Permanent magnet type rotary motor and compressor using the same

Abstract

To provide a permanent magnet rotary motor and a compressor using the same, which can reduce costs while ensuring the performance of the electric motor and suppress the generation of noise due to the whistling phenomenon. [Solution] The permanent magnet rotary motor 100 comprises a rotor 10 having a rotor core 13 having a plurality of magnet insertion holes 13c, a permanent magnet 11 and a pair of end plates 16 made of magnetic material. The rotor core 13 comprises a recess 12 provided between two adjacent magnet insertion holes 13c, and a pair of slits 13a, 13a provided radially outside the magnet insertion holes 13c and spaced apart in the circumferential direction. At least one of the pair of end plates 16 comprises a cover portion 16a that covers the axial outer ends of the recess 12 and the pair of slits 13a, 13a, and a notch portion 16b positioned between the pair of slits 13a, 13a. The notch portion 16b extends to a position that overlaps with at least the permanent magnet 11 in an axial view.

Description

Technical Field

[0005] , ,

[0001] The present disclosure relates to a permanent magnet type rotating electric motor and a compressor using the same.

Background Art

[0002] In recent years, with the rapid climate change on a global scale, reduction of environmental load has been strongly demanded, and reduction of energy consumption has become an important issue also in the industrial field. In particular, in a compressor used in a refrigeration cycle device, improvement of the efficiency of an electric motor as a drive source has been strongly promoted, and the demand for reduction of power consumption has been increasing year by year.

[0003] Under such circumstances, in order to maintain the competitiveness of products, cost reduction is also required in parallel. As means for reducing the cost of an electric motor, review of constituent materials and simplification of component specifications can be cited, but it is not allowed that the performance of the compressor deteriorates due to these changes.

[0004] Under such a background, as a technique for reducing cost while maintaining the performance of an electric motor, attempts have been made to devise the structure of a rotor. For example, Patent Document 1 discloses a rotor including a rotor core formed of a cylindrical magnetic material having a magnet accommodating portion formed of a through hole or a notch penetrating in the axial direction, and end plates provided at axial end portions of the rotor core. The end plates are formed of a magnetic material. Thereby, cost reduction is achieved by making the end plates of a magnetic material. [[ID=二十一]] [[ID=二十二]]

[0005] [[ID=二十三]] [[ID=二十四]]Further, in the rotor of Patent Document 1, the rotor core is close to the magnet accommodating portion and includes a non-magnetic space formed of a through hole or a notch penetrating in the axial direction, and the end plates include openings overlapping the non-magnetic space in the axial direction. Thereby, leakage of magnetic flux to adjacent magnetic poles can be suppressed by the non-magnetic spaces provided in the rotor core and the end plates, and improvement of the magnetic characteristics of the rotor is achieved. As a result, cost reduction can be achieved while maintaining the efficiency of the electric motor. [[ID=二十五]] [[ID=二十六]]

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-150458 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, when the rotor rotates at high speed due to the electric motor drive, and the compressed fluid inside the compressor moves at high speed in the axial direction, there is a risk of noise being generated due to a whistling phenomenon as the compressed fluid passes through non-magnetic spaces composed of through holes or notches that penetrate in the axial direction.

[0008] The purpose of this disclosure is to provide a permanent magnet rotary motor and a compressor using the same, which can reduce costs while ensuring the performance of the motor and suppress the generation of noise due to the whistling phenomenon. [Means for solving the problem]

[0009] The scroll compressor of this disclosure is A stator having a yoke and a plurality of teeth extending radially inward from the yoke and around which armature windings are wound, The rotor comprises a rotor core having a plurality of magnet insertion holes near its outer surface, a plurality of plate-shaped permanent magnets inserted into the plurality of magnet insertion holes, and a pair of end plates made of magnetic material provided on both axially outer sides of the rotor core. The rotor core comprises a recess provided between two adjacent magnet insertion holes, and a pair of slits provided radially outside the magnet insertion holes and spaced apart in the circumferential direction, At least one of the pair of end plates comprises a cover portion that covers the axial outer ends of the recess and the pair of slits, and a notch portion positioned between the pair of slits. The notch extends to a position that overlaps with the permanent magnet in an axial view. [Brief explanation of the drawing]

[0010] [Figure 1] A cross-sectional view of a permanent magnet rotary motor in one embodiment, cut by a plane perpendicular to its axis of rotation. [Figure 2] Enlarged view showing the area near the outer core of the rotor in Figure 1. [Figure 3] Plan view showing the end plate of the permanent magnet rotary motor in the same embodiment. [Figure 4] Plan view showing a permanent magnet rotary motor in the same embodiment. [Figure 5] Cross-sectional view of a compressor equipped with a permanent magnet rotary motor in the same embodiment. [Figure 6] Plan view showing a permanent magnet rotary motor in another embodiment. [Modes for carrying out the invention]

