Stator and inverter motor

Abstract

Provided is a stator comprising: a stator core having a plurality of slot parts; a plurality of electric wires accommodated in the slot parts; and a thermosetting resin part formed between the electric wires. Each of the electric wires includes: a core wire; and a fluororesin layer that contains a fluororesin and forms the outermost circumferential surface of the electric wire. The thermosetting resin part is formed of a thermosetting resin.

Description

Stator and inverter motor

[0001] This disclosure relates to stator and inverter motors.

[0002] Patent Document 1 describes an electrical equipment insulating resin composition in which, when applied to electrical equipment and cured by heating to perform electrical insulation treatment, the weight loss rate of the electrical equipment insulating resin composition during the curing process is 5% or less.

[0003] Japanese Patent Publication No. 2009-117335

[0004] The purpose of this disclosure is to provide a stator that can be used in a motor.

[0005] According to this disclosure, a stator is provided comprising a stator core having a plurality of slots, a plurality of electric wires housed in the slots, and a thermosetting resin portion formed between the electric wires, wherein the electric wires comprise a core wire and a fluororesin layer containing fluororesin that forms the outermost surface of the electric wires, and the thermosetting resin portion is formed of a thermosetting resin.

[0006] According to this disclosure, a stator that can be used in a motor can be provided.

[0007] Figure 1 is a schematic cross-sectional view of a stator according to one embodiment. Figure 2 is a schematic diagram illustrating a method for attaching an electric wire to a jig used to measure the bonding force between a fluororesin layer and a cured thermosetting resin.

[0008] The following describes specific embodiments of this disclosure in detail, but this disclosure is not limited to the embodiments described below.

[0009] The stator of this disclosure comprises a stator core having a plurality of slots, a plurality of electric wires housed in the slots, and a thermosetting resin portion formed between the electric wires. Furthermore, in the stator of this disclosure, the electric wires comprise a core wire and a fluororesin layer, the fluororesin layer containing fluororesin and forming the outermost surface of the electric wires. The thermosetting resin portion is formed of a thermosetting resin.

[0010] Patent Document 1 describes impregnating the voids in the slots of a stator core with varnish (a resin composition for insulating electrical equipment). However, Patent Document 1 does not consider the configuration of the electric wires inserted into the slots.

[0011] Polyamide-imide wire, polyimide wire, and polyester-imide wire are known to be used as the wires that make up the stator coil. However, these wires have the problem of not having sufficient insulation.

[0012] The stator of this disclosure uses a wire having a fluororesin layer forming the outermost surface of the wire. Since the fluororesin layer has excellent insulating and heat-resistant properties, using the stator of this disclosure makes it possible to increase the voltage, output, and size of the motor.

[0013] Furthermore, in the stator of this disclosure, since a thermosetting resin portion is formed to fill the spaces between multiple wires housed in the slot portion, the wires are fixed to each other, the free movement of the wires can be suppressed, and motor vibration can be suppressed.

[0014] An embodiment of the stator of this disclosure will be described with reference to Figure 1.

[0015] The stator used in inverter motors and the like comprises a coil section formed by winding electric wires around a cylindrical stator core. The electric wires are formed, for example, by bending a predetermined length of flat wire into a roughly U-shape. The roughly U-shaped electric wires are inserted into a pair of slots so as to straddle the teeth section, thereby forming the coil section.

[0016] Figure 1 is a schematic cross-sectional view of a stator according to one embodiment. As shown in Figure 1, the stator 1 comprises a cylindrical stator core 10, the stator core 10 comprising an annular yoke portion 11, teeth portions 12 provided at equal intervals on the inner circumference of the stator core 10, and slot portions 13 provided between the teeth portions 12. The stator core 10 also comprises a coil portion 14 composed of electric wires 21 housed and wound around a pair of slot portions 13 that straddle the teeth portions 12.

[0017] As shown in Figure 1, thermosetting resin parts 22 are provided between the electric wires 21, fixing the electric wires 21 together. By fixing the electric wires 21 together, the free movement of the electric wires 21 is suppressed, thereby suppressing wear caused by friction between the electric wires 21 and vibration of the motor caused by the shaking of the electric wires 21.

[0018] Insulating paper (not shown) may be provided between the electric wire 21 and the inner surface of the slot portion 13 (the wall surface of the yoke portion 11 and the wall surface of the teeth portion 12). Also, in the slot portion 13 of the stator core 10 shown in Figure 1, the thermosetting resin portion 22 is provided only between the electric wires 21, but the thermosetting resin portion 22 may also be provided between the electric wire 21 and the inner surface of the slot portion 13. With this configuration, the electric wires 21 are fixed to each other, and the electric wires 21 are fixed to the stator core 10, so not only is it possible to prevent the electric wires 21 from coming out of the slot portion 13, but the free movement of the electric wires 21 is further suppressed.

[0019] In one embodiment, 50% or more of the surface area of ​​the electric wire 21 housed in the slot portion 13 is covered by the thermosetting resin portion 22. The proportion of the area covered by the thermosetting resin portion 22 is more preferably 60% or more, even more preferably 70% or more, preferably 100% or less, more preferably 98% or less, and even more preferably 95% or less, relative to the surface area of ​​the electric wire 21.

[0020] The ratio of the area covered by the thermosetting resin portion 22 to the total surface area of ​​the electric wire 21 can be calculated by taking a cross-section of any electric wire housed in the slot portion and determining the ratio of the surface area of ​​the electric wire where the thermosetting resin is present in that cross-section.

[0021] In one embodiment, the space occupied by the electric wire 21 in the slot portion 13 is preferably 40% or more, more preferably 60% or more, even more preferably 70% or more, and may be 99% or less, 95% or less, or 90% or less.

[0022] The stator of this disclosure can be suitably used in motors such as inverter motors, generators, inductors, and other electrical or electronic equipment. Furthermore, the stator of this disclosure can be suitably used in automotive electrical equipment or automotive electronic equipment such as automotive motors, automotive generators, and automotive inductors.

[0023] In one embodiment, the drive voltage of a motor equipped with the stator of the present disclosure is 100V or more, preferably 300V or more, and more preferably 400V or more. In one embodiment, when the wires of the stator are round wires, the drive voltage of a motor equipped with the stator of the present disclosure is 100V or more, preferably 300V or more, and more preferably 500V or more. In one embodiment, when the wires of the stator are flat rectangular wires, the drive voltage of a motor equipped with the stator of the present disclosure is 400V or more, preferably 500V or more, and more preferably 700V or more.

