacket surface 21 of the brake drum 2 designed as a friction surface radially with respect to the axis of rotation D of the brake drum 2 (direction r shown in FIG. 1 ) is arranged on the armature housing 5.For transmitting the movement of the wedge ring 41 to the brake pads 3, a respective pressing wedge 34 is arranged as part of a respective brake pad 3 on a side of the friction pad carriers 32 facing away from the friction pad 31. The pressure wedge 34 is connected to the friction lining carrier 32 via a pressure ram 35.The pressure wedge 34 lies on a pressure surface of the wedge ring 41, as can be seen in FIG. 2.The wedge ring 41 is displaceable, for example, via a service brake piston 92 parallel to the axis of rotation D of the brake drum 2 from a non-braking position into a braking position in a direction z, shown in FIG. 1.Between the wedge ring 41 and the pressing wedge 34 of the brake lining 3, a slide 42 with a plurality of rolling bodies 43 is arranged in order to reduce the friction between the pressing surface of the wedge ring 41 and the pressing wedge 34 of the brake lining 3.In the preferred embodiment variant shown in FIG. 2, the application device 4 has a brake cylinder arrangement 9 which is arranged in a rotationally fixed manner in the receiving space 29 of the brake drum 2 on the armature housing 5 in order to carry out the radial pressing movement of the brake shoes 3 on the casing inner surface 21 of the brake drum 2.The brake cylinder arrangement 9 has a housing 91 fixed to the armature housing 5 in a fixed position in the receiving space 29 of the brake drum 2.Relative to this housing 91, the service brake piston 92 is arranged displaceably parallel to the axis of rotation D of the brake drum 2.The brake cylinder arrangement 9 further has a parking brake piston 93 which is displaceable relative to the housing 91 parallel to the axis of rotation D of the brake drum 2 and can be acted upon by the spring force of a spring element 96 via an intermediate plate 95.The spring element 96 is preferably designed as a disk spring, as is also shown by way of example in FIG. 2.The brake cylinder arrangement 9 furthermore has a plurality of plungers 94 which serve for transmitting a movement of the parking brake piston 93 to the service brake piston 92.Furthermore, compressed air feeds are provided, which open on the one hand into a service brake pressure space between the housing 91 and the service brake piston 92 and on the other hand into a parking brake pressure space 97 between the housing 91 and the parking brake piston 93.The movement of the service brake piston 92 is always important for the actuation of the brake shoes 3, which movement is effected by supplying compressed air into the service brake pressure chamber in the event of an intended throttling of the speed of the commercial vehicle, a so-called service brake process.In the event of an intended brake determination, which serves to prevent unintentional rolling away of the commercial vehicle in a parking situation, compressed air present in the parking brake pressure chamber 97 during driving operation is discharged from the parking brake pressure chamber 97, which results in a displacement of the parking brake piston 93 in the direction of the service brake piston 92. The displacement is caused by the force exerted by the spring element 96 on a rear side of the parking brake piston 93 facing away from the service brake piston 92.While in the embodiment variant shown in FIG. 2 the application device 4 is designed such that the brake pads can be moved radially to the axis of rotation D in the direction of the inner jacket surface 21 of the brake drum 2, it is also conceivable to arrange the brake pads on one or more subassemblies which can be pivoted against the inner jacket surface 21 of the brake drum 2 via a so-called S-cam, as is the case with so-called simplex drum brakes. In such simplex drum brakes, the application device is formed by the S-cam and the subassembly movable by it.As is shown in FIG. 2 and in FIGS. 3 to 6, at least one partial surface of an open end side of the brake drum 2 is covered with a covering element 6 mounted in the region of the open end side of the brake drum 2 without contact, forming an air gap 11.A collecting material collecting brake dust is arranged at or near an end edge of the brake drum, wherein the collecting material is arranged between the brake drum and the cover element.In the embodiment variant shown in FIG. 2, the cover element 6 also covers a recess formed on or near an end edge 23 of the brake drum 2, in which recess the brake dust-collecting material 7 is arranged.The cover element 6 is preferably designed as an annular cover plate.The air gap 11 is likewise preferably of annular design and, as is illustrated by way of example in FIGS. 3 to 6, extends between the end-face edge of the brake drum 2 and