Stator for rotating electric machine

Abstract

A stator of a rotating electrical machine is provided with: a cylindrical stator core in which a plurality of slots are formed; and a plurality of conductor segments inserted into the slots and electrically connected to each other to constitute a stator coil. The conductor segment has: a linear conductor (36); an insulating film (35) that covers the outer periphery of the conductor; a plurality of hollow capsules (38) arranged in a dispersed manner inside the insulating film; and a bent portion (41) that forms a folded-back shape of the conductor segments at an axial end portion of the stator core. The shape of the capsule included in the outer peripheral portion (42) and the inner peripheral portion of the curved portion is an ellipsoid.

Description

Technical Field

[0001] The invention relates to a stator of a rotating electric machine. Background Art

[0002] For example, there is a segmented capacitor type stator, in which, at the axial end of the stator core, the stator coil is arranged in a manner that a plurality of transition portions are continuous in the circumferential direction, and the transition portions adjacent in the circumferential direction partially overlap each other when viewed from the axial direction, the transition portion is connected from the radially inner portion of the slot to the radially outer portion of the slot, the top of the transition portion is twisted in a manner to form a cross state when viewed from the radial direction, and the portion radially outward relative to the top of the transition portion bulges radially outward when viewed from the axial direction (see Patent Document 1). According to Patent Document 1, interference between coil segments (conductor segments) at the coil end can be avoided, and the height of the transition portion can be suppressed.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2014-225974

[0006] However, in the stator described in Patent Document 1, the top of the transition portion is twisted and the transition portion bulges outward in the radial direction of the stator core, so the length of the conductor constituting the stator coil is increased, and the conduction loss increases. Summary of the invention

[0007] The present invention has been made to solve the above-mentioned technical problems, and a main object of the present invention is to suppress the height of the coil end and the conduction loss of the stator coil in a stator of a rotating electric machine including a plurality of conductor segments.

[0008] The first means for achieving the above object is a stator of a rotating electrical machine, comprising:

[0009] a cylindrical stator core having a plurality of slots formed therein; and

[0010] a plurality of conductor segments, which are inserted into the slots and electrically connected to each other to form stator coils,

[0011] The conductor segment includes: a linear conductor, an insulating film covering the outer periphery of the conductor, a plurality of hollow capsules dispersedly arranged inside the insulating film, and a bent portion forming a folded shape of the conductor segment at an axial end of the stator core.

[0012] The capsule included in the outer peripheral portion and the inner peripheral portion of the curved portion has an ellipsoidal shape.

[0013] According to the above structure, 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 suppressing the height of the conductor segment at the axial end of the stator core, that is, the height of the coil end, the length of the conductor segment can be shortened and the conduction loss can be suppressed.

[0014] Here, the conductor segment is formed into a bent portion in a folded shape at the axial end of the stator core. Therefore, by reducing the curvature radius of the bent portion, the height of the coil end can be suppressed. However, if the curvature radius of the bent portion is reduced, the insulating coating is pulled at the outer periphery of the bent portion, and cracks may occur in the insulating coating. In addition, as the cracks progress due to the use of the rotating electrical machine, the insulation of the stator coil may be reduced.

[0015] In this regard, the conductor segment has a plurality of hollow capsules dispersedly arranged inside the insulating coating. Therefore, even if cracks occur in the insulating coating at the outer periphery of the curved portion, the stress of the insulating coating can be relieved by the cracks reaching the capsules, thereby stretching or rupturing the capsules. Therefore, the progress of cracks generated in the insulating coating can be suppressed. Moreover, the shape of the capsules included in the outer periphery and inner periphery of the curved portion is ellipsoidal. Therefore, compared with spherical capsules of the same volume, cracks in the insulating coating can easily cross the capsules. Therefore, compared with the case where spherical capsules are dispersedly arranged inside the outer periphery of the insulating coating, the progress of cracks generated in the insulating coating can be suppressed. Through the above, the radius of curvature of the curved portion can be further reduced, so the height of the coil end of the stator coil can be suppressed, and further the conduction loss of the stator coil can be suppressed.

[0016] In the second means, the long diameter direction of the capsule included in the outer periphery of the curved portion is along the circumferential direction of the outer periphery of the curved portion. According to such a structure, when the cracks generated in the outer periphery of the curved portion progress toward the inner diameter direction of the curved portion, the cracks can easily cross the long diameter of the capsule. Therefore, the progress of the cracks generated in the outer periphery of the curved portion can be further suppressed.

[0017] In the third means, the major diameter direction of the capsule included in the inner circumference of the curved portion is along a direction perpendicular to the circumference of the outer circumference of the curved portion. According to such a structure, in the inner circumference of the curved portion, the minor diameter direction of the capsule becomes along the circumference of the inner circumference of the curved portion. Therefore, in the inner circumference of the curved portion, the length of the capsule in the circumference of the curved portion can be suppressed, and the curvature radius of the curved portion can be further reduced.

