JP2024128627A - Insulated wires, coils, rotating electrical machinery and electrical/electronic equipment - Google Patents

Abstract

[Problem] To provide an insulated electric wire that has excellent peelability of an insulating coating by laser light irradiation even when the insulating coating does not contain foreign matter such as transition metal oxide particles, a coil using the insulated electric wire, a rotating electric machine and an electrical/electronic device having the coil, and a method for manufacturing the rotating electric machine and the electrical/electronic device. [Solution] An insulated electric wire 1 having a conductor 10 and an insulating coating 20 that covers the outer periphery of the conductor 10, the insulating coating 20 being a multilayer insulating layer formed by repeatedly applying and baking a resin varnish to the outer periphery of the conductor 10, the average thickness of each insulating layer that constitutes the multilayer insulating layer being 3.0% or more relative to the thickness of the insulating coating 20, and the interlayer adhesion strength of the multilayer insulating layer being 0.04 N/mm or more. [Selected Figure] Figure 1

Description

The present invention relates to insulated wires, coils, rotating electrical machines, and electrical and electronic devices.

Coils used in rotating electrical machines such as motors are manufactured, for example, by shortening (segmenting) an insulated electric wire, processing it into a hairpin shape to make a segment coil, inserting this segment coil into a slot in a stator core, and electrically connecting the ends of the segment coil protruding from the stator core by welding them together. In order to perform this welding, it is necessary to remove the insulating coating (end insulating coating) covering the end of the segment coil to expose the conductor. To remove this end coating, a method of mechanically cutting and removing it by press processing or the like has been used in the past. However, with this method, not only the insulating coating but also the surface layer of the conductor part is scraped off, which causes a problem in terms of the cross-sectional area of the conductor. In addition, there are problems in terms of manufacturing efficiency, such as the need to dispose of the shavings of the metal conductor and wear on the mold used in the press processing.
Instead of the above-mentioned mechanical removal method of the end coating, a technique has been proposed in which the end coating is burned off and removed using a laser beam. For example, Patent Document 1 describes that, in manufacturing a rotating device in which an insulated electric wire is wound around an insulated armature, the insulating coating of the insulated electric wire contains transition metal oxide particles that absorb laser beams and generate heat, so that the insulating coating of the end portion of the insulated electric wire can be easily removed by irradiating the wire with a laser beam.

JP 2010-15907 A

In the technology described in Patent Document 1, it is necessary to prepare a slurry in which a relatively large amount of transition metal oxide particles are uniformly dispersed in a resin varnish prior to forming the insulating film, which limits the improvement of work efficiency. In addition, if the insulating film contains a large amount of transition metal oxide particles that exhibit physical properties different from those of the insulating resin, there is a concern that the adhesion between the insulating film and the conductor and between the layers that make up the insulating film may decrease.

The present invention aims to provide an insulated electric wire that has excellent peelability of an insulating coating by laser light irradiation, even when the insulating coating does not contain foreign matter such as the transition metal oxide particles. In addition, the present invention aims to provide a coil using this insulated electric wire, a rotating electric machine and an electric/electronic device that have this coil, and a method for manufacturing these.

The above object of the present invention can be achieved by the following means.
[1]
An insulated wire having a conductor and an insulating coating covering the outer periphery of the conductor,
The insulating coating is a multi-layer insulating layer formed by repeatedly applying and baking a resin varnish on the outer periphery of the conductor,
the average thickness of each insulating layer constituting the multilayer insulating layer is 3.0% or more of the thickness of the insulating coating;
The insulated wire has an interlayer adhesion strength of 0.04 N/mm or more for the multilayer insulating layer.
[2]
The insulated wire according to any one of claims 1 to 5, wherein the number of layers of the multilayer insulating layer is 25 or less.
[3]
The insulated wire according to any one of [1] to [2], wherein the insulating coating has a transmittance of 50% or less at a wavelength of 450 nm.
[4]
The insulated wire according to any one of [1] to [3], wherein the insulating coating contains polyimide and/or polyamideimide.
[5]
The insulated wire according to any one of [1] to [4], wherein the insulated wire is used after an end insulating coating is laser peeled off.
[6]
A coil using the insulated wire according to any one of [1] to [5].
[7]
A rotating electric machine having the coil according to [6].
[8]
An electric/electronic device having the coil according to [6] above.
[9]
A laser peelable insulating coating that covers the outer periphery of a conductor,
The insulating coating is a multi-layer insulating layer formed by repeatedly applying and baking a resin varnish on the outer periphery of the conductor,
the average thickness of each insulating layer constituting the multilayer insulating layer is 3.0% or more of the thickness of the insulating coating;
The insulating coating for laser peeling has an interlayer adhesion strength of 0.04 N/mm or more for the multilayer insulating layer.
[10]
A step of removing an end insulating coating of the segment of the insulated electric wire according to any one of [1] to [5] by irradiating with laser light;
a step of forming the segment from which the end insulating coating has been removed into a coil shape to form a segment coil, and incorporating the segment coil into a slot of a stator core;
A method for manufacturing a rotating electric machine or an electrical/electronic device, comprising a step of welding the ends of the segment coils together to electrically connect them.
[11]
A process of processing the segment of the insulated electric wire according to any one of [1] to [5] into a coil shape to form a segment coil and incorporating the segment coil into a slot of a stator core;
removing an end insulating coating of the segment coil incorporated in the slot of the stator core by irradiating it with laser light;
A method for manufacturing a rotating electric machine or an electrical/electronic device, comprising a step of welding the ends of the segment coils together to electrically connect them.