[0011] A permanent magnet type rotary motor 100 (hereinafter simply referred to as motor 100) according to one embodiment will be described with reference to Figures 1 to 5. Note that in each figure (and also in Figure 6), the dimensional ratios in the drawings do not necessarily match the actual dimensional ratios, and the dimensional ratios between the drawings do not necessarily match either. Figure 1 is a cross-sectional view of the motor 100 cut with a plane perpendicular to its rotation axis. Figure 2 is an enlarged view showing the vicinity of the outer core portion 13D of the rotor 10 in Figure 1.

[0012] As shown in Figure 1, the electric motor 100 comprises a stator 1 and a rotor 10. The stator 1 has a cylindrical yoke 6 and a plurality of teeth 3, and the plurality of teeth 3 form a plurality of slot portions 2. An armature winding (not shown) is wound around each tooth 3 and arranged in the slot portion 2.

[0013] The rotor 10 is composed of a rotor core 13 and a plurality (e.g., six) of permanent magnets 11. The rotor core 13 has a plurality of magnet insertion holes 13c. The magnet insertion holes 13c are formed near the outer peripheral surface of the rotor core 13 and penetrate the rotor core 13 in the axial direction. Near the outer peripheral surface means, for example, that they are located radially outside 70% of the outer diameter of the rotor core 13. In an axial view of the rotor core 13, the magnet insertion holes 13c extend linearly along the circumferential direction. The plurality of magnet insertion holes 13c are arranged at equal intervals along the circumferential direction.

[0014] Each magnet insertion hole 13c has a plate-shaped permanent magnet 11 inserted into it. For example, one permanent magnet 11 is inserted into one magnet insertion hole 13c. The magnetic poles of the rotor 10 are formed by the permanent magnets 11.

[0015] The rotor core 13 includes a recess 12 provided between two adjacent magnet insertion holes 13c (permanent magnets 11). The recess 12 is recessed from the outer surface of the rotor core 13 to a virtual straight line connecting the two adjacent magnet insertion holes 13c (permanent magnets 11). This prevents short circuits of the field flux between adjacent permanent magnets 11. Preferably, the virtual straight line is a straight line connecting the inner surfaces of the two adjacent magnet insertion holes 13c.

[0016] The rotor core 13 is provided with at least one (for example, six) recesses 12. The recesses 12 extend along the axial direction of the rotor core 13. Preferably, the number of recesses 12 is the same as the number of magnet insertion holes 13c (permanent magnets 11). The recesses 12 penetrate the rotor core 13 in the axial direction.

[0017] The rotor core 13 is provided with a pair of slits 13a, 13a located radially outward from the magnet insertion hole 13c (permanent magnet 11). The pair of slits 13a, 13a are provided in the outer core portion 13D located on the outer diameter side of the magnet insertion hole 13c (permanent magnet 11). Slit 13a extends along the axial direction of the rotor core 13. Slit 13a penetrates the rotor core 13 in the axial direction.

[0018] The pair of slits 13a, 13a are arranged at intervals in the circumferential direction, and are provided at the respective ends 13D1 (see FIG. 2) of the outer core portion 13D located on the outer diameter side of both ends in the width direction of the permanent magnet 11, for example. Only one slit 13a is formed at each end 13D1. In the outer core portion 13D, a central portion 13D2 (see FIG. 2) located between the pair of ends 13D1 is solid. Thereby, further prevention of the short-circuit of the field magnetic flux can be achieved, the magnetic flux distribution can be smoothed, and the armature reaction can be reduced. As a result, the efficiency of the motor 100 can be improved. Also, by adopting a simple configuration, many precision cutting tools are not required during the manufacture of the rotor core 13, and the formability of the rotor core 13 can be easily maintained.

[0019] As shown in FIGS. 1 and 2, the tooth 3 includes a tooth base portion 7 extending radially inward from the yoke 6, and a tooth arc portion 4 provided on the tip side of the tooth base portion 7 and extending along the circumferential direction.

