Rotating electric machines

Abstract

A rotating electric machine comprising a multi-phase armature coil wound on an armature core. The armature coil is formed by conductor groups, each conductor group being a bundle of conductor segments and having a pair of legs and a connecting portion connecting the legs. The connecting portion is radially bent relative to the circumferential direction. The conductor groups are paired, such that each pair of conductor groups comprises a first conductor group and a second conductor group, both belonging to the same phase of the armature coil. The circumferential spacing between the legs of the first conductor group is greater than the circumferential spacing between the legs of the second conductor group. In each pair of conductor groups, the connecting portions of the first conductor group and the second conductor group are arranged to axially overlap each other.

Description

Technical Field

[0001] The present disclosure relates to a rotating electric machine. Background Art

[0002] A known rotating electric machine includes an armature having a multi-phase armature coil wound around an armature core. Furthermore, a method is also known for forming the armature coil by: (1) inserting two legs of each generally U-shaped coil segment into corresponding slots of the armature core from one axial side of the armature core; and (2) joining each pair of corresponding portions of the coil segment legs that protrude outside corresponding slots on the other axial side of the armature core (see, for example, Japanese Patent No. JP5702179B2).

[0003] More specifically, according to a known method, a generally S-shaped portion is formed in the head portion of each coil segment, thereby reducing the circumferential dimension of the intersection region where the head portion radially crosses the coil end portion of the armature coil. Consequently, the heads of the coil segments extending from adjacent slots of the armature core can be compactly overlapped, thereby reducing the size of the coil end portion of the armature coil.

[0004] The inventors of the present application have discovered the following problem with known rotating electrical machines. Specifically, in practice, it is desirable to modify the design specifications of the rotating electrical machine, such as by reducing the outer diameter of the armature, increasing the number of slots formed in the armature core, increasing the thickness of the coil segments, or increasing the number of coil segments, depending on the desired performance. However, even using known armature coil forming methods, there are limitations on how much the circumferential dimension of the intersection region of each coil segment's head can be reduced. Consequently, the design specifications of the rotating electrical machine may not be easily modified. Summary of the Invention

[0005] The present disclosure has been made in view of the above-mentioned problems. Therefore, a main object of the present disclosure is to provide a rotating electric machine having an improved structure with which design specifications can be easily changed and the size of the rotating electric machine can be minimized.

[0006] According to the present disclosure, a rotating electrical machine including an armature is provided. The armature includes an annular armature core and a multi-phase armature coil wound around the armature core. The armature core has a plurality of slots arranged circumferentially thereof. The armature coil is formed by a plurality of interconnected conductor groups. Each of the plurality of conductor groups comprises a bundle of a plurality of conductor segments. Furthermore, each of the plurality of conductor groups is generally U-shaped, having a pair of legs and a connecting portion. The pair of legs are received in a corresponding pair of slots in the armature core and are located at different radial positions within the corresponding slots. The connecting portion extends on one axial side of the armature core to connect the pair of legs. The connecting portion has a curved portion that curves radially relative to the circumferential direction. The plurality of conductor groups are arranged in pairs, such that each pair includes a first conductor group and a second conductor group, both belonging to the same phase of the armature coil. The circumferential spacing between the pair of legs of the first conductor group is greater than the circumferential spacing between the pair of legs of the second conductor group. In each pair of conductor groups, the connecting portions of the first and second conductor groups are arranged to axially overlap.

[0007] With this arrangement, a larger gap can be provided between each pair of circumferentially adjacent connecting portions of the electrical conductor groups, compared to a case where the connecting portions of the first and second electrical conductor groups are arranged so as not to axially overlap each other. Consequently, it becomes easier to change the design specifications of the rotating electrical machine, such as reducing the outer diameter of the armature, increasing the number of slots formed in the armature core, increasing the thickness of the electrical conductor segments, or increasing the number of electrical conductor segments included in each electrical conductor group.

[0008] Furthermore, according to the above arrangement, compared to a case where the connection portions of the first and second electrical conductor groups are arranged so as not to axially overlap each other, the gap between each pair of axially adjacent connection portions of the electrical conductor groups can be reduced, thereby reducing the size of the coil end portion of the armature coil. Here, the coil end portion includes all the connection portions of the electrical conductor groups.

[0009] Furthermore, in order to arrange the connection portions of the first and second conductor groups to overlap axially, the conductor groups are bent in the same manner at the connection portions. Thus, interference between each pair of adjacent connection portions of the conductor groups can be prevented.

[0010] Furthermore, since the connection portions of the first and second electric conductor groups arranged to overlap axially belong to the same phase of the armature coil, even when the first and second electric conductor groups accidentally come into contact with each other, occurrence of discharge can be suppressed.

[0011] In another embodiment, for each conductor group, the conductor segments constituting the conductor group may be arranged in a predetermined arrangement order along a radial direction at a pair of legs of the conductor group so as to be radially aligned with each other in corresponding slots of the armature core. At the connection portion of the conductor group, the conductor segments constituting the conductor group are arranged parallel to each other to maintain the arrangement order of the conductor segments at the pair of legs of the conductor group in the corresponding slots.

[0012] By the above arrangement, the electrical conductor segments can be bent in the same manner, thereby facilitating the manufacture of the armature. In addition, the electrical conductor segments can be arranged in a circumferential direction at the connecting portion, thereby reducing the axial width of the connecting portion.

[0013] The bent portions of the connecting portions of the first electrical conductor group may be arranged to be aligned with each other in the circumferential direction. The circumferential spacing between the bent portions of the connecting portions of the first electrical conductor group may be set to be greater than or equal to the circumferential spacing between the slots of the armature core and less than or equal to twice the circumferential spacing between the slots. The bent portions of the connecting portions of the second electrical conductor group may also be arranged to be aligned with each other in the circumferential direction. The circumferential spacing between the bent portions of the connecting portions of the second electrical conductor group may also be set to be greater than or equal to the circumferential spacing between the slots of the armature core and less than or equal to twice the circumferential spacing between the slots.

[0014] By the above arrangement, the axial width of the coil end portion constituted by all the connecting portions of the electrical conductor group can be reduced.

[0015] For each conductor group, one of the pair of legs of the conductor group can be received radially outside of a corresponding slot of the armature core, and the other of the pair of legs can be received radially inside of another corresponding slot of the armature core. For each conductor group, a radial extension extending in the radial direction can be formed in the bent portion of the connecting portion of the conductor group, and the conductor segments constituting the conductor group in the radial extension are arranged to be aligned with each other in the circumferential direction. The radial extensions of the connecting portion of the first conductor group can be arranged to be aligned with each other in the circumferential direction; the radial extensions of the connecting portion of the second conductor group can be arranged to be aligned with each other in the circumferential direction. The following relationship is satisfied: Rc×2×π / S≤N×Hc≤Rc×2×π / (S / 2), where Rc is the distance from the central axis of the armature core to the radial center of each slot, S is the number of slots formed in the armature core, N is the number of conductor segments included in each conductor group, and Hc is the radial thickness of each conductor segment in the corresponding slot of the armature core.

[0016] With the above configuration, the axial width of the coil end portion constituted by all the connection portions of the electric conductor group can be reduced more effectively.

[0017] A gap may be provided between each pair of circumferentially adjacent bends of the connecting portion of the electrical conductor set.

[0018] The bends in the connecting portion are typically formed by bending a conductor segment. Therefore, the bends in the connecting portion are more likely to induce large strains and damage the insulation coating of the conductor segment than other portions of the connecting portion. However, if a gap is provided between each pair of circumferentially adjacent bends in the connecting portion of the conductor set, electrical insulation between different phases of the armature coil can still be ensured.

[0019] For each conductor group, one of the pair of legs of the conductor group can be received radially outside of a corresponding slot of the armature core, and the other of the pair of legs can be received radially inside of another corresponding slot of the armature core. The following relationship can be satisfied: Wc×2<Hc×N, where Wc is the circumferential width of each conductor segment in the corresponding slot of the armature core, Hc is the radial thickness of each conductor segment in the corresponding slot of the armature core, and N is the number of conductor segments included in each conductor group.

[0020] With the above configuration, the axial width of the connecting portion of the electric conductor group can be reduced more effectively.

[0021] The armature coil may be a three-phase coil having three phase windings connected in a star shape to define a neutral point therebetween. A first electrical conductor group and a second electrical conductor group, each of which is a phase winding forming the armature coil, may be connected in series. The first electrical conductor group may be connected closer to the neutral point than the second electrical conductor group.

[0022] With this configuration, the second electrical conductor group has a higher potential than the first electrical conductor group. Furthermore, as described above, in each pair of electrical conductor groups, the second electrical conductor group is located axially inward of and covered by the first electrical conductor group. This ensures a sufficient distance between the second electrical conductor group and other electrical conductor groups belonging to different phases of the armature coil than the second electrical conductor group, thereby improving the insulation properties of the armature coil.

[0023] At a connection portion of each pair of electrical conductor sets, an axially inner side surface of the first electrical conductor set and an axially outer side surface of the second electrical conductor set may be arranged in surface contact with each other.

[0024] With this arrangement, a larger contact area can be ensured between the axially inner surface of the first electrical conductor group and the axially outer surface of the second electrical conductor group than when they are arranged in point contact or line contact with each other. Therefore, damage to the insulating coating of the electrical conductor segments constituting the first electrical conductor group and the second electrical conductor group due to contact between the connecting portions can be suppressed.

