Rotor and rotating electric machine

Abstract

One embodiment of a rotor according to the present invention is a rotor for a rotating electric machine, said rotor rotating about the central axis. The rotor comprises: a rotor core provided with a plurality of slots arranged in the circumferential direction and penetrating in the axial direction; a plurality of conductor parts disposed in the slots; a pair of end rings positioned on one side and the other side of the rotor core in the axial direction, respectively, and connecting the plurality of conductor parts to each other; and a plurality of fixing parts. The slots each have an opening that opens to a core outer peripheral part of the rotor core and extends in the axial direction. The conductor parts each have a conductor outer peripheral part that faces the outside in the radial direction and is exposed to the outside in the radial direction from the opening. The plurality of fixing parts each fix the core outer peripheral part and the conductor outer peripheral part to each other. The plurality of fixing parts are discretely disposed in the axial direction.

Description

Rotor and rotating electric machine

[0001] The present invention relates to a rotor and a rotating electric machine.

[0002] A rotor for a rotating electric machine used as a drive source for an automobile may be a squirrel-cage rotor having a rotor core, conductors disposed in slots of the rotor core, and end rings that short-circuit the conductors. In a squirrel-cage rotor, it is necessary to prevent the conductors from coming off the slots due to centrifugal force. Japanese Patent Laid-Open Publication No. 59-117448 discloses a structure that prevents the conductors from coming off the slots by integrating the conductors and the end rings.

[0003] Japanese Patent Publication No. 59-117448

[0004] In recent years, there has been a trend toward smaller size and higher output for rotating electrical machines used as the drive source for automobiles, which inevitably requires higher speeds. In rotating electrical machines with conventional structures, there have been cases where it has not been possible to sufficiently prevent the conductors from coming off the slots during high speed rotation.

[0005] In view of the above circumstances, an object of the present invention is to provide a rotor and a rotating electric machine that can prevent conductor portions from coming off slots even during high-speed rotation.

[0006] One aspect of the rotor of the present invention is a rotor for a rotating electric machine that rotates about a central axis. The rotor includes a rotor core having a plurality of slots arranged circumferentially and penetrating in the axial direction, a plurality of conductor portions arranged in the slots, a pair of end rings located on one axial side and the other axial side of the rotor core, respectively, connecting the plurality of conductor portions, and a plurality of fixing portions. The slots have openings that open to the core outer periphery of the rotor core and extend in the axial direction. The conductor portions have conductor outer periphery portions that face radially outward and are exposed radially outward from the openings. The plurality of fixing portions fix the core outer periphery and the conductor outer periphery to each other. The plurality of fixing portions are arranged discretely in the axial direction.

[0007] One aspect of the rotating electric machine of the present invention includes the rotor described above and a stator surrounding the rotor from the outside in the radial direction.

[0008] According to one aspect of the present invention, it is possible to provide a rotor and a rotating electric machine that can prevent conductor portions from coming off slots even during high-speed rotation.

[0009] Fig. 1 is a cross-sectional view taken along the central axis of a rotating electric machine according to a first embodiment. Fig. 2 is a perspective view of a rotor according to the first embodiment. Fig. 3 is a cross-sectional view perpendicular to the central axis of the rotor according to the first embodiment. Fig. 4 is a schematic view of the outer circumferential surface of the rotor according to the first embodiment. Fig. 5 is a schematic view of the outer circumferential surface of a rotor according to a first modified example. Fig. 6 is a perspective view of a rotor according to a second embodiment. Fig. 7 is a schematic view of the outer circumferential surface of a rotor according to a comparative example.

[0010] A rotor 20 according to the present invention and a rotating electric machine 100 having the rotor 20 will be described in detail below with reference to the drawings. The Z axis is illustrated in each drawing as necessary. The Z axis is a direction parallel to the central axis J of the rotating electric machine 100. In the following description, the direction parallel to the central axis J of the rotating electric machine 100 will be simply referred to as the "axial direction," the radial direction centered on the central axis J will be simply referred to as the "radial direction," and the circumferential direction centered on the central axis J, i.e., around the axis of the central axis J, will be simply referred to as the "circumferential direction."

