Method for manufacturing stator for rotary electric machine

Abstract

To appropriately ensure the thickness of liquid resin material at the corner of a joint part without reducing material selectivity of the liquid resin material.SOLUTION: A method for manufacturing a stator for a rotary electric machine is disclosed including: a mounting step of mounting a plurality of coil pieces for forming a stator coil on a stator core to form a workpiece; a joining step of, after the mounting step, on one end side in an axial direction of the workpiece, joining leading ends of one coil piece and the other coil piece to each other; a first impregnation step of, after the joining step, impregnating an impregnation target portion including a joint portion of the leading ends in the workpiece, with liquid resin material; a first end face hardening step of, after the first impregnation step, performing resin hardening processing of the liquid resin material on an end face in an axial direction of the impregnation target portion; and a second impregnation step of, after the first end face hardening step, impregnating at least part of a side of the end face in the axial direction of the impregnation target portion, with the liquid resin material.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] A method for manufacturing a stator for a rotating electric machine is known, which comprises 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 together at one axial end of the workpiece, impregnating a portion to be impregnated, including the joint (exposed conductor portion), with a liquid resin material, and then curing the liquid resin material to cover the joint with an insulating coating of the resin material. In this type of manufacturing method, a technique has been proposed in which the coil pieces are heated while the workpiece is immersed in a tank of the liquid resin material to gel the liquid resin material impregnated in the portion to be impregnated, so that the liquid resin material impregnated in the portion to be impregnated does not drip due to its own weight. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-165484 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional techniques described above, it is necessary to use a liquid resin material that gels when heated, which results in a problem of low material selectivity. If the liquid resin material does not gel in a desired manner, the liquid resin material applied to the joint will sag under its own weight, and the thickness of the liquid resin material will tend to be insufficient at the corners of the joint (corners on the axial end faces of the coil pieces).

[0005] Therefore, in one aspect, an object of the present disclosure is to ensure an appropriate thickness of liquid resin material at corners of a joint without reducing the material selectivity of the liquid resin material. [Means for solving the problem]

[0006] In one aspect, a mounting step of mounting a plurality of coil pieces forming a stator coil on a stator core to form a workpiece; a joining step of joining a tip end portion of one of the coil pieces and another of the coil pieces to each other at one axial end side of the workpiece after the mounting step; A first impregnation step of impregnating a liquid resin material into an impregnation target portion including a joint between the tip portions of the workpiece after the joining step; a first end surface hardening process for performing a resin hardening process on an axial end surface of the impregnation target portion after the first impregnation process; The method for manufacturing a stator for a rotating electric machine includes, after the first end face hardening step, a second impregnation step of impregnating at least a part of the axial end face side of the impregnation target portion with a liquid resin material. Effect of the Invention

[0007] According to one aspect, the present disclosure makes it possible to ensure an appropriate thickness of the liquid resin material at the corners of the joint without reducing the material selectivity of the liquid resin material. [Brief description of the drawings]

[0008] [Figure 1] 4 is a schematic flowchart showing an example of a method for manufacturing a stator for a rotating electric machine. [Diagram 2] FIG. 2 is a diagram showing a schematic view of an entire workpiece for forming a stator for a rotating electric machine; [Diagram 3] 4 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. [Diagram 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 6A]13 is an explanatory diagram of an overlapping state of a joint portion of a specific coil piece. FIG. [Figure 7] 1 is a schematic side view of a workpiece before it is immersed in a tank of liquid resin material; FIG. [Figure 8] 1 is a schematic side view of a workpiece immersed in a tank of liquid resin material; FIG. [Figure 9] 11 is a diagram showing a schematic side view of the state of the workpiece in the lifting process; FIG. [Figure 10] 11 is a schematic side view of a state of a workpiece undergoing an outer diameter side resin hardening process in an outer diameter side resin hardening step; FIG. [Figure 11] 13 is a schematic side view of the workpiece in an upward orientation in a top-down inversion process after the outer diameter side resin hardening treatment; FIG. [Figure 12] FIG. 11 is an explanatory diagram of a preferred rotation axis when turning the work upside down. [Figure 12A] FIG. 13 is an explanatory diagram of a rotating shaft according to a comparative example. [Figure 13] 13 is a schematic side view of a state of a workpiece undergoing an upper surface resin hardening process in an upper surface resin hardening step; FIG. [Figure 14] 11 is a schematic side view of a state of a workpiece undergoing an inner diameter side resin hardening process in an inner diameter side resin hardening step; FIG. [Figure 15] 1 is a schematic side view of the state of the workpiece in a downward position immediately before being subjected to a second immersion process. FIG. [Figure 15A] FIG. 13 is an illustration of the preferred immersion range for certain coil segment joints. [Figure 16] 13 is a diagram showing a schematic view of the workpiece in an upward position after the second insulating coating process is completed. FIG. [Figure 17] FIG. 11 is a diagram showing a schematic side view of the state of the workpiece in a heating process. [Figure 18] FIG. 13 is an explanatory diagram of the effect of a heating process. [Figure 19] FIG. 2 is a diagram illustrating an example of a cooling structure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 be limiting, and shapes and the like in the drawings may be partially exaggerated for the sake of explanation. 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. In the following, as a suitable application example, a 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.