[0025] Each of the electrical conductor segments may include a body formed of a conductive material and an insulating coating covering a surface of the body. The insulating coating may be formed of an electrically insulating material having voids formed therein.

[0026] With the above configuration, when the insulating coating of the conductor segments is subjected to external forces or vibrations, for example, the voids formed in the insulating coating may collapse, significantly degrading the insulating properties of the insulating coating. However, as described above, the connecting portions of each pair of conductor groups are arranged to axially overlap each other; a gap is provided between each pair of circumferentially adjacent bends in the connecting portions of the conductor groups. Therefore, despite the insulating coating being formed from an electrically insulating material having voids formed therein, the insulating properties of the insulating coating can still be maintained.

[0027] At the connection portion of each pair of electrical conductor groups, the electrical conductor segments constituting the first electrical conductor group may be axially opposed to the electrical conductor segments constituting the second electrical conductor group and spaced apart at a substantially constant interval.

[0028] With the above arrangement, it is possible to prevent damage to the insulating coating of the electric conductor section while suppressing an increase in the axial width of the coil end portion constituted by all the connection portions of the electric conductor group.

[0029] Each conductor group may include a bundle of three conductor segments. The armature coil may be a three-phase coil having three-phase windings connected together in a star shape. Each phase winding of the armature coil may include four winding units connected in parallel to each other, and each winding unit includes a pair of first conductor groups and a second conductor group connected in series to each other. The plurality of slots of the armature core may include pairs of in-phase slots. Each pair of in-phase slots includes two circumferentially adjacent slots corresponding to the same one in the phase winding of the armature coil. In each pair of in-phase slots, the four winding units forming the corresponding phase winding of the armature coil may be arranged so that the number of legs of the conductor group of the four winding units received in one of the pair of in-phase slots is equal to the number of legs of the conductor group of the four winding units received in the other of the pair of in-phase slots.

[0030] With the above arrangement, the four winding units can be evenly accommodated in a pair of in-phase slots, thereby ensuring electromagnetic balance and suppressing circulating current in the armature. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a cross-sectional view of a rotating electric machine according to an exemplary embodiment.

[0032] Figure 2 It is a top view of the stator of the rotating electrical machine.

[0033] Figure 3 This is a schematic diagram illustrating the structure of a stator core and stator coils of a stator.

[0034] Figure 4A and Figure 4B It is a perspective view showing a pair of a first electric conductor group and a second electric conductor group for forming a stator coil from opposite sides in the axial direction.

[0035] Figure 5A and Figure 5B is a perspective view showing a pair of a first electrical conductor group and a second electrical conductor group from their radial side and axial side, respectively.

[0036] Figure 6 is an enlarged cross-sectional view of a conductor segment.

[0037] Figure 7 This is an enlarged perspective view of a turn portion of an electric conductor group forming a stator coil.

[0038] Figure 8 Schematic diagram showing arrangement of conductor segments at a bend in a conductor group.

[0039] Figure 9 is a perspective view showing the stator core and the assembled electric conductor groups before the electric conductor groups are inserted into the slots of the stator core.

[0040] Figure 10 is a perspective view showing the electric conductor group and the stator core after the electric conductor group is inserted into the slots of the stator core.

[0041] Figure 11A is a perspective view of a portion of a stator developed in the circumferential direction.

[0042] Figure 11B is a top view of a portion of the stator developed in the circumferential direction.

[0043] Figure 12A is a schematic diagram illustrating the arrangement of a pair of first and second electrical conductor groups in corresponding slots of a stator core.

[0044] Figure 12B The diagram shows the formation of the corresponding slots in the stator core. Figure 12A A schematic diagram of the arrangement of conductor segments of a first conductor set is shown.

[0045] Figure 13 Schematic diagram showing the connection pattern of the U-phase winding of the stator coil.

[0046] Figure 14 It is a schematic circuit diagram of the stator coil.

[0047] Figure 15A is an enlarged cross-sectional view of an electric conductor segment according to a first variant.

[0048] Figure 15B is an enlarged cross-sectional view of another electrical conductor segment according to the first variant.

[0049] Figure 16Ais a schematic diagram showing a desired arrangement of electrical conductor segments at a bend in an electrical conductor set according to a second variation.

[0050] Figure 16B is a schematic diagram showing another desired arrangement of electrical conductor segments at a turning portion of an electrical conductor set according to a second variation.

[0051] Figure 16C is a schematic diagram illustrating an undesirable arrangement of electrical conductor segments at a bend of an electrical conductor set according to a second variation.

[0052] Figure 17A and Figure 17B 1 and 2 are schematic diagrams showing together an example in which each phase winding of a stator coil according to a third modification is configured as a short-pitch winding wound in a wave winding manner.

[0053] Figure 18A 1 is a schematic diagram showing an example in which each phase winding of the stator coil according to the third modification is configured as a wave-wound full-pitch winding.

[0054] Figure 18B 1 is a schematic diagram showing an example in which each phase winding of the stator coil according to the third modification is configured as a wave-wound short-pitch winding.

[0055] Figure 19A 1 is a schematic diagram showing an example in which each phase winding of the stator coil according to the third modification is configured as a lap-wound full-pitch winding.

[0056] Figure 19B 1 is a schematic diagram showing an example in which each phase winding of the stator coil according to the third modification is configured as a lap-wound short-pitch winding.

[0057] Figure 20A 、 Figure 20B and Figure 20C is a schematic diagram showing alternative cross-sectional shapes of electrical conductor segments according to a fourth variation.

[0058] Figure 21 is a schematic circuit diagram of a stator coil according to a fifth modification.

[0059] Figure 22 is a perspective view showing a bridging wire employed in a stator according to a sixth modification. DETAILED DESCRIPTION

[0060] Hereinafter, exemplary embodiments will be described with reference to the accompanying drawings. It should be noted that for clarity and understanding, identical components having identical functions are marked with identical reference numerals as much as possible throughout the overall description, and to avoid redundancy, identical components will not be described repeatedly.

[0061] Figure 1An overall structure of a rotating electric machine according to an exemplary embodiment is shown.

[0062] In this embodiment, the rotating electric machine is configured as an electric motor 10 used in a vehicle. Specifically, electric motor 10 is a three-phase permanent magnet synchronous motor. In other words, electric motor 10 is a brushless motor. Furthermore, electric motor 10 may include only one three-phase coil belonging to a single system, or two three-phase coils belonging to two respective systems.

[0063] like Figure 1 As shown, the motor 10 includes a housing 20 , a stator 30 fixed to the housing 20 and serving as an armature in this embodiment, a rotor 40 configured to rotate relative to the stator 30 , and a rotating shaft 11 on which the rotor 40 is fixed.

[0064] In addition, in the following, the direction in which the center axis O of the rotating shaft 11 extends will be referred to as the axial direction (indicated by a double-headed arrow Y1 in the figure); the direction radially extending from the center axis O of the rotating shaft 11 will be referred to as the radial direction (indicated by a double-headed arrow Y2 in the figure); and the direction extending along a circle whose center is located on the center axis O of the rotating shaft 11 will be referred to as the circumferential direction (indicated by a double-headed arrow Y3 in the figure).

[0065] The housing 20 is cylindrical and houses both the stator 30 and the rotor 40. A pair of bearings 23 and 24 are provided in the housing 20, and the rotating shaft 11 is rotatably supported by the bearings 23 and 24. The axis of the inner peripheral surface of the housing 20 coincides with the central axis O of the rotating shaft 11.

[0066] The rotor 40 forms part of the magnetic circuit formed in the motor 10. The rotor 40 has one or more pairs of magnetic poles arranged in the circumferential direction and is radially opposed to the stator 30. More specifically, in the present embodiment, the rotor 40 has twelve magnetic poles (i.e., the number of magnetic pole pairs of the rotor 40 is equal to six). Alternatively, the number of magnetic poles of the rotor 40 may be set to another value depending on the design specifications of the motor 10.

[0067] The rotor 40 includes a rotor core 41 formed of a magnetic material and permanent magnets 42 fixed to the rotor core 41 .

[0068] More specifically, in this embodiment, rotor 40 includes twelve permanent magnets 42 whose polarity alternates in the circumferential direction. Permanent magnets 42 are respectively embedded in twelve magnet receiving holes, each of which is formed in the rotor core 41 along the axial direction. That is, in this embodiment, rotor 40 is configured as an IPM (Interior Permanent Magnet) rotor. Alternatively, rotor 40 may be configured as an SPM (Surface Permanent Magnet) rotor. As another alternative, rotor 40 may be configured as a field coil rotor.

[0069] In the center hole of the rotor core 41 , the rotation shaft 11 is fixedly inserted so that the rotor 40 can rotate together with the rotation shaft 11 around the center axis O of the rotation shaft 11 .

[0070] The stator 30 is cylindrical and arranged along the inner periphery of the housing 20 in a substantially axially central portion of the housing 20. The stator 30 is fixed to the inner peripheral surface of the housing 20 such that the central axis thereof coincides with the central axis O of the rotating shaft 11.

[0071] The stator 30 also constitutes a part of the magnetic circuit formed in the motor 10. Figure 2 As shown, the stator 30 has an annular stator core (or armature core) 31, which is arranged radially outside the rotor 40 so as to radially face the rotor 40 and a three-phase stator coil (or armature coil) 32 wound on the stator core 31.

