VEHICLE DRUM BRAKE

Abstract

A vehicle drum brake includes a drum (3) having an inner friction surface (21) formed circumferentially, a brake carrier (5) that can move in rotation relative to the drum (3) about a drum axis (X), and a brake lining assembly (7) arranged on the brake carrier (5). The brake lining assembly (7) has a plurality of radially movable lining carriers (11), on each of which a brake lining segment (9) is provided, facing the friction surface (21). The drum brake (1) has an actuating ring (13) displaceable along the drum axis (X) and rotatable about the drum axis (X), and a displacement surface arrangement (30), which is operatively connected to the lining carriers (11). The displacement surface arrangement (30) is shaped such that both the axial displacement and the rotary movement of the actuating ring (13) bring about a respective synchronous radial movement of all the lining carriers (11).

Claims

1. A vehicle drum brake (1), comprising: a drum (3) having an inner friction surface (21) formed circumferentially, a brake carrier (5), which is arranged within the drum (3) in such a way that it can move in rotation relative to the drum (3) about a drum axis (X), a brake lining assembly (7), which is arranged on the brake carrier (5), wherein the brake lining assembly (7) has a plurality of radially movable lining carriers (11), on each of which a brake lining segment (9) is provided, facing the friction surface (21), an actuating ring (13), wherein the actuating ring (13) is displaceable along the drum axis (X) and rotatable about the drum axis (X), wherein the actuating ring includes a displacement surface arrangement (30), which is operatively connected to the lining carriers (11), wherein the displacement surface arrangement (30) is sized and arranged such that both axial displacement and rotary movement of the actuating ring (13) causes a respective synchronous radial movement of each of the lining carriers (11).

2. The vehicle drum brake (1) as claimed in claim 1, wherein the actuating ring (13) is coupled to a first actuator (23) that causes the axial displacement of the actuating ring (13), wherein the actuating ring (13) is coupled to a second actuator (25) that causes out the rotary movement of the actuating ring (13), and wherein the first and second actuators (23, 25) are kinematically decoupled from one another.

3. The vehicle drum brake (1) as claimed in claim 1, wherein the actuating ring (13) is axially displaceable between a first, retracted, axial position (A1) and a second, extended, axial position (A2), wherein the axial displacement from the first axial position (A1) to the second axial position (A2) is converted in a radial direction into a first stroke length (H1) of the brake lining assembly (7), and wherein the actuating ring (13) is rotatable between a first rotational position (D1) and a second rotational position (D2), wherein the rotary movement from the first rotational position (D1) to the second rotational position (D2) is converted in a radial direction into a second stroke length (H2) of the brake lining assembly (7).

4. The vehicle drum brake (1) as claimed in claim 3, wherein the first stroke length (H1) and the second stroke length (H2) differ, wherein the larger of the two stroke lengths (H1, H2) defines a range of movement for an application and release movement of a main braking function of the drum brake (1), and the smaller of the two stroke lengths (H1, H2) defines a range of movement for a release clearance adjustment of the drum brake (1).

5. The vehicle drum brake (1) as claimed in claim 4, wherein the first stroke length (H1) is larger than the second stroke length (H2).

6. The vehicle drum brake (1) as claimed in claim 1, wherein the displacement surface arrangement (30) has a displacement surface (31) which faces the brake lining assembly (7) and which interacts with the brake lining assembly (7) in such a way that a movement of the displacement surface (31) is converted into the radial movement of the lining carriers (11).

7. The vehicle drum brake (1) as claimed in claim 6, wherein the displacement surface (31) has a rising profile (V1), relative to the drum axis (X), from the first axial position (A1), along the drum axis (X), in the direction of the second axial position (A2), which profile defines the first stroke length (H1).

8. The vehicle drum brake (1) as claimed in claim 7, wherein the displacement surface (31) is divided into a plurality of surface segments (32), wherein each of the lining carriers is assigned a dedicated surface segment (32).

9. The vehicle drum brake (1) as claimed in claim 8, wherein, the surface segments (32) of the displacement surface (31) have a rising profile (V2), relative to the drum axis (X), in the circumferential direction from the first rotational position (D1) in the direction of the second rotational position (D2), which profile defines the second stroke length (H2).

10. The vehicle drum brake (1) as claimed in 9, wherein the profile (V1) in the axial direction between the first axial position (A1) and the second axial position (A2) is linear.

11. The vehicle drum brake (1) as claimed in 10, wherein the profile (V2) in the circumferential direction between the first and second rotational positions (D1, D2) is proportional to the angle of rotation (a).

12. The vehicle drum brake (1) as claimed in claim 1, wherein the first actuator (23) is a pneumatic actuator.

13. The vehicle drum brake (1) as claimed in claim 12, wherein the second actuator (25) is an electric motor actuator.

14. The vehicle drum brake (1) as claimed in claim 13, wherein the second actuator (25) is coupled to the actuating ring (13) by way of a mechanism (27).

