Stator for rotary electric machine

Abstract

To suppress the height of a coil end of a stator coil and conduction loss in a stator for a rotary electric machine that has a plurality of conductive segments.SOLUTION: A stator for a rotary electric machine comprises: a cylindrical stator core with a plurality of slots formed therein; and a plurality of conductive segments inserted into the slots and being electrically connected to each other to form a stator coil. Each conductive segment includes: a linear conductor (36); an insulation coated film (35) covering an outer periphery of the conductor; a plurality of hollow capsules (38) distributed inside the insulation coated film; and a bent part (41) that forms the conductive segments in a folded shape at an axial end of the stator core. Capsules contained in an external peripheral part (42) and an internal peripheral part of the folding part are ellipsoidal in shape.SELECTED DRAWING: Figure 7

Description

[Technical field]

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

[0002] For example, there is a segment conductor type stator in which, at the axial end of the stator core, the stator coil has a crossover section that connects the radially inner part of the slot to the radially outer part of the slot, which is continuous in multiple circumferential directions, and is arranged so that adjacent crossover sections in the circumferential direction partially overlap when viewed from the axial direction, and the tops of the crossover sections are twisted to form an intersecting state when viewed from the radial direction, and the parts radially outer than the tops of the crossover sections bulge radially outward when viewed from the axial direction (see Patent Document 1). According to Patent Document 1, it is possible to avoid interference between coil segments (conductor segments) at the coil ends and to suppress the height of the crossover section. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-225974 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the stator described in Patent Document 1, the tops of the transition parts are twisted and the transition parts bulge radially outward from the stator core, which increases the length of the conductors that make up the stator coil and increases conduction loss.

[0005] The present invention has been made to solve the above-mentioned problems, and its main object is to reduce the height and conduction loss of the coil ends of a stator coil in a stator of a rotating electric machine having a plurality of conductor segments. [Means for solving the problem]

[0006] The first means for solving the above problem is a cylindrical stator core (11) having a plurality of slots (23) formed therein; a plurality of conductor segments (30) inserted into the slots and electrically connected to each other to form a stator coil (12), The conductor segment includes a linear conductor (36), an insulating coating (35) covering an outer periphery of the conductor, a plurality of hollow capsules (38, 38A) distributed within the insulating coating, and a bent portion (41) that forms a folded-back shape on the conductor segment at an end portion in the axial direction of the stator core, The capsule contained within the outer periphery (42) and inner periphery (43) of the bent portion has an ellipsoidal shape.

[0007] According to the above configuration, a plurality of slots are formed in the cylindrical stator core. A plurality of conductor segments are inserted into the slots and electrically connected to each other to form a stator coil. Therefore, by reducing the height of the conductor segments at the axial ends of the stator core, i.e., the height of the coil ends, it is possible to shorten the length of the conductor segments and reduce conduction loss.

[0008] Here, the conductor segments have bent portions at the axial ends of the stator core that form a folded shape on the conductor segments. Therefore, by reducing the radius of curvature of the bent portions, the height of the coil ends can be reduced. However, if the radius of curvature of the bent portions is reduced, the insulating coating is pulled at the outer periphery of the bent portions, which may cause cracks in the insulating coating. Furthermore, the cracks may grow during use of the rotating electric machine, which may cause a deterioration in the insulation of the stator coil.

[0009] In this regard, the conductor segment has a plurality of hollow capsules dispersedly disposed inside the insulating coating. Therefore, even if a crack occurs in the insulating coating at the outer periphery of the bent portion, the crack reaches the capsule, which stretches or breaks, thereby alleviating the stress of the insulating coating. Therefore, the crack occurring in the insulating coating can be suppressed from progressing. Furthermore, the capsules included in the outer periphery and inner periphery of the bent portion have an ellipsoidal shape. Therefore, compared with a spherical capsule of the same volume, it is possible to make it easier for a crack in the insulating coating to cross the capsule. Therefore, compared with a case in which spherical capsules are dispersedly disposed inside the outer periphery of the insulating coating, it is possible to suppress the progression of a crack occurring in the insulating coating. As a result, the radius of curvature of the bent portion can be made smaller, so that the height of the coil end of the stator coil can be suppressed, and thus the conduction loss of the stator coil can be suppressed.

[0010] In the second aspect, the major axis direction of the capsule included in the outer periphery of the bent portion is aligned with the circumferential direction of the outer periphery of the bent portion. With this configuration, when a crack generated in the outer periphery of the bent portion propagates toward the inner diameter of the bent portion, the crack can easily cross the major axis of the capsule. Therefore, the propagation of the crack generated in the outer periphery of the bent portion can be further suppressed.

[0011] In the third aspect, the major axis of the capsule included in the inner peripheral portion of the bent portion is aligned in a direction perpendicular to the circumferential direction of the outer peripheral portion of the bent portion. With this configuration, the minor axis of the capsule is aligned in the circumferential direction of the inner peripheral portion of the bent portion. Therefore, the length of the capsule in the circumferential direction of the bent portion can be reduced in the inner peripheral portion of the bent portion, making it easier to further reduce the radius of curvature of the bent portion.