[0011] First Embodiment FIG. 1 is a cross-sectional view taken along a central axis J of a rotating electric machine 100 according to a first embodiment. The rotating electric machine 100 according to this embodiment is a squirrel-cage three-phase AC motor. The rotating electric machine 100 according to this embodiment is mounted on a vehicle powered by a rotating electric machine, such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHV), or an electric vehicle (EV), and is used as the power source thereof. The rotating electric machine 100 has both a function of outputting power as a motor and a function of generating electricity as a generator. The rotating electric machine 100 may also be used as either a motor or a generator. The configuration of the rotating electric machine 100 is not limited to that of this embodiment, and may be, for example, an AC motor with four or more phases.

[0012] The rotating electric machine 100 of this embodiment has a rotor 20 configured as a squirrel-cage rotor, a stator 10 that generates a rotating magnetic flux by an alternating current, and a housing 6 that accommodates the rotor 20 and the stator 10. In the rotating electric machine 100, a rotational force is generated in the rotor 20 by linkage between the rotating magnetic flux generated from the stator 10 and an induced current generated in a conductor portion 40 of the rotor 20 configured as a squirrel-cage rotor.

[0013] The housing 6 has a housing main body 6a, a bearing holder 6b, and a pair of bearings 8a, 8b. The housing main body 6a has a tubular portion 6d and a bottom plate portion 6e. The tubular portion 6d is cylindrical and has a center on the central axis J. The bottom plate portion 6e extends radially inward from the end of the tubular portion 6d on the other axial side (-Z side). The bottom plate portion 6e holds the bearing 8a. The bearing holder 6b covers the opening on one axial side (+Z side) of the housing main body 6a. The bearing holder 6b holds the bearing 8b.

[0014] The stator 10 is fixed to the inner peripheral surface of the cylindrical portion 6d. The stator 10 is annular and centered on the central axis J. The stator 10 surrounds the rotor 20 from the radially outer side. The stator 10 includes an annular stator core 11 and coils 12 attached to the stator core 11. The stator core 11 is formed by stacking multiple electromagnetic steel plates in the axial direction. The stator core 11 includes a cylindrical core back portion 11a centered on the central axis J and multiple stator teeth 11b that protrude radially inward from the inner peripheral surface of the core back portion 11a and are arranged in the circumferential direction. The coils 12 are attached to the stator teeth 11b. The coils 12 include three-phase coils, namely, U-phase, V-phase, and W-phase, through which AC current flows in different phases.

[0015] The rotor 20 rotates about the central axis J. The rotor 20 is rotatably supported by a pair of bearings 8a, 8b. The rotor 20 has a shaft 29, a rotor core 21, a plurality of conductor portions 40, a pair of end rings 50, and a pair of plate members 60. The shaft 29 is cylindrical and extends axially about the central axis J. The shaft 29 is supported by the pair of bearings 8a, 8b.

[0016] The rotor core 21 extends in the axial direction with, for example, a uniform cross section. The rotor core 21 is substantially circular when viewed in the axial direction. The outer peripheral surface of the rotor core 21 faces the inner peripheral surface of the stator 10 in the radial direction with a gap therebetween. The rotor core 21 is fixed to the shaft 29. The rotor core 21 also holds a plurality of conductor portions 40 and a pair of end rings 50.

[0017] The rotor core 21 is formed by stacking a plurality of electromagnetic steel sheets 21p in the axial direction. In this embodiment, the plurality of electromagnetic steel sheets 21p have the same shape. The plurality of electromagnetic steel sheets 21p are fixed to each other using a joining means such as caulking.

[0018] FIG. 2 is a perspective view of the rotor 20 of the first embodiment. FIG. 3 is a cross-sectional view of the rotor 20 of the first embodiment taken along a plane perpendicular to the central axis J of the rotor 20. As shown in FIG. 3, the rotor core 21 is provided with a central hole 21h penetrating in the axial direction and a plurality of slots 30. The central hole 21h is substantially circular and centered on the central axis J. A shaft 29 is inserted into the central hole 21h. A pair of protrusions 21c protruding radially inward is provided on the inner circumferential surface of the central hole 21h. Meanwhile, a pair of grooves 29g extending along the axial direction is provided on the outer circumferential surface of the shaft 29. The protrusions 21c are inserted into the grooves 29g. As a result, the rotor core 21 is positioned circumferentially with respect to the shaft 29.

