Thermosetting resin composition and method for manufacturing stator

Abstract

Provided is a thermosetting resin composition which is used for the purpose of forming an insulating layer by filling a space (88) that is formed between a mold core (80) (blade), which is inserted into a slot (8) of a stator (4), and a wall surface (an inner wall surface (72) of a tooth part (7) and an inner wall surface (62) of a yoke part (6)) of the slot (8), the thermosetting resin composition containing an epoxy resin, a curing agent, an inorganic filler, and a wax (a mold release agent). With respect to the thermosetting resin composition, the wax contains a higher fatty acid ester or a higher fatty acid amide, and the amount of the higher fatty acid ester or the higher fatty acid amide is 1.0 mass% or less relative to the entire thermosetting resin composition.

Description

Thermosetting resin composition and method for manufacturing a stator

[0001] The present invention relates to a thermosetting resin composition and a stator, and more particularly to a thermosetting resin composition for use as a sealing material for a stator core, and a stator including the thermosetting resin composition as a sealing material.

[0002] Patent Document 1 (JP 2003-284277 A) describes a technology for using a resin material in a stator core. The document describes a rotating electric machine having a stator in which multiple coils are wound at predetermined intervals around a stator core made of laminated electromagnetic steel sheets, a rotor rotatably held relative to the stator, and a cooling frame to which the stator is fixed, in which slots that form the winding portions of the stator are filled with a highly thermally conductive composite material made of a thermosetting resin whose resin component has an anisotropic structure. The document states that this configuration provides a rotating electric machine with good heat dissipation properties, as it easily transfers heat generated in the coils.

[0003] Japanese Patent Application Laid-Open No. 2003-284277

[0004] Coils are inserted into stator slots, and to ensure insulation between the coil and the slot, a resin layer is sometimes formed on the wall surface of the slot before the coil is inserted. The process of forming this resin layer involves placing a mold core (also called a blade) in the slot, filling the space formed by the slot wall and the mold core with a resin composition, and then removing the mold core after a certain period of time. When the mold core is removed, problems such as distortion of the resin composition around the mold core can occur, making it impossible to increase the removal speed. Therefore, a technology to address this issue has been sought from the perspective of productivity.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a technology that improves productivity when inserting a mold core into a slot and forming a resin layer on the wall surface of the slot.

[0006] The present invention provides the following technologies: <1> A thermosetting resin composition used to form an insulating layer by filling a space formed between a blade, which is a mold core inserted into a slot of a stator, and the wall surface of the slot, the thermosetting resin composition comprising: an epoxy resin; a curing agent; an inorganic filler; and a wax, the wax including a higher fatty acid ester or a higher fatty acid amide, the amount of the higher fatty acid ester or the higher fatty acid amide being 1.0 mass% or less relative to the entire thermosetting resin composition. <2> A method for manufacturing a stator using the thermosetting resin composition according to <1> to provide an insulating layer on the wall surface of a slot, the method comprising: a core placement step of inserting a blade-shaped mold core into the slot to form a filling space between the wall surface of the slot and the mold core for filling with the thermosetting resin composition; and a resin filling step of filling the filling space with the thermosetting resin composition. <3> A method for manufacturing a stator according to <2>, wherein the surface roughness Ra of the mold core is 10 μm or less. <4> The method for manufacturing a stator according to <2> or <3>, wherein the surface of the mold core has a coating layer. <5> The method for manufacturing a stator according to any one of <2> to <4>, further comprising a mold core removal step of pulling out and removing the mold core after the resin filling step. <6> The method for manufacturing a stator according to claim <5>, wherein in the mold core removal step, a pulling force F when removing the mold core is 250 kgf or less. <7> In the mold core removal step, a ratio F / S of the surface area S of the mold core to the pulling force F is 3.6 kgf / cm ２ The method for manufacturing a stator according to <6>, wherein: <8> the method for manufacturing a stator according to any one of <5> to <7>, wherein the die core removing step is performed in an as-molded state. <9> the method for manufacturing a stator according to any one of <2> to <8>, wherein a glass transition temperature Tg of a cured product of the thermosetting resin composition is 120°C or higher.

[0007] The present invention has been made in consideration of such circumstances, and can provide a technology that improves productivity when a mold core is inserted into a slot and a resin layer is formed on the wall surface of the slot.

[0008] 1 is a cross-sectional view in a direction perpendicular to the rotational axis direction of the motor; FIG. 2 is a longitudinal cross-sectional view in the rotational axis direction of the motor; FIG. 3 is an enlarged view of the periphery of a slot; FIG. 4 is a cross-sectional view showing the inside of a slot; FIG. 5 is a flowchart showing a method for manufacturing a stator; FIG. 6 is a view explaining the transition of the state within the slot in the resin layer forming process; FIG. 7 is a view explaining the transition of the state within the slot in the resin layer forming process; FIG. 8 is a view showing a slot of a stator simulation mold of an embodiment; FIG. 9 is a view showing a mold core of an embodiment.

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all drawings, similar components are denoted by similar reference numerals, and descriptions thereof will be omitted where appropriate. In this specification, the numerical range "a to b" means "a or more and b or less."

