WO2022024181A1

WO2022024181A1 - Thermosetting resin composition, stator coil and rotary electric machine

Info

Publication number: WO2022024181A1
Application number: PCT/JP2020/028714
Authority: WO
Inventors: 暁紅殷; 貴裕馬渕; 壮平鮫島
Original assignee: 三菱電機株式会社
Priority date: 2020-07-27
Filing date: 2020-07-27
Publication date: 2022-02-03
Also published as: JP7262677B2; JPWO2022024181A1

Abstract

This thermosetting resin composition contains: a thermosetting resin (4); organic microfiller (5); and inorganic nanofiller (6). The thermosetting resin composition is used for making an insulation layer (3) for a stator coil of a rotary electric machine. The surface of the organic microfiller (5) is coated with an inorganic layer. The stator coil comprises: a conductive wire; and the insulation layer (3) that covers the conductive wire. The insulation layer (3) contains: the thermosetting resin (4); the organic microfiller (5); and the inorganic nanofiller (6).

Description

Thermosetting resin composition, stator coil and rotary electric machine

The present disclosure relates to a thermosetting resin composition, a stator coil provided with an insulating layer formed of the thermosetting resin composition, and a rotary electric machine provided with the stator coil.

As a stator coil of a conventional rotary electric machine, a structure having an insulating layer is known. In such a stator coil, a thermosetting resin composition is impregnated as an insulating varnish in a stator coil formed by winding a coil wire around a tooth of a stator core, and then the thermosetting resin composition is heated. It is obtained by forming an insulating layer by curing the coil.

Since the stator coil is exposed to high voltage during operation of the rotary electric machine, the insulating layer is required to have characteristics that can withstand high voltage for a long period of time. Further, in recent years, the electric field strength applied to the insulating layer tends to increase more and more as the rotary electric machine becomes smaller and more efficient. Therefore, a large number of insulating layers having improved long-term withstand voltage characteristics, that is, long-term withstand voltage characteristics, have been proposed.

For example, Patent Document 1 discloses a technique of using a thermosetting resin composition containing an epoxy resin, an inorganic nanofiller, and an inorganic microfiller as an insulating layer. In the technique disclosed in Patent Document 1, since the inorganic nanofiller and the inorganic microfiller exert an effect of suppressing the progress of the electric tree, which is an electrical destruction phenomenon, the long-term withstand voltage characteristics of the insulating layer can be improved. can.

Japanese Unexamined Patent Publication No. 2008-75069

However, since the thermosetting resin composition disclosed in Patent Document 1 contains an inorganic microfiller having a hard and brittle property, there is a risk that the toughness may decrease. Therefore, when the thermosetting resin composition disclosed in Patent Document 1 is used for the insulating layer of the stator coil of the rotary electric machine, cracks are likely to occur in the insulating layer due to the vibration generated during the operation of the rotary electric machine, and the insulating layer is insulated. There was a risk of shortening the insulation life of the layer.

The present disclosure has been made in view of the above, and an object of the present disclosure is to obtain a thermosetting resin composition capable of increasing toughness as compared with the conventional one.

In order to solve the above-mentioned problems and achieve the object, the thermosetting resin composition according to the present disclosure contains a thermosetting resin, an organic microfiller, and an inorganic nanofiller, and is a rotary electric machine. Used for the insulating layer of the stator coil of.

According to this disclosure, it has the effect of increasing toughness more than before.

Cross-sectional view of the servomotor according to the first embodiment cut along the central axis. FIG. 6 is a cross-sectional view of the servomotor according to the first embodiment cut in a direction orthogonal to the central axis, and is a partially enlarged cross-sectional view showing a stator. Sectional drawing which shows typically the coil wire in Embodiment 1. Sectional drawing which shows typically the organic microfiller in Embodiment 2. Sectional drawing which shows typically the coil wire in Embodiment 3. A graph showing the relationship between the volume ratio of the organic microfiller in the entire insulating layer of the third embodiment and the distance from the central axis along the radial direction of the enamel wire.

Hereinafter, the thermosetting resin composition, the stator coil, and the rotary electric machine according to the embodiment will be described in detail with reference to the drawings.

Embodiment 1.
In this embodiment, a case where the rotary electric machine is a servomotor 8 will be described as an example. FIG. 1 is a cross-sectional view of the servomotor 8 according to the first embodiment cut along the central axis C. The servomotor 8 includes a stator 9, a rotor 10, a shaft 11, a frame 12, and two brackets 13. The stator 9 is formed in a cylindrical shape having a central axis C. Hereinafter, when the direction of each component of the servomotor 8 is described, the direction parallel to the central axis C is the axial direction, the direction orthogonal to the central axis C is the radial direction, and the rotational direction about the central axis C is the circumferential direction. And.

The rotor 10 is arranged inside the stator 9. A gap is provided between the stator 9 and the rotor 10 over the entire circumference in the circumferential direction. A shaft 11 is connected to the center of the rotor 10. The shaft 11 and the central axis C of the stator 9 are provided coaxially. The rotor 10 can rotate with the central axis C as the rotation axis. The frame 12 constitutes the outer shell of the servomotor 8 and houses the stator 9 and the rotor 10. The frame 12 is formed in a cylindrical shape with both ends open along the axial direction. One bracket 13 is arranged so as to close the opening at one end of the frame 12 along the axial direction. The other bracket 13 is arranged so as to close the opening at the other end of the frame 12 along the axial direction. One end of the shaft 11 along the axial direction protrudes to the outside of the frame 12 through a hole 13a formed in one of the brackets 13.