[0010] FIG. 1 is a schematic flow chart showing an example of a method for manufacturing a stator for a rotating electric machine. Note that FIG. 1 is a flow chart showing a schematic flow, and may include additional steps at any stage. FIGS. 2 to 6 are explanatory diagrams of a workpiece W. FIG. 2 is a diagram showing a schematic overall view of a workpiece W for forming a stator 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 the coil pieces 52 are assembled to the stator core 112. FIG. 4 is a front view of one of the coil pieces 52 among the multiple 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, and corresponds to an enlarged view of the Q1 portion in FIG. 2. FIG. 6A is an explanatory diagram of an overlapping mode of the joint portion 40 of a specific coil piece 52. FIGS. 7 to 18 are explanatory diagrams of this manufacturing method, and FIGS. 7 to 11 and FIGS. 13 to 18 are diagrams showing the state of the workpiece W in each step in a side view. Fig. 12 is an explanatory diagram of a preferable rotation axis I1 when turning the workpiece W upside down. Fig. 12 shows a schematic diagram of a workpiece gripping unit 1000 that is a part of the manufacturing apparatus. Fig. 12A is an explanatory diagram of a rotation axis I2 according to a comparative example.

[0011] The Z direction is shown in Fig. 2 and other figures. The Z direction corresponds to the up-down direction, with the Z1 side and the Z2 side corresponding to the upper side and the lower side, respectively. The Y direction is shown in Fig. 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).

[0012] In the following description, unless otherwise specified, the axial direction refers to the direction in which the central axis I of 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. Additionally, the axially outer side refers to the side away from the axial center of stator core 112, and the axially inner side refers to the side closer to the axial center of stator core 112. Additionally, the circumferential direction corresponds to the direction of rotation around the central axis I.

[0013] This manufacturing method first includes a mounting step (step S200) of mounting a plurality of coil pieces 52 that form the stator coil 114 on the stator core 112 to form an assembly (hereinafter also referred to as a "workpiece W").

[0014] 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 are 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 coil 114 is star-connected. However, the connection mode 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.

[0015] Each phase coil of the stator coil 114 is formed by connecting a plurality of 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 covering 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 a modified example, the linear conductor may be formed of another conductive material such as iron. The cross-sectional shape of the linear conductor may be other than rectangular.

[0016] 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-accommodated portions 50 and a transition portion 54 connecting the pair of slot-accommodated portions 50. The transition portion 54 on the other axial side (upper side in Fig. 4) may be formed by shaping in the circumferential direction from the state shown in Fig. 4. A joint portion 40 is set at an end of the transition portion 54 on the other axial side (upper side in Fig. 4) to be joined to a joint portion 40 of the transition 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).

[0017] When the coil pieces 52 are assembled to the stator core 112, the pair of slot housing 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.

[0018] 4 are inserted into each slot 23 in a radially aligned manner. Thus, a plurality of circumferentially extending transition portions 54 are aligned in the radial direction at both axial ends of the stator core 112. The transition portions 54 (and the joint portions 40 which are a part of the transition portions 54) form coil end portions 114A which are portions which protrude axially outward from the axial end faces of the stator core 112.

[0019] The coil pieces 52 may be wound around the stator core 112 in a lap winding manner. In the example shown in Fig. 4, the lower transition portion 54 may have an offset portion 521B that is offset from the other transition portion 521B by one layer in the radial direction. The upper transition portion 54 may also have a similar offset portion 521A.

[0020] 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 type described above, such as a wave winding type.

