Method and apparatus for manufacturing a stator for a rotating electric machine

Abstract

To reduce a scattering amount of a liquid resin material when workpiece is vertically reversed.SOLUTION: A stator manufacturing method for a rotary electric machine includes: a mounting step of mounting a plurality of conductor pieces forming a stator coil on a stator core, and forming a workpiece; a joint step of joining tips of each of one conductor piece and the other conductor piece, on one end side in an axial direction of the workpiece, after the mounting step; an impregnation step of impregnating an impregnation object part including a joint part between the tips of the workpiece with a liquid resin material, after the joint step; and a vertical reverse step of vertically reversing the attitude of the workpiece, after the impregnation step, wherein the vertical reverse step includes rotating the workpiece around a rotary shaft extending on a side closer to one end side in the axial direction than the center in the axial direction of the stator core.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present disclosure relates to a method and an apparatus for manufacturing a stator for a rotating electric machine. [Background technology]

[0002] A known method for manufacturing a stator for a rotating electric machine includes preparing a workpiece for a rotating electric machine, in which a plurality of coil pieces that form a stator coil are attached to a stator core, joining the tips of the plurality of coil pieces at one axial end of the workpiece, impregnating the impregnation target area, including the joint (exposed conductor portion), with a liquid resin material, and then curing the liquid resin material to insulate the joint between the coil pieces with the resin material. In this type of manufacturing method, for a workpiece having joints on both axial sides, a technique has been proposed in which the joint end on one axial side of the workpiece is immersed in a bath of liquid resin material such as varnish, and then the workpiece is turned upside down and the joint end on the other axial side is immersed in the bath of liquid resin material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-070554 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-described conventional technology has a problem in that the liquid resin material is likely to splash when the workpiece is turned upside down, which may result in an insufficient thickness or coverage of the insulating coating covering the joints of the coil pieces.

[0005] Therefore, in one aspect, an object of the present disclosure is to reduce the amount of liquid resin material that splashes when a workpiece is turned upside down. [Means for solving the problem]

[0006] In one aspect, a mounting step of mounting a plurality of conductor pieces that form a stator coil on a stator core to form a workpiece; a joining step of joining tip portions of one of the conductor pieces and another of the conductor pieces to each other at one axial end side of the workpiece after the mounting step; an impregnation step of impregnating a liquid resin material into an impregnation target portion including a joint portion between the tip portions of the workpiece after the joining step; and a vertical inversion step of inverting the posture of the workpiece vertically after the impregnation step, The method for manufacturing a stator for a rotating electric machine includes rotating the workpiece around a rotation axis that extends toward the one axial end side of the axial center of the stator core. [Effects of the Invention]

[0007] According to one aspect of the present disclosure, it is possible to reduce the amount of liquid resin material that splashes when a workpiece is turned upside down. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic flowchart illustrating an example of a method for manufacturing a stator for a rotating electric machine. [Figure 2] FIG. 2 is a diagram schematically illustrating an entire workpiece for forming a stator for a rotating electric machine. [Figure 3] 10 is a cross-sectional view taken along the axial direction of the workpiece in a state in which coil pieces are assembled to a stator core. FIG. [Figure 4] FIG. [Figure 5] FIG. 2 is a schematic cross-sectional view of a coil piece. [Figure 6] FIG. 3 is an explanatory diagram of a joint, corresponding to an enlarged view of part Q1 in FIG. 2. [Figure 7] FIG. 2 is a diagram schematically illustrating a side view of a workpiece before it is immersed in a tank of liquid resin material. [Figure 8] FIG. 2 is a diagram schematically illustrating a side view of a workpiece immersed in a tank of liquid resin material. [Figure 9] FIG. 10 is a diagram schematically illustrating the state of the workpiece in a lifting process as viewed from the side. [Figure 10] 10 is a side view schematically illustrating a state of a workpiece undergoing an outer diameter side resin hardening process in an outer diameter side resin hardening step. FIG. [Figure 11] 10 is a side view schematically illustrating the workpiece in an upward orientation in a top-down inversion process after the outer diameter side resin hardening treatment. FIG. [Figure 12] FIG. 10 is an explanatory diagram of a preferred rotation axis when turning the workpiece upside down. [Figure 12A] FIG. 10 is an explanatory diagram of a rotation shaft according to a comparative example. [Figure 13] 10 is a side view schematically illustrating a state of a workpiece undergoing an upper surface resin curing process in an upper surface resin curing step. FIG. [Figure 14] 10 is a side view schematically illustrating a state of a workpiece undergoing an inner diameter side resin hardening process in an inner diameter side resin hardening step. FIG. [Figure 15] FIG. 10 is a side view schematically illustrating the state of the workpiece in a downward position immediately before being subjected to the second immersion step. [Figure 16] FIG. 10 is a diagram schematically showing the workpiece in an upward position after the second insulating coating process is completed. [Figure 17] FIG. 10 is a diagram schematically illustrating the state of the workpiece in a heating step as viewed from the side. [Figure 18] FIG. 10 is an explanatory diagram of the effect of the heating process. [Figure 19] FIG. 2 is a diagram schematically illustrating an example of a cooling structure. DETAILED DESCRIPTION OF THE INVENTION

