Rotor assembly, motor and household appliance

Abstract

The utility model discloses a rotor assembly, a motor and a household electrical appliance, and relates to the technical field of motors. The rotor assembly comprises the rotor core and the permanent magnet, and the permanent magnet is integrally injection-molded on the rotor core, so that the assembly of the rotor assembly can be simplified, and the production efficiency is improved. The inner side wall of the rotor core is provided with a plurality of grooves which are arranged around the axis of the rotating shaft of the rotor assembly, the outer side wall of the first magnetic part is provided with convex parts which are the same as the grooves in number, and the convex parts are correspondingly arranged in the grooves. Under the condition that the external dimension of the motor is not changed basically, the size of the permanent magnet can be effectively increased, and then the magnetic flux generated by the permanent magnet is increased. And meanwhile, the outer side wall of the first magnetic part is provided with the convex part, so that the area of the outer side wall of the first magnetic part can be effectively increased, the area of magnetic flux emitted by the rotor assembly is larger than the area of one side close to the air gap, a magnetism gathering effect can be formed, the air gap flux density is improved, the torque density is improved, and the performance of the motor is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of motors, in particular to a rotor assembly, a motor and a household appliance. Background Art

[0002] Permanent magnet motors drive the rotor assembly to rotate and output torque through the interaction between the magnetic field of the permanent magnet and the magnetic field of the winding. Permanent magnet motors have the advantages of high efficiency, high power density, and rapid response, and are widely used in industrial automation, electric vehicles, household appliances and other fields. The rotor assembly of a permanent magnet motor includes a rotor core and multiple permanent magnets. The rotor core is annular, and multiple permanent magnets are arranged on the inner side of the rotor core. In the motor using the above scheme, multiple permanent magnets need to be installed on the inner side of the rotor core respectively, and the installation efficiency is low; limited by the size of the motor, the size of the permanent magnet is small, and the air gap magnetic density is low, resulting in low torque density, and it is difficult to improve the performance of the motor. Utility Model Content

[0003] The utility model aims to solve at least one of the technical problems existing in the prior art. To this end, the utility model proposes a rotor assembly that can improve the assembly efficiency of the rotor assembly, increase the volume of the permanent magnet, increase the air gap magnetic density, and further increase the torque density to improve the performance of the motor.

[0004] The utility model also provides a motor and a household appliance having the rotor assembly.

[0005] According to the first aspect of the present invention, the rotor assembly comprises: an annular rotor core, wherein the inner side wall of the rotor core is provided with a plurality of grooves, and the plurality of grooves are arranged around the rotation axis of the rotor assembly;

[0006] A permanent magnet is integrally injection molded on the rotor core, and the permanent magnet includes a first magnetic part, which is arranged around the inner wall of the rotor core, and the outer wall of the first magnetic part is provided with convex parts with the same number as the grooves, and multiple convex parts are correspondingly arranged in multiple grooves.

[0007] The rotor assembly according to the embodiment of the utility model has at least the following beneficial effects:

[0008] By setting the rotor assembly to include a permanent magnet and an annular rotor core, the permanent magnet is integrally injection molded on the rotor core, which can simplify the assembly of the rotor assembly and improve production efficiency. The inner side wall of the rotor core is provided with a plurality of grooves arranged around the axis of the rotating shaft of the rotor assembly, and the outer side wall of the first magnetic part is provided with convex parts with the same number as the grooves, and the convex parts are correspondingly arranged in the grooves. Therefore, the contact area between the rotor core and the first magnetic part is increased, which can improve the stability and reliability of the connection. Without substantially changing the outer dimensions of the motor, the volume of the permanent magnet can be effectively increased, thereby increasing the magnetic flux generated by the permanent magnet. At the same time, the outer side wall of the first magnetic part is provided with a convex part, which can effectively increase the area of ​​the outer side wall of the first magnetic part, so that the magnetic flux area emitted by the rotor assembly is greater than the area close to the air gap side, which can form a magnetic concentration effect, thereby increasing the air gap magnetic density, and then increasing the torque density, so as to improve the performance of the motor.

