Cage type rotor and cage type induction rotary electric machine

Abstract

To provide a cage type rotor capable of securing strengths of an end ring and a slot bar even during high-speed rotation.SOLUTION: A cage type rotor comprises a rotor core 10, a plurality of slot bars and an end ring. The rotor core 10 includes: a plurality of first electromagnetic steel plates 11 in each of which a rotor shaft penetration hole for rotor shaft penetration and a plurality of first slot holes in a circumferential direction are formed; and a plurality of second electromagnetic steel plates 21 in each of which a rotor shaft penetration hole and a plurality of second slot holes in a circumferential direction to be respectively overlapped with the plurality of first slot holes are formed. In comparison with the first electromagnetic steel plate 11, in the second electromagnetic steel plate 21, projections 21v and 21w protruding to the inside of a recess or the second slot hole are further formed in a portion of a second electromagnetic steel plate slot edge that is a boundary with the second slot hole.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a squirrel-cage rotor and a squirrel-cage induction rotating electric machine. [Background technology]

[0002] A known method for manufacturing a cage rotor for a motor is to integrally mold two short-circuit rings formed at both ends of the rotor core and multiple rotor bars (hereinafter referred to as "slot bars") that connect these short-circuit rings using a conductive material by die-casting. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-112687 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-170937 Summary of the Invention [Problem to be solved by the invention]

[0004] Motors for vehicle use, i.e., vehicle drive motors, are becoming faster. When using aluminum die-cast induction motor rotors for vehicle use, the strength of the connection between the end ring and slot bar at high rotation speeds becomes an issue.

[0005] An object of embodiments of the present invention is to provide a squirrel-cage rotor and a squirrel-cage induction rotating electric machine that can ensure the strength of the end rings and slot bars even during high-speed rotation. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the squirrel-cage rotor of this embodiment comprises a rotor core having: a rotor shaft extending in the direction of the rotation axis; a plurality of first electromagnetic steel sheets stacked in the direction of the rotation axis, each having a rotor shaft through hole for passing the rotor shaft therethrough and a plurality of first slot holes formed in the circumferential direction; and a plurality of second electromagnetic steel sheets each having a plurality of second slot holes formed so as to overlap the rotor shaft through hole and the plurality of first slot holes in the circumferential direction, respectively; a plurality of slot bars which are metal conductors filled in each of a plurality of rotor slots formed by the plurality of first slot holes and the plurality of second slot holes; and annular end rings provided at each end of the rotor core in the direction of the rotation axis and connected to the plurality of slot bars, and wherein, compared to the first electromagnetic steel sheets, the second electromagnetic steel sheets further have a recess that is recessed from the inner side of the second slot holes or a protrusion that protrudes toward the inner side of the second slot holes, at a part of the slot edge of the second electromagnetic steel sheet that is the boundary of the second slot holes. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view showing the configuration of a rotating electric machine including a squirrel-cage rotor according to a first embodiment. [Figure 2] 1 is a perspective view showing the configuration of a squirrel-cage rotor according to a first embodiment. [Figure 3] 2 is a partial front view in the circumferential direction showing a first electromagnetic steel plate that constitutes a rotor core of the squirrel-cage rotor according to the first embodiment. FIG. [Figure 4] 3 is a partial front view of a first electromagnetic steel sheet constituting the rotor core of the squirrel-cage rotor according to the first embodiment, showing first slot holes formed in the first electromagnetic steel sheet. FIG. [Figure 5] 3 is a partial front view in the circumferential direction showing a second electromagnetic steel plate that constitutes the rotor core of the squirrel-cage rotor according to the first embodiment. FIG. [Figure 6] 3 is a partial front view of a second electromagnetic steel sheet constituting the rotor core of the squirrel-cage rotor according to the first embodiment, showing second slots formed in the second electromagnetic steel sheet. FIG. [Figure 7] FIG. 2 is a perspective view showing the inner surface of a rotor slot of the squirrel-cage rotor according to the first embodiment. [Figure 8] 1 is a vertical cross-sectional view of the upper half along the rotation axis direction, showing the configuration of a squirrel-cage rotor according to a first embodiment. [Figure 9] FIG. 2 is a conceptual vertical cross-sectional view of the upper half taken along the rotation axis direction, illustrating the effect of the squirrel-cage rotor according to the first embodiment. [Figure 10] 10 is a partial front view of a second electromagnetic steel sheet constituting a rotor core of a squirrel-cage rotor according to a second embodiment, showing second slots formed in the second electromagnetic steel sheet. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, a squirrel-cage rotor and a squirrel-cage induction rotating electric machine according to an embodiment of the present invention will be described with reference to the drawings. Hereinafter, identical or similar parts will be designated by common reference numerals, and overlapping descriptions will be omitted.

