Method for manufacturing stator

Abstract

The present invention provides a method for manufacturing a stator (4), wherein a resin layer is formed using a mold for forming a resin layer on wall surfaces (a teeth wall surface (72) and a yoke wall surface (62)) of a slot (8) inside the slot (8) which is a space between teeth (7) that extend from an annular yoke part (6). The mold has a blade (80) that is housed inside the slot (8), and the resin layer (50) is formed by filling a space, which is formed between the blade (80) and the wall surfaces of the slot (8) when the blade (80) is housed therein, with a resin material. The blade (80) is provided with a draft on a surface that faces the wall surfaces of the slot (8), and the draft is 15 μm to 100 μm. The surface roughness Ra of the surface that is provided with the draft is 0.2 μm to 2 μm.

Description

Stator manufacturing method

[0001] The present invention relates to a method for manufacturing a stator.

[0002] In rotating electrical machines such as motors and generators, when a coil is placed in a slot provided in a stator, a technique is known in which insulating paper or a resin material is filled into the slot to ensure insulation between the slot and the coil (see, for example, Patent Document 1). Patent Document 1 discloses a technique in which resin is injected between the coil and the peripheral wall of the slot and hardened to form an insulating layer.

[0003] Patent No. 6814568

[0004] To improve motor performance, a thin insulation layer is desirable for accurately arranging the coils while maintaining proper insulation, and for improving the space utilization efficiency of the slots. When molding the insulation layer inside the slots, if the molded parts (called blades or cores) are pulled out with a large force, the insulation layer may be damaged, and a technology to address this issue has been sought.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a technology that prevents the insulating layer from being damaged when the molded parts of the mold are pulled out when molding the insulating layer inside the slot.

[0006] The present invention provides the following technologies: (1) A method for manufacturing a stator, comprising: forming a resin layer on a wall surface of a slot, which is a space between teeth extending from an annular yoke portion, using a mold for molding the resin layer inside the slot, wherein the mold has a blade to be accommodated inside the slot, and the resin layer is formed by filling a resin material into a space formed between the wall surface of the slot and the blade when the blade is accommodated, and wherein a draft is set on a surface of the blade facing the wall surface of the slot, the draft being 15 μm or more and 100 μm or less, and the surface roughness Ra of the surface on which the draft is set is 0.2 μm or more and 2 μm or less. (2) The method for manufacturing a stator described in (1), wherein the surface roughness RSm of the surface on which the draft is set is 200 μm or more and 700 μm or less. (3) The method for manufacturing a stator described in (1) or (2), wherein the draft is set on a surface of the blade facing the wall surface of the teeth in the slot. (4) The method for manufacturing a stator according to (3), wherein the draft angle is set on a surface of the blade facing a wall surface of the yoke portion within the slot. (5) The method for manufacturing a stator according to (4), wherein a space formed between the wall surface of the slot and the blade when the blade is accommodated is formed by closing tips of adjacent teeth portions with a mold member separate from the blade, and the draft angle is set on a surface of the blade facing the mold member. (6) The method for manufacturing a stator according to any one of (1) to (5), wherein the resin layer is a cured product of a resin material, and the resin material consists of one or two thermosetting resins selected from the group consisting of epoxy resins and phenolic resins. (7) The method for manufacturing a stator according to any one of (1) to (6), wherein the thickness of the resin layer is 100 μm or more and 400 μm or less. (8) The method for manufacturing a stator according to any one of (1) to (7), wherein the axial length of the slot is 100 mm or more and 300 mm or less.(9) The method for manufacturing a stator according to any one of (1) to (8), wherein the region in which the draft angle is set in the blade includes at least a region through which the blade passes within the slot when pulled out of the slot.

[0007] According to the present invention, it is possible to provide a technique for preventing the insulating layer from being damaged when the molded part of the mold is pulled out when molding the insulating layer in the slot.

