Squirrel cage rotor and manufacturing method thereof

Abstract

To suppress torque unevenness and facilitate insertion of rod-shaped conductors into slots in a squirrel cage rotor.SOLUTION: A rotating shaft 12 extends in the axial direction. Laminated cores 13a and 13b are fixed to the rotating shaft 12, and a plurality of slots 21 are formed at predetermined angles θs along the circumferential direction and in parallel to the rotating shaft 12, and are spaced apart from each other in the axial direction and shifted in sequence by a predetermined angle θc in the circumferential direction. A rod-shaped conductor 14 is inserted into each slot 21. A cast conductor 16 is cast into one end side of the laminated core 13a located at one end in the axial direction, the other end side of the laminated core 13b located at the other end in the axial direction, between the laminated cores 13a and 13b, and into gaps 22 between the slots 21 and the rod-shaped conductors 14.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a squirrel cage rotor and a method for manufacturing a squirrel cage rotor. [Background technology]

[0002] The squirrel-cage rotor disclosed in Patent Document 1 is formed by inserting rod-shaped conductors into the slots of a laminated core and casting aluminum in it. In order to suppress torque unevenness, the multiple rod-shaped conductors (copper bars) arranged in the circumferential direction are given a skew angle in the circumferential direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 043812 Summary of the Invention [Problem to be solved by the invention]

[0004] When providing a skew angle, the laminated core is formed by laminating steel plates with a circumferential offset, which poses the problem that it is difficult to insert a rod-shaped conductor into a slot having small steps. An object of the present invention is to suppress torque unevenness and to make it easier to insert rod-shaped conductors into slots in a squirrel-cage rotor. [Means for solving the problem]

[0005] A squirrel-cage rotor according to one aspect of the present invention includes a rotating shaft, n laminated cores, a rod-shaped conductor, and a cast conductor, where n is an integer equal to or greater than 2. The rotating shaft extends in the axial direction. The n laminated cores are fixed to the rotating shaft, and a plurality of slots are formed in the n laminated cores, which are inserted parallel to the rotating shaft at predetermined angles θs along the circumferential direction, and are spaced apart from each other in the axial direction and shifted in sequence by a predetermined angle θc in the circumferential direction. The rod-shaped conductors are inserted into each slot. The cast conductors are cast into one end side of the laminated core located at one end in the axial direction, the other end side of the laminated core located at the other end in the axial direction, between the laminated cores, and in the gaps between the slots and the rod-shaped conductors.

[0006] In another embodiment of the present invention, a method for manufacturing a squirrel-cage rotor includes arranging n laminated cores, n being an integer of 2 or more, axially spaced from one another and shifted sequentially in the circumferential direction by a predetermined angle θc. A plurality of slots are formed in the laminated core along the circumferential direction at predetermined angles θs, penetrating the laminated core parallel to the rotation axis, and a rod-shaped conductor is inserted into each slot. Molten metal is then poured into one end side of the laminated core located at one axial end, the other end side of the laminated core located at the other axial end, between the laminated cores, and into the gaps between the slots and the rod-shaped conductors to form cast conductors. Effect of the Invention

[0007] According to the present invention, since two or more laminated cores are offset in the circumferential direction, it is possible to suppress torque unevenness. Furthermore, since the laminated core has a plurality of slots formed therethrough parallel to the rotation axis, it is easy to insert rod-shaped conductors into the slots. [Brief description of the drawings]

[0008] [Figure 1] FIG. [Diagram 2] FIG. 2 is a diagram showing the appearance of a squirrel-cage rotor. [Diagram 3] FIG. 2 is a cross-sectional view of a squirrel-cage rotor. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6] FIG. 2 is a diagram showing current flow paths in a squirrel-cage rotor. [Figure 7] 13A and 13B are diagrams showing modified examples of the rod-shaped conductor. [Figure 8] FIG. 2 is a diagram showing the appearance of a squirrel-cage rotor. [Figure 9] FIG. 2 is a diagram showing the appearance of a squirrel-cage rotor. [Figure 10] FIG. 2 is a cross-sectional view of a squirrel-cage rotor. [Figure 11] FIG. [Figure 12] FIG. [Figure 13] FIG. 2 is a diagram showing current flow paths in a squirrel-cage rotor. [Figure 14] FIG. 2 is a cross-sectional view of a squirrel-cage rotor. [Figure 15] FIG. [Figure 16] FIG. 13 is a diagram showing the arrangement of openings. [Figure 17] FIG. [Figure 18] FIG. 2 is a diagram showing current flow paths in a squirrel-cage rotor. [Figure 19] FIG. 2 is a cross-sectional view of a squirrel-cage rotor. [Figure 20] FIG. 2 is a diagram showing an annular conductor, a laminated core, and spacers. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that each drawing is a schematic view and may differ from the actual one. In addition, the following embodiment illustrates an apparatus and method for embodying the technical idea of ​​the present invention, and does not specify the configuration as described below. In other words, the technical idea of ​​the present invention can be modified in various ways within the technical scope described in the claims.

