EP4307322A1 - Enamelled rolled wire, method for its manufacture and its use - Google Patents

Abstract

The invention relates to a enamel-insulated round wire, a method for producing a enamel-insulated round wire and the use of enamel-insulated round wires. To date, it has not been possible to impregnate slippery wire enamels, especially with polymers containing siloxane groups, because the top "last" sliding layer in the multi-layer structure of the wire enamels has non-polar properties due to the siloxane groups. The invention shows that the multi-layer structure can be used to at least break up the top anti-friction varnish layer for a short time to 200 ° C or more without the often existing intermediate step with temperature input of current and / or Joule heating, so that a subsequent impregnation with liquid impregnation resin can bind to the thermally unstable layer located under the top sliding layer.

Description

The invention relates to a enamel-insulated round wire, a method for producing a enamel-insulated round wire and the use of enamel-insulated round wires.

A common example of an enameled round wire is a copper wire, i.e. a so-called enameled copper wire. An enameled copper wire is an insulated conductor that was covered with an electrically insulating layer of varnish during production. The thickness and weight of this paint insulation is very low compared to other insulation materials with the same effect. Enamelled copper wire is therefore preferred for the construction of electrical coils, transformers and machines. Other applications include solderable switching wires and the production of high-frequency strands.

By using enameled copper wire, the mechanical size of electrical machines is reduced in a favorable manner, with spatial savings effects resulting from the concentration of the electric and magnetic fields in a smaller space as part of the winding technology. Ultimately, this reduction in size through shorter cable routes also leads to energy savings with the same power output.

Electrical insulating varnishes are used to coat enamelled copper wires that are used as electrical conductors in electrical components such as coils, rotors and stators. To produce these electrical components, the coated and insulated round wire is wound using automated winding machines. The painted electrical wires on the edges of the electrical components should not be damaged and should fit easily into the grooves of the components so that a high packing density of the wire in the electrical components can be achieved. High packing densities are required to achieve optimal induction performance. A high packing density is also desirable because electrical machines such as electric motors that contain such electrical components are becoming more and more miniaturized because there is an increased demand for ever smaller devices and components.

For example, low-voltage motors are usually manufactured using wound round enameled wires, which are drawn into the stator laminated core after the winding process. A limiting factor is the copper filling in the groove, i.e. the number of wires, which can be inserted into the groove fully automatically using this technology. The enamelled copper wires are first wrapped around a template using a so-called flyer winder and then pulled into the groove in a bundle. Here, the initially very ordered winding is no longer fixed, which can result in unfavorable structures - such as wire crossings. Such crossings additionally increase the effective cross section of the wire bundles, which further increases the required pulling force and thus the load on both the pulling machine and the winding. In order to minimize these forces and thus increase the maximum possible copper filling, slippery waxes, e.g. paraffins, are used as a coating according to the state of the art. The use of siloxane co-polymers in the top layer of wire enamel also results in a significant increase in lubricity.

Good sliding properties enable the enameled copper wire to be processed in modern high-speed automatic winding machines, in which wire, brake and/or guide systems put a lot of strain on the enameled copper wire. For these reasons, the ability of wires to slide has become an important quality feature for the production and processing of insulated round wires.

From the EP 3769403 A1 an electrical insulation system EIS of an electric motor is known, which comprises electrical conductors in the form of round enamel wires with a round enamel wire winding arranged in a groove of a laminated core of a stator. The cavities between the windings of the conductors are filled with impregnation resin. The content of impregnation resin is determined by introducing a carrier containing impregnation resin into the conductor in order to sufficiently cast the cavities in the conductor of the laminated core. The impregnation resin wets the surface of the round wire varnish before it hardens.

The wire enamel itself comprises a large number of individual plastic layers, for example made of polyethylene, "PE", polyetherimide, "PEI", polyamidimide "PAI", polyimide "PI", for example each layer being applied in a slidable manner on the layer below and/or above is to be flexible to mechanical stress, e.g. stretching, bending, etc.

