Rotor core, rotor, motor and compressor

Abstract

The utility model discloses a rotor iron core, a rotor, a motor and a compressor, and relates to the technical field of motors, and the rotor iron core comprises a plurality of rotor punching sheets which are laminated along the axial direction of the rotor iron core; the rotor punching sheet comprises a plurality of mounting grooves arranged along the circumferential direction of the rotor punching sheet, the inner side of each mounting groove is provided with a plurality of circulation holes, at least part of the circulation holes are communicated with at least part of the mounting grooves through first passages, and the circulation holes and the first passages are arranged on the center lines of the corresponding mounting grooves; according to the technical scheme provided by the utility model, the loss of the rotor iron core can be reduced so as to improve the motor efficiency.

Description

Technical Field

[0001] The utility model relates to the technical field of motors, and particularly to a rotor core, a rotor, a motor and a compressor. Background Art

[0002] The motor is the core part of the compressor, and its energy consumption directly affects the operation efficiency and service life of the compressor. However, the motor design of traditional compressors has relatively high losses, especially under high-load working conditions, and the losses are more significant, thus reducing the motor efficiency. Summary of the Utility Model

[0003] The main purpose of the utility model is to provide a rotor core, a rotor, a motor and a compressor, aiming to reduce the loss of the rotor core so as to improve the motor efficiency.

[0004] To achieve the above object, the rotor core proposed by the utility model comprises a plurality of rotor punching sheets stacked along its axial direction;

[0005] The rotor punching sheet comprises a plurality of mounting grooves arranged along its circumferential direction. A plurality of circulation holes are arranged inside the mounting grooves. At least part of the circulation holes are communicated with at least part of the mounting grooves through a first passage. The circulation holes and the first passage are arranged on the center line of the corresponding mounting groove.

[0006] In an embodiment, the width of the first passage at the mounting groove is d1, and the width of the first passage at the circulation hole is d2, and d1≤d2.

[0007] In an embodiment, the number of pole pairs of the rotor core is P, and the number of the first passages is K, and K = P; or K = 2P.

[0008] In an embodiment, the number of the first passages on the plurality of rotor punching sheets is the same.

[0009] In an embodiment, the plurality of rotor punching sheets at least comprise a first punching sheet and a second punching sheet stacked along the axial direction of the rotor core, and the number of the first passages on the first punching sheet is less than the number of the first passages on the second punching sheet.

[0010] In an embodiment, there are a plurality of the first punching sheets, and at least one of the first punching sheets is arranged at each end of the rotor core, and the second punching sheet is located between the two first punching sheets respectively arranged at the two ends of the rotor core.

[0011] In an embodiment, the number of the first punching sheets is 2N1, and the number of the second punching sheets is N2, and 0.5≤N2 / N1≤8.

[0012] In one embodiment, a plurality of the second punching sheets are provided and arranged between the two first punching sheets disposed at both ends of the rotor core.

[0013] In one embodiment, the rotor core further includes a punching sheet assembly and the first punching sheet disposed at the end of the punching sheet assembly;

[0014] The punching sheet assembly includes the first punching sheet and the second punching sheet stacked together, and the number of the first punching sheets at the end of the punching sheet assembly is equal to the number of the first punching sheets within the punching sheet assembly.

[0015] In one embodiment, within the punching sheet assembly, one first punching sheet and one second punching sheet are provided respectively;

[0016] Alternatively, within the punching sheet assembly, a plurality of first punching sheets and a plurality of second punching sheets are provided respectively.

[0017] In one embodiment, a plurality of groups of the punching sheet assemblies are provided.

[0018] In one embodiment, the installation groove includes a first groove section parallel to the radial direction of the rotor core and two second groove sections connected to opposite sides of the first groove section, and the circulation hole communicates with the first groove section.

[0019] In one embodiment, a first permanent magnet is installed in the first groove section, and the length of the first permanent magnet is Lm1, a second permanent magnet is installed in the second groove section, and the length of the second permanent magnet is Lm2, and 1.02 ≤ Lm1 / Lm2 ≤ 1.3.

[0020] In one embodiment, an air groove is provided on the rotor punching sheet between two adjacent installation grooves, and the area of the air groove is S, and 3 ≤ S ≤ 3.9.

[0021] The present utility model further provides a rotor, which includes the rotor core as described above.

