JP2024148868A - Prepreg mica tape, rotating electric machine, and method for manufacturing rotating electric machine - Google Patents

Abstract

[Problem] To provide a prepreg mica tape capable of suppressing the occurrence of discharge during voltage application. [Solution] A prepreg mica tape 30 comprises a laminate (mica tape MT) in which a substrate 33 and mica paper 31 are laminated, varnish impregnated into the mica tape MT and brought to a semi-cured state, and an unreacted thermosetting raw resin (resin layer 34) that is in a solid state at room temperature and is provided on at least one of the front and back surfaces of the mica tape MT impregnated with the varnish, the unreacted thermosetting raw resin being in a solid state at room temperature being a thermosetting resin that melts when heated to become liquid and then hardens. [Selected Figure] Figure 3

Description

The present invention relates to prepreg mica tape, a rotating electric machine, and a method for manufacturing a rotating electric machine.

Thermosetting resins, which have high electrical insulation (insulation reliability) and excellent mechanical properties, are widely used to insulate and secure coils used in electrical equipment (generators, electric motors, transformers, etc.). And mica insulation systems, which have high insulation reliability, are used to insulate high-voltage rotating electrical machines such as generators and electric motors. For example, the prepreg method is known as one of the manufacturing methods for the mica insulation systems used in the stator windings that make up rotating electrical machines.

In the conventional prepreg method, mica tape is impregnated with varnish (a liquid thermosetting insulating resin) in advance, and the prepreg mica tape is used in which the varnish is in a semi-cured state. First, a coil is manufactured by winding the prepreg mica tape around an insulating conductor, and the coil is heated and pressurized to thermally cure the varnish. Next, the stator winding is manufactured by incorporating the coil into the core slot 13. The prepreg method is suitable for large generators with high voltage and high capacity (for example, large power generators). For example, Patent Document 1 describes a prepreg method technology suitable for large generators.

JP 2010-158113 A

However, if there is a gap between the stator coil and the stator slot, there is a risk of discharge occurring in this gap when voltage is applied. In the conventional prepreg method, a varnish layer is formed on the stator coil before the stator coil is placed in the stator slot, which makes it easy for a gap to form between the stator coil and the stator slot.

The prepreg mica tape according to one aspect of the present invention comprises a laminate of a base material and mica paper, a varnish impregnated into the laminate and brought into a semi-cured state, and a resin layer formed on at least one of the front and back surfaces of the laminate impregnated with the varnish and composed of an unreacted thermosetting raw resin that is in a solid state at room temperature, the unreacted thermosetting raw resin being in a solid state at room temperature being a thermosetting resin that melts when heated to become liquid and then hardens.

The present invention makes it possible to suppress the occurrence of discharge during voltage application.

FIG. 1 is a cross-sectional view that illustrates an example of the configuration of a rotating electric machine. FIG. 2 is a cross-sectional view showing a schematic example of a single coil shown in FIG. FIG. 3 is a diagram showing the prepreg mica tape of this embodiment. FIG. 4 is a diagram showing another example of a prepreg mica tape. FIG. 5 is an enlarged perspective view of a portion of the stator winding of FIG. 1. FIG. 6 is a cross-sectional view of the stator winding taken along plane H shown in FIG. FIG. 7 is an enlarged view showing the final state of the stator windings after the heat-setting process. FIG. 8 is a schematic diagram showing the overlapping state of the prepreg mica tape in the case of a single wrap. FIG. 9 is a schematic diagram showing the overlapping state of the prepreg mica tape when wrapped twice. FIG. 10 is a schematic diagram of the temperature profile of the flow and hardening process.

An embodiment of the present invention will be described with reference to Figures 1 to 10. Note that substantially the same or similar configurations are given the same reference numerals, and where explanations are redundant, they may be omitted.

<Prepreg mica tape>
Fig. 1 is a cross-sectional view showing a schematic example of the configuration of a rotating electric machine 1. The rotating electric machine 1 includes a stator winding 10 and a rotor 9. The stator winding 10 includes a stator core 11 having a plurality of core slots 13, and coil units 12 accommodated in the core slots 13. In the example shown in Fig. 1, two coil units 12 are provided radially side by side in one core slot 13. Although not shown, in the stator winding 10, the coil units 12 are wound between one core slot 13 and another core slot 13.

The rotating electric machine has a rotor coil (not shown) inside the stator winding 10 described above. In this way, the stator winding 10 and the rotor coil are used to configure a rotating electric machine such as a generator or an electric motor. When the rotating electric machine is a generator, the rotor coil is rotated by external power and current is taken out from the stator winding 10. When the rotating electric machine is an electric motor, current is passed through the stator winding 10 to rotate the rotor coil and supply power to the outside.

Figure 2 is a cross-sectional view showing a schematic example of the coil unit 12 shown in Figure 1. Note that (A) shows the overall configuration of the coil unit 12, and (B) shows an enlarged portion of the coil unit 12. The coil unit 12 described in this embodiment is formed by tying (twisting) both ends of the coil unit 12 as shown in Figure 2 (A). In other words, one end (for example, the left side of the paper in Figure 2) is formed by tying (twisting) the coil unit 12 and exists outside the stator winding 10. Also, the other end (for example, the right side of the paper in Figure 2) is formed by tying (twisting) the coil unit 12 and exists outside the stator winding 10.

