Rotor, motor, compressor, and refrigeration cycle device

Abstract

This rotor comprises: an annular rotor core that extends in the circumferential direction around a rotation axis, the rotor core having a center hole at the center in the radial direction around the rotation axis and having a magnet insertion hole on the outer side in the radial direction with respect to the center hole; and a permanent magnet that is composed of a rare earth magnet disposed in the magnet insertion hole. In a region between the center hole and the magnet insertion hole, the rotor core has m first gaps (m being an integer of 1 or greater) on a first side with respect to a reference plane including the rotation axis, and n second gaps (n being an integer of 1 or greater) on a second side with respect to the reference plane. In a plane orthogonal to the rotation axis, the total area of the m first gaps is greater than the total area of the n second gaps.

Description

Rotor, motor, compressor and refrigeration cycle device

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

[0002] The rotor has a rotor core with a center hole and magnet insertion holes, permanent magnets arranged in the magnet insertion holes, and a shaft fixed to the center hole. To adjust the eccentricity of the rotor, a rotor core with an eccentric hole on one side of a reference plane including the rotation axis of the rotor core is known (see, for example, Patent Document 1).

[0003] Patent No. 7088229 (see Figure 2)

[0004] Here, heat generated by friction between the shaft and bearings is transferred to the central hole of the rotor core. On the side of the rotor core where the eccentric hole is not provided, heat is easily transferred from the central hole to the magnet insertion holes, causing the temperature of the permanent magnets to rise and potentially causing thermal demagnetization.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to suppress thermal demagnetization of permanent magnets.

[0006] The rotor disclosed herein is an annular rotor core extending circumferentially about a rotation axis, the rotor core having a center hole at its radial center about the rotation axis and magnet insertion holes radially outward from the center hole, and permanent magnets made of rare earth magnets disposed 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 air 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 air 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 air gaps is greater than the total area of ​​the n second air gaps.

[0007] In the present disclosure, m first voids are provided on the first side of the rotor core and n second voids are provided on the second side, which makes it difficult for heat to be transferred from the center hole to the magnet insertion holes, thereby suppressing thermal demagnetization of the permanent magnets. Furthermore, because the total area of ​​the m first voids is larger than the total area of ​​the n second voids, the eccentricity of the rotor can be adjusted.

[0008] 10 is a cross-sectional view showing a motor according to a first embodiment; FIG. 11 is a cross-sectional view showing a rotor according to the first embodiment; FIG. 12 is a longitudinal cross-sectional view showing a rotor according to the first embodiment; FIG. 13 is a cross-sectional view showing another configuration example of the rotor according to the first embodiment; FIG. 14 is a cross-sectional view showing a rotor of a comparative example (A), and a graph (B) showing the analysis results of the temperature transition of a permanent magnet; FIG. 15 is a cross-sectional view showing a rotor according to a second embodiment (A), and a schematic diagram (B) showing two first air gaps of the rotor; FIG. 16 is a cross-sectional view showing a rotor according to the second embodiment (A), and a graph (B) showing the analysis results of the temperature transition of a permanent magnet; FIG. 17 is a cross-sectional view showing a rotor according to a third embodiment; FIG. 18 is a longitudinal cross-sectional view showing a rotor according to a fourth embodiment; FIG. 19 is a longitudinal cross-sectional view showing a compressor to which the motors according to the first to fourth embodiments can be applied; FIG. 19 is a diagram showing a refrigeration cycle device including the compressor of FIG.

[0009] Embodiment 1. <Configuration of Motor 5> Figure 1 is a cross-sectional view showing a motor 5 according to embodiment 1. The motor 5 includes a shaft 25, a rotor 1 attached to the shaft 25, and an annular stator 3 surrounding the rotor 1. An air gap of 0.3 mm to 1.0 mm is provided between the stator 3 and the rotor 1. The stator 3 is fixed to the inside of a cylindrical shell 28 of a compressor 300 (Figure 10), 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 taken along a plane parallel to the rotation axis C1 will be referred to as a "longitudinal cross-sectional view," and a cross-sectional view taken along a plane perpendicular to the rotation axis C1 will be referred to as a "transverse cross-sectional view."

[0011] <Configuration of Stator 3> The stator 3 has an annular stator core 30 and a coil 35 wound around the stator core 30. The stator core 30 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, and is 0.35 mm, for example.

[0012] The stator core 30 has a yoke 31 extending in the circumferential direction and a plurality of teeth 32 extending radially inward from the yoke 31. Slots 33, which are spaces for accommodating coils 35, are formed between adjacent teeth 32.

[0013] Here, nine teeth 32 are provided at equal intervals in the circumferential direction. However, the number of teeth 32 is not limited to nine, and may be two or more. An insulating portion is provided between the stator core 30 and the coil 35. The insulating portion is, for example, the insulating portion 34 shown in FIG. 10 or an insulating film.

[0014] A groove 30c is formed on the outer periphery of the yoke 31, forming a refrigerant flow path between the shell 28 and the yoke 31. Crimped portions 30a are formed on both circumferential sides of the groove 30c in the yoke 31 for fixing the electromagnetic steel sheets that make up the stator core 30 to one another. A recess 30b is formed radially inside the groove 30c for fixing an insulating portion to the stator core 30. The arrangement of the crimped portions 30a, recess 30b, and groove 30c is arbitrary.

[0015] The coils 35 are made of magnet wire. The magnet wire is a conductor made of copper or aluminum covered with an insulating coating. The coils 35 are wound around the teeth 32 via insulating parts. The coils 35 are wound using concentrated winding, in which the magnet wire is wound around each tooth 32 individually.

[0016] The wire diameter and number of turns of the coil 35 are determined based on the characteristics required of the motor 5 (e.g., rotation speed, torque, etc.), voltage specifications, the cross-sectional area of ​​the slot 33, etc. For example, a magnet wire with a wire diameter of 1.0 mm is wound around one tooth 32 about 80 turns.