[0021] Next, this manufacturing method includes a joining process (step S202) of joining the joint portions 40, which are the respective tip portions of one coil piece 52 and another coil piece 52, at one axial end side of the workpiece W. The joint portions 40 may be overlapped and the opposing sides may be joined. Any method may be used to join the joint portions 40, for example, welding. In this case, the welding may be achieved by any method such as laser welding or TIG welding. FIG. 6 shows a joint portion 400 including a welded portion 401 (joint portion) formed on two joint portions 40 overlapped in the radial direction.

[0022] 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 in the radial direction, with two radially adjacent joining portions 40 (tips) being considered as one pair.

[0023] In addition, the joining range of the joint parts 40, the posture of the joint parts 40 when joining (the posture when overlapping) and the like are arbitrary. For example, in FIG. 6, the joint parts 40 are vertically upright and overlapped in the radial direction, but they may be overlapped in the axial direction in a posture extending in the radial direction. Alternatively, even when overlapped in the radial direction, various overlapping methods are possible. For example, the joint parts 40 may be overlapped in a manner crossing in an X-shape when viewed in the radial direction, or as shown in FIG. 6A, only the joint parts 40 may be overlapped in the radial direction in a diagonal posture. In the example shown in FIG. 6A, the joint part 40 has an arc-shaped outer portion 402 tapered toward the tip when viewed in the radial direction. In this case, the joining process may be realized by applying welding heat (for example, heat by laser irradiation) to the radial abutment surface 4021 of the arc-shaped outer portions 402 of the joint parts 40 of the coil pieces. In this case, the axial size of the lead-side coil end portion 114A can be reduced.

[0024] 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 above-mentioned neutral point.

[0025] In this embodiment, as an example, the joint portion 400 is provided on only one axial side of the stator core 112. In the following, for the sake of distinction, the side having the joint portion 400 among both axial sides of the stator core 112 (or both axial sides of the workpiece W) is also 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.

[0026] Next, in this manufacturing method, the work W is set at a start position (work carry-in position) for the insulation coating process (step S204). At this time, the work W may be set in a position in which the lead side is on the upper side (i.e., the joint 400 is on the upper side). Hereinafter, such a position in which the lead side is on the upper side is also referred to as the "upward position of the work W".

[0027] Next, this manufacturing method includes an upside-down step (step S206) of upside-down the attitude of the work W as the first step of the insulating coating step. That is, the work W is upside-down to an attitude in which the lead side is on the bottom (i.e., the joint 400 is on the bottom). Hereinafter, such an attitude in which the lead side is on the bottom is also referred to as the "downward attitude of the work W." Upside-down reversal of the attitude of the work W may be achieved by a manufacturing device (not shown, for example, an articulated robot having a hand that grasps the work W).

[0028] Next, the manufacturing method includes an immersion step (step S208) of immersing the workpiece W 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, as a preferred example, a resin material that has a property of being hardened by heating and a property of being hardened by a polymerization reaction when irradiated with ultraviolet light. The tank 600 may have a circular shape corresponding to the circular impregnation target portion when viewed from above.

[0029] The immersion step is performed so that the axial end (lower end in the downward orientation) of the workpiece W is immersed in the liquid resin material M0 (i.e., positioned below the liquid surface of the liquid resin material M0) while the workpiece W is maintained in a downward orientation. 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 (portions including the joint portions 400) of the coil pieces 52 of the workpiece W where the conductors (conductor portions related to the linear conductors) are exposed. The impregnation target portions are annular about the central axis I when viewed in the axial direction, and include a portion (a portion on the axial end side) of the coil end portions 114A.

[0030] In this embodiment, as 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 described later.

[0031] In the immersion step, the workpiece W may be maintained in an immersed state in a downward position for a certain period of time by a manufacturing device (not shown) (for example, an articulated robot having a hand that grasps the workpiece W).

[0032] 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 (e.g., an articulated robot having a hand for gripping the workpiece W) not shown. Fig. 9 shows the workpiece W in a downward position after being lifted. The workpiece W in the downward position after being lifted has a liquid resin material M0 (schematically shown by a hatched area M1 in Fig. 9) impregnated in the portion to be impregnated at the axial end (the lower end in the downward position) of the workpiece W.

[0033] Next, this manufacturing method includes an outer diameter side resin hardening process (step S212) in which a resin hardening 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 pulled up from the tank 600. Hereinafter, the resin hardening process performed in the outer diameter side resin hardening process (step S212) is also referred to as the "outer diameter side resin hardening process" to distinguish it from the resin hardening process performed in the upper surface resin hardening process (step S216) described later.

