Prepreg mica tape, rotating electric machine, and method for manufacturing a rotating electric machine

Abstract

To provide a prepreg mica tape which can suppress generation of discharge during charging time.SOLUTION: A prepreg mica tape 30 includes a laminate (mica tape MT) in which a base material 33 and a mica paper 31 are laminated, a varnish which is impregnated into the mica tape MT and is made in a semi-cured state, and an unreacted thermosetting raw material resin (resin layer 34) which is provided on at least one surface of a surface and a rear face of the mica tape MT impregnated with the varnish and is in a solid state at normal temperature, wherein the unreacted thermosetting raw material resin which is in a solid state at normal temperature is molten by heating to be a liquid and then is cured.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a prepreg mica tape, a rotating electrical machine, and a method for manufacturing a rotating electrical machine.

Background Art

[0002] In order to insulate and fix the coils used in electrical equipment (generators, motors, transformers, etc.), thermosetting resins with high electrical insulation (insulation reliability) and excellent mechanical properties are widely used. For the insulation of high-voltage rotating electrical machines such as generators and motors, mica insulation systems with high insulation reliability are used. For example, a prepreg method is known as one of the manufacturing methods in a mica insulation system used for stator windings constituting a rotating electrical machine.

[0003] In the conventional prepreg method, a prepreg mica tape in which mica tape is impregnated in advance with varnish (liquid thermosetting insulating resin) and the varnish is in a semi-cured state is used. First, a prepreg mica tape is wound around an insulated conductor to manufacture a single coil, and this single coil is heated and pressurized to thermally cure the varnish. Next, the stator winding is manufactured by incorporating this single coil into the iron core slot 13. The prepreg method is suitable for large generators with high voltage and high capacity (for example, large power generators for power generation), and for example, Patent Document 1 describes a prepreg method technology suitable for large generators.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, if there is a gap between the stator coil and the stator slot, there is a risk of discharge occurring in this gap when energized. In the conventional prepreg method, a varnish layer is formed on the stator coil before it is installed in the stator slot, which makes it easy for a gap to occur between the stator coil and the stator slot. [Means for solving the problem]

[0006] A prepreg mica tape according to one aspect of the present invention comprises a laminate formed by laminating a substrate and mica paper; a varnish impregnated into the laminate and in a semi-cured state; and a resin layer provided on at least one of the front and back surfaces of the varnish-impregnated laminate, which is composed of an unreacted thermosetting raw material resin that is solid at room temperature, wherein the unreacted thermosetting raw material resin that is solid at room temperature is a thermosetting resin that melts into a liquid state upon heating and then hardens. [Effects of the Invention]

[0007] According to the present invention, the occurrence of discharge during energization can be suppressed. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic cross-sectional view showing an example of the configuration of a rotating electric machine. [Figure 2] Figure 2 is a schematic cross-sectional view showing an example of a single coil as shown in Figure 1. [Figure 3] Figure 3 shows the prepreg mica tape of this embodiment. [Figure 4] Figure 4 shows another example of prepreg mica tape. [Figure 5] Figure 5 is a perspective view showing a magnified portion of the stator windings in Figure 1. [Figure 6] Figure 6 is a cross-sectional view of the stator winding when it is cross-sectionally viewed along the plane H shown in Figure 5. [Figure 7] Figure 7 is an enlarged view showing the final state of the stator winding after the heat-curing treatment. [Figure 8]Figure 8 is a schematic diagram showing the overlapping state of prepreg mica tape in the case of a single winding. [Figure 9] Figure 9 is a schematic diagram showing the overlapping state of prepreg mica tape in the case of double winding. [Figure 10] Figure 10 is a schematic diagram of the temperature profile of the fluid curing process. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described with reference to Figures 1 to 10. Note that substantially identical or similar components are denoted by the same reference numerals, and descriptions may be omitted if they are redundant.

[0010] <Prepreg Mica Tape> Figure 1 is a schematic cross-sectional view showing an example of the configuration of a rotating electric machine 1. The rotating electric machine 1 comprises a stator winding 10 and a rotor 9. The stator winding 10 has a stator core 11 having a plurality of core slots 13, and individual coils 12 housed in the core slots 13. In the example shown in Figure 1, two individual coils 12 are arranged radially side by side in one core slot 13. Although not shown, the individual coils 12 are wound between core slots 13 and other core slots 13 in the stator winding 10.

[0011] A 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 construct 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 an external power source, and current is drawn from the stator winding 10. When the rotating electric machine is an electric motor, current is passed through the stator winding 10, rotating the rotor coil and supplying power to the outside.

[0012] FIG. 2 is a cross-sectional view schematically showing an example of the single coil 12 shown in FIG. 1. Note that (A) shows the overall configuration of the single coil 12, and (B) shows a partial enlargement of the single coil 12. As shown in FIG. 2(A), the single coil 12 described in this embodiment is formed by being joined (twisted) at both ends of the single coil 12. That is, one end (for example, the left side of the paper surface in FIG. 2) is joined (twisted) and formed, and exists outside the stator winding 10. Also, the other end (for example, the right side of the paper surface in FIG. 2) is formed by the single coil 12 being joined (twisted) and exists outside the stator winding 10.