[0020] The tooth arc portion 4 includes a tooth central portion 8 whose inner peripheral surface is arc-shaped, and a pair of tooth enlarged portions 5. The pair of tooth enlarged portions 5 are located at both ends in the circumferential direction of the tooth central portion 8. The distance between each tooth enlarged portion 5 and the outer core portion 13D is configured to be larger than the distance between the tooth central portion 8 and the outer core portion 13D. In the present embodiment, the inner surface of the tooth enlarged portion 5 is configured such that the distance from the outer core portion 13D increases as it goes toward the outside in the circumferential direction. That is, the inner surface of the tooth enlarged portion 5 is located radially outside the inner surface of the tooth central portion 8.

[0021] In a configuration where the teeth 3 and the outer core portion 13D are aligned radially, one tooth enlargement portion 5 of the tooth arc portion 4 faces one slit 13a of the outer core portion 13D, and the other tooth enlargement portion 5 of the tooth arc portion 4 faces the other slit 13a of the outer core portion 13D. This prevents the field magnetic flux from concentrating at the circumferential end of the tooth arc portion 4, thereby smoothing the magnetic flux distribution and keeping torque fluctuations low. In other words, with only the combination of the recess 12 and the slit 13a, the field magnetic flux may concentrate at the circumferential end of the tooth arc portion 4, making it difficult for the magnetic flux distribution to change smoothly and potentially leading to large torque fluctuations, but this can be prevented.

[0022] As shown in Figure 2, the outer core portion 13D of the rotor 10 has a rotor arc portion 14 and a pair of rotor enlargements 15 at its radially outer end. The outer circumferential surface of the rotor arc portion 14 facing the teeth 3 is arc-shaped. Each rotor enlargement 15 is located between the slit 13a and the recess 12. The distance between each rotor enlargement 15 and the teeth arc portion 4 is greater than the distance between the rotor arc portion 14 and the teeth arc portion 4. This further smooths the magnetic flux distribution and reduces torque fluctuations. In this embodiment, the outer surface of the rotor enlargement 15 is configured such that the distance from the teeth arc portion 4 increases as it moves outward in the circumferential direction. That is, the outer surface of the rotor enlargement 15 is located radially inward from the outer surface of the rotor arc portion 14.

[0023] Figure 3 is a plan view showing the end plates 16 of the electric motor 100, and Figure 4 is a plan view showing the electric motor 100. As shown in Figures 3 and 4, the electric motor 100 is provided with a pair of end plates 16 made of magnetic material, which are provided on both axially outer sides of the rotor core 13. By forming the end plates 16 from a magnetic material, cost reduction can be achieved compared to when they are formed from non-magnetic materials such as SUS300 series or aluminum. Examples of magnetic materials include iron, silicon steel, and ferrite. The end plates 16 may be made from the same material as the rotor core 13, or from a different material than the rotor core 13.

[0024] The end plates 16 are in contact with the axial outer end of the rotor core 13, and the pair of end plates 16 are positioned to sandwich the rotor core 13. The pair of end plates 16 hold the permanent magnet 11 inserted into the magnet insertion hole 13c.

[0025] At least one of the pair of end plates 16 is provided with a cover portion 16a that covers the axial outer ends (through spaces) of the recess 12 and the pair of slits 13a. The cover portion 16a is positioned to overlap with the recess 12 and the pair of slits 13a in an axial view. This prevents the compressed fluid from passing through the recess 12 and the slits 13a, thereby suppressing noise caused by the whistling phenomenon. In this embodiment, a cover portion 16a is provided on each of the pair of end plates 16. However, the cover portion 16a may be provided only on the other end plate. The one end plate 16 may be the upper end plate 16 or the lower end plate 16 that is arranged in the compressor 200 described later (see Figure 5).

[0026] The statement that the cover portion 16a covers the axial outer ends (through spaces) of the recess 12 and the pair of slits 13a does not mean only when the cover portion 16a completely covers the recess 12 and the pair of slits 13a, but also includes cases where each part is slightly exposed. In this embodiment, the cover portion 16a covers the widthwise end of the permanent magnet 11 and the end 13D1 of the outer core portion 13D. By covering the widthwise end of the permanent magnet 11 with the cover portion 16a, for example, the permanent magnet 11 can be held. By covering the end 13D1 of the outer core portion 13D with the cover portion 16a, the strength of the end plate 16 can be increased.

[0027] At least one of the pair of end plates 16 is provided with a notch 16b located between a pair of slits 13a. In an axial view, the notch 16b extends at least from the outer edge of the end plate 16 to a position overlapping with the permanent magnet 11. This reduces the contact area between the permanent magnet 11 and the end plate 16 by exposing a portion of the permanent magnet 11, thereby suppressing leakage flux toward adjacent permanent magnets 11 via the end plate 16 and improving the performance of the electric motor 100. This reduces costs while ensuring the performance of the electric motor 100 and suppresses the generation of noise due to the whistling phenomenon. In this embodiment, the notch 16b is provided on each of the pair of end plates 16. The notch 16b may be provided only on the other end plate.