[0010] <Overview> This embodiment provides a technology for improving productivity when inserting a mold core into a stator slot and forming a resin layer on the wall surface of the slot. To achieve this, a wax (mold release agent) is contained in the thermosetting resin composition used to form the resin layer. The wax contains a higher fatty acid ester or a higher fatty acid amide, and the amount of the higher fatty acid ester or higher fatty acid amide is 1.0 mass% or less relative to the total thermosetting resin composition. Furthermore, the surface of the blade-shaped mold core used to form the resin layer is designed to facilitate easy removal from the thermosetting resin composition. Specific details are provided below. The stator of this embodiment is used in, for example, an electric motor (motor) as a rotating electrical machine (electric motor, generator, or dual-purpose electric motor / generator). The application of the motor is described below as one embodiment.

[0011] <Motor> Fig. 1 is a schematic cross-sectional view of motor 100 taken perpendicular to the rotational axis direction. Fig. 2 is a schematic cross-sectional view of motor 100 taken in the rotational axis direction. Fig. 3 is an enlarged view of the periphery of the slot (area X in Fig. 1), and is a schematic cross-sectional view of the portion where coil 9 protrudes from the end of slot 8. Fig. 4 is a cross-sectional view taken along line A-A in Fig. 3, showing the inside of slot 8.

[0012] The motor 100 includes a case 1 , and a rotor 2 , a stator 4 , and a coil 9 housed inside the case 1 .

[0013] <Case> The case 1 includes a cylindrical portion 1 a and side plate portions 1 b, 1 c that close both axial ends of the cylindrical portion 1 a. The case 1 can be made of, for example, an aluminum alloy (cast metal product), a resin material, or a combination thereof.

[0014] <Rotor> As shown in Figures 1 and 2, the rotor 2 is housed inside the case 1. As shown in Figure 2, a rotary shaft 3 is attached to the center of the rotor 2 as an output shaft. Both ends of the rotary shaft 3 are supported by the side plate portions 1b and 1c via bearings 3a. This allows the rotor 2 to rotate freely around the rotary shaft 3.

[0015] Permanent magnets 5 are installed inside the rotor 2. Specifically, as shown in Fig. 1, a plurality of (eight in this example) permanent magnets 5 are arranged at equal intervals on the same circumference, with the magnetic poles of adjacent permanent magnets 5 being set to be opposite to each other.

[0016] <Stator> The stator 4 has a stator core 41 and coils 9 sealed in slots 8. The stator core 41 is formed by stacking a plurality of electromagnetic steel plates in the axial direction and closely fixing them together. When viewed from the axial end as shown in FIG. 1 , the stator core 41 has an annular yoke portion 6 and a plurality of teeth portions 7 extending from the yoke portion 6 toward the rotor 2 (inner periphery). The plurality of teeth portions 7 are arranged at equal intervals in the circumferential direction. In this example, as shown in FIG. 1 , 24 teeth portions 7 are provided. Slots 8 are provided between each of the teeth portions 7. The teeth portions 7 are also provided with a thin resin layer 50 formed by wrapping a resin composition around them to cover them.

[0017] <Coil> As an example, the coil 9 is a U-shaped rectangular wire wound so as to straddle the tooth portion 7 and be housed in two spaced-apart slots 8. The coil 9 may be housed in a distributed winding manner in a liner member disposed in the slot 8, or may be housed without a liner member. The coil 9 has a coil body made of a good conductor such as copper and having a rectangular cross section, and a resin coating layer that coats the surface of the coil body. The resin coating layer may be made of the same material as that described below as the resin material for the resin layer 50.

[0018] <Teeth portion> The teeth portion 7 is provided to correspond to the permanent magnets 5 of the rotor 2 described above, and by sequentially exciting each coil 9, the rotor 2 rotates due to attraction and repulsion with the corresponding permanent magnets 5.

[0019] The teeth 7 are tapered, with a larger circumferential width on the outer periphery and a smaller width on the inner periphery. Teeth tips 71 are formed at the inner periphery end of the teeth 7, facing each other along the circumferential direction so as to reduce the width of the slots 8.

[0020] <Slots> Slots 8 are spaces between adjacent teeth 7, and as shown in Figures 3 and 4, are provided so that the inner wall surfaces 72 of teeth 7 that face each other in the radial direction are parallel to each other. The space between the tooth tips 71 forms the inner peripheral opening of the slot 8. The slot 8 has multiple coils 9 arranged on the outer peripheral side (the yoke portion 6 side), a resin layer 50, and a resin sealing portion 65 that fills the space in the slot 8 excluding the coils 9 and resin layer 50.

[0021] <Resin Layer> As shown in Figures 3 and 4, resin layer 50 is formed by integrally wrapping a resin composition around the periphery of tooth portion 7 to cover it, and includes tooth inner surface resin layer 51 that covers inner wall surface 72 of tooth portion 7, tooth outer surface resin layer 52 that covers upper surface 75a and lower surface 75b of tooth portion 7, and yoke inner surface resin layer 53 that covers inner wall surface 62 of yoke portion 6.

[0022] Resin layer 50 is inserted into the stator 4, and is inserted into the teeth 7 to form a thin film that covers the teeth 7. Resin layer 50 does not necessarily have to be inserted into the teeth 7 to form a thin film, and tooth outer surface resin layer 52 may be omitted. By providing tooth inner surface resin layer 51 and yoke inner surface resin layer 53, insulation between coil 9 and the inner wall surface of slot 8 (inner wall surface 72 of tooth 7 and inner wall surface 62 of yoke 6) is ensured.