[0022] The present utility model further provides a motor, which includes the rotor as described above.

[0023] The present utility model further provides a compressor, which includes the motor as described above.

[0024] In the technical solution of the present utility model, at least part of the installation grooves and at least part of the circulation holes are communicated through a first passage, so as to adjust the magnetic field saturation phenomenon between the installation grooves and the circulation holes, reduce the magnetic leakage at this position, reduce the magnetic resistance and magnetic flux loss, and at the same time, effectively ensure the structural strength of the rotor core, thereby improving the motor efficiency. Description of the Drawings

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0026] Figure 1 It is a schematic structural diagram of a rotor punching sheet of a rotor core provided by the present invention;

[0027] Figure 2 It is a schematic structural diagram of another embodiment of the rotor punching sheet provided by the present invention;

[0028] Figure 3 It is a schematic structural diagram of an embodiment of a first punching sheet and a second punching sheet stacked provided by the present invention;

[0029] Figure 4 It is a schematic structural diagram of another embodiment of the first punching sheet and the second punching sheet stacked provided by the present invention.

[0030] Explanation of the reference numerals in the drawings:

[0031] 100, rotor core; 11, rotor punching sheet; 111, first passage; 113, first punching sheet; 114, second punching sheet; 12, flow hole; 13, installation groove; 131, first groove section; 132, second groove section; 14, air groove; 15, punching sheet combination.

[0032] The realization, functional features and advantages of the object of the present invention will be further described with reference to the embodiments and the drawings. Detailed Embodiments

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0034] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present invention, the directional indications are only used to explain the relative position relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0035] In addition, if the embodiments of the present utility model involve descriptions such as "first", "second", etc., the descriptions of "first", "second", etc. are only for descriptive purposes and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel scenarios. Taking "A and / or B" as an example, it includes Scenario A, or Scenario B, or the scenario where both A and B are satisfied simultaneously. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or is unable to be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0036] The motor is the core part of the compressor, and its energy consumption directly affects the operating efficiency and service life of the compressor; however, the motor design of traditional compressors has relatively high losses, especially under high-load working conditions, and the losses are more significant, thus reducing the motor efficiency.

[0037] To solve this technical problem, the present utility model proposes a rotor core 100.

[0038] Please refer to Figures 1 to 4 , in an embodiment of the present utility model, the rotor core 100 includes a plurality of rotor punching sheets 11 stacked along its axial direction; the rotor punching sheets 11 include a plurality of mounting grooves 13 arranged along its circumferential direction, and a plurality of flow holes 12 are provided inside the mounting grooves 13. At least part of the flow holes 12 are connected to at least part of the mounting grooves 13 through a first passage 111, and the flow holes 12 and the first passage 111 are arranged on the center line of the corresponding mounting groove 13; the loss of the rotor core 100 is reduced to improve the motor efficiency.

[0039] In the technical solution of the present utility model, at least part of the mounting grooves 13 and at least part of the flow holes 12 are connected through the first passage 111 to adjust the magnetic field saturation phenomenon between the mounting grooves 13 and the flow holes 12, reduce the magnetic leakage at this position, reduce the magnetic resistance and magnetic flux loss, and at the same time, effectively ensure the structural strength of the rotor core 100, thereby improving the motor efficiency.

[0040] Specifically, the circulation hole 12, the installation groove 13, and the first passage 111 connecting the circulation hole 12 and the installation groove 13 are located on the same center line, which is the center line of the installation groove 13 connected by the first passage 111, so as to ensure the uniform distribution of the magnetic field on the rotor core 100. Among them, the installation groove 13 is used to fix the permanent magnet, the circulation hole 12 is used to reduce the weight of the rotor core 100 and improve the heat dissipation effect of the rotor core 100, and can also optimize the magnetic circuit of the rotor core 100 to a certain extent. The setting of the first passage 111 can further reduce the weight of the rotor core 100, and its number is specifically associated with the number of poles of the rotor core 100 and is also related to the loss of the rotor core 100, that is, it can be set according to the specific number of poles and the required loss reduction on the basis of ensuring the structural strength of the rotor core 100.

