Drum brake

Abstract

The invention relates to a radially actuatable drum brake (1) for a utility vehicle, having an armature housing (5), a brake drum (2) which at least partly encloses the armature housing (5) and is rotatably mounted relative to the armature housing (5) about a rotational axis (AR), and at least two brake linings (3) which are mounted in an intermediate space (11) between a casing inner surface (21) of the brake drum (2) and the armature housing (5) in respective bearing receiving areas (52) of the armature housing (5), said bearing receiving areas being open towards the casing inner surface (21) of the brake drum (2), wherein each of the brake linings (3) has a friction lining support (32), a friction lining (31) arranged thereon, and a pressure piece (35) which is arranged on the lining support (32) lower face facing away from the friction lining and which extends radially in the direction of the rotational axis (AR) of the brake drum (2) into the interior (10) of the armature housing (5) through an opening (54) of the respective bearing receiving area (52) of the armature housing (5). The drum brake also has a clamping device (4) which is arranged in the interior (10) of the armature housing (5) and which comprises at least one pressing part, by means of which the brake lining (3) can be pressed against a casing inner surface (21) of the brake drum (2) in a clamping direction (r) radially to the rotational axis (AR) of the brake drum (2). A sealing element (7, 8, 9) which at least contacts the pressure piece (35) is arranged on the armature housing (5) in the region of the opening (54) of the respective bearing receiving area (52) of the armature housing (5) such that brake dust and / or a liquid medium is prevented from passing between the intermediate space (11), which is provided between the casing inner surface (21) of the brake drum (2) and the armature housing (5), and the interior (10) of the armature housing (5).

Description

[0001] DRUM BRAKE

[0002] The invention relates to a drum brake according to the preamble of claim 1.

[0003] A drum brake of this type is known, for example, from DE 10 2021 115 785 B3. Such drum brakes generally have a cylindrical drum-shaped rotor with friction surfaces arranged on the inside of the rotor, also referred to as the brake drum. Braking force is generated by brake pads that are pressed against the inner friction surface of the brake drum.

[0004] In the generic drum brake known from DE 10 2021 115 785 B3, the force transmission of which is designed in such a way that a force introduced axially to the axis of rotation is amplified by its deflection so that the reaction force acts radially on the friction surface of the brake drum, the brake pads are pressed on by means of a wedge that can be moved in the direction of the axis of rotation.

[0005] The reaction force can be divided by activating several pressure pieces.

[0006] The force required for this is generated by a brake cylinder installed in the drum brake by ventilating a service brake piston of the brake cylinder with compressed air and thereby displacing the wedge parallel to the axis of rotation of the drum brake.

[0007] A major advantage of the drum brake known from DE 10 2021 115 785 B3 is that the brake dust is not released into the environment but is stored inside the brake. At the same time, however, it must be ensured that the moving components of the internal mechanism do not come into contact with the deposited brake dust, as this could cause the mechanism to become stiff or, in the worst case, jam. This internal mechanism should also be protected from other environmental influences such as dirt, moisture, etc.

[0008] The object of the present invention is to further develop a drum brake of this type so that the internal mechanism can be reliably protected from external influences. This object is achieved by a drum brake having the features of claim 1.

[0009] The radially actuated drum brake for a commercial vehicle according to the invention has an armature housing and a brake drum which at least partially encloses the armature housing and is mounted so as to be rotatable about a rotation axis relative to the armature housing.

[0010] The drum brake further comprises at least two brake pads mounted in a space between an inner surface of the brake drum and the armature housing in respective bearing receptacles of the armature housing that are open to the inner surface of the brake drum.

[0011] Each of the brake pads has a pad carrier, a friction pad arranged thereon and a pressure piece arranged on an underside of the pad carrier facing away from the friction pad, which pressure piece extends radially through an opening of the respective bearing receptacle of the armature housing in the direction of the axis of rotation of the brake drum into an interior of the armature housing.

[0012] In the interior of the armature housing, an application device is also arranged, with at least one pressing part with which the brake pads can be pressed against an inner surface of the brake drum in an application direction radial to the rotational axis of the brake drum.

[0013] In the area of ​​the opening of the respective bearing receptacle of the armature housing, a sealing element which at least touches the pressure piece is arranged on the armature housing, so that a transfer of brake dust and / or a liquid medium between the space present between the inner surface of the brake drum and the armature housing and the interior of the armature housing is prevented.