[0024] In one embodiment, the output of the motor equipped with the stator of the present disclosure is 10 kW or more, preferably 50 kW or more, more preferably 100 kW or more, and even more preferably 150 kW or more.

[0025] Next, we will explain the thermosetting resin parts and the electric wires in more detail.

[0026] 1. Thermosetting resin portion: The thermosetting resin portion is a part formed of thermosetting resin between multiple electric wires housed in the slot portion.

[0027] In one embodiment, the thermosetting resin portion is formed by curing a thermosetting resin composition containing a thermosetting resin. In this disclosure, the term "thermosetting resin composition" is used for convenience even when the thermosetting resin composition contains only a thermosetting resin. Therefore, the thermosetting resin portion may be a portion formed by curing only a thermosetting resin, or a portion formed by curing a composition containing a thermosetting resin and other components other than a thermosetting resin.

[0028] The viscosity of the thermosetting resin composition at 25°C is preferably 0.5 to 20 Pa·s. More preferably, the viscosity of the thermosetting resin composition at 25°C is 1.0 Pa·s or more, even more preferably 1.5 Pa·s or more, even more preferably 2.0 Pa·s or more, even more preferably 15.0 Pa·s or less, and even more preferably 10.0 Pa·s or less.

[0029] The viscosity of a thermosetting resin composition at 25°C can be measured in accordance with JIS C2105.

[0030] In the stator of this disclosure, electric wires are used whose outermost surface is formed of a fluororesin layer. Because fluororesins are non-adhesive, there is a problem in that it is difficult to firmly bond electric wires whose outermost surfaces are formed of a fluororesin layer together. By using a thermosetting resin composition having a viscosity within the above range, the fluororesin layer forming the outermost surface of the electric wire and the thermosetting resin part can be firmly bonded together. Therefore, since the fluororesin layer and the thermosetting resin part are less likely to peel off, the free movement of the electric wires can be suppressed for a long period of time, and as a result, the increase in motor vibration can be suppressed for a long period of time. If the viscosity of the thermosetting resin composition at 25°C is too low, the molecular weight of the thermosetting resin becomes small, making it difficult to firmly bond electric wires together, or the cured product may shrink easily during curing, which may adversely affect the performance of the motor.

[0031] The heat resistance temperature of the thermosetting resin is preferably 155°C or higher. More preferably 170°C or higher, even more preferably 180°C or higher, preferably 300°C or lower, more preferably 280°C or lower, and even more preferably 270°C or lower. By having the heat resistance temperature of the thermosetting resin within the above range, even when the motor generates heat and the stator becomes hot due to increased voltage and power output of the motor, the fixing of the wires housed in the slots can be maintained.

[0032] The heat resistance temperature of a thermosetting resin is the temperature of the thermosetting resin (cured product) forming the thermosetting resin portion or the cured product obtained by curing the thermosetting resin in a thermosetting resin composition. The heat resistance temperature of a thermosetting resin can be measured in accordance with UL1446.

[0033] The volume resistivity of the thermosetting resin is preferably 1.0 × 10⁻⁶. １５ It is Ω·cm or greater. The volume resistivity of the thermosetting resin is more preferably 1.5 × 10⁻⁶. １５ The density is Ω·cm or greater, and more preferably 2.0 × 10⁻⁶. １５ The density is Ω·cm or greater, preferably 1.0 × 10⁻⁶. １７ It is less than or equal to Ω·cm, and more preferably 8.0 × 10 １６ It is less than or equal to Ω·cm.

[0034] The volume resistivity of a thermosetting resin is the volume resistivity of the thermosetting resin (cured product) forming the thermosetting resin portion or the cured product obtained by curing the thermosetting resin in a thermosetting resin composition. The volume resistivity of a thermosetting resin can be measured in accordance with JIS C2139 3-1.

[0035] The dielectric breakdown strength of the thermosetting resin is preferably 15 kV / mm or more. More preferably 17 kV / mm or more, even more preferably 20 kV / mm or more, preferably 40 kV / mm or less, more preferably 38 kV / mm or less, and even more preferably 35 kV / mm or less.

[0036] The dielectric breakdown strength of a thermosetting resin is the dielectric breakdown strength of the thermosetting resin (cured product) forming the thermosetting resin portion or the cured product obtained by curing the thermosetting resin in a thermosetting resin composition. The dielectric breakdown strength of a thermosetting resin can be measured in accordance with JIS C2103. As motors are made higher voltage and more powerful, high voltage currents flow through the wires. However, if the volume resistivity and dielectric breakdown strength of the thermosetting resin are within the above range, it is easy to maintain high insulation performance between the wires and between the wires and the stator. Furthermore, when motors are miniaturized, the thickness of the thermosetting resin portion filling the spaces between multiple wires, and the thermosetting resin portion filling the space between the wires and the stator, becomes thinner. Therefore, if the volume resistivity and dielectric breakdown strength of the thermosetting resin are within the above range, it is easy to maintain insulation between the wires and between the wires and the stator. It also becomes easier to reduce the thickness of the wire coating layer.

[0037] The decomposition temperature of 1% by mass of the thermosetting resin is preferably 200°C or higher. More preferably, the decomposition temperature of 1% by mass of the thermosetting resin is 210°C or higher, even more preferably 220°C, still more preferably 230°C or higher, preferably 300°C or lower, more preferably 290°C or lower, and still more preferably 280°C or lower. By having the decomposition temperature of 1% by mass of the thermosetting resin within the above range, the fixing of the wires housed in the slots can be maintained even when the motor generates heat and the stator becomes hot.

[0038] The 1% by mass decomposition temperature of a thermosetting resin is the 1% by mass decomposition temperature of the thermosetting resin (cured product) forming the thermosetting resin portion or the cured product obtained by curing the thermosetting resin in a thermosetting resin composition. The 1% by mass decomposition temperature of a thermosetting resin can be determined by using a thermogravimetric differential thermal analyzer (TG-DTA) to heat the cured thermosetting resin from 25°C to 600°C at a heating rate of 10°C / min and measuring the temperature at which the mass of the heated cured product decreases by 1% by mass.