[0010] First Embodiment "composition" FIG. 1 is a diagram showing the appearance of a squirrel-cage rotor 11. As shown in FIG. Fig. 1(a) shows the squirrel-cage rotor 11 as viewed obliquely from one side of the axial direction, while Fig. 1(b) shows the squirrel-cage rotor 11 as viewed from a direction perpendicular to the axis. The squirrel-cage rotor 11 is a two-stage rotor for a three-phase induction motor, and is formed in a generally cylindrical shape extending in the axial direction. FIG. 2 is a diagram showing the appearance of the squirrel-cage rotor 11. As shown in FIG. Here, the squirrel-cage rotor 11 at a predetermined angular position along the circumferential direction is shown as viewed from one side in the axial direction. The cutting line that passes through the axis center and is perpendicular to the paper surface is taken as A-A, and the cutting line that is shifted clockwise from the cutting line A-A by an angle θc is taken as B-B.

[0011] FIG. 3 is a cross-sectional view of the squirrel cage rotor 11. As shown in FIG. Fig. 1(a) shows a half cross section of the squirrel-cage rotor 11 taken along the cutting line A-A in Fig. 2. Fig. 1(b) shows a half cross section of the squirrel-cage rotor 11 taken along the cutting line B-B in Fig. 2. The squirrel-cage rotor 11 includes a rotating shaft 12, two laminated cores 13a and 13b, a rod-shaped conductor 14, spacers 15, and a cast conductor 16. The rotating shaft 12 has an elongated cylindrical shape extending in the axial direction, and is made of, for example, stainless steel.

[0012] The laminated core 13a and the laminated core 13b are formed into a substantially cylindrical shape by laminating thin annular silicon steel plates in the axial direction, and are fixed to the rotating shaft 12. The laminated core 13a and the laminated core 13b have the same shape and dimensions, and a plurality of slots 21 are formed along the circumferential direction at predetermined angles θs, which penetrate the laminated core 13a and the laminated core 13b in parallel with the rotating shaft 12. The slots 21 are tapered so that they become wider toward the radially outward direction as viewed from the axial direction (FIG. 4), and the entire inner peripheral surface is formed uniformly along the axial direction. The laminated cores 13a and the laminated cores 13b are arranged in order from one side to the other in the axial direction, and are shifted from each other in the axial direction by a predetermined angle θc in the circumferential direction. The cutting line A-A passes through the center of one slot 21 formed in one laminated core 13a as viewed from the axial direction, and the cutting line B-B passes through the center of one slot 21 formed in the other laminated core 13b as viewed from the axial direction.

[0013] The rod-shaped conductor 14 is a copper or copper alloy bar, and is formed in a tapered shape that becomes wider radially outward when viewed from the axial direction, and is inserted closely to the inside of the axial direction of each slot 21. Even after the rod-shaped conductor 14 is inserted into the slot 21, a gap 22 is formed on the outside in the radial direction (FIG. 4). The inside of the rod-shaped conductor 14 is aligned with the inside opening end of the slot 21 in the axial direction, and the outside of the rod-shaped conductor 14 protrudes beyond the outside opening end of the slot 21 in the axial direction. Spacer 15 is formed into a generally cylindrical shape by laminating thin, annular silicon steel plates in the axial direction, and is interposed between laminated core 13a and laminated core 13b and fixed to rotating shaft 12. Spacer 15 has an outer diameter smaller than the outer diameters of laminated core 13a and laminated core 13b and slightly larger than the innermost diameter of slot 21.

[0014] The cast conductor 16 is an aluminum alloy, and is formed by die casting into one end of the laminated core 13a, the other end of the laminated core 13b, between the laminated cores 13a and 13b, and into gaps 22 between the rod-shaped conductors 14 and the slots 21. The gaps 22 connect both ends of the laminated core 13a and both ends of the laminated core 13b, and serve as a flow path through which the molten aluminum alloy flows from one side to the other or vice versa during die casting. The cast conductor 16 includes a pair of end rings 25 and 26, one intermediate ring 27, and a connecting portion 28.