[0014] The dust- and / or liquid-tight division of the space within the drum brake into a gap between the inner surface of the brake drum and the armature housing on the one hand, and an interior space within the armature housing on the other, makes it possible to store the brake dust generated during braking within the drum brake, reducing particulate pollution. At the same time, the dust- and / or liquid-tight sealing of the gap from the interior space protects the mechanical components located within, thus ensuring the functionality of the drum brake.

[0015] Advantageous embodiments of the invention are the subject of the subclaims.

[0016] According to an advantageous embodiment, the sealing element is designed as a rolling bellows or bellows, with a first end fastened to the armature housing and a second end fastened to the pressure piece.

[0017] On the one hand, such a bellows or rolling bellows protects the interior from dirt, and on the other hand, such a bellows or rolling bellows allows the sealing element to extend when the brake pad moves relative to the armature housing, thus enabling the respective brake pad to be lifted to carry out a braking operation while maintaining dust tightness.

[0018] At least one of the ends of the sealing element designed as a rolling bellows or bellows is fastened to the respective component by means of a press ring and / or threaded ring.

[0019] According to an advantageous embodiment, the sealing element is made of metal, silicone, a fabric composite material, an elastomer, TPE, or a wire mesh in order to take into account the high temperature load in this area of ​​the drum brake.

[0020] According to an alternative embodiment, the sealing element is designed as a sliding seal.

[0021] Such a sliding seal is cost-effective to manufacture and install.

[0022] According to a preferred development, the sealing element designed as a sliding seal is accommodated in a recess in the region of the opening of the respective bearing holder.

[0023] This allows the sliding seal to remain stationary in the area of ​​the opening of the respective bearing mount during movement of the pressure piece of the brake pad. According to a further advantageous development, the sealing element designed as a sliding seal has a retaining ring, made in particular from a metal sheet, with which a sealing body of the sealing element is fastened to the armature housing, in particular by being pressed or screwed in.

[0024] Such a retaining ring made of sheet metal is also suitable for fastening the sealing element designed as a sliding seal due to its good temperature resistance.

[0025] The sealing body of the sealing element is designed with an oversize so that when installed it is deformed by the pressure piece resting against it and thus the contact of the sealing body with the pressure piece is always guaranteed.

[0026] According to a further advantageous development, the sealing element designed as a sliding seal has a scraper ring which is arranged near the underside of the lining carrier.

[0027] The sealing body designed as a sliding seal preferably consists of a thermally resistant material, in particular PTFE.

[0028] Preferred embodiments are explained in more detail below with reference to the accompanying drawings. They show:

[0029] Fig. 1 is a schematic isometric view of an embodiment of a drum brake according to the invention,

[0030] Fig. 2 is a sectional view of the drum brake shown in Fig. 1 without showing the brake drum,

[0031] Fig. 3 is a sectional view of a section of a first embodiment of a drum brake according to the invention with a sealing element designed as a bellows between the armature housing and the pressure piece,

[0032] Fig. 4 is a sectional view of a section of a second embodiment of a drum brake according to the invention with a sealing element designed as a sliding seal between the armature housing and the pressure piece,

[0033] Fig. 5 is an enlarged section of the section marked V in Figure 4 to show the structure of the sliding seal, and

[0034] Fig. 6 is a sectional view of a section of a third embodiment of a drum brake according to the invention with a sealing element designed as a rolling bellows between the armature housing and the pressure piece.

[0035] In the following description of the figures, terms such as top, bottom, left, right, front, rear, etc., refer exclusively to the exemplary representation and position of the brake pads, drum brake, brake drum, housing, wedge ring, pressure piston, sealing elements, and the like chosen in the respective figures. These terms are not to be understood as limiting; i.e., these references may change due to different operating positions or the mirror-symmetrical design, or the like.

[0036] In Figure 1, the reference number 1 denotes an embodiment variant of a drum brake according to the invention, in particular for use on a commercial vehicle.

[0037] The drum brake 1 has a brake drum 2 which is mounted so as to be rotatable about a rotation axis AR and which is connected in a rotationally fixed manner to a hub of a wheel axle (not shown here) via an armature housing 5.

