Method for coating wire arrangement for electrical machine

Abstract

The invention relates to a method for applying an electrically insulating foam structure to a wire arrangement (100) of an active component of an electrical machine and for foaming the foam structure, the method comprising: applying a thermoplastic coating polymer (110) to the wire arrangement (100), introducing the wire arrangement (100) into the active component, and applying the thermoplastic coating polymer (110) to the wire arrangement (100). The thermoplastic coating polymer (110) is brought into carbon dioxide saturation under defined temperature and pressure conditions, the active component is cooled, the ambient pressure of the active component is reduced, and the temperature is raised to form a foam structure such that the foam structure (100X) has electrically insulating properties.

Description

Technical Field

[0001] The invention relates to a method for applying an electrically insulating layer to an associated wire arrangement of an electrical machine, as well as to a wire arrangement produced by means of the method and an electrical machine having a wire arrangement produced according to the method. Background Art

[0002] The wire coils wound around the core of stators, rotors and transformers play a decisive role in electrical machines such as motors, generators and transformers, which convert electrical energy into mechanical energy or mechanical energy into electrical energy or, in the case of transformers, electrical energy into higher or lower voltages. Effective wire coating is essential for winding insulation, heat dissipation and efficiency of electrical machines. The technologies and methods for wire coating of stators in electrical machines to date have mainly involved developing corresponding formulations for the wire coating.

[0003] DE 202012104118 U1, for example, shows a method for producing a wire lacquer layer, in which the wire is pulled through a liquid lacquer bath, and then further process steps are carried out, such as baking the lacquer, and the entire process is repeated.

[0004] Patent document DE 697 14 491 T2 likewise describes the production of a varnish solution which is applied to a conductor and subsequently baked.

[0005] In general, there are few advances or innovative methods in the application and coating methods of wire coatings and the chemical composition of the formulations. In addition, these methods are often only of limited use, for example due to insufficient temperature resistance of the proposed solutions.

[0006] In active components of electrical machines, impregnation resins are often used in addition to wire lacquer to additionally protect the wire windings. Due to the small mechanical deflections of the wires, these rub against each other at high frequencies, which can damage or even strip the wire lacquer. The use of suitable impregnation resins solves this problem and protects the thin wire lacquer from mechanical forces and other factors.

[0007] However, other effects may occur for both the wire varnish and the impregnating resin, which may lead to cracks in the wire varnish insulation or the impregnating resin and eventually to peeling off the wire. For example, rapid heating and expansion of the wire or electrical conductor during operation of the electrical machine, as well as cooling and contraction after switching off, may lead to cracks in the wire varnish insulation.

[0008] If wire lacquer and impregnation resin having different thermal expansion properties are nevertheless combined with high adhesive adhesion in electrical machines, this can likewise lead to cracks at the interface between wire lacquer and impregnation resin.

[0009] Another reason for cracking or peeling of wire lacquers is that the impregnating resin contains air bubbles, which can form during the usual application methods. These bubbles expand greatly when heated and contract again when cooled. The expansion and contraction of the bubbles can lead to large-scale peeling of the wire lacquer insulation after many heating and cooling cycles.

[0010] If particles (dust, etc.) get into the wire lacquer or impregnation resin, these particles can also act as stress concentrators and cause cracking.

[0011] US2018 / 0262073A1 describes an electrical insulating material for use in an electrical device. This relates to a flexible material comprising at least one epoxy resin layer. The patent document also describes a non-woven material, such as a nylon non-woven material, as an insulating layer, which can assume the function of impregnating the resin. Summary of the invention

[0012] Therefore, the technical problem to be solved by the present invention is to provide a method for insulating the wire of an active component of an electrical machine, which method at least partially overcomes the above-mentioned disadvantages, thereby enabling effective coating of the wire device. Another technical problem to be solved is to provide insulation for the wire device in the active component of the electrical machine.

[0013] The technical objects are each achieved by a method for applying an electrically insulating foam structure to a wire arrangement of an active component of an electrical machine and for foaming the foam structure, a wire arrangement and an electrical machine.

[0014] According to one embodiment, the present disclosure provides a method for applying an electrically insulating foam structure to a wire device of an active component of an electrical machine and foaming the foam structure, wherein the method includes: applying a thermoplastic coating polymer to the wire device, introducing the wire device into the active component, achieving carbon dioxide saturation under specified temperature and pressure conditions, cooling the active component, reducing the ambient pressure of the active component and increasing the temperature to form a foam structure, wherein the foam structure has electrically insulating properties.