[0039] The curing shrinkage rate of the thermosetting resin composition is preferably 15% or less. The curing shrinkage rate of the thermosetting resin composition is preferably 10.0% or less, more preferably 5.0% or less, and the lower limit is not particularly limited and may be 0%.

[0040] The curing shrinkage rate of a thermosetting resin composition can be calculated from the specific gravity (B) of the thermosetting resin composition before curing and the specific gravity (C) of the cured product obtained by curing the thermosetting resin composition using the following formula: Curing shrinkage rate (%) = (Specific gravity (C) - Specific gravity (B)) / Specific gravity (C) × 100 Specific gravity (B): Specific gravity of the thermosetting resin before curing, measured at 25 degrees Celsius in accordance with JIS C2103 5.2.1 Pycnometer method Specific gravity (C): Specific gravity of the thermosetting resin after curing, measured using an electronic balance hydrometer (manufactured by METTLER TOLEDO) By having the curing shrinkage rate of the thermosetting resin within the above range, the fluororesin layer forming the outermost surface of the electric wire and the thermosetting resin part can be firmly bonded together in one layer. Therefore, since the fluororesin layer and the thermosetting resin part are less likely to peel off, the free movement of the electric wires can be further suppressed over a long period of time, and as a result, the increase in motor vibration can be further suppressed over a long period of time.

[0041] The thermosetting resin is preferably at least one selected from the group consisting of epoxy resins, polyimide resins, polyurethanes, and silicones, and more preferably at least one selected from the group consisting of epoxy resins and polyimide resins.

[0042] As the epoxy resin, at least one selected from the group consisting of modified epoxy resin, epoxy resin, epoxy acrylate resin, and epoxy ester resin is preferred, at least one selected from the group consisting of epoxy resin, epoxy acrylate resin, and epoxy ester resin is more preferred, and epoxy resin is even more preferred. Modified epoxy resin is a resin obtained by adding a modified resin to epoxy resin or by changing the resin skeleton. In this disclosure, epoxy resin is unmodified epoxy resin. Compared to modified epoxy resin, epoxy resin (unmodified epoxy resin) is preferred because it can firmly bond wires together and the cured product does not shrink easily during curing.

[0043] As the polyimide resin, at least one selected from the group consisting of polyimide and polyamideimide is preferred.

[0044] The thermosetting resin portion may contain components other than the thermosetting resin. A thermosetting resin portion containing components other than the thermosetting resin can be formed, for example, by curing a thermosetting resin composition containing the thermosetting resin and the other components.

[0045] Other components include inorganic fillers. Examples of inorganic fillers include metal oxides, calcium carbonate, talc, alumina, aluminum hydroxide, magnesium hydroxide, glass powder, titanium dioxide, glass fibers, fibrous materials, potassium titanate fibers, crystalline silica, and fused silica.

[0046] When the thermosetting resin portion contains an inorganic filler, the amount of inorganic filler is preferably 0.01% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, preferably 80% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less, relative to the mass of the thermosetting resin portion.

[0047] The thermosetting resin portion can be formed, for example, by housing the electric wire in the slot portion, impregnating the slot portion with a thermosetting resin composition, and then curing the thermosetting resin composition.

[0048] 2. The stator of the wire disclosed herein comprises a core wire and a fluororesin layer.

[0049] (Core wire) The core wire may be a single wire, a bundled wire, a stranded wire, etc., but a single wire is preferred. The cross-sectional shape of the core wire may be either roughly rectangular or roughly circular, but a roughly rectangular shape is preferred.

[0050] The core wire is preferably made of a conductive material, and can be made of materials such as copper, copper alloys, aluminum, aluminum alloys, iron, silver, and nickel, with copper, copper alloys, aluminum, or aluminum alloys being more preferable. A core wire with plating such as silver plating or nickel plating can also be used. For copper, oxygen-free copper, low-oxygen copper, and copper alloys can be used.

[0051] When the cross-section of the core wire is approximately rectangular, that is, when the core wire is a flat rectangular wire, the width of the cross-section of the core wire may be 1 to 75 mm, and the thickness of the cross-section of the core wire may be 0.1 to 30 mm. The outer diameter of the core wire may be 6.5 mm or more and 200 mm or less. Also, the ratio of width to thickness may be greater than 1 and 30 or less.

[0052] When the cross-section of the core wire is approximately circular, that is, when the core wire is a round wire, the diameter of the core wire is preferably 0.1 to 10 mm, and more preferably 0.3 to 3 mm.

[0053] The surface roughness Sz of the core wire is preferably 0.2 to 12 μm, more preferably 1 μm or more, even more preferably 5 μm or more, and more preferably 10 μm or less, in order to ensure that the core wire and the fluororesin layer adhere more firmly.

[0054] The surface roughness of the core wire can be adjusted by surface treatment methods such as etching, blasting, and laser treatment. Alternatively, surface treatment may create irregularities on the core wire surface. The distance between protrusions is preferably small, for example, 5 μm or less. The size of the irregularities should be such that, for example, the area of ​​each recess when a protrusion is cut relative to the unprocessed surface is 1 μm. ２The following applies: The uneven shape may be a single crater-like shape, or it may be branched like an ant's nest.

[0055] (Fluororesin layer) The fluororesin layer contains fluororesin, is formed around the core wire, and forms the outermost surface of the electric wire. The fluororesin layer may be formed directly on the core wire, or it may be formed on the core wire via other layers other than the fluororesin layer. If the electric wire has other layers other than the fluororesin layer, the fluororesin layer is provided as the outermost layer.

[0056] The fluororesin contained in the fluororesin layer is typically a melt-processable fluororesin. Melt-processability means that the polymer can be melted and processed using conventional processing equipment such as extruders and injection molding machines. Therefore, melt-processable fluororesins typically have a melt flow rate of 0.01 to 500 g / 10 min, as measured by the measurement method described later.

[0057] The melt flow rate of the fluororesin is preferably 0.1 to 120 g / 10 min, more preferably 80 g / 10 min or less, even more preferably 70 g / 10 min or less, preferably 5 g / 10 min or more, and more preferably 10 g / 10 min or more. By having the melt flow rate of the fluororesin within the above range, the fluororesin layer can be easily formed, and the resulting fluororesin layer has excellent mechanical strength.