[0019] The multiple slots 30 are arranged at equal intervals along the circumferential direction. The slots 30 extend in the axial direction with a uniform cross-sectional shape. The slots 30 extend radially and open at their radially outer ends to the outer core portion 21a of the rotor core 21. That is, the slots 30 have openings 30a that open to the outer core portion 21a and extend in the axial direction. Note that the outer core portion 21a here refers to the area of ​​the surface of the rotor core 21 that faces radially outward and faces the stator 10.

[0020] The rotor core 21 also has teeth 22 provided between circumferentially adjacent slots 30. That is, the slots 30 are located between circumferentially adjacent teeth 22. The multiple teeth 22 are arranged at equal intervals along the circumferential direction.

[0021] The conductor portion 40 is a rod-shaped portion that is disposed within the slot 30 and extends along the axial direction. The conductor portion 40 is made of a non-magnetic, conductive material such as an aluminum alloy. The conductor portion 40 is formed by die-casting into the slot 30. Therefore, the cross-sectional shape of the conductor portion 40 as viewed in the axial direction is substantially the same as the cross-sectional shape of the slot 30.

[0022] The conductor portion 40 has a conductor outer peripheral portion 40a exposed radially outward from the opening 30a. The conductor outer peripheral portion 40a faces radially outward and faces the stator 10. In addition, a plurality of welds (fixing portions) 70 that fix the core outer peripheral portion 21a and the conductor outer peripheral portion 40a to each other are provided on the outer peripheral surface of the rotor 20. In other words, the rotor 20 has the welds 70. The welds 70 will be described in detail later.

[0023] As shown in FIG. 1 , the conductor portions 40 extend linearly along the axial direction of the rotor core 21. The conductor portions 40 may extend at a slight circumferential incline relative to the axial direction. The length dimension of the conductor portions 40 is approximately equal to the axial dimension of the rotor core 21. One axial end and the other axial end of each of the multiple conductor portions 40 are connected to an end ring 50, respectively. As a result, the multiple conductor portions 40 lined up in the circumferential direction are short-circuited to each other. An induced current flows through the conductor portions 40 due to the rotational magnetic flux generated by the stator 10 when the rotor 20 rotates. The induced current flows axially through the conductor portions 40.

[0024] The end rings 50 are located on one axial side and the other axial side of the rotor core 21. The end rings 50 are annular and centered on the central axis J. The end rings 50 face the outer peripheral surface of the shaft 29 in the radial direction with a gap therebetween. The end rings 50 connect the multiple conductor portions 40 together. Like the conductor portions 40, the end rings 50 are made of a non-magnetic, conductive material such as an aluminum alloy. In this embodiment, the end rings 50 are formed integrally with the conductor portions 40 by die-cast molding.

[0025] The plate members 60 are plate-shaped and extend along a plane perpendicular to the central axis J. A pair of plate members 60 are located on one axial side and the other axial side of the rotor core 21, respectively, between the end faces and the end rings 50. When viewed axially, the plate members 60 have substantially the same shape as the electromagnetic steel plates 21p that constitute the rotor core 21. That is, the plate members 60 are provided with a plate center hole 60h and multiple plate slots 68, similar to those of the rotor core 21. When viewed axially, the plate center hole 60h overlaps with the central holes 21h of the rotor core 21. When viewed axially, the plate slots 68 overlap with the slots 30 of the rotor core 21.

[0026] The plate member 60 has a first surface 60a and a second surface 60b that face in opposite axial directions. The first surface 60a faces and contacts the end face of the rotor core 21 in the axial direction. The second surface 60b faces and contacts the end ring 50 in the axial direction. The second surface 60b is embedded by the end ring 50 when the end ring 50 is molded.