Using siloxane co-polymer technology - at least in the top wire enamel layer - it is possible to realize very high copper fillings fully automatically, but subsequent impregnation - for example of the filled groove - using impregnating resin, which includes, for example, polyetherimide, polyether and / or epoxy resin, not possible because the chemical surface groups that provide lubricity repel the impregnation resin. In particular, no chemical bond can be created between the non-polar functional groups - for example siloxane or fluorine groups, i.e. the anti-friction varnish surface on the one hand and the polar impregnation resin on the other. Impregnation of a round wire with high lubricity, produced by fluorine and/or siloxane groups on the surface, is therefore not yet possible. However, impregnation resins are regularly used in the grooves for low-voltage motors.

It is therefore the object of the present invention to provide a round wire varnish that combines high lubricity with good impregnability with the conventional impregnation resins based on polyurethane, polyetherimide, polyether and / or epoxy resin.

This object is achieved by the subject matter of the present invention as disclosed in the description, the figures and the claims.

Accordingly, the subject of the present invention is a lacquer-insulated round wire, comprising an electrical conductor which is insulated with wire lacquer and which surrounds the round wire in such a way that a layer of thermally unstable material is used as the top layer or as the penultimate layer directly adjacent to the surface the wire enamel insulation is provided.

• Aufbringen von polymerisierbarem Lackmaterial schichtweise auf den Runddraht,
• Schichtweise Aushärten und Polymerisieren des Lackmaterials zum Erhalt einer dünnen polymerisierten Lackschicht,
• Optional Wiederholen der ersten beiden Verfahrensschritte, bis ein Runddraht mit einer Lackisolation im Multilagen-Drahtlack-Aufbau vorliegt,
• Aufbringen einer thermisch instabilen Schicht darüber,
• Herstellen der Wicklung,
• Einziehen der Wicklung in die Nut,
• Erwärmen der gefüllten Nut, wodurch eine Zersetzung der thermisch instabilen Schicht in Gang gesetzt wird,
• Imprägnieren durch Eintauchen in flüssiges Imprägnierharz und anschließendes
• Aushärten.

The invention also relates to a method for producing a enamel-insulated round wire, comprising the following process steps:

• Applying polymerizable lacquer material in layers to the round wire,
• Curing and polymerizing the paint material layer by layer to obtain a thin polymerized paint layer,
• Optionally repeat the first two process steps until you have a round wire with varnish insulation in a multi-layer wire enamel structure,
• Applying a thermally unstable layer over it,
• producing the winding,
• pulling the winding into the groove,
• Heating the filled groove, which initiates decomposition of the thermally unstable layer,
• Impregnation by dipping into liquid impregnation resin and then
• Harden.

Finally, the invention also relates to the use of a lacquer-insulated round wire as described above and a layer of thermally unstable material thereon for the production of low-voltage electric motors.

According to an advantageous embodiment of the invention, a lubricating varnish layer is applied over the thermally unstable layer, which becomes at least holey when the thermally unstable layer decomposes and/or is partially or completely removed in some places due to gas release from the decomposing lower thermally unstable layer. The anti-friction varnish layer can be provided over the entire surface or in part, whereby when partially coated with anti-friction varnish, it floats in areas like "ice floes" on the lower layer, especially when melting on the lower layer. The anti-friction varnish can make up a surface area, for example in the range from 40% to 100%, preferably 50% to 99%, in particular in the range from 55% to 95% of the surface of the wire enamel insulation.

According to a further advantageous embodiment of the invention, a lubricating varnish is chemically designed so that the base is thermally unstable, with lubricating properties being achieved on the surface by introducing, copolymerizing, mixing and/or blending the base polymer with lubricating components.

