JP3654125B2 - Rotating electric machine - Google Patents

Description

【００４９】
表１に示す、本発明のＫ値が０．４〜２．２の回転電機は従来のＡｌ製フレームのものに比べ騒音を小さくすることができた。また、実施例のいずれのＭｇ合金とも比較例１のＡｌ合金に比べ軽量であった。また、実施例５および８以外のＫ値は、いずれも０．７以上２．０以下の間にある。実施例５は他の実施例と比べると表面が荒れており、供用期間中での腐食が懸念されるが、他の実施例に比べ騒音を低減する効果は優れている。一方、実施例８は表面状態が良好で耐食性に優れると考えられるが、騒音を低減する効果は他の実施例と比べると小さい。しかし、上記実施例ではいずれも比較例１と比較して軽量化および低騒音化がなされている。
【００５０】
【発明の効果】
本発明によれば、低騒音かつ軽量な回転電機を提供することができる。
【図面の簡単な説明】
【図１】本発明に関わる誘導電動機の断面図。
【符号の説明】
１…ステータコア、２…電機子巻線、３…ロータコア、４…回転軸、５…ベアリング、６…導電体、７…フレーム、８…ブラケット、９…ボルト、１０…ステータ、１１…ロータ。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a novel lightweight rotating machine with low noise and low noise.
[0002]
[Prior art]
Rotating electric machines are required to be further reduced in noise and reduced in size and weight. The noise of a rotating electrical machine is closely related to the vibration, and generally the vibration of the rotating electrical machine is a cause of noise generation. The causes of noise and vibration of the rotating electrical machine itself are roughly classified into 1) mechanical, 2) electromagnetic, and 3) ventilation.
[0003]
The mechanical components include those due to dynamic unbalance of the rotor, those from the bearings, those due to the sliding portion of the brush, those due to fastening conditions such as screws, and those that occur due to structural reasons. The dynamic unbalance of the rotor has a significant influence particularly at high speed rotation, and can be reduced by adjusting the rotation balance of the rotor more accurately. For example, in the case of a ball bearing, the noise from the bearing is due to friction between the balls and between the balls and the container. Since this noise varies depending on the bearing to be manufactured, a bearing with a lower sound is selected and noise is reduced by using an appropriate grease. When there is a brush, noise caused by sliding of the brush can be suppressed by performing normal work on commutator eccentricity, undercut burrs, brush operation, and the like. In the case of a fastening condition such as a screw, if the fastening condition is insufficient, vibration may be promoted and noise may be increased. Therefore, it is necessary to confirm that the screw is securely tightened without loosening. The structural noise is generated and increased when the vibration generated by the rotation is a frequency that causes resonance in the rotating electrical machine. Therefore, the rotating electrical machine itself must have a structure that does not cause resonance.
[0004]
Electromagnetic noise is sound generated by electromagnetic force acting between the rotor and the stator. The vibrations that generate this sound include radial vibrations that occur when the main magnetic flux passes through the air gap in the radial direction, and the air gap magnetic flux that deviates from the radial direction and receives a pulsating component in the circumferential direction. There are vibrations that occur. In a rotating electrical machine, such an electromagnetic exciting force cannot be avoided, but in order to suppress vibration, it is effective not to match the frequency of the exciting force with the natural frequency of the rotating electrical machine structure.
[0005]
When a fan is attached to the rotor and the rotor is cooled, noise is generated due to collision, friction, or imbalance of the fan itself due to the passage of wind through the rotating electrical machine. In order to suppress the generation of sound, it is better not to smooth the air path, make the exhaust hole sufficiently large, or increase the wind speed too much. It is also effective to attach a silencer to the ventilation hole. Furthermore, an outer envelope that encloses the rotating electric machine may be attached. Although the soundproofing effect is better when the jacket is closer to the seal, care must be taken not to resonate with the rotation frequency.
[0006]
As described above, the causes of noise generation have been investigated and countermeasures have been taken to reduce noise.On the other hand, rotating electrical machines tend to improve the efficiency of electrical characteristics and reduce size and weight. Along with this, vibration and noise are becoming more likely to occur.
[0007]
Vibration generated in the rotating electrical machine mechanism can be suppressed by preventing an increase due to resonance, but the vibration source cannot be easily removed. Therefore, as another method for reducing noise, there is a method for absorbing and attenuating vibration energy. Absorption and damping of vibration energy is called damping, and includes a) system damping, b) structural damping, and c) material damping.