[0017] The stator core 30 may be configured by combining split cores in the circumferential direction, each split core being divided into individual teeth 32. In this case, the stator core 30 is spread out in a strip shape, and the coils 35 are wound around each tooth 32 via an insulating portion. Thereafter, the stator core 30 is bent into an annular shape and both ends are welded, thereby obtaining the stator 3.

[0018] <Configuration of Rotor 1> Fig. 2 is a cross-sectional view showing the rotor 1. The rotor 1 has a rotor core 10 and permanent magnets 20. The rotor core 10 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 or less, and is 0.35 mm, for example.

[0019] A center hole 13 is formed in the radial center of the rotor core 10. The center hole 13 of the rotor core 10 is fixed to the shaft 25. The fixing method may be, for example, shrink fitting or press fitting.

[0020] A number k (k is an integer of 2 or greater) of magnet insertion holes 11 are formed along the outer periphery 14 of the rotor core 10. The k 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.

[0021] The permanent magnet 20 is flat, 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 a rare earth magnet. For example, a neodymium magnet containing neodymium (Nd), iron (Fe), and boron (B) is used as the rare earth magnet.

[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 M.

[0023] Flux barriers 12 serving as leakage flux suppression holes are formed on both circumferential sides of each magnet insertion hole 11. Thin-walled portions are formed between the flux barriers 12 and the outer periphery 14 of the rotor core 10. The thickness of the thin-walled portions is set to be equal to the thickness of the electromagnetic steel plates, for example, in order to suppress leakage flux between adjacent magnetic poles.

[0024] Here, the number (k) 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, although one permanent magnet 20 is placed in each magnet insertion hole 11 here, two or more permanent magnets 20 may be placed in each magnet insertion hole 11. Also, although the magnet insertion hole 11 extends linearly here, it may extend in a V-shape, for example.

[0026] The rotor 1 has m air gaps A1 to Am and n air gaps B1 to Bn in the radial region between the center hole 13 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, but are not limited to 3. 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.

[0028] The plane passing through the rotation axis C1 is referred to as the reference plane T. The reference plane T is set in consideration of 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.

[0029] 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.

[0030] The voids A1, A2, and A3 shown in Fig. 2 are arranged in this order counterclockwise in the drawing. Similarly, the voids B1, B2, and B3 shown in Fig. 2 are arranged in this order counterclockwise in the drawing.

[0031] In the example shown in Figure 2, the voids A1 to A3 have the same shape and the same dimensions. Similarly, the voids B1 to B3 have the same shape and the same 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.

[0032] The gap A has an inner peripheral edge 51 on the side of the center hole 13, an outer peripheral edge 52 on the side of the outer periphery 14, and side edges 53 on both sides in the circumferential direction. Both the inner peripheral edge 51 and the outer peripheral edge 52 extend in an arc shape centered on the rotation axis C1. The side edges 53 extend in a curved radial direction.

[0033] Ribs 15, which are iron core portions, are formed between adjacent gaps A. The ribs 15 are sandwiched from both sides in the circumferential direction by the side edges 53 of adjacent gaps A. The width D1 of the rib 15 is narrowest at its radial center. The ribs 15 are also referred to as first ribs.

[0034] The gap B has an inner peripheral edge 61 on the side of the center hole 13, an outer peripheral edge 62 on the side of the outer periphery 14, and side edges 63 on both sides in the circumferential direction. Both the inner peripheral edge 61 and the outer peripheral edge 62 extend in an arc shape centered on the rotation axis C1. The side edges 63 extend in a curved radial direction.

[0035] Ribs 16, which are iron core portions, are formed between adjacent gaps B. The ribs 16 are sandwiched from both circumferential sides by the side edges 63 of adjacent gaps B. The width D2 of the ribs 16 is narrowest at the radial center. The ribs 16 are also referred to as second ribs.

[0036] A rib 17, which is an iron core portion, is also formed between the gap A and the gap B. The rib 17 is located on the reference plane T. The rib 17 is also referred to as a third rib.

[0037] 2, gap A has a width W1 in the radial direction. Width W1 is the distance from inner peripheral edge 51 to outer peripheral edge 52. Gap B has a width W2 in the radial direction. Width W2 is the distance from inner peripheral edge 61 to outer peripheral edge 62. Width W1 of gap A is wider than width W2 of gap B (i.e., W1 > W2).

[0038] In the first embodiment, in a plane perpendicular to the rotation axis C1, the area of ​​each void A is larger than the area of ​​each void B. Therefore, the total area of ​​the voids A1 to A3 is larger than the total area of ​​the voids B1 to B3.

[0039] Therefore, the weight of the first side S1 of the rotor core 10 is lighter than the weight of the second side S2 of the rotor core 10. This allows the amount of eccentricity of the rotor 1 to be adjusted.

[0040] Here, the shortest distance R1 from the rotation axis C1 to the gap A is equal to the shortest distance R2 from the rotation axis C1 to the gap B (i.e., R1=R2). The case where R1<R2 will be described later (see FIG. 8).

[0041] Furthermore, here, the circumferential width D1 of rib 15 and the circumferential width D2 of rib 16 are equal (i.e., D1 = D2). A case where D1 < D2 will be described later (see FIG. 8). Due to processing constraints, both widths D1 and D2 are set to be equal to or greater than the thickness of the electromagnetic steel sheets that make up rotor core 10.

[0042] 3 is a longitudinal cross-sectional view showing the rotor 1. The gap A extends in the axial direction from a first end face 10a, which is one axial end face of the rotor core 10, to a second end face 10b, which is the other axial end face of the rotor core 10. The radial width W1 of the gap A is constant. Similarly, the gap B extends in the axial direction from the first end face 10a to the second end face 10b of the rotor core 10. The radial width W2 of the gap B is constant.