[0009] Each embodiment will be described in detail below with reference to the accompanying drawings. Note that the dimensional ratios in the drawings are merely examples and are not intended to limit the scope of the invention. In addition, shapes and the like in the drawings may be partially exaggerated for the sake of explanation.

[0010] The manufacturing method of a stator for a rotating electric machine described below can be applied to any stator for a rotating electric machine as long as the stator has a joint portion of the coil pieces at the coil end portion. As a suitable application example, the manufacturing method of a stator for a rotating electric machine that can function as a power source that generates a propulsive force for a vehicle will be described below.

[0011] FIG. 1 is a schematic flowchart illustrating an example of a method for manufacturing a stator for a rotating electric machine. Note that FIG. 1 is a flowchart illustrating a schematic flow, and additional processes may be included at any stage. FIGS. 2 to 6 are explanatory diagrams of a workpiece W. FIG. 2 is a schematic diagram illustrating the entire workpiece W including a stator core 112 and a stator coil 114 for forming a stator 10 for a rotating electric machine. FIG. 3 is a cross-sectional view along the axial direction of the workpiece W in a state in which coil pieces 52 are assembled to the stator core 112. FIG. 4 is a front view of one of the coil pieces 52. FIG. 5 is a schematic cross-sectional view of the coil piece 52. FIG. 6 is an explanatory diagram of a joint 400, corresponding to an enlarged view of portion Q1 in FIG. 2. FIGS. 7 to 18 are explanatory diagrams of this manufacturing method, and FIGS. 7 to 11 and 13 to 18 are schematic side views illustrating the state of the workpiece W at each process. FIG. 12 is an explanatory diagram of a preferred rotation axis I1 when turning the workpiece W upside down. Fig. 12 schematically shows a workpiece gripping section 1000 that is part of the manufacturing apparatus. Fig. 12A is an explanatory diagram of a rotation axis I2 according to a comparative example.

[0012] The Z direction is shown in Figure 2 and other figures. The Z direction corresponds to the up-down direction, with the Z1 side and Z2 side corresponding to the upper side and lower side, respectively. The Y direction is shown in Figure 3 and other figures. The Y direction corresponds to the radial direction, with the Y1 side corresponding to the radially outer side and the Y2 side corresponding to the radially inner side (the side closer to the central axis I of the stator core 112).

[0013] In the following description, unless otherwise specified, the 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 the radial direction refers to the radial direction centered on the central axis I. Therefore, the radially outer side refers to the side away from the central axis I, and the radially inner side refers to the side closer to the central axis I. Furthermore, the axially outer side refers to the side away from the axial center of the stator core 112, and the axially inner side refers to the side closer to the axial center of the stator core 112. Furthermore, the circumferential direction corresponds to the direction of rotation around the central axis I.

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

[0015] Here, the stator coils 114 include 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 coil to form a neutral point. In other words, the stator coils 114 are star-connected. However, the connection mode of the stator coils 114 may be changed as appropriate depending on the required motor characteristics, etc. For example, the stator coils 114 may be delta-connected instead of star-connected.

[0016] Each phase coil of the stator coil 114 is formed by connecting multiple coil pieces 52. The coil pieces 52 are in the form of segment coils (segment conductors) obtained by dividing the phase coil into units that are easy to assemble (for example, units that can be inserted into two slots 23). As shown in FIG. 5, the coil pieces 52 are formed by coating a linear conductor (rectangular wire) 120 having a substantially rectangular cross section with an insulating film 130. Here, the linear conductor is formed of copper, as an example. However, in modified examples, the linear conductor may be formed of other conductive materials such as iron. Furthermore, the cross-sectional shape of the linear conductor may be other than rectangular.