The insulated wire of the present invention has excellent peelability of the insulating coating by laser light irradiation, even when the insulating coating does not contain foreign matter such as the transition metal oxide particles. Therefore, when welding insulated wires together during the manufacture of coils, rotating electrical machines, or electrical/electronic devices using the insulated wire of the present invention, the end insulating coating can be quickly removed by laser light irradiation, resulting in excellent manufacturing efficiency.

1 is a cross-sectional view illustrating a schematic configuration example of an insulated wire according to an embodiment of the present invention. 3A to 3C are explanatory diagrams for explaining a manufacturing process of the coil of the present invention. 1 is a schematic perspective view showing a preferred embodiment of a stator used in an electric/electronic device of the present invention; 1 is a schematic exploded perspective view showing a preferred embodiment of a stator used in an electric/electronic device of the present invention;

In the present invention and this specification, the term "insulating layer" simply refers to a layer (enamel layer) formed by applying and baking a resin varnish once. In the present invention, an insulating layer formed by repeatedly applying and baking the same resin varnish multiple times is considered to be a multi-layer insulating layer (multilayer insulating layer). In other words, whether the resin varnish is the same or different, a layer formed by applying and baking once is counted as one insulating layer. In other words, when applying and baking are repeated, a multilayer insulating layer is formed in which the same number of insulating layers as the number of repetitions are stacked.
In the present invention, the insulating coating of the insulated wire, as described above, has as a specific feature that it includes multiple insulating layers formed by repeatedly applying and baking resin varnish. However, this simply indicates the state of the insulating coating (i.e., indicates that the insulating coating includes a specific enamel layer), thereby clarifying the structure or characteristics of the insulating coating.
In this specification, the cross-sectional shape of the insulated electric wire perpendicular to the longitudinal direction, including the conductor and the insulating coating, may be simply referred to as the cross-sectional shape. The cross-sectional shape in this invention does not simply mean that only the cut surface has a specific shape, but means that this cross-sectional shape is continuous in the longitudinal direction of the entire insulated electric wire, and unless otherwise specified, the cross-sectional shape perpendicular to the longitudinal direction is substantially the same for any part of the insulated electric wire.
In this specification, a numerical range expressed using "to" means a range including the numerical values before and after it as the lower limit and upper limit.
In this specification, the unit of concentration "ppm" is based on mass.

[Insulated wire]
The insulated wire of the present invention has a conductor and an insulating coating covering the outer periphery of the conductor. The insulating coating is a multi-layer insulating layer (multi-layer enamel layer) formed by repeatedly applying and baking a resin varnish.
It is preferable that the cross-sectional shape of the insulated wire of the present invention is similar to that of the conductor, and it is particularly preferable that the overall shape of the insulating coating, i.e., the cross-sectional shape of the outermost surface of the insulating coating opposite the conductor, is similar to that of the conductor. Note that the similar shape is not limited to a completely similar shape, and may be an approximately similar shape.

The following describes a preferred embodiment of the present invention with reference to the drawings. Note that the present invention is not limited to the embodiments described below, except as specified in the present invention. In addition, the explanations of the conductor, insulating film, and insulating layer described with reference to the drawings below are not limited to the forms shown in the drawings, but are applied as explanations of the configuration or invention-specific matters of the present invention.

