Rotor and rotating machine equipped therewith

Abstract

The present invention provides a rotor that can reduce the maximum stress caused by differences in the coefficient of linear expansion of different materials in near-extremely low temperature environments. [Solution] The squirrel-cage rotor of the present invention comprises a shaft, a cylindrical core formed by laminating first electromagnetic steel sheets having an opening in which the shaft is arranged, a support ring positioned on the end face of the core and having an opening in which the shaft is arranged, a plurality of conductor bars embedded in a plurality of slots formed at circumferential intervals on the outer circumference of the core, and end rings connecting the conductor bars at both ends of the core. The support ring is positioned radially inward from the slots of the core and forms a stepped portion that protrudes axially outward at the connection point with the end face of the core, and the end ring presses the support ring toward the end face of the core.

Description

Technical Field

[0001] The present invention relates to, for example, a rotor and a rotating machine including the same.

Background Art

[0002] Conventionally, as a cage-type rotor 501 of a rotating machine, as shown in FIG. 7, there is known one having a shaft 510, a cylindrical core 520 disposed on the outer peripheral side of the shaft 510, conductor bars 561 embedded in a plurality of slots 521 formed in the outer peripheral portion of the core 520, and end rings 562 connecting the conductor bars 561 at both ends of the core 520.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the cage-type rotor 501, when the core 520 is formed of an iron electromagnetic steel sheet and the conductor bars 561 and the end rings 562 are formed of aluminum, the linear expansion coefficients of the conductor bars 561 and the end rings 562 are larger than the linear expansion coefficient of the core 520. In particular, in an environment near extremely low temperatures (such as in a liquefied gas environment of liquefied natural gas, liquefied petroleum gas, liquefied nitrogen, liquefied hydrogen, etc.), since the conductor bars 561 are rod-shaped, they tend to contract in the axial direction, and since the end rings 562 are annular, they tend to contract toward the center of the ring.

[0005] At that time, the core 520 also contracts, but due to the material properties, the rate of change is smaller than that of the conductor bar 561 and end ring 562. As shown in Figure 6(a), in an environment near the cryogenic temperature, thermal stress due to the difference in the coefficient of linear expansion of each material may concentrate locally in part 503a, potentially causing the material to fracture. In recent years, rotating machinery has increasingly been used in liquid hydrogen environments, where the ambient temperature is around -250°C, resulting in greater thermal stress. Therefore, measures to reduce the maximum stress are necessary.

[0006] This invention was made in view of these problems, and its main objective is to provide a rotor and a rotating machine equipped therewith that can reduce the maximum stress due to the difference in the coefficient of linear expansion of each material in an environment near the cryogenic temperature. [Means for solving the problem]

[0007] In other words, the rotor of a rotating machine according to the present invention comprises a shaft, a cylindrical core formed by laminating first electromagnetic steel sheets having an opening in which the shaft is arranged, a support ring disposed on the end face of the core and having an opening in which the shaft is arranged, a plurality of conductor bars embedded in a plurality of slots formed at circumferential intervals on the outer circumference of the core, and end rings connecting the conductor bars at both ends of the core, wherein the support ring is arranged radially inward from the slots of the core and forms a stepped portion that protrudes axially outward at the connection point with the end face of the core, and the end ring presses the support ring toward the end face of the core.

[0008] As a result, a step is formed at the connection between the end face of the core and the support ring. Therefore, in near-cryogenic environments, when the conductor bar tries to contract axially and the end ring tries to contract toward the annular center, the surface that receives the contraction force of the conductor bar is divided into two locations (the end face of the core and the end face of the support ring), and the contraction force of the end ring is received by the wide outer surface of the support ring. Thus, in near-cryogenic environments, the location of thermal stress caused by the difference in linear expansion coefficients of each material can be widely dispersed, thereby reducing the maximum stress.

[0009] In the rotor of a rotating machine according to the present invention, the support ring is preferably formed by laminating a plurality of second electromagnetic steel sheets.

[0010] This reduces losses by suppressing eddy currents that occur in areas where magnetic flux flows.

[0011] In the rotor of a rotating machine according to the present invention, the support ring is preferably formed by laminating a second electromagnetic steel sheet of the same shape.

[0012] This allows the second electrical steel sheet of the support ring to be manufactured using a single mold.

[0013] In the rotor of a rotating machine according to the present invention, it is preferable that the first electrical steel sheet and the second electrical steel sheet are formed from the same material.