[0015] The end ring 25 is substantially annular, is formed on one end of the laminated core 13a, and electrically connects and shorts the axial outer ends of each of the rod-shaped conductors 14. The end ring 26 is substantially annular, is formed on the other end of the laminated core 13b, and electrically connects and shorts the axial outer ends of each of the rod-shaped conductors 14. The intermediate ring 27 is substantially annular, and is formed between the laminated cores 13a and 13b on the radial outside of the spacer 15, and electrically connects and shorts the axial inner ends of the rod-shaped conductors 14. Since the thickness of the spacer 15 is the thickness of the intermediate ring 27, it is preferable to make the spacer 15 thin in order to prevent the axial size from increasing and to reduce the amount of aluminum alloy. Therefore, the spacer 15 may be made of, for example, only one silicon steel plate. The connecting portion 28 is generally plate-shaped and is formed in the gap 22 of each slot 21 to connect the end ring 25 to the intermediate ring 27 and also to connect the end ring 26 to the intermediate ring 27 .

[0016] FIG. 4 is a diagram showing the laminated core 13a and the laminated core 13b. FIG. 1A shows one laminated core 13a as viewed from one axial direction. FIG. 1B shows the other laminated core 13b as viewed from one axial direction. The slots 21 are tapered so that they become wider as they go radially outward, and a total of 40 slots are formed along the circumferential direction at intervals of θs=9°. The laminated cores 13a and 13b are offset from each other by an angle θc in the circumferential direction. The number of stages of the squirrel-cage rotor 11, that is, the number of laminated cores, is n=2. The angle θc is within ±10% of the value obtained by dividing the angle θs by n. Therefore, the angle difference between the laminated cores 13a and 13b in the circumferential direction is θc=4.5°.

[0017] FIG. 5 is a diagram showing the laminated core 13a, the spacer 15, and the laminated core 13b. In the figure, (a) shows the laminated core 13a, spacer 15, and laminated core 13b separated in the axial direction, viewed obliquely from one side in the axial direction. In the figure, (b) shows the laminated core 13a, spacer 15, and laminated core 13b closely packed in the axial direction, viewed from a direction perpendicular to the axis. The laminated core 13a, spacer 15, and laminated core 13b closely packed in the axial direction are set in a mold, and insert molding is performed by die casting to form the cast conductor 16.

[0018] FIG. 6 is a diagram showing the current flow paths of the squirrel-cage rotor 11. As shown in FIG. Here, the current flow path of the squirrel-cage rotor 11, i.e., the remaining portion excluding the rotating shaft 12, laminated core 13a, laminated core 13b, and spacer pieces 15, is shown as viewed obliquely from one side of the axial direction. First, the end ring 25 and the intermediate ring 27 are connected by the rod-shaped conductor 14 and the connecting portion 28. In addition, the intermediate ring 27 and the end ring 26 are connected by the rod-shaped conductor 14 and the connecting portion 28. This forms a two-stage squirrel-cage current flow path.

[0019] <Action and Effect> Next, main effects of the first embodiment will be described. The cage rotor 11 includes a rotating shaft 12, two laminated cores 13a and 13b, a rod-shaped conductor 14, and a cast conductor 16. The rotating shaft 12 extends in the axial direction. The laminated cores 13a and 13b are fixed to the rotating shaft 12, and a plurality of slots 21 are formed in the laminated cores 13a and 13b, which are passed through the rotating shaft 12 at predetermined angles θs along the circumferential direction and are offset from each other in the axial direction by a predetermined angle θc in the circumferential direction. The rod-shaped conductors 14 are inserted into each slot 21. The cast conductors 16 are cast into one end side of the laminated core 13a located at one end in the axial direction, the other end side of the laminated core 13b located at the other end in the axial direction, between the laminated cores 13a and 13b, and into the gaps 22 between the slots 21 and the rod-shaped conductors 14. In this way, since the two laminated cores 13a and 13b are offset in the circumferential direction, torque unevenness can be suppressed. Furthermore, since the laminated cores 13a and 13b have a plurality of slots 21 formed therethrough parallel to the rotating shaft 12, it is easy to insert the rod-shaped conductor 14 into the slots 21. This is because the inner peripheral surface of the slot 21 is flat along the axial direction and has no unnecessary steps. Therefore, the gap 22 between the slot 21 and the rod-shaped conductor 14 can be made as small as possible, and the cross-sectional area of ​​the rod-shaped conductor 14 can be increased accordingly. Furthermore, since offsetting the laminated cores 13a and 13b in the circumferential direction provides the same effect as a configuration in which the rod-shaped conductor 14 is tilted to provide a skew angle, the skew angle can be freely set simply by changing the relative angle in the circumferential direction.