the inner surface of the cover element 6 facing the latter.In the embodiment variant shown in FIG. 3, the covering plate has a covering region 61 which extends over a part of the end-face edge 23 of the brake drum 2 and a region radially within the casing inner surface 21 of the brake drum 2 and extends radially with respect to the axis of rotation D from the end-face edge 23 of the brake drum 2 in the direction of the axis of rotation D, and a collecting region 62 which partially surrounds the collecting material 7.This collecting region 62 extends into a recess formed as a groove 24 in the end edge 23 of the brake drum 2, in which recess the collecting material 7 is accommodated.As is further illustrated in FIGS. 1 and 2, the cover element 6 is preferably fastened to the anchor housing 5 with screws.It is also conceivable to fix the cover element 6 to the brake drum 2, in particular in the region of an outer surface of the outer shell of the brake drum 2.By covering the gap between the armature housing 5 and the casing inner surface 21 of the brake drum 2, in which the brake shoes are arranged movably, by the cover element 6, brake dust which arises during a braking process cannot escape from the interior of the brake drum 2 into the wheel house of a vehicle wheel, but is largely suctioned directly from the interior of the brake drum 2 via a suction device.For this purpose, in the embodiment variant shown here, a suction connection 8 with a suction pipe 81 and a holding lip 82 is provided on the cover element 6, onto which a connection hose of the suction device (not shown) can be plugged.A further part of the brake dust reaches the collecting region 62 of the cover element 6 through a remaining gap between the cover region 61 of the cover element 6 and the end edge 23 of the brake drum 2, with an air flow guided through the underside of the cover element 6 facing the end edge 23 of the brake drum 2.The brake dust that has reached this region can thus be collected in the collecting material 7 by the collecting material 7 arranged in the collecting region 62, and the collecting material 7 filled with brake dust can be exchanged in the case of service.The collecting material 7 can be shaped as a filter mat and preferably consists of metal wool, a wire mesh or a porous metal foam, in particular a foamed aluminum.It is also conceivable to form the collecting material in the form of a fabric tube filled with a granulate.The collecting material 7 is preferably held, preferably clamped, on the cover element 6 by the shape of the collecting region 62. The collecting regions 62 are preferably configured in a small shape as a bent continuation of the covering region 61.It is also conceivable to additionally glue the collecting material 7 to the covering element 6.In the variant embodiments shown in FIGS. 4 to 6, the recess on the brake drum 2 is formed as a material recess 25 which is introduced in a transition region between the end-face edge 23 and a casing outer surface 22 of the brake drum 2 and in which the collecting material 7 is accommodated.The collecting material 7 is accommodated here in a space delimited by the collecting region 62 of the cover element 6 and an abutment surface 26 of the brake drum 2.The collecting region 62 is preferably formed in a pocket-shaped manner in cross section, so that the collecting material 7 is accommodated in this pocket, preferably fixed to the inner surface of the pocket. The air gap 11 preferably extends here between the collecting material 7 and the contact surface 26 of the brake drum 2.Furthermore, in the embodiment variants shown in FIGS. 4 to 6, the cover element 6 has a radially inwardly bent region 63 which adjoins the collecting region 62 and extends in the direction of a groove-shaped cutout 27 in the region of the material cutout 25 of the brake drum 2 and thus permits further swirling of an air flow flowing through the collecting region 62 from the air gap 11.As is further illustrated in FIGS. 5 and 6, an annular bead 28 extends radially outwards from the contact surface 26 of the brake drum 2 in order to positively influence the air flow enriched with the brake dust.In the embodiment variant shown in FIG. 5, this bead 28 is formed on the surface of the groove-shaped recess 27.In the embodiment variant shown in FIG. 6, this bead 28 extends radially outwards directly as an extension of the end edge 23 of the brake drum 2.In all the embodiments shown, the shape of the collecting material 7 is designed such that it takes up as completely as possible the space between the inner side of the collecting region 62 and the respective contact surface 26 in the region of the groove 24 or the material recess 25 of the brake drum 2.Overall, the cover element 6 with the collecting material 7 arranged thereon can be installed on the brake drum 2 in a simple manner and can be attached to the