Disc brakes for a commercial vehicle

Abstract

Disc brake for a commercial vehicle, comprising a cast iron brake caliper (1) that overlaps a vehicle-side brake disc (2) and is axially displaceable relative to the brake disc (2) by means of at least one guide arm (9) on a stationary brake carrier (3), wherein the guide arm (9) attached to the brake carrier (3) is guided in at least one sliding bushing (7) which is axially secured by at least one integrally formed protrusion (14) engaging in a circumferential groove (13) of a bearing bore (12) of the brake caliper (1) produced during the casting of the brake caliper (1), characterized in that the at least one protrusion (14) has a side wall that is radially oriented circumferentially relative to the central axis of the sliding bushing (7).

Description

[0001] The invention relates to a disc brake for a commercial vehicle according to the preamble of claim 1.

[0002] The brake calliper of a disc brake, in particular a sliding calliper disc brake, serves to accommodate functional parts such as an application device, which is arranged in a receiving space of the brake calliper that can be closed by a cover.

[0003] A known application device has a pneumatically or electric motor-operated brake lever which, when actuated, acts on a bridge which is movably mounted in the brake calliper and in which adjusting spindles are positioned, by means of which an application-side brake pad can be pressed against a vehicle-side brake disc.

[0004] For axial movement of the brake disc, the brake caliper is mounted on at least one guide bar, preferably two, connected to a stationary brake carrier. The guide bars are guided in sliding bushings, which are secured against displacement in bearing bores of the brake caliper, so that the guide bar / sliding bushing combination forms a sliding bearing.

[0005] One of the plain bearings is designed as a loose bearing and the other as a fixed bearing, whereby the loose bearing has a larger radial play than the fixed bearing, in particular to compensate for manufacturing tolerances.

[0006] For optimized sliding of the brake caliper on the guide rails, the sliding bushings are made of a suitable plain bearing material, such as brass, bronze or similar.

[0007] The aforementioned axial displacement protection of the sliding bush in the bearing bore of the brake calliper is achieved by a positive fit, in that at least one external protrusion of the sliding bush projects into a recess in the bearing bore.

[0008] This recess is designed as a circumferential groove into which the protrusion of the sliding bush, produced by circumferential rolling, engages.

[0009] Since the plain bearing material, i.e., the aforementioned non-ferrous metal, is relatively expensive, instead of a single sliding bushing extending almost the entire length of the bearing bore, two sliding bushings are used. These are spaced apart and their combined length is shorter than the single sliding bushing mentioned above. This means that the material consumption is significantly reduced when two sliding bushings are used in the bearing bore.

[0010] However, circumferential rolling of both sliding bushes is problematic from a manufacturing point of view, especially since the circumferential groove assigned to one sliding bush can be incorporated during the casting of the brake caliper made of cast iron, while the circumferential groove assigned to the second sliding bush must be machined.

[0011] Due to the relatively small rolling depth of approximately 0.26 mm and the resulting sensitive machining, it is not possible to machine both sliding bushes simultaneously in one rolling process, which naturally results in significant cost disadvantages.

[0012] In order to achieve a cost reduction, the positive connection is achieved by caulking the sliding bushes in correspondence with the grooves, for which purpose caulking punches are used, with which material of the sliding bush is pressed into the groove of the bearing bore.

[0013] The tools used for this purpose are punches with a conical head that engages the inner surface of the respective sliding bushing and pushes the material into the circumferential groove of the bearing bore. For example, three punches can be used, distributed around the circumference.

[0014] The disadvantage, however, is that due to the conical shape of the punch head on the inside of the sliding bushing, a bead forms in the edge area of ​​the protrusion when chiseling, which protrudes beyond the inner surface of the sliding bushing.

[0015] To achieve a smooth sliding surface for the sliding bushing, an axial groove or countersink is introduced into the sliding bushing, which is deeper than the sliding surface of the sliding bushing by the height of the bead. Since the introduction of such a groove or countersink is associated with a cost that conflicts with the ever-desired goal of cost optimization, the conventional method of securing the sliding bushing against displacement in the bearing bore represents an unsatisfactory solution.

[0016] From DE 103 11 896 A1, a generic disc brake is known in which a protrusion can be formed onto the sliding bush by first creating a transverse slot and then deforming a portion of the sliding bush convexly outwards and thereby engaging in a recess of the brake calliper.

[0017] A disc brake of this type is disclosed in DE 10 2006 050 647 A1. While it mentions that a sliding bushing is held in the brake caliper to prevent displacement, this sliding bushing does not have a protrusion engaging the bearing bore.

[0018] In the Fig. 1A of DE 43 34 914 A1 depicts a disc brake of this type. The fastening of the sliding sleeve in the associated bearing bore is described in DE 10 2009 007 330 A1, with the sliding sleeve having outwardly directed protrusions that engage in recesses in the bearing bore.

[0019] Without any reference to the fastening of the sliding bushing to the brake calliper, US 2009 / 0 272 607 A1 discloses a disc brake in which a guide bar connected to a brake carrier is guided in a sliding bushing that is connected to the brake calliper.

[0020] DE 33 31 656 A1, DE 103 14 435 A1 and US 2013 / 0 298 711 A1 each disclose ways in which sliding bushes or bearing shells are secured against displacement in bearing bores.

[0021] The invention is based on the object of further developing a disc brake of the generic type so that it can be manufactured more easily and cost-effectively.

[0022] This object is achieved by a disc brake having the features of claim 1.

[0023] As has surprisingly been shown, the formation of the protuberances according to the invention, namely such that the protuberance has a circumferentially radially aligned side wall with respect to the central axis of the sliding bush, prevents the formation of the bead in the edge region during caulking as described in the prior art.

