Disc brake and method for mounting a brake component

Abstract

A disc brake (1) for a commercial vehicle, comprising a brake caliper (2) which overlaps a brake disc which, during braking, is contacted on both sides by brake pads mounted in the brake caliper (2) and which has a receiving space (10) for brake components, which is closed on the side facing the brake disc by a cover (4) which rests against the brake caliper (2) and is connected to it by screws, wherein at least one screw for closing the cover (4) is designed as a self-tapping screw (8), which is arranged in a corresponding receiving channel of the brake caliper (2) by cutting a thread (9) into a coating material introduced in the receiving channel, and a method for mounting a brake component.

Description

The present invention relates to a disc brake and a method for assembling a brake component of such a disc brake. In commercial vehicle disc brakes, the interior of the brake caliper is sealed with metal or plastic covers, which are then bolted to the caliper. The brake caliper typically has a cathodic dip coating (KTL). The threads required for the bolting must be cut into the caliper's mounting channels in a separate operation after the coating process, as any remaining KTL in the threads would lead to irregular, temperature-dependent loosening torques. However, due to the aforementioned sequence of steps, the existing manufacturing process requires an increased number of assembly steps and possibly various mechanical connecting elements for mounting the closure lid. The invention is therefore based on the objective of further developing a disc brake of the generic type in such a way that it can be manufactured more easily and cost-effectively with less effort in terms of design and manufacturing technology. This problem is solved by a disc brake having the features of claim 1. A disc brake according to the invention for a commercial vehicle has a brake caliper that engages a brake disc, which, during braking, is contacted on both sides by brake pads mounted in the brake caliper. The brake disc and the brake pads are also part of the disc brake. The disc brake is particularly preferably designed as a sliding caliper disc brake. The disc brake has a receiving space for brake components, e.g., a brake actuator assembly, a synchronization device for synchronizing several brake actuators, and / or a potentiometer, in particular for determining brake wear. The disc brake can have a stationary brake housing and the brake caliper slidably mounted on the brake housing. The receiving space can be located in the brake housing or in the brake caliper. Typically, both brake elements can be exposed to extensive spray or rainwater, e.g., in the case of severe weather.Therefore, the combination of high humidity with driving-related vibrations in both variants poses a particular challenge for the optimal sealing of the recording space. The sealing cap or the opening of the receiving chamber is preferably located on the side facing the brake disc. It is closed by the sealing cap, which rests against the brake caliper and is thus connected to it by screws. The sealing cap is therefore also part of the disc brake. The cover can close a mounting opening, a synchronization device (part of the clamping mechanism), or a potentiometer housing. This housing can also be the interior of a larger housing, which is itself located within a larger housing. Preferably, however, the housing is located directly in the brake caliper or in the brake housing on which the caliper is slidably mounted. According to the invention, at least some of the screws are designed to seal the end cap. For this purpose, the screw is arranged in a corresponding receiving channel of the brake caliper, e.g., in a blind hole or bore. This arrangement involves cutting a thread into a coating material introduced into the receiving channel. Such a screw can be designed as a self-tapping screw for cutting into the coating material. Preferably, several or all of the screws can be arranged as self-tapping screws, as described above, in several of the corresponding receiving channels. By using the aforementioned screw, particularly in the form of a self-tapping screw, no coating material needs to be removed beforehand. Instead, the coating material acts as an additional sealant at the transition to the metal wall of the brake caliper, which is usually cast. This significantly simplifies the manufacturing of the disc brake and also facilitates the replacement of brake components located within the mounting area. Further advantageous embodiments of the invention are part of the dependent claims. The cutting screw can advantageously be designed as a thread-cutting screw for screwing into a solid metal body, such as a cast metal, in particular a cast steel or cast iron material. The receiving channel, in the contact area with the self-tapping screw, has a first thread that corresponds to the self-tapping screw. Beyond the contact area, a thread is arranged in the receiving channel, e.g., in the borehole, which, in its uncoated state, has a smaller inner diameter than the outer diameter of the self-tapping screw. This indicates that the self-tapping screw was inserted into the receiving channel, forming a new thread. The self-tapping screw is therefore a thread-forming or thread-cutting screw, which has an interference fit with the receiving channel before the screw is inserted. At least the nominal thread diameter D of the screw is always larger than the internal thread diameter DI of the uncoated thread of the receiving channel. When tightened, this ensures that excess paint is always removed, as the final deformation of the thread takes place during this process, i.e., the thread is (fully) cut. The KTL coating, which negatively affects the strength / durability of the screw