Figure 1 is a cross-sectional view showing a schematic configuration example of an insulated wire 1 according to one embodiment of the present invention. The insulated wire 1 has a conductor 10 and an insulating coating 20 that contacts the conductor 10 and covers the circumferential surface of the conductor 10. In Figure 1, the conductor 10 is a conductor having a circular cross-sectional shape perpendicular to the longitudinal direction. The insulating coating 20 is a multi-layer insulating layer in which multiple insulating layers 21 are laminated and formed by applying and baking a resin varnish. Note that in Figure 1, some of the boundaries between the insulating layers 21 are omitted.

In the insulated wire 1 of the present invention, the average thickness of each insulating layer 21 constituting the insulating coating 20 (multilayer insulating layer) is controlled to be 3.0% or more relative to the thickness of the insulating coating 20. Therefore, for example, when the insulating coating 20 is a multilayer insulating layer of 25 layers consisting of insulating layers a1, a2, a3, ..., a23, a24, and a25, the sum of the thicknesses of the insulating layers a1, a2, a3, ..., a23, a24, and a25 divided by the number of layers 25 is the average thickness of each insulating layer 21, and this average value is 3.0% or more relative to the thickness of the insulating coating 20 (100 x the average value / thickness of the insulating coating ≧ 3.0). In other words, the "average thickness of each insulating layer constituting the insulating coating (multilayer insulating layer)" can be determined by measuring the thickness of each insulating layer and determining the arithmetic average value of each measured value obtained. In addition, a value calculated by dividing the thickness of the insulating coating 20 by the number of insulating layers 21 that constitute the insulating coating 20 is essentially the same as the "average thickness of each insulating layer that constitutes the insulating coating (multilayer insulating layer)." The number of insulating layers 21 can be determined by observing the cross section of the insulating coating 20 with an optical microscope or a microscope after etching.
The thickness (thickness of each layer) of each insulating layer 21 constituting the insulating coating 20 was measured at 16 points. The 16-point measurement is a commonly used measurement method in this field, and a specific measurement method is described in the pamphlet of International Publication No. WO 2013/073397.

In addition, in the insulated wire 1 of the present invention, the interlayer adhesion between the insulating layers 21 (i.e., the interlayer adhesion between the multilayer insulating layers) measured by the method described below is controlled to be 0.04 N/mm or more.
A preferred embodiment of the insulated wire 1 of the present invention will now be described.

<Conductor>
The conductor used in the insulated wire of the present invention may be any conductor that has been conventionally used as a conductor for an insulated wire, such as a metal conductor such as a copper wire or an aluminum wire.

The cross-sectional shape perpendicular to the longitudinal direction of the conductor used in the insulated wire of the present invention is not particularly limited. For example, a conductor having a circular or rectangular (rectangular) cross-sectional shape may be used. In the present invention, a conductor having a rectangular cross-sectional shape, i.e., a rectangular conductor, is preferred. A conductor having a rectangular cross-sectional shape has a higher space factor in the slots of the stator core than a conductor having a circular cross-sectional shape. For this reason, it is preferred for applications in which many insulated wires are incorporated in a certain narrow space.
A conductor having a rectangular cross section is preferably provided with four chamfered corners (with a radius of curvature r) in order to suppress partial discharge from the corners. The radius of curvature r is preferably 0.6 mm or less, and more preferably 0.2 to 0.4 mm.
The size of the conductor is not particularly limited, but in the case of a rectangular conductor, the width (long side) of the rectangular cross-sectional shape is preferably 1.0 to 10.0 mm, more preferably 1.0 to 5.0 mm, and even more preferably 1.4 to 4.0 mm, and the thickness (short side) is preferably 0.4 to 3.0 mm, and more preferably 0.5 to 2.5 mm. The ratio of the length of the width (long side) to the thickness (short side) (thickness:width) is preferably 1:1 to 1:20, and more preferably 1:1 to 1:4. On the other hand, in the case of a conductor having a circular cross-sectional shape, the diameter is preferably 0.3 to 3.0 mm, and more preferably 0.4 to 2.7 mm.

<Insulating film>
In the insulated wire of the present invention, the insulating coating is a multi-layer insulating layer in which a plurality of insulating layers are laminated, the insulating layers being formed by coating and baking a resin varnish.
The thickness of the insulating coating (total thickness of the multilayer insulating layer) is preferably 20 μm or more and 200 μm or less, more preferably 30 μm or more and 170 μm or less, and even more preferably 40 μm or more and 140 μm or less.