[0017] In the example shown in Fig. 4, one coil piece 52 may be formed into a substantially U-shape having a pair of linear slot-receiving portions 50 and a bridge portion 54 connecting the pair of slot-receiving portions 50. The bridge portion 54 on the other axial side (upper side in Fig. 4) may be formed by circumferentially molding the state shown in Fig. 4. A joint portion 40 is set at the end of the bridge portion 54 on the other axial side (upper side in Fig. 4) to be joined to a joint portion 40 of a bridge portion 54 of another coil piece 52. The joint portion 40 is a portion where the insulating film 130 has been removed (i.e., a portion where the conductor portion related to the linear conductor is exposed).

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

[0019] 4 are inserted into each slot 23 in a radially aligned arrangement. Accordingly, a plurality of circumferentially extending transition portions 54 are aligned radially at both axial ends of the stator core 112. The transition portions 54 (and the connecting portions 40 that are part of them) form coil end portions 114A that protrude axially outward from the axial end faces of the stator core 112.

[0020] The coil pieces 52 may be wound around the stator core 112 in a lap winding manner, for example. In the example shown in Fig. 4, the lower transition portions 54 may have offset portions 521B that are offset from each other by one layer in the radial direction. The upper transition portions 54 may also have similar offset portions 521A.

[0021] 2 to 5 show the stator core 112 and the stator coil 114 having a specific structure, the structure of the stator core 112 and the stator coil 114 is arbitrary as long as the stator coil 114 has the joint portion 40. The winding method of the stator coil 114 is also arbitrary, and may be a winding method other than the lap winding described above, such as a wave winding method.

[0022] Next, this manufacturing method includes a joining process (step S202) of joining the joint portions 40, which are the tip portions of one coil piece 52 and another coil piece 52, at one axial end of the workpiece W. The joint portions 40 may be overlapped with each other, and the opposing sides may be joined. Any method may be used to join the joint portions 40, for example, welding. In this case, welding may be achieved by any method, such as laser welding or TIG welding. FIG. 6 schematically shows a joint portion 400 including a welded portion 401 (joining portion) formed on two joint portions 40 overlapped in the radial direction.

[0023] For example, when four or more coil pieces 52 are mounted in each slot 23 of the stator core 112 in a radially overlapping manner, the joining process may join multiple pairs of adjacent joining portions 40 (tip ends) in the radial direction together.

[0024] The joining range of the joining portions 40 and the orientation of the joining portions 40 when joined (the orientation when overlapping) are arbitrary. For example, in Fig. 6, the joining portions 40 are vertically upright and overlapped in the radial direction, but they may be overlapped in an X-shaped crossing when viewed in the radial direction, or only the joining portions 40 may be overlapped in the radial direction in an oblique orientation. Furthermore, the joining portions 40 may be overlapped in the axial direction in an orientation extending in the radial direction.

[0025] In the joining process, not only the coil pieces 52 are joined to each other, but also the coil pieces 52 may be joined to a bus bar or a terminal block (an output bus bar for connection to an inverter, not shown). Fig. 2 shows a schematic diagram of a neutral point bus bar 59 as an example of such a bus bar. The neutral point bus bar 59 is a bus bar that forms the neutral point described above.

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

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

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

[0029] Next, this manufacturing method includes an immersion process (an example of an impregnation process) (step S208) in which the workpiece W is immersed in a tank 600 of liquid resin material M0. FIG. 7 is a schematic side view of the workpiece W before being immersed in the tank 600 of liquid resin material M0, and FIG. 8 is a schematic side view of the workpiece W 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 being hardened by a polymerization reaction when irradiated with ultraviolet light. Note that the tank 600 may have a circular shape in top view corresponding to the circular impregnation target portion.

[0030] The immersion process is performed while the workpiece W is maintained in a downward orientation, so that the axial end (the lower end in the downward orientation) of the workpiece W to be impregnated is immersed in the liquid resin material M0 (i.e., positioned below the liquid surface of the liquid resin material M0). The impregnation target portions of the workpiece W are set at the portions of the multiple coil pieces 52 of the workpiece W. Specifically, the impregnation target portions of the workpiece W are the axial end portions (lead-side end portions) of the multiple coil pieces 52, and include the joint portions 400. More specifically, the impregnation target portions of the workpiece W include the portions of each coil piece 52 of the workpiece W where the conductors (conductor portions related to the linear conductors) are exposed (portions including the joint portions 400). The impregnation target portions have an annular shape around the central axis I when viewed in the axial direction, and include a portion of the coil end portion 114A (a portion on the axial end side).

[0031] In this embodiment, as will be described later, the immersion process is performed twice for one workpiece W. In this case, the portions of the workpiece W to be impregnated in each immersion process may be completely the same, or may be partially different, as will be described later.

