Friction brake element, in particular disc brake, and method for producing same

Abstract

The invention relates to a friction brake element (1), in particular a disc brake, for friction braking a motor vehicle, comprising friction rings (2, 3) having braking portions (4, 5) on the outer faces (6, 7) thereof, a cooling portion (8) between the inner faces (9, 10) of two friction rings (2, 3), and a securing portion (11), the friction brake body being produced at least partly using forming techniques.

Description

[0001] Friction brake bodies, in particular disc brakes and manufacturing methods therefor

[0002] The invention relates to a friction brake body, in particular a disc brake, and a manufacturing method for it.

[0003] One-piece cast iron brake discs for motor vehicles, cast in one piece in sand molds and then machined to a finished state of the art, are currently state of the art. Such cast iron brake discs are generally fitted to the front and rear axles of passenger cars. In the motorcycle sector, stainless steel brake discs are common, which are assembled by laser cutting and subsequent bolting. In the high-performance segment, such as in the sports sector, ceramic and carbon disc brakes are well-known. In specific cases, coated cast iron brake discs are available. The coating, for example, a tungsten carbide coating, increases performance.

[0004] It is known that at least the friction contact surfaces of disc brakes can also be manufactured from metals containing chromium iron to improve corrosion resistance.

[0005] WO 2020 / 173756 describes a friction brake body for a friction brake of a motor vehicle with a wear-resistant layer on a friction contact surface of a base body made of grey cast iron, wherein the wear-resistant layer comprises, in addition to the ferrous material, at least two elements from the group consisting of chromium, molybdenum, vanadium and aluminium.

[0006] The task is to create a friction brake body, in particular a disc brake, and a method for manufacturing it, in order to improve its service life, especially when the friction brake body is used less mechanically due to new drive technologies.

[0007] The problem is solved by independent device and method claims. Further embodiments are described in the dependent claims. A friction brake body, in particular a disc brake, for friction braking of a motor vehicle is described, comprising friction rings with brake sections on their outer surfaces and a mounting section, wherein the friction brake body is at least partially manufactured by forming. Friction brake bodies manufactured by forming have the advantages that they can be produced cost-effectively in large volumes and that higher-strength steels, in particular corrosion-resistant steels, can also be used to achieve the required strength for mechanical friction brakes. Higher-strength steels have a yield strength above 550 MPa.The fastening section is the area where the brake body is positively connected to the wheel of the vehicle by means of a threaded screw connection and also frictionally connected by the frictional force in the thread.

[0008] It is understood that the friction brake body as well as the individual friction ring can be manufactured in one piece or in multiple pieces. The terms "one-piece" and "single-piece" are to be understood as synonyms.

[0009] In order to be able to subject a friction brake body to higher braking forces and to achieve a lightweight construction, the friction brake body has two friction rings with a cooling section between the inner surfaces of the two friction rings.

[0010] To design the friction brake body as light as possible with a long service life while conserving resources in terms of material and manufacturing capacity, the mounting section is generally formed by deep drawing in a cold forming process, particularly with the aid of temperature control, onto a friction ring, preferably a cooling element, where the cooling element can be provided for forming the cooling section. If the manufacturing process makes temperature control more economical or necessary, this method should be included.

[0011] A friction brake body is described here in which at least the friction rings, or in particular the brake sections, essentially comprise steel with in particular less than 2% carbon content, more preferably stainless steel, even more preferably rust-free stainless steel, and most preferably a chromium-iron alloy with a chromium content of more than 10.5%, in particular in the martensitic and / or austenitic and / or ferritic dissolved solid solution.

[0012] This offers several advantages. Steel friction rings or brake sections are easily machined using forming techniques. This allows for weight savings, and stainless steel results in a longer service life. Chromium-iron alloys with a chromium content of more than 10.5% are essentially corrosion-free and therefore have a significantly longer service life than friction rings made from conventional gray cast iron. Gray cast iron alloys have a carbon content ranging from 2% to 6.67%. Such friction brake components can be used very effectively in vehicles with new electric drive technologies. Due to high electromechanical recuperation performance, which can lead to adjustable, strong deceleration, electric vehicles have a significantly reduced need for mechanically generated friction braking power.In these types of electric vehicles, things have gone so far that rear axle brake discs are hardly ever used anymore. Drum brakes are therefore also installed on the rear axle. A drum brake generally has lower braking performance than a disc brake and therefore also disadvantages. Coated brake discs do have a somewhat longer lifespan. However, gray cast iron is very unsuitable for coating, or rather, coating is only possible under difficult conditions. The material layers could be undermined and flake off locally, so that problems with reproducibility can arise in the long term. Since rear axle brake discs are hardly ever used in new electric drives, abrasive wear is significantly reduced.Instead, disc brakes corrode more due to everyday disuse, meaning that conventional cast iron brake discs have to be replaced well before the usual wear limit.