[0013] Conductor 21 is exposed at either end of the single coil 12, and the conductor 21 is exposed outside the stator winding 10. The end where the conductor 21 is exposed is connected to an external power source or a storage battery.

[0014] Note that the straight long portion marked with reference numeral 12a in FIG. 2(A) of the single coil 12 is inserted into the core slot 13. That is, the single coil 12 shown in FIG. 2(A) shows the state of the stator winding 10 viewed from the radial direction.

[0015] Also, as shown in FIG. 2(B), the single coil 12 has a conductor 21 (for example, a metal wire, etc.) with a rectangular cross-section and a mica insulating layer 22 that covers the conductor 21. A prepreg mica tape 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 a prepreg mica tape around a plurality of bundled conductors 21. The conductor 21 is insulated and coated with a resin material or the like, and the conductors 21 are insulated from each other.

[0016] Next, the details of the structure of the prepreg mica tape will be described. FIG. 3 is a diagram showing the prepreg mica tape 30 in the present embodiment. The prepreg mica tape 30 includes a mica paper 31, an adhesive layer 32, a base material 33, and a resin layer 34. The mica paper 31 is adhered to the base material 33 by the adhesive layer 32. Since the mica paper 31 is usually brittle, it is adhered to the base material 33 used as a reinforcing base material. Hereinafter, the laminate of the mica paper and the base material 33 will be referred to as a mica tape MT.

[0017] Then, after impregnating the mica tape MT with varnish in a liquid state (liquid thermosetting insulating resin), the impregnated varnish is brought into a semi-cured state. Here, making the impregnated varnish into a semi-cured state, that is, the B-stage which is the initial stage of the curing reaction, is to keep the impregnated varnish in a semi-cured state so that it does not flow out and is held in the mica tape MT.

[0018] Note that mica is what is called so-called "muscovite". The form of mica is not particularly limited. Integrated mica is widely used as mica for the mica paper 31. Note that depending on the application and the manufacturing method of the insulating material, etc., flake mica may be used as mica. Also, the particle size of the mica constituting the integrated mica or flake mica is set according to the application and the manufacturing method of the insulating material, etc. Such mica paper 31 is usually brittle, and thus is adhered to the base material 33 used as a reinforcing base material as described above by the adhesive layer 32.

[0019] For the base material 33, depending on heat resistance and insulation properties, for example, an inorganic base material such as glass cloth, or an organic base material such as a polyethylene terephthalate film, a polyimide film, cellulose paper, aramid paper, non-woven fabric, etc. is used. Also, its shape is, for example, a sheet shape or a tape shape, etc.

[0020] The mica tape MT (a laminate of mica paper 31 bonded by an adhesive layer 32 and a substrate 33) is immersed in liquid varnish, or liquid varnish is applied to the front and back surfaces of the mica tape MT to impregnate it with varnish, and then it is allowed to reach a semi-cured state. As a result, the liquid varnish penetrates into the voids in the substrate 33, and then reaches a semi-cured state. In addition, a thin layer of varnish is present on the front and back surfaces of the mica tape MT due to the impregnation. In Figure 3, this semi-cured varnish is shown as varnish layers 35a and 35b.

[0021] The adhesive layer 32 that bonds the mica paper 31 to the substrate 33 contains a material (component) capable of bonding the mica paper 31 to the substrate 33. Alternatively, 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 impregnated into the mica paper 31 is allowed to partially harden, the varnish becomes tacky. This varnish layer is then used as the adhesive layer to bond the mica paper 31 to the substrate 33.

[0022] The prepreg mica tape 30 of this embodiment is characterized in that a liquid varnish is impregnated into a laminate of mica paper 31 and a substrate 33 (mica tape MT) 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 composed of unreacted thermosetting raw resin that is solid at room temperature and is held in place by adhering to the semi-cured varnish layers 35a and 35b formed on the front and back surfaces of the mica tape MT.

[0023] In the example shown in Figure 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 also be provided on the front side of the mica tape MT, as in (a) prepreg mica tape 30a in Figure 4, or on both the front and back sides of the mica tape MT, as in (b) prepreg mica tape 30b. In the following, we will explain using the case where prepreg mica tape 30 is used as a representative example.

[0024] Thermosetting resins such as epoxy resins, unsaturated polyester resins, and silicone resins are used as varnishes in a liquid state that are impregnated into mica tape MT and brought to a semi-cured state. Of these, the curing reaction of silicone resins can be broadly classified 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, bubbles (voids) may be formed, which may result in defects in insulation. Also, the removal of low molecular weight compounds from the insulating layer may increase shrinkage during curing. For this reason, when using silicone resin as a varnish, it is preferable to use an addition-curing type varnish that cures by a hydrosilylation reaction.