[0024] If a cylindrical mortising punch is used for caulking, the protrusion is formed as a cylindrical one with a closed bottom, so that the protrusion is in the form of a cylindrical pin which projects into the circumferential groove of the bearing bore, whereby the width of the groove preferably corresponds approximately to the outer diameter of the protrusion.

[0025] Further advantageous embodiments of the invention are characterized in the subclaims.

[0026] An embodiment of the invention is described below with reference to the accompanying drawings.

[0027] They show: Fig. 1 a disc brake according to the prior art in a partially sectioned plan view Fig. 2 a detail of a disc brake according to the invention in a sectional side view Fig. 3 and Fig. 4 each a partial section according to the indication III in Fig. 2 in different functional positions.

[0028] In the Fig. 1 shows a disc brake for a commercial vehicle according to the prior art, with a brake calliper 1 made of cast iron which overlaps a brake disc 2 and is mounted so as to be axially displaceable relative to the brake disc 2 via two plain bearings, one of which is designed as a fixed bearing 5 and the other as a loose bearing 6.

[0029] An application device 8 is arranged in the brake calliper 1, by means of which brake pads 4 can be pressed against the brake disc 2 on both sides during braking.

[0030] The two plain bearings, i.e. the fixed bearing 5 and the loose bearing 6, each have a sliding bush 7, which is mounted in the brake calliper 1 in a way that prevents it from shifting and which consists of a different material than the brake calliper 1, usually a non-ferrous metal with corresponding sliding properties.

[0031] In each sliding bushing 7, a guide bar 9 is slidably guided, which is fastened to a stationary brake carrier 3 by means of a screw 10.

[0032] To accommodate the sliding bushing 7 of the fixed bearing 5, the brake calliper 1 has a molded-on support 11 in order to obtain a length dimension of the fixed bearing 5 sufficient to absorb occurring loads.

[0033] In the Fig. 2 shows a detail of a disc brake according to the invention, the fixed bearing 5, in which two spaced-apart sliding bushes 7 are held in a bearing bore 12. Both the Fig. 2 as well as the Fig. 3, which shows a partial section of the fixed bearing 5 according to line III in Fig. 2, the sliding bushes 7 show before final assembly how they Fig. 4 and according to which the sliding bushes 7 are held in the bearing bore 12 in a way that prevents them from shifting. Fig. 3 and Fig. Only one of the two sliding bushings is shown in Figure 4. The second sliding bushing 7 is connected to the connecting piece 11 in the same manner, in accordance with the invention, in a manner that prevents it from slipping.

[0034] Furthermore, the number and arrangement of the sliding bushings 7 are exemplary. Of course, the number of sliding bushings 7 can vary, i.e., several sliding bushings 7 can be provided, or just one, as in the prior art. The floating bearing 6 can also be equipped with the sliding bushings 7 in the same way.

[0035] Each of the sliding bushings 7 in the embodiment is assigned a circumferential groove 13 which is introduced into the bearing bore 12 during casting.

[0036] To prevent displacement, the sliding bush 7, whose inner surface is provided with cups 16 for receiving grease, is partially deformed in such a way that a protrusion 14 engages in the groove 13 forming a depression, for which purpose a Fig. 3 is used, which stamps out the protuberance 14 by radially advancing in the direction of the arrow. According to the invention, the respective protuberance 14 has a circumferentially radially aligned side wall, ie, the protuberance 14 is stamped in the example in the sense of a cylindrical pin designed as a blind hole, as in the Fig. 4. The punch 15 is configured accordingly and is also cylindrical.

[0037] In principle, a different outer contour of the protuberance 14 is also conceivable, i.e. not cylindrical, but non-circular or angular, but in any case with a circumferentially radially aligned side wall, which preferably rests frictionally on the opposite side walls of the groove 13, whereby an anti-twist protection is also achieved.

[0038] Although in principle the formation of one protrusion 14 is sufficient to prevent displacement, it is preferable to use several protrusions 14 which engage in the groove and are preferably arranged at the same angular distance from one another.

Claims

[1] Disc brake for a commercial vehicle, with a brake calliper (1) made of cast iron which engages over a vehicle-side brake disc (2) and is held axially displaceably on a stationary brake carrier (3) by means of at least one guide bar (9) in relation to the brake disc (2), wherein the guide bar (9) fastened to the brake carrier (3) is guided in at least one sliding bush (7) which is held axially secured by at least one molded protrusion (14) engaging in a circumferential groove (13) of a bearing bore (12) of the brake calliper (1) produced during the casting of the brake calliper (1), characterized by that the at least one protrusion (14) has a side wall which is radially oriented circumferentially relative to the central axis of the sliding bush (7). [2] Disc brake according to claim 1, characterized by that the protrusion (14) engages in the recess formed as a circumferential groove (13). [3] Disc brake according to claim 1 or 2, characterized by that the protrusion (14) lies in the recess in a form-fitting and frictional manner. [4] Disc brake according to one of the preceding claims, characterized by that the protrusion (14) is embossed by means of a stamp (15). [5] Disc brake according to one of the preceding claims, characterized by that several protrusions (14) distributed over the circumference are provided. [6] Disc brake according to one of the preceding claims, characterized by that the plurality of protrusions (14) are arranged at the same angular distance from one another. [7] Disc brake according to one of the preceding claims, characterized by that each protrusion (14) engages in a recess adapted to its outer contour. [8] Disc brake according to one of the preceding claims, characterized by that the protrusion (14) has a round, non-round or angular cross-sectional contour. [9] Disc brake according to one of the preceding claims, characterized by that the protrusion (14) is designed as a blind hole.

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