[0012] In a fourth aspect, the volume of the capsule included in the inner peripheral portion of the bent portion is smaller than the volume of the capsule included in the outer peripheral portion of the bent portion. With this configuration, it is possible to make it easier for cracks to cross the capsule at the outer peripheral portion of the bent portion, and it is easier to further reduce the radius of curvature of the bent portion at the inner peripheral portion of the bent portion. In addition, this configuration can be manufactured, for example, when forming a bent portion in a conductor segment, by pulling the outer peripheral portion of the bent portion in the circumferential direction and compressing the inner peripheral portion of the bent portion from the circumferential direction. Therefore, the above configuration can be easily manufactured by processing the bent portion.

[0013] In a fifth means, the insulating coating is formed of polyimide, the conductor segments are fixed to the stator core inside the slots by varnish (26), and the capsule (38A) arranged on the surface of the insulating coating is covered with the polyimide.

[0014] According to the above configuration, the insulating coating is formed of polyimide, and the conductor segments are fixed to the stator core by varnish inside the slots. Since polyimide and varnish have good adhesion, the conductor segments can be stably fixed to the stator core by the varnish as long as the polyimide is in contact with the varnish. Here, the capsules may be disposed on the surface of the insulating coating, and if the adhesion between the capsules and the varnish is poor, the fixing of the conductor segments to the stator core by the varnish may be weakened. In this regard, the capsules disposed on the surface of the insulating coating are covered by the polyimide. Therefore, the conductor segments can be stably fixed to the stator core by the varnish.

[0015] In a sixth means, the insulating coating is formed of polyimide, a weld (34) is formed by welding the conductor (33) exposed from the insulating coating at the end of the conductor segment to the conductor exposed from the insulating coating at the end of another conductor segment, the weld and a portion (35a) of the insulating coating adjacent to the weld are powder coated, and the capsule arranged on the surface of the insulating coating is covered with the polyimide.

[0016] According to the above configuration, the insulating coating is made of polyimide, and the welded portion and the portion of the insulating coating adjacent to the welded portion are powder coated. Since the adhesion between polyimide and the powder coating is good, if the polyimide is in contact with the powder coating, the portion of the insulating coating adjacent to the welded portion can be stably powder coated. Here, the capsule may be disposed on the surface of the insulating coating, and if the adhesion between the capsule and the powder coating is poor, the adhesion of the powder coating to the portion of the insulating coating adjacent to the welded portion may be weakened. In this regard, the capsule disposed on the surface of the insulating coating is covered by the polyimide. Therefore, the portion of the insulating coating adjacent to the welded portion can be stably powder coated.

[0017] In the seventh means, the other insertion portion of adjacent conductor segments, one of which is inserted into the common slot, is inserted into a different slot, and the conductor segments have an apex (46) that is a portion that is bent separately from the bent portion, and the radius of curvature of the inner periphery of the bent portion is 3.5 mm or less, and the radius of curvature of the inner periphery of the apex is 2.0 mm or less.

[0018] According to the above configuration, the other insertion portion of the adjacent conductor segments, one of which is inserted into the common slot, is inserted into a different slot. Therefore, compared to a configuration in which the other insertion portion of the adjacent conductor segments, one of which is inserted into the common slot, is inserted into the common slot, the height of the coil end is likely to be high in order to avoid interference between the conductor segments. In this regard, since the radius of curvature of the inner peripheral portion of the bent portion is 3.5 mm or less, the height of the coil end can be suppressed. Even in this case, the capsule can suppress the propagation of cracks generated in the insulating coating.

[0019] The insulating coating is stretched around the outer periphery of the bent portion of the conductor segment, making the insulating coating thinner and more susceptible to cracking, which reduces the withstand voltage of the outer periphery of the bent portion of the conductor segment.

[0020] In this regard, in the eighth aspect, the plurality of conductor segments are disposed at a distance greater than half the thickness of the conductor on the outer circumferential side of the bent portion (46) separately from the bent portion. This configuration makes it easier to ensure an insulation distance between the outer circumferential portion of the bent portion of the conductor segment and other conductor segments, thereby further improving the insulation of the stator coil. [Brief description of the drawings]

[0021] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3] FIG. [Figure 4] FIG. 4 is a perspective view showing a conductor segment and a portion of a stator core. [Diagram 5] FIG. 4 is a partial cross-sectional view showing some conductor segments received in a slot. [Figure 5A] FIG. 4 is an enlarged perspective view showing a welded portion of a conductor segment. [Figure 6]FIG. 4 is a schematic diagram showing how a crack in an insulating coating grows in a comparative example. [Figure 7] FIG. 1 is a schematic diagram showing how the capsule suppresses the growth of a crack in an insulating coating. [Figure 8] Schematic diagram showing how the propagation of a crack in an insulating coating is suppressed by a spherical capsule. [Figure 9] A schematic diagram showing how the propagation of a crack in an insulating coating is suppressed by an ellipsoidal capsule. [Figure 10] FIG. [Figure 11] FIG. [Figure 12] 11 is a cross-sectional photograph showing a capsule on the outer periphery of a bent portion. [Figure 13] 5A and 5B are schematic diagrams showing bent portions of a comparative example and an embodiment of the present application. [Figure 14] 11 is a cross-sectional photograph showing a capsule at the inner circumference of a bent portion. [Figure 15] FIG. 4 is an enlarged view showing the radius of curvature of a bent portion according to a comparative example and an embodiment of the present application. [Figure 16] FIG. 4 is a front view showing the height of the coil end portion according to the comparative example and the embodiment of the present application. [Figure 17] 5A and 5B are schematic diagrams showing the adhesive state between the conductor segments and the stator core according to the comparative example and the embodiment of the present application. [Figure 18] FIG. 4 is a plan view of a plurality of arranged conductor segments. [Figure 19] FIG. 4 is a front view of a plurality of arranged conductor segments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] An embodiment of the present invention implemented as a stator for a rotating electric machine will be described below with reference to the drawings. In the following embodiment and modified examples, the same or equivalent parts are denoted by the same reference numerals in the drawings, and the description of the same parts is incorporated herein. The motor as the rotating electric machine of this embodiment is used as, for example, an electric motor for a vehicle or an electric motor for an aircraft.