connection, is thus largely removed from the thread. It is advantageous if the self-tapping screw(s) each have a cutting edge or cutting rib. Preferably, the cutting rib or cutting edge is arranged helically on the outer wall of the screw body. A thread is arranged between the cutting rib or cutting edge. In the thread, a coating material, preferably a paint coating material, and particularly preferably a cathodic dip coating (KTL coating) material, is applied at least partially in the thread when the self-tapping screw is installed. This material, which is worn away during installation, acts as an additional seal against the ingress of water into the receiving channel along the thread. The cutting screw can advantageously have a terminal conical projection to facilitate the cutting operation and insertion into the receiving channel. The cover can be secured to the brake caliper solely via the self-tapping screws and, if necessary, additionally by clamping forces. These clamping forces allow the cover to be pre-positioned. The self-tapping screws are the only mechanical fasteners for further securing the cover. No other fasteners, such as bolts or other screws, are required. The conical insert can be positioned within a coated area of ​​the brake caliper's mounting channel. This design creates a continuous seal at the screw's base within the mounting channel, thanks to the coating. Simultaneously, vibrations in this area are dampened. To improve the removal of coating material during the screwing in of the cutting screw, it may have one or more removal grooves which interrupt the thread and which have a steeper pitch than the thread. Ideally, the discharge groove should also be sealed against water ingress. Therefore, it is advantageous if, when the cutting screw is installed, a coating material, preferably a paint coating, and particularly preferably a cathodic dip coating (KTL) material, is applied to the discharge groove. Furthermore, the brake caliper can advantageously have a paint coating, preferably a KTL coating, in a manner known per se. Beyond the cutting screw, the receiving channel has no thread, but a smooth coated surface, resulting in further optimized sealing and vibration damping via the smooth contact surface at the screw base. Furthermore, according to the invention, a method for mounting a brake component, in particular a clamping device, in the receiving space of a disc brake according to the invention comprises the following steps: A. Providing a brake caliper or a brake housing with the receiving space; B. Inserting a brake component, in particular a clamping device, through a mounting opening into the receiving space; and C. Closing the mounting opening by means of the closing cover by inserting self-tapping screws into corresponding receiving channels of the brake caliper or the brake housing on the side facing the mounting opening. Thus, a corrosion-tight connection of the closure cover can be achieved not only during initial assembly, but also when replacing the clamping device, e.g. in case of defect, using the self-tapping screws. Additionally, it can be advantageous to apply a coating to the receiving channel after each removal of the self-tapping screws from the screw hole, before inserting another self-tapping screw. This coating can provide a renewed sealing effect in the screw connection area and replace any sealant or coating material that has already been worn away. However, it is also possible that the cutting screw only engages or cuts into the coating and not into the metallic base material of the receiving channel. Preferably, a thread-forming or thread-cutting screw with an oversized thread is used to form the closure, which has a KTL coating in the receiving channel. The receiving channel can have a thread with a smaller diameter than the oversized thread. It is also advantageous if the method includes providing the brake caliper with a paint coating, preferably by coating using cathodic dip coating. According to the invention, the closure is achieved in step C by cutting the cutting screw into the coated surface of the receiving channel. The lid can be preferably manufactured as a sheet metal part by stamping and forming. This lid is characterized by its simple and therefore extremely cost-effective production. Thanks to the cutting screws, it is relatively easy to install and can be positioned on the brake caliper in a sealing manner. As already discussed, the cutting screw is provided, for example, with one or more helical discharge grooves, the transitions to the thread of which can form a sharp-edged cutting notch to remove KTL from the receiving channel, whereas the grooves can receive the scraped-off KTL. In general, solutions are conceivable which have a sharp edge (cutting edge) perpendicular to the circumferential direction of the cutting screw (screwing direction) and notches and / or recesses in which the scraped-off KTL can collect. An embodiment of the invention is described below with reference to the accompanying drawings. The invention is not limited to this embodiment, but can be modified in a variety of ways. Figure 1 shows a perspective view of a brake caliper of a disc brake according to the invention, provided with a cover; Figure 2 shows a perspective view of the cover of Figure 1; and Figure 3 shows a side view of a self-tapping screw for fixing the cover of Figure 2. Figure 1 shows the brake caliper 2 of a disc brake 1 for a commercial vehicle, which is designed as a sliding caliper disc brake. The brake caliper 2 has a receiving space 10 for brake components, in particular a clamping device. The receiving space 10 is located adjacent to a brake disc (not shown). The brake components located in the receiving space 10 are accessible via a mounting opening 3 and / or can be positioned within the receiving space. The aforementioned