Rotor, electric motor, compressor and refrigeration cycle device

Abstract

The rotor 1 is an annular rotor core 10 extending in the circumferential direction centered on the rotation axis C1, and has a center hole 18 at the radial center centered on the rotation axis C1 and magnet insertion holes 11 radially outward from the center hole 18, and permanent magnets 20 arranged in the magnet insertion holes 11. In the region between the center hole 18 and the magnet insertion holes 11, the rotor core 10 has m (m is an integer of 1 or greater) air gaps (first air gaps) A1 to Am on a first side S1 with respect to a reference plane T including the rotation axis C1, and n (n is an integer of 1 or greater) air gaps (second air gaps) B1 to Bn on a second side S2 with respect to the reference plane T. In a plane perpendicular to the rotation axis T, the total area of ​​the m air gaps A1 to Am is greater than the total area of ​​the n air gaps B1 to Bn. The inner peripheral edge e1 facing the central hole 18 of each void A extends in an arc shape with its center on the side of the rotation axis C1, and the inner peripheral edge f1 facing the central hole 18 of each void B extends in an arc shape with its center on the side of the rotation axis C1.

Description

[Technical Field]

[0001] The present disclosure relates to a rotor, an electric motor, a compressor, and a refrigeration cycle device. [Background technology]

[0002] The rotor has a rotor core with magnet insertion holes and permanent magnets arranged in the magnet insertion holes. For example, Patent Document 1 discloses a rotor having a first air gap formed on a first side of a reference plane including the rotation axis of the rotor core and a second air gap formed on a second side opposite the first side, with the first air gap and the second air gap having different areas, in a plane perpendicular to the axial direction. The first air gap has a generally pentagonal shape, and the second air gap has a circular shape. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2024 / 084657 (see Figure 2) Summary of the Invention [Problem to be solved by the invention]

[0004] Here, heat generated by friction between the shaft and bearings is transferred to the central hole of the rotor core. In conventional configurations, the first gap is roughly pentagonal in shape and the second gap is circular in shape, which causes uneven heat transfer from the central hole to the outer periphery of the rotor core, making the circumferential temperature distribution of the rotor core uneven. As a result, uneven thermal expansion can cause the rotor core to lose its circularity, potentially resulting in vibration or noise.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to make the temperature distribution of a rotor core uniform. [Means for solving the problem]

[0006] The rotor disclosed herein is a rotor for an electric motor used with a refrigerant. The rotor is an annular rotor core extending circumferentially about a rotation axis, the rotor core having a center hole at a radial center about the rotation axis and magnet insertion holes radially outward from the center hole, and permanent magnets arranged in the magnet insertion holes. In a region between the center hole and the magnet insertion holes, the rotor core has m (m is an integer of 1 or greater) first gaps on a first side with respect to a reference plane including the rotation axis, and n (n is an integer of 1 or greater) second gaps on a second side with respect to the reference plane. In a plane perpendicular to the rotation axis, the total area of ​​the m first gaps is greater than the total area of ​​the n second gaps. An edge of each first gap facing the center hole extends in an arc having a center on the rotation axis side. An edge of each second gap facing the center hole extends in an arc having a center on the rotation axis side. [Effects of the Invention]

[0007] In the present disclosure, the total area of ​​the first gaps in the rotor core is larger than the total area of ​​the second gaps, which allows adjustment of the eccentricity of the rotor and allows at least part of the function of a balance weight to be performed. Furthermore, because the edges of the first gaps on the center hole side and the edges of the second gaps on the center hole side both extend in arcs with their centers on the rotation shaft side, heat transfer from the center hole of the rotor core to the outer periphery can be made more uniform in the circumferential direction. This allows for a more uniform temperature distribution in the rotor core. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing an electric motor according to a first embodiment. [Figure 2] 1 is a plan view showing a rotor according to a first embodiment. [Figure 3] (A) is a diagram showing the first gap and the second gap of the rotor of embodiment 1, (B) is a diagram showing another example of the first gap, and (C) is a diagram showing another example of the second gap. [Figure 4]FIG. 1 is a perspective view showing a rotor according to a first embodiment. [Figure 5] 1 is a vertical cross-sectional view showing an electric motor according to a first embodiment together with a compression mechanism. [Figure 6] 1 is a vertical cross-sectional view showing a compressor according to a first embodiment. [Figure 7] 1 is a diagram showing a refrigeration cycle device according to a first embodiment. [Figure 8] FIG. 10 is a diagram illustrating a compressor according to a second embodiment. [Figure 9] FIG. 10 is a cross-sectional view showing a rotor according to a third embodiment. [Figure 10] FIG. 11 is a diagram showing one side of a rotor of a third embodiment with respect to a reference plane. [Figure 11] FIG. 10 is a diagram showing one side of a rotor of a reference example with respect to a reference plane. [Figure 12] 1A and 1B are schematic diagrams for explaining a method for magnetizing a permanent magnet. [Figure 13] 1 is a graph showing the relationship between the angle formed between a permanent magnet and a magnetic pole center line and the magnetization rate of the permanent magnet. [Figure 14] 10 is a graph showing the relationship between the angle formed between a permanent magnet and a magnetic pole center line and the difference in magnetization rate of the permanent magnet. [Figure 15] 10 is a graph showing the change in the effect of a V-shaped arrangement of permanent magnets relative to the area ratio of the air gap in the rotor. [Figure 16] FIG. 10 is a cross-sectional view showing a rotor according to a first modified example. [Figure 17] FIG. 10 is a vertical cross-sectional view showing an electric motor according to a fourth embodiment. [Figure 18] FIG. 11 is a perspective view showing a stator core of an electric motor according to a fifth embodiment. [Figure 19] 10(A) is a plan view showing a part of a stator core according to a fifth embodiment, and FIG. 10(B) is a cross-sectional view showing a cross section of a tooth of the stator core. [Figure 20] FIG. 10 is a vertical cross-sectional view showing an electric motor according to a fifth embodiment. [Figure 21] FIG. 13 is a plan view showing another example of the configuration of the stator core according to the fifth embodiment. [Figure 22]10(A) is a plan view showing a rotor according to a sixth embodiment, and FIG. 10(B) is a plan view showing a rotor according to a second modified example. [Figure 23] FIG. 13 is a plan view showing a rotor according to a seventh embodiment. [Figure 24] FIG. 10 is a plan view showing a rotor of a third modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Embodiment 1 <Configuration of electric motor 3> Fig. 1 is a cross-sectional view showing an electric motor 3 according to a first embodiment. The electric motor 3 includes a shaft 30, a rotor 1 attached to the shaft 30, and an annular stator 5 surrounding the rotor 1. An air gap of 0.3 mm to 1.0 mm is provided between the stator 5 and the rotor 1. The stator 5 is fixed to the inside of a cylindrical sealed container 71 of the compressor 7 (Fig. 6), for example.

[0010] Hereinafter, the center of rotation of the rotor 1 will be referred to as the rotation axis C1. The direction of the rotation axis C1 will be referred to as the "axial direction." The circumferential direction centered on the rotation axis C1 will be referred to as the "circumferential direction," and the radial direction centered on the rotation axis C1 will be referred to as the "radial direction." Furthermore, a cross-sectional view in a plane parallel to the rotation axis C1 will be referred to as a "longitudinal cross-sectional view," and a cross-sectional view in a plane perpendicular to the rotation axis C1 will be referred to as a "transverse cross-sectional view."

[0011] <Configuration of stator 5> The stator 5 has an annular stator core 50 centered on the rotation axis C1, and a coil 55 wound around the stator core 50. The stator core 50 is made up of a plurality of electromagnetic steel plates stacked in the axial direction. The thickness of the electromagnetic steel plates is 0.1 mm to 0.7 mm, for example 0.35 mm.

[0012] The stator core 50 has an annular yoke 51 extending in the circumferential direction and a plurality of teeth 52 extending radially inward from the yoke 51. A slot 53, which is a space for accommodating a coil 55, is formed between adjacent teeth 52.

[0013] Here, nine teeth 52 are provided at equal intervals in the circumferential direction. However, the number of teeth 52 is not limited to nine, and may be two or more. An insulating portion is provided between the stator core 50 and the coil 55. The insulating portion is, for example, the insulating portion 54 shown in FIG. 6 or an insulating film.

[0014] Groove portions 50c are formed on the outer periphery of yoke 51, forming a refrigerant flow path between yoke 51 and sealed container 71. Crimped portions 50a are formed on both circumferential sides of groove portion 50c in yoke 51 for fixing the electromagnetic steel sheets that make up stator core 50 to one another. Recessed portions 50b are formed radially inside groove portion 50c for fixing an insulating portion to stator core 50. The arrangement of crimped portions 50a, recessed portions 50b, and groove portion 50c is arbitrary.

[0015] The coils 55 are made of magnet wire. The magnet wire is a conductor made of copper or aluminum covered with an insulating coating. The coils 55 are wound around the teeth 52 via insulating portions. The coils 55 are wound by concentrated winding, for example.

[0016] The wire diameter and number of turns of the coil 55 are determined based on the characteristics (e.g., rotation speed, torque, etc.) required of the electric motor 3, the voltage specifications, the cross-sectional area of ​​the slot 53, etc. For example, a magnet wire with a wire diameter of 1.0 mm is wound around one tooth 52 about 80 turns.

[0017] Stator core 50 may be formed by combining split cores in the circumferential direction, each split core being divided into individual teeth 52. In this case, stator core 50 is spread out in a strip shape, and coils 55 are wound around each tooth 52 via an insulating portion. Stator core 50 is then bent into a ring shape and both ends are welded together to obtain stator 5.

[0018] <Configuration of Rotor 1> Fig. 2 is a cross-sectional view showing the rotor 1. The rotor 1 shown in Fig. 2 has a rotor core 10 and permanent magnets 20. The rotor core 10 is made up of a plurality of electromagnetic steel plates laminated in the axial direction. The thickness of the electromagnetic steel plates is 0.1 mm to 0.7 mm or less, and is, for example, 0.35 mm.

[0019] The rotor core 10 has a center hole 18 at its radial center. The shape of the center hole 18 is, for example, a circular shape centered on the rotation axis C1. A shaft 30 is fixed to the center hole 18 of the rotor core 10. The fixing method may be, for example, shrink fitting or press fitting.