[0009] According to some embodiments of the present invention, the rotor core includes multiple transition sections and multiple matching sections, the number of the matching sections is the same as the number of the transition sections, the inner wall of the matching section is recessed to form the groove, and the multiple transition sections and the multiple matching sections are alternately connected in sequence.

[0010] According to some embodiments of the present invention, the rotor core includes a plurality of arc segments, the plurality of arc segments are sequentially connected along the circumference of the rotor assembly, the plurality of arc segments protrude in a direction away from the rotation axis, and the groove is formed on the inner side of the arc segments.

[0011] According to some embodiments of the present invention, along the radial direction of the rotor assembly, the maximum thickness of the rotor assembly is hx0, and the maximum thickness of the rotor core is hx1, satisfying: 0.3≤hx1 / hx0≤0.97.

[0012] According to some embodiments of the present invention, along the radial direction of the rotor assembly, the maximum thickness of the rotor core is hx1, and the minimum thickness of the rotor core is hx2, satisfying: 0.1≤hx2 / hx1≤0.4.

[0013] According to some embodiments of the present invention, the permanent magnet further includes a second magnetic portion, and the second magnetic portion is arranged around the outer side wall of the rotor core.

[0014] According to some embodiments of the present invention, in a cross section perpendicular to the rotation axis, the cross-sectional area of ​​the first magnetic portion is S1, and the cross-sectional area of ​​the second magnetic portion is S2, satisfying: S1 / S2≥0.5.

[0015] According to some embodiments of the present invention, the permanent magnet further includes a third magnetic portion, the third magnetic portion is disposed at at least one end of the rotor core along the axial direction of the rotor assembly, and the third magnetic portion is connected to the first magnetic portion and the second magnetic portion.

[0016] According to some embodiments of the present invention, the permanent magnet further includes a third magnetic portion, the third magnetic portion is disposed at at least one end of the rotor core along the axial direction of the rotor assembly, and the third magnetic portion is connected to the first magnetic portion.

[0017] The motor according to the second embodiment of the utility model comprises a stator assembly and the rotor assembly described in the above embodiment, wherein the stator assembly is arranged on the inner side of the rotor assembly; or the rotor assembly is arranged on the inner side of the stator assembly.

[0018] The motor according to the embodiment of the utility model has at least the following beneficial effects:

[0019] By adopting the rotor assembly of the first aspect embodiment, the rotor assembly includes a permanent magnet and an annular rotor core, and the permanent magnet is integrally injection molded on the rotor core, which can simplify the assembly of the rotor assembly and improve production efficiency. The inner side wall of the rotor core is provided with a plurality of grooves arranged around the axis of the rotating shaft of the rotor assembly, and the outer side wall of the first magnetic part is provided with convex parts with the same number as the grooves, and the convex parts are correspondingly arranged in the grooves. Therefore, the contact area between the rotor core and the first magnetic part is increased, which can improve the stability and reliability of the connection. Without substantially changing the outer dimensions of the motor, the volume of the permanent magnet can be effectively increased, thereby increasing the magnetic flux generated by the permanent magnet. At the same time, the outer side wall of the first magnetic part is provided with a convex part, which can effectively increase the area of ​​the outer side wall of the first magnetic part, so that the magnetic flux area emitted by the rotor assembly is greater than the area close to the air gap side, which can form a magnetic concentration effect, thereby improving the air gap magnetic density, and then improving the torque density, so as to improve the performance of the motor.

[0020] A household appliance according to an embodiment of the third aspect of the utility model comprises the motor described in the above embodiment.

