Stator coil manufacturing method

Abstract

To provide a manufacturing method of a stator coil capable of easily controlling thickness of an isolation film provided in a part of the stator coil.SOLUTION: A manufacturing method of a stator coil 100 has a film removal step (S4) of subjecting a part of a stator coil 100 to treatment of partly removing a first insulation film 3 so as to partly expose a conductor part 4, and a film forming step (S6) of forming a second insulation film 8 by electrodeposition coating in an exposure part 4a formed by exposing the conductor part 4 after the film removal step (S4).SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] BACKGROUND ART Conventionally, a method for manufacturing a stator coil including an insulating coating is known (see, for example, Patent Document 1).

[0003] 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 together 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, thereby serving as an insulating coating for the stator coil. The resin is hardened by applying heat in the curing process. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-97306 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the stator coil forming process described in Patent Document 1, heat is applied to the resin in 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 in the curing process, causing it to flow. In this case, it becomes difficult to control the thickness of the resin as an insulating coating. Therefore, there is a need for a stator coil manufacturing method that allows for easy control of the thickness of the insulating coating provided on a portion of the stator coil.

[0006] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide a method for manufacturing a stator coil that makes it possible to easily control the thickness of an insulating coating provided on a portion of the stator coil. [Means for solving the problem]

[0007] 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 an axial direction, the method comprising the steps of: By irradiating with a pulsed laser, a coating removal process for partially exposing the conductor portion by performing a process for partially removing the first insulating coating so as to form a plurality of through holes in the first insulating coating; After the coating removal process, the stator coil is bent into a U-shape. 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. The coating removal process is a process of forming a plurality of through holes so that the intervals between the through holes in the compressed portion of the stator coil, which is compressed by bending in the bending process, are larger than the intervals between the through holes in the tension portion of the stator coil, which is tensioned by bending in the bending process. .

[0008] In a stator coil manufacturing method according to one aspect of the present invention, as described above, the first insulating coating is partially removed from a portion of the stator coil to partially expose the conductor portion, and a second insulating coating is formed 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 on the conductive surface by electrodeposition coating. 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.

[0009] Furthermore, 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 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. [Effects of the Invention]

[0010] According to the present invention, the thickness of the insulating coating provided on a portion of the stator coil can be easily controlled. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a plan view showing a configuration of a rotating electric machine according to an embodiment; [Figure 2] FIG. 2 is a partially enlarged perspective view of FIG. [Figure 3] 1 is a schematic cross-sectional view showing the configuration of a stator coil according to an embodiment. [Figure 4] FIG. 4 is a flow diagram illustrating a method for manufacturing a stator coil according to one embodiment. [Figure 5]5 is a schematic cross-sectional view showing the removal of a first insulating coating by a laser in a method for manufacturing a stator coil according to one embodiment. FIG. [Figure 6] FIG. 4 illustrates a through hole formed in a first insulating coating according to one embodiment. [Figure 7] FIG. 6 is a partially enlarged view of FIG. 5. [Figure 8] 5 is a schematic diagram illustrating a state in which a second insulating coating is formed by electrodeposition coating in a method for manufacturing a stator coil according to one embodiment. FIG. [Figure 9] FIG. 2 is a schematic front view of a stator coil on which a second insulating coating is formed according to an embodiment. [Figure 10] 4 is a schematic cross-sectional view of a stator coil on which a second insulating coating is formed according to one embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] A method for manufacturing the stator coil 100 according to this embodiment will be described with reference to FIGS.

[0014] 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.

[0015] The stator coil 100 is a segment conductor (flat conductor wire). A plurality of stator coils 100 are arranged on a stator core 10 and combined together to form a coil assembly.

[0016] 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 includes a coil end portion 2a connecting the Z2-side end portions 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. That is, the coil end portions 2b of different stator coils 100 are connected to each other on the axial outer side (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 end portions 1b of the pair of slot-accommodated portions 1. In the following description, the term "coil end portion 2" refers to both the coil end portion 2a and the coil end portion 2b. For ease of understanding, the circumferential width W of the slot 13 is shown larger than it actually is in Fig. 3. Fig. 3 also shows the stator coil 100 before the coil end portions 2b are joined together.