[0008]
System damping uses vibrational force of fluid, frictional force of solid, etc., or uses electromagnetic induction action force to consume vibration energy and suppress vibration. Therefore, it is necessary to provide a special damper system for this purpose outside or inside the rotating electrical machine. In structural damping, a metal material and a polymer material are alternately laminated, and vibration energy is attenuated as energy for deforming the polymer. Material dumping is a concept that attempts to suppress vibrations by utilizing the damping ability of the material itself.
[0009]
In the case of rotating electrical machines, system damping is not practical due to restrictions on dimensions, structure, strength, cost, etc. On the other hand, structural damping is already implemented by resin molding in some rotating electrical machines. It is effective. Therefore, material damping is necessary to achieve further noise reduction, and this method can be said to be a fundamental vibration damping method.
[0010]
Since it is difficult to change the material of the stator and the rotor made of a magnetic material, material damping is substantially performed by selecting a structural material that surrounds them. Until now, steel plate frames, cast frames and aluminum frames have been used. However, steel and aluminum alloys have a low damping capacity, and cannot be appropriate materials from the viewpoint of vibration prevention.
[0011]
So far, several damping materials with improved material damping capacity have been developed. For example, Japanese Patent No. 2846392 discloses a composite material of an aluminum material and a resin material, and Japanese Patent No. 2599614 discloses a Zn—Al alloy. However, these materials have increased in cost, increased in weight, and decreased in strength, and have not yet been put into practical use. On the other hand, JP-A-8-33255 and JP-A-8-47196 disclose a rotating electrical machine in which a magnesium alloy is applied to a housing. In addition, the '96 magnesium manual (Japan Magnesium Association) describes that Mg has a large damping capacity and has a specific gravity of about 2/3 of that of an Al alloy. However, in order to use an Mg alloy for a housing of a rotating electrical machine, the alloy composition must be considered in consideration of corrosion resistance and manufacturability, and further, adjustment of the alloy composition is necessary for providing a noise reduction function.
[0012]
[Problems to be solved by the invention]
An object of the present invention is to provide a lightweight and low-noise rotating electrical machine that can dampen vibration by a material itself and uses a lightweight Mg alloy for a structure.
[0013]
[Means for Solving the Problems]
The present invention is a rotating electrical machine including a stator and a rotor, and a structure that supports and surrounds the stator, and the structure is a lightweight, low-noise rotating electrical machine made of an alloy mainly composed of Mg. The above structure contains two or more of Al 1 to 11%, Zn 0.05 to 6.0%, Mn 0.05 to 1.0% and rare earth metal element (REM) 0.5 to 3.0% by weight. It is made of an alloy mainly composed of Mg, and has a K value obtained by the following K1 of 0.4 to 2.2, preferably 0.7 to 2.0.
[0014]
K1 = 0.1Al + 0.1Zn + 2Mn + 0.1REM
Also, the structure is less Cu0.40%, Ni0.03% or less, an alloy mainly composed of Mg is less than Fe0.01%.
[0015]
In addition, the present invention is a lightweight, low noise rotating electrical machine in which the structure is made of an alloy mainly composed of Mg containing 0.2 to 1.0% of Zr. The above structure further contains any one kind or two kinds or more of Zn 0.05 to 7.0%, REM 0.5 to 5.0%, Ag 3.0% or less, Y 6.0% or less, Mn 0.1% or less. It consists of an alloy mainly containing Mg. The above structure is Zr 0.2-1.0%, Zn 0.05-7.0%, REM 0.5-5.0%, Ag 3.0% or less, Y 6.0% or less, Mn 0.1% or less. It is an alloy mainly composed of Mg, and expressed in terms of weight ratio, the K value obtained by K 2 = Zr + 0.1Zn + 0.1REM + 0.1Ag + 0.1Y + 2Mn is 0.4 to 2.2, preferably 0.7 to 2.0. It is made of an alloy mainly composed of Mg. Further, the above structure is made of an alloy mainly composed of Mg with Cu: 0.10% or less and Ni: 0.01% or less.