[0043] Fig. 4 is a cross-sectional view showing another example of the rotor 1. In the example shown in Fig. 4, the rotor core 10 has six gaps A1 to A6 on the first side S1 and six gaps B1 to B6 on the second side S2. In Fig. 4 as well, the radial width W1 of gap A is larger than the radial width of gap B. Therefore, the total area of ​​gaps A1 to A6 is larger than the total area of ​​gaps B1 to B6.

[0044] <Operation> Next, the operation of the first embodiment will be described. In the motor 5 used in the compressor 300 ( FIG. 10 ) or the like, heat is generated due to friction between the shaft 25 and the bearing of the compression mechanism 301. The heat of the shaft 25 is transferred from the center hole 13 to the rotor core 10.

[0045] The rare earth magnet used for permanent magnet 20 has the property that its coercive force decreases with an increase in temperature. For example, a 1°C increase in temperature reduces the coercive force by 0.5 to 0.6%. Therefore, an increase in temperature of permanent magnet 20 can lead to demagnetization at high temperatures, i.e., thermal demagnetization.

[0046] 5A is a schematic diagram showing a rotor 1E of a comparative example to be compared with embodiment 1. In the rotor 1E of the comparative example, in order to adjust the amount of eccentricity, two gaps A are formed on a first side S1 with respect to the reference plane T in the region between the center hole 13 and the magnet insertion hole 11. On the other hand, no gaps are formed on a second side S2 with respect to the reference plane T.

[0047] Since the gaps A1 and A2 are provided only on the first side S1, the weight of the rotor core 10 is greater on the second side S2 than on the first side S1, making it possible to adjust the eccentricity of the rotor 1E. In other words, it can function similarly to a balance weight.

[0048] Here, of the three permanent magnets 20 on the first side S1, the permanent magnet 20 located at a position 90 degrees from the reference plane T with the rotation axis C1 as the center is referred to as permanent magnet 201, and the permanent magnet 20 adjacent to this permanent magnet 201 is referred to as permanent magnet 202. In addition, the permanent magnet 20 located on the opposite side of the permanent magnet 201 is referred to as permanent magnet 203.

[0049] Permanent magnets 201 and 202 are arranged on a first side S1 with respect to a reference plane T, and permanent magnet 203 is arranged on a second side S2 with respect to the reference plane T. Air gap A1 is formed radially inside permanent magnet 201, and air gap A2 is formed radially inside permanent magnet 202. No air gap is formed radially inside permanent magnet 203.

[0050] 5A also shows points Q1, Q2, and Q3 on the surface of the permanent magnet 20 of the rotor 1E on the side of the center hole 13. Point Q1 is located at the circumferential center of the surface of the permanent magnet 201. Point Q2 is located at the circumferential center of the surface of the permanent magnet 202. Point Q3 is located at the circumferential center of the surface of the permanent magnet 203.

[0051] Figure 5(B) is a graph showing the analysis results of temperature transitions at points Q1 to Q3 when a constant amount of heat is continuously applied to central hole 13. As shown in Figure 5(B), the temperature is highest at point Q3. This is because there is no gap between central hole 13 and magnet insertion hole 11 into which permanent magnet 203 is inserted to prevent heat transfer (indicated by arrow H in Figure 5(A)).

[0052] On the other hand, the temperatures at points Q1 and Q2 are approximately 20% lower than the temperature at point Q3 because there are gaps A1 and A2 between the center hole 13 and the magnet insertion holes 11 into which the permanent magnets 201 and 202 are inserted, which prevent heat transfer.

[0053] As such, in the comparative rotor 1E, there is a bias in the way heat is transferred from the center hole 13 to the magnet insertion hole 11 between the first side S1 and the second side S2, and as a result, the temperature of the permanent magnet 20 rises on the second side S2, which may result in thermal demagnetization.

[0054] In contrast, in embodiment 1, as shown in Figure 2, in the region between the center hole 13 and the magnet insertion hole 11 of the rotor core 10, gaps A1 to Am are provided on the first side S1, and gaps B1 to Bn are provided on the second side.

[0055] Therefore, gaps A1 to Am and gaps B1 to Bn can suppress heat transfer from center hole 13 of rotor core 10 to magnet insertion holes 11. In other words, it is possible to suppress temperature rise in all permanent magnets 20 of rotor 1, and to suppress thermal demagnetization.

[0056] Furthermore, because the total area of ​​the gaps A1 to Am in a plane perpendicular to the axial direction is greater than the total area of ​​the gaps B1 to Bn in a plane perpendicular to the axial direction, the weight of the second side S2 is greater than the weight of the first side S1 of the rotor core 10. As a result, the eccentricity of the rotor 1 can be adjusted, and the balance weight can be reduced.

[0057] Generally, increasing the radial width of the gap is more effective than increasing the circumferential length of the gap in adjusting the amount of eccentricity of the rotor 1. As described above, by making the radial width W1 of gap A larger than the radial width W2 of gap B (W1 > W2), the effect of adjusting the amount of eccentricity of the rotor 1 can be increased.

[0058] It is desirable that the radial width W1 of all gaps A1 to Am be wider than the radial width W2 of all gaps B1 to Bm, but if the radial width W1 of at least one gap A is wider than the radial width W2 of at least one gap B, the effect of adjusting the eccentricity of the rotor 1 can be enhanced.

[0059] 2, the air gap A or the air gap B is arranged to face radially relative to the circumferential center (i.e., the pole center) of all magnet insertion holes 11. This makes it possible to effectively suppress temperature rise in all permanent magnets 20. Specifically, by making the number m of air gaps A and the number n of air gaps B equal to 1 / 2 of the number k of poles (i.e., m = n = k / 2), the effect of suppressing temperature rise in the permanent magnets 20 can be enhanced.