[0023] The rotating electric machine of this embodiment is applicable to permanent magnet synchronous motors, wound field type motors, and induction motors, and is a rotating electric machine having three-phase coils. The rotating electric machine includes a cylindrical stator 10 (fixed part) shown in FIG. 1, a rotor (not shown) arranged radially inside the stator 10, and the like. The rotor (rotor) is arranged rotatably about a rotation axis with respect to the stator 10. Hereinafter, the axial direction refers to the axial direction of the stator 10, i.e., the axial direction of the rotor's rotation axis, the radial direction refers to the radial direction of the stator 10, i.e., the direction passing through the center of the rotor's rotation axis and perpendicular to the rotation axis, and the circumferential direction refers to the circumferential direction of the stator 10, i.e., the direction around the rotor's rotation axis.

[0024] As shown in FIG. 1 and FIG. 2, the stator 10 includes a stator core 11 having an annular (cylindrical, tubular) shape, and a stator coil 12 (stator winding) wound around the stator core 11. The rotating electric machine of this embodiment is an inner rotor type rotating electric machine, and the rotor is arranged radially inside the stator 10 in a rotatable state. The stator coil 12 is a three-phase coil having a U-phase coil, a V-phase coil, and a W-phase coil as phase coils (phase windings) for each phase, and a power line bus bar 13 (power line connection line) is connected to one end of each phase coil, and a neutral line bus bar (neutral line connection line) is connected to the other end. In the stator coil 12, the range overlapping with the stator core 11 in the axial direction is the in-slot coil portion CS, and the portions on both axial sides that are axially outside the stator core 11 are the coil end portions CE1 and CE2. The rotating electric machine may be an outer rotor type or an axial gap type.

[0025] As shown in Fig. 3, the stator core 11 has an annular back yoke 21 and a plurality of teeth 22 that protrude radially inward from the back yoke 21 and are arranged at a predetermined distance in the circumferential direction. Slots 23 are formed between adjacent teeth 22. The slots 23 have an opening shape that extends in the radial direction as the longitudinal direction, and are provided at equal intervals in the circumferential direction in the stator core 11. The stator coil 12 is provided in a state of being wound around the slots 23. The stator core 11 is configured as a core sheet laminate in which core sheets made of, for example, electromagnetic steel sheets, which are magnetic bodies, are stacked in the axial direction.

[0026] The stator coil 12 is configured by connecting three-phase coils, for example, in a Y-connection (star-shaped connection). The three-phase coils may also be connected in a Δ-connection or the like. The stator coil 12 generates magnetic flux when power (AC power) is supplied from a power source via an inverter (not shown). The stator coil 12 is configured using a plurality of conductor segments 30. The conductor segments 30 (coil segments) are divided conductors formed by shaping a linear electric conductor (conductor) of a constant thickness with a substantially rectangular cross section (flat square cross section) into a substantially U-shape (folded shape). The segment structure of the stator coil 12 will be described in detail below.

[0027] FIG. 4 is a perspective view showing a conductor segment 30 and a part of the stator core 11. As shown in FIG. 4, the conductor segment 30 is substantially U-shaped and has a pair of straight portions 31 that are linear, and a turn portion 32 that is bent so as to connect the pair of straight portions 31. The pair of straight portions 31 (insertion portion) has a length longer than the axial thickness of the stator core 11. The conductor segment 30 is formed using a rectangular conductor wire in which a conductor having a rectangular cross section (a conductor having a pair of opposing flat portions) is covered with an insulating coating. The insulating coating is made of polyimide. The tip portion of each straight portion 31 is a conductor exposed portion 33 where the conductor is exposed by removing the insulating coating.

[0028] A plurality of conductor segments 30 are inserted into the slots 23 of the stator core 11 in a radially aligned state. In this embodiment, the straight portions 31 of the conductor segments 30 are accommodated in the slots 23 in a stacked state in four layers. In the conductor segment 30, a pair of straight portions 31 are accommodated in the two slots 23 separated by a predetermined coil pitch. The portion of the straight portions 31 accommodated in the slots 23 corresponds to the in-slot coil portion CS of the stator coil 12. An insulating sheet 24 is provided in the slots 23 to electrically insulate the stator core 11 from the stator coil 12 (the conductor segments 30). The insulating sheet 24 is folded so as to surround the plurality of conductor segments 30 inserted into the slots 23, and is provided in the slots 23 in a state of being sandwiched between the inner peripheral surface (inner wall surface) of the stator core 11 and the conductor segments 30. The insulating sheet 24 is impregnated with varnish and then cured, so that the conductor segments 30 are fixed to the stator core 11 inside the slots 23 by the varnish.