The stator 9 includes a stator core 14 and a coil wire 1. FIG. 2 is a cross-sectional view of the servomotor 8 according to the first embodiment cut in a direction orthogonal to the central axis C, and is a partially enlarged cross-sectional view showing the stator 9. The stator core 14 has a cylindrical core back 15 made of a magnetic material, and a plurality of teeth 16 protruding inward in the radial direction from the inner peripheral surface of the core back 15. Slots 17 are formed between adjacent teeth 16. An insulator 18 is inserted in the slot 17. The insulator 18 covers the surface of the core back 15 facing the slot 17 and the surface of the teeth 16 facing the slot 17. A coil wire 1 is wound around each of the plurality of teeth 16 via an insulator 18, and a stator coil 19 is formed. A tape 20 is arranged between the stator coils 19 adjacent to each other in each slot 17. The tape 20 serves to electrically insulate between the adjacent stator coils 19. For example, a polyimide film or a polyester film is used as the material of the tape 20. The stator 9 is not limited to the illustrated example, and may be appropriately selected and used from known stators.

FIG. 3 is a cross-sectional view schematically showing the coil wire 1 in the first embodiment. The coil wire 1 includes an enamel wire 2 and an insulating layer 3 that covers the enamel wire 2. The enamel wire 2 is an insulating conducting wire in which the conductive core wire 21 is covered with the enamel layer 22. The core wire 21 is, for example, a copper wire. The enamel wire 2 is not limited to the illustrated example, and may be appropriately selected from known enamel wires and used.

The insulating layer 3 is formed of a thermosetting resin composition. The insulating layer 3 contains a thermosetting resin 4, an organic microfiller 5, and an inorganic nanofiller 6. The organic microfiller 5 and the inorganic nanofiller 6 are dispersed in the matrix of the thermosetting resin 4. Hereinafter, the components of the thermosetting resin composition used for the insulating layer 3 will be described in detail.

Epoxy resin, phenol resin, silicon resin, and imide resin are preferably used as the thermosetting resin 4 from the viewpoint of improving heat resistance, adhesiveness, electrical insulation, and mechanical strength, and epoxy resin is used. It is more preferable to be done. Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, biphenol type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, and bisphenol A type novolak type epoxy resin. Bisphenol F type novolak type epoxy resin, alicyclic epoxy resin, aliphatic chain epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, hidden in type epoxy resin, isocyanurate type epoxy resin, salicylaldehyde novolak type epoxy resin , Diglycidyl etherified products of bifunctional phenols, halides of bifunctional phenols, hydrogenated additives of bifunctional phenols, diglycidyl etherified products of bifunctional alcohols, halides of bifunctional alcohols, bifunctional alcohols Epoxy additives can be mentioned. These epoxy resins may be used alone or in combination of two or more. On the other hand, from the viewpoint of improving the balance between material cost, viscosity and heat resistance, it is preferable to use a reaction product of epichlorohydrin and a bisphenol A compound as the thermosetting resin 4.

Since the organic microfiller 5 has higher toughness than the inorganic nanofiller 6, it suppresses the generation of cracks in the insulating layer 3 even in an environment where vibration is generated by the operation of the servomotor 8 to insulate the insulating layer 3. It has the effect of improving the service life. Further, since the specific gravity of the organic microfiller 5 is substantially the same as that of the thermosetting resin 4, it is difficult for the organic microfiller 5 to settle in the thermosetting resin 4 during the impregnation treatment described later, and the organic microfiller 5 is uniformly contained in the thermosetting resin 4. It has the effect of being dispersed. Further, when the organic microfiller 5 is used in combination with the inorganic nanofiller 6, the thixophilicity of the thermosetting resin composition during the impregnation treatment is improved, and the workability during the impregnation treatment is significantly improved. It is effective.

For the organic microfiller 5, for example, a thermosetting resin polyimide resin, a polyimide amide resin, and a polyester imide resin are used. For the organic microfiller 5, it is preferable to use an insulating resin having a low dielectric constant and a high dielectric breakdown electric field strength, which has a lower dielectric constant than the thermosetting resin 4 and dielectric breakdown than the thermosetting resin 4. It is more preferable that a resin having a high electric field strength is used. For example, when a polyimide resin is used for the organic microfiller 5, it is preferable to use a polyimide resin having a low polyimide group concentration. Since the polyimide resin having a low polyimide group concentration has a low dielectric constant, it can be expected that the partial discharge start voltage (Partial Discharge Inception Voltage: PDIV) of the insulating layer 3 will be high, which has the effect of prolonging the insulating life of the insulating layer 3. Demonstrate.

Further, as the organic microfiller 5, a thermoplastic resin having a high melting point, a low dielectric constant, and a high dielectric breakdown electric field strength may be used. A high melting point means, for example, that the melting point is 200 ° C. or higher. Examples of such thermoplastic resins include engineering plastics and super engineer plastics. Examples of engineering plastics include polybutylene naphthalate having a melting point of 243 ° C., polybutylene terephthalate having a melting point of 224 ° C., polyethylene naphthalate having a melting point of 269 ° C., and polyethylene terephthalate having a melting point of 258 ° C. Examples of the super engineer plastic include polyphenylene sulfide having a melting point of 285 ° C., a thermoplastic polyimide having a melting point of 338 ° C., a polyetheretherketone having a melting point of 334 ° C., and a polyetherketone having a melting point of 373 ° C.