[0020] The outer periphery 19 of the rotor core 10 extends, for example, circumferentially around the rotation axis C1. A plurality of magnet insertion holes 11 are formed along the outer periphery 19 of the rotor core 10. The plurality of magnet insertion holes 11 are arranged at equal intervals in the circumferential direction. One permanent magnet 20 is inserted into each magnet insertion hole 11. The number of magnet insertion holes 11 is h (h is an integer of 2 or greater), for example, six.

[0021] The permanent magnet 20 is flat and has a width in the circumferential direction and a thickness in the radial direction. The permanent magnet 20 is magnetized in the thickness direction. The permanent magnet 20 is made of, for example, a rare earth magnet. As the rare earth magnet, for example, a neodymium magnet containing neodymium (Nd), iron (Fe), and boron (B) is used.

[0022] The permanent magnet 20 placed in each magnet insertion hole 11 constitutes one magnetic pole. The circumferential center of the magnet insertion hole 11 is the pole center. An inter-pole section is formed between adjacent magnet insertion holes 11. A radial line passing through the pole center is called the magnetic pole center line P. A radial line passing through the inter-pole section is called the inter-pole center line Q.

[0023] Flux barriers 12 are formed as leakage flux suppression holes on both circumferential sides of each magnet insertion hole 11. Thin-walled portions are formed between the flux barriers 12 and the outer periphery 19 of the rotor core 10. The thickness of the thin-walled portions is set to be equal to the thickness of the electromagnetic steel sheets, for example, in order to suppress leakage flux between adjacent magnetic poles.

[0024] Here, the number (h) of magnet insertion holes 11 is six, and the number of permanent magnets 20 is also six. Therefore, the number of poles of the rotor 1 is six. However, the number of poles of the rotor 1 is not limited to six, and may be two or more.

[0025] Also, here, one magnet insertion hole 11 is formed in each magnetic pole and one permanent magnet 20 is placed therein, but two or more permanent magnets 20 may be placed in each magnetic pole. Specifically, two permanent magnets may be placed in one magnet insertion hole formed in one magnetic pole, or two magnet insertion holes may be formed in one magnetic pole and a permanent magnet may be placed in each (see FIG. 9, described later).

[0026] m air gaps A1 to Am and n air gaps B1 to Bn are formed in the region between the center hole 18 of the rotor core 10 and the magnet insertion hole 11. The air gaps A1 to Am are also referred to as first air gaps, and the air gaps B1 to Bn are also referred to as second air gaps.

[0027] Both m and n are integers equal to or greater than 1. In the example shown in Fig. 2, both m and n are 3. In the example shown in Fig. 2, three voids A1, A2, and A3 are arranged counterclockwise in this order, and three voids B1, B2, and B3 are arranged counterclockwise in this order.

[0028] Both m and n are not limited to 3, and may be 1 or greater. Furthermore, m and n do not have to be the same number. When there is no particular need to distinguish between the voids A1 to Am, they will be described as void A. Similarly, when there is no particular need to distinguish between the voids B1 to Bn, they will be described as void B.

[0029] The plane including the rotation axis C1 is referred to as the reference plane T. The reference plane T is set taking into consideration the amount of eccentricity to be applied to the rotor 1. One side of the reference plane T is referred to as the first side S1. The other side of the reference plane T is referred to as the second side S2.

[0030] The m voids A1 to Am are formed on a first side S1 with respect to the reference plane T. The n voids B1 to Bn are formed on a second side S2 with respect to the reference plane T. As an example, m=3 and n=3.

[0031] It can also be said that the gaps A1 to Am are formed within an angle range of 0 to 180 degrees from a reference point R centered on the rotation axis C1. The reference point R is one of two intersections between the central hole 18 of the rotor core 10 and the reference plane T (for example, the intersection on the right side in FIG. 2). Similarly, it can also be said that the gaps B1 to Bn are formed within an angle range of 180 to 360 degrees from the reference point R centered on the rotation axis C1.

[0032] In the example shown in Figure 2, the voids A1 to A3 have the same shape and dimensions. Similarly, the voids B1 to B3 have the same shape and dimensions. However, the shape or dimensions of at least one of the voids A1 to Am may be different from the others. Similarly, the shape or dimensions of at least one of the voids B1 to Bn may be different from the others.

[0033] Fig. 3(A) is a schematic diagram illustrating the shape and arrangement of gaps A and B. As shown in Fig. 3(A), gap A has an inner peripheral edge e1 on the side of center hole 18, an outer peripheral edge e2 on the side of outer periphery 19 (Fig. 2), and side edges e3 on both circumferential sides. Both inner peripheral edge e1 and outer peripheral edge e2 extend in an arc shape with a center on the rotation axis C1 side (preferably, an arc shape with a center on rotation axis C1). Side edge e3 extends in the radial direction.

[0034] Radial ribs 15, which are iron core parts, are formed between adjacent gaps A (i.e., between gaps A1 and A2 and between gaps A2 and A3). The radial ribs 15 extend radially between the side edges e3 of adjacent gaps A. The radial ribs 15 are also referred to as first radial ribs.

[0035] The gap B has an inner peripheral edge f1 on the side of the center hole 18, an outer peripheral edge f2 on the side of the outer periphery 19 (FIG. 2), and side edges f3 on both sides in the circumferential direction. Both the inner peripheral edge f1 and the outer peripheral edge f2 extend in an arc shape with a center on the rotation axis C1 side (preferably, an arc shape with a center on the rotation axis C1). The side edge f3 extends in the radial direction.

[0036] Radial ribs 16, which are iron core parts, are formed between adjacent gaps B (i.e., between gaps B1 and B2 and between gaps B2 and B3). The radial ribs 16 extend radially between the side edges f3 of adjacent gaps B. The radial ribs 16 are also referred to as second radial ribs.

[0037] Between the gaps A and B (i.e., between the gaps A1 and B3, and between the gaps A3 and B1), ribs 17, which are iron core parts, are formed. The ribs 17 extend radially between the side edges e3 and f3 of the adjacent gaps A and B. The ribs 17 are located on the reference plane T. The ribs 17 are also referred to as third radial ribs.

[0038] Gap A has a width W1 in the radial direction. Width W1 is the distance from the inner peripheral edge e1 to the outer peripheral edge e2. Gap B has a width W2 in the radial direction. Width W2 is the distance from the inner peripheral edge f1 to the outer peripheral edge f2. Width W1 of gap A is wider than width W2 of gap B. In other words, W1 > W2 holds.

[0039] Gap A has a length L1 in the circumferential direction. Length L1 is the maximum distance in the circumferential direction between the two side edges e3. Gap B has a length L2 in the circumferential direction. Length L2 is the maximum distance in the circumferential direction between the two side edges f3. Although length L1 of gap A and length L2 of gap B are the same in Figure 3(A), they may be different.

[0040] In the first embodiment, in a plane perpendicular to the rotation axis C1, the area of ​​each gap A is larger than the area of ​​each gap B. Therefore, the total area of ​​gaps A1 to A3 is larger than the total area of ​​gaps B1 to B3. Therefore, in the rotor core 10, the weight of the first side S1 is lighter than the weight of the second side S2. This makes it possible to adjust the eccentricity of the rotor 1.

[0041] The above-mentioned radial rib 15 has a width D1 in the circumferential direction. Width D1 is the shortest circumferential distance between adjacent gaps A. The above-mentioned radial rib 16 has a width D2 in the circumferential direction. Width D2 is the shortest circumferential distance between adjacent gaps B. Although width D1 of radial rib 15 and width D2 of radial rib 16 are the same in FIG. 3(A), they may be different.

[0042] A circumferential rib 13 extending in the circumferential direction is formed between the inner peripheral edge e1 of the gap A and the central hole 18 of the rotor core 10. The circumferential rib 13 is also referred to as a first circumferential rib. It is desirable that the radial width T1 of the circumferential rib 13 be constant from one end to the other in the circumferential direction of the gap A, but it may be constant over a range of at least half the length L1 of the gap A.

[0043] Similarly, a circumferential rib 14 extending in the circumferential direction is formed between the inner peripheral edge f1 of the gap B and the central hole 18 of the rotor core 10. The circumferential rib 14 is also referred to as a second circumferential rib. It is desirable that the radial width T2 of the circumferential rib 14 be constant from one end to the other in the circumferential direction of the gap B, but it is sufficient if the width T2 is constant over a range of at least half the length L2 of the gap B.

[0044] Furthermore, although the radial width T1 of the circumferential rib 13 and the radial width T2 of the circumferential rib 14 are the same in FIG. 3(A), they may be different.

[0045] 3(B) is a diagram showing another example of the gap A. In the example shown in FIG. 3(B), a curved portion e4 is formed between the inner peripheral edge e1 and the side edge e3 of the gap A. In addition, a curved portion e5 is formed between the outer peripheral edge e2 and the side edge e3 of the gap A. In this case, too, the radial width T1 of the circumferential rib 13 only needs to be constant over a range of at least half the length L1 of the gap A.

[0046] 3(C) is a diagram showing another example of the gap B. In the example shown in FIG. 3(C), a curved portion f4 is formed between the inner peripheral edge f1 and the side edge f3 of the gap B. In addition, a curved portion f5 is formed between the outer peripheral edge f2 and the side edge f3 of the gap B. In this case, too, the radial width T2 of the circumferential rib 14 only needs to be constant over a range of at least half the length L2 of the gap B.

[0047] 2 and 3(A), all of the voids A1 to Am are formed on the first side S1, but some of the voids A1 to Am may extend onto the second side S2. Similarly, in FIGS. 2 and 3(A), all of the voids B1 to Bn are formed on the second side S2, but some of the voids B1 to Bn may extend onto the first side S1.

[0048] That is, in a plane perpendicular to the axial direction, it is sufficient that a portion occupying half or more of the total area of ​​the gaps A1 to Am is located on the first side S1 with respect to the reference plane T, and a portion occupying half or more of the total area of ​​the gaps B1 to Bn is located on the second side S2 with respect to the reference plane T. This configuration makes it possible to adjust the amount of eccentricity of the rotor 1.

[0049] 4 is a perspective view showing the rotor 1. A balance weight 31 serving as a first balance weight is attached to a first axial end face 10a of the rotor core 10. A balance weight 32 serving as a second balance weight is attached to a second axial end face 10b of the rotor core 10.

[0050] The balance weights 31 and 32 are metal parts formed by casting or forging. The balance weights 31 and 32 are attached to the end faces 10a and 10b of the rotor core 10, respectively, by fastening members (not shown). The balance weights 31 and 32 are positioned to suppress eccentricity of the rotor 1, thereby offsetting the bias of the centrifugal force of the rotor 1 that occurs during rotation and achieving stable rotation of the rotor 1.