[0015] The electrical machine may be an electrical machine designed to generate mechanical force from an electric current. The electrical machine may in particular be an electric motor, a generator, a combination of an electric motor and a generator or the like. The electrical machine may in particular be arranged to drive a motor vehicle. The electrical machine may also be a separately excited synchronous machine.

[0016] The active parts of an electrical machine are components of an electrical machine that play an active role in the operation of the electrical machine, such as moving parts of the electrical machine or electrical components of the electrical machine. Active parts of an electrical machine are, for example, rotors, stators or armatures, transformers, coils or other components in which wire devices can be installed.

[0017] By applying the foam structure according to the disclosure, it is possible to dispense with the impregnation of the active components, while at the same time improving insulation can be achieved.

[0018] According to the present disclosure, applying a coating on a wire arrangement also includes applying a coating on a wire, in particular a wire that is part of a wire arrangement.

[0019] A "wire arrangement" is a structure or arrangement of wires intended for use in active components of electrical machines. A wire arrangement is, for example, a wire winding for a rotor, stator or transformer, or a hairpin for a stator, which comprises electrically insulated wires that conduct current.

[0020] The thermoplastic coating polymer can be applied to the wire arrangement using different techniques, such as extrusion, dipping, spraying or by roller or brush application, coating or similar methods. Typical layer thicknesses are in the range of 80-150 μm; although greater layer thicknesses are also possible, it is not desirable to use greater layer thicknesses if, for example, the highest possible conductor filling factor is to be achieved in the grooves.

[0021] Conductors in the sense of the present disclosure refer to conductive elements, such as wires or materials with electrical conductivity. Unless otherwise specified, conductors can be made of copper, copper-containing materials, aluminum or aluminum-containing materials, wherein other materials known to have electrical conductivity can also be provided according to the present invention.

[0022] The thermoplastic coating polymer is subjected to a gas treatment with carbon dioxide (CO2) under pressure and temperature. During this period, the thermoplastic coating polymer is saturated with CO2, which is in a supercritical state due to the selected pressure and temperature conditions. In order to eliminate the supercritical state of CO2, the temperature is subsequently reduced, which leads to a slow diffusion of the now liquid CO2 and thus a longer residence time of the CO2 in the thermoplastic coating polymer.

[0023] For gas treatment with CO2, the active components with the thermoplastic coated wire device can be placed in a reactor / autoclave.

[0024] For example, if the temperature in the autoclave / reactor is at least 30.9°C and the pressure is at least 73.75 bar, the CO2 may be in a supercritical state. For example, at a pressure of 74 bar, the supercritical state of CO2 can be induced by increasing the temperature in the autoclave / reactor to above 30.9°C.

[0025] In some embodiments, cooling of the active component includes cooling to a temperature below 30.9° C., and the ambient pressure of the active component is abruptly reduced to atmospheric pressure.

[0026] By suddenly reducing the pressure to atmospheric pressure, CO2 begins to transform into a gaseous state, thereby causing the CO2 to begin to phase separate.

[0027] After reducing the temperature and pressure, the temperature is increased in a targeted manner. The CO2 that is initially still dissolved in the polymer acts as a softener, thereby softening the thermoplastic coating polymer, which enables the formation of foam pores. Since there is less and less CO2 in the polymer during the temperature treatment, the softener effect is also continuously reduced until the thermoplastic polymer solidifies and foam pores are formed in the thermoplastic polymer. The pore structure can be described as "solidification". The temperature treatment can be achieved here, for example, by an induction heating element or a resistance heating element, or by using a current pulse, which is positioned in close proximity to the active component of the electrical machine, and the current pulse briefly increases the current flowing through the corresponding active component of the electrical machine. In order to improve the uniformity of the temperature distribution, the methods mentioned can be combined with each other. The increased temperature is set to a corresponding value until the foaming process is completed, which value can be 165° C., for example.

[0028] The method foams the thermoplastic coating polymer, thereby producing a porous / foamed structure, which can be referred to as a foam structure or an electrically insulating foam structure. The electrically insulating foam structure surrounds the outer contour of the wire device or each individual conductor element of the wire device. The foam structure can be arranged in a gap in the wire device, or in a gap between the wire device and the inner wall or outer wall of the active component. The foam structure can also be arranged in a gap between the wire device and the inner wall or outer wall of the electrical machinery. The foam structure can fill the gap where it is located.