[0021] The household appliance according to the embodiment of the utility model has at least the following beneficial effects:

[0022] By adopting the motor of the second embodiment, the rotor assembly of the motor includes a permanent magnet and an annular rotor core, and the permanent magnet is integrally injection molded on the rotor core, which can simplify the assembly of the rotor assembly and improve production efficiency. The inner side wall of the rotor core is provided with a plurality of grooves arranged around the axis of the rotating shaft of the rotor assembly, and the outer side wall of the first magnetic part is provided with convex parts with the same number as the grooves, and the convex parts are correspondingly arranged in the grooves. Therefore, the contact area between the rotor core and the first magnetic part is increased, which can improve the stability and reliability of the connection. Without substantially changing the outer dimensions of the motor, the volume of the permanent magnet can be effectively increased, thereby increasing the magnetic flux generated by the permanent magnet. At the same time, the outer side wall of the first magnetic part is provided with a convex part, which can effectively increase the area of ​​the outer side wall of the first magnetic part, so that the magnetic flux area emitted by the rotor assembly is greater than the area close to the air gap side, which can form a magnetic concentration effect, thereby improving the air gap magnetic density, and then improving the torque density, so as to improve the performance of the motor.

[0023] Additional aspects and advantages of the present invention will be given in part in the following description, and in part will become apparent from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention is further described below with reference to the accompanying drawings and embodiments, wherein:

[0025] Figure 1 It is a structural schematic diagram of a rotor assembly of the first embodiment of the utility model;

[0026] Figure 2 It is a structural schematic diagram of a rotor assembly of a second embodiment of the utility model;

[0027] Figure 3 It is a structural schematic diagram of a rotor assembly of a third embodiment of the utility model;

[0028] Figure 4 It is a structural schematic diagram of a rotor assembly of a fourth embodiment of the utility model;

[0029] Figure 5 is a cross-sectional view of a rotor assembly of a fifth embodiment of the utility model;

[0030] Figure 6 is a cross-sectional view of a rotor assembly of a sixth embodiment of the utility model;

[0031] Figure 7 It is a structural schematic diagram of a motor in one embodiment of the utility model;

[0032] Figure 8 It is a structural schematic diagram of a motor in another embodiment of the utility model;

[0033] Fig. 9It is a curve diagram showing the relationship between the ratio of hx1 / hx0 and the line back electromotive force of an embodiment of the utility model;

[0034] Fig.10 It is a curve diagram showing the relationship between the ratio of hx2 / hx1 and the line back electromotive force of an embodiment of the utility model;

[0035] Fig.11 It is a curve diagram showing the relationship between the ratio of S1 / S2 and the line back electromotive force of an embodiment of the utility model;

[0036] Fig.12 It is a curve diagram showing the relationship between the ratio of S1 / S2 and efficiency of an embodiment of the utility model;

[0037] Fig.13 It is a relationship curve diagram of the ratio of S1 / S2 and copper loss in one embodiment of the utility model.

[0038] Reference numerals:

[0039] Rotor assembly 1000;

[0040] Rotor core 100; groove 110; transition section 120; matching section 130; arc section 140; positioning structure 150; positioning hole 152; positioning groove 153;

[0041] Permanent magnet 200; first magnetic part 210; convex part 211; second magnetic part 220; third magnetic part 230;

[0042] Stator assembly 2000. DETAILED DESCRIPTION

[0043] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0044] In the description of the present invention, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0045] In the description of the present utility model, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0046] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0047] Reference Figure 1 As shown, a rotor assembly 1000 of an embodiment of the utility model can be used for a permanent magnet motor. The rotor assembly 1000 of the embodiment of the utility model includes a rotor core 100 and a permanent magnet 200. The rotor core 100 is annular, and the inner side wall of the rotor core 100 is provided with a plurality of grooves 110, and the plurality of grooves 110 are arranged around the rotation axis of the rotor assembly 1000. The permanent magnet 200 is integrally injection molded on the rotor core 100, and the rotor core 100 includes a first magnetic portion 210, and the first magnetic portion 210 is arranged around the inner side wall of the rotor core 100. The outer side wall of the first magnetic portion 210 is provided with a plurality of protrusions 211, and the number of the protrusions 211 is the same as the number of the grooves 110, and the plurality of protrusions 211 are correspondingly arranged in the plurality of grooves 110. Therefore, the contact area between the first magnetic part 210 and the rotor core 100 is increased, which can effectively improve the stability of the connection between the first magnetic part 210 and the rotor core 100, reduce the risk of loosening and falling off, and improve the reliability of the rotor assembly 1000.