brake drum 2 quickly and easily.The use of such a cover element 6 with the collecting material 7 arranged thereon contributes in particular to reducing the environmental impact due to brake dust and to prolonging the service life of the drum brake.In principle, an arrangement of the cover element on a brake drum without a recess in the region of the end-face edge 23 of the brake drum 2 is also conceivable, in which the collecting material 7 is accommodated, for example, between the brake drum 2 and a crimped-over region of the cover element 6 or a region cranked toward the brake drum 2.FIGS. 7 to 19 show further embodiment variants of drum brakes according to the invention.As shown in FIGS. 7, 8, 12, 13, 16 and 17, brake dust collecting material 7 is also arranged between adjacent brake pads 3 as viewed in the circumferential direction of the brake drum in this embodiment variant.The arrangement of the collecting material 7 between adjacent brake pads 3 represents a further significant improvement with regard to the collecting of the brake fine dust which is produced during braking processes, since the brake dust particles are thrown away tangentially to the direction of rotation of the brake drum 2 when the friction material is pressed against the friction surface of the brake drum 2.The brake dust particles are not discharged directly to the environment, but are initially thrown into the space between the armature housing 5, brake drum 2 and cover element 6.Depending on the available space between adjacent brake pads, correspondingly large areas are provided for the collecting material 7.The collecting material 7 arranged between adjacent brake pads 3 is preferably held on holders 14, which are in turn fastened to the armature housing 5.As can be further seen in FIGS. 8 and 12, the holders 14 here consist of webs through which bolts extend parallel to the axis of rotation of the brake drum 2 and which are passed through the collecting material 7.The radial thickness of the collecting material 7 arranged in the regions between the brake pads 3 is dimensioned such that it uses the space between the brake pads 3, the armature housing 5 and the brake drum 2 to the maximum extent.As is further illustrated in FIGS. 9 and 10, in the embodiment variant shown here, the collecting material 7 arranged under the cover element 6 is also inserted not only in the region of the groove-shaped cutout of the material cutout 25 of the brake drum 2, but in the entire U-shaped cross section of the cover element 6, wherein the axial thickness of the collecting material 7 varies depending on the space available.Thus, a greater axial thickness is reinforced, in particular in the regions not occupied by the brake pads 3, as shown in FIG. 10.The collecting material 7 is arranged on the surface facing the end edge 23 of the brake drum 2 at least partially, in the exemplary embodiment shown, completely covering the surface facing the end edge 23 of the brake drum 2.In the embodiment variant shown in FIGS. 13 to 19, which corresponds substantially to the embodiment variant shown in FIGS. 7 to 12, the collecting material 7 is fixed by holders 12, 13, 14 which are at least partially formed as wire mesh, as shown in FIGS. 17 to 19.If the collecting material 7 consists of metal wool, it preferably has a wire thickness between 30 μm and 120 μm, with a specific weight between 800 g / m 2 and 1300 g / m 2.The material steel wool as the collecting material 7 is particularly advantageous because the steel threads of this steel wool provide a very large surface area with a small volume due to their very small diameter.Steel wool is moreover very heat-resistant and quasi material-neutral with regard to its abrasion, since the brake drum 2 itself also consists of a material containing iron.List of reference characters1 Drum brake 2 Brake drum 21 Inner jacket surface 22 Outer jacket surface 23 Edge 24 Groove 25 Material cutout 26 Contact surface 27 Cutout 28 Bead 29 Receiving space 3 Brake shoe 31 Friction lining 32 Friction lining carrier 33 Friction surface 34 Pressing wedge 35 Pressure plunger 4 Application device 41 Wedge ring 42 Slide 43 Rolling element 5 Armature housing 51 Cylinder sleeve 6 Cover element 61 Cover region 62 Collecting region 63 region 7 Collecting material 8 Suction connection 81 Suction pipe 82 Holding lip 9 Brake cylinder arrangement 91 Housing 92 Service brake piston 93 Parking brake piston 94 Plunger 95 Intermediate plate 96 Spring element 97 Parking brake pressure space 10 Brake dust collecting device 11 Air gap 12 Holder 13 Holder 14 Holder D Axis of rotation R, z DirectionReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2016 117 778 A1

[0007]

Claims

