Rotor and rotating electric machine

Abstract

A rotor according to the present invention comprises: a rotor core which has a cylindrical core body that extends in an axial direction so as to be centered upon a central axis and a plurality of projecting parts that project outward in the radial direction from a radially outward facing surface of the core body and that are arranged at intervals from one another along a circumferential direction; a plurality of conductor parts which are arranged between the projecting parts arranged adjacently to each other in the circumferential direction; and a pair of end rings which are arranged on one side in the axial direction with respect to the rotor core and on the other side in the axial direction with respect to the rotor core, respectively, and which connect the plurality of conductor parts. Each of the plurality of projecting parts has: a toothed part that projects outward in the radial direction from the radially outward facing surface of the core body; and a plurality of projections that project from the toothed part to one side in the circumferential direction and the other side in the circumferential direction, respectively. In the radial direction, the dimension of the toothed part in a direction orthogonal to the radial direction is constant.

Description

Rotor and Rotating Electric Machine

[0001] The present invention relates to a rotor and a rotating electric machine. This application claims priority based on Japanese Patent Application No. 2024-226889 filed in Japan on December 24, 2024, and incorporates its content herein.

[0002] A cage-type rotor in which a conductor part is arranged in a slot of a rotor core is known. In a cage-type rotor, a structure for suppressing the detachment of the conductor part from the rotor core is required. For example, Patent Document 1 discloses a structure in which convex portions protruding in the circumferential direction are provided on the inner surfaces of the respective slots formed in the rotor core, and the convex portions receive the centrifugal force applied to the conductor part.

[0003] Japanese Patent Application Laid-Open No. 2016-171627

[0004] In recent years, rotating electric machines using cage-type rotors as drive sources for automobiles and the like have been adopted. In such rotating electric machines, miniaturization and high output are required, so high-speed rotation is inevitably required. When the above-mentioned cage-type rotor is rotated at high speed, a large centrifugal force is applied to the conductor part, so there is a risk that a large force is locally applied to the rotor core. As a result, when the rotor core is deformed, there is a risk that the conductive part will detach from the rotor core.

[0005] One object of one aspect of the present invention is to provide a rotor and a rotating electric machine capable of suppressing the detachment of the conductive part from the rotor core.

[0006] One embodiment of the rotor of the present invention comprises a rotor core having a cylindrical core body portion extending axially with respect to a central axis, and a plurality of protrusions projecting radially outward from a radially outward-facing surface of the core body portion and arranged at intervals from one another along the circumferential direction; a plurality of conductor portions arranged between adjacent protrusions in the circumferential direction; and a pair of end rings connecting the plurality of conductor portions, arranged on one axial side and the other axial side of the rotor core. Each of the plurality of protrusions has a tooth portion projecting radially outward from a radially outward-facing surface of the core body portion, and a plurality of convex portions projecting circumferentially on one and the other sides from the tooth portion. In the radial direction, the dimension of the tooth portion in the direction perpendicular to the radial direction is constant.

[0007] One embodiment of the rotating electric machine of the present invention comprises the rotor described above and a stator surrounding the rotor from the radially outer side. The stator has an annular stator core and a coil portion mounted on the stator core.

[0008] According to one aspect of the present invention, in a rotor and a rotating electric machine, it is possible to suppress the separation of the conductive part from the rotor core.

[0009] Figure 1 is a cross-sectional view showing a rotating electric machine according to an embodiment. Figure 2 is a cross-sectional view showing a rotating electric machine according to an embodiment, and is a cross-sectional view taken along line II-II in Figure 1. Figure 3 is a cross-sectional view showing a rotor according to an embodiment, and is a partially enlarged cross-sectional view obtained by enlarging a part of Figure 2.

[0010] The rotor and rotating electric machine according to embodiments of the present invention will be described below with reference to the drawings. Note that the scope of the present invention is not limited to the following embodiments, and modifications can be made as appropriate within the scope of the technical idea of ​​the present invention. Furthermore, in the following drawings, the scale and number of components may differ from the actual structure for the sake of clarity.

[0011] Each figure shows the Z-axis. The Z-axis is the direction in which the central axis J of the rotating electric machine 1 extends. In this embodiment, the central axis J is a virtual axis. In the following description, the direction in which the central axis J extends, that is, the direction parallel to the Z-axis, will be referred to as the "axial direction". The radial direction centered on the central axis J will simply be referred to as the "radial direction". The circumferential direction centered on the central axis J will simply be referred to as the "circumferential direction". Of the axial directions, the side in which the Z-axis arrow points (+Z side) will be referred to as the "one axial side" or "upper side". Of the axial directions, the side opposite to the side in which the Z-axis arrow points (-Z side) will be referred to as the "other axial side" or "lower side". Note that the upper side and lower side are merely names used to describe the relative positional relationship of each part, and the actual arrangement relationships may be other than those indicated by these names.

[0012] The circumferential direction is indicated by the arrow θ in each diagram. The side of the circumferential direction in which the arrow θ points (the +θ side) is called the "one side of the circumferential direction." The side of the circumferential direction opposite to the side in which the arrow θ points (the -θ side) is called the "other side of the circumferential direction." The one side of the circumferential direction is the side that proceeds clockwise around the central axis J when viewed from above. The other side of the circumferential direction is the side that proceeds counterclockwise around the central axis J when viewed from above.

[0013] In the following explanation, "facing side A" is not limited to strictly facing side A, but also includes facing a side that is tilted within a range of 45° from side A. Furthermore, in the following explanation, "constant" is not limited to strictly constant, but includes non-constant values ​​within the range of design tolerances, etc.