Further, it is preferable that a rod-shaped, fibrous, or scaly resin is used for the organic microfiller 5. When the organic microfiller 5 having such a shape is oriented in a certain direction, the failure path at the time of dielectric breakdown of the insulating layer 3 can be significantly extended as compared with the case where the spherical organic microfiller 5 is oriented in a certain direction. It can be expected to increase the dielectric breakdown voltage of the insulating layer 3. Further, it is preferable that a crystalline resin is used for the organic microfiller 5. When a crystalline resin is used, the dielectric breakdown electric field strength of the insulating layer 3 can be increased.

The volume content of the organic microfiller 5 in the entire thermosetting resin composition is preferably 1% by volume or more and 30% by volume or less, and more preferably 5% by volume or more and 20% by volume or less. The volume content of the organic microfiller 5 is a value obtained by dividing the volume of the organic microfiller 5 by the volume of the thermosetting resin composition as a percentage. The volume of the organic microfiller 5 is determined by dividing the mass of the powder of the organic microfiller 5 by the true density of the organic microfiller 5. When the volume content of the organic microfiller 5 is 1% by volume or more, the insulating performance of the thermosetting resin composition can be significantly improved. On the other hand, when the volume content of the organic microfiller 5 is 30% by volume or less, the viscosity of the thermosetting resin composition becomes low, and the thermosetting resin composition is easily impregnated into the stator coil 19.

For the inorganic nanofiller 6, for example, particles composed of either an oxide or a nitride, or a mixture of two or more thereof is used. Examples of the oxide include silica, alumina, titanium oxide, bismuth trioxide, cerium dioxide, cobalt monoxide, copper oxide, iron trioxide, formium oxide, indium oxide, manganese oxide, tin oxide, yttrium oxide, and zinc oxide. Can be mentioned. Each of these oxides may be used alone, or two or more of them may be used in combination. As the nitride, nitrides such as Ti, Ta, Nb, Mo, Co, Fe, Cr, V, Mn, Al, and Si are used. These nitrides may be used alone or in combination of two or more.

The volume content of the inorganic nanofiller 6 in the entire thermosetting resin composition is preferably 1% by volume or more and 20% by volume or less, and more preferably 3% by volume or more and 10% by volume or less. The volume content of the inorganic nanofiller 6 is a value obtained by dividing the volume of the inorganic nanofiller 6 by the volume of the thermosetting resin composition as a percentage. The volume of the inorganic nanofiller 6 is determined by dividing the mass of the powdered inorganic nanofiller 6 by the true density of the inorganic nanofiller 6. When the volume content of the inorganic nanofiller 6 is 1% by volume or more, the insulating performance of the thermosetting resin composition can be significantly improved. Here, the insulation performance is, for example, insulation life and partial discharge resistance. On the other hand, when the volume content of the inorganic nanofiller 6 is 20% by volume or less, the dispersibility of the inorganic nanofiller 6 in the entire thermosetting resin composition becomes the best.

The primary particle size of the inorganic nanofiller 6 is preferably in the range of 1 nm to 500 nm. If the primary particle size of the inorganic nanofiller 6 deviates from the range of 1 nm to 500 nm, the insulating performance of the thermosetting resin composition may be impaired and the workability during the impregnation treatment may be deteriorated. ..

The surface of the inorganic nanofiller 6 may be modified with a surface treatment agent. Here, the case where the inorganic nanofiller 6 is silica particles will be described as an example. The surface of the silica particles is usually covered with silanol groups, which makes them hydrophilic. Therefore, the surface of the silica particles may be hydrophobized using a surface treatment agent. The hydrophobization treatment means that the silanol group on the silica surface is reacted with a surface treatment agent and modified with a functional group such as a methyl group, a dimethyl group, a trimethyl group, an octyl group and an amino group. Further, the surface of the silica particles may be modified by using a surface treatment agent so as to improve the adhesion between the thermosetting resin 4 of the matrix and the silica particles.

Examples of the surface treatment agent include γ-glycidoxy-propyltrimethoxysilane, γ-aminopropyl-trimethoxysilane, vinyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-glycidyloxypropyl-trimethoxysilane, and the like. Examples thereof include silane coupling agents, titanate-based coupling agents, coupling agents such as aluminum-based coupling agents, aluminum laurate, aluminum stearate, iron alumina stearate, aluminum hydroxide, alumina, zirconia, and silicon. These surface treatment agents may be used alone or in combination of two or more.

Although not shown, a curing agent is added to the thermosetting resin composition in order to cure the thermosetting resin 4. As the curing agent for the resin, for example, an acid anhydride, an amine-based compound, and an imidazole-based compound are used. In addition, instead of the curing agent, a catalyst for curing the thermosetting resin 4 may be added.

Examples of the acid anhydride include hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, and methylnadic anhydride. These acid anhydrides may be used alone or in combination of two or more. The blending amount of the acid anhydride is not particularly limited, and may be appropriately adjusted according to the type of the acid anhydride used, the type of the thermosetting resin 4, and the like. For example, when a bisphenol type epoxy resin is used for the thermosetting resin 4, the amount of the acid anhydride is preferably 10 parts by mass to 150 parts by mass with respect to 100 parts by mass of the bisphenol type epoxy resin. , 30 parts by mass to 120 parts by mass, more preferably 50 parts by mass to 100 parts by mass. With such an amount of acid anhydride, the thermosetting resin composition can be appropriately cured. When a bisphenol type epoxy resin and a bisphenol type curing agent are used, the equivalent ratio of the acid anhydride group of the acid anhydride to the epoxy group of the epoxy resin is not particularly limited, but is 0.7 to 1.3. It is preferably 0.8 to 1.2, more preferably 0.9 to 1.1. If the equivalent ratio is less than 0.7, the workability when forming the insulating layer 3 tends to decrease. On the other hand, when the equivalent ratio exceeds 1.3, the heat resistance of the insulating layer 3 tends to decrease.

