Isolationsmaterial

Abstract

The invention relates to an insulating material (4) comprising: an inner layer (41) which is provided and designed to adjoin the windings (35) of a coil (3), wherein the inner layer (41) is designed to be electrically insulating; an outer layer (43) which is provided and designed to adjoin an electrically conductive object (104) of an electrical machine (100), wherein the outer layer (43) is designed to be electrically conductive; and at least one middle layer (42) which is arranged between the inner layer (41) and the outer layer (43), wherein the at least one middle layer (42) is designed to be electrically insulating and with high dielectric strength in the sense that its breakdown voltage is at least 1 kV.

Description

[0001] The invention relates to an insulation material, in particular for electrical machines, such as is used as slot insulation material in stators.

[0002] There is a need to improve electric motors with regard to the target parameters of efficiency, power-to-weight ratio, reliability, and service life, although these target parameters sometimes conflict with each other. In addition to energy efficiency, increasing installation space requirements due to limited space and the constantly growing number of components are becoming more important. The requirements for reliability and service life are particularly relevant for applications in the aviation industry. The future of aircraft electrification depends significantly on the quality of the insulation systems of the motors and generators used.

[0003] US 2021 / 0036568 A1 discloses the use of a multilayer slot insulation material. A two-layer laminate or a three-layer laminate is inserted between a coil and a stator slot, with the two-layer laminate comprising an electrically conductive layer on the outside and an electrically insulating layer on the inside, and the three-layer laminate comprising an electrically conductive layer on the outside, an electrically insulating layer in the middle, and another electrically conductive layer on the inside.

[0004] The invention is based on the object of providing an insulation material for electrical machines which further improves the insulation between an electrical coil and an electrically conductive component of the electrical machine, such as a stator slot.

[0005] This object is achieved by an insulating material having the features of claim 1 and a stator having the feature of claim 21. Embodiments of the invention are specified in the dependent claims.

[0006] The invention accordingly provides an insulating material, in particular for electrical machines, which has an inner layer which is intended and designed to border the windings of a coil. The inner layer is designed to be electrically insulating. The insulating material further comprises an outer layer which is intended and designed to border an electrically conductive object of an electrical machine, wherein the outer layer is designed to be electrically conductive. As a further component, the insulating material comprises at least one middle layer which is arranged between the inner layer and the outer layer, wherein the at least one middle layer is designed to be electrically insulating and with high dielectric strength in the sense that its breakdown voltage is at least 1 kV.

[0007] The inventive solution is based on the idea of ​​providing a laminate consisting of three layers, whereby the use of an electrically conductive outer layer minimizes the risk of electrically caused damage due to delamination of the laminate against the adjacent electrically conductive structure. This is because the conductivity of the outer layer allows an electrical voltage to be evenly distributed across the outer layer, thus avoiding voltage differences. Defects such as air pockets can thus be electrically bridged. This reduces the risk of partial discharges in cavities between the insulation material and the conductive structure, which can occur particularly during coil impregnation. This ensures long-term electrical operation without aging due to partial discharges in the area of ​​the conductive outer layer.

[0008] In this context, it should be noted that a coil of an electric motor or generator is typically impregnated with a low-viscosity resin system. A resin is applied to the winding wire of the coil to fill voids within the windings or between the winding and the adjacent conductive structure (e.g., a laminated core) and to displace air bubbles. In practice, remaining air-filled voids adjacent to the conductive structure are often unavoidable. If partial discharges occur there, they can damage the insulation system. By reducing the probability of partial discharges, the quality of the insulation and its performance is improved, which can result in an extended service life.

[0009] A further advantage associated with the solution according to the invention is that the good electrical connection of the insulation material through its electrically conductive outer layer can also provide a good thermal connection, which enables improved heat dissipation.

[0010] The solution according to the invention has the further advantage that, by providing an electrically insulating middle layer with high dielectric strength, a high dielectric strength of the insulation material as a whole is ensured. A decrease in dielectric strength due to a suboptimal impregnation containing cavities can thus be avoided.

[0011] In this context, it should be noted that the dielectric strength of the core layer, which has a breakdown voltage of at least 1 kV (1000 volts), can be achieved both by combining a material with a high breakdown voltage (e.g., Kapton with a breakdown voltage of approximately 250 kV / mm) with a thin core layer thickness, or by combining a material with a relatively low breakdown voltage with a greater thickness. If the breakdown voltage is temperature-dependent, it refers to room temperature (20 °C) for the purposes of the present invention.

