Method for manufacturing stators for rotating electric machines

Abstract

To reduce a cavity in a liquid resin material of an impregnation object part which can be generated when a workpiece is immersed in a tank of the liquid resin material.SOLUTION: A stator manufacturing method for a rotary electric machine includes: a mounting step of mounting a plurality of coil pieces forming a stator coil on a stator core, and forming a workpiece; a joint step of joining tips of each of one coil piece and the other coil piece, on one end side in an axial direction of the workpiece, after the mounting step; an immersion step of immersing the workpiece in a tank of a liquid resin material so that an impregnation object part including a joint part between the tips is immersed, after the joint step; and a curing step of curing the liquid resin material, after the immersion step, wherein the immersion step includes immersing the impregnation object part to be the lower side of the liquid surface of the liquid resin material of the tank, in such a workpiece inclination attitude that an angle made by an axial direction of the stator core relative to the liquid surface of the liquid resin material of the tank is different from 90 degrees.SELECTED DRAWING: Figure 20

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a stator for a rotating electrical machine.

Background Art

[0002] A workpiece for a rotating electrical machine is prepared, in which a plurality of coil pieces forming a stator coil are attached to a stator core. At one end side in the axial direction of the workpiece, the tip portions of the plurality of coil pieces are joined together. After impregnating a liquid resin material into an impregnation target portion including the joint portion (conductor exposed portion), the liquid resin material is cured, thereby covering the joint portion with an insulating coating of the resin material. A method for manufacturing a stator for a rotating electrical machine is known. In this type of manufacturing method, with the workpiece in a posture where the joint portion is on the lower side, the workpiece is immersed in a tank of the liquid resin material (the impregnation target portion is impregnated with the liquid resin material). Then, in order to suppress voids in the insulating coating (resin mold) that may occur due to the boiling of the curing agent, a technique of heating and curing the liquid resin material in a positive pressure environment has been proposed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, it is difficult for the above-described conventional techniques to reduce voids (voids caused by air accumulating below the workpiece) that may occur when the workpiece is immersed in the tank of the liquid resin material. Such voids can cause voids in the insulating coating (resin mold) after curing.

[0005] Therefore, on one aspect, an object of the present disclosure is to reduce voids in the liquid resin material of the impregnation target portion that may occur when the workpiece is immersed in the tank of the liquid resin material.

Means for Solving the Problems

[0006] One aspect involves a mounting process in which multiple coil pieces forming the stator coil are attached to the stator core to form the workpiece, Following the mounting step, a joining step is performed in which the respective tip portions of one coil piece and the other coil piece are joined together at one axial end of the workpiece. Following the joining process, the workpiece is immersed in a tank of liquid resin material so that the part to be penetrated, including the joint between the tip portions, is submerged. The process includes, after the immersion step, a curing step in which the liquid resin material is cured. A method for manufacturing a stator for a rotating electric machine is provided, wherein the immersion step includes immersing the portion to be penetrated below the liquid surface of the liquid resin material in the tank, with the workpiece in an inclined position where the angle between the axial direction of the stator core and the liquid surface of the liquid resin material in the tank is different from 90 degrees. [Effects of the Invention]

[0007] In one aspect, the present disclosure makes it possible to reduce voids in the liquid resin material at the part of the workpiece to be impregnated that may occur when the workpiece is immersed in a tank of liquid resin material. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic flowchart illustrating an example of a manufacturing method for stators used in rotating electric machines. [Figure 2] This diagram schematically shows the entire workpiece used to form a stator for a rotating electric machine. [Figure 3] This is a cross-sectional view along the axial direction of the workpiece with the coil pieces assembled to the stator core. [Figure 4] This is a front view of one coil section. [Figure 5] This is a schematic cross-sectional view of a coil piece. [Figure 6] This is an explanatory diagram of the joint, corresponding to an enlarged view of section Q1 in Figure 2. [Figure 7]It is a diagram schematically showing a workpiece before being immersed in a tank of a liquid resin material in a side view. [Figure 8] It is a diagram schematically showing a workpiece in a state of being immersed in a tank of a liquid resin material in a side view. [Figure 9] It is a diagram schematically showing a state of a workpiece in a lifting process in a side view. [Figure 10] It is a diagram schematically showing a state of a workpiece receiving an outer diameter side resin curing treatment in an outer diameter side resin curing process in a side view. [Figure 11] It is a diagram schematically showing a workpiece in an upward posture in an up and down inversion process after the outer diameter side resin curing treatment in a side view. [Figure 12] It is an explanatory diagram of a preferable rotation axis when inverting a workpiece up and down. [Figure 12A] It is an explanatory diagram of a rotation axis according to a comparative example. [Figure 13] It is a diagram schematically showing a state of a workpiece receiving an upper surface resin curing treatment in an upper surface resin curing process in a side view. [Figure 14] It is a diagram schematically showing a state of a workpiece receiving an inner diameter side resin curing treatment in an inner diameter side resin curing process in a side view. [Figure 15] It is a diagram schematically showing a state of a workpiece in a downward posture immediately before receiving a second immersion process in a side view. [Figure 16] It is a diagram schematically showing a workpiece in an upward posture after completion of a second insulation coating process. [Figure 17] It is a diagram schematically showing a state of a workpiece in a heating process in a side view. [Figure 18] It is an explanatory diagram of the effect in a heating process. [Figure 19] It is a diagram schematically showing an example of a cooling structure. [Figure 20] It is an explanatory diagram of a preferable method related to an immersion process (step S208). [Figure 21] It is an explanatory diagram of the effect of the method shown in FIG. 20. [Figure 22] It is an explanatory diagram of the inconvenience that may occur in an immersion process according to a comparative example. [Figure 23]It is an explanatory diagram of another inclined posture. [Figure 24] It is an explanatory diagram of another inclined posture. [Figure 25] It is an explanatory diagram of a preferable method related to the dipping process (step S208) in the second insulation coating process. [Figure 26] It is an explanatory diagram of the disadvantages that may occur in the dipping process according to the comparative example. [Figure 27] It is an explanatory diagram of preferable examples of eight types of inclined postures.

Mode for Carrying Out the Invention

[0009] Hereinafter, each embodiment will be described in detail with reference to the accompanying drawings. Note that the dimensional ratios in the drawings are merely examples and are not limited thereto, and the shapes, etc. in the drawings may be exaggerated partially for the sake of explanation.

[0010] The method for manufacturing a stator for a rotating electric machine described below is applicable to any stator for a rotating electric machine as long as it has a joint portion of coil pieces in the coil end portion. Hereinafter, as a preferred application example, a method for manufacturing a stator for a rotating electric machine that can function as a power source for generating the driving force of a vehicle will be described.

