Internally ventilated rotor

Abstract

Internally ventilated rotor (1) comprising at least two disc elements (2) connected to one another via at least one cooling element (3), wherein the at least one cooling element (3) comprises a textile structure (4) which extends from a disc element contact area (31) of the cooling element (3), with which the cooling element (3) is in contact with a disc element (2), to another disc element contact area (32) of the cooling element (3), with which the cooling element (3) is in contact with another disc element (2), and wherein the textile structure (4) comprises parallel fibers, a plurality of parallel fibers extend from one disc element contact area (31) of the cooling element (3) into the other disc element contact area (32) of the cooling element (3), and the rotor (1) has at least two oppositely inclined cooling elements (3) or two oppositely inclined cooling element areas of the cooling element (3), and wherein the disc element contact areas (31, 32) extend in recesses of the two disc elements (2).

Description

[0001] The invention relates to an internally ventilated rotor which can serve in particular as a brake disc.

[0002] Internally ventilated brake discs primarily serve to decelerate a rotating body. The kinetic energy is converted into heat. To improve this dissipation, the aim is to rapidly release the heat to the environment. This occurs via forced convection in the internally ventilated area. Convection is directly dependent on the shape and surface area of the cooling elements present in the internally ventilated area and the cooling channels defined above them.

[0003] Connecting elements that allow air to flow around or through the friction rings of internally ventilated brake discs can be present, for example in the form of connecting ribs (DE 10 2010 007 474 A, US 3,623,579 A). The connecting ribs can be designed, for example, as a lattice-like supporting structure, as described in DE 195 37 392 A1.

[0004] However, they can also have completely different shapes. GB 2 543 020 A describes an internally ventilated brake disc that is conventionally cast from metal using a lost core made of sand and resin. The brake disc described therein comprises two friction rings that have a common axis of rotation and are spaced apart along this axis so that an air-filled gap exists. It also comprises a plurality of air guide vanes that extend outwards relative to this axis to direct cooling air through the air-filled gap. All of the air guide vanes are twisted along their outward extension. For certain air guide vane shapes, GB 2 543 020 A proposes producing lost cores using 3D printing.

[0005] GB 2 543 020 A makes it clear that there are great variations in the shape of the air guide vanes in conventional, cast, internally ventilated metal brake discs.

[0006] These do not exist with fiber-reinforced, internally ventilated, ceramic brake discs. To date, ceramic brake discs have been manufactured by molding a mixture of fibers, resin, and carbon-rich raw materials into a brake disc blank under pressure and temperature. This utilizes the properties of resins to harden upon increasing temperature. In a subsequent step, the blank is pyrolyzed. Furthermore, the fiber-reinforced carbon ring can be infiltrated with silicon, which changes, in particular, the mechanical and thermal properties. To meet the geometric requirements, mechanical processing steps are preferably performed. Some known manufacturing processes for fiber-reinforced ceramic brake discs are described in European Patent EP 2 334 945 B1, particularly in paragraphs 6 to 10.DE 601 15 964 T2 describes a molding tool and method for producing a self-ventilated brake pad. WO 2006 / 002471 A1 and GB 2 444 927 A also describe simply shaped connections of disc elements whose surfaces are substantially perpendicular to the disc elements.

[0007] Fiber-reinforced ceramic brake discs have so far had the disadvantage, due to production reasons, that intermediate elements, particularly in the form of cooling fins, are wide in relation to their height due to the limited formability of the starting material. Building on this, European Patent EP 2 334 945 B1 proposes a process that is intended to make it possible to design the shape of the cooling channels more economically and simply. The process comprises: (a) producing load discs, friction surfaces, and air guide elements of the disc rotor, each through separate processes using a carbon fiber-reinforced carbon-carbon composite material, (b) joining the load discs, friction surfaces, and air guide elements, each produced through separate processes, to form a single structure, and (c) performing a liquid silicon melt infiltration process on the joined structure. The material of the load discs and the air guide elements is always the same.

[0008] DE 196 51 798 A1 describes a friction unit, in particular a brake disc, having at least one friction surface, a friction body, and at least one molded body. The molded body is connected to the friction body in such a way that at least a portion of it forms a region of the friction surface, and the molded body has a higher thermal conductivity in the direction of the surface normal than the friction surface itself.

[0009] DE 10 2013 201 303 A1 describes an internally ventilated motor vehicle brake disc made of fiber composite material in which the cooling channels have a rectangular cross-section.

[0010] The present invention is based on the object of providing an internally ventilated rotor which enables the greatest possible braking performance while simultaneously minimizing the overall weight of the braking device.