[0032] In the immersion step, 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 having a hand for gripping the workpiece W).

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

[0034] Next, this manufacturing method includes an outer diameter side resin curing step (step S212) in which a resin curing process of the liquid resin material M0 is performed on the side surface of the portion to be impregnated of the workpiece W in a downward orientation that has been pulled up from the tank 600. Hereinafter, 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" to distinguish it from the resin curing process performed in the upper surface resin curing step (step S216) described later.

[0035] In this embodiment, the outer diameter side resin curing process includes irradiating ultraviolet rays onto the side surface of the portion of the workpiece W to be impregnated. FIG. 9 schematically shows the state in which the outer diameter side resin curing process is being performed. Also, in FIG. 9 (as well as FIG. 10, etc., described later), the liquid resin material M0 impregnated into the workpiece W is schematically shown by a hatched area M1. In the example shown in FIG. 10, the ultraviolet irradiation device 900 irradiates ultraviolet rays onto the radially outer side surface of the portion of the workpiece W to be impregnated (see arrow R10). This hardens the radially outer portion (mainly the surface portion) of the liquid resin material M0 impregnated into the portion of the workpiece W to be impregnated.

[0036] The ultraviolet irradiation device 900 preferably irradiates ultraviolet rays onto the radially outer side surface of the portion of the workpiece W to be impregnated, all around the circumference. This allows the liquid resin material M0 in the radially outer portion to be cured all around the entire circumference of the portion to be impregnated. In this case, the workpiece W may be rotated around the central axis I, or the ultraviolet irradiation device 900 may be rotated. Alternatively, multiple ultraviolet irradiation devices 900 may be arranged circumferentially and dispersed around the radially outer side of the workpiece W.

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

[0038] In this manner, according to this embodiment, the radially outer portion of the liquid resin material M0 impregnated into the impregnation target portion of the workpiece W is cured while the workpiece W is maintained in the downward orientation after being lifted from the tank 600. This reduces the inconvenience that may occur when the workpiece W is inverted upside down without undergoing the outer diameter side resin curing process after being lifted from the tank 600. Specifically, if the workpiece W is inverted upside down in the next inversion step (step S214) without undergoing the outer diameter side resin curing process, the liquid resin material M0 impregnated into the impregnation target portion of the workpiece W is likely to drip downward due to its own weight (see arrow R11 in FIG. 11 ). In this case, the exposed area (area not covered by the resin material) of the side surface of the coil end portion 114A may be unnecessarily narrow. If the exposed area of ​​the side surface of the coil end portion 114A is insufficient, the cooling efficiency may be reduced when a refrigerant (e.g., oil) is supplied to the side surface of the coil end portion 114A during operation of the rotating electrical machine (as will be described later with reference to FIG. 19 ). Furthermore, if the liquid resin material M0 on the radially outer side surface of the impregnation target portion 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 using a scraper or the like. In contrast, according to this embodiment, as described above, such inconvenience can be reduced.

[0039] Next, this manufacturing method includes an upside-down inversion step (step S214) in which the orientation of the workpiece W is inverted upside down. That is, the workpiece W is inverted upside down from a downward orientation to an upward orientation. Fig. 11 schematically shows the workpiece W inverted upside down to an upward orientation.

[0040] However, when the workpiece W is inverted upside down while impregnated with the liquid resin material M0, centrifugal force can easily cause the liquid resin material M0 to scatter. If the liquid resin material M0 scatters, the material may be wasted, and the thickness or 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 the centrifugal force, the time required for the upside-down process increases, which tends to increase the cycle time (CT).

[0041] Therefore, in this embodiment, the workpiece W is preferably rotated around a rotation axis I1 in a horizontal plane passing through the target impregnation area, as shown by the arrow R12 in FIG. 12, thereby flipping the workpiece W upside down from a downward position to an upward position. That is, the workpiece gripping unit 1000 flips the workpiece W upside down so that the workpiece W rotates around the rotation axis I1 in a horizontal plane passing through the target impregnation area. This effectively reduces the distance from the rotation axis I1 to the target impregnation area (the radius that affects the centrifugal force). Even when the workpiece W is flipped at a relatively high rotation speed, the centrifugal force does not become excessive (for example, centrifugal force that would cause the liquid resin material M0 to splash is not generated). In this way, splashing of the liquid resin material M0 from the workpiece W and an increase in CT can be prevented.

