Fully sintered multi-layer brake pad

Abstract

A fully sintered multi-layer brake pad (10; 110; 210; 310; 410; 510) having at least one first layer comprising iron-containing material and forming a pad carrier (20) and a second layer forming a friction pad (30; 230; 330; 430), which second layer is formed on the pad carrier (20) in a powder sintering process, and having at least one acoustic wear indicator which is designed to generate an indicator noise which is different from a braking noise of the friction pad (30; 230; 330; 430) when a wear limit of the friction pad (30; 230; 330; 430) is reached during braking operation.

Description

Technical FieldThe present invention relates to a fully sintered multi-layer brake pad, particularly for use with vehicle disc brakes.Description of the Prior ArtSintered friction materials for the production of brake linings are known, for example from DE-AS 1 214 409. Furthermore, measures have been described in the prior art for generating an acoustic warning signal when a limit thickness of the brake lining is reached. It is known from German Offenlegungsschrift No. 1,555,973 to press one or more metal inserts of the minimum thickness of the friction lining between the friction lining and the backing layer adjacent to the latter. DE 103 47 409 B4 discloses a brake lining with metal crimps integrally connected to the brake lining carrier plate.SUMMARY OF THE INVENTIONIn contrast, according to the invention, a fully sintered multilayer brake lining having the features of claim 1 is proposed.According to the invention, the proposed multilayer brake lining comprises a first layer with ferrous material forming a lining carrier and a second layer forming a friction lining, which is formed on the lining carrier in a powder sintering process. Furthermore, an acoustic wear indicator is provided. The acoustic wear indicator is in particular designed such that in the braking mode, when a wear limit of the friction lining is reached, an indicator noise different from a braking noise of the friction lining is generated.The invention is based on the finding of achieving a reliable acoustic warning effect by means of a wear indicator likewise formed within the scope of the powder sintering process for producing the brake lining.Various possibilities for configuring the wear indicator according to the invention are described below.The following is a numbered list of aspects of the invention:1. Fully sintered multilayer brake lining having at least one first layer, which forms a lining carrier and has ferrous material, and a second layer, which forms a friction lining and is formed on the lining carrier in a powder sintering process, and having at least one acoustic wear indicator, which is formed in particular within the scope of the powder sintering process.2. Brake pad according to Aspect 1, the wear indicator of which is designed to generate an indicator noise which differs from a braking noise of the friction pad when a wear limit of the friction pad is reached in the braking operation.3. Brake pad according to Aspect 1 or 2, in which the wear indicator is formed by addition of lubricants and / or friction value modifiers to the ferrous material of the pad carrier.4. Brake pad according to one of aspects 1 to 3, in which the wear indicator is formed by a sintered indicator layer arranged between the pad carrier and the friction pad.5. Brake pad according to one of aspects 1 to 4, in which the wear indicator is formed by an indicator structure defining the wear limit.6. Brake pad according to Aspect 5, the indicator structure of which is designed in such a way that the indicator noise is generated by a geometric configuration in the friction lining or a transition between the lining carrier and the friction lining.7. Brake pad according to Aspect 4, the wear indicator of which is formed by an indicator structure in the indicator layer or between the pad carrier and the indicator layer.8. Brake pad according to Aspect 7, the indicator structure of which is designed in such a way that the indicator noise is generated by a geometric configuration in the indicator layer or a transition between the pad carrier and the indicator layer or the friction pad and the indicator layer.9. Brake pad according to Aspect 6 or 8, the geometric configuration of which is corresponding relief surfaces, such as corrugations, zigzag structures or the like, or cavities, such as perforations, channels or the like.10. Brake pad according to Aspect 4, the indicator layer of which is formed by addition of lubricants and / or friction value modifiers to the ferrous material of the pad carrier.11. Brake pad according to aspect 3 or 10, in which the lubricants are selected from the group comprising in particular graphites, fluorides (e.g. CaF2, BaF2, LiF, MgF2), soft metals (e.g. copper, tin, zinc), metal sulfides (e.g. MnS, MoS 2, WS 2) and hexagonal boron nitride or the friction value modifiers from the group comprising in particular oxides (e.g. Al 2 O 3, MgO, ZrO 2, SiO 2 and compounds thereof), silicates (e.g. zirconium silicate, The following are selected from the group consisting of aluminum silicate, mica, feldspar, potassium silicate and compounds thereof), titanates (e.g. CaMgTiO 2), intermetallic phases (e.g. FeCr, FeV, FeW, FeMo, FeNb), carbides (e.g. WC, MoC, FeC, NbC) and nitrides (e.g. FeN, Mo 2 N, Si 3 N 4).12. Brake pad according to one of aspects 9 to 11, in which cavities of the indicator structure are filled with an indicator layer material.13. Brake pad according to one of aspects 2 to 12, the pad carrier of which has an improved braking action compared to conventional steel carrier plates and generates less wear on a brake disc.14. Brake lining according to one of aspects 4 to 13, in which the lining carrier and the friction lining are formed from the same materials.Further advantages and embodiments of the invention are evident from the dependent claims, the description and the accompanying drawing.It is understood that the features mentioned above and those still to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the present invention.The invention is schematically illustrated in the drawing on the basis of an exemplary embodiment and is described in detail below with reference to the drawing.Brief Description of the DrawingsFIG. 