[0011] This object is achieved by an internally ventilated rotor comprising at least two disc elements connected to one another via at least one cooling element, wherein the at least one cooling element has a textile structure which extends from a disc element contact region of the cooling element, with which the cooling element is in contact with one disc element, into another disc element contact region of the cooling element, with which the cooling element is in contact with another disc element, and wherein the textile structure comprises parallel fibers, a plurality of the parallel fibers extend from one disc element contact region of the cooling element into the other disc element contact region of the cooling element and the rotor has at least two oppositely inclined cooling elements or two oppositely inclined cooling element regions of the cooling element.

[0012] The number of cooling elements connecting the disc elements is not limited. The invention can be implemented with only one cooling element, e.g., if it is a cord-shaped cooling element, similar to Fig. 5, when this cooling element runs between the disc elements not in a circular fashion, but in a spiral fashion. A small number of cooling elements can also be present, for example, if the rotor already has support elements that connect the two disc elements in addition to the cooling elements. However, there can also be a large number of cooling elements, especially if they are cooling plates, as in Fig. 1 to 3 shown.

[0013] The textile structure comprises parallel fibers, and a plurality of the parallel fibers extend from one disc element contact area of the cooling element to the other disc element contact area of the cooling element. Any tensile load is then transferred directly from one disc element to the other disc element via the fiber(s). Fibers are considered to be parallel if they run at an angle of no more than 15° to each other at any point on the cooling element. Of course, one of several parallel fibers can run in a completely different direction at one point on the cooling element than another fiber of the parallel fibers at another point on the cooling element. For example, Fig. 5A, in which a plurality of parallel fibers, only a part of which is shown, run up and down together parallel to one another at every point of the cooling element.

[0014] When braking, a completely even distribution of the contact pressure between both brake pads is only ever achieved approximately. This is particularly true at the beginning of the braking process due to the different contact times of the brake pads. Higher contact pressure leads to greater friction and consequently to a greater reduction in rotational speed. A more heavily braked disc element tends to rotate more slowly than a less heavily braked disc element. As a result, torsional moments arise between the disc elements within the rotor, which must not lead to failure of the elements (cooling elements and, if applicable, additional support elements) that connect the differently decelerated disc elements. It has been found that the rotor according to the invention effectively counteracts failure by directly transferring tensile forces along the fiber direction from one disc element to the other disc element.Due to the tensile load in the fiber direction, the cooling elements can be realized with particularly fine detail, allowing the rotor to be constructed even lighter. This is especially true when fibers with particularly high tensile strength extend from one disc element contact area of the cooling element to the other disc element contact area. This results in even lighter and simultaneously highly resilient rotors.

[0015] Less delicate support elements, such as the air guide elements proposed for connecting the friction discs in European Patent No. 2,334,945, can exhibit greater rigidity than the cooling elements of the present invention. However, the same rotor rigidity can be achieved according to the invention by using a larger number of more delicate cooling elements or by using a more dense network of disc element contact areas on the disc elements. Since this simultaneously creates a particularly large cooling element surface, the invention achieves better dissipation of the heat generated during braking with the same rotor rigidity.

[0016] The textile structure is preferably a scrim or a woven fabric, and a multitude of parallel fibers extend from one disc element contact area of the cooling element to the other disc element contact area of the cooling element. This ensures that these parallel fibers are loaded in their main load direction, and their tensile strength is utilized to the greatest possible extent. The desired load capacity of the rotor is achieved with even more delicate cooling elements, thus with an even lower overall rotor weight.

[0017] However, the invention is not limited to embodiments in which the textile structure is a scrim or a woven fabric. The textile structure can also be a nonwoven, for example. This has thermal advantages, since fibers also run in the thickness direction of the cooling element, thus further improving the cooling effect. The combination of nonwovens with scrims and / or woven fabrics is conceivable. For example, in an area subject to less mechanical stress (e.g. near an already existing support element that connects the two disc elements in addition to the cooling elements), a cooling element can be present in which the textile structure is a nonwoven. In this case, heat dissipation is particularly improved there. Alternatively or additionally, in an area subject to greater mechanical stress (e.g.A cooling element can be used in this case (at a greater distance from an existing support element that connects the two disc elements in addition to the cooling elements), in which the textile structure is a scrim or a woven fabric. In this case, the mechanical load-bearing capacity (but also the thermal load-bearing capacity) is further increased. Threads, yarns, cords, knits, braids, and felt are also suitable as textile structures or as part of textile structures.