[0012] The mechanical, thermomechanical and thermal properties of the three-layer insulation material as a whole can also be negatively influenced by defects in the insulation system, so that the solution according to the invention also improves the mechanical resistance, the thermomechanical resistance and the thermal conductivity for heat dissipation.

[0013] In the context of the present invention, any material is considered electrically insulating which has a specific electrical resistance of at least 10 10 Ω·cm. Accordingly, any material with a specific electrical resistance of less than 10 10 Ω·cm.

[0014] An embodiment of the invention provides that the electrically conductive outer layer has a surface resistance on its outer side in the range between 10 -6 Ohm to 10 10Ohm. The electrical conductivity is accompanied by a correspondingly low surface resistance. Furthermore, the electrically insulating inner layer can have a surface resistance on its inside in the range between 10 13 Ω and 10 18 Ω. The electrically insulating design of the inner layer is accompanied by a correspondingly high surface resistance. Surface resistance is defined as the quotient of the electrical voltage applied between two electrodes and the current measured between these electrodes, with both electrodes placed on the same surface.

[0015] A further embodiment of the invention provides that the electrical properties of the three-layer insulation material as a whole are such that at least one of the following parameters is realized: - the specific resistance (also called volume resistance) of the insulation material is in the range between 10 14 Ω·cm and 10 19 Ω·cm, and / or - the breakdown voltage of the insulation material is in the range between 1 kV and 30 kV, and / or - the loss factor of the insulation material at 50 Hz is in the range between 0.0001 and 0.001, and / or - the relative permittivity (also called relative dielectric constant) of the insulation material at 50 Hz and at 1000 Hz is in the range between 1.5 and 2.5.

[0016] The electrical properties mentioned identify the insulating properties of the insulating material.

[0017] A further embodiment of the invention provides for the outer layer to be formed as a porous and yet electrically conductive material. The outer layer material exhibits open porosity, which allows it to absorb liquids or be permeable to liquids. The design of the outer layer as an open, porous material thus allows the outer layer to be filled with impregnation material during the coil impregnation process, so that the insulating material according to the invention is part of the cured resin composition. This ensures thorough impregnation and good adhesion to the adjacent phase boundary.

[0018] A porous outer layer can be formed by having conductive fibers interconnected with one another, with cavities between the fibers creating porosity in the outer layer. The conductive fibers are interconnected, for example, by weaving, braiding, knitting, laying, or bonding. Furthermore, the conductive fibers can be carbon fibers or fibers based on metals such as silver or copper.

[0019] The outer layer can consist exclusively of conductive fibers. Alternatively, conductive fibers can form the outer layer together with non-conductive fibers. For example, the outer layer consists of a blend of glass fibers and carbon fibers.

[0020] In a further embodiment, the outer layer is coated with conductive particles. Such conductive particles include, for example, graphite, carbon black, metallic particles, or electrically conductive polymers. Such a coating can be applied to a porous outer layer or to a non-porous outer layer.

[0021] Another design variant provides for the outer layer to be formed as a metallic foil. Such a conductive foil can be provided with or without perforations, with perforations enabling better impregnation.

[0022] In a further embodiment of the invention, it is provided that the inner layer and / or the outer layer are each mechanically robust. According to one embodiment, a mechanically robust design means that the tensile strength is in the range between 5 and 50 N / mm 2 lies.

[0023] The high tensile strength and the associated mechanical robustness of the inner layer and / or the outer layer enable damage-free, even fully automatic installation of the insulation material into a typically sharp-edged laminated sheet stack.

[0024] The electrically insulating inner layer can generally be made of a variety of materials. One design provides for the inner layer to be made of an aramid material. Examples of aramid materials are commercially available under the names Nomex, Kevlar, and Twaron. The inner layer can also be made of polybenzimidazole (abbreviated PBI). This is an automatic polyamide material that has similar properties to Nomex. The inner layer can, for example, be made of aramid paper.

[0025] In another example, the inner layer consists of glass fibers, basalt fibers, or a mixture thereof. Furthermore, the inner layer can be made of synthetic fibers such as polyester, nylon, acrylic, polypropylene, or elastane.

[0026] According to one embodiment, the middle layer consists of a polyimide material, in particular a polyimide film. One example of this is available under the trade name Kapton. Kapton has a high breakdown voltage of over 20 kV / mm. Alternatively, the middle layer consists of, for example, a polyester film, a Mylar film, or a film made of fluoropolymers. Furthermore, the middle layer can be made of a thermoplastic film, for example, a high-performance plastic such as PEEK.

