JP7790038B2 - Stator coil manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a stator coil.

Conventionally, methods for manufacturing stator coils that include insulating coatings have been known (see, for example, Patent Document 1).

In the stator coil forming process described in Patent Document 1, multiple U-shaped conductor segments are inserted into slots in a stator core, and the ends of the conductor segments are joined to form the stator coil. A high-viscosity resin is applied to a portion of the stator coil (conductor segments). Specifically, the resin is applied to the portions of the conductor segments that will come into contact with other conductor segments when the stator coil is formed. This improves the insulation between the conductor segments that come into contact with each other. The resin applied to the segment conductors is hardened in a subsequent curing process, and thus serves as an insulating coating for the stator coil. The resin is hardened by applying heat in the curing process.

Japanese Patent Application Laid-Open No. 2019-97306

However, in the stator coil forming process described in Patent Document 1, heat is applied to the resin during the curing process. Here, the resin is simply applied to the stator coil, so it has low adhesion to the stator coil. For this reason, it is thought that the viscosity of the resin may decrease due to the heat applied during the curing process, causing it to flow. In this case, it becomes difficult to control the thickness of the resin used as an insulating coating. Therefore, there is a need for a stator coil manufacturing method that makes it easy to control the thickness of the insulating coating applied to part of the stator coil.

This invention was made to solve the above-mentioned problems, and one object of this invention is to provide a method for manufacturing a stator coil that makes it possible to easily control the thickness of the insulating coating applied to a portion of the stator coil.

In order to achieve the above object, one aspect of the present invention provides a method for manufacturing a stator coil for a rotating electric machine, the stator coil being disposed in a stator core including a plurality of slots extending in the axial direction, the method comprising: a coating removal process in which a portion of the stator coil including a first insulating coating and a conductor portion covered by the first insulating coating is irradiated with a pulsed laser to partially remove the first insulating coating so as to form a plurality of through holes in the first insulating coating, thereby partially exposing the conductor portion; a bending process in which the stator coil is bent into a U-shape after the coating removal process; and a coating formation process in which a second insulating coating is formed by electrocoating on the exposed portion where the conductor portion is exposed so that the second insulating coating spans the plurality of through holes , the coating removal process being a process in which the spacing between the through holes in the compressed portion of the stator coil that is compressed by bending in the bending process is greater than the spacing between the through holes in the tension portion of the stator coil that is tensioned by bending in the bending process .

In one aspect of the present invention, a stator coil manufacturing method involves partially removing the first insulating coating from a portion of the stator coil, as described above, to partially expose the conductor portion, and then forming a second insulating coating on the exposed portion by electrodeposition coating. Here, the viscosity of the film after electrodeposition coating changes little with temperature, so it does not flow even when heated. This makes it possible to precisely control the thickness of the film formed by electrodeposition coating on the conductive surface. Therefore, the thickness of the second insulating coating formed on the exposed portion where the conductor portion is exposed can be easily controlled by electrodeposition coating. As a result, the thickness of the insulating coating provided on a portion of the stator coil can be easily controlled.

In addition, compared to when the second insulating coating is applied to the entire conductor portion, the second insulating coating is formed only on a portion of the conductor surface by electrodeposition coating, which improves the adhesion of the second insulating coating to the conductor portion. Furthermore, by forming the second insulating coating only on a portion of the stator coil, the amount of second insulating coating used can be reduced compared to when the second insulating coating is formed on the entire stator coil.

The present invention makes it easy to control the thickness of the insulating coating applied to a portion of the stator coil.