[0042] Here, while the workpiece W is being turned upside down, the rotation axis I1 may be fixed or may be moved in a translational manner. For example, the rotation axis I1 may be moved upward while rotating the workpiece W. This allows the workpiece W to be turned upside down while being moved to the next process in a manner that prevents the liquid resin material M0 from scattering. Note that this type of operation is suitable when the workpiece gripping unit 1000 is attached to the hand of an articulated robot.

[0043] The rotation axis I1 may be fixed in a constant positional relationship with respect to the workpiece W to be inverted during the inversion operation, or the positional relationship with respect to the workpiece W may change only for a portion of the inversion operation. For example, when 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 portion to be impregnated only for a portion of the inversion operation, such as the final stage of the inversion operation.

[0044] Furthermore, the rotation axis I1 preferably passes through the impregnation target portion as described above so as to reduce the radius associated with the centrifugal force, but this 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 a reference radius, significant effects can be obtained if the rotation radius of the impregnation target portion around the rotation axis I1 is equal to or less than 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 portion. Even in this case, the radius associated with the centrifugal force (the rotation radius of the impregnation target portion around the rotation axis) is smaller than in the comparative example (see FIG. 12A) having a rotation axis I2 positioned on the opposite side of the impregnation target portion and outside the workpiece W, so the above-mentioned effects can still be obtained. Note that in the comparative example shown in FIG. 12A, the workpiece W held by the loader hand 1200 is rotated around the rotation axis I2 positioned on the opposite side of the impregnation target portion and outside the workpiece W. In this case, the radius r2 of the centrifugal force (the radius of rotation of the part to be impregnated around the rotation axis I2) becomes relatively large (at least equal to or greater than the axial length of the stator core 112), which makes it easy for the above-mentioned problems to occur, such as the liquid resin material M0 scattering.

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

[0046] In this embodiment, the upper surface resin curing process includes irradiating the upper surface of the portion of the workpiece W to be impregnated with ultraviolet rays. FIG. 13 schematically shows a state in which the upper surface resin curing process is being performed. In the example shown in FIG. 13, the ultraviolet irradiation device 900 irradiates the upper surface of the portion of the workpiece W to be impregnated with ultraviolet rays (see arrow R13). This hardens the upper portion (mainly the upper surface portion) of the liquid resin material M0 that has impregnated the portion of the workpiece W to be impregnated. 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 process described above, or may be a different device.

[0047] The ultraviolet irradiation device 900 preferably irradiates ultraviolet rays over the entire circumference of the upper surface of the portion to be impregnated of the workpiece W. This allows the liquid resin material M0 in the upper portion to be cured over the entire circumference of the portion to be impregnated. In this case, the workpiece W may be rotated about the central axis I, or the ultraviolet irradiation device 900 may be rotated. Alternatively, multiple ultraviolet irradiation devices 900 may be arranged circumferentially above the workpiece W.

[0048] The ultraviolet irradiation device 900 is preferably positioned with respect to the workpiece W so that the optical axis 901 is approximately perpendicular to the upper surface of the portion of the workpiece W to be impregnated. That is, the ultraviolet irradiation device 900 is preferably positioned with respect to the workpiece W so that the optical axis 901 is located in an approximately vertical plane. Here, "approximately" is a concept that includes an error of, for example, 10% or less. The ultraviolet irradiation device 900 is preferably positioned with respect to the workpiece W so that the optical axis 901 passes through the portion of the workpiece W to be impregnated, and more preferably, is positioned with respect to the workpiece W so that 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 portion of the workpiece W to be impregnated. In this case, the liquid resin material M0 in the upper portion of the portion of the workpiece W to be impregnated can be efficiently cured.

[0049] In this manner, 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 impregnation target portion is cured. Therefore, it is possible to reduce the inconvenience that may occur when the top-surface resin curing process is performed on the workpiece W while it is in a downward position after being lifted from the tank 600 (i.e., when the top-surface resin curing process is performed simultaneously with the outer diameter side resin curing process described above). Specifically, if the resin curing process is performed on the underside of the impregnation target portion of the workpiece W while it is in a downward position after being lifted from the tank 600, the liquid resin material M0 impregnated into the impregnation target portion of the workpiece W may harden while dripping downward due to its own weight. In other words, the liquid resin material M0 may harden into an icicle-like shape. In contrast, according to this embodiment, the top-surface resin curing process is performed in an upward position as described above, thereby reducing such inconvenience.