[0008] 4 is a cross-sectional view perpendicular to the rotational axis direction of the motor according to the embodiment. FIG. 5 is a longitudinal cross-sectional view in the rotational axis direction of the motor according to the embodiment. FIG. 6 is an enlarged view of the periphery of a slot according to the embodiment. FIG. 7 is an enlarged view of the periphery of a slot according to the embodiment, showing the coils and resin sealing portion in the slot from FIG. 3. FIG. 8 is a cross-sectional view of the periphery of a slot according to the embodiment, taken along the line A-A in FIG. 3. FIG. 9 is a cross-sectional view of the periphery of a slot according to the embodiment, taken along the line B-B in FIG. 4. FIG. 10 is a flowchart showing a method for manufacturing a stator according to the embodiment. FIG. 11 is a view explaining the transition of the state inside a slot in a resin layer forming step according to the embodiment. FIG. 12 is a view explaining the transition of the state inside a slot in a resin layer forming step according to the embodiment. FIG. 13 is a view showing a blade according to the embodiment. FIG. 14 is a view explaining the size of the slot in the example.

[0009] <Overview> In this embodiment, an example will be described in which the present invention is applied to an electric motor (motor) as a rotating electric machine (electric motor, generator, or dual-purpose electric motor / generator). 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 along the rotational axis direction. FIG. 3 is an enlarged view of the slot periphery (area X in FIG. 1 ), showing a cross-sectional view of the portion where coil 9 protrudes from the end of slot 8. FIG. 4 is a diagram of FIG. 3 , omitting the coil 9 in slot 8 and resin sealing portion 65. FIG. 5 is a cross-sectional view taken along A-A in FIG. 3 . FIG. 6 is a cross-sectional view taken along B-B in FIG. 4 . Note that in FIGS. 3 and 4 , the resin layer 50 is indicated by black ink for convenience. In the following description, the rotating shaft 3 side of motor 100 will be referred to as the inner periphery (or rotating shaft side), and the case 1 side will be referred to as the outer periphery.

[0010] The outline of this embodiment is as follows. In a motor 100, the wall surfaces (tooth wall surfaces 72, yoke wall surfaces 62) of slots 8 of a stator 4 are covered with a resin layer 50 made of an insulating resin composition. At this time, a draft gradient is set in a mold core (hereinafter, blade 80) and the surface roughness of the blade surface is set, thereby suppressing the pull-out force of the blade 80 and preventing damage to the insulating layer. Note that in this embodiment, the draft gradient refers to the gradient of the inclined surface on the cross section set for removing the blade 80, and is explained as the horizontal length of the inclined surface when the removal direction is defined as the vertical direction and the horizontal direction is defined relative to that. A specific explanation will be given below.

[0011] <Basic Structure of Motor 100 > The motor 100 includes a case 1 , and a rotor 2 , a stator 4 , and a coil 9 housed inside the case 1 .

[0012] <Case 1> 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.

[0013] <Rotor 2> The rotor 2 is housed inside the case 1. A rotating shaft 3 is attached to the center of the rotor 2 as an output shaft. Both ends of the rotating 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 rotating shaft 3.

[0014] 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 different from each other.

[0015] A cylindrical stator 4 is disposed and fixed on the inner periphery of the cylindrical portion 1a so as to surround the outer periphery of the rotor 2. A minute gap (air gap) is provided between the inner periphery of the stator 4 and the outer periphery of the rotor 2.

[0016] <Stator 4> The stator 4 includes a stator core 41 and coils 9 sealed in slots 8. The stator core 41 is formed by stacking and closely fixing multiple electromagnetic steel plates in the axial direction. As shown in FIG. 1 , when viewed from the axial end, the stator core 41 includes an annular yoke portion 6 and multiple teeth portions 7 extending from the yoke portion 6 toward the rotor 2 (inner periphery). The multiple 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 tooth portion 7. The teeth portions 7 are also provided with a thin resin layer 50 formed by wrapping a resin composition around the teeth portions 7. The axial length of the stator 4 is, for example, 100 mm or more and 300 mm or less. A motor 100 including a stator 4 of this size is suitable, for example, as a drive motor for an electric vehicle.