[0058] In this disclosure, the melt flow rate of the fluororesin is a value obtained in accordance with ASTM D1238, using a melt indexer (manufactured by Yasuda Seiki Seisakusho Co., Ltd.) as the mass of polymer flowing out of a nozzle with an inner diameter of 2.1 mm and a length of 8 mm per 10 minutes at 372°C and a load of 5 kg (g / 10 min).

[0059] The melting point of the fluororesin is preferably 200 to 322°C, more preferably 210°C or higher, even more preferably 220°C or higher, still more preferably 250°C or higher, particularly preferably 280°C or higher, and more preferably 320°C or lower.

[0060] The melting point can be measured using a differential scanning calorimeter [DSC].

[0061] Examples of fluororesins with melt processability include tetrafluoroethylene (TFE) / fluoroalkyl vinyl ether (FAVE) copolymers, tetrafluoroethylene (TFE) / hexafluoropropylene (HFP) copolymers, TFE / ethylene copolymers [ETFE], TFE / ethylene / HFP copolymers, ethylene / chlorotrifluoroethylene (CTFE) copolymers [ECTFE], polychlorotrifluoroethylene [PCTFE], CTFE / TFE copolymers, polyvinylidene fluoride [PVdF], TFE / vinylidene fluoride (VdF) copolymers [VT], polyvinyl fluoride [PVF], TFE / VdF / CTFE copolymers [VTC], TFE / HFP / VdF copolymers, and the like.

[0062] As fluororesins, at least one selected from the group consisting of TFE / FAVE copolymers and TFE / HFP copolymers is preferable because they are excellent in heat resistance, moldability, and electrical properties.

[0063] The TFE / FAVE copolymer is a copolymer containing tetrafluoroethylene (TFE) units and fluoroalkyl vinyl ether (FAVE) units.

[0064] As the FAVE constituting the FAVE unit, the general formula (1): CF ２ =CFO(CF ２ CFY １ O) ｐ -(CF ２ CF ２ CF ２ O) ｑ -Rf (1) (In the formula, Y １ represents F or CF ３ and Rf represents a perfluoroalkyl group having 1 to 5 carbon atoms. p represents an integer of 0 to 5, and q represents an integer of 0 to 5.) The monomer represented by, and the general formula (2): CFX = CXOCF ２ OR １ (2) (In the formula, X is the same or different and represents H, F, or CF ３ and R １This represents a linear or branched fluoroalkyl group having 1 to 6 carbon atoms, which may contain 1 to 2 atoms selected from the group consisting of H, Cl, Br, and I, or a cyclic fluoroalkyl group having 5 or 6 carbon atoms, which may contain 1 to 2 atoms selected from the group consisting of H, Cl, Br, and I.) A possible example is at least one selected from the group consisting of monomers represented by ).

[0065] Among the FAVEs, monomers represented by general formula (1) are preferred, at least one selected from the group consisting of perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether) (PEVE), and perfluoro(propyl vinyl ether) (PPVE) is more preferred, at least one selected from the group consisting of PEVE and PPVE is even more preferred, and PPVE is particularly preferred.

[0066] The FAVE unit content of the TFE / FAVE copolymer is preferably 1.0 to 30.0 mol%, more preferably 1.2 mol% or more, even more preferably 1.4 mol% or more, still more preferably 1.6 mol% or more, particularly preferably 1.8 mol% or more, more preferably 3.5 mol% or less, still more preferably 3.2 mol% or less, still more preferably 2.9 mol% or less, and particularly preferably 2.6 mol% or less, relative to the total monomer units.

[0067] The TFE unit content of the TFE / FAVE copolymer is preferably 99.0 to 70.0 mol%, more preferably 96.5 mol% or more, even more preferably 96.8 mol% or more, still more preferably 97.1 mol% or more, particularly preferably 97.4 mol% or more, more preferably 98.8 mol% or less, still more preferably 98.6 mol% or less, still more preferably 98.4 mol% or less, and particularly preferably 98.2 mol% or less, relative to the total monomer units.

[0068] In this disclosure, the content of each monomer unit in the copolymer is: １９ Measurement is performed using the F-NMR method.

[0069] The TFE / FAVE copolymer may also contain monomer units derived from monomers copolymerizable with TFE and FAVE. In this case, the content of monomers copolymerizable with TFE and FAVE is preferably 0 to 29.0 mol%, more preferably 0.1 to 5.0 mol%, and even more preferably 0.1 to 1.0 mol%, relative to the total monomer units of the TFE / FAVE copolymer.

[0070] Monomers copolymerizable with TFE and FAVE include HFP and CZ. １ Z ２ = CZ ３ (CF ２ ) ｎ Z ４ (In the formula, Z １ Z ２ and Z ３ These represent H or F, and Z, either identical or different. ４ ) represents a vinyl monomer, and CF ２ = CF - OCH ２ -Rf １ (wherein, Rf １ ∫ represents a perfluoroalkyl group having 1 to 5 carbon atoms. Examples include alkyl perfluorovinyl ether derivatives represented by ∫, monomers having functional groups, etc. Among these, HFP is preferred.

[0071] The TFE / FAVE copolymer is preferably at least one selected from the group consisting of a copolymer consisting only of TFE units and FAVE units, and the TFE / HFP / FAVE copolymer described above, and more preferably a copolymer consisting only of TFE units and FAVE units.

[0072] The melting point of the TFE / FAVE copolymer is preferably 240 to 322°C, more preferably 285°C or higher, more preferably 320°C or lower, even more preferably 315°C or lower, and particularly preferably 310°C or lower, from the viewpoint of heat resistance and stress crack resistance. The melting point can be measured using a differential scanning calorimeter (DSC).

[0073] The glass transition temperature (Tg) of the TFE / FAVE copolymer is preferably 70 to 110°C, more preferably 80°C or higher, and more preferably 100°C or lower. The glass transition temperature can be measured by dynamic viscoelasticity measurement.

[0074] The relative permittivity of the TFE / FAVE copolymer is preferably 2.4 or less, more preferably 2.1 or less, and while there is no particular lower limit, it is preferably 1.8 or more. The relative permittivity is a value obtained by measuring the change in resonant frequency and electric field strength at a temperature of 20 to 25°C using a network analyzer HP8510C (manufactured by Hewlett-Packard) and a cavity resonator.