[0014] The rotating electric machine 1 in this embodiment, shown in Figure 1, is a squirrel-cage type three-phase AC motor. The rotating electric machine 1 is mounted on vehicles that use the rotating electric machine 1 as a power source, such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and electric vehicles (EVs). The rotating electric machine 1 has both the function of outputting power as an engine and the function of generating electricity as a generator. The rotating electric machine 1 may also be used as either an engine or a generator. The configuration of the rotating electric machine 1 is not limited to this embodiment, and the rotating electric machine 1 may be, for example, a four-phase or more AC motor.

[0015] The rotating electric machine 1 of this embodiment comprises a rotor 20 configured as a cage-type rotor, a stator 10 that generates a rotational magnetic flux by alternating current, and a housing 6 that houses the rotor 20 and the stator 10. In the rotating electric machine 1 of this embodiment, the rotational magnetic flux generated in the stator 10 and the induced current generated in the conductor portion 40 of the rotor 20 configured as a cage-type rotor link together, thereby generating a rotational force around the central axis J in the rotor 20.

[0016] The housing 6 has a housing body 6a and a bearing holder 6b. The housing body 6a is substantially cylindrical with a central axis J. The housing body 6a is open on the upper side. The rotor 20 and the stator 10 are housed inside the housing body 6a. The housing body 6a has a cylindrical portion 6d and a bottom plate portion 6e.

[0017] The cylindrical portion 6d is substantially cylindrical with respect to the central axis J. The cylindrical portion 6d surrounds the rotor 20 and the stator 10 from the radially outer side. The bottom plate portion 6e is substantially annular with respect to the central axis J. The bottom plate portion 6e is positioned below the rotor 20 and the stator 10. The radial outer edge of the bottom plate portion 6e is connected to the lower end of the cylindrical portion 6d. The bottom plate portion 6e holds the bearing 8a. The bearing 8a is substantially annular with respect to the central axis J.

[0018] The bearing holder 6b is a substantially annular plate shape centered on the central axis J. The bearing holder 6b is positioned above the rotor 20 and stator 10. The bearing holder 6b is fixed to the upper end of the cylindrical portion 6d. As a result, the bearing holder 6b closes the opening of the housing body 6a. The bearing holder 6b holds the bearing 8b. The bearing 8b is a substantially annular shape centered on the central axis J.

[0019] The stator 10 is an annular shape centered on the central axis J. The stator 10 is fixed to the inner circumferential surface of the cylindrical portion 6d. The stator 10 surrounds the rotor 20 from the radially outer side. The stator 10 has an annular stator core 11 and a coil portion 12 mounted on the stator core 11.

[0020] Although not shown in the diagram, the stator core 11 of this embodiment is constructed by stacking multiple electromagnetic steel sheets in the axial direction. The stator core 11 has an annular core back portion 11a centered on the central axis J, and multiple stator teeth portions 11b that protrude radially inward from the inner circumferential surface of the core back portion 11a and are arranged in a circumferential direction. The radially outward-facing surface of the core back portion 11a is fixed to the inner circumferential surface of the cylindrical portion 6d. The coil portion 12 is mounted on each stator tooth portion 11b. The coil portion 12 includes three-phase coils for U-phase, V-phase, and W-phase. AC currents with different phases are supplied to the U-phase, V-phase, and W-phase coils.

[0021] The rotor 20 is rotatable about its central axis J. The rotor 20 is supported so as to be rotatable about its central axis J by a pair of bearings 8a and 8b. The rotor 20 comprises a shaft 38, a rotor core 21, a plurality of conductor sections 40, a pair of end rings 50, and a pair of plate members 60.

[0022] The shaft 38 is approximately cylindrical in shape, extending axially around the central axis J. The upper part of the shaft 38 is supported by bearing 8b. The lower part of the shaft 38 is supported by bearing 8a. As a result, the shaft 38 is rotatable around the central axis J.

[0023] The rotor core 21 is substantially cylindrical in shape, extending axially with respect to the central axis J. The rotor core 21 is positioned radially inward from the stator core 11. The rotor core 21 faces the stator core 11 radially with a gap between them. The rotor core 21 is fixed to the shaft 38. The rotor core 21 holds each of the multiple conductor portions 40 and the pair of end rings 50. As shown in Figure 2, the rotor core 21 has a core body portion 22 and multiple protrusions 24.

[0024] As shown in Figure 1, the core body portion 22 is cylindrical in shape, extending axially around the central axis J. The core body portion 22 has a central hole 22a. The central hole 22a is a hole that penetrates the core body portion 22 axially. When viewed from the axial direction, the central hole 22a is approximately circular in shape. A shaft 38 is passed through the central hole 22a axially. The shaft 38 is fixed to the inner circumferential surface of the central hole 22a. As a result, the rotor core 21 can rotate together with the shaft 38 around the central axis J.

[0025] As shown in Figure 2, the inner circumferential surface of the central hole 22a is provided with a pair of projections 22c that protrude radially inward and extend along the axial direction. The outer circumferential surface of the shaft 38 is provided with a pair of grooves 38a that are recessed radially inward and extend along the axial direction. Each projection 22c is inserted into a different groove 38a. As a result, the rotor core 21 and the shaft 38 are positioned relative to each other in the circumferential direction.