[0013] In contrast, friction rings with a high chromium content of over 10.5% are significantly more corrosion-resistant or even completely corrosion-free. Such chromium-iron alloys are generally referred to as stainless steel and have material numbers such as 1.4301, 1.4305, or 1.4401, etc. A further advantage of using higher-strength steels with a higher chromium content is that harder brake pads produce significantly fewer fine dust particles compared to softer brake pads for the relatively soft gray cast iron, which leads to high abrasive wear and a high proportion of fine dust particles.

[0014] To improve corrosion resistance and achieve further favorable mechanical properties, the chromium-iron alloy of the friction brake body includes additional or substitute alloying elements from the group consisting of nickel, molybdenum, manganese, aluminum, vanadium and niobium, in particular according to the specification of steel 1.4021 or, preferably, comparable alloys.

[0015] For example, increasing the nickel content can lead to a reduction in the chromium content, further improving corrosion resistance and mechanical properties. Chromium is more commonly used than nickel for cost reasons.

[0016] Since high mechanical loads are placed on the friction brake body in motor vehicles, especially those with more than two wheels, simply cut friction rings are generally unsuitable and require a cooling section. Furthermore, the friction brake body must possess sufficient heat capacity to remain below a maximum temperature of 700 °C. Additionally, the thermal conductivity of chromium-iron alloys is lower than that of gray cast iron.

[0017] To simplify manufacturing, prevent corrosion, facilitate recycling, and maximize service life, the mounting section of the friction brake body, and especially the cooling section, are made of the same material as the friction rings. For manufacturing simplification, the material thickness can be the same. To achieve weight savings and lightweight construction, different materials with varying thicknesses can be used within the friction brake body.

[0018] In order to produce small series of friction brake bodies cost-effectively, the fastening section can be arranged on the friction brake body by means of positive and / or force-fit connections, preferably forming connections, preferably clinching, riveting or especially screw connections.

[0019] To attach the friction brake body to the wheel of a motor vehicle using screws, axially and radially symmetrically offset bores are arranged on the mounting section.

[0020] According to a further embodiment, the cooling section can be designed as an intermediate element by means of spacer elements, in particular cylindrical spacer elements, which can be arranged mechanically, in particular by positive and / or force-fit, between the friction rings. In particular, the friction rings can have indentations or countersunk holes with countersunk screws distributed around their outer surfaces, which can positively connect the friction rings to the spacer elements with threaded holes on their end faces. It is understood that other positive-fit connections can also be achieved by other distributions of external and internal threads. For example, the spacer elements could already have external threads at their ends, which can be screwed into threaded holes in the friction rings.

[0021] This allows a friction brake body to be manufactured cost-effectively in small quantities.

[0022] To produce larger quantities cost-effectively and resource-efficiently with regard to both assembly effort and manufacturing, the cooling section can comprise an intermediate element, preferably a single piece, which has circumferentially offset, corrugated webs, wherein the webs are corrugated inversely to the adjacent webs, wherein in particular the fastening section on the intermediate element is formed, preferably in the form of a cup, wherein the friction rings more preferably have a flange, so that the friction rings with their flanges and the intermediate element with the fastening section cup can be slid into one another or pressed together by means of cold joining, in particular, preferably by means of a temperature control process, and can be positively secured by means of radial bores and screws or bolts arranged therein, in particular by mechanical connections, more preferably by embossing.

[0023] Depending on the embodiment, the webs on the intermediate element have waves, with the following web having exactly an inverse wave to the adjacent web.