[0029] Compared to non-foamed coating polymers, the electrically insulating foam structure produced has an increased surface ratio and has improved insulating properties in combination with electrically insulating electrical machine oils. The wire is better protected from mechanical influences by the buffering effect of the foamed thermoplastic coating polymer on mechanical forces. This reduces the probability of wire breakage. As a result, the service life of the electrical machine can be extended. The foamed thermoplastic coating polymer can act as a mechanical "buffer" and prevent damage to the wire arrangement.

[0030] Since no impregnation resin and therefore no impregnation step is required in the method according to the invention, the manufacture of the electrical machine is simpler and more cost-effective. In addition, impregnation equipment is maintenance-intensive equipment and requires long installation and maintenance times, which leads to extended manufacturing times.

[0031] By replacing the impregnation resin with a foamed material according to the invention, the overall weight of the electrical machine can be reduced. In addition, due to the omission of the impregnation resin and due to the uniformity of the materials of the slot base insulation and the wire insulation, adhesion problems between the slot base insulation and the wire insulation are eliminated. In addition, by omitting the impregnation resin, a corresponding interface that may occur, for example between the impregnation resin and the wire varnish, can also be eliminated, thereby also eliminating the disadvantageous interface polarization caused by this.

[0032] Since the materials used for the foamed slot base insulation and the foamed wire insulation are thermoplastics, recyclability also results. This is not usually the case with conventional wire lacquer and resin impregnation systems, since thermosetting materials are usually involved.

[0033] Since the insulation has a higher temperature resistance and the partial discharge strength and the breakdown field strength are improved, the electrical machine according to the present invention can be designed with a higher output power, or can be designed with a smaller size with the same output power. In other words: since the insulation has a higher temperature resistance, a higher power loss can be allowed.

[0034] For example, a thermosetting polymer which is not foamed by CO 2 can be applied to the wire arrangement of the active component of the electrical machine before the first coating process. A second thermoplastic layer is then applied to the first thermosetting plastic layer, which can be a primary thermosetting plastic layer, and is then foamed.

[0035] In some embodiments, a slot insulation is also introduced into the slot, which also includes a thermoplastic coating polymer. Then, the thermoplastic coated wire arrangement of the active component of the electrical machine can be foamed according to the above method. In this way, the wire coating of the active component of the electrical machine, which consists of a thermoplastic polymer, can be foamed. By omitting the impregnation resin, the interface between the wire coating of the active component of the electrical machine and the impregnation resin is also eliminated. Therefore, in this case, no adverse interface polarization occurs.

[0036] In some embodiments, the pores contained in the foam structure are filled with an insulating material. The insulating material can be an insulating fluid, such as a mineral insulating fluid or a synthetic insulating fluid. Mineral insulating fluids are based on mineral oils obtained from petroleum. Synthetic insulating fluids are based on organic compounds. Compared with mineral insulating fluids, synthetic insulating fluids generally have better properties, such as higher temperature resistance, better environmental compatibility, and a wider range of applications.

[0037] In some embodiments, the insulating material comprises oil, in particular transmission oil or insulating gas. According to the invention, the pores of the insulating foam structure are filled with electrical insulating oil, for example, by an immersion process. The transmission oil is absorbed into the porous or foamed slot insulating material by diffusion effects.

[0038] Alternatively, the pores of the insulating foam structure can be filled with an insulating gas, such as Insulating gas filling. This can be achieved, for example, by pressure injection, in which the insulating gas is injected into the pores of the material under pressure, or by an immersion process similar to that used for filling oil. However, the introduction of the insulating fluid may depend on the material properties, the pore size and the requirements of the application. It may therefore be necessary to combine different techniques or use special manufacturing to achieve effective filling of the pores.

[0039] In some embodiments, the thermoplastic coating polymer includes at least one foamable high-temperature polymer and / or a mixture of multiple foamable high-temperature polymers, wherein the foamable high-temperature polymer includes polyetherketone, especially polyetherketoneketone, polyetheretherketone, polyphenylene ether, polyetherimide, polyester, including polyethylene naphthalate, as well as polyethersulfone, polysulfone, polyethersulfone, polyphenylene sulfide and random, isotactic or syndiotactic polystyrene.