[0028] The width (maximum width) of the notch 16b along the circumferential direction is smaller than the spacing between the pair of slits 13a, 13a. Preferably, the width (maximum width) of the notch 16b is 80% or more of the spacing between the pair of slits 13a, 13a, and more preferably 90% or more. Preferably, the circumferential center of the notch 16b substantially coincides with the circumferential center of the central portion 13D2 of the outer core portion 13D.

[0029] The notch 16b is preferably formed in a rectangular shape (for example, a rectangle) when viewed in the axial direction. However, the notch 16b may also be formed in a polygonal shape such as a triangle, pentagon, or hexagon, a semicircle, or an elongated hole when viewed in the axial direction.

[0030] Preferably, the notch 16b extends radially inward beyond the permanent magnet 11. Preferably, the notch 16b exposes the permanent magnet 11 from its outer diameter side to its inner diameter side. Preferably, the minimum distance from the center of the end plate 16 to the notch 16b is smaller than the minimum distance from the center of the rotor core 13 to the permanent magnet 11. With such a configuration, the adjacent portion between the permanent magnet 11 and the end plate 16 can be further reduced, and leakage flux toward adjacent permanent magnets 11 via the end plate 16 and leakage flux generated on the front and back surfaces of the permanent magnet 11 can be suppressed, thereby further improving the performance of the electric motor 100. In this embodiment, the notch 16b extends radially inward beyond the magnet insertion hole 13c, but is not limited to this.

[0031] Figure 5 shows a cross-sectional view of a compressor 200 equipped with an electric motor 100. As shown in Figure 5, the compressor 200 comprises a cylindrical case 203 that also serves as a pressure vessel, an electric motor 100, a drive shaft 202, and a compression mechanism 201.

[0032] The stator 1 is supported by the case 203. A drive shaft 202 is attached to the rotor 10. The drive shaft 202 is rotatably supported by the case 203. The compression mechanism 201 is a scroll-type compression mechanism. In the compressor 200, the rotation of the rotor 10 is transmitted to the compression mechanism 201 via the drive shaft 202, where the gas is compressed, and the compressed gas is discharged outside the case 203.

[0033] Thus, since the torque of the electric motor 100 is directly transmitted to the compression mechanism 201 via the drive shaft 202, torque fluctuations of the electric motor 100 cause vibration and noise throughout the compressor 200. However, by equipping the compressor 200 with the electric motor 100 that reduces torque fluctuations as in this embodiment, and by driving the compression mechanism 201 with the electric motor 100, the efficiency of the compressor 200 can be improved and vibration and noise can be reduced.

[0034] (modified version) In the above embodiment, the electric motor 100 had 6 poles and 9 slots, but the number of magnetic poles and slots are not limited to these. Also, the inner surface of the tooth enlargement portion 5 was configured such that the distance from the outer core portion 13D increases as it moves outward in the circumferential direction, but this is not limited to this configuration. It is sufficient that the distance between each tooth enlargement portion 5 and the outer core portion 13D is greater than the distance between the tooth center portion 8 and the outer core portion 13D, and the inner surface of the tooth enlargement portion 5 may maintain a constant distance from the outer core portion 13D along the circumferential direction.

[0035] In the above embodiment, the outer surface of the rotor enlargement portion 15 was configured such that the distance from the tooth arc portion 4 increases as it moves outward in the circumferential direction, but it is not limited to this. The distance between each rotor enlargement portion 15 and the tooth arc portion 4 only needs to be greater than the distance between the rotor arc portion 14 and the tooth arc portion 4, and the outer surface of the rotor enlargement portion 15 may have a constant distance from the tooth arc portion 4 along the circumferential direction.

[0036] In the above embodiment, the cover portion 16a covers the widthwise end of the permanent magnet 11 and the end portion 13D1 of the outer core portion 13D, but is not limited to this. For example, as shown in Figure 6, the end plate 16 may have a pair of second notches 16c, 16c, and the widthwise end of the permanent magnet 11 and the end portion 13D1 of the outer core portion 13D may be exposed. In such an example, by further exposing the permanent magnet 11, leakage magnetic flux toward adjacent permanent magnets 11 via the end plate 16 can be suppressed, thereby improving the performance of the electric motor 100.