[0023] The thickness of the resin layer 50 is, for example, 50 μm or more and 500 μm or less. The lower limit of the thickness is preferably 100 μm or more, more preferably 150 μm or more. The upper limit of the thickness is preferably 400 μm or less, more preferably 300 μm or less. The tooth inner surface resin layer 51, the tooth outer surface resin layer 52, and the yoke inner surface resin layer 53 may have the same or different thicknesses. The lower limit of the thickness is preferably within the above range from the viewpoint of ensuring the fluidity of the resin composition in the extremely narrow portion between the mold (mold core 80) and the wall surface of the slot 8 relative to the axial length of the stator (i.e., the thickness of the stator 4) during insert molding. The upper limit of the thickness is preferably within the above range from the viewpoint of improving the space utilization efficiency within the slot 8 and ensuring the flexibility of the size of the usable coil 9 and performance such as magnetic flux density in a structure in which the coil 9 is wound around the tooth portion 7 and placed in the slot 8.

[0024] <Physical Properties of Resin Layer> The physical properties of the cured resin material constituting the resin layer 50 are, for example, as follows: The thermal conductivity of the cured resin material is 0.5 W / (m·K) or more. The lower limit of the thermal conductivity is preferably 1.0 W / (m·K) or more, and more preferably 2 W / (m·K) or more. The upper limit of the thermal conductivity is not particularly limited, but a realistic value is 10 W / (m·K).

[0025] The glass transition temperature Tg of the resin composition of the resin layer 50 is 120° C. or higher, preferably 140° C. or higher, and more preferably 160° C. or higher. By setting the glass transition temperature Tg within the above range, the motor 100 can be used at high temperatures and can be resistant to heat generation in the coil 9, allowing it to be used at high output. The resin composition of the resin layer 50 will be described in detail below.

[0026] <Materials for Resin Layer> The resin composition of the resin layer 50 preferably contains a thermosetting resin (A), a filler (B), a curing agent (C), and the like.

[0027] [Thermosetting resin (A)] Examples of the thermosetting resin (A) include epoxy resins, cyanate resins, polyimide resins, benzoxazine resins, unsaturated polyester resins, phenolic resins, melamine resins, silicone resins, bismaleimide resins, phenoxy resins, and acrylic resins. As the thermosetting resin (A), one of these may be used alone, or two or more may be used in combination. Among these, from the viewpoint of having high insulating properties, epoxy resins, phenolic resins, and phenoxy resins are preferred as the thermosetting resin (A). From the viewpoint of ensuring flow in extremely narrow parts during molding, epoxy resins are particularly preferred.

[0028] Examples of epoxy resins include bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, bisphenol S type epoxy resin, bisphenol M type epoxy resin (4,4'-(1,3-phenylenediisopridiene)bisphenol type epoxy resin), bisphenol P type epoxy resin (4,4'-(1,4-phenylenediisopridiene)bisphenol type epoxy resin), and bisphenol Z type epoxy resin (4,4'-cyclohexidienebisphenol type epoxy resin); phenol novolac type epoxy resin, cresol novolac type epoxy resin, trisphenol group methane type novolac type epoxy resin, tetraphenol group ethoxylated epoxy resin, and the like. Examples of the epoxy resin include novolac-type epoxy resins such as benzophenone-type novolac-type epoxy resins and novolac-type epoxy resins having a condensed ring aromatic hydrocarbon structure; biphenyl-type epoxy resins; aryl alkylene-type epoxy resins such as xylylene-type epoxy resins and biphenyl aralkyl-type epoxy resins; naphthalene-type epoxy resins such as naphthylene ether-type epoxy resins, naphthol-type epoxy resins, naphthalene diol-type epoxy resins, bifunctional to tetrafunctional epoxy naphthalene resins, binaphthyl-type epoxy resins, and naphthalene aralkyl-type epoxy resins; anthracene-type epoxy resins; phenoxy-type epoxy resins; dicyclopentadiene-type epoxy resins; norbornene-type epoxy resins; adamantane-type epoxy resins; and fluorene-type epoxy resins. These may be used singly or in combination of two or more.

[0029] Among the epoxy resins, from the viewpoint of further improving heat resistance and insulation reliability, it is preferable to use one or more types selected from the group consisting of bisphenol-type epoxy resins, novolac-type epoxy resins, biphenyl-type epoxy resins, aryl alkylene-type epoxy resins, naphthalene-type epoxy resins, anthracene-type epoxy resins, and dicyclopentadiene-type epoxy resins.

[0030] Examples of phenolic resins include novolac-type phenolic resins such as phenol novolac resin, cresol novolac resin, and bisphenol A novolac resin, and resol-type phenolic resins. One of these may be used alone, or two or more may be used in combination. Among phenolic resins, phenol novolac resins are preferred.

[0031] The content of the thermosetting resin (A) is preferably 1% by mass or more, and more preferably 5% by mass or more, relative to the total amount of the resin composition of the resin layer 50. On the other hand, the content is preferably 30% by mass or less, and more preferably 20% by mass or less, relative to the total amount of the resin composition of the resin layer 50.

[0032] When the content of thermosetting resin (A) is equal to or greater than the above lower limit, the handleability of the entire resin composition of resin layer 50 is improved, making it easier to form the inner surface resin layer (tooth inner surface resin layer 51, yoke inner surface resin layer 53) and improving the strength of the inner surface resin layer (tooth inner surface resin layer 51, yoke inner surface resin layer 53).