[0020] Angle θc is within ±10% of the value obtained by dividing angle θs by the number of stages (n=2) of squirrel-cage rotor 11. This makes it possible to set the angle difference of laminated core 13b relative to laminated core 13a by evenly dividing the circumferential spacing of slots 21. Therefore, torque unevenness can be effectively suppressed. The cage rotor 11 includes spacers 15. The spacers 15 are interposed between the laminated cores 13a and 13b. This makes it easy to form the cast conductors 16 cast between the laminated cores 13a and 13b. Therefore, the axial inner ends of the rod-shaped conductors 14 can be electrically connected to each other without providing new connection means such as wiring. Furthermore, by providing the spacers 15, the amount of material cast between the laminated cores 13a and 13b can be reduced, thereby suppressing increases in costs.

[0021] The outer diameter of the spacer 15 is larger than the innermost diameter of the slot 21. This allows the spacer 15 to position the rod-shaped conductor 14, improving ease of manufacture. The outer diameter of the spacer 15 is smaller than the outermost diameter of the slot 21. This ensures a flow path for the molten metal to be cast, and also ensures that the axial inner ends of the rod-shaped conductors 14 are electrically connected to each other. The rod-shaped conductor 14 is made of copper or a copper alloy, which makes it possible to inexpensively realize the squirrel-cage rotor 11 having high electrical conductivity.

[0022] The cast conductor 16 is made of an aluminum alloy, which allows the squirrel cage rotor 11 to have high electrical conductivity and a light weight. The squirrel-cage rotor 11 includes spacers 15. The spacers 15 are interposed between the laminated cores 13a and 13b. The spacers 15 are made of a steel plate having a higher melting point than an aluminum alloy. This prevents the spacers 15 from melting during casting, and allows the cast conductors 16 to be properly formed. The squirrel cage rotor 11 is of a two-stage type with n being 2. Therefore, it is easier to manufacture than a multi-stage type.

[0023] In the manufacturing method of the cage rotor 11, two laminated cores 13a and 13b are arranged axially apart from each other and shifted in the circumferential direction by a predetermined angle θc. A plurality of slots 21 are formed in the laminated cores 13a and 13b, which are parallel to the rotating shaft 12 and are arranged at predetermined angles θs along the circumferential direction, and a rod-shaped conductor 14 is inserted into each slot 21. Molten metal is cast into one end side of the laminated core 13a located at one end in the axial direction, the other end side of the laminated core 13b located at the other end in the axial direction, between the laminated cores 13a and 13b, and into the gaps 22 between the slots 21 and the rod-shaped conductors 14 to form cast conductors 16. In this way, the two laminated cores 13a and 13b are shifted in the circumferential direction, so that torque unevenness can be suppressed. Furthermore, since the laminated core 13a and the laminated core 13b are formed with a plurality of slots 21 penetrating parallel to the rotating shaft 12, the rod-shaped conductors 14 can be easily inserted into the slots 21.

[0024] Next, a comparative example will be described. Here, a comparative example will be described in which a copper bar is tilted in the circumferential direction to provide a skew angle in order to suppress torque unevenness. When providing a skew angle, the laminated core has steel plates laminated with a circumferential shift, which makes it difficult to insert the copper bar into a slot with a small step. In addition, the small step increases the gap between the slot and the copper bar, making it difficult to ensure a sufficient cross-sectional area of ​​the copper bar. Furthermore, when the opening area of ​​the slot is constant, the cross-sectional area of ​​the copper bar is determined by the size of the skew angle, so there are restrictions on the skew angle that can be set, and the degree of freedom in design is limited.

[0025] <<Variation>> In the first embodiment, the rod-shaped conductor 14 is formed from a single copper bar. However, the present invention is not limited to this, and the rod-shaped conductor 14 may be formed by bundling a plurality of conductive wires. FIG. 7 is a diagram showing a modified example of the rod-shaped conductor 14. In FIG. Here, the rod-shaped conductor 14 is shown as viewed from the axial direction. The rod-shaped conductor 14 is formed by bundling a plurality of conductive wires 31. This allows the rod-shaped conductor 14 to be formed using the same conductive wires 31 for other models with different slot shapes, improving productivity. The conductive wires 31 are coated with a material such as silver or tin that has a lower melting point than the conductive wires 31, and are formed by fusing them together. This allows the rod-shaped conductor 14 to be easily formed into a desired cross-sectional shape.