[0018] Layered composite cooling elements are also conceivable, comprising scrim and / or woven layers in combination with nonwoven layers. In order to counteract buckling of the cooling element, several spaced-apart layers of parallel fibers have proven advantageous, particularly when parallel fibers from both layers extend from one sliding element contact area into the other disc element contact area. This can be achieved, for example, with the help of cooling elements in the form of cooling plates in which two or more layers of parallel, unidirectional scrim, e.g. carbon fiber scrim, are kept at a distance with one or more support layers arranged between these layers. Preferably, the distance d between the furthest apart layers of parallel fibers of the cooling element is then more than a times 0.025, in particular more than a times 0.05, where a is the distance between the disc elements connected via the cooling element.

[0019] The textile structure and / or the parallel fibers can comprise carbon fibers, silicon carbide fibers, boron nitride fibers, or mixtures thereof. The skilled person selects the fibers depending on whether particularly pronounced mechanical and / or thermal stresses will occur where the fibers are to be used. They specifically utilize the different mechanical and thermal properties of the various fibers. Carbon fibers are particularly preferred because they exhibit high tensile strength at high temperatures while maintaining a low density. Due to their high temperature resistance, they remain in the semi-finished product throughout the entire production process, including siliconization.

[0020] The shape of the cooling element(s) is not restricted. In principle, any shape is conceivable. In certain embodiments of the rotor according to the invention, the at least one cooling element is a cooling plate. A targeted arrangement of cooling plates allows channels to be defined particularly easily. This allows the airflow to be controlled. Compared to more delicate cooling elements, such as cooling rods, a further advantage is that the fibers in the plates support each other.

[0021] The cooling elements can be curved. Along their length, the cooling elements can be twisted, as described in GB 2543020, since the prepregs used to manufacture the cooling elements can be shaped accordingly. The cooling elements (or their precursors, e.g., prepregs) can be formed into the desired shape and then cured.

[0022] The cooling elements preferably have a rough and / or textured surface. This promotes the formation of turbulent flows; consequently, the heat generated from the rotor during braking is dissipated more efficiently.

[0023] The invention encompasses rotor configurations with large or small cooling elements. However, smaller, more delicate cooling elements are preferred, as they achieve even more efficient heat dissipation. Preferably, the ratio of the cooling surface A of the cooling element, e.g., the cooling plate, facing the interior of the brake disc to the volume V of the section of the cooling element, e.g., the cooling plate, facing the interior of the brake disc is at least 0.25 mm. -1 , in particular at least 0.4 mm -1 , particularly preferably at least 0.6 mm -1 , e.g. at least 0.8 mm -1. Therefore, only those cooling element surfaces and those cooling element volume areas that face the interior are included in the calculation of this ratio. Areas located within a disc element are not taken into account when calculating both the cooling surface A and the volume V, because the cooling element extends into an area located within a disc element. Ultimately, adhering to the ratio specified here results in heat transfer being further increased while maintaining the same mass. This, in turn, opens up the possibility of scaling down the overall size of the rotor, so that the same braking performance can be achieved with a smaller and lighter braking system.

[0024] It is preferred if the cooling element or elements are inclined. In this case, it / they do not run orthogonally to the surfaces of the disc elements. Preferably, the cooling element runs at an angle of less than 89°, in particular less than 80°, e.g. less than 70°, at least at one point which lies between two adjacent disc elements and is equidistant from these two disc elements. The angle is preferably more than 20°, in particular more than 30°, e.g. more than 35°. The person skilled in the art selects this angle depending, among other things, on the coefficient of friction. With very low coefficients of friction, the disc elements are primarily pressed together by the contact pressure of the brake shoes. At the same time, the torsional moment acting between the disc elements when the contact pressure of the two brake shoes is uneven is relatively low. In this case, the person skilled in the art would select an angle in the upper range.With very high friction coefficients, the disc elements are compressed less strongly by the contact pressure of the brake shoes for the same braking performance. Generally, the torsional moment is then greater when the contact pressure of the two brake shoes is uneven. A specialist would then choose an angle in the lower range. This ensures that the main fiber direction during braking runs more frequently along the effective force direction resulting from the torsional moments and contact forces.