[0033] When the content of the thermosetting resin (A) is equal to or less than the upper limit, the linear expansion coefficient and elastic modulus of the inner surface resin layer (tooth inner surface resin layer 51, yoke inner surface resin layer 53) are further improved, and the thermal conductivity is further improved.

[0034] [Filler (B)] In this embodiment, filler (B) is used to improve the thermal conductivity of the resin layer 50 (more specifically, the inner surface resin layer (tooth inner surface resin layer 51, yoke inner surface resin layer 53)) and to obtain strength.

[0035] As the filler (B), an inorganic filler is preferred, and a thermally conductive filler is particularly preferred. More specifically, as the filler (B), from the viewpoint of achieving a balance between thermal conductivity and electrical insulation, for example, silica, alumina, boron nitride, aluminum nitride, silicon carbide, etc. may be mentioned. These may be used alone or in combination of two or more. Among them, the filler (B) is preferably alumina or boron nitride.

[0036] The content of the filler (B), that is, the content of the above filler, is preferably 60% by mass or more based on the total amount of the resin composition.

[0037] [Curing Agent (C)] When an epoxy resin or a phenolic resin is used as the thermosetting resin (A), the resin composition preferably further contains a curing agent (C). As the curing agent (C), one or more selected from a curing catalyst (C-1) and a phenolic curing agent (C-2) can be used.

[0038] Examples of the curing catalyst (C-1) include organic metal salts such as zinc naphthenate, cobalt naphthenate, tin octoate, cobalt octoate, bisacetylacetonate cobalt(II), and trisacetylacetonate cobalt(III); tertiary amines such as triethylamine, tributylamine, and 1,4-diazabicyclo[2.2.2]octane; 2-phenyl-4-methylimidazole, 2-ethyl-4-methylimidazole, 2,4-diethylimidazole, and 2-phenyl-4-methyl-5-hydroxyimidazole; imidazoles such as 2-phenyl-4,5-dihydroxymethylimidazole; organic phosphorus compounds such as triphenylphosphine, tri-p-tolylphosphine, tetraphenylphosphonium tetraphenylborate, triphenylphosphine triphenylborane, 1,2-bis-(diphenylphosphino)ethane; phenolic compounds such as phenol, bisphenol A, nonylphenol; organic acids such as acetic acid, benzoic acid, salicylic acid, p-toluenesulfonic acid; etc., or mixtures thereof. As the curing catalyst (C-1), one of these, including derivatives thereof, can be used alone, or two or more of these, including derivatives thereof, can be used in combination.

[0039] The content of the curing catalyst (C-1) is not particularly limited, but is preferably 0.001% by mass or more and 1% by mass or less based on the total amount of the resin composition.

[0040] Examples of the phenolic curing agent (C-2) include novolac-type phenolic resins such as phenol novolac resin, cresol novolac resin, trisphenolmethane-type novolac resin, naphthol novolac resin, and aminotriazine novolac resin; modified phenolic resins such as terpene-modified phenolic resin and dicyclopentadiene-modified phenolic resin; aralkyl-type resins such as phenol aralkyl resins having a phenylene skeleton and / or biphenylene skeleton and naphthol aralkyl resins having a phenylene skeleton and / or biphenylene skeleton; bisphenol compounds such as bisphenol A and bisphenol F; and resol-type phenolic resins, and these may be used alone or in combination of two or more.

[0041] Among these, from the viewpoint of improving the glass transition temperature and reducing the linear expansion coefficient, the phenolic curing agent (C-2) is preferably a novolac phenolic resin or a resol phenolic resin. The content of the phenolic curing agent (C-2) is not particularly limited, but is preferably 1% by mass or more, and more preferably 5% by mass or more, relative to the total amount of the resin composition. On the other hand, the content is preferably 30% by mass or less, and more preferably 15% by mass or less, relative to the total amount of the resin composition.

[0042] [Coupling Agent (D)] The resin composition may contain a coupling agent (D). The coupling agent (D) can improve the wettability at the interface between the thermosetting resin (A) and the filler (B).

[0043] The coupling agent (D) is not particularly limited, but it is preferable to use, for example, one or more coupling agents selected from epoxy silane coupling agents, cationic silane coupling agents, amino silane coupling agents, titanate-based coupling agents, and silicone oil-type coupling agents.

[0044] The content of the coupling agent (D) is not particularly limited, but is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, relative to 100% by mass of the filler (B), while the content is preferably 3% by mass or less, more preferably 2% by mass or less, relative to 100% by mass of the filler (B).

[0045] [Phenoxy Resin (E)] The resin composition may further contain a phenoxy resin (E). By containing the phenoxy resin (E), the bending resistance of the resin layer 50 can be improved, and the elastic modulus can be reduced, thereby improving the stress relaxation force of the resin layer 50.

[0046] Furthermore, when the resin layer 50 contains the phenoxy resin (E), the viscosity increases, reducing the flowability and preventing the formation of voids, etc. Furthermore, when the resin layer 50 is used in close contact with a metal member (i.e., the teeth 7 or the yoke 6), the adhesion between the metal and the cured resin composition can be improved.

[0047] Examples of the phenoxy resin (E) include phenoxy resins having a bisphenol skeleton, phenoxy resins having a naphthalene skeleton, phenoxy resins having an anthracene skeleton, and phenoxy resins having a biphenyl skeleton. Phenoxy resins having a structure containing multiple types of these skeletons can also be used. The content of the phenoxy resin (E) is preferably, for example, 3% by mass or more and 10% by mass or less relative to the total amount of the resin composition.