[0037] [1] As described above, the permanent magnet rotary motor 100 comprises a stator 1 having a yoke 6 and a plurality of teeth 3 extending radially inward from the yoke 6 around which the armature winding is wound, a rotor 10 having a rotor core 13 having a plurality of magnet insertion holes 13c near its outer surface, a plurality of plate-shaped permanent magnets 11 inserted into the plurality of magnet insertion holes 13c, and a pair of end plates 16 made of magnetic material provided on both axially outer sides of the rotor core 13, and the rotor core 13 has two adjacent magnets The magnet insertion hole 13c comprises a recess 12 provided between the insertion holes 13c and a pair of slits 13a, 13a provided radially outside the magnet insertion hole 13c and spaced apart in the circumferential direction. At least one of the pair of end plates 16 has a cover portion 16a that covers the axial outer ends of the recess 12 and the pair of slits 13a, 13a, and a notch portion 16b positioned between the pair of slits 13a, 13a, the notch portion 16b extending to a position that overlaps with at least the permanent magnet 11 in an axial view.

[0038] With this configuration, by exposing a portion of the permanent magnet 11, the contact area between the permanent magnet 11 and the end plate 16 is reduced, and leakage magnetic flux toward adjacent permanent magnets 11 via the end plate 16 is suppressed, thereby improving the performance of the electric motor 100. Furthermore, by forming the end plate 16 from a magnetic material, costs can be reduced. In addition, since the end plate 16 is equipped with a cover portion 16a that covers the outer axial ends of the recess 12 and the pair of slits 13a, compressed fluid is prevented from passing through the recess 12 and slits 13a, thereby suppressing noise caused by the whistling phenomenon. As a result, costs can be reduced while ensuring the performance of the electric motor 100, and the generation of noise caused by the whistling phenomenon can be suppressed.

[0039] [2] In the permanent magnet type rotary motor 100 described in [1] above, it is preferable that the notch 16b extends radially inward beyond the permanent magnet 11.

[0040] With this configuration, the adjacent area between the permanent magnet 11 and the end plate 16 can be further reduced, and leakage flux toward adjacent permanent magnets 11 via the end plate 16 and leakage flux generated on the front and back surfaces of the permanent magnet 11 can be suppressed, thereby further improving the performance of the electric motor 100.

[0041] [3] The compressor 200 comprises the permanent magnet type rotary motor 100 described in [1] or [2] above, and a compression mechanism 201 driven by the permanent magnet type rotary motor 100.

[0042] It should be noted that the permanent magnet type rotary motor and compressor are not limited to the configuration of the embodiments described above, nor are they limited to the effects described above. Furthermore, it goes without saying that the permanent magnet type rotary motor and compressor can be modified in various ways without departing from the spirit of the present invention. For example, one or more of the configurations and methods related to the various modifications described above may be arbitrarily selected and adopted in the configurations and methods of the embodiments described above. [Explanation of symbols]

[0043] 1...Stator, 2...Slot section, 3...Teeth, 4...Teeth arc section, 5...Teeth enlargement section, 6...Yoke, 7...Teeth base, 8...Teeth center section, 10...Rotor, 11...Permanent magnet, 12...Recess, 13...Rotor core, 13D...Outer core section, 13D1...End section, 13D2...Center section, 13a...Slit, 13c...Magnet insertion hole, 14...Rotor arc section, 15...Rotor enlargement section, 16...End plate, 16a...Cover section, 16b...Notch section, 16c...Second notch section, 100...Permanent magnet rotary motor (motor), 200...Compressor, 201...Compression mechanism section, 202...Drive shaft, 203...Case

Claims

1. A stator having a yoke and a plurality of teeth extending radially inward from the yoke and around which armature windings are wound, The rotor comprises a rotor core having a plurality of magnet insertion holes near its outer surface, a plurality of plate-shaped permanent magnets inserted into the plurality of magnet insertion holes, and a pair of end plates made of magnetic material provided on both axially outer sides of the rotor core. The rotor core comprises a recess provided between two adjacent magnet insertion holes, and a pair of slits provided radially outside the magnet insertion holes and spaced apart in the circumferential direction, At least one of the pair of end plates comprises a cover portion that covers the axial outer ends of the recess and the pair of slits, and a notch portion positioned between the pair of slits. A permanent magnet type rotary motor, wherein the notch extends to a position that overlaps with the permanent magnet in an axial view.

2. The permanent magnet type rotary motor according to claim 1, wherein the notch extends radially inward from the permanent magnet.

3. A permanent magnet type rotary motor according to claim 1 or 2, A compressor comprising a compression mechanism driven by the aforementioned permanent magnet rotary motor.

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