[0025] The rotor has at least two cooling elements inclined in opposite directions, e.g. cooling plates, or two cooling element regions of a cooling element inclined in opposite directions. In the context of the present invention, oppositely inclined means that one of the two cooling elements or one of the two cooling element regions would be stretched overall and the other cooling element or the other cooling element region would be compressed overall if one of the two disk elements were rotated relative to the other disk element about the common axis of rotation of both disk elements in the sense of the torsional moment described above. Regardless of which side of the rotor according to the invention a brake pad is pressed against more strongly, at least one of the cooling elements always counteracts failure of the rotor by subjecting it (and preferably its fibers) to tensile stress. This leads to stiffening of the rotor.If the cooling elements are not tilted relative to each other, they have less resistance to the rotation of one disc element relative to the other around the common rotation axis of both disc elements. This is because the rotation would then not necessarily lead to a tensile load in one of the cooling elements (due to a parallelogram effect). To achieve a predefined braking performance, a rotor according to the invention with tilted cooling elements can therefore be designed with even lower material consumption, making the entire braking system lighter.

[0026] The effect described above is achieved particularly well when the oppositely inclined cooling elements or cooling element areas are arranged close to one another in the rotor.

[0027] Thus, preferred rotors according to the invention have at least one pair of adjacent cooling elements, e.g., cooling plates. Orthogonal projections of the four disk element contact areas onto the respective inner surface of the disk element in contact with the respective disk element contact area define four projection surfaces. Four points located within the projection surfaces define the corners of a trapezoid. If, therefore, a point can be defined in each of the four projection surfaces such that the four points define a trapezoid, a preferred rotor according to the invention is present in this sense.

[0028] The invention also encompasses rotors according to the invention in which one or more cooling elements extend back and forth between the disk elements. Such a cooling element has many disk element contact regions along the cooling element, with which the cooling element is in alternating contact with one and the other disk element. Thus, the at least one cooling element can have at least three disk element contact regions, wherein at least two disk element contact regions are in contact with one disk element and a disk element contact region lying along the cooling element between these disk element contact regions is in contact with the other disk element. The textile structure extends through the disk element contact region, which lies along the cooling element between the other disk element contact regions.Preferably, the textile structure then extends from the first disc element contact area across a plurality of further disc element contact areas into the last disc element contact area. Preferably, the textile structure is then a fiber bundle, e.g., a carbon fiber bundle. The fibers extending through multiple disc element contact areas impart maximum stability to the rotor according to the invention. Potential weak points can exist where fibers end in disc element contact areas. Such weak points are avoided where fibers extend through disc element contact areas. At the same time, such cooling elements can be realized using very thin fiber bundles, automatically resulting in a high surface-to-volume ratio, which in turn increases the cooling effect.Orthogonal projections of the three disc element contact areas into the respective inner surface of the disc element in contact with the respective disc element contact area then define three projection surfaces A. 31 , A 32 , A 33 . One within each of the projection surfaces A 31 and A 33 lying point P 31 , P 33 defined with two within the projection area A 32 lying points P 32a , P 32b then the corners of a trapezoid. If in each of the projection surfaces A 31 , A 33 one point P each 31 , P 33 and in the projection area A 32 two points P 32a , P 32b can be determined in such a way that these four points define a trapezoid, a rotor according to the invention which is preferred in this sense is present.

[0029] For the trapezoids mentioned herein, preferably two of the four angles enclosed by the trapezoid are of equal size. Angles that differ by no more than 5° are considered equal. Preferably, the two smaller angles are each less than 89°, in particular less than 80°, e.g., less than 70° but at the same time 20°, in particular more than 30°, e.g., more than 35°.

[0030] As already mentioned above, it is advantageous if two cooling elements or cooling element regions are arranged close to one another in the rotor. This can again be described in more detail using the trapezoid described here, wherein the close arrangement is expressed in the fact that the shorter of the two parallel sides of the trapezoid takes up no more than 10% of the total length of all four edges of the trapezoid, preferably no more than 8%, in particular no more than 6%, e.g. no more than 4% of the total length of all four edges of the trapezoid. The cooling elements or cooling element regions are then (roughly approximated) aligned in the shape of a triangle, with two cooling elements or two cooling element regions of a cooling element defining two sides of the triangle and a section of one of the two disk elements defining the third side of the triangle. It can be seen that this further increases the torsional rigidity of the rotor.

[0031] The greatest longitudinal extent of a cooling element between disk elements is preferably at most 70% of the radius of the disk element with the largest radius. The cooling elements or cooling element regions are preferably distributed in the rotor such that certain cooling elements or cooling element regions rotate within an inner region of the rotor and other cooling elements or cooling element regions rotate within an outer region of the rotor. The inner and outer regions do not overlap. The cooling elements or cooling element regions are therefore arranged such that an outermost point of an inner cooling element or cooling element region is closer to the rotational axis of the rotor than an innermost point of an outer cooling element. This radial spacing creates additional turbulence, i.e. turbulent flows over large areas, so that the heat generated during braking is dissipated particularly efficiently.