[0048] By providing the permanent magnet 200 to be integrally injection molded on the rotor core 100, the assembly of the rotor assembly 1000 can be simplified and the production efficiency can be improved. The outer wall of the first magnetic part 210 is provided with a convex part 211 located in the groove 110, which can effectively increase the volume of the permanent magnet 200 without substantially changing the outer dimensions of the motor, thereby increasing the magnetic flux generated by the permanent magnet 200. At the same time, the area of ​​the outer wall of the first magnetic part 210 can be increased, so that the area of ​​the magnetic flux emitted by the rotor assembly 1000 is larger than the area close to the air gap side, so as to form a magnetic concentration effect, thereby increasing the air gap magnetic density, and then increasing the torque density, so as to improve the performance of the motor.

[0049] It should be noted that the permanent magnet 200 can be an injection-molded magnet, in which magnetic powder, binder and other additives are mixed in a certain proportion, injected into a mold and integrally formed with the rotor core 100. Compared with sintered magnets, there are many processing methods for injection-molded permanent magnets 200, such as calendering, extrusion, injection, molding, etc.; the shape of injection molding has a large degree of freedom and can produce complex shapes; the dimensional accuracy is high and basically no secondary processing is required; the process is simple and can be mass-produced automatically with high efficiency and high yield. Therefore, the permanent magnet 200 can perfectly fit the inner shape of the rotor core 100, and can automatically form a corresponding number of protrusions 211 according to the number of grooves 110.

[0050] Reference Figure 1 As shown, in the first embodiment of the utility model, the rotor core 100 includes a plurality of transition sections 120 and a plurality of matching sections 130, the number of matching sections 130 is the same as the number of transition sections 120, and the inner wall of the matching section 130 is recessed to form a groove 110. Along the circumference of the rotor assembly 1000, the plurality of transition sections 120 and the plurality of matching sections 130 are alternately connected in sequence to form an annular structure. Among them, the connection method of the transition section 120 and the matching section 130 is integrally formed, for example, by punching out a punching sheet of a corresponding shape on a plate, and then stacking a plurality of punching sheets to form the rotor core 100. In other connection methods, the relative position of the transition section 120 and the matching section 130 can also be fixed by welding, bonding, or integral plastic coating.

[0051] It can be understood that by setting the rotor core 100 to include a transition section 120 and a mating section 130, the transition section 120 can increase the magnetic flux area and avoid magnetic circuit congestion; the transition section 120 can also increase the overall strength of the rotor core 100, improve the stability of the rotor core 100, and at the same time simplify the production and manufacturing of the rotor core 100, avoid the appearance of sharp corners between adjacent grooves 110, which is beneficial to the production and manufacturing of the rotor core 100.

[0052] Reference Figure 2As shown, in the second embodiment of the utility model, the rotor core 100 includes a plurality of arc segments 140, and the plurality of arc segments 140 are sequentially connected along the circumference of the rotor assembly 1000. In order to avoid sharp corners at the connection of the arc segments 140, rounded corners or straight angles can be set at the connection of the arc segments 140. The plurality of arc segments 140 protrude in a direction away from the axis of rotation, and the inner side of the arc segments 140 is recessed to form a groove 110. Since the adjacent arc segments 140 are directly connected, the area of ​​the inner wall of the groove 110 is larger, further increasing the area of ​​the outer wall of the first magnetic portion 210, so that the magnetic flux area emitted by the rotor assembly 1000 is larger than the area close to the air gap side, so as to form a magnetic concentration effect, thereby increasing the air gap magnetic density, and then increasing the torque density, so as to improve the performance of the motor. At the same time, a positioning groove 153 is formed between the outer side walls of two adjacent arc segments 140. When the permanent magnet 200 is injected, the positioning groove 153 is used to determine the position of the rotor core 100 in the mold to prevent the rotor core 100 from being misplaced or shaken during the injection molding process. There is no need to design other positioning structures 150, which can simplify the production steps of the rotor core 100 and improve the injection molding efficiency.