[0041] Please refer to Figure 1 , in the embodiment of the present invention, the width of the first passage 111 at the installation groove 13 is d1, and the width of the first passage 111 at the circulation hole 12 is d2, and d1 ≤ d2. With this setting, on the basis of ensuring the connection effect of the first passage 111 on the installation groove 13 and the circulation hole 12, the reliable assembly of the permanent magnet in the installation groove 13 is ensured. At the same time, it is avoided that the leakage magnetic flux increases due to the too large width of the first passage 111 at the installation groove 13, which helps to reduce the loss, ensure the normal output torque of the motor, and improve the motor efficiency.

[0042] Specifically, in an embodiment of the present invention, the number of pole pairs of the rotor core 100 is P, and the number of the first passages 111 is K, and K = P; as Figure 1 shown, the number of poles of the rotor is 6, and the number of pole pairs is 3. At this time, 6 installation grooves 13 are provided, and the number of the first passages 111 is 3. Among them, the three first passages 111 are evenly spaced along the circumferential direction of the rotor core 100, which improves the structural stability of the rotor punching sheet 11. At the same time, it improves the leakage magnetic flux inside the installation groove 13 connected with the first passage 111, reduces the loss of the rotor core 100, and further enhances the efficiency improvement effect. The number of the circulation holes 12 can be greater than or equal to 3.

[0043] In another embodiment of the present invention, the number of pole pairs of the rotor core 100 is P, and the number of the first passages 111 is K, and K = 2P; as Figure 2As shown, the number of poles of the rotor is 6, and the number of pole pairs is 3. At this time, 6 installation grooves 13 are provided, and the number of the first passages 111 is 6. Among them, the 6 first passages 111 are evenly spaced along the circumferential direction of the rotor core 100 and correspond to the installation grooves 13 one by one, improving the structural stability of the rotor punching sheet 11. At the same time, the magnetic leakage inside the installation groove 13 connected to the first passage 111 is improved, the loss of the rotor core 100 is reduced, and the efficiency improvement effect is enhanced. The number of the circulation holes 12 is 6, which is convenient for enhancing the heat dissipation effect of the rotor core 100 and reducing the overall weight of the rotor core 100. The number of pole pairs of the rotor core 100 includes but is not limited to 3, 4, 5, and 6.

[0044] Optionally, in the embodiment of the present invention, the number of the first passages 111 on the multiple rotor punching sheets 11 is the same, which is convenient for accelerating the forming of the rotor core 100.

[0045] Among them, taking the case where the number of the first passages 111 is less than the number of the installation grooves 13 of the rotor punching sheet 11 as an example, the specific efficiency improvement ratio analysis is as follows in the following table:

[0046]

[0047] It can be seen that the "original motor" specifically refers to the motor that does not adopt the rotor punching sheet 11 with the first passage 111, and the "improved motor" refers to the motor that adopts the rotor punching sheet 11 with the first passage 111; for a specific rotational speed, compared with the original motor, the motor efficiency of the modified motor is significantly improved during operation, that is, through the structural improvement of the rotor punching sheet 11, the high stability and low loss characteristics of the rotor punching sheet 11 under high-speed operation can be realized, thereby significantly improving the motor efficiency.

[0048] Among them, the first passages 111 on two adjacent rotor punching sheets 11 can be at least partially staggered, which is convenient for enhancing the overall structural strength of the rotor core 100 and improving the motor efficiency. However, in other embodiments, only the installation grooves 13 on two adjacent rotor punching sheets 11 need to be butted to ensure the installation of the permanent magnet.

[0049] Please refer to Figure 3 and Figure 4, in the embodiment of the present utility model, the plurality of rotor punching sheets 11 at least include a first punching sheet 113 and a second punching sheet 114 laminated along the axial direction of the rotor core 100, and the number of the first passages 111 on the first punching sheet 113 is less than the number of the first passages 111 on the second punching sheet 114. In this way, it can not only ensure that the overall holding force of the formed rotor core 100 is relatively high, that is, it has better structural strength, but also reduce the loss of the rotor core 100 to a certain extent, reduce magnetic leakage, and thus improve the motor efficiency. However, in other embodiments, the rotor punching sheet 11 can be laminated with a punching sheet without the first passage 111 to form the rotor core 100.

