Enameled insulated round wire, manufacturing method and application thereof

Abstract

The invention relates to an enameled round wire, to a method for producing an enameled round wire and to the use of an enameled round wire. So far, lubricating wire paints, in particular wire paints having polymers containing siloxane groups, cannot be impregnated because the uppermost "last" lubricating layer in the multilayer wire paint structure is non-polar due to the siloxane groups. The invention suggests that the multilayer structure can be used in order to break at least the uppermost layer of lubricating paint by means of an intermediate step of energizing and / or Joule heating, which is often present, to raise the temperature to 200 DEG C or higher for a short period of time, thus, the subsequent impregnation with the liquid impregnating resin can be bonded to the thermally labile layer below the uppermost lubricating layer.

Description

Technical Field

[0001] The invention relates to an enameled insulated round wire, a method for manufacturing the enameled insulated round wire and use of the enameled insulated round wire. Background Art

[0002] A common example of an enameled insulated round wire is a copper wire, so-called enameled copper wire. Enameled copper wire is an insulated conductor which is covered with an electrically insulating enamel layer during manufacture. The thickness and weight of this enamel insulation is very small compared to other insulating materials with the same effect. Enameled copper wire is therefore preferably used for the production of electrical coils, transformers and machines. Other applications are the production of solderable jumpers and high-frequency stranded wires.

[0003] The use of enameled copper wires advantageously reduces the mechanical size of the motor, which results in space-saving effects in terms of winding technology, since the electric and magnetic fields are concentrated in a smaller space. Ultimately, this reduction in size due to shorter line paths also results in energy savings at the same power output.

[0004] Electrical insulating varnishes are used for coating enameled copper wires, which are used as electrical conductors in electrical components such as coils, rotors and stators. To produce these electrical components, automated winding machines are used to wind the coated insulated round wires. Here, the enameled wires should not be damaged at the edges of these electrical components and should fit easily into the grooves of these components so that a high packing density of the wires in these electrical components can be achieved. In order to achieve optimal inductive performance, a high packing density is required. Furthermore, due to the increasing demand for smaller and smaller devices and components, a high packing density is desirable, since machines such as electric motors that contain such electrical components are becoming increasingly miniaturized.

[0005] For example, low-voltage electric motors are usually manufactured with the aid of wound enameled round wires, which are drawn into the stator lamination stack after the winding process. A limiting factor here is the copper filling in the grooves, i.e. the amount of wire that can be introduced into the grooves fully automatically with the aid of this technology. First, the enameled copper wires are wound on a template with the aid of a so-called flywheel winding machine and then drawn into the grooves in bundles. In this case, the initially very orderly winding is not further fixed, as a result of which unfavorable coils can form - such as wire crossings. This crossing additionally increases the effective cross-section of the wire bundle, thereby further increasing the required pulling forces and thus further increasing the load on the automatic wire drawing machine and the winding. In order to reduce these forces to a minimum and thereby increase the maximum possible copper filling, a lubricating wax according to the prior art, such as paraffin, is used as a coating. The lubricity is also significantly increased by the use of silicone copolymers in the uppermost wire lacquer layer.

[0006] Thus, good lubricity enables processing in modern high-speed automatic winding machines where the conductors, brakes and / or guide systems exert great stresses on the enameled copper wire. For these reasons, the lubricity characteristics of the wire have become an important quality feature for the production and processing of insulated round wire.

[0007] EP 3769403 A1 discloses an electrical insulation system EIS for an electric motor, which comprises an electrical conductor in the form of a round enameled wire, wherein the round enameled wire windings are arranged in grooves of a stator lamination stack. The cavities between the windings of these conductors are filled with an impregnation resin. The content of the impregnation resin is determined by introducing a carrier containing the impregnation resin into the conductor in order to fully fill the cavities in the conductor of the lamination stack. In this case, the impregnation resin wets the surface of the round wire lacquer before the round wire lacquer hardens.

[0008] The wire lacquer itself consists of a plurality of individual plastic layers, for example made of polyethylene "PE", polyetherimide "PEI", polyamideimide "PAI", polyimide "PI", wherein, for example, each layer itself is coated in a lubricating manner on the underlying and / or upper layers so as to be flexible with respect to mechanical loads (e.g. stretching, bending, etc.).