[0029] A pair of straight portions 31 of a conductor segment 30 are accommodated in two slots 23, each shifted by one position in the radial direction. For example, when one straight portion 31 is accommodated in the nth position from the radial back side (back yoke side), the other straight portion 31 is accommodated in the n+1th position from the radial back side. In addition, when one straight portion 31 is inserted into a common slot 23, the other straight portion 31 of two radially adjacent conductor segments 30 is inserted into a different slot 23. In addition, in a conductor segment serving as a crossover wire between the outermost and innermost circumferences, when one straight portion 31 is accommodated in the nth position from the radial back side, the other straight portion 31 is also accommodated in the nth position from the radial back side.

[0030] When each conductor segment 30 is inserted into the slot 23 of the stator core 11, the straight portion 31 of each conductor segment 30 is inserted from the first end side of the first end side and the tip portion of the straight portion 31 protrudes from the second end side. In this case, at the first end side of the stator core 11, one coil end portion CE1 is formed by the turn portion 32 of the conductor segment 30. At the second end side of the stator core 11, the anti-turn portion side of each straight portion 31 is bent in the circumferential direction, and the straight portions 31 of different conductor segments 30 are connected to each other to form the other coil end portion CE2. The coil end portions CE1 and CE2 (coil ends) are outlined as shown in FIG. 2. Next, the connection of the conductor segments 30 at the coil end portion CE2 will be described in more detail.

[0031] FIG. 5 is a diagram showing some of the conductor segments 30 housed in the slots 23. In the conductor segments 30, the opposite turn sides of a pair of straight portions 31 protrude from the axial end face (the upper end face in the figure) of the stator core 11 and are bent in the circumferential direction so as to be oblique at a predetermined angle with respect to the core end face. As shown in an enlarged view of the coil end portion CE2 in FIG. 5A, the conductor exposed portions 33 at the tips of different conductor segments 30 are joined together by welding, so that the multiple conductor segments 30 are connected (electrically connected). The portion where the conductor exposed portions 33 are joined together by welding becomes a welded portion 34. The welded portion 34 and a portion 35a of the insulating coating 35 adjacent to the welded portion 34 are powder coated. In more detail, a powder is sprayed so as to cover the welded portion 34 and the portion 35a of the insulating coating 35, and the powder is melted at a high temperature and then solidified to form a coating (not shown).

[0032] In the coil end portion CE2, a circumferential tip portion of a conductor segment 30 extending in a constant circumferential direction on the axial outside of the stator core 11 is joined to a circumferential tip portion of another conductor segment 30 extending in a direction opposite to the constant circumferential direction. As a result, in the stator coil 12, the straight portions 31 of the conductor segments 30 extend in a direction inclined with respect to the axial direction at the coil end portion CE2 and are folded back at a predetermined apex position. The conductor segments 30 include those in which the anti-turn portion side of each straight portion 31 is bent in the same circumferential direction as the turn portion 32, and those in which the anti-turn portion side of each straight portion 31 is bent in the circumferential direction opposite to the turn portion 32.

[0033] In the phase coil of each phase, the conductors are connected in the middle by joining the conductor segments 30 together, while at the coil ends, the power line bus bar 13 and neutral line bus bar of each phase are connected to the conductor exposed portion 33.

[0034] Here, as shown in FIG. 5, the conductor segment 30 has a bent portion 41 that forms a folded shape on the conductor segment 30 at the end in the axial direction of the stator core 11. The smaller the radius of curvature of the bent portion 41, the more the height of the coil end portion CE1 can be suppressed. The lower the height of the coil end portion CE1, the shorter the length of the turn portion 32 can be, and the smaller the conduction loss of the stator coil 12 can be. However, if the radius of curvature of the bent portion 41 is made small, cracks are more likely to occur in the insulating coating 35 of the outer circumferential portion 42 of the bent portion 41 when the conductor segment 30 is bent by press processing or the like to form the bent portion 41, or during use of the rotating electric machine. This is because the smaller the radius of curvature of the bent portion 41, the greater the circumferential tensile stress generated in the insulating coating 35 of the outer circumferential portion 42.

[0035] 6 is a schematic diagram showing how a crack 37 in an insulating coating 35 in a comparative example grows. When a crack 37 occurs on the outer peripheral surface of the insulating coating 35 at an outer periphery 42 of a bent portion 41, the crack 37 grows in the radial direction of the bent portion 41 as shown by the arrow. Even if the crack 37 grows, the stress in the insulating coating 35 is not relieved, so the crack 37 grows to the conductor 36. The conductor 36 is made of oxygen-free copper, aluminum, tough pitch copper, or the like.

[0036] In this embodiment, as shown in FIG. 7, the conductor segment 30 has a plurality of hollow capsules 38 dispersedly arranged inside the insulating coating 35. The capsules 38 are formed of a resin such as silicone and have a hollow spherical shape, a hollow ellipsoidal shape, or the like. When a crack 37 occurs on the outer peripheral surface of the insulating coating 35 at the outer peripheral portion 42 of the bent portion 41, the crack 37 propagates in the inner diameter direction of the bent portion 41 as shown by the arrow. However, when the crack 37 propagates, the crack 37 reaches the capsule 38, and the capsule 38 located at the tip of the crack 37 stretches or breaks. This relieves the stress of the insulating coating 35, and the crack 37 stops at the capsule 38 before it propagates to the conductor 36.