[0009] [First embodiment] FIG. 1 is a cross-sectional view showing the configuration of a squirrel-cage induction rotating electric machine 1 including a squirrel-cage rotor 2 according to a first embodiment.

[0010] The squirrel-cage induction rotating electric machine 1 has a squirrel-cage rotor 2, a stator 3, two bearings 4, a bearing bracket 5 that supports the bearings 4, and a frame 6 that supports the stator 3 and the like.

[0011] The squirrel-cage rotor 2 includes a rotor shaft 2a that extends in a direction parallel to the direction of extension of the rotation axis CL (rotation axis direction) and is rotatably supported by two bearings 4, a cylindrical rotor core 10 attached to the radial outside of the rotor shaft 2a, a plurality of slot bars 30 that pass through the rotor core 10 in the rotation axis direction, and annular end rings 40 provided at each end of the rotor core 10 in the rotation axis direction. Here, the radial direction refers to the direction that spreads radially from the rotation axis CL in a cross section perpendicular to the rotation axis CL.

[0012] The stator 3 has a cylindrical stator core 3a disposed radially outside the rotor core 10, and a stator winding 3b wound around stator teeth (not shown) formed on the stator core 3a.

[0013] Fig. 2 is a perspective view showing the configuration of the squirrel-cage rotor 2 according to the first embodiment. Note that the rotor shaft 2a (Fig. 1) is not shown in Fig. 2. Note that the slot bars 30 are located inside the rotor core 10 and are therefore not visible in Fig. 2.

[0014] Rotor core 10 has a plurality of first electromagnetic steel sheets 11 and second electromagnetic steel sheets 21 stacked in the direction of the rotation axis. As described above, end rings 40 are disposed on both ends of rotor core 10 in the direction of the rotation axis. Rotor core 10 also has rotor shaft through-hole 10a formed therein for rotor shaft 2a (FIG. 1) to pass through.

[0015] <First electromagnetic steel sheet and first slot hole> Fig. 3 is a partial circumferential front view showing a first electromagnetic steel sheet 11 constituting the rotor core 10 of the squirrel-cage rotor 2 according to the first embodiment. Fig. 4 is a partial front view of a portion of the first electromagnetic steel sheet 11 in the circumferential direction, showing first slot holes 12 formed in the first electromagnetic steel sheet 11. Note that Fig. 3 also shows a cross section of the rotor shaft 2a. Here, the circumferential direction is the direction of rotation about the rotation axis CL (Fig. 1), i.e., the direction in which the angular position changes.

[0016] As shown in FIG. 3, the first electromagnetic steel sheet 11 has a plurality of first slot holes 12 formed in the vicinity of its radial outer edge 11t, that is, along the outer edge 11t, at intervals from one another in the circumferential direction.

[0017] As shown in FIG. 4 , the first slot hole 12 is formed by a first electromagnetic steel sheet slot edge portion 11s, which is a boundary portion of the first slot hole 12 in the first electromagnetic steel sheet 11. The first electromagnetic steel sheet slot edge portion 11s is composed of a first electromagnetic steel sheet slot edge innermost portion 11a, a first electromagnetic steel sheet slot edge outermost portion 11b, and first electromagnetic steel sheet slot edge side portions 11c and 11d, which extend from the first electromagnetic steel sheet slot edge innermost portion 11a toward the first electromagnetic steel sheet slot edge outermost portion 11b. Here, the first electromagnetic steel sheet slot edge innermost portion 11a is the innermost boundary portion of the first slot hole 12 in the first electromagnetic steel sheet 11. The first electromagnetic steel sheet slot edge outermost portion 11b is the outermost boundary portion of the first slot hole 12 in the first electromagnetic steel sheet 11 in the radial direction.