[0050] Specifically, in the embodiment of the present utility model, a plurality of the first punching sheets 113 are provided, and at least one of the first punching sheets 113 is provided at each end of the rotor core 100. The second punching sheet 114 is located between the two first punching sheets 113 respectively provided at the two ends of the rotor core 100. Since the number of the first passages 111 on the first punching sheet 113 is less than the number of the first passages 111 on the second punching sheet 114, at this time, the structural strength of the first punching sheet 113 is higher than that of the second punching sheet 114. By arranging the second punching sheet 114 between the first punching sheets 113 at both ends, the structural strength at both ends of the rotor core 100 is ensured. Of course, in other embodiments, at least one second punching sheet 114 is provided at each end of the rotor core 100, and the first punching sheet 113 is located between the two second punching sheets 114 respectively provided at the two ends of the rotor core 100.

[0051] Specifically, in the embodiment of the present utility model, the number of the first punching sheets 113 is 2N1, and the number of the second punching sheets 114 is N2, where 0.5 ≤ N2 / N1 ≤ 8. It can be understood that in order to ensure the structural stability of the rotor core 100, the same number of the first punching sheets 113 are provided at both ends of the rotor core 100, so that the specific number of the first punching sheets 113 is 2N1. The arrangement of the second punching sheet 114 can further reduce the loss and magnetic leakage of the rotor core 100 because the number of the first passages 111 on it is more than the number of the first passages 111 on the first punching sheet 113, and effectively improve the motor efficiency.

[0052] Specifically, when the ratio of N2 / N1 is too small, it is likely that the number of the second punching sheets 114 is too small to significantly improve the efficiency improvement effect. When the ratio of N2 / N1 is too large, the total number of the first punching sheets 113 is less than the number of the second punching sheets 114, and it is likely that the overall structural strength of the rotor core 100 is affected due to the excessive number of the second punching sheets 114. Therefore, it is defined that 0.5 ≤ N2 / N1 ≤ 8, and on the basis of ensuring the structural strength of the rotor core 100, the efficiency of the motor adopting the rotor core 100 is further improved. The specific values of N2 / N1 include but are not limited to 0.5, 0.8, 1, 2, 3, 4, 5, 6, 7, 8.

[0053] Please refer to Figure 3 , in the embodiment of the present utility model, a plurality of the second punching sheets 114 are provided and arranged between the two first punching sheets 113 provided at both ends of the rotor core 100, that is, in the axial direction of the rotor punching sheet 11, a plurality of the second punching sheets 114 are stacked and are all located between the respective first punching sheets 113 provided at both ends of the rotor core 100 to form the rotor core 100; wherein, according to 0.5 ≤ N2 / N1 ≤ 8, the numbers of the first punching sheets 113 and the second punching sheets 114 on the rotor core 100 are reasonably designed to obtain the rotor core 100 with high stability and low loss characteristics under high-speed operation.

[0054] Please refer to Figure 4 , in the embodiment of the present utility model, the rotor core 100 further includes a punching sheet combination 15 and the first punching sheet 113 provided at the end of the punching sheet combination 15;

[0055] The punching sheet combination 15 includes the stacked first punching sheets 113 and the second punching sheets 114, and the number of the first punching sheets 113 at the end of the punching sheet combination 15 is equal to the number of the first punching sheets 113 inside the punching sheet combination 15, so as to ensure the symmetric arrangement of the two first punching sheets 113 at both ends of the rotor core 100 and facilitate improving the structural stability of the rotor. The specific number of the punching sheet combinations 15 mainly depends on the thickness of the rotor core 100 in the axial direction and the performance requirements of the motor. Among them, one set or multiple sets of punching sheet combinations 15 can be provided. However, in other embodiments, the positions of the first punching sheets 113 and the second punching sheets 114 can be interchangeably arranged.

[0056] Specifically, in an embodiment of the present utility model, within the punching sheet assembly 15, one first punching sheet 113 and one second punching sheet 114 are provided, forming a punching sheet assembly 15 with high stability and low loss characteristics, facilitating the assembly of the rotor core 100; when multiple punching sheet assemblies 15 are provided, each punching sheet assembly 15 is stacked in sequence along the axial direction of the rotor core 100, and one first punching sheet 113 is provided at the end of the stacked punching sheet assembly aggregate, ensuring the symmetry of the structure of the rotor core 100, and also ensuring the structural strength at both ends of the rotor core 100 because the number of first passages 111 on the first punching sheet 113 is less than the number of first passages 111 on the second punching sheet 114.

