ELECTROMECHANICAL DRUM BRAKE

Abstract

An electromechanical drum brake for a motor vehicle. The electromechanical drum brake includes a drum, in which brake shoes are arranged, and an adjusting device, which is arranged between the brake shoes and driven by a drive unit and via which the brake shoes can be spread for braking. An end of each brake shoe that faces the adjusting device is supported on a support element cooperating with the adjusting device, movably in relation to the support element, wherein a spreading force of the adjusting device is transferable to the brake shoes via the support element.

Claims

1. An electromechanical drum brake for a motor vehicle, comprising: a drum, in which brake shoes are arranged; and an adjusting device, which is arranged between the brake shoes and driven by a drive unit and via which the brake shoes can be spread for braking; wherein an end of each of the brake shoes that faces the adjusting device is supported on a support arrangement cooperating with the adjusting device, movably in relation to the support arrangement, wherein a spreading force of the adjusting device is transferable to the brake shoes via the support arrangement.

2. The electromechanical drum brake according to claim 1, wherein a support bearing, on which the brake shoes are movably supported, is arranged at an end of the brake shoes that is opposite to the adjusting device.

3. The electromechanical drum brake according to claim 1, wherein the support arrangement includes semi-annular expansion clips.

4. The electromechanical drum brake according to claim 3, wherein a support bearing, on which the expansion clips are rotatably supported, is arranged at an end of the brake shoes that is opposite to the adjusting device.

5. The electromechanical drum brake according to claim 3, wherein at least one holding element, which cooperates with a corresponding expansion clip and via which the brake shoes can be held in a normal direction of the drum, is attached to the brake shoes.

6. The electromechanical drum brake according to claim 5, wherein the holding element is a retaining clip.

7. The electromechanical drum brake according to claim 3, wherein the adjusting device including a cam, and wherein, at an expansion clip end facing the cam, the expansion clips respectively include a roller carrier, on which a roller is arranged, which is in contact with the cam.

8. The electromechanical drum brake according to claim 1, wherein the adjusting device is an S-shaped cam.

9. The electromechanical drum brake according to claim 8, wherein an adjustment path of the cam is configured in such a way that the adjustment path includes wear of the brake shoes.

10. The electromechanical drum brake according to claim 1, wherein the drive unit includes a transmission unit, which is configured without locking.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG. 1 shows a schematic illustration of an electromechanical drum brake according to an exemplary embodiment of the present invention.

[0022] FIG. 2 shows a plan view of an internal arrangement in a drum according to an exemplary embodiment of the present invention.

[0023] FIG. 3 shows a sectional view in the area of the cam of the electromechanical drum brake according to FIG. 2.

[0024] FIG. 4 shows a support bearing according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0025] FIG. 1 shows a schematic illustration of an electromechanical drum brake 10 according to an exemplary embodiment of the present invention. The electromechanical drum brake 10 comprises a drive unit 14 and a drum 18. The drive unit 14 comprises an electric motor 22, which drives a transmission unit 26. The transmission unit 26 comprises a worm 30, which is driven by the electric motor 22 and which drives multiple spur gears 34 of the transmission unit 26. The drive unit 14 is attached to a rear wall 38 of the drum 18. An adjusting device 42 arranged in the drum 18 is driven via the spur gears 34.

[0026] FIG. 2 shows a plan view of an internal arrangement in a drum 18 according to an exemplary embodiment of the present invention. In this view, the drum 18 has been omitted for a better view. The figure also shows the adjusting device 42, which is designed as an S-shaped cam in this exemplary embodiment. The cam 42 cooperates with two support means 46, which are designed as expansion clips in this exemplary embodiment. In this exemplary embodiment, the expansion clips 46 are semi-annular. On each expansion clip end 50 facing the cam 42 is arranged a roller carrier 54, to which a roller 58 cooperating with the cam 42 is attached. The roller 58 rolls on a surface 62 of the cam 42 and thus follows the contour of the cam 42.

[0027] At their ends opposite to the cam 42, the expansion clips 46 are rotatably supported on a support bearing 66. Rotation of the cam 42 causes the expansion clips 46 to perform a rotational movement about the support bearing 66 in an area of the cam 42. Accordingly, the expansion clips 46 are spread by a rotation of the cam 42. By the spreading movement, the expansion clips 46 apply a spreading force F.sub.s to brake shoes 70 arranged in the drum 18. The spreading force F.sub.s is applied to an end 72 of the brake shoes 70 that faces the adjusting device 42. This end 72 of the brake shoes is movably supported on the expansion clips 46. Accordingly, for braking, the brake shoes 70 are placed against the drum 18.

[0028] Between a center point M of the drum 18 and the expansion clips 46, a respective holding element 74, via which the brake shoes 70 are held in a normal direction N.sub.T (see FIG. 1) of the drum 18, is arranged on the brake shoes 70. This prevents the brake shoes from moving in the normal direction N.sub.T within the drum. In the exemplary embodiment shown here, the holding elements 74 are designed as retaining clips. The holding elements 74 only abut against the expansion clips 46. This ensures relative mobility of the brake shoes 70 in relation to the expansion clips 46.

[0029] FIG. 3 shows a sectional view in the area of the cam 42 of the electromechanical drum brake 10 of FIG. 2. In this figure, it can be seen how the cam 42 acts on the expansion clips 46 via the rollers 58. At an expansion clip end 50 facing the adjusting device 42, the expansion clips 46 form an upper stop 78 for the brake shoes 70. The brake shoes 70 are only supported on the respective upper stop 78 and are thus movably mounted in the area of the upper stop 78. Via this upper stop 78, the spreading force F.sub.s can thus also be applied to the brake shoes 70 via the expansion clips 46.

[0030] FIG. 4 shows the support bearing 66 according to an exemplary embodiment of the present invention. At an end 80 of the brake shoes 70 that is opposite to the adjusting device 42, this support bearing 66 forms a lower stop 82 for the brake shoes 70. The brake shoes 70 are also only supported on the lower stop 82 so that the brake shoes are movable in relation to the lower stop 82. Accordingly, the brake shoes 70 only abut against the lower and upper stops 78, 82 so that the brake shoes 70 are not fixed in the drum 18 and can move. As a result, it is possible that out-of-roundness and eccentricity of the drum brake 10 can be compensated. A possibility of compensation in the area of the cam 42 can thus be dispensed with.