[0011] Figure 1 is a schematic flowchart showing an example of a method for manufacturing a stator for a rotating electric machine. Note that Figure 1 is a schematic flowchart showing the general flow, and additional steps may be included at any stage. Figures 2 to 6 are explanatory diagrams of the workpiece W. Figure 2 is a schematic diagram showing the entire workpiece W, which includes a stator core 112 and stator coils 114 for forming a stator 10 for a rotating electric machine. Figure 3 is a cross-sectional view along the axial direction of the workpiece W with the coil pieces 52 assembled to the stator core 112. Figure 4 is a front view of one of the coil pieces 52 among a plurality of coil pieces 52. Figure 5 is a schematic cross-sectional view of the coil piece 52. Figure 6 is an explanatory diagram of the joint 400, which corresponds to an enlarged view of part Q1 in Figure 2. Figures 7 to 18 are explanatory diagrams of this manufacturing method, and Figures 7 to 11 and Figures 13 to 18 are schematic diagrams showing the state of the workpiece W at each step in a side view. Figure 12 is an explanatory diagram of a preferred rotation axis I1 when the workpiece W is inverted vertically. Figure 12 schematically shows a workpiece gripping section 1000 of the manufacturing apparatus. Figure 12A is an explanatory diagram of the rotating shaft I2 in a comparative example.

[0012] Figure 2 shows the Z direction. The Z direction corresponds to the vertical direction, with Z1 and Z2 corresponding to the upper and lower sides, respectively. Figure 3 shows the Y direction. The Y direction corresponds to the radial direction, with Y1 corresponding to the radially outer side and Y2 corresponding to the radially inner side (the side closer to the central axis I of the stator core 112).

[0013] In the following explanation, unless otherwise specified, "axial direction" refers to the direction in which the central axis I of the stator core 112 (= the central axis of the workpiece W) extends, and "radial direction" refers to the radial direction around the central axis I. Therefore, "radial outward" refers to the side away from the central axis I, and "radial inward" refers to the side closer to the central axis I. Furthermore, "axial outward" refers to the side away from the axial center of the stator core 112, and "axial inward" refers to the side closer to the axial center of the stator core 112. In addition, "circumferential direction" corresponds to the direction of rotation around the central axis I.

[0014] This manufacturing method first includes a mounting step (step S200) in which a plurality of coil pieces 52 forming the stator coil 114 are attached to the stator core 112 to form an assembly (hereinafter also referred to as "workpiece W").

[0015] Here, the stator coil 114 includes a U-phase coil, a V-phase coil, and a W-phase coil (hereinafter, when U, V, and W are not distinguished, they will be referred to as "phase coils"). The base end of each phase coil is connected to an input terminal (not shown), and the end of each phase coil is connected to the end of the other phase coils to form a neutral point. In other words, the stator coil 114 is star-connected. However, the connection configuration of the stator coil 114 may be changed as appropriate depending on the required motor characteristics, etc. For example, the stator coil 114 may be delta-connected instead of star-connected.

[0016] Each phase coil of the stator coil 114 is formed by combining multiple coil pieces 52. The coil piece 52 is in the form of a segment coil (segment conductor), which divides the phase coil into units that are easy to assemble (for example, units that are inserted into two slots 23). As shown in Figure 5, the coil piece 52 is made by covering a linear conductor (flat wire) 120 with a roughly rectangular cross-section with an insulating film 130. Here, the linear conductor is made of copper as an example. However, in modified examples, the linear conductor may be made of other conductive materials such as iron. Also, the cross-sectional shape of the linear conductor may not be rectangular.

[0017] In the example shown in Figure 4, one coil piece 52 may be formed in a substantially U-shape having a pair of linear slot housings 50 and a connecting portion 54 that connects the pair of slot housings 50. The connecting portion 54 on the other axial side (upper side in Figure 4) may be formed by shaping it circumferentially from the state shown in Figure 4. At the end of the connecting portion 54 on the other axial side (upper side in Figure 4), a coupling portion 40 is provided that connects to the coupling portion 40 of the connecting portion 54 of another coil piece 52. The coupling portion 40 is the portion where the insulating film 130 has been removed (i.e., the portion where the conductor portion relating to the linear conductor is exposed).

[0018] When assembling the coil piece 52 to the stator core 112, the pair of slot housings 50 are each inserted into the slots 23 between the teeth 22 (see Figure 3). In this case, the coil piece 52 can be assembled, for example, in the axial direction.

[0019] Multiple slot housing portions 50 of the coil piece 52 shown in Figure 4 are inserted radially into one slot 23. Consequently, multiple connecting portions 54 extending in the circumferential direction are arranged radially at both ends of the stator core 112. The connecting portions 54 (and the connecting portion 40 which is a part thereof) form the coil end portions 114A, which are parts that protrude axially outward from the axial end face of the stator core 112.

[0020] The coil pieces 52 may be wound around the stator core 112 in an overlapping winding configuration, for example. In the example shown in Figure 4, the lower connecting portion 54 may have an offset portion 521B that is offset in a direction that separates them by one layer in the radial direction. The upper connecting portion 54 may also have a similar offset portion 521A.

[0021] Although Figures 2 to 5 show stator cores 112 and stator coils 114 with specific structures, the structures of the stator cores 112 and stator coils 114 are arbitrary, as long as the stator coils 114 have a coupling portion 40. Furthermore, the winding method of the stator coils 114 is also arbitrary, and winding methods other than the overlapping winding method described above, such as a wave winding configuration, are also acceptable.

[0022] Next, this manufacturing method includes a joining step (step S202) in which the joint portions 40, which are the respective tips of one coil piece 52 and the other coil piece 52, are joined at one axial end of the workpiece W. The joint portions 40 may be overlapped and joined on their opposing sides. The method of joining the joint portions 40 may be arbitrary, but welding may be used, for example. In this case, welding may be performed by any method such as laser welding or TIG welding. Figure 6 schematically shows a joint portion 400 including a welded area 401 (joint area) formed on two radially overlapping joint portions 40.

[0023] For example, if four or more coil pieces 52 are mounted in each slot 23 of the stator core 112 in a manner that overlaps radially, the joining process may involve joining multiple sets radially, with two radially adjacent joining portions 40 (tip portions) forming one pair.

[0024] The joining range of the connecting parts 40 and the orientation of the connecting parts 40 when joining them (the orientation when overlapping) are arbitrary. For example, in Figure 6, the connecting parts 40 are upright in the vertical direction and overlapped radially, but they may also be overlapped in an X-shape when viewed radially, or only the connecting parts 40 may be overlapped radially in an oblique orientation. Furthermore, the connecting parts 40 may be overlapped axially in an orientation that extends radially.

[0025] In the joining process, not only may the coil pieces 52 be joined to each other, but also the coil pieces 52 may be joined to busbars or terminal blocks (output busbars for connection to inverters, not shown). Figure 2 schematically shows a neutral point busbar 59 as an example of such a busbar. The neutral point busbar 59 is a busbar that forms the neutral point described above.

[0026] In this embodiment, as an example, the stator core 112 has a joint 400 on only one axial side. Hereinafter, for distinction, the side of the stator core 112 (or the axial side of the workpiece W) that has the joint 400 will also be referred to as the lead side. In a modified example, joints 400 may be set on both axial sides of the stator core 112.

[0027] Next, in this manufacturing method, the workpiece W is set at the starting position (workpiece loading position) for the insulation coating process (step S204). At this time, the workpiece W may be set with the lead side facing upwards (i.e., with the joint portion 400 facing upwards). Hereinafter, this position with the lead side facing upwards will also be referred to as the "upward position of the workpiece W".