[0037] The shape of the capsule 38 varies depending on the portion of the conductor segment 30 .

[0038] In the straight portion 31 and the straight portion of the turn portion 32, the capsules 38 contained in the insulating coating 35 are spherical in shape, as shown in Fig. 8. In this case, there is a risk that the crack 37 will reach the capsules 38 after propagating between the capsules 38.

[0039] 9, in the outer periphery 42 of the bent portion 41, the capsules 38 contained in the insulating coating 35 have an ellipsoidal shape. The direction of the major axis a (major axis direction) of the capsules 38 contained in the outer periphery 42 of the bent portion 41 is along (substantially parallel to) the circumferential direction Cr of the outer periphery 42 of the bent portion 41. In this case, the cracks 37 are unlikely to progress between the capsules 38, and the cracks 37 are likely to reach the capsules 38 at a position close to the outer periphery of the insulating coating 35.

[0040] FIG. 10 is a front view of the conductor segment 30, and FIG. 11 is a plan view of the conductor segment 30. As shown in FIG. 11, the turn portion 32 of the conductor segment 30 has an apex 46 bent into a crank shape (an "S" shape). The apex 46 (bent portion) has two outer periphery portions 47 and two inner periphery portions 48. The minimum value of the radius of curvature of the inner periphery portion 43 of the bent portion 41 is 3.5 [mm] or less. The minimum value of the radius of curvature of the inner periphery portion 48 of the apex 46 is 2.0 [mm] or less, for example, 1.5 [mm] or more and 2.0 [mm] or less. The radius of curvature of the inner periphery portion 43 of the bent portion 41 can be 3.0 [mm] or less, 3.0 [mm] or more and 4.0 [mm] or less, or greater than 4.0 [mm]. The radius of curvature of the inner periphery 48 of the apex 46 can be 1.5 mm or less, 1.5 mm or more and 2.5 mm or less, or greater than 2.5 mm.

[0041] Fig. 12 is a cross-sectional photograph showing a capsule 38 at the outer periphery of a bent portion. Fig. 12 is a cross-sectional photograph of region A in Fig. 10 and region B in Fig. 11. The major axis direction of capsule 38 is aligned (substantially parallel) with the circumferential direction Cr of outer periphery 42 of bent portion 41 (outer periphery 47 of apex 46).

[0042] FIG. 13 is a schematic diagram showing the bent portion of the comparative example and the embodiment of the present application. In the figure, the capsule 38 included in the outer circumferential portion 42 is omitted. In the comparative example, when the conductor segment 30 is bent by the jig T, the bending load fb and the compressive load fp act on the inner circumferential portion 43A, generating a reaction force fr1. In the present embodiment, when the conductor segment 30 is bent by the jig T, the compressive load fp acts on the inner circumferential portion 43, crushing the capsule 38, and the gas inside the capsule 38 escapes to the outside of the insulating coating 35. Therefore, the reaction force fr2 becomes smaller than the reaction force fr1 of the comparative example, and the inner circumferential portion 43 shrinks in the radial direction Dr of the bent portion 41. As a result, the position of the outer surface of the outer circumferential portion 42 moves in the inner radial direction by a distance ΔR from the position of the outer surface of the outer circumferential portion 42A of the comparative example. In addition, the volume of the capsule 38 included in the inner circumferential portion 43 of the bent portion 41 is smaller than the volume of the capsule 38 included in the outer circumferential portion 42 of the bent portion 41. In addition, the distance ΔR is exaggerated in the figure.

[0043] Fig. 14 is a cross-sectional photograph showing the capsule 38 at the inner periphery of the bent portion. Fig. 14 is a cross-sectional photograph of region C in Fig. 13. The major axis direction of the capsule 38 is along a direction perpendicular to (substantially parallel to) the circumferential direction Cr of the inner periphery 43 (the inner periphery 48 of the apex 46) of the bent portion 41. The direction perpendicular to the circumferential direction Cr is the radial direction Dr of the bent portion 41, a direction Dv perpendicular to the circumferential direction Cr and the radial direction Dr, an intermediate direction between the radial direction Dr and the direction Dv, etc.

[0044] 15 is an enlarged view showing the radius of curvature of the bent portion 41 of the comparative example and the embodiment of the present application. The distance X2 from the surface of the stator core 11 to the end of the bent portion 41 (outer peripheral portion 42, inner peripheral portion 43) of this embodiment is the same as the distance X1 from the surface of the stator core 11 to the end of the bent portion 41 (outer peripheral portion 42A, inner peripheral portion 43A) of the comparative example. The radius of curvature R2 of the inner peripheral portion 43 of this embodiment is smaller than the radius of curvature R1 of the inner peripheral portion 43A of the comparative example. Therefore, the height H2 at which the turn portion 32 starts in this embodiment can be made lower than the height H1 at which the turn portion 32 starts in the comparative example.

[0045] Fig. 16 is a front view showing the height of the coil end portion of the comparative example and the embodiment of the present application. Due to the configurations shown in Fig. 13 and Fig. 15, the height H4 from the surface of the stator core 11 to the upper surface of the apex 46 in this embodiment is lower than the height H3 from the surface of the stator core 11 to the upper surface of the apex 46 in the comparative example.