[0018] In the fourth means, the volume of the capsule contained in the inner circumference of the curved portion is smaller than the volume of the capsule contained in the outer circumference of the curved portion. According to such a structure, in the outer circumference of the curved portion, the crack can easily cross the capsule, and in the inner circumference of the curved portion, the radius of curvature of the curved portion can be further reduced. In addition, such a structure can be manufactured by, for example, pulling the outer circumference of the curved portion in the circumferential direction and compressing the inner circumference of the curved portion from the circumferential direction when the conductor segment forms the curved portion. Therefore, the above structure can be easily manufactured by processing the curved portion.

[0019] In the fifth means, the insulating coating is formed of polyimide, the conductor segment is fixed to the stator core via varnish inside the slot, and the capsule disposed on the surface of the insulating coating is covered with the polyimide.

[0020] According to the above structure, the insulating coating is formed of polyimide, and inside the slot, the conductor segment is fixed to the stator core by varnish. Since polyimide has good adhesion to varnish, as long as polyimide is in contact with varnish, the conductor segment can be stably fixed to the stator core by varnish. Here, the capsule is arranged on the surface of the insulating coating, and in the case where the adhesion between the capsule and the varnish is poor, the fixation of the conductor segment to the stator core based on the varnish may become weak. In this regard, the capsule arranged on the surface of the insulating coating is covered with the polyimide. Therefore, the conductor segment can be stably fixed to the stator core by varnish.

[0021] In the sixth means, the insulating coating is formed of polyimide, and the stator of the rotating electric machine is formed with a fusion portion, which is formed by fusing the conductor exposed from the insulating coating at the end of the conductor segment and the conductor exposed from the insulating coating at the end of another conductor segment, the fusion portion and a portion of the insulating coating adjacent to the fusion portion are powder-coated, and the capsule arranged on the surface of the insulating coating is covered with the polyimide.

[0022] According to the above structure, the insulating coating is formed of polyimide, and the weld portion and the portion of the insulating coating adjacent to the weld portion are powder coated. Since polyimide has good adhesion to the powder coating, as long as the polyimide is in contact with the powder coating, the portion of the insulating coating adjacent to the weld portion can be stably powder coated. Here, the capsule is arranged on the surface of the insulating coating, and in the case where 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 weld portion may be weakened. In this regard, the capsule arranged on the surface of the insulating coating is covered with the polyimide. Therefore, the portion of the insulating coating adjacent to the weld portion can be stably powder coated.

[0023] In the seventh means, one insertion portion is inserted into the common slot, and the other insertion portion of the adjacent conductor segment is inserted into the different slots, the conductor segment has a top portion, the top portion is a curved portion different from the curved portion, the curvature radius of the inner circumference of the curved portion is less than 3.5 mm, and the curvature radius of the inner circumference of the top portion is less than 2.0 mm.

[0024] According to the above structure, the insertion part of one side is inserted into the adjacent conductor segment of the common slot, and the insertion part of the other side is inserted into the different slots. Therefore, compared with the structure in which the insertion part of one side is inserted into the adjacent conductor segment of the common slot, the insertion part of the other side is inserted into the common slot, it is easy to increase the height of the coil end in order to avoid interference between the conductor segments. In this regard, since the radius of curvature of the inner circumference of the curved portion is less than 3.5 mm, the height of the coil end can be suppressed. And even in this case, the capsule can suppress the progress of cracks generated in the insulating coating.

[0025] At the outer periphery of the bent portion of the conductor segment, the insulation coating is stretched and thinned, and cracks are likely to enter the insulation coating. Therefore, the insulation withstand voltage at the outer periphery of the bent portion of the conductor segment is likely to decrease.

[0026] In this regard, in the eighth means, the plurality of conductor segments are arranged at a distance longer than 1 / 2 of the thickness of the conductor on the outer peripheral side of the curved portion different from the curved portion. According to such a structure, it is easy to ensure the insulation distance between the outer peripheral portion of the curved portion of the conductor segment and other conductor segments, so the insulation of the stator coil can be further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a three-dimensional diagram of the stator.

[0028] Figure 2 This is the front view of the stator.

[0029] Figure 3 It is a top view of the stator core.

[0030] Figure 4 It is a perspective view showing a conductor segment and a part of a stator core.

[0031] Figure 5A It is a partial cross-sectional view showing a part of the conductor segment housed in the slot.

[0032] Figure 5B It is an enlarged perspective view showing the welded portion of the conductor segment.

[0033] Figure 6 It is a schematic diagram showing the state of progress of cracks in the insulating coating in the comparative example.

[0034] Figure 7 This is a schematic diagram showing a state in which the progress of cracks in the insulating coating is suppressed by the capsule.

[0035] Figure 8 This is a schematic diagram showing a state in which the progress of cracks in the insulating coating is suppressed by the spherical capsules.