[0048] [Wax (mold release agent)] The resin composition contains a wax. This can improve the releasability from the mold core 80 after molding. Examples of waxes include natural waxes such as carnauba wax, synthetic waxes such as Montan acid ester wax and oxidized polyethylene wax, higher fatty acids such as zinc stearate and their metal salts, paraffin, and higher fatty acid amides. These may be used alone or in combination of two or more. It is preferable to contain a higher fatty acid ester or a higher fatty acid amide, and it is particularly preferable to contain Montan acid ester wax.

[0049] Examples of hydrocarbon waxes include paraffin waxes having 24 or more carbon atoms, olefin waxes having 26 or more carbon atoms, alkylbenzene waxes having 28 or more carbon atoms, and microcrystalline waxes.

[0050] Examples of higher fatty acids include higher saturated fatty acids having 12 or more carbon atoms, such as lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, cerotic acid, and montanic acid, and unsaturated fatty acids having 18 or more carbon atoms, such as oleic acid, linoleic acid, linolenic acid, elaidic acid, octadecenoic acid, arachidonic acid, cadreic acid, erucic acid, and parinaric acid.

[0051] Examples of waxes obtained by deriving higher fatty acids include higher fatty acid esters, higher fatty acid amides, and higher fatty acid salts (metal soaps).

[0052] The higher fatty acid esters are esters of the above higher fatty acids with monohydric or polyhydric alcohols, such as caprylic alcohol, lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, and behenyl alcohol, and such polyhydric alcohols as ethylene glycol, propylene glycol, butanediol, glycerin, pentaerythritol, and sorbitol.

[0053] Examples of higher fatty acid esters include stearyl stearate, pentaerythritol tetrastearate, stearic acid monoglyceride, behenic acid monoglyceride, and montanic acid wax.

[0054] Examples of higher fatty acid amides include saturated higher fatty acid amides such as lauric acid amide, palmitic acid amide, stearic acid amide, and behenic acid amide; unsaturated higher fatty acid amides such as erucic acid amide, oleic acid amide, brassidic acid amide, and elaidic acid amide; and higher fatty acid bisamides such as methylene bisstearic acid amide, ethylene bisstearic acid amide, and ethylene bisoleic acid amide (including saturated or unsaturated higher fatty acid alkylamides such as higher fatty acid methylamides and higher fatty acid ethylamides).

[0055] When wax (mold release agent) is used, its content in the entire resin molding material is preferably 0.01 to 3 mass %, more preferably 0.05 to 2 mass %. This ensures improved mold releasability. As a result, the molding precision of the inner surface resin layer of resin layer 50 (more specifically, tooth inner surface resin layer 51 and yoke inner surface resin layer 53) can be improved.

[0056] When a higher fatty acid ester or a higher fatty acid amide is included as the wax (mold release agent), the blending amount of the higher fatty acid ester or the higher fatty acid amide is 1.0 mass% or less relative to the entire thermosetting resin composition. By blending the higher fatty acid ester or the higher fatty acid amide as the wax (mold release agent) in an amount of 1.0 mass% or less relative to the entire thermosetting resin composition, it is possible to achieve both the pullability of the mold core 80 (blade) and its adhesion to the stator core 41. The upper limit of the blending amount of the higher fatty acid ester or the higher fatty acid amide is preferably 0.8 mass% or less, more preferably 0.6 mass% or less. The lower limit is, for example, 0.1 mass% or more, preferably 0.2 mass% or more, and more preferably 0.3 mass% or more.

[0057] [Other Components] The resin composition may also contain other components such as an antioxidant and a leveling agent, provided that the effects of the present invention are not impaired.

[0058] <Resin Sealing Portion> The resin sealing portion 65 is provided inside the slot 8 (more specifically, between the resin layer 50 and the coil 9) to seal the coil 9. The resin sealing portion 65 may be provided by insert molding or may be provided as a separate component. The resin material used for the resin sealing portion 65 may be the same as the resin material described for the resin layer 50.

[0059] <Method of Manufacturing Stator> A method of manufacturing the stator 4 of this embodiment will be described. Fig. 5 is a flowchart showing a method of manufacturing the stator 4. First, a stator 4 is prepared by stacking a plurality of electromagnetic steel plates in the axial direction and closely fixing them together (stator preparation step S10).

[0060] Next, a mold core 80 is placed in the slot 8, and the periphery (inner wall surface 72, upper surface 75a, and lower surface 75b) of the tooth portion 7 and the inner wall surface 62 of the yoke portion 6 are integrally covered with an insulating resin composition by insert molding to form a resin layer 50 (resin layer forming step S20). The resin layer forming step S20 will be described in detail later.

[0061] Next, the coils 9 are placed in the slots 8 provided with the resin layer 50 (coil placement step S30). After all the coils 9 are accommodated, the inner peripheral region of the slots 8 is filled with a resin material to obtain a resin-sealed portion 65 (coil sealing step S40).

[0062] Next, the resin layer forming step S20 will be described in more detail with reference to the above flowchart and Figures 6 and 7. Figures 6 and 7 show the transition of the state inside the slot during the resin layer forming step S20, with Figure 6 being a cross-sectional view cut along a plane perpendicular to the axis, and Figure 7 being a cross-sectional view of a portion corresponding to the A-A cross section in Figure 3.

[0063] The resin layer forming step S20 includes a core placing step S21, a resin filling step S22, and a mold core removing step S23.