[0032] In certain rotors according to the invention, the disc element contact areas can be mounted flat on the inner surfaces of the two disc elements.

[0033] According to the invention, the disc element contact areas run in recesses between the two disc elements. The textile structure extends into the disc element. This enables particularly strong anchoring. The risk of brittle fracture between the cooling elements and the disc elements is reduced to a minimum. The transition between the disc element and the cooling element can then be designed with minimal effort to withstand continuous, extreme mechanical and thermal stress.

[0034] The invention is not limited to specific disc element materials. The disc elements can, for example, be made of steel or other metals / metal alloys that are familiar to those skilled in the art for producing brake discs. However, it is particularly preferred according to the invention if at least one disc element comprises a ceramic fiber composite, such as a silicon carbide fiber composite, in particular a silicon carbide carbon fiber composite. The word "comprises" is intended to express in particular that other materials present in the layered composite, e.g. where the brake pad is pressed on, can be applied. These can be included in the disc element. Preferably, all disc elements comprise a ceramic fiber composite, e.g. a silicon carbide fiber composite, in particular a silicon carbide carbon fiber composite.

[0035] A material and / or form-fitting connection between the textile structure and the disc elements can be formed by a ceramic matrix, e.g., a matrix containing silicon carbide, in which the textile structure is embedded and which extends into the two disc elements. The disc element contact areas are then the surfaces of the textile structure where they are in contact with the disc elements.

[0036] The number of disc elements is not limited. However, since the invention relates to an internally ventilated rotor, the number of disc elements is at least two. The ventilated area arranged between the outermost disc elements can in turn be interrupted by disc elements. Such intermediate disc elements can be advantageous for certain applications; for example, the surface area of the internally ventilated area can be further increased and overheating of the brake disc can thus be counteracted even more effectively. For example, the number of disc elements can be at least three. Typically, two of the disc elements are friction disc elements and at least one disc element is an intermediate disc element. An intermediate disc element can also function as a support disc element, via which other disc elements, such as the friction disc elements, can be connected to a rotatable axle.

[0037] The connection of a rotor according to the invention to the axle can be made via a brake disc chamber that is firmly connected to the axle and to which the rotor is attached. The rotor can be attached to the brake disc chamber using conventional fastening means, such as screws. In certain embodiments, the fastening means extend only into one of the at least two disc elements. The inner diameter of this disc element is then usually smaller than the inner diameter of the other disc element or the other disc elements, such as in Fig. 5, in which only one disc element has holes for mounting fasteners such as screws. The inner diameter is defined as the smallest distance a disc element occupies from the rotor's rotational axis.

[0038] For many applications, such as in the automotive sector, the number of disc elements is two. Typically, both disc elements are friction disc elements. A friction disc element is a disc element whose surface is intended to engage a brake pad. Certain (ring-shaped) friction disc elements are often referred to as friction rings.

[0039] Internally ventilated rotors according to the invention are obtainable, for example, by a process in which a) Cooling elements or cooling element precursors (e.g. prepregs cut into small plates) are positioned relative to each other in a support material so that they protrude on both sides of the support material, b) solidifiable disc element masses are applied to opposite surfaces of the support material so that the cooling elements or cooling element precursors protrude into the solidifiable disc element masses, and c) the disc element masses are solidified.

[0040] For example, a polymer foam can be used as the support material. Specifically aligned slots can be made in this, into which platelets reinforced with carbon fiber fabric or carbon fiber scrim (prepreg platelets) are inserted so that they protrude from the support material on both sides. A polymer resin mixed with carbon fiber bundle sections can be used as the disc element mass. The applied disc element mass is cured (solidified) by heating. The support material can then be removed, e.g., by pyrolysis. The green body thus obtained is carbonized in a manner known to those skilled in the art and then infiltrated with silicon, whereby the silicon reacts with the carbonized resin to form the silicon carbide-containing matrix. The infiltration is carried out in such a way that the silicon spreads from one disc element via the cooling element platelets into the other disc element.

[0041] The invention is illustrated by the following figures and embodiments, without being limited thereto. Fig. 1 shows a rotor according to the invention Fig. 2 shows an enlarged section of the Fig. 1 shown rotor Fig. 3 shows a cooling element of the rotor from Fig. 1 and Fig. 2, in which the textile structure is a scrim Fig. 4A and Fig. 4B show the same section through the rotor of the Fig. 1 and Fig. 2 with different information each Fig. 5 shows another rotor according to the invention Fig. 5A shows a section of a cooling element of the rotor from Fig. 5 Fig. 6A and Fig. 6B show the same section through the rotor of the Fig. 5 with different information Fig. 7A and Fig. 7B illustrates the manufacture of another rotor according to the invention using sections.