[0016]
(1) Mg—Al-based alloy Al is a component that improves the mechanical properties of the Mg alloy. In addition, since the melting point is lowered, the molten metal flow during molding by casting or injection is improved. If the Al content exceeds 11%, a large amount of an intermetallic compound is formed, resulting in brittleness. In addition, the damping capacity decreases as the content increases. Therefore, it is made to contain in 11% or less of range. In particular, it exceeds 3.5% and is preferably 10% or less.
[0017]
Zn improves the mechanical properties like Al. If the Zn content exceeds 6.0%, hot cracks are likely to occur during casting. Moreover, although attenuation capacity is not reduced as much as Al, attenuation capacity becomes small when content increases. Therefore, Zn is set to 6.0% or less. In this system, 0.1 to 1.0% is particularly preferable.
[0018]
Mn improves corrosion resistance. When Mn is present together with Al, it forms an Al—Mn-based compound and incorporates Fe, which is a factor that lowers the corrosion resistance of Mg, thereby reducing the amount of impurity Fe dissolved in Mg and improving the corrosion resistance of the Mg—Al-based alloy. . However, when the amount of Mn exceeds 0.6%, the mechanical properties are deteriorated. Therefore, Mn is set to 0.6% or less. In this system, 0.1 to 0.5% is particularly preferable.
[0019]
Rare earth elements (REM) improve the mechanical properties. The REM contained is not particularly limited, but Dy and Nd are mainly used. When REM exceeds 3.0%, a large amount of Al and a high melting point compound are formed, and the castability is deteriorated. Therefore, it is contained in the range of 3.0% or less. 1 to 2.5% is particularly preferable.
[0020]
Since these additive elements decrease the vibration damping ability as much as any element, there is a case where noise reduction cannot be expected depending on the combination of additive elements even within the above composition range. Therefore, the inventors first derived the following expression that displays a composition that can be expected to reduce noise after considering formability and corrosion resistance.
[0021]
From the point of view of the top Symbol, more preferably K2 value Hasa Raniwa 1.0 to 1.5.
[0022]
The presence of Fe, Ni and Cu significantly increases the corrosion rate and deteriorates the corrosion resistance. If the corrosion resistance is low, a defective film is generated on the outer surface, so that the design property is deteriorated. In addition, the function as a structural body may deteriorate during long-term use, and the reliability of the rotating electrical machine may be impaired. Therefore, it is necessary to reduce the concentration of these elements. Cu is preferably 0.4% or less, and more preferably 0.1% or less. Ni is preferably 0.03% or less, more preferably 0.005% or less. Fe is preferably 0.01% or less, more preferably 0.005% or less. On the other hand, Si contained as an impurity is not particularly limited, but is preferably 0.50% or less. The other impurities are preferably 0.30% or less.
[0023]
Specific examples of the Mg-Al alloy as described above include AZ91D and AM60B (ASTM alloy number).
[0024]
(2) The Mg—Zr-based alloy Zr refines the crystal grains of the Mg alloy and improves the mechanical properties and corrosion resistance without greatly reducing the excellent damping capacity of Mg. However, since the solid solubility limit is small, the effect is saturated even if it exceeds 1.0%. Therefore, Zr is 1.0% or less. In particular, 0.3 to 1.0% is preferable.
[0025]
Zn improves castability and mechanical properties. If the Mg-Zr alloy is added in excess of 7.0%, the mechanical properties may be deteriorated, so the upper limit is set to 7.0%.
[0026]
Ag, Y, and REM all improve mechanical properties. If Ag is contained in an amount exceeding 3.0%, the corrosion resistance is deteriorated, so the upper limit is made 3.0%. Since Y causes castability deterioration, the upper limit is made 6.0%. When the content exceeds 5.0%, REM becomes brittle by forming a large amount of intermetallic compounds. In particular, 1 to 4% is preferable in this system.
[0027]
In addition, the addition of Zn, Ag, Y, REM, and Mn lowers the vibration damping ability, and the addition of Ag, Y, REM leads to high cost of the alloy, so the total amount of these additions is 10% or less. Preferably there is. In particular, Y1-7% and Ag1-5% are preferable.
[0028]
For the Mg—Zr-based alloy, the following formula expressing the composition that can be expected to reduce noise is derived after considering formability and corrosion resistance.
[0030]
In the Mg—Zr alloy, the presence of Ni and Cu significantly increases the corrosion rate and deteriorates the corrosion resistance, as in the Mg—Al alloy. Therefore, it is necessary to reduce the concentration of these elements, and the ranges are preferably 0.10% or less for Cu and 0.01% or less for Ni. Further, other impurities are preferably 0.30% or less.