[0064] 6( a) and 7(a), the core placement step S21 is a step of inserting a blade-shaped mold core 80 into the slot 8. In this embodiment, the mold core 80 is inserted into the slot 8 from the upper side as shown in the figure. At this time, the upper and lower ends of the mold core 80 protrude from the upper and lower ends of the slot 8.

[0065] The core placement process S21 forms a space 88 between the wall surfaces of the slot 8 (the inner wall surfaces 72 of the tooth portion 7 and the inner wall surfaces 62 of the yoke portion 6) and the mold core 80 for filling with a thermosetting resin composition.

[0066] Next, as shown in FIG. 6(b) and FIG. 7(b), the resin filling step S22 is a step of filling the space 88 formed in the core placement step S21 with the above-mentioned thermosetting resin composition.

[0067] 6(c) and 7(c), the mold core removal step S23 is a step following the resin filling step S22 in which the mold core 80 is pulled out and removed. This step is performed in the as-molded state, which has not yet undergone after-cure. For example, as shown in FIG. 9 for the mold core 80 used in the example described below, an access opening 87 is provided near the upper end 80a of the mold core 80. A predetermined jig is attached to this opening 87, and the mold core 80 is pulled out in the upward direction as shown in the figure.

[0068] When the mold core removal process S23 is completed, a resin layer 50 is formed on the wall surfaces of the slot 8 (the inner wall surfaces 72 of the tooth portion 7 and the inner wall surfaces 62 of the yoke portion 6), as shown in Figures 6(d) and 7(d).

[0069] <Mold Core> The mold core 80 used in the resin layer forming step S20 will be described. The mold core 80 is formed in an appropriate shape depending on the shape of the slot 8 and the resin layer 50 to be formed, but generally has a long, thin blade shape. A general mold steel material, such as SKD-11 (JIS standard), can be used for the mold core 80. The surface of the mold core 80 (the surface that comes into contact with the resin layer 50) is smoothed. This makes it possible to avoid any effects, such as distortion, on the resin layer 50 when the mold core 80 is pulled out.

[0070] Furthermore, the water contact angle on the surface of the mold core 80 is 90° or more, preferably 95° or more, and more preferably 100° or more. A practical upper limit for the water contact angle is 170° or less, preferably 160° or less, and more preferably 150° or less. The water contact angle is measured in accordance with JIS R3257, for example, using a contact angle meter. Known methods such as the width-height method (θ / 2 method), the Young-Laplace method, and the ellipse method can be used as the measurement method.

[0071] By blending a higher fatty acid ester or a higher fatty acid amide as the wax (mold release agent) contained in the material (thermosetting resin composition) of the resin layer 50 so that the amount is 1.0 mass % or less, and by setting the water contact angle on the surface of the mold core 80 within the above range, it is possible to improve the pull-out properties of the mold core 80 while ensuring adhesion of the resin layer 50 to the stator core 41.

[0072] Furthermore, the surface roughness Ra of the mold core 80 is 10 μm or less, preferably 5 μm or less, and more preferably 1 μm or less. There is no particular lower limit for the surface roughness Ra, but a practical range is 0.01 μm or more, preferably 0.05 μm or more, and more preferably 0.1 μm or more. The surface roughness Ra is measured in accordance with JIS B 0601-2001. By smoothing the surface of the mold core 80 so that the surface roughness Ra of the mold core 80 falls within the above range, the pullability of the mold core 80 can be improved while ensuring the adhesion of the resin layer 50 to the stator core 41. It is sufficient that at least one of the water contact angle and surface roughness Ra of the mold core 80 falls within the above range. However, satisfying both conditions can achieve both the pullability of the mold core 80 and the adhesion of the resin layer 50 to the stator core 41.

[0073] The surface of the mold core 80 may have a coating layer. Examples of the coating layer that can be used include a chrome plating layer, a fluorine coating layer, a PVD (Physical Vapor Deposition) coating layer, and a ceramic coating layer. By providing such a coating layer on the surface of the mold core 80, it becomes easier to adjust the water contact angle and surface roughness Ra of the surface of the mold core 80 to fall within the above ranges. Note that the type and thickness of the coating layer are not limited to the above examples, and various coating layers that can set the water contact angle and surface roughness within appropriate ranges can be used.

[0074] In the mold core removal step S23, the pulling force F when removing the mold core 80 is 250 kgf or less, preferably 200 kgf or less, and more preferably 150 kgf or less. The lower limit is, for example, 25 kgf or more, preferably 50 kgf or more, and more preferably 75 kgf or more. In addition, in the mold core removal step S23, the ratio F / S1 of the surface area S1 of the mold core 80 to the pulling force F is 3.6 kgf / cm. ２ Preferably, it is 2.9 kgf / cm or less. ２ More preferably, it is 2.2 kgf / cm or less. ２ The lower limit is, for example, 0.4 kgf / cm ２ The force is equal to or greater than 0.8 kgf, and more preferably equal to or greater than 1.2 kgf. By setting the pull-out force F of the mold core 80 and the ratio F / S1 of the surface area S1 to the pull-out force F within the above ranges, the force acting on the resin layer 50 during pull-out can be reduced, preventing defects such as distortion in the resin layer 50. This can be achieved by setting the material of the resin layer 50 (particularly the selection and amount of wax) and the surface condition of the mold core 80 (water contact angle and surface roughness Ra) as described above.