[0060] Here, the heat applied to center hole 13 of rotor core 10 has been described as frictional heat with the bearing of compression mechanism 301 (FIG. 10), but heat is also applied to expand the inner diameter of center hole 13 in the shrink-fitting process for fixing shaft 25 to rotor core 10. In this case as well, gaps A1-Am and gaps B1-Bn can suppress heat transfer from center hole 13 to magnet insertion hole 11, thereby suppressing thermal demagnetization of permanent magnet 20.

[0061] <Effects of the embodiment> As described above, the rotor 1 of the first embodiment includes a rotor core 10 having a center hole 13 and magnet insertion holes 11, and permanent magnets 20 made of rare earth magnets that are arranged in the magnet insertion holes 11. In a region between the center hole 13 and the magnet insertion holes 11, the rotor core 10 has m (m is an integer of 1 or more) gaps A as first gaps 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 more) gaps B as second gaps on a second side S2 with respect to the reference plane T. In a plane perpendicular to the rotation axis C1, the total area of ​​the n gaps A is greater than the total area of ​​the m gaps B.

[0062] Since gap A is provided on first side S1 and gap B is provided on second side S2, gaps A and B suppress the transfer of heat from center hole 13 to magnet insertion hole 11, thereby suppressing the temperature rise and accompanying thermal demagnetization of permanent magnet 20. Furthermore, since the total area of ​​m gaps A is larger than the total area of ​​n gaps B, the amount of eccentricity of rotor 1 can be adjusted.

[0063] In particular, since the radial width W1 of the gap A is wider than the radial width W2 of the gap B (W1>W2), the eccentricity of the rotor 1 can be adjusted more effectively.

[0064] 6A is a diagram showing a rotor 1A according to embodiment 2. The rotor 1A according to embodiment 2 differs from the rotor 1 according to embodiment 1 in the shape of the gaps A1 to Am serving as first gaps.

[0065] As shown in Fig. 6(A), the rotor core 10 of the rotor 1A has gaps A1 to Am as first gaps on a first side S1 with respect to a reference plane T in a region between the center hole 13 and the magnet insertion holes 11 in the radial direction, and gaps B1 to Bn as second gaps on a second side S2. In the example shown in Fig. 6(A), both m and n are 4, but are not limited to 4. Furthermore, m and n do not have to be the same number.

[0066] 6A, the rib 15 between the gaps A2 and A3 is located on the magnetic pole center line P of one magnetic pole. The gaps A2 and A3 have shapes symmetrical to each other with respect to the magnetic pole center line P.

[0067] 6B is an enlarged schematic diagram of gaps A2 and A3. Gap A2 has an inner peripheral edge 51 on the center hole 13 side, an outer peripheral edge 52 on the outer periphery 14 side, a side edge 53a on the magnetic pole center line P side, and an opposite side edge 53b.

[0068] The gap A2 has an asymmetric shape with respect to the line V. The line V is a line passing through the rotation axis C1 and bisects the area of ​​the gap A2 in a plane perpendicular to the axial direction. The side edge 53a of the gap A2 is curved so that the circumferential width of the rib 15 between the gap A2 and the gap A3 increases radially outward.

[0069] The side edge 53b of the gap A2 extends linearly radially outward from the end of the inner peripheral edge 51 and is curved where it joins the outer peripheral edge 52. However, the side edge 53b of the gap A2 may extend linearly overall or may be curved. Both the inner peripheral edge 51 and the outer peripheral edge 52 extend in an arc shape centered on the rotation axis C1.

[0070] The gap A3 has a shape symmetrical to the gap A2 across the rib 15. That is, the gap A3 has a shape asymmetrical with respect to the line V. The line V is a line passing through the rotation axis C1 and is a line that bisects the area of ​​the gap A3 in a plane perpendicular to the axial direction.

[0071] The circumferential width D1 of the rib 15 between the gaps A2 and A3 becomes wider toward the radially outer side. ｉｎ The width D1 of the radially outer end of the rib 15 is ｏｕｔ is wider.

[0072] As shown in Figure 6A, gap A1 has an inner peripheral edge 51 on the center hole 13 side, an outer peripheral edge 52 on the outer periphery 14 side, and side edges 53 on both sides in the circumferential direction. Both inner peripheral edge 51 and outer peripheral edge 52 extend in an arc shape centered on rotation axis C1. Side edge 53 extends linearly in the radial direction. Gap A4 has the same shape as gap A1.

[0073] The gaps B1 to B4 are formed in the same manner as the gaps B1 to B3 shown in FIG. 3 of the first embodiment, except for the number and circumferential length.

[0074] In the second embodiment, the width of the rib 15 between the gaps A2 and A3 increases radially outward, so that heat traveling from the center hole 13 of the rotor core 10 toward the magnet insertion holes 11 spreads to both sides in the circumferential direction. As a result, the heat passing through the rib 15 toward the magnet insertion holes 11 can be dispersed in the circumferential direction, and the temperature rise of the permanent magnets 20 can be suppressed.

[0075] 7A is a diagram showing points P1, P2, P3, and P4 on the surface of the permanent magnet 20 of the rotor 1A on the side of the center hole 13. Point P1 is located at the center of the surface of the permanent magnet 20 radially outside the rib 15 between the gaps A2 and A3. Point P2 is located at the center of the surface of the permanent magnet 20 radially outside the gap A4. Point P3 is located at the center of the surface of the permanent magnet 20 radially outside the gap B1. Point P4 is located at the center of the surface of the permanent magnet 20 radially outside the rib 16 between the gaps B2 and B3.

[0076] 7B is a graph showing the results of a numerical analysis of the temperature transition at points P1 to P4 when a constant amount of heat is continuously applied to the central hole 13. As shown in FIG. 7B, the temperature at point P4 is the highest, and the temperature at point P3 is the second highest.