Drum brake (1), in particular for a commercial vehicle, having - a brake drum (2) mounted rotatably about an axis of rotation (D), - a plurality of brake pads (3) mounted in a receiving space (22) of the brake drum (2), having a respective friction pad carrier (32) and a friction pad (31) arranged thereon, - a brake application device (4) arranged in a rotationally fixed manner on an armature housing (5), with which the brake pads (3) can be pressed against a casing inner surface (21) of the brake drum (2) designed as a friction surface, - a cover element (6) covering at least a partial surface of an open end face of the brake drum (2) and mounted in the region of the open end face of the brake drum (2) without contact, forming an air gap (11) with respect to the brake drum (2), characterized in that, - a collecting material (7) collecting brake dust is arranged on or near an end edge (23) of the brake drum (2), - wherein the collecting material (7) is arranged between the brake drum (2) and the cover element (6).Drum brake (1) according to Claim 1, characterized in that a recess is formed on the brake drum (2) on or close to the end-face edge (23) of the brake drum (2), in which recess the collecting material (7) collecting the brake dust is arranged, wherein the recess with the collecting material (7) arranged therein is covered by the covering element (6).Drum brake (1) according to Claim 1 or 2, characterized in that the covering element (6) is designed as an annular covering plate.Drum brake (1) according to one of the preceding claims, characterized in that the cover element (6) has a cover region (61) which extends radially with respect to the axis of rotation (D) from the end-face edge (23) of the brake drum (2) in the direction of the axis of rotation (D), and a collecting region (62) which partially surrounds the collecting material (7).Drum brake (1) according to Claim 4, characterized in that the covering element (6) has a region (63) which adjoins the collecting region (62) and is bent radially inwards and is shaped parallel to an outer contour of the brake drum (2).Drum brake (1) according to one of Claims 2 to 5, characterized in that the recess is designed as a groove (24), which is introduced in the end-face edge (23) of the brake drum (2) and in which the collecting material (7) is accommodated.Drum brake (1) according to one of Claims 2 to 5, characterized in that the recess is designed as a material cutout (25), which is introduced in a transition region between the end-face edge (23) and a casing outer surface (22) of the brake drum (2) and in which the collecting material (7) is accommodated, the collecting material (7) being accommodated in a space bounded by the collecting region (62) of the covering element (6) and a contact surface (26) of the brake drum (2).Drum brake (1) according to one of Claims 5 to 7, characterized in that the region (63) of the covering element (6) which is bent radially inward projects into a groove-shaped cutout (27) in the material cutout (25) of the brake drum (2).Drum brake (1) according to Claim 7 or 8, characterized in that an annular bead (28) extends radially outwards from the contact surface (26) of the brake drum (2).Drum brake (1) according to one of the preceding claims, characterized in that the cover element (6) is fastened to the armature housing (5).Drum brake (1) according to one of the preceding claims, characterized in that at least one suction connection (8) is arranged on the cover element (6).Drum brake (1) according to one of the preceding claims, characterized in that the cover element (6) is fastened to the brake drum (2).Drum brake (1) according to one of the preceding claims, characterized in that the collecting material (7) is fixed, in particular bonded, to the cover element (6).Drum brake (1) according to one of the preceding claims, characterized in that the collecting material (7) at least partially, in particular completely, covers a surface facing the end-face edge (23) of the brake drum (2).Drum brake (1) according to one of the preceding claims or according to the preamble of claim 1, characterized in that brake dust-collecting material (7) is arranged between adjacent brake linings (3) as viewed in the circumferential direction.Drum brake (1) according to one of the preceding claims, characterized in that the collecting material (7) is held in holders (12, 13, 14) fastened to the armature housing (5).Drum brake (1) according to claim 16, characterised in that the holders (12, 13, 14) are at least partially formed as wire mesh.Drum brake (1) according to one of the preceding claims, characterized in that the collecting material (7) consists of one or more of the following materials: metal wool, wire braid, porous metal foam, in particular foamed aluminium, woven hose filled with granules.Drum brake (1) according to claim 18, characterised in that the metal wool has a wire thickness between 30 μm and 120 μm, at a specific weight between 800 g / m 2 and 1300 g / m 2.

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