[0042] The internally ventilated rotors 1 shown in the figures comprise two disc elements 2 ( Fig. 1 and Fig. 5). The at least one cooling element 3 has a textile structure 4, as in Fig. 3 for the rotor of the Fig. 1 and in Fig. 5A for the rotor of the Fig. 5. According to the invention, the textile structure 4 extends from a disc element contact area 31 of the cooling element 3, with which the cooling element 3 is in contact with a disc element 2, to another disc element contact area 32, with which the cooling element 3 is in contact with another disc element 2. This is Fig. 2 and Fig. 3 for the rotor of the Fig. 1 and out Fig. 5A and Fig. 6A for the rotor of the Fig. 5. The textile structure 4 is only visible in the Fig. 3 and Fig. 5A. For reasons of clarity, the textile structure 4 has been omitted from the other figures.

[0043] In all embodiments of the rotor according to the invention shown in the figures, all textile structures 4 comprise parallel fibers 5. These are carbon fibers. However, other fibers would also be conceivable, e.g., silicon carbide fibers, boron nitride fibers. This is Fig. 3 and Fig. 5A. In the examples shown here, not only at least one of the parallel fibers 5 extends from one disk element contact area 31 of the cooling element 3 into the other disk element contact area 32 of the cooling element, but all parallel fibers 5. Thus, in Fig. 3 the textile structure 4 a scrim 41 and a plurality of fibers 5 running parallel therein extends from one disc element contact area 31 of the cooling element 3 into the other disc element contact area 32 of the cooling element 3.

[0044] In the rotor of the Fig. 1 to 4B, the cooling elements are 3 cooling plates (30-1 and 30-2 in the section of the Fig. 4A). In the rotor of the Fig. 5 to 6B, cord-shaped cooling elements 3 run up and down in a circle all around and are thus alternately in contact with both disc elements 2. This can be achieved, for example, with the aid of a towpreg, which is passed through two spaced material layers, e.g. nonwoven layers, alternately from top to bottom and then again from bottom to top, in order to connect the material layers to one another at the desired distance. The material layers sewn together with towpreg can be transferred into a rotor according to the invention, for example, by applying solidifiable disc element mass (e.g. a polymer resin mixed with carbon fiber bundle sections) to the two outer surfaces of the material layers, solidifying this, e.g. curing it, and then carbonizing the resulting green compact and subsequently infiltrating it with silicon. A towpreg is understood to be a cord-shaped impregnated fiber bundle. It can, for example, be impregnated with a resin. The fiber bundle can, for example,a carbon fiber bundle. Instead of the towpreg, a non-impregnated, cord-shaped fiber bundle, e.g., a cord-shaped carbon fiber bundle, could also be used.

[0045] Alternatively, the application of the solidifiable disc element mass can be omitted, and only the Towpreg and any resin components contained in the associated material layers can be cured, then carbonized, and then infiltrated with silicon. To prevent unevenness on the outward-facing surfaces caused by the Towpreg or cooling element precursor, protruding Towpreg sections can be milled off. Fig. 7A and Fig. 7B show that cooling elements 3 can initially be brought into contact with the disc elements or disc element precursors in such a way that they protrude beyond the outer surfaces of the disc elements or the disc element precursors present before silicon infiltration ( Fig. 7A). The towpreg can be passed through two spaced material layers, e.g. nonwoven layers, alternating from top to bottom and then again from bottom to top, as described above. Fig. 7A to the upper illustration of the Fig. The arrow leading to Figure 7B indicates that the sections of the cooling elements 3 that extend beyond the outer surfaces of the disk elements can be milled off. Milling can be performed, for example, before infiltration with silicon, since the resulting SiC-free cooling element precursor can be processed more easily than after infiltration with silicon (which is associated with the formation of very hard SiC).

[0046] In all the examples shown, the ratio of the cooling surface A of the cooling element 3 facing the interior of the brake disc to the volume V of the section of the cooling element facing the interior of the brake disc is well over 0.4 mm-1.