[0009] With the aid of siloxane copolymer technology - at least in the uppermost wire varnish layer - very high copper fillings can be achieved fully automatically, but subsequent impregnation - for example of the filled grooves - with the aid of impregnation resins, for example including polyetherimides, polyethers and / or epoxy resins, is not possible, since the chemical surface groups that cause lubricity repel the impregnation resin. In particular, chemical bonds cannot be established between non-polar functional groups - such as siloxane or fluorine groups, i.e. of the lubricating varnish surface, on the one hand, and the polar impregnation resin on the other hand. Thus, up to now, it has not been possible to achieve round wire impregnation with high lubricity resulting from fluorine and / or siloxane groups on the surface. However, for low-voltage electric machines, impregnation resins are often used in the grooves. Summary of the invention

[0010] It is therefore an object of the present invention to provide a round wire lacquer which combines good lubricity and good impregnation properties with conventional impregnation resins based on polyurethane, polyetherimide, polyether and / or epoxy resins.

[0011] This object is achieved by the subject matter of the invention disclosed in the description, the drawings and the claims.

[0012] Correspondingly, the subject matter of the invention is an enameled insulated round wire comprising an electrical conductor insulated with a wire enamel surrounding the round wire in the manner of a sheath, so that the layer made of the thermally unstable material is provided as the uppermost layer or as the second-to-last wire enamel insulation layer directly adjacent to the surface.

[0013] Furthermore, the subject matter of the invention is a method for producing an enameled insulated round wire, the method comprising the following method steps:

[0014] - applying a polymerizable lacquer material layer by layer onto the round wire;

[0015] - allowing the lacquer material to harden and polymerize layer by layer to obtain a thin polymerized lacquer layer;

[0016] - optionally repeating the first two method steps until a round wire having lacquer insulation with a multilayer wire lacquer structure is present;

[0017] - applying a thermally unstable layer to the round wire;

[0018] - Manufacturing windings;

[0019] - Pull the winding into the groove;

[0020] - heating the filled grooves, thereby initiating decomposition of the thermally unstable layer;

[0021] - impregnation is performed by immersion in a liquid impregnation resin; and then

[0022] -hardening.

[0023] Finally, the subject of the present invention is also the use of an enamelled insulated round wire as described above and of a layer of thermally unstable material thereon for the production of a low-voltage electric motor.

[0024] According to an advantageous embodiment of the invention, a lubricating lacquer layer is applied to the thermally unstable layer, which lubricating lacquer layer becomes at least porous when the thermally unstable layer decomposes and / or is partially or completely removed in some places due to the release of gas by the decomposed underlying thermally unstable layer. The lubricating lacquer layer can be provided over the entire surface or in parts, wherein in the case of partial coating with lubricating lacquer, the lubricating lacquer floats locally on the underlying layer like "floating ice", especially when melting on the underlying layer. The lubricating lacquer can constitute an area proportion of the surface of the wire lacquer insulation, for example, in the range of 40% to 100%, preferably 50% to 99%, especially in the range of 55% to 95%.

[0025] According to a further advantageous embodiment of the invention, the lubricating lacquer is chemically designed such that the base material is thermally unstable, wherein the lubricity is achieved on the surface by incorporation, copolymerization, mixing and / or blending of the base material polymer with the lubricity component.

[0026] Such lubricating components are, for example, paraffins, waxes, soaps, lubricants, solid lubricants, organic radicals and surfactants, organosilicon compounds, i.e. in particular siloxanes, polysiloxanes, silazanes, polysilazanes, compounds such as boron nitride, perfluorooctanoic acid "PFOA", polytetrafluoroethylene "PTFE" or " (Teflon)" and similar materials in thermally unstable wire enamel insulation.

[0027] According to one embodiment of the invention, the uppermost wire enamel insulation layer is made of a thermally unstable material such as polyethylene so that it decomposes when heated after being introduced into the groove and exposes the underlying layers, which are, for example, part of a multilayer wire enamel structure that is compatible with the impregnation resin.

[0028] The thermally unstable layer comprises, for example, a compound selected from the group consisting of polyethylene, polyethylene glycol, polyolefins and / or polyolefin waxes, alone or in any combination. By varying the chain length of the polymer, the temperature stability can be influenced. In principle, the temperature stability shifts toward higher temperatures as the chain length increases.