[0017] <Coil 9> 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. Here, the coil 9 is housed in a liner member 20 arranged in the slot 8 in a distributed winding manner. 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. The resin coating layer can be made of the same material as that described below as the resin material for the resin layer 50.

[0018] <Teeth portion 7> 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] <Slot 8> The slot 8 is a space between adjacent teeth 7, and is provided so that the tooth wall surfaces 72 of the teeth 7 that face each other in the radial direction are parallel to each other. The space between the tooth tips 71 forms an opening on the inner circumferential side of the slot 8. The slot 8 includes a plurality of coils 9 arranged on the outer circumferential side (the yoke portion 6 side) and a resin sealing portion 65 provided on the inner circumferential side (the tooth tip 71 side).

[0021] <Resin layer 50> As shown in Figures 3 to 5, for example, resin layer 50 is formed by integrally wrapping a resin composition around the periphery of tooth portion 7 to cover it, and includes a teeth inner surface resin layer 51 that covers the inner wall surface of tooth portion 7 (tooth wall surface 72), a teeth outer surface resin layer 52 that covers the upper surface 75a and lower surface 75b of tooth portion 7, and a yoke inner surface resin layer 53 that covers the inner wall surface of yoke portion 6 (yoke wall surface 62).

[0022] Resin layer 50 is inserted into the stator 4, and is thinly formed to surround and cover tooth portion 7, thereby tightly fixing the stacked electromagnetic steel sheets in tooth portion 7. Resin layer 50 does not necessarily have to be thinly formed to surround tooth portion 7, 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 (tooth wall surface 72 of tooth portion 7 and yoke wall surface 62 of yoke portion 6) is ensured.

[0023] The tooth inner surface resin layer 51 has a thickness of 100 μm or more and 400 μm or less. The lower limit of the thickness is preferably 150 μm or more, and more preferably 200 μm or more. The upper limit of the thickness is preferably 350 μm or less, and more preferably 300 μm or less.

[0024] It is preferable that the lower limit of the thickness be within the above range from the viewpoint of ensuring the fluidity of the resin composition in the extremely narrow portion between the mold (blade 80) and the tooth portion 7 (tooth wall surface 72) relative to the axial length of the stator (i.e., the thickness of the stator 4) during insert molding.

[0025] In a structure in which the coil 9 is wound around the tooth portion 7 and placed in the slot 8, it is preferable to set the upper limit of the thickness within the above range from the viewpoint of increasing the space utilization efficiency within the slot 8, ensuring the degree of freedom in the size of the coil 9 that can be used, and ensuring performance such as magnetic flux density.

[0026] The thickness of yoke inner surface resin layer 53 may be the same as or different from the thickness range of tooth inner surface resin layer 51. The thickness of tooth outer surface resin layer 52 is not particularly limited, but may be approximately the same as that of tooth inner surface resin layer 51.

[0027] As will be described later, the surface of the blade 80 used to form the resin layer 50 has a draft slope on one side. In the area in contact with the surface with the draft slope, the thickness of the resin layer 50 (tooth inner surface resin layer 51) reflects the draft slope. For example, as shown in Fig. 6, the tooth inner surface resin layer 51 is thicker on the lower side (lower surface 75b side) and thinner on the upper side (upper surface 75a side).

[0028] <Physical Properties of Resin Layer 50> 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, for example, 10 W / (m·K).

[0029] 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.

[0030] <Materials of Resin Layer 50> The resin composition of the resin layer 50 preferably contains a thermosetting resin (A), a filler (B), a curing agent (C), and the like.

[0031] [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 and phenolic 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] The content of 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 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 resin layer 50. When the content of thermosetting resin (A) is equal to or greater than the above-mentioned lower limit, the handleability of the total amount of the resin composition of resin layer 50 is improved, making it easier to form teeth inner surface resin layer 51 and improving the strength of teeth inner surface resin layer 51. When the content of thermosetting resin (A) is equal to or less than the above-mentioned upper limit, the linear expansion coefficient and elastic modulus of teeth inner surface resin layer 51 are further improved, and the thermal conductivity is further improved.