Such lubricity components are, for example, paraffins, waxes, soaps, lubricants, solid lubricants, organic groups and compounds such as surfactants, organosilicon compounds, in particular siloxanes, polysiloxanes, silazanes, polysilazanes, boron nitride, fluorinated compounds such as perfluorooctanoic acid "PFOA", polytetrafluoroethylene "PTFE" or "Teflon ^® " and similar in the thermally unstable wire enamel insulation layers.

According to one embodiment of the invention, the top wire enamel insulation layer is made of a thermally unstable material such as polyethylene so that it can be used after insertion in the groove when heated, this layer decomposes and exposes the underlying layers, which are, for example, part of a multi-layer wire enamel structure that is compatible with the impregnation resins.

The thermally unstable layer comprises, for example, a compound selected from the group comprising: polyethylene, polyethylene glycol, polyolefin and/or polyolefin wax alone or in any combinations. The temperature stability can be influenced by varying the chain length of the polymer. Basically, the temperature stability is shifted to higher temperatures with longer chain lengths.

When impregnating electric motors, the so-called current UV process is often used, whereby the stators are heated in advance by energizing the individual phases before being immersed in the liquid impregnation resin. The temperatures in the copper windings, which are heated directly by the Joule effect, briefly reach 200°C to 300°C before the heat is distributed relatively homogeneously in the stator. It is therefore common practice to connect the stators and heat them, also to reduce the viscosity of the impregnation resin and to specifically bring about chemical gelling.

Conventional wire enamels include several, for example in the range of 3 to 30, layers of different or identical polymers, e.g. polyetherimide, polyetherimine and/or polyamideimide, as well as any combinations or mixtures thereof. This is commonly referred to as the multi-layer wire enamel construction of the wire insulation enamel.

In particular, impregnation resins based on polyurethane, saturated and particularly preferably unsaturated polyesterimide, polyamideimide, polyester and/or epoxy resin, as well as any combinations, mixtures, copolymers and/or blends thereof, combined, are used for the multilayer wire enamel structure.

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.

The layers are preferably hardened separately from one another, so that sliding interfaces are created between them and no chemical bond occurs between the layers.

For example, the thermally unstable layer can also be applied as a top layer - slightly thicker than the other wire enamel layers.

In terms of 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 between 0.5 to 20 µm .

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

The invention is explained in more detail below using three figures that show the prior art and exemplary embodiments of the invention:
Figure 1 shows an overview of the state of the art, how enameled round wires are usually constructed and are present as an impregnated composite in a groove, for example of a low-voltage electric motor such as a traction motor.

A composite 7 of round wires 1 insulated with wire enamel 2 and impregnated with impregnation resin 3 can be seen.

To the right of the composite, a conical detail section 4 is shown enlarged, with the round wire 1 again. and wire enamel 2 can be seen. In the wire enamel 2, the individual layers 4 can be seen in the enlarged view.

Below the detailed view there is a further enlargement of the conical section shown above, with another prior art shown here. Above the usual wire enamel layers 2, for example with a layer structure 4, as shown above, there is a lubricating varnish layer 5. This lubricating varnish layer 5 comprises, for example, a siloxane copolymer, whereby the lubricating varnish layer 5 receives a slippery surface 8, on which the impregnation resin 3 unfortunately rolls off .

Directly adjacent to the area between round wire 1 and conventional wire enamel 2, there is this layer of anti-friction varnish 5 with added lubricity, for example with a siloxane copolymer, and then a dashed interface 8 drawn in red on the surface of the anti-friction varnish layer 5, which is at least poor or even a complete lack of chemical bonding of the impregnating agent 3 to the top anti-friction varnish layer 5 enriched with lubricant on the surface Figure 1 clarified. Because of this layer 8, which would form according to the SdT if the round wires with a sliding varnish layer 5 were impregnated with impregnation resin 3, the problem of the present invention arises. The technology with bonded varnish wires is generally only used without subsequent impregnation because impregnation is of no technical use as long as the impregnation resin 3 rolls off the bonded varnish 5.

Figure 2 shows - based on this prior art - the solution according to the present invention using an exemplary embodiment.