[0040] PEKK is particularly suitable for use as a wire coating due to its properties. It is characterized, for example, by its particularly high temperature resistance, and has, for example, a glass transition temperature of 155°C and a melting temperature of 307°C. In addition, it has an extremely low permittivity (dielectric constant) of 2.6 (without exceeding 250°C), which is very advantageous in terms of electrical insulation. In addition, PEKK can also be foamed at a lower cost. Therefore, in actual experiments, a density reduction of about 44% was achieved compared to compact, non-foamed PEKK. PEKK foam with oil-filled pores for wire device insulation can also perform the function of impregnating resin. In addition to PEKK, materials such as polyetheretherketone (PEEK) can also be considered, but the foamability of this material is significantly poorer. In addition, polyetherimide, polyester (such as polyethylene naphthalate), polyethersulfone, polysulfone, polyethersulfone, polyphenylene sulfide and (atactic, isotactic or syndiotactic) polystyrene can also be used.

[0041] In some embodiments, saturating the thermoplastic coating polymer with carbon dioxide is performed at a pressure of about 75-200 bar and a temperature of 40° C.-80° C. for a duration of 5 to 40 minutes.

[0042] The reactor / autoclave is then cooled to 30.9° C. or below, the pressure is then reduced to atmospheric pressure or below, and the thermoplastic material is then foamed by the action of heat at a temperature in the range of 100-250° C. until the foaming process is complete. The active component with the groove- and wire arrangement coated with PEKK is preferably introduced into the reactor and treated with carbon dioxide at a pressure of up to about 75-80 bar and a temperature of up to about 40° C. for a period of 6 minutes. Experiments have shown that under these parameters, a density reduction of about 44% (based on the thermoplastic polymer, here PEKK) is produced. Higher density reductions can also be achieved by increasing the pressure, temperature and duration (for example, a density reduction of 62% at a temperature of 200 bar and 80° C. with a saturation period of 15 minutes).

[0043] In some embodiments, a wire arrangement has a first insulation layer comprising a thermoset plastic and a second insulation layer comprised of a thermoplastic coating polymer.

[0044] The thermoplastic insulation layer of the wire arrangement is characterized in that the insulation layer is composed of a foamable high-temperature polymer, preferably PEKK. However, it may also be advantageous to use a multilayer insulation portion, which, for example, has a combination of a first insulation layer of a thermosetting material and a second insulation layer of a foamable thermoplastic coating polymer. The wire arrangement can be provided, for example, with a first base layer composed of a non-foamed polyamide-imide (PAI) and a second insulation layer of a coating polymer composed of PEKK, which is then foamed according to the above method. The foamed PEKK constitutes a high-temperature polymer foam with a high operating temperature, which, for example, can absorb and adsorb oil as an insulator. By combining these different layers and materials, an insulation portion that is both resistant to high temperatures and provides an electrical insulation effect and a mechanical buffering effect can be achieved. Combinations consisting of different thermosetting and thermoplastic coating polymers can also be used.

[0045] In some embodiments, the insulating foam structure has a layer thickness of more than 80 μm.

[0046] The typical layer thickness of the thermoplastic coating polymer initially applied to the wire arrangement and / or the groove is about 80-150 μm. During the foaming process, the density of the thermoplastic insulating layer decreases, which allows the volume to be increased and a layer thickness of 200 μm or more to be produced. Due to the increased layer thickness of the insulating foam structure in the range of 80 to 200 μm or more compared to the non-foamed wire lacquer, an optimal insulation efficiency can be achieved, depending on the active component in which the foam structure is to be introduced. In terms of mechanical forces, the wire can also be better protected from mechanical influences. The possibility of wire breakage is thus reduced.

[0047] PEKK or other high-temperature polymers can likewise be used for the insulation, whereby the insulation can also be foamed.

[0048] The space available in the gap can be taken into account here. For example, there may be more space in the winding ends of a stator as an active component. Therefore, a higher degree of expansion, i.e. a greater final layer thickness of 200 μm or more, can be achieved by foaming. The final layer thickness is the thickness of the layer at the end of the foaming process.

[0049] For example, if the insulation of an electrical machine is to be designed, the desired conductor filling factor can be taken into account.

[0050] In some embodiments, the foam structure comprises pores having a diameter no greater than 100 μm.