[0036] [Filler (B)] The filler (B) in this embodiment is used from the viewpoint of improving the thermal conductivity of the resin layer 50 (more specifically, the tooth inner surface resin layer 51) and obtaining strength.

[0037] 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.

[0038] 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.

[0039] [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).

[0040] The curing agent (C) can be one or more selected from the group consisting of a curing catalyst (C-1) and a phenolic curing agent (C-2). 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; Examples of suitable curing catalysts include imidazoles such as 2-phenyl-4,5-dihydroxymethylimidazole; organic phosphorus compounds such as triphenylphosphine, tri-p-tolylphosphine, tetraphenylphosphonium tetraphenylborate, triphenylphosphine-triphenylborane, and 1,2-bis-(diphenylphosphino)ethane; phenolic compounds such as phenol, bisphenol A, and nonylphenol; and organic acids such as acetic acid, benzoic acid, salicylic acid, and p-toluenesulfonic acid, or mixtures thereof. As the curing catalyst (C-1), one of these compounds, including derivatives thereof, can be used alone, or two or more of these compounds, including derivatives thereof, can be used in combination. 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.

[0041] Examples of the phenolic curing agent (C-2) include novolac-type phenolic resins such as phenol novolac resins, cresol novolac resins, trisphenolmethane novolac resins, naphthol novolac resins, and aminotriazine novolac resins; modified phenolic resins such as terpene-modified phenolic resins and dicyclopentadiene-modified phenolic resins; 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 resole-type phenolic resins, and these may be used alone or in combination of two or more. 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-type phenolic resin or a resole-type phenolic resin.

[0042] The content of the phenolic curing agent (C-2) is not particularly limited, but is preferably 1% by mass or more, more preferably 5% by mass or more, relative to the total amount of the resin composition, while the content is preferably 30% by mass or less, more preferably 15% by mass or less, relative to the total amount of the resin composition.

[0043] [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).

[0044] The coupling agent (D) is not particularly limited, but it is preferable to use one or more coupling agents selected from, for example, epoxy silane coupling agents, cationic silane coupling agents, amino silane coupling agents, titanate coupling agents, and silicone oil coupling agents. The content of the coupling agent (D) is not particularly limited, but it 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). On the other hand, 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 voids from occurring. Furthermore, when the resin layer 50 is used in close contact with a metal member (i.e., the teeth portion 7), 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.

[0048] The content of the phenoxy resin (E) is preferably, for example, 3 mass % or more and 10 mass % or less relative to the total amount of the resin composition.

[0049] [Mold Release Agent] The resin composition preferably contains a mold release agent. This can improve mold releasability after molding. Examples of mold release agents 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, and paraffin. These may be used alone or in combination of two or more.

[0050] When a 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 tooth inner surface resin layer 51 of the resin layer 50 can be improved.

[0051] [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.

[0052] <Resin Sealing Portion 65> The resin sealing portion 65 is provided on the inner circumferential side of the slot 8 (toward the tooth tip 71). 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 that described for the resin layer 50.

[0053] <Method of Manufacturing Stator 4> A method of manufacturing the stator 4 of this embodiment will be described. Fig. 7 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).

[0054] Next, the blade 80 is placed in the slot 8, and the periphery of the tooth portion 7 (the tooth wall surface 72, the upper surface 75a, and the lower surface 75b) and the inner wall surface of the yoke portion 6 (the yoke wall surface 62) are integrally covered with an insulating resin composition by insert molding to form the resin layer 50 (resin layer forming step S20). The resin layer forming step S20 will be described in detail later.

[0055] 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).

[0056] Next, the resin layer forming step S20 will be described in more detail with reference to the above flowchart and Figures 8 and 9. Figures 8 and 9 show the transition of the state inside the slot 8 in the resin layer forming step S20, with Figure 8 being a cross-sectional view cut along a plane perpendicular to the axis, and Figure 9 being a cross-sectional view of a portion corresponding to the A-A cross section in Figure 3.