[0018] 4 illustrates an example of the shape of the first slot hole 12 in which the center of the outermost slot edge portion 11b of the first electromagnetic steel sheet, which is the radially outer portion, protrudes radially, and the innermost slot edge portion 11a of the first electromagnetic steel sheet, which is the radially inner portion, protrudes radially inward, but the shape is not limited to this. The shape of the first slot hole 12 may be other shapes, such as a trapezoid or a polygon with curved corners.

[0019] <Second electromagnetic steel sheet and second slot hole> Fig. 5 is a partial front view in the circumferential direction showing the second electromagnetic steel sheet 21 that constitutes the rotor core 10 of the squirrel-cage rotor 2 according to the first embodiment. Fig. 6 is a partial front view in the circumferential direction of a portion of the second electromagnetic steel sheet 21, showing the second slot holes 22 formed in the second electromagnetic steel sheet 21. Note that Fig. 5 also shows a cross section of the rotor shaft 2a.

[0020] As shown in FIG. 5, the second electromagnetic steel sheet 21 has a plurality of second slot holes 22 formed in the vicinity of its radial outer edge 21t, that is, along the outer edge 21t, at intervals from one another in the circumferential direction.

[0021] As shown in FIG. 6 , the second slot holes 22 are defined by second electromagnetic steel sheet slot edge portions 21s, which are boundaries of the second slot holes 22 in the second electromagnetic steel sheet 21. The second electromagnetic steel sheet slot edge portions 21s have a second electromagnetic steel sheet slot edge innermost portion 21a and a second electromagnetic steel sheet slot edge outermost portion 21b of the second electromagnetic steel sheet 21, as well as second electromagnetic steel sheet slot edge side portions 21c and second electromagnetic steel sheet slot edge side portions 21d that extend from the second electromagnetic steel sheet slot edge innermost portion 21a toward the second electromagnetic steel sheet slot edge outermost portion 21b of the second electromagnetic steel sheet 21. In this respect, the second electromagnetic steel sheet slot edge portions 21s are similar to the first electromagnetic steel sheet slot edge portions 11s. Furthermore, within this range, each second slot hole 22 has the same shape and dimensions as each first slot hole 12, and is formed at the same radial and circumferential positions as the first slot holes 12. The second electromagnetic steel sheet slot edge portion 21s differs from the first electromagnetic steel sheet slot edge portion 11s in that it further has a bottom restraint protrusion 21w and two side restraint protrusions 21v, which will be described next; otherwise, the second electromagnetic steel sheet slot edge portion 21s and the first electromagnetic steel sheet slot edge portion 11s overlap each other when viewed in the rotation axis direction.

[0022] Here, the convex portions of the bottom restraint protrusion 21w and the two side restraint protrusions 21v refer to the portions that protrude toward the inside of the second slot hole 22 in a part of the second electromagnetic steel sheet slot edge portion 21s, which is the boundary with the second slot hole 22, compared to the case of the first electromagnetic steel sheet 11.

[0023] In this way, two side restraining protrusions 21v and a bottom restraining protrusion 21w are further formed as the second electromagnetic steel sheet slot edge portion 21s. Therefore, the second electromagnetic steel sheet slot edge portion 21s is composed of the second electromagnetic steel sheet slot edge innermost portion 21a, the second electromagnetic steel sheet slot edge outermost portion 21b, the second electromagnetic steel sheet slot edge side portion 21c, the second electromagnetic steel sheet slot edge side portion 21d, as well as the bottom restraining protrusion 21w and the two side restraining protrusions 21v. Outermost slot edge portion

[0024] The side restraint protrusions 21v are formed on the second electromagnetic steel sheet 21 at the second electromagnetic steel sheet slot edge side portions 21c and 21d, respectively, so as to protrude from the second electromagnetic steel sheet 21 toward the second slot hole 22, i.e., toward the circumferentially inner side. The side restraint protrusions 21v are formed at positions closer to the second electromagnetic steel sheet slot edge innermost portion 21a than to the second electromagnetic steel sheet slot edge outermost portion 21b. While FIG. 6 illustrates an example in which the side restraint protrusions 21v are rectangular, the shape is not limited thereto. The side restraint protrusions 21v may have other shapes, such as a triangle or a trapezoid whose apex protrudes toward the second slot hole 22. Furthermore, a plurality of side restraint protrusions 21v may be formed, for example, in a sawtooth shape, i.e., a series of multiple triangles.