[0025] As the unreacted thermosetting raw material resin that is solid at room temperature, thermosetting resins such as epoxy resins, unsaturated polyester resins, and silicone resins can be used. In the case of silicone resins, materials that have hydroxyl groups and cure by a dehydration condensation reaction may also be used. Since the dehydration condensation reaction of silicone resins usually proceeds at a high temperature of about 200°C, there is little concern that it will remain in the insulating layer and form bubbles (voids). Furthermore, the melting point or softening point is preferably higher than room temperature and lower than the curing 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 material resin, various shapes can be used as long as they can be held in the mica tape MT, such as powder, fiber, or mesh.

[0026] For example, the varnish may be dissolved in a solvent to form a solution, applied to the surface of the mica tape as described above, and then the solvent may be evaporated to remove it, forming a thin solid varnish layer. Also, as described above, the varnish that is thinly present on the surface and back of the mica tape MT due to impregnation becomes adhesive when it reaches a semi-cured state, so a thin powdery varnish layer may be formed on this surface. Alternatively, a varnish solution may be impregnated into a nonwoven fabric or sheet-like material, and then the solvent may be evaporated to remove it, and a thin sheet bearing the solid varnish may be laminated to it.

[0027] The semi-cured liquid varnish used to impregnate the mica tape MT represents the initial stage of the curing reaction. At room temperature, the semi-cured varnish has high viscosity and low fluidity; however, when heated to a higher temperature, its viscosity decreases and its fluidity increases.

[0028] In contrast, the unreacted thermosetting raw material resin, which is solid at room temperature, is unreacted, and when heated, it undergoes a phase transition from solid to liquid, increasing its fluidity. Also, since liquids generally have a lower specific gravity than solids, its volume increases, making it easier to flow out of the mica tape MT and to fill gaps. The resin layer 34, which consists of this unreacted thermosetting raw material resin that is solid at room temperature, melts (undergoes a phase transition) when heated, becomes liquid, and then hardens.

[0029] Furthermore, it is preferable that the unreacted thermosetting raw material resin, which is solid at room temperature, contains a filler. Preferred fillers are inorganic particles used in insulating materials, such as silica, alumina, and boron nitride. By adjusting the type, shape, particle size, and content of this filler, the viscosity of the thermosetting resin in its solid state after it has melted (underwent a phase transition) upon heating and become liquid can be adjusted. Additionally, by incorporating insulating fillers into the raw material resin, the insulating properties of the cured resin can be improved.

[0030] By adjusting the type, shape, particle size, and content of this filler, the viscosity of the unreacted thermosetting raw resin, which was solid at room temperature, can be reduced when it becomes liquid upon heating. In other words, the fluidity of the resin when it becomes liquid can be increased.

[0031] On the other hand, in order to give the prepreg mica tape 30 the necessary flexibility when winding the prepreg mica tape 30 around the insulated conductor 21, the degree of hardening of the impregnated varnish (hereinafter sometimes referred to as impregnated varnish) is adjusted. Note that the viscosity (fluidity) of the impregnated varnish when heated and the viscosity (fluidity) of the resin layer 34 after it becomes liquid will differ depending on the degree of hardening of the impregnated varnish and the type, shape, particle size, and content of the filler contained in the resin layer 34.

[0032] <Rotating Electric Machinery> Next, a rotating electric machine using the prepreg mica tape 30 of this embodiment described above will be explained. Figure 5 is a schematic perspective view showing the configuration of the stator winding 10 in Figure 1, and is an enlarged view of the part indicated by the symbol R in Figure 1. The stator winding 10 has three types of insulation: phase-to-phase insulation a, ground insulation b, and winding turn-to-turn insulation c. As shown in Figure 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 circumference side of the columnar stator core 11, which is made up of stacked ring-shaped steel plates, and extend in the axial direction (stacking direction).

[0033] Figure 6 is a cross-sectional view of the stator winding 10 when it is cross-sectionally viewed along the plane H shown in Figure 5. However, it shows the intermediate stage before the impregnation varnish and resin layer 34 are heat-cured. On the other hand, Figure 7 shows the final state of the stator winding 10 after the heat-curing treatment, and is an enlarged view of the coil unit 12 on the slot bottom side of Figure 6.

[0034] As shown in Figure 6, the core slot 13 contains two individual coils 12, a slot liner 42, and three slot-insulating materials 43. The core slot 13 is an open slot type with an open inner circumference, and a wedge 41 is fixed to the slot opening. The two individual coils 12 are arranged side by side in the radial direction of the stator core 11. The three slot-insulating materials 43 are installed so as to sandwich each individual coil 12 from above and below (radially in the direction of the stator core 11). The slot liner 42 is bent into a U shape and provided inside the core slot 13 so as to be positioned between the side wall of the core slot 13 and the two individual coils 12, and between the bottom surface of the core slot 13 and the slot-insulating materials 43.