[0029] When impregnating electric motors, the so-called current UV process is usually used, in which the stator is heated before being immersed in the liquid impregnation resin by energizing the individual phases. In this case, the temperature in the copper windings - which is heated directly by the Joule effect - reaches 200 to 300 ° C for a short time, and the heat is then distributed - relatively - evenly in the stator. Therefore, the stator is usually clamped and heated, which is also done in order to reduce the viscosity of the impregnation resin and to induce chemical gelling in a targeted manner.

[0030] Conventional wire varnishes include multiple layers, for example 3 to 30 layers, of different or identical polymers, such as polyetherimide, polyetherimide and / or polyamideimide, and any combination or mixture thereof. This is usually referred to as a multilayer wire varnish structure of the wire insulation varnish.

[0031] In particular, for the multilayer wire lacquer structures, impregnation resins based on polyurethanes, saturated and, in particular, preferably unsaturated polyesterimides, polyamideimides, polyesters and / or epoxy resins, and any combinations, mixtures, copolymers and / or blends thereof are used in combination.

[0032] The number of layers varies, for example, it is between 3 and 25 layers, preferably 7 to 20 layers, or 10 to 20 layers, particularly preferably, for example 15 layers.

[0033] Preferably, the layers are hardened separately from one another, so that a lubricated interface is formed between them in each case and no chemical bonding occurs between the layers.

[0034] For example, the thermally unstable layer can also be applied as the uppermost layer - somewhat thicker than the other line lacquer layers.

[0035] With regard to the layer thickness, the layers of the multilayer wire enamel structure for the wire enamel insulation of round wires are in the range from 0.2 μm to 200 μm, in particular from 0.3 μm to 50 μm and particularly advantageously in the range from 0.5 to 20 μm.

[0036] The thermally unstable layer is also applied, for example, as a prepreg based on polyethylene and / or polyethylene glycol. DETAILED DESCRIPTION

[0037] In the following, the invention is also explained in more detail with the aid of three figures, which show exemplary embodiments of the prior art and of the invention:

[0038] Figure 1 An overview of the prior art is shown as to how enamelled insulated round wires are usually constructed and present as an impregnation composite in grooves, for example in grooves of low-voltage electric motors such as traction motors.

[0039] A composite body 7 of a round wire 1 insulated with wire varnish 2 and impregnated with an impregnating resin 3 can be seen.

[0040] On the right side of the composite, a conical detail section 4 is shown enlarged, wherein the round wire 1 and the wire lacquer 2 can again be seen. In the enlarged view, the individual layers 4 can be seen on the wire lacquer 2.

[0041] Below this detailed view, the cone section shown above is further enlarged, wherein another prior art is shown here. Here, as shown above, a lubricating lacquer layer 5 is located above a conventional wire lacquer layer 2, for example with a layer structure 4. The lubricating lacquer layer 5 comprises, for example, a siloxane copolymer, whereby the lubricating lacquer layer 5 obtains a lubricated surface 8, but, unfortunately, the impregnation resin 3 falls off on this lubricated surface.

[0042] Thus, directly adjacent to the region between the round wire 1 and the conventional wire lacquer 2 there is a layer of lubricating lacquer 5 which has a lubricating additive, for example a siloxane copolymer, and then on the surface of the lubricating lacquer layer 5 there is a dashed boundary surface 8 drawn in red. Figure 1 In the example of FIG. 1 , this interface illustrates at least poor or even completely absent chemical bonding of the impregnating agent 3 to the uppermost lubricant lacquer layer 5, which is rich in lubricant on the surface. Due to this layer 8, which can form after SdT, problems according to the invention arise when impregnating round wires with a lubricant lacquer layer 5 with an impregnating resin 3. In principle, the lubricant lacquer wire technology is only used without subsequent impregnation, since as long as the impregnating resin 3 falls off on the lubricant lacquer 5, the impregnation is technically useless.

[0043] Figure 2 Starting from this prior art, a solution according to the invention according to an exemplary embodiment is shown.