[0050] Furthermore, according to this embodiment, by curing the upper portion (axial end) of the liquid resin material M0 impregnated into the impregnation target portion, 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 FIG. 5 , hereinafter referred to as the “joint edge 122”). That is, even on the joint edge 122, where the liquid resin material M0 is difficult to form due to the influence of the wettability around the coil pieces 52, a relatively thin film of the liquid resin material M0 can be formed. The joint edge 122 on which such a film of the liquid resin material M0 is formed has high wettability due to the film. In this way, the wettability (wettability of the liquid resin material M0) of the joint edge 122 can be improved. As a result, in the subsequent second dipping process (described below), it becomes easier to ensure the required thickness of the insulating coating (cured liquid resin material M0) on the joint edge 122 of the coil pieces 52. That is, in the second dipping step, a relatively thick film can be formed on the joint edge 122 using the film of liquid resin material M0 formed in the first dipping step as a base. This point will be explained again when explaining the second dipping step.

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

[0052] In this embodiment, the inner diameter side resin curing process includes irradiating ultraviolet rays onto the radially inner side surface of the portion of the workpiece W to be impregnated. FIG. 14 schematically shows a state in which the inner diameter side resin curing process is being performed. In the example shown in FIG. 14, the ultraviolet irradiation device 900 irradiates ultraviolet rays onto the radially inner side surface of the portion of the workpiece W to be impregnated (see arrow R14). This hardens the radially inner portion (mainly the surface portion) of the liquid resin material M0 that has impregnated the portion of the workpiece W to be impregnated. Note that the ultraviolet irradiation device 900 may be the same as the ultraviolet irradiation device 900 used in the above-mentioned upper surface resin curing process.

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

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

[0055] However, depending on the size of the ultraviolet irradiation device 900 and the space radially inside the workpiece W, the ultraviolet irradiation device 900 may be positioned relative to the workpiece W such that the optical axis 901 intersects obliquely with the radially inside side surface of the portion to be impregnated of the workpiece W, as shown in Fig. 14. In this case, one of the inner diameter side resin curing treatment and the upper surface resin curing treatment may serve as the other.

[0056] When the inner diameter side resin hardening step (step S218) by the inner diameter side resin hardening treatment is completed, the insulation coating step for that time is completed.

[0057] Next, in this manufacturing method, it is determined whether the insulation coating process has been performed on one workpiece W a predetermined number of times (in this embodiment, for example, twice) (step S220). This determination may be performed manually or by image processing, etc. If the determination result is "YES," the process proceeds to the next step; otherwise, steps S206 to S218 are similarly performed to perform the second insulation coating process. FIG. 15 schematically shows the workpiece W that has been turned upside down in step S206 and placed in a downward position in the second insulation coating process. Thereafter, the workpiece W undergoes a second immersion process, etc.

[0058] The second insulating coating process may be exactly the same as the first insulating coating process, which can simplify the control of the manufacturing equipment, for example.

[0059] However, the second insulating coating process preferably differs from the first insulating coating process in at least the dipping step. Specifically, the dipping step in the second insulating coating process reduces the area to be impregnated compared to the dipping step in the first insulating coating process. That is, the area to be impregnated in the second dipping process may be a portion (a portion on the axial end side) of the area to be impregnated in the first dipping process. In this case, the area to be impregnated in the second dipping process may be a minimum area including the joint edge 122 of the coil piece 52. This allows an insulating coating (a cured product of the liquid resin material M0) having the required functions to be efficiently formed using a relatively small amount (e.g., a minimum) of the liquid resin material M0.

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

[0061] In this manner, in this embodiment, the insulating coating process is performed multiple times (for example, twice in this embodiment), thereby ensuring the necessary thickness of the insulating coating (cured product of the liquid resin material M0) on the joint edges 122 of the coil pieces 52.

[0062] Specifically, Fig. 16 schematically shows the workpiece W in an upward position after the second insulation coating process has been completed. In Fig. 16, the range of the liquid resin material M0 formed in the first insulation coating process (hatched area M1) and the range of the liquid resin material M0 formed in the second insulation coating process are schematically shown by hatched area M2. Note that, for convenience of explanation, Fig. 16 (as well as Fig. 18, etc., described later) schematically shows only the axial end of the coil end portion 114A of the stator coil 114 without omission.

[0063] In the first insulating coating process, as shown by the hatched area M1, a thin film of the liquid resin material M0 can be formed on the joint edge 122 of the coil piece 52. In this case, the thickness of the thin film of the 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 (the wettability of the corners of the linear conductor) is low. However, even if the thin film of the 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 dipping step in the second insulating coating process, the liquid resin material M0 on the joint edge 122 is more likely to adhere. That is, in the second insulating coating process, as shown by the hatched area M2, a further film of the liquid resin material M0 can be formed with a relatively large thickness on the joint edge 122 of the coil piece 52. In this way, it is possible to ensure the necessary thickness of the insulating coating (cured product of the liquid resin material M0) even for the joint edges 122 of the coil pieces 52, which have low wettability.