[0014] As a result, the coefficient of thermal expansion of the first electrical steel sheet of the core and the coefficient of thermal expansion of the second electrical steel sheet of the support ring become the same, so that the shape of the stepped portion formed at the connection between the support ring and the end face of the core can be kept constant regardless of the ambient temperature.

[0015] In the rotor of a rotating machine according to the present invention, the support rings are preferably arranged at both axial ends of the core.

[0016] As a result, the maximum stress can be reduced at both ends of the core.

[0017] The rotating machine according to the present invention is provided in any one of the above-described rotors.

[0018] As a result, it is possible to provide a rotating machine including a rotor that can solve the problem of locally generating thermal stress in an environment near extremely low temperatures.

Brief Description of the Drawings

[0019] [Figure 1] It is a cross-sectional view of the cage-type rotor 1 according to the present embodiment. [Figure 2] It is a perspective view of the support ring 50. [Figure 3] It is a perspective cross-sectional view of the cage-type rotor 1 in FIG. 1. [Figure 4] It is a perspective view of the cage-type rotor 1 in FIG. 1. [Figure 5] It is a flowchart showing the procedure for manufacturing the cage-type rotor 1 in FIG. 1. [Figure 6] FIG. 6(a) is a diagram showing a location where thermal stress occurs in the conventional cage-type rotor 501, and FIG. 6(b) is a diagram showing a location where thermal stress occurs in the cage-type rotor 1 in FIG. 1. [Figure 7] It is a perspective cross-sectional view of the conventional cage-type rotor 501.

Embodiments for Carrying Out the Invention

[0020] Hereinafter, the cage-type rotor 1 of the rotating machine according to the embodiment of the present invention will be described with reference to the drawings.

[0021] The squirrel-cage rotor 1 of this embodiment is used together with a stator that generates a rotating magnetic flux by a three-phase alternating current to constitute a squirrel-cage three-phase induction motor (rotating machine). As shown in Figure 1, the squirrel-cage rotor 1 has a shaft 10, a cylindrical core 20 arranged on the outer circumference of the shaft 10, two support rings 50 arranged at both ends of the core 20, and conductors 60 that tighten and fix the support rings 50 to the core 20 in the axial direction.

[0022] The core 20 is formed by laminating multiple circular plate-shaped members, which are electromagnetic steel sheets 20n (first electromagnetic steel sheets). A circular opening 20a is formed on the inner circumference of the electromagnetic steel sheets 20n, in which the shaft 10 is placed. Multiple slots 21 are formed on the outer circumference of the core 20 (electromagnetic steel sheets 20n) at intervals in the circumferential direction. The electromagnetic steel sheets 20n are, for example, made mainly of iron, and the average coefficient of linear expansion of the electromagnetic steel sheets 20n is approximately 12 × 10⁻¹⁰ -6 / K(20~0℃), approx. 9×10 -6 The temperature range is / K (20 to -200℃).

[0023] As shown in Figure 2, the support ring 50 is made by laminating multiple circular plate-shaped members, which are electromagnetic steel sheets 50n (second electromagnetic steel sheets). A circular opening 50a is formed on the inner circumference of the electromagnetic steel sheet 50n, where the shaft 10 is placed. The outer shape of the electromagnetic steel sheet 50n is circular, and the outer diameter of the electromagnetic steel sheet 50n is smaller than the outer diameter of the electromagnetic steel sheet 20n of the core 20. The electromagnetic steel sheet 50n is made of the same material as the electromagnetic steel sheet 20n. For example, the electromagnetic steel sheet 50n is made mainly of iron, and the average coefficient of linear expansion of the electromagnetic steel sheet 20n is approximately 12 × 10⁻¹⁰. -6 / K(20~0℃), approx. 9×10 -6 The temperature range is / K (20 to -200℃).

[0024] The conductor 60 has a conductor bar 61 embedded in a slot 21 of the core 20, and end rings 62 connecting the multiple conductor bars 61 at both ends of the core 20. The conductor bar 61 penetrates the core 20 axially, and the two end rings 62 are positioned at both ends of the core 20. The conductor 60 is made of, for example, aluminum, and the average coefficient of linear expansion of the conductor 60 is approximately 12 × 10⁻¹⁰.-6 / K(20~0℃), approx. 9×10 -6 The temperature range is / K (20 to -200℃).