[0072] It should be noted that when illustrating the stator coil 32 in the drawings, among the edge lines representing the boundaries between surfaces having different orientations, only those edge lines that are particularly important for representing the three-dimensional shape of the stator coil 32 are depicted. It should also be noted that the edge lines representing the radial outer contour of the stator coil 32 are depicted as solid lines in the drawings.

[0073] like Figure 3 As shown, the stator core 31 includes an annular back yoke (or back core) 33 and a plurality of teeth 34 arranged at predetermined intervals in the circumferential direction, with each tooth 34 protruding radially inward from the back yoke 33. A slot 35 is formed between each pair of circumferentially adjacent teeth 34. In other words, the stator core 31 has a plurality of slots 35 formed at equal intervals in the circumferential direction. The stator coils 32 are wound around the teeth 34 so as to be received in the slots 35. Furthermore, the number of teeth 34 is equal to the number of slots 35.

[0074] In the present embodiment, the number of slots 35 (or the number of teeth 34) per magnetic pole of the rotor 40 having twelve magnetic poles and per phase of the three-phase stator coil 32 is equal to 2. In other words, the slot multiplier is equal to 2. Thus, the total number of slots 35 formed in the stator core 31 is equal to 72 (i.e., 2×12×3). In addition, the seventy-two slots 35 include pairs of U-phase slots Su1, Su2, V-phase slots Sv1, Sv2, and W-phase slots Sw1, Sw2 arranged sequentially and repeatedly in the circumferential direction (see FIG. 1 ). Figure 12A ).

[0075] In this embodiment, the stator core 31 is composed of a laminated member formed by laminating a plurality of annular magnetic steel sheets (or core sheets) in the axial direction. Alternatively, the stator core 31 may be composed of a plurality of stator core segments arranged adjacent to each other in the circumferential direction.

[0076] The stator coil 32 includes a U-phase winding, a V-phase winding, and a W-phase winding that are star-connected (or Y-connected) to define a neutral point therebetween (see FIG. Figure 14 ). In operation, the stator coils 32 generate magnetic flux when supplied with three-phase AC power.

[0077] In the present embodiment, the stator coil 32 is formed by inserting a plurality of generally U-shaped electrical conductor segments 52 into the slots 35 of the stator core 31 from a first axial side of the stator core 31, and joining each pair of corresponding ends of the electrical conductor segments 52 that protrude outside the slots 35 on the second axial side of the stator core 31. Each electrical conductor segment 52 is obtained by cutting and plastically deforming an electrical conductor having a generally rectangular cross-sectional shape and a constant thickness into a generally "U" shape.

[0078] Specifically, in this embodiment, Figure 4A and Figure 4B As shown, each phase winding of the stator coil 32 is formed by a plurality of generally U-shaped electrical conductor groups 51. The electrical conductor groups 51 include two types of electrical conductor groups 51 having different sizes and being paired to overlap each other. Each pair of electrical conductor groups 51 includes a first electrical conductor group 51a located on the outside and a second electrical conductor group 51b located on the inside. For each pair of electrical conductor groups 51, both the first electrical conductor group 51a and the second electrical conductor group 51b of the pair are connected to the same one of the U-phase, V-phase and W-phase terminals, and thus belong to the same one of the U-phase, V-phase and W-phase terminals of the stator coil 32. In addition, Figure 4A and Figure 4B 1 and 2 are perspective views showing a pair of first and second electric conductor groups 51 a and 51 b from opposite sides in the axial direction before they are mounted to the stator core 31 .

[0079] In addition, if Figure 5A and Figure 5BAs shown, each conductor group 51 includes a plurality of (eg, four in this embodiment) substantially U-shaped conductor segments 52 bundled together. Figure 5A and Figure 5B 1 is a perspective view showing a pair of first and second electrical conductor groups 51a and 51b before they are mounted on the stator core 31, respectively, from their radial and axial sides. Figure 5A and Figure 5B Furthermore, the conductor segments 52 of each conductor group 51 are not depicted individually in the figures.

[0080] like Figure 3 As shown, the conductor segments 52 have a generally rectangular cross-sectional shape. In each slot 35 of the stator core 31, the conductor segments 52 are radially aligned in a row such that the longer sides of the rectangular cross-sections of the conductor segments 52 radially face each other.

[0081] refer to Figure 3 In the present embodiment, each electric conductor group 51 is configured to satisfy the following relationship: Wc×2<Hc×N, where Wc is the circumferential width of each electric conductor segment 52 in the corresponding slot 35 of the stator core 31, Hc is the radial thickness of each electric conductor segment 52 in the corresponding slot 35 of the stator core 31, and N is the number of electric conductor segments 52 included in each electric conductor group 51.

[0082] Furthermore, in the present embodiment, each electric conductor group 51 is formed by bending the group 51 of electric conductor segments 52 in a bundled state into a substantially “U” shape using a forming die.

[0083] like Figure 6 As shown, each conductor segment 52 includes a body 52a formed of a conductive material (e.g., copper) and an insulating coating 52b covering the surface of the body 52a. In this embodiment, the insulating coating 52b is formed of an electrically insulating material (e.g., resin) having voids formed therein.

[0084] As shown in Figures 4 and 5, each conductor group 51 has: a pair of straight portions (or legs) 53, which are respectively received in a pair of grooves 35 circumferentially separated from each other at predetermined intervals; and a turning portion (or connecting portion) 54, which connects the pair of straight portions 53.

[0085] The straight portions 53 are formed to extend straight in the axial direction. The straight portions 53 are parallel to each other and spaced a predetermined distance apart. The axial length of the straight portions 53 is set to be greater than the axial length of the stator core 31. Each straight portion 53 is received in a corresponding one of the slots 35 of the stator core 31, and its ends protrude axially from the corresponding slot 35. In addition, the spacing L1 between the straight portions 53 of the first electrical conductor group 51a is set to be greater than the spacing L2 between the straight portions 53 of the second electrical conductor group 51b.

[0086] For each of the electrical conductor groups 51 (ie, the first electrical conductor group 51a and the second electrical conductor group 51b), a pair of straight portions 53 of the electrical conductor group 51 are respectively received in the corresponding slots 35 of the stator core 31 so as to be different from each other in radial positions. More specifically, as shown in FIG. Figure 12A and Figure 12B As shown, one of the pair of straight portions 53 is received radially outside of one corresponding slot 35 of the stator core 31 , while the other of the pair of straight portions 53 is received radially inside of the other corresponding slot 35 of the stator core 31 .

[0087] Furthermore, for each electrical conductor group 51, the electrical conductor segments 52 constituting the electrical conductor group 51 are arranged in a predetermined arrangement order along the radial direction at a pair of straight portions 53 of the electrical conductor group 51 so as to be radially aligned with each other in the corresponding slots 35. For example, Figure 12B At one of the pair of straight portions 53 shown, the conductor segments 52 are arranged in the corresponding slot 35 in the order of U1a→U1b→U1c→U1d from the radial inside; Figure 12B At the other of the pair of straight portions 53 shown, the electric conductor segments 52 are also arranged in the corresponding slot 35 in the order of U1 a → U1 b → U1 c → U1 d from the radial inside.

[0088] like Figure 2 and Figures 4A to 4B As shown, in each of the electric conductor groups 51 (ie, the first electric conductor group 51a and the second electric conductor group 51b), the turn portion 54 is formed to extend in the circumferential direction and is connected to the axial end of the straight portion 53 at its circumferential end. Figure 7 As shown in FIG. 1 , the turning portion 54 is formed in the shape of a ridge whose circumferential center is higher than its circumferential ends. The circumferential ends of the turning portion 54 are respectively connected to the straight portion 53 so as to be inclined at a predetermined angle to the extending direction (or axial direction) of the straight portion 53. More specifically, as shown in FIG. Figure 4A and Figure 7 As shown, each circumferential end portion of the turn portion 54 is inclined relative to the extension direction (or axial direction) of the straight portion 53, so that the angle α between the circumferential end portion and the extension direction of the straight portion 53 is equal to a predetermined angle (e.g., approximately 120°). In addition, the predetermined angle is set to be equal for both the first electrical conductor group 51a and the second electrical conductor group 51b.

[0089] In addition, if Figure 12A and Figure 12B As shown in FIG. 1 , the bend portion 54 connects a pair of straight portions 53 located at different radial positions. Figure 2 As shown, the turning portion 54 has a curved portion that is repaired (or bent) in a substantially "S" shape when viewed in the axial direction. Figures 4A to 4B and Figure 7 As shown, each conductor group 51 is bent so that the axial inner surface of the turn portion 54 of the conductor group 51 connected to the circumferential inner surface of the straight portion 53 of the conductor group 51 faces the axial end surface of the stator core 31 .

[0090] More specifically, in each of the electrical conductor groups 51 (i.e., the first electrical conductor group 51a and the second electrical conductor group 51b), the turn portion 54 has: a first circumferential end connected to one of the pair of straight portions 53 located radially inward; and a second circumferential end connected to one of the pair of straight portions 53 located radially outward. The turn portion 54 extends from the first circumferential end to the vicinity of its center portion along the circumferential direction. In addition, as Figure 2 and Figure 7 As shown, the turn portion 54 has a first bend 55 that bends from the radial inside to the radial outside relative to the circumferential direction near the center of the turn portion 54. The first bend 55 is bent to such an extent that the turn portion 54 is parallel to the radial direction, that is, to such an extent that all the conductor segments 52 forming the turn portion 54 are aligned with each other in the circumferential direction.