[0027] The second surface 60b is provided with a protrusion 61 that protrudes in the axial direction. The protrusion 61 is embedded in the end ring 50. When the rotor 20 rotates around the central axis J, centrifugal force is applied to the end ring 50 and the conductor portion 40. According to this embodiment, because the protrusion 61 of the plate member 60 is embedded in the end ring 50, the protrusion 61 can withstand the centrifugal force applied to the end ring 50. This makes it possible to suppress deformation and movement of the end ring 50 radially outward.

[0028] As shown in FIG. 2 , the boundary 20b between the outer core portion 21a and the outer conductor portion 40a extends linearly in the axial direction on the outer peripheral surface of the rotor 20. The multiple boundaries 20b are aligned in the circumferential direction. The multiple welds 70 are provided along the boundaries 20b. Some of the multiple welds 70 are aligned in the axial direction along one boundary 20b. That is, the multiple welds 70 are discretely arranged in the axial direction. Furthermore, some of the multiple welds 70 are aligned in the circumferential direction. Therefore, the multiple welds 70 are arranged in both the axial and circumferential directions on the outer peripheral surface of the rotor 20.

[0029] The opening 30a of one slot 30 has two edge portions that face each other in the circumferential direction. Therefore, the outer conductor portion 40a of one conductor portion 40 disposed in the opening 30a contacts the outer core portion 21a at two boundary portions 20b located on one circumferential side and the other circumferential side of the outer conductor portion 40a. In this embodiment, the welds 70 at these two boundary portions 20b are aligned in the axial direction. That is, among the multiple welds 70, the welds 70 located on one circumferential side of the outer conductor portion 40a and the welds 70 located on the other circumferential side of the outer conductor portion 40a overlap each other in the axial direction.

[0030] When the welded portions 70 of this embodiment are formed by laser welding, the welded portions 70 are formed, for example, by irradiating the boundary portion 20b between the core outer periphery 21a and the conductor outer periphery 40a with laser light to melt and re-solidify the rotor core 21 and the conductor portion 40. In particular, in this embodiment, the irradiation spot of the laser light is aligned with the boundary portion 20b, and the irradiation device and the rotor 20 are moved in the axial direction while repeatedly irradiating and stopping the laser light, thereby forming welded portions 70 that are discretely arranged in the axial direction. Note that the method of forming the welded portions 70 is not limited to this embodiment.

[0031] At the welded portion 70, a portion of the metallic material constituting the rotor core 21 and a portion of the metallic material constituting the conductor portion 40 are alloyed and fixed to each other when they are melted and solidified again. Furthermore, when the portion of the metallic material constituting the rotor core 21 and the portion of the metallic material constituting the conductor portion 40 are melted and solidified again, they become intertwined with each other, thereby providing an anchor effect and fixing them to each other. At the welded portion 70, the rotor core 21 and the conductor portion 40 are fixed to each other by the interaction of at least one of the above-mentioned alloying effect and the anchor effect, or a combination of these effects.

[0032] In the present embodiment, the fixing portion that fixes the core outer peripheral portion 21 a and the conductor outer peripheral portion 40 a to each other is a welded portion formed by welding. However, a fixing portion corresponding to the welded portion 70 of the present embodiment may be formed by a method other than welding (e.g., brazing).

[0033] When the rotor 20 is rotated at high speed, a large centrifugal force is applied to the conductor portion 40. According to this embodiment, the core outer peripheral portion 21a and the conductor outer peripheral portion 40a are fixed to each other by the welded portion 70, thereby preventing the conductor outer peripheral portion 40a from moving radially outward relative to the core outer peripheral portion 21a. This prevents the conductor portion 40 from coming off the slot 30 of the rotor core 21 due to the centrifugal force.

[0034] In particular, in this embodiment, a plurality of welded portions 70 are provided lined up in the axial direction, so that the conductor portions 40 can be fixed to the rotor core 21 over the entire axial length of the rotor core 21. As a result, the conductor portions 40 can be more reliably prevented from coming off the slots 30.

[0035] Fig. 4 is a schematic diagram of the outer peripheral surface of the rotor 20 of the first embodiment. Fig. 7 is a schematic diagram of the outer peripheral surface of a rotor 1020 of a comparative embodiment for explaining the effects of this embodiment.