[0035] Thus, the two coil units 12, sandwiched between three slot-insulating materials 43, are positioned in the space enclosed by the slot liner 42 and wedge 41 within the iron core slot 13. The wedge 41 is a component that fixes the coil units 12, the slot-insulating materials 43, and the slot liner 42 within the iron core slot 13. That is, the three slot-insulating materials 43 and the two coil units 12 are inserted into the iron core slot 13 where the slot liner 42 is provided, from the slot opening on the inner circumference side of the stator iron core 11, and finally, the wedge-shaped wedge 41 is fixed to the slot opening. A laminated composite material of glass cloth and resin is used for the wedge 41.

[0036] The slot liner 42 reinforces the insulation between the conductor 21 provided on the coil unit 12 and the stator core 11, and also protects the mica insulating layer 22 of the coil unit 12. Organic substrates such as polyethylene terephthalate film, polyimide film, cellulose paper, aramid paper, and nonwoven fabric are used for the slot liner 42.

[0037] The slot-internal insulating material 43 reinforces the insulation between the conductors 21 provided in the coil unit 12, the insulation between the conductors 21 and the stator core 11, and the insulation between the conductors 21 and the wedge 41. A laminated composite material of glass cloth and resin is used for the slot-internal insulating material 43.

[0038] <Manufacturing method for rotating electric machines> Next, a method for manufacturing the stator winding 10 using the prepreg mica tape 30 of this embodiment will be described.

[0039] First, in STEP 1A, the prepreg mica tape 30 described above is wound around the insulated conductor 21 to form a mica insulating layer 22, thereby manufacturing a coil unit 12.

[0040] In STEP 2A, the coil unit 12, slot liner 42, and slot-internal insulating material 43 are inserted into the iron core slot 13, and a wedge 41 is placed in the slot opening. This forms the intermediate stage stator winding 10 before the heat curing treatment, as shown in Figure 6. In this intermediate stage stator winding 10, as shown in Figure 6, gaps 44 are created around the two coil units 12. Also, gaps tend to form between the slot liner 42 and the inner wall (side wall and bottom surface) of the iron core slot 13.

[0041] In STEP 3A, the intermediate stator winding 10 is heated based on the flow and curing process of the impregnation varnish and resin layer (unreacted thermosetting raw material resin that was solid at room temperature) 34. Upon heating, the viscosity of the impregnation varnish of the mica insulation layer 22 decreases, and the resin layer 34 melts and becomes liquid. This fluid impregnation varnish and resin layer 34 seep out from the mica insulation layer 22.

[0042] As shown in Figure 7, the fluid impregnating varnish and resin layer 34 that seeps out from the mica insulating layer 22 fills the gaps 44 around the coil unit 12, and then hardens. Hereafter, the impregnating varnish and resin layer 34 that seeps into the gaps 44 will be referred to as the seeping resin 45. If the impregnating varnish or resin layer 34 contains fillers, then the seeping resin 45 will also contain those fillers.

[0043] After completing STEP1A to STEP3A described above, the stator winding 10 is formed in its final stage, with the impregnating varnish and resin layer 34 having hardened. Although not shown in Figure 7, the seeping resin 45 (impregnating varnish and resin layer 34) from the mica insulating layer 22 seeps 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 iron core slot 13.

[0044] Thus, in the stator winding 10 of this embodiment, an intermediate stage of the stator winding 10 is formed using a prepreg mica tape 30, and then the impregnating varnish and resin layer 34 of the prepreg mica tape 30 is heated based on a flow-curing process to form the final stage of the stator winding 10. As a result, the impregnating 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 seeped-out resin 45 fills the gaps 44 around the coil unit 12 (see Figure 7). As a result, the voids in the gaps 44 are reduced or completely eliminated, and discharge generation during energization can be suppressed.

[0045] The thermosetting resin used in the resin layer 34 is an unreacted raw material resin that is solid at room temperature. When heated, the unreacted raw material resin in a solid state melts into a liquid, and its volume increases compared to the solid state. Therefore, the effect of filling the gaps 44 is greater compared to when a semi-cured varnish becomes fluid and fills the gaps 44. For this reason, it is preferable that the unreacted raw material resin used in the resin layer 34, which is solid at room temperature, has a large difference between its specific gravity in the solid state and its specific gravity in the liquid state. For example, silicone resins with hydroxyl groups are known to be solid at room temperature and have a large difference between their specific gravity in the solid state and its specific gravity in the liquid state, making them a preferred material for use in the resin layer 34.

[0046] Furthermore, in order to completely suppress discharge caused by gaps when the device is energized, it is preferable to completely fill the gaps 44 with resin material formed by the flow of the varnish or resin layer 34. However, even if the gaps 44 are not completely filled, discharge when the device is energized can be suppressed by reducing the size of the gaps 44 with the flowing resin material.