[0026] Each of the multiple protrusions 24 projects radially outward from the radially outward-facing surface of the core body 22. The protrusions 24 are spaced apart from each other along the circumferential direction. In this embodiment, the protrusions 24 are spaced equally apart from each other along the circumferential direction. The circumferential spacing of the protrusions 24 may differ from each other. In this embodiment, the rotor core 21 has 34 protrusions 24. The number of protrusions 24 in the rotor core 21 may be 33 or less, or 35 or more. Each protrusion 24 has a uniform cross-sectional shape and extends axially. The virtual protrusion line Lt shown in Figure 2 is a virtual straight line that, when viewed from the axial direction, passes through the circumferential center of the protrusion 24 and extends radially. The virtual protrusion line Lt passes through the central axis J. In this embodiment, when viewed from the axial direction, each protrusion 24 has a shape that is symmetrical with respect to the virtual protrusion line Lt as the axis of symmetry. When viewed from the axial direction, each projection 24 does not necessarily have to be symmetrical with respect to the imaginary projection line Lt as the axis of symmetry. In the following description, the side of each projection 24 that approaches the imaginary projection line Lt in the circumferential direction may be referred to as the inner side in the circumferential direction, and the side that moves away from the imaginary projection line Lt in the circumferential direction may be referred to as the outer side in the circumferential direction.

[0027] A pair of protrusions 24, arranged adjacent to each other in the circumferential direction, constitute a slot 39. A slot 39 is the space between a pair of protrusions 24, arranged adjacent to each other in the circumferential direction. In this embodiment, the rotor core 21 constitutes 34 slots 39. In this embodiment, each slot 39 is provided at equal intervals along the circumferential direction. Each slot 39 opens radially outward. Each slot 39 extends axially with a uniform cross-sectional shape. Each slot 39 opens on both the upper and lower sides.

[0028] Each of the multiple protrusions 24 has a tooth portion 25, multiple convex portions 26, and an umbrella portion 36. In each protrusion 24, the tooth portion 25 and the multiple convex portions 26 are connected to each other, and the tooth portion 25 and the umbrella portion 36 are connected to each other. The tooth portion 25 protrudes radially outward from the radially outward-facing surface of the core body portion 22. Viewed from the axial direction, the tooth portion 25 has a substantially rectangular shape with its long side extending radially. Therefore, as shown in Figure 3, the dimension Wt of the tooth portion 25 in the direction perpendicular to the radial direction is constant in the radial direction. Viewed from the axial direction, the tooth portion 25 has a shape that is symmetrical with respect to the imaginary protrusion line Lt as the axis of symmetry.

[0029] Each of the multiple protrusions 26 projects from one side (+θ side) and the other side (-θ side) of the teeth portion 25 in the circumferential direction. Each protrusion 26 prevents the conductor portion 40 from moving radially outward due to the centrifugal force applied to the conductor portion 40 when the rotor 20 rotates around the central axis J. In this way, each protrusion 26 prevents the conductor portion 40 from falling off the rotor core 21. The multiple protrusions 26 will be described in detail later.

[0030] Viewed from the axial direction, the umbrella portion 36 is a substantially arc shape extending in the circumferential direction. The umbrella portion 36 is connected to the radially outer end of the teeth portion 25. As shown in Figure 2, the radially outward-facing surface of the umbrella portion 36 constitutes a part of the outer circumferential surface of the rotor core 21. Although not shown, the radially outward-facing surface of the umbrella portion 36 faces the stator core 11 radially with a gap in between. As shown in Figure 3, the end of the umbrella portion 36 on one circumferential side (+θ side) is located circumferentially further to the other side than the four protrusions 26 that project circumferentially from the teeth portion 25. The end of the umbrella portion 36 on the other circumferential side (-θ side) is located circumferentially further to the other side than the other four protrusions 26 that project circumferentially from the circumferentially-facing surface of the teeth portion 25. As a result, the umbrella portion 36 protrudes outward in the circumferential direction more than the multiple protrusions 26.

[0031] In this embodiment, the rotor core 21 is constructed by stacking multiple electromagnetic steel sheets in the axial direction, each sheet having a central hole 22a and multiple protrusions 24 formed in advance by press processing.

[0032] The conductor portion 40 shown in Figure 2 is a rod-shaped component that extends along the axial direction and is arranged in different slots 39. In other words, each conductor portion 40 is positioned between adjacent protrusions 24 in the circumferential direction. Each conductor portion 40 is spaced apart from one another along the circumferential direction. The conductor portion 40 is made of a non-magnetic and conductive material, such as an aluminum alloy. In this embodiment, the conductor portion 40 is made of an aluminum alloy. The conductor portion 40 is formed in the slot 39 by a die-casting method using the rotor core 21 as an insert member. Therefore, the cross-sectional shape of the conductor portion 40 as viewed from the axial direction is substantially the same as the cross-sectional shape of the slot 39.

[0033] As shown in Figure 1, the conductor portion 40 extends linearly along the axial direction. The conductor portion 40 may also extend along a direction inclined circumferentially with respect to the axial direction. In this case, each protrusion 24 and each slot 39 also extends along a direction inclined circumferentially with respect to the axial direction. The axial dimension of the conductor portion 40 is approximately the same as the axial dimension of the rotor core 21. The upper and lower ends of each conductor portion 40 are connected to the end ring 50. Each conductor portion 40 is electrically connected to one another via the end ring 50. When the rotor 20 rotates, an induced current flows through the conductor portion 40 due to the rotational magnetic flux generated in the stator 10. This induced current flows through each conductor portion 40 in the axial direction.