[0053] Reference Figure 3 As shown, in the third embodiment of the utility model, on the basis of the rotor assembly 1000 of the first embodiment, the permanent magnet 200 further includes a second magnetic portion 220, and the second magnetic portion 220 is arranged around the outer wall of the rotor core 100. It can be understood that by arranging the first magnetic portion 210 and the second magnetic portion 220 on the inner side and the outer side of the permanent magnet 200, respectively, the volume of the permanent magnet 200 can be further increased to increase the magnetic field strength of the permanent magnet 200, thereby increasing the air gap magnetic density of the motor and improving the power density of the motor. At the same time, it can also effectively limit the separation of the rotor core 100 and the permanent magnet 200, and improve the stability and reliability of the connection between the rotor core 100 and the permanent magnet 200.

[0054] Reference Figure 4 As shown, in the fourth embodiment of the utility model, on the basis of the rotor assembly 1000 of the second embodiment, the permanent magnet 200 also includes a second magnetic part 220, and the second magnetic part 220 is arranged around the outer wall of the rotor core 100, and the second magnetic part 220 can be filled in the positioning groove 153 between adjacent arc segments 140 to further improve the stability of the connection between the second magnetic part 220 and the rotor core 100, effectively avoid the second magnetic part 220 from loosening and falling off, and improve the reliability of the connection.

[0055] In order to further improve the stability of the connection between the rotor core 100 and the permanent magnet 200, refer to Figure 5As shown, in the fifth embodiment of the utility model, the permanent magnet 200 further includes a third magnetic portion 230, which is disposed at at least one end of the rotor core 100 along the axial direction of the rotor assembly 1000, for example, the third magnetic portion 230 is disposed at both ends of the rotor core 100, and the third magnetic portion 230 is connected to the first magnetic portion 210 and the second magnetic portion 220, for example, the third magnetic portion 230 is integrally injection molded with the first magnetic portion 210 and the second magnetic portion 220 to limit the displacement of the rotor core 100 along the axial direction. The third magnetic portion 230 is in a continuous ring shape and is arranged around the rotation axis of the rotor assembly 1000; or, the third magnetic portion 230 includes a plurality of magnetic segments arranged at intervals and is arranged around the rotation axis of the rotor assembly 1000, and a suitable solution is selected according to actual conditions.

[0056] By providing the first magnetic portion 210, the second magnetic portion 220 and the third magnetic portion 230, that is, the rotor core 100 is wrapped by the permanent magnet 200, the stability of the connection between the rotor core 100 and the permanent magnet 200 can be further improved, and the rotor core 100 and the permanent magnet 200 can be prevented from being separated during the rotation process, and the reliability of the rotor assembly 1000 can be improved. At the same time, the third magnetic portion 230 can also increase the volume of the permanent magnet 200, and increase the magnetic field strength of the permanent magnet 200, thereby increasing the air gap magnetic density of the motor and improving the power density of the motor. At the same time, it can also effectively limit the separation of the rotor core 100 and the permanent magnet 200, and improve the stability and reliability of the connection between the rotor core 100 and the permanent magnet 200.