[0051] The balance weight 31 is an annular member centered on the rotation axis C1, and has a weight portion 31a on a first side S1 with respect to a reference plane T and an end plate portion 31b on a second side S2. The weight portion 31a and the end plate portion 31b are semicircular arc-shaped when viewed in the axial direction. The axial length of the weight portion 31a is longer than the axial length of the end plate portion 31b. Therefore, the weight of the weight portion 31a is greater than the weight of the end plate portion 31b.

[0052] The balance weight 32 is an annular member centered on the rotation axis C1, and has a weight portion 32a on a second side S2 with respect to the reference plane T and an end plate portion 32b on a first side S1. The weight portion 32a and the end plate portion 32b are semicircular arc-shaped when viewed in the axial direction. The axial length of the weight portion 32a is longer than the axial length of the end plate portion 32b. Therefore, the weight of the weight portion 32a is greater than the weight of the end plate portion 32b.

[0053] However, the shapes of the weight portions 31a and 32a of the balance weights 31 and 32 are not limited to the example shown in Fig. 4 and can be modified as appropriate. In addition, because the amount of eccentricity of the rotor 1 is adjusted by the gaps A and B of the rotor core 10, it is possible to omit one or both of the balance weights 31 and 32.

[0054] A guide mechanism and fixing means that allow for easy positioning are used to attach the balance weights 31, 32 to the rotor core 10, improving workability in the assembly process and ensuring durability over long periods of operation. Furthermore, by fine-tuning the weight or position of the balance weights 31, 32 according to the usage conditions (including the usage environment) of the rotor 1, optimal balance adjustment of the rotor 1 can be achieved.

[0055] 5 is a longitudinal cross-sectional view showing the rotor 1. Gap A extends in the axial direction from the first end face 10a to the second end face 10b of the rotor core 10. Similarly, gap B extends in the axial direction from the first end face 10a to the second end face 10b of the rotor core 10.

[0056] The balance weights 31 and 32 are preferably attached to the end faces 10a and 10b of the rotor core 10 at positions that do not block the gaps A and B (for example, radially outward of the gaps A and B).

[0057] <Compressor> 6 is a longitudinal cross-sectional view showing a compressor 7 equipped with the electric motor 3 of the first embodiment. The compressor 7 is a rotary compressor here, but may be a scroll compressor. The compressor 7 includes a sealed container 71, a compression mechanism 72 disposed within the sealed container 71, and the electric motor 3 that drives the compression mechanism 72.

[0058] The compression mechanism 72 has a cylinder 72a having a cylinder chamber 72g, a rolling piston 72b fixed to the shaft 30 of the electric motor 3, a vane that divides the interior of the cylinder chamber 72g into a suction side and a compression side, and an upper frame 72c and a lower frame 72d into which the shaft 30 is inserted and which close the axial end faces of the cylinder chamber 72g. An upper discharge muffler 72e and a lower discharge muffler 72f are attached to the upper frame 72c and the lower frame 72d, respectively.

[0059] The sealed container 71 is a cylindrical container. Refrigerating machine oil (not shown) that lubricates the sliding parts of the compression mechanism 72 is stored in the bottom of the sealed container 71. The shaft 30 is rotatably held by an upper frame 72c and a lower frame 72d that serve as bearings.

[0060] The cylinder 72a has a cylinder chamber 72g therein, and the rolling piston 72b rotates eccentrically within the cylinder chamber 72g. The shaft 30 has an eccentric shaft portion, and the rolling piston 72b is fitted onto the eccentric shaft portion.

[0061] The stator 5 of the electric motor 3 is assembled inside the sealed container 71 by a method such as shrink fitting, press fitting, or welding. Electric power is supplied to the coil 55 of the stator 5 from a glass terminal 75 fixed to the sealed container 71. The shaft 30 is fixed to the rotor core 10 as described above.

[0062] An accumulator 73 is attached to the outside of the sealed container 71. Refrigerant gas flows into the accumulator 73 from the refrigerant circuit through a suction pipe 73a. When liquid refrigerant flows in together with the refrigerant gas from the suction pipe 73a, the liquid refrigerant is stored in the accumulator 73, and the refrigerant gas is supplied to the compressor 7.

[0063] A suction pipe 74 is fixed to the sealed container 71, and refrigerant gas is supplied from the accumulator 73 to the cylinder 72a via this suction pipe 74. In addition, a discharge pipe 76 is provided at the top of the sealed container 71 to discharge the refrigerant to the outside.

[0064] The amount of eccentricity of the rotor 1 described in the first embodiment and the like is adjusted in consideration of various factors such as the amount of eccentricity of the rolling piston 72b in the compression mechanism 72 so that the rotation of the rotor 1 is stable.

[0065] A refrigerant containing a substance that has the property of causing a disproportionation reaction is used as the refrigerant for the compressor 7. From the viewpoint of preventing global warming, a refrigerant with a low GWP (global warming potential), for example, a GWP of 1500 or less, is desirable. Below, the types of refrigerants are explained using refrigerant numbers beginning with "R" defined in the international standard ISO817.

[0066] Specifically, it is desirable to use at least one of R1234yf, R1234ze(E), R448A, R449A, R452A, R452B, R454A, R454B, R454C, R463A, R513A, and R513B.

[0067] Of these refrigerants, R1234yf has the chemical formula CF3CF=CH2 (2,3,3,3-tetrafluoropropene) and a GWP of 1. R1234ze(E) has the chemical formula CF3CH=CHF (1,3,3,3-tetrafluoropropene) and a GWP of 1. The other refrigerants are mixed refrigerants.

[0068] Specifically, R448A is a mixture of R32, R125, R1234yf, R134a, and R1234ze(E) in a weight ratio of 26.0:26.0:20.0:21.0:7.0. The chemical formula for R32 is CH2F2 (difluoromethane), the chemical formula for R125 is CHF2CF3 (pentafluoroethane), and the chemical formula for R134a is CH2FCF3 (tetrafluoroethane).

[0069] R449A is a mixture of R32, R125, R1234yf, and R134a in a weight ratio of 24.3:24.7:25.3:25.7.

[0070] R452A is a mixture of R32, R125, and R1234yf in a weight ratio of 11.0:59.0:30.0.

[0071] R452B is a mixture of R32, R125, and R1234yf in a weight ratio of 67.0:7.0:26.0.

[0072] R454A is a mixture of R32 and R1234yf in a weight ratio of 35.0:65.0.

[0073] R454B is a mixture of R32 and R1234yf in a weight ratio of 68.9:31.1.

[0074] R454C is a mixture of R32 and R1234yf in a weight ratio of 21.5:78.5.

[0075] R463A is a mixture of R744, R32, R125, R1234yf, and R134a in a weight ratio of 6.0:36.0:30.0:14.0:14.0. The chemical formula for R744 is CO2 (carbon dioxide).

[0076] R513A is a mixture of R1234yf and R134a in a weight ratio of 56.0:44.0.

[0077] R513B is a mixture of R1234yf and R134a in a weight ratio of 58.5:41.5.

[0078] Use of these refrigerants can meet the demand for preventing global warming while improving the operating capacity of the compressor 7. However, when these refrigerants are used, there is a possibility that a disproportionation reaction will occur due to an increase in the pressure of the refrigerant inside the compressor 7.

[0079] In the compressor 7 of the first embodiment, the pressure rise in the refrigerant is suppressed as will be described later, and therefore the occurrence of disproportionation reactions can be suppressed even when the above-mentioned refrigerants are used.

[0080] <Refrigeration cycle equipment> Next, a refrigeration cycle device 9 having the compressor 7 shown in Fig. 6 will be described. Fig. 7 is a diagram showing the refrigeration cycle device 9. The refrigeration cycle device 9 is, for example, an air conditioner, but is not limited to this and may be, for example, a refrigerator.

[0081] 7 includes a compressor 91, a condenser 92 that condenses a refrigerant, a pressure reducing device 93 that reduces the pressure of the refrigerant, and an evaporator 94 that evaporates the refrigerant. The compressor 91, the condenser 92, and the pressure reducing device 93 are provided in an outdoor unit 9A, and the evaporator 94 is provided in an indoor unit 9B.

[0082] The compressor 91, the condenser 92, the pressure reducing device 93, and the evaporator 94 are connected by a refrigerant pipe 97 to form a refrigerant circuit. The compressor 91 is configured as the compressor 7 shown in FIG. 6. The refrigeration cycle device 9 also includes an outdoor fan 95 facing the condenser 92 and an indoor fan 96 facing the evaporator 94.

[0083] The refrigeration cycle device 9 operates as follows. The compressor 91 compresses the refrigerant it draws in and sends it out as high-temperature, high-pressure refrigerant gas. The condenser 92 exchanges heat between the refrigerant sent out from the compressor 91 and the outdoor air sent by the outdoor blower 95, condenses the refrigerant, and sends it out as liquid refrigerant. The pressure reducing device 93 expands the liquid refrigerant sent out from the condenser 92 and sends it out as low-temperature, low-pressure liquid refrigerant.

[0084] The evaporator 94 exchanges heat between the low-temperature, low-pressure liquid refrigerant sent from the pressure reducing device 93 and the indoor air, evaporating the refrigerant and sending it out as refrigerant gas. The air from which heat has been removed in the evaporator 94 is supplied by an indoor fan 96 into the room, which is the space to be air-conditioned.

[0085] During heating operation, a switching valve (not shown) sends the refrigerant from the compressor 7 to the evaporator 94. In this case, the evaporator 94 functions as a condenser, and the condenser 92 functions as an evaporator.

[0086] <Action: Inhibition of disproportionation reaction> The operation of the first embodiment will now be described. In the electric motor 3, the center of gravity of the rotor 1 may become unbalanced due to imbalance in the center of gravity of the components of the rotor 1 (i.e., the rotor core 10, the permanent magnets 20, etc.) or imbalance in mass distribution due to dimensional tolerances and assembly errors of the components. When the center of gravity of the rotor 1 becomes unbalanced, the rotor 1 may whirl due to an imbalance in the centrifugal force generated during rotation, potentially generating vibration and noise.

[0087] Therefore, by attaching balance weights 31 and 32 with pre-calculated appropriate positions and weights to the rotor core 10, the center of gravity balance of the rotor 1 is corrected, preventing the rotor 1 from whirling and reducing vibration and noise.