15. The vehicle drum brake (1) as claimed in claim 14, wherein the actuating ring includes a plurality of gear teeth, and the mechanism (27) is a gear mechanism, wherein the gear mechanism (27) is coupled to the plurality of gear teeth.

16. The vehicle drum brake (1) as claimed in claim 6, wherein the displacement surface (31) is divided into a plurality of surface segments (32), wherein each of the lining carriers is assigned a dedicated surface segment (32).

17. The vehicle drum brake (1) as claimed in claim 16, wherein the surface segments (32) have a convex profile.

18. The vehicle drum brake (1) as claimed in claim 17, wherein each of the surface segments (32) has a rising profile (V1), relative to the drum axis (X), from the first axial position (A1), along the drum axis (X), in the direction of the second axial position (A2), which profile defines the first stroke length (H1).

19. The vehicle drum brake (1) as claimed in claim 18, wherein, each of the surface segments (32) have a rising profile (V2), relative to the drum axis (X), in the circumferential direction from the first rotational position (D1) in the direction of the second rotational position (D2), which profile defines the second stroke length (H2).

20. The vehicle drum brake as claimed in claim 1, wherein the displacement surface (31) is segmented such that, for a given rotary position of the actuating ring (13) about the axis (X), an axial displacement of the actuating ring (13) in the direction of the axis (X) causes the same radial displacement of each of the lining carriers (11), wherein the rotary position of the actuating ring (13) is adjustable to account for wear to the brake linings over time, wherein axial movement of the ring (13) translates the lining carriers toward the friction surface during a braking operation; wherein a first actuator effects the axial movement; wherein a second actuation, independent of the first actuator, effects the rotary movement, such that the rotary movement and the axial movement may separately and independently effected.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present disclosure is described in greater detail below by way of an exemplary embodiment with reference to the attached drawings. In the drawings:

[0028] FIG. 1 shows a schematic, three-dimensional, partially sectioned view of a drum brake according to a preferred exemplary embodiment,

[0029] FIG. 2 shows a detail view in cross section of the drum brake from FIG. 1 in a first operating state,

[0030] FIG. 3 shows a view according to FIG. 2 in another operating state, and

[0031] FIG. 4 shows a detail view of an actuating ring of the drum brake according to FIGS. 1-3.

DETAILED DESCRIPTION

[0032] FIG. 1 shows a drum brake 1 according to a preferred exemplary embodiment of the present disclosure. The drum brake 1 is a commercial vehicle drum brake of closed construction, referred to as a zero-emission drum brake. The drum brake 1 has a drum 3, with a flange 4 for attachment to the wheel. The drum brake 1 furthermore has a brake carrier 5, which, together with the drum 3, forms a housing. The brake carrier 5 likewise has a flange 6, by way of which the brake carrier 5 can be attached to the vehicle.

[0033] A brake lining assembly 7 is arranged in the interior of the housing formed by the drum 3 and the brake carrier 5. The brake lining assembly 7 has a multiplicity of brake lining segments 9, namely a total of twelve according to one embodiment, which are pressed into a radially movable lining carrier 11, wherein the lining carrier 11 is guided in a radially movable manner on the brake carrier 5. The adjusting movement of the lining carriers 11 with the brake lining segments 9 is accomplished by way of an actuating ring 13, which can be turned in rotation about a drum axis X and displaced axially in the direction of the drum axis X.

[0034] FIGS. 2-4 illustrate the action of the drum brake according to the present disclosure, in particular of the actuating ring 13 of the drum brake 1.

[0035] FIG. 2 shows the drum brake in cross section in a plane which coincides with the drum axis X. The actuating ring 13 is arranged in sliding fashion on a stub 15 of the brake carrier 5. The actuating ring 13 is in a first, retracted, axial position A.sub.1. The brake lining assembly 7, of which one brake lining segment 9 with a lining carrier 11 is shown here by way of example, is coupled to the actuating ring 13 by way of a bearing assembly 17 and a piston 19, which can move radially in a guided manner. The actuating ring 13 has a displacement surface arrangement 30 having a displacement surface 31, which is operatively connected to the piston 19 of the brake lining assembly 7 in such a way that an axial movement of the actuating ring 13 in the direction of arrow P.sub.1 results in a radial deflection of the piston 19 and, with the latter, of the brake lining segment 9.

[0036] The displacement surface arrangement 30 is formed integrally on the actuating ring 13, and each movement of the actuating ring is an identical movement of the actuating surface arrangement 30.

[0037] The maximum deflection which the brake lining assembly 7 can perform in the radial direction as a result of this interaction is defined by a first stroke length H.sub.1. The actuating ring 13 is furthermore also mounted on the stub 15 in such a way as to be rotatable about the drum axis X, and can be moved in both rotational directions in the direction of arrow P.sub.2, cf. especially FIG. 4.

[0038] To bring about the axial displacement in the direction of arrow P.sub.1, the actuating ring 13 is operatively connected to a first actuator 23, which can be a pneumatic actuator, for example. The first actuator 23 is connected in a fluid-transmitting manner to a compressed air supply 29, preferably the compressed air supply of the brake system of a commercial vehicle (not shown).