[0025] In the squirrel-cage rotor 1, the core 20 is made of iron electromagnetic steel sheet, and the conductor bars 61 and end rings 62 are made of aluminum. The coefficients of thermal expansion of the conductor bars 61 and end rings 62 are greater than those of the core 20. In particular, in near-cryogenic environments (liquid gas environments such as liquefied natural gas, liquefied petroleum gas, liquefied nitrogen, and liquefied hydrogen), the conductor bars 61, being rod-shaped, tend to contract axially, and the end rings 62, being annular, tend to contract toward the annular center. The end rings 62 press the support rings 50 toward the end face of the core 20. As a result, the conductors 60 press the two support rings 50 toward the ends of the core 20.

[0026] The shaft 10 has a keyway 31 formed along its axial direction on its outer circumferential surface 10a, and a key 30 protruding outward from the outer circumferential surface 10a of the shaft 10 is positioned inside the keyway 31. A keyway 32 extending in the axial direction is formed on the inner circumferential surface of the core 20 (the upper end of the inner circumferential surface of the core 20 in Figure 1), and a keyway 33 extending in the thickness direction is formed on the inner circumferential surface of the support ring 50 (the upper end of the inner circumferential surface of the support ring 50 in Figure 1). With the two support rings 50 positioned at both ends of the core 20, the key 30 protruding outward from the outer circumferential surface 10a of the shaft 10 engages with the keyway 32 and the keyway 33. Therefore, when the shaft 10 rotates, the rotational torque of the shaft 10 is transmitted to the core 20 via the key 30, causing the shaft 10 and the core 20 to rotate together. The shaft 10 is made of, for example, stainless steel, and the average coefficient of linear expansion of the shaft 10 is approximately 15 × 10⁻⁶. -6 / K(20~0℃), approx. 13×10 -6 The temperature range is / K (20 to -200℃).

[0027] Figure 3 is a perspective view of the squirrel-cage rotor 1, but the shaft 10 and key 30 are not shown. With the two support rings 50 positioned at both ends of the core 20, the support rings 50 are positioned radially inward from the slots 21 of the core 20, as shown in Figures 3 and 4. Therefore, the outer circumference of the support rings 50 is positioned radially outward from the radially inward end 21a of the slots 21.

[0028] The inner diameter of the opening 50a of the electromagnetic steel sheet 50n of the support ring 50 is approximately the same as the inner diameter of the opening 20a of the electromagnetic steel sheet 20n of the core 20. Therefore, when the shaft 10 is press-fitted into the opening 20a of the electromagnetic steel sheet 20n of the core 20 and the openings 50a of the electromagnetic steel sheets 50n of the two support rings 50, as shown in Figure 1, the outer circumferential surface 10a of the shaft 10 and the inner surface (inner circumferential surface) of the opening 20a of the electromagnetic steel sheet 20n of the core 20 come into contact, and the outer circumferential surface 10a of the shaft 10 also comes into contact with the inner surface of the opening 50a of the electromagnetic steel sheet 50n of the support ring 50.

[0029] The manufacturing method of the cage rotor 1 of this embodiment will be described with reference to Figure 5.

[0030] (Step S1) A core 20 is created by laminating multiple electrical steel sheets 20n.

[0031] (Step S2) Multiple electrical steel sheets 50n are laminated together to create two support rings 50, and the two support rings 50 are placed at both ends of the core 20.

[0032] (Step S3) The core 20 and two support rings 50 are cast from aluminum, and the core 20 and the two support rings 50 are integrally molded to create a core-support ring assembly. In the core-support ring assembly, the core 20 and the two support rings 50 are integrally fixed by a conductor 60.

[0033] (Step S4) The core-support ring assembly is shrink-fitted (press-fitted) onto the shaft 10.

[0034] (Step S5) The cage rotor 1, in which the shaft 10 is positioned within the core-support ring assembly, is completed.

[0035] In the cage rotor 1 of this embodiment, when the core-support ring assembly is shrink-fitted (press-fitted) onto the shaft 10, the shaft 10, core 20, and support ring 50 are press-fitted with an appropriate interference fit at the ambient temperature during use. As a result, the shaft 10 and the core-support ring assembly rotate as a single unit.