[0047] It is clearly visible that the cooling elements 3, 3-1, 3-2 in all embodiments shown, at the point located between two adjacent disc elements 2 and equidistant from these two disc elements 2, extend at an angle of less than 89° to these two disc elements. The sections 4A, 6A, 7B show this most clearly, even without the point equidistant from the two adjacent disc elements being drawn in one of the figures. It is also immediately apparent from these sections that they each comprise at least two oppositely inclined cooling elements (3-1 and 3-2 in Fig. 7B), such as oppositely inclined cooling plates (30-1, 30-2 in Fig. 4A) or two oppositely inclined cooling element regions of a cooling element (310, 320 in Fig. 6A).

[0048] In Fig. 4B, Fig. 6B and Fig. 7B, trapezoids are shown in dotted lines, which can be used to describe particularly preferred rotors according to the invention in more detail. The four corners of the trapezoids each lie in projection surfaces defined by orthogonal projections, i.e., projections orthogonal to the inner surfaces of the disk elements. The outlines of the projection surfaces are shown in the sections of the Fig. 4A, Fig. 4B, Fig. 6A, Fig. 6B and Fig. 7B are indicated by dashed lines running in the direction of projection.

[0049] The rotor according to the invention Fig. 1 to 4B has pairs of adjacent cooling plates (30-1, 30-2 in Fig. 4A). Orthogonal projections (see dashed lines in Fig. 4A and Fig. 4B) of the four disc element contact areas 31-1, 32-1, 31-2, 32-2 into the respective inner surface 21, 22 of the disc element in contact with the respective disc element contact area define four projection surfaces A 31-1 , A 32-1 , A 31-2 , A 32-2 . Four points P lying within the projection surfaces 31-1 , P 32-1 , P 31-2 , P 32-2 in turn define the corners of the trapezoid.

[0050] One of the cooling plates made of Fig. 1 to 4B similar arrangement of cut or severed cooling elements exists in the rotor according to the invention, which in Fig. 7B in section. By milling, the original, continuous cooling element precursor was completely severed in the protruding areas, so that it has pairs of adjacent cooling elements (3-1, 3-2 in Fig. 7B above). Orthogonal projections (see dashed lines in Fig. 7B top and bottom) of the four disc element contact areas 31-1, 32-1, 31-2, 32-2 into the respective inner surface 21, 22 of the disc element in contact with the respective disc element contact area define four projection surfaces A 31-1 , A 32-1 , A 31-2 , A 32-2 , just like the cuts of the Fig. 4A, Fig. 4B. Here too, four points lying within the projection surfaces define P 31-1 , P 32-1 , P 31-2 , P 32-2 the corners of the mentioned trapezoid.

[0051] In contrast to the rotors of the Fig. 1 to 5A and 7B, the cord-shaped cooling element 3 comprises Fig. 5 to 6B not only two, but a plurality of disc element contact areas 31, 32, 33 ... , of which the Fig. 6A and Fig. 6B only show three. The trapezoid can still be defined in the same way as for the rotors of the Fig. 1 to 5A and 7B. However, two of the four corners of the trapezoid P 32a , P 32b in a single projection screen A 32 , as in Fig. 6B. The rotor of the Fig. 5 to 6B, the cooling element 3 has a plurality of disc element contact regions 31, 32, 33. At least two disc element contact regions 31, 33 are in contact with one disc element. A disc element contact region 32 located along the cooling element between these disc element contact regions 31, 33 is in contact with the other disc element. The textile structure 4 extends through the disc element contact region 32, which lies along the cooling element between the other disc element contact regions 31, 33. In such embodiments of the invention, the textile structure generally extends from one end of the cord-shaped cooling element to the other end of the cord-shaped cooling element and through all disc element contact regions located between the ends.Orthogonal projections of the three disc element contact areas 31, 32, 33 into the respective inner surface 21, 22 of the disc element in contact with the respective disc element contact area thus define three projection surfaces A. 31 , A 32 , A 33 . One within each of the projection surfaces A 31 , A 33 lying point P 31 , P 33 defined with two within the projection area A 32 lying points P 32a , P 32b the corners of the trapezoid.

[0052] In Fig. 4B, Fig. 6B and Fig. 7B, two of the four angles enclosed by the trapezoid are equal.

[0053] To enable particularly strong anchoring in the disc elements, the textile structure extends into the disc element in all embodiments of the invention shown in the figures. This is always particularly preferred according to the invention, regardless of the specific embodiments shown here. The disc element contact areas 31, 32, 33, 31-1, 31-2, 32-1, 32-2 thus extend into recesses in the two disc elements 2.