[0047] In addition to the conventional prepreg method mentioned above, conventional rotating electric machines employ methods such as the integrated injection method (total impregnation method) and the individual injection method. In the manufacture of stator windings using the integrated injection method, individual coils, each with dry mica tape wound around a conductor, are assembled into the iron core slot 13 to form the stator winding. The stator winding is then immersed in varnish, and the varnish is vacuum-impregnated (vacuum-pressurized injection) and heat-cured.

[0048] In the single-coil injection method, first, a coil consisting of an insulated conductor wrapped with dry mica tape is immersed in varnish, and the varnish is vacuum-impregnated (vacuum-pressurized injection) into this coil. Next, the coil is heated to heat-cur the varnish, and then assembled into the iron core slot 13 to manufacture the stator winding.

[0049] In these conventional methods, a corona prevention layer d or an electric field relaxation layer e may be installed on the stator winding 10 to suppress the occurrence of discharge in the gaps within the iron core slots 13 (see Figure 5). In particular, in high-voltage and high-capacity generators such as large power generators, a corona prevention layer d or an electric field relaxation layer e is installed on the stator winding 10.

[0050] On the other hand, in the stator winding 10 of this embodiment, as described above, the gaps 44 in the iron core slot 13 are filled with seeping resin 45, so the effect of suppressing discharge generation in the gaps 44 can be further improved compared to the conventional prepreg method described above. Furthermore, in the integrated injection method and the individual injection method, for example, varnish is injected into the fine voids of the dry mica tape to prevent void retention, but this requires vacuum impregnation (vacuum pressurized injection) over a long period of time. However, in this embodiment, it is not necessary to vacuum impregnate the fine voids of the dry mica tape with varnish over a long period of time.

[0051] 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, and show the mica insulating layer 22 when cross-sectioned along the conductor 21. Figure 8 shows the case of a single winding, where the prepreg mica tape 30 is wound so that it partially overlaps. Figure 9 shows the case of a double winding, where one more layer is wound on top of the single winding in Figure 8. Note that the varnish layers 35a and 35b (see Figures 3 and 4) on the prepreg mica tape 30 are not shown in Figures 8 and 9.

[0052] As shown in Figure 8, the prepreg mica tape 30 is wound around the conductor 21 with some overlap, like wrapping a bandage (spiral band). Therefore, in the initial stage of the flow and curing process when the stator winding 10 is heated in STEP 3A described above, when the impregnating varnish and resin layer (unreacted thermosetting raw resin that is solid at room temperature) 34 of the prepreg mica tape 30 become fluid, they seep out from the surface and edges of the wound prepreg mica tape 30 (mica insulating layer 22). The seeping resin 45 that seeps out 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. In addition, the seeping resin 45 that seeps into the gaps 46 in the overlapping parts of the prepreg mica tape 30 fills the gaps 46.

[0053] In this way, during the initial stages of the flow and curing process when heated, the seeping resin 45 from the surface and edges of the prepreg mica tape 30 fills the gaps 46 in the overlapping portions of the mica insulating layer 22 and the prepreg mica tape 30, and as it further hardens, hardened resin is formed in the gaps 46. As hardened resin is formed in the gaps 46 in this way, the voids in the gaps 46 are reduced, and discharge generation when power is applied can be suppressed.

[0054] In particular, as shown in Figure 9, when multiple layers of prepreg mica tape 30 are laminated, the insulation properties of the prepreg mica tape 30 in the lamination direction are high, but the gaps 46 formed between the laminated prepreg mica tapes 30 can become an insulation defect. However, when using the prepreg mica tape 30 of this embodiment, the impregnating varnish and resin layer 34 contained in the prepreg mica tape 30 become fluid and seep out, and the seeped-out resin 45 fills the gaps 46. As a result, the partial discharge resistance characteristics of the interface between the prepreg mica tape 30 and the prepreg mica tape 30 can be improved.

[0055] Figure 10 schematically shows the temperature profile of the flow and curing process (STEP 3A) of the impregnating varnish and resin layer 34 due to heating of the stator winding 10.

[0056] As the temperature rises (T>T1), the viscosity of the semi-cured impregnating varnish decreases, and the thermosetting resin constituting the resin layer 34 (unreacted thermosetting raw material resin that is solid at room temperature) melts (phase transition) and becomes a liquid. At T=T2, as the temperature rises, it melts (phase transition) and becomes a liquid, and the thermosetting resin constituting the impregnating varnish and resin layer 34 gels. As the temperature rises further (T>T2), the thermosetting resin constituting the impregnating varnish and resin layer 34 begins to harden, and finally the hardening of the entire impregnating varnish and thermosetting resin constituting the resin layer 34 is completed.