[0027] In exemplary embodiments, the total thickness of the insulation material is in the range between 0.02 and 0.8 mm. A distinction can be made between high-voltage applications (over 1000 V) and low-voltage applications (up to 1000 V). For low-voltage applications, for example, the total thickness is in the range between 0.02 and 0.4 mm; for high-voltage applications, the total thickness is, for example, in the range between 0.4 and 0.8 mm, but there is generally no upper limit. The ratio of the layer thicknesses between the inner and middle layers can be in the range between 0.1 and 10. The layer thickness of the outer layer is, for example, 20% to 40%, e.g., 30% less than the sum of the layer thicknesses of the inner and middle layers.

[0028] Embodiments of the invention provide for the inner layer, the middle layer, and the outer layer to be bonded together by an adhesive. Bonding occurs by applying an adhesive to the surface of the layers and then joining the laminate layers together. The adhesive is then cured to ensure a permanent bond between the layers. The resulting laminate is a composite material that can be used in applications such as transformers, generators, and electric motors. The laminate can be manufactured as a continuous web.

[0029] In alternative embodiments, it can be provided that one of the layers, for example the outer layer, is pre-assembled on another structure such as in the slot of a stator and the connection with the other layers only takes place during assembly.

[0030] It should be noted that the insulating material according to the invention comprises an inner layer, a middle layer, and an outer layer as defined in claim 1. This does not preclude the insulating material from having further layers, for example, a further layer between the middle layer and the outer layer or a further layer between the inner layer and the middle layer.

[0031] In a further aspect of the invention, the present invention relates to a stator having individual teeth, each of which comprises a groove wall provided with an insulating material according to claim 1. Such a configuration is used, for example, in permanent magnet synchronous motors.

[0032] The invention is explained in more detail below with reference to the figures of the drawing using several exemplary embodiments. They show: Fig. 1 an embodiment of an insulating material; Fig. 2 schematically and by way of example an electrical machine designed as an electric motor; Fig. 3 a single tooth of a stator of the electric motor of the Fig. 2, comprising a coil of a winding wire, the coil being electrically insulated from a winding body of the single tooth via a slot insulation material; and Fig. 4 an example of the occurrence of faulty air-filled cavities between a slot insulation material and a slot wall.

[0033] For a better understanding of the present invention, its background will first be explained with reference to Fig. 2 to 4 are explained as examples.

[0034] The Fig. 1 shows, by way of example and schematically, an electric machine embodied as an electric motor 100, which, with a similar structure, can in principle also be operated as a generator. The electric motor 100 has a substantially annular stator 1 and a substantially cylindrical rotor 2, embodied in the example considered as an internal rotor. The rotor 2 is arranged within the stator 1 and rotates about a rotational axis when the electric motor 100 is in operation. The rotor 2 is connected in a rotationally fixed manner to a shaft 20, so that a rotation of the rotor 2 can be transmitted via the shaft 20 to a component to be driven (not shown), for example, to a propeller of an aircraft.

[0035] The stator 1 comprises a plurality of individual teeth 10 arranged in a ring around the stator 1. The individual teeth 10 can form a stator ring 15 or be attached to a stator ring 15. A coil in the form of a single-tooth coil 3 is applied to each individual tooth 10 and wound on a coil former formed by the individual tooth 10.

[0036] The rotor 2 has magnetic elements, e.g., in the form of permanent magnets 25 or, alternatively, in the form of excitable windings. The rotor 2 and the stator 1 are separated from each other by an air gap. Such an electric motor design is generally known to those skilled in the art, so it will not be discussed further here. A stator 1 using single-tooth coils 3 is used, for example, in permanent magnet synchronous motors.

[0037] The design of the single tooth 10 with wound coil 3 is shown in the cross-sectional view of the Fig. 3 is shown in more detail by way of example. The individual teeth 10 each comprise a sheet metal front plate 101, a sheet metal rear plate 102 and a winding core 103, which extends between the sheet metal front plate 101 and the sheet metal rear plate 102 and around which a winding wire 30 is wound. As shown in the Fig. As shown in Figure 2, the sheet metal front plate 101 has a smaller width than the sheet metal rear plate 102. This allows the majority of the individual teeth to be assembled to form the ring-shaped stator 1.