1 is a plan view showing a configuration of a rotating electric machine according to an embodiment; FIG. 2 is a partially enlarged perspective view of FIG. 1 . 1 is a schematic cross-sectional view showing the configuration of a stator coil according to an embodiment. FIG. 4 is a flow diagram illustrating a method for manufacturing a stator coil according to one embodiment. 5 is a schematic cross-sectional view showing a state in which a first insulating coating is removed by a laser in a method for manufacturing a stator coil according to one embodiment. FIG. FIG. 2 illustrates a through hole formed in a first insulating coating according to one embodiment. FIG. 6 is a partial enlarged view of FIG. 5 . 5A and 5B are schematic diagrams illustrating a state in which a second insulating coating is formed by electrodeposition coating in a method for manufacturing a stator coil according to an embodiment. FIG. 2 is a schematic front view of a stator coil on which a second insulating coating is formed according to an embodiment. 4 is a schematic cross-sectional view of a stator coil on which a second insulating coating is formed according to an embodiment; FIG.

Embodiments of the present invention will be described below with reference to the drawings.

A method for manufacturing the stator coil 100 according to this embodiment will be described with reference to Figures 1 to 10.

As shown in FIG. 1, the stator coil 100 is provided in a stator core 10. The stator core 10 includes an annular back yoke 11, a plurality of teeth 12 protruding from the back yoke 11 toward the R1 side, and a plurality of slots 13 formed between adjacent teeth 12 in the E direction. Each of the plurality of slots 13 is provided to extend in the axial direction of the stator core 10. The stator core 10 is combined with a rotor core 110 to form a rotating electric machine 120.

The stator coil 100 is a segment conductor (flat conductor wire). A coil assembly is formed by combining multiple stator coils 100 arranged on the stator core 10.

As shown in FIG. 3 , each of the multiple stator coils 100 includes a slot-accommodated portion 1 accommodated in a slot 13 of the stator core 10 and a coil end portion 2 connecting the slot-accommodated portions 1 accommodated in different slots 13. Specifically, each of the multiple stator coils 100 includes a pair of slot-accommodated portions 1 accommodated in different slots 13. The coil end portion 2 also includes a coil end portion 2a connecting the Z2-side ends 1a of the pair of slot-accommodated portions 1. The coil end portion 2 also includes a coil end portion 2b connecting the slot-accommodated portions 1 of different stator coils 100. In other words, the coil end portions 2b of different stator coils 100 are connected to each other on the axial outside (Z1 side) of the stator core 10. In each of the multiple stator coils 100, the coil end portion 2b is connected to the Z1-side ends 1b of the pair of slot-accommodated portions 1. In the following description, the term "coil end portion 2" refers to both coil end portion 2a and coil end portion 2b. For ease of understanding, the circumferential width W of the slot 13 is shown larger than it actually is in Figure 3. Also, Figure 3 shows the stator coil 100 before the coil end portions 2b are joined together.

A crank portion 2c is provided in the circumferential center (E direction) of the coil end portion 2a. The coil end portion 2a is provided so that when the stator coil 100 is arranged in the stator core 10, a lane change occurs at the crank portion 2c. Specifically, when the stator coil 100 is arranged in the stator core 10, the coil end portion 2a includes a straight portion 2d that extends circumferentially on one circumferential side (E1 side) of the crank portion 2c. When the stator coil 100 is arranged in the stator core 10, the coil end portion 2a also includes a straight portion 2e that extends circumferentially on the other circumferential side (E2 side) of the crank portion 2c. When the stator coil 100 is arranged in the stator core 10, the straight portion 2d is positioned radially outward relative to the straight portion 2e by the radial thickness of the stator coil 100.

(Method for manufacturing stator coil)
2 to 10, a method for manufacturing the stator coil 100 will be described. In this manufacturing process, the first insulating coating 3 is partially removed, and the second insulating coating 8 is formed in the portion where the first insulating coating 3 was removed.

(preparation process)
As shown in Fig. 4, first, in step S1, a copper wire (bare copper wire having a substantially rectangular cross section) to be used as the stator coil 100 is prepared. In the preparation step (S1), the copper wire is prepared in a state where it is wound around a bobbin (in a roll). At this stage, the stator coil 100 includes a first insulating coating 3 (see Fig. 3) and a conductor portion 4 (see Fig. 3) covered with the first insulating coating 3.