[0057] Thus, in the initial stages of heating, when the viscosity of the impregnating varnish decreases and the thermosetting resin constituting the resin layer 34 becomes liquid, the fluid impregnating varnish and the thermosetting resin constituting the resin layer 34 seep into the gap 46 between the surface of the mica insulating layer 22 and the prepreg mica tape 30, and flow inside the iron core slot 13. In particular, when the stator winding 10 is heated, rotating the stator winding 10 around its axis makes it even easier for the seeped impregnating varnish and resin layer 34 to flow inside the iron core slot 13.

[0058] As a result, the seeped-out impregnating varnish and resin layer 34 fill the gaps 44 and 46 that existed before heating. This suppresses the occurrence of discharge in the gaps 44 and 46 when an electric current is applied.

[0059] Furthermore, the fluidity of the impregnating varnish and the unreacted thermosetting raw material resin, which is solid at room temperature, i.e., the viscosity during heating due to differences in the degree of curing, will vary depending on the size and shape of the coil unit 12 and the iron core slot 13, and will be adjusted accordingly. In addition, the amount of impregnating varnish and the unreacted thermosetting raw material resin, which is solid at room temperature, and the degree of semi-curing will be adjusted according to the size and shape of the coil unit 12 and the iron core slot 13. Moreover, the temperature profile of the flow and curing process of the varnish and the unreacted thermosetting raw material resin, which is solid at room temperature, due to heating of the stator winding 10 will be adjusted.

[0060] Furthermore, the viscosity (fluidity) of the impregnating varnish during heating and the viscosity (fluidity) of the resin layer 34 (a thermosetting raw resin that was solid 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 may be lower than the viscosity of the impregnating varnish during heating. This makes it possible to increase the fluidity of the thermosetting raw resin that was solid at room temperature after it has become liquid during heating compared to the fluidity of the impregnating varnish, thereby making it easier for the thermosetting resin that was solid at room temperature to flow from the prepreg mica tape.

[0061] As described above, the prepreg mica tapes 30, 30a, and 30b of this embodiment comprise a mica tape MT which is a laminate formed by laminating a base material 33 and mica paper 31, a varnish impregnated into the mica tape MT and in a semi-cured state, and an unreacted thermosetting raw material resin (resin layer 34) provided on at least one of the front and back surfaces of the varnish-impregnated laminate, which is solid at room temperature. The unreacted thermosetting raw material resin, which is solid at room temperature, is a thermosetting resin that melts into a liquid state upon heating and then hardens.

[0062] The prepreg mica tapes 30, 30a, and 30b have an adhesive layer 32 between the base material 33 and the mica paper 31. This adhesive layer 32 may be a semi-cured varnish or another resin material.

[0063] Furthermore, the rotating electric machine 1 comprises a stator core 11 in which core slots 13 are formed, a coil unit 12 having a conductor 21 on which a mica insulating layer 22 is formed and arranged in the core slots 13, a slot liner 42 arranged in the core slots 13 to protect the coil unit 12, and an in-slot insulating material 43 arranged in the core slots 13 to insulate the coil unit 12. At least a portion of the gap 44 of the core slots 13 in which the coil unit 12, slot liner 42, and in-slot insulating material 43 are arranged is filled with a cured resin (exudate resin 45) produced by the heat curing of an unreacted thermosetting raw material resin (resin layer 34) that is solid at room temperature.

[0064] The mica insulating layer 22 may also be composed of prepreg mica tapes 30, 30a, and 30b wound around the conductor 21.

[0065] The resin layer (unreacted thermosetting raw resin, solid 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 seeping resin 45 fills at least a portion of the gaps 44, reducing the voids in the gaps 44 and suppressing discharge when power is applied.

[0066] Furthermore, since semi-cured varnish layers 35a and 35b are formed on the front and back surfaces of the varnish-impregnated mica tape MT, stickiness may occur when using the mica tape MT alone, potentially reducing 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. Therefore, compared to conventional prepreg mica tapes that do not have a resin layer 34, workability can be improved. In particular, the configuration in which a resin layer 34 is provided on both the front and back surfaces further improves workability and increases the amount of exuded resin 45, thereby further improving the discharge suppression effect.

[0067] (Variation 1) The prepreg mica tapes 30, 30a, and 30b of this embodiment described above can also be used in conventional prepreg manufacturing methods. For example, when applying the prepreg mica tape 30 to a conventional prepreg manufacturing method for stator windings 10, the stator windings 10 are manufactured in the following procedure.

[0068] In STEP 1B, similar to the case of STEP 1A described above, the prepreg mica tape 30 of this embodiment is wound around the conductor 21 to form a mica insulating layer 22, thereby manufacturing an intermediate coil unit 12.

[0069] In STEP 2B, the intermediate coil unit 12 is heated and pressurized to fluidize and cure the impregnating varnish and resin layer (unreacted thermosetting raw material resin that is solid at room temperature) 34 contained in the prepreg mica tape 30, thereby 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 edges of the prepreg mica tape 30 fills the gaps 46 between the prepreg mica tapes 30 in the mica insulating layer 22. Here, the coil unit 12 is pressurized as in the conventional process, but when using the prepreg mica tape 30 of this embodiment, the varnish may be cured without pressurizing the coil unit 12, thereby shortening the manufacturing time. Of course, pressurization may also be used, which improves impregnation and filling properties.