[0036] Figure 6(a) shows a part of the conventional squirrel-cage rotor 501 shown in Figure 7. In the squirrel-cage rotor 501, when the core 520 is made of iron electromagnetic steel sheet and the conductor bars 561 and end rings 562 are made of aluminum, the coefficients of linear expansion of the conductor bars 561 and end rings 562 are greater than those of the core 520. In particular, in near-zero temperature environments (liquid gas environments such as liquefied natural gas, liquefied petroleum gas, liquefied nitrogen, and liquefied hydrogen), the conductor bars 561, being rod-shaped, tend to contract axially, and the end rings 562, being annular, tend to contract toward the center of the annulus. At that time, the core 520 also contracts, but due to the material properties, its rate of change is smaller than that of the conductor bars 561 and end rings 562. Therefore, in near-zero temperature environments, thermal stress due to the difference in the coefficients of linear expansion of each material occurs locally (part 503a in Figure 6(a)).

[0037] In contrast, Figure 6(b) shows a part of the squirrel-cage rotor 1 shown in Figure 1, where the support ring 50 is positioned on the end face of the core 20. As shown in Figure 6(b), radially inward from the slot 21 of the core 20, the support ring 50 protrudes axially outward from the end face of the core 20. In the squirrel-cage rotor 1, especially in near-cryogenic environments (liquid gas environments such as liquefied natural gas, liquefied petroleum gas, liquefied nitrogen, and liquefied hydrogen), the conductor bar 61 tends to contract axially, and the end ring 62 tends to contract toward the annular center. At that time, in the squirrel-cage rotor 1, a stepped portion N is formed at the connection between the end face of the core 20 and the support ring 50, so the surface that receives the contraction force of the conductor bar 61 is divided into two places (the end face of the core 20 and the end face of the support ring 50), and the contraction force of the end ring 62 is received by the wider surface of the end face of the support ring 50. Therefore, in near-extremely low temperature environments, the thermal stress caused by the difference in the coefficients of linear expansion of each material is distributed to two locations (the two parts 3a in Figure 6(b)), reducing the maximum stress.

[0038] In the cage rotor 1 of this embodiment, the maximum value of the generated stress is reduced, which increases the safety factor of the mechanical strength and thus the fatigue strength. Furthermore, since materials with lower strength can be used, the degree of freedom in material selection is increased (and thus the degree of freedom in electrical design).

[0039] In the cage rotor 1 of this embodiment, the opening (shaft hole) 50a and keyway 33 of the support ring 50 can be the same dimensions as the opening (shaft hole) 20a and keyway 32 of the core 20, so the press die for processing can be shared between the support ring 50 and the core 20.

[0040] The cage rotor 1 of this embodiment comprises a shaft 10, a cylindrical core 20 made of laminated electromagnetic steel sheets 20n (first electromagnetic steel sheets) having an opening 20a in which the shaft 10 is placed, a support ring 50 placed on the end face of the core 20 and having an opening 51a in which the shaft 10 is placed, a plurality of conductor bars 61 embedded in a plurality of slots 21 formed at circumferential intervals on the outer circumference of the core 20, and end rings 62 connecting the conductor bars 61 at both ends of the core 20. The support ring 50 is positioned radially inward from the slots 21 of the core 20, and is arranged to form a stepped portion N that protrudes axially outward at the connection point with the end face of the core 20, and the end rings 62 press the support ring 50 toward the end face of the core 20.

[0041] As a result, a stepped portion N is formed at the connection between the end face of the core 20 and the support ring 50. Therefore, in near-cryogenic environments, when the conductor bar 61 attempts to contract axially and the end ring 62 attempts to contract toward the annular center, the surface receiving the contraction force of the conductor bar 61 is divided into two locations (the end face of the core 10 and the end face of the support ring 50), while the contraction force of the end ring 62 is received by the wide outer surface of the support ring 50. Consequently, in near-cryogenic environments, the location of thermal stress caused by differences in the coefficients of linear expansion of each material can be widely dispersed, thereby reducing the maximum stress.

[0042] In the cage rotor 1 of this embodiment, the support ring 50 is formed by laminating a plurality of electromagnetic steel sheets 50n (first electromagnetic steel sheets).

[0043] This reduces losses by suppressing eddy currents that occur in areas where magnetic flux flows.

[0044] In the cage rotor 1 of this embodiment, the support ring 50 is formed by laminating electromagnetic steel sheets 50n (first electromagnetic steel sheets) of the same shape.