(straightening/cutting process)
Next, in step S2, a straightening and cutting process is performed to straighten and cut the copper wire. Specifically, in the straightening and cutting process (S2), the rolled copper wire is straightened. Then, the straightened copper wire is cut to the length of the stator coil 100.

(Rolling process)
Next, in step S3, a rolling process is performed on the stator coil 100. Specifically, the stator coil 100 is rolled by a rolling roll (not shown) so that the cross section of the stator coil 100 has a predetermined shape (a predetermined rectangular shape).

(Film removal process)
Next, in step S4, a coating removal process is performed in which the first insulating coating 3 is partially removed from a part of the stator coil 100, thereby partially exposing the conductor portion 4.

Specifically, as shown in Figure 5, the coating removal process (S4) involves irradiating a portion of the stator coil 100 with a laser to remove the first insulating coating 3 from the laser-irradiated portion, thereby partially exposing the conductor portion 4.

This makes it easier to remove the first insulating coating 3 of the stator coil 100 than when it is removed by cutting. Furthermore, by removing the first insulating coating 3 by laser irradiation, it is easier to form any desired pattern on the first insulating coating 3 than when it is removed by etching using a liquid or cutting.

Furthermore, compared to removing the first insulating coating 3 using an etching solution, the first insulating coating 3 can be easily removed locally. As a result, a pattern that makes it easier for the stator coil 100 to bend can be easily formed in the first insulating coating 3.

In the coating removal process (S4), the stator coil 100 is moved relative to the laser source 30, which is irradiating the laser, thereby changing the portion of the stator coil 100 that is irradiated with the laser, and the first insulating coating 3 is removed.

The coating removal process (S4) involves irradiating the first insulating coating 3 with a pulsed laser to form multiple through holes 3a in the first insulating coating 3 while leaving the first insulating coating 3 partially intact in a portion of the stator coil 100.

As a result, a pulsed laser that emits laser light intermittently has relatively greater energy than a laser that emits laser light continuously, making it easier to remove the first insulating coating 3 than when using a laser that emits laser light continuously. Furthermore, by using a pulsed laser, the laser can be emitted intermittently, making it easier to form through holes 3a in the first insulating coating 3. Furthermore, the second insulating coating 8, which will be described later, is formed via multiple through holes 3a in the subsequent coating formation step (S6), allowing the second insulating coating 8 to adhere more closely to the conductor portion 4 due to the anchor effect.

Specifically, in each region irradiated with the pulsed laser (the interphase adjacent portion 7 described below), the area of the portion from which the first insulating coating 3 is removed (the total area of the through holes 3a) is larger than the area of the portion from which the first insulating coating 3 remains unremoved.

The coating removal step (S4) is a step of forming a plurality of through holes 3a by irradiating the first insulating coating 3 with a pulsed laser having a pulse width on the order of femtoseconds, thereby partially evaporating or sublimating (ablation) the first insulating coating 3. That is, the pulsed laser includes a femtosecond laser, which is an ultrashort pulse laser. A femtosecond is ^10-15 seconds. The femtosecond laser is a laser that does not have a thermal effect on the irradiated material.

This prevents the conductor portion 4 of the stator coil 100 from being thermally affected, thereby preventing the formation of a thermal oxide film on the conductor portion 4. As a result, the process of removing the thermal oxide film can be omitted. Furthermore, because the first insulating coating 3 is evaporated or sublimated (ablated) by the femtosecond laser, the first insulating coating 3 does not remain as foreign matter, so the degreasing and water washing processes for removing foreign matter can be omitted.

As shown in FIG. 6, the coating removal process (S4) is a process for forming a plurality of through holes 3a arranged in a lattice (matrix) pattern in the first insulating coating 3. In the coating removal process (S4), circular through holes 3a with a diameter r are formed. The diameter r is, for example, 5 to 500 μm.