[0046] FIG. 17 is a schematic diagram showing the state of adhesion between the conductor segment 30 and the stator core 11 in the comparative example and the embodiment of the present application. In the comparative example, the capsule 38A arranged on the surface of the insulating coating 35 is not covered with the insulating coating 35. Therefore, the capsule 38A is in contact with the varnish 26. If the capsule 38 (38A) is made of silicone, the adhesion between the capsule 38A and the varnish 26 is poor, and the fixing of the conductor segment 30 to the stator core 11 by the varnish 26 inside the slot 23 is weakened. In contrast, in the present embodiment, the capsule 38A arranged on the surface of the insulating coating 35 is covered with the insulating coating 35. The adhesion between the insulating coating 35 made of polyimide and the varnish 26 is good. Therefore, the conductor segment 30 can be firmly fixed to the stator core 11 by the varnish 26 inside the slot 23.

[0047] The same is true for portion 35a of insulating coating 35 adjacent to welded portion 34. That is, if capsule 38 (38A) is made of silicone, adhesion between capsule 38A arranged on the surface of insulating coating 35 and the powder coating will be poor. In this embodiment, capsule 38A arranged on the surface of insulating coating 35 is covered with insulating coating 35. Adhesion between insulating coating 35 made of polyimide and the powder coating is good. Therefore, adhesion between portion 35a of insulating coating 35 and the powder coating can be improved.

[0048] The present embodiment described above in detail has the following advantages.

[0049] The conductor segment 30 has a plurality of hollow capsules 38 dispersedly disposed inside the insulating coating 35. Therefore, even if a crack 37 occurs in the insulating coating 35 at the outer periphery 42, 47 of the bent portion 41 and the apex 46, the crack 37 reaches the capsule 38, which stretches or breaks, thereby alleviating the stress of the insulating coating 35. Therefore, the crack 37 occurring in the insulating coating 35 can be prevented from progressing. Furthermore, the capsules 38 included in the outer periphery 42, 47 and the inner periphery 43, 48 of the bent portion 41 and the apex 46 are ellipsoidal in shape. Therefore, compared to a spherical capsule 38 of the same volume, the crack 37 in the insulating coating 35 can easily cross the capsule 38. Therefore, compared to a case in which the spherical capsules 38 are dispersedly disposed inside the outer periphery 42, 47 of the insulating coating 35, the crack 37 occurring in the insulating coating 35 can be prevented from progressing. As a result, the radius of curvature of the bent portion 41 and the apex 46 can be made smaller, which in turn makes it possible to reduce the height H4 of the coil end portion CE1 of the stator coil 12 and thus the conduction loss of the stator coil 12. This also contributes to the miniaturization of the stator 10 and, in turn, the miniaturization of the electric motor.

[0050] The direction of the major axis a of the capsule 38 included in the outer periphery 42, 47 of the bent portion 41 and the apex 46 is aligned with the circumferential direction Cr of the outer periphery 42, 47 of the bent portion 41 and the apex 46. With this configuration, when the crack 37 generated in the outer periphery 42, 47 of the bent portion 41 and the apex 46 propagates in the inner diameter direction of the bent portion 41 and the apex 46, the crack 37 can easily cross the major axis a of the capsule 38. Therefore, the propagation of the crack 37 generated in the outer periphery 42, 47 of the bent portion 41 and the apex 46 can be further suppressed.

[0051] The direction of the major axis a of the capsule 38 included in the inner peripheral parts 43, 48 of the bent portion 41 and the apex 46 is along a direction perpendicular to the circumferential direction Cr of the outer peripheral parts 42, 47 of the bent portion 41 and the apex 46. With this configuration, the minor axis direction of the capsule 38 in the inner peripheral parts 43, 48 of the bent portion 41 and the apex 46 is along the circumferential direction Cr of the inner peripheral parts 43, 48 of the bent portion 41 and the apex 46. Therefore, in the inner peripheral parts 43, 48 of the bent portion 41 and the apex 46, the length of the capsule 38 in the circumferential direction Cr of the bent portion 41 and the apex 46 can be reduced, making it easier to further reduce the radius of curvature of the bent portion 41 and the apex 46.

[0052] The volume of the capsule 38 included in the inner circumferential parts 43, 48 of the bent part 41 and the apex 46 is smaller than the volume of the capsule 38 included in the outer circumferential parts 42, 47 of the bent part 41 and the apex 46. With this configuration, the crack 37 can easily cross the capsule 38 at the outer circumferential parts 42, 47 of the bent part 41 and the apex 46, and the radius of curvature of the bent part 41 and the apex 46 can be easily reduced at the inner circumferential parts 43, 48 of the bent part 41 and the apex 46. This configuration can be manufactured by pulling the outer circumferential parts 42, 47 of the bent part 41 and the apex 46 in the circumferential direction Cr and compressing the inner circumferential parts 43, 48 of the bent part 41 and the apex 46 from the circumferential direction Cr when forming the bent part 41 and the apex 46 in the conductor segment 30. Therefore, the above configuration can be easily manufactured by processing the bent part 41 and the apex 46.

[0053] The insulating coating 35 is made of polyimide, and the conductor segments 30 are fixed to the stator core 11 by the varnish 26 inside the slots 23. Since the adhesion between polyimide and the varnish 26 is good, the conductor segments 30 can be stably fixed to the stator core 11 by the varnish 26 as long as the polyimide is in contact with the varnish 26. Here, capsules 38A may be arranged on the surface of the insulating coating 35, and if the adhesion between the capsules 38A and the varnish 26 is poor, the fixing of the conductor segments 30 to the stator core 11 by the varnish 26 may be weakened. In this regard, the capsules 38A arranged on the surface of the insulating coating 35 are covered by the insulating coating 35 (polyimide). Therefore, the conductor segments 30 can be stably fixed to the stator core 11 by the varnish 26.