[0051] In general, pores or cavities in insulating materials have a negative impact on the resistance to partial discharges and the breakdown field strength. Discharges in individual larger pores with a diameter of about 100 μm or more can significantly increase the risk of complete insulation failure of the entire material. The method of the invention can advantageously make the pore diameter less than 100 μm.

[0052] In some embodiments, applying a thermoplastic coating polymer to a wire device includes contacting a wire blank (raw wire) with thermoplastic particles or thermoplastic fibers.

[0053] Thermoplastic particles can be applied to the wire arrangement by a suitable spraying process, in particular an electrospraying process. Thermoplastic particles or thermoplastic fibers can be used as spray material, which can be generated in situ by electrospraying or electrospinning processes known from the prior art.

[0054] After the application of the thermoplastic granules or the thermoplastic fibers, the uppermost layer of the wire arrangement or the wire coating of the wires comprises a layer of thermoplastic powder granules or thermoplastic fibers.

[0055] In a next step, the particles or fibers can be melted onto the wire arrangement by means of a corresponding heating device, for example based on infrared radiator technology, whereby a homogeneous layer is produced in conjunction with the spraying process.

[0056] In some embodiments, applying the thermoplastic coating polymer to the wire device comprises a fluidized bed process or an electrostatic fluidized bed process.

[0057] In order to produce a particularly uniform layer, the wire arrangement can be placed in a chamber which is designed to generate an electric field between the object to be sprayed, in this case the wire arrangement and the spray material. In particular, a fluidized bed process can be used, such as the prior art

[0058] In a next step, the particles or fibers can be melted onto the wire arrangement by means of a corresponding heating device, for example based on infrared radiator technology, whereby a particularly uniform layer is produced in conjunction with the fluidized bed process.

[0059] In some embodiments, applying the thermoplastic coating polymer to the wire device includes applying the thermoplastic coating polymer to a wire blank and fabricating the wire device from the wire blank.

[0060] In the sense of the present disclosure, a wire blank is an untreated wire or a wire having a thermosetting coating as described above and which has not or has not yet been manufactured into a wire arrangement. By applying a thermoplastic coating polymer to the wire blank, the wire arrangement can be constructed on an active component provided for this purpose, while the foam structure is only formed when the wire arrangement is in its intended position, thereby enabling a particularly suitable placement of the foam structure.

[0061] Furthermore, wire that is not processed into wire devices for active components of electrical machinery can also be used as an intermediate product for other purposes. For example, the coated wire can be used in communication metals for communication lines, wires in actuators or as "ring wires" in acoustic applications such as speakers and signal sensors.

[0062] In some embodiments, application of the thermoplastic coating polymer includes premixing a thermoset-forming polymer into the coating polymer.

[0063] Premixing means that the thermoset-forming polymer is introduced into the coating polymer before the coating polymer is applied to the wire arrangement or wire blank.

[0064] By previously mixing a thermosetting polymer into the coating polymer and a subsequent baking step for forming the thermosetting plastic layer, a multilayer structure composed of thermosetting plastic and thermoplastic coating polymer can be formed in one working step.

[0065] According to another aspect, the present disclosure comprises a wire device processed by a method according to any one of the preceding claims, and further comprising an insulating foam structure surrounding a surface of the wire device, wherein the insulating foam structure is a foamed coating polymer.

[0066] In one embodiment, the pores created by the foaming process are filled with an insulating fluid.

[0067] In another embodiment, the wire device includes an insulating foam structure applied to a first insulating layer, wherein the first insulating layer is a thermosetting material and the insulating foam structure is a foamed thermoplastic coating polymer. This multi-layer insulation surrounds the surface of the wire device. In one embodiment, the pores created by the foaming process are filled with an insulating fluid.

[0068] According to another aspect, the present disclosure includes an active component for an electrical machine, the active component also including: a wire device, which is processed according to the method of the present disclosure and has an electrically insulating foam structure enveloping the wire device. The contour of the wire device forms a thermoplastic polymer foam in the process, and the thermoplastic polymer foam completely closes the remaining cavity of the active component of the electrical machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Embodiments of the present invention are described herein by way of example and with reference to the accompanying drawings. In the drawings:

[0070] Figure 1 shows an overall view of a stator equipped with a wire arrangement, wherein the wire arrangement is coated with a coating according to the invention;

[0071] Figure 2 shows a perspective partial view of a stator with a wire arrangement coated according to the invention in the slots;

[0072] Figure 3A and Figure 3B Two different embodiments of a wire device coated according to the invention are schematically shown respectively;

[0073] Figure 4 A flow chart showing a method according to the present invention in a first embodiment;

[0074] Figure 5 A flow chart showing a method according to the present invention in a second embodiment;

[0075] Figure 6 An overall view of a stator filled with wires in the prior art is shown;

[0076] Fig. 7A and Figure 7BThe drawings show a cross section of a wire arrangement coated according to the invention in the non-foamed state and in the foamed state, respectively.