[0057] The resin layer forming step S20 includes a core placing step S21, a resin filling step S22, and a mold core removing step S23.

[0058] 8(a) and 9(a) show a state before the blade 80 is inserted. As shown in FIGS. 8(b) and 9(b), the core placement step S21 is a step of inserting the blade 80 into the slot 8. In this embodiment, the blade 80 is inserted into the slot 8 from the upper side as shown in the drawing. At this time, the upper and lower ends of the blade 80 protrude from the upper and lower ends of the slot 8.

[0059] The core placement step S21 forms a space 88 for filling with a thermosetting resin composition between the wall surfaces of the slot 8 (the tooth wall surfaces 72 of the tooth portion 7 and the yoke wall surfaces 62 of the yoke portion 6) and the blade 80. Because a draft angle is set in the blade 80, the distance between the inner wall surface of the slot 8 and the blade 80 becomes wider as it approaches the lower surface 75b.

[0060] Next, as shown in Figures 8(c) and 9(c), the resin filling step S22 is a step of filling the space 88 formed by the core placement step S21 with the above-mentioned thermosetting resin composition.

[0061] As shown in FIGS. 8( d ) and 9 ( d ), the mold core removal process S23, which follows the resin filling process S22, involves removing the blade 80 by pulling it out. This process is performed in the as-molded state, i.e., without any after-curing. The temperature of the resin layer 50 at this time is, for example, 100°C. An access hole 85 is provided near the upper end 80a of the blade 80. A predetermined jig is attached to this hole 85, and the blade 80 is pulled out in the upward direction as shown. The resin layer 50 is formed on the wall surfaces of the slot 8 (the tooth wall surfaces 72 of the tooth portion 7 and the yoke wall surfaces 62 of the yoke portion 6). The blade 80 has a draft angle, which makes it easier to pull out the blade 80. This reduces the pulling force and minimizes damage to the resin layer 50 compared to when there is no draft angle.

[0062] <Blade 80> The blade 80 used in the resin layer forming step S20 will be described. The blade 80 is provided in an appropriate shape depending on the shape of the slot 8 and the resin layer 50, but in this embodiment, it has a long, thin blade shape. Figure 10(a) is a front view of the blade 80, Figure 10(b) is a side view, and Figure 10(c) is a plan view.

[0063] Specifically, the blade 80 has first to fourth blade surfaces 81 to 84 as surfaces to be accommodated in the slot 8. The first blade surface 81 and the second blade surface 82 are surfaces facing the tooth wall surface 72 of the tooth portion 7. The third blade surface 83 is a surface facing the yoke wall surface 62. The fourth blade surface 84 is a surface facing the space between the tooth portion tips 71, and when the space between the tooth portion tips 71 is closed by a mold member, it is a surface facing the mold member.

[0064] When the first to fourth blade surfaces 81 to 84 are accommodated in the slot 8, the end in the insertion direction and the end on the front side in the insertion direction protrude from the slot 8. The end on the front side is provided with a through-hole 85 to which a predetermined jig can be attached for operating the blade 80.

[0065] When the blade 80 is accommodated in the slot 8, the distance between the blade 80 and the slot 8 (including the mold member 95) corresponds to the thickness of the resin layer 50. In this embodiment, the blade 80 has a draft, and therefore the distance changes depending on the draft.

[0066] In the blade 80, draft gradients d1 and d2 are set on the surfaces (first blade surface 81, second blade surface 82, third blade surface 83) facing the wall surfaces (tooth wall surface 72, yoke wall surface 62) of the slot 8. In particular, the draft gradient d1 is set on the first blade surface 81 and the second blade surface 82 facing the tooth wall surface 72, which has a large area. Note that the draft gradient may be set on only either the first blade surface 81 or the second blade surface 82. The draft gradient d1 can be set, for example, from 15 μm to 100 μm. The lower limit of the draft gradient is preferably 17 μm or more, and more preferably 20 μm or more. The upper limit of the draft gradient is preferably 50 μm or less, and more preferably 40 μm or less.