[0024] A method for manufacturing a friction brake element, in particular a disc brake, for friction braking of a motor vehicle is described, comprising friction rings with braking sections on their outer surfaces, a cooling section between the inner surfaces of two friction rings, and a mounting section, wherein the friction brake element is at least partially manufactured by forming. Thus, higher-strength steels could also be used as friction brake elements.

[0025] The process is described below, in particular with the features described above, wherein at least the friction rings, or in particular the brake sections, are made essentially of steel with less than 2% carbon content, more preferably of stainless steel, even more preferably of rust-free stainless steel, particularly preferably of a chromium-iron alloy with a proportion of more than 10.5% chromium in the martensitic, austenitic and / or ferritic dissolved solid solution, or in particular as unalloyed or low-alloy steels are subsequently enhanced by coating or treatment, in particular equivalent to nitriding, wherein in particular the friction rings with the mounting section are preferably produced by separating, or cutting and forming techniques from the group of deep drawing by means of cold forming, in particular by means of tempering and / or particularly preferably by powder metallurgy processes.The powder metallurgy process could be called "sintering" if the pressed green compact is subjected to heat treatment.

[0026] The manufacturing process creates a corrosion-resistant friction brake body that, due to separation processes such as cutting and forming techniques such as deep drawing, can be reproduced very cost-effectively in high volumes. To cost-effectively produce higher-strength steels in this special chromium-iron alloy with specific geometries, it can be advantageous to manufacture them using powder metallurgy processes such as sintering.

[0027] The above-described method for manufacturing a friction brake body can be further developed as follows, wherein the cooling section is produced by means of cylindrical spacer elements as intermediate elements, which can be mechanically, in particular by form-fit and / or force-fit, embossed between the friction rings, or, for example, in particular by means of countersunk holes in the friction rings into which countersunk screws are screwed into end-face threaded holes in the spacer elements. This manufacturing method is advantageous for small production runs of the friction brake body, as expensive deep-drawing tools or other expensive forming processes can be avoided.

[0028] According to an alternative, further method for very high production volumes, the method for manufacturing the friction brake body described above can be further developed by manufacturing the cooling section from an intermediate element, in particular in one piece, which can particularly preferably be manufactured with circumferentially offset, corrugated webs, wherein in particular the webs can be corrugated alternately in the opposite direction to the respective adjacent web, wherein in particular the mounting section, preferably in the form of a cup, can be formed on the intermediate element, wherein the friction rings can further preferably be manufactured with a flange, so that the friction rings with their flanges and the intermediate element with a cup with mounting section can be cold-formed or preferably by means of a tempering process.can be pushed or, in particular, pressed into one another and can be positively secured by means of radial bores in the flanges and the fastening section plug and screws or bolts arranged therein.

[0029] It is understood that the intermediate element may preferably have a rectangular, polygonal or triangular profile or any other known profile shape that can achieve a cooling function, instead of a wave structure.

[0030] Thus, the problem is solved by a compact friction brake body or a manufacturing process resulting in a highly corrosion-resistant friction brake body. Due to its specific application in electric motor drive trains of motor vehicles with high recuperation motor outputs, this can be used very effectively with a long service life and low maintenance requirements.

[0031] The invention will be explained in more detail below with reference to exemplary embodiments and the drawings. The drawings show:

[0032] Fig. 1 shows a perspective view from the front of a friction brake body according to a first

[0033] embodiment,

[0034] Fig. 2 shows a perspective view from the rear of the friction brake body according to Fig. 1.

[0035] Fig. 3 shows a first perspective exploded view of the friction brake body according to Fig. 1.

[0036] Fig. 4 shows a second perspective exploded view of the friction brake body according to Fig. 2;

[0037] Fig. 5 shows a perspective view from the front of a friction brake body according to a second

[0038] embodiment,

[0039] Fig. 6 shows a perspective view from the rear of a friction brake body according to Fig. 5.

[0040] Fig. 7 shows a first perspective exploded view of the friction brake body according to Fig. 5 and

[0041] Fig. 8 shows a second perspective exploded view of the friction brake body according to Fig. 6.