[0075] TFE / HFP copolymers are copolymers containing tetrafluoroethylene (TFE) units and hexafluoropropylene (HFP) units.

[0076] The HFP unit content of the TFE / HFP copolymer is preferably 0.1 to 30.0 mol%, more preferably 0.7 mol% or more, even more preferably 1.4 mol% or more, and more preferably 10.0 mol% or less, relative to the total monomer units.

[0077] The TFE unit content of the TFE / HFP copolymer is preferably 70.0 to 99.9 mol%, more preferably 90.0 mol% or more, more preferably 99.3 mol% or less, and even more preferably 98.6 mol%, relative to the total monomer units.

[0078] The TFE / HFP copolymer may also contain monomer units derived from monomers copolymerizable with TFE and HFP. In this case, the content of monomers copolymerizable with TFE and HFP is preferably 0 to 29.9 mol%, more preferably 0.1 to 5.0 mol%, and even more preferably 0.1 to 1.0 mol%, relative to the total monomer units of the TFE / HFP copolymer.

[0079] Monomers copolymerizable with TFE and HFP include FAVE and CZ. １ Z ２ = CZ ３ (CF ２) ｎ Z ４ (In the formula, Z １ Z ２ and Z ３ These represent H or F, and Z, either identical or different. ４ ) represents a vinyl monomer, and CF ２ = CF - OCH ２ -Rf １ (wherein, Rf １ ∫ represents a perfluoroalkyl group having 1 to 5 carbon atoms. Examples include alkyl perfluorovinyl ether derivatives represented by ∫, monomers having functional groups, etc. Among these, FAVE is preferred.

[0080] The melting point of the TFE / HFP copolymer is preferably 200 to 322°C, more preferably 210°C or higher, even more preferably 220°C or higher, particularly preferably 240°C or higher, more preferably 320°C or lower, even more preferably less than 300°C, and particularly preferably 280°C or lower.

[0081] The glass transition temperature (Tg) of the TFE / HFP copolymer is preferably 60 to 110°C, more preferably 65°C or higher, and more preferably 100°C or lower.

[0082] It is preferable that the fluororesin has functional groups. The presence of functional groups in the fluororesin allows for strong adhesion between the core wire and the fluororesin layer.

[0083] Functional groups include carbonyl group-containing groups, amino groups, hydroxyl groups, and -CF groups. ２ At least one selected from the group consisting of H groups, olefin groups, epoxy groups, and isocyanate groups is preferred.

[0084] A carbonyl group-containing group is a group that contains a carbonyl group (-C(=O)-) in its structure. Examples of carbonyl group-containing groups include carbonate groups [-O-C(=O)-OR ３ (In the formula, R ３(This is an alkyl group having 1 to 20 carbon atoms or an alkyl group having 2 to 20 carbon atoms containing an ether-bonded oxygen atom), Acyl group [-C(=O)-R ３ (In the formula, R ３ (This is an alkyl group having 1 to 20 carbon atoms or an alkyl group having 2 to 20 carbon atoms containing an ether-bonded oxygen atom) Haloformyl group [-C(=O)X ５ , X ５ [Halogen atom], formyl group [-C(=O)H], formula: -R ４ -C(=O)-R ５ (In the formula, R ４ R is a divalent organic group having 1 to 20 carbon atoms. ５ (A is a monovalent organic group with 1 to 20 carbon atoms) The group is represented by the formula: -O-C(=O)-R ６ (In the formula, R ６ (This refers to groups represented by alkyl groups having 1 to 20 carbon atoms or alkyl groups having 2 to 20 carbon atoms containing an ether-bonded oxygen atom), carboxyl groups [-C(=O)OH], alkoxycarbonyl groups [-C(=O)OR ７ (In the formula, R ７ (A is a monovalent organic group with 1 to 20 carbon atoms), carbamoyl group [-C(=O)NR ８ R ９ (In the formula, R ８ and R ９ Examples include: (which may be the same or different, and is a monovalent organic group having 1 to 20 hydrogen atoms or carbon atoms), acid anhydride bond [-C(=O)-O-C(=O)-], etc.

[0085] R ３ Specific examples include methyl group, ethyl group, propyl group, isopropyl group, and butyl group. ４ Specific examples include the methylene group and -CF ２ - group, -C ６ H ４ - Examples include the group, R ５ Specific examples include methyl, ethyl, propyl, isopropyl, and butyl groups. ７Specific examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and the like. Further, R ８ and R ９ Specific examples thereof include a hydrogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a phenyl group, and the like.

[0086] The hydroxy group is a group represented by -OH or a group containing a group represented by -OH. In the present disclosure, -OH constituting the carboxyl group is not included in the hydroxy group. Examples of the hydroxy group include -OH, a methylol group, an ethyrol group, and the like.

[0087] The olefin group (Olefinic group) is a group having a carbon-carbon double bond. Examples of the olefin group include the following formula: -CR １０ =CR １１ R １２ (In the formula, R １０ , R １１ and R １２ may be the same or different, and are a hydrogen atom, a fluorine atom or a monovalent organic group having 1 to 20 carbon atoms.) Functional groups represented by are included, and -CF=CF ２ , -CH=CF ２ , -CF=CHF, -CF=CH ２ and -CH=CH ２ At least one selected from the group consisting of is preferred.

[0088] The isocyanate group is a group represented by -N=C=O.

[0089] Further, as the functional group, a non-fluorinated alkyl group or a partially fluorinated alkyl group such as a -CH ３ group and a -CFH ２ group can also be mentioned.

[0090] The number of functional groups of the fluororesin is preferably 5 to 2,000 per 10 carbon atoms so that the core wire and the fluororesin layer are firmly adhered to each other. The number of functional groups is 10 carbon atoms ６ per, and preferably 5 to 2,000. The number of functional groups is 10 carbon atoms ６Per unit, more preferably 50 or more, still more preferably 100 or more, particularly preferably 200 or more, more preferably 1500 or less, still more preferably 1300 or less, particularly preferably 1100 or less, and most preferably 1000 or less.