Examples of amine-based compounds include ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, hexamethylenediamine, diproprenedamine, polyetherdiamine, 2,5-dimethylhexamethylenediamine, and trimethylhexamethylenediamine. Diethylenetriamine, iminobispropylamine, bis (hexamethyl) triamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, aminoethylethanolamine, tri (methylamino) hexane, dimethylaminopropylamine, diethylaminopropylamine, methylimino Bispropylamine, mensendiamine, isophoronediamine, bis (4-amino-3-methyldicyclohexyl) methane, diaminodicyclohexylmethane, bis (aminomethyl) cyclohexane, N-aminoethylpiperazine, 3,9-bis (3) -Aminopropyl) 2,4,8,10-Tetraoxaspiro (5,5) Undecane, m-xylenediamine, metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulphon, diaminodiethyldiphenylmethane, dicyandiamide, organic acid dihydrazide. ..

Examples of the imidazole-based compound include 2-methylimidazole, 2-undecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, and 2-phenyl-. Examples thereof include 4-methylimidazole, 1-benzyl-2-methylimidazole and 1-benzyl-2-phenylimidazole.

A reactive diluent may be added to the curing agent. As the reactive diluent, a styrene monomer, a monomer having a hydrocarbon functional group added to the phenyl group thereof, a methacrylic monomer, or an acrylic monomer is used. The methacrylic monomer is not particularly limited as long as it does not impair the curing of the epoxy resin, and examples thereof include linear methacrylate, branched methacrylate, and cyclic methacrylate. From the viewpoint of heat resistance, it is preferable to use linear methacrylate as the methacrylic monomer. Examples of the linear methacrylate include lauryl methacrylate, isobornyl methacrylate, tetrahydrofurfuryl methacrylate, 2-hydroxyethyl methacrylate, benzyl methacrylate, and cyclohexyl methacrylate. These linear methacrylates may be used alone or in combination of two or more. The acrylic monomer is not particularly limited as long as it does not impair the curing of the epoxy resin, and examples thereof include linear acrylates, branched acrylates, and cyclic acrylates. From the viewpoint of heat resistance, it is preferable to use a linear acrylate as the acrylic monomer. Examples of the linear acrylate include 2-ethylhexyl acrylate, cyclohexyl acrylate, diethylene glycol mono2-ethylhexyl ether acrylate, diethylene glycol monophenyl ether acrylate, tetraethylene glycol monophenyl ether acrylate, trimethyl propantriacrylate, lauryl acrylate, and isobol. Nyl acrylate, 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, 2-hydroxypropyl acrylate, benzyl acrylate, 2- (2,4,6-tribromophenoxy) ethyl acrylate can be mentioned. These linear acrylates may be used alone or in combination of two or more. The blending amount of the reactive diluent is not particularly limited and may be appropriately adjusted.

In addition to the above-mentioned components, various additives may be added to the thermosetting resin composition of the present embodiment as long as the effects of the present embodiment are not impaired. Examples of such additives include defoaming agents, leveling agents, solvents, and dispersants.

Next, a method of manufacturing the stator coil 19 according to the present embodiment will be described. The method for manufacturing the stator coil 19 includes a shear dispersion step, a mixing step, and a coating step.

The shear dispersion step is a step in which the inorganic nanofiller 6 shown in FIG. 3 is added to the thermosetting resin 4, sheared, and dispersed in the thermosetting resin 4. Since the inorganic nanofiller 6 is usually aggregated as secondary particles or tertiary particles before being added to the thermosetting resin 4, the secondary particles or tertiary particles of the inorganic nanofiller 6 are subjected to the shear dispersion step. Need to be crushed and dispersed in the thermosetting resin 4. By appropriately setting the shear dispersion conditions, the aggregated state and the dispersed state of the inorganic nanofiller 6 can be adjusted. In the shear dispersion step, the thermosetting resin 4 and the inorganic nanofiller 6 are mixed by the shearing force. The device used in the shear dispersion step is not particularly limited as long as it is a mixing device that can apply a shearing force to the inorganic nanofiller 6, and may be appropriately selected from known devices. Examples of the apparatus used in the shear dispersion step include a wet high pressure shear dispersion apparatus.

The mixing step is a step of adding the organic microfiller 5 and the curing agent to the thermosetting resin 4 in which the inorganic nanofiller 6 is dispersed and mixing them. By the mixing step, the organic microfiller 5 and the curing agent are dispersed in the thermosetting resin 4. The method of mixing the organic microfiller 5 and the curing agent with the thermosetting resin 4 is not particularly limited, and may be appropriately selected from known methods. For example, after adding the organic microfiller 5 and the curing agent to the thermosetting resin 4, the organic microfiller 5 may be mixed with the curing agent and the thermosetting resin 4 using a machine such as a stirrer. The thermosetting resin composition can be obtained by the above shear dispersion step and mixing step.