[0091] Therefore, if Figure 2 and Figures 7 and 8 As shown in FIG. 5 , a radially extending portion 56 extending in the radial direction is formed near the center of the turning portion 54. Figure 7 As shown, radially extending portion 56 corresponds to the vertex of turn portion 54 located axially farthest from stator core 31 in turn portion 54. That is, in the range from the first circumferential end to radially extending portion 56, turn portion 54 extends obliquely relative to the axial direction and away from stator core 31.

[0092] In addition, if Figure 2 As shown, the radially extending portion 56 is connected to the second bent portion 57 of the turn portion 54 that bends from the radial direction toward the circumferential direction. More specifically, the second bent portion 57 is bent at an acute angle in a hairpin curve shape so that a portion of the second bent portion 57 protrudes radially outward from the slot 35 of the stator core 31. Starting from the second bent portion 57, the turn portion 54 extends along the circumferential direction to its second circumferential end. In addition, as shown in FIG. Figure 7As shown, the turn portion 54 extends toward the stator core 31 at an inclination relative to the axial direction within a range from the radially extending portion 56 to the second circumferential end thereof.

[0093] In the present embodiment, the curvature radius (or fillet radius R) of the second curved portion 57 is set to be smaller than the curvature radius of the first curved portion 55. Therefore, in the turn portion 54, the curved portion having a smaller curvature radius (i.e., the second curved portion 57) is located radially outwardly relative to the curved portion having a larger curvature radius (i.e., the first curved portion 55).

[0094] In addition, if Figure 2 As shown, the protrusion amount of the second bent portion 57 (i.e., the amount by which the second bent portion 57 protrudes radially outward from the slot 35 of the stator core 31) is set to be within the range of the back yoke 33 of the stator core 33. In other words, the protrusion amount is set so that the entire second bent portion 57 is located radially inside the radial outer periphery of the stator core 31.

[0095] On the other hand, Figure 2 As shown, the first bent portion 55 does not protrude radially inward from the slot 35 of the stator core 31. That is, the amount by which the turn portion 54 protrudes radially outward from the slot 35 of the stator core 31 is set to be greater than the amount by which the turn portion 54 protrudes radially inward from the slot 35. In other words, the stator coil 32 only protrudes radially outward from the slot 35 of the stator core 31, and does not protrude radially inward.

[0096] As described above, in the present embodiment, the first curved portion 55 , the radially extending portion 56 , and the second curved portion 57 together constitute the substantially S-shaped curved portion of the turn portion 54 .

[0097] In addition, in this embodiment, the rotor 40 is configured to Figure 2 The blank arrow in the figure indicates the intended direction of rotation (i.e., Figure 2 The turn portion 54 extends radially outward as it extends in the rotation direction of the rotor 40. That is, of the pair of circumferential ends of the turn portion 54, the second circumferential end on the radially outer side is located forward (downstream) from the first circumferential end on the radially inner side in the rotation direction of the rotor 40.

[0098] Figure 4 and Figure 7As shown, for each pair of first and second conductor groups 51a, 51b, the turns 54 of the first and second conductor groups 51a, 51b are arranged so as to overlap each other in the axial direction. Furthermore, the turns 54 of the second conductor group 51b are located axially inward (or on the stator core 31 side) of the turns 54 of the first conductor group 51a. Furthermore, the turns 54 of the first and second conductor groups 51a, 51b are arranged so that the axially inner surfaces of the turns 54 of the first conductor group 51a face the axially outer surfaces of the turns 54 of the second conductor group 51b, and are axially spaced apart therefrom at a substantially constant interval. In other words, the turns 54 of the first and second conductor groups 51a, 51b are arranged so as to extend parallel to each other.

[0099] More specifically, if Figure 4A and Figure 7 As shown, the inclination angle α between the turn portion 54 and the straight portion 53 in the first electrical conductor group 51a is substantially equal to the inclination angle α between the turn portion 54 and the straight portion 53 in the second electrical conductor group 51b. Furthermore, the first bend 55, radial extension 56, and second bend 57 in the turn portion 54 of the first electrical conductor group 51a are located at substantially the same circumferential positions as the first bend 55, radial extension 56, and second bend 57 in the turn portion 54 of the second electrical conductor group 51b. Furthermore, the radius of curvature of the first bend 55, the length of the radial extension 56, and the radius of curvature of the second bend 57 in the turn portion 54 of the first electrical conductor group 51a are set to be substantially equal to the radius of curvature of the first bend 55, the length of the radial extension 56, and the radius of curvature of the second bend 57 in the turn portion 54 of the second electrical conductor group 51b. That is, the bends of the turn portions 54 of the first electrical conductor group 51a and the bend portions of the turn portions 54 of the second electrical conductor group 51b have the same substantially "S" shape.

[0100] Through the above construction, Figure 8 As shown, at the turning portion 54 of each pair of the first electrical conductor group 51a and the second electrical conductor group 51b, the electrical conductor segments 52 constituting the first electrical conductor group 51a are arranged parallel to the electrical conductor segments 52 constituting the second electrical conductor group 51b. In addition, the axial inner side surfaces (i.e., Figure 8 The lower side surface in the middle) are respectively connected to the axial outer side surface of the electric conductor segment 52 constituting the second electric conductor group 51b (ie, Figure 8 The upper side surfaces in the middle) are axially opposed and separated by a substantially constant interval.

[0101] Furthermore, the axially inner surfaces of the conductor segments 52 constituting the first conductor group 51 a may alternatively be arranged to be in surface contact with the axially outer surfaces of the conductor segments 52 constituting the second conductor group 51 b. That is, the axially inner surfaces of the conductor segments 52 constituting the first conductor group 51 a may not be separated from the axially outer surfaces of the conductor segments 52 constituting the second conductor group 51 b.

[0102] In addition, if Figure 2 As shown, the substantially S-shaped bends of the turn portions 54 of the electrical conductor group 51 are arranged to be aligned with each other in the circumferential direction. In the present embodiment, the circumferential spacing between the bends of the turn portions 54 of the electrical conductor group 51 is set to be greater than or equal to the circumferential spacing between the slots 35 of the stator core 31, and less than or equal to twice the circumferential spacing between the slots 35.

[0103] More specifically, if Figure 2 and Figure 7 As shown, the radial extensions 56 of the turn portions 54 of the first electrical conductor group 51a are arranged to be aligned with each other in the circumferential direction. The circumferential spacing between the radial extensions 56 of the turn portions 54 of the first electrical conductor group 51a is set to be greater than or equal to the circumferential spacing between the slots 35, and less than or equal to twice the circumferential spacing between the slots 35. Similarly, the radial extensions 56 of the turn portions 54 of the second electrical conductor group 51b are also arranged to be aligned with each other in the circumferential direction. The circumferential spacing between the radial extensions 56 of the turn portions 54 of the second electrical conductor group 51b is also set to be greater than or equal to the circumferential spacing between the slots 35, and less than or equal to twice the circumferential spacing between the slots 35.

[0104] In addition, a predetermined gap C1 is provided between each pair of circumferentially adjacent radially extending portions 56 of the turn portion 54 of the electrical conductor group 51. In the present embodiment, the stator 30 is configured to satisfy the following relationship:

[0105] Rc×2×π / S≤N×Hc≤Rc×2×π / (S / 2)

[0106] Wherein, Rc is the distance from the central axis of the stator core 31 (or the central axis O of the rotating shaft 11) to the radial center of each slot 35, S is the number of slots 35 formed in the stator core 31, N is the number of electrical conductor segments 52 included in each electrical conductor group 51, and Hc is the radial thickness of each electrical conductor segment 52 in the corresponding slot 35 of the stator core 31.

[0107] In addition, the distance Rc is Figure 2 and Figure 3 Shown. Figure 2 It can be seen that the distance Rc can be regarded as the distance from the central axis of the stator core 31 to the radial center position of the radial extension 56 of the turn portion 54 of the electrical conductor group 51. Figure 3 It can be seen that the distance Rc can also be considered as the distance from the central axis of the stator core 31 to the boundary between the two electrical conductor groups 51 in each slot 35 . Figure 3 The radial thickness Hc of each conductor segment 52 is shown in FIG. Figure 8 It can be seen that N×Hc represents the circumferential dimension of each radial extension portion 56 (or vertex portion) of the turn portion 54 of the electrical conductor set 51 .

[0108] Reference again Figure 2 and Figure 7 , the first bends 55 of the turn portions 54 of the first electrical conductor group 51a are arranged to be aligned with each other in the circumferential direction. The circumferential spacing between the first bends 55 of the turn portions 54 of the first electrical conductor group 51a is set to be greater than or equal to the circumferential spacing between the slots 35, and less than or equal to twice the circumferential spacing between the slots 35. Similarly, the first bends 55 of the turn portions 54 of the second electrical conductor group 51b are also arranged to be aligned with each other in the circumferential direction. The circumferential spacing between the first bends 55 of the turn portions 54 of the second electrical conductor group 51b is also set to be greater than or equal to the circumferential spacing between the slots 35, and less than or equal to twice the circumferential spacing between the slots 35.