[0088] Here, a refrigerant containing a substance that has the property of causing a disproportionation reaction may be used in the compressor 7. When a refrigerant containing a substance that has the property of causing a disproportionation reaction is used, a disproportionation reaction may occur if the pressure of the refrigerant increases, which may cause a breakdown of the compression mechanism 72 of the compressor 7 (particularly the cylinder 72a).

[0089] Furthermore, since the rotor 1 is provided with the balance weights 31 and 32, when the refrigerant flows around the balance weights 31 and 32, the pressure of the refrigerant may increase locally, possibly causing a disproportionation reaction.

[0090] Rotor core 10 has axial through-holes formed therein, such as magnet insertion holes 11, flux barriers 12, and gaps A and B. If these through-holes are partially blocked by balance weights 31 and 32, the refrigerant inlet and outlet narrows, causing the refrigerant pressure to rise according to Bernoulli's principle. Therefore, if the refrigerant contains a substance that has the property of causing a disproportionation reaction, the rise in refrigerant pressure may cause the disproportionation reaction.

[0091] The occurrence of the above-described disproportionation reaction can be suppressed by arranging the balance weights 31, 32 in positions that do not block the through holes of the rotor core 10, or by not providing the balance weights 31, 32 at all. However, depending on the size of the balance weights 31, 32, it may be difficult to arrange them in positions that do not block the through holes of the rotor core 10. Furthermore, due to the need to adjust the center of gravity balance of the rotor 1, it is also difficult to not provide the balance weights 31, 32.

[0092] In contrast, in the first embodiment, the rotor core 10 has gaps A1-Am on the first side S1 of the reference plane T, gaps B1-Bn on the second side S2, and the total area of ​​the gaps A1-Am is larger than the total area of ​​the gaps B1-Bn, making it possible to adjust the center of gravity balance of the rotor core 10. Therefore, it is possible to reduce the size of the balance weights 31 and 32 and place the balance weights in positions that do not block the through holes (including the gaps A and B) of the rotor core 10, or to realize a configuration in which the balance weights 31 and 32 are not placed at all.

[0093] This prevents the refrigerant from increasing in pressure due to the refrigerant flowing around the balance weights 31 and 32, and thus prevents the occurrence of disproportionation reactions.

[0094] <Uniform rotor temperature distribution> On the other hand, when the gaps A1 to Am and the gaps B1 to Bn are provided in the rotor core 10, there is a possibility that the temperature distribution in the circumferential direction of the rotor core 10 will become non-uniform. This point will be explained below.

[0095] In the compressor 7 (FIG. 6), heat is generated due to friction between the shaft 30 and the bearings (upper frame 72c and lower frame 72d) of the compression mechanism 72. The heat of the shaft 30 is transferred to the central hole 18 of the rotor core 10 and moves from the central hole 18 toward the outer periphery 19 within the rotor core 10.

[0096] Here, as shown in Fig. 2 of Patent Document 1, if a substantially pentagonal gap is formed on the first side S1 of rotor core 10 and a circular gap is formed on the second side S2, an imbalance is likely to occur in the heat transfer from center hole 18 to outer periphery 19 of rotor core 10. As a result, a difference in the amount of temperature rise occurs between first side S1 and second side S2, and the temperature distribution in the circumferential direction of rotor core 10 may become uneven.

[0097] 3A, in the first embodiment, the inner peripheral edge e1 of the gap A is arc-shaped with its center on the rotation axis C1 side, and the inner peripheral edge f1 of the gap B is also arc-shaped with its center on the rotation axis C1 side. Therefore, a circumferential rib 13 is formed between the center hole 18 of the rotor core 10 and the gap A, and a circumferential rib 14 is formed between the center hole 18 of the rotor core 10 and the gap B.

[0098] As a result, heat applied to center hole 18 of rotor core 10 flows circumferentially along circumferential ribs 13, 14, and then passes through radial ribs 15, 16 toward outer periphery 19. This reduces the difference in the temperature rise of rotor core 10 between first side S1 and second side S2, making it possible to uniform the temperature distribution in the circumferential direction of rotor core 10.

[0099] By thus uniforming the temperature distribution in the circumferential direction of rotor core 10, vibrations and noise caused by non-uniform thermal expansion can be suppressed, and damage to rotor core 10 and permanent magnets 20 can be prevented.

[0100] Furthermore, even if a rare earth magnet, which is prone to demagnetization at high temperatures, is used as the permanent magnet 20, the uniform temperature distribution in the rotor core 10 suppresses local temperature increases in the permanent magnet 20, thereby suppressing the occurrence of thermal demagnetization.

[0101] In particular, if the inner peripheral edge e1 of gap A is arc-shaped with its center on the rotation axis C1 and the inner peripheral edge f1 of gap B is also arc-shaped with its center on the rotation axis C1, the radial widths T1 and T2 of the circumferential ribs 13 and 14 can be made constant, thereby enhancing the effect of uniforming the circumferential temperature distribution of the rotor core 10.

[0102] Here, the heat applied to the central hole 18 of the rotor core 10 has been described as frictional heat with the frames 72c, 72d (FIG. 6) of the compression mechanism 72, but heat is also applied to expand the inner diameter of the central hole 18 in the shrink-fitting process for fixing the shaft 30 to the rotor core 10. In this case, too, the inner peripheral edges e1, f1 of the gaps A, B have an arc shape with their centers on the rotation axis C1 side, which has the effect of making the temperature distribution in the rotor core 10 uniform.

[0103] 2, 3(A), etc., the radial widths of the gaps A1 to Am are the same, and the radial widths of the gaps B1 to Bn are the same. However, the radial widths of the gaps A1 to Am do not necessarily have to be the same, and the radial widths of the gaps B1 to Bn do not necessarily have to be the same. It is sufficient that the total area of ​​the gaps A1 to Am is larger than the total area of ​​the gaps B1 to Bn.

[0104] 2, 3A, etc., the gaps A1 to Am are equidistant from the rotation axis C1, and the gaps B1 to Bn are equidistant from the rotation axis C1. However, the gaps A1 to Am do not have to be equidistant from the rotation axis C1, and the gaps B1 to Bn do not have to be equidistant from the rotation axis C1.

[0105] <Effects of the embodiment> As described above, the rotor 1 of the first embodiment has a rotor core 10 with magnet insertion holes 11, and permanent magnets 20 arranged in the magnet insertion holes 11. The rotor core 10 has air gaps A1 to Am (m first air gaps) and air gaps B1 to Bn (n second air gaps) in a region between the center hole 18 and the magnet insertion holes 11 in the radial direction. If one side of a reference plane T including the rotation axis C1 is defined as a first side S1 and the other side is defined as a second side S2, then in a plane perpendicular to the rotation axis C1, the air gaps A1 to Am are located on the first side S1, and the air gaps B1 to Bn are located on the second side S2. The inner peripheral edge e1 facing the central hole 18 of the rotor core 10 in gap A extends in an arc shape with its center on the side of the rotation axis C1, and the inner peripheral edge e1 facing the central hole 18 of the rotor core 10 in gap B extends in an arc shape with its center on the side of the rotation axis C1.

[0106] In this way, the inner peripheral edges e1, f1 of the gaps A, B are arc-shaped with their centers on the rotation axis C1 side, so that circumferential ribs 13, 14 are formed between the center hole 18 of the rotor core 10 and the gaps A, B. Therefore, when heat is applied to the center hole 18 of the rotor core 10, the difference in the amount of temperature rise between the first side S1 and the second side S2 can be reduced, and the temperature distribution in the circumferential direction of the rotor core 10 can be made uniform.

[0107] Furthermore, since the rotor core 10 is formed with the gaps A1 to Am and the gaps B1 to Bn, and the total area of ​​the gaps A1 to Am is larger than the total area of ​​the gaps B1 to Bn, it is possible to adjust the eccentricity of the rotor 1. As a result, the balance weights 31 and 32 can be made smaller or eliminated.

[0108] Furthermore, in the first embodiment, a refrigerant containing a substance that has the property of causing a disproportionation reaction is used. Specifically, the refrigerant used includes at least one of R1234yf, R1234ze(E), R448A, R449A, R452A, R452B, R454A, R454B, R454C, R463A, R513A, and R513B.

[0109] By reducing the size of the balance weights 31, 32 attached to the rotor core 10 or eliminating them as described above, it is possible to suppress the pressure increase that occurs when the refrigerant passes through the balance weights 31, 32, and to suppress the occurrence of disproportionation reactions.

[0110] Embodiment 2 8 is a cross-sectional view showing a compressor 8 according to the second embodiment. The compressor 8 is a scroll compressor here, but may also be a rotary compressor.

[0111] The compressor 8 includes a sealed container 81, a compression mechanism 82 arranged within the sealed container 81, an electric motor 3 that drives the compression mechanism 82, a shaft 30 that connects the compression mechanism 82 and the electric motor 3, and a subframe 83 that supports the lower end of the shaft 30.

[0112] The compression mechanism 82 includes a fixed scroll 82a having a spiral portion, a swinging scroll 82b having a spiral portion that forms a compression chamber between the fixed scroll 82a and the spiral portion of the fixed scroll 82a, a compliance frame 82c that holds the upper end of the shaft 30, and a guide frame 82d that is fixed to the sealed container 81 and holds the compliance frame 82c.

[0113] A suction pipe 84 penetrating the sealed container 81 is press-fitted into the fixed scroll 82a. The sealed container 81 is also provided with a discharge pipe 86 that discharges high-pressure refrigerant gas from the fixed scroll 82a to the outside. The discharge pipe 86 communicates with an opening (not shown) provided between the compression mechanism 82 of the sealed container 81 and the electric motor 3.

[0114] The electric motor 3 is fixed to the sealed container 81 by fitting the stator 5 into the sealed container 81. The configuration of the electric motor 3 is as described in embodiment 1. A glass terminal 85 that supplies power to the electric motor 3 is fixed to the sealed container 81 by welding.

[0115] When the electric motor 3 rotates, the rotation is transmitted to the orbiting scroll 82b, causing the orbiting scroll 82b to oscillate. When the orbiting scroll 82b oscillates, the volume of the compression chamber formed by the spiral portion of the orbiting scroll 82b and the spiral portion of the fixed scroll 82a changes. Refrigerant gas is drawn in through the suction pipe 84, compressed, and discharged from the discharge pipe 86.

[0116] In the second embodiment, a refrigerant with a low GWP and a low operating pressure is used. In the following, the types of refrigerants will be explained using refrigerant numbers beginning with "R" as defined in the international standard ISO817.