[0067] When the blade 80 is accommodated in the slot 8, the tooth tip 71 of the adjacent tooth portion 7 may be closed by a mold member other than the blade 80. In this case, a draft may be set on the surface of the blade 80 facing the mold member (fourth blade surface).

[0068] The region of blade 80 where the draft angle is set is at least the region that passes through slot 8 when the blade is pulled out of slot 8, more specifically, the draft angle is set in the portion that faces resin layer 50 when resin layer 50 is formed. In other words, the draft angle does not need to be set in the portion that protrudes out of slot 8 when resin layer 50 is molded.

[0069] The blade 80 can be made of a general mold steel material, for example, SKD-11 (JIS standard).

[0070] The surfaces of the blade 80 (surfaces that come into contact with the resin layer 50), specifically the first to fourth blade surfaces 81 to 84, are smoothed so that the surface roughnesses Ra and RSm fall within the specified ranges as follows. This makes it possible to avoid distortion or other effects on the resin layer 50 when the blade 80 is pulled out.

[0071] The surface roughness Ra of the blade 80 is 0.2 μm or more and 2 μm or less. The lower limit is not particularly limited as the smoother the surface, and any value above the above value may be used as a practical value. The upper limit is preferably 2.0 μm or less, and more preferably 1.5 μm or less. The surface roughness Ra is measured in accordance with JIS B 0601-2001. By smoothing the surface of the blade 80 so that the surface roughness Ra of the blade 80 falls within the above range, the pullability of the blade 80 can be improved while ensuring adhesion of the resin layer 50 to the stator core 41.

[0072] The surface roughness RSm of the blade 80 is 200 μm or more and 700 μm or less. The lower limit is not particularly limited as the smoother the surface, and any value above the above value is sufficient as a practical value. The upper limit is preferably 600 μm or less, and more preferably 500 μm or less. The surface roughness RSm is measured in accordance with JIS B 0601-2001. By smoothing the surface of the blade 80 so that the surface roughness RSm of the blade 80 falls within the above range, the pullability of the blade 80 can be improved while ensuring adhesion of the resin layer 50 to the stator core 41.

[0073] The surfaces of the blades 80 for which the surface roughnesses Ra and RSm are set as described above are particularly set on the first blade surface 81 and the second blade surface 82 that face the large-area tooth wall surface 72, but only one of them may be set. The third blade surface 83 and the fourth blade surface, which have relatively small areas, may have surface roughnesses Ra and RSm that are larger than the above ranges to a certain extent.

[0074] Summary of the embodiment The features of the present embodiment can be summarized as follows: (1) A method for manufacturing a stator 4, in which a resin layer is formed inside a slot 8, which is a space between teeth 7 extending from an annular yoke portion 6, using a mold for molding the resin layer on wall surfaces (tooth wall surfaces 72, yoke wall surfaces 62) of the slot 8, the mold having a blade 80 to be accommodated inside the slot 8, the resin layer 50 being formed by filling a resin material into a space formed between the wall surfaces (tooth wall surfaces 72, yoke wall surfaces 62) of the slot 8 and the blade 80 when the blade 80 is accommodated, a draft is set on a surface of the blade 80 facing the wall surfaces (tooth wall surfaces 72, yoke wall surfaces 62) of the slot 8, the draft is 15 μm or more and 100 μm or less, and the surface on which the draft is set has a surface roughness Ra of 0.2 μm or more and 2 μm or less. (2) The method for manufacturing a stator 4 according to (1), wherein a surface roughness RSm of the surface on which the draft is set is 200 μm or more and 700 μm or less. (3) The method for manufacturing a stator 4 according to (1) or (2), wherein the draft is set on a surface of the blade 80 that faces a wall surface (tooth wall surface 72) of the tooth portion 7 within the slot 8. (4) The method for manufacturing a stator 4 according to (4), wherein the draft is set on a surface of the blade 80 that faces a wall surface (yoke wall surface 62) of the yoke portion 6 within the slot 8. (5) The method for manufacturing a stator 4 according to (4), wherein when the blade 80 is accommodated, a space formed between the wall surface (tooth wall surface 72, yoke wall surface 62) of the slot 8 and the blade 80 is formed by closing the tip (71) of the adjacent tooth portion 7 with a mold member separate from the blade 80, and the draft is set on a surface of the blade 80 that faces the mold member. (6) The method for manufacturing a stator according to any one of (1) to (5), wherein the resin layer 50 is a cured product of a resin material, and the resin material is made of one or two types of thermosetting resin selected from the group consisting of epoxy resins and phenolic resins.(7) The method for manufacturing a stator according to any one of (1) to (6), wherein the resin layer 50 has a thickness of 100 μm or more and 400 μm or less. (8) The method for manufacturing a stator according to any one of (1) to (7), wherein the axial length of the slot 8 is 100 mm or more and 300 mm or less. (9) The method for manufacturing a stator 4 according to any one of (1) to (8), wherein the region in which the draft angle is set in the blade 80 includes at least a region that passes through the slot 8 when the blade 80 is pulled out of the slot 8.