A conductor 21 is exposed at one end of each coil unit 12, and the conductor 21 is exposed to the outside of the stator winding 10. The exposed end of the conductor 21 is connected to an external power source or a storage battery.

The coil unit 12 has a long, straight portion indicated by reference symbol 12a in FIG. 2(A) inserted into the core slot 13. In other words, the coil unit 12 shown in FIG. 2(A) shows the state of the stator winding 10 as viewed from the radial direction.

As shown in FIG. 2(B), the coil unit 12 has a conductor 21 (e.g., a metal wire) with a rectangular cross section, and a mica insulating layer 22 that covers the conductor 21. Prepreg mica tape, which will be described later, is used for the mica insulating layer 22. As shown in FIG. 2(B), the mica insulating layer 22 is formed by winding the prepreg mica tape around a bundle of conductors 21. The conductors 21 are insulated with a resin material or the like, and the conductors 21 are insulated from each other.

Next, the structure of the prepreg mica tape will be described in detail. FIG. 3 is a diagram showing the prepreg mica tape 30 in this embodiment. The prepreg mica tape 30 comprises mica paper 31, an adhesive layer 32, a substrate 33, and a resin layer 34. The mica paper 31 is adhered to the substrate 33 by the adhesive layer 32. Since the mica paper 31 is usually brittle, it is adhered to the substrate 33, which is used as a reinforcing substrate. Hereinafter, the laminate of the mica paper and substrate 33 will be referred to as mica tape MT.

The mica tape MT is then impregnated with liquid varnish (liquid thermosetting insulating resin), and the impregnated varnish is then semi-cured. The reason for putting the impregnated varnish into a semi-cured state, i.e., into the B-stage, which is the initial stage of the curing reaction, is to keep the impregnated varnish in a semi-cured state and retain it in the mica tape MT so that it does not leak out.

The mica is what is commonly called "mica". There are no particular limitations on the form of the mica. For the mica paper 31, aggregated mica is widely used. Depending on the application and the manufacturing method of the insulating material, flake mica may be used as the mica. The particle size of the mica that constitutes the aggregated mica or flake mica is also set depending on the application and the manufacturing method of the insulating material. Since such mica paper 31 is usually brittle, it is adhered to the substrate 33 used as the reinforcing substrate by an adhesive layer 32 as described above.

For the substrate 33, an inorganic substrate such as glass cloth or an organic substrate such as polyethylene terephthalate film, polyimide film, cellulose paper, aramid paper, or nonwoven fabric is used depending on the heat resistance and insulation properties. The substrate may also be in the form of, for example, a sheet or tape.

The mica tape MT (a laminate of mica paper 31 and substrate 33 bonded by adhesive layer 32) is immersed in liquid varnish, or liquid varnish is applied to the front and back surfaces of the mica tape MT to impregnate the varnish, and then the mica tape MT is brought into a semi-cured state. This causes the liquid varnish to penetrate into the voids in the substrate 33, and then the mica tape MT is brought into a semi-cured state. The impregnation also results in a thin layer of varnish being present on the front and back surfaces of the mica tape MT. In Figure 3, this semi-cured varnish is shown as varnish layers 35a and 35b.

The adhesive layer 32 that bonds the mica paper 31 and the substrate 33 contains a material (component) that can bond the mica paper 31 and the substrate 33. The mica paper 31 may be impregnated with varnish, and the thin varnish layer formed on the surface of the mica paper 31 may be used as the adhesive layer 32. When the varnish that has impregnated the mica paper 31 is brought to a semi-cured state, the varnish becomes sticky. The varnish layer is then used as an adhesive layer to bond the mica paper 31 and the substrate 33.

The prepreg mica tape 30 of this embodiment is characterized in that a laminate (mica tape MT) of mica paper 31 and substrate 33 is impregnated with liquid varnish to bring it to a semi-cured state, and a special resin layer 34 is provided on at least one of the front and back surfaces of the mica tape MT. The resin layer 34 is made of unreacted thermosetting raw resin that is in a solid state at room temperature, and is held in place by adhering to the semi-cured varnish layers 35a, 35b formed on the front and back surfaces of the mica tape MT.

In the example shown in FIG. 3, the resin layer 34 is attached to the varnish layer 35b formed on the back side of the mica tape MT. Of course, the resin layer 34 may be provided on the front side of the mica tape MT as in (a) prepreg mica tape 30a in FIG. 4, or the resin layer 34 may be provided on both the front and back sides of the mica tape MT as in (b) prepreg mica tape 30b. In the following, a representative example will be described in which the prepreg mica tape 30 is used.