[0036] Fig. 9 This is a schematic diagram showing a state in which the progress of cracks in the insulating coating is suppressed by the ellipsoidal capsule.

[0037] Fig.10 It is the front view of the conductor segment.

[0038] Fig.11 is a top view of the conductor segment.

[0039] Fig.12 This is a cross-sectional photograph of the capsule showing the outer peripheral portion of the curved portion.

[0040] Fig.13 It is a schematic diagram showing the bending part of a comparative example and an embodiment of the present application.

[0041] Fig.14 This is a cross-sectional photograph of the capsule showing the inner circumference of the curved portion.

[0042] Fig.15 It is an enlarged view showing the curvature radius of the curved portion of the comparative example and the embodiment of the present application.

[0043] Fig.16 It is a front view showing the height of the coil end portion in the comparative example and the embodiment of the present application.

[0044] Fig.17 Schematic diagrams showing bonding states between conductor segments and stator cores according to a comparative example and an embodiment of the present application.

[0045] Fig.18 is a top view of a plurality of configured conductor segments.

[0046] Fig.19 is a front view of a plurality of configured conductor segments. DETAILED DESCRIPTION

[0047] Hereinafter, an embodiment of a stator embodied as a rotating electrical machine will be described based on the accompanying drawings. In addition, in the following embodiments and modifications, the same reference numerals are given to the parts that are common or equivalent to each other in the drawings, and the descriptions thereof are cited for the parts with the same reference numerals. The electric motor as the rotating electrical machine of this embodiment is used as, for example, an electric motor for a vehicle or an electric motor for an aircraft.

[0048] The rotating electrical machine of the present embodiment can be applied to a winding excitation type or an induction machine including a permanent magnet synchronous motor, and is a rotating electrical machine having a three-phase coil. Figure 1 The cylindrical stator 10 (stator) shown in the figure, and the rotor (not shown) arranged on the radial inner side of the stator 10. The rotor (rotor) is arranged to be rotatable with respect to the stator 10 around the rotation axis. Hereinafter, the axial direction refers to the axial direction of the stator 10, that is, the axial direction of the rotation axis of the rotor, the radial direction refers to the radial direction of the stator 10, that is, the direction passing through the center of the rotation axis of the rotor and orthogonal to the rotation axis, and the circumferential direction refers to the circumferential direction of the stator 10, that is, the circumferential direction around the rotation axis of the rotor.

[0049] like Figure 1 and Figure 2 As shown, the stator 10 has a stator core 11 in an annular shape (cylindrical shape, tubular shape) and a stator coil 12 (stator winding) wound on the stator core 11. The rotating electric machine of this embodiment is an inner rotor type rotating electric machine, and the rotor is arranged in a rotatable state on the radial inner side of the stator 10. 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) of each phase, and a power line bus bar 13 (power line connection line) is connected to one end of the phase coil of each phase, and a neutral line bus bar (neutral line connection line) is connected to the other end. In the stator coil 12, the range that overlaps with the stator core 11 in the axial direction is the slot coil part CS, and the parts on both sides of the axial direction that are closer to the axial outside than the stator core 11 are the coil ends CE1 and CE2. In addition, the rotating electric machine can also be an outer rotor type or an axial gap type.

[0050] like Figure 3 As shown, the stator core 11 has an annular back yoke 21 and a plurality of teeth 22 protruding radially inward from the back yoke 21 and arranged at a predetermined distance in the circumferential direction. Slots 23 are formed between adjacent teeth 22. The slots 23 are open shapes extending in the radial direction as the long side direction, and are arranged at equal intervals in the circumferential direction in the stator core 11. And the stator coil 12 is arranged in a state of being wound around the slots 23. The stator core 11 is configured as a chip stack body in which chips composed of electromagnetic steel plates as magnetic bodies are stacked in the axial direction, for example.

[0051] The stator coil 12 is formed by connecting three-phase coils by, for example, a Y-connection (star connection). In addition, the three-phase coils can also be connected by a Δ connection or the like. The stator coil 12 generates a magnetic flux by being supplied with electric power (AC power) from a power supply via an inverter not shown in the figure. The stator coil 12 is formed using a plurality of conductor segments 30. The conductor segment 30 (coil segment) is a divided conductor formed by shaping a linear electric conductor (conductor) of a constant thickness with a roughly rectangular cross-section (rectangular cross-section) into a roughly U-shape (folded shape). The segmented structure of the stator coil 12 is described in detail below.

[0052] Figure 4 3 is a perspective view showing a portion of the conductor segment 30 and the stator core 11. Figure 4 As shown, the conductor segment 30 is substantially U-shaped and has a pair of straight portions 31 and a bend portion 32 formed by bending to connect the pair of straight portions 31. The pair of straight portions 31 (insertion portions) have a length longer than the axial thickness of the stator core 11. The conductor segment 30 is formed using a rectangular wire formed by covering a conductor (a conductor having a pair of opposing flat portions) with an insulating film having a rectangular cross section. The insulating film is formed of polyimide. The top end of each straight portion 31 is cut off from the insulating film to form a conductor exposed portion 33 where the conductor is exposed.