[0057] Specifically, in another embodiment of the present utility model, within the punching sheet assembly 15, multiple first punching sheets 113 and multiple second punching sheets 114 are provided, forming a punching sheet assembly 15 with high stability and low loss characteristics, facilitating the assembly of the rotor core 100; when multiple punching sheet assemblies 15 are provided, each punching sheet assembly 15 is stacked in sequence along the axial direction of the rotor core 100, and multiple first punching sheets 113 are provided at the end of the stacked punching sheet assembly aggregate, ensuring the symmetry of the structure of the rotor core 100, and also ensuring the structural strength at both ends of the rotor core 100 because the number of first passages 111 on the first punching sheet 113 is less than the number of first passages 111 on the second punching sheet 114. At this time, the specific number of groups of the punching sheet assembly 15 is (total number of punching sheets - number of first punching sheets 113 at the end) / 2 groups.

[0058] Please refer to Figure 1 , in an embodiment of the present utility model, the mounting groove 13 includes a first groove section 131 parallel to the radial direction of the rotor core 100 and two second groove sections 132 connected to opposite sides of the first groove section 131. The circulation hole 12 communicates with the first groove section 131, that is, the first groove section 131 extends in a direction parallel to the radial direction of the rotor core 100. The second groove section 132 is arranged at an angle with the first groove section 131, and its extending direction can intersect the radial direction of the rotor core 100. The first passage 111 communicates the circulation hole 12 and the first groove section 131, facilitating the realization of structural symmetry, ensuring the uniform distribution of the magnetic field on the rotor punching sheet 11, thereby improving the running stability of the motor, reliably reducing noise, and also facilitating the optimization of the magnetic circuit on the rotor punching sheet 11, improving the motor efficiency and motor performance; wherein, the mounting groove 13 includes the first groove section 131 and two second groove sections 132, which can increase the magnetic flux to a certain extent, improve the magnetic field intensity, and is also beneficial to improving the structural strength of the rotor punching sheet 11 and extending the service life of the rotor core 100. However, in other embodiments, the mounting groove 13 only includes the first groove section 131; or, the first groove section 131 and the two second groove sections 132 are both connected with the first passage 111. At this time, the shape of the circulation hole 12 is adapted to the formation of the mounting groove 13.

[0059] Optionally, in an embodiment of the present utility model, a first permanent magnet is installed in the first slot section 131, and the length of the first permanent magnet is Lm1. A second permanent magnet is installed in the second slot section 132, and the length of the second permanent magnet is Lm2. 1.02 ≤ Lm1 / Lm2 ≤ 1.3. Wherein, the length direction of the first permanent magnet is arranged parallel to the radial direction of the rotor core 100, which helps to generate a constant magnetic flux and facilitates ensuring the stability of the magnetic field during high-speed operation. The length direction of the second permanent magnet is arranged at an angle to the radial direction of the rotor core 100, which facilitates improving the starting performance. By limiting 1.02 ≤ Lm1 / Lm2 ≤ 1.3, the length of the first permanent magnet is always greater than that of the second permanent magnet, improving the running stability of the motor. Cooperating with the two symmetrically arranged second permanent magnets can also enhance the starting reliability of the motor. At the same time, it is also convenient for the motor to adapt to different working conditions and load requirements. With such an arrangement, it helps to improve the motor efficiency and motor performance.

[0060] Optionally, in an embodiment of the present utility model, an air slot 14 is provided on the rotor punching 11 between two adjacent mounting slots 13. The area of the air slot 14 is S, and 3 ≤ S ≤ 3.9. Specifically, when the area of the air slot 14 is less than 3, it is not conducive to reducing magnetic leakage. When the area of the air slot 14 is greater than 3.9, it is easy to reduce the structural strength of the rotor punching 11. Therefore, limiting the area of the air slot 14 between 3 and 3.9 can not only reduce magnetic leakage and reduce the influence on the output torque, but also effectively ensure the structural strength of the rotor core 100, thereby improving the motor efficiency and motor performance.

[0061] Specifically, the specific values of the area S of the air slot 14 include but are not limited to 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9. And, the cross-sectional shape of the air slot 14 can be circular or trapezoidal.

[0062] The present utility model also proposes a rotor, which includes a rotor core 100. The specific structure of the rotor core 100 refers to the above embodiment. Since this rotor adopts all the technical solutions of the above all embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated here one by one.