(Insulating layer)
The insulating layer is an enamel layer formed by applying a resin varnish containing an insulating resin (insulating polymer) onto a conductor and baking it. A thermoplastic resin such as a thermosetting resin or polyetherimide can be used to form the enamel layer, and an enamel layer formed by curing a thermosetting resin is preferred. Examples of the thermosetting resin used to form the enamel layer include polyimide (PI), polyamideimide (PAI), polyurethane, thermosetting polyester (PEst), H-type polyester (HPE), polybenzimidazole, polyesterimide (PEsI), melamine resin, and epoxy resin, and one or more of these can be used. Among them, polyimide (PI) and/or polyamideimide (PAI) are preferred, and polyimide (PI) is more preferred.

The type of the polyimide (PI) is not particularly limited, and any polyimide that is generally used as a material for an insulating film, such as a wholly aromatic polyimide or a thermosetting aromatic polyimide, can be used. In addition, a polyimide obtained by using a polyamic acid solution obtained by reacting an aromatic tetracarboxylic dianhydride with an aromatic diamine compound in a polar solvent in a conventional manner and imidizing the polyamic acid solution by a heat treatment during baking can be used.
Examples of commercially available polyimides (PI) include U-imide (trade name, manufactured by Unitika Ltd.) and U-Varnish (trade name, manufactured by Ube Industries Ltd.).

-Resin varnish-
As the resin contained in the resin varnish, the resins described above can be used.
Examples of the organic solvent (organic solvent) contained in the resin varnish and used to turn the resin into a varnish include amide-based solvents such as N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), and N,N-dimethylformamide (DMF); urea-based solvents such as N,N-dimethylethyleneurea, N,N-dimethylpropyleneurea, and tetramethylurea; lactone-based solvents such as γ-butyrolactone and γ-caprolactone; carbonate-based solvents such as propylene carbonate; methyl ethyl ketone; Examples of suitable organic solvents include ketones, cyclohexanone, and other ketone-based solvents, ethyl acetate, n-butyl acetate, butyl cellosolve acetate, butyl carbitol acetate, ethyl cellosolve acetate, ethyl carbitol acetate, and other ester-based solvents, diglyme, triglyme, tetraglyme, and other glyme-based solvents, toluene, xylene, cyclohexane, and other hydrocarbon-based solvents, cresol, phenol, halogenated phenol, and other phenol-based solvents, sulfone-based solvents, such as sulfolane, and dimethyl sulfoxide (DMSO). Among these, from the viewpoint of varnish stability due to hydrogen bonding with the resin, the organic solvent is preferably an aprotic solvent, preferably containing DMAc and/or NMP, and more preferably being DMAc and/or NMP.
The organic solvents and the like may be used alone or in combination of two or more kinds.

In the insulated wire of the present invention, the interlayer adhesion of the multilayer insulating layer is controlled to be 0.04 N/mm or more. The interlayer adhesion can also be controlled, for example, by adjusting the amount of residual solvent in the insulating coating (in each insulating layer). For example, from the viewpoint of improving the interlayer adhesion of the multilayer insulating layer, the amount of residual solvent in the insulating coating is preferably 500 to 20,000 ppm, more preferably 1,000 to 10,000 ppm, and even more preferably 2,000 to 5,000 ppm.
The amount of residual solvent can be adjusted to a desired level by, for example, changing the type of solvent in the resin varnish or by changing the baking conditions after applying the resin varnish. The amount of residual solvent can be measured by a conventional method, for example, by peeling the insulating coating from the insulated wire and measuring the amount using a gas chromatograph (model: GC-2010 Plus, manufactured by Shimadzu Corporation, carrier gas: nitrogen).

The resin varnish may contain various additives, such as adhesion aids, foaming agents for forming bubbles, antioxidants, antistatic agents, ultraviolet inhibitors, light stabilizers, fluorescent whitening agents, pigments, dyes, compatibilizers, lubricants, reinforcing agents, flame retardants, crosslinking agents, crosslinking aids, plasticizers, thickeners, viscosity reducers, and elastomers, as necessary. The resin varnish may also contain inorganic fine particles to the extent that they do not affect the properties. Examples of such inorganic fine particles include zinc oxide, titanium oxide, tin oxide, silicon carbide, and strontium titanate.