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

[0065] The posture of the workpiece W during the heating process is arbitrary, but is preferably a downward posture as shown schematically in FIG. 17. Note that FIG. 17 also shows a state in which a plurality of workpieces W are arranged side by side in a downward posture and undergo a heating process. Note that FIG. 17 also shows a state in which a workpiece gripping unit 1001, which is part of the manufacturing apparatus, clamps a plurality of workpieces W, but the workpieces W may also be supported on a table in such a manner that the end face of the stator core 112 abuts against the upper surface (not shown) of the table. Also, in FIG. 17, as an example, heat is radiated from below the workpiece W (see arrow R17), but the direction of heat radiation is arbitrary.

[0066] During the heating process, when the stator core 112 is in an upward position, the liquid resin material M0 that is in the process of hardening before it is completely hardened may drip downward onto the stator core 112 due to its own weight (see arrow R16 in FIG. 16). In this case, the liquid resin material M0 that has adhered to the stator core 112 must be removed separately using a scraper or the like.

[0067] In contrast, in the downward position, even if the liquid resin material M0 that is still in the process of hardening moves downward under its own weight before it is completely hardened, it will not reach the stator core 112. Furthermore, the portions of the liquid resin material M0 that have hardened during the outer diameter side resin hardening process, the upper surface resin hardening process, and the inner diameter side resin hardening process (see the C-shaped area 1800 in Figure 18 ) function as a "bottom lid," thereby reducing the possibility of the dripping liquid resin material M0 becoming icicle-like. In Figure 18 , the downward movement of the liquid resin material M0 that is still in the process of hardening is shown, as schematically indicated by arrow R19. This downward movement of the liquid resin material M0 that is still in the process of hardening is blocked by the portions of the liquid resin material M0 that have hardened during the outer diameter side resin hardening process, the upper surface resin hardening process, and the inner diameter side resin hardening process. This prevents problems that may occur when the heating process is performed in the downward position.

[0068] In this way, according to this embodiment, by performing the heating process in a downward position, dripping of the liquid resin material M0 onto the stator core 112 is prevented, and the "bottom lid" function of the portions of the liquid resin material M0 that have hardened in the outer diameter side resin hardening process, the upper surface resin hardening process, and the inner diameter side resin hardening process can reduce the liquid resin material M0 from hardening in an icicle-like manner dripping downward.

[0069] In order to effectively enhance this "bottom cover" function, it is desirable to perform all of the outer diameter side resin hardening process, the upper surface resin hardening process, and the inner diameter side resin hardening process, but it is also possible to omit only the outer diameter side resin hardening process and / or the inner diameter side resin hardening process.

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

[0071] Furthermore, when a heating step is performed after each insulating coating step, a discontinuous boundary (layer separation) is formed between the insulating coating of liquid resin material M0 formed the first time and the insulating coating of liquid resin material M0 formed the second time, but this manufacturing method eliminates this boundary and increases the strength of the insulating coating of liquid resin material M0 as a whole. That is, with this manufacturing method, the viscosity of the liquid resin material M0 impregnated twice decreases during the heating step and it becomes a single layer, so there is no discontinuous boundary (layer separation) within the insulating coating and strength is improved.

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

[0073] FIG. 19 is a diagram schematically showing an example of a cooling structure, and is a diagram schematically showing a part of the cross-sectional structure of a rotating electrical machine 1.

[0074] 19, oil is supplied from the radially outer and radially inner sides to coil end portions 114A at both axial ends of stator coil 114. Specifically, oil supplied to intra-case oil passage 60 of case 2 (see arrow R20A) is supplied to the radially outer side surface of coil end portion 114A via oil hole 62 penetrating radially inward (see arrow R20). Note that oil hole 62 may be positioned vertically upward to promote dripping of oil by gravity. Furthermore, oil supplied to axial center oil passage 64 of rotor shaft 112A (see arrow R21A) is supplied to the radially inner side surface of coil end portion 114A via oil hole 66 penetrating radially outward (see arrow R21).