[0028] Next, this manufacturing method includes an inversion step (step S206) as the first step of the insulation coating process, in which the orientation of the workpiece W is inverted vertically. That is, the workpiece W is inverted vertically so that the lead side is on the bottom (i.e., the joint portion 400 is on the bottom). Hereinafter, this orientation with the lead side on the bottom will also be referred to as the "downward orientation of the workpiece W". The inversion of the orientation of the workpiece W may be achieved by a manufacturing device not shown (for example, an articulated robot with a hand to grasp the workpiece W).

[0029] Next, this manufacturing method includes an immersion step (step S208) in which the workpiece W is immersed in a tank 600 of liquid resin material M0. Figure 7 is a schematic side view of the workpiece W before it is immersed in the tank 600 of liquid resin material M0, and Figure 8 is a schematic side view of the workpiece W after it has been immersed in the tank 600 of liquid resin material M0. In this embodiment, the liquid resin material M0 is preferably a resin material that has the property of curing by heating and also curing by polymerization reaction when irradiated with ultraviolet light. The tank 600 may have an annular shape in a top view that corresponds to the annular part to be impregnated.

[0030] The immersion process is performed such that the workpiece W maintains a downward orientation, and the portion to be impregnated at the axial end (the lower end in the downward orientation) of the workpiece W is immersed in the liquid resin material M0 (i.e., positioned below the liquid level of the liquid resin material M0). The portion to be impregnated of the workpiece W is set to the portion of one of the multiple coil pieces 52 of the workpiece W. Specifically, the portion to be impregnated of the workpiece W is the axial end (lead-side end) of one of the multiple coil pieces 52, and includes the joint portion 400. More specifically, the portion to be impregnated of the workpiece W includes the portion of each coil piece 52 of the workpiece W where the conductor (conducting portion relating to a linear conductor) is exposed (the portion including the joint portion 400). The portion to be impregnated has an annular shape around the central axis I when viewed in the axial direction, and includes a part of the coil end portion 114A (a part on the axial end side).

[0031] In this embodiment, as will be described later, the immersion process is performed twice on a single workpiece W. In this case, the parts of the workpiece W to be impregnated in each immersion process may be exactly the same, or they may be partially different, as will be described later.

[0032] During the immersion process, the workpiece W may be kept immersed in a downward position for a certain period of time by a manufacturing device (not shown) (for example, an articulated robot with a hand for gripping the workpiece W).

[0033] Next, this manufacturing method includes a lifting step (step S210) in which the workpiece W is lifted out of the tank 600. The lifting of the workpiece W may be achieved by a manufacturing device (for example, an articulated robot having a hand for grasping the workpiece W) not shown. Figure 9 schematically shows the workpiece W in a downward position after being lifted. In the workpiece W in a downward position after being lifted, the liquid resin material M0 (schematically shown as a hatched area M1 in Figure 9) is impregnated in the impregnation target area at the axial end (the lower end in the downward position).

[0034] Next, this manufacturing method includes an outer diameter side resin curing step (step S212) in which a liquid resin material M0 is cured on the side surface of the part to be impregnated on the workpiece W in a downward position that has been lifted out of the tank 600. Hereinafter, in order to distinguish it from the resin curing process performed in the upper surface resin curing step (step S216) described later, the resin curing process performed in the outer diameter side resin curing step (step S212) will also be referred to as the "outer diameter side resin curing process".

[0035] In this embodiment, the outer diameter side resin curing treatment includes irradiating the side surface of the impregnation target area of ​​the workpiece W with ultraviolet light. Figure 9 schematically shows the state in which the outer diameter side resin curing treatment is being performed. Also in Figure 9 (and similarly in Figure 10 and others shown later), the liquid resin material M0 impregnated in the workpiece W is schematically shown by a hatched area M1. In the example shown in Figure 10, the ultraviolet irradiation device 900 irradiates ultraviolet light onto the radially outer side surface of the impregnation target area of ​​the workpiece W (see arrow R10). As a result, the radially outer portion (mainly the surface portion) of the liquid resin material M0 impregnated in the impregnation target area of ​​the workpiece W is cured.

[0036] Preferably, the ultraviolet irradiation device 900 irradiates the radially outer side surface of the impregnation target area of ​​the workpiece W with ultraviolet light over its entire circumference. This allows the liquid resin material M0 in the radially outer portion to be cured over its entire circumference. In this case, the workpiece W may rotate around the central axis I, or the ultraviolet irradiation device 900 may rotate. Alternatively, multiple ultraviolet irradiation devices 900 may be dispersed circumferentially around the radially outer side of the workpiece W.

[0037] Preferably, the ultraviolet irradiation device 900 is positioned relative to the workpiece W such that the optical axis 901 is substantially perpendicular to the radially outer side surface of the part of the workpiece W to be impregnated. That is, preferably, the ultraviolet irradiation device 900 is positioned relative to the workpiece W such that the optical axis 901 is located in a substantially horizontal plane. Here, "subjectively" is a concept that includes an error of, for example, 10% or less. Furthermore, preferably, the ultraviolet irradiation device 900 is positioned relative to the workpiece W such that the optical axis 901 passes through the part of the workpiece W to be impregnated, and more preferably, the optical axis 901 passes near the axial center of the part of the workpiece W to be impregnated. In this case, the liquid resin material M0 in the radially outer portion of the part of the workpiece W to be impregnated can be efficiently cured.

[0038] In this way, according to this embodiment, the radially outer portion of the liquid resin material M0 impregnated into the impregnation target area of ​​the workpiece W is cured while maintaining the downward position after being lifted out of the tank 600. Therefore, it is possible to reduce the inconvenience that may occur if the workpiece W is inverted upside down without performing this outer diameter side resin curing treatment after being lifted out of the tank 600. That is, if the workpiece W is inverted upside down in the next upside-down step (step S214) without performing this outer diameter side resin curing treatment after being lifted out of the tank 600, the liquid resin material M0 impregnated into the impregnation target area of ​​the workpiece W is likely to sag downward due to its own weight (see arrow R11 in Figure 11). In this case, the exposed area (the area not covered by the resin member) on the side surface of the coil end portion 114A may become unnecessarily narrow. If the exposed area on the side surface of the coil end portion 114A is insufficient, the cooling efficiency when a coolant (e.g., oil) is supplied to the side surface of the coil end portion 114A during the operation of the rotating electric machine may decrease (see Figure 19 and describe later). Furthermore, if the liquid resin material M0 on the radially outer side surface of the impregnation target area drips downward, it may adhere to the axial end face (upper end face) of the stator core 112. In this case, the liquid resin material M0 adhering to the stator core 112 must be removed separately with a scraper or the like. In contrast, according to this embodiment, as described above, such inconveniences can be reduced.

[0039] Next, this manufacturing method includes an inversion step (step S214) in which the orientation of the workpiece W is reversed vertically. That is, the workpiece W is inverted vertically from a downward orientation to an upward orientation. Figure 11 schematically shows the workpiece W after being inverted vertically to an upward orientation.