[0063] The present utility model also proposes a motor, which includes a rotor. The specific structure of the rotor refers to the above embodiment. Since this motor adopts all the technical solutions of the above all embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated here one by one. Among them, each rotor punching 11 is laminated through riveting holes to form a rotor core 100. The permanent magnet is installed in the mounting slot 13, and the stator is fixed to the outer periphery of the rotor core 100.

[0064] The present utility model also provides a compressor, which includes a motor. The specific structure of the motor refers to the above embodiments. Since this compressor adopts all the technical solutions of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated one by one here. Among them, the compressor can be applied to devices such as air conditioners and refrigerators.

[0065] The above is only an exemplary embodiment of the present utility model, and does not limit the patent scope of the present utility model. Any equivalent structural transformation made under the technical concept of the present utility model by using the content of the specification and drawings of the present utility model, or any direct / indirect application in other related technical fields is included in the patent protection scope of the present utility model.

Claims

1. A rotor core, characterized in that: The invention comprises a plurality of rotor punching sheets stacked along the axial direction thereof; The rotor punching sheet includes a plurality of mounting grooves arranged along its circumference, a plurality of flow holes are provided on the inner side of the mounting grooves, at least part of the flow holes are connected to at least part of the mounting grooves through a first passage, and the flow holes and the first passage are provided on the center line of the corresponding mounting groove.

2. The rotor core according to claim 1, characterized in that: The width of the first passage at the mounting groove is d1, and the width of the first passage at the circulation hole is d2, where d1≤d2.

3. The rotor core according to claim 1, characterized in that: The number of pole pairs of the rotor core is P, the number of the first paths is K, and K=P; Alternatively, K=2P.

4. The rotor core according to claim 1, characterized in that: The numbers of the first passages on the plurality of rotor sheets are the same.

5. The rotor core according to claim 1, characterized in that: The plurality of rotor punching sheets at least include a first punching sheet and a second punching sheet stacked in the axial direction of the rotor core, and the number of first passages on the first punching sheet is less than the number of first passages on the second punching sheet.

6. The rotor core according to claim 5, characterized in that: A plurality of the first punching sheets are provided, and at least one first punching sheet is provided at each of the two ends of the rotor core. The second punching sheet is located between two first punching sheets provided at the two ends of the rotor core.

7. The rotor core according to claim 6, characterized in that: The number of the first punching sheets is 2N1, the number of the second punching sheets is N2, and 0.5≤N2 / N1≤8.

8. The rotor core according to claim 6, characterized in that: A plurality of second punching sheets are provided and arranged between two first punching sheets provided at two ends of the rotor core.

9. The rotor core according to claim 6, characterized in that: The rotor core further comprises a punching sheet assembly and the first punching sheet arranged at the end of the punching sheet assembly; The punching sheet assembly includes the first punching sheets and the second punching sheets stacked together, and the number of the first punching sheets located at the end of the punching sheet assembly is equal to the number of the first punching sheets located in the punching sheet assembly.

10. The rotor core according to claim 9, characterized in that: In the punching sheet assembly, each of the first punching sheet and the second punching sheet is provided with one; Alternatively, in the punching sheet assembly, a plurality of the first punching sheets and a plurality of the second punching sheets are provided.

11. The rotor core according to claim 10, characterized in that: The punching sheet assembly is provided in multiple groups.

12. The rotor core according to claim 1, characterized in that: The installation slot includes a first slot section radially parallel to the rotor core and two second slot sections connected to opposite sides of the first slot section, and the flow hole is communicated with the first slot section.

13. The rotor core according to claim 12, characterized in that: A first permanent magnet is installed in the first slot section, and the length of the first permanent magnet is Lm1. A second permanent magnet is installed in the second slot section, and the length of the second permanent magnet is Lm2. 1.02≤Lm1 / Lm2≤1.

3.

14. The rotor core according to claim 1, characterized in that: The rotor punching sheet is provided with an air groove located between two adjacent mounting grooves, and the area of ​​the air groove is S, 3≤S≤3.

9.

15. A rotor, characterized in that: Comprising the rotor core according to any one of claims 1 to 14.

16. A motor, characterized in that: Comprising a rotor as claimed in claim 15.

17. A compressor, characterized in that: Comprising the motor as claimed in claim 16.

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