The coating removal process (S4) is a process for partially exposing the conductor portion 4 by removing the first insulating coating 3 from the second surface 6 (see FIG. 2) of the stator coil 100, which extends so as to intersect with the first surface 5 (see FIG. 2), without removing the first insulating coating 3 from the first surface 5 (see FIG. 2) of the stator coil 100, which extends along the radial direction (R direction) of the stator core 10 when the stator coil 100, which is a rectangular conductor wire, is placed on the stator core 10. Specifically, the second surface 6 is the surface that extends perpendicular to the radial direction (R direction) when the stator coil 100 is placed on the stator core 10.

The coating removal process (S4) is a process for partially removing the first insulating coating 3 from the coil end portion 2. Note that the coil end portion 2 in the manufacturing process of the stator coil 100 refers to the portion that will constitute the coil end portion 2 when the stator coil 100 is placed on the stator core 10.

This allows the second insulating coating 8 to be easily formed by electrodeposition coating on the coil end portion 2 where the conductor portion 4 is exposed in the coating removal process (S4).

In other words, the coating removal process (S4) is a process for partially removing the first insulating coating 3 from the coil end portion 2 without removing the first insulating coating 3 from the slot-accommodating portion 1. The coating removal process (S4) is a process for removing the first insulating coating 3 from a portion of the second surface 6 of the coil end portion 2.

Specifically, the coating removal process (S4) is a process for removing the first insulating coating 3 provided on the interphase adjacent portions 7 (see Figure 2) of the coil end portions 2 where stator coils 100 of different phases are adjacent when the stator coils 100 are arranged in the stator core 10. Note that the interphase adjacent portions 7 in the manufacturing process of the stator coil 100 refer to the portions that will constitute the interphase adjacent portions 7 when the stator coil 100 is arranged in the stator core 10.

This allows the second insulating coating 8 to be easily formed by electrocoating on the interphase adjacent portions 7 of the coil end portion 2, where the conductor portion 4 is exposed in the coating removal process (S4). As a result, the insulation properties of the interphase adjacent portions 7, where the potential difference between adjacent stator coils 100 is large, can be easily controlled by the second insulating coating 8.

More specifically, as shown in FIG. 3, two interphase adjacent portions 7 are provided in the coil end portion 2a. In the coil end portion 2a, the interphase adjacent portions 7 are provided on both sides (E1 side) and (E2 side) of the crank portion 2c, sandwiching the crank portion 2c. In other words, an interphase adjacent portion 7 is provided on each of the straight portions 2d and 2e of the coil end portion 2a.

As shown in FIG. 5 , the second surface 6 of the stator coil 100 includes an inner surface 6a that faces radially inward when the stator coil 100 is disposed in the stator core 10, and an outer surface 6b that faces radially outward. In this embodiment, the first insulating coating 3 is removed from the outer surface 6b in both of the two interphase adjacent portions 7 of the coil end portion 2a. It is also possible to remove the first insulating coating 3 from the inner surface 6a in both of the two interphase adjacent portions 7 of the coil end portion 2a. It is also possible to remove the first insulating coating 3 from the inner surface 6a in one of the two interphase adjacent portions 7 of the coil end portion 2a, and remove the first insulating coating 3 from the outer surface 6b in the other.

Furthermore, each of the two coil end portions 2b has one interphase adjacent portion 7. In this embodiment, the first insulating coating 3 is removed from the outer surface 6b in both of the two interphase adjacent portions 7 of the coil end portion 2b. Note that the first insulating coating 3 may also be removed from the inner surface 6a in both of the two interphase adjacent portions 7 of the coil end portion 2b. Alternatively, the first insulating coating 3 may be removed from the inner surface 6a in one of the two interphase adjacent portions 7 of the coil end portion 2b, and the first insulating coating 3 may be removed from the outer surface 6b in the other. Furthermore, the surface from which the first insulating coating 3 is removed in the coil end portion 2a may be the opposite surface from the surface from which the first insulating coating 3 is removed in the coil end portion 2b.