[0044] A multilayer wire varnish structure 2 or 4 is again used on a round wire 1. A thin lubricating varnish layer 5 is applied as the top, “last” layer. There are a plurality of lubricating varnish layers 5 which are suitable for the relevant field of application here. For example, natural waxes, montan waxes, polyethylene waxes, and copolymers with propylene polymers formed from higher α-olefins, polypropylene oxides, esters formed from higher functional polyols and long-chain fatty acids are suitable. However, the polytetrafluoroethylene dispersions known from WO 2007 / 045575 are also suitable as lubricating varnishes for the lubricating varnish layer 5. Finally, there are lubricating varnish layers 5 containing siloxane copolymers which are suitable as lubricating varnish layers 5. In another method for increasing the lubricity of electrical insulating varnishes, components are used to functionalize the polymers contained in the varnish, for example polyamide-imides are modified with terminal long-chain alkyl groups.

[0045] Below and immediately adjacent to the last, uppermost lubricating lacquer layer 5, there is a thermally unstable layer 10, for example made of polar glycol, as the “penultimate” layer. The thermally unstable layer 10 can also be made of another suitable polymer, which decomposes at higher temperatures, which occur, for example, when manufacturing low-voltage electric machines with already filled stator grooves, and—for example, by generating gases, such as CO2—the uppermost layer is at least partially broken off, as described in accordance with Figure 2 As shown by arrow 11 in FIG.

[0046] The core of the invention is to use a multilayer structure of wire varnish so that the uppermost layer made of lubricating varnish is advantageously used for the process of drawing the enameled insulated round wire into the groove of the motor stator and then - after filling the groove - the lubricating layer is destroyed by the temperature increase by "bursting" the underlying layer to such an extent that a surface is exposed that can chemically bond with the impregnation resin.

[0047] Figure 2 Shows this:

[0048] exist Figure 2 On the far left of the figure, a thermally unstable layer 10 can be seen as the "penultimate" thin layer on the multilayer wire lacquer structure 2 - 4. On top of it there is the last lubricating lacquer layer 5, which cannot chemically bond with the impregnation resin.

[0049] Arrow 11: During the manufacture of the electric machine, by heating the windings already in the grooves, for example by energizing them, a temperature rise is formed and a thermally unstable layer 10 is formed, and this temperature rise causes the thermally unstable layer to decompose. This decomposition usually releases gaseous CO2 and thus causes the upper lubricating lacquer layer 5 to burst at multiple locations, so that the material of the penultimate layer 10 is located on the surface of the lacquer insulation layer. See Figure 2 The middle diagram of .

[0050] Arrow 12: The impregnation of the winding with the impregnation resin 3 now encounters a surface which at least partially consists of the thermally unstable layer 10, whereby a good chemical bond of the impregnation agent 3 to the thermally unstable layer 10 can be achieved at these locations. On the other hand, beneath the decomposed thermally unstable layer 10, the multi-layer wire lacquer structure 2 or 4 is exposed, through which a good chemical bond with the impregnation resin 3 can also be achieved.

[0051] Then, in Figure 2 The left side of FIG. 1 shows good chemical bonding of the impregnation resin 3 according to the invention to the surface of the enameled insulated round wire 1, since the material of the thermally unstable layer 10 or of the multilayer wire enamel 4 forms the surface of the wire insulation at several locations.

[0052] Figure 3 A further advantageous embodiment of the invention is shown. Here, by introducing siloxane groups into the thermally unstable layer, after the round wire coated with lubricating lacquer has been drawn into the groove, the lubricating lacquer layer is at least partially decomposed during the subsequent heating, thereby exposing the multilayer wire lacquer structure 4 located underneath and being able to form a good chemical bond with the impregnation resin on the surface.

[0053] Specifically, the left side again shows the structure of a round wire 1 drawn into a groove by means of a surface lubricating varnish 9. The lubricating varnish 9 is designed such that, in addition to the lubricating properties achieved by the contained siloxane groups, it has a thermally unstable material, such as polyethylene and / or polyethylene glycol, as a basic material.

[0054] Thus, at the temperature increase that occurs during the manufacture of the electric machine—indicated by arrows 11—the lubricating varnish 9 dissolves on the basis of the thermally unstable material. Under the lubricating varnish 9, the multilayer wire varnish structure 4 is exposed, which—see arrows 12—has a surface that can chemically bond well to the impregnation resin 3 when impregnated with the impregnation resin 3.