[0034] Each of the pair of end rings 50 electrically connects a plurality of conductor sections 40. Each end ring 50 is substantially annular in shape with respect to the central axis J. One end ring 50 is positioned above the rotor core 21, i.e., on one axial side (+Z side). The other end ring 50 is positioned below the rotor core 21, i.e., on the other axial side (-Z side). Each end ring 50 is connected to each conductor section 40. Each end ring 50 faces the outer circumferential surface of the shaft 38 with a gap between them in the radial direction. The end rings 50, like the conductor sections 40, are made of a non-magnetic and conductive material, such as an aluminum alloy. In this embodiment, each conductor section 40 and the pair of end rings 50 are integrally molded by a die-casting method using the rotor core 21 as an insert member.

[0035] Each of the pair of plate members 60 is plate-shaped and extends along a plane perpendicular to the central axis J. One plate member 60 is positioned between the upper end of the rotor core 21 and one end ring 50, and the other plate member 60 is positioned between the lower end of the rotor core 21 and the other end ring 50.

[0036] Each plate member 60 plays a role in protecting the rotor core 21 when die-casting each conductor portion 40 and end ring 50. As described above, the rotor core 21 is composed of multiple electromagnetic steel sheets stacked in the axial direction. Each conductor portion 40 is formed by die-casting so as to be embedded in each slot 39 of the rotor core 21. Therefore, if the gaps between the electromagnetic steel sheets constituting the rotor core 21 are large, there is a risk that the molten metal constituting the conductor portion 40 and end ring 50 may enter these gaps. For this reason, when forming the conductor portion 40 and end ring 50, the rotor core 21 is compressed in the axial direction, and the electromagnetic steel sheets are placed in the mold in a state of close contact with each other. The plate members 60 protect the axial end faces of the rotor core 21 when the rotor core 21 is compressed in the axial direction, and prevent damage to the rotor core 21. Since sufficient strength and rigidity are required for the plate members 60, it is preferable that the material of the plate members 60 be a metallic material such as steel or aluminum alloy.

[0037] The plate member 60 has a first surface 60a and a second surface 60b facing opposite directions in the axial direction. The first surface 60a faces the rotor core 21 and makes axial contact with it. The second surface 60b faces the end ring 50 and makes axial contact with it. The second surface 60b is embedded in the end ring 50 during the molding of the end ring 50. The second surface 60b is provided with a projection 61 that protrudes in the axial direction. Therefore, the end ring 50 is configured with a housing portion 51 that accommodates the projection 61. When the rotor 20 rotates about the central axis J, centrifugal force is applied to both the end ring 50 and the conductor portion 40. In this embodiment, however, the projection 61 catches on the inner surface of the housing portion 51, thereby suppressing radial movement of both the end ring 50 and the conductor portion 40 due to the centrifugal force.

[0038] As described above, each projection 24 has a plurality of protrusions 26. As shown in Figure 3, in this embodiment, each projection 24 has eight protrusions 26. The number of protrusions 26 on each projection 24 may be seven or fewer, or nine or more. The plurality of protrusions 26 include a first protrusion 27, a second protrusion 28, a third protrusion 29, a fourth protrusion 30, a fifth protrusion 31, a sixth protrusion 32, a seventh protrusion 33, and an eighth protrusion 34. Each of the first protrusion 27, the third protrusion 29, the fifth protrusion 31, and the seventh protrusion 33 protrudes from the other side in the circumferential direction (-θ side) of the teeth portion 25 to the other side in the circumferential direction, and is arranged in this order from the radially inside to the radially outside. The second protrusion 28, the fourth protrusion 30, the sixth protrusion 32, and the eighth protrusion 34 each project outwards from the surface of the teeth portion 25 facing one side in the circumferential direction (+θ side), and are arranged in this order from the radially inner side to the radially outer side. As a result, the multiple protrusions 26 project outwards from the teeth portion 25 on both the circumferential side and the circumferential side.

[0039] Furthermore, the first protrusion 27, the second protrusion 28, the third protrusion 29, and the fourth protrusion 30 each project outward in the circumferential direction from the radially inner portion of the teeth portion 25. The fifth protrusion 31, the sixth protrusion 32, the seventh protrusion 33, and the eighth protrusion 34 each project outward in the circumferential direction from the radially outer portion of the teeth portion 25. As a result, the protrusions 26 project from both the radially inner and radially outer portions of the teeth portion 25.

[0040] As described above, in this embodiment, each conductor portion 40 is formed by die casting so as to be embedded in each slot 39 of the rotor core 21. Therefore, each conductor portion 40 is configured with a plurality of recesses 40a that accommodate each convex portion 26. That is, each conductor portion 40 has a plurality of recesses 40a. In this embodiment, each conductor portion 40 has eight recesses 40a. Different convex portions 26 are arranged inside each recess 40a. The outer surface of each convex portion 26 is in contact with the inner surface of a different recess 40a. This makes it possible to suppress radial movement of each conductor portion 40 relative to the rotor core 21.

[0041] The first protrusion 27 has a first outer surface 27a, a second outer surface 27b, a third outer surface 27c, a first corner 27f, and a second corner 27g. The first outer surface 27a is the outer surface of the first protrusion 27 that faces radially inward. The second outer surface 27b is the outer surface of the first protrusion 27 that faces radially outward. Viewed from the axial direction, the length of the first outer surface 27a is longer than the length of the second outer surface 27b. The third outer surface 27c is the outer surface of the first protrusion 27 that faces the other side in the circumferential direction (-θ side). The third outer surface 27c connects the first outer surface 27a and the second outer surface 27b. Viewed from the axial direction, the first angle 27α, which is the angle between the first outer surface 27a and the third outer surface 27c, is an obtuse angle. Viewed from the axial direction, the second angle 27β, which is the angle formed by the second outer surface 27b and the third outer surface 27c, is an obtuse angle. The first corner 27f is the corner where the first outer surface 27a and the third outer surface 27c connect. The second corner 27g is the corner where the second outer surface 27b and the third outer surface 27c connect.