[0036] As shown in Fig. 4 , the welded portion 70 of this embodiment is formed across several of the electromagnetic steel sheets 21p that make up the rotor core 21. Therefore, the welded portion 70 electrically connects the several electromagnetic steel sheets 21p. Note that Fig. 4 is merely a schematic diagram, and the number of electromagnetic steel sheets 21p joined by one welded portion 70 in Fig. 4 is merely an example.

[0037] 7, the rotor 1020 of the comparative embodiment differs from the rotor 20 of the present embodiment in the configuration of the welded portion 1070. The rotor 1020 of the comparative embodiment has the same configuration as the rotor 20 of the present embodiment except for the welded portion 1070.

[0038] The welded portion 1070 of the comparative example is formed over the entire axial length of the rotor core 21. Therefore, the welded portion 1070 is formed across all of the electromagnetic steel sheets 21p that make up the rotor core 21. The welded portion 1070 electrically connects all of the electromagnetic steel sheets 21p that make up the rotor core 21.

[0039] Generally, when the rotating electric machine 100 is driven to rotate the rotor 20, eddy currents are generated on the surface of the rotor 20, resulting in losses (eddy current losses) due to the eddy currents. In the rotor 1020 of the comparative embodiment shown in Fig. 7, the electromagnetic steel sheets 21p are conductive over the entire axial length of the rotor core 21, which increases the loop of the eddy currents EC. As a result, the eddy current losses of the rotating electric machine 100 increase in the rotor 1020 of the comparative embodiment.

[0040] In contrast, in the rotor 20 of this embodiment shown in Figure 4, the welds 70 are arranged discretely in the axial direction, so that the number of electromagnetic steel sheets 21p joined via the welds 70 can be reduced compared to the comparative embodiment. This makes it possible to reduce the size of eddy current loops that occur on the outer peripheral surface of the rotor 20, thereby reducing eddy current loss in the rotating electric machine 100. In other words, according to this embodiment, by arranging the welds 70 discretely in the axial direction, it is possible to provide a highly efficient rotating electric machine 100 in which eddy current loss is suppressed.

[0041] It is preferable that the number of electromagnetic steel sheets 21p joined to one weld 70 is two or more. By joining two or more electromagnetic steel sheets 21p to one weld 70, it becomes easier to firmly fix each weld 70 to the rotor core 21. It is also preferable that the axial dimension of each weld 70 is 30% or less of the axial dimension of the rotor core 21. By making the axial dimension of the weld 70 30% or less of the axial dimension of the rotor core 21, it is possible to sufficiently reduce the eddy current loop generated on the outer peripheral surface of the rotor core 21, and it is possible to sufficiently reduce eddy current loss in the rotating electric machine 100.

[0042] As shown in Fig. 2, the multiple welds 70 of this embodiment are arranged symmetrically with respect to the axial center of the rotor 20. In the rotor 20 of this embodiment, the multiple welds 70 lined up in the axial direction are arranged at equal intervals. Furthermore, the weld 70 located furthest to one axial side of the multiple welds 70 is arranged axially apart from the end ring 50 located on one axial side of the rotor core 21. Similarly, the weld 70 located furthest to the other axial side of the multiple welds is arranged axially apart from the end ring 50 located on the other axial side of the rotor core 21.

[0043] In this embodiment, the distance between the welded portion 70 located furthest on one axial side and the end ring 50 located on one axial side is equal to the distance between the welded portion 70 located furthest on the other axial side and the end ring 50 located on the other axial side.

[0044] Here, the axial distance between the welded portion 70 located closest to one axial side (or the other side) and the end ring 50 located on one axial side (or the other side) of the rotor core 21 is defined as a first distance dimension d1. The axial distance dimension between the plurality of welded portions 70 is defined as a second distance dimension d2.

[0045] In the present embodiment, the first distance dimension d1 is greater than the second distance dimension d2 (d1>d2). With this configuration, the multiple welds 70 are densely arranged near the axial center of the rotor core 21, relative to near one axial end of the rotor core 21 and near the other axial end of the rotor core 21.