[0057] Reference Figure 6 As shown, in the sixth embodiment of the utility model, the second magnetic part 220 may not be provided on the outer side wall of the rotor core 100, and the permanent magnet 200 only includes the first magnetic part 210 and the third magnetic part 230. The third magnetic part 230 is provided at least at one end of the rotor core 100 along the axial direction of the rotor assembly 1000. For example, the third magnetic part 230 is provided at both ends of the rotor core 100, and the third magnetic part 230 and the first magnetic part 210 are integrally injection molded to limit the displacement of the rotor core 100 along the axial direction. The third magnetic part 230 is in a continuous ring shape and is arranged around the rotation axis of the rotor assembly 1000; or, the third magnetic part 230 includes a plurality of magnetic segments arranged at intervals and is arranged around the rotation axis of the rotor assembly 1000. The appropriate solution is selected according to the actual situation. By setting the third magnetic part 230 to limit the displacement of the rotor core 100 along the axial direction, the stability of the connection between the rotor core 100 and the permanent magnet 200 is further improved, the risk of loosening and falling off is reduced, and the reliability and stability of the rotor assembly 1000 are improved.

[0058] Reference Figure 3As shown, in the embodiment of the utility model, based on the solution of the third embodiment, along the radial direction of the rotor assembly 1000, the maximum thickness of the rotor assembly 1000 is hx0, and the maximum thickness of the rotor core 100 is hx1. For example, the maximum thickness of the rotor core 100 is the thickness of the transition section 120, which satisfies: 0.3≤hx1 / hx0≤0.97. For example, the value of hx1 / hx0 can be 0.3, 0.45, 0.51, 0.62, 0.73, 0.86, 0.91, 0.97, etc. hx1 / hx0 reflects the ratio between the maximum thickness of the rotor core 100 and the maximum thickness of the rotor assembly 1000. Fig. 9 As shown, Fig. 9 The horizontal axis represents the value of hx1 / hx0, and the vertical axis represents the line back EMF. The line back EMF refers to the electromotive force generated in the winding due to the change of the rotor magnetic flux when the motor is running. Fig. 9 It can be seen that as the value of hx1 / hx0 gradually increases in the range of 0.2 to 1, the line back EMF increases first and then decreases. The increase in line back EMF can improve the efficiency of the motor. Under the same torque demand and line back EMF conditions, the motor current can be reduced, thereby effectively improving the efficiency of the motor at low speed and high torque. Fig. 9 The curve in is explained as follows:

[0059] When the maximum thickness of the rotor assembly 1000 remains unchanged, when hx1 / hx0 is less than 0.3, that is, the maximum thickness of the rotor core 100 is too small, and the volume of the permanent magnet 200 is too large. The rotor core 100 mainly plays the role of magnetic circuit conduction, and the permanent magnet 200 is used to provide magnetic flux. When the maximum thickness of the rotor assembly 1000 is too small, it means that the cross-sectional area of ​​the magnetic circuit conduction is reduced, and the magnetic circuit is easily saturated, resulting in increased leakage magnetic flux, and a decrease in the effective magnetic flux density entering the air gap, which in turn leads to a decrease in torque density, resulting in a lower line back electromotive force.

[0060] When hx1 / hx0 is greater than 0.97, that is, the maximum thickness of the rotor core 100 is too large, the volume of the permanent magnet 200 is reduced. When the shape of the matching section 130 remains unchanged and the thickness of the transition section 120 increases, the volume of the permanent magnet 200 will be reduced, but the reduction is not large. Fig. 9 The curve in the figure has a small drop in the range of 0.8 to 1. However, as the thickness of the transition section 120 increases, the transition section 120 is prone to have sharp corners, which is not conducive to the design of high-impact dies and the production of the rotor core 100.

[0061] Therefore, by reasonably designing the value of hx1 / hx0 and limiting it within the range of 0.3 to 0.97, the cross-sectional area of ​​the magnetic circuit of the rotor core 100 can be increased, leakage magnetic flux can be reduced, air gap magnetic density can be increased, and thus the torque density can be increased to increase the back electromotive force. At the same time, the rotor core 100 can be prevented from having sharp corners, which is beneficial to the production of the rotor core 100.