Thermosetting resins such as epoxy resins, unsaturated polyester resins, and silicone resins are used as liquid varnishes that are impregnated into the mica tape MT and brought to a semi-cured state. Of these, the curing reaction of silicone resins is broadly divided into condensation reactions that produce low molecular weight compounds such as dehydration condensation, and hydrosilylation reactions (addition reactions). In particular, in the case of condensation reactions, if low molecular weight compounds remain in the insulating layer, air bubbles (voids) may be formed, which may cause insulation defects. In addition, if low molecular weight compounds escape from the insulating layer, there is a risk of significant shrinkage during curing. For this reason, when using silicone resins as varnishes, it is preferable to use addition-curing varnishes that cure by hydrosilylation reactions.

As the unreacted thermosetting raw resin that is in a solid state at room temperature, thermosetting resins such as epoxy resin, unsaturated polyester resin, and silicone resin are used. In the case of silicone resin, a material that has a hydroxyl group and hardens by a dehydration condensation reaction may be used. Since the dehydration condensation reaction of silicone resin usually proceeds at a high temperature of about 200°C, there is little concern that it will remain in the insulating layer and form air bubbles (voids). In addition, the melting point or softening point is preferably higher than room temperature and lower than the hardening temperature, and those with a melting point of about 50°C to 100°C can be preferably used. As for the shape of the raw resin, various shapes such as powder, fiber, and mesh can be used as long as they can be held by the mica tape MT.

For example, it may be dissolved in a solvent to create a solution, which is then applied to the surface of the mica tape described above, and the solvent is then volatilized off to form a thin solid varnish layer. As described above, the thin layer of varnish present on the front and back surfaces of the mica tape MT due to impregnation becomes sticky when semi-cured, so a thin layer of powdered varnish may be formed on this surface. Alternatively, a nonwoven fabric or sheet may be impregnated with the varnish solution, the solvent may be volatilized off, and a thin sheet carrying the solid varnish may be attached to the surface.

The liquid varnish that is impregnated into the mica tape MT is in a semi-cured state, which is the initial stage of the curing reaction. At room temperature, the semi-cured varnish has high viscosity and low fluidity, but when heated to a higher temperature, its viscosity decreases and its fluidity increases.

In contrast, unreacted thermosetting raw resin that is in a solid state at room temperature remains unreacted, and when heated to a high temperature it undergoes a phase transition from solid to liquid, increasing its fluidity. Also, because liquids generally have a lower specific gravity than solids, their volume increases, making them more likely to flow and flow out of the mica tape MT and easier to fill gaps. This resin layer 34, made of unreacted thermosetting raw resin that is in a solid state at room temperature, melts (transitions phase) when heated, becomes liquid, and then hardens.

In addition, the unreacted thermosetting raw resin that is in a solid state at room temperature preferably contains a filler. As the filler, inorganic particles used in insulating materials such as silica, alumina, and boron nitride are preferable. By adjusting the type, shape, particle size, and content of this filler, it is possible to adjust the viscosity of the solid-state thermosetting resin after it melts (phase transitions) upon heating and becomes liquid. In addition, by including an insulating filler in the raw resin, it is possible to improve the insulating properties of the resin after it has hardened.

By adjusting the type, shape, particle size, and content of this filler, it is possible to lower the viscosity of the unreacted thermosetting raw resin when it becomes liquid upon heating, even though the raw resin is in a solid state at room temperature. In other words, it is possible to increase the fluidity of the resin when it becomes liquid.

On the other hand, in order to give the prepreg mica tape 30 the flexibility required for winding the prepreg mica tape 30 around the insulating coated conductor 21, the degree of hardening of the impregnated varnish (hereinafter sometimes referred to as impregnating varnish) is adjusted. Note that the viscosity (fluidity) of the impregnating varnish when heated and the viscosity (fluidity) of the resin layer 34 after it has become liquid vary depending on the degree of hardening of the impregnating varnish and the type, shape, particle size and content of the filler contained in the resin layer 34.

<Rotating Electric Machine>
Next, a rotating electric machine using the prepreg mica tape 30 of the present embodiment described above will be described. Fig. 5 is a perspective view showing a schematic configuration of the stator winding 10 of Fig. 1, and is an enlarged view of the portion indicated by the symbol R in Fig. 1. The stator winding 10 has three insulations: interphase insulation a, ground insulation b, and insulation c between winding turns. As shown in Fig. 1, a plurality of core slots 13 are formed in the stator core 11. The core slots 13 are grooves formed at regular intervals on the inner periphery of the columnar stator core 11 formed of laminated ring-shaped steel plates, and extend in the axial direction (lamination direction).

Figure 6 is a cross-sectional view of the stator winding 10 cut along plane H shown in Figure 5. However, this shows an intermediate stage before the impregnating varnish and resin layer 34 are thermally cured. On the other hand, Figure 7 shows the final state of the stator winding 10 after the thermal curing process, and is an enlarged view of the coil unit 12 at the bottom of the slot in Figure 6.

As shown in FIG. 6, two coil units 12, a slot liner 42, and three in-slot insulation materials 43 are arranged in the core slot 13. The core slot 13 is an open slot type with the inner circumferential side of the slot open, and a wedge 41 is fixed to the slot opening. The two coil units 12 are arranged side by side in the radial direction of the stator core 11. The three in-slot insulation materials 43 are installed so as to sandwich each coil unit 12 from above and below (in the radial direction of the stator core 11) as shown in the figure. The slot liner 42 is bent into a U-shape and provided in the core slot 13 so as to be arranged between the side wall of the core slot 13 and the two coil units 12, and between the bottom surface of the core slot 13 and the in-slot insulation materials 43.