[0017] Furthermore, a crank portion 2c is provided at the center of the coil end portion 2a in the circumferential direction (E direction). The coil end portion 2a is provided so that when the stator coil 100 is arranged on the stator core 10, a lane change occurs at the crank portion 2c. Specifically, when the stator coil 100 is arranged on the stator core 10, the coil end portion 2a includes a straight portion 2d that extends along the circumferential direction on one circumferential side (E1 side) of the crank portion 2c. When the stator coil 100 is arranged on the stator core 10, the coil end portion 2a also includes a straight portion 2e that extends along the circumferential direction on the other circumferential side (E2 side) of the crank portion 2c. When the stator coil 100 is arranged on the stator core 10, the straight portion 2d is positioned radially outward with respect to the straight portion 2e by the radial thickness of the stator coil 100.

[0018] (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 area where the first insulating coating 3 was removed.

[0019] (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 state), for example. 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.

[0020] (Straight / 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.

[0021] (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).

[0022] (Coating removal process) Next, in step S4, a coating removal step 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.

[0023] Specifically, as shown in FIG. 5, the coating removal process (S4) is a process in which a laser is irradiated onto a portion of the stator coil 100, thereby removing the first insulating coating 3 from the portion irradiated with the laser, thereby partially exposing the conductor portion 4.

[0024] This makes it easier to remove the first insulating coating 3 than when the first insulating coating 3 of the stator coil 100 is removed by cutting. Also, 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 the first insulating coating 3 is removed by etching using a liquid or by cutting.

[0025] Furthermore, compared to removing the first insulating coating 3 with an etching solution, the first insulating coating 3 can be easily removed locally. As a result, a pattern that makes the stator coil 100 more easily bendable can be easily formed in the first insulating coating 3.

[0026] In the coating removal process (S4), the stator coil 100 is moved relative to the laser source 30 while 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.

[0027] In addition, the coating removal process (S4) is a process of forming multiple through holes 3a in the first insulating coating 3 while leaving the first insulating coating 3 partially in a part of the stator coil 100 by irradiating the first insulating coating 3 with a pulsed laser.

[0028] As a result, a pulsed laser that irradiates intermittently has relatively greater energy than a laser that irradiates continuously, and therefore can more easily remove the first insulating coating 3 than when a laser that irradiates continuously is used. Furthermore, by using a pulsed laser, the laser can be irradiated intermittently, which makes it easy 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 the multiple through holes 3a in the subsequent coating formation step (S6), and therefore the anchor effect allows the second insulating coating 8 to be more closely attached to the conductor portion 4.

[0029] Specifically, in each region irradiated with the pulsed laser (the interphase adjacent portion 7 described later), the area of ​​the portion where the first insulating coating 3 is removed (the total area of ​​the through holes 3a) is larger than the area of ​​the portion where the first insulating coating 3 remains unremoved.

[0030] 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. Note that femtoseconds refers to 10 -15 The femtosecond laser is a laser that does not have a thermal effect on the irradiated material.

[0031] 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 step of removing the thermal oxide film can be omitted. Furthermore, since the first insulating coating 3 is evaporated or sublimated (ablated) by the femtosecond laser, the first insulating coating 3 does not remain as a foreign substance, so the degreasing step and water washing step for removing the foreign substance can be omitted.

[0032] 6, the coating removal step (S4) is a step of forming a plurality of through holes 3a arranged in a lattice (matrix) pattern in the first insulating coating 3. In the coating removal step (S4), circular through holes 3a having a diameter r are formed. Here, the diameter r is, for example, 5 to 500 μm.

[0033] The coating removal step (S4) is a step of partially exposing the conductor portion 4 by removing the first insulating coating 3 from a second surface 6 (see FIG. 2) of the stator coil 100, which extends so as to intersect with the first surface 5, without removing the first insulating coating 3 from a 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 flat conductor wire, is placed in the stator core 10. Specifically, the second surface 6 is a surface that extends so as to be perpendicular to the radial direction (R direction) when the stator coil 100 is placed in the stator core 10.

[0034] 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 arranged on the stator core 10.

[0035] This allows the second insulating coating 8 to be easily formed by electrodeposition coating on the portion of the coil end portion 2 where the conductor portion 4 is exposed in the coating removal step (S4).

[0036] That is, the coating removal step (S4) is a step of performing a process of 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 step (S4) is a step of removing the first insulating coating 3 from a portion of the second surface 6 of the coil end portion 2.