[0040] However, when the workpiece W is inverted while impregnated with liquid resin material M0, there is a problem that the liquid resin material M0 is easily scattered due to centrifugal force. If the liquid resin material M0 is scattered, material waste may occur, and the thickness and coverage of the insulating coating covering the joint 400 of the coil end portion 114A may become insufficient. Furthermore, if the rotation speed of the workpiece W is reduced to reduce centrifugal force, the time required for the inversion process increases, and the CT (Cycle Time) tends to increase.

[0041] Therefore, in this embodiment, the workpiece W is preferably rotated around a rotation axis I1 in a horizontal plane passing through the area to be impregnated, as schematically shown by arrow R12 in Figure 12, thereby inverting it from a downward position to an upward position. That is, the workpiece gripping unit 1000 inverts the workpiece W so that it rotates around a rotation axis I1 in a horizontal plane passing through the area to be impregnated. This efficiently reduces the distance from the rotation axis I1 to the area to be impregnated (the radius that affects centrifugal force), and even when inverted at a relatively fast rotation speed, the centrifugal force does not become excessive (for example, no centrifugal force is generated that would cause the liquid resin material M0 to scatter). In this way, it is possible to prevent the scattering of the liquid resin material M0 from the workpiece W and to prevent an increase in CT.

[0042] Here, while the workpiece W is being inverted, the rotation axis I1 may be fixed or moved translationally. For example, the rotation axis I1 may move upward while rotating the workpiece W. This allows the workpiece W to be moved to the next process while its orientation is inverted in a manner that prevents the liquid resin material M0 from scattering. This type of operation is particularly suitable when the workpiece gripping unit 1000 is attached to the hand of a multi-joint robot.

[0043] Furthermore, the rotation axis I1 may be fixed in a constant positional relationship with respect to the workpiece W to be inverted throughout the inversion operation, or its positional relationship with respect to the workpiece W may change only for a portion of the inversion operation. For example, if the workpiece gripping unit 1000 is attached to the hand of an articulated robot, the positional relationship between the rotation axis I1 and the workpiece W may deviate from the positional relationship in which the rotation axis I1 passes through the part to be impregnated only for a portion of the operation, such as the final stage of the inversion operation.

[0044] Furthermore, the rotation axis I1 preferably passes through the impregnation target area as described above, so as to reduce the radius related to centrifugal force, but is not limited to this. When the rotation radius of the axial center of the stator core 112 around the rotation axis I1 is taken as the reference radius, a significant effect can be obtained if the rotation radius of the impregnation target area around the rotation axis I1 is less than or equal to the reference radius. For example, the rotation axis I1 may be set to pass between the axial center of the stator core 112 and the impregnation target area. Even in this case, the radius related to centrifugal force (the rotation radius of the impregnation target area around the rotation axis) is smaller than in the comparative example (see Figure 12A) which has a rotation axis I2 located on the opposite side of the impregnation target area and outside the workpiece W, so the above-mentioned effect can still be obtained. In the comparative example shown in Figure 12A, the workpiece W gripped by the loader hand 1200 is rotated around the rotation axis I2 located on the opposite side of the impregnation target area and outside the workpiece W. In this case, the radius r2 related to centrifugal force (the rotational radius of the impregnation target area around the rotation axis I2) becomes relatively large (at least greater than or equal to the axial length of the stator core 112), and the aforementioned problems such as the scattering of the liquid resin material M0 are likely to occur.

[0045] Next, this manufacturing method includes an upper surface resin curing step (step S216) in which a liquid resin material M0 is cured on the upper surface of the part to be impregnated on the workpiece W which has been inverted to an upward position. Hereinafter, the resin curing treatment related to the upper surface resin curing step will also be referred to as the "upper surface resin curing treatment" to distinguish it from the outer diameter side resin curing treatment described above.

[0046] In this embodiment, the top surface resin curing treatment includes irradiating the top surface of the impregnation target area of ​​the workpiece W with ultraviolet light. Figure 13 schematically shows the state in which the top surface resin curing treatment is being performed. In the example shown in Figure 13, the ultraviolet irradiation device 900 irradiates the top surface of the impregnation target area of ​​the workpiece W with ultraviolet light (see arrow R13). As a result, the upper portion (mainly the upper surface portion) of the liquid resin material M0 impregnated into the impregnation target area of ​​the workpiece W is cured. Note that the ultraviolet irradiation device 900 may be the same as the ultraviolet irradiation device 900 used in the outer diameter side resin curing treatment described above, or it may be a different device.

[0047] Preferably, the ultraviolet irradiation device 900 irradiates the upper surface of the part of the workpiece W to be impregnated with ultraviolet light over its entire circumference. This allows the liquid resin material M0 in the upper portion to be cured over its entire circumference. In this case, the workpiece W may rotate around the central axis I, or the ultraviolet irradiation device 900 may rotate. Alternatively, multiple ultraviolet irradiation devices 900 may be arranged circumferentially on the upper side of the workpiece W.

[0048] Preferably, the ultraviolet irradiation device 900 is positioned relative to the workpiece W such that the optical axis 901 is substantially perpendicular to the upper surface of the part of the workpiece W to be impregnated. That is, preferably, the ultraviolet irradiation device 900 is positioned relative to the workpiece W such that the optical axis 901 is located in a substantially vertical plane. Here, "subjectively" is a concept that includes an error of, for example, 10% or less. Furthermore, preferably, the ultraviolet irradiation device 900 is positioned relative to the workpiece W such that the optical axis 901 passes through the part of the workpiece W to be impregnated, and more preferably, the optical axis 901 passes near the center of the radial range (range from the innermost diameter position to the outermost diameter position) of the part of the workpiece W to be impregnated. In this case, the liquid resin material M0 in the upper portion of the part of the workpiece W to be impregnated can be efficiently cured.

[0049] In this way, according to this embodiment, the workpiece W is in an upward position, and the upper portion (axial end) of the liquid resin material M0 impregnated into the area to be impregnated is cured. Therefore, it is possible to reduce the inconveniences that may occur when the upper surface resin curing treatment is performed on the workpiece W while it is in a downward position after being lifted out of the tank 600 (i.e., when the upper surface resin curing treatment is performed simultaneously with the outer diameter side resin curing treatment described above). Specifically, if the resin curing treatment is performed on the lower surface of the area to be impregnated on the workpiece W while it is in a downward position after being lifted out of the tank 600, the liquid resin material M0 impregnated into the area to be impregnated on the workpiece W may harden while sagging downwards due to its own weight. In other words, the liquid resin material M0 may harden in an icicle-like shape. In contrast, according to this embodiment, since the upper surface resin curing treatment is performed in an upward position as described above, such inconveniences can be reduced.

[0050] Furthermore, according to this embodiment, by curing the upper portion (axial end) of the liquid resin material M0 impregnated into the impregnation target area, a thin film of the liquid resin material M0 can be formed on the corner of the rectangular cross-section of the joint 40 (see Figure 5, hereinafter referred to as the "joint edge 122"). In other words, even on the joint edge 122, where it is difficult to form the liquid resin material M0 due to the influence of wettability around the coil piece 52, a film of the liquid resin material M0 can be formed, albeit with a relatively thin thickness. The joint edge 122 on which such a film of liquid resin material M0 is formed has increased wettability due to the film. In this way, the wettability of the joint edge 122 (wettability related to the liquid resin material M0) can be increased. As a result, in the subsequent second immersion step (described later), it becomes easier to secure the required thickness of the insulating coating (cured liquid resin material M0) on the joint edge 122 of the coil piece 52. In other words, the second immersion step allows for the formation of a relatively thick film on the joint edge 122, using the film of liquid resin material M0 formed during the first immersion step as a base. This point will be explained again when describing the second immersion step.