[0054] The insulating coating 35 is made of polyimide, and the welded portion 34 and the portion 35a of the insulating coating 35 adjacent to the welded portion 34 are powder coated. Since the adhesion between polyimide and the powder coating is good, if the polyimide is in contact with the powder coating, the portion 35a of the insulating coating 35 adjacent to the welded portion 34 can be stably powder coated. Here, capsules 38A may be arranged on the surface of the insulating coating 35, and if the adhesion between the capsules 38A and the powder coating is poor, the adhesion of the powder coating to the portion 35a of the insulating coating 35 adjacent to the welded portion 34 may be weakened. In this regard, the capsules 38A arranged on the surface of the insulating coating 35 are covered by the insulating coating 35 (polyimide). Therefore, the portion 35a of the insulating coating 35 adjacent to the welded portion 34 can be stably powder coated.

[0055] The straight portions 31 of adjacent conductor segments 30, one of which is inserted into a common slot 23, are inserted into different slots 23. For this reason, the height of the coil end portion CE1 is likely to be high in order to avoid interference between the conductor segments 30, compared to a configuration in which the straight portions 31 of adjacent conductor segments 30, one of which is inserted into a common slot 23, are inserted into a common slot 23. In this regard, the minimum value of the radius of curvature of the inner periphery 43 of the bent portion 41 is 3.5 mm or less, so that the height H4 of the coil end portion CE1 can be suppressed. Even in this case, the capsule 38 can suppress the propagation of the crack 37 generated in the insulating coating 35.

[0056] When the conductor segment 30 is bent using the jig T, the capsules 38 contained in the inner circumferential portion 43 are crushed and the reaction force fr2 is reduced, thereby reducing the force required to bend the conductor segment 30. Also, wrinkles in the insulating coating 35 can be prevented at the bent portion 41 and the inner circumferential portions 43, 48 of the apex 46. Furthermore, the amount of return of the conductor segment 30 after bending can be reduced, making it easier to bend the conductor segment 30.

[0057] The above embodiment can be modified as follows: The same parts as those in the above embodiment are denoted by the same reference numerals and the description thereof will be incorporated herein.

[0058] As shown in the plan view of Fig. 18, at the outer periphery 47 of the bent portion of the top 46 of the conductor segment 30, the insulating coating 35 (not shown) is stretched, making the insulating coating 35 thinner and more susceptible to cracking. As a result, the dielectric strength of the outer periphery 47 of the bent portion of the top 46 of the conductor segment 30 is likely to decrease. Fig. 19 is a front view of the conductor segment 30 of Fig. 18.

[0059] Therefore, as shown in the plan view of FIG. 18, the distance X1 between the outer periphery 47 of the bent portion of the apex 46 of one conductor segment 30 and the outer periphery 47 of the opposing bent portion of the apex 46 of another conductor segment 30 is longer than half the thickness of the electric conductor constituting the conductor segment 30. Desirably, the distance X1 is longer than 2 / 3 the thickness of the electric conductor constituting the conductor segment 30. That is, the multiple conductor segments 30 are arranged at a distance longer than 1 / 2 the thickness of the electric conductor on the outer periphery side of the portion (apex 46) bent separately from the bent portion 41. In other words, on the outer periphery side of the portion bent separately from the bent portion 41 in one conductor segment 30, there is no other conductor segment 30 arranged along (adjacent to) that conductor segment 30. Note that the conductor segments 30 are molded one by one, and are not molded by bundling multiple conductor segments. In contrast, when multiple conductor segments are molded by bundling multiple conductor segments, the conductor segments are adjacent to each other. Furthermore, since other conductor segments are present along (adjacent to) the outer periphery of the bent portion, the dielectric strength of the outer periphery of the bent portion decreases.

[0060] 18, it is easy to ensure an insulation distance between the outer periphery 47 of the bent portion of the apex 46 of the conductor segment 30 and other conductor segments 30, thereby further improving the insulation of the stator coil 12. Note that the multiple conductor segments 30 may be arranged on the outer periphery side of the bent portion of the apex 46 with a distance between them that is longer than the thickness of the electrical conductor that constitutes the conductor segment 30.

[0061] Inside the slots 23, the conductor segments 30 may be fixed to the stator core 11 using a resin paint other than varnish, or may be fixed to the stator core 11 by a foamed resin sheet (insulating sheet).

[0062] The insulating coating 35 can also be made of a heat-resistant resin other than polyimide, such as PEEK (Poly Ether Ether Ketone) resin, PPS (Poly Phenylene Sulfide) resin, or PAI (Poly Amide Imide) resin.

[0063] The electric motor to which the stator 10 is applied may be a generator or a motor generator (MG).

[0064] The above-described embodiments and their modifications can be combined to the extent possible.