[0053] A plurality of conductor segments 30 are inserted into the slots 23 of the stator core 11 in a state of being arranged in a row in the radial direction. In the present embodiment, the straight portions 31 of the conductor segments 30 are accommodated in the slots 23 in a state of stacking four layers. In the conductor segment 30, a pair of straight portions 31 are respectively accommodated in two slots 23 separated by a predetermined coil pitch. The portion of the straight portion 31 accommodated in the slot 23 corresponds to the slot coil portion CS in the stator coil 12. In addition, an insulating sheet 24 is provided in the slot 23 to electrically insulate the stator core 11 from the stator coil 12 (conductor segment 30). The insulating sheet 24 is bent in a manner of completely surrounding the plurality of conductor segments 30 inserted in the slot 23, and is provided in the slot 23 in a state of being sandwiched between the inner peripheral surface (inner wall surface) of the stator core 11 and the conductor segment 30. By impregnating the insulating sheet 24 with varnish and hardening it, the conductor segment 30 is fixed to the stator core 11 by the varnish inside the slot 23.

[0054] A pair of straight portions 31 of the conductor segment 30 are respectively accommodated in two slots 23 with one radial position offset. For example, when the straight portion 31 of one side is accommodated in the position No. n from the radial inside (back yoke side), the straight portion 31 of the other side is accommodated in the position No. n+1 from the radial inside. In addition, the straight portions 31 of the other side of the radially adjacent conductor segment 30, whose straight portion 31 of one side is inserted into the common slot 23, are respectively inserted into different slots 23. In addition, in the conductor segment that serves as a transition line between the outermost periphery and the innermost periphery, when the straight portion 31 of one side is accommodated in the position No. n from the radial inside, the straight portion 31 of the other side is also accommodated in the position No. n from the radial inside.

[0055] 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 second end side at the axial ends of the stator core 11, and the top end 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 CE1 is formed by the turn portion 32 of the conductor segment 30. In addition, at the second end side of the stator core 11, the reverse 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, thereby forming the other coil end CE2. The outline of each coil end CE1, CE2 (coil end) is as follows. Figure 2 Next, the connection of the conductor segment 30 in the coil end CE2 will be described in detail.

[0056] Figure 5A 2 is a diagram showing a portion of a conductor segment 30 housed in a slot 23. In the conductor segment 30, the reverse bend side of a pair of straight portions 31 protrudes from the axial end surface (upper end surface in the figure) of the stator core 11 and is bent in the circumferential direction in a manner inclined at a predetermined angle relative to the core end surface. Figure 5B As shown in the enlarged coil end CE2 in the figure, the conductor exposed portions 33 at the top ends of different conductor segments 30 are joined by welding, so that the plurality of conductor segments 30 are connected (electrically connected). The portion where the conductor exposed portions 33 are joined by welding is the welding portion 34. The welding portion 34 and a portion 35a adjacent to the welding portion 34 in the insulating coating 35 are coated with powder. In detail, the powder is blown in a manner to cover the welding portion 34 and the portion 35a of the insulating coating 35, and the powder is melted and solidified by high temperature to form a coating (not shown).

[0057] In the coil end CE2, the circumferential top end of the conductor segment 30 extending in a certain circumferential direction on the axially outer side of the stator core 11 is joined to the circumferential top end of another conductor segment 30 extending in a direction opposite to the certain circumferential direction. As a result, the stator coil 12 is in a state where the straight portion 31 of the conductor segment 30 extends in a direction inclined relative to the axial direction and is folded back at a predetermined top position. The conductor segment 30 includes a portion where the reverse turning portion side of each straight portion 31 is bent in the circumferential direction to the same side as the turning portion 32 and a portion where the reverse turning portion side of each straight portion 31 is bent in the circumferential direction to the side opposite to the turning portion 32.

[0058] In the phase coils of each phase, conductors are connected by joining the conductor segments 30 together in the middle portion thereof, and the power line bus bar 13 and the neutral line bus bar of each phase are connected to the conductor exposed portion 33 at the coil ends.

[0059] Here, if Figure 5AAs shown, the conductor segment 30 has a bend 41 that forms a folded shape of the conductor segment 30 at the axial end of the stator core 11. The smaller the radius of curvature of the bend 41, the more the height of the coil end CE1 can be suppressed. The lower the height of the coil end CE1, the shorter the length of the turn 32 can be, and the conduction loss of the stator coil 12 can be reduced. However, if the radius of curvature of the bend 41 is reduced, when the conductor segment 30 is bent by stamping to form the bend 41, or as the rotating motor is used, the insulating coating 35 of the outer peripheral portion 42 of the bend 41 is prone to cracking. This is because, as the radius of curvature of the bend 41 is smaller, the circumferential tensile stress generated on the insulating coating 35 of the outer peripheral portion 42 is greater.