[0062] Continue to refer to Figure 3 As shown, in the embodiment of the present invention, based on the solution of the third embodiment, along the radial direction of the rotor assembly 1000, the maximum thickness of the rotor core 100 is hx1, and the minimum thickness of the rotor core 100 is hx2. For example, the minimum thickness of the rotor core 100 is located at the matching section 130, and satisfies: 0.1≤hx2 / hx1≤0.4. For example, the value of hx2 / hx1 can be 0.1, 0.15, 0.23, 0.28, 0.34, 0.4, etc. hx2 / hx1 reflects the ratio between the maximum thickness and the minimum thickness of the rotor core 100. Fig.10 As shown, Fig.10 The horizontal axis represents the value of hx2 / hx1, and the vertical axis represents the line back EMF. The line back EMF refers to the electromotive force generated in the winding due to the change of the rotor magnetic flux when the motor is running. Fig.10 It can be seen that as the value of hx2 / hx1 gradually increases in the range of 0.2 to 0.5, the line back EMF increases first and then decreases. The increase in line back EMF can improve the efficiency of the motor. Under the same torque demand and line back EMF conditions, the motor current can be reduced, thereby effectively improving the efficiency of the motor at low speed and high torque. Fig.10 The curve in is explained as follows:

[0063] When hx2 / hx1 is less than 0.1, the minimum thickness of the rotor core 100 is too small and the maximum thickness is too thick, which may lead to insufficient strength at the thinnest part of the rotor core 100, and may cause deformation, bending, fracture and other adverse effects, resulting in low yield rate. If the maximum thickness is too thick, sharp corners may appear, which is not conducive to the design of high-impact molds and the production of the rotor core 100. In addition, the increase in the maximum thickness will lead to a decrease in the volume of the permanent magnet 200, but because the volume of the permanent magnet 200 is not reduced much, Fig.10 The curve in the graph has dropped slightly, but the drop is not large.

[0064] When hx2 / hx1 is greater than 0.4, that is, the minimum thickness of the rotor core 100 increases, the maximum thickness decreases, and the depth of the groove 110 decreases, resulting in a decrease in the area of ​​the outer wall of the first magnetic part 210, making it difficult to form a magnetic field concentration effect; and the reduction in the maximum thickness reduces the cross-sectional area of ​​the magnetic circuit, and the magnetic circuit is easily saturated, resulting in increased leakage flux and a decrease in the effective magnetic flux density entering the air gap, which in turn leads to a decrease in the torque density, which greatly reduces the line back electromotive force.

[0065] Therefore, by reasonably designing the value of hx2 / hx1 and limiting it within the range of 0.1 to 0.4, the cross-sectional area of ​​the magnetic circuit of the rotor core 100 can be increased, leakage magnetic flux can be reduced, a magnetic concentration effect can be formed, the air gap magnetic density can be increased, and then the torque density can be increased to increase the back electromotive force. At the same time, the rotor core 100 can be avoided from having sharp corners, which is beneficial to the production of the rotor core 100.

[0066] Reference Figure 4 As shown, in an embodiment of the utility model, based on the scheme of the fourth embodiment described above, along the radial direction of the rotor assembly 1000, the maximum thickness of the rotor assembly 1000 is hx0, the maximum thickness of the rotor core 100 is hx1, and the minimum thickness of the rotor core 100 is hx2, satisfying: 0.3≤hx1 / hx0≤0.97, 0.1≤hx2 / hx1≤0.4. For example, the value of hx1 / hx0 can be 0.3, 0.45, 0.51, 0.62, 0.73, 0.86, 0.91, 0.97, etc., and the value of hx2 / hx1 can be 0.1, 0.15, 0.23, 0.28, 0.34, 0.4, etc. It should be noted that, in the fourth embodiment, the maximum thickness of the rotor core 100 refers to the distance between the maximum inscribed circle of the rotor core 100 and the maximum circumscribed circle of the rotor core 100, Figure 4 The dotted line in is the maximum inscribed circle of the rotor core 100. The size limitation effect of the fourth embodiment is similar to that of the third embodiment, which will not be described in detail here. Alternatively, the rotor assembly 1000 can be limited based on the first or second embodiment, with the same scope and similar effect as the above embodiments, which will not be described in detail here.