[0026] In the first embodiment, the spacer 15 is provided, but is not limited to this. If the laminated cores 13a, 13b, and rod-shaped conductors 14 are positioned and then casting is performed between the laminated cores 13a and 13b, the spacer 15 may be omitted. In this case, the inner circumference of the intermediate ring 27 contacts the rotating shaft 12. This makes it possible to reduce the number of parts. In the first embodiment, the cross-sectional shape of the gap 22 is described as an elongated rectangle, but the present invention is not limited to this. The cross-sectional shape of the gap 22 may be any shape as long as a flow path for the molten metal to be cast can be secured.

[0027] Second Embodiment "composition" The second embodiment is similar to the first embodiment described above, except that it is a three-stage system, so the same reference numerals are used for common configurations and detailed explanations are omitted. FIG. 8 is a diagram showing the appearance of the squirrel-cage rotor 11. As shown in FIG. Fig. 1(a) shows the squirrel-cage rotor 11 as viewed obliquely from one side of the axial direction, while Fig. 1(b) shows the squirrel-cage rotor 11 as viewed from a direction perpendicular to the axis. The squirrel-cage rotor 11 is a three-stage rotor for a three-phase induction motor, and is formed in a substantially cylindrical shape extending in the axial direction.

[0028] FIG. 9 is a diagram showing the appearance of the squirrel-cage rotor 11. As shown in FIG. Here, the squirrel-cage rotor 11 at a predetermined angular position along the circumferential direction is shown as viewed from one side in the axial direction. The cutting line that passes through the axial center and is perpendicular to the paper surface is designated as A-A, the cutting line shifted clockwise by an angle θc from the cutting line A-A is designated as B-B, and the cutting line shifted clockwise by an angle θc from the cutting line B-B is designated as C-C. FIG. 10 is a cross-sectional view of the squirrel-cage rotor 11. As shown in FIG. FIG. 9(a) shows a half cross section of the squirrel-cage rotor 11 taken along the cutting line A-A in FIG. 9. FIG. 9(b) shows a half cross section of the squirrel-cage rotor 11 taken along the cutting line B-B in FIG. 9. FIG. 9(c) shows a half cross section of the squirrel-cage rotor 11 taken along the cutting line CC in FIG. 9. The squirrel-cage rotor 11 has three laminated cores 13a, 13b, and 13c, and two spacers 15.

[0029] The laminated cores 13a, 13b, and 13c have the same shape and dimensions, are arranged in order from one side in the axial direction to the other, and are offset from each other in the axial direction by a predetermined angle θc in the circumferential direction. The section line A-A passes through the center of one of the slots 21 formed in the laminated core 13a, as viewed from the axial direction. The section line B-B passes through the center of one of the slots 21 formed in the other laminated core 13b, as viewed from the axial direction. The section line C-C passes through the center of one of the slots 21 formed in the laminated core 13c, as viewed from the axial direction. The spacers 15 are fixed to the rotating shaft 12 and are interposed between the laminated cores 13a and 13b, and between the laminated cores 13b and 13c. The cast conductor 16 is provided with two intermediate rings 27 . One intermediate ring 27 is formed between the laminated cores 13a and 13b on the radial outside of the spacer 15, and electrically connects and shorts the axial inner ends of each rod-shaped conductor 14. The other intermediate ring 27 is formed between the laminated cores 13b and 13c on the radial outside of the spacer 15, and electrically connects and shorts the axial inner ends of each rod-shaped conductor 14.

[0030] FIG. 11 is a diagram showing the laminated core 13a, the laminated core 13b, and the laminated core 13c. FIG. 1A shows one laminated core 13a as viewed from one axial direction. FIG. 1B shows the central laminated core 13b as viewed from one axial direction. FIG. 1C shows the other laminated core 13c as viewed from one axial direction. The laminated cores 13a and 13b are offset from each other in the circumferential direction by an angle θc, and the laminated cores 13a and 13c are offset from each other in the circumferential direction by twice the angle θc (2θc). The number of stages in the squirrel-cage rotor 11, i.e., the number of laminated cores, is n=3. The angle θc is within ±10% of the value obtained by dividing the angle θs by n. Therefore, the angle difference between the laminated cores 13a and 13b in the circumferential direction is θc=3°. Moreover, the angular difference between the laminated cores 13b and 13c in the circumferential direction is θc=3°, and the angular difference between the laminated cores 13a and 13c in the circumferential direction is θc=6°.