[0060] Figure 6 Schematic diagram showing the state of the progress of cracks 37 in the insulating coating 35 in the comparative example. In the outer peripheral portion 42 of the curved portion 41, if cracks 37 are generated on the outer peripheral surface of the insulating coating 35, the cracks 37 progress in the inner diameter direction of the curved portion 41 as shown by the arrow. Even if the cracks 37 progress, the stress of the insulating coating 35 is not relaxed, so the cracks 37 progress to the conductor 36. In addition, the conductor 36 is formed of oxygen-free copper, aluminum, hard asphalt copper, etc.

[0061] In this embodiment, if Figure 7 As shown in FIG. 1 , 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 are in a hollow spherical shape, a hollow ellipsoidal shape, or the like. If a crack 37 is generated on the outer peripheral surface of the insulating coating 35 in the outer peripheral portion 42 of the curved portion 41, the crack 37 advances in the inner diameter direction of the curved portion 41 as indicated by the arrow. However, when the crack 37 advances, the crack 37 reaches the capsule 38, and the capsule 38 at the top of the crack 37 is stretched or broken. As a result, the stress of the insulating coating 35 is relieved, and the crack 37 stops at the capsule 38 before advancing to the conductor 36.

[0062] The shape of capsule 38 varies depending on the portion of conductor segment 30 .

[0063] like Figure 8 As shown, the capsule 38 included in the insulating coating 35 has a spherical shape in the linear portion of the linear portion 31 and the curved portion 32. In this case, the crack 37 may reach the capsule 38 after advancing between the capsules 38.

[0064] like Fig. 9As shown in FIG. 1 , the capsule 38 included in the insulating film 35 is ellipsoidal in the outer peripheral portion 42 of the curved portion 41. In addition, the direction of the major diameter a (major diameter direction) of the capsule 38 included in the outer peripheral portion 42 of the curved portion 41 is along (substantially parallel to) the circumferential direction Cr of the outer peripheral portion 42 of the curved portion 41. In this case, the crack 37 is difficult to develop between the capsules 38, and the crack 37 is easy to reach the capsule 38 at a position close to the outer peripheral surface of the insulating film 35.

[0065] Fig.10 is a front view of the conductor segment 30, Fig.11 30 is a top view of the conductor segment 30. Fig.11 As shown, the turning portion 32 of the conductor segment 30 has a top portion 46 that is bent in a crank shape ("S" shape). The top portion 46 (bend portion) has two outer peripheral portions 47 and two inner peripheral portions 48. The minimum value of the radius of curvature of the inner peripheral portion 43 of the bend 41 is 3.5 mm or less. The minimum value of the radius of curvature of the inner peripheral portion 48 of the top portion 46 is 2.0 mm or less, for example, 1.5 mm or more and 2.0 mm or less. In addition, the radius of curvature of the inner peripheral portion 43 of the bend 41 can be 3.0 mm or less, or 3.0 mm or more and 4.0 mm or less, or greater than 4.0 mm. The radius of curvature of the inner peripheral portion 48 of the top portion 46 can also be 1.5 mm or less, or 1.5 mm or more and 2.5 mm or less, or greater than 2.5 mm.

[0066] Fig.12 This is a cross-sectional photograph of the capsule 38 showing the outer peripheral portion of the curved portion. Fig.12 yes Fig.10 Area A and Fig.11 The cross-sectional photograph of the region B of the capsule 38 is shown. The major axis direction of the capsule 38 is along (substantially parallel to) the circumferential direction Cr of the outer peripheral portion 42 of the curved portion 41 (the outer peripheral portion 47 of the top portion 46 ).

[0067] Fig.13Schematic diagram showing the bending portion of the comparative example and the embodiment of the present application. In addition, in the same figure, the display of the capsule 38 included in the outer peripheral 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 compression load fp act on the inner peripheral portion 43A to generate a reaction force fr1. In the present embodiment, when the conductor segment 30 is bent by the jig T, the compression load fp acts on the inner peripheral portion 43 so that the capsule 38 is broken, and the gas inside the capsule 38 is released 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 peripheral portion 43 shrinks in the radial direction Dr of the curved portion 41. As a result, the position of the outer surface of the outer peripheral portion 42 moves a distance ΔR in the inner diameter direction compared with the position of the outer surface of the outer peripheral portion 42A of the comparative example. In addition, the volume of the capsule 38 included in the inner peripheral portion 43 of the curved portion 41 becomes smaller than the volume of the capsule 38 included in the outer peripheral portion 42 of the curved portion 41. In addition, in the same figure, the distance ΔR is exaggeratedly shown.