[0042] Viewed from the axial direction, the second protrusion 28 is symmetrical to the first protrusion 27 with respect to the imaginary projection line Lt as the axis of symmetry. The second protrusion 28 has a first outer surface 28a, a second outer surface 28b, a third outer surface 28c, a first corner 28f, and a second corner 28g. The first outer surface 28a is a surface facing radially inward. The second outer surface 28b is a surface facing radially outward. Viewed from the axial direction, the length of the first outer surface 28a is longer than the length of the second outer surface 28b. The third outer surface 28c connects the first outer surface 28a and the second outer surface 28b. Viewed from the axial direction, the first angle 28α, which is the angle between the first outer surface 28a and the third outer surface 28c, and the second angle 28β, which is the angle between the second outer surface 28b and the third outer surface 28c, are both obtuse angles. The first corner 28f is the corner where the first outer surface 28a and the third outer surface 28c connect. The second corner 28g is the corner where the second outer surface 28b and the third outer surface 28c connect.

[0043] The third convex portion 29 has a first outer surface 29a, a second outer surface 29b, a third outer surface 29c, a first corner portion 29f, and a second corner portion 29g. The first outer surface 29a is a surface facing the radially inner side. The second outer surface 29b is a surface facing the radially outer side. When viewed in the axial direction, the length of the first outer surface 29a is longer than the length of the second outer surface 29b. The third outer surface 29c connects the first outer surface 29a and the second outer surface 29b. When viewed in the axial direction, each of the first angle 29α formed by the first outer surface 29a and the third outer surface 29c and the second angle 29β formed by the second outer surface 29b and the third outer surface 29c is an obtuse angle. The first corner portion 29f is a corner portion where the first outer surface 29a and the third outer surface 29c are connected. The second corner portion 29g is a corner portion where the second outer surface 29b and the third outer surface 29c are connected.

[0044] When viewed in the axial direction, the fourth convex portion 30 has a shape that is line-symmetric with the third convex portion 29 with the protruding virtual line Lt as the axis of symmetry. The fourth convex portion 30 has a first outer surface 30a, a second outer surface 30b, a third outer surface 30c, a first corner portion 30f, and a second corner portion 30g. The first outer surface 30a is a surface facing the radially inner side. The second outer surface 30b is a surface facing the radially outer side. When viewed in the axial direction, the length of the first outer surface 30a is longer than the length of the second outer surface 30b. The third outer surface 30c connects the first outer surface 30a and the second outer surface 30b. When viewed in the axial direction, each of the first angle 30α formed by the first outer surface 30a and the third outer surface 30c and the second angle 30β formed by the second outer surface 30b and the third outer surface 30c is an obtuse angle. The first corner portion 30f is a corner portion where the first outer surface 30a and the third outer surface 30c are connected. The second corner portion 30g is a corner portion where the second outer surface 30b and the third outer surface 30c are connected.

[0045] The fifth protrusion 31 has a first outer surface 31a, a second outer surface 31b, a third outer surface 31c, a first corner 31f, and a second corner 31g. The first outer surface 31a is a surface facing radially inward. The second outer surface 31b is a surface facing radially outward. Viewed from the axial direction, the length of the first outer surface 31a is longer than the length of the second outer surface 31b. The third outer surface 31c connects the first outer surface 31a and the second outer surface 31b. Viewed from the axial direction, the first angle 31α, which is the angle between the first outer surface 31a and the third outer surface 31c, and the second angle 31β, which is the angle between the second outer surface 31b and the third outer surface 31c, are both obtuse angles. The first corner 31f is the corner where the first outer surface 31a and the third outer surface 31c connect. The second corner 31g is the corner where the second outer surface 31b and the third outer surface 31c connect.

[0046] Viewed from the axial direction, the sixth protrusion 32 is symmetrical to the fifth protrusion 31 with respect to the imaginary projection line Lt as the axis of symmetry. The sixth protrusion 32 has a first outer surface 32a, a second outer surface 32b, a third outer surface 32c, a first corner 32f, and a second corner 32g. The first outer surface 32a is a surface facing radially inward. The second outer surface 32b is a surface facing radially outward. Viewed from the axial direction, the length of the first outer surface 32a is longer than the length of the second outer surface 32b. The third outer surface 32c connects the first outer surface 32a and the second outer surface 32b. Viewed from the axial direction, the first angle 32α, which is the angle between the first outer surface 32a and the third outer surface 32c, and the second angle 32β, which is the angle between the second outer surface 32b and the third outer surface 32c, are both obtuse angles. The first corner 32f is the corner where the first outer surface 32a and the third outer surface 32c connect. The second corner 32g is the corner where the second outer surface 32b and the third outer surface 32c connect.

[0047] The seventh convex portion 33 has a first outer surface 33a, a second outer surface 33b, a third outer surface 33c, a first corner portion 33f, and a second corner portion 33g. The first outer surface 33a is a surface facing the inner side in the radial direction. The second outer surface 33b is a surface facing the outer side in the radial direction. When viewed from the axial direction, the length of the first outer surface 33a is longer than the length of the second outer surface 33b. The third outer surface 33c connects the first outer surface 33a and the second outer surface 33b. When viewed from the axial direction, each of the first angle 33α formed by the first outer surface 33a and the third outer surface 33c, and the second angle 33β formed by the second outer surface 33b and the third outer surface 33c is an obtuse angle. The first corner portion 33f is a corner portion where the first outer surface 33a and the third outer surface 33c are connected. The second corner portion 33g is a corner portion where the second outer surface 33b and the third outer surface 33c are connected.