mounting opening 3 can be at least partially covered or closed by a cover 4, which is shown in detail in Figure 2. Furthermore, the cover 4 has two openings 5, which, when the disc brake is functioning, are pressed through by two brake pistons of the clamping device located in the receiving space 10. Bellows (not shown) seal the passage between the brake pistons and the cover 4.However, the invention is not limited to a closure cover 4 in the illustrated form; in particular, various construction variants of closure covers are possible which have only one or more than two openings 5 ​​for the passage of a corresponding number of brake pistons or other brake components. The end cap is secured to a mounting surface of the brake caliper 2 by screws. The end cap may also have a sealing cord or ring on its edge, which, when installed, is positioned between the mounting surface and the end cap. Overall, the end cap fits tightly against the mounting surface. The closure cover may have openings 6, e.g. bores, for pre-positioning the fasteners, into which the fasteners can be inserted and in which they can engage. To stiffen the sheet metal closure cover 4, a rib 7 can be arranged on the edge, which protrudes or is recessed compared to the rest of the cover surface. Alternatively, a plastic cover can also be used as the closure cover. The closure cover 4 can preferably be designed as a sheet metal part. It can be manufactured by deep drawing and / or stamping. Alternatively, it is also conceivable to design the closure cover 4 as a casting. To prevent corrosion, the brake caliper has a coating, preferably an organic coating. This coating can be applied as a cathodic dip coating (e-coating). The coating is based on an aqueous, electrically conductive system and penetrates cavities and undercuts. According to the invention, one or more cutting screws 8 are used for the first time to fix the closing plate to the brake caliper painted in this way. The use of self-tapping screws to secure metallic parts is a known practice in other applications. However, the securing of the cover plate of a brake caliper's mounting opening is subject to specific stresses. On the one hand, the cover plate is subjected to axial tensile and compressive forces from the bellows used to seal the brake pistons, relative to the brake disc, during clamping. During driving, for example on cobblestones, the locking plate is subjected to increased vibrations. Heat generated during braking can also lead to irregularities in the loosening torque of the bolted connections, provided that the KTL coating material is not removed from the area of ​​the bolted connection in the case of standard bolted connections. Unlike conventional screw connections between brake caliper and cover plate, where KTL material always had to be removed due to the increased risk of the screws loosening, it has surprisingly been shown that with self-tapping screws 8, even when the screw engages an opening with existing KTL coating within the channel or bore in the brake caliper 2, sufficient fixation of the cover plate is achieved under operating conditions. The threads are coated with KTL material. This KTL material provides additional sealing against moisture ingress into the bore area and protects against the screw connection becoming permanently seized due to rust formation in the thread area. The use of self-tapping screws is also more efficient from a manufacturing perspective, as it simplifies the manufacturing and assembly process, in which KTL coating is permitted in the mounting holes of the brake caliper. Fig. 3 shows a preferred embodiment of a self-tapping screw 8 for fixing the cover plate 4 of Fig. 2 to the brake caliper 2 of Fig. 1. In a conventional manner, the self-tapping screw has a screw body 13 and a screw head 14. In addition to a thread 9 arranged spirally around the screw axis on the outside of the screw body and the sharp-edged, also spirally shaped cutting rib 11 located between them, the self-tapping screw 8 has discharge grooves 12 into which a portion of the scraped-off KTL coating material can be discharged. The cutting screw 8 also has a conical projection 15, which facilitates the penetration of the cutting rib into the material of the end cap or the brake caliper and allows better centering of the cutting screw 8 in the openings of the end cap and in the receiving channel of the brake caliper. In general, solutions are also conceivable which have a cutting edge perpendicular to the circumference in the screw-in direction, as well as notches / recesses in which the scraped-off KTL can collect. During the fixing process, the discharge via the discharge grooves 12 only occurs with continuous forward movement. In the final position, a residual amount of KTL material, particularly the most recently removed material, remains in the discharge grooves 12 and / or threads 9, providing a special form of sealing against corrosion at this point. This aspect is particularly important in the braking system, where brake components require special sealing, for example when driving in the rain. The displaced material, which in a conventional screw connection is perceived as a negative factor influencing the loosening torque, is surprisingly used as a seal against water penetrating the deeper threads of the screw connection when self-tapping screws are used. As an alternative to the example described above, the self-tapping screw can also dig into the base material of a brake caliper or, alternatively, a brake housing. For this purpose, a thread-forming or thread-cutting screw with an oversized thread is used. REFERENCE MARK 1 Disc brake 2 Brake caliper 3 Mounting opening 4 Cover 5 Openings 6 Openings 7 Bridge 8 Self-tapping screw 9 Thread 10 Receipt space 11 Cutting rib 12 Discharge groove 13 Screw body 14 Screw head 15 Conical shoulder