[0051] Next, this manufacturing method includes an inner diameter side resin curing step (step S218) in which a liquid resin material M0 is cured on the radially inner side surface of the part to be impregnated on the workpiece W which has been inverted to an upward position. Hereinafter, the resin curing treatment related to the inner diameter side resin curing step will also be referred to as the "inner diameter side resin curing treatment" to distinguish it from the outer diameter side resin curing treatment and the top surface resin curing treatment described above.

[0052] In this embodiment, the inner diameter side resin curing treatment includes irradiating the radially inner side surface of the impregnation target area of ​​the workpiece W with ultraviolet light. Figure 14 schematically shows the state in which the inner diameter side resin curing treatment is being performed. In the example shown in Figure 14, the ultraviolet irradiation device 900 irradiates the radially inner side surface of the impregnation target area of ​​the workpiece W with ultraviolet light (see arrow R14). As a result, the radially inner portion (mainly the surface portion) of the liquid resin material M0 impregnated into the impregnation target area of ​​the workpiece W is cured. Note that the ultraviolet irradiation device 900 may be the same as the ultraviolet irradiation device 900 used in the top surface resin curing treatment described above.

[0053] Preferably, the ultraviolet irradiation device 900 irradiates ultraviolet light over the entire circumference of the radially inner side surface of the impregnation target area of ​​the workpiece W. This allows the liquid resin material M0 in the radially inner portion to be cured over the entire circumference of the impregnation target area. In this case, the inner diameter side resin curing treatment may be performed sequentially in parallel with the upper surface resin curing treatment. Specifically, the upper surface resin curing treatment and the inner diameter side resin curing treatment may be performed together for each divided circumferential range of the entire circumference of the impregnation target area of ​​the workpiece W. Alternatively, the inner diameter side resin curing treatment may be performed before the upper surface resin curing treatment. In this case, the inner diameter side resin curing treatment may be performed simultaneously with or before the outer diameter side resin curing treatment.

[0054] Preferably, the ultraviolet irradiation device 900 is positioned relative to the workpiece W such that the optical axis 901 is substantially perpendicular to the radially inner side surface of the impregnation target area of ​​the workpiece W. That is, preferably, the ultraviolet irradiation device 900 is positioned relative to the workpiece W such that the optical axis 901 is located in a substantially vertical plane. Here, "subjectively" is a concept that includes an error of, for example, 10% or less. Furthermore, preferably, the ultraviolet irradiation device 900 is positioned relative to the workpiece W such that the optical axis 901 passes through the impregnation target area of ​​the workpiece W, and more preferably, the optical axis 901 passes near the axial center of the impregnation target area of ​​the workpiece W. In this case, the liquid resin material M0 in the upper portion of the impregnation target area of ​​the workpiece W can be efficiently cured.

[0055] However, depending on the size of the ultraviolet irradiation device 900 and the space inside the workpiece W in the radial direction, the ultraviolet irradiation device 900 may be positioned relative to the workpiece W such that the optical axis 901 intersects diagonally with respect to the radially inner side surface of the impregnation target area of ​​the workpiece W, as shown in Figure 14. In this case, one of the inner diameter side resin curing treatment and the top surface resin curing treatment may serve as the other.

[0056] Once the resin curing process on the inner diameter side (step S218) is completed, the insulation coating process for that round is finished.

[0057] Next, the manufacturing method determines whether the number of times the insulation coating process has been performed on a single workpiece W has reached a predetermined number (in this embodiment, for example, 2 times) (step S220). This determination may be performed by a person or by image processing, etc. If the determination result is "YES", the process proceeds to the next step; otherwise, steps S206 to S218 are performed in the same manner to perform the second insulation coating process. Figure 15 schematically shows the workpiece W inverted upside down in step S206 to a downward position during the second insulation coating process. After that, the workpiece W undergoes a second immersion process, etc.

[0058] The second insulation coating process may be exactly the same as the first insulation coating process. In this case, for example, the control of the manufacturing equipment can be simplified.

[0059] However, the second insulating coating step preferably differs from the first insulating coating step in at least the immersion step. Specifically, the immersion step in the second insulating coating step reduces the area to be impregnated compared to the immersion step in the first insulating coating step. That is, the area to be impregnated in the second immersion step may be only a part of the area to be impregnated in the first immersion step (a part on the axial end side). In this case, the area to be impregnated in the second immersion step may be a minimum area including the joint edge 122 of the coil piece 52. This makes it possible to efficiently form an insulating coating (cured product of liquid resin material M0) with the required function using a relatively small amount (e.g., a minimum) of liquid resin material M0.

[0060] Figure 15 schematically shows the area Q15 to which the impregnation target area for the second insulation coating process belongs, relative to the area of ​​the liquid resin material M0 impregnated into the workpiece W in the first insulation coating process (hatched area M1).

[0061] In this embodiment, the insulating coating process is performed multiple times (twice in this embodiment as an example). This makes it possible to ensure the required thickness of the insulating coating (cured liquid resin material M0) on the joint edge 122 of the coil piece 52.

[0062] Specifically, Figure 16 schematically shows the workpiece W in an upward position after the second insulation coating process is completed. In Figure 16, the area of ​​the liquid resin material M0 formed by the second insulation coating process is schematically shown in hatched area M2, along with the area of ​​the liquid resin material M0 formed by the second insulation coating process (hatched area M1). Note that in Figure 16 (and similarly in Figure 18, etc., which will be shown later), for the sake of explanation, only the axial end of the coil end portion 114A of the stator coil 114 is schematically shown without being omitted.

[0063] In the first insulating coating process, a thin film of liquid resin material M0 can be formed on the joint edge 122 of the coil piece 52, as schematically shown in the hatched area M1. In this case, the thickness of the thin film of liquid resin material M0 on the joint edge 122 is significantly smaller than the required thickness of the insulating coating (cured liquid resin material M0) because the wettability of the joint edge 122 (wettability of the corner of the linear conductor) is low. However, even if the thin film of liquid resin material M0 on the joint edge 122 is relatively thin, it can increase the wettability of the joint edge 122 to the liquid resin material M0. Therefore, during the immersion process in the second insulating coating process, the liquid resin material M0 on the joint edge 122 adheres more easily. That is, in the second insulating coating process, a further film of liquid resin material M0 can be formed on the joint edge 122 of the coil piece 52 with a relatively large thickness, as schematically shown in the hatched area M2. In this way, it becomes possible to secure the necessary thickness of insulating coating (cured liquid resin material M0) even for the joint edges 122 of the coil pieces 52, which have low wettability.