[0077] This is because the radial width W2 of the gaps B1 to B4 (FIG. 6A) is narrower than the radial width W1 of the gaps A1 to A4 (FIG. 6A). Also, the temperature at point P4 is higher than the temperature at point P3 because point P4 is located radially outward of rib 16 and heat from central hole 13 is easily transferred to point P4.

[0078] On the other hand, the temperature at point P2 is the lowest. Specifically, the temperature at point P2 is approximately 10% lower than the temperature at point P4. This is because point P2 is located radially outside gap A4, which has a wide width W1. Furthermore, the temperature at point P1 is higher than the temperature at point P2. This is because point P1 is located radially outside rib 15.

[0079] However, since the gaps A2 and A3 have the asymmetric shape described above and have the effect of dispersing the heat passing through the rib 15, the temperature rise at the point P1 is also suppressed.

[0080] 6A and 6B, the side edge 53 of the gap A1 extends linearly, and the side edge 53b of the opposing gap A2 is curved toward the outer periphery 14. Therefore, heat that passes through the rib 15 between the gaps A1 and A2 is guided toward the inter-pole (i.e., between adjacent magnet insertion holes 11) side rather than toward the permanent magnets 20 radially outside the gap A1. This enhances the effect of suppressing temperature rise in the permanent magnets 20.

[0081] As described above, the number m of voids A and the number n of voids B are not limited to 4, but in order to form ribs 15 between adjacent voids A, it is desirable that the number m of voids A be 2 or more.

[0082] Furthermore, although the case where the rib 15 between the gaps A2 and A3 is located on the magnetic pole center line P has been described here, the rib 15 between the gaps A2 and A3 does not necessarily have to be located on the magnetic pole center line P.

[0083] Furthermore, if at least one of the gaps A among the gaps A1 to Am has the asymmetric shape (FIG. 6B), it is possible to obtain the effect of dispersing heat passing through the rib 15 in the circumferential direction, thereby suppressing the temperature rise of the permanent magnet 20. Furthermore, although the case where the gap A has an asymmetric shape has been described here, the gap B may also have an asymmetric shape.

[0084] Except for the points mentioned above, the rotor 1A of the second embodiment is configured similarly to the rotor 1 of the first embodiment.

[0085] As described above, in embodiment 2, at least one of the gaps A1 to Am in the rotor core 10 is formed asymmetrically with respect to the line V, which is a straight line passing through the rotation axis C1 and which bisects the gap area in a plane perpendicular to the axial direction, so that heat directed toward the magnet insertion hole 11 can be dispersed to both sides in the circumferential direction, thereby suppressing the temperature rise of the permanent magnet 20.

[0086] Furthermore, since the circumferential width of the rib 15 between two adjacent gaps A is wider at the radially outer end of the rib 15 than at the radially inner end, heat flowing from the center hole 13 toward the magnet insertion hole 11 can be more effectively dispersed, thereby suppressing the temperature rise of the permanent magnet 20.

[0087] 8 is a diagram showing a rotor 1B according to embodiment 3. The rotor 1B according to embodiment 3 differs from the rotor 1A according to embodiment 2 in the shape of the gaps A1 to Am and the arrangement of the gaps B1 to Bn.

[0088] As shown in Fig. 8, the rotor core 10 of the rotor 1B has gaps A1 to Am as first gaps on a first side S1 with respect to a reference plane T in a region between the center hole 13 and the magnet insertion holes 11 in the radial direction, and gaps B1 to Bn as second gaps on a second side S2. In the example shown in Fig. 8, both m and n are 4, but are not limited to 4. Furthermore, m and n do not have to be the same number.

[0089] 8, the rib 15 between the gaps A2 and A3 is located on the magnetic pole center line P of the permanent magnet 20. The gaps A2 and A3 have shapes symmetrical to each other with respect to the magnetic pole center line P.

[0090] The gap A2 has an inner peripheral edge 51 on the side of the center hole 13, an outer peripheral edge 52 on the side of the outer periphery 14, a side edge 53a on the side of the magnetic pole center line P, and an opposite side edge 53b. Both the inner peripheral edge 51 and the outer peripheral edge 52 extend in an arc shape centered on the rotation axis C1.

[0091] The side edge 53a of the gap A2 extends linearly from the end of the inner peripheral edge 51 to the end of the outer peripheral edge 52, parallel to the magnetic pole center line P. The side edge 53b extends radially outward from the end of the inner peripheral edge 51 and is curved where it joins the outer peripheral edge 52.

[0092] The gap A3 is formed symmetrically to the gap A2, with the rib 15 sandwiched between them. Since the side edges 53a of the gaps A2 and A3 both extend linearly parallel to the magnetic pole center line P, the circumferential width of the rib 15 between the gaps A2 and A3 is constant.

[0093] The gaps A1 and A4 have the same shapes as the gaps A1 and A4 in the second embodiment (FIG. 6A).

[0094] The gaps B1 to B4 have the same shape as the gaps B1 to B4 in the second embodiment (FIG. 6A). However, the shortest distance R2 from the rotation axis C1 to the gaps B1 to B4 is shorter than the shortest distance R1 from the rotation axis C1 to the gaps A1 to A4. In other words, R1>R2 holds. In other words, the gaps B1 to B4 are formed radially inward of the gaps A1 to A4.

[0095] Since the gaps B1 to B4 are formed radially inward of the gaps A1 to A4, heat transfer from the center hole 13 of the rotor core 10 to the magnet insertion holes 11 can be suppressed further radially inward.

[0096] Furthermore, the circumferential width D2 of the rib 16 between the gaps B1 to B4 is narrower than the circumferential width D1 of the rib 15 between the gaps A1 to A4.

[0097] As explained in embodiment 1, the radial width of the gap has a greater effect on the eccentricity of rotor 1B than the circumferential length of the gap, so the radial width W1 of gaps A1 to A4 is set wider than the radial width W2 of gaps B1 to B4.