[0068] Fig.14 This is a cross-sectional photograph of the capsule 38 showing the inner peripheral portion of the curved portion. Fig.14 yes Fig.13 The cross-sectional photograph of region C of the capsule 38 is shown in FIG. The major axis direction of the capsule 38 is along a direction perpendicular to (substantially parallel to) the circumferential direction Cr of the inner circumference 43 of the curved portion 41 (the inner circumference 48 of the top portion 46). The direction perpendicular to the circumferential direction Cr is the radial direction Dr of the curved portion 41, the direction Dv perpendicular to the circumferential direction Cr and the radial direction Dr, and the direction between the radial direction Dr and the direction Dv.

[0069] Fig.15 It is an enlarged view showing the curvature radius of the curved 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 curved portion 41 (outer peripheral portion 42, inner peripheral portion 43) of the present embodiment is the same as the distance X1 from the surface of the stator core 11 to the end of the curved portion 41 (outer peripheral portion 42A, inner peripheral portion 43A) of the comparative example. The curvature radius R2 of the inner peripheral portion 43 of the present embodiment is smaller than the curvature radius R1 of the inner peripheral portion 43A of the comparative example. Therefore, the height H2 of the starting point of the turning portion 32 in the present embodiment can be made lower than the height H1 of the starting point of the turning portion 32 in the comparative example.

[0070] Fig.16 This is a front view showing the height of the coil end of the comparative example and the embodiment of the present application. Fig.13 , Fig.15 In the structure shown, a height H4 from the surface of the stator core 11 to the upper surface of the top portion 46 in the present embodiment is lower than a height H3 from the surface of the stator core 11 to the upper surface of the top portion 46 in the comparative example.

[0071] Fig.17Schematic diagram showing the bonding state of the conductor segment 30 and the stator core 11 of 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 by the insulating coating 35. Therefore, the capsule 38A is in contact with the varnish 26. In the case where the capsule 38 (38A) is formed of silicone, the adhesion between the capsule 38A and the varnish 26 deteriorates, and the fixation of the conductor segment 30 to the stator core 11 based on the varnish 26 becomes weak inside the slot 23. In contrast, in the present embodiment, the capsule 38A arranged on the surface of the insulating coating 35 is covered by the insulating coating 35. The insulating coating 35 formed of polyimide has good adhesion to the varnish 26. Therefore, inside the slot 23, the conductor segment 30 can be firmly fixed to the stator core 11 by the varnish 26.

[0072] In addition, the same is true for the portion 35a adjacent to the welded portion 34 in the insulating film 35. That is, when the capsule 38 (38A) is formed of silicone, the adhesion between the capsule 38A disposed on the surface of the insulating film 35 and the powder coating is deteriorated. In the present embodiment, the capsule 38A disposed on the surface of the insulating film 35 is covered by the insulating film 35. The insulating film 35 formed of polyimide has good adhesion to the coating film of the powder coating. Therefore, the close contact between the portion 35a of the insulating film 35 and the coating film of the powder coating can be improved.

[0073] The present embodiment described in detail above can be summarized as follows.

[0074] The conductor segment 30 has a plurality of hollow capsules 38 dispersedly arranged inside the insulating coating 35. Therefore, even if cracks 37 are generated in the insulating coating 35 at the outer peripheral portions 42 and 47 of the curved portion 41 and the top portion 46, the stress of the insulating coating 35 can be relieved by the cracks 37 reaching the capsules 38 and the capsules 38 stretching or breaking. Therefore, the progress of the cracks 37 generated in the insulating coating 35 can be suppressed. Moreover, the shape of the capsules 38 included in the outer peripheral portions 42 and 47 and the inner peripheral portions 43 and 48 of the curved portion 41 and the top portion 46 is an ellipsoid. Therefore, compared with a spherical capsule 38 of the same volume, the cracks 37 of the insulating coating 35 can easily cross the capsules 38. Therefore, compared with a case where the spherical capsules 38 are dispersedly arranged inside the outer peripheral portions 42 and 47 of the insulating coating 35, the progress of the cracks 37 generated in the insulating coating 35 can be suppressed. As described above, the curvature radius of the curved portion 41 and the top portion 46 can be reduced, so that the height H4 of the coil end CE1 of the stator coil 12 can be reduced, thereby reducing the conduction loss of the stator coil 12. In addition, it can contribute to the miniaturization of the stator 10 and the miniaturization of the motor.

[0075] The direction of the major diameter a of the capsule 38 included in the outer peripheral portions 42 and 47 of the curved portion 41 and the top portion 46 is along the circumferential direction Cr of the outer peripheral portions 42 and 47 of the curved portion 41 and the top portion 46. According to such a structure, when the cracks 37 generated in the outer peripheral portions 42 and 47 of the curved portion 41 and the top portion 46 advance in the inner diameter direction of the curved portion 41 and the top portion 46, the cracks 37 can easily cross the major diameter a of the capsule 38. Therefore, the progress of the cracks 37 generated in the outer peripheral portions 42 and 47 of the curved portion 41 and the top portion 46 can be further suppressed.