[0038] As shown in Figures 2, 3, 4 and 6, in an intermediate space 11 between an inner surface 21 of the brake drum 2 and the armature housing 5, a plurality of brake pads 3 with a respective friction pad carrier 32 and a friction pad 31 arranged thereon are arranged in respective bearing receptacles 52 of the armature housing 5, said bearing receptacles being open to the inner surface 21 of the brake drum 2.

[0039] The brake pads 3 are arranged with their friction linings 31 facing the inner surface 21 of the brake drum 2. The intermediate space 11 is delimited, in particular in the radial direction, on the one hand by a radial outer surface of the armature housing 5 facing the inner surface 21 of the brake drum 2 and, on the other hand, by the inner surface 21 of the brake drum 2. In an interior space 10 of the armature housing 5, an application device 4 is arranged with a wedge ring 41 that can be moved on a cylinder sleeve 51 of the armature housing 5 parallel to the axis of rotation AR of the brake drum 2, with which wedge ring the brake pads 3 can be pressed against the inner surface 21 of the brake drum 2, designed as a friction surface, radially to the axis of rotation AR of the brake drum 2 (direction r shown in Figure 1), as can be clearly seen in Figure 3.

[0040] To transmit the movement of the wedge ring 41 to the brake pads 3, a respective pressure wedge 33 is arranged as part of a respective brake pad 3 on a side of the friction pad carrier 32 facing away from the friction pad 31. The pressure wedge 33 is connected to the friction pad carrier 32 via a pressure piece 35. The pressure piece 35 extends radially through an opening 54 of the respective bearing receptacle 52 of the armature housing 5 in the direction of the rotational axis AR of the brake drum 2 into the interior 10 of the armature housing 5.

[0041] The pressure wedge 33 rests on a pressure surface of the wedge ring 41, as can be seen, for example, in Figure 2.

[0042] The wedge ring 41 is preferably displaceable via a service brake piston 62 of a brake cylinder arrangement 6 parallel to the rotation axis AR of the brake drum 2 from a non-braking position into a braking position in a direction z, shown in Figure 2.

[0043] A slide 42 with a plurality of rolling elements 43 is arranged between the wedge ring 41 and the pressure wedge 33 of the brake pad 3 in order to reduce the friction between the pressure surface of the wedge ring 41 and the pressure wedge 33 of the brake pad 3.

[0044] The brake cylinder arrangement 6 shown in Figure 2 as a component of the application device 4 serves to carry out the radial pressing movement of the brake shoes 3 against the inner surface of the brake drum 2.

[0045] The brake cylinder arrangement 6 has a housing 61 fixedly fastened to the armature housing 5 in the receiving space of the brake drum 2.

[0046] The service brake piston 62 is arranged displaceably relative to this housing 61 parallel to the rotational axis AR of the brake drum 2. Furthermore, the brake cylinder arrangement 6 has a parking brake piston 63, which is displaceable relative to the housing 61 parallel to the rotational axis AR of the brake drum 2 and can be subjected to the spring force of a spring element 66, preferably designed as a disc spring, via an intermediate plate 65.

[0047] The brake cylinder arrangement 6 further comprises a plurality of tappets 64 which serve to transmit a movement of the parking brake piston 63 to the service brake piston 62.

[0048] Furthermore, compressed air supplies are provided, which open firstly into a service brake pressure chamber between the housing 61 and the service brake piston 62 and secondly into a parking brake pressure chamber 67 between the housing 61 and the parking brake piston 63.

[0049] Important for the actuation of the brake shoes 3 is always the movement of the service brake piston 62, which in the event of an intentional throttling of the speed of the commercial vehicle, a so-called service braking operation, is brought about by the supply of compressed air into the service brake pressure chamber.

[0050] In the event of an intentional application of the brake, which serves to prevent the commercial vehicle from unintentionally rolling away in a parking situation, compressed air present in the parking brake pressure chamber 67 during parking operation is released from the parking brake pressure chamber 67, which results in a displacement of the parking brake piston 63 in the direction of the service brake piston 62.

[0051] The displacement is caused by the force exerted by the spring element 66 on a rear side of the parking brake piston 63 facing away from the service brake piston 62.