[0098] However, since gaps B1 to B4 with a small radial width W2 have little effect in suppressing heat transfer from the center hole 13 of the rotor core 10 to the magnet insertion hole 11, there is a possibility that there will be a bias in the way heat is transferred from the center hole 13 to the magnet insertion hole 11 between the first side S1 and the second side S2.

[0099] In contrast, if the width D2 of the rib 16 between two gaps B1 to B4 is narrower than the width D1 of the rib 15 between two gaps A1 to A4, heat is less likely to pass through the rib 16. Therefore, the heat can be transferred more evenly from the center hole 13 to the magnet insertion holes 11 on the first side S1 and the second side S2 of the rotor core 10.

[0100] This effect can be obtained if the width D2 of the rib 16 between at least two gaps B (e.g., gaps B2 and B3) among the gaps B1 to B4 is narrower than the width D1 of the rib 15 between at least two gaps A1 to A4 (e.g., gaps A2 and A3).

[0101] If the circumferential width of the rib 15 varies depending on the radial position, the minimum width is defined as D1. Similarly, if the circumferential width of the rib 16 varies depending on the radial position, the minimum width is defined as D2.

[0102] The shapes of the gaps A2 and A3 are not limited to the shapes shown in Fig. 8. That is, the gaps A2 and A3 may have the same shapes as the gaps A1 and A4, or may have the same shapes as the gaps A1, A2, and A3 (Fig. 2) of the first embodiment.

[0103] Except for the above-mentioned points, the rotor 1B of the third embodiment is configured similarly to the rotor 1 of the first embodiment.

[0104] As described above, in the third embodiment, the shortest distance R2 from the rotation axis C1 to the gap B is shorter than the shortest distance R1 from the rotation axis C1 to the gap A (R1>R2), and therefore the gap B can prevent heat transfer from the center hole 13 to the magnet insertion hole 11 at a position further radially inward. This makes it possible to make the heat transfer to the magnet insertion hole 11 more uniform between the first side S1 and the second side S2 of the rotor core 10.

[0105] Furthermore, since the width D2 of the rib 16 between at least two of the n gaps B in the rotor core 10 is narrower than the width D1 of the rib 15 between at least two of the m gaps A (D1 > D2), the way heat is transferred from the center hole 13 to the magnet insertion hole 11 is made more uniform on the first side S1 and the second side S2 of the rotor core 10, thereby suppressing thermal demagnetization of the permanent magnet 20.

[0106] Furthermore, even if only one of the above-mentioned features R1>R2 and D1>D2 is used, it is possible to make the heat transfer from the center hole 13 to the magnet insertion hole 11 more uniform on the first side S1 and the second side S2 of the rotor core 10, thereby suppressing thermal demagnetization of the permanent magnet 20.

[0107] 9 is a longitudinal cross-sectional view showing a rotor 1C according to embodiment 4. The rotor 1C according to embodiment 4 differs from the rotor 1 (FIG. 3) according to embodiment 1 in that the rotor core 10 has a first core portion 101 and a second core portion 102, and the arrangements of the gaps A1 to Am and the gaps B1 to Bn are different between the first core portion 101 and the second core portion 102.

[0108] 9, rotor core 10 has a first core portion 101 and a second core portion 102 in the axial direction. The orientations of the electromagnetic steel sheets of first core portion 101 and second core portion 102 around rotation axis C1 are different by 180 degrees.

[0109] The gap A of the first core portion 101 and the gap B of the second core portion 102 are continuous in the axial direction. Similarly, the gap B of the first core portion 101 and the gap A of the second core portion 102 are continuous in the axial direction. In other words, the first side S1 and the second side S2 of the first core portion 101 and the second core portion 102 are reversed.

[0110] As described in the first embodiment, the radial width W1 of the gap A is wider than the radial width W2 of the gap B. Therefore, the continuous gaps A and B form a flow path whose cross-sectional area changes midway.

[0111] In the first embodiment described above, as shown in Fig. 2, both gaps A and B axially penetrate rotor core 10. Because gaps A and B have different radial widths W1 and W2, the rotational balance of rotor 1C may change depending on the density of the refrigerant used. The rotational balance of rotor 1C can be adjusted by attaching balance weights or the like to rotor core 10, but this increases the number of parts and costs.

[0112] Therefore, in the fourth embodiment, the orientation of the electromagnetic steel sheets is changed between the first core portion 101 and the second core portion 102 of the rotor core 10, thereby making it possible to adjust the rotational balance of the rotor 1C.

[0113] For example, the rotational balance of the rotor 1C can be adjusted by adjusting the ratio between the axial length of the first core portion 101 of the rotor core 10 (i.e., the number of laminated electromagnetic steel sheets) and the axial length of the second core portion 102.

[0114] Here, the orientation of the electromagnetic steel sheets around the rotation axis C1 differs by 180 degrees between the first core portion 101 and the second core portion 102, but is not limited to 180 degrees. However, the position of the magnet insertion hole 11 in the first core portion 101 and the position of the magnet insertion hole 11 in the second core portion 102 must be aligned.

[0115] Therefore, when the number m of gaps A and the number n of gaps B are the same and the number of poles of rotor 1C is k, the positions of first core portion 101, second core portion 102 and magnet insertion hole 11 can be aligned by rotating the electromagnetic steel plate of second core portion 102 relative to the electromagnetic steel plate of first core portion 101 by an angle equivalent to an integer multiple of 360 / k.

[0116] For example, if the number of poles k of rotor 1C is 6, the positions of the magnet insertion holes 11 in the first core portion 101 and the second core portion 102 can be aligned by rotating the electromagnetic steel plate of the second core portion 102 by 60 degrees, 120 degrees, 180 degrees, 240 degrees, or 300 degrees relative to the electromagnetic steel plate of the first core portion 101.