[0025] Furthermore, a bottom restraint protrusion 21w is formed in the circumferential center of the innermost inner portion 21a of the second electromagnetic steel sheet slot edge portion, protruding from the second electromagnetic steel sheet 21 toward the second slot hole 22, i.e., radially outward. The shape and number of the bottom restraint protrusions 21w are not limited to the single rectangular shape shown in Fig. 6, similar to the side restraint protrusions 21v.

[0026] In addition, instead of or in addition to the innermost portion 21a of the second electromagnetic steel sheet slot edge portion, a convex portion protruding radially inward may be formed, for example, on the outermost portion 21b of the second electromagnetic steel sheet slot edge portion.

[0027] The side restraining protrusions 21v and the bottom restraining protrusions 21w are formed on parts of the second electromagnetic steel sheet slot edge portions 21s and function as protrusions protruding inward of the second slot hole 22, respectively.

[0028] <Formation of rotor slots by first slot holes and second slot holes> Fig. 7 is a perspective view showing the inner surface of the rotor slot 10s of the squirrel-cage rotor 2 according to the first embodiment. Fig. 7 shows the inside of one half of the rotor slot 10s when the rotor slot 10s formed in the rotor core 10 is divided in half along the longitudinal direction, i.e., the radial direction, of the rotor slot 10s.

[0029] When the first electromagnetic steel sheet 11 and the second electromagnetic steel sheet 21 are stacked in the rotation axis direction, as described above, the slot edge portion 11s of the first electromagnetic steel sheet and the slot edge portion 21s of the second electromagnetic steel sheet overlap each other when viewed in the rotation axis direction, except for the bottom constraint protrusion 21w and the two side constraint protrusions 21v. Therefore, the first slot hole 12 and the second slot hole 22 also form a plurality of rotor slots 10s in the circumferential direction, which are through holes in the rotor core 10 that have a constant cross-sectional shape and extend in the rotation axis direction, except for the bottom constraint protrusion 21w and the two side constraint protrusions 21v formed on the second electromagnetic steel sheet 21.

[0030] At the location where the second electromagnetic steel plate 21 is provided in the direction of the rotation axis, a bottom restraining protrusion 21w and two side restraining protrusions 21v protrude inward into this rotor slot 10s.

[0031] Note that FIG. 7 shows an example in which second electromagnetic steel sheets 21 are arranged at intervals among stacked first electromagnetic steel sheets 11. However, the arrangement of the second electromagnetic steel sheets 21 is not limited to this. For example, while FIG. 7 shows one second electromagnetic steel sheet 21 arranged on each side, multiple second electromagnetic steel sheets 21 may be arranged, or multiple sheets may be arranged partially. Alternatively, from the perspective of further enhancing stress reduction at the connection between the slot bar 30 and the end rings 40, multiple second electromagnetic steel sheets 21 may be provided in regions close to each end ring 40 in the rotational axis direction. Alternatively, half of the total number of second electromagnetic steel sheets 21 may be arranged in regions close to each end ring 40. Alternatively, these arrangements may be combined.

[0032] <Slot bar and end ring> Fig. 8 is a vertical cross-sectional view of the upper half along the rotation axis direction showing the configuration of the squirrel-cage rotor 2 according to the first embodiment. Note that the rotor shaft 2a (Fig. 1) is not shown in Fig. 8. Fig. 8 shows the bottom restraining protrusions 21w out of the bottom restraining protrusions 21w and the side restraining protrusions 21v.

[0033] The slot bars 30 in each rotor slot 10s and the end rings 40 at both ends in the rotational axis direction of the rotor core 10 are integrally formed by die casting, in which a metal with high electrical conductivity, such as aluminum, copper, or a copper alloy, is poured into a mold (not shown) attached to the outside of the assembled rotor core 10. Therefore, each of the two integrally formed end rings 40 and the multiple slot bars 30 is a metallic conductor.