[0038] In the Fig. 3, the winding core 102 is formed integrally with the sheet metal front plate 101 and the sheet metal rear plate 102. However, this is not necessarily the case. The winding core 60 typically consists of a stack of rectangular, enamel-insulated electrical sheets (laminated sheet stack). The ends of the winding body (those in front of and behind the plane of the drawing of the Fig. 3) a winding head carrier can be attached to provide the required curvature for rounded sections of the winding wire 30.

[0039] The wound winding wire 30 forms a plurality of adjacent coil windings 35, which together form the coil 3. The coil windings 35 are wound onto the winding core 4 in the region of a groove, which has a groove wall 104.

[0040] In the illustrated embodiment, the winding wire 30 is designed as a flat copper conductor and provided with winding insulation (not shown). Alternatively, the winding wire is designed with a circular cross-section and / or as a stranded wire.

[0041] In the context of the present invention, it is important that an insulating material 4 is arranged between the inner side of the coil 3 and the winding core 103 in the region of the groove. This insulating material 4 lines the groove wall 104 and provides insulation between the coil 3 and the winding body 103 or the individual tooth 10. The present invention relates to certain embodiments of such an insulating material 4.

[0042] It should be noted that the design of the insulation material 4 does not depend on the structure of the electric motor 100. The electric motor 100 of the Fig. 2 and Fig. 3 is merely an example of an electric motor in which an insulating material 4 is used. For example, other designs of electric motors can alternatively be provided, for example, electric motors in which the rotor is designed as an external rotor, or electric motors designed as transverse flux machines. The design of the stator from individual teeth is also only an example. Furthermore, various types of coil winding can be implemented, for example, distributed windings in which coils are inserted into the stator slots across several individual teeth.

[0043] It should also be noted that the insulation material described below can be used in numerous configurations. Examples of this are described in US 2021 / 0036568 A1. The insulation material can be foil-like or flat and extend along or line a groove wall, or alternatively, it can be tubular and thus completely surround a winding wire and / or a coil.

[0044] Known slot insulation materials are, for example, designed as a three-layer laminate based on Nomex / Kapton / Nomex or as a two-layer laminate or three-layer laminate according to the document US 2021 / 0036568 A1. However, the problem is that after impregnation of the coils using resin systems, as is regularly done to mechanically fix the coils, air-filled cavities or delaminations occur between the slot insulation material and the slot wall or stator wall. Reliable, defect-free impregnation is practically impossible. The air-filled cavities result in significant disadvantages with regard to the properties of the insulation system. Such air-filled cavities are Fig. 4 shown schematically.

[0045] The Fig. Figure 4 shows a winding wire 30, which is designed as a stranded wire and accordingly has a plurality of individual wires 301 with a circular cross-section, which are surrounded by winding insulation 302. A slot insulation material 4, which may have multiple layers, is arranged between the winding wire 30 and the slot wall 104 of the winding core 103. It can be seen that in a region A, a plurality of air-filled cavities B are formed between the slot insulation material 4 and the slot wall 104.

[0046] The Fig. 1 shows an embodiment of an insulation material 4 which is designed as a three-layer laminate and avoids or at least reduces disadvantages associated with air-filled cavities.

[0047] The insulation material 4, hereinafter also referred to as insulation laminate, comprises an inner layer 41, a middle layer 42 and an outer layer 43. The inner layer 41 is intended and designed to adjoin a coil, for example a coil corresponding to the coil 3 of the Fig. 3. The outer layer 43 is intended and designed to adjoin an electrically conductive object of an electrical machine, for example a groove wall 104 of the winding core 103 of a single tooth 10 of a stator 1 according to the Fig. 3. The middle layer 42 is located between the inner layer 41 and the outer layer 43.

[0048] Each of the layers 41-43 comprises an outer side 411, 421, 431 and an inner side 412, 422, 432, with the layers 411, 422 and 421, 432 each adjacent to one another. The outer side 431 forms the outer side of the insulation laminate 4, and the inner side 412 forms the inner side of the insulation laminate 4.

[0049] For example, the individual layers 41-43 are glued together.

[0050] The inner layer 41 is designed to be mechanically robust and electrically insulating. According to one embodiment, the inner layer 41 is made of the material Nomex. The inner layer 41 can be woven or constructed of fabric. Another variant provides for the inner layer to be made of an electrical insulation paper, e.g., Nomex 410, which is an aramid paper.