In this way, the two coil units 12 sandwiched between the three in-slot insulating materials 43 are placed in the space surrounded by the slot liner 42 and the wedge 41 in the core slot 13. The wedge 41 is a member that fixes the coil unit 12, the in-slot insulating materials 43, and the slot liner 42 in the core slot 13. That is, the three in-slot insulating materials 43 and the two coil units 12 are inserted into the core slot 13 in which the slot liner 42 is provided from the slot opening on the inner periphery of the stator core 11, and finally the wedge-shaped wedge 41 is fixed to the slot opening. The wedge 41 is made of a laminated composite material of glass cloth and resin.

The slot liner 42 reinforces the insulation between the conductor 21 provided in the coil unit 12 and the stator core 11, and also protects the mica insulation layer 22 of the coil unit 12. The slot liner 42 is made of an organic base material such as polyethylene terephthalate film, polyimide film, cellulose paper, aramid paper, or nonwoven fabric.

The slot insulation material 43 reinforces the insulation between the conductors 21 in the coil unit 12, between the conductors 21 and the stator core 11, and between the conductors 21 and the wedges 41. The slot insulation material 43 is made of a laminated composite material of glass cloth and resin.

<Manufacturing method of rotating electric machine>
Next, a method for manufacturing the stator winding 10 using the prepreg mica tape 30 of this embodiment will be described.

First, in STEP 1A, the above-mentioned prepreg mica tape 30 is wound around an insulatingly coated conductor 21 to form a mica insulating layer 22, thereby producing a coil unit 12.

In STEP 2A, the coil units 12, slot liners 42, and in-slot insulation material 43 are inserted into the core slots 13, and wedges 41 are placed in the slot openings. This forms the stator winding 10 in an intermediate stage before the thermal hardening process is performed, as shown in FIG. 6. In this intermediate stage stator winding 10, as shown in FIG. 6, gaps 44 are generated around the two coil units 12. Gaps are also likely to occur between the slot liners 42 and the inner walls (side walls and bottom surface) of the core slots 13.

In STEP 3A, the stator winding 10 in the intermediate stage is heated based on the flow and hardening process of the impregnating varnish and the resin layer (unreacted thermosetting raw resin that was in a solid state at room temperature) 34. By heating, the viscosity of the impregnating varnish in the mica insulating layer 22 decreases, and the resin layer 34 melts and becomes liquid. The fluid impregnating varnish and resin layer 34 seep out from the mica insulating layer 22.

As shown in FIG. 7, the fluid impregnating varnish and resin layer 34 seeping out from the mica insulating layer 22 fills the gap 44 around the coil unit 12 and then hardens. Hereinafter, the impregnating varnish and resin layer 34 that seeps into the gap 44 will be referred to as exuded resin 45. Note that if the impregnating varnish or resin layer 34 contains fillers, the exuded resin 45 will also contain those fillers.

Through the above STEP 1A to STEP 3A, the stator winding 10 is formed in the final stage, with the impregnating varnish and resin layer 34 hardened. Although not shown in FIG. 7, the exuded resin 45 (impregnating varnish and resin layer 34) seeping out from the mica insulating layer 22 seeps out not only into the gap 44 but also to the outside of the slot liner 42, filling the gap between the slot liner 42 and the inner wall of the core slot 13.

In this manner, in the stator winding 10 of this embodiment, the prepreg mica tape 30 is used to form the intermediate stage stator winding 10, and then the impregnated varnish and resin layer 34 of the prepreg mica tape 30 are heated based on a flow and hardening process to form the final stage stator winding 10. As a result, the impregnated varnish and resin layer 34, which have become fluid due to heating, seep out from the surface of the mica insulating layer 22, and the gaps 44 around the coil unit 12 are filled with the seeped out resin 45 (see FIG. 7). As a result, the voids in the gaps 44 become smaller or disappear completely, making it possible to suppress the occurrence of discharge when a voltage is applied.

The thermosetting resin used for the resin layer 34 is an unreacted raw resin in a solid state at room temperature. When the unreacted raw resin in a solid state melts and becomes liquid upon heating, its volume increases compared to when it is in a solid state. Therefore, the effect of filling the gaps 44 is higher than when a semi-cured varnish becomes fluid and fills the gaps 44. Therefore, it is preferable that the unreacted raw resin in a solid state at room temperature used for the resin layer 34 is a material with a larger difference between the specific gravity in the solid state and the specific gravity in the liquid state. For example, it is known that there are silicone resins with hydroxyl groups that are in a solid state at room temperature and have a large difference between the specific gravity in the solid state and the specific gravity in the liquid state, and are preferable as materials to be used for the resin layer 34.

In order to completely suppress discharge caused by the gap when a voltage is applied, it is preferable to completely fill the gap 44 with the resin material created by the flow of the varnish or resin layer 34. However, even if the gap 44 is not completely filled, the flowed resin material can be used to reduce the void of the gap 44, thereby suppressing discharge when a voltage is applied.

