Device with a sensor and a snap ring for indicating wear of a brake pad of a disc brake.

Description

[0001] The present invention relates to a device for indicating wear of a brake pad of a disc brake, as is used particularly in commercial vehicles, for example in trucks, trailers or buses.

[0002] Disc brakes in motor vehicles have brake pads that, depending on the activation of a brake force sensor, are pressed by an actuator against a brake disc connected to a wheel to be braked, in order to transmit a braking effect to the brake disc and the wheel during braking. The brake pads have friction surfaces that wear down through braking.

[0003] It is desirable to replace a brake pad when its friction surface has worn down to a predetermined wear limit.

[0004] Commercial vehicles in particular often have a brake pad wear indicator, which alerts the driver of the commercial vehicle to wear on the brake pads.

[0005] A disc brake with such a brake pad wear indicator is known, for example, from WO 2012 / 052121 A1.

[0006] DE 39 04 673 A1 discloses a device for indicating the wear of a friction lining of a brake pad of a disc brake, which has an electrically conductive element that comes into electrical contact with the brake disc when a predetermined wear limit is reached during braking. The device has a sensor that is inserted into a bore of the disc brake and secured in the bore by a snap ring. The snap ring secures the sensor in the bore with a preload, so that the sensor cannot rotate or shift while the commercial vehicle is being driven.

[0007] Another device for indicating wear is disclosed in JPH1047397A, which shows a wear sensor device and a shaped spring wire for fixing the wear sensor device in a brake pad. The straight sections of the spring wire rest axially against the pad wear sensor. The circular bend serves to axially pull out the retaining ring to release the pad wear sensor from the brake pad.

[0008] JP2000220676 A and DE102015211176 A1 disclose a further device for indicating wear, wherein the snap ring is designed in the shape of tweezers.

[0009] GB649860A, WO9725539 A1, FR994526 A and US 3758923 disclose snap rings in various forms, but not a device for indicating wear per se.

[0010] For securing such a sensor in a brake pad, round wire snap rings are used, for example. Special pliers are required to install such a snap ring. However, even with special pliers, installing a snap ring is a delicate task. Snap rings of this type are also known as retaining rings, spring rings, or snap rings.

[0011] It is therefore an object of the invention to provide a device for indicating wear of a brake pad of a disc brake of the type mentioned above, which has a simplified assembly.

[0012] This problem is solved by a device for indicating wear of a brake pad of a disc brake according to claim 1.

[0013] The dependent claim includes an advantageous further development and improvement of the invention in accordance with the following description of these measures.

[0014] The invention relates to a device for indicating the wear of a brake pad in a disc brake, which triggers a signal when a predetermined wear limit of the brake pad is reached. The device includes a snap ring and a sensor with a sensor head that has a groove for receiving the snap ring to secure the sensor to the brake pad. The sensor head can be mounted in a bore in the brake pad. The groove has a flattened area, and the shape of the snap ring is adapted to this flattened area.

[0015] The snap ring has a round area with a uniform curvature, which is bounded by two ends.

[0016] Furthermore, each end of the circular area is separated from the circular area by an end piece of the snap ring, each end piece having a straight section. The snap ring is bounded by end faces, the bends of which cause the end faces to lie parallel to each other, since the straight sections of the end pieces lie on a straight line, parallel to each other, and the end faces have perpendicular intersections.

[0017] Furthermore, the sensor head has a cylindrical shape and the groove runs around the circumference of the sensor head.

[0018] In another preferred embodiment, the flattened area of ​​the groove has a straight area, and the shape of the snap ring is adapted to the straight area of ​​the groove.

[0019] According to the invention, the flattened area of ​​the groove and the further course of the groove, as well as the round area and the two flattened areas of the snap ring, are designed in such a way that the snap ring engages in the groove with a mate fit.

[0020] A device for indicating wear facilitates easier mounting of the sensor on a brake pad of a disc brake. The flattened ends of the snap ring allow for a defined positioning of the snap ring in the groove of the sensor head. Exemplary embodiments of the invention are shown schematically in the drawings and are explained in more detail below with reference to the figures.

[0021] They show: Fig. 1 a snap ring according to the prior art; Fig. 2 a snap ring for a device according to Fig. 3 ; and Fig. 3 the snap ring of the Fig. 2 and a sensor of a device for

[0022] Indication of the wear of a brake pad of a disc brake according to the invention.

[0023] In the Fig. 1 A snap ring 1 according to the prior art is shown in a top view, having a uniformly curved, circular curvature up to its ends 2, 3. The snap ring 1 is preferably made of a round steel wire.