[0031]
Specific examples of the Mg—Zr alloy as described above include KIA, EZ33A, QE22A, and the like.
[0032]
In addition to the above-described Mg-Al alloys and Mg-Zr alloys, Mg-3 to 5% Al-0.1 to 0.7% Mn-0.3 to 2%, such as AS41A and AS41XB. It is also possible to use a Si-based alloy.
[0033]
The rotating electrical machine structure within the above composition range can solve the problems related to corrosion resistance, surface properties, mechanical properties, moldability, and damping capacity, and can provide a rotating electrical machine that is lightweight and has low noise. The structure can be formed by injection molding with a molten alloy, die casting, sand casting, die casting, or the like. Furthermore, in injection molding, it is possible to manufacture in the presence of solid-liquid.
[0034]
An alloy compact mainly composed of Mg has different surface states depending on the alloy composition, manufacturing method, and the like. It is considered that dirt such as oxides, lubricants, mold release agents, foundry sand, etc. are adhered to the surface of the material as it is molded. Since these deteriorate the soundness of various protective films and cause corrosion, it is necessary to remove them. In general, the Mg compact is subjected to a surface treatment such as a cleaning treatment, a base treatment, and a paint finish. The Mg alloy structure according to the present invention does not necessarily require surface treatment, but it is preferable to carry out the surface treatment from the viewpoint of maintaining corrosion resistance for a long period of time and designability. Here, the cleaning treatment means mechanical methods such as grinding, shot blasting, sand blasting, barrel, wire brushing, belt polishing, etc., kerosene and light oil, gasoline petroleum, benzene, toluene and xylene aromatics, trichlorethylene and par Solvent method using chloroethylene solvent such as chlorine, alkali method using caustic soda, sodium carbonate, etc., pickling method using phosphoric acid, hydrofluoric acid, sulfuric acid, chromic acid, nitric acid, acetic acid, ferric nitrate or glucose. is there. The base treatment is a treatment for chemically forming an anticorrosion film on the surface of the Mg alloy, and an anodic oxidation method such as HAE or Dow 17 is mainly used. The paint finish and the number of paintings are changed according to the usage environment. Also, when there is a strict requirement for corrosion resistance, primer treatment with vinyl or epoxy resin is performed before finishing the coating. In addition, surface treatment such as electroplating and electroless plating is also effective.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
(Example 1)
FIG. 1 is a cross-sectional view of an induction motor using the Mg-based alloy of the present invention.
[0036]
The stator core 1 is configured by laminating electromagnetic steel plates, and an armature winding 2 is wound around the stator core 1. This winding is connected to an external power source, and generates a rotating magnetic field inside the stator 10 by controlling a current waveform and the like. On the inner side of the stator, a rotor core 3 formed by laminating electromagnetic steel plates is installed around a rotating shaft 4 so as to be supported by a bearing 5 and rotated. An Al conductor 6 is inserted into the rotor core. The conductor is short-circuited at both ends by end rings and skewed by one slot. The frame 7 and the bracket 8 are fastened with bolts 9 so as to surround the stator 10 and the rotor 11 and support the bearing, and also serve to protect the rotor and the stator. Although only the induction motor is illustrated here, the present invention can be applied to any rotary electric machine including a stator and a rotor, such as a surface magnet motor, an embedded magnet motor, and a reluctance motor, without being limited to the above motor. In particular, the present invention is effective for a small motor of 10 kW or less. Examples of the structure that is made of an alloy mainly composed of Mg and supports or surrounds the stator and the rotor include a frame and a bracket. These are also called housings, cases, and casings.
[0037]
Rice granular chips made of Mg alloy (MG-1) of Al 9.10%, Mn 0.20%, Zn 0.64%, Si 0.08%, Cu 0.027%, Ni 0.001%, Fe 0.003% by weight. In use, the frame 7 shown in FIG. 1 was formed from the molten metal by injection molding. This frame has a maximum wall thickness of 6 mm and a minimum wall thickness of 2 mm. Although injection molding was performed in a non-oxidizing atmosphere, the molded body was observed to have a pattern that was thought to be due to oxidation, but no defects such as cracks or holes were observed. Further, some burrs were generated along the joints of the molding dies, but they were removed by cutting. The molded body of the frame obtained here was not particularly subjected to surface treatment.