[0054] All figures show rotors in which both disc elements are silicon carbide carbon fiber composite friction discs, and in which a material and form-fitting connection between disc element contact areas 31, 32, 33, 31-1, 32-1, 31-2, 32-2, and disc elements 2 is formed by a silicon carbide-containing matrix in which the textile structure 4 or the parallel carbon fibers encompassed therein are embedded. The matrix extends into the two disc elements.

Claims

[1] Internally ventilated rotor (1) comprising at least two disc elements (2) connected to one another via at least one cooling element (3), wherein the at least one cooling element (3) comprises a textile structure (4) which extends from a disc element contact area (31) of the cooling element (3), with which the cooling element (3) is in contact with a disc element (2), to another disc element contact area (32) of the cooling element (3), with which the cooling element (3) is in contact with another disc element (2), and wherein the textile structure (4) comprises parallel fibers, a plurality of parallel fibers extend from one disc element contact area (31) of the cooling element (3) into the other disc element contact area (32) of the cooling element (3), and the rotor (1) has at least two oppositely inclined cooling elements (3) or two oppositely inclined cooling element areas of the cooling element (3), and wherein the disc element contact areas (31, 32) extend in recesses of the two disc elements (2). [2] Internally ventilated rotor (1) according to claim 1, wherein the textile structure (4) is a scrim (41) or a woven fabric (42) and a plurality of fibers (5) running parallel therein extend from one disc element contact area (31) of the cooling element (3) into the other disc element contact area (32) of the cooling element (3). [3] Internally ventilated rotor (1) according to claim 1 or 2, wherein the textile structure (4) and / or the parallel fibers (5) comprise carbon fibers, silicon carbide fibers, boron nitride fibers or mixtures thereof. [4] Internally ventilated rotor (1) according to claim 1, wherein the at least one cooling element (3) is a cooling plate (30). [5] Internally ventilated rotor (1) according to claim 1, wherein the ratio of the cooling surface A of the cooling element (3), e.g. the cooling plate, facing the interior of the brake disc to the volume V of the section of the cooling element, e.g. the cooling plate, facing the interior of the brake disc is at least 0.4 mm -1 amounts. [6] Internally ventilated rotor (1) according to claim 1, comprising at least two oppositely inclined cooling elements (3-1, 3-2). [7] Internally ventilated rotor (1) according to claim 1, comprising at least one pair of adjacent cooling elements (3-1, 3-2), e.g. cooling plates (30-1, 30-2), wherein orthogonal projections of the four disc element contact areas (31-1, 32-1, 31-2, 32-2) into the respective inner surface (21, 22) of the disc element in contact with the respective disc element contact area form four projection surfaces (A 31-1 , A 32-1 , A 31-2 , A 32-2 ) and four points lying within the projection surfaces (P 31-1 , P 32-1 , P 31-2 , P 32-2 ) define the vertices of a trapezoid. [8] Internally ventilated rotor (1) according to claim 1, wherein the cooling element extends back and forth between the disc elements or a plurality of cooling elements extend back and forth between the disc elements. [9] Internally ventilated rotor (1) according to claim 1, wherein the at least one cooling element (3) has at least three disc element contact areas (31, 32, 33), at least two disc element contact areas (31, 33) are in contact with the one disc element (2) and a disc element contact area (32) lying along the cooling element between these disc element contact areas (31, 33) is in contact with the other disc element (2) and the textile structure (4) extends through the disc element contact area (32) which lies along the cooling element between the other disc element contact areas (31, 33). [10] Internally ventilated rotor (1) according to claim 9, wherein orthogonal projections of the three disc element contact areas (31, 32, 33) into the respective inner surface (21, 22) of the disc element in contact with the respective disc element contact area define three projection surfaces (A31, A32, A33) and one point (P31, P33) lying within the projection surfaces (A31, A33) defines the corners of a trapezoid with two points (P32a, P32b) lying within the projection surface (A32). [11] Internally ventilated rotor (1) according to claim 7 or 10, wherein two of the four angles enclosed by the trapezoid are of equal size and / or the shorter of the two parallel sides of the trapezoid takes up at most 10% of the total length of all four edges of the trapezoid. [12] Internally ventilated rotor (1) according to claim 1, wherein at least one disc element (2) comprises a ceramic fiber composite. [13] Internally ventilated rotor (1) according to claim 1, wherein a material and / or positive connection between disc element contact areas (31, 32) and disc elements (2) is formed by a silicon carbide-containing matrix in which the structure (4) is embedded and which extends into the two disc elements (2). [14] Internally ventilated rotor (1) according to claim 1, wherein the number of disc elements (2) is two and both disc elements (2) are friction disc elements.

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