[0117] Except for the above-mentioned points, the rotor 1C of the fourth embodiment is configured similarly to the rotor 1 of the first embodiment.

[0118] As described above, in the fourth embodiment, rotor core 10 has first core portion 101 and second core portion 102, and gap A of first core portion 101 and gap B of second core portion 102 are continuous in the axial direction, and gap B of first core portion 101 and gap A of second core portion 102 are continuous in the axial direction. Therefore, by adjusting the ratio of the axial lengths of first core portion 101 and second core portion 102, etc., it is possible to adjust the rotational balance of rotor 1C.

[0119] <Compressor> Next, a compressor 300 to which the motor 5 of any of the first to fourth embodiments can be applied will be described. Fig. 10 is a vertical cross-sectional view showing the compressor 300 equipped with the motor 5 of the first embodiment. The compressor 300 is a rotary compressor in this example, but may also be a scroll compressor.

[0120] The compressor 300 includes a sealed container 307, a compression mechanism 301 disposed in the sealed container 307, and a motor 5 that drives the compression mechanism 301. The configuration of the motor 5 is as described in the first embodiment.

[0121] The compression mechanism 301 has a cylinder 302 having a cylinder chamber 303, a rolling piston 304 fixed to the shaft 25 of the motor 5, a vane that divides the interior of the cylinder chamber 303 into an intake side and a compression side, and an upper frame 305 and a lower frame 306 into which the shaft 25 is inserted and which close the axial end faces of the cylinder chamber 303. An upper discharge muffler 308 and a lower discharge muffler 309 are attached to the upper frame 305 and the lower frame 306, respectively.

[0122] The sealed container 307 is a cylindrical container. Refrigerating machine oil (not shown) that lubricates the sliding parts of the compression mechanism 301 is stored in the bottom of the sealed container 307. The shaft 25 is rotatably held by an upper frame 305 and a lower frame 306 that serve as bearings.

[0123] The cylinder 302 has a cylinder chamber 303 therein, and the rolling piston 304 rotates eccentrically within the cylinder chamber 303. The shaft 25 has an eccentric shaft portion, and the rolling piston 304 is fitted onto the eccentric shaft portion.

[0124] The stator 3 of the motor 5 is assembled inside the sealed container 307 by shrink fitting, press fitting, welding, or other methods. The shell 28 shown in FIG. 1 corresponds to a part of the sealed container 307. Electric power is supplied to the coil 35 of the stator 3 from a glass terminal 311 fixed to the sealed container 307. The shaft 25 is fixed to the rotor core 10 as described above.

[0125] An accumulator 310 is attached to the outside of the sealed container 307. Refrigerant gas flows into the accumulator 310 from the refrigerant circuit via a suction pipe 314. When liquid refrigerant flows in together with the refrigerant gas from the suction pipe 314, the liquid refrigerant is stored in the accumulator 310, and the refrigerant gas is supplied to the compressor 300.

[0126] A suction pipe 313 is fixed to the sealed container 307, and refrigerant gas is supplied from the accumulator 310 to the cylinder 302 via this suction pipe 313. In addition, a discharge pipe 312 is provided at the top of the sealed container 307 to discharge the refrigerant to the outside.

[0127] The eccentricity of the rotor 1 described in the first embodiment and the like is adjusted so that the rotation of the rotor 1 is stable, taking into consideration various factors such as the eccentricity of the rolling piston 304 in the compression mechanism 301.

[0128] The refrigerant used in the compressor 300 may be, for example, R410A, R407C, or R22. However, from the perspective of preventing global warming, it is desirable to use a refrigerant with a low GWP (global warming potential). For example, the following refrigerants can be used as refrigerants with a low GWP:

[0129] (1) First, a halogenated hydrocarbon having a carbon-carbon double bond in its composition, such as HFO (Hydro-Fluoro-Orefin)-1234yf (CF ３ CF=CH ２ ) can be used. The GWP of HFO-1234yf is 4. (2) Alternatively, a hydrocarbon having a carbon-carbon double bond in its composition, such as R1270 (propylene), may be used. The GWP of R1270 is 3, which is lower than that of HFO-1234yf, but its flammability is higher than that of HFO-1234yf. (3) Alternatively, a mixture containing at least one halogenated hydrocarbon having a carbon-carbon double bond in its composition or a hydrocarbon having a carbon-carbon double bond in its composition, such as a mixture of HFO-1234yf and R32, may be used. The above-mentioned HFO-1234yf is a low-pressure refrigerant and therefore tends to cause large pressure loss, which may lead to a decrease in the performance of the refrigeration cycle (especially the evaporator). Therefore, it is practically desirable to use a mixture of HFO-1234yf with R32 or R41, which are higher-pressure refrigerants than HFO-1234yf.

[0130] The operation of the compressor 300 is as follows: Refrigerant gas supplied from the accumulator 310 is supplied through the suction pipe 313 into the cylinder chamber 303 of the cylinder 302. When the motor 5 is driven by supplying current to the coil 35, the shaft 25 rotates together with the rotor 1. Then, the rolling piston 304 fitted to the shaft 25 rotates eccentrically within the cylinder chamber 303, compressing the refrigerant within the cylinder chamber 303.

[0131] The refrigerant compressed in the cylinder chamber 303 passes through discharge mufflers 308 and 309, and then passes through the groove 30c of the stator 3 (FIG. 1) and the air gap between the rotor 1 and the refrigerant, and rises inside the sealed container 307. The refrigerant that has risen inside the sealed container 307 is discharged from a discharge pipe 312 and supplied to the high-pressure side of the refrigeration cycle.

[0132] This compressor 300 has the motor 5 described in the first embodiment, and thus is capable of stable operation over a long period of time by suppressing demagnetization of the permanent magnets 20. This improves the operational reliability of the compressor 300. The motor is not limited to the motor described in the first embodiment, and motors equipped with the rotors described in the second to fourth embodiments may also be used.