[0037] Specifically, the coating removal process (S4) is a process for removing the first insulating coating 3 provided in the interphase adjacent portions 7 (see FIG. 2 ) of the coil end portions 2 where the stator coils 100 of different phases are adjacent to each other 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 are to constitute the interphase adjacent portions 7 when the stator coil 100 is arranged in the stator core 10.

[0038] This allows the second insulating coating 8 to be easily formed by electrodeposition coating on the interphase adjacent portions 7 of the coil end portions 2 where the conductor portions 4 are exposed in the coating removal step (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.

[0039] 3, two inter-phase adjacent portions 7 are provided in the coil end portion 2a. In the coil end portion 2a, the inter-phase adjacent portions 7 are provided on one side (E1 side) and the other side (E2 side) of the crank portion 2c, sandwiching the crank portion 2c. That is, an inter-phase adjacent portion 7 is provided on each of the straight portion 2d and the straight portion 2e of the coil end portion 2a.

[0040] 5, the second surface 6 of the stator coil 100 includes an inner surface 6a facing radially inward when the stator coil 100 is disposed in the stator core 10, and an outer surface 6b facing 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. 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 2a. 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 2a, and the first insulating coating 3 may be removed from the outer surface 6b in the other of the two interphase adjacent portions 7 of the coil end portion 2a.

[0041] 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. 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. Alternatively, the surface of the coil end portion 2a from which the first insulating coating 3 is removed may be the opposite surface to the surface of the coil end portion 2b from which the first insulating coating 3 is removed.

[0042] 7, the coating removal step (S4) is a step of forming the 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 step (S5), is larger 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 step (S5). Note that the distances d1 and d2 are each approximately 5 to 500 μm.

[0043] This allows the spacing between the through holes 3 a in the compressed portions 70 and the spacing between the through holes 3 a 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 3 a 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 bending of the stator coil 100 than when the density of the first insulating coating 3 in the compressed portions 70 is relatively high, and the stator coil 100 can be easily bent.

[0044] Specifically, in the subsequent bending step (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 is generated in the interphase adjacent portion 7 in the straight portion 2d of the coil end portion 2a. A tensile portion 71 is generated in the interphase adjacent portion 7 in the straight portion 2e of the coil end portion 2a. Note that the configurations and locations of the compressed portion 70 and the tensile portion 71 are merely examples and may vary depending on the shapes of the stator core 10 and the stator coil 100. In some cases, a single interphase adjacent portion 7 may contain both compressed portions 70 and tensile portions 71.

[0045] The coating removal step (S4) is a step performed on the straight stator coil 100 (see FIG. 5) before the bending step (S5).

[0046] As a result, the coating removal step (S4) is performed on the straight stator coil 100 (see FIG. 5) before the bending step (S5), which makes it easier to control the movement of the device or jig (laser source 30 in this embodiment) for removing the first insulating coating 3 relative to the stator coil 100. Furthermore, since 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.

[0047] (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.

[0048] (Film formation process) Next, in step S6, a coating formation step is performed 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).

[0049] 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 t2 (see FIG. 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.

[0050] Furthermore, 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.

[0051] Specifically, as shown in Fig. 8, the coating formation step (S6) is a step in which the stator coil 100 is immersed in a liquid paint and electrodeposition-coated. By applying a voltage to the stator coil 100 immersed in the liquid paint by a DC rectifier 200, the liquid paint is deposited on the exposed portion 4a of the stator coil 100. As a result, a second insulating coating 8 (see Fig. 9) is formed on the exposed portion 4a of the stator coil 100. Note that, for simplification, through holes 3a are not shown in Fig. 8.

[0052] Specifically, as shown in Fig. 10, the second insulating coating 8 grows in each of the through holes 3a and bonds with each other to form a single, integrated second insulating coating 8. Alternatively, the second insulating coatings 8 of the through holes 3a may be formed separately from each other without bonding with each other. Furthermore, the surface 8a of the second insulating coating 8 is formed to be relatively smooth (flat) compared to the irregularities on the surface of the first insulating coating 3 caused by the through holes 3a. In other words, the irregularities on the surface of the first insulating coating 3 are hardly reflected on the surface 8a of the second insulating coating 8.

[0053] The coating formation step (S6) is a step 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.

[0054] This allows the insulation in the portion where the second insulating coating 8 is formed to be higher than the insulation in the portion where the first insulating coating 3 is formed. As a result, the insulation in the interphase adjacent portion 7 where the potential difference between adjacent stator coils 100 becomes large can be increased by the second insulating coating 8. This makes it possible to more reliably prevent partial discharge from occurring in the interphase adjacent portion 7.