[0109] Furthermore, the second bends 57 of the turn portions 54 of the first electrical conductor group 51a are arranged so as to be aligned with one another in the circumferential direction. The circumferential spacing between the second bends 57 of the turn portions 54 of the first electrical conductor group 51a is set to be greater than or equal to the circumferential spacing between the slots 35 and less than or equal to twice the circumferential spacing between the slots 35. Similarly, the second bends 57 of the turn portions 54 of the second electrical conductor group 51b are also arranged so as to be aligned with one another in the circumferential direction. The circumferential spacing between the second bends 57 of the turn portions 54 of the second electrical conductor group 51b is also set to be greater than or equal to the circumferential spacing between the slots 35 and less than or equal to twice the circumferential spacing between the slots 35.

[0110] In this embodiment, if Figure 12B As shown, for each conductor group 51, the conductor segments 52 constituting the conductor group 51 are arranged parallel to each other at the turning portion 54 of the conductor group 51 to maintain the arrangement order of the conductor segments 52 at a pair of straight portions 53 of the conductor group 51 in the corresponding slots 35 of the stator core 31.

[0111] like Figure 9 As shown, the straight portion 53 of each pair of axially overlapping first and second electrical conductor groups 51a and 51b is located from the first axial side (ie, Figure 9 The upper side in the middle) is inserted into the corresponding slot 35 of the stator core 31. Then, it protrudes to the second axial side of the stator core 31 (i.e., Figure 10The distal end portion of the straight portion 53 on the outer side of the corresponding groove 35 on the lower side in the middle is twisted and bent at a predetermined pitch in the circumferential direction, thereby forming a connecting portion 58.

[0112] As shown in Figure 11 and Figure 13 As shown, each connection portion 58 includes a first terminal portion 58 a that is circumferentially bent outward from the corresponding pair of straight portions 53 and a second terminal portion 58 b that is circumferentially bent inward from the corresponding pair of straight portions 53 .

[0113] in addition, Figure 11A 3 is a perspective view of a portion of the stator 30 developed in the circumferential direction. Figure 11B is a top view of a portion of the stator 30 developed in the circumferential direction. It should be noted that for simplicity, Figure 11A and Figure 11B Only some of the connecting portions 58 are shown in FIG. 1 , and virtually all of the slots 35 of the stator core 31 have corresponding straight portions 53 of the electrical conductor set 51 received therein and corresponding connecting portions 58 protruding therefrom.

[0114] For the electric conductor segments 52 constituting the electric conductor group 51, the bending directions of the terminal portions 58a, 58b are changed based on the predetermined connection pattern of the stator coil 32. In addition, Figure 11A and Figure 11B 1 and 2. A manner of changing the bending direction of the terminal portions 58a, 58b for the electrical conductor segments 52 is shown in FIG.

[0115] Each pair of corresponding terminal portions 58a, 58b of the electrical conductor group 51 is connected by, for example, TIG welding, laser welding, ultrasonic welding, or the like. Thus, the connecting portions 58 are axially engaged with and fixed to the stator core 31; thus, the electrical conductor group 51 is fixed to the stator core 31 via the connecting portions 58 and the bent portions 54. As a result, the straight portions 53 of the electrical conductor group 51 are restricted from axial movement relative to the stator core 31, thereby being securely retained in the corresponding slots 35 of the stator core 31.

[0116] Furthermore, through the connection portions 58 , the electric conductor groups 51 are electrically connected in a predetermined connection pattern, thereby forming a U-phase winding, a V-phase winding, and a W-phase winding of the stator coil 32 .

[0117] Next, refer to FIG. 12A to FIG. 12B and Figure 13 The connection mode of the stator coil 32 is described in detail.

[0118] Figure 12A The arrangement of a pair of first and second electrical conductor sets 51 a and 51 b in corresponding slots 35 of the stator core 31 is shown. Figure 12B Shows the composition Figure 12AThe arrangement of the conductor segments 52 of the first conductor set 51 a in the corresponding slots 35 of the stator core 31 is shown. Figure 13 FIG shows a connection pattern of the U-phase winding of the stator coil 32. Figure 12A and Figure 13 , the first electrical conductor set 51a is shown with solid lines, and the second electrical conductor set 51b is shown with dashed lines.

[0119] In this embodiment, if FIG. 12A to FIG. 12B and Figure 13 As shown, each phase winding of the stator coil 32 is configured as a distributed winding.

[0120] In addition, if FIG. 12A to FIG. 12B As shown, for each electrical conductor group 51 (i.e., the first electrical conductor group 51a and the second electrical conductor group 51b), one of the pair of straight portions 53 of the electrical conductor group 51 is received radially outside of one corresponding slot 35, while the other of the pair of straight portions 53 is received radially inside of the other corresponding slot 35. In addition, for each pair of the first electrical conductor group 51a and the second electrical conductor group 51b, the turn portion 54 of the first electrical conductor group 51a is formed at a seven-slot pitch, while the turn portion 54 of the second electrical conductor group 51b is formed at a five-slot pitch.

[0121] like Figure 13 As shown, in each electrical conductor group 51, a pair of straight portions 53 located at different radial positions pass through the first axial side (ie, Figure 13 On the other hand, on the second axial side of the stator core 31 (ie, Figure 13 On the lower side in the figure), each pair of corresponding straight portions 53 belonging to a different one of the electrical conductor groups 51 and located at the same radial position is connected by one of the connecting portions 58.

[0122] In addition, if Figure 13 As shown, each phase winding of the stator coil 32 is wound in a distributed winding manner, more specifically, a wave winding manner, on the stator core 31. In addition, each phase winding of the stator coil 32 is configured as a full-pitch winding whose pitch is equal to the magnetic pole pitch.

[0123] As mentioned above, in this embodiment, Figure 14 As shown, the U-phase winding, V-phase winding, and W-phase winding of the stator coil 32 are connected in a star shape to define a neutral point therebetween. Furthermore, the first electrical conductor group 51a and the second electrical conductor group 51b, which form the same of the U-phase winding, V-phase winding, and W-phase winding of the stator coil 32, are connected in series. Furthermore, the first electrical conductor group 51a can be connected closer to the neutral point than the second electrical conductor group 52.

[0124] According to this embodiment, the following advantageous effects can be achieved.

[0125] In this embodiment, the electric motor 10 includes a stator 30 (or armature). The stator 30 includes a stator core 31 (or an annular armature core) and three-phase stator coils 32 (or armature coils) wound around the stator core 31. The stator core 31 has a plurality of slots 35 arranged along its circumferential direction. The stator coils 32 are formed by a plurality of interconnected conductor groups 51. Each conductor group 51 includes a bundle of multiple (e.g., four, in this embodiment) conductor segments 52. Each of the conductor groups 51 is generally U-shaped, having a pair of straight portions 53 (or legs) and a turn portion 54 (or connecting portion). The straight portions 53 are respectively received in a corresponding pair of slots 35 of the stator core 31, so as to be located at different radial positions within the corresponding slots 35. The turn portion 54 extends on a first axial side of the stator core 31 to connect the pair of straight portions 53. The turn portion 54 has a generally S-shaped bend that curves radially relative to the circumferential direction. The plurality of electrical conductor groups 51 are arranged in pairs, such that each pair of electrical conductor groups 51 includes a first electrical conductor group 51a and a second electrical conductor group 51b of the same phase, both belonging to the stator coil 32. The circumferential spacing between the pair of straight portions 53 of the first electrical conductor group 51a is greater than the circumferential spacing between the pair of straight portions 53 of the second electrical conductor group 51b. In each pair of electrical conductor groups 51, the turn portions 54 of the first electrical conductor group 51a and the second electrical conductor group 51b are arranged to axially overlap each other.

[0126] With the above arrangement, a larger gap can be provided between each pair of circumferentially adjacent turns 54 of the electric conductor groups 51, compared to a case where the turns 54 of the first and second electric conductor groups 51a, 51b are arranged so as not to axially overlap each other. Therefore, it becomes easier to change the design specifications of the electric motor 10, such as reducing the outer diameter of the stator 30, increasing the number of slots 35 formed in the stator core 31, increasing the thickness of the electric conductor segments 52, or increasing the number of electric conductor segments 52 included in each electric conductor group 51.

[0127] Furthermore, with the above arrangement, compared to a case where the turns 54 of the first and second electric conductor groups 51a and 51b are arranged so as not to axially overlap each other, the gap between each pair of axially adjacent turns 54 of the electric conductor group 51 can be reduced, thereby reducing the size of the coil end portion of the stator coil 32. Furthermore, the coil end portion includes all the turns 54 of the electric conductor group 51.

[0128] Furthermore, in order to arrange the turns 54 of the first and second conductor groups 51a and 51b to overlap axially, the conductor groups 51 are bent in the same manner at the respective turns 54. Therefore, interference between each pair of adjacent turns 54 of the conductor groups 51 can be prevented.

[0129] In addition, since the turning portions 54 of the first electric conductor group 51a and the second electric conductor group 51b, which are arranged to axially overlap each other, belong to the same phase of the stator coil 32, discharge can be suppressed even when the first electric conductor group 51a and the second electric conductor group 51b accidentally contact each other.

[0130] In the present embodiment, for each electrical conductor group 51, the electrical conductor segments 52 constituting the electrical conductor group 51 are arranged in a predetermined arrangement order along the radial direction at a pair of straight portions 53 of the electrical conductor group 51 so as to be radially aligned with each other in the corresponding slots 35 of the stator core 31. Furthermore, at the turn portions 54 of the electrical conductor group 51, the electrical conductor segments 52 constituting the electrical conductor group 51 are arranged parallel to each other so as to maintain the arrangement order of the electrical conductor segments 52 at the pair of straight portions 53 of the electrical conductor group 51 in the corresponding slots 35.