Also, as shown in Figure 7, the coating removal process (S4) is a process for forming a plurality of through holes 3a so that the distance d1 between the through holes 3a in the compressed portion 70 of the stator coil 100, which will be compressed by bending in the subsequent bending process (S5), is greater than the distance d2 between the through holes 3a in the tension portion 71 of the stator coil 100, which will be stretched by bending in the bending process (S5). Note that the distances d1 and d2 are each approximately 5 to 500 μm.

This allows the spacing between the through holes 3a in the compressed portions 70 and the spacing between the through holes 3a in the tensioned portions 71 to be uniform when the stator coil 100 is bent in the bending step (S5). As a result, the thickness t2 of the second insulating coating 8 formed in the subsequent coating formation step (S6) can be made uniform between the compressed portions 70 and the tensioned portions 71. Furthermore, by making the spacing d1 between the through holes 3a in the compressed portions 70 relatively large, the density of the first insulating coating 3 in the compressed portions 70 can be made relatively small when the stator coil 100 is bent. As a result, the first insulating coating 3 is less likely to interfere with the bending of the stator coil 100 than when the density of the first insulating coating 3 in the compressed portions 70 is relatively high, making it easier to bend the stator coil 100.

Specifically, in the subsequent bending process (S5), the stator coil 100 is bent into a U-shape and a crank portion 2c (see FIG. 2) is formed in the coil end portion 2a, resulting in compressive stress on the inner side of the bend in the stator coil 100 (coil end portion 2a) and tensile stress on the outer side of the bend in the stator coil 100 (coil end portion 2a). In the example shown in FIG. 7, a compressed portion 70 occurs in the interphase adjacent portion 7 at the straight portion 2d of the coil end portion 2a. A tensile portion 71 occurs in the interphase adjacent portion 7 at the straight portion 2e of the coil end portion 2a. Note that the configuration and location of the compressed portion 70 and tensile portion 71 are merely examples and may vary depending on the shape of the stator core 10 and stator coil 100. A single interphase adjacent portion 7 may contain both compressed and tensile portions 70 and 71.

The coating removal process (S4) is performed on the straight stator coil 100 (see Figure 5) before the bending process (S5).

As a result, the coating removal process (S4) is performed on the straight stator coil 100 (see Figure 5) before the bending process (S5), making it easier to control the relative movement of the device or jig (laser source 30 in this embodiment) used to remove the first insulating coating 3 relative to the stator coil 100. Furthermore, because the stator coil 100 can be bent with the through holes 3a formed in the first insulating coating 3, the stator coil 100 can be bent more easily than when the entire surface of the stator coil 100 is covered with the first insulating coating 3.

(Bending process)
Next, as shown in Fig. 4, in step S5, a bending process is performed in which the stator coil 100 is bent into a U-shape (see Fig. 3). In this bending process (S5), the stator coil 100 is bent into a U-shape and a crank portion 2c (see Fig. 2) is formed.

(Film formation process)
Next, in step S6, a coating formation step is carried out in which a second insulating coating 8 is formed on the exposed portion 4a of the conductor portion 4 by electrodeposition coating (see FIG. 8).

The film after electrodeposition coating exhibits little change in viscosity with temperature, so it does not flow even when heated. This makes it possible to precisely control the thickness of the film formed by electrodeposition coating on the conductive surface. Therefore, the thickness t2 (see Figure 10) of the second insulating coating 8 formed on the exposed portion 4a where the conductor portion 4 is exposed can be easily controlled by electrodeposition coating. As a result, the thickness of the insulating coating provided on a portion of the stator coil 100 can be easily controlled.

