rolling bearings

Abstract

Rolling bearing (1) comprising two rings (2, 3) and rolling elements (4) rolling between them, wherein at least one electrical insulation plane formed by means of a PEEK film (5) is provided for the electrical insulation of two components (13, 14) coupled via the rolling bearing (1) from each other, characterized in that the PEEK film (5) is arranged in the rolling area of ​​the rolling bearing (1).

Description

[0001] The invention relates to a rolling bearing comprising two rings and rolling elements rolling between them.

[0002] Rolling bearings are used in a wide variety of applications and, as is well known, serve to mount two components so that they can rotate relative to each other. If the components are used, for example, for power generation, such as a rotor and a stator, or components that are potentially exposed to the risk of unintended current flow, then appropriate measures must usually be taken on the component side to electrically isolate the components from each other. It is known to apply suitable insulating layers for this purpose, often using electrically insulating plastic coatings or coverings. PEEK (polyetheretherketone), a high-performance polymer, is known to be used as the insulating material.This coating is usually applied as a powder to the surface of the component to be coated and then melted at a high temperature of 350–400°C, a process that typically takes between 30 and 60 minutes. Alternatively, application by flame spraying is also possible, in which case baking is not required. However, both coating methods are very complex and, in the case of melting the coating, involve a high temperature input that can negatively affect the mechanical properties of the coated component, for example, if the component is hardened and then tempered due to the high coating temperature.

[0003] DE 10 2009 056 349 A1 describes a rolling bearing in which a section of plastic film is attached to the circumference of the outer ring to increase thermal and / or electrical insulation. PEEK is among the materials already mentioned as a possible material for the plastic film.

[0004] The JP S63 - 259 216 A describes the application of an insulating layer to the outer surface of an outer ring as well as the inner surface of an inner ring.

[0005] DE 10 2017 106 004 A1 discloses a motor-driven fluid machine comprising an electric motor that rotates a rotary shaft and a drive circuit that drives the electric motor. Insulating films are incorporated into the fluid machine.

[0006] JP 2014-99961A describes an electric motor for an electric fan in which electrically insulating foil is installed.

[0007] The invention is therefore based on the problem of providing an alternative way to improve the isolation of two components that are rotatably mounted relative to each other.

[0008] To solve this problem, according to claim 1, a rolling bearing comprising two rings and rolling elements rolling between them is provided, which provides at least one electrical insulation plane formed by means of a PEEK film for the electrical insulation of two components coupled to each other via the rolling bearing, wherein the PEEK film is arranged on the inside of a ring and thus in the rolling area.

[0009] The invention provides a novel rolling bearing that is itself equipped with at least one electrical insulation layer. This insulation layer is formed by means of a PEEK film applied directly to the rolling bearing itself. Since the rolling bearing directly couples the two components that require electrical isolation, the insulation layer is provided precisely at the interface, i.e., the coupling point, via the rolling bearing, thus preventing current flow from one component to the other through the insulating effect of the rolling bearing or its insulation layer.

[0010] The PEEK film, which consists of pre-polymerized PEEK, can be produced in various thicknesses; thicknesses from approximately 6 µm up to several hundred µm are readily achievable. The film can also be easily pre-formed, meaning it can be geometrically adapted to the shape of the rolling bearing component to which it is to be applied, thus enabling simple attachment due to its form compatibility.

[0011] The film is conveniently applied to the rolling bearing component by gluing or laminating, for example, hot lamination. Since the film consists of a pre-polymerized PEEK, no heat is introduced into the rolling bearing component. The rolling bearing component is typically a hardened component, meaning it has undergone special heat treatments to achieve a specific surface hardness or a specific hardness profile through the material, thus creating targeted mechanical strength properties. As already described in the introduction, these properties could be reduced or negated by a higher temperature input, i.e., by re-tempering.Since, according to the invention, a fully polymerized PEEK film is already used, which is expediently attached to the rolling bearing component by simple gluing or laminating, there is consequently no temperature input that could have any negative effect on the mechanical properties of the component.

[0012] According to the invention, the PEEK film is applied to the rolling area of ​​a ring. This is particularly possible when dealing with a lightly loaded rolling bearing, i.e., one that experiences only very low rotational speeds or movements.