The coating step is a step of applying the thermosetting resin composition to the stator coil 19. The method for applying the thermosetting resin composition is not particularly limited, and may be appropriately selected from known methods. As a method of applying the thermosetting resin composition, for example, there is a method of immersing the stator coil 19 in a container containing the thermosetting resin composition. Examples of the impregnation treatment method include vacuum impregnation, vacuum pressure impregnation, and normal pressure impregnation. The conditions of the impregnation treatment are not particularly limited, and may be appropriately set according to the type of the thermosetting resin composition, the enamel wire 2, and the like. Further, as a method of applying the thermosetting resin composition, there is a method of dropping the thermosetting resin composition onto the stator coil 19. By heating and curing the thermosetting resin composition after the coating step, the stator coil 19 provided with the insulating layer 3 is obtained. The thickness of the insulating layer 3 is not particularly limited, and may be appropriately set according to the size of the stator coil 19 to be manufactured and the like.

Next, the effect of the thermosetting resin composition according to the present embodiment will be described.

In the present embodiment, as shown in FIG. 3, the thermosetting resin composition contains a thermosetting resin 4, an organic microfiller 5, and an inorganic nanofiller 6. Since the thermosetting resin composition containing the organic microfiller 5 is used for the insulating layer 3, the insulating layer 3 is compared with the case where the thermosetting resin composition containing the inorganic microfiller is used for the insulating layer. Can increase toughness. As a result, it is possible to suppress the occurrence of cracks in the insulating layer 3 due to vibration generated during the operation of the servomotor 8, so that the insulating life of the insulating layer 3 can be extended. Further, when the thermosetting resin composition containing the organic microfiller 5 and the inorganic nanofiller 6 is used for the insulating layer 3 of the stator coil 19, the electric tree, which is an electrical destruction phenomenon of the insulating layer 3, is used. Since the progress can be suppressed, the long-term withstand voltage characteristics of the insulating layer 3 can be improved.

In the present embodiment, the thermosetting resin composition of the present disclosure is used for the insulating layer 3 of the stator coil 19 of the servomotor 8, but the rotation of an electric motor, a generator, a compressor, etc. other than the servomotor 8 is performed. The thermosetting resin composition of the present disclosure may be used for the insulating layer of the stator coil of the machine.

Embodiment 2.
FIG. 4 is a cross-sectional view schematically showing the organic microfiller 5 in the second embodiment. The second embodiment is different from the first embodiment in that the surface of the organic microfiller 5 is coated with the inorganic layer 7. In the second embodiment, the same reference numerals are given to the parts overlapping with the first embodiment, and the description thereof will be omitted.

The surface of the organic microfiller 5 is coated with an inorganic layer 7 formed of an inorganic material. The inorganic layer 7 is a thin-film insulating layer thinner than the organic microfiller 5, and exhibits the effect of improving the withstand voltage characteristics of the insulating layer 3. For the inorganic layer 7, for example, a substance selected from the group consisting of silica and alumina may be used, or a substance selected from the group consisting of oxides and nitrides may be used. The thickness of the inorganic layer 7 is preferably in the range of 0.1 μm to 1.5 μm, and more preferably in the range of 0.5 μm to 1.0 μm. If the thickness of the inorganic layer 7 is less than 0.1 μm, the effect of improving the withstand voltage characteristics of the insulating layer 3 may be reduced. Therefore, the thickness of the inorganic layer 7 is preferably 0.1 μm or more. , 0.5 μm or more is more preferable. On the other hand, if the thickness of the inorganic layer 7 exceeds 1.5 μm, the possibility of cracks in the inorganic layer 7 increases. Therefore, the thickness of the inorganic layer 7 is preferably 1.5 μm or less, preferably 1.0 μm. The following is more preferable.

Next, the coating process of coating the surface of the organic microfiller 5 with the inorganic layer 7 will be described. The coating step may be performed before the above-mentioned mixing step. Examples of the method of coating the surface of the organic microfiller 5 with the inorganic layer 7 include a dipping method in which the organic microfiller 5 is immersed in the inorganic coating agent and a method of spraying the organic microfiller 5 with the inorganic coating agent. Inorganic coating agents include a high-temperature firing type, a low-temperature type in which the curing temperature is suppressed by adding a catalyst, and a normal temperature type. As the inorganic coating agent, it is preferable to use a low temperature type or a normal temperature type having a heat resistant temperature of the organic microfiller 5 or less. The term "heat resistant temperature or lower" means, for example, 250 ° C. or lower.

Here, the principle of improving the withstand voltage characteristics of the insulating layer 3 by the inorganic layer 7 will be described. In general, inorganic materials are higher than organic materials in terms of dielectric breakdown electric field strength. Therefore, by adding an inorganic material to the thermosetting resin, the withstand voltage characteristics of the insulating layer 3 can be improved. On the other hand, in terms of static strength, inorganic materials are higher than organic materials, but in terms of dynamic strength and toughness, organic materials are higher than inorganic materials. That is, the inorganic material has both a hard property and a brittle property. Therefore, when an inorganic material is added to the thermosetting resin, the toughness of the insulating layer 3 is lowered, the insulating layer 3 becomes brittle, and the insulating layer 3 is liable to crack due to the vibration generated during the operation of the servomotor 8. .. Therefore, in the present embodiment, as a method of overcoming the brittle property of the inorganic material while utilizing the high withstand voltage characteristics of the inorganic material, the surface of the organic microfiller 5 is formed by the thin film-like inorganic layer 7 formed of the inorganic material. I took the method of coating. When the thin-film inorganic layer 7 is used, cracks are less likely to occur in the inorganic layer 7, and the inorganic layer 7 does not form in the path through which the cracks propagate, so that a decrease in the mechanical strength of the insulating layer 3 can be suppressed. As described above, in the present embodiment, the surface of the organic microfiller 5 is coated with the thin-film inorganic layer 7, so that the withstand voltage characteristics of the insulating layer 3 and the withstand voltage characteristics of the insulating layer 3 are not impaired without impairing the mechanical strength of the insulating layer 3. The insulation life can be improved.