[0070] In STEP 3B, the final coil unit 12 is inserted into the iron core slot 13 together with the slot liner 42 and the slot insulation material 43. The coil unit 12, slot liner 42, and slot insulation material 43 are then fixed to the iron core slot 13 with wedges to manufacture the stator winding 10.

[0071] Thus, when the prepreg mica tape 30 is applied to the conventional prepreg method for manufacturing the stator winding 10, in STEP 2B, which manufactures the final coil unit 12, a thermosetting resin layer formed by cured seepage resin 45 can be formed in the gaps 46 between the prepreg mica tapes 30. This improves the partial discharge resistance characteristics of the interface between the prepreg mica tapes 30.

[0072] (Modification 2) In the above-described embodiment, the prepreg mica tape 30 is impregnated with varnish and provided with a resin layer 34 made of unreacted thermosetting raw material resin that is solid at room temperature. On the other hand, in the modified example 2, at least one of the coil unit 12, slot liner 42, slot insulating material 43, and wedge 41 is provided with unreacted thermosetting raw material resin that is solid at room temperature. When the coil unit 12 is provided with unreacted thermosetting raw material resin that is solid at room temperature, the prepreg mica tape 30 is used for the mica insulating layer 22, as in the above-described embodiment.

[0073] In the case of a semi-closed slot or closed slot type iron core slot, the wedge 41 is omitted. In that case, at least one of the coil unit 12, slot liner 42, and slot insulating material 43 is made to hold the unreacted thermosetting raw material resin in a solid state at room temperature.

[0074] When the slot liner 42, the slot-internal insulating material 43, and the wedge 41 are to hold the raw material resin, a layer of semi-cured varnish may be formed on the surfaces of the slot liner 42, the slot-internal insulating material 43, and the wedge 41, and the raw material resin may be attached to and held on the varnish layer. In addition, for the slot liner 42, the slot-internal insulating material 43, and the wedge 41 that do not hold unreacted thermosetting raw material resin that is solid at room temperature, only a layer of semi-cured varnish may be formed on the surface. When forming a layer of semi-cured varnish on the surfaces of the slot liner 42, the slot-internal insulating material 43, and the wedge 41, the varnish is applied or impregnated and then brought to a semi-cured state.

[0075] When the wedge 41 is to hold a semi-cured varnish and an unreacted thermosetting raw material resin (resin layer 34) that is solid at room temperature, it is preferable to hold them on the surface of the wedge 41 that faces the insulating material 43 inside the slot. With such a configuration, it is possible to prevent the formation of cured resin on the surface of the wedge 41 that faces the rotor 9 due to heating and curing.

[0076] After installing the coil unit 12, slot liner 42, slot insulation material 43, and wedge 41 in the iron core slot 13, the stator winding 10 is heated to cause the resin layer 34, which is composed of unreacted thermosetting raw material resin that is solid at room temperature, to flow and harden. If a semi-hardened varnish is also to be retained as described above, the semi-hardened varnish is also caused to flow and harden by heating. The flowing resin layer 34 and varnish flow inside the iron core slot 13, filling the gaps (for example, gaps 44) inside the iron core slot 13. Therefore, in the modified example 2, in which at least one of the coil unit 12, slot liner 42, slot insulation material 43, and wedge 41 retains an unreacted thermosetting raw material resin that is solid at room temperature, the void in the gap 44 becomes smaller, similar to the other cases described above, and discharge generation during energization can be suppressed.

[0077] Furthermore, the amount of semi-cured varnish and resin layer 34 (unreacted thermosetting raw resin that is solid at room temperature) held in the slot liner 42, the slot insulating material 43, and the 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 iron core slot 13. In addition, the temperature profile of the flow and curing process is adjusted.

[0078] In the embodiments and modifications described above, the prepreg mica tapes 30, 30a, and 30b hold the unreacted thermosetting raw material resin, which is solid at room temperature. However, the conductor 21 of the coil unit 12 may also hold the unreacted thermosetting raw material resin, which is solid at room temperature. In that case, the raw material resin may be attached before the insulating resin covering the conductor 21 hardens, or varnish may be applied to the surface of the conductor 21 covered with insulating resin before the raw material resin is attached.

[0079] The effects of the above-described embodiments and modified examples can be summarized as follows.

[0080] (1) Unreacted thermosetting raw material resin, which is solid at room temperature, seeps out from the prepreg mica tape 30 when heated, filling the gap 44 formed in the iron core slot 13. This suppresses the generation of discharge in the gap 44.