1 shows a perspective schematic illustration of a first embodiment of a fully sintered multilayer brake pad according to the invention. FIG. 2 shows, analogously to the illustration of FIG. 1, a second embodiment of a fully sintered multilayer brake pad according to the invention having an indicator layer. FIG. 3 shows, analogously to the illustration of FIG. 1, a third embodiment of a fully sintered multilayer brake pad according to the invention having an indicator structure. FIG. 4 shows the brake lining of FIG. 3 after the wear limit has been reached. FIG. 5 shows, analogously to the illustration of FIG. 3, a further embodiment of a fully sintered multilayer brake pad according to the invention having an indicator structure. FIG. 6 shows the embodiment of FIG. 5 with an additional indicator layer.DETAILED DESCRIPTIONIdentical and similar features shown in the individual figures are denoted by identical reference numerals.FIG. 1 shows a highly schematic perspective illustration of a first embodiment of a fully sintered multilayer brake pad 10 according to the invention for a disc brake, in particular a bicycle disc brake. The brake lining 10 comprises a lining carrier 20 as the first layer and a friction lining 30 as the second layer.The lining carrier 20 has a fundamentally known shape in a flat construction and comprises a substantially rectangular carrier section 22, from which a mounting section 24 with a through bore 26 projects in the manner of a handle. The through bore 26 serves for fastening the lining carrier 20 or the brake lining 10 to a brake cylinder (not shown here) of the disc brake. The geometric configuration of the lining carrier 20 is within the scope of the expert's discretion.The friction lining 30 is formed in a powder sintering process in a manner known per se on the carrier section 22 of the lining carrier 20. During operation, the side of the friction lining 30 facing away from the lining carrier 20 comes into contact as a friction surface 32 with a brake disc (not shown) of the disc brake during the braking operation and is correspondingly worn out with each braking operation, so that its thickness is reduced over the period of use.In order to signal to a user that a wear limit of the brake lining 10 is reached and it is at the time of a brake lining change, according to the first embodiment of the invention it is provided to mix components of lubricants and / or friction value modifiers into the ferrous material of the lining carrier 20 and to configure the lining carrier 20 in such a way that an indicator noise different from a brake noise of the friction lining is generated upon contact of the lining carrier 20 with the brake disc. On the basis of the different noise, the user of the brake is signalled that the friction lining 30 is worn out. Furthermore, the material admixture of lubricants and / or friction value modifiers is effected in such a way that the lining carrier 20 has an improved braking action compared to conventional steel carrier plates and generates less wear on the brake disc.FIG. 2 shows a brake lining 110 as a further exemplary embodiment of the invention, in which an indicator layer 140 is provided as an intermediate layer between the lining carrier 20 and the friction lining 30 according to the invention. The indicator layer 140 is formed within the scope of the sintering process for producing the brake lining 110 with the lining carrier 20 and the friction lining 30. This is thus a fully sintered brake lining in which no layers are subsequently welded, bonded or the like.The brake lining is pressed in three steps and subsequently tempered, for example at a temperature >800 °C in an atmosphere containing inert gas.The material composition of the indicator layer 140 is selected such that, upon contact with the brake disk, it generates an indicator noise that differs from a braking noise of the friction lining and is signaled to the user of the brake on the basis of the different noise such that the friction lining 30 is worn out. In addition, the material composition of the indicator layer 140 is selected such that it has a coefficient of friction which is smaller than the coefficient of friction of the friction lining, but is sufficiently large to ensure sufficient braking safety.As can be seen from the illustration of FIG. 2, the lining carrier 20 can be constructed in a somewhat elevated manner in order to provide a base 28 (made of lining carrier material) as the basis for the indicator layer 140. Alternatively, the indicator layer can be built up directly on the carrier section 22 of the lining carrier 20.FIG. 3 shows a brake lining 210 as a third exemplary embodiment of the invention, in which an indicator structure 250 for generating an indicator noise is provided according to the invention.In the exemplary embodiment shown, a plurality of channels 252 running parallel to one another are provided at the same height in order to form the indicator structure 250 in the friction lining 230 distributed over the width thereof. The orientation of the channels can, as illustrated, run transversely (i.e. substantially at right angles) to the direction of rotation of the brake disc in the braking mode. Other orientations, such as at an angle to the direction of rotation of the brake disc, are also possible. The channels 252 may be formed, for example, by perforating the finish sintered friction lining.FIG. 4 shows the brake lining 210 of FIG. 3 in operation when the wear limit is reached in order to illustrate the mode of operation of the indicator structure 250.In operation, when the friction lining 230 has been worn until the indicator structure 250 is reached, the channels 252 are exposed, as shown in FIG. 4. During a braking process which then takes place, the brake disk no longer bears over its entire surface on a friction lining, but rather only on elevations or webs 254 present between the channels 252. As a result, the