In addition, in conventional rotating electric machines, in addition to the conventional prepreg method described above, methods such as the one-piece injection method (full impregnation method) and the single injection method are used. When manufacturing a stator winding using the one-piece injection method, a single coil with dry mica tape wound around a conductor is assembled into the core slot 13 to form the stator winding. The stator winding is then immersed in varnish to vacuum impregnate the varnish (vacuum pressure injection), and the varnish is then thermally cured.

In the single injection method, a single coil, which is made of an insulating conductor wrapped in dry mica tape, is first immersed in varnish, and the varnish is vacuum-impregnated (vacuum pressure-injected) into the single coil. Next, the single coil is heated to thermally harden the varnish, and then the coil is assembled into the core slot 13 to produce the stator winding.

In these conventional methods, in order to suppress the occurrence of discharge in the gaps in the core slots 13, a corona prevention layer d and an electric field relaxation layer e may be installed on the stator winding 10 (see Figure 5). In particular, in high-voltage, high-capacity generators such as large power generators, a corona prevention layer d and an electric field relaxation layer e are installed on the stator winding 10.

On the other hand, in the stator winding 10 of this embodiment, the gaps 44 in the iron core slots 13 are filled with exudation resin 45 as described above, so that the effect of suppressing discharge generation in the gaps 44 can be improved compared to the conventional prepreg method described above. In addition, in the integrated injection method and the single injection method, for example, varnish is injected into the fine gaps in the dry mica tape to prevent voids from remaining, but vacuum impregnation (vacuum pressure injection) must be carried out over a long period of time. However, in this embodiment, it is not necessary to vacuum impregnate the fine gaps in the dry mica tape with varnish over a long period of time.

Figures 8 and 9 are schematic diagrams showing the overlapping state of the prepreg mica tape 30 (mica insulating layer 22) wound around the conductor 21, showing the mica insulating layer 22 cross-sectioned along the conductor 21. Figure 8 shows the case of a single wrap, where the prepreg mica tape 30 is wound so that it overlaps in parts. Figure 9 shows the case of a double wrap, where an additional wrap is added on top of the single wrap of Figure 8. Note that in Figures 8 and 9, the varnish layers 35a and 35b (see Figures 3 and 4) on the prepreg mica tape 30 are omitted.

As shown in FIG. 8, the prepreg mica tape 30 is wound around the conductor 21 with some overlapping like a bandage (spiral band). Therefore, in the initial stage of the flow and hardening process when the stator winding 10 is heated in STEP 3A described above, when the impregnated varnish and resin layer (unreacted thermosetting raw resin in a solid state at room temperature) 34 of the prepreg mica tape 30 become in a flowable state, they exude from the surface and end faces of the wound prepreg mica tape 30 (mica insulating layer 22). The exuded resin 45 that exudes onto the surface of the prepreg mica tape 30 (mica insulating layer 22) wound around the conductor 21 fills the gaps 44 as described above. Also, the exuded resin 45 that exudes into the gaps 46 in the overlapping portions of the prepreg mica tape 30 fills the gaps 46.

In this way, in the initial stage of the flow and hardening process when heated, the exuded resin 45 seeps out from the surface and end faces of the prepreg mica tape 30, fills the gaps 46 on the surface of the mica insulating layer 22 and in the overlapping portions of the prepreg mica tape 30, and hardens further, forming hardened resin in the gaps 46. By forming hardened resin in this way in the gaps 46, the voids in the gaps 46 become smaller, making it possible to suppress the occurrence of discharge when a voltage is applied.

In particular, as shown in FIG. 9, when the prepreg mica tapes 30 are laminated in multiple layers, the insulation in the lamination direction of the prepreg mica tapes 30 is high, but the gaps 46 formed between the laminated prepreg mica tapes 30 can become insulation defects. However, when the prepreg mica tape 30 of this embodiment is used, the impregnating varnish and resin layer 34 contained in the prepreg mica tape 30 become fluid and seep out, and the exuded exuded resin 45 fills the gaps 46. As a result, the partial discharge resistance characteristics of the interface between the prepreg mica tapes 30 can be improved.

Figure 10 is a schematic diagram showing the temperature profile of the flow and hardening process (STEP 3A) of the impregnating varnish and resin layer 34 caused by heating the stator winding 10.

As the temperature rises (T>T1), the viscosity of the semi-cured impregnating varnish decreases, and the thermosetting resin (unreacted thermosetting raw resin that is solid at room temperature) that constitutes the resin layer 34 melts (transitions phase) and becomes liquid. At T=T2, as the temperature rises, it melts (transitions phase) and becomes liquid, and the impregnating varnish and the thermosetting resin that constitutes the resin layer 34 gel. As the temperature rises further (T>T2), the thermosetting resin that constitutes the impregnating varnish and the resin layer 34 begins to harden, and finally the hardening of the entire impregnating varnish and the thermosetting resin that constitutes the resin layer 34 is completed.