[0065] Characteristic configurations extracted from the above-described embodiment and modified examples will be described below. [Configuration 1] a cylindrical stator core (11) having a plurality of slots (23) formed therein; a plurality of conductor segments (30) inserted into the slots and electrically connected to each other to form a stator coil (12), The conductor segment includes a linear conductor (36), an insulating coating (35) covering an outer periphery of the conductor, a plurality of hollow capsules (38, 38A) distributed within the insulating coating, and a bent portion (41) that forms a folded-back shape on the conductor segment at an end portion in the axial direction of the stator core, a capsule included in the outer circumferential portion (42) and the inner circumferential portion (43) of the bent portion has an ellipsoidal shape; [Configuration 2] 2. The stator of the rotating electric machine according to claim 1, wherein a major axis direction of the capsule included in the outer periphery of the bent portion is aligned with a circumferential direction of the outer periphery of the bent portion. [Configuration 3] 3. The stator of the rotating electric machine according to claim 1 or 2, wherein a major axis direction of the capsule included in the inner periphery of the bent portion is aligned in a direction perpendicular to a circumferential direction of the outer periphery of the bent portion. [Configuration 4] 4. The stator for a rotating electric machine according to any one of configurations 1 to 3, wherein a volume of the capsule included in the inner circumferential portion of the bent portion is smaller than a volume of the capsule included in the outer circumferential portion of the bent portion. [Configuration 5] the insulating coating is made of polyimide; Within the slots, the conductor segments are fixed to the stator core by varnish (26), 5. The stator of a rotating electric machine according to any one of configurations 1 to 4, wherein the capsule (38A) disposed on the surface of the insulating coating is covered with the polyimide. [Configuration 6] the insulating coating is made of polyimide; a welded portion (34) is formed by welding the conductor (33) exposed from the insulating coating at the end of the conductor segment to the conductor exposed from the insulating coating at the end of another conductor segment, The welded portion and a portion (35a) of the insulating coating adjacent to the welded portion are powder coated, 6. The stator of a rotating electric machine according to any one of configurations 1 to 5, wherein the capsule disposed on the surface of the insulating coating is covered with the polyimide. [Configuration 7] The other insertion portions of adjacent conductor segments, one of which is inserted into the common slot, are inserted into different slots, The conductor segment has a top portion (46) which is a bent portion separate from the bent portion, The radius of curvature of the inner periphery of the bent portion is 3.5 mm or less, 7. The stator for a rotating electric machine according to any one of configurations 1 to 6, wherein the radius of curvature of the inner periphery of the apex is 2.0 mm or less. [Configuration 8] The stator of a rotating electric machine according to any one of configurations 1 to 7, wherein the plurality of conductor segments are arranged at a distance from each other that is greater than half the thickness of the conductor on the outer circumferential side of a portion (46) bent separately from the bent portion. [Explanation of symbols]

[0066] 10... stator, 11... stator core, 12... stator coil, 23... slot, 30... conductor segment, 35... insulating coating, 36... conductor, 38... capsule, 38A... capsule, 41... bent portion, 42... outer periphery, 43... inner periphery.

Claims

1. A cylindrical stator core (11) having a plurality of slots (23) formed therein; a plurality of conductor segments (30) inserted into the slots and electrically connected to each other to form a stator coil (12), The conductor segment includes a linear conductor (36), an insulating coating (35) covering an outer periphery of the conductor, a plurality of hollow capsules (38, 38A) distributed within the insulating coating, and a bent portion (41) that forms a folded-back shape on the conductor segment at an end portion in the axial direction of the stator core, A stator for a rotating electric machine, wherein the capsule included in the outer circumferential portion (42) and the inner circumferential portion (43) of the bent portion has an ellipsoidal shape.

2. The stator of claim 1 , wherein a major axis direction of the capsule included in the outer periphery of the bent portion is aligned with a circumferential direction of the outer periphery of the bent portion.

3. 3. The stator for a rotating electric machine according to claim 1, wherein a major axis direction of the capsule included in the inner periphery of the bent portion is aligned in a direction perpendicular to a circumferential direction of the outer periphery of the bent portion.

4. 3. The stator for a rotating electric machine according to claim 1, wherein a volume of the capsule included in the inner peripheral portion of the bent portion is smaller than a volume of the capsule included in the outer peripheral portion of the bent portion.

5. the insulating coating is made of polyimide; Within the slots, the conductor segments are fixed to the stator core by varnish (26); 3. The stator of claim 1, wherein the capsule (38A) disposed on the surface of the insulating coating is covered with the polyimide.

6. the insulating coating is made of polyimide; a welded portion (34) is formed by welding the conductor (33) exposed from the insulating coating at the end of the conductor segment to the conductor exposed from the insulating coating at the end of another conductor segment, The welded portion and a portion (35a) of the insulating coating adjacent to the welded portion are powder coated; 3. The stator for a rotating electric machine according to claim 1, wherein the capsules disposed on the surface of the insulating coating are covered with the polyimide.

7. The other insertion portions of adjacent conductor segments, one of which is inserted into the common slot, are inserted into different slots, The conductor segment has a top portion (46) that is a bent portion separate from the bent portion, The radius of curvature of the inner periphery of the bent portion is 3.5 mm or less, 3. The stator for a rotating electric machine according to claim 1, wherein a radius of curvature of an inner periphery of said apex portion is 2.0 mm or less.

8. 3. The stator of claim 1, wherein the plurality of conductor segments are arranged at an outer circumferential side of a portion bent separately from the bent portion, the plurality of conductor segments being spaced apart from each other by a distance greater than half the thickness of the conductor.

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