[0042] Figures 1 to 8 show a friction brake body 1 in the form of a disc brake for friction braking of a motor vehicle. The friction brake body 1 comprises two friction rings 2, 3 with braking sections 4, 5 on the outer surfaces 6, 7. A cooling section 8 is arranged between the friction rings 2, 3, i.e., between the inner surfaces 9, 10 of the two friction rings 2, 3. The friction brake body 1 is mounted to the wheel of the vehicle by means of a mounting section 11. For this purpose, the mounting section 11 has, for example as shown in Figures 1, 3 and 5, five axial bores 31 arranged symmetrically to each other around a core hole with an axis of rotation 30.

[0043] In a very simple embodiment not shown, the brake sections 4, 5 are essentially formed with a chromium-iron alloy with a proportion of more than 10.5% chromium in the austenitic or ferritic dissolved solid solution on the outer surfaces 6, 7 of the friction rings 2, 3.

[0044] Preferably, the friction rings 2, 3 are made entirely of such a chromium-iron alloy with a chromium content of more than 10.5% in the austenitic or ferritic dissolved solid solution. This significantly extends the service life compared to conventional gray cast iron friction rings, even though the friction brake elements are used considerably less frequently due to their installation in vehicles powered by electric motors. The recuperation rate is very high in electric vehicles, as the vehicle is decelerated by recuperation, i.e., by the magnetic field of a generator, and thus a conventional friction brake is not needed, or only rarely required, for assistance during sudden and significant braking maneuvers with high braking loads.

[0045] The chromium-iron alloy of the friction brake body can include additional or substitute alloying elements from the group consisting of nickel, molybdenum, vanadium, aluminum, manganese, and niobium. In the friction brake body 1, both the mounting section 11 and the cooling section 8 can be made of the same material as the friction rings. This should prevent contact corrosion due to different materials and result in a more uniform service life for all components.

[0046] The mounting section 11 is generally cold-formed. The mounting section 11 is formed in one piece from the friction ring 2 by deep drawing, preferably supported by a tempering process. The mounting section 11 forms a shape similar to a cup 16 on the friction ring 2.

[0047] Figures 1, 2, 3, and 4 show the friction brake body 1 with a cooling section 8 formed by means of cylindrical spacer elements 12. The cooling section 8 provides air cooling between the two friction brake bodies 2 and 3. The spacer elements 12 conduct the heat. The spacer elements 12 mechanically connect the two friction rings 2 and 3, in particular by means of a positive fit. The spacer elements 12 are positively connected to the friction rings 2 and 3 by means of threaded screws and threaded holes. The threaded screws can be located at the ends of the spacer elements 12 and can also be threaded holes extending over the entire surface of the friction rings 2 and 3.

[0048] Figures 3 and 4 show the first described embodiment with threads at the ends of the spacer elements 12 and internal threads in the friction rings 2, 3, each in an exploded view from the front and back. In the radial direction, two cylindrical spacer elements are always spaced apart one behind the other and then each offset by, for example, 12° rotationally around the axis of rotation 30, so that a total of, for example, 30 spacer elements are provided for each circumferential radius, i.e., a total of 60 spacer elements for two circumferential radii.

[0049] Alternatively, according to an embodiment not shown, the friction rings can have countersunk bores distributed around their circumference on their outer sides, into which countersunk screws can be screwed by being positively inserted into threaded bores on the end faces of spacer elements 12.

[0050] Figures 5 to 8 show a friction brake body 1 in which the mounting section 11 is formed on an intermediate element 17. The mounting section is, as shown in the figures, in the form of a pot 16. The intermediate element 17 forms a cooling section 8 between the friction rings 2, 3.

[0051] The intermediate element 17 comprises, around its entire circumference and at the outer edge of the pot 16, freely projecting, offset, alternately corrugated webs 18, 19, wherein one web is corrugated inversely to the adjacent web, so that every second adjacent web 18, 19 has the same corrugation. This corrugation creates a cooling gap between the friction rings 2, 3 when these are slid into one another over flanges 20, 21, as shown in Figures 7, 8, or, in particular, pressed into one another by means of a heat process. The height of the corrugated section that creates the cooling gap in the cooling section 8 depends on the cooling requirements and is designed for the specific application.

[0052] Radial bores 22, 23, 24 in the flanges 20, 21 and in the pot 16 serve to accommodate screws 25 or bolts, so that the friction brake body can be positively secured in the axial direction and the friction rings 2, 3 with the intermediate element 17 in between are secured in the axial direction.