[0133] <Refrigeration cycle device> Next, a refrigeration cycle device 400 having the compressor 300 shown in Fig. 10 will be described. Fig. 11 is a diagram showing the refrigeration cycle device 400. The refrigeration cycle device 400 is, for example, an air conditioner, but is not limited to this and may be, for example, a refrigerator.

[0134] 11 includes a compressor 401, a condenser 402 that condenses a refrigerant, a pressure reducing device 403 that reduces the pressure of the refrigerant, and an evaporator 404 that evaporates the refrigerant. The compressor 401, the condenser 402, and the pressure reducing device 403 are provided in an outdoor unit 410, and the evaporator 404 is provided in an indoor unit 420.

[0135] The compressor 401, the condenser 402, the pressure reducing device 403, and the evaporator 404 are connected by refrigerant piping 407 to form a refrigerant circuit. The compressor 401 is configured as the compressor 300 shown in Fig. 10. The refrigeration cycle device 400 also includes an outdoor fan 405 facing the condenser 402 and an indoor fan 406 facing the evaporator 404.

[0136] The refrigeration cycle apparatus 400 operates as follows: The compressor 401 compresses the refrigerant it draws in and sends it out as high-temperature, high-pressure refrigerant gas. The condenser 402 exchanges heat between the refrigerant sent out from the compressor 401 and outdoor air sent by the outdoor air blower 405, condenses the refrigerant, and sends it out as liquid refrigerant. The pressure reducing device 403 expands the liquid refrigerant sent out from the condenser 402 and sends it out as low-temperature, low-pressure liquid refrigerant.

[0137] The evaporator 404 exchanges heat between the low-temperature, low-pressure liquid refrigerant sent from the pressure reducing device 403 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 404 is supplied by the indoor fan 406 into the room, which is the space to be air-conditioned.

[0138] The compressor 401 of the refrigeration cycle apparatus 400 has the motor 5 of the first embodiment, and is capable of stable operation over a long period of time, thereby improving the reliability of operation of the refrigeration cycle apparatus 400. The compressor 401 is not limited to the motor described in the first embodiment, and a motor having a rotor described in any of the second to fourth embodiments may also be used.

[0139] 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.

[0140] DESCRIPTION OF SYMBOLS 1, 1A, 1B, 1C Rotor, 3 Stator, 5 Motor, 10 Rotor core, 11 Magnet insertion hole, 13 Center hole, 14 Outer periphery, 15 Rib (first rib), 16 Rib (second rib), 20 Permanent magnet, 25 Shaft, 30 Stator core, 31 Yoke, 32 Teeth, 33 Slot, 34 Insulating portion, 35 Coil, 51 Inner peripheral edge, 52 Outer peripheral edge, 53, 53a, 53b Side edge, 61 Inner peripheral edge, 62 Outer peripheral edge, 63 Side edge, 101 First core portion, 102 Second core portion, 300 Compressor, 301 Compression mechanism, 302 Cylinder, 307 Sealed container, 400 Refrigeration cycle device, 401 compressor, 402 condenser, 403 pressure reducing device, 404 evaporator, A, A1 to A6 gaps (first gaps), B, B1 to B6 gaps (second gaps), P magnetic pole center line, S1 first side, S2 second side, T reference plane.

Claims

1. 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 made of a rare earth magnet placed 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 2 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 2 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; a first rib is formed between two adjacent first voids among the m first voids; a second rib is formed between two adjacent second voids among the n second voids; The width D1 of the first rib in the circumferential direction and the width D2 of the second rib in the circumferential direction satisfy D1≧D2. Rotor.

2. The width W1 in the radial direction of at least one first gap among the m number of first gaps and the width W2 in the radial direction of at least one second gap among the n number of second gaps satisfy W1≧W2. The rotor of claim 1 .

3. The m first voids are a first gap formed asymmetrically with respect to a line passing through the rotation axis and dividing the gap area in half on a plane perpendicular to the rotation axis; Contains The rotor of claim 1 .

4. The m first voids are: a first gap formed asymmetrically with respect to a line passing through the rotation axis and dividing the gap area in half on a plane perpendicular to the rotation axis; Contains The rotor of claim 2 .

5. a first rib is formed between two adjacent first voids among the m first voids; The circumferential width of the first rib is wider at an outer end in the radial direction than at an inner end in the radial direction of the first rib. The rotor of claim 1 .

6. A first rib is formed between two adjacent first voids among the m first voids, The circumferential width of the first rib is wider at an outer end in the radial direction than at an inner end in the radial direction of the first rib. The rotor of claim 2 .

7. A shortest distance R1 from the rotation axis to the m first gaps and a shortest distance R2 from the rotation axis to the n second gaps satisfy R1≧R2. A rotor according to any one of claims 1 to 6.

8. the rotor core has a first core portion and a second core portion in the axial direction of the rotation shaft, the first gap of the first core portion and the second gap of the second core portion are continuous in the axial direction, The second gap of the first core portion and the first gap of the second core portion are continuous in the axial direction. A rotor according to any one of claims 1 to 6.

9. The electromagnetic steel sheet constituting the second core portion is located at a position rotated about the rotation axis relative to the electromagnetic steel sheet constituting the first core portion. The rotor of claim 8 .

10. the rotor core has k magnet insertion holes (k is an integer of 2 or more), The first gap or the second gap is disposed so as to face the center of each of the k magnet insertion holes in the circumferential direction. A rotor according to any one of claims 1 to 6.

11. A rotor according to any one of claims 1 to 6; a stator surrounding the rotor; Equipped with Motor.

12. a motor according to claim 11; a compression mechanism driven by the motor; A compressor equipped with

13. A compressor comprising the compressor according to claim 12, a condenser, a pressure reducing device, and an evaporator. Refrigeration cycle equipment.