[0076] The direction of the major diameter a of the capsule 38 included in the inner circumference 43 and 48 of the curved portion 41 and the top portion 46 is along the direction perpendicular to the circumferential direction Cr of the outer circumference 42 and 47 of the curved portion 41 and the top portion 46. According to such a structure, in the inner circumference 43 and 48 of the curved portion 41 and the top portion 46, the minor diameter direction of the capsule 38 is along the circumferential direction Cr of the inner circumference 43 and 48 of the curved portion 41 and the top portion 46. Therefore, in the inner circumference 43 and 48 of the curved portion 41 and the top portion 46, the length of the capsule 38 in the circumferential direction Cr of the curved portion 41 and the top portion 46 can be suppressed, and the curvature radius of the curved portion 41 and the top portion 46 can be more easily reduced.

[0077] The volume of the capsule 38 included in the inner circumference 43 and 48 of the curved portion 41 and the top portion 46 is smaller than the volume of the capsule 38 included in the outer circumference 42 and 47 of the curved portion 41 and the top portion 46. According to such a structure, the crack 37 can easily cross the capsule 38 in the outer circumference 42 and 47 of the curved portion 41 and the top portion 46, and the curvature radius of the curved portion 41 and the top portion 46 can be more easily reduced in the inner circumference 43 and 48 of the curved portion 41 and the top portion 46. In addition, such a structure can be manufactured by pulling the outer circumference 42 and 47 of the curved portion 41 and the top portion 46 in the circumferential direction Cr and compressing the inner circumference 43 and 48 of the curved portion 41 and the top portion 46 from the circumferential direction Cr when forming the curved portion 41 and the top portion 46 in the conductor segment 30. Therefore, the above structure can be easily manufactured by processing the curved portion 41 and the top portion 46.

[0078] The insulating coating 35 is formed of polyimide, and the conductor segment 30 is fixed to the stator core 11 by the varnish 26 inside the slot 23. Since the adhesion between polyimide and the varnish 26 is good, as long as the polyimide and the varnish 26 are in contact, the conductor segment 30 can be stably fixed to the stator core 11 by the varnish 26. Here, the capsule 38A may be arranged on the surface of the insulating coating 35. In the case where the adhesion between the capsule 38A and the varnish 26 is poor, the fixing of the conductor segment 30 to the stator core 11 by the varnish 26 will be weakened. In this regard, the capsule 38A arranged on the surface of the insulating coating 35 is covered by the insulating coating 35 (polyimide). Therefore, the conductor segment 30 can be stably fixed to the stator core 11 by the varnish 26.

[0079] The insulating film 35 is formed of polyimide, and the weld 34 and the portion 35a adjacent to the weld 34 in the insulating film 35 are powder-coated. Since the adhesion between polyimide and the powder coating is good, as long as the polyimide and the powder coating are in contact, the portion 35a adjacent to the weld 34 in the insulating film 35 can be stably powder-coated. Here, the capsule 38A is arranged on the surface of the insulating film 35. In the case where the adhesion between the capsule 38A and the powder coating is poor, the adhesion of the powder coating to the portion 35a adjacent to the weld 34 in the insulating film 35 may be weakened. In this regard, the capsule 38A arranged on the surface of the insulating film 35 is covered by the insulating film 35 (polyimide). Therefore, the portion 35a adjacent to the weld 34 in the insulating film 35 can be stably powder-coated.

[0080] The straight portion 31 of one side is inserted into the common slot 23, and the straight portion 31 of the other side is inserted into the different slots 23. Therefore, compared with the structure in which the straight portion 31 of one side is inserted into the common slot 23, and the straight portion 31 of the other side of the adjacent conductor segment 30 is inserted into the common slot 23, it is easy to increase the height of the coil end CE1 to avoid interference between the conductor segments 30. In this regard, the minimum value of the radius of curvature of the inner circumference 43 of the curved portion 41 is 3.5 mm or less, so the height H4 of the coil end CE1 can be suppressed. And even in this case, the capsule 38 can suppress the progress of the crack 37 generated in the insulating coating 35.

[0081] When the conductor segment 30 is bent by the jig T, the capsule 38 included in the inner peripheral portion 43 is broken and the reaction force fr2 is reduced, so that the force required for the process of bending the conductor segment 30 can be reduced. In addition, the insulating film 35 can be suppressed from wrinkling in the inner peripheral portions 43 and 48 of the curved portion 41 and the top portion 46. Moreover, the return amount after the conductor segment 30 is bent can be suppressed, so the bending process of the conductor segment 30 becomes easy.

[0082] In addition, the above-mentioned embodiment can be implemented by changing as follows. The same reference numerals are attached to the same parts as those in the above-mentioned embodiment, and the description thereof is cited.

[0083] like Fig.18 As shown in the top view of FIG. 4 , the insulating film 35 (not shown) extends in the outer peripheral portion 47 of the curved portion of the top 46 of the conductor segment 30, so that the insulating film 35 becomes thinner, and cracks easily enter the insulating film 35. Therefore, the insulation withstand voltage of the outer peripheral portion 47 of the curved portion of the top 46 of the conductor segment 30 is easily reduced. In addition, Fig.19 yes Fig.18 A front view of a conductor segment 30 is shown.