[0013] Furthermore, the PEEK film can be positioned or applied outside the rolling area on the outer surface of the outer ring and / or the inner surface of the inner ring and / or an end face of a ring. If the film is also applied to the outer surface of the outer ring, this provides an additional insulation layer, for example, at the transition between the rolling bearing and a fixed component, such as a stator. An additional placement on an end face is also conceivable if the component to be coupled only connects to the rolling bearing at its end face. Naturally, the film can also extend from the outside across the end face, for example, in the case of an outer ring of a radial bearing.

[0014] Furthermore, the rolling bearing can also be designed as an axial bearing, as an alternative to the radial bearing. In this case, correspondingly different arrangements of the PEEK film on one or both rings are also conceivable.

[0015] Although a single electrical insulation layer, formed by a PEEK film, may be sufficient for adequate electrical insulation, it is advantageous to provide two or more separate electrical insulation layers, each formed by a PEEK film. For example, in a radial bearing, an additional PEEK film could be applied to the outside of the outer ring or the inside of the inner ring. In the case of a thrust bearing, additional PEEK films could be applied to the axial outer surfaces of the thrust rings. This means that there are fundamentally different arrangement options, whether they are located outside the rolling area, on the outside, inside, or end face, and on one or both rings, thus offering a high degree of flexibility for optimizing the electrical insulation and the number of insulation layers.

[0016] As previously described, it is advantageous to attach the PEEK film using an adhesive. It is conceivable that the PEEK film may already be equipped with an adhesive coating. In this case, it simply needs to be attached to the respective component or ring; no additional measures such as applying adhesive are required. Attachment is particularly easy if the PEEK film is pre-shaped, which is possible through simple thermoplastic forming, as the positioning shape is predetermined.

[0017] In addition to the rolling bearing itself, the invention further relates to a method for manufacturing a rolling bearing of the described type. This method is characterized in that at least one PEEK film forming an electrical insulating layer is attached to at least one ring by means of an adhesive.

[0018] The PEEK film used can have a pre-formed shape corresponding to the geometry of the surface to which it is to be attached, i.e., it is already brought into a three-dimensional basic shape by appropriate thermoforming and, if necessary, prior cutting, which essentially corresponds to the geometry of the component or the surface geometry of the component to which it is to be attached.

[0019] Finally, the invention relates to an electrical machine comprising a stator and a rotor, which are rotatably mounted relative to each other by means of at least one rolling bearing of the type described and are electrically insulated.

[0020] It is conceivable that one or more further electrical components, in particular coils, of the electric machine are electrically insulated from surrounding objects by means of one or more further PEEK films, which form one or more electrical insulation layers. This means that the electric machine is provided with further PEEK films at corresponding positions, which locally form electrical insulation layers in order to electrically insulate further electrical components relative to each other. The use of PEEK films within the electric machine, whose rotor and stator are electrically isolated from each other but rotatably mounted via at least one rolling bearing according to the invention, usually via several such rolling bearings, is therefore advantageous for the electrical insulation of further electrical components.Here too, the described advantages regarding simple installation apply, as no special precautions for melting or flame spraying, etc., are necessary; rather, the PEEK film can simply be inserted and bonded. Likewise, the PEEK film can also be pre-shaped for this application.

[0021] The invention is explained below with reference to exemplary embodiments and the drawings. The drawings are schematic representations and show: Fig. 1 a schematic representation of a rolling bearing according to the invention together with an additional PEEK film to be applied before its arrangement, Fig. 2 the rolling bearing according to the invention made of Fig. 1 with attached additional PEEK film, and Fig. 3 A schematic representation as a partial view of an electrical machine according to the invention with a rotor and a stator, which are supported by two rolling bearings according to the invention.

[0022] Fig. Figure 1 shows a rolling bearing 1 according to the invention, comprising an outer ring 2, an inner ring 3, and rolling elements 4 rotating between them, which are usually guided in a cage and run on corresponding raceways on the outer ring 2 and the inner ring 3. The basic structure of such a rolling bearing is, of course, well known.

[0023] In the rolling area of ​​the rolling bearing 1, a PEEK film is attached to the inside of the outer ring 2 and / or to the outside of the inner ring 3, which is not shown in detail here.

[0024] In the exploded view according to Fig. Figure 1 shows an additional PEEK film 5, which is subsequently applied to the outer surface 6 of the outer ring, partially overlapping both end faces. The additional PEEK film 5 is sufficiently thin, but its thickness is chosen to ensure that the electrical insulation properties meet the requirements. The additional PEEK film 5 is, for example, cut to size from a suitably long, large film strip and then thermoformed into a three-dimensional basic shape that essentially corresponds to the shape of the outer surface 6 of the outer ring 2.