[0034] In this embodiment, the outer diameter side resin hardening process includes irradiating ultraviolet rays to the side surface of the portion of the workpiece W to be impregnated. FIG. 9 shows a schematic state in which the outer diameter side resin hardening process is being performed. FIG. 9 (as well as FIG. 10 and the like described later) also shows the liquid resin material M0 impregnated in the workpiece W by a hatched area M1. In the example shown in FIG. 10, the ultraviolet irradiating device 900 irradiates ultraviolet rays to the radially outer side surface of the portion of the workpiece W to be impregnated (see arrow R10). As a result, the radially outer portion (mainly the surface portion) of the liquid resin material M0 impregnated in the portion of the workpiece W to be impregnated is hardened.

[0035] The ultraviolet irradiation device 900 preferably irradiates ultraviolet rays to the entire circumference of the radially outer side surface of the portion to be impregnated of the workpiece W. This allows the liquid resin material M0 in the radially outer 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 disposed circumferentially distributed on the radially outer side of the workpiece W.

[0036] The ultraviolet irradiation device 900 is preferably positioned with respect to the workpiece W such that the optical axis 901 is approximately perpendicular to the radially outer side surface of the portion to be impregnated of the workpiece W. That is, the ultraviolet irradiation device 900 is preferably positioned with respect to the workpiece W such that the optical axis 901 is located in an approximately horizontal plane. Here, "approximately" is a concept including an error of, for example, 10% or less. The ultraviolet irradiation device 900 is preferably positioned with respect to the workpiece W such that the optical axis 901 passes through the portion to be impregnated of the workpiece W, and more preferably, is positioned with respect to the workpiece W such that the optical axis 901 passes near the axial center of the portion to be impregnated of the workpiece W. In this case, the liquid resin material M0 in the radially outer portion of the portion to be impregnated of the workpiece W can be efficiently cured.

[0037] In this way, according to this embodiment, the radially outer portion of the liquid resin material M0 impregnated in the impregnation target portion is hardened while the workpiece W is kept in the downward orientation after being pulled up from the tank 600. This reduces the inconvenience that may occur when the workpiece W pulled up from the tank 600 is turned upside down without undergoing the outer diameter side resin hardening process. That is, if the workpiece W pulled up from the tank 600 is turned upside down in the next upside-down turning step (step S214) without undergoing the outer diameter side resin hardening process, the liquid resin material M0 impregnated in 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, there is a risk that the exposed range (range not covered by the resin member) on the side surface of the coil end portion 114A may be unnecessarily narrowed. If the exposed range on the side surface of the coil end portion 114A is insufficient, there is a risk that the cooling efficiency may decrease when a coolant (e.g., oil) is supplied to the side surface of the coil end portion 114A during operation of the rotating electric machine (described later with reference to FIG. 19). Furthermore, if the liquid resin material M0 on the radially outer side surface of the portion to be impregnated 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.

[0038] Next, the present manufacturing method includes a top-down inversion step (step S214) for inverting the orientation of the workpiece W upside down. That is, the workpiece W is inverted upside down from a downward orientation to an upward orientation. Fig. 11 shows a schematic diagram of the workpiece W inverted upside down to an upward orientation.

[0039] However, when the workpiece W is in a state where it is impregnated with the liquid resin material M0, there is a problem that the liquid resin material M0 is likely to scatter due to centrifugal force when the workpiece W is turned upside down. 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 in order to reduce the centrifugal force, the time required for the upside-down turning process increases, and the cycle time (CT) tends to increase.

[0040] Therefore, in this embodiment, the workpiece W is preferably turned upside down from a downward posture to an upward posture by rotating it around a rotation axis I1 in a horizontal plane passing through the part to be impregnated, as shown diagrammatically by an arrow R12 in FIG. 12. That is, the workpiece gripping unit 1000 turns the workpiece W upside down so that the workpiece W rotates around the rotation axis I1 in a horizontal plane passing through the part to be impregnated. This makes it possible to efficiently reduce the distance from the rotation axis I1 to the part to be impregnated (the radius that affects the centrifugal force), and even when the workpiece W is turned over at a relatively high rotation speed, the centrifugal force does not become excessive (for example, no centrifugal force that would cause the liquid resin material M0 to scatter is generated). In this way, the liquid resin material M0 can be prevented from scattering from the workpiece W, and an increase in CT can be prevented.