[0117] (1) First, R290 can be used as a single refrigerant. Alternatively, a mixed refrigerant containing two or more refrigerants including R290 can be used. R290 is propane. R290 belongs to the HC refrigerant family.

[0118] (2) Instead of R290, R1234yf, R1234ze(E), or R1132(E) may be used as a single medium. These belong to the HFO refrigerant family. R1234yf and R1234ze(E) are as described in the first embodiment. R1132(E) is trans-1,2-difluoroethylene. A mixed refrigerant containing at least one of R1234yf, R1234ze(E), and R1132(E) and another refrigerant may also be used.

[0119] (3) It is also possible to use a mixed refrigerant selected from R444A, R444B, R445A, R446A, R447A, R447B, R452B, R454A, R454B, R454C, R455A, R457A, R459A, and R459B, or a mixed refrigerant containing at least one of these.

[0120] Of these, R444A is a mixture of R32, R1234ze(E), and R152a in a weight ratio of 12.0:83.0:5.0.

[0121] R444B is a mixture of R32, R1234ze(E), and R152a in a weight ratio of 41.5:48.5:10.0.

[0122] R445A is a mixture of R1234ze(E), R134a, and CO2 in a weight ratio of 85.0:9.0:6.0.

[0123] R446A is a mixture of R32, R1234ze(E), and R600a in a weight ratio of 68.0:29.0:3.0.

[0124] R447A is a mixture of R32, R1234ze(E), and R125 in a weight ratio of 68.0:28.5:3.5.

[0125] R447B is a mixture of R32, R1234ze(E), and R125 in a weight ratio of 68.0:24.0:8.0.

[0126] R452B, R454A, R454B and R454C are as described in the first embodiment.

[0127] R455A is a mixture of R32, R1234yf, and CO2 in a weight ratio of 21.5:75.5:3.0.

[0128] R457A is a mixture of R32, R1234yf, and R152a in a weight ratio of 18.0:70.0:12.0.

[0129] R459A is a mixture of R32, R1234yf, and R1234Ze(E) in a weight ratio of 68.0:26.0:6.0.

[0130] R459B is a mixture of R32, R1234yf, and R1234Ze(E) in a weight ratio of 21.0:69.0:10.0.

[0131] Of the refrigerants listed here, R1234yf, R1234ze(E), R452B, R454A, R454B, and R454C contain substances that have the property of causing a disproportionation reaction, and are also used in the first embodiment.

[0132] The refrigerants listed above (1) to (3) have lower operating pressures than the R32 single refrigerant used in general compressors. The operating pressure of the refrigerant is the same as the saturation pressure of the refrigerant. When such refrigerants with low operating pressures are used, the electric motor 3 is driven with low torque.

[0133] Therefore, in order to obtain the same motor output as when using a single refrigerant, R32, it is necessary to increase the drive frequency of the compressor 8 or increase the compression volume (also called stroke volume) of the compression mechanism 82. The drive frequency of the compressor 8 corresponds to the rotation speed of the electric motor 3.

[0134] In both cases where the drive frequency of the compressor 8 is increased and where the compression volume of the compression mechanism 82 is increased, the imbalance of centrifugal force increases during rotation of the shaft 30 having the eccentric portion 30a for oscillating the oscillating scroll 82b, thereby increasing the whirling of the shaft 30. In order to suppress the whirling of the shaft 30, it is necessary to increase the size of the balance weights 31 and 32 attached to the rotor 1.

[0135] In contrast, in the electric motor 3 of the compressor 8, as described in the first embodiment, the rotor core 10 has gaps A and B, which makes it possible to adjust the eccentricity of the rotor 1. By adjusting the eccentricity of the rotor 1 using the gaps A and B of the rotor core 10, it is possible to suppress whirling of the shaft 30 without increasing the size of the balance weights 31 and 32.

[0136] As described above, in the second embodiment, the refrigerant is (1) R290 or a mixture of two or more refrigerants including R290 (2) R1234yf, R1234ze(E), or R1132(E), or a mixture of at least one of these with other refrigerants (3) A refrigerant mixture of any of R444A, R444B, R454A, R446A, R447A, R447B, R452B, R454A, R454B, R454C, R455A, R457A, R459A, and R459B, or a refrigerant mixture containing at least one of these. Since these refrigerants have low operating pressures, it is necessary to increase the drive frequency of the compressor 8 or to increase the compression volume of the compression mechanism 82. However, because the rotor 1 of the electric motor 3 has the gaps A and B described above, it is possible to suppress whirling of the shaft 30 without increasing the size of the balance weights 31 and 32.

[0137] Embodiment 3 9 is a cross-sectional view showing a rotor 1A of embodiment 3. The rotor 1A of embodiment 3 differs from the rotor 1 of embodiment 1 in that it has two permanent magnets 21a, 21b per magnetic pole.

[0138] As shown in Fig. 9, the rotor core 10 of the rotor 1A has two magnet insertion holes 11a, 11b per magnetic pole. The magnet insertion holes 11a, 11b are formed on both sides of the magnetic pole center line P. The magnet insertion holes 11a, 11b are formed symmetrically with respect to the magnetic pole center line P. Both magnet insertion holes 11a, 11b are inclined so that they are displaced radially inward as they approach the magnetic pole center line P.

[0139] A bridge portion 11c extending in the radial direction is formed between the magnet insertion holes 11a and 11b. That is, the magnet insertion holes 11a and 11b are separated from each other by the bridge portion 11c. The bridge portion 11c is located on the magnetic pole center line P.

[0140] A permanent magnet 21a is placed in the magnet insertion hole 11a, and a permanent magnet 21b is placed in the magnet insertion hole 11b. That is, the permanent magnets 21a and 21b are arranged in a V-shape at each magnetic pole. Both the permanent magnets 21a and 21b are configured in the same manner as the permanent magnet 20 (FIG. 2) described in the first embodiment.

[0141] Flux barriers 12 are formed on the inter-pole side of magnet insertion hole 11a and on the inter-pole side of magnet insertion hole 11b. Similar to the flux barrier 12 (FIG. 2) described in the first embodiment, flux barriers 12 have the effect of suppressing magnetic flux leakage between adjacent magnetic poles.

[0142] m air gaps A1 to Am and n air gaps B1 to Bn are formed in the region between the center hole 18 of the rotor core 10 and the magnet insertion holes 11. The shapes, arrangements, and functions of the air gaps A and B are as described in the first embodiment.

[0143] 10 is a plan view showing one side of the rotor 1A with respect to the reference plane T (FIG. 9). As shown in FIG. 10, the permanent magnets 21a and 21b are arranged symmetrically with respect to the magnetic pole center line P. The permanent magnets 21a and 21b are collectively referred to as permanent magnets 21. The angle formed between the magnetic pole surface 211 on the outer periphery of the permanent magnet 21 and the magnetic pole center line P is defined as angle β (<90 degrees).

[0144] 11 is a diagram showing one side of the rotor 1K of the reference example with respect to the reference plane T (FIG. 9). Like the rotor 1 of the first embodiment (FIG. 2), the rotor 1K of the reference example has one magnet insertion hole 11 and one permanent magnet 20 for each magnetic pole. The angle β between the magnetic pole face 201 on the outer periphery of the permanent magnet 20 and the magnetic pole center line P is 90 degrees.

[0145] 12(A) and (B) are schematic diagrams for explaining a method for magnetizing the permanent magnet 20. The permanent magnet 20 can be magnetized using a dedicated magnetizing yoke or by incorporating it into the stator 5 (built-in magnetization), but here we will explain built-in magnetization.

[0146] A radial line passing through the circumferential center of the teeth 52 of the stator 5 is referred to as a teeth center line Tc. The permanent magnets 20 are magnetized by changing the relative rotational position of the rotor 1K with respect to the stator 5 in two stages as shown in Figures 12(A) and (B).

[0147] Specifically, as shown in FIG. 12(A), the rotor 1K is rotated so that the magnetic pole center line P forms an angle α with respect to the tooth center line Tc in a first direction, and a magnetizing current is passed through the coil 55. Next, as shown in FIG. 12(B), the rotor 1K is rotated so that the magnetic pole center line P forms an angle α with respect to the tooth center line Tc in a second direction, and a magnetizing current is passed through the coil 55. This magnetizing method is called double magnetization. The magnetomotive force generated by the magnetizing current is, for example, 53 kAT.

[0148] 12(A) and (B) show the magnetization method of the permanent magnets 20 of the rotor 1K of the reference example, but the magnetization direction of the permanent magnets 20 of the rotor 1A of embodiment 3 (FIGS. 10(A) and (B)) is also the same.

[0149] When magnetizing the permanent magnets 20, the magnetizing magnetic flux supplied from the stator 5 flows so as to avoid the gaps A and B (see FIGS. 12A and 12B). As described in the first embodiment, the total area of ​​the gaps A1 to Am on the first side S1 of the rotor 1A is larger than the total area of ​​the gaps B1 to Bn on the second side S2. Therefore, the amount of magnetizing magnetic flux flowing into the permanent magnets 20 arranged on the first side S1 of the rotor 1A is smaller than that of the permanent magnets 20 arranged on the second side S2.

[0150] As a result, the magnetization rate Ma [%] of the permanent magnet 20 arranged on the first side S1 is lower than the magnetization rate Mb [%] of the permanent magnet 20 arranged on the second side S2. Therefore, in the third embodiment, the magnetization rate is improved by arranging two permanent magnets 21a, 21b in a V-shape at each magnetic pole.

[0151] 13 is a graph showing the relationship between the angle β and the magnetization rate of the permanent magnets 21 in the rotor 1A of the third embodiment. The horizontal axis represents the angle β, and the vertical axis represents the magnetization rate.

[0152] The magnetization rate [%] is the degree of magnetization where complete magnetization is 100% and is measured based on the induced voltage generated when a specified current (e.g., 1 million A) is passed through the coil 55. The magnetization rate Ma [%] is the magnetization rate of the permanent magnet 20 arranged on the first side S1. The magnetization rate Mb [%] is the magnetization rate of the permanent magnet 20 arranged on the second side S2.

[0153] 13 also shows the magnetization rates ma and mb [%] of the permanent magnets 20 of the rotor 1K of the reference example. In the rotor 1K of the reference example, β=90 [degrees], but for comparison with the third embodiment, the magnetization rates ma and mb [%] are both shown as straight lines.

[0154] As shown in FIG. 13, when β is equal to or greater than 70 degrees and equal to or less than 88 degrees, the magnetization rates Ma and Mb of permanent magnet 21 of embodiment 3 are equal to or greater than the magnetization rates ma and mb of permanent magnet 20 of the reference example (i.e., Ma≧ma, Mb≧mb).