[0091] Also, since the number of functional groups of the fluororesin can form a coating layer having excellent electrical properties, it may be less than 5 per 10 carbon atoms. ６ Per unit, less than 5 may be acceptable.

[0092] The above functional groups are functional groups present at the main chain end or side chain end of the copolymer (fluororesin), and functional groups present in the main chain or side chain, and are preferably present at the main chain end. Examples of the above functional groups include -CF=CF, -CFH, -COF, -COOH, -COOCH, -CONH, -OH, -CH2OH, etc., and at least one selected from the group consisting of -CFH, -COF, -COOH, -COOCH and -CH2OH is preferable. -COOH includes a dicarboxylic acid anhydride group (-CO-O-CO-) formed by bonding two -COOHs. ２ -CF ２ H, -COF, -COOH, -COOCH ３ , -CONH ２ , -OH, -CH ２ OH, etc., and -CF ２ H, -COF, -COOH, -COOCH ３ and -CH ２ OH are preferably at least one selected from the group consisting of. -COOH includes a dicarboxylic acid anhydride group (-CO-O-CO-) formed by bonding two -COOHs.

[0093] Infrared spectroscopy can be used to identify the type of the above functional groups and measure the number of functional groups.

[0094] Specifically, the number of functional groups is measured by the following method. First, the copolymer is melted at 330 to 340 ° C for 30 minutes and compression molded to produce a film with a thickness of 0.20 to 0.25 mm. This film is analyzed by Fourier transform infrared spectroscopy to obtain the infrared absorption spectrum of the copolymer, and a difference spectrum from a base spectrum that is completely fluorinated and has no functional groups is obtained. From the absorption peak of a specific functional group appearing in this difference spectrum, according to the following formula (A), 1 × 10 carbon atoms in the copolymer ６Calculate the number of functional groups N per individual. N = I × K / t (A) I: absorbance K: correction factor t: film thickness (mm)

[0095] For reference, Table 1 shows the absorption frequency, molar extinction coefficient, and correction factor for the functional groups in this disclosure. The molar extinction coefficient was determined from FT-IR measurement data of a small molecule model compound.

[0096]

[0097] Note that -CH ２ CF ２ H, -CH ２ COF, -CH ２ COOH, -CH ２ COOCH ３ ien-CH ２ CONH ２ The absorption frequencies are shown in the table below, -CF ２ H, -COF, -COOH free and -COOH bonded, -COOCH ３ , -CONH ２ From the absorption frequency to several tens of kaiser (cm) －１ ) becomes lower. Therefore, for example, the number of functional groups in -COF is -CF ２ The absorption frequency due to COF is 1883 cm⁻¹. －１ The number of functional groups determined from the absorption peak, and -CH ２ The absorption frequency due to COF is 1840 cm⁻¹. －１ This is the sum of the number of functional groups determined from the absorption peaks.

[0098] The number of functional groups is -CF = CF ２ , -CF ２ H, -COF, -COOH, -COOCH ３ , -CONH ２ and -CH ２ The total number of OH groups may be -CF ２ H, -COF, -COOH, -COOCH ３ and -CH ２ The total number of OH groups is acceptable.

[0099] The above functional groups are introduced into the fluororesin (polymer) by, for example, chain transfer agents or polymerization initiators used in the production of fluororesins. For example, alcohol may be used as a chain transfer agent, or -CH may be used as a polymerization initiator. ２ When using peroxides with an OH structure, -CH can form at the end of the main chain of the fluororesin. ２ An OH group is introduced. Furthermore, by polymerizing a monomer having a functional group, the functional group is introduced to the side chain ends of the fluororesin. The fluororesin may also contain units derived from the monomer having a functional group.

[0100] Examples of monomers having functional groups include cyclic hydrocarbon monomers having a dicarboxylic acid anhydride group ((-CO-O-CO-) and a polymerizable unsaturated group in the ring, as described in Japanese Patent Publication No. 2006-152234, and monomers having a functional group (f), as described in International Publication No. 2017 / 122743. Among these, examples of monomers having functional groups include monomers having a carboxyl group (maleic acid, itaconic acid, citraconic acid, undecylenic acid, etc.); monomers having an acid anhydride group (itaconic anhydride, citraconic anhydride, 5-norbornene-2,3-dicarboxylic acid anhydride, maleic anhydride, etc.); and monomers having a hydroxyl group or an epoxy group (hydroxybutyl vinyl ether, glycidyl vinyl ether, etc.).

[0101] Fluororesins can be manufactured by conventionally known methods, such as emulsion polymerization or suspension polymerization, by appropriately mixing monomers that form their constituent units and additives such as polymerization initiators.

[0102] The fluororesin layer may contain other components as needed. Examples of other components include additives such as crosslinking agents, antistatic agents, heat stabilizers, foaming agents, foaming nucleating agents, antioxidants, surfactants, photopolymerization initiators, anti-wear agents, surface modifiers, various organic and inorganic pigments, copper damage inhibitors, anti-bubble agents, adhesion promoters, lubricants, processing aids, colorants, phosphorus-based stabilizers, lubricants, release agents, sliding materials, UV absorbers, dyes and pigments, reinforcing materials, drip inhibitors, fillers, curing agents, UV curing agents, and flame retardants. The content of other components in the fluororesin layer is preferably less than 30% by mass, more preferably less than 10% by mass, and even more preferably 5% by mass or less, relative to the mass of fluororesin in the fluororesin layer. The lower limit is not particularly limited, but may be 0% by mass or more. In other words, the fluororesin layer does not need to contain other components.

[0103] From the viewpoint of insulating properties, the thickness of the fluororesin layer is preferably 40 to 300 μm, more preferably 50 μm or more, even more preferably 60 μm or more, even more preferably 250 μm or less, and even more preferably 200 μm or less.

[0104] The relative permittivity of the fluororesin layer is preferably 2.5 or less, more preferably 2.4 or less, even more preferably 2.3 or less, still more preferably 2.2 or less, particularly preferably 2.1 or less, and preferably 1.8 or more. The relative permittivity is a value obtained by measuring the change in resonant frequency and electric field strength at a temperature of 20 to 25°C using a network analyzer HP8510C (manufactured by Hewlett-Packard) and a cavity resonator.