[0046] In this embodiment, the conductor portion 40 is supported by the end rings 50 at both axial ends. Therefore, the amount of radially outward deformation of the conductor portion 40 due to centrifugal force is greatest near the axial center of the rotor core 21. According to this embodiment, the multiple welds 70 are arranged relatively densely near the axial center of the rotor core 21, and therefore the multiple welds 70 can firmly fix the conductor portion 40 near the axial center, where the amount of deformation of the conductor portion 40 is likely to be large. As a result, deformation of the conductor portion 40 can be effectively suppressed. Meanwhile, at the ends on one and the other axial sides, where deformation of the conductor portion 40 is more likely to be suppressed by the end rings 50, the number of welds 70 can be reduced, thereby reducing the work time required for the welding process.

[0047] This effect can be obtained at least on one axial side if the first distance d1 between the weld 70 located furthest on one axial side and the end ring 50 on one axial side (+Z) is greater than the second distance d2. Furthermore, when the distances between the multiple welds 70 are different from one another, this effect can be obtained to a certain extent or more if the first distance d1 is greater than the smallest axial distance between the multiple welds 70. In other words, it is sufficient that the axial distance between the weld 70 located furthest on one axial side among the multiple welds 70 and one of the pair of end rings 50 located on one axial side is greater than the smallest axial distance between the multiple welds 70.

[0048] 5 is a schematic diagram of the outer circumferential surface of a rotor 20A according to a modification of the first embodiment. The rotor 20A according to this modification differs from the embodiment described above mainly in the arrangement of the plurality of welds 70A, 70B.

[0049] In this embodiment, the welds 70A, 70B provided at the two boundaries 20b of one conductor outer peripheral portion 40a are offset in the axial direction. Here, of the multiple welds 70A, 70B, one located on one circumferential side of one conductor outer peripheral portion 40a is referred to as the first weld 70A, and the other located on the other circumferential side is referred to as the second weld 70B. In other words, the multiple welds 70A, 70B include the first weld 70A and the second weld 70B.

[0050] In this modification, the first welded portion 70A and the second welded portion 70B are positioned offset in the axial direction. According to this modification, the multiple axially stacked electromagnetic steel sheets 21p are welded on only one circumferential side in a region of the core outer peripheral portion 21a located between two circumferentially aligned conductor outer peripheral portions 40a. Therefore, the multiple electromagnetic steel sheets 21p do not form a large eddy current loop connecting one circumferential side and the other circumferential side of the conductor outer peripheral portion 40a. According to this modification, the eddy current loop generated on the outer peripheral surface of the rotor 20A can be reduced, thereby reducing eddy current loss in the rotating electric machine 100.

[0051] Second Embodiment Fig. 2 is a perspective view of a rotor 120 according to a second embodiment. Compared to the first embodiment, the rotor 120 according to the second embodiment has a plurality of tubular portions (fixing portions) 170 instead of the plurality of welded portions 70 as fixing portions. The plurality of tubular portions 170 fix the core outer peripheral portion 21a and the conductor outer peripheral portion 40a to each other instead of the plurality of welded portions 70. In the following description of the second embodiment, the same components as those in the first embodiment are designated by the same reference numerals, and description thereof will be omitted.

[0052] The cylindrical portion 170 is made of carbon fiber composite plastic. Each of the multiple cylindrical portions 170 has a cylindrical shape centered on the central axis J. The multiple cylindrical portions 170 are arranged side by side in the axial direction. The multiple cylindrical portions 170 surround the rotor core 21 from the outside in the radial direction. The inner diameter of the cylindrical portion 170 is approximately equal to the outer diameter of the rotor core 21. The cylindrical portion 170 is fixed to the rotor core 21 by, for example, cool fitting. The cylindrical portion 170 may also be fixed to the rotor core 21 by wrapping uncured carbon prepreg around the outer peripheral surface of the rotor core 21 and then curing it.