[0034] As a result, the bottom restraint protrusions 21w and side restraint protrusions 21v protruding into the rotor slots 10s fit snugly with the slot bar 30. In other words, the bottom restraint protrusions 21w and side restraint protrusions 21v are in close contact with the slot bar 30. As a result, the bottom restraint protrusions 21w and side restraint protrusions 21v are embedded in the slot bar 30.

[0035] The slot bars 30 and end rings 40 formed by die casting are made of aluminum or copper. On the other hand, the first electromagnetic steel sheets 11 and second electromagnetic steel sheets 21 are made of alloy steel with silicon or the like added to iron, for example. Therefore, electromagnetic steel sheets generally have higher strength than the materials of the slot bars 30 and end rings 40.

[0036] <Actions and Effects> The operation and effects of the squirrel-cage rotor 2 according to this embodiment as described above will be described below in order. Fig. 9 is a conceptual vertical cross-sectional view of the upper half along the rotation axis direction, illustrating the effects of the squirrel-cage rotor 2 according to the first embodiment.

[0037] <Previous behavior> Now, let us consider a conventional case in which the bottom restraining protrusions 21w and the side restraining protrusions 21v of this embodiment are not provided. In this case, as shown in Fig. 9, the rotor core 10 has the first electromagnetic steel sheets 11 but does not have the second electromagnetic steel sheets 21.

[0038] When the squirrel-cage rotor 2 rotates at high speed, centrifugal force is applied to each component. Focusing on the slot bar 30, the slot bar outer surface 30a is pressed against the radially outer portion of the inner surface of the rotor slot 10s, i.e., the rotor slot inner surface outer portion 10w, by centrifugal force. In other words, the slot bar 30 is constrained on the radially outer side. In this state, a compressive force acts on the slot bar 30 in the radially outward direction. As a result, the slot bar 30 shrinks in the radial direction, and the slot bar 30 expands in the direction of the rotation axis to compensate for this volume reduction. Furthermore, the slot bar inner surface 30b, which is the radially inner portion of the slot bar 30, is displaced radially outward by the amount of the radial shrinkage of the slot bar 30. Note that these displacements are exaggerated in Figure 9.

[0039] On the other hand, the end ring 40 is an annular member centered on the rotation axis CL. The end ring 40 is located at the same radial position as the slot bar 30 even in a cross section perpendicular to the rotation axis CL, and has a larger radial width than the slot bar 30. Therefore, the radial rigidity of the end ring 40 is greater than that of the slot bar 30. For this reason, even if the end ring 40 is made of the same material as the slot bar 30, its radial displacement due to centrifugal force is much smaller than that of the slot bar 30.

[0040] As a result, high stress occurs near point P, the corner surrounded by a dashed line in Figure 9. That is, the slot bar inner surface 30b tends to displace radially outward, while the end ring 40 only displaces a small amount. That is, the radially outward displacement of the slot bar inner surface 30b is restrained by the end ring 40. As a result, large stress occurs at the connection between the slot bar 30 and the end ring 40, particularly near point P. When the rotation speed of high-speed rotation increases, stress that exceeds the allowable stress occurs, which may result in cracks or even breakage.

[0041] <Operation of this embodiment> On the other hand, in this embodiment, as shown in FIGS. 7 and 8, the rotor core 10 is provided with side restraining protrusions 21v and bottom restraining protrusions 21w that protrude into the rotor slots 10s.

[0042] The side restraint protrusions 21v restrain radial displacement of the slot bar 30. The side restraint protrusions 21v are formed in a position in the radial direction closer to the innermost part 21a of the second electromagnetic steel sheet slot edge portion than to the outermost part 21b of the second electromagnetic steel sheet slot edge portion. In other words, they are provided in a radially inner region of the rotor slot 10s. As a result, they effectively function to restrain radially outward displacement of the slot bar inner surface 30b, which is the radially inner part of the slot bar 30.