[0055] Moreover, the coating formation step (S6) is a step of forming the second insulating coating 8 on the coil end portion 2 without forming the second insulating coating 8 on the slot-receiving portion 1. This prevents the second insulating coating 8, which has a relatively large thickness t2, from being provided on the slot-receiving portion 1, thereby increasing the space factor of the stator coil 100 in the slot 13. As a result, the stator core 10 can be made smaller.

[0056] The coating formation step (S6) is a step of forming the second insulating coating 8 on the exposed portion 4a of the second surface 6 (see FIG. 5) without forming the second insulating coating 8 on the first surface 5.

[0057] Here, when the stator coils 100 are arranged in the stator core 10, the second surfaces 6 of the different stator coils 100 are surfaces that are likely to come into contact with each other. Therefore, by forming the second insulating coating 8 on the second surfaces 6, it is possible to more reliably prevent partial discharges between the stator coils 100 that come into contact with each other when the stator coils 100 are arranged in the stator core 10. Furthermore, by not forming the second insulating coating 8 on the first surfaces 5 that extend along the radial direction when the stator coil 100 is arranged 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 FIG. 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 in the circumferential direction across the opening, thereby enabling the rotary electric machine 120 to be made more efficient.

[0058] Specifically, the coating formation step (S6) is a step of forming a second insulating coating 8 on the outer surface 6b of the second surface 6 (see FIG. 5).

[0059] The coating formation step (S10) is a step of forming a second insulating coating 8 having a lower dielectric constant than the first insulating coating 3 in the coating formation step (S6).

[0060] This allows the thickness t2 (see Figure 10) of the second insulating coating 8 to be made smaller while 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.

[0061] 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 is mixed into 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).

[0062] (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).

[0063] Here, the adhesion of the second insulating coating 8 formed by electrodeposition coating to the conductor portion 4 is relatively high, so it is possible to prevent the second insulating coating 8 from flowing due to heating in the baking step (S7).

[0064] (cooling process) Then, in step S8, a cooling step is carried out to cool the stator coil 100 heated in the baking step (S7).

[0065] [Variations] 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 above description of the embodiments, and further includes all modifications (variations) within the meaning and scope of the claims.

[0066] For example, in the above embodiment, an example was shown in which the first insulating coating 3 was removed using a pulsed laser, but the present invention is not limited to this. For example, the first insulating coating 3 may be removed using a continuous laser. Also, the first insulating coating 3 may be removed using a pulsed laser with a pulse width larger (or smaller) than that of a femtosecond laser. Also, the first insulating coating 3 may be removed by a method other than a laser (for example, cutting).

[0067] In the above embodiment, the thickness t2 of the second insulating coating 8 is greater than the thickness t1 of the first insulating coating 3, but the present invention is not limited to this. As long as 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.

[0068] In addition, in the above embodiment, an example has been described in which the second insulating coating 8 is 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.

[0069] In the above embodiment, the second insulating coating 8 is formed on the coil end portion 2, but the present invention is not limited to this. The second insulating coating 8 may be formed on the slot-receiving portion 1.

[0070] Furthermore, in the above embodiment, an example was shown in which the second insulating coating 8 is 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.

[0071] In the above embodiment, the coating removal step (S4) is performed before the bending step (S5), but the present invention is not limited to this. The coating removal step may be performed after the bending step.

[0072] In the above embodiment, 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 same material as the first insulating coating 3.

[0073] In the above embodiment, the first insulating coating 3 is removed so that the distance d1 between the through holes 3a in the compressed portion 70 is larger 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 be removed so that the distance between the through holes 3a is constant regardless of the position on the stator coil 100. [Explanation of symbols]

[0074] 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

1. 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. 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. 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.

4. 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 any one of claims 1 to 4, wherein the coating removal process is a process for partially removing the first insulating coating from the coil end portion of the stator coil, which includes a slot-accommodated portion that is accommodated in the slot and a coil end portion that connects the axial ends of the slot-accommodated portion that is accommodated in different slots.

6. 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.

7. A method for manufacturing a stator coil described in any one of claims 1 to 6, wherein the coating removal process is a process performed on the straight stator coil before the bending process.

8. 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 dielectric constant than the first insulating coating.

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