[0075] 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.

[0076] The present invention will be described in detail below using examples, but the present invention is not limited to the descriptions of these examples. In the following examples, mock molds for a stator and blades were prepared, and a resin layer (corresponding to the resin layer 50 in the embodiment) was formed on the inner wall surface of the slot, and the relationship between the draft angle, surface roughness Ra, RSm of the blade, and pullability was evaluated.

[0077] <Composition of Thermosetting Resin Composition> The thermosetting resin compositions (materials of the resin layer 50) used in the evaluation are as follows.

[0078] (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)

[0079] (Colorants) Colorant 1: Carbon black

[0080] (Coupling materials) Coupling material 1: N-phenyl-3-aminopropyltrimethoxysilane Coupling material 2: 3-mercaptopropyltrimethoxysilane

[0081] (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)

[0082] (Curing Agents) Curing Agent 1: Novolac-type phenol compound (manufactured by Sumitomo Bakelite Co., Ltd.)

[0083] (Curing accelerator) ・Curing accelerator 1: Tetraphenylphosphonium 4,4'-sulfonyldiphenolate ・Curing accelerator 2: Tetraphenylphosphonium bis(naphthalene-2,3-dioxy)phenylsilicate

[0084] (Wax (release agent)) Wax 1: Carnauba wax (manufactured by Air Water Inc.) Wax 3: Diethanolamine dimontanic acid ester

[0085] (Ion Scavenger) Ion Scavenger 1: Hydrometasite (manufactured by Kyowa Chemical Industry Co., Ltd.)

[0086] (Other additives) Troazole compound 1: Triazole compound (manufactured by Shikoku Chemicals Corporation)

[0087] (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.)

[0088] (Preparation of Resin Composition) First, the raw materials formulated according to Table 1 were mixed at room temperature using a mixer, and then roll-kneaded at 70° C. or higher and 110° C. or lower. Next, the resulting kneaded mixture was cooled and then pulverized to obtain a resin composition.

[0089] (Stator simulation mold) Figure 11 shows the shape of the slots in the stator simulation mold. One slot is shown here. The dimensions of the slots were as follows: Slot width (L1): 4.5 mm Slot length (L2): 24.3 mm Slot height: 150 mm

[0090] (Blade (mold core)) A blade with the same shape as that shown in Figure 10 was used. As described above, Figure 10(a) is a plan view, Figure 10(b) is a side view, and Figure 10(c) is a front view. Draft gradients were set in the blackened areas in the figure (surfaces corresponding to the first blade surface 81 and second blade surface 82 in the embodiment) according to Examples 1 to 4 and Comparative Examples 1 to 4. In addition, the surface roughness of the regions where the draft gradients were set was set according to Examples 1 to 4 and Comparative Examples 1 to 4. The set draft gradients and surface roughnesses Ra and RSm were as shown in Table 2.