[0053] The multiple cylindrical portions 170 cover the openings 30a of the slots 30 from the radially outer side. As a result, the multiple cylindrical portions 170 prevent the conductor portions 40 from protruding from the openings 30a of the slots 30. As a result, the cylindrical portions 170 can fix the core outer peripheral portion 21a and the conductor outer peripheral portion 40a to each other. According to the present embodiment, even when the rotor 120 rotates at high speed and a large centrifugal force is applied to the conductor portions 40, the multiple cylindrical portions 170 prevent the conductor portions 40 from moving radially outward, thereby preventing the conductor portions 40 from coming off the slots 30.

[0054] As described above, the cylindrical portion 170 is made of carbon fiber composite plastic. Therefore, the cylindrical portion 170 has a relatively high strength and rigidity relative to its weight. According to this embodiment, even if the cylindrical portion 170 is made thick enough to withstand the centrifugal force applied to the conductor portion 40, an increase in the weight of the rotor 120 can be suppressed.

[0055] In this embodiment, the multiple cylindrical portions 170 are arranged spaced apart from one another in the axial direction. That is, the multiple cylindrical portions 170 are arranged discretely in the axial direction. Because the cylindrical portions 170 contain carbon fiber, eddy currents are generated on the outer circumferential surfaces of the cylindrical portions 170 when the rotor 120 rotates. According to this embodiment, by arranging the multiple cylindrical portions 170 discretely in the axial direction, it is possible to reduce the size of the eddy current loops generated on the outer circumferential surfaces of the cylindrical portions 170, and it is possible to reduce the eddy current loss of the rotating electric machine 100.

[0056] The multiple cylindrical portions 170 of this embodiment include multiple (four in this embodiment) first cylindrical portions 171 and one second cylindrical portion 172. The outer diameter of the first cylindrical portion 171 and the outer diameter of the second cylindrical portion 172 are equal to each other. The inner diameter of the first cylindrical portion 171 and the inner diameter of the second cylindrical portion 172 are equal to each other. The first cylindrical portion 171 and the second cylindrical portion 172 have different axial dimensions.

[0057] Here, the axial dimension of the first cylindrical portion 171 is defined as a first axial dimension D1. The axial dimension of the second cylindrical portion 172 is defined as a second axial dimension D2. In this embodiment, the second axial dimension D2 is greater than the first axial dimension D1 (D2>D1).

[0058] In this embodiment, the multiple cylindrical portions 170 are arranged symmetrically with respect to the axial center of the rotor 120. The second cylindrical portion 172 is arranged at the axial center of the rotor 120. Two of the four first cylindrical portions 171 are arranged at equal intervals on one axial side of the second cylindrical portion 172, and the other two are arranged at equal intervals on the other axial side of the second cylindrical portion 172. That is, in this embodiment, the second cylindrical portion 172 has a larger axial dimension than the first cylindrical portion 171 and is arranged closer to the center of the rotor core 21 in the axial direction than the first cylindrical portion 171.

[0059] According to this embodiment, by arranging the second cylindrical portion 172, which has a relatively large axial dimension, at the axial center, it is possible to firmly fix the conductor portion 40 near the axial center, where the amount of radially outward deformation of the conductor portion 40 is likely to be large. This effectively suppresses deformation of the conductor portion 40. Furthermore, because the first cylindrical portion 171, which has a relatively small axial dimension, is arranged at the ends on one and the other axial sides where deformation of the conductor portion 40 can be easily suppressed by the end rings 50, it is possible to reduce the total axial dimension of the multiple cylindrical portions 170, and suppress eddy current loss in the rotating electric machine 100.

[0060] Although the embodiments of the present invention have been described above, the configurations and combinations thereof in the embodiments are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to the embodiments.

[0061] For example, the rotor may be manufactured by inserting a preformed rod-shaped conductor into a slot in a rotor core and connecting end rings to both ends of the conductor. Even in this case, the cross-sectional shape of the slot can be configured as described above to prevent the conductor from coming off the slot. Furthermore, the material of the conductor and the end ring is not limited to aluminum alloy, but may also be copper or a copper-based alloy.