[0041] 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 attitude of the workpiece W to be turned upside down while moving the workpiece W to the next process in a manner that makes it difficult for the liquid resin material M0 to scatter. This type of operation is suitable when the workpiece gripping part 1000 is attached to the hand of an articulated robot.

[0042] 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 during a portion of the inversion operation. For example, when the workpiece gripping part 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 during a portion of the inversion operation, such as the final stage.

[0043] In addition, the rotation axis I1 preferably passes through the impregnation target portion as described above so that the radius related to the centrifugal force is small, 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 set as a reference radius, a significant effect can be obtained if the rotation radius of the impregnation target portion around the rotation axis I1 is equal to or smaller 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 related to the centrifugal force (the rotation radius of the impregnation target portion around the rotation axis) is smaller than that of a comparative example (see FIG. 12A) having a rotation axis I2 located outside the work W on the opposite side to the impregnation target portion, so that the above-mentioned effect can still be obtained. In the comparative example shown in FIG. 12A, the work W held by the loader hand 1200 is rotated around the rotation axis I2 located outside the work W on the opposite side to the impregnation target portion. 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 such as the liquid resin material M0 scattering to occur.

[0044] Next, this manufacturing method includes an upper surface resin curing process (one example of a first or second end surface curing process) (step S216) in which a resin curing process of the liquid resin material M0 is performed 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 an "upper surface resin curing process" to distinguish it from the outer diameter side resin curing process described above.

[0045] In this embodiment, the upper surface resin hardening process includes irradiating the upper surface of the portion of the workpiece W to be impregnated with ultraviolet rays. FIG. 13 shows a schematic diagram of the state in which the upper surface resin hardening process is being performed. In the example shown in FIG. 13, the ultraviolet irradiating 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 been impregnated into the portion of the workpiece W to be impregnated. The ultraviolet irradiating device 900 may be the same as the ultraviolet irradiating device 900 used in the outer diameter side resin hardening process described above, or may be a different device.

[0046] 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 disposed circumferentially on the upper side of the workpiece W.

[0047] The ultraviolet irradiation device 900 is preferably positioned with respect to the workpiece W such 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 such that the optical axis 901 is located in an approximately vertical plane. Here, "approximately" is a concept including an error of, for example, 10% or less. The ultraviolet irradiation device 900 is preferably positioned with respect to the workpiece W such 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 such that the optical axis 901 passes near the center of the radial range (range from the innermost position to the outermost 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.

[0048] 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 in the impregnation target portion is hardened. Therefore, it is possible to reduce inconveniences that may occur when the upper surface resin hardening process is performed on the workpiece W pulled up from the tank 600 while it is in a downward position (i.e., when the upper surface resin hardening process is performed simultaneously with the outer diameter side resin hardening process described above). Specifically, when the resin hardening process is performed on the lower surface of the impregnation target portion of the workpiece W pulled up from the tank 600 while it is in a downward position, the liquid resin material M0 impregnated in the impregnation target portion of the workpiece W may harden while dripping downward due to its own weight. That is, the liquid resin material M0 may harden in an icicle shape. On the other hand, according to this embodiment, the upper surface resin hardening process is performed in an upward position as described above, so that such inconveniences can be reduced.

[0049] Moreover, according to this embodiment, by hardening the upper portion (axial end portion) of the liquid resin material M0 impregnated in the impregnation target portion, a thin film of the liquid resin material M0 can be formed on the corner portion of the rectangular cross section of the joint portion 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 piece 52, a film of the liquid resin material M0 can be formed, although it is relatively thin. 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 immersion process (described later), the required thickness of the insulating coating (cured product of the liquid resin material M0) on the joint edge 122 of the coil piece 52 can be easily ensured. That is, in the second dipping process, a relatively thick film can be formed on the joint edge 122 using the film of the liquid resin material M0 formed through the first dipping process as a base. This point will be described again when describing the second dipping process.

[0050] Next, this manufacturing method includes an inner diameter side resin hardening process (step S218) in which a resin hardening 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 inverted into an upward position. Hereinafter, the resin hardening process related to the inner diameter side resin hardening process is also referred to as the "inner diameter side resin hardening process" to distinguish it from the outer diameter side resin hardening process and the upper surface resin hardening process described above.