[0024] The snap ring 1 can be used, for example, to attach a brake pad wear indicator sensor to a disc brake. For this purpose, it is inserted into a groove in the sensor. Special pliers are required to install such a snap ring 1. However, it is still possible that the snap ring 1 may become jammed in the groove during installation due to its free ends.

[0025] A snap ring 10 for a device according to the invention Fig. 3 is schematic in the Fig. 2 The snap ring 10 has a region 12 with a uniformly curved, circular shape, the region 12 being bounded at its ends 14, 16 by bends 18 and 20, respectively. These bends 18 and 20 delineate two end pieces 22 and 24 of the snap ring 10 from the circular region 12. The bends 18 and 20 are curved inwards towards a center 25 of the snap ring 10 defined by the circular region 12. The end pieces 22 and 24 of the snap ring 10 are flattened.

[0026] The flattened end pieces 22, 24 each have a straight section, indicated by a segment 26. The snap ring 10 is bounded by end surfaces 28, 30, whereby, due to the bends 18, 20, the end surfaces 28, 30 are parallel to each other in this embodiment, since the straight sections of the end pieces 22, 24 are on a surface in the Fig. 2 The straight lines not shown lie parallel to each other, and the end surfaces 28, 30 have perpendicular cross-sectional surfaces.

[0027] The snap ring 10 can be used in particular for attaching a sensor to a brake pad of a disc brake.

[0028] The Fig. 3 Figure 1 schematically shows a sensor 32 of a device for indicating the wear of a brake pad of a disc brake according to the invention, which has a cylindrical sensor head 34 with which the sensor 32 is attached to a brake pad of a disc brake, in the Fig. 3 The sensor head 34, which is not shown, can be attached. For this purpose, the sensor head 34 is, for example, pushed into a bore in the brake pad and then secured by the snap ring 10. The sensor head 34 can be secured in the bore of the brake pad by the snap ring 10, in particular with a preload, so that the sensor 32 is secured against rotation and displacement.

[0029] The sensor 32 has a groove 36 extending around the circumference of the sensor head 34 for receiving the snap ring 10. The groove 36 has, in particular, a straight section which is dimensioned to fit the straight end pieces 22, 24 of the snap ring 10. The straight section of the groove 36, its further course, the circular section 12, and the flattened end pieces 22, 24 of the snap ring 10 are shaped such that the snap ring 10 engages in the groove 36 with a mate fit. The snap ring 10 allows the sensor 32 to be detachably attached to a brake pad.

[0030] The snap ring 10 is preferably a round wire snap ring and is made, for example, of a round steel wire, in particular a spring wire.

[0031] All examples and conditional formulations mentioned herein are to be understood without limitation to the specifically cited embodiments. The invention is not limited to the embodiments described herein. The appended claims define the scope of protection of the invention. Reference numeral list (part of the description)

[0032] 1 Snap ring 2, 3 Ends of the snap ring 1 10 Snap ring 12 Area with a uniform curvature 14, 16 Ends of the area 12 18, 20 Bends 22, 24 End pieces of the snap ring 10 25 Center of the snap ring 10 26 Section 28, 30 End faces of the snap ring 10 32 Sensor 34 Sensor head 36 Groove

Claims

1. Device for indicating the wear on a brake pad of a disc brake, which device triggers a signal when a predetermined wear limit of the brake pad is reached, and comprises a snap ring (10) and a sensor (32) having a sensor head (34) which can be fastened in a bore of the brake pad and which has a groove (36) for receiving the snap ring (10) in order to secure the sensor (32) to the brake pad, the groove (36) having a flattened region and the shape of the snap ring (10) being adapted to the flattened region, the snap ring (10) having a round region (12) with a uniform curvature, and the round region (12) being delimited by two ends (14, 16), each end (14, 16) of the round region (12) respectively distinguishing an end piece (22, 24) of the snap ring (10) from the round region (12), each end piece (22, 24) having a straight region, and the two straight regions being delimited by end surfaces (28, 30) of the snap ring (10), characterized in that the end surfaces (28, 30) are opposite one another in a plane-parallel manner, the sensor head (34) having a cylindrical shape and the groove (36) extending over a circumference of the sensor head (34), with the flattened region of the groove (36) and the further course of the groove (36), as well as the round region (12) and the two end pieces (36) of the snap ring (36), being designed such that the snap ring (10) engages in the groove (36) with a snug fit.

2. Device according to claim 1, wherein the flattened region of the groove (36) has a straight region, and the shape of the snap ring (10) is adapted to the straight region of the groove (36).