The number of repetitions of coating and baking the resin varnish to form the insulating film is not particularly limited, and can be appropriately set so as to satisfy the provisions of the present invention. In the present invention, the "number of repetitions of coating and baking" is synonymous with the number of layers of the multilayer insulating layer. For example, the number of repetitions of coating and baking can be 10 or more, 12 or more, or 15 or more. The number of repetitions can also be 35 or less, 30 or less, or 25 or less. The number of repetitions is preferably in the range of 10 to 35, more preferably 12 to 30, and even more preferably 15 to 25.
Similarly, the number of insulating layers constituting the insulating coating may be 10 or more, 12 or more, or 15 or more. The number of layers may be 35 or less, 30 or less, or 25 or less. A preferred range for the number of layers is 10 to 35, more preferably 12 to 30, and even more preferably 15 to 25.

The average thickness of each insulating layer constituting the insulating coating is preferably 2 μm or more, more preferably 3 μm or more, and even more preferably 4 μm or more. The average thickness is preferably 7 μm or less, more preferably 6 μm or less, and even more preferably 5 μm or less. The preferred range for the average thickness is 2 to 7 μm, more preferably 3 to 6 μm, and even more preferably 4 to 5 μm.

The thickness of each insulating layer constituting the insulating coating can be 1 μm or more, 2 μm or more, 3 μm or more, or 4 μm or more. The average thickness can be 10 μm or less, 9 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, or 5 μm or less. A preferred range for the average thickness is 1 to 10 μm, more preferably 2 to 9 μm, even more preferably 2 to 8 μm, even more preferably 3 to 7 μm, even more preferably 3 to 6 μm, and even more preferably 4 to 5 μm.

In the insulated wire of the present invention, the average thickness of each insulating layer constituting the insulating coating (multilayer insulating layer) relative to the thickness of the insulating coating is 3.0% or more as described above, and from the viewpoint of further improving the laser peelability of the insulating coating, it is more preferable that it is 3.5% or more, and even more preferable that it is 4.0% or more. In addition, the average thickness of each insulating layer constituting the insulating coating relative to the thickness of the insulating coating is usually 10.0% or less, may be 9.0% or less, and can also be 8.0% or less.

In the insulated wire of the present invention, the interlayer adhesion strength of the multilayer insulating layer is 0.04 N/mm or more as described above. From the viewpoint of both maintaining insulation properties and coating peelability, the adhesion strength is preferably 0.05 to 0.15 N/mm, more preferably 0.06 to 0.12 N/mm, even more preferably 0.07 to 0.10 N/mm, and even more preferably 0.08 to 0.10 N/mm.
The interlayer adhesion can be measured, for example, by the method described in the Examples.

The insulated wire of the present invention is preferably intended to be used after the end insulating coating is removed by laser light irradiation. For example, when welding the ends of the insulated wires together to electrically connect them, it is preferable that the end insulating coating is removed by laser light irradiation. In other words, according to one aspect of the present invention, the following laser-peelable insulating coating is provided.

A laser peelable insulating coating that covers the outer periphery of a conductor,
The insulating coating is a multi-layer insulating layer formed by repeatedly applying and baking a resin varnish on the outer periphery of the conductor,
the average thickness of each insulating layer constituting the multilayer insulating layer is 3.0% or more of the thickness of the insulating coating;
The insulating coating for laser peeling has an interlayer adhesion strength of 0.04 N/mm or more for the multilayer insulating layer.

Furthermore, from the viewpoint of enabling the insulating coating to efficiently absorb the energy of laser light and further improving laser peelability, the transmittance (T450, %) of the insulating coating at a wavelength of 450 nm is preferably 60% or less, more preferably 50% or less, even more preferably 40% or less, even more preferably 30% or less, even more preferably 20% or less, even more preferably 15% or less, even more preferably 13% or less, and even more preferably 10% or less.
The transmittance at a wavelength of 450 nm can be measured by the method described in the examples.

[Method of manufacturing insulated wire]
The insulated wire of the present invention can be obtained by forming a multi-layer insulating layer by a coating/baking process in which the operation of coating and baking a resin varnish on the outer periphery of a conductor is repeated multiple times. The resin varnish used in the coating/baking process may be the same for all insulating layers, or different types of resin varnish may be used for each insulating layer. The resin varnish described above can be used as the resin varnish.

The resin varnish can be applied to the conductor by any conventional method, such as using a varnish application die that is similar in shape to the conductor, or, if the cross-sectional shape of the conductor is rectangular, a die called a "universal die" that is shaped like a grid can be used.