[0051] In this embodiment, the inner diameter side resin hardening process includes irradiating ultraviolet rays to the radially inner side surface of the impregnation target portion of the workpiece W. FIG. 14 shows a schematic diagram of the state in which the inner diameter side resin hardening process is being performed. In the example shown in FIG. 14, the ultraviolet irradiating device 900 irradiates ultraviolet rays to the radially inner side surface of the impregnation target portion of the workpiece W (see arrow R14). This hardens the radially inner portion (mainly the surface portion) of the liquid resin material M0 impregnated into the impregnation target portion of the workpiece W. The ultraviolet irradiating device 900 may be the same as the ultraviolet irradiating device 900 used in the above-mentioned upper surface resin hardening process.

[0052] The ultraviolet irradiation device 900 preferably irradiates ultraviolet rays to the radially inner side surface of the impregnation target portion of the workpiece W over the entire circumference. This allows the liquid resin material M0 in the radially inner portion to be cured over 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.

[0053] The ultraviolet irradiation device 900 is preferably positioned with respect to the workpiece W such 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 such that the optical axis 901 is located in an approximately vertical plane. Here, "approximately" is a concept including an error of, for example, 10% or less. The ultraviolet irradiation device 900 is preferably positioned with respect to the workpiece W such that the optical axis 901 passes through the portion of the workpiece W to be impregnated, and more preferably, the ultraviolet irradiation device 900 is positioned with respect to the workpiece W such 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.

[0054] 14, 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 in such a manner that the optical axis 901 crosses obliquely with respect to the radially inside side surface of the portion to be impregnated of the workpiece W. In this case, one of the inner diameter side resin hardening treatment and the upper surface resin hardening treatment may serve as the other.

[0055] 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.

[0056] Next, in this manufacturing method, it is determined whether the number of times the insulation coating process has been performed on one workpiece W has reached a predetermined number (in this embodiment, as an example, twice) (step S220). Such a determination may be made manually or by image processing or the like. If the determination result is "YES", the process proceeds to the next step, and otherwise, steps S206 to S218 are similarly performed to perform the second insulation coating process. FIG. 15 shows a schematic diagram of 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.

[0057] 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.

[0058] However, the second insulating coating process is preferably different from the first insulating coating process in at least the immersion process. Specifically, the immersion process in the second insulating coating process reduces the number of impregnation target portions compared to the immersion process in the first insulating coating process. That is, the impregnation target portions in the second immersion process may be a part (a part on the axial end side) of the impregnation target portions in the first immersion process (an example of the first immersion process). In this case, the impregnation target portions in the second immersion process (an example of the second immersion process) may be a minimum portion including the joint edge 122 of the coil piece 52. This allows an insulating coating (cured product of the liquid resin material M0) having the required function to be efficiently formed using a relatively small amount (for example, a minimum) of the liquid resin material M0.

[0059] FIG. 15 shows a schematic view of the range Q16 of the impregnation target portion for the second insulation coating process relative to the range (hatched area M1) of the liquid resin material impregnated into the workpiece W in the first insulation coating process. FIG. 15A also shows a schematic view of the impregnation target portion for the preferred second immersion process in the case of the joining method described above with reference to FIG. 6A. In this case, the impregnation target portion for the second immersion process may be the joint edge 122 of the coil piece 52, which is a minimum portion including the joint edge 122 for the arc-shaped outer portion 402. For example, FIG. 15A shows a schematic view of the state in which only the arc-shaped outer portion 402 of the coil piece 52 is immersed in the liquid resin material M0. In this case, only the joint edge 122 for the arc-shaped outer portion 402 can be impregnated with the liquid resin material M0 by the second immersion process.

[0060] In this manner, in this embodiment, the insulating coating process is performed multiple times (twice in this embodiment, as an example), which makes it possible to ensure a necessary thickness of the insulating coating (cured product of the liquid resin material M0) on the joint edge 122 of the coil piece 52.

[0061] Specifically, Fig. 16 shows a schematic diagram of the workpiece W in an upward orientation after the second insulating coating process is completed. In Fig. 16, the range of the liquid resin material M0 formed in the first insulating coating process (hatched area M1) and the range of the liquid resin material M0 formed in the second insulating coating process are shown in hatched area M2. Note that, for convenience of explanation, Fig. 16 (as well as Fig. 18, etc., described later) shows only the axial end of the coil end portion 114A of the stator coil 114 in a schematic diagram without omission.

[0062] In the first insulating coating process, as shown in 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 product of the 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 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 immersion step in the second insulating coating step, the liquid resin material M0 on the joint edge 122 is easily attached. That is, in the second insulating coating step, as shown in 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 a necessary thickness of insulating coating (cured product of liquid resin material M0) even for the joint edges 122 of the coil pieces 52, which have low wettability.