[0048] When viewed from the axial direction, the eighth convex portion 34 has a shape that is line-symmetric with the seventh convex portion 33 with the protruding virtual line Lt as the axis of symmetry. The eighth convex portion 34 has a first outer surface 34a, a second outer surface 34b, a third outer surface 34c, a first corner portion 34f, and a second corner portion 34g. The first outer surface 34a is a surface facing the inner side in the radial direction. The second outer surface 34b is a surface facing the outer side in the radial direction. When viewed from the axial direction, the length of the first outer surface 34a is longer than the length of the second outer surface 34b. The third outer surface 34c connects the first outer surface 34a and the second outer surface 34b. When viewed from the axial direction, each of the first angle 34α formed by the first outer surface 34a and the third outer surface 34c, and the second angle 34β formed by the second outer surface 34b and the third outer surface 34c is an obtuse angle. The first corner portion 34f is a corner portion where the first outer surface 34a and the third outer surface 34c are connected. The second corner portion 34g is a corner portion where the second outer surface 34b and the third outer surface 34c are connected.

[0049] From the above, when viewed from the axial direction, in each of the plurality of convex portions 26, the length of the first outer surface, which is the surface facing the inner side in the radial direction, is longer than the length of the second outer surface, which is the surface facing the outer side in the radial direction. Also, in each of the plurality of convex portions 26, when viewed from the axial direction, each of the first angles 27α to 34α formed by the first outer surface and the third outer surface, and the second angles 27β to 34β formed by the second outer surface and the third outer surface is an obtuse angle.

[0050] According to this embodiment, the rotor 20 comprises a rotor core 21 having a cylindrical core body portion 22 extending axially with respect to a central axis J, and a plurality of protrusions 24 projecting radially outward from the radially outward-facing surface of the core body portion 22 and arranged at intervals from each other along the circumferential direction; a plurality of conductor portions 40 arranged between adjacent protrusions 24 in the circumferential direction; and a pair of end rings 50 arranged on one axial side (+Z side) and the other axial side (-Z side) of the rotor core 21, respectively, connecting the plurality of conductor portions 40. Each of the plurality of protrusions 24 has a tooth portion 25 projecting radially outward from the radially outward-facing surface of the core body portion 22, and a plurality of convex portions 26 projecting from the tooth portion 25 on one circumferential side (+θ side) and the other circumferential side (-θ side), respectively, and the dimension Wt of the tooth portion 25 in the direction perpendicular to the radial direction is constant in the radial direction. Therefore, as described above, the convex portion 26 can be positioned inside each of the multiple recesses 40a of the conductor portion 40. As a result, when a centrifugal force Fc is applied to each conductor portion 40 by the rotation of the rotor 20 during the operation of the rotating electric machine 1, as shown in Figure 3, the first outer surfaces 27a to 34a of each convex portion 26, which are the surfaces facing radially inward, come into contact with the inner surface of the recess 40a in the radial direction. This prevents the conductor portion 40 from moving radially outward due to the centrifugal force Fc. Consequently, it is possible to prevent the conductor portion 40 from detaching from the rotor core 21.

[0051] In a configuration where the teeth portion 25 has multiple recesses facing inward in the circumferential direction, and the conductor portion 40 has multiple protrusions arranged inside these recesses, the minimum dimension of the teeth portion 25 in the direction perpendicular to the radial direction becomes smaller. As a result, if the magnetic flux passing through the teeth portion 25 decreases due to magnetic saturation in the teeth portion 25, the rotational torque of the rotor 20 decreases. In contrast, in this embodiment, as described above, the dimension Wt of the teeth portion 25 in the direction perpendicular to the radial direction is constant in the radial direction, so it is possible to suppress the decrease in the minimum dimension of the teeth portion 25 in the direction perpendicular to the radial direction. As a result, it is possible to suppress magnetic saturation in the teeth portion 25, and therefore suppress the decrease in the magnetic flux passing through the teeth portion 25. Thus, it is possible to suppress the detachment of the conductor portion 40 from the rotor core 21 due to centrifugal force Fc, while suppressing a decrease in the rotational torque of the rotor 20.

[0052] In this embodiment, protrusions 26 protrude from both the radially inner and radially outer portions of the teeth portion 25. Therefore, when the rotor 20 rotates, the radially inner and radially outer portions of the protrusions 24 can receive the centrifugal force Fc applied to the conductor portion 40. As a result, when the rotor 20 rotates, the concentration of stress on a part of the radial direction of the protrusions 24 can be effectively suppressed. This effectively suppresses deformation of the protrusions 24 due to the centrifugal force Fc, and thus more effectively suppresses the detachment of the conductor portion 40 from the rotor core 21.

[0053] Furthermore, in this embodiment, as described above, when the rotor 20 rotates, the concentration of stress on a part of the radial direction of the protrusion 24 can be suppressed, thus effectively preventing damage to the protrusion 24. This prevents fragments of the protrusion 24 from getting caught between the rotor core 21 and the stator core 11. Therefore, the rotating electric machine 1 can be operated stably.