[0077] Figure 1 An overall view of a stator 10 is shown, which has a plurality of slots 20 concentrically surrounding a central cavity, and a wire arrangement 100 arranged in the slot 20, which constitutes a winding end 30 and is coated with an insulating foam structure 110X according to the present invention. The insulating foam structure 110X according to the present invention has a layer thickness of 600 μm, for example. After the foaming process, the slot 20 is completely filled with the wire arrangement 100, the foamed wire insulation and the foamed slot insulation. Since the coating polymer 110 expands during the foaming process, a larger distance can be achieved between the critical wires in the winding end 30 compared to a simple wire coating, thereby improving the insulation efficiency. The pores of the foamed slot base insulation and the pores of the foamed wire arrangement are also additionally filled with an insulating fluid, which has a similar permittivity to the coating polymer 110 of the slot base insulation and the wire insulation layer. The filling of the insulating fluid can be performed during the foaming process or after the foaming process.

[0078] Figure 2 The three-dimensional partial view of shows the cross section of the stator 10 by way of example, and schematically shows the wire device 100 located therein. The wire device 100 inserted into the slot 20 of the stator 10 has an insulating foam structure 110X that envelops the wire device 100. Before the foaming process, not only the wire device 100, but also the slot 20 of the stator 10 can be equipped with a thermoplastic coating polymer 110, so that a uniform insulating foam structure 110X can be formed during the foaming process. In this process, the contour of the wire device 100 and the thermoplastic coating polymer 110 that is optionally / selectively inserted into the slot 20 form a thermoplastic polymer foam, which completely closes the cavity remaining in the slot 20. The pores generated during the foaming process can be filled with electrical insulating oil, such as gearbox oil. The insulation efficiency of the entire stator is thus improved.

[0079] Figure 3A and Figure 3B Two different embodiments of coated wire arrangements are schematically shown before and after the foaming process. Figure 3A Here, a wire device 100 is shown with a coating polymer 110. After the foaming process, as indicated by the arrows, the volume of the coating polymer 110 increases or the density decreases, and an insulating foam structure 110X with open-cell pores is formed, which envelops the wire device 100. The pores created in the insulating foam structure 110X can now be filled with an electrically insulating oil, such as a gearbox oil, to increase the permittivity.

[0080] Figure 3B Another embodiment of the coated wire device 100 is shown, which has a multilayer insulating layer. It may be advantageous to apply a first insulating layer 110B in the first coating process, which is non-foamed and surrounds the surface of the wire device 100. The first insulating layer may be, for example, a thermosetting material. In the second step, a second insulating layer of a thermoplastic coating polymer 110A is then applied to the wire device 100 coated with the first insulating layer 110B. After the foaming process, as shown by the arrow, the volume of the coating polymer 110 increases or the density decreases, and an insulating foam structure 110X with open-cell pores is formed around the surface of the wire device 100, at which time the wire device 100 additionally has an unchanged first insulating layer 110B. The pores produced in the insulating foam structure 110X can now be filled with electrical insulating oil, such as gearbox oil, to improve the dielectric constant. The unfoamed first insulating layer 110B made of a thermosetting material, for example, has the advantage that the insulation efficiency can be improved by this additional layer.