[0063] After the second insulating coating process is completed, the manufacturing method includes a heating process (step S222) in which the workpiece W is heated so that the liquid resin material M0 in the entire workpiece W is cured. This heating process has a function of completely curing the portion of the liquid resin material M0 that has not been cured in the various resin curing processes described above (for example, the portion 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 impregnated in the impregnation portion including the portion to be impregnated of the workpiece W is heated and completely cured. As a result, an insulating coating of the liquid resin material M0 is formed on the stator coil 114.

[0064] The posture of the workpiece W in the heating process is arbitrary, but is preferably a downward posture as shown in FIG. 17. FIG. 17 shows a schematic diagram of a plurality of workpieces W arranged side by side in a downward posture and undergoing a heating process. FIG. 17 shows a schematic diagram of a workpiece gripper 1001 of a part of a manufacturing device clamping a plurality of workpieces W, but the workpieces W may be supported on a table in such a manner that an end face of a stator core 112 abuts against an upper surface (not shown) of the table. FIG. 17 shows, as an example, heat being radiated from below the workpiece W (see arrow R17), but the direction of heat radiation is arbitrary.

[0065] Incidentally, in 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 being completely hardened may drip downward to 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 needs to be removed separately using a scraper or the like.

[0066] On the other hand, in the case of the downward posture, even if the liquid resin material M0 in the middle of curing before being completely cured moves downward under its own weight, it does not reach the stator core 112. In addition, the part of the liquid resin material M0 cured in the outer diameter side resin curing process, the upper surface resin curing process, and the inner diameter side resin curing process (see the C-shaped range 1800 when viewed from the direction in FIG. 18) functions as a "lower cover", thereby reducing the possibility that the dripping liquid resin material M0 will become icicle-like. In FIG. 18, as shown diagrammatically by the arrow R19, the downward movement of the liquid resin material M0 in the middle of curing is shown. Such downward movement of the liquid resin material M0 in the middle of curing is blocked by the part of the liquid resin material M0 cured in the outer diameter side resin curing process, the upper surface resin curing process, and the inner diameter side resin curing process. This makes it possible to prevent inconveniences that may occur when the heating process is performed in the downward posture.

[0067] Thus, 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 can be prevented, while the "bottom lid" function of the portions of the liquid resin material M0 that have been 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 icicle-like hardening of the liquid resin material M0 dripping downward.

[0068] 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 only the outer diameter side resin hardening process and / or the inner diameter side resin hardening process may be omitted.

[0069] In addition, according to the present manufacturing method, since one heating step is performed for every two insulating coating steps as described above, the amount of energy consumption (and the associated amount of carbon dioxide emissions) can be reduced compared to the case where a heating step is performed for each insulating coating step. Therefore, according to the present manufacturing method, the thickness of the insulating coating of the liquid resin material M0 can be efficiently increased.

[0070] Furthermore, when a heating step is performed after each insulating coating step, a discontinuous boundary (separation of layers) 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, but this manufacturing method can eliminate such a boundary and increase the strength of the insulating coating of the liquid resin material M0 as a whole. That is, in this manufacturing method, the viscosity of the liquid resin material M0 impregnated twice decreases during the heating step and becomes a single layer, so there is no discontinuous boundary (separation of layers) in the insulating coating and the strength is improved.

[0071] Next, with reference to FIG. 19, a cooling structure suitable for the rotating electric machine 1 incorporating the rotating electric machine stator manufactured by the present manufacturing method will be described.

[0072] FIG. 19 is a diagram showing an example of a cooling structure, and is a diagram showing a part of the cross-sectional structure of a rotating electric machine 1. As shown in FIG.

[0073] In the example shown in Fig. 19, oil is supplied from the radially outer side and the radially inner side to the coil end portion 114A at both axial ends of the stator coil 114. Specifically, oil (see arrow R20A) supplied to the case inner oil passage 60 of the case 2 is supplied to the radially outer side surface of the coil end portion 114A through an oil hole 62 penetrating toward the radially inner side (see arrow R20). Note that the oil hole 62 may be disposed on the vertically upper side so as to promote dripping of oil by gravity. Also, oil (see arrow R21A) supplied to the axial center oil passage 64 of the rotor shaft 112A is supplied to the radially inner side surface of the coil end portion 114A through an oil hole 66 penetrating toward the radially outer side (see arrow R21).