[0031] FIG. 12 is a diagram showing a laminated core 13a, a spacer 15, a laminated core 13b, a spacer 15, and a laminated core 13c. In the figure, (a) shows the laminated core 13a, spacer 15, laminated core 13b, spacer 15, and laminated core 13c separated in the axial direction, viewed obliquely from one side in the axial direction. In the figure, (b) shows the laminated core 13a, spacer 15, laminated core 13b, spacer 15, and laminated core 13c closely packed in the axial direction, viewed from a direction perpendicular to the axis. The laminated core 13a, spacer 15, laminated core 13b, spacer 15, and laminated core 13c closely packed in the axial direction are set in a mold, and insert molding is performed by die casting to form a cast conductor 16.

[0032] FIG. 13 is a diagram showing the current flow paths of the squirrel-cage rotor 11. As shown in FIG. Here, the current flow path of the squirrel-cage rotor 11, i.e., the rotating shaft 12, laminated core 13a, spacer 15, laminated core 13b, spacer 15, and laminated core 13c are omitted, and the remaining portion is shown as viewed obliquely from one side of the axial direction. First, the end ring 25 and one of the intermediate rings 27 are connected by the rod-shaped conductor 14 and the connecting portion 28. Also, the one intermediate ring 27 and the other intermediate ring 27 are connected by the rod-shaped conductor 14 and the connecting portion 28. Furthermore, the other intermediate ring 27 and the end ring 26 are connected by the rod-shaped conductor 14 and the connecting portion 28. This forms a three-stage squirrel-cage current flow path.

[0033] <Action and Effect> Next, the main effects of the second embodiment will be described. The cage rotor 11 is a three-stage type with n being 3. That is, the cage rotor 11 includes three laminated cores 13a, 13b, and 13c. Therefore, it is easier to manufacture than a multi-stage type. Other effects brought about by the common configuration are similar to those of the first embodiment described above. <<Variation>> In the second embodiment, a three-stage type has been described, but the present invention is not limited to this and may be four or more stages. This can further suppress torque unevenness. That is, in the squirrel-cage rotor 11 having n laminated cores, n may be an integer of 2 or more.

[0034] Third Embodiment "composition" The third embodiment shows another aspect of the spacer 15, and is otherwise similar to the first embodiment described above. Therefore, the same reference numerals are used for common configurations and detailed explanations are omitted. FIG. 14 is a cross-sectional view of the squirrel-cage rotor 11. As shown in FIG. FIG. 1A shows a half-section of the squirrel-cage rotor 11 taken along the line A-A. FIG. 1B shows a half-section of the squirrel-cage rotor 11 taken along the line B-B. The squirrel-cage rotor 11 is provided with spacers 35. The spacer 35 has the same outer diameter as the laminated core 13a and the laminated core 13b.

[0035] FIG. 15 is a diagram showing the spacer piece 35. As shown in FIG. FIG. 1(a) shows the spacer 35 as viewed obliquely from one side of the axial direction. FIG. 1(b) shows the spacer 35 as viewed from the axial direction. The spacer 35 has openings 36 formed therethrough in the axial direction at positions overlapping with the slots 21 as viewed from the axial direction. The openings 36 extend in an arch shape along the circumferential direction and are formed at predetermined intervals along the circumferential direction. Here, the arch angle is set to 60°, and six openings 36 are formed along the circumferential direction. The spaces between the openings 36 are portions that connect the radial inside and outside of the spacer 35, and it is preferable that they are as thin as possible as long as the necessary strength can be ensured.

[0036] FIG. 16 is a diagram showing the arrangement of the openings 36. As shown in FIG. FIG. 1(a) shows the laminated core 13a and the spacer 35 as viewed from the other axial direction. FIG. 1(b) shows the laminated core 13b and the spacer 35 as viewed from one axial direction. The openings 36 have an innermost diameter larger than the innermost diameter of the slots 21 and an outermost diameter smaller than the outermost diameter of the slots 21. The openings 36 are formed in the spacer 35 at positions overlapping the slots 21 as viewed from the axial direction, and seven rod-shaped conductors 14 are arranged to overlap one opening 36, with one rod-shaped conductor 14 overlapping two openings 36 in some locations.