[0075] Summary of the embodiment The features of the present embodiment can be summarized as follows: <1> A thermosetting resin composition used to form an insulating layer by filling a space 88 formed between a mold core 80 (blade) inserted into a slot 8 of a stator 4 and a wall surface of the slot 8 (inner wall surface 72 of a tooth portion 7, inner wall surface 62 of a yoke portion 6), the thermosetting resin composition comprising: an epoxy resin; a curing agent; an inorganic filler; and a wax (mold release agent), the wax containing a higher fatty acid ester or a higher fatty acid amide, and the amount of the higher fatty acid ester or the higher fatty acid amide blended is 1.0 mass % or less with respect to the entire thermosetting resin composition. <2> A method for manufacturing a stator 4 using the thermosetting resin composition according to <1> to provide an insulating layer (resin layer 50) on wall surfaces of slots 8 (inner wall surfaces 72 of teeth portions 7, inner wall surfaces 62 of yoke portions 6), the method comprising: a core placement step S21 of inserting a blade-shaped mold core 80 into the slots 8 to form a filling space (space 88) between the wall surfaces of the slots 8 and the mold core 80 for filling the thermosetting resin composition; and a resin filling step S22 of filling the filling space (space 88) with the thermosetting resin composition. <3> A method for manufacturing a stator 4 according to <2>, in which the mold core 80 has a surface roughness Ra of 10 μm or less. <4> A method for manufacturing a stator according to <2> or <3>, in which the surface of the mold core 80 has a coating layer. <5> The method for manufacturing a stator 4 according to any one of <2> to <4>, further comprising a mold core removal step S23 of pulling out and removing the mold core 80 after the resin filling step S22. <6> The method for manufacturing a stator 4 according to <5>, wherein in the mold core removal step S23, a pulling force F when removing the mold core 80 is 250 kgf or less. <7> In the mold core removal step S23, a ratio F / S1 of a surface area S1 of the mold core 80 to the pulling force F is 3.6 kgf / cm ２<8> The method for manufacturing a stator 4 according to any one of <5> to <7>, wherein the mold core removing step S23 is performed in an as-molded state. <9> The method for manufacturing a stator 4 according to any one of <2> to <8>, wherein a glass transition temperature Tg of a cured product of the thermosetting resin composition is 120°C or higher.

[0076] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations can also be adopted.

[0077] The present invention will be described in detail below using examples, but the present invention is not limited to the descriptions of these examples. The following examples show evaluation 1 (Example 1, Comparative Example 1) on the thermosetting resin composition and evaluation 2 (Examples 2, 3, and 4) on the mold core.

[0078] <Evaluation 1> Evaluation 1 illustrates a thermosetting resin composition corresponding to the resin layer 50 of the embodiment. The raw material components used in Example 1 and Comparative Example 1 are shown below.

[0079] (Inorganic fillers) Inorganic filler 1: fused spherical alumina (manufactured by Micron Co., Ltd., average particle size 20 μm) Inorganic filler 2: fused spherical silica (manufactured by Tokuyama Corporation, average particle size 0.2 μm) Inorganic filler 3: fused spherical alumina (manufactured by Admatechs Co., Ltd., average particle size 0.6 μm)

[0080] (Colorants) Colorant 1: Carbon black

[0081] (Coupling materials) Coupling material 1: N-phenyl-3-aminopropyltrimethoxysilane Coupling material 2: 3-mercaptopropyltrimethoxysilane

[0082] (Epoxy resins) Epoxy resin 1: biphenyl-type epoxy resin (manufactured by Mitsubishi Chemical Corporation, YX4000HK) Epoxy resin 2: triphenolmethane-type phenol resin (manufactured by Mitsubishi Chemical Corporation, YL6677)

[0083] (Curing Agents) Curing Agent 1: Novolac-type phenol compound (manufactured by Sumitomo Bakelite Co., Ltd.)

[0084] (Curing accelerator) ・Curing accelerator 1: Tetraphenylphosphonium 4,4'-sulfonyldiphenolate ・Curing accelerator 2: Tetraphenylphosphonium bis(naphthalene-2,3-dioxy)phenylsilicate

[0085] (Waxes (release agents)) Wax 1: Carnauba wax (manufactured by Air Water Inc.) Wax 2: Montanic acid derivative (Licowax E, manufactured by Clariant Japan Co., Ltd.) Wax 3: Diethanolamine dimontanic acid ester

[0086] (Ion Scavenger) Ion Scavenger 1: Hydrotalcite (manufactured by Kyowa Chemical Industry Co., Ltd.)

[0087] (Other additives) Triazole compound 1: Triazole compound (manufactured by Shikoku Chemicals Corporation)

[0088] (Low stress material) Silicone resin: silicone oil (KR-480, manufactured by Shin-Etsu Chemical Co., Ltd.) Silicone resin: epoxy polyether modified silicone oil (FZ-3730, manufactured by Dow Corning Toray Co., Ltd.)

[0089] (Preparation of Resin Composition) First, the raw materials formulated according to Table 1 were mixed at room temperature using a mixer, and then kneaded at 70° C. to 110° C. Next, the resulting kneaded mixture was cooled and then pulverized to obtain a resin composition.

[0090] The resin compositions obtained in the examples were subjected to the following measurements. The measurement results are shown in Table 1.