[0074] According to this manufacturing method, as described above, the coil end portion 114A of the stator coil 114 is provided with an insulating coating of the liquid resin material M0. The portion of the stator coil 114 to which the insulating coating of the liquid resin material M0 is provided has lower thermal conductivity than the portion not covered by the insulating coating of the liquid resin material M0 (i.e., the portion where 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 the liquid resin material M0 becomes unnecessarily narrow, the cooling performance by the oil from the oil hole 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 the liquid resin material M0 becomes unnecessarily narrow, the cooling performance by the oil from the oil hole 66 described above may be unnecessarily reduced.

[0075] In this respect, 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 by the outer diameter side resin curing process is cured while remaining in a downward position, so that even if the workpiece W is then in an upward position, the liquid resin material M0 on the radially outer side does 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.

[0076] In the above embodiment, the inner diameter side resin hardening process is performed on the workpiece W in an upward orientation, but it may be performed on the workpiece W in a downward orientation, similar to the outer diameter side resin hardening process. In this case, the inner diameter side resin hardening process may be performed in parallel with the outer diameter side resin hardening process. In this case, the radially inner part of the liquid resin material M0 impregnated in the impregnation target part by the inner diameter side resin hardening process is hardened while being in a downward orientation, so that 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 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 becomes unnecessarily narrow. As a result, the cooling performance of the coil end portion 114A by the oil from the above-mentioned oil hole 66 can be effectively improved.

[0077] Although each embodiment has been described above in detail, the present invention is not limited to the specific embodiment, and various modifications and changes are possible within the scope of the claims. In addition, it is also possible to combine all or a plurality of the components of the above-described embodiments.

[0078] For example, in the above-described embodiment, the outer diameter side resin hardening process is performed as a preferred embodiment, but the inner diameter side resin hardening process may be performed instead of the outer diameter side resin hardening process.

[0079] In addition, 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. However, instead of or in addition to this, a process (an example of a first or second 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]

[0080] 40 ··· Joint portion (tip portion), 52 ··· Coil piece, 112 ··· Stator core, 114 ··· Stator coil, 122 ··· Joint edge (corner portion), 402 ··· Circular arc-shaped outer portion, 4021 ··· Contact surface, 600 ··· Tank, W ··· Workpiece, M0 ··· Liquid resin material

Claims

1. a mounting step of mounting a plurality of coil pieces forming a stator coil on a stator core to form a workpiece; a joining step of joining a tip end portion of one of the coil pieces and another of the coil pieces to each other at one axial end side of the workpiece after the mounting step; A first 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; a first end surface hardening step of performing a resin hardening process on an axial end surface of the impregnation target portion after the first impregnation step; the manufacturing method for a stator for a rotating electric machine further comprising: a second impregnation step of impregnating at least a portion of an axial end face side of the impregnation target portion with a liquid resin material after the first end face hardening step.

2. 2. The method for manufacturing a stator for a rotating electric machine according to claim 1, wherein the second impregnation process includes immersing the workpiece in a tank of liquid resin material with the workpiece in an orientation such that the portion to be impregnated faces downward, so that only the portion of the portion to be impregnated is immersed.

3. 3. The method for manufacturing a stator for a rotating electric machine according to claim 1, further comprising, after the second impregnation step, a second end surface hardening step of performing a resin hardening process on the axial end surface of the impregnation target portion using a liquid resin material.

4. The liquid resin material has a property of being hardened by irradiation with ultraviolet light, 4. The method for manufacturing a stator for a rotating electric machine according to claim 3, wherein the first end surface hardening step and the second end surface hardening step include irradiating ultraviolet light.

5. The liquid resin material has a property of being hardened by heating, 5. The method for manufacturing a stator for a rotating electric machine according to claim 3, further comprising, after the second end surface hardening step, a heating step of heating the workpiece so that the liquid resin material in the entire workpiece is hardened.

6. The coil pieces have a rectangular cross-sectional shape, 6. The method for manufacturing a stator for a rotating electric machine according to claim 1, wherein the portion of the portion to be impregnated includes a corner portion on an axial end face side of the coil piece.

7. The tip portion of the coil piece has an arc-shaped outer shape that tapers toward the tip when viewed in the radial direction, The method for manufacturing a stator for a rotating electric machine according to claim 6 , wherein the corner portion extends toward an axial end face side of the arc-shaped outer portion.

8. 8. The method for manufacturing a stator for a rotating electric machine according to claim 7, wherein the joining step includes applying heat for welding to radial contact surfaces between the arc-shaped outer portions at the tip ends of the coil pieces.

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