[0105] From the viewpoint of insulation properties, the partial discharge initiation voltage of an electric wire measured at 25°C preferably satisfies the following relationship: Partial discharge initiation voltage (V) ≥ 5.5 × t + 600 t: Fluororesin layer thickness (μm)

[0106] The partial discharge initiation voltage of an electric wire is preferably less prone to change even after the wire has been used in a high-temperature environment. The rate of change calculated from the partial discharge initiation voltage (D) of the electric wire measured at 25°C and the partial discharge initiation voltage (E) of the electric wire measured at 25°C after heating the electric wire at 180°C for 3000 hours is preferably less than 10%, and more preferably less than 5%. Rate of change (%) = [(Partial discharge initiation voltage (D)) - (Partial discharge initiation voltage (E))] / (Partial discharge initiation voltage (D)) × 100

[0107] The electric wire used in the stator of this disclosure can be manufactured, for example, by heating and melting a fluororesin using an extruder, and then extruding the molten fluororesin onto a core wire to form a fluororesin layer.

[0108] Although embodiments have been described above, it should be understood that various modifications to the form and details are possible without departing from the spirit and scope of the claims.

[0109] <1> According to a first aspect of this disclosure, a stator is provided comprising: a stator core having a plurality of slot portions; a plurality of electric wires housed in the slot portions; and a thermosetting resin portion formed between the electric wires, wherein the electric wires comprise a core wire and a fluororesin layer containing fluororesin that forms the outermost surface of the electric wires, and the thermosetting resin portion is formed of a thermosetting resin. <2> According to a second aspect of this disclosure, a stator according to the first aspect is provided, wherein the thermosetting resin portion is formed by curing a thermosetting resin composition containing the thermosetting resin. <3> According to a third aspect of this disclosure, a stator according to the second aspect is provided, wherein the viscosity of the thermosetting resin composition at 25°C is 0.5 to 20 Pa·s. <4> According to a fourth aspect of this disclosure, a stator according to the second or third aspect is provided, wherein the curing shrinkage rate of the thermosetting resin composition is 15% or less. <5> According to the fifth aspect of this disclosure, a stator according to any of the first to fourth aspects is provided, wherein the heat resistance temperature of the thermosetting resin is 155°C or higher. <6> According to the sixth aspect of this disclosure, the volume resistivity of the thermosetting resin is 1.0 × 10 １５A stator according to any of the first to fifth aspects is provided, wherein the dielectric breakdown strength of the thermosetting resin is Ω·cm or more. <7> According to the seventh aspect of this disclosure, a stator according to any of the first to sixth aspects is provided, wherein the dielectric breakdown strength of the thermosetting resin is 15 kV / mm or more. <8> According to the eighth aspect of this disclosure, a stator according to any of the first to seventh aspects is provided, wherein the 1 mass% decomposition temperature of the thermosetting resin is 200°C or more. <9> According to the ninth aspect of this disclosure, a stator according to any of the first to eighth aspects is provided, wherein the thermosetting resin is at least one selected from the group consisting of epoxy resins, polyimide resins, polyurethanes and silicones. <10> According to the tenth aspect of this disclosure, a stator according to any of the first to ninth aspects is provided, wherein the thermosetting resin is an epoxy resin, and the epoxy resin is at least one selected from the group consisting of modified epoxy resins, epoxy resins, epoxy acrylate resins and epoxy ester resins. <11> According to the eleventh aspect of this disclosure, a stator according to any of the first to tenth aspects is provided, wherein the thermosetting resin is a polyimide resin, and the polyimide resin is at least one selected from the group consisting of polyimide and polyamideimide. <12> According to the twelfth aspect of this disclosure, a stator according to any of the first to eleventh aspects is provided, wherein the thermosetting resin portion contains an inorganic filler. <13> According to the thirteenth aspect of this disclosure, a stator according to the twelfth aspect is provided, wherein the content of the inorganic filler is 0.01 to 80% by mass with respect to the mass of the thermosetting resin portion. <14> According to the fourteenth aspect of this disclosure, a stator according to any of the first to thirteenth aspects is provided, wherein the melt flow rate of the fluororesin is 0.1 to 120 g / 10 min. <15> According to the fifteenth aspect of the present disclosure, a stator according to any of the first to fourteenth aspects is provided, wherein the melting point of the fluororesin is 200 to 322°C. <16> According to the sixteenth aspect of the present disclosure, a stator according to any of the first to fifteenth aspects is provided, wherein the fluororesin is a copolymer containing tetrafluoroethylene units and fluoroalkyl vinyl ether units.<17> According to the seventeenth aspect of this disclosure, an inverter motor is provided which has a stator according to any of the first to sixteenth aspects.

[0110] Next, we will describe embodiments of the present disclosure with reference to experimental examples, but the present disclosure is not limited to such experimental examples.

[0111] Each value in the experimental example was measured using the following method.

[0112] (Melt Flow Rate (MFR) of Fluoropolymer) In accordance with ASTM D1238, the mass (g / 10 min) of copolymer flowing out of a nozzle with an inner diameter of 2.1 mm and a length of 8 mm per 10 minutes was determined using a melt indexer (manufactured by Yasuda Seiki Seisakusho Co., Ltd.) at 372°C and under a 5 kg load.

[0113] (Melting point of fluororesin) The melting point was determined as the temperature corresponding to the maximum value of the heat of fusion in the heat of fusion curve when the temperature was increased at a rate of 10°C / min using a differential scanning calorimeter (DSC).

[0114] (Composition of fluororesin) １９ The measurement was performed using the F-NMR method.

[0115] (Viscosity of thermosetting resin composition) The viscosity was measured in accordance with JIS C2105.

[0116] (Heat resistance temperature of cured thermosetting resin) The heat resistance temperature was measured in accordance with UL1446.

[0117] (Volume resistivity of cured thermosetting resin) The volume resistivity was measured in accordance with JIS C2139 3-1.

[0118] (1 mass% decomposition temperature of cured thermosetting resin) Using a thermogravimetric differential thermal analyzer (TG-DTA) (STA7200, Hitachi High-Tech Science), cured thermosetting resin was heated in air from 25°C to 600°C at a heating rate of 10°C / min, and the temperature at which it decreased by 1 mass% (1 mass% decomposition temperature) was measured.