[0051] Instead of Nomex, other aramid materials can be used for the inner layer 41. Examples of materials analogous to Nomex include Kevlar, Twaron, and BPI. Kevlar and Twaron are aramid materials that have similar properties to Nomex and are known for their high strength and stiffness, as well as their resistance to high temperatures. PBI is an aromatic polyamide material. It is also known for its high temperature resistance and chemical resistance.

[0052] The use of Nomex or other aramid materials provides good mechanical properties on the inner side 412 of the insulation laminate 4.

[0053] As an alternative to the aramid materials mentioned, electrically insulating fabrics can be used. These can be made of glass fibers or basalt fibers, for example. Glass fibers are glass fibers produced by melting silicon dioxide and other additives. They are known for their high strength and stiffness while remaining lightweight. Basalt fibers are fibers made from basalt rock, which are produced by melting basalt rock and then extruding it. They are known for their high strength and stiffness while remaining lightweight.

[0054] In another embodiment, the inner layer 41 is made of synthetic fibers of polyester, nylon, acrylic, polypropylene, or elastane. Polyester is a synthetic fiber made from polyethylene terephthalate (PET). It is known for its high strength and resistance to wrinkling and shrinkage. Nylon is a synthetic fiber made from polyamide. It is known for its high strength and durability, as well as its resistance to abrasion and moisture. Acrylic is a synthetic fiber made from polyacrylonitrile. It is known for its softness and thermal insulation, as well as its resistance to sunlight and aging. Polypropylene is a synthetic fiber made from propylene. It is known for its high strength and durability, as well as its resistance to moisture and chemicals. Elastane is a synthetic fiber made from polyurethane.It is known for its stretchability and elasticity as well as its resistance to sweat and sunlight.

[0055] The middle layer 42 is electrically insulating and has a high dielectric strength with a breakdown voltage of at least 1000 V. It is designed, for example, as a polyimide film and is made of Kapton material. It has a breakdown voltage of 7000 V at a thickness of 25.4 µm. Due to the good dielectric strength of the middle layer 42, the insulation material 4 as a whole has good dielectric strength and advantageous electrical insulating properties.

[0056] In alternative embodiments, the middle layer 42 is formed from films made of polyester, Mylar, or fluoropolymers. Polyester film is a synthetic film made from polyethylene terephthalate (PET). It is known for its high strength and resistance to wrinkling and shrinkage. Mylar film is a biaxially oriented PET film known for its high strength and durability. Films made of fluoropolymers include, for example, films made of FEP (fluoroethylenepropylene) or PTFE (polytetrafluoroethylene). In further embodiments, films with low temperature stability such as PP (polypropylene) and PVC (polyvinyl chloride) can be used for the middle layer 42.

[0057] The outer layer 43 is mechanically robust and electrically conductive. It consists, for example, of a porous, electrically conductive fabric. The porous fabric consists of three-dimensional components containing conductive fibers, such as carbon fibers or metal fibers. The fibers are bonded together where they touch. This creates a cavity between the fibers, which defines the porosity of the outer layer 43. This porosity allows liquid to pass through or, after curing, retains it.

[0058] The fibers are joined together by weaving, laying, gluing or other joining technologies to create two-dimensional porous, conductive flat structures.

[0059] The outer layer 43 can further be formed from a mixed fabric of electrically conductive and electrically non-conductive fibers, for example from conductive carbon fibers and non-conductive glass fibers or plastic fibers.

[0060] In a further embodiment, the outer layer 43 is coated with conductive particles, for example, with particles of graphite or carbon black, or with metallic particles. Furthermore, in exemplary embodiments, the use of electrically partially conductive particles, such as SiC particles, can be used, which can serve as an electrical potential controller due to their potential-dependent conductivity. A coating with conductive or partially conductive particles can be applied to an otherwise non-conductive material or as a conductive additive to an otherwise electrically conductive material, such as a fabric with / made of plastic fibers. A coating with conductive or partially conductive particles can also be applied to a porous material or a non-porous material.

[0061] In a further embodiment, the outer layer 43 is formed as a metallic foil, which can have perforations for better impregnability.

[0062] The electrically conductive design of the outer layer 43 prevents the formation of voltage differences on the surface 431 of the outer layer 43, so that the risk of partial discharges in the area of ​​air bubbles and defects is reduced.

[0063] The described insulation material can be used, for example, in radial flux machines, but can also be used in other topologies such as transverse flux machines and axial flux machines.