[0052] As an alternative to the application device 4 with wedge ring 41 and brake cylinder arrangement 6 arranged in the receiving space 22 of the brake drum 2 on the armature housing 5 for actuating the wedge ring 41, it is in principle also conceivable to provide an application device with at least one pressing part with which the brake pads 3 can be pressed against an inner surface 21 of the brake drum 2 in an application direction r radial to the rotation axis AR of the brake drum 2, in particular by pneumatic, hydraulic or electrical actuation. As further shown in Figures 3-6, a sealing element 7, 8, 9 at least touching the pressure piece 35 is arranged on the armature housing 5 in the region of the opening 54 of the respective bearing receptacle 52 of the armature housing 5.

[0053] This prevents the passage of brake dust and / or liquid media such as water between the gap 11 present between the inner surface 21 of the brake drum 2 and the armature housing 5 and an interior space 10 of the armature housing 5. The sealing element 7, 8, 9 preferably also prevents the passage of other externally acting dust, dirt, and other solids.

[0054] Thus, in the embodiment shown in Figure 3, the sealing element 9 is designed as a bellows, with a flexible bellows 91 with a first end fastened to the armature housing 5 and a second end fastened to the pressure piece 35, which second end encompasses the pressure piece circumferentially.

[0055] The two ends of the sealing element 9 are preferably fastened here by means of a press ring 92, 93 and / or a threaded ring on the one hand to the armature housing 5 and on the other hand to the pressure piece 35.

[0056] Preferably, the lower press ring 92 in Figure 3 is pressed into the armature housing 5. The upper press ring 93 is preferably cup-shaped and pressed into an upper end of the pressure piece 35 near the lining carrier 32. The flexible bellows 91 is preferably welded to the press rings 92, 93 in the region of both ends.

[0057] The bellows itself is preferably made of metal. It is also conceivable to manufacture the bellows from a fabric composite material, an elastomer, TPE (thermoplastic elastomer), or even a wire mesh.

[0058] An important factor in selecting the material for the bellows is its resistance to high temperature loads, which is important in this area close to the brake pads.

[0059] With the aid of such a bellows, it is possible for the sealing element, with its end attached to the pressure piece, to be able to move along the stroke of the pressure piece when the brake pad moves to the inner surface 21 of the brake drum 2, thus creating a reliable dust seal from the dust-laden intermediate space 11 to the interior 10 of the armature housing 5.

[0060] As an alternative to the design of the sealing element as a bellows, a design as a rolling bellows is also conceivable, as shown in Figure 6.

[0061] Such a rolling bellows is preferably made of a thermally resistant material such as silicone.

[0062] In the sealing element 8 designed as a rolling bellows, at least one of the ends of a flexible bellows 81 of the sealing element 8 is also fastened to the respective component by means of a press ring 82, 83.

[0063] In the advantageous embodiment shown in Figures 4 and 5, the sealing element 7 is designed as a sliding seal.

[0064] The sealing element 7 designed as a sliding seal is preferably received in a recess 53 in the region of the opening 54 of the respective bearing receptacle 52 of the armature housing 5.

[0065] The sealing element 7, designed as a sliding seal, has, as shown in Figure 5, a retaining ring 72, with which a sealing body 71 of the sealing element 7 is fastened to the armature housing 5, in particular pressed or screwed in. The retaining ring 72 is preferably made of a metal sheet.

[0066] This sealing body 71 is designed with an oversize in its cross section shown in Figure 5, ie the sealing body 71 projects from the recess 53 into the area of ​​the opening 54 before the brake pad 3 is inserted into the bearing receptacle 52 of the armature housing 5 provided for it and is deformed after installation of the brake pad 3 by the pressure piece 35 resting against it.

[0067] In an advantageous development, the sealing element 7, designed as a sliding seal, also has a scraper ring arranged near the underside of the lining carrier 32. The sealing body 71 is also made of a thermally resistant material that can withstand temperatures of at least 250°C. It is particularly preferably made of PTFE (polytetrafluoroethylene). Instead of a sliding seal, a plug seal is also conceivable.