[0043] Furthermore, the bottom restraining protrusions 21w restrain the displacement of the slot bars 30 in the rotational axis direction. The side restraining protrusions 21v have a similar effect. As described above, the expansion of the slot bars 30 in the rotational axis direction is caused by a reduction in the radial width of the slot bars 30. Therefore, by restraining the expansion of the slot bars 30 in the rotational axis direction, the degree of radial contraction of the slot bars 30 can be reduced. As a result, the effect of reducing the radially outward displacement of the slot bar inner surfaces 30b can be obtained. Note that, if necessary, in order to ensure the effect of reducing the radially outward displacement of the slot bar inner surfaces 30b, the rotor core 10 may be formed only from the second electromagnetic steel sheets 21, rather than from the first electromagnetic steel sheets 11 and the second electromagnetic steel sheets 21.

[0044] As described above, the side restraint protrusions 21v and bottom restraint protrusions 21w act to reduce stress at the connection between the slot bar 30 and the end ring 40 during high-speed rotation. In other words, the strength of the end ring 40 and the slot bar 30 can be ensured even during high-speed rotation.

[0045] [Second embodiment] FIG. 10 is a partial front view of a second electromagnetic steel sheet 21 that constitutes a rotor core 10 of a squirrel-cage rotor 2 according to the second embodiment, showing second slots 22a formed in the second electromagnetic steel sheet 21.

[0046] This embodiment is a modification of the first embodiment. Regarding the second slot hole 22 in the first embodiment, a side restraint protrusion 21v and a bottom restraint protrusion 21w are provided. However, in this embodiment, instead, a side restraint recess 21x and a bottom restraint recess 21y are provided at the same positions as the first and second slot holes 22. Therefore, the second electromagnetic steel sheet slot edge portion 21s in this embodiment is composed of a second electromagnetic steel sheet slot edge innermost portion 21a, a second electromagnetic steel sheet slot edge outermost portion 21b, a second electromagnetic steel sheet slot edge side portion 21c, a second electromagnetic steel sheet slot edge side portion 21d, a bottom restraint recess 21y, and two side restraint recesses 21x.

[0047] Here, the recesses of the side restraint recess 21x and the bottom restraint recess 21y refer to the portions of the second electromagnetic steel sheet slot edge portion 21s, which is the boundary with the second slot hole 22a, that are recessed from the inside of the second slot hole 22a compared to the first electromagnetic steel sheet 11.

[0048] Other than this, the present embodiment is similar to embodiment 1. The side restraint recesses 21x and the bottom restraint recesses 21y each function as recesses formed in a part of the second electromagnetic steel sheet slot edge portion 21s.

[0049] The shape and number of the side restraint recesses 21x and bottom restraint recesses 21y are not limited to those shown in FIG. 10, and other shapes and numbers may be used, as in the first embodiment.

[0050] In this configuration, the slot bars 30 in each rotor slot 10s and the end rings 40 at both ends of the rotor core 10 in the direction of the rotation axis are integrally formed by injecting a highly conductive metal into the assembled rotor core 10, i.e., by die casting.

[0051] At this time, the good conductor metal is also poured into the side restraint recesses 21x and the bottom restraint recesses 21y.

[0052] In the first embodiment, the side restraining protrusions 21v and the bottom restraining protrusions 21w have the function of restraining the slot bar 30 in the radial direction and in the rotation axis direction.

[0053] On the other hand, in this embodiment, as part of the slot bar 30, the good conductor such as aluminum or copper present in the side restraining recesses 21x and bottom restraining recesses 21y forms convex portions, which have a similar restraining function.

[0054] However, compared to side restraint protrusions 21v and bottom restraint protrusions 21w, which are made of electromagnetic steel sheets, this good conductor portion is made of a material with low strength. For this reason, by increasing the proportion of second electromagnetic steel sheet 21 or by making the dimensions of side restraint recesses 21x and bottom restraint recesses 21y larger than the dimensions of side restraint protrusions 21v and bottom restraint protrusions 21w, it is possible to ensure the same strength for restraint as in the first embodiment.

[0055] As a result, the same effects as those of the first embodiment can be obtained.