The conductor coated with the resin varnish is baked in a baking oven in the usual manner. Specific baking conditions depend on the shape of the oven used, but in the case of a natural convection vertical oven of about 10 m, the baking conditions can be achieved by setting the oven temperature at 400 to 650° C. and the passage time at 10 to 90 seconds.
In addition, when the insulating coating of the insulated wire of the present invention contains polyimide and/or polyamideimide as the resin, the transmittance at the wavelength of 450 nm decreases as the imidization rate of the resin increases. Therefore, the baking conditions can be appropriately set so that the imidization rate of the resin increases to a certain degree. In addition, the baking conditions can be appropriately set so that the amount of residual solvent contained in the insulating coating falls within the above-described preferred range so that the interlayer adhesion of the multilayer insulating layer is not reduced.

[Coils, rotating electrical machines, and electrical/electronic devices]
The insulated wire of the present invention can be used as a coil in fields requiring electrical properties (voltage resistance) and heat resistance, such as rotating electrical machines and various electrical and electronic devices. For example, the insulated wire of the present invention can be used in motors, transformers, etc. to configure high-performance rotating electrical machines and electrical and electronic devices. In particular, the insulated wire can be suitably used as a winding for the drive motor of a hybrid vehicle (HV) or an electric vehicle (EV).

[coil]
The coil of the present invention may be formed by coiling the insulated electric wire of the present invention, or may be formed by bending the insulated electric wire of the present invention and then electrically connecting predetermined portions thereof.
The coil formed by coil processing the insulated electric wire of the present invention is not particularly limited, and may be a coil formed by winding a long insulated electric wire in a spiral shape. In such a coil, the number of turns of the insulated electric wire is not particularly limited. Usually, an iron core or the like is used to wind the insulated electric wire.
An example of the coil obtained by electrically connecting predetermined portions of the insulated electric wire of the present invention after bending is a coil used in a stator of a rotating electric machine or the like. For example, as shown in FIG. 2, the insulated electric wire 1 of the present invention is cut to a predetermined length to shorten (segment), the insulating coating 20 (end insulating coating) of the obtained segment is burned (pyrolyzed) by laser light irradiation to remove it, the conductor 10 is exposed (conductor exposed portion 34b), and the coil is bent into a U-shape or the like to form a plurality of segment coils (segment conductors) 34, and then the conductor exposed portions 34b of the two open ends (ends) 34a of the U-shape or the like of each segment coil 34 are welded and electrically connected alternately. The removal of the end insulating coating by the laser light irradiation can be performed after shortening the insulated electric wire 1 as shown in FIG. 2, or can be performed after the insulated electric wire 1 is incorporated into the slot 32 of the stator core 31 as the segment coil 34.

The method of removing the end insulating film by irradiating the laser light is disclosed in, for example, Japanese Patent Application Laid-Open No. 6-38330, Japanese Patent Application Laid-Open No. 2001-309521, and Japanese Patent Application Laid-Open No. 2005-285755. The removal of the end insulating film by irradiating the laser light may be performed by a laser device. The laser device may have, for example, a laser oscillator and be configured to be capable of outputting a laser light with a power of several kW. Alternatively, for example, the laser device may have a plurality of semiconductor laser elements therein and be configured to be capable of outputting a multi-mode laser light with a power of several kW as the total output of the plurality of semiconductor laser elements. The wavelength of the laser light may be 800 to 1200 nm, or 1000 to 1200 nm.
The laser device may have various laser light sources such as a fiber laser, a YAG (Yttrium Aluminum Garnet) laser, a disk laser, etc. The laser device may output a continuous wave of laser light or a pulse of laser light.

As described above, the insulated wire of the present invention is controlled so that the average thickness of each insulating layer relative to the thickness of the insulating coating is equal to or less than a specific value, and the interlayer adhesion of the multilayer insulating layer is equal to or greater than a specific value. This allows the insulating coating to be removed sufficiently in a short time by irradiating it with laser light. In addition, the reduction in the cross-sectional area of the conductor caused by excessive removal of the surface layer of the conductor, which was a problem in the conventional mechanical cutting method, is suppressed. In addition, no shavings of the conductor are generated, and there is no need to worry about wear of the mold used in the press processing. Therefore, it is possible to effectively improve the performance and manufacturing efficiency of coils, rotating electrical machines, and electrical and electronic devices using the insulated wire of the present invention.