braking behavior and, associated therewith, the braking noise, change naturally, which now represents an indicator noise. This effect is enhanced by the presence of the voids between the protrusions 254, since these voids contribute to a frequency change of the brake noise.FIG. 5 shows a further exemplary embodiment of a brake lining 310 according to the invention having an indicator structure 350, in this exemplary embodiment the indicator structure 350 is formed by a wave-shaped transition between the friction lining 330 and the material of the lining carrier 20.For this purpose, the lining carrier is constructed in a raised manner, similar to the exemplary embodiment of FIG. 2, in order to form a base 328. The side of the base 328 facing away from the carrier portion 22 is formed (for example during the pressing process) with a wave-shaped relief surface. In the exemplary embodiment shown, wave troughs 352 run substantially transversely to a rotational direction of the brake disc in the braking mode. The friction lining 330 inserts itself into the predetermined wave structure during the further construction of the sintered layers. The wave structure can of course alternatively also be formed without a base 328 directly in the carrier section 22 of the lining carrier 20 (this also applies to the exemplary embodiment described in connection with FIG. six and also all other possibilities of configuring an indicator structure).Similarly as shown in FIG. 4, when the friction lining 330 wears, peaks 354 of the shaft structure 350 are exposed when the wear limit is reached, so that the brake disc is increasingly in contact with the material of the lining carrier or the lining carrier base 328 and is increasingly in contact with the material of the friction lining 330 during the braking process. This change in the effective friction material is accompanied, as described above, by an increasing change in the indicator noise. The lining carrier material can be composed as described above in connection with the exemplary embodiment of FIG. 1.FIG. 6 shows an exemplary embodiment of a brake pad 410 similar to FIG. 5 with a likewise wave-shaped indicator structure 450 made of alternating wave valleys 452 and wave peaks 454. In contrast to the exemplary embodiment of FIG. 5, an indicator layer 440 is now introduced between the base 428 of the lining carrier 20 and the friction lining 430 as an intermediate layer. The indicator layer 440 simulates the wave structure both with respect to the lining carrier 20 or the base 428 and also has the analogous wave structure with wave valleys 442 and wave peaks 444 with respect to the layer of the friction lining 430 lying above it.In the braking mode, upon reaching the wear limit, the friction lining 430 is worn until the wave crests 444 of the indicator layer 440 are exposed. During the braking process, the brake disk is thus increasingly in contact with the material of the indicator layer 440 and is increasingly in contact with the material of the friction lining 430. This change in the effective friction material is accompanied, as described above in connection with the exemplary embodiment of FIG. 5, by an increasing change in the indicator noise. The material of the indicator layer can be composed as described above in connection with the exemplary embodiment of FIG. 2.As brake wear continues, peaks 454 of the lining carrier material are exposed from a given time, which is accompanied by a new change in the effective friction material. The materials of the indicator layer and of the coating carrier can be selected in such a way that different indicator noises are produced. With such a configuration, a two-stage wear warning can thus be generated to the user.Further possible embodiments will be readily apparent to the skilled person. Thus, the indicator structures can also have different geometric configurations than those shown and explained here. For example, in a modification of the regular wave structure shown, other wave structures with wave peaks of different heights can be selected in order to generate two- or multi-stage wear warnings with different indicator noises in this way. Alternatively, zigzag structures (saw-tooth) or the like may be adopted. Other types of hollow spaces, such as enclosed circular or ring-like hollow spaces, are also possible. The cavities can also be filled with indicator layer material, for example.As described above, a plurality of combinations of the basic aspects of the invention are possible (material selection of the lining carrier, material selection of the friction lining, material selection of the indicator layer, provision of indicator structures in the friction lining, provision of indicator structures in the transition between friction lining and lining carrier, provision of indicator structures in the transition between lining carrier and indicator layer and / or in the transition between indicator layer and friction lining, filling cavities of the indicator structure with indicator layer material).The invention combines sustainability with certainty. By generating an indicator noise according to the invention, the user is informed efficiently and early about the reaching of the wear limit. At the same time, it can brake further reliably without relevant safety restriction with a somewhat reduced coefficient of friction on account of the admixture according to the invention to the material of the lining carrier or of the indicator layer. The invention provides the possibility of a two- or multi-stage acoustic warning.List of reference characters10 Brake pad 20 Pad carrier 22 Carrier portion 24 Attachment portion 26 Through bore 28 Socket 30 Friction pad 32 Friction surface 110 Brake pad 140 Indicator layer 210 Brake pad 230 Friction pad 250 Indicator structure 252 Channels 254 Protrusions 310 Brake pad 328 Socket 330 Friction pad 350 Indicator structure 352 Wave valleys 354 Wave peaks 410 Brake pad 430 Friction pad 440 Indicator layer 442 Wave valleys 444 Wave peaks 450 Indicator structure 452 Wave valleys 454 Wave peaksReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE-AS 1 214 409