In addition, compared to when the second insulating coating 8 is applied to the entire conductor portion 4, the second insulating coating 8 is formed only on a portion of the conductor surface by electrodeposition coating, which improves the adhesion of the second insulating coating 8 to the conductor portion 4. Furthermore, by forming the second insulating coating 8 only on a portion of the stator coil 100, the amount of second insulating coating 8 used can be reduced compared to when the second insulating coating 8 is formed on the entire stator coil 100.

Specifically, as shown in Figure 8, the coating formation process (S6) is a process in which the stator coil 100 is immersed in liquid paint and electrodeposition-coated. A voltage is applied to the stator coil 100 immersed in the liquid paint by a DC rectifier 200, causing the liquid paint to be deposited on the exposed portion 4a of the stator coil 100. This forms a second insulating coating 8 (see Figure 9) on the exposed portion 4a of the stator coil 100. Note that for simplicity, the through-holes 3a are not shown in Figure 8.

Specifically, as shown in FIG. 10 , the second insulating coating 8 grows in each of the multiple through holes 3a, and the second insulating coatings 8 of the multiple through holes 3a bond together to form a single, integrated second insulating coating 8. The second insulating coatings 8 of the multiple through holes 3a may be formed separately from each other without bonding together. Furthermore, the surface 8a of the second insulating coating 8 is relatively smooth (flat) compared to the uneven surface of the first insulating coating 3 caused by the through holes 3a. In other words, the uneven surface of the first insulating coating 3 is hardly reflected on the surface 8a of the second insulating coating 8.

The coating formation process (S6) is a process of forming a second insulating coating 8, which has a thickness t2 greater than that of the first insulating coating 3, on the exposed portion 4a by electrodeposition coating. Specifically, the thickness t1 of the first insulating coating 3 is, for example, approximately 20 μm. The thickness t2 of the second insulating coating 8 is, for example, approximately 30 to 100 μm. In this embodiment, as an example, the thickness t2 of the second insulating coating 8 is approximately three times the thickness t1 of the first insulating coating 3. The thickness t2 of the second insulating coating 8 can be adjusted by the electrodeposition coating time, applied voltage, etc.

This allows the insulation in the area where the second insulating coating 8 is formed to be higher than the insulation in the area where the first insulating coating 3 is formed. As a result, the insulation in the interphase adjacent areas 7, where the potential difference between adjacent stator coils 100 is large, can be increased by the second insulating coating 8. This makes it possible to more reliably prevent partial discharges from occurring in the interphase adjacent areas 7.

The coating formation process (S6) is a process in which the second insulating coating 8 is formed on the coil end portion 2 without forming the second insulating coating 8 on the slot-receiving portion 1. As a result, the second insulating coating 8, which has a relatively large thickness t2, is not provided on the slot-receiving portion 1, making it possible to increase the space factor of the stator coil 100 in the slot 13. As a result, it is possible to reduce the size of the stator core 10.

The coating formation process (S6) is a process in which the second insulating coating 8 is formed on the exposed portion 4a of the second surface 6 (see Figure 5) without forming the second insulating coating 8 on the first surface 5.

Here, when the stator coils 100 are placed in the stator core 10, the second surfaces 6 of different stator coils 100 are prone to contact with each other. Therefore, by forming the second insulating coating 8 on the second surfaces 6, partial discharges can be more reliably prevented between the stator coils 100 that are in contact with each other when placed in the stator core 10. Furthermore, by not forming the second insulating coating 8 on the first surfaces 5 that extend radially when the stator coil 100 is placed in the stator core 10, it is possible to prevent deterioration in insertability of the stator coil 100 due to interference between the second insulating coating 8 and the circumferential side surfaces 13a of the slots 13 (see Figure 3) when inserting the stator coil 100 into the slots 13. As a result, the circumferential width W of the slots 13 can be further reduced. Furthermore, by preventing deterioration in insertability of the stator coil 100 into the slots 13, it is not necessary to insert the stator coil 100 into the slots 13 along the radial direction. This allows the radial opening of the slot 13 to be narrowed, making it easier for magnetic flux to flow circumferentially across the opening. As a result, the efficiency of the rotating electric machine 120 can be improved.