In this way, in the initial stage of heating when the viscosity of the impregnating varnish is reduced and the thermosetting resin constituting the resin layer 34 becomes liquid, the fluidized impregnating varnish and the thermosetting resin constituting the resin layer 34 seep out into the gaps 46 on the surface of the mica insulating layer 22 and between the prepreg mica tapes 30, and flow inside the iron core slots 13. In particular, when the stator winding 10 is heated, the stator winding 10 is rotated about its axis, which makes it easier for the seeped impregnating varnish and resin layer 34 to flow inside the iron core slots 13.

As a result, the seeping impregnated varnish and resin layer 34 fill the gaps 44 and 46 that existed before heating. This makes it possible to suppress discharges in the gaps 44 and 46 when a voltage is applied.

The fluidity of the impregnating varnish and the unreacted thermosetting raw resin that is in a solid state at room temperature, that is, the viscosity when heated due to differences in the degree of hardening, differs depending on the size and shape of the coil unit 12 and the iron core slot 13, and is therefore adjusted as appropriate. Also, the amount of the impregnating varnish and the unreacted thermosetting raw resin that is in a solid state at room temperature and the degree of semi-hardening are adjusted according to the size and shape of the coil unit 12 and the iron core slot 13. Furthermore, the temperature profile of the flow and hardening process of the varnish and the unreacted thermosetting raw resin that is in a solid state at room temperature due to heating of the stator winding 10 is adjusted.

The viscosity (fluidity) of the impregnating varnish when heated and the viscosity (fluidity) of the resin layer 34 (the thermosetting raw resin that was in a solid state at room temperature) after it has become liquid may be the same or different. For example, the viscosity of the resin layer 34 after it has become liquid is made lower than the viscosity of the impregnating varnish when heated. This makes the fluidity of the thermosetting raw resin that was in a solid state at room temperature after it has become liquid when heated higher than the fluidity of the impregnating varnish, making it easier to flow the thermosetting resin that was in a solid state at room temperature from the prepreg mica tape.

As described above, the prepreg mica tapes 30, 30a, and 30b of this embodiment include the mica tape MT, which is a laminate of the base material 33 and the mica paper 31, the varnish impregnated into the mica tape MT and brought to a semi-cured state, and the unreacted thermosetting raw resin (resin layer 34) that is in a solid state at room temperature and is provided on at least one of the front and back surfaces of the laminate impregnated with the varnish. The unreacted thermosetting raw resin that is in a solid state at room temperature is a thermosetting resin that melts when heated and becomes liquid, and then hardens.

The prepreg mica tapes 30, 30a, and 30b have an adhesive layer 32 between the substrate 33 and the mica paper 31. This adhesive layer 32 may be a semi-cured varnish or another resin material.

The rotating electric machine 1 also includes a stator core 11 in which core slots 13 are formed, a coil unit 12 arranged in the core slot 13 and having a conductor 21 on which a mica insulating layer 22 is formed, a slot liner 42 arranged in the core slot 13 to protect the coil unit 12, and an in-slot insulating material 43 arranged in the core slot 13 to insulate the coil unit 12. At least a portion of the gap 44 of the core slot 13 in which the coil unit 12, the slot liner 42, and the in-slot insulating material 43 are arranged is filled with a cured resin (exuded resin 45) produced by thermally curing an unreacted thermosetting raw resin (resin layer 34) that is solid at room temperature.

The mica insulating layer 22 may also be composed of prepreg mica tapes 30, 30a, and 30b wound around the conductor 21.

The resin layer (unreacted thermosetting raw resin that is in a solid state at room temperature) 34 provided on the prepreg mica tapes 30, 30a, and 30b becomes fluid when heated, seeping out from the mica insulating layer 22 and filling the gaps 44. As a result, the exuded resin 45 fills at least a portion of the gaps 44, reducing the voids in the gaps 44 and suppressing discharge during voltage application.

In addition, since the varnish-impregnated mica tape MT has semi-cured varnish layers 35a and 35b formed on the front and back surfaces, the mica tape MT alone may become sticky and reduce workability. However, in the prepreg mica tapes 30, 30a and 30b of this embodiment, a solid resin layer 34 is provided on at least one of the front and back surfaces of the mica tape MT. This improves workability compared to conventional prepreg mica tapes that do not have a resin layer 34. In particular, the configuration in which the resin layer 34 is provided on both the front and back surfaces improves workability and increases the amount of exuded resin 45, thereby further improving the discharge suppression effect.

(Variation 1)
The prepreg mica tapes 30, 30a, and 30b of the present embodiment described above can also be used in a conventional prepreg manufacturing method. For example, when the prepreg mica tape 30 is applied to a conventional prepreg manufacturing method for the stator winding 10, the stator winding 10 is manufactured in the following procedure.

In STEP 1B, similar to STEP 1A described above, the prepreg mica tape 30 of this embodiment is wound around the conductor 21 to form the mica insulating layer 22, thereby producing the intermediate stage coil unit 12.