[0039] To bring about the rotary movement in the direction of arrow P.sub.2, the actuating ring 13 is furthermore operatively connected to a second actuator 25, which can be an electric motor actuator, for example. The second actuator 25 is preferably coupled to the actuating ring 13 by way of a mechanism 27.

[0040] The first actuator 23 and the second actuator 25 are kinematically decoupled from one another. Accordingly, activation of just one of the actuators 23, 25 brings about only the movement of the actuating ring 13 exclusively in the selected direction. In other words, activation by way of the first actuator 23 brings about exclusively the displacement movement in the direction of arrow P.sub.1, and activation only by the second actuator 25 brings about exclusively a rotary movement in the direction of arrow P.sub.2 about the drum axis X.

[0041] In FIG. 3, following activation by the first actuator 23, the actuating ring 13 has been moved in the direction of arrow P.sub.1 out of the first axial position A.sub.1 into a second, extended, axial position A.sub.2. Owing to a rising profile V.sub.1 of the displacement surface 31 in the direction of the drum axis X, the brake lining assembly 7 has been deflected radially owing to the movement of the piston 19 in the direction of arrow P.sub.3. Owing to the coupling of all the brake lining segments 9 of the drum brake 1, this has taken place synchronously in the case of all the brake lining segments 9.

[0042] As a particular preference, activation by way of the first actuator 23 is used to bring about the application and release movement of the brake lining assembly 7 for the service braking and/or parking brake function.

[0043] In addition to the adjusting movement, shown in FIGS. 2 and 3, of the brake lining assembly 7, adjustment of the brake lining assembly 7 in the radial direction by way of activation of the actuating ring 13 by the second actuator 25 is furthermore also possible, this being particularly clearly apparent also from FIG. 4.

[0044] While the rising axial profile V.sub.1, which defines the first stroke length H.sub.1, extends between a first axial end 35 and a second axial end 37, the displacement surface 31, which is divided into a number of surface segments 32 that corresponds to the number of brake lining segments 9, has a first rotational position D.sub.1 and a second rotational position D.sub.2 for each of the surface segments 32, which are each offset from the respectively adjacent surface segment 32 by step-type boundaries 39, 41.

[0045] Between rotational positions D.sub.1 and D.sub.2, the respective surface segment 32 forms an angle along which the surface segment 32 has a rising profile V.sub.2 in the circumferential direction, which defines a second stroke H.sub.2. If, therefore, the actuating ring 13 is moved in rotation about the drum axis X in the direction of arrow P.sub.2, this being accomplished by activation by way of the second actuator 25, the piston 19 and, together with the latter, the brake lining assembly 7 and the brake lining segments 9 thereof are likewise deflected in the radial direction.

[0046] The second stroke length H.sub.2 is preferably smaller than the first stroke length H.sub.1. The radial adjustment of the brake lining assembly 7 by way of rotary movement of the actuating ring 13 is preferably used for release clearance adjustment, i.e. to adjust the position of the brake linings as a consequence of the wear which occurs during their life.

[0047] To perform the rotary movement about the drum axis X, the actuating ring 13 preferably has a toothing system 33, e.g. cylindrical toothing, which is in mesh with the mechanism 27, which is operatively connected to the second actuator 25.

[0048] Consideration of the surface segments 32 of the displacement surface 31 shows that the first profile V.sub.1 is of linear design in the axial direction. Consequently, each incremental axial movement of the actuating ring 13 is associated with a linearly proportional radial deflection of the brake lining assembly 7. When considered in the circumferential direction, the second profile V.sub.2 between the first rotational position D.sub.1 and the second rotational position D.sub.2 it is developed in a manner proportional to the angle of rotation . Each incremental change in the angle is likewise associated in a linearly proportional manner with a deflection of the brake lining assembly 7 in the radial direction. This finds its visual expression in a slightly convex curvature of the surface segments 32 of the displacement surface 31.

REFERENCE SIGNS (PART OF THE DESCRIPTION)

[0049] 1 drum brake [0050] 3 drum [0051] 4,6 flange [0052] 5 brake carrier [0053] 7 brake lining assembly [0054] 9 brake lining segment [0055] 11 lining carrier [0056] 13 actuating ring [0057] 15 stub [0058] 17 bearing assembly, pin [0059] 19 piston [0060] 21 friction surface [0061] 23 first actuator [0062] 25 second actuator [0063] 27 mechanism [0064] 29 compressed air supply [0065] 30 displacement surface arrangement [0066] 31 displacement surface [0067] 32 surface segment, displacement surface [0068] 33 toothing system [0069] 35 first axial end [0070] 37 second axial end [0071] 39, 41 steps [0072] A.sub.1 first axial position [0073] A.sub.2 second axial position [0074] P.sub.1, P.sub.2, P.sub.3 arrows [0075] D.sub.1, D.sub.2 rotational position [0076] H.sub.1, H.sub.2 stroke length [0077] V.sub.1 (first) profile, axial direction [0078] V.sub.2 (second) profile, circumferential direction [0079] X drum axis [0080] rotation angle