[0062] The present technology can be configured as follows: (1) A rotor for a rotating electric machine that rotates about a central axis, comprising: a rotor core having a plurality of slots that are arranged circumferentially and penetrate in the axial direction, a plurality of conductor portions arranged in the slots, a pair of end rings located on one axial side and the other axial side of the rotor core, respectively, and connecting the plurality of conductor portions, and a plurality of fixing portions, wherein the slots have openings that open to a core outer periphery of the rotor core and extend in the axial direction, the conductor portions have conductor outer periphery portions that face radially outward and are exposed radially outward from the openings, the plurality of fixing portions fix the core outer periphery portion and the conductor outer periphery portion to each other, and the plurality of fixing portions are arranged discretely in the axial direction. (2) The rotor according to (1), wherein the plurality of fixing portions are welded portions that weld the core outer periphery portion and the conductor outer periphery portion together. (3) The rotor described in (2), wherein the axial distance between the welded portion located closest to one axial side of the plurality of welded portions and one of the pair of end rings located on one axial side is larger than the smallest axial distance between the plurality of welded portions. (4) The rotor described in (2) or (3), wherein the plurality of welded portions include a first welded portion located on one circumferential side of the conductor outer circumferential portion and a second welded portion located on the other circumferential side of the conductor outer circumferential portion, and the first welded portion and the second welded portion are positioned with an axial shift. (5) The rotor described in (1), wherein the plurality of fixing portions are each a cylindrical portion surrounding the rotor core from the radially outer side, and the cylindrical portion is made of carbon fiber composite plastic. (6) The rotor described in (5), wherein the plurality of cylindrical portions include a first cylindrical portion and a second cylindrical portion having an axial dimension larger than that of the first cylindrical portion, and the second cylindrical portion is positioned axially closer to the center of the rotor core than the first cylindrical portion. (7) A rotating electric machine comprising: the rotor according to any one of (1) to (6); and a stator surrounding the rotor from the radially outer side.

[0063] 10... stator, 20, 20A, 120, 1020... rotor, 21... rotor core, 21a... core outer periphery, 30... slot, 30a... opening, 40... conductor portion, 40a... conductor outer periphery, 50... end ring, 70, 1070... welded portion (fixed portion), 70A... first welded portion, 70B... second welded portion, 100... rotating electric machine, 170... cylindrical portion (fixed portion), 171... first cylindrical portion, 172... second cylindrical portion, J... central axis

Claims

1. A rotor for a rotating electric machine that rotates around a central axis, comprising: a rotor core having a plurality of slots that are arranged circumferentially and penetrate in the axial direction; a plurality of conductor portions arranged in the slots; a pair of end rings located on one axial side and the other axial side of the rotor core, respectively, and connecting the plurality of conductor portions; and a plurality of fixing portions, wherein the slots have openings that open to the outer periphery of the core of the rotor core and extend in the axial direction, the conductor portions have conductor outer periphery portions that face radially outward and are exposed radially outward from the openings, the plurality of fixing portions fixing the outer periphery of the core and the conductor outer periphery to each other, and the plurality of fixing portions are arranged discretely in the axial direction.

2. The rotor according to claim 1, wherein each of the plurality of fixing portions is a welded portion that welds the outer periphery of the core and the outer periphery of the conductor together.

3. A rotor as described in claim 2, wherein the axial distance between the welded portion located furthest to one side of the plurality of welded portions and one of the pair of end rings located on one side of the axial direction is greater than the smallest axial distance between the plurality of welded portions.

4. A rotor as described in claim 2, wherein the plurality of welds include a first weld located on one circumferential side of the outer circumferential portion of the conductor, and a second weld located on the other circumferential side of the outer circumferential portion of the conductor, and the first weld and the second weld are positioned offset in the axial direction.

5. A rotor according to claim 1, wherein each of the plurality of fixing portions is a cylindrical portion that surrounds the rotor core from the radially outer side, and the cylindrical portion is made of carbon fiber composite plastic.

6. A rotor as described in claim 5, wherein the plurality of cylindrical portions include a first cylindrical portion and a second cylindrical portion having an axial dimension larger than that of the first cylindrical portion, and the second cylindrical portion is positioned axially closer to the center of the rotor core than the first cylindrical portion.

7. A rotating electric machine comprising: a rotor according to any one of claims 1 to 6; and a stator surrounding the rotor from the radially outer side.

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