Specifically, the coating formation process (S6) is a process of forming a second insulating coating 8 on the outer surface 6b of the second surface 6 (see Figure 5).

The coating formation process (S10) is a process for forming a second insulating coating 8 having a lower dielectric constant than the first insulating coating 3.

This allows the thickness t2 (see Figure 10) of the second insulating coating 8 to be made smaller while still maintaining the insulating properties of the second insulating coating 8, compared to when the relative dielectric constant of the second insulating coating 8 is equal to or greater than the relative dielectric constant of the first insulating coating 3.

Specifically, the first insulating coating 3 is made of enamel resin, while the second insulating coating 8 is made of a resin in which a filler (filling material) is mixed with enamel resin. The dielectric constant of the first insulating coating 3 is approximately 3.1, while the dielectric constant of the second insulating coating 8 is approximately 2.2 to 3.0 (for example, 2.6).

(Baking process)
Next, as shown in FIG. 4 , in step S7, a baking process is performed in which the second insulating coating 8 that has been electrodeposited onto the stator coil 100 is baked. This hardens the second insulating coating 8, which is a thermosetting resin. The baking temperature in this process is, for example, 300° C. to 350° C. Alternatively, the baking temperature may be raised to a temperature generally used for annealing copper (for example, 350° C. to 500° C.).

Here, the second insulating coating 8 formed by electrodeposition coating has relatively high adhesion to the conductor portion 4, making it possible to prevent the second insulating coating 8 from flowing due to heating in the baking process (S7).

(cooling process)
Then, in step S8, a cooling step is carried out to cool the stator coil 100 heated in the baking step (S7).

[Modification]
It should be noted that the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims rather than the description of the above embodiments, and further includes all modifications (variations) within the meaning and scope equivalent to the claims.

For example, while the above embodiment illustrates an example in which the first insulating coating 3 is removed using a pulsed laser, the present invention is not limited to this. For example, the first insulating coating 3 may be removed using a continuous laser. The first insulating coating 3 may also be removed using a pulsed laser with a pulse width larger (or smaller) than that of a femtosecond laser. The first insulating coating 3 may also be removed using a method other than a laser (for example, cutting).

In addition, in the above embodiment, an example was shown in which the thickness t2 of the second insulating coating 8 was greater than the thickness t1 of the first insulating coating 3, but the present invention is not limited to this. If the second insulating coating 8 has higher insulating properties than the first insulating coating 3, the thickness t2 of the second insulating coating 8 may be equal to or less than the thickness t1 of the first insulating coating 3.

In addition, in the above embodiment, an example was shown in which the second insulating coating 8 was formed only on the second surface 6 of the stator coil 100, but the present invention is not limited to this. The second insulating coating 8 may be formed only on the first surface 5 of the stator coil 100. Furthermore, the second insulating coating 8 may be formed on both the first surface 5 and the second surface 6 of the stator coil 100.

In addition, in the above embodiment, an example was shown in which the second insulating coating 8 was formed on the coil end portion 2, but the present invention is not limited to this. The second insulating coating 8 may also be formed on the slot accommodating portion 1.

In addition, in the above embodiment, an example was shown in which the second insulating coating 8 was formed only on the interphase adjacent portions 7 of the coil end portion 2, but the present invention is not limited to this. The second insulating coating 8 may also be formed on portions of the coil end portion 2 other than the interphase adjacent portions 7. For example, the second insulating coating 8 may be formed over the entire coil end portion 2.

In addition, in the above embodiment, an example was shown in which the coating removal process (S4) was performed before the bending process (S5), but the present invention is not limited to this. The coating removal process may also be performed after the bending process.