[0055] Thus, not only the advantages of lubricating varnish technology but also the advantages of impregnation can be used.

[0056] Until now, lubricating wire lacquers, in particular also wire lacquers with polymers containing siloxane groups, could not be impregnated because the uppermost, "last" lubricating layer in the multilayer wire lacquer structure is non-polar due to the siloxane groups. The present invention shows that this multilayer structure can be used to at least break up the uppermost lubricating lacquer layer by means of an intermediate step, which is always present anyway, of applying current and / or Joule heating to briefly increase the temperature to 200° C. or more, so that the subsequent impregnation with a liquid impregnation resin can bond with the thermally unstable layer located below the uppermost lubricating layer.

[0057] Reference numerals list

[0058] 1 round wire

[0059] 2 line paint

[0060] 3 Impregnation resin

[0061] 4 Multi-layer line paint structure

[0062] 5. Lubricating paint in the prior art

[0063] 6 Details

[0064] 7 Composite of enameled insulated round wire and impregnated resin

[0065] 8. No chemical bonding interface with the impregnation resin

[0066] 9 Thermally unstable lubricating paint layer

[0067] 10 Thermally unstable penultimate layer

[0068] 11 Arrows

Claims

1. An enameled insulated round wire comprising an electrical conductor insulated with a wire enamel surrounding the round wire in the form of a sheath, such that a layer made of a thermally unstable material having a lubricating component is provided as the uppermost layer and / or a thermally unstable layer is provided as the penultimate wire enamel insulation layer directly adjacent to the surface.

2. The round wire according to claim 1, wherein: The wire lacquer is realized as a multilayer wire lacquer structure having 2 to 40 layers.

3. The round wire according to any one of claims 1 or 2, wherein There are multilayer wire lacquer structures having 10 to 20 layers.

4. A round wire according to any one of the preceding claims, wherein The individual layers of the wire lacquer have a layer thickness in the range from 0.2 to 200 μm.

5. A round wire according to any one of the preceding claims, wherein The individual layers of the multi-layer wire lacquer structure are made of polymer materials.

6. The round wire according to claim 4, wherein: The individual layers of the multi-layer wire lacquer structure include an impregnating resin selected from the group consisting of epoxy resins, polyetherimides, polyurethanes and / or polyamideimides, and any combinations and / or mixtures thereof.

7. A round wire according to any one of the preceding claims, wherein After each wire lacquer layer of the multilayer wire lacquer structure, this layer is hardened before the next layer is applied, whereby a lubricated surface is present between the layers.

8. A round wire according to any one of the preceding claims, wherein The thermally unstable layer includes one or more lubricious components.

9. A round wire according to any one of the preceding claims, wherein The thermally unstable layer includes siloxane-silazane and / or fluorine groups which impart a lubricious surface to the thermally unstable layer.

10. A round wire according to any one of the preceding claims, wherein The thermally unstable layer comprises a material selected from the group consisting of polyethylene, polyethylene glycol, polyolefin and / or polyethylene wax alone or in any combination, blend and / or copolymer.

11. A round wire according to any one of the preceding claims, wherein The thermally unstable layer is thicker than the other layers of the multilayer wire lacquer structure.

12. A round wire according to any one of the preceding claims, wherein The multilayer wire lacquer structure of the round wire has a thermally unstable layer as the penultimate layer and comprises a lubricating lacquer layer on the thermally unstable layer as the last and uppermost layer.

13. A method for manufacturing an enameled insulated round wire, the method comprising the following steps: - applying a polymerizable lacquer material layer by layer onto the round wire; - allowing the lacquer material to harden and polymerize layer by layer to obtain a thin polymerized lacquer layer; - repeating the first two method steps several times until a round wire having lacquer insulation with a multi-layer wire lacquer structure is present; - applying a thermally unstable layer to the round wire; - Manufacturing windings; - pulling the winding into the groove; - heating the filled grooves, thereby initiating decomposition of the thermally unstable layer; - impregnation is performed by immersion in a liquid impregnation resin; and then -hardening.

14. The method according to claim 13, wherein: The method step of heating is at least partially carried out by supplying electricity.

15. Use of the enameled insulated round wire according to any one of claims 1 to 12 for producing a low voltage electric motor.

Images