[0067] In the embodiment of the present invention, based on the third or fourth embodiment, in the cross section perpendicular to the rotation axis, the cross-sectional area of ​​the first magnetic part 210 is S1, and the cross-sectional area of ​​the second magnetic part 220 is S2, satisfying: S1 / S2 ≥ 0.5, for example, the value of S1 / S2 can be 0.5, 0.8, 1, 2, 3, 4, 5, 6, 7, 8, etc. S1 / S2 reflects the ratio between the cross-sectional area of ​​the first magnetic part 210 and the cross-sectional area of ​​the second magnetic part 220. Fig.11 As shown, Fig.11 The horizontal axis represents the value of S1 / S2, and the vertical axis represents the line back potential. As the value of S1 / S2 increases, the line back potential increases accordingly. Fig.12 As shown, Fig.12 The horizontal axis represents the value of S1 / S2, and the vertical axis represents the working efficiency of the motor. As the value of S1 / S2 increases, the working efficiency of the motor increases accordingly. Fig.13 As shown, Fig.13The horizontal axis represents the value of S1 / S2, and the vertical axis represents the copper loss. As the value of S1 / S2 increases, the copper loss decreases. The copper loss of the motor refers to the resistance loss caused by the current passing through the coil during the operation of the motor.

[0068] Since the first magnetic part 210 is located on the inner side of the rotor core 100, that is, the first magnetic part 210 is located on the side close to the air gap of the motor, the first magnetic part 210 mainly plays the role of providing magnetic flux, and the second magnetic part 220 plays a secondary role. When S1 / S2 is less than 0.5, the volume of the first magnetic part 210 is small, and the magnetic flux provided is reduced, which will cause the line back electromotive force and efficiency of the motor to decrease, and the copper loss to increase. Therefore, by reasonably designing the ratio range of S1 / S2, the line back electromotive force of the motor can be increased, the copper loss can be reduced, and the working efficiency can be improved by reducing the cross-sectional area of ​​the second magnetic part 220 and increasing the cross-sectional area of ​​the first magnetic part 210 without changing the outer dimensions of the motor.

[0069] In the embodiment of the present invention, the rotor core 100 is further provided with a positioning structure 150, which is used to determine the relative position of the rotor core 100 in the injection mold, so as to facilitate the integral injection molding of the rotor core 100 and the permanent magnet 200. The positioning structure 150 can be a structure such as a groove, a hole, a protrusion, etc. Figure 1 As shown, the positioning structure 150 is a plurality of positioning holes 152, which are arranged at intervals on the rotor core 100 and around the rotation axis. The positioning holes 152 pass through both axial ends of the rotor core 100, so as to facilitate the positioning and matching of the positioning holes 152 and the corresponding positioning columns in the mold to determine the position of the rotor core 100. Alternatively, refer to Figure 2 As shown, the positioning structure 150 can also be a positioning groove 153, which is formed in the depression between two adjacent arc-shaped portions. The positioning structure 150 is formed by using the structure of the rotor core 100 itself, and no additional positioning structure 150 needs to be designed, which can simplify the design of the rotor core 100 and improve production efficiency. In another embodiment, the positioning structure 150 can also be a protrusion, which is provided on the outer wall of the rotor core 100, and the protrusion is used to cooperate with the groove of the mold for positioning. The appropriate solution is selected according to the actual situation.

[0070] A motor according to an embodiment of the present invention comprises a stator assembly 2000 and a rotor assembly