[0064] Once the second insulating coating process is complete, the manufacturing method includes a heating step (step S222) in which the workpiece W is heated so that the liquid resin material M0 throughout the workpiece W hardens. This heating step has the function of completely hardening the parts of the liquid resin material M0 that have not hardened in the various resin hardening steps described above (for example, the parts inside the surface). The heating method in the heating step is arbitrary and may be achieved, for example, by placing the workpiece W in a furnace. The liquid resin material M0 impregnated in the impregnation area, including the part of the workpiece W to be impregnated, is completely hardened by heating. As a result, an insulating coating of liquid resin material M0 is formed on the stator coil 114.

[0065] The orientation of the workpiece W during the heating process is arbitrary, but preferably downward, as schematically shown in Figure 17. Figure 17 schematically shows multiple workpieces W arranged in a downward orientation while undergoing the heating process. In Figure 17, a workpiece gripping section 1001 of the manufacturing apparatus schematically shows how multiple workpieces W are held between the workpieces W, but the workpieces W may also be supported on the base in such a manner that the end face of the stator core 112 abuts against the upper surface of the base (not shown). Also, in Figure 17, as an example, heat is radiated from below to the workpiece W (see arrow R17), but the direction of heat radiation is arbitrary.

[0066] Incidentally, during the heating process, if the device is in an upward position, the partially cured liquid resin material M0 may sag downwards to the stator core 112 due to its own weight (see arrow R16 in Figure 16). In this case, the liquid resin material M0 adhering to the stator core 112 must be removed separately with a scraper or the like.

[0067] In contrast, in the downward orientation, even if the partially cured liquid resin material M0 moves downward due to its own weight before it is completely hardened, it will not reach the stator core 112. Furthermore, the portion of the liquid resin material M0 that has been cured by the outer diameter side resin curing treatment, the top surface resin curing treatment, and the inner diameter side resin curing treatment (see the C-shaped area 1800 in the directional view of Figure 18) functions as a "bottom cover," reducing the possibility of the sagging liquid resin material M0 forming an icicle-like structure. Figure 18 schematically shows the downward movement of the partially cured liquid resin material M0, as indicated by arrow R19. This downward movement of the partially cured liquid resin material M0 is blocked by the portion of the liquid resin material M0 that has been cured by the outer diameter side resin curing treatment, the top surface resin curing treatment, and the inner diameter side resin curing treatment. This prevents the problems that may occur when the heating process is performed in a downward orientation.

[0068] In this embodiment, by performing the heating process in a downward position, it is possible to prevent the liquid resin material M0 from dripping onto the stator core 112, while the "bottom cover" function of the portion of liquid resin material M0 cured by the outer diameter side resin curing treatment, the top surface resin curing treatment, and the inner diameter side resin curing treatment reduces the icicle-like curing of the liquid resin material M0 that would otherwise drip downward.

[0069] In order to effectively enhance this "bottom cover" function, it is desirable that the outer diameter side resin curing treatment, the top surface resin curing treatment, and the inner diameter side resin curing treatment all be performed, however, the outer diameter side resin curing treatment and / or the inner diameter side resin curing treatment may be omitted.

[0070] Furthermore, according to this manufacturing method, as described above, one heating step is performed for every two insulation coating steps, thus reducing energy consumption (and the resulting carbon dioxide emissions) compared to the case where a heating step is performed for each insulation coating step. Therefore, according to this manufacturing method, the thickness of the insulation coating of the liquid resin material M0 can be efficiently increased.

[0071] Furthermore, when a heating process is performed after each insulating coating process, a discontinuous boundary (layer separation) is formed between the insulating coating of the liquid resin material M0 formed the first time and the insulating coating of the liquid resin material M0 formed the second time. However, this manufacturing method eliminates such boundaries and increases the overall strength of the insulating coating of the liquid resin material M0. In other words, in this manufacturing method, the liquid resin material M0 impregnated twice decreases in viscosity during the heating process and forms a single layer, so there are no discontinuous boundaries (layer separation) within the insulating coating, and the strength is improved.

[0072] Next, with reference to Figure 19, a suitable cooling structure for a rotating electric machine 1 incorporating a stator manufactured by this manufacturing method will be described.

[0073] Figure 19 is a schematic diagram illustrating an example of a cooling structure, and shows a general overview of a part of the cross-sectional structure of the rotating electric machine 1.

[0074] In the example shown in Figure 19, oil is supplied to the coil end portions 114A at both axial ends of the stator coil 114 from the radially outer and radially inner sides. Specifically, the oil supplied to the internal oil passage 60 of case 2 (see arrow R20A) is supplied to the radially outer side surface of the coil end portion 114A through an oil hole 62 that penetrates radially inward (see arrow R20). The oil hole 62 may be positioned vertically upward to promote oil dripping by gravity. In addition, the oil supplied to the axial oil passage 64 of rotor shaft 112A (see arrow R21A) is supplied to the radially inner side surface of the coil end portion 114A through an oil hole 66 that penetrates radially outward (see arrow R21).

[0075] According to this manufacturing method, as described above, the coil end portion 114A of the stator coil 114 is coated with an insulating coating of liquid resin material M0. The areas of the stator coil 114 coated with the insulating coating of liquid resin material M0 have lower thermal conductivity than the areas where it is not coated (i.e., the insulating film 130 is the surface). Therefore, if the exposed area of ​​the radially outer side surface of the coil end portion 114A that is not covered by the insulating coating of liquid resin material M0 becomes unnecessarily narrow, the cooling performance by oil from the oil holes 62 described above may be unnecessarily reduced. Similarly, if the exposed area of ​​the radially inner side surface of the coil end portion 114A that is not covered by the insulating coating of liquid resin material M0 becomes unnecessarily narrow, the cooling performance by oil from the oil holes 66 described above may be reduced.

[0076] In this regard, according to the present manufacturing method, as described above, the radially outer portion of the liquid resin material M0 impregnated into the impregnation target area by the outer diameter side resin curing treatment is cured while in a downward position. Therefore, even if the workpiece W is subsequently in an upward position, the radially outer liquid resin material M0 will not sag downward. This reduces the possibility that the exposed area of ​​the radially outer side surface of the coil end portion 114A that is not covered by the insulating coating of the liquid resin material M0 will become unnecessarily narrow. As a result, the cooling performance of the coil end portion 114A by oil from the oil holes 62 described above can be effectively improved.

[0077] In the above-described embodiment, the inner diameter side resin curing treatment is performed on a workpiece W in an upward position, but it may also be performed on a workpiece W in a downward position, similar to the outer diameter side resin curing treatment. In this case, the inner diameter side resin curing treatment may be performed simultaneously with the outer diameter side resin curing treatment in parallel. In this case, the radially inner portion of the liquid resin material M0 impregnated into the impregnation target area by the inner diameter side resin curing treatment is cured while in a downward position, so even if the workpiece W is subsequently in an upward position, the radially inner liquid resin material M0 will not sag downward. This reduces the possibility that the exposed area of ​​the radially inner side surface of the coil end portion 114A that is not covered by the insulating coating of the liquid resin material M0 will become unnecessarily narrow. As a result, the cooling performance of the coil end portion 114A by oil from the oil holes 66 described above can be effectively improved.