[0131] With the above arrangement, the conductor segments 52 can be bent in the same manner, thereby facilitating the manufacture of the stator 30. Furthermore, the conductor segments 52 can be arranged in the circumferential direction at the turns 54, thereby reducing the axial width of the turns 54.

[0132] In this embodiment, the substantially S-shaped bends of the turns 54 of the first electrical conductor group 51 a are arranged to align with one another in the circumferential direction. The circumferential spacing between the bends of the turns 54 of the first electrical conductor group 51 a is greater than or equal to the circumferential spacing between the slots 35 of the stator core 31, and less than or equal to twice the circumferential spacing between the slots 35. The substantially S-shaped bends of the turns 54 of the second electrical conductor group 51 b are also arranged to align with one another in the circumferential direction. The circumferential spacing between the bends of the turns 54 of the second electrical conductor group 51 b is also greater than or equal to the circumferential spacing between the slots 35 of the stator core 31, and less than or equal to twice the circumferential spacing between the slots 35.

[0133] By the above arrangement, the axial width of the coil end portion constituted by all the turning portions 54 of the electric conductor group 51 can be reduced.

[0134] In this embodiment, for each conductor set 51, one of the pair of straight portions 53 of the conductor set 51 is received radially outside of a corresponding slot 35 in the stator core 31, and the other of the pair of straight portions 53 is received radially inside of the other corresponding slot 35 in the stator core 31. Radial extensions 56 extending radially may be formed in the curved portions of the turns 54 of the conductor sets 51. Within these radial extensions 56, the conductor segments 52 comprising the conductor sets 51 are arranged circumferentially aligned. Furthermore, the radial extensions 56 of the turns 54 of the first conductor set are arranged circumferentially aligned; and the radial extensions 56 of the turns 54 of the second conductor set are also arranged circumferentially aligned. The stator 30 is configured to satisfy the relationship: Rc×2×π / S≤N×Hc≤Rc×2×π / (S / 2).

[0135] With the above configuration, the axial width of the coil end portion constituted by all the turn portions 54 of the electric conductor group 51 can be reduced more effectively.

[0136] In the present embodiment, a predetermined gap C1 is provided between each pair of circumferentially adjacent bends of the turn portion 54 of the electric conductor group 51 .

[0137] The bends of the turns 54 are typically formed by bending the conductor segments 52. Therefore, large strains are more likely to be induced at the bends of the turns 54 than at other portions of the turns 54, and the insulating coating 52b of the conductor segments 52 is more likely to be damaged. However, when a gap C1 is provided between each pair of circumferentially adjacent bends of the turns 54 of the conductor group 51, more specifically, between each pair of circumferentially adjacent radially extending portions 56 of the bends, electrical insulation between the U-phase winding, the V-phase winding, and the W-phase winding of the stator coil 32 can still be ensured.

[0138] In this embodiment, for each electrical conductor group 51, one of the pair of straight portions 53 of the electrical conductor group 51 is received radially outside of a corresponding slot 35 of the stator core 31, and the other of the pair of straight portions 53 is received radially inside of the other corresponding slot 35 of the stator core 31. Furthermore, each electrical conductor group 51 is configured to satisfy the relationship Wc×2<Hc×N. Furthermore, each electrical conductor group 51 is bent so that the axially inner surface of the turn portion 54 of the electrical conductor group 51, which is connected to the circumferential inner surface of the straight portion 53 of the electrical conductor group 51, faces the axial end surface of the stator core 31.

[0139] With the above configuration, the axial width of the turn portion 54 of the electric conductor group 51 can be reduced more effectively.

[0140] In this embodiment, the stator coil 32 is a three-phase coil having a U-phase winding, a V-phase winding, and a W-phase winding connected in a star shape to define a neutral point therebetween. The first electric conductor group 51a and the second electric conductor group 51b of the same one of the U-phase winding, the V-phase winding, and the W-phase winding forming the stator coil 32 are connected in series with each other. In addition, the first electric conductor group 51a can be connected at a position closer to the neutral point than the second electric conductor group 51b (see FIG. Figure 14 ).

[0141] With this configuration, the second electrical conductor group 51b has a higher potential than the first electrical conductor group 51a. Furthermore, as described above, in this embodiment, in each pair of electrical conductor groups 51, the second electrical conductor group 51b is located axially inward of the first electrical conductor group 51a and is covered by the first electrical conductor group 51a. Therefore, a sufficient distance can be ensured between the second electrical conductor group 51b and the other electrical conductor groups 51 belonging to a different phase of the stator coil 32 than the second electrical conductor group 51b, thereby improving the insulation performance of the stator coil 32.

[0142] In this embodiment, at the turns 54 of each pair of conductor groups 51, the axially inner surface of the first conductor group 51a and the axially outer surface of the second conductor group 51b are arranged to be axially opposite to each other and spaced apart at a substantially constant interval. That is, the turns 54 of the first conductor group 51a and the second conductor group 51b are arranged to extend parallel to each other. Therefore, the turns 54 of the first conductor group 51a and the second conductor group 51b can be prevented from contacting each other, thereby preventing the insulating coatings 52b of the conductor segments 52 constituting the first conductor group 51a and the second conductor group 51b from being damaged by contact between the turns 54. Alternatively, at the turns 54 of each pair of conductor groups 51, the axially inner surface of the first conductor group 51a and the axially outer surface of the second conductor group 51b can be arranged to be in surface contact with each other. In this case, compared with the case where the axial inner surface of the first electrical conductor group 51a and the axial outer surface of the second electrical conductor group 51b are arranged in point contact or line contact with each other, a larger contact area between them can be ensured; therefore, the insulating coating 52b of the electrical conductor segments 52 constituting the first electrical conductor group 51a and the second electrical conductor group 51b can be suppressed from being damaged due to contact between the turning portions 54.

[0143] In this embodiment, each electric conductor segment 52 includes a main body 52a formed of a conductive material and an insulating coating 52b covering a surface of the main body 52a. The insulating coating 52b is formed of an electrically insulating material having voids formed therein.

[0144] With the above configuration, when the insulating coating 52b of the conductor segment 52 is subjected to, for example, external force or vibration, the voids formed in the insulating coating 52b may collapse, significantly degrading the insulating performance of the insulating coating 52b. However, as described above, in this embodiment, the turns 54 of each pair of conductor groups 51 are arranged so as to axially overlap each other; a predetermined gap C1 is provided between each pair of circumferentially adjacent bends of the turns 54 of the conductor groups 51. Therefore, although the insulating coating 52b is formed of an electrically insulating material having voids formed therein, the insulating performance of the insulating coating 52b can still be ensured.

[0145] In this embodiment, at the turning portion 54 of each pair of electrical conductor groups 51, the electrical conductor segments 52 constituting the first electrical conductor group 51a are axially opposed to the electrical conductor segments 52 constituting the second electrical conductor group 51b and are spaced apart at a substantially constant interval (see FIG. Figure 8 ).

[0146] With the above arrangement, it is possible to prevent damage to the insulating coating 52 b of the electric conductor segment 52 while suppressing an increase in the axial width of the coil end portion constituted by all the turn portions 54 of the electric conductor group 51 .

[0147] In this embodiment, in each electric conductor group 51, the curved portion of the turn portion 54 is configured to include a first curved portion 55, a radially extending portion 56, and a second curved portion 57. The curvature radius (or fillet radius R) of the second curved portion 57 is set to be smaller than the curvature radius of the first curved portion 55. In addition, the second curved portion 57 is located radially outside the first curved portion 55 (see FIG. Figure 2 ).

[0148] With the above configuration, all of the second bent portions 57 of the turn portions 54 of the electric conductor group 51 can be arranged with a relatively small radius of curvature, and therefore, the insulating coatings 52 b of the electric conductor segments 52 constituting the electric conductor group 51 at the radially outer portion of the stator coil 32 are more easily damaged during the bending of the electric conductor group 51. Therefore, a sufficient gap can be ensured between each pair of circumferentially adjacent second bent portions 57 of the turn portions 54 of the electric conductor group 51, thereby improving the insulation characteristics of the stator coil 32.

[0149] In the present embodiment, the turn portion 54 of the electric conductor group 51 is formed so that the amount of the turn portion 54 protruding radially outward from the slot 35 of the stator core 31 is greater than the amount of the turn portion 54 protruding radially inward from the slot 35. In other words, the stator coil 32 only protrudes radially outward from the slot 35 of the stator core 31, and does not protrude radially inward (see FIG. Figure 2 ).

[0150] With the above configuration, it is possible to prevent the stator coil 32 from coming into contact with the rotor 40. Furthermore, it is possible to suppress an increase in the axial width of the coil end portion constituted by all the turns 54 of the electrical conductor group 51 while ensuring a sufficient gap between each pair of circumferentially adjacent bends of the turns 54 of the electrical conductor group 51.

[0151] In the present embodiment, the rotor 40 is configured to rotate in a predetermined direction (ie, Figure 2 The turn portion 54 of each electrical conductor group 51 extends radially outward as it extends in the rotational direction of the rotor 40. That is, of the pair of circumferential ends of the turn portion 54, the second circumferential end on the radially outer side is located forward of the first circumferential end on the radially inner side in the rotational direction of the rotor 40.