[0037] FIG. 17 is a diagram showing the laminated core 13a, the spacer 35, and the laminated core 13b. In the figure, (a) shows the laminated core 13a, spacer 35, and laminated core 13b separated in the axial direction, viewed obliquely from one side in the axial direction. In the figure, (b) shows the laminated core 13a, spacer 35, and laminated core 13b closely packed in the axial direction, viewed from a direction perpendicular to the axis. The laminated core 13a, spacer 35, and laminated core 13b closely packed in the axial direction are set in a mold, and insert molding is performed by die casting to form the cast conductor 16.

[0038] FIG. 18 is a diagram showing the current flow paths of the squirrel-cage rotor 11. Here, the current flow path of the squirrel-cage rotor 11, i.e., the remaining portion excluding the rotating shaft 12, laminated core 13a, spacer pieces 35, and laminated core 13b, is shown as viewed obliquely from one side of the axial direction. First, the end ring 25 and the intermediate ring 27 divided into six pieces are connected by the rod-shaped conductors 14 and the connecting parts 28. In addition, the intermediate ring 27 divided into six pieces and the end ring 26 are connected by the rod-shaped conductors 14 and the connecting parts 28. This forms a two-stage squirrel-cage current flow path.

[0039] <Action and Effect> Next, main effects of the third embodiment will be described. The spacer 35 has the same outer diameter as the laminated cores 13a and 13b, and has an opening 36 penetrating therethrough in the axial direction at a position overlapping with the slot 21 when viewed from the axial direction. This allows the axial inner ends of the rod-shaped conductors 14 to be electrically connected to each other by the intermediate ring 27 formed in the opening 36. In addition, the amount of material to be cast between the laminated cores 13a and 13b can be reduced, suppressing increases in costs.

[0040] The openings 36 extend in an arch shape in the circumferential direction and are formed at predetermined intervals in the circumferential direction. This makes it possible to minimize the opening area. This reliably reduces the amount of material to be cast between the laminated cores 13a and 13b, thereby preventing increases in costs. The opening 36 has an innermost diameter larger than the innermost diameter of the slot 21 and an outermost diameter smaller than the outermost diameter of the slot 21. This allows the rod-shaped conductor 14 to be positioned by the spacer 35, improving ease of manufacture. Other effects brought about by the common configuration are similar to those of the first embodiment described above.

[0041] Fourth Embodiment "composition" The fourth embodiment is similar to the first embodiment described above, except for the addition of a configuration for connecting the axial outer ends of the rod-shaped conductors 14 to each other. Therefore, the common configurations are given the same symbols and detailed descriptions are omitted. FIG. 19 is a cross-sectional view of the squirrel-cage rotor 11. As shown in FIG. FIG. 1A shows a half cross section of the squirrel-cage rotor 11 taken along the line A-A. FIG. 1B shows a half cross section of the squirrel-cage rotor 11 taken along the line B-B. The squirrel-cage rotor 11 includes an annular conductor 41 and an annular conductor 42. The annular conductor 41 is made of copper or a copper alloy and is formed on one end of the laminated core 13a, and electrically connects and shorts the axial outer ends of each of the rod-shaped conductors 14. The annular conductor 42 is made of copper or a copper alloy and is formed on the other end of the laminated core 13b, and electrically connects and shorts the axial outer ends of each of the rod-shaped conductors 14.

[0042] FIG. 20 is a diagram showing the annular conductor 41, the laminated core 13a, the spacer 15, the laminated core 13b, and the annular conductor 42. As shown in FIG. FIG. 1(a) shows the annular conductor 41, laminated core 13a, spacer 15, laminated core 13b, and annular conductor 42, which are separated in the axial direction, as viewed obliquely from one side of the axial direction. FIG. 1(b) shows the annular conductor 41, laminated core 13a, spacer 15, laminated core 13b, and annular conductor 42, which are tightly packed in the axial direction, as viewed perpendicular to the axis. The annular conductor 41, laminated core 13a, spacer 15, laminated core 13b, and annular conductor 42, which are tightly packed in the axial direction, are set in a mold, and insert molding is performed by die casting to form the cast conductor 16. At this time, the annular conductor 41 and the annular conductor 42 are joined to the rod-shaped conductor 14 by brazing or the like.