[0078] Next, with reference to Figure 20 and subsequent figures, further preferred configurations relating to the manufacturing method described above will be explained.

[0079] Figure 20 is an explanatory diagram of a preferred method for the immersion process (step S208). Figure 20 schematically shows a portion of the workpiece W together with the tank 600 at the start of the immersion process in the first insulation coating process. Figure 21 is an explanatory diagram of the effect of the method shown in Figure 20, schematically showing the state in which part Q20 in Figure 20 has entered the liquid resin material M0 in the tank 600. Figure 22 is an explanatory diagram of potential problems that may occur in the immersion process according to a comparative example. Figures 23 and 24 are explanatory diagrams of other inclined positions.

[0080] In the immersion process, the workpiece W is preferably immersed in the liquid resin material M0 of the tank 600 in an inclined position. An inclined position means that the angle α (see Figure 20) of the stator core 112 in the axial direction with respect to the perpendicular I3 to the liquid surface of the liquid resin material M0 in the tank 600 is different from 0 degrees. The angle α is arbitrary, but may be, for example, 5 degrees or more. Hereinafter, for comparison, the position of the workpiece W with angle α = 0 will also be referred to as the upright position.

[0081] Incidentally, the area of ​​the workpiece W to be impregnated is formed by coil pieces 52, busbars, etc., but may have a planar area that extends perpendicular to the central axis I. Such a planar area is formed by a part of the coil piece 52, a part of the neutral point busbar 59, etc. Such a planar area is likely to cause air to accumulate below the workpiece W when the workpiece W is immersed in a tank 600 of liquid resin material M0 in an upright position. Figure 22 schematically shows the air (bubbles) B22 that accumulates below the workpiece W when the workpiece W is immersed in a tank of liquid resin material in an upright position. If the end face of the area of ​​the workpiece W to be impregnated is covered with liquid resin material M0 while such air B22 is attached to the bottom of the workpiece W, it can become a cavity in the liquid resin material M0, which can cause voids in the insulating coating (resin mold) after the liquid resin material M0 has hardened.

[0082] In contrast, as shown in Figure 20, when the workpiece W is immersed in a tank of liquid resin material in an inclined position, the air (bubbles) B21 below the workpiece W rises along the inclined planar portion 591 (in Figure 21, the planar portion 591 of the neutral point busbar 59). That is, the air that could accumulate below the workpiece W can be reduced or eliminated. In this way, the method shown in Figure 20 makes it possible to reduce voids in the liquid resin material M0 of the impregnation target area that may occur when the workpiece W is immersed in the tank of liquid resin material. As a result, voids that may occur in the insulating coating (resin mold) after curing can be reduced or eliminated.

[0083] In the inclined position shown in Figure 21, the bubble B21 rises radially outward. However, an inclined position may be set such that, for example, the bubble B23 rises radially inward (see arrow R23), as shown in Figure 23. Alternatively, an inclined position may be set such that the bubble B24 rises circumferentially (see arrow R24), as shown in Figure 24.

[0084] Thus, the highest circumferential position of the workpiece W in the inclined position may be appropriately determined to facilitate the rise of bubbles, depending on the position and shape of the planar portion. In this case, the highest circumferential position of the workpiece W in the inclined position may be set, for example, so that the length of the planar portion along which the bubbles follow when rising (the distance the bubbles travel) is shortened. Specifically, if the planar portion has a longitudinal direction and a transverse direction, the inclined position of the workpiece W may be determined such that the inclination angle of the planar portion with respect to the liquid surface of the liquid resin material M0 is greater along the transverse direction than along the longitudinal direction. In this case, since the bubbles rise along the transverse direction, the length of the planar portion along which the bubbles follow when rising (the distance the bubbles travel) can be shortened. In other words, an inclined position that facilitates the release of bubbles can be achieved.

[0085] In the immersion process according to the method shown in Figure 20, the workpiece W is preferably changed from an inclined position to an upright position after the flat portion of the workpiece W has fallen below the liquid level of the liquid resin material M0 in the tank 600. That is, the final position of the workpiece W in the immersion process is preferably an upright position. In this case, the immersion depth of the workpiece W is approximately the same at each position in the circumferential direction (i.e., the formation range of the insulating coating of the liquid resin material M0 is approximately the same at each position in the circumferential direction), which facilitates product control.

[0086] In this way, when the immersion depth of the workpiece W during the immersion process is made approximately the same at each position in the circumferential direction, the inclined position may be set so that the planar portion is immersed before other circumferential positions (so that it reaches below the liquid surface first) in order to prevent the immersion depth from becoming unnecessarily large. In this case, even if the position is changed from an inclined position to an upright position when most of the planar portion has been immersed, it is advantageous in that the immersion depth is less likely to increase. For example, the inclined position shown in Figure 23 is more advantageous than the inclined position shown in Figure 21 in that it is less likely to increase the immersion depth. Therefore, an inclined position may be adopted in which the circumferential range to which the neutral point busbar 59 having the planar portion 591 extends is lower than other circumferential ranges.

[0087] Furthermore, when the insulating coating process is performed multiple times on a single workpiece W, the method shown in Figure 20 is preferably implemented in each immersion step, but it may also be implemented in only some of the immersion steps.

[0088] Figure 25 is an explanatory diagram illustrating a preferred method for the immersion step (step S208) in the second insulation coating process. Figure 25 schematically shows a portion of the workpiece W in an inclined position, along with the tank 600, during the immersion step in the second insulation coating process. Figure 26 is an explanatory diagram illustrating potential problems that may occur in the immersion step according to a comparative example.

[0089] In the following description of the second insulation coating process, unless otherwise specified, the impregnation target area of ​​the workpiece W refers to the impregnation target area related to the immersion process in the second insulation coating process. Furthermore, in the following, the immersion process in the first insulation coating process will also be referred to as the "first immersion process," and the immersion process in the second insulation coating process will also be referred to as the "second immersion process."

[0090] In the second immersion step, the workpiece W is preferably partially immersed in the liquid resin material M0 of the tank 600 in two or more inclined positions before being fully immersed. An inclined position refers to a position of the workpiece W in which the angle α (see Figure 20) described above is significantly greater than 0. The angle α in the second immersion step is arbitrary, but may be greater than the angle α described above, as shown in Figure 20.

[0091] Two or more inclined positions include positions in which the angle α is the same, but the highest circumferential position of the workpiece W is different. That is, in an inclined position, only a portion of the workpiece W to be impregnated (a portion in the circumferential direction) is lifted above the liquid surface of the liquid resin material M0 in the tank 600, but the circumferential position of this portion changes depending on the type of inclined position. In a modified example, the two or more inclined positions may also involve differences in the angle α.

[0092] Incidentally, in this manufacturing method, when the insulating coating process is divided into two or more steps to ensure sufficient insulating coating thickness (for example, the thickness of the insulating coating on the joint edge 122), when the workpiece W is immersed in the liquid resin material tank in the second and subsequent steps, air tends to accumulate beneath the workpiece due to the uneven morphology of the liquid resin material impregnated in previous steps (i.e., the unevenness of the axial end face of the workpiece W). Furthermore, since the liquid resin material M0 is non-permeable, the liquid resin material M0 impregnated in previous steps obstructs the escape of air. Such cavities can cause voids within the insulating coating (resin mold) after curing.