[0152] With the above configuration, when the stator coil 32 is cooled by oil, the oil flowing out of the rotor 40 easily passes through the gaps between the turns 54 of the electrical conductor group 51, thereby effectively cooling the stator coil 32. Otherwise, when the stator coil 32 is cooled by air, the air flowing out of the rotor 40 easily passes through the gaps between the turns 54 of the electrical conductor group 51. Therefore, air resistance can be reduced, thereby suppressing wind noise generated during the rotation of the rotor 40.

[0153] While the above particular embodiments have been shown and described, it will be understood by those skilled in the art that various variations, changes, and modifications may be made without departing from the spirit of the present disclosure.

[0154] [First variant]

[0155] In the embodiment described above, each electric conductor segment 52 includes a main body 52a formed of a conductive material and an insulating coating 52b covering the surface of the main body 52a. The insulating coating 52b is formed of an electrically insulating material having voids formed therein (see FIG. Figure 6 ).

[0156] As an alternative, Figure 15A As shown, each conductor segment 52 may further include an insulating coating 52c having no voids formed therein. Furthermore, the insulating coating 52c having no voids may be provided to cover the surface of the body 52a, and the insulating coating 52b having voids may be provided to cover the outer surface of the insulating coating 52c.

[0157] As another alternative, Figure 15B As shown, an insulating coating layer 52b having voids may be provided to cover the surface of the body 52a, and an insulating coating layer 52c having no voids may be provided to cover the outer surface of the insulating coating layer 52b.

[0158] [Second variant]

[0159] In the above-described embodiment, Figure 8 As shown, in each pair of first electrical conductor group 51a and second electrical conductor group 51b, the electrical conductor segments 52 constituting the first electrical conductor group 51a are aligned in a row, so that the axial inner surface and the axial outer surface of the turning portion 54 of the first electrical conductor group 51a are flat; the electrical conductor segments 52 constituting the second electrical conductor group 51b are aligned in a row, so that the axial inner surface and the axial outer surface of the turning portion 54 of the second electrical conductor group 51b are flat; and the axial inner surface of the turning portion 54 of the first electrical conductor group 51a and the axial outer surface of the turning portion 54 of the second electrical conductor group 51b are axially opposite to each other and separated by a substantially constant interval.

[0160] Alternatively, as 16A to 16C As shown, in each pair of the first electrical conductor group 51a and the second electrical conductor group 51b, the electrical conductor segments 52 constituting the first electrical conductor group 51a can be aligned so that the axial inner surface and the axial outer surface of the turning portion 54 of the first electrical conductor group 51a are wavy; and the electrical conductor segments 52 constituting the second electrical conductor group 51b can be aligned so that the axial inner surface and the axial outer surface of the turning portion 54 of the second electrical conductor group 51b are wavy. Moreover, as Figure 16A and Figure 16B As shown, in this case, it is desirable that the axially inner surface of the turn portion 54 of the first electrical conductor group 51a and the axially outer surface of the turn portion 54 of the second electrical conductor group 51b are axially opposite to each other and spaced apart at a substantially constant interval. Figure 16C As shown, it is undesirable that the intervals between the axially inner surface of the turn portion 54 of the first electrical conductor group 51 a and the axially outer surface of the turn portion 54 of the second electrical conductor group 51 b are uneven.

[0161] [Third variant]

[0162] In the above-described embodiment, FIG. 12A to FIG. 12B and Figure 13 In the embodiment, each phase winding of the stator coil 32 is configured as a full-pitch distributed winding. In addition, for each pair of the first electrical conductor group 51a and the second electrical conductor group 51b, the turn portion 54 of the first electrical conductor group 51a is formed at a seven-slot pitch, while the turn portion 54 of the second electrical conductor group 51b is formed at a five-slot pitch.

[0163] However, each phase winding of the stator coil 32 may be wound in another manner instead. In addition, the turn portions 54 of the electric conductor group 51 may be formed at pitches other than the seven-slot and five-slot pitches instead.

[0164] For example, Figure 17A and Figure 17BAs shown, each phase winding of the stator coil 32 can be alternatively configured as a short-pitch distributed winding. Specifically, in this example, as shown in FIG. Figure 17A As shown, for each conductor group 51 (i.e., the first conductor group 51a and the second conductor group 51b), one of the pair of straight portions 53 of the conductor group 51 is received radially outside a corresponding slot 35, while the other of the pair of straight portions 53 is received radially inside the other corresponding slot 35. In addition, for each pair of the first conductor group 51a and the second conductor group 51b, the turn portion 54 of the first conductor group 51a is formed at a six-slot pitch, while the turn portion 54 of the second conductor group 51b is formed at a four-slot pitch. In addition, as shown Figure 17B As shown, in each electrical conductor group 51, a pair of straight portions 53 located at different radial positions pass through the first axial side (ie, Figure 17B On the other hand, on the second axial side of the stator core 31 (ie, Figure 17B On the lower side in the figure), each pair of corresponding straight portions 53 belonging to different ones of the electrical conductor groups 51 and located at the same radial position is connected by one of the connecting portions 58. In addition, as Figure 17B As shown, each phase winding of the stator coil 32 is wound on the stator core 31 in a distributed winding manner, more specifically, in a wave winding manner.

[0165] As an alternative, Figure 18A and Figure 18B As shown, each phase winding of the stator coil 32 can be wound on the stator core 31 in a wave winding manner. Figure 18A In the example shown, each phase winding of the stator coil 32 is formed as a wave-wound full-pitch winding. In addition, for each pair of the first electrical conductor group 51a and the second electrical conductor group 51b, the turn portion 54 of the first electrical conductor group 51a is formed at a seven-slot pitch, while the turn portion 54 of the second electrical conductor group 51b is formed at a five-slot pitch. On the other hand, Figure 18B In the illustrated example, each phase winding of the stator coil 32 is configured as a wave-wound short-pitch winding. Furthermore, for each pair of the first electrical conductor group 51a and the second electrical conductor group 51b, the turns 54 of the first electrical conductor group 51a are formed at a six-slot pitch, while the turns 54 of the second electrical conductor group 51b are formed at a four-slot pitch.

[0166] As an alternative, Figure 19A and Figure 19B As shown, each phase winding of the stator coil 32 can be wound on the stator core 31 in a lap-wound manner. Figure 19AIn the example shown, each phase winding of the stator coil 32 is formed as a stacked full-pitch winding. In addition, for each pair of the first electrical conductor group 51a and the second electrical conductor group 51b, the turn portion 54 of the first electrical conductor group 51a is formed at a seven-slot pitch, while the turn portion 54 of the second electrical conductor group 51b is formed at a five-slot pitch. On the other hand, Figure 19B In the illustrated example, each phase winding of the stator coil 32 is configured as a stacked short-pitch winding. Furthermore, for each pair of the first electrical conductor group 51a and the second electrical conductor group 51b, the turns 54 of the first electrical conductor group 51a are formed at a six-slot pitch, while the turns 54 of the second electrical conductor group 51b are formed at a four-slot pitch.

[0167] [Fourth variant]

[0168] In the embodiment described above, each conductor segment 52 has a substantially rectangular cross-sectional shape (see FIG. Figure 6 ).

[0169] However, each electrical conductor segment 52 may alternatively have other cross-sectional shapes, such as 20A to 20C Circular, oval or barrel cross-sectional shapes as shown.

[0170] Furthermore, in the case where each electric conductor segment 52 has a circular, oval or barrel-shaped cross-sectional shape, it is possible to 20A to 20C As shown, the radial thickness Hc and the circumferential width Wc of each electric conductor segment 52 in the corresponding slot 35 of the stator core 31 are defined. More specifically, in this case, the radial thickness Hc can be represented by the maximum radial thickness of each electric conductor segment 52; and the circumferential width Wc can be represented by the maximum circumferential width of each electric conductor segment 52.

[0171] [Fifth variant]

[0172] In the embodiment described above, the same first electric conductor group 51a and second electric conductor group 51b in the U-phase winding, the V-phase winding, and the W-phase winding forming the stator coil 32 are connected in series with each other (see FIG. Figure 14 ).

[0173] As an alternative, Figure 21 As shown, each of the U-phase winding, the V-phase winding, and the W-phase winding of the stator coil 32 may include a plurality of (eg, Figure 21 The paired electrical conductor groups 51 are connected in parallel to each other, and each pair of electrical conductor groups 51 includes a first electrical conductor group 51a and a second electrical conductor group 51b connected in series to each other.

[0174] [Sixth Variant]

[0175] In the embodiment described above, a bridge wire may be used to connect each pair of corresponding portions of the stator coil 32 positioned apart from each other in the circumferential direction; these portions may include, for example, the ends of the U-phase winding, the V-phase winding, and the W-phase winding of the stator coil 32, the neutral terminal, and the U-phase terminal, the V-phase terminal, and the W-phase terminal of the stator coil 32. In this case, as Figure 22 As shown, preferably, the radially innermost portions of the terminal portions 58a, 58b of the conductor segments 52 of the conductor groups 51 are connected by bridge wires 100. Therefore, the bridge wires 100 can be prevented from protruding radially inward or radially outward from the conductor groups 51, thereby suppressing an increase in the radial size of the stator 30 and ensuring electrical insulation of the bridge wires 100 from the housing 20 and the rotor 40. In addition, the bridge wires 100 can share a common insulating coating with the connecting portion 58 (or the terminal portions 58a, 58b of the conductor segments 52).

[0176] [Seventh Variant]

[0177] In the embodiment described above, the number N of electric conductor segments 52 included in each electric conductor group 51 is set to 4. In addition, the same first electric conductor group 51 a and second electric conductor group 51 b of the U-phase winding, V-phase winding, and W-phase winding forming the stator coil 32 are connected in series with each other.