[0075] According to this manufacturing method, as described above, the coil end portions 114A of the stator coil 114 are coated with an insulating coating of liquid resin material M0. The portions of the stator coil 114 coated with the insulating coating of liquid resin material M0 have lower thermal conductivity than the portions of the stator coil 114 that are not (i.e., the portions where the insulating film 130 is the surface). Therefore, if the exposed area of ​​the radially outer side surface of the coil end portions 114A that is not covered with the insulating coating of liquid resin material M0 becomes unnecessarily narrow, the cooling performance of the 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 portions 114A that is not covered with the insulating coating of liquid resin material M0 becomes unnecessarily narrow, the cooling performance of the oil from the oil holes 66 described above may be unnecessarily 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 portion during the outer diameter side resin curing process is cured while facing downward. Therefore, even if the workpiece W is then turned upward, the radially outer liquid resin material M0 will not drip 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 be unnecessarily narrowed. As a result, the cooling performance of the coil end portion 114A by the oil from the oil hole 62 described above can be effectively improved.

[0077] In the above-described embodiment, the inner diameter side resin curing process is performed on the workpiece W in an upward orientation. However, similar to the outer diameter side resin curing process, it may also be performed on the workpiece W in a downward orientation. In this case, the inner diameter side resin curing process and the outer diameter side resin curing process may be performed simultaneously in parallel. In this case, the radially inner portion of the liquid resin material M0 impregnated into the impregnation target portion during the inner diameter side resin curing process is cured while remaining in a downward orientation. Therefore, even if the workpiece W is then in an upward orientation, the liquid resin material M0 on the radially inner side does not drip downward. This reduces the possibility of unnecessary narrowing of 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. As a result, the cooling performance of the coil end portion 114A by the oil from the oil hole 66 described above can be effectively improved.

[0078] Although each embodiment has been described in detail above, it is not limited to the specific embodiment, and various modifications and changes are possible within the scope of the claims. It is also possible to combine all or a plurality of components of the above-described embodiments.

[0079] For example, in the above-described embodiment, the outer diameter side resin hardening process is preferably performed, but the inner diameter side resin hardening process may be performed instead of the outer diameter side resin hardening process.

[0080] Furthermore, in the above-described embodiment, an immersion process is performed in which the workpiece W is immersed in a tank 600 of liquid resin material M0, but instead of or in addition to this, a process (an example of an impregnation process) may be performed in which the liquid resin material M0 is dripped onto the portion of the workpiece W to be impregnated, thereby impregnating the portion of the workpiece W to be impregnated with the liquid resin material M0. [Explanation of symbols]

[0081] 40 ··· Joint portion (tip portion), 52 ··· Coil piece, 112 ··· Stator core, 114 ··· Stator coil, 600 ··· Tank, W ··· Workpiece, M0 ··· Liquid resin material, I2 ··· Rotating shaft

Claims

1. a mounting step of mounting a plurality of conductor pieces that form a stator coil on a stator core to form a workpiece; a joining step of joining tip portions of one of the conductor pieces and another of the conductor pieces to each other at one axial end side of the workpiece after the mounting step; an impregnation step of impregnating a liquid resin material into an impregnation target portion including a joint portion between the tip portions of the workpiece after the joining step; and a vertical inversion step of inverting the posture of the workpiece vertically after the impregnation step, The method for manufacturing a stator for a rotating electric machine, wherein the upside-down turning step includes rotating the workpiece around a rotation axis that extends toward the one axial end side of the axial center of the stator core.

2. 2. The method for manufacturing a stator for a rotating electric machine according to claim 1, wherein the rotation axis overlaps the impregnation target portion when viewed in a radial direction of the stator core.

3. 3. The method for manufacturing a stator for a rotating electric machine according to claim 1, wherein the upside-down turning step includes rotating the workpiece while translating the rotation shaft.

4. the impregnation step includes a dipping step of dipping the workpiece in a tank of the liquid resin material in a downward position where the portion to be impregnated faces downward, 4. The manufacturing method of a stator for a rotating electric machine according to claim 1, wherein the upside-down inversion step is performed to invert the workpiece upside-down into an upward position in which the portion to be impregnated faces upward.

5. a gripping unit that grips a workpiece formed by attaching a plurality of conductor pieces that form a stator coil to a stator core; a rotation mechanism that rotates the gripping unit around a rotation axis so that the posture of the workpiece gripped by the gripping unit is inverted upside down, The manufacturing apparatus for a stator for a rotating electric machine, wherein the rotating shaft extends toward one axial end of the stator core relative to the axial center of the stator core when the workpiece is gripped by the gripping portion.

6. the rotating mechanism rotates the workpiece in which the liquid resin material has been impregnated into the impregnation target portion including the joint portion between the plurality of conductor pieces; 6. The manufacturing apparatus for a stator for a rotating electric machine according to claim 5, wherein the rotation axis overlaps the impregnation target portion when viewed in a radial direction of the stator core.

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