[0053] Figures 3, 4, 7, and 8 show, by means of exploded views, process steps for manufacturing a friction element 1 as described above. Preferably, the friction rings 2, 3 and the intermediate element 17 with the mounting section 11 in the form of a cup 16 are formed on the friction ring 2, 3 or the intermediate element 17, depending on the embodiment. They are preferably manufactured by separating or cutting and forming techniques, such as deep drawing from the correspondingly preferably higher-strength iron-chromium alloy, optionally and preferably with the application of tempering.

[0054] Alternatively, these parts and elements are manufactured using a powder metallurgical process, e.g. sintering.

[0055] Figures 3 and 4 show exploded views of the process steps for the mechanical manufacture of the cooling section 8 using cylindrical spacer elements 12. These cylindrical spacer elements either have external threads that can be screwed into the friction rings 2, 3, or countersunk screws are screwed into countersunk holes in the friction rings 2, 3 at their ends. Figures 7 and 8 show how the intermediate element 17 was manufactured circumferentially with stepped and alternately inverted corrugated webs 18, 19 by deep drawing. The mounting section 11, in the form of the cup 16, was produced by deep drawing. Flanges 20, 21 on the friction rings 2, 3 are manufactured by deep drawing, cold and / or hot forming, or by powder metallurgy. The radial bores 22, 23, 24 are preferably produced by machining.It is understood that the bores can also be threaded bores to accommodate screws 25 instead of bolts. The friction rings 2, 3 and the intermediate element 17 are thus axially secured by means of the screws or bolts 25.

[0056] This results in a friction ring with a long, corrosion-free service life. It can be efficiently reproduced in either small or large quantities.

[0057] The previously described variants of the system, method, and devices serve only to improve understanding of the structure, function, and properties of the presented solution; they do not limit the disclosure to the exemplary embodiments. The figures are schematic, with essential properties and effects shown, in some cases significantly enlarged, to clarify the functions, operating principles, technical configurations, and features. Each function, principle, technical configuration, and feature disclosed in the figures or in the text can be freely and arbitrarily combined with all claims, features in the text and in the other figures, other functions, principles, technical configurations, and features contained in or resulting from this disclosure, so that all conceivable combinations can be attributed to the described solution.This also includes combinations between all individual descriptions in the text, i.e., in each section of the description, in the claims, and also combinations between different variants in the text, in the claims and in the figures.

[0058] The system, device, and process details described above are presented together; however, it should be noted that they are also independent of one another and can be freely combined. The relationships of the individual parts and sections shown in the figures, as well as their dimensions and proportions, are not to be understood as restrictive. Rather, individual dimensions and proportions may deviate from those shown.

[0059] The claims do not limit the disclosure and thus the possible combinations of all the identified features. All identified features are explicitly disclosed here, both individually and in combination with all other features.

[0060] All figures are merely schematic representations not to scale. For further details, please refer to the accompanying drawings. REFERENCE SYMBOL LIST

[0061] 1 friction brake body

[0062] 2 friction rings

[0063] 3 friction ring

[0064] 4 Braking section

[0065] 5 braking sections

[0066] 6 Outside

[0067] 7 Outside

[0068] 8 Cooling section

[0069] 9 Inside

[0070] 10 Inside

[0071] 11 Fastening section

[0072] 12 spacer elements

[0073] 16 pots

[0074] 17 Intermediate element

[0075] 18 Bridge

[0076] 19 Bridge

[0077] 20 flange

[0078] 21 Flange

[0079] 22 bore

[0080] 23 bore

[0081] 24 bore

[0082] 25 screws / bolts

[0083] 30 Rotation axis

[0084] 31 bore

Claims

PATENT CLAIMS 1. Friction brake body (1), in particular disc brake, for friction braking of a motor vehicle with at least one friction ring (2, 3) with brake sections (4, 5) on outer surfaces (6, 7), and with a mounting section (11), wherein the friction brake body is at least partially manufactured by forming.

2. Friction brake body according to claim 1, wherein the friction brake body has two friction rings (2, 3) with a cooling section (8) between the inner surfaces (9, 10) of the two friction rings.