[0038]
The stator 10 is formed by punching out a 0.5 mm thick silicon steel plate to have an outer diameter of 105 mm, an inner diameter of 56 mm, and 24 slots, and applying a three-phase AC armature winding 2 to the stator core 1 laminated to a thickness of 50 mm. Produced. The rotor 11 is formed by punching a silicon steel plate having a thickness of 0.5 mm into a disk having an outer diameter of approximately 55 mm and having a gap for inserting a conductor, and laminating the conductor 6 made of Al on the rotor core 3 laminated to a thickness of 50 mm. It was prepared by inserting. Both ends of the conductor 6 are short-circuited by end rings, and a skew of one slot is applied. The rotor 11 is inserted into the stator after the rotation shaft 4 is passed through and supported by the bearing 5. The bearing 5 is supported by a frame 7 and a bracket 8. The stator 10 is installed inside the frame 7. The induction motor manufactured as described above has four poles, a rated output of 750 W, a rated voltage of 220 V, and a rated current of 6 A, and can be operated at 0 to 120 Hz.
[0039]
(Example 2)
An induction motor was produced in the same manner as in Example 1. However, the frame 7 is obtained by die casting in a non-oxidizing atmosphere by using a molten metal of Mg alloy (MG-2) of Al 5.67%, Mn 0.26%, Zn 0.19% by weight. Molded. The burrs generated during molding were removed by grinding. The dimensions of the frame are the same as in Example 1. The surface properties were the same as in Example 1, and no defects were observed. The molded body of this frame was not subjected to surface treatment.
[0040]
(Example 3)
An induction motor was produced in the same manner as in Example 1. However, the frame 7 is an Mg alloy of 3.72% Al, 0.42% Mn, 0.10% Zn, 2.15% rare earth element (REM), 0.02% Cu, 0.001% Ni, 0.002% Fe by weight. Using (MG-3), it was similarly molded by die casting. The burrs generated during molding were removed by grinding. The dimensions of the frame are the same as in Example 1. The surface properties were the same as in Example 1, and no defects were observed. The molded body of this frame was not subjected to surface treatment.
[0041]
(Example 4)
An induction motor was produced in the same manner as in Example 1. However, the frame 7 uses a molten Mg alloy (MG-4) of Zn 3.70%, Zr 0.72%, Cu 0.07%, Ni 0.005% by weight in a non-oxidizing atmosphere. Molded by sand casting. The burrs generated during molding were removed by grinding. The dimensions of the frame are the same as in Example 1. The surface properties were rougher than the molded bodies of Examples 1 to 3, but no defects such as cracks or holes were observed. The molded body of this frame was subjected to wire brushing to remove sand adhered to the surface.
[0042]
(Example 5)
An induction motor was produced in the same manner as in Example 1. However, the frame 7 was formed by sand casting in the same manner using a Mg alloy (MG-5) with a weight of Zr 0.49%. The burrs generated during molding were removed by grinding. The dimensions of the frame are the same as in Example 1. Although the surface was rough, defects such as cracks and holes were not observed. The molded body of this frame was subjected to wire brushing to remove sand adhered to the surface. However, no further surface treatment was applied.
[0043]
(Example 6)
An induction motor was produced in the same manner as in Example 1. However, the frame 7 uses Mg alloy (MG-6) of Zn 3.9%, Mn 0.10%, REM 1.32%, Zr 0.51%, Cu 0.008%, Ni 0.003% by weight. Similarly, it was formed by sand casting. Here, REM contains a lot of Nd. The burrs generated during molding were removed by grinding. The dimensions of the frame are the same as in Example 1. The surface roughness was less than in Examples 4 and 5, and no defects such as cracks or holes were observed. The molded body of this frame was subjected to wire brushing to remove sand adhered to the surface. However, no further surface treatment was applied.
[0044]
(Example 7)
An induction motor was produced in the same manner as in Example 1. However, the frame 7 is formed by die casting in a non-oxidizing atmosphere using a molten metal of REM 2.11%, Zr 0.49%, Ag 2.37% Mg alloy (MG-7) by weight. did. The burrs generated during molding were removed by grinding. The dimensions of the frame are the same as in Example 1. The surface was not very rough, and no defects such as cracks or holes were observed. The molded body of this frame was used for an induction motor without any further surface treatment.