[0084] Therefore, if Fig.18As shown in the top view of , the distance X1 between the outer peripheral portion 47 of the curved portion of the top 46 of one conductor segment 30 and the outer peripheral portion 47 of the opposite curved portion of the top 46 of other conductor segments 30 is longer than half the thickness of the electric conductor constituting the conductor segment 30. Preferably, the distance X1 is longer than 2 / 3 of the thickness of the electric conductor constituting the conductor segment 30. That is, the plurality of conductor segments 30 are arranged at a distance longer than 1 / 2 of the thickness of the electric conductor on the outer peripheral side of the curved portion (top 46) different from the curved portion 41. In other words, in one conductor segment 30, there are no other conductor segments 30 arranged along (adjacent to) the conductor segment 30 on the outer peripheral side of the curved portion different from the curved portion 41. In addition, the conductor segments 30 are formed one by one, rather than being formed in a bundle. In contrast, when the plurality of conductor segments are formed in a bundle, the conductor segments are adjacent to each other. In addition, since there are other conductor segments arranged along (adjacent to) the outer peripheral side of the curved portion, the insulation withstand voltage of the outer peripheral portion of the curved portion is reduced.

[0085] according to Fig.18 The structure shown can easily ensure the insulation distance between the outer peripheral portion 47 of the curved portion of the top 46 of the conductor segment 30 and other conductor segments 30, thereby further improving the insulation of the stator coil 12. In addition, the plurality of conductor segments 30 can also be arranged at a distance longer than the thickness of the electrical conductor constituting the conductor segment 30 on the outer peripheral side of the curved portion of the top 46.

[0086] Inside the slot 23 , the conductor segment 30 may be fixed to the stator core 11 using a resin coating other than varnish, or may be fixed to the stator core 11 via a foamed resin sheet (insulating sheet).

[0087] The insulating film 35 can be formed 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.

[0088] The electric motor to which the stator 10 is applied may be a generator or a motor generator (MG: Motor Generator). In addition, the above-mentioned embodiments and their modified examples may be implemented in combination within the range in which the combinations are possible.

Claims

1. A stator of a rotating electrical machine, comprising: a cylindrical stator core having a plurality of slots formed therein; and a plurality of conductor segments, which are inserted into the slots and electrically connected to each other to form stator coils, It is characterized in that The conductor segment includes: a linear conductor, an insulating film covering the outer periphery of the conductor, a plurality of hollow capsules dispersedly arranged inside the insulating film, and a bent portion forming a folded shape of the conductor segment at an axial end of the stator core. The capsule included in the outer peripheral portion and the inner peripheral portion of the curved portion has an ellipsoidal shape.

2. The stator of a rotating electrical machine according to claim 1, characterized in that: The major diameter direction of the capsule included in the outer peripheral portion of the curved portion is along the circumferential direction of the outer peripheral portion of the curved portion.

3. The stator of a rotating electrical machine according to claim 1 or 2, characterized in that: The major axis direction of the capsule included in the inner peripheral portion of the curved portion is along a direction perpendicular to the circumferential direction of the outer peripheral portion of the curved portion.

4. The stator of a rotating electrical machine according to claim 1 or 2, characterized in that: The volume of the capsule included in the inner circumference of the curved portion is smaller than the volume of the capsule included in the outer circumference of the curved portion.

5. The stator of a rotating electrical machine according to claim 1 or 2, characterized in that: The insulating film is formed of polyimide. Inside the slots, the conductor segments are fixed to the stator core by varnish, The capsule disposed on the surface of the insulating film is covered with the polyimide.

6. The stator of a rotating electrical machine according to claim 1 or 2, characterized in that: The insulating film is formed of polyimide. The stator of the rotating electric machine is formed with a welded portion formed by welding the conductor exposed from the insulating film at the end of the conductor segment and the conductor exposed from the insulating film at the end of another conductor segment. The welded portion and a portion of the insulating film adjacent to the welded portion are powder coated, The capsule disposed on the surface of the insulating film is covered with the polyimide.

7. The stator of a rotating electrical machine according to claim 1 or 2, characterized in that: One insertion portion is inserted into the common slot, and the other insertion portion of the adjacent conductor segments is inserted into the different slots. The conductor segment has a top portion, the top portion being a curved portion different from the curved portion, The curvature radius of the inner circumference of the curved portion is less than 3.5 mm, The curvature radius of the inner peripheral portion of the top portion is 2.0 mm or less.

8. The stator of a rotating electrical machine according to claim 1 or 2, characterized in that: The plurality of conductor segments are arranged at an outer peripheral side of a curved portion different from the curved portion, spaced apart from each other by a distance longer than ½ of the thickness of the conductor.

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