3. Friction brake body according to claim 1 or 2, wherein the fastening section (11) is formed on a friction ring (2, 3), more preferably on an intermediate element (12, 17), by means of deep drawing, in particular supported by tempering, wherein the intermediate element (12, 17) is provided for forming the cooling section (8).

4. Friction brake body according to one of claims 1, 2 or 3, wherein at least the friction rings (2, 3), or in particular the brake sections (4, 5), comprise steel with in particular less than 2% carbon content, more preferably stainless steel, even more preferably rust-free stainless steel, and most preferably essentially a chromium-iron alloy with a chromium content of more than 10.5%, in particular in the martensitic or austenitic or ferritic dissolved solid solution.

5. Friction brake body according to one of claims 1 to 4, wherein the fastening section and in particular the cooling section are made of the same material as the friction rings or, more preferably, of different materials, wherein the material thickness is the same, or more preferably, different.

6. Friction brake body according to one of claims 1 to 5, wherein the fastening section is arranged on the friction brake body by means of positive and / or force-fit connections, preferably forming connections, preferably by means of clinching, riveting or in particular screw connections.

7. Friction brake body according to one of claims 1 to 6, wherein the cooling section (8) is designed as an intermediate element by means of spacer elements (12), in particular cylindrical spacer elements (12), which are arranged mechanically, in particular by positive and / or force-fit connection between the friction rings, wherein in particular the friction rings have indentations or countersunk bores with countersunk screws distributed around their outer surfaces, which connect the friction rings to the spacer elements in a form-fit connection at the end face.

8. Friction brake body according to one of claims 1 to 7, wherein the cooling section (8) comprises an intermediate element (17), in particular a one-piece element, which in particular has circumferentially offset, alternately inverted corrugated webs (18, 19), wherein in particular the fastening section on the intermediate element is formed, preferably in the form of a cup (16), wherein the friction rings (2, 3) more preferably have a flange, so that the friction rings with their flanges (20, 21) and the intermediate element (17) can be slid into one another with the cup (16) for the fastening section (11) or can be pressed into one another by means of cold joining, in particular, preferably by means of a temperature control process, and can be positively secured by means of radial bores (22, 23, 24) and screws (25) or bolts arranged therein, in particular by mechanical connections, more preferably by embossing.

9. Method for manufacturing a friction brake body, in particular a disc brake, for friction braking of a motor vehicle with friction rings having brake sections on their outer sides, a cooling section between the inner sides of two friction rings and with a mounting section, wherein at least the friction rings, or in particular the brake sections, wherein the friction brake body is manufactured at least partially by forming.

10. Method for manufacturing a friction brake body, in particular according to claim 9, wherein the friction brake body is essentially made of steel with less than 2% carbon content, more preferably of stainless steel, even more preferably of rust-free stainless steel, particularly preferably of a chromium-iron alloy with a chromium content of more than 10.5%, in particular in the martensitic, austenitic and / or ferritic dissolved solid solution, or in particular as unalloyed or low-alloy steels are subsequently enhanced by coating or treatment, in particular equivalent to nitriding, wherein in particular the friction rings with the mounting section are preferably manufactured by separation techniques, such as cutting and forming techniques from the group of deep drawing, in particular by tempering and / or particularly preferably by powder metallurgical processes.

11. Method for manufacturing a friction brake body according to the previous claim, wherein the cooling section is manufactured by means of cylindrical spacer elements as an intermediate element, which are mechanically, in particular by form and / or force-fit, embossed between the friction rings or screwed into end-face threaded bores of the spacer elements by means of countersunk bores in the friction rings.

12. Method for manufacturing a friction brake body according to claim 10, wherein the cooling section is manufactured from an intermediate element, in particular in one piece, which is manufactured with circumferentially offset, alternately corrugated webs, wherein in particular the webs are corrugated alternately inversely to the respective adjacent web, wherein in particular the fastening section, preferably in the form of a cup, is formed on the intermediate element, wherein further preferably the friction rings are manufactured with a flange, so that the friction rings with their flanges and the intermediate element with the cup and the fastening section are cold-formed or preferably by means of a tempering process, are pushed into one another or, in particular, pressed together and are positively secured by means of radial bores in the flanges and the pot with the fastening section and screws or bolts arranged therein.

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