[0155] 14 is a graph showing the relationship between the angle β and the magnetization rate difference (Ma-Mb) of the permanent magnet 21 in the rotor 1A according to the embodiment 3. The magnetization rate difference Ma-Mb is the difference between the magnetization rates Ma and Mb of the permanent magnet 21 shown in FIG.

[0156] 14 also shows the magnetization rate difference (ma-mb) of the permanent magnet 20 in the rotor 1K of the reference example. In the reference example, β=90 [degrees], but for comparison with the third embodiment, the magnetization rate difference ma-mb [%] is shown as a straight line.

[0157] As shown in FIG. 14, if the angle β is 88 degrees or less, the magnetization rate difference (Ma-Mb) of the permanent magnet 21 is equal to or less than the magnetization rate difference (ma-mb) of the permanent magnet 20 in the rotor 1K of the reference example.

[0158] These results show that by setting the angle β to be greater than or equal to 70 degrees and less than or equal to 88 degrees (i.e., 70 degrees≦β≦88 degrees), the V-shaped arrangement of permanent magnets 21a, 21b can be used to improve the magnetization rate.

[0159] Here, the results of an analysis conducted to determine whether the above-mentioned effects can be obtained even when the area ratio of the gaps A and B in the rotor 1A is changed will be described.

[0160] Fig. 15 is a graph showing the results of an analysis of how the angle β when Ma = ma (or Mb = mb), as shown by symbols P1 to P4 in Fig. 13, changes with respect to the area ratio of the air gap A (B) in the rotor 1A. The area ratio of the air gap A (B) is the ratio of the total area of ​​the air gap A (B) to the area S perpendicular to the axial direction of the rotor 1A. Note that while Fig. 10 shows a range of 180 degrees centered on the rotation axis C1 of the rotor 1A, the area S is the area of ​​a range of 360 degrees of the rotor 1A.

[0161] As shown in FIG. 15, if the area ratio of the gap A (B) in the rotor 1A is 20% or less, the effect of improving the magnetization rate by arranging the permanent magnets 21a, 21b in a V-shape can be obtained when the angle β is in the range of 70 degrees to 88 degrees.

[0162] In contrast, if the area ratio of the gap A (B) in the rotor 1A exceeds 20%, as shown in the top plot of the curve on the right side in FIG. 15, the effect of improving the magnetization rate by arranging the permanent magnets 21a, 21b in a V-shape may not be obtained within the angle β range of 70 degrees to 88 degrees.

[0163] As described above, in the third embodiment, by arranging two permanent magnets 21a, 21b in a V-shape for each magnetic pole on the rotor 1A, it is possible to suppress a decrease in the magnetization rate of the permanent magnet 21 caused by forming the gaps A, B in the rotor core 10, and improve the efficiency of the electric motor.

[0164] In particular, if the areas Sa and Sb of the gaps A and B and the area S of the rotor 1A satisfy Sa / S≦20% and Sb / S≦20%, and the angle β between the radially outer magnetic pole face 211 of each permanent magnet 21 and the magnetic pole center line P is 70 degrees or more and 88 degrees or less (i.e., 70 degrees≦β≦88 degrees), the decrease in the magnetization rate of the permanent magnet 21 can be effectively suppressed, and the motor efficiency can be further improved.

[0165] Variation 1. Fig. 16 is a cross-sectional view showing rotor 1B of modified example 1. Rotor 1B of modified example 1 shown in Fig. 16 differs from rotor 1A of embodiment 3 in that the number of gaps A and B is four and holes 61 to 66 are formed in rotor core 10.

[0166] In rotor 1B of modified example 1, similar to rotor 1A of embodiment 3, magnet insertion holes 11a and 11b are formed for each magnetic pole in rotor core 10, and permanent magnets 21a and 21b are disposed in the magnet insertion holes, respectively.

[0167] The rotor 1B of the first modification has four air gaps A1 to A4 on a first side S1 with respect to the reference plane T, and four air gaps B1 to B4 on a second side S2. That is, in the rotor 1B of the first modification, m=4 and n=4. The total area of ​​the air gaps A1 to A4 is larger than the total area of ​​the air gaps B1 to B4. The inner peripheral edge e1 of the air gaps A1 to A4 is arc-shaped with its center on the rotation axis C1 side, and the inner peripheral edge f1 of the air gaps B1 to B4 is arc-shaped with its center on the rotation axis C1 side.

[0168] In the rotor core 10 of the rotor 1B, a hole 61 is formed radially outward from the radial rib 15 between the gaps A1 and A2. A hole 62 is formed radially outward from the radial rib 15 between the gaps A3 and A4. The holes 61 and 62 have a circular shape in a plane perpendicular to the axial direction.

[0169] In addition, in the rotor core 10 of the rotor 1B, a hole 63 is formed radially outward from the radial rib 16 between the gaps B1 and B2. A hole 64 is formed radially outward from the radial rib 16 between the gaps B3 and B4. The holes 63 and 64 have a circular shape in a plane perpendicular to the axial direction.

[0170] Furthermore, holes 65 and 66 are formed radially outward from the gaps B1 and B4, respectively. The hole 65 is located on a magnetic pole center line P that passes between the permanent magnets 21a and 21b radially outward from the gap B1. The hole 66 is located on a magnetic pole center line P that passes between the permanent magnets 21a and 21b radially outward from the gap B4. The holes 65 and 66 have, for example, a circular shape in a plane perpendicular to the axial direction. The area of ​​each of the holes 65 and 66 is smaller than the area of ​​each of the holes 61 to 64.

[0171] At each magnetic pole, a crimped portion 67 is formed on the radially outer side of the bridge portion 11c between the magnet insertion holes 11a and 11b. Also, a crimped portion 68 is formed on the radially inner side of each inter-pole portion.

[0172] In rotor 1B of modified example 1, the total area of ​​gaps A1 to A4 is larger than the total area of ​​gaps B1 to B4, and the inner peripheral edges e1 and f1 of each gap A and B are arc-shaped with their centers on the rotation axis C1 side, so that, similar to rotor 1 of embodiment 1, it is possible to obtain the effects of reducing the weight of balance weights 31 and 32 (FIG. 5) and uniforming the temperature distribution of rotor 1B. Furthermore, by setting angle β as described in embodiment 2, it is possible to suppress a decrease in the magnetization rate of permanent magnets 21a and 21b.

[0173] Embodiment 4 Fig. 17 is a cross-sectional view showing an electric motor 3C according to embodiment 4. As shown in Fig. 17, electric motor 3C according to embodiment 4 differs from electric motor 3 according to embodiment 1 in that the thickness Tr of electromagnetic steel sheets 10S forming rotor core 10 and the thickness Ts of electromagnetic steel sheets 50S forming stator core 50 are different.

[0174] Generally, the iron loss generated in the stator 5C during operation of the electric motor 3C is greater than the iron loss generated in the rotor 1C. When the rotor 1C rotates, the relative position of the stator 5C with respect to the permanent magnet 20 changes, causing a large change in the magnetic flux flowing through the stator 5C, whereas the relative position of the rotor 1C with respect to the permanent magnet 20 remains constant, so there is little change in the magnetic flux flowing through the rotor 1C. This results in the above-mentioned iron loss relationship.

[0175] Therefore, in order to reduce the material cost of the electric motor 3C without reducing the efficiency of the electric motor, it is desirable to reduce the cost of the electromagnetic steel sheets 10S of the rotor core 10 rather than the cost of the electromagnetic steel sheets 50S of the stator core 50.

[0176] Therefore, in this fourth embodiment, the thickness Tr of the electromagnetic steel sheets 10S of the rotor core 10 is set to be equal to or greater than the thickness Ts of the electromagnetic steel sheets 50S of the stator core 50 (i.e., Tr≧Ts is satisfied). By increasing the thickness of the electromagnetic steel sheets 10S of the rotor core 10, the processing costs of the electromagnetic steel sheets 10S can be reduced, thereby reducing the material costs of the electric motor 3C.

[0177] As described above, the iron loss generated in the rotor 1C is smaller than the iron loss generated in the stator 5C, but if the iron loss in the rotor 1C increases by increasing the plate thickness Tr, the temperature of the rotor 1C may rise, causing high-temperature demagnetization of the permanent magnets 20. In order to suppress high-temperature demagnetization of the permanent magnets 20, it is common to improve the coercive force of the permanent magnets 20, but in this case the component cost of the permanent magnets 20 increases.

[0178] In rotor 1C of embodiment 4, as described in embodiment 1, gaps A and B are formed in rotor core 10, and the refrigerant flows through gaps A and B, resulting in a large contact area between the refrigerant and rotor core 10. By passing a refrigerant with a lower temperature through the interior of rotor core 10, it is possible to suppress a temperature rise in rotor core 10.

[0179] In addition to the sheet thicknesses Tr and Ts, the electromagnetic steel sheets 10S of the rotor core 10 and the electromagnetic steel sheets 50S of the stator core 50 may also have different characteristic values. One of the characteristics of an electromagnetic steel sheet is iron loss measured by the Epstein test (JIS_C2550-1).

[0180] For example, when measuring the iron loss (W15 / 50) when a frequency of 50 [Hz] and a maximum magnetic flux density of 1.5 [T] are applied in an Epstein test, it is desirable that the iron loss Wr per unit weight of the electromagnetic steel sheet 10S of the rotor core 10 be equal to or greater than the iron loss Ws per unit weight of the electromagnetic steel sheet 50S of the stator core 50.

[0181] The iron loss value of the electromagnetic steel sheet can be adjusted, for example, by the silicon content contained in the electromagnetic steel sheet. The higher the silicon content, the lower the iron loss value, and the lower the silicon content, the higher the iron loss value. By reducing the silicon content of the electromagnetic steel sheet 10S of the rotor core 10, material costs can be reduced.

[0182] The characteristics of the electromagnetic steel sheets are not limited to iron loss measured by the Epstein test, but may also be iron loss measured by, for example, a single sheet magnetic property test. In other words, it is sufficient if the characteristics are measured by a common method for the electromagnetic steel sheets 10S of the rotor core 10 and the electromagnetic steel sheets 50S of the stator core 50.