[0091] (Glass Transition Temperature Tg) For each example, the glass transition temperature of the cured product of the obtained resin composition was measured as follows. First, the encapsulating resin composition was injection molded using a transfer molding machine at a mold temperature of 175°C, an injection pressure of 9.8 MPa, and a curing time of 5 minutes to obtain a test piece measuring 15 mm x 3 mm x 4 mm. Next, using a thermomechanical analyzer (Seiko Instruments Inc., TMA100), measurements were performed under conditions of a measurement temperature range of 40°C to 300°C and a heating rate of 5°C / min. The glass transition temperature was calculated from the measurement results.

[0092] (Thermal Conductivity) The resin composition obtained in each example was injection molded into an encapsulating resin composition using a transfer molding machine at a mold temperature of 175°C, an injection pressure of 9.8 MPa, and a curing time of 3 minutes to obtain a cured product of 10 mm x 10 mm x 1 mm. The thermal conductivity of the obtained cured product was calculated using the following formula from the thermal diffusion coefficient (α) measured by the laser flash method (half-time method), the specific heat (Cp) measured by the DSC method, and the density (ρ) measured in accordance with JIS K 6911. The unit of thermal conductivity is W / m K. Thermal conductivity [W / m K] = α [mm ２ / s]×Cp[J / kg・K]×ρ[g / cm ３ ]

[0093]

[0094] <Evaluation 2> In Evaluation 2, three mold cores (blades) were prepared for the mold core 80 (blade) of the embodiment, and the following evaluation items were evaluated. The evaluation items were measurements of surface roughness Ra, pull-out force F, and pull-out force F / surface area S. The evaluation results are shown in Table 2.

[0095] (Stator simulation mold) Figure 8 shows the shape of the slot in the stator simulation mold used to measure the pull-out force F and the pull-out force F / surface area S. One slot is shown here. The dimensions of the slot were as follows: Slot width (L1): 4.5 mm Slot length (L2): 24.3 mm Slot height: 150 mm

[0096] (Mold core (blade)) Figure 9 shows the shape of the mold core 80 (blade) used. Figure 9(a) is a plan view, Figure 9(b) is a side view, and Figure 9(c) is a front view. The blackened areas in the figures are the areas that become the blade pressure-receiving area (surface area S). The dimensions of the mold core 80 (blade) corresponding to the blade pressure-receiving area were as follows: Blade pressure-receiving width (L3): 3.9 mm Blade pressure-receiving length (L4): 20.5 mm Blade pressure-receiving height (L5): 156 mm The mold cores 80 used in Examples 3 to 5 had the same shape but different surface conditions.

[0097] <Surface Roughness Ra> The surface roughness Ra of the mold core 80 was measured using a measuring device (manufactured by KEYENCE Corporation) in accordance with JIS B 0601-2001.

[0098] (Pulling force F and pulling force F / surface area S) The above stator simulation mold and mold core 80 were prepared, and the mold core 80 was inserted into the three slots 8 and then sealed with sealing resin. After sealing, hydraulic extraction was performed in the as-molded state, and the pulling force was measured with a pressure measuring device. The temperature during extraction was 80°C, and the blade pressure-receiving area (surface area S) was 70 cm ２ It was.

[0099]

[0100] This application claims priority based on Japanese Patent Application No. 2023-203627, filed December 1, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0101] REFERENCE SIGNS LIST 100 Motor 1 Case 2 Rotor 4 Stator 5 Permanent magnet 6 Yoke portion 7 Teeth portion 8 Slot 9 Coil 21 Coil accommodating portion 41 Stator core 50 Resin layer 51 Teeth inner surface resin layer 52 Teeth outer surface resin layer 53 Yoke inner surface resin layer 62, 72 Inner wall surface 65 Resin sealing portion 80 Mold core (blade)

Claims

1. A thermosetting resin composition used to form an insulating layer by filling a space formed between a blade, which is a die core inserted into a slot of a stator, and a wall surface of the slot, the thermosetting resin composition comprising: an epoxy resin; a curing agent; an inorganic filler; and a wax, the wax containing a higher fatty acid ester or a higher fatty acid amide, the amount of the higher fatty acid ester or the higher fatty acid amide being 1.0 mass% or less relative to the entire thermosetting resin composition.

2. A method for manufacturing a stator in which an insulating layer is provided on a wall surface of a slot using the thermosetting resin composition according to claim 1, comprising: a core placement step of inserting a blade-shaped die core into the inside of the slot to form a filling space between the wall surface of the slot and the die core for filling the thermosetting resin composition; and a resin filling step of filling the filling space with the thermosetting resin composition.

3. A method for manufacturing a stator as set forth in claim 2, wherein the surface roughness Ra of the die core is 10 μm or less.

4. The method for manufacturing a stator according to claim 2 or 3, wherein the surface of the die core has a coating layer.

5. A method for manufacturing a stator as set forth in claim 2 or 3, further comprising a die core removal step of extracting and removing the die core after the resin filling step.

6. A method for manufacturing a stator as set forth in claim 5, wherein in said die core removing step, a pulling force F when removing said die core is 250 kgf or less.

7. In the die core removal process, the ratio F / S of the surface area S of the die core to the pulling force F is 3.6 kgf / cm ２ The method for manufacturing a stator according to claim 6, wherein:

8. The method for manufacturing a stator according to claim 5, wherein the die core removing step is performed in an as-molded state.

9. The method for manufacturing a stator according to claim 2 or 3, wherein the glass transition temperature Tg of the cured product of the thermosetting resin composition is 120° C. or higher.

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