[0081] Figure 4 A flow chart of a coating method for coating an electrical insulation layer on a wire device 100 or a slot 20 of a stator 10 according to the present invention is shown. The stator 10 is considered as a representative of an active component in the sense of the present invention. In a first step S001A, a thermoplastic coating polymer 110 is applied to the wire device 100. At the same time, the thermoplastic coating polymer 110 can be introduced into the slot 20 of the stator 10 in step S001B. In a second step, the wire device 100 coated with a thermoplastic polymer is introduced into the groove 20 of the stator. In the next step S003, the entire stator 10 is transferred to a reactor / autoclave together with the wire device 100. In the next step S004, the coating polymer is charged with carbon dioxide CO2 or saturated with carbon dioxide in the reactor / autoclave by a prescribed pressure and temperature action (at least 73.75 bar and 30.9 ° C). In the fifth step S005, the stator is cooled to a desired temperature of at least below 30.9°C while maintaining a constant pressure, which slows down the diffusion rate of CO2, thereby allowing CO2 to stay in the coating polymer for a longer time. In the subsequent step S006, the pressure in the reactor / autoclave is suddenly reduced to atmospheric pressure. By suddenly reducing the pressure to atmospheric pressure, CO2 begins to transform into a gaseous state, which causes the CO2 to begin to phase separate. In the last step S007, the temperature is specifically increased (for example, 165°C). The CO2 that is initially still dissolved in the polymer acts as a softener here, thereby softening the thermoplastic coating polymer and thus causing the formation of foam pores (S008). Since there is less and less CO2 in the polymer during the temperature treatment, the softener effect is also continuously reduced until the thermoplastic polymer "solidifies" in the pore structure.

[0082] Figure 5 A flow chart of a coating method according to the invention for coating an electrically insulating layer on a wire arrangement 100 installed in an active component, such as a stator 10, is shown. In a first step S0011, a thermoplastic coating polymer 110 is applied to a wire blank intended for manufacturing the wire arrangement 100.

[0083] As mentioned above, the wire stock may be uncoated or have a previously applied and hardened thermosetting plastic layer.

[0084] Thermoplastic particles are applied to the wire stock by a suitable spraying process, in particular an electrospraying process. For example, thermoplastic particles or thermoplastic fibers can be selectively used as spraying materials. For this purpose, the wire stock is introduced into a chamber configured for this purpose. The wire stock is grounded and a spraying device suitable for spraying the selected spraying material is charged. This allows the particles or fibers, which are electrostatically charged by the charge of the spraying device, to adhere to the wire stock.

[0085] As an alternative to the electrospraying process, the wire blank can be coated in a fluidized bed process. For this purpose, the wire blank is introduced into a chamber, wherein the particles or fibers are electrostatically charged in the fluidized bed. For example, the wire blank can be coated in a fluidized bed according to known methods. The technology deposits the particles or fibers from an electrostatic fluidized bed onto a conveyor belt and from there they are transferred to the wire blank moving past by means of additional electrodes that conduct the high voltage.

[0086] The particles or fibers can advantageously be produced in situ by means of electrospraying processes or electrospinning processes known from the prior art.

[0087] After the application of the thermoplastic granules or thermoplastic fibers, the uppermost layer of the wire coating of the wire blank comprises a layer of thermoplastic powder granules or thermoplastic fibers.

[0088] In a next step S0012 , the particles or fibers can be melted onto the wire blank by means of a corresponding heating device, for example based on infrared radiator technology, whereby a homogeneous layer is produced in combination with a spraying process or a fluidized bed process.

[0089] In the next step S0021, the wire blank is manufactured into a wire device 100. In the wire device, the wire is arranged in an active component such as a stator 10, for example.

[0090] Then proceed by Figure 4 From step S003, the Figure 4 The method in is performed with corresponding method steps S003, S004, S005, S006, S007 and S008.

[0091] Figure 6 The overall view shows a stator 10 having a plurality of slots 20 concentrically surrounding a central cavity and wire arrangements 100 arranged in the slots 20, which form winding heads 30 and are coated with a prior art coating polymer 200. The layer thickness known from the prior art is 80 to 150 μm.

[0092] Fig. 7A An embodiment of a coated wire device 100 of the present disclosure is schematically shown having a coating polymer 110 in a foam structure 110X. Fig. 7A Implementation methods are compared. Figure 7B Schematically shown is a wire arrangement 100 coated with a coating polymer 110 according to the prior art. Figure 7B The structure of the coating polymer 110 is Fig. 7A The different volumes of the structures of the midcoat polymer 110 and 100X are for illustration only. The structures in actual implementations may also be different. Fig. 7A The foam structures 110X in the embodiment may be transitionally connected to each other or form a coherent structure, which may also be referred to as a foam structure 110X.