[0119] (Curing shrinkage rate of thermosetting resin cured products) The specific gravity of the thermosetting resin before curing was measured at 25 degrees Celsius in accordance with the JIS C2103 5.2.1 pycnometer method. Specifically, a metal pycnometer measuring 100 cm³ was used. ３ Using a pycnometer, the varnish was filled, and the specific gravity (B) was determined from the mass and volume of the varnish. The specific gravity of the thermosetting resin after curing was measured using an electronic balance hydrometer (METTLER TOLEDO). Specifically, the specific gravity (C) was determined from the weight in air and water of a cured varnish sample approximately 10 mm x 10 mm in size and approximately 1 mm thick. The curing shrinkage rate was calculated according to the following formula: Curing shrinkage rate (%) = (Specific gravity (C) - Specific gravity (B)) / Specific gravity (C) × 100

[0120] (Dielectric breakdown strength of cured thermosetting resin) The dielectric breakdown strength was measured in accordance with JIS C2103.

[0121] Experimental Example 1: A copper flat wire with a roughly rectangular cross-section (width (long side) 3.4 mm, thickness (short side) 2.0 mm) was used as the conductor. A copolymer of tetrafluoroethylene and perfluoro(propyl vinyl ether) (PFA) (MFR 27 g / 10 min, melting point 302°C) was used as the coating material. The wire was extruded at a resin temperature of 370°C at the die exit to obtain a flat wire coated with fluororesin, resulting in a coating layer thickness of 150 μm.

[0122] (Adhesion strength between fluororesin layer and cured thermosetting resin) The adhesion strength was measured using a prepared rectangular wire and an AGS-X Autograph (5kN) (manufactured by Shimadzu Corporation). The rectangular wire was cut to a length of approximately 10 cm. A portion of the rectangular wire was impregnated with varnish (epoxy resin (Somar E-530)), and heated in an electric furnace at 150°C for 1 hour to cure the resin, thereby creating a test piece 41 comprising a wire 42 with 5.0 cm of the end exposed and a thermosetting resin portion 43 covering 5.0 cm of the other end of the wire 42. For measurement, a jig 31 was used, which had a through hole smaller than the diameter of the portion covered by the thermosetting resin portion 43 of the test piece 41 and larger than the width (long side) of the wire 42. The jig 31 was attached to the upper chuck of the Autograph. As shown in Figure 2, the wire 42 of the test piece 41 was inserted into a through hole (not shown) provided in the jig 31, and the wire 42 was attached to the lower chuck of the autograph. The tensile stress was measured when the wire was pulled vertically over a distance of 30 mm at a speed of 50 mm / min, and the stress at the maximum point was defined as the fixing force. The results are shown in Table 2.

[0123] Experimental Example 2: A test specimen 41 was prepared in the same manner as in Experimental Example 1, except that a portion of the electric wire was impregnated with varnish (epoxy resin (Somar E-9566-1)) and heated in an electric furnace at 150°C for 2 hours. The results are shown in Table 2.

[0124] Experimental Example 3 A test specimen 41 was prepared in the same manner as in Experimental Example 1, except that a portion of the electric wire was impregnated with varnish (epoxy resin (KE-573D manufactured by Resonaq Corporation (a mixture of KE-573DA and KE-573DB in a mass ratio of 100:90))) and heated in an electric furnace at 150°C for 1.5 hours). The results are shown in Table 2.

[0125] Experimental Example 4 A test specimen 41 was prepared in the same manner as in Experimental Example 1, except that a portion of the electric wire was impregnated with varnish (modified epoxy resin (V066-00 mixed with V565-30 manufactured by Ryoden Chemical Co., Ltd. in a mass ratio of 100:1)) and heated in an electric furnace at 160°C for 2 hours. The results are shown in Table 2.

[0126]

Claims

1. A stator comprising: a stator core having a plurality of slots; a plurality of electric wires housed in the slots; and a thermosetting resin portion formed between the electric wires, wherein the electric wires comprise a core wire and a fluororesin layer containing fluororesin that forms the outermost surface of the electric wires, and the thermosetting resin portion is formed of a thermosetting resin.

2. The stator according to claim 1, wherein the thermosetting resin portion is formed by curing a thermosetting resin composition containing the thermosetting resin.

3. The stator according to claim 2, wherein the viscosity of the thermosetting resin composition at 25°C is 0.5 to 20 Pa·s.

4. The stator according to claim 2 or 3, wherein the curing shrinkage rate of the thermosetting resin composition is 15% or less.

5. The stator according to any one of claims 1 to 4, wherein the heat resistance temperature of the thermosetting resin is 155°C or higher.

6. The volume resistivity of the thermosetting resin is 1.0 × 10 １５ A stator according to any one of claims 1 to 5, wherein the stator is Ω·cm or larger.

7. The stator according to any one of claims 1 to 6, wherein the dielectric breakdown strength of the thermosetting resin is 15 kV / mm or more.

8. The stator according to any one of claims 1 to 7, wherein the decomposition temperature of 1% by mass of the thermosetting resin is 200°C or higher.

9. The stator according to any one of claims 1 to 8, wherein the thermosetting resin is at least one selected from the group consisting of epoxy resins, polyimide resins, polyurethanes, and silicones.

10. The stator according to any one of claims 1 to 9, wherein the thermosetting resin is an epoxy resin, and the epoxy resin is at least one selected from the group consisting of modified epoxy resin, epoxy resin, epoxy acrylate resin, and epoxy ester resin.

11. The stator according to any one of claims 1 to 10, wherein the thermosetting resin is a polyimide resin, and the polyimide resin is at least one selected from the group consisting of polyimide and polyamideimide.

12. The stator according to any one of claims 1 to 11, wherein the thermosetting resin portion contains an inorganic filler.

13. The stator according to claim 12, wherein the content of the inorganic filler is 0.01 to 80% by mass with respect to the mass of the thermosetting resin portion.

14. The stator according to any one of claims 1 to 13, wherein the melt flow rate of the fluororesin is 0.1 to 120 g / 10 min.

15. The stator according to any one of claims 1 to 14, wherein the melting point of the fluororesin is 200 to 322°C.

16. The stator according to any one of claims 1 to 15, wherein the fluororesin is a copolymer containing tetrafluoroethylene units and fluoroalkyl vinyl ether units.

17. An inverter motor comprising a stator according to any one of claims 1 to 16.

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