In STEP 2B, the coil unit 12 in the intermediate stage is heated and pressurized to flow and harden the impregnating varnish and resin layer (unreacted thermosetting raw resin in a solid state at room temperature) 34 contained in the prepreg mica tape 30, producing the final coil unit 12. As a result, the impregnating varnish and resin layer 34 become fluid, and the exuded resin 45 that seeps out from the surface and end face of the prepreg mica tape 30 fills the gaps 46 between the prepreg mica tapes 30 in the mica insulating layer 22. Note that, although the coil unit 12 is pressurized here as in the conventional process, when the prepreg mica tape 30 of this embodiment is used, the varnish may be hardened without pressurizing the coil unit 12, thereby shortening the manufacturing time. Of course, pressure may be applied, which improves impregnation and filling properties.

In STEP 3B, the coil unit 12 in this final stage is inserted into the core slot 13 together with the slot liner 42 and the in-slot insulation material 43, and the coil unit 12, slot liner 42, and in-slot insulation material 43 are fixed to the core slot 13 with wedges to manufacture the stator winding 10.

In this way, when the prepreg mica tape 30 is applied to a conventional prepreg method for manufacturing a stator winding 10, in STEP 2B in which the coil unit 12 is manufactured in the final stage, a thermosetting resin layer formed by hardening the exuded resin 45 can be formed in the gaps 46 between the prepreg mica tapes 30. This can improve the partial discharge resistance characteristics of the interface between the prepreg mica tapes 30.

(Variation 2)
In the above-described embodiment, the prepreg mica tape 30 is impregnated with varnish and is provided with a resin layer 34 made of unreacted thermosetting raw resin that is solid at room temperature. On the other hand, in the second modification, unreacted thermosetting raw resin that is solid at room temperature is held in at least one of the coil unit 12, the slot liner 42, the in-slot insulation material 43, and the wedge 41. When unreacted thermosetting raw resin that is solid at room temperature is held in the coil unit 12, the prepreg mica tape 30 is used for the mica insulating layer 22 as in the above-described embodiment.

In the case of semi-closed or closed core slots, the wedge 41 is omitted. In that case, at least one of the coil unit 12, the slot liner 42, and the in-slot insulation material 43 is made to hold unreacted thermosetting raw resin that is in a solid state at room temperature.

When the raw resin is to be held in the slot liner 42, the in-slot insulating material 43, and the wedge 41, a layer of semi-cured varnish may be formed on the surfaces of the slot liner 42, the in-slot insulating material 43, and the wedge 41, and the above-mentioned raw resin may be adhered and held on the varnish layer. In addition, for the slot liner 42, the in-slot insulating material 43, and the wedge 41, which do not hold unreacted thermosetting raw resin in a solid state at room temperature, only a layer of semi-cured varnish may be formed on the surface. When a layer of semi-cured varnish is formed on the surfaces of the slot liner 42, the in-slot insulating material 43, and the wedge 41, the varnish is applied or impregnated and then semi-cured.

When the wedge 41 is to hold semi-cured varnish or unreacted thermosetting raw resin (resin layer 34) that is in a solid state at room temperature, it is preferable to hold it on the surface of the wedge 41 that faces the in-slot insulation material 43. By configuring it in this way, it is possible to prevent the formation of hardened resin on the surface of the wedge 41 that faces the rotor 9 due to heating and hardening.

After placing the coil unit 12, slot liner 42, in-slot insulating material 43, and wedge 41 in the iron core slot 13, the stator winding 10 is heated to flow and harden the resin layer 34, which is made of unreacted thermosetting raw resin in a solid state at room temperature. When the semi-hardened varnish is also held as described above, the semi-hardened varnish is also flowed and hardened by heating. The resin layer 34 and varnish in a fluid state flow inside the iron core slot 13 and fill the gaps (e.g., gap 44) in the iron core slot 13. Therefore, in the second modification in which at least one of the coil unit 12, slot liner 42, in-slot insulating material 43, and wedge 41 holds the unreacted thermosetting raw resin in a solid state at room temperature, the gap in the gap 44 is small as in the other embodiments described above, and discharge generation during voltage application can be suppressed.

The amount of semi-cured varnish and resin layer 34 (unreacted thermosetting raw resin in a solid state at room temperature) held by the slot liner 42, in-slot insulation material 43, and wedge 41, as well as the degree of semi-curing of the varnish, are adjusted according to the size and shape of the coil unit 12 and the core slot 13. The temperature profile of the flow and curing process is also adjusted.

In the above-described embodiment and modified example, the prepreg mica tapes 30, 30a, and 30b hold unreacted thermosetting raw resin in a solid state at room temperature, but the conductor 21 of the coil unit 12 may hold unreacted thermosetting raw resin in a solid state at room temperature. In this case, the raw resin may be applied before the insulating resin coating the conductor 21 hardens, or the raw resin may be applied by applying varnish to the surface of the conductor 21 coated with the insulating resin.

The effects of the above-described embodiment and modified examples can be summarized as follows:

(1) When heated, the unreacted thermosetting raw resin, which is in a solid state at room temperature, seeps out of the prepreg mica tape 30 and fills the gaps 44 formed in the iron core slots 13. This makes it possible to suppress the occurrence of discharge in the gaps 44.