[0056] According to the embodiments described above, it is possible to provide a squirrel-cage rotor and a squirrel-cage induction rotating electric machine that can ensure the strength of the end rings and slot bars even during high-speed rotation.

[0057] [Other embodiments] Although the embodiments of the present invention have been described above, they are presented as examples and are not intended to limit the scope of the invention. Furthermore, features of each embodiment may be combined. For example, the convex portion of the first embodiment may be mixed with the concave portion of the second embodiment. Furthermore, the embodiments may be embodied in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. The embodiments and their modifications are within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. [Explanation of symbols]

[0058] 1...squirrel-cage induction rotating electric machine, 2...squirrel-cage rotor, 2a...rotor shaft, 3...stator, 3a...stator core, 3b...stator winding, 4...bearing, 5...bearing bracket, 6...frame, 10...rotor core, 10a...rotor shaft through-hole, 10s...rotor slot, 10w...outer portion of inner surface of rotor slot, 11...first electromagnetic steel sheet, 11a...innermost portion of slot edge of first electromagnetic steel sheet, 11b...outermost portion of slot edge of first electromagnetic steel sheet, 11c, 11d...side portion of slot edge of first electromagnetic steel sheet, 11s...first electromagnetic steel sheet slot edge, 11 t...outer edge, 12...first slot hole, 21...second electromagnetic steel sheet, 21a...innermost part of slot edge portion of second electromagnetic steel sheet, 21b...outermost part of slot edge portion of second electromagnetic steel sheet, 21c, 21d...side part of slot edge portion of second electromagnetic steel sheet, 21s...slot edge portion of second electromagnetic steel sheet, 21t...outer edge, 21v...side restraint convex portion, 21w...bottom restraint convex portion, 21x...side restraint concave portion, 21y...bottom restraint concave portion, 22, 22a...second slot hole, 30...slot bar, 30a...outer surface of slot bar, 30b...inner surface of slot bar, 40...end ring

Claims

1. a rotor shaft extending in the direction of the rotation axis; a rotor core including: a plurality of first electromagnetic steel sheets stacked in the direction of the rotation axis, each having a rotor shaft through hole for passing the rotor shaft therethrough and a plurality of first slot holes formed in the circumferential direction; and a plurality of second electromagnetic steel sheets each having a plurality of second slot holes formed therein so as to overlap the rotor shaft through hole and the plurality of first slot holes in the circumferential direction, a plurality of slot bars each being a metal conductor filled in each of a plurality of rotor slots formed by the plurality of first slot holes and the plurality of second slot holes; annular end rings provided at each end of the rotor core in the rotational axis direction and connected to the plurality of slot bars; Equipped with the second electromagnetic steel sheet further has, in comparison with the first electromagnetic steel sheet, a recess recessed from an inner side of the second slot hole or a protrusion protruding toward the inner side of the second slot hole, at a part of a slot edge portion of the second electromagnetic steel sheet which is a boundary portion of the second slot hole; A cage rotor characterized by:

2. 2. The squirrel-cage rotor according to claim 1, wherein the concave or convex portion is formed at a position closer to the innermost part of the second electromagnetic steel sheet slot edge than to the outermost part of the second electromagnetic steel sheet slot edge, on each of two second electromagnetic steel sheet slot edge side portions extending from the innermost part of the second electromagnetic steel sheet slot edge to the outermost part of the second electromagnetic steel sheet slot edge.

3. 3. The squirrel-cage rotor according to claim 2, wherein the recessed portion or the protruding portion is further formed on at least one of the innermost portion and the outermost portion of the slot edge portion of the second electromagnetic steel sheet.

4. 2. The squirrel-cage rotor according to claim 1, wherein the second electromagnetic steel plates are arranged at intervals in the direction of the rotation axis among the first electromagnetic steel plates stacked in the direction of the rotation axis.

5. 2. The squirrel-cage rotor according to claim 1, wherein the second electromagnetic steel plate is disposed near the end ring in the direction of the rotation axis.

6. A squirrel-cage rotor according to any one of claims 1 to 5; a stator having a stator core disposed radially outside the rotor core and a stator winding wound around the stator core; two bearings that rotatably support the rotor shaft; A squirrel-cage induction rotating electric machine comprising:

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