[0081] (2) Unreacted thermosetting raw material resin, which is solid at room temperature, seeps out from the prepreg mica tape 30 when heated, filling 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. Since discharge generation in the gaps 44 and 46 can be suppressed in this way, a rotating electric machine with high insulation reliability can be provided.

[0082] (3) In the integrated injection method and the individual injection method, varnish is injected into the fine voids of 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 voids of 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 voids of the dry mica tape over a long period of time.

[0083] (4) Unlike the conventional prepreg method, the varnish can be cured without pressurizing the coil unit 12, thereby enabling the manufacture of the coil unit 12. This reduces the manufacturing time.

[0084] (5) Unlike the integral injection method, there is no need to immerse the stator windings 10 in varnish, so excess varnish does not adhere to unnecessary parts. This reduces the amount of varnish used. In addition, there is no risk of varnish adhering to the inner circumference of the stator windings 10, and it does not adversely affect the gap with the rotor 9. Furthermore, if varnish adheres to the outer circumference of the stator windings 10, it may affect the cooling efficiency of the stator windings 10, but in this embodiment, there is no risk of the fluid resin layer 34 adhering to the outer circumference of the stator windings 10.

[0085] (6) By using the prepreg mica tape 30, the manufacturing equipment and process for vacuum pressurized varnish injection become unnecessary. In addition, the manufacturing equipment and process for the production of the rotating electric machine (stator winding 10) can be simplified, and the manufacturing time can be shortened.

[0086] Although embodiments of the present invention have been described above, these embodiments only represent a part 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. [Explanation of Symbols]

[0087] 1...Rotating electric machine, 9...Rotor, 10...Stator winding, 11...Stator iron core, 12...Coil unit, 13...Iron core slot, 21...Conductor, 22...Mica insulating layer, 30,30a,30b...Prepreg mica tape, 31...Mica paper, 32...Adhesive layer, 33...Base material, 34...Resin layer, 41...Wedge, 42...Slot liner, 43...Insulating material inside slot, 44...Gap, 45...Leaking resin

Claims

1. A laminate formed by laminating a substrate and mica paper, The varnish impregnated into the laminate and in a semi-cured state, The laminate impregnated with the varnish comprises an unreacted thermosetting raw material resin that is solid at room temperature, provided on at least one of the front and back surfaces of the laminate, The prepreg mica tape is a thermosetting resin in which the unreacted, solid raw material resin at room temperature melts upon heating, becomes liquid, and then hardens.

2. In the prepreg mica tape according to claim 1, A prepreg mica tape having an adhesive layer between the substrate and the mica paper.

3. A coil unit having a conductor on which a mica insulating layer formed by the prepreg mica tape described in claim 1 is formed, A slot liner that protects the coil unit, The aforementioned coil unit is insulated by an insulating material inside the slot, A rotating electric machine comprising the coil unit, the slot liner, and a stator core having core slots in which the insulating material within the slots is arranged.

4. A holding step involves holding an unreacted thermosetting raw material resin, which is in a solid state at room temperature, in at least one of the following: a coil unit, a slot liner protecting the coil unit, and an in-slot insulating material insulating the coil unit, which are arranged in the iron core slot of a rotating electric machine. The arrangement step involves arranging the coil unit, the slot liner, and the slot-internal insulating material in the iron core slot, A heating step in which the raw material resin is melted into a liquid state by heating and then cured, A method for manufacturing a rotating electric machine, including the following:

5. In the method for manufacturing a rotating electric machine according to claim 4, In the holding step, the raw material resin is held in the coil by winding a prepreg mica tape around the conductor of the coil unit. The aforementioned prepreg mica tape is A laminate formed by laminating a substrate and mica paper, The varnish impregnated into the laminate and in a semi-cured state, The laminate impregnated with the varnish comprises an unreacted thermosetting raw material resin that is solid at room temperature, provided on at least one of the front and back surfaces of the laminate, A method for manufacturing a rotating electric machine.

6. In the method for manufacturing a rotating electric machine according to claim 5, A method for manufacturing a rotating electric machine, wherein the heating step is performed after the arrangement step, and the unreacted raw material resin is melted into a liquid state and then cured, and the semi-cured varnish is made into a fluid state and then cured.

7. In the method for manufacturing a rotating electric machine according to claim 5, In the heating step, the coil unit is heated and pressurized before the arrangement step is performed, the unreacted raw material resin is melted into a liquid state and then cured, and the semi-cured varnish is made into a fluid state and then cured. A method for manufacturing a rotating electric machine, wherein the arrangement step involves arranging the coil unit after the heating step has been performed.

8. In the method for manufacturing a rotating electric machine according to claim 4, In the holding step, a semi-cured varnish is placed on the surface of the slot liner and the insulating material inside the slot, and the raw material resin is attached to the varnish and held in place. A method for manufacturing a rotating electric machine, comprising the heating step of melting the unreacted raw material resin into a liquid state and then curing it, and curing the semi-cured varnish into a fluid state.

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