[0054] According to this embodiment, when viewed from the axial direction, the protrusion 24 is symmetrical with respect to the imaginary protrusion line Lt that passes through the circumferential center of the protrusion 24 and extends radially. As described above, the rotor core 21 of this embodiment is constructed by stacking multiple electromagnetic steel sheets in the axial direction, each sheet having a central hole 22a and multiple protrusions 24 formed in advance by press working. When viewed from the axial direction, if the protrusion 24 is not symmetrical with respect to the imaginary protrusion line Lt, stress tends to concentrate on a part of the protrusion 24 when press working is performed on each electromagnetic steel sheet. Therefore, it is difficult to improve the shape accuracy of each electromagnetic steel sheet, and thus difficult to improve the shape accuracy of the rotor core 21. In contrast, in this embodiment, as described above, when viewed from the axial direction, the protrusion 24 is symmetrical with respect to the imaginary protrusion line Lt, making it easier to suppress stress concentration on a part of the protrusion 24 when press working is performed on each electromagnetic steel sheet. As a result, the shape accuracy of each electromagnetic steel sheet can be improved, and thus the shape accuracy of the rotor core 21 can be improved.

[0055] According to this embodiment, when viewed from the axial direction, the length of the first outer surface of each of the multiple protrusions 26, which faces radially inward, is longer than the length of the second outer surface, which faces radially outward. Therefore, the area of ​​each first outer surface 27a to 34a can be increased, and the contact area between each first outer surface 27a to 34a and the inner surface of each recess 40a of the conductor portion 40 can be increased. As a result, the stress applied to each first outer surface 27a to 34a by the centrifugal force Fc applied to the conductor portion 40 when the rotor 20 rotates can be reduced. Therefore, deformation of each protrusion 26 can be suitably suppressed when the rotor 20 rotates, and the detachment of the conductor portion 40 from the rotor core 21 can be more suitably suppressed.

[0056] In this embodiment, each of the multiple protrusions 26 has a third outer surface connecting the first outer surface and the second outer surface, and when viewed from the axial direction, the first angles 27α to 34α formed by the first outer surface and the third outer surface, and the second angles 27β to 34β formed by the second outer surface and the third outer surface are both obtuse angles. Therefore, compared to the case where the first angles 27α to 34α and the second angles 27β to 34β are both acute angles in each protrusion 26, it is easier to improve the shape accuracy of each protrusion 26 formed by press working on the electrical steel sheet. As a result, the shape accuracy of each electrical steel sheet can be more favorably improved, and therefore the shape accuracy of the rotor core 21 can be more favorably improved.

[0057] As described above, in this embodiment, each conductor portion 40 is formed by a die-casting method using the rotor core 21 as an insert member. When the first angles 27α to 34α and the second angles 27β to 34β are acute angles, when molten aluminum alloy is poured into each slot 39 of the rotor core 21, there is a risk that the radial flow of the aluminum alloy near the first corners 27f to 34f and near the second corners 27g to 34g will be disturbed. As a result, casting defects are more likely to occur in the portions of the conductor portion 40 near the first corners 27f to 34f and near the second corners 27g to 34g, which may reduce the strength of the conductor portion 40. In contrast, in this embodiment, since the first angles 27α to 34α and the second angles 27β to 34β are obtuse angles, when forming each conductor portion 40, it is possible to suppress disturbance in the radial flow of the aluminum alloy near the first corners 27f to 34f and near the second corners 27g to 34g. As a result, it is possible to suppress the occurrence of casting defects in the portions of the conductor portion 40 near the first corners 27f to 34f and near the second corners 27g to 34g. Therefore, it is possible to suppress a decrease in the strength of the conductor portion 40.

[0058] According to this embodiment, each of the multiple protrusions 24 is connected to the radially outer end of the teeth portion 25 and has an umbrella portion 36 that protrudes circumferentially outward from the multiple convex portions 26. Therefore, compared to a configuration in which the multiple convex portions 26 protrude circumferentially outward from the umbrella portion 36, it is possible to suppress the circumferential dimension of each convex portion 26 from becoming too large. As a result, it is possible to suppress the circumferential dimension of each recess 40a of the conductor portion 40 from becoming too large. This prevents the cross-sectional area of ​​the conductor portion 40 as viewed from the axial direction from becoming too small, and thus prevents an increase in the electrical resistance of the conductor portion 40. Therefore, it is possible to suppress a decrease in the induced current flowing through each conductor portion 40 due to the rotational magnetic flux received from the stator 10. As a result, the rotational torque of the rotating electric machine 1 can be increased, and the driving efficiency of the rotating electric machine 1 can be increased.

[0059] Furthermore, in this embodiment, since the circumferential dimensions of the umbrella portion 36 can be easily increased, the area of ​​the radially outward-facing surface of the protruding portion 24 can be increased. This makes it possible to increase the rotational magnetic flux flowing from the stator 10 to the protruding portion 24. Therefore, the rotational torque of the rotating electric machine 1 can be more effectively increased.

[0060] According to this embodiment, the rotating electric machine 1 comprises a rotor 20 and a stator 10 surrounding the rotor 20 from the radially outer side. The stator 10 has an annular stator core 11 and a coil portion 12 mounted on the stator core 11. Therefore, as described above, when the rotor 20 rotates and a centrifugal force Fc is applied to each conductor portion 40, the first outer surfaces 27a to 34a of each convex portion 26 and the inner surface of the concave portion 40a can be brought into radial contact. This prevents the conductor portion 40 from moving radially outward due to the centrifugal force Fc. Therefore, it is possible to prevent the conductor portion 40 from detaching from the rotor core 21.

[0061] Although 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 are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited by the embodiments.