[0183] As described above, in the fourth embodiment, the thickness Tr of the electromagnetic steel sheets 10S (i.e., the first electromagnetic steel sheets) of the rotor core 10 is equal to or greater than the thickness Ts of the electromagnetic steel sheets 50S (i.e., the second electromagnetic steel sheets) of the stator core 50, so that the material costs of the electric motor 3C can be reduced while suppressing an increase in iron loss during operation of the electric motor 3C. Furthermore, because the rotor core 10 is provided with the gaps A and B, the refrigerant flowing through the gaps A and B can suppress a temperature rise in the rotor core 10, thereby suppressing thermal demagnetization of the permanent magnets 20.

[0184] Furthermore, the iron loss Wr per unit weight of the electromagnetic steel sheet 10S of the rotor core 10 and the iron loss Ws per unit weight of the electromagnetic steel sheet 50S of the stator core 50, as measured in the Epstein test, satisfy Wr≧Ws, thereby further reducing the material cost of the electric motor 3C.

[0185] The electric motor 3C may be used with the refrigerant described in embodiment 1 or 2. Furthermore, the permanent magnets 21a and 21b described in embodiment 3 may be provided on the magnetic poles of the rotor 1C.

[0186] Embodiment 5. Fig. 18 is a perspective view showing a stator core 50 of a stator 5D (Fig. 20) of an electric motor 3D according to embodiment 5. The electric motor 3D according to embodiment 5 differs from the electric motor 3 according to embodiment 1 in that a step portion 52b is provided at an axial end of the stator core 50.

[0187] 18, the teeth 52 have extending portions 521 extending radially inward from the yoke 51, and tip portions 522 formed at the tips of the extending portions 521. The tip portions 522 have rotor-facing surfaces 52c facing the rotor 1D (FIG. 20).

[0188] Fig. 19(A) is a plan view showing a portion including one tooth 52 of stator core 50. Fig. 19(B) is a cross-sectional view taken along a plane perpendicular to the extending direction of tooth 52 (more specifically, extending portion 521).

[0189] 19(A) and 19(B), the extending portions 521 of the teeth 52 have side surfaces 52a facing the slots 53. Steps 52b recessed from the side surfaces 52a are formed at the axial ends (here, both ends) of the extending portions 521 of the teeth 52. If the circumferential width of the extending portions 521 of the teeth 52 (the distance between the two side surfaces 52a) is H1 and the circumferential width of the portions of the teeth 52 where the step portions 52b are provided is H2, then H1 > H2.

[0190] 19(B), the stator core 50 is divided in the axial direction into a first region 56 where the teeth 52 have step portions 52b and a second region 57 where the teeth 52 do not have step portions 52b. The first region 56 includes the axial center portion of the stator core 50, and the second region 57 includes the axial end portion of the stator core 50.

[0191] 20 is a cross-sectional view showing an electric motor 3D according to a fifth embodiment. The electric motor 3D has a rotor 1D and a stator 5D. In the fifth embodiment, the axial length of the rotor core 10 of the rotor 1D is longer than the axial length of the stator core 50 of the stator 5D, and the rotor core 10 protrudes (i.e., overhangs) from the stator core 50 in the axial direction.

[0192] Stator 5D is configured similarly to stator 5 of embodiment 1 (FIG. 1), except that teeth 52 have stepped portions 52b (FIGS. 19A and 19B). Second regions 57 of stator 5D (i.e., regions where teeth 52 have stepped portions 52b) face the axial ends of rotor 1D.

[0193] Magnetic flux from the permanent magnets 20 of the rotor 1D flows into the teeth 52 of the stator 5D. The magnetic flux that has flowed into the teeth 52 flows radially outward within the teeth 52 (FIGS. 19A and 19B) and into the yoke 51. The magnetic flux from the rotor 1D tends to concentrate at the axial ends of the stator core 50 (more specifically, the axial ends of the teeth 52).

[0194] When magnetic flux concentrates at the axial end of stator core 50, a magnetic attractive force acting between rotor core 10 and the axial end of stator core 50 increases. In rotor 1D, whirling is suppressed by balance weights 31 and 32 described in embodiment 1, but if shaft 30 tilts for some reason, the magnetic attractive force between rotor core 10 and the axial end of stator core 50 may increase the tilt of shaft 30.

[0195] In contrast, in the fifth embodiment, stepped portions 52b (FIGS. 19A and 19B) are formed at the axial ends of the teeth 52, thereby narrowing the magnetic path at the axial ends of the teeth 52. As a result, the magnetic flux density becomes high at the axial ends of the teeth 52, causing magnetic saturation.

[0196] This magnetic saturation reduces the magnetic flux flowing through the axial ends of the teeth 52. As a result, the magnetic attraction force between the rotor core 10 and the axial ends of the stator core 50 is weakened, and tilt of the shaft 30 can be suppressed.

[0197] 20, magnetic flux tends to concentrate at the axial ends of teeth 52. Therefore, providing stepped portions 52b at the axial ends of teeth 52 more significantly suppresses tilt of shaft 30.

[0198] In the example shown in Figure 19(B), step portions 52b are provided at both axial ends of the teeth 52, but if step portions 52b are provided at at least one axial end of the teeth 52, magnetic saturation can be generated at that end, thereby achieving the effect of suppressing tilt of the shaft 30.

[0199] In addition, in the example shown in Figure 20, the rotor core 10 protrudes from the stator core 50 on both sides in the axial direction, but it may protrude from only one side in the axial direction, or the rotor core 10 may not protrude from the stator core 50 in the axial direction (see Figure 2).

[0200] While an example in which step portions 52b are provided on teeth 52 has been described above, step portions 51b facing slots 53 may be provided at the axial ends of yoke 51 as shown in Fig. 21. Step portions 51b are portions that are recessed radially outward from inner circumferential surface 51a of yoke 51. That is, in the fifth embodiment, it is sufficient that the area of ​​slots 53 in a plane perpendicular to the axial direction is larger at the axial ends than at the axial center of stator core 50.

[0201] As described above, in embodiment 5, a step portion (i.e., step portion 51b or 52b) is provided at the axial end of at least one of the yoke 51 and teeth 52 of the stator core 50, thereby weakening the magnetic attraction force between the rotor core 10 and the axial end of the stator core 50 and suppressing tilt of the shaft 30.

[0202] The electric motor 3D of the fifth embodiment may be used with the refrigerant described in the first or second embodiment. Furthermore, the permanent magnets 21a, 21b described in the third embodiment may be provided on each magnetic pole of the rotor 1D. Furthermore, the rotor core 10 and the stator core 50 may be formed from the electromagnetic steel sheets 10S, 50S described in the fourth embodiment.

[0203] Embodiment 6 Fig. 22(A) is a cross-sectional view showing a rotor 1E of embodiment 6. As shown in Fig. 22(A), the rotor 1E of embodiment 6 differs from the rotor 1 (Fig. 2) of embodiment 1 in that the number of poles is eight.

[0204] Eight magnet insertion holes 11 are formed in the rotor core 10 of the rotor 1E. The magnet insertion holes 11 are formed at equal intervals in the circumferential direction. One permanent magnet 20 is disposed in each magnet insertion hole 11. Flux barriers 12 are formed on both circumferential sides of each magnet insertion hole 11.

[0205] The rotor 1E of the sixth embodiment has more poles than the six-pole rotor 1 (FIG. 2) of the first embodiment. Therefore, the magnet insertion holes 11 of the sixth embodiment have a shorter circumferential length and are formed further radially outward than the magnet insertion holes 11 of the first embodiment. In other words, the permanent magnets 20 of the sixth embodiment have a shorter circumferential length than the permanent magnets 20 of the first embodiment, and are positioned further radially outward than the permanent magnets 20 of the first embodiment.

[0206] Therefore, compared to the rotor 1 (FIG. 2) of the first embodiment, the rotor 1E of the sixth embodiment has a larger space radially inward of the magnet insertion holes 11. This makes it possible to form large-area gaps A and B radially inward of the magnet insertion holes 11 of the rotor core 10.

[0207] As a result, the function of adjusting the eccentricity of the rotor 1E by the gaps A and B of the rotor core 10 is further enhanced, and the effect of reducing the size of the balance weights 31 and 32 (FIG. 4) or eliminating them altogether can be enhanced.

[0208] The rotor 1E is configured similarly to the rotor 1 of embodiment 1 (FIG. 2) except for the number and arrangement of the magnet insertion holes 11 and the number and arrangement of the permanent magnets 20. The number of poles of the rotor 1E is not limited to eight, and may be more than eight.

[0209] As described above, the rotor 1F of embodiment 6 has eight or more poles, so that a larger space can be secured radially inward from the magnet insertion holes 11 of the rotor core 10, making it possible to form gaps A and B with larger areas, thereby further improving the ability to adjust the eccentricity of the rotor 1E.

[0210] An electric motor having the rotor 1F of the sixth embodiment may be used with the refrigerant described in the first or second embodiment. Furthermore, the permanent magnets 21a, 21b described in the third embodiment may be provided on each magnetic pole of the rotor 1F. Furthermore, the rotor core 10 and the stator core 50 may be formed from the electromagnetic steel sheets 10S, 50S described in the fourth embodiment. The stepped portion 52b described in the fifth embodiment may be formed on the stator core 50.

[0211] Variation 2. Fig. 22(B) is a cross-sectional view showing a rotor 1F of Modification 2. As shown in Fig. 22(B), the rotor 1F of Modification 2 differs from the rotor 1E of Embodiment 6 in that the number of poles is four.

[0212] Four magnet insertion holes 11 are formed in the rotor core 10 of the rotor 1F. The magnet insertion holes 11 are formed at equal intervals in the circumferential direction. One permanent magnet 20 is disposed in each magnet insertion hole 11. Flux barriers 12 are formed on both circumferential sides of each magnet insertion hole 11.

[0213] The rotor 1F of Modification 2 has fewer poles than the six-pole rotor 1 (FIG. 2) of Embodiment 1. Therefore, the magnet insertion holes 11 of Modification 2 are longer in the circumferential direction and are formed further radially inward than the magnet insertion holes 11 of Embodiment 1. In other words, the permanent magnets 20 of Modification 2 are longer in the circumferential direction than the permanent magnets 20 of Embodiment 1 and are positioned further radially inward than the permanent magnets 20 of Embodiment 1.

[0214] Therefore, in the rotor 1F of the second modification, the space radially inward of the magnet insertion hole 11 (ie, the space forming the gaps A and B) is narrower than in the rotor 1 of the first embodiment (FIG. 2).

[0215] Therefore, compared to the rotor 1F of variant example 2 (Figure 22(B)), which has four poles, the rotor 1 of embodiment 1 (Figure 2), which has six poles, is preferable, and the rotor 1F of embodiment 6 (Figure 22(A)), which has eight poles, is even more preferable.