[0045] This allows the electrical steel sheet 50n of the support ring 50 to be manufactured using a single mold.

[0046] In the cage rotor 1 of this embodiment, the first electrical steel sheet 20a and the second electrical steel sheet 50a are formed from the same material.

[0047] As a result, the coefficient of thermal expansion of the first electrical steel sheet 20a of the core 20 and the coefficient of thermal expansion of the second electrical steel sheet 50a of the support ring 50 become the same, so that the shape of the stepped portion N formed at the connection between the support ring 50 and the end face of the core 20 can be kept constant regardless of the ambient temperature.

[0048] In the cage rotor 1 of this embodiment, the support rings 50 are arranged at both axial ends of the core 20.

[0049] This allows for a reduction in maximum stress at both ends of the core 20.

[0050] The rotating machine of this embodiment is provided on any of the squirrel-cage rotors 1 described above.

[0051] This makes it possible to provide a rotating machine equipped with a squirrel-cage rotor 1 that can solve the problem of localized thermal stress occurring in near-extremely low temperature environments.

[0052] However, the present invention is not limited to the embodiments described above.

[0053] In the above embodiment, the support ring 50 is formed by laminating a plurality of electromagnetic steel sheets 50n, but it is not limited to this. The support ring 50 may be formed from a single plate-like member having a predetermined thickness.

[0054] The support ring 50 in the above embodiment is made of the same material as the core 20, and its coefficient of thermal expansion is the same as that of the core 20, but is not limited to that. For example, the material of the support ring 50 is arbitrary, and it may be made of a different material from the core 20.

[0055] In the above embodiment, the squirrel-cage rotor 1 was manufactured by shrink-fitting (press-fitting) the core-support ring assembly onto the shaft 10 while it was heated, but the invention is not limited to this. For example, the squirrel-cage rotor 1 may be manufactured by shrink-fitting (press-fitting) the core-support ring assembly at room temperature onto the shaft 10 while it is cooled.

[0056] In the above embodiment, the key 30 is positioned between the shaft 10 and the core 20 and support ring 50, but it is not limited to this. In the present invention, the key 30 does not have to be positioned between the core 20 and support ring 50.

[0057] The above embodiments describe an aluminum squirrel-cage rotor, but are not limited thereto. The present invention is also applicable to copper squirrel-cage rotors. Copper squirrel-cage rotors may be formed by casting copper, or they may not be cast copper. If they are not cast copper, the conductor bars 61 and end rings 62 are connected by brazing, and the end rings 62 and support rings 50 are connected by shrink fitting or press fitting. The present invention is applicable to rotors that use a core, for example, induction motor rotors or induction generator rotors that have end rings on the rotor.

[0058] Furthermore, the specific configuration of each part is not limited to the above embodiment, and the present invention Various modifications are possible as long as they do not deviate from the original purpose. [Explanation of Symbols]

[0059] 1. Cage-type rotor 10 shafts 20 cores 20a opening 20n electromagnetic steel sheet (No. 1 electromagnetic steel sheet) 21 slots 50 support rings 50a opening 50n electromagnetic steel plate (second electromagnetic steel plate) 61 Conductor Bars 62 End Rings

Claims

1. The shaft and A cylindrical core made of laminated first electromagnetic steel sheets having an opening in which the shaft is arranged, A support ring is positioned on the end face of the core and has an opening in which the shaft is positioned, A conductive bar embedded in a plurality of slots formed at circumferential intervals on the outer periphery of the core, The core comprises end rings connecting the conductor bars at both ends, The support ring is positioned radially inward from the slot of the core, and is arranged to form a stepped portion that protrudes axially outward at the connection point with the end face of the core. The rotor of a rotating machine is characterized in that the end ring presses the support ring toward the end face of the core.

2. The rotor of the rotating machine according to claim 1, characterized in that the support ring is formed by laminating a plurality of second electromagnetic steel sheets.

3. The rotor of the rotating machine according to claim 1, characterized in that the support ring is formed by laminating a second electromagnetic steel sheet of the same shape.

4. The rotor of the rotating machine according to claim 1, characterized in that the first electrical steel sheet and the second electrical steel sheet are formed from the same material.

5. The rotor of the rotating machine according to claim 1, characterized in that the support rings are arranged at both axial ends of the core.

6. A rotating machine comprising a rotor according to any one of claims 1 to 5.

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