[0025] The outer surface 6 of the outer ring is clearly cylindrical, with corresponding end faces 7 adjoining it on both sides. Similarly, the additional PEEK film 5 also has a cylindrical section 8 and adjoining side sections 9.

[0026] For fastening, the additional PEEK film 5, which in the example shown is slit over a slot 10, is placed around the outer ring 2 and then attached using an adhesive. For this purpose, the additional PEEK film 5 can already be equipped with an adhesive on one side, i.e., be self-adhesive.

[0027] Fig. Figure 2 shows the rolling bearing 1 with the additional PEEK film 5 attached to the outside of the outer ring 2. This film clearly covers the entire outer surface 6 of the outer ring 2 and extends at least partially over the corresponding end faces 7 of the outer ring 2.

[0028] Fig. Figure 3 shows a schematic diagram as a partial view of an electrical machine 11 according to the invention, comprising a rotor 13 rotatably mounted on a shaft 12 and a stationary stator 14. For the rotatable mounting of the rotor 13 and the shaft 12, respectively, two rolling bearings 1 according to the invention are provided, each of which, in the example shown, is equipped with an additional PEEK film 5 on the outer ring. This additional PEEK film 5 forms a further layer of insulation, electrically isolating the rotor 13 and the shaft 12 from the stator 14. This prevents unwanted current flow across this interface.

[0029] In principle, it is possible to mount the depicted rolling bearing 1 alternatively or additionally on the inside 15 of the inner ring 3 (see Fig. 1) to equip with another PEEK film 5, which would then also be pre-formed three-dimensionally. In this case, with regard to Fig. 3, a further additional insulation layer may be provided in the transition from the shaft 12 to the rolling bearing 1.

[0030] In conclusion, it should be noted that, as an alternative to the radial design of the rolling bearing 1, it can also be designed as an axial bearing. In this case, one or more PEEK films 5 would be arranged on the corresponding axial surfaces of the two axial rings. Reference symbol list 1 rolling bearing 2 outer ring 3 inner ring 4 rolling elements 5 PEEK film 6 Outside 7 Front surface Section 8 Section 9 10 slots 11 electric machine 12 wave 13 Rotor 14 Stator 15 Inside

Claims

[1] Rolling bearing (1) comprising two rings (2, 3) and rolling elements (4) rolling between them, wherein at least one electrical insulation plane formed by means of a PEEK film (5) is provided for the electrical insulation of two components (13, 14) coupled to each other via the rolling bearing (1), characterized by , that the PEEK film (5) is arranged in the rolling area of ​​the rolling bearing (1). [2] Rolling bearing (1) according to claim 1, characterized by , that the PEEK film (5) is further arranged outside the rolling area on the outside (6) of an outer ring (2) and / or the inside of the inner ring (3) and / or an end face (7) of a ring (2, 3). [3] Rolling bearings (1) according to claim 1 or 2, characterized by that two or more separate insulation layers, each formed over a PEEK film (5), are provided. [4] Rolling bearing (1) according to any one of claims 1 to 3, characterized by, that PEEK films (5) are provided on both outer sides of the rings (2, 3) or on one outer side of the inner ring (3) and one inner side of the outer ring (2) or on both inner sides of the rings (2, 3). [5] Rolling bearing (1) according to any one of the preceding claims, characterized by , that the PEEK film (5) is attached by means of an adhesive. [6] Method for manufacturing a rolling bearing (1) according to any one of the preceding claims, characterized by , that at least one PEEK film (5) forming an electrical insulating layer is attached to at least one ring (2, 3) by means of an adhesive. [7] Method according to claim 6, characterized by , that the PEEK film (5) used has a pre-formed shape corresponding to the geometry of the surface to which it is to be attached. [8] Electrical machine comprising a stator (14) and a rotor (13) which are rotatably mounted relative to each other via at least one rolling bearing (1) according to one of claims 1 to 5 and are electrically insulated. [9] Electric machine according to claim 8, characterized by , that one or more further electrical components, in particular coils, are electrically insulated from surrounding third-party objects by means of one or more further PEEK films (5) which form one or more electrical insulation levels.

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