[0091] <Surface Roughness Ra, RSm> The surface roughness Ra and RSm of the blade surface were measured using a measuring device (manufactured by Keyence Corporation, model number VR-5000) in accordance with JIS B 0601-2001.

[0092] <Molding of Resin Layer> The resin composition obtained above was placed in a slot with a blade, and the resin composition was filled into the space between the slot and the blade. The blade was then pulled out in an as-molded state (temperature 100° C.). The maximum thickness of the resin layer was 300 μm, and the minimum thickness was set to a thickness obtained by subtracting the set draft angle.

[0093] <Resin distortion when blade is removed> After the blade was removed from the slot, the state of the resin layer was visually inspected and evaluated based on whether distortion had occurred. The evaluation results are shown in Table 2. The evaluation was performed according to the following evaluation criteria A to C. A: No distortion was visible to the naked eye. B: Slight distortion was visible to the naked eye. C: Distortion was visible to the naked eye.

[0094] <Coil Filling> When a blade was placed in a slot, resin was filled in, and a resin layer was formed, the occurrence of short shots (a state in which the resin is cooled without being filled) was visually confirmed. The results are shown in Table 2. The evaluation was performed according to the following two-level evaluation criteria. OK: No short shots occurred. NG: Short shots occurred.

[0095]

[0096] This application claims priority based on Japanese Patent Application No. 2024-042078, filed March 18, 2024, the disclosure of which is incorporated herein by reference in its entirety.

[0097] REFERENCE SIGNS LIST 100 Motor 1 Case 2 Rotor 4 Stator 6 Yoke portion 7 Teeth portion 8 Slot 9 Coil 50 Resin layer 51 Teeth inner surface resin layer 52 Teeth outer surface resin layer 55 Resin layer surface 55a, 55b End portion 62 Yoke wall surface 65 Resin sealing portion 71 Teeth portion tip 72 Teeth wall surface 80 Blade 81 First blade surface 82 Second blade surface 83 Third blade surface 84 Fourth blade surface 100 Motor

Claims

1. A method for manufacturing a stator, in which a resin layer is formed inside a slot, which is the space between teeth extending from an annular yoke portion, using a mold for molding the resin layer on the wall surface of the slot, wherein the mold has a blade to be housed inside the slot, and the resin layer is formed by filling a resin material into the space formed between the wall surface of the slot and the blade when the blade is housed, and a draft angle is set on the surface of the blade facing the wall surface of the slot, and the draft angle is 15 μm or more and 100 μm or less, and the surface roughness Ra of the surface on which the draft angle is set is 0.2 μm or more and 2 μm or less.

2. The method for manufacturing a stator according to claim 1, wherein the surface roughness RSm of the surface on which the draft is set is 200 μm or more and 700 μm or less.

3. A method for manufacturing a stator according to claim 1 or 2, wherein the draft angle is set on the surface of the blade that faces the wall surface of the tooth portion within the slot.

4. A method for manufacturing a stator according to claim 3, wherein the draft angle is set on the surface of the blade that faces the wall surface of the yoke portion within the slot.

5. A method for manufacturing a stator as described in claim 4, wherein the space formed between the wall surface of the slot and the blade when the blade is accommodated is formed by closing the tips of the adjacent teeth with a mold member separate from the blade, and the draft angle is set on the surface of the blade facing the mold member.

6. A method for manufacturing a stator according to any one of claims 1 to 5, wherein the resin layer is a cured resin material, and the resin material is made of one or two types of thermosetting resin selected from the group consisting of epoxy resins and phenolic resins.

7. A method for manufacturing a stator according to any one of claims 1 to 6, wherein the resin layer has a thickness of 100 μm or more and 400 μm or less.

8. A method for manufacturing a stator according to any one of claims 1 to 7, wherein the axial length of the slot is 100 mm or more and 300 mm or less.

9. A method for manufacturing a stator according to any one of claims 1 to 8, wherein the region in which the draft angle is set in the blade includes at least the region through which the blade passes within the slot when pulled out of the slot.

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