[0045]
(Example 8)
An induction motor was produced in the same manner as in Example 1. However, the frame 7 uses a Mg alloy (MG-8) of Zn 0.13%, Mn 0.12%, REM 3.56%, Zr 0.89%, and Y 5.27% by weight, and is similarly mold Molded by casting. The burrs generated during molding were removed by grinding. The dimensions of the frame are the same as in Example 1. There was almost no surface roughness, and no defects such as cracks or holes were observed. The molded body of this frame was used for an induction motor without any further surface treatment.
[0046]
(Comparative Example 1)
For comparison, an induction motor similar to that of Example 1 was manufactured using a conventional aluminum frame.
[0047]
Each induction motor was installed on a stainless steel pedestal, and a rotation test at a rotation speed of 3600 rpm was performed in an anechoic chamber. The sound pressure level generated by the rotation of the electric motor was measured at 10 points approximately 1 m from the rotation axis as a base point, and the average value was used as each sound pressure level. Table 1 shows the sound pressure level difference and the K value of each example when the comparative example 1 is used as a reference. The K value is determined by the above-described K1 or K2 based on the component of the alloy element contained.
[0048]
[Table 1]

[0049]
The rotary electric machine having a K value of 0.4 to 2.2 according to the present invention shown in Table 1 was able to reduce noise as compared with the conventional Al frame. Moreover, all the Mg alloys of the examples were lighter than the Al alloy of Comparative Example 1. Moreover, K values other than Example 5 and 8 are all between 0.7 and 2.0. The surface of Example 5 is rough compared to other examples, and there is a concern about corrosion during the service period. However, the effect of reducing noise is superior to other examples. On the other hand, Example 8 is considered to have a good surface condition and excellent corrosion resistance, but the effect of reducing noise is small compared to other Examples. However, in each of the above-described embodiments, the weight and the noise are reduced as compared with Comparative Example 1.
[0050]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, a low noise and lightweight rotary electric machine can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an induction motor according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Stator core, 2 ... Armature winding, 3 ... Rotor core, 4 ... Rotary shaft, 5 ... Bearing, 6 ... Conductor, 7 ... Frame, 8 ... Bracket, 9 ... Bolt, 10 ... Stator, 11 ... Rotor.

Claims (6)

In a rotating electric machine including a stator and a rotor, and a structure that supports and surrounds the stator, the structure is Al 1 to 11%, Zn is 0.05 to 6.0%, and Mn is 0.05 to 1. Mg-based alloy mainly composed of Mg containing 2% or more of 0% and rare earth metal element (REM) 0.5 to 3.0% and having a K value of 0.4 to 2.2 determined by the following K1 A rotating electric machine comprising:
K1 = 0.1Al + 0.1Zn + 2Mn + 0.1REM   2. The rotating electrical machine according to claim 1, wherein the Mg-based alloy contains Cu of 0.40% or less, Ni of 0.03% or less, and Fe of 0.01% or less by weight.   3. The rotating electrical machine according to claim 2, wherein the Mg-based alloy contains Zr 0.2 to 1.0%. In a rotating electrical machine including a stator and a rotor, and a structure that supports and surrounds the stator, the structure is Zr 0.2 to 1.0% by weight, Zn 0.05 to 7.0%, rare earth Elemental (REM) 0.5 to 5.0%, Ag 3.0% or less, Y 6.0% or less, and Mn 0.1% or less, and a K value determined by the following K2 is 0.4. A rotating electrical machine comprising an Mg-based alloy mainly composed of Mg of up to 2.2.
K2 = Zr + 0.1Zn + 0.1REM + 0.1Ag + 0.1Y + 2Mn In a rotating electrical machine including a stator and a rotor, and a structure that supports and surrounds the stator, the structure is Zr 0.2 to 1.0% by weight, Zn 7.0% or less, rare earth element (REM) ) 5.0% or less, Ag3.0% or less, Y6.0% or less, and one or more of Mn 0.1% or less, and the K value determined by the following K2 is 0.4 to 2.2. A rotating electric machine comprising an Mg-based alloy mainly composed of Mg.
K2 = Zr + 0.1Zn + 0.1REM + 0.1Ag + 0.1Y + 2Mn   6. The rotating electrical machine according to claim 4, wherein the Mg-based alloy contains 0.10 wt% or less of Cu and 0.01 wt% or less of Ni.

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