The multi-layer wire varnish structure 2 or 4 on the round wire 1 is used again. A thin anti-friction varnish layer 5 is applied as the top “last” layer. There are many anti-friction coatings 5 that are suitable for the relevant area of application. For example, natural waxes, montan waxes, polyethylene waxes, and copolymers with propylene polymers are suitable from higher α-olefins, polypropylene oxides, esters from higher functional polyols and longer chain fatty acids. But also polytetrafluoroethylene dispersions, such as those from the WO 2007/045575 are known, are suitable as a lubricating varnish for the lubricating varnish layer 5. Finally, there are lubricating varnish layers 5 with siloxane copolymer, which are suitable as a lubricating varnish layer 5. In a further approach to improving the sliding properties of electrical insulating paints, the polymers contained in the paint are functionalized with components, for example the modification of polyamide imides with terminal longer-chain alkyl groups.

Under the last top anti-friction varnish layer 5 and directly next to it there is a thermally unstable layer 10, for example made of polyethylene glycol, as the "penultimate" layer. The thermally unstable layer 10 can also be made of another suitable polymer, which decomposes at higher temperatures, such as those that occur in the production of low-voltage motors with already filled stator slots, and - through, for example, gas evolution such as CO2 evolution - at least the upper layer partly blows off, as shown by arrow 11 in the Figure 2 shown.

The core of the invention is to use the multi-layer structure of a wire enamel in order to use the top layer of anti-friction varnish for the process of pulling the enamel-insulated round wires into the stator groove of the motor and then - after filling the groove - to pass the anti-friction layer through the temperature input. "Bursting" of an underlying layer to such an extent that a surface that can be chemically bonded with the impregnation resin is exposed.

This shows the Figure 2 :
On the far left in the Figure 2 A thermally unstable layer layer 10 can be seen as the "penultimate" thin layer on the multilayer wire enamel structure 2 - 4. Above this is the last layer of anti-friction varnish 5, which cannot be chemically bonded to the impregnation resin.

Arrow 11: By heating, for example energizing, the winding already in the slot during the manufacture of the motor, a temperature input is created in the thermally unstable layer 10 and decomposes it. The decomposition usually releases CO2 in gaseous form and causes the overlying anti-friction varnish layer 5 to burst in many places, so that the material of the penultimate layer 10 comes to rest on the surface of the varnish insulation. See the illustration in the middle Figure 2 .

Arrow 12: Impregnation of the winding with impregnation resin 3 now encounters a surface which at least partially consists of a thermally unstable layer 10, which means that a good chemical bonding of the impregnation agent 3 to the thermally unstable layer 10 is possible at these points. On the other hand, below the decomposed, thermally unstable layer 10, the multilayer wire enamel structure 2, or 4, is exposed, via which a good chemical bond to the impregnation resin 3 is also possible.

Left in the Figure 2 then shows the good chemical bond according to the invention of the impregnation resin 3 to the surface of the lacquer-insulated round wire 1, because in many places the material of the thermally unstable layer 10 or the multi-layer wire lacquer 4 forms the surface of the wire insulation.

Figure 3 shows a further advantageous embodiment of the invention. By introducing siloxane groups into the thermally unstable layer after the round wires coated with anti-friction varnish have been drawn into the groove, the anti-friction varnish layer is at least partially decomposed during the subsequent heating, as a result of which the underlying multi-layer wire varnish structure 4 is exposed and superficially coated with an impregnation resin can form good chemical bonds.

In detail, the structure of a round wire 1 drawn into the groove using superficial anti-friction varnish 9 is shown again on the left. The anti-friction varnish 9 is designed in such a way that, in addition to the anti-friction properties achieved by the siloxane groups it contains, it is a thermally unstable base material Material such as polyethylene and/or polyethylene glycol.