[0002] DE-OS 1 555 973

[0002] DE 103 47 409 B4

[0002]

Claims

Fully sintered multilayer brake lining (10; 110; 210; 310; 410; 510) having at least one first layer, which forms a lining carrier (20) and comprises ferrous material, and a second layer, which forms a friction lining (30; 230; 330; 430) and is formed on the lining carrier (20) in a powder sintering process, and having at least one acoustic wear indicator, which is designed to generate an indicator noise which differs from a braking noise of the friction lining (30; 230; 330; 430) when a wear limit of the friction lining (30; 230; 330; 430) is reached during braking operation.Brake pad (10; 110; 210; 310; 410; 510) according to claim 1, wherein the wear indicator is formed by adding lubricants and / or friction modifiers to the ferrous material of the pad carrier (20).Brake pad (10; 110; 210; 310; 410; 510) according to Claim 1 or 2, in which the wear indicator is formed by a sintered indicator layer (140; 440) arranged between the pad carrier (20) and the friction pad (30; 230; 330; 430).Brake pad (10; 110; 210; 310; 410; 510) according to one of Claims 1 to 3, in which the wear indicator is formed by an indicator structure (250; 350; 450) between the pad carrier (20) and the friction lining (30; 230; 330; 430).Brake pad (10; 110; 210; 310; 410; 510) according to claim 3, wherein the wear indicator is formed by an indicator structure (250; 350; 450) defining the wear limit.Brake pad (10; 110; 210; 310; 410; 510) according to Claim 4 or 5, the indicator structure (250; 350; 450) of which is formed in such a way that the indicator noise is generated by a geometric configuration in the friction pad (30; 230; 330; 430) or between the pad carrier (20) and the friction pad (30; 230; 330; 430) or between the pad carrier (20) and the indicator layer (140; 440) or between the friction pad (30; 230; 330; 430) and the indicator layer (140; 440) with corresponding relief surfaces, such as corrugations (352, 354; 452, 454), zigzag structures or the like, or with hollow spaces, such as perforations, channels (252) or the like.Brake pad (10; 110; 210; 310; 410; 510) according to claim 3, the indicator layer (140; 440) of which is formed by adding lubricants and / or friction value modifiers to the ferrous material of the pad carrier (20).Brake pad (10; 110; 210; 310; 410; 510) according to Claim 2 or 7, in which the lubricants are selected from the group comprising, in particular, graphites, fluorides (e.g. CaF2, BaF2, LiF, MgF2), soft metals (e.g. copper, tin, zinc), metal sulfides (e.g. MnS, MoS 2, WS 2) and hexagonal boron nitride, or the friction value modifiers from the group comprising, in particular, oxides (e.g. Al 2 O 3, MgO, ZrO 2, SiO 2 and compounds thereof), The following are examples of the group consisting of silicates (e.g. zirconium silicate, aluminum silicate, mica, feldspar, potassium silicate and compounds thereof), titanates (e.g. CaMgTiO 2), intermetallic phases (e.g. FeCr, FeV, FeW, FeMo, FeMn), carbides (e.g. WC, MoC, FeC, NbC) and nitrides (e.g. FeN, Mo 2 N, Si 3 N 4).Brake pad (10; 110; 210; 310; 410; 510) according to one of Claims 6 to 8, in which cavities of the indicator structure (250; 350; 450) are filled with an indicator layer material.Brake pad (110; 210; 310; 410; 510) according to one of Claims 3 to 9, in which the pad carrier (20) and the friction pad (30; 230; 330; 430) are formed from the same materials.

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