[0064] It is understood that the invention is not limited to the embodiments described above, and various modifications and improvements may be made without departing from the concepts described herein. It is further understood that any of the described features may be used separately or in combination with any other features, provided they are not mutually exclusive. The disclosure extends to and encompasses all combinations and subcombinations of one or more features described herein. Where ranges are defined, these include all values ​​within these ranges, as well as all subranges that fall within a range. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 2021 / 0036568 A1 [0003, 0043, 0044]

Claims

[1] Insulation material (4) which has: - an inner layer (41) which is designed and configured to adjoin the windings (35) of a coil (3), wherein the inner layer (41) is electrically insulating, - an outer layer (43) which is designed and configured to adjoin an electrically conductive object (104) of an electrical machine (100), wherein the outer layer (43) is electrically conductive, and - at least one middle layer (42) arranged between the inner layer (41) and the outer layer (43), wherein the at least one middle layer (42) is electrically insulating and has high electrical dielectric strength in the sense that its breakdown voltage is at least 1 kV. [2] Insulation material according to claim 1, characterized by , that the electrically conductive outer layer (43) has a surface resistance on its outer surface (431) in the range between 10 -6Ω and 10 10 exhibits Ω. [3] Insulation material according to claim 1 or 2, characterized by , that the electrically insulating inner layer (41) has a surface resistance on its inner side (412) in the range between 10 13 Ω and 10 18 exhibits Ω. [4] Insulation material according to any one of the preceding claims, characterized by , that the electrical properties of the insulating material (4) are such that at least one of the following parameters is realized: - the specific resistance of the insulating material (4) is in the range between 10 14 Ω.cm and 10 19 Ω·cm lies, and / or - the breakdown voltage of the insulating material (4) is in the range between 1 kV and 30 kV, and / or - the loss factor of the insulating material (4) at 50 Hz is in the range between 0.0001 and 0.001, and / or - the relative permittivity of the insulating material (4) at 50 Hz and at 1000 Hz is in the range between 1.5 and 2.

5. [5] Insulation material according to any one of the preceding claims, characterized by , that the outer layer (43) is designed as a porous and electrically conductive material. [6] Insulation material according to claim 5, characterized by , that the outer layer (43) has conductive fibers which are connected to each other, with cavities between the fibers which cause a porosity of the outer layer (43). [7] Insulation material according to claim 6, characterized by that the conductive fibers have been joined together by weaving, braiding, knitting, laying or gluing. [8] Insulation material according to claim 6 or 7, characterized by that the conductive fibers are carbon fibers or fibers based on metals. [9] Insulation material according to any one of claims 6 to 8, characterized by, that the conductive fibers together with non-conductive fibers form the outer layer (43). [10] Insulation material according to any one of claims 5 to 9, characterized by , that the outer layer (43) is coated with conductive particles. [11] Insulation material according to claim 5, characterized by , that the outer layer (43) is designed as a metallic foil. [12] Insulation material according to any of the preceding claims, characterized by , that the inner layer (41) and / or the outer layer (43) are each mechanically robust in the sense that the tensile strength is at least 5 N / mm² 2 , especially up to 50 N / mm 2 reached. [13] Insulation material according to any of the preceding claims, characterized by , that the inner layer (41) consists of an aramid material. [14] Insulation material according to any one of claims 1 to 12, characterized by, that the inner layer (41) consists of glass fibers or basalt fibers or a mixture thereof. [15] Insulation material according to any one of claims 1 to 12, characterized by , that the inner layer (41) consists of synthetic fibers made of polyester, nylon, acrylic, polypropylene or elastane. [16] Insulation material according to any of the preceding claims, characterized by , that the middle layer (42) consists of a polyimide material. [17] Insulation material according to any one of claims 1 to 15, characterized by , that the middle layer (42) consists of a polyester film, a Mylar film or a film made of fluoropolymers. [18] Insulation material according to any one of claims 1 to 15, characterized by , that the middle layer (42) consists of a thermoplastic film, preferably a high-performance plastic, for example PEEK. [19] Insulation material according to any of the preceding claims, characterized by, that the total thickness of the insulating material (4) is in the range between 0.02 and 0.8 mm. [20] Insulation material according to any one of the preceding claims, characterized by , that the inner layer (41), the middle layer (42) and the outer layer (43) are each connected to each other by an adhesive. [21] Stator (1) with individual teeth (10) each having a groove wall (104) provided with an insulating material (4) according to claim 1.

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