When temperature is introduced - shown by arrow 11 - which occurs during the manufacture of an engine, the anti-friction varnish 9 on a thermally unstable material basis dissolves. Below the anti-friction varnish 9, the multi-layer wire varnish structure 4 is exposed, which - see arrow 12 - has a surface that can be easily bonded chemically to the impregnation resin 3 when impregnated with impregnating resin 3.

This means that both the advantages of the bonded coating technology and those of impregnation can be used.

To date, it has not been possible to impregnate slippery wire enamels, especially with polymers containing siloxane groups, because the top "last" sliding layer in the multi-layer structure of the wire enamels has non-polar properties due to the siloxane groups. The invention shows that the multi-layer structure can be used to at least break up the top anti-friction varnish layer without the often existing intermediate step with temperature input of current and / or Joule heating to 200 ° C or more, so that a subsequent impregnation with liquid impregnation resin can bind to the thermally unstable layer located under the top sliding layer.

Reference symbol list

1

round wire

2

Wire enamel

3

waterproofing resin

4

Multilayer wire enamel construction

5

Anti-friction varnish according to the state of the art

6

Detail section

7

Composite of varnished round wires and impregnation resin

8th

Interface that does not chemically bond to the impregnation resin

9

Thermally unstable anti-friction coating layer

10

Thermally unstable penultimate layer

11

Arrow

Claims (15)

Lacquer-insulated round wire, comprising an electrical conductor insulated with wire enamel that encases the round wire, such that a layer of thermally unstable material with a lubricity component is provided as the topmost layer and / or a thermally unstable layer as the penultimate , a layer of wire enamel insulation directly adjacent to the surface is provided. Round wire according to claim 1, in which the wire enamel is realized in a multilayer wire enamel structure with 2 to 40 layers. Round wire according to one of claims 1 or 2, in which there is a multilayer wire enamel structure with 10 to 20 layers. Round wire according to one of the preceding claims, in which the individual layers of the wire enamel have a layer thickness in the range of 0.2 to 200µm. Round wire according to one of the preceding claims, in which the individual layers of the multilayer wire enamel structure are made of polymeric material. Round wire according to claim 4, in which the individual layers of the multilayer wire enamel structure comprise an impregnation resin selected from the group of the following compounds: epoxy, polyetherimide, polyurethane and/or polyamideimide, as well as any combinations and/or mixtures thereof. Round wire according to one of the preceding claims, in which after each wire enamel layer of the multilayer wire enamel structure, the layer is hardened before the next layer is applied and thus There are slippery surfaces between the layers. Round wire according to one of the preceding claims, wherein the thermally unstable layer layer comprises one or more lubricity components. Round wire according to one of the preceding claims, wherein the thermally unstable layer comprises siloxane-silazane and/or fluorine groups which give the thermally unstable layer a lubricious surface. Round wire according to one of the preceding claims, wherein the thermally unstable layer layer comprises a material selected from the group of the following compounds: polyethylene, polyethylene glycol, polyolefin and/or polyethylene wax alone or in any combinations, blends and/or copolymers. Round wire according to one of the preceding claims, wherein the thermally unstable layer layer is thicker than the other layers of the multilayer wire enamel structure. Round wire according to one of the preceding claims, wherein the multi-layer wire enamel structure of the round wire has a thermally unstable layer as the penultimate layer and, lying on top of it, comprises a lubricating varnish layer as the last and top layer. Process for producing a lacquer-insulated round wire, comprising the following process steps: - Applying polymerizable lacquer material in layers to the round wire, - Curing and polymerizing the paint material layer by layer to obtain a thin polymerized paint layer, - Repeat the first two process steps several times until you have a round wire with varnish insulation in a multi-layer wire enamel structure - applying a thermally unstable layer over it, - Making the winding - Pulling the winding into the groove - Heating the filled groove, which initiates decomposition of the thermally unstable layer, - Impregnation by dipping into liquid impregnation resin and then - Harden. Method according to claim 13, in which the step of heating is carried out at least in part by supplying electricity. Use of a paint-insulated according to one of claims 1 to 12 for the production of low-voltage electric motors.

Images