[Rotary electric machines, electrical and electronic equipment]
The electric/electronic device having the coil of the present invention is not particularly limited. A preferred embodiment of such an electric/electronic device is a transformer. Another example is a rotating electric machine (particularly a drive motor for HVs and EVs) equipped with a stator 30 shown in FIG. 3. This rotating electric machine can have the same configuration as a conventional rotating electric machine, except that it is equipped with the stator 30.
The stator 30 can be configured in the same manner as a conventional stator, except that the segment coil 34 is formed of the insulated electric wire of the present invention. That is, the stator 30 has a stator core 31 and a coil 33 in which a segment coil 34 made of the insulated electric wire of the present invention is incorporated into a slot 32 of the stator core 31 and the open end 34a is electrically connected, as shown in FIG. 4. Here, the segment coil 34 may be incorporated into the slot 32 by itself, but is preferably incorporated as a set of two coils as shown in FIG. 4. In this stator 30, the coil 33 is formed by connecting the open end 34a, which is the two ends of the segment coil 34 bent as described above, in the slot 32 of the stator core 31. At this time, the open end 34a of the segment coil 34 may be connected before being housed in the slot 32, or the open end 34a of the segment coil 34 may be bent and connected after the segment coil 34 is housed in the slot 32.

[Manufacturing methods for rotating electrical machines and electrical/electronic devices]
In relation to the above-described embodiment, the present invention further provides the following manufacturing methods for rotating electrical machines and electric/electronic devices.

a step of removing an end insulating coating of a segment of the insulated electric wire of the present invention by irradiating the end insulating coating with a laser beam;
a step of forming the segment from which the end insulating coating has been removed into a coil shape to form a segment coil, and incorporating the segment coil into a slot of a stator core;
A method for manufacturing a rotating electric machine or an electrical/electronic device, comprising a step of welding the ends of the segment coils together to electrically connect them.

A step of forming a segment coil by processing the segment of the insulated wire of the present invention into a coil shape and incorporating the segment coil into a slot of a stator core;
removing an end insulating coating of the segment coil incorporated in the slot of the stator core by irradiating it with laser light;
A method for manufacturing a rotating electric machine or an electrical/electronic device, comprising a step of welding the ends of the segment coils together to electrically connect them.

The present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[Preparation of insulated wire]
Example 1
The conductor used was a copper conductor with a circular cross section (outer diameter of the cross section: 1 mm) and an oxygen content of 15 ppm.
Using a die in which the cross-sectional outer shape of the innermost insulating layer in contact with the conductor is similar to the cross-sectional shape of the conductor, polyimide resin varnish (product name: U-imide, manufactured by Unitika Ltd.) was applied to the surface of the conductor so that the average thickness (thickness after drying) of each insulating layer was the thickness shown in Table 1 below, and the conductor was passed through a baking furnace with a length of 10 m set at 520° C. at a speed that gave a passing time of 10 to 20 seconds. This application and baking was performed a total of 25 times to form an insulating coating (thickness: 100 μm) consisting of 25 polyimide insulating layers. In this way, the insulated wire of Example 1 was obtained. The thickness of each insulating layer was the same for all layers.

<Examples 2 to 5, Comparative Examples 1 to 4>
Insulated wires of Examples 2 to 5 and Comparative Examples 1 to 4 were obtained in the same manner as in Example 1, except that the thickness of the insulating coating, the average thickness of each insulating layer, the number of insulating layers, and the time of passing through the baking oven were set to the conditions shown in Table 1 below.

[Evaluation method]
The physical properties and characteristics of the insulating coatings of the obtained insulated wires of Examples 1 to 5 and Comparative Examples 1 to 4 were evaluated by the following tests. The results are shown in Table 1 below.

<Transmittance Measurement>
The insulating film was peeled off from each of the insulated wires of Examples 1 to 5 and Comparative Examples 1 to 4, and the transmittance (T450, %) of the insulating film at a wavelength of 450 nm was measured using an ultraviolet-visible-near infrared spectrophotometer (model number: V-630, manufactured by JASCO Corporation). The measured wavelength range was 200 to 800 nm, the measurement method was the transmission method, and the light source switching was 340 nm.