[0093] Figure 26 schematically shows air (bubbles) B26 that accumulates below the workpiece W due to the uneven morphology of the liquid resin material M0 that was impregnated in a previous application. When the end face of the part of the workpiece W to be impregnated is covered with the liquid resin material M0 while this air B2 is attached to the bottom of the workpiece W, it can form a cavity within the liquid resin material M0, as described above with reference to Figure 22, and may cause voids in the insulating coating (resin mold) after the liquid resin material M0 has hardened.

[0094] In contrast, as shown in Figure 25, when the workpiece W is immersed in a tank of liquid resin material in an inclined position, the liquid resin material M0 can easily penetrate into the recess 70, as schematically shown by arrow R25 in Figure 25. That is, it is possible to reduce or eliminate air that may accumulate below the workpiece W due to the recess 70. In this way, the method shown in Figure 20 makes it possible to reduce voids in the liquid resin material M0 of the impregnation target area that may occur when the workpiece W is immersed in a tank of liquid resin material. As a result, it is possible to reduce or eliminate voids that may occur in the insulating coating (resin mold) after curing.

[0095] Here, the irregularities on the axial end face of the workpiece W that can cause the voids mentioned above (the irregular shape of the liquid resin material M0 applied to the workpiece W in the first immersion step) are likely to occur when four or more coil pieces 52 are mounted in each slot 23 of the stator core 112 in a manner that overlaps radially. In this case, when multiple sets of two radially adjacent joints 40 are joined radially, a recess 70 (see Figure 25) that is recessed inward in the axial direction is likely to be formed between the multiple sets of joints 400 in the radial direction. In Figure 25, one recess 70 is shown between two sets of radial joints 400, but in the case of three or more sets, two or more recesses 70 will be formed. The recess 70 basically extends around the entire circumference of the workpiece W.

[0096] In this regard, if, in the second immersion step, the workpiece W is partially immersed in the liquid resin material M0 of the tank 600 in two or more inclined positions before the entire workpiece is immersed, the liquid resin material M0 in the tank 600 can enter the recesses 70 at each position in the circumferential direction in the manner shown in Figure 25. In particular, if the recesses 70 are continuous in the circumferential direction, the air in the recesses 70 in the circumferential range that enters the liquid resin material M0 of the tank 600 in one type of inclined position can escape to the outside of the liquid resin material M0 through the recesses 70 in other circumferential ranges located above the liquid resin material M0. That is, the air in the recesses 70 that are below the liquid surface can escape to the outside through other recesses 70 that are above the liquid surface.

[0097] In the second immersion process, a greater number of different inclination positions applied to a single workpiece W is advantageous in that it can reduce the amount of air that may remain in the recesses 70 at each position in the circumferential direction. On the other hand, a greater number of different inclination positions is disadvantageous from the viewpoint of CT.

[0098] Therefore, the number of types of inclination positions applied to a single workpiece W in the second immersion step is preferably three or more, and may be eight, for example, as will be explained below with reference to Figure 27.

[0099] Figure 27 is an explanatory diagram illustrating eight preferred inclination positions. Figure 27 schematically shows the workpiece W in a top view, along with the circumferential ranges SC1 to SC8 of the workpiece W, which is divided into eight sections.

[0100] In this case, the eight types of inclination positions include a first type of inclination position in which the circumferential range SC1 of the workpiece W is most immersed in the liquid resin material M0 of the tank 600 (i.e., located most below the liquid surface), a second type of inclination position in which the circumferential range SC2 of the workpiece W is most immersed in the liquid resin material M0 of the tank 600, and similar third to eighth types of inclination positions relating to SC3 to SC8.

[0101] The order in which the eight types of inclined positions are formed is arbitrary, but for example, they may be formed in the clockwise order shown in Figure 27, from the first type of inclined position to the eighth type of inclined position. In this case, the air in the recess 70 can be expelled to the outside in a clockwise direction in the circumferential direction. In this case, although it becomes impossible to expel the air in the recess 70 in the circumferential direction in the eighth type of inclined position, the amount of air in the recess 70 can be minimized by, for example, increasing the angle α. If, for example, the configuration of the recess 70 differs from other circumferential ranges in the circumferential range where the neutral point busbar 59 is located, the circumferential range SC8 related to the eighth type of inclined position may be made to coincide with the circumferential range where the neutral point busbar 59 is located.

[0102] Furthermore, in the second immersion step using the method shown in Figure 27, the workpiece W may be changed from an inclined position to an upright position after the eighth type of inclined position. In this case, the formation range and thickness of the insulating coating of the liquid resin material M0 will be approximately the same at each position in the circumferential direction, making product control easier.

[0103] Although each embodiment has been described in detail above, the invention is not limited to any particular embodiment, and various modifications and changes are possible within the scope described in the claims. Furthermore, it is possible to combine all or more of the components of the embodiments described above.

[0104] For example, in the above-described embodiment, an outer diameter side resin curing treatment is performed as a preferred embodiment, but an inner diameter side resin curing treatment may be performed instead of the outer diameter side resin curing treatment. [Explanation of Symbols]

[0105] 40... Joint (tip), 52... Coil piece, 112... Stator core, 114... Stator coil, 59... Neutral point busbar (busbar), 591... Planar section, 600... Tank, W... Workpiece, M0... Liquid resin material

Claims

1. A mounting process in which a workpiece is formed by attaching multiple coil pieces that form a stator coil to a stator core, Following the mounting step, a joining step is performed in which the respective tip portions of one coil piece and the other coil piece are joined together at one axial end of the workpiece. Following the joining process, the workpiece is immersed in a tank of liquid resin material so that the part to be penetrated, including the joint between the tip portions, is submerged. The process includes, after the immersion step, a curing step in which the liquid resin material is cured. The immersion step includes immersing the portion to be penetrated below the liquid surface of the liquid resin material in the tank, with the workpiece in an inclined position such that the angle between the stator core and the liquid surface of the liquid resin material in the tank is different from 90 degrees. A method for manufacturing a stator for a rotating electric machine, wherein the immersion step is a step in which the stator core is immersed without rotating the stator core around its central axis.

2. The method for manufacturing a stator for a rotating electric machine according to claim 1, wherein the joining step includes joining a busbar having a planar portion extending in a direction perpendicular to the axial direction of the stator core to the coil piece.

3. The aforementioned planar portion has a longitudinal direction and a transverse direction, The method for manufacturing a stator for a rotating electric machine according to claim 2, wherein the inclination posture is such that the angle of inclination of the planar portion with respect to the liquid surface of the liquid resin material is greater in the short direction than in the longitudinal direction.

4. A method for manufacturing a stator for a rotating electric machine according to any one of claims 1 to 3, wherein the immersion step includes immersing the portion to be penetrated below the liquid surface of the liquid resin material in the tank in the inclined position of the workpiece, and then changing the position of the workpiece to an upright position in which the angle between the axial direction of the stator core and the liquid surface of the liquid resin material in the tank is 90 degrees.

Images