[0068] List of reference symbols

[0069] 1 drum brake

[0070] 2 brake drums

[0071] 3 brake pad

[0072] 31 Friction lining

[0073] 32 lining carriers

[0074] 33 Pressure wedge

[0075] 34 threaded pipe

[0076] 35 pressure piece

[0077] 4 clamping device

[0078] 41 wedge ring

[0079] 42 sleds

[0080] 43 rolling elements

[0081] 5 armature housing

[0082] 51 Cylinder sleeve

[0083] 52 Stock recording

[0084] 53 recess

[0085] 54 Opening

[0086] 6 Brake cylinder arrangement

[0087] 61 brake cylinder housing

[0088] 62 service brake pistons

[0089] 63 parking brake pistons

[0090] 64 tappets

[0091] 65 intermediate plate

[0092] 66 spring element

[0093] 67 Parking brake pressure chamber

[0094] 68 Seal

[0095] 69 Seal

[0096] 7 Sealing element

[0097] 71 Sealing body 72 Retaining ring

[0098] 8 Sealing element 81 Flexible bellows 82 Press ring

[0099] 83 Press ring

[0100] 9 Sealing element 91 Flexible bellows 92 Press ring

[0101] 93 Press ring

[0102] 10 Interior

[0103] 11 space

[0104] AR rotation axis

[0105] U Circumferential direction of the brake drum r direction z direction

Claims

Claims 1. Radially actuated drum brake (1) for a commercial vehicle, comprising - an armature housing (5), - a brake drum (2) at least partially enclosing the armature housing (5) and mounted so as to be rotatable about an axis of rotation (AR) relative to the armature housing (5), - at least two brake pads (3) mounted in a space (11) between an inner surface (21) of the brake drum (2) and the armature housing (5) in respective bearing receptacles (52) of the armature housing (5) open to the inner surface (21) of the brake drum (2), - wherein each of the brake pads (3) has a pad carrier (32), a friction pad (31) arranged thereon and a pressure piece (35) arranged on an underside of the pad carrier (32) facing away from the friction pad, which pressure piece extends through an opening (54) of the respective bearing receptacle (52) of the armature housing (5) radially in the direction of the rotational axis (AR) of the brake drum (2) into an interior space (10) of the armature housing (5), - an application device (4) arranged in the interior (10) of the armature housing (5) with at least one pressing part, with which the brake pads (3) can be pressed against the inner surface (21) of the brake drum (2) in an application direction (r) radial to the axis of rotation (AR) of the brake drum (2), characterized in that - in the region of the opening (54) of the respective bearing receptacle (52) of the armature housing (5), a sealing element (7, 8, 9) which at least touches the pressure piece (35) is arranged on the armature housing (5), so that a transfer of brake dust and / or a liquid medium between the intermediate space (11) present between the inner surface (21) of the casing of the brake drum (2) and the armature housing (5) and the interior space (10) of the armature housing (5) is prevented.

2. Drum brake (1) according to claim 1, characterized in that the sealing element (8, 9) is designed as a rolling bellows or bellows, with a first end fastened to the armature housing (5) and a second end fastened to the pressure piece (35).

3. Drum brake (1) according to claim 2, characterized in that at least one of the ends of the sealing element (8, 9) is Press ring (82, 92, 83, 93) and / or threaded ring is attached to the respective component.

4. Drum brake (1) according to one of the preceding claims, characterized in that the sealing element (8, 9) is made at least partially, preferably completely, from metal, silicone, a fabric composite material, elastomer, TPE, or a wire mesh.

5. Drum brake (1) according to claim 1, characterized in that the sealing element (7) is designed as a sliding seal.

6. Drum brake (1) according to claim 5, characterized in that the sealing element (7) designed as a sliding seal is received in a recess (53) in the region of the opening (54) of the respective bearing receptacle (52).

7. Drum brake (1) according to claim 5 or 6, characterized in that the sealing element (7) designed as a sliding seal has a retaining ring (72) with which a sealing body (71) of the sealing element (7) is fastened to the armature housing (5), in particular pressed or screwed in.

8. Drum brake (1) according to claim 7, characterized in that the sealing body (71) is deformed in the installed state by the pressure piece (35) resting against it.

9. Drum brake (1) according to one of claims 5 to 8, characterized in that the sealing element (7) designed as a sliding seal has a scraper ring which is arranged near the underside of the lining carrier (32).

10. Drum brake (1) according to one of claims 7 to 9, characterized in that the sealing body (71) is made of a thermally resistant material, in particular of PTFE.

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