<Measurement of Interlayer Adhesion>
The interlayer adhesion was measured in part in accordance with Japanese Industrial Standard: JIS Z 0237 (2009).
The insulated wire produced above was cut with a cutter in the longitudinal direction from one end of the insulated wire, with two cuts of 1 mm width and 50 mm or more length (two cuts). The depth of the cut was controlled with a micrometer to a position from the surface of the insulating film to half the thickness of the insulating film, so that the cut did not reach the conductor. At the one end of the insulated wire, the insulating film was peeled off from the surface of the insulating film to the depth of the cut by a cut width of 1 mm, and a 180° peel test was performed in the longitudinal direction along the cut at a speed of 4 mm/min using a tensile tester (manufactured by Shimadzu Corporation, device name "Autograph AGS-J"). The average peel strength (irregularity average value) over a length of 50 mm was taken as the adhesion strength (interlayer adhesion force).

<Laser peeling test>
The insulated wires according to the examples and comparative examples were cut into segments each having a length of 70 mm, and the insulating coating covering the end portion of each segment was removed by irradiating the segment with an infrared laser beam having a wavelength of 1070 nm (output: 300 W, speed: 1500 mm/s). The time required for the insulating coating to be completely removed from the end of the insulated wire to a point 10 mm away was measured.

In the insulated wires of Comparative Examples 1 and 2, in which the ratio of the average thickness of the insulating layer to the thickness of the insulating coating ([B]/[A]×100) was less than 3.0%, it took 1.0 seconds or more to remove the insulating coating at the end of the insulated wire by laser light irradiation, and the interlayer adhesion between the insulating layers was also poor. In addition, the insulated wire of Comparative Example 3, although the ratio was 3.0% or more, was poor in the interlayer adhesion between the insulating layers (integrity of the entire insulating layer), and as a result, was poor in laser peelability. Furthermore, the insulated wire of Comparative Example 4, although excellent in the interlayer adhesion between the insulating layers, was poor in the laser peelability because the ratio was less than 3.0%.
In contrast, the insulated wires of Examples 1 to 5 all had a ratio value of 3.0% or more, and were excellent in interlayer adhesion between the insulating layers, and as a result, were excellent in laser peelability (the time required for peeling off the insulating coating by laser light irradiation was short).

REFERENCE SIGNS LIST 1 insulated wire 10 conductor 20 insulating coating 21 insulating layer 30 stator 31 stator core 32 slot 33 coil 34 segment coil 34a open end 34b exposed conductor portion 35 resin cap

Claims (11)

An insulated wire having a conductor and an insulating coating covering the outer periphery of the conductor,
The insulating coating is a multi-layer insulating layer formed by repeatedly applying and baking a resin varnish on the outer periphery of the conductor,
the average thickness of each insulating layer constituting the multilayer insulating layer is 3.0% or more of the thickness of the insulating coating;
The insulated wire has an interlayer adhesion strength of 0.04 N/mm or more for the multilayer insulating layer. The insulated wire according to claim 1, wherein the number of layers of the multilayer insulation is 25 or less. The insulated wire according to claim 1, wherein the transmittance of the insulating coating at a wavelength of 450 nm is 50% or less. The insulated wire according to claim 1, wherein the insulating coating comprises polyimide and/or polyamideimide. The insulated wire according to any one of claims 1 to 4, wherein the end insulating coating is laser peeled off before use. A coil using the insulated wire according to claim 5. A rotating electric machine having the coil according to claim 6. An electric/electronic device having the coil according to claim 6. A laser peelable insulating coating that covers the outer periphery of a conductor,
The insulating coating is a multi-layer insulating layer formed by repeatedly applying and baking a resin varnish on the outer periphery of the conductor,
the average thickness of each insulating layer constituting the multilayer insulating layer is 3.0% or more of the thickness of the insulating coating;
The insulating coating for laser peeling has an interlayer adhesion strength of 0.04 N/mm or more for the multilayer insulating layer. a step of removing an end insulating coating of the segment of the insulated electric wire according to claim 5 by irradiating the end insulating coating with a laser beam;
a step of forming the segment from which the end insulating coating has been removed into a coil shape to form a segment coil, and incorporating the segment coil into a slot of a stator core;
A method for manufacturing a rotating electric machine or an electrical/electronic device, comprising a step of welding the ends of the segment coils together to electrically connect them. A step of forming a segment coil by processing the segment of the insulated electric wire according to claim 5 into a coil shape and incorporating the segment coil into a slot of a stator core;
removing an end insulating coating of the segment coil incorporated in the slot of the stator core by irradiating it with laser light;
A method for manufacturing a rotating electric machine or an electrical/electronic device, comprising a step of welding the ends of the segment coils together to electrically connect them.

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