(2) When heated, the unreacted thermosetting raw resin, which is in a solid state at room temperature, seeps out of the prepreg mica tape 30 and fills the gaps 46 between the prepreg mica tapes 30 in the mica insulating layer 22. This improves the partial discharge resistance characteristics of the interface between the prepreg mica tapes 30. In this way, discharge occurrence in the gaps 44, 46 can be suppressed, making it possible to provide a rotating electric machine with high insulation reliability.

(3) In the integrated injection method and the single injection method, varnish is injected into the fine gaps in the dry mica tape so that no voids remain in the mica insulating layer 22. Normally, the varnish is vacuum-impregnated (vacuum-pressurized injection) into the fine gaps in the dry mica tape over a long period of time. However, in this embodiment, it is not necessary to vacuum-impregnate (vacuum-pressurized injection) the varnish into the fine gaps in the dry mica tape over a long period of time.

(4) Unlike conventional prepreg methods, the coil unit 12 can be manufactured by hardening the varnish without applying pressure to the coil unit 12. This reduces manufacturing time.

(5) Unlike the one-piece injection method, there is no need to immerse the stator winding 10 in varnish, so excess varnish does not adhere to unnecessary areas. This allows the amount of varnish used to be reduced. There is also no risk of varnish adhering to the inner circumference of the stator winding 10, and it does not adversely affect the gap with the rotor 9. In addition, if varnish adheres to the outer circumference of the stator winding 10, it may affect the cooling efficiency of the stator winding 10, but in this embodiment, there is no risk of the resin layer 34 in a fluid state adhering to the outer circumference of the stator winding 10.

(6) By using the prepreg mica tape 30, manufacturing equipment and manufacturing processes for vacuum pressure injection of varnish are not required. In addition, the manufacturing equipment and manufacturing processes for manufacturing the rotating electric machine (stator winding 10) can be simplified, and the manufacturing time can be shortened.

Although the embodiments of the present invention have been described above, the above embodiments merely show some of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

1... rotating machine, 9... rotor, 10... stator winding, 11... stator core, 12... coil unit, 13... core slot, 21... conductor, 22... mica insulation layer, 30, 30a, 30b... prepreg mica tape, 31... mica paper, 32... adhesive layer, 33... substrate, 34... resin layer, 41... wedge, 42... slot liner, 43... slot insulation material, 44... gap, 45... exuded resin

Claims (8)

A laminate in which a base material and mica paper are laminated;
a varnish impregnated in the laminate and brought to a semi-cured state;
and an unreacted thermosetting raw material resin that is in a solid state at room temperature and is provided on at least one of the front and back surfaces of the laminate impregnated with the varnish,
In the prepreg mica tape, the raw material resin is an unreacted thermosetting resin that is in a solid state at room temperature, and is a thermosetting resin that melts and becomes liquid when heated and then hardens. 2. The prepreg mica tape according to claim 1,
A prepreg mica tape having an adhesive layer between the substrate and the mica paper. A coil unit having a conductor on which a mica insulating layer formed of the prepreg mica tape according to claim 1 is formed;
A slot liner for protecting the coil unit;
An in-slot insulating material that insulates the coil unit;
a stator core having core slots in which the coil units, the slot liners, and the in-slot insulating materials are arranged. a retaining step of retaining an unreacted thermosetting raw material resin in a solid state at room temperature in at least one of a coil unit, a slot liner protecting the coil unit, and an in-slot insulating material insulating the coil unit, the in-slot insulating material being disposed in an iron core slot of a rotating electric machine;
an arrangement step of arranging the coil unit, the slot liner, and the in-slot insulating material in the core slot;
a heating step of melting the raw material resin by heating to make it liquid and then curing it;
A method for manufacturing a rotating electric machine comprising the steps of: 5. The method for manufacturing a rotating electric machine according to claim 4,
In the holding step, the raw material resin is held by the coil unit by winding a prepreg mica tape around the conductor of the coil unit,
The prepreg mica tape is
A laminate in which a base material and mica paper are laminated;
a varnish impregnated in the laminate and brought to a semi-cured state;
The raw material resin is provided on at least one of the front and back surfaces of the laminate impregnated with the varnish, and is an unreacted thermosetting raw material resin in a solid state at room temperature.
A method for manufacturing a rotating electric machine. 6. The method for manufacturing a rotating electric machine according to claim 5,
The method for manufacturing a rotating electric machine includes the steps of: (a) heating the raw resin after the placement step; (b) melting the unreacted raw resin into a liquid state and then hardening the liquid; and (c) hardening the varnish after the semi-hardened state is rendered fluid. 6. The method for manufacturing a rotating electric machine according to claim 5,
In the heating step, the coil unit before the arrangement step is heated and pressurized, the unreacted raw resin is melted and liquidized, and then cured, and the varnish in a semi-cured state is made fluid and then cured.
In the arranging step, the coil unit is arranged after the heating step. 5. The method for manufacturing a rotating electric machine according to claim 4,
In the holding step, a semi-cured varnish is placed on the surfaces of the slot liner and the in-slot insulating material, and the raw resin is adhered to the varnish and held thereon;
In the heating step, the unreacted raw resin is melted into a liquid state and then hardened, and the varnish in a semi-hardened state is made into a fluid state and then hardened.

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