In addition, in the above embodiment, an example was shown in which the second insulating coating 8 has a higher dielectric constant than the first insulating coating 3, but the present invention is not limited to this. The second insulating coating 8 may be made of the exact same material as the first insulating coating 3.

In addition, in the above embodiment, an example was shown in which the first insulating coating 3 was removed so that the distance d1 between the through holes 3a in the compressed portion 70 was greater than the distance d2 between the through holes 3a in the tensioned portion 71, but the present invention is not limited to this. The first insulating coating 3 may also be removed so that the distance between the through holes 3a remains constant regardless of the position on the stator coil 100.

1...slot accommodating portion, 1a, 1b...end portion, 2, 2a, 2b...coil end portion, 3...first insulating coating, 3a...through hole, 4...conductor portion, 4a...exposed portion, 5...first surface, 6...second surface, 7...interphase adjacent portion, 8...second insulating coating, 10...stator core, 13...slot, 70...compressed portion, 71...tensile portion, 100...stator coil, 102...rotating electric machine, d1...spacing (spacing between through holes in compressed portion), d2...spacing (spacing between through holes in tensile portion), t2...thickness (thickness of second insulating coating)

Claims (8)

A method for manufacturing a stator coil for a rotating electric machine, the stator coil being disposed in a stator core including a plurality of slots extending in an axial direction, comprising:
a coating removal process in which a pulse laser is applied to a portion of the stator coil including a first insulating coating and a conductor portion covered with the first insulating coating, thereby partially removing the first insulating coating so as to form a plurality of through holes in the first insulating coating, thereby partially exposing the conductor portion;
a bending step of bending the stator coil into a U-shape after the coating removal step;
and a coating formation step of forming a second insulating coating by electrodeposition coating on the exposed portion where the conductor portion is exposed so that the second insulating coating spans the plurality of through holes after the bending step ,
A method for manufacturing a stator coil, wherein the coating removal process is a process for forming the plurality of through holes so that the spacing between the through holes in the compressed portion of the stator coil that is compressed by bending in the bending process is larger than the spacing between the through holes in the tension portion of the stator coil that is stretched by bending in the bending process. 2. The method for manufacturing a stator coil according to claim 1, wherein the coating removal process is a process of forming the plurality of through holes by irradiating the first insulating coating with the pulse laser having a pulse width on the order of femtoseconds , thereby partially evaporating or sublimating the first insulating coating. 3. The method for manufacturing a stator coil according to claim 1, wherein the coating forming step is a step of forming the second insulating coating, which is thicker than the first insulating coating, on the exposed portion by electro-deposition coating. the coating removal step is a step of partially exposing the conductor portion by performing a process of removing the first insulating coating on a second surface of the stator coil, the second surface extending to intersect with the first surface, without removing the first insulating coating on a first surface of the stator coil, the first surface extending along the radial direction of the stator core, when the stator coil is a flat conductor wire and is disposed in the stator core;
4. The method for manufacturing a stator coil according to claim 3 , wherein the coating forming step is a step of forming the second insulating coating on the exposed portion of the second surface without forming the second insulating coating on the first surface. 5. The method for manufacturing a stator coil according to claim 1, wherein the coating removal process is a process for partially removing the first insulating coating from the coil end portions of the stator coil, the coil end portions including slot-accommodated portions accommodated in the slots and coil end portions connecting the axial ends of the slot-accommodated portions accommodated in different slots. 6. The method for manufacturing a stator coil according to claim 5, wherein the coating removal process is a process for removing the first insulating coating provided in an interphase adjacent portion of the coil end portion where the stator coils of different phases are adjacent to each other when the stator coil is arranged in the stator core . The method for manufacturing a stator coil according to any one of claims 1 to 6 , wherein the coating removal step is a step performed on the stator coil in a straight state before the bending step. The method for manufacturing a stator coil according to any one of claims 1 to 7 , wherein the coating formation step is a step of forming the second insulating coating having a lower relative dielectric constant than the first insulating coating.