Embodiment 3.
FIG. 5 is a cross-sectional view schematically showing the coil wire 1 in the third embodiment. FIG. 6 is a graph showing the relationship between the volume ratio of the organic microfiller 5 in the entire insulating layer 3 of the third embodiment and the distance from the central axis C1 along the radial direction of the enamel wire 2. In the third embodiment, the volume ratio of at least one of the organic microfiller 5 and the inorganic nanofiller 6 in the entire insulating layer 3 is increased as the enamel wire 2 is closer to the central axis C1. Is different from. In the third embodiment, the same reference numerals are given to the parts overlapping with the first embodiment, and the description thereof will be omitted. In the present embodiment, only the volume ratio of the organic microfiller 5 in the entire insulating layer 3 is higher as it is closer to the central axis C1 of the enamel wire 2, and the volume ratio of the inorganic nanofiller 6 in the entire insulating layer 3 is the radius of the enamel wire 2. The case where the volume is uniform regardless of the distance from the central axis C1 along the direction will be described as an example.

As shown in FIG. 5, the enamel wire 2 is formed in a cylindrical shape having a central axis C1. FIG. 5 illustrates two lines corresponding to the X-axis of FIG. 6 that pass through the central axis C1 and extend in the radial direction. As the organic microfiller 5, the organic microfiller 5 of the above-described first embodiment may be used, or the organic microfiller 5 coated with the inorganic layer 7 of the above-mentioned embodiment 2 may be used. .. The vertical axis of FIG. 6 shows the volume ratio of the organic microfiller 5 in the entire insulating layer 3. The horizontal axis of FIG. 6 indicates the distance from the central axis C1 along the radial direction of the enamel wire 2. 0 (zero) on the horizontal axis of FIG. 6 indicates the central axis C1 of the enamel wire 2, and means that the farther away from 0 (zero) along the horizontal axis, the more it is located on the outer side in the radial direction of the coil wire 1. A shown in FIGS. 5 and 6 represents the position of the most radial innermost portion of the insulating layer 3, that is, the position of the interface between the insulating layer 3 and the enamel wire 2. Further, B shown in FIGS. 5 and 6 represents the position of the outermost portion of the insulating layer 3 in the radial direction, that is, the position of the outer peripheral portion of the insulating layer 3. As shown in FIG. 6, the volume ratio of the organic microfiller 5 in the entire insulating layer 3 increases from B to A. That is, the volume ratio of the organic microfiller 5 in the entire insulating layer 3 is higher as it is closer to the central axis C1 of the enamel wire 2.

Next, the method of forming the insulating layer 3 in the present embodiment will be described. Generally, the stator coil 19 is impregnated with the thermosetting resin composition, and then the thermosetting resin composition is heated and cured to form the insulating layer 3. In this respect, in the present embodiment, it is necessary to change the volume ratio of the organic microfiller 5 in the entire insulating layer 3 depending on the distance from the central axis C1 along the radial direction of the enamel wire 2. Therefore, the above-mentioned impregnation treatment is performed. It will be divided into multiple times. First, the stator coil 19 is impregnated with a thermosetting resin composition having a high content of the organic microfiller 5, and the insulating layer 3 is thinly formed on the surface of the stator coil 19. As a method of forming the insulating layer 3 thinly, there is a method of adding a diluent to the thermosetting resin composition to appropriately adjust the viscosity of the thermosetting resin composition. Further, as another method of forming the insulating layer 3 thinly, there is a method of reducing the thickness of the insulating layer 3 by subjecting the insulating layer 3 to a vibration treatment or a decentering treatment before drying. Subsequently, the stator coil 19 is impregnated with a thermosetting resin composition having a lower content of the organic microfiller 5 than the previous impregnation treatment. The thickness of the insulating layer 3 can be adjusted by the method described above. The impregnation treatment may be performed a plurality of times. As described above, by performing the impregnation treatment a plurality of times and reducing the content of the organic microfiller 5 in the entire thermosetting resin composition as the number of impregnation treatments is repeated, the central axis C1 of the enamel wire 2 is formed. The closer it is, the higher the volume ratio of the organic microfiller 5 can be formed in the insulating layer 3.

Here, the principle of improving the withstand voltage characteristic of the insulating layer 3 of the present embodiment will be described. By adding the organic microfiller 5 to the thermosetting resin 4, the withstand voltage characteristics of the insulating layer 3 can be improved. As the amount of the organic microfiller 5 added increases, the withstand voltage characteristics of the insulating layer 3 can be improved. On the other hand, the shorter the distance from the interface between the insulating layer 3 and the enamel wire 2, the stronger the electric field strength applied to the insulating layer 3. Therefore, the dielectric breakdown of the insulating layer 3 can be suppressed by increasing the volume ratio of the organic microfiller 5 as it is closer to the interface with the enamel wire 2 in the insulating layer 3. On the other hand, even if the volume ratio of the organic microfiller 5 is lowered as the distance from the interface between the insulating layer 3 and the enamel wire 2 of the insulating layer 3 is longer, the dielectric breakdown of the insulating layer 3 can be suppressed.