[0216] Embodiment 7 Fig. 23 is a cross-sectional view showing a rotor 1G according to embodiment 7. As shown in Fig. 23, the rotor 1G according to embodiment 7 differs from the rotor 1 according to embodiment 1 in that the permanent magnets 25 on the first side S1 and the permanent magnets 26 on the second side S2 have different coercive forces.

[0217] In the seventh embodiment, a permanent magnet 25 serving as a first permanent magnet is disposed in the magnet insertion hole 11 on the first side S1. A permanent magnet 26 serving as a second permanent magnet is disposed in the magnet insertion hole 11 on the second side S2. Both the permanent magnets 25 and 26 are formed of rare earth magnets, and heavy rare earth elements (e.g., dysprosium, terbium) are added as necessary.

[0218] The coercive force of permanent magnet 25 is lower than that of permanent magnet 26. For example, by making the content of heavy rare earth elements in permanent magnet 25 less than that of heavy rare earth elements in permanent magnet 26 (or making it zero), the coercive force of permanent magnet 25 can be made lower than that of permanent magnet 26.

[0219] As described in the first embodiment, the total area of ​​the gaps A on the first side S1 of the rotor 1G is larger than the total area of ​​the gaps B on the second side S2. Because the refrigerant passes through the gaps A and B, the first side S1 of the rotor core 10 is cooled more than the second side S2.

[0220] Because the permanent magnets 25 and 26 are rare earth magnets, they are prone to irreversible demagnetization at high temperatures. However, because the permanent magnet 25 on the first side S1 is located radially outside the air gap A, the temperature rise is suppressed, whereas the permanent magnet 26 on the second side S2 is located radially outside the air gap B, so the temperature rise is likely to occur.

[0221] Therefore, by making the coercive force of permanent magnet 26, which is prone to temperature rise, higher than the coercive force of permanent magnet 25, it is possible to suppress irreversible demagnetization of both permanent magnets 25 and 26. Furthermore, by reducing the heavy rare earth element content of permanent magnet 25, it is possible to reduce the manufacturing cost of rotor 1G.

[0222] As described above, the rotor 1G of embodiment 7 can suppress irreversible demagnetization of both the permanent magnets 25 and 26 and reduce the manufacturing cost of the rotor 1G by making the coercive force of the permanent magnet 25 on the first side S1 lower than the coercive force of the permanent magnet 26 on the second side S2.

[0223] An electric motor having the rotor 1G of embodiment 7 may be used with the refrigerant described in embodiment 1 or 2. Furthermore, the permanent magnets 21a, 21b described in embodiment 3 may be provided on each magnetic pole of the rotor 1G. Furthermore, the rotor core 10 and the stator core 50 may be formed from the electromagnetic steel sheets 10S, 50S described in embodiment 4. The stepped portion 52b described in embodiment 5 may be formed on the stator core 50. Furthermore, the number of poles of the rotor 1G may be eight or more, as described in embodiment 6.

[0224] Variation 3. Fig. 24 is a cross-sectional view showing a rotor 1H of Modification 3. As shown in Fig. 24, rotor 1H of Modification 3 differs from rotor 1 of embodiment 1 in the shape of magnet insertion holes 110 and the material of permanent magnets 28.

[0225] The rotor 1H has a plurality of magnet insertion holes 110 formed along the outer periphery 19 of the rotor core 10. The magnet insertion holes 110 are arranged at equal intervals in the circumferential direction. In this example, there are six magnet insertion holes 110. One permanent magnet 28 is inserted into each magnet insertion hole 110. The permanent magnets 28 are made of a non-rare earth magnet, more specifically, a ferrite magnet.

[0226] The magnet insertion hole 110 has a first edge 111 on the radially outer side and a second edge 112 on the radially inner side. The first edge 111 of the magnet insertion hole 110 has a curved shape that follows the outer periphery 19 of the rotor core 10. The second edge 112 of the magnet insertion hole 110 has a curved shape that curves in the opposite direction to the first edge 111. In other words, the magnet insertion hole 110 has a shape in which its radial thickness is greatest at the pole center.

[0227] The rotor 1H is configured in the same manner as the rotor 1 of the first embodiment, except for the shape of the magnet insertion holes 110 and the material of the permanent magnets 20.

[0228] In the rotor 1H of the third modification, the permanent magnets 28 are made of ferrite magnets, which are less expensive than rare earth magnets and therefore have the advantage of reducing manufacturing costs.

[0229] However, because ferrite magnets have a weaker magnetic force than rare earth magnets, the volume of the permanent magnets 28 must be increased, and so must the magnet insertion holes 110. As a result, the space radially inward of the magnet insertion holes 110 in the rotor core 10 becomes narrower, limiting the area of ​​the gaps A and B formed in that space.

[0230] In contrast, in the rotor 1 (FIG. 2) of the first embodiment described above, the permanent magnets 20 are made of rare earth magnets, which not only provides high output but also ensures a larger space radially inward of the magnet insertion holes 11 in the rotor core 10. This increases the difference in the total areas of the gaps A and B, thereby improving the ability to adjust the eccentricity of the rotor 1.

[0231] The above-described first to seventh embodiments and first to third modifications can be combined as appropriate.

[0232] Although the preferred embodiments have been specifically described above, the present disclosure is not limited to the above-described embodiments, and various improvements and modifications can be made. [Explanation of symbols]

[0233] 1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H rotor, 3, 3C, 3D electric motor, 5, 5C stator, 10 rotor core, 11, 110 magnet insertion hole, 12 flux barrier, 13 circumferential rib (first circumferential rib), 14 circumferential rib (second circumferential rib), 15 radial rib (first radial rib), 16 radial rib (second radial rib), 17 radial rib, 18 center hole, 19 outer periphery, 20, 21, 21a, 21b, permanent magnet, 25 permanent magnet (first permanent magnet), 26 permanent magnet (second permanent magnet), 28 permanent magnet, 30 shaft, 31, 32 balance weight, 50 stator core, 51 Yoke, 51b stepped portion, 52 teeth, 52b stepped portion, 53 slot, 54 insulating portion, 55 coil, 7,8 compressors, 71,81 sealed container, 72,82 compression mechanism, 9 refrigeration cycle device, 91 compressor, 92 condenser, 93 pressure reducing device, 94 evaporator, A,A1 to Am gap (first gap), e1 inner peripheral edge, e2 outer peripheral edge, e3 side edge, B,B1 to Bn gap (second gap), f1 inner peripheral edge, f2 outer peripheral edge, f3 side edge, S1 first side, S2 second side, T reference plane.

Claims

1. 1. A rotor of an electric motor for use with a refrigerant, comprising: an annular rotor core extending in a circumferential direction about a rotation axis, the rotor core having a center hole at a radial center about the rotation axis and magnet insertion holes located radially outward of the center hole; a permanent magnet disposed in the magnet insertion hole; and the rotor core has, in a region between the center hole and the magnet insertion holes, m first air gaps (m is an integer of 1 or more) on a first side with respect to a reference plane including the rotation axis, and n second air gaps (n is an integer of 1 or more) on a second side with respect to the reference plane, a total area of ​​the m first voids is greater than a total area of ​​the n second voids in a plane perpendicular to the rotation axis; An edge of each first gap facing the central hole extends in an arc shape having a center on the rotation shaft side, and an edge of each second gap facing the central hole extends in an arc shape having a center on the rotation shaft side. Rotor.

2. The refrigerant contains a substance that has the property of causing a disproportionation reaction. The rotor of claim 1 .

3. The refrigerant is R1234yf, R1234ze(E), R448A, R449A, R452A, R452B, R454A, R454B, R454C, R463A, R513A, and R513B Contains at least one of The rotor of claim 1 .

4. The refrigerant is A single refrigerant selected from R290, R1234yf, R1234ze(E), and R1132(E), or A mixed refrigerant containing at least one of R444A, R444B, R445A, R446A, R447A, R447B, R452B, R454A, R454B, R454C, R455A, R457A, R459A, and R459B.

2. The rotor according to claim 1, wherein:

5. The permanent magnet is a rare earth magnet. A rotor according to any one of claims 1 to 4.

6. the permanent magnet disposed in the magnet insertion hole provided on the first side is a first permanent magnet, When the permanent magnet disposed in the magnet insertion hole provided on the second side is defined as a second permanent magnet, The coercive force of the first permanent magnet is lower than the coercive force of the second permanent magnet. A rotor according to any one of claims 1 to 4.

7. Has six or more magnetic poles A rotor according to any one of claims 1 to 4.

8. Two of the permanent magnets are arranged for one magnetic pole, a straight line passing through the center of the magnetic pole and the rotation axis is defined as a magnetic pole center line; In a plane perpendicular to the rotation axis, the area of ​​the rotor is S, the total area of ​​the m first air gaps is Sa, and the total area of ​​the n second air gaps is Sb; If the angle formed between the magnetic pole surface of the permanent magnet on the outer periphery of the rotor core and the magnetic pole center line is β, then: Sa / S≦20[%] Sb / S≦20[%] 70[degrees]≦β≦88[degrees] holds true A rotor according to any one of claims 1 to 4.

9. A rotor according to any one of claims 1 to 4; a stator surrounding the rotor; An electric motor having

10. the rotor core is a laminate of first electromagnetic steel sheets, a stator core of the stator is a laminate of second electromagnetic steel sheets, The thickness Tr of the first electromagnetic steel sheet and the thickness Ts of the second electromagnetic steel sheet satisfy Tr≧Ts.

10. The electric motor according to claim 9.

11. The iron loss Wr per unit weight of the first electrical steel sheet and the iron loss Ws per unit weight of the second electrical steel sheet, measured by an Epstein test, satisfy Wr≧Ws.

11. The electric motor according to claim 10.

12. The stator core of the stator has an annular yoke surrounding the rotor from the outside in the radial direction and a plurality of teeth extending from the yoke toward the rotor, and a slot is formed between two adjacent teeth of the plurality of teeth, A step portion facing the slot is formed on at least one of the end portion of the tooth in the direction of the rotation axis and the end portion of the yoke in the direction of the rotation axis.

10. The electric motor according to claim 9.

13. The electric motor according to claim 9; a compression mechanism driven by the electric motor to compress the refrigerant; A compressor equipped with

14. A compressor comprising the compressor according to claim 13, a condenser, a pressure reducing device, and an evaporator. Refrigeration cycle equipment.

Images