[0043] <Action and Effect> Next, main effects of the fourth embodiment will be described. An annular conductor 41 and an annular conductor 42 are provided inside the cast conductor 16 at one end side of the laminated core 13a located at one axial end, and at the other end side of the laminated core 13b located at the other axial end, and are connected to each rod-shaped conductor 14. This ensures that the axial outer ends of each rod-shaped conductor 14 are electrically connected and short-circuited. In addition, the amount of material cast at one end side of the laminated core 13a and the other end side of the laminated core 13b can be reduced, suppressing increases in costs. The annular conductors 41 and 42 are made of copper or a copper alloy, which makes it possible to inexpensively realize the squirrel-cage rotor 11 having high electrical conductivity. Other effects brought about by the common configuration are similar to those of the first embodiment described above.

[0044] Although the above description has been given with reference to a limited number of embodiments, the scope of the invention is not limited thereto, and modifications of the embodiments based on the above disclosure will be obvious to those skilled in the art. [Explanation of symbols]

[0045] 11... rotor, 12... rotating shaft, 13a... laminated core, 13b... laminated core, 13c... laminated core, 14... rod-shaped conductor, 15... spacer, 16... cast conductor, 21... slot, 22... gap, 25... end ring, 26... end ring, 27... intermediate ring, 28... connecting portion, 31... conductor, 35... spacer, 36... opening, 41... annular conductor, 42... annular conductor

Claims

1. n is an integer of 2 or more, A rotating shaft extending in an axial direction; n laminated cores, each of which is fixed to the rotating shaft, and has a plurality of slots formed therethrough in a circumferential direction at predetermined intervals of an angle θs, the slots being parallel to the rotating shaft, and the n laminated cores being spaced apart from each other in the axial direction and shifted in sequence by a predetermined angle θc in the circumferential direction; A rod-shaped conductor inserted into each of the slots; A squirrel-cage rotor comprising: one end side of the laminated core located at one axial end; the other end side of the laminated core located at the other axial end; and a cast conductor cast into the gaps between the laminated cores and the rod-shaped conductors of the slots.

2. 2. The squirrel cage rotor according to claim 1, wherein the angle θc is within ±10% of a value obtained by dividing the angle θs by the angle n.

3. 2. A squirrel cage rotor according to claim 1, further comprising spacers interposed between said laminated cores.

4. 4. A squirrel cage rotor as claimed in claim 3, wherein said spacer has an outer diameter larger than an innermost diameter of said slot.

5. 5. A squirrel cage rotor as claimed in claim 4, wherein said spacer has an outer diameter smaller than the outermost diameter of said slot.

6. 5. The squirrel cage rotor according to claim 4, wherein the spacer has the same outer diameter as the laminated core, and has an opening penetrating therethrough in the axial direction at a position overlapping with the slot when viewed in the axial direction.

7. 7. The squirrel cage rotor according to claim 6, wherein the openings extend in an arch shape along the circumferential direction and are formed at predetermined intervals along the circumferential direction.

8. 8. The squirrel cage rotor of claim 7, wherein said opening has an innermost diameter larger than an innermost diameter of said slot and an outermost diameter smaller than an outermost diameter of said slot.

9. 2. The squirrel cage rotor according to claim 1, wherein said rod-shaped conductor is made of copper or a copper alloy.

10. 2. The squirrel cage rotor according to claim 1, wherein the rod-shaped conductor is formed by bundling a plurality of conducting wires.

11. 11. The squirrel cage rotor according to claim 10, wherein the conductor wires are coated with a material having a lower melting point than the conductor wires and are fused together to form the conductor wires.

12. 2. The squirrel cage rotor of claim 1, wherein said cast conductor is an aluminum alloy.

13. A spacer is provided between the laminated cores, 13. The squirrel cage rotor according to claim 12, wherein said spacer pieces are formed of steel plates having a melting point higher than that of said aluminum alloy.

14. A cage rotor as described in claim 1, characterized in that it is provided with an annular conductor arranged inside the cast conductor and connected to each of the rod-shaped conductors at one end side of the laminated core located at one axial end and at the other end side of the laminated core located at the other axial end.

15. 15. The squirrel cage rotor of claim 14, wherein the annular conductor is made of copper or a copper alloy.

16. n is an integer of 2 or more, a plurality of slots are formed in the circumferential direction at predetermined angles θs, the slots being parallel to the rotation axis, and n laminated cores having rod-shaped conductors inserted therein are arranged axially spaced from one another and shifted in sequence by a predetermined angle θc in the circumferential direction; A manufacturing method for a squirrel-cage rotor, characterized in that molten metal is poured into one end side of the laminated core located at one axial end, the other end side of the laminated core located at the other axial end, between the laminated cores, and in the gaps between the slots and the rod-shaped conductors to form cast conductors.

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