Claims

Disc brake (1) for a commercial vehicle, with a brake caliper (2) which overlaps a brake disc which, during braking, is contacted on both sides by brake pads mounted in the brake caliper (2) and wherein the disc brake (1) has a receiving space (10) for brake components which is closed by a sealing cover (4) which is fixed to the disc brake by screws, characterized in that at least one of the screws for closing the receiving space (10) with the sealing cover (4) is arranged in a receiving channel of the disc brake by cutting a thread (9) into a coating material introduced in the receiving channel. Disc brake according to claim 1, characterized in that the at least one screw is designed as a cutting screw (8) which is arranged for cutting into the coating material. Disc brake according to claim 1 or 2, characterized in that one receiving chamber (10) is assigned to the brake caliper and that the closing cover for closing the receiving chamber rests on the side facing the brake disc on the brake caliper (2) and so that the receiving chamber is closed by the screws, wherein the receiving channel is arranged in the brake caliper. Disc brake according to claim 1 or 2, characterized in that the receiving space (10) is assigned to a brake housing which is arranged in a stationary position with respect to the brake caliper (2), wherein at least in some areas a brake actuator arrangement with several brake components is arranged in the receiving space and that the closing cover (4) for closing the receiving space (19) rests on the side facing the brake disc on the brake housing, so that the receiving space (10) is closed by the screws, wherein the receiving channel is arranged in the brake housing. Disc brake according to claim 2, characterized in that the cutting screw is designed as a thread-cutting screw, wherein the receiving channel in the contact area with the cutting screw has a first thread corresponding to the cutting screw and beyond the contact area has a thread which in the uncoated state has a smaller inner diameter than the outer diameter of the thread-cutting screw. Disc brake according to one of the preceding claims, characterized in that the cutting screw (8) has a screw body (13) and a screw head (14), and that the cutting screw (8) has a cutting edge or cutting rib (11), in particular a cutting edge or cutting rib (11) arranged spirally on the outer wall of the screw body (13), wherein a thread (9) is arranged between the cutting edge or cutting rib (11) and wherein the coating material, preferably a paint layer material, particularly preferably a KTL coating, is arranged at least partially in the thread (9) in the assembled state of the cutting screw (8). Disc brake according to one of the preceding claims, characterized in that the cutting screw (8) has a terminal conical projection (15). Disc brake according to one of the preceding claims, characterized in that the end cap (4) is fixed exclusively via the cutting screws (8) and, if necessary, additionally via clamping forces on the brake caliper (2). Disc brake according to one of the preceding claims, characterized in that the conical projection (15) is located in a coated area of ​​the receiving channel of the brake caliper (2). Disc brake according to one of the preceding claims, characterized in that the cutting screw (8) has one or more discharge grooves (12) which interrupt the thread (9) and which preferably have a steeper pitch than the thread (9). Disc brake according to one of the preceding claims, characterized in that in the assembled state of the cutting screw (8) the coating material, preferably a paint coating, particularly preferably KTL material, is arranged in the discharge groove (12). Disc brake according to one of the preceding claims, characterized in that the brake caliper (2) has a paint coating, preferably a KTL coating. Disc brake according to one of the preceding claims, characterized in that the receiving channel of the brake caliper (2) beyond the cutting screw (8) has a layer of coating material without a thread. Disc brake according to one of the preceding claims, characterized in that the closure cover (4) has openings (6), preferably bores, into which the cutting screws (8) engage in a material-locking manner in the assembled state. Method for mounting a brake component, in particular a clamping device, in the receiving space (10) of a disc brake (1) according to one of the preceding claims, characterized by the following steps: A. Providing the brake caliper (2) or a brake housing with the receiving space (10) and with receiving channels arranged at the periphery of the receiving space, the receiving channels having a coating on the channel wall. B. Inserting a brake component, in particular a clamping device, through a mounting opening (3) into the receiving space (10); C. Closing the mounting opening (3) by means of the closing cover (4) by inserting screws (8) into receiving channels at the periphery of the mounting opening (3) with partial discharge of the coating. Method according to claim 15, characterized in that the provision of the brake caliper (2) comprises a paint coating, preferably by coating by means of cathodic dip coating. Method according to claim 15 or 16, characterized in that the closure according to step C is effected by cutting the respective screws designed as cutting screws (8) into the coated surface of the receiving channel of the brake caliper (2). Method according to one of the preceding claims, characterized in that the receiving channels in the uncoated state before the insertion of the screws according to step C each have an opening diameter smaller than the outer diameter of the cutting screw (8). Method according to one of the preceding claims, characterized in that a respective opening (6) of the closure cover (4) has a smaller diameter before closure in step C than the maximum outer radius of the corresponding cutting screw (8).

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