[0178] Alternatively, the number N of the electric conductor segments 52 included in each electric conductor group 51 may be set to 3. In addition, each of the U-phase winding, the V-phase winding, and the W-phase winding of the stator coil 32 may include four winding units connected in parallel to each other, and each winding unit includes a pair of first electric conductor groups 51a and second electric conductor groups 51b connected in series to each other. In addition, as described in the above embodiment, the slots 35 of the stator core 31 include pairs of in-phase slots Su1, Su2, Sv1, Sv2, Sw1, Sw2 (see Figure 12A ). Each pair of same-phase slots includes two circumferentially adjacent slots 35, corresponding to the same one of the U-phase winding, V-phase winding and W-phase winding of the stator coil 32. In each pair of same-phase slots (for example, Su1, Su2), four winding units forming the corresponding phase winding (for example, U-phase winding) of the stator coil 32 are arranged, so that the number of straight portions 53 of the electrical conductor group 51 of the four winding units accommodated in one of the pair of same-phase slots (for example, Su1) is equal to the number of straight portions 53 of the electrical conductor group 51 of the four winding units accommodated in the other of the pair of same-phase slots (for example, Su2). Through the above arrangement, the four winding units can be evenly accommodated in a pair of same-phase slots, thereby ensuring electromagnetic balance and suppressing circulating currents in the stator 30.

[0179] [Eighth Variant]

[0180] In the embodiment described above, the U-phase winding, V-phase winding, and W-phase winding of the stator coil 32 are star-connected. However, the U-phase winding, V-phase winding, and W-phase winding of the stator coil 32 may be delta-connected instead.

Claims

1. A rotating electric machine comprising an armature, wherein the armature comprises an annular armature core and a multi-phase armature coil wound around the armature core. in, The armature core has a plurality of slots arranged along a circumferential direction of the armature core; The armature coil is formed by a plurality of electric conductor groups connected to each other, each of the electric conductor groups comprising a bundle of a plurality of electric conductor segments; Each of the plurality of electrical conductor groups is substantially U-shaped to have a pair of leg portions and a connecting portion, the pair of leg portions being respectively received in a corresponding pair of slots of the armature core and being located at different radial positions in the corresponding slots, the connecting portion extending on one axial side of the armature core to connect the pair of leg portions, the connecting portion having a bent portion bent radially relative to the circumferential direction; The plurality of electrical conductor groups are paired such that each pair of the electrical conductor groups includes a first electrical conductor group and a second electrical conductor group both belonging to the same phase of the armature coil; The circumferential spacing between a pair of legs of the first electrical conductor set is greater than the circumferential spacing between a pair of legs of the second electrical conductor set; In each pair of the electrical conductor groups, the connecting portions of the first electrical conductor group and the second electrical conductor group are arranged to axially overlap each other; For each of the electrical conductor groups, at least at the connecting portion of the electrical conductor group and those portions of a pair of the legs in the electrical conductor group that are respectively received in a corresponding pair of slots of the armature core, the electrical conductor segments constituting the electrical conductor group are arranged to overlap each other in a direction perpendicular to the axial direction of the armature core; For each of the electrical conductor sets, one of the pair of legs of the electrical conductor set is received radially outside a corresponding slot of the armature core, and the other of the pair of legs is received radially inside another corresponding slot of the armature core; In each of the electrical conductor groups, the connecting portion includes: (i) a first end connected to one of the pair of leg portions located on the radially inner side; (ii) a second end connected to one of the pair of leg portions located on the radially outer side; and (iii) a first bent portion located closer to the first end than the second end and bent from the radially inner side to the radially outer side relative to the circumferential direction. and (iv) a second curved portion located closer to the second end than the first curved portion and curved from the radial direction toward the circumferential direction; The curvature radius of the second curved portion is set to be smaller than the curvature radius of the first curved portion.

2. The rotating electrical machine according to claim 1, wherein For each of the electrical conductor groups, the electrical conductor segments constituting the electrical conductor group are arranged in a predetermined arrangement order in a radial direction at a pair of the legs of the electrical conductor group so as to be radially aligned with each other in corresponding slots of the armature core; and At the connection portion of the conductor set, the conductor segments constituting the conductor set are arranged parallel to each other to maintain an arrangement order of the conductor segments at a pair of legs of the conductor set in corresponding slots.

3. The rotating electrical machine according to claim 1, wherein The bent portions of the connecting portion of the first electrical conductor group are arranged to be aligned with each other in the circumferential direction; a circumferential spacing between the bent portions of the connecting portion of the first electrical conductor group being greater than or equal to a circumferential spacing between the slots of the armature core and less than or equal to twice the circumferential spacing between the slots; The bent portions of the connecting portions of the second electrical conductor set are also arranged to be aligned with each other in the circumferential direction; and The circumferential spacing between the bent portions of the connecting portion of the second electrical conductor group is also greater than or equal to the circumferential spacing between the slots of the armature core, and less than or equal to twice the circumferential spacing between the slots.

4. The rotating electrical machine according to claim 2, wherein: The bent portions of the connecting portion of the first electrical conductor group are arranged to be aligned with each other in the circumferential direction; a circumferential spacing between the bent portions of the connecting portion of the first electrical conductor group being greater than or equal to a circumferential spacing between the slots of the armature core and less than or equal to twice the circumferential spacing between the slots; The bent portions of the connecting portions of the second electrical conductor set are also arranged to be aligned with each other in the circumferential direction; and The circumferential spacing between the bent portions of the connecting portion of the second electrical conductor group is also greater than or equal to the circumferential spacing between the slots of the armature core, and less than or equal to twice the circumferential spacing between the slots.

5. The rotating electrical machine according to any one of claims 1 to 4, characterized in that For each of the electrical conductor groups, a radially extending portion extending in a radial direction is formed in the bent portion of the connecting portion of the electrical conductor group, and the electrical conductor segments constituting the electrical conductor group are arranged in alignment with each other in the circumferential direction in the radially extending portion; The radial extensions of the connecting portions of the first electrical conductor group are arranged to be aligned with each other in the circumferential direction, and the radial extensions of the connecting portions of the second electrical conductor group are arranged to be aligned with each other in the circumferential direction; and The following relations are satisfied: Rc×2×π / S≤N×Hc≤Rc×2×π / (S / 2) Wherein, Rc is the distance from the central axis of the armature core to the radial center of each of the slots, S is the number of the slots formed in the armature core, N is the number of the conductor segments included in each of the conductor groups, and Hc is the radial thickness of each of the conductor segments in the corresponding slot of the armature core.

6. The rotating electrical machine according to any one of claims 1 to 4, characterized in that A gap is provided between each pair of circumferentially adjacent bent portions of the connecting portion of the electrical conductor set.

7. The rotating electrical machine according to any one of claims 1 to 4, characterized in that For each of the electrical conductor sets, one of the pair of legs of the electrical conductor set is received radially outside a corresponding slot of the armature core, and the other of the pair of legs is received radially inside another corresponding slot of the armature core; The following relations are satisfied: Wc×2<Hc×N, Wherein, Wc is the circumferential width of each of the electrical conductor segments in the corresponding slot of the armature core, Hc is the radial thickness of each of the electrical conductor segments in the corresponding slot of the armature core, and N is the number of the electrical conductor segments included in each of the electrical conductor groups.

8. The rotating electrical machine according to any one of claims 1 to 4, characterized in that The armature coil is a three-phase coil having three-phase windings connected in a star shape to define a neutral point therebetween; The first electrical conductor group and the second electrical conductor group forming the same one of the phase windings of the armature coil are connected in series with each other; and The first electrical conductor set is connected at a position closer to the neutral point than the second electrical conductor set.

9. The rotating electrical machine according to any one of claims 1 to 4, characterized in that At the connection portion of each pair of the electrical conductor groups, the axially inner side surface of the first electrical conductor group and the axially outer side surface of the second electrical conductor group are arranged in surface contact with each other.

10. The rotating electrical machine according to any one of claims 1 to 4, characterized in that Each of the electrical conductor segments includes a body formed of a conductive material and an insulating coating covering a surface of the body; and The insulating coating is formed of an electrically insulating material having voids formed therein.

11. The rotating electrical machine according to any one of claims 1 to 4, characterized in that At the connection portion of each pair of the electrical conductor groups, the electrical conductor segments constituting the first electrical conductor group are axially opposed to the electrical conductor segments constituting the second electrical conductor group and are spaced apart at a substantially constant interval.

12. The rotating electrical machine according to any one of claims 1 to 4, characterized in that Each of said electrical conductor groups comprises a bundle of three electrical conductor segments; The armature coil is a three-phase coil having three-phase windings connected together in a star shape; Each of the phase windings of the armature coil includes four winding units connected in parallel to each other, and each of the winding units includes a pair of a first electrical conductor group and a second electrical conductor group connected in series to each other; The plurality of slots of the armature core include pairs of same-phase slots, each pair of same-phase slots including two circumferentially adjacent slots corresponding to the same phase winding of the armature coil; and In each pair of the in-phase slots, four winding units forming the corresponding phase winding of the armature coil are arranged so that the number of legs of the electrical conductor group of the four winding units received in one of the pair of in-phase slots is equal to the number of legs of the electrical conductor group of the four winding units received in the other of the pair of in-phase slots.

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