[0062] The protrusion may project outward in the circumferential direction from only one of the radially inner or radially outer portions of the teeth. In this case, it is preferable that a recess is provided on the other radially inner or radially outer portion of the teeth, and that a part of the conductor is positioned inside this recess. This effectively prevents the conductor from separating from the rotor core when the rotor rotates.

[0063] When viewed from the axial direction, the length of the first outer surface of each of the multiple protrusions may be shorter than or the same as the length of the second outer surface. Also, each of the multiple protrusions does not necessarily have a third outer surface. In this case, the first outer surface and the second outer surface are directly connected.

[0064] The rotor may be constructed by inserting pre-formed rod-shaped conductors into each slot of the rotor core, inserting the ends of each conductor into holes provided in each of a pair of end rings, and then connecting each conductor to each end ring, for example, by welding. In this case as well, by configuring the protruding parts as described above, it is possible to suppress the conductors from detaching from the rotor core. Furthermore, the material of the conductors and end rings is not limited to aluminum alloy, but may be copper or copper-based alloys, etc.

[0065] Furthermore, this technology can take the following configurations: (1) A rotor having a cylindrical core body portion extending axially with respect to a central axis, and a plurality of protrusions projecting radially outward from a radially outward-facing surface of the core body portion and arranged at intervals from each other along the circumferential direction, a plurality of conductor portions arranged between adjacent protrusions in the circumferential direction, and a pair of end rings arranged on one axial side and the other axial side of the rotor core, respectively, connecting the plurality of conductor portions, wherein each of the plurality of protrusions has a tooth portion projecting radially outward from a radially outward-facing surface of the core body portion, and a plurality of convex portions projecting from the tooth portion to one circumferential side and the other circumferential side, respectively, and the dimension in the direction perpendicular to the radial direction of the tooth portion is constant in the radial direction. (2) The rotor according to (1), wherein the convex portions project from the radially inner portion and the radially outer portion of the tooth portion, respectively. (3) The rotor according to (1) or (2), wherein, when viewed from the axial direction, the projection is symmetrical with respect to a virtual line of symmetry passing through the circumferential center of the projection and extending radially. (4) The rotor according to any one of (1) to (3), wherein, when viewed from the axial direction, the length of the first outer surface, which is the radially inward-facing surface of each of the plurality of protrusions, is longer than the length of the second outer surface, which is the radially outward-facing surface. (5) The rotor according to (4), wherein each of the plurality of protrusions has a third outer surface connecting the first outer surface and the second outer surface, and when viewed from the axial direction, the angle formed by the first outer surface and the third outer surface, and the angle formed by the second outer surface and the third outer surface are both obtuse angles. (6) The rotor according to any one of (1) to (5), wherein each of the plurality of projections has an umbrella portion that is connected to the radially outward end of the teeth portion and protrudes circumferentially outward from the plurality of protrusions. (7) A rotating electric machine comprising a rotor as described in any one of (1) to (6), and a stator surrounding the rotor from the radially outer side, wherein the stator has an annular stator core and a coil portion mounted on the stator core.

[0066] 1...Rotating electric machine, 10...Stator, 11...Stator core, 12...Coil section, 20...Rotor, 21...Rotor core, 22...Core body section, 24...Protruding section, 25...Teeth section, 26...Convex section, 27a, 28a, 29a, 30a, 31a, 32a, 33a, 34a...First outer surface, 27b, 28b, 29b, 30b, 31b, 32b, 33b, 34b...Second outer surface, 27c, 28c, 29c, 30c, 31c, 32c, 33c, 34c...Third outer surface, 36...Umbrella section, 40...Conductor section, 50...End ring, J...Central axis, Lt...Imaginary projection line, Wt...Dimension in the direction perpendicular to the radial direction of the teeth section

Claims

1. A rotor having a cylindrical core body portion extending axially with respect to a central axis, and a plurality of protrusions projecting radially outward from a radially outward-facing surface of the core body portion and spaced apart from each other along the circumferential direction; a plurality of conductor portions arranged between adjacent protrusions in the circumferential direction; and a pair of end rings connecting the plurality of conductor portions, each of which has a tooth portion projecting radially outward from a radially outward-facing surface of the core body portion, and a plurality of convex portions projecting circumferentially to one side and the other side from the tooth portion, respectively, and the dimension of the tooth portion in the direction perpendicular to the radial direction is constant in the radial direction.

2. The rotor according to claim 1, wherein the protrusions protrude from the radially inner portion and the radially outer portion of the teeth portion, respectively.

3. The rotor according to claim 1 or 2, wherein, when viewed from the axial direction, the projection is symmetrical with respect to a virtual line of symmetry passing through the circumferential center of the projection and extending radially.

4. The rotor according to claim 1 or 2, wherein, when viewed from the axial direction, the length of the first outer surface, which is the radially inward-facing surface of each of the plurality of protrusions, is longer than the length of the second outer surface, which is the radially outward-facing surface.

5. The rotor according to claim 4, wherein each of the plurality of protrusions has a third outer surface connecting the first outer surface and the second outer surface, and the angle formed by the first outer surface and the third outer surface, and the angle formed by the second outer surface and the third outer surface, when viewed from the axial direction, are both obtuse angles.

6. The rotor according to claim 1 or 2, wherein each of the plurality of protrusions is connected to the radially outer end of the tooth portion and has an umbrella portion that protrudes circumferentially outward from the plurality of convex portions.

7. A rotating electric machine comprising: a rotor according to claim 1 or 2; and a stator surrounding the rotor from the radially outer side, wherein the stator has an annular stator core and a coil portion mounted on the stator core.

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