[0093] Reference numerals list

[0094] 10 Stator

[0095] 20 slots

[0096] 30 Winding end

[0097] 100 Wire Device

[0098] 110 Thermoplastic coating polymer

[0099] 110A coating polymer first insulation layer

[0100] 110X Insulated Foam Structure

[0101] 200 Coatings in the Prior Art

[0102] S0000 Start of the method according to the first embodiment

[0103] S001A Applying thermoplastic coating polymer to wire device

[0104] S001B Placing thermoplastic coating polymer into the groove

[0105] S002 Introduction of coated wire device

[0106] S003 Introduce the entire stator into the reactor / autoclave

[0107] S004 Load the coating polymer with carbon dioxide and set the specified temperature and pressure conditions

[0108] S005 Cooling active components

[0109] S006 Pressure suddenly decreases

[0110] S007 temperature rises and forms an insulating foam structure

[0111] S008 coating- and foaming process is completed

[0112] S0000 Start of the method according to the second embodiment

[0113] S0011 Applying thermoplastic coating polymer to wire stock

[0114] S0012 Temperature treatment

[0115] S0021 Installing wire blanks

Claims

1. A method for applying an electrically insulating foam structure to a wire arrangement (100) of an active component of an electrical machine and for foaming the foam structure, wherein: The method comprises: (S001A) applying a thermoplastic coating polymer (110) to the wire device (100); (S002) introducing the wire device (100) into the active component; (S004) saturating the thermoplastic coating polymer (110) with carbon dioxide under specified temperature and pressure conditions; (S005) Cooling active components; (S006) reducing the environmental pressure of active components; (S007) increasing the temperature to form a foam structure (100X); Among them, the foam structure (100X) has electrical insulation properties.

2. The method according to claim 1, wherein: Cooling the active component includes cooling to a temperature below 30.9° C.; and when reducing the ambient pressure, the ambient pressure of the active component is suddenly reduced to atmospheric pressure.

3. The method according to any of the preceding claims, further comprising filling the pores contained in the foam structure (110X) with an insulating material.

4. The method according to claim 3, wherein: The insulating material comprises oil, in particular transmission oil, or insulating gas.

5. A method according to any one of the preceding claims, wherein: The thermoplastic coating polymer (110) includes at least one foamable high-temperature polymer and / or a mixture of multiple foamable high-temperature polymers, wherein the foamable high-temperature polymer includes polyetherketone, especially polyetherketoneketone, polyetheretherketone, polyphenylene ether, polyetherimide, polyester, including polyethylene naphthalate, as well as polyethersulfone, polysulfone, polyethersulfone, polyphenylene sulfide and random, isotactic or syndiotactic polystyrene.

6. A method according to any one of the preceding claims, wherein: Saturating the thermoplastic coating polymer (110) with carbon dioxide is carried out at a pressure of about 75-200 bar and a temperature of 40°C-80°C for a period of 5 to 40 minutes.

7. A method according to any one of the preceding claims, wherein: The wire device (100) has a first insulation layer (110A) of thermosetting and a second insulation layer of a thermoplastic coating polymer (110).

8. A method according to any one of the preceding claims, wherein: The insulating foam structure (110X) has a layer thickness of more than 80 μm.

9. A method according to any one of the preceding claims, wherein: The diameter of pores contained in the foam structure (110X) is not more than 100 μm.

10. A method according to any one of the preceding claims, wherein: Applying the thermoplastic coating polymer (110) to the wire device (100) includes contacting the wire blank with thermoplastic particles and / or thermoplastic fibers.

11. A method according to any one of the preceding claims, wherein: Applying the thermoplastic coating polymer (110) to the wire device (100) also includes a fluidized bed process or an electrostatic fluidized bed process.

12. A method according to any one of the preceding claims, wherein: Applying the thermoplastic coating polymer (110) to the wire device (100) includes applying the thermoplastic coating polymer (110) to a wire stock and manufacturing the wire device from the wire stock.

13. A method according to any one of the preceding claims, wherein: Applying the thermoplastic coating polymer (110) includes premixing a thermosetting plastic forming polymer into the coating polymer.

14. A wire arrangement (100) manufactured by means of a method according to any one of the preceding claims, comprising: A foam structure (110X) surrounds a surface of a wire device (100), wherein the foam structure (110X) comprises a foamed thermoplastic coating polymer (110).

15. An electrical machine, comprising: The wire arrangement (100) according to claim 14, wherein the wire arrangement is arranged in an active component of an electrical machine.

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