Generally, the coefficient of thermal expansion of the thermosetting resin 4 is higher than the coefficient of thermal expansion of the enamel wire 2. Further, the coefficient of thermal expansion of the organic microfiller 5 and the inorganic nanofiller 6 is lower than the coefficient of thermal expansion of the thermosetting resin 4. Therefore, by adding the organic microfiller 5 and the inorganic nanofiller 6 to the thermosetting resin 4, the coefficient of thermal expansion of the thermosetting resin composition approaches the coefficient of thermal expansion of the enamel wire 2. Therefore, in the process of impregnating the stator coil 19 with the thermosetting resin composition, the thermal stress generated due to the difference in the thermal expansion rate between the enamel wire 2 and the thermosetting resin composition is relaxed. Can be done. Further, during the operation of the servomotor 8, the thermal stress generated between the enamel wire 2 and the insulating layer 3 due to the difference in the thermal expansion rate when energized can be relaxed. Then, by relaxing these thermal stresses, the thermal strain of the insulating layer 3 can be reduced, and by extension, the probability of occurrence of mechanical defects can be reduced. As a result, the withstand voltage characteristics and the insulation life of the insulating layer 3 can be improved.

As described above, in the present embodiment, the volume ratio of the organic microfiller 5 in the entire insulating layer 3 is higher as it is closer to the central axis C1 of the enamel wire 2, thereby improving the withstand voltage characteristics and the insulating life of the insulating layer 3. be able to.

Although the volume ratio of the organic microfiller 5 in the entire insulating layer 3 is higher as it is closer to the central axis C1 of the enamel wire 2, at least one of the organic microfiller 5 and the inorganic nanofiller 6 in the entire insulating layer 3 is configured. The closer the volume ratio is to the central axis C1 of the enamel wire 2, the higher it is. That is, the configuration may be such that only the volume ratio of the inorganic nanofiller 6 in the entire insulating layer 3 is closer to the central axis C1 of the enamel wire 2. Further, the volume ratio of both the organic microfiller 5 and the inorganic nanofiller 6 in the entire insulating layer 3 may be higher as it is closer to the central axis C1 of the enamel wire 2. The stator coil 19 having these configurations is obtained by the above-mentioned impregnation treatment method. Further, even with these configurations, the withstand voltage characteristics and the insulation life of the insulating layer 3 can be improved.

Next, the effects of the present disclosure will be further described with reference to Examples and Comparative Examples.

(Example 1)
100 parts by mass of bisphenol A type epoxy resin as a thermosetting resin and 90 parts by mass of methyl-1,2,3,6-tetrahydrophthalic anhydride as a curing agent were mixed and stirred, and then defoamed. To the mixture thus obtained, 5% by volume of nanosilica particles having an average primary particle size of 40 nm were added as an inorganic nanofiller, and the mixture was stirred at 2000 rpm for 2 minutes using a rotating and revolving stirrer. The mixture thus obtained was subjected to shear dispersion treatment under the conditions of 200 MPa or less using a wet high-pressure shear dispersion device. To the mixture thus obtained, 10% by volume of polyimide fine particles having an average particle size of 5 μm and an average length of 50 μm were added as an organic microfiller, and the mixture was stirred at 2000 rpm for 2 minutes using a rotating revolution type stirrer. did. A thermosetting resin composition was obtained by adding 3 parts by mass of an imidazole-based curing agent to the mixture thus obtained, stirring the mixture, and then performing a vacuum degassing treatment.

Next, a twisted pair cable was produced using an enamel wire having a polyamide-imide film as an enamel coating in accordance with JIS C2103. The prepared twisted pair cable was impregnated with the thermosetting resin composition described above, and then heated at 180 ° C. for 5 hours to form an insulating layer on the surface of the twisted pair. The thickness of the insulating layer was about 600 μm. In Example 1, the volume ratio of the organic microfiller in the entire insulating layer was uniform over the entire insulating layer.

(Example 2)
As the organic microfiller, a twisted pair cable having an insulating layer formed in the same manner as in Example 1 was obtained, except that the polyimide fine particles whose surface was coated with silica were used instead of the polyimide fine particles of Example 1. The thickness of the inorganic layer formed of silica was about 1 μm.

(Example 3)
As the organic microfiller, the same organic microfiller as in Example 2 was used. In addition, the volume ratio of the organic microfiller in the entire insulating layer is increased as it is closer to the central axis of the enamel wire. In Example 3, the step method impregnation treatment method shown below was used as a method of changing the volume ratio of the organic microfiller in the entire insulating layer depending on the distance from the central axis of the enamel wire along the radial direction of the enamel wire. The step method impregnation treatment method includes a first step, a second step, and a third step. In the first step, the twisted pair cable is impregnated with a thermosetting resin composition containing an organic microfiller having a first volume ratio to form a first insulating layer on the surface of the twisted pair cable. In the second step, the twisted pair cable is impregnated with a thermosetting resin composition containing an organic microfiller having a second volume ratio lower than that of the first volume ratio, and a second insulating layer is formed on the surface of the twisted pair cable. Form. In the third step, the twisted pair cable is impregnated with a thermosetting resin composition containing no organic microfiller to form a third insulating layer on the surface of the twisted pair cable. As a result, a twisted pair cable having a first insulating layer, a second insulating layer, and a third insulating layer formed was obtained. The volume ratio of the organic microfiller in the entire first insulating layer was 20%. The volume ratio of the organic microfiller in the entire second insulating layer was 10%. The volume ratio of the organic microfiller in the entire third insulating layer was 0%. The thicknesses of the first insulating layer, the second insulating layer, and the third insulating layer were almost uniform, and each was about 200 μm. The above-mentioned step method impregnation treatment method is an example, and is not intended to limit the method of changing the volume ratio of the organic microfiller depending on the distance from the central axis of the enamel wire along the radial direction of the enamel wire.

(Comparative Example 1)
A twisted pair cable having an insulating layer formed in the same manner as in Example 1 was obtained in the same manner as in Example 1 except that an inorganic microfiller was used instead of the polyimide fine particles of Example 1. As the inorganic microfiller, spherical silica particles having an average particle size of about 8 μm were used.

(Test method)
The fracture toughness, the breakdown voltage, the insulation life, and the partial discharge start voltage were measured for each of the twisted pair cables on which the insulating layers of Examples 1 to 3 and Comparative Example 1 were formed by the test methods shown below.

[Fracture toughness]
According to ASTM _D5045-91 , an initial crack was generated in the compact tension test piece, a tensile load was applied, and the fracture toughness value (KIC) was calculated from the load when the crack developed and broke. The moving speed of the crosshead was 1 mm / min, and the measurement temperature was room temperature.

[Break voltage]
Using an insulation breakdown voltage measuring device manufactured by Yamayo Tester Co., Ltd., an AC voltage of a sinusoidal wave of 50Hz is applied between the conductors of the twist pair cable at a boosting speed of 500V / sec, and the voltage is continuously boosted while breaking the insulation. The effective value was measured. The measurement temperature was room temperature.

[Insulation life]
Using a withstand voltage tester manufactured by Yamayo Tester Co., Ltd., an AC voltage of 2 kV / 50 Hz was applied between the conductors of the twisted pair cable, and the time for destruction was measured. The measurement temperature was room temperature.

[Partial discharge start voltage]
Using a partial discharge tester manufactured by Mitsubishi Electric Wire Co., Ltd., an AC voltage of 50 Hz sine wave is applied between the conductors of the twist pair cable, and the effective value of the voltage when the discharge charge amount is 10 pC is measured while continuously boosting the voltage. did. The measurement temperature was room temperature.

Table 1 shows the evaluation results for Examples 1 to 3 and Comparative Example 1. In Table 1, each characteristic value of Comparative Example 1 is set to 1, and each characteristic value of Examples 1 to 3 is shown in a ratio with that of Comparative Example 1. The larger the numerical value of each physical property value, the better the characteristics.

As is clear from Table 1, Examples 1 to 3 in which the insulating layer of the twisted pair cable is formed by using the thermosetting resin composition containing the organic microfiller are the thermosetting resin compositions containing the inorganic microfiller. Compared with Comparative Example 1 in which the insulating layer of the twisted pair cable was formed using the above, high values were shown in all the evaluation items of breaking toughness, breaking voltage, insulation life and partial discharge start voltage. From this, it can be seen that the organic microfiller is effective in improving the toughness of the insulating layer, improving the withstand voltage characteristics of the insulating layer, and improving the insulating life of the insulating layer.

Consider the effect of the presence of the inorganic layer on the withstand voltage characteristics and insulation life of the insulating layer. The only difference between Examples 1 and 2 is the presence or absence of an inorganic layer. Example 2 in which the surface of the organic microfiller was coated with the inorganic layer showed higher numerical values in the evaluation items of fracture voltage and insulation life as compared with Example 1 in which the surface of the organic microfiller was not coated with the inorganic layer. .. From this, it can be seen that the inorganic layer that coats the surface of the organic microfiller is effective in improving the withstand voltage characteristics of the insulating layer and improving the insulating life of the insulating layer.

Consider the effect of the volume ratio of the organic microfiller on the withstand voltage characteristics of the insulating layer and the insulation life. Example 3 in which the volume ratio of the organic microfiller in the entire insulating layer is higher as it is closer to the central axis of the enamel wire is compared with Example 2 in which the volume ratio of the organic microfiller in the entire insulating layer is uniform over the entire insulating layer. Then, high values were shown in the evaluation items of breakdown voltage and insulation life. From this, it is effective to increase the volume ratio of the organic microfiller in the entire insulating layer toward the central axis of the enamel wire in order to improve the withstand voltage characteristics of the insulating layer and the insulating life of the insulating layer. I understand.

The configuration shown in the above embodiments is an example, and can be combined with another known technique, can be combined with each other, and does not deviate from the gist. It is also possible to omit or change a part of the configuration.

1 coil wire, 2 enamel wire, 3 insulating layer, 4 thermosetting resin, 5 organic microfiller, 6 inorganic nanofiller, 7 inorganic layer, 8 servo motor, 9 stator, 10 rotor, 11 shaft, 12 frame, 13 brackets, 13a holes, 14 stator cores, 15 core backs, 16 teeth, 17 slots, 18 insulators, 19 stator coils, 20 tapes, 21 core wires, 22 enamel layers.

Claims

Thermosetting resin and
With organic microfiller
Contains inorganic nanofillers,
A thermosetting resin composition characterized by being used for an insulating layer of a stator coil of a rotary electric machine.
The thermosetting resin composition according to claim 1, wherein the surface of the organic microfiller is coated with an inorganic layer.
The thermosetting resin composition according to claim 2, wherein the thickness of the inorganic layer is in the range of 0.1 μm to 1.5 μm.
With conductors
With an insulating layer covering the conductor,
The insulating layer is
Thermosetting resin and
With organic microfiller
A stator coil characterized by containing an inorganic nanofiller.
The stator coil according to claim 4, wherein the volume ratio of at least one of the organic microfiller and the inorganic nanofiller is higher as it is closer to the central axis of the conducting wire.
With a stator core with multiple teeth,
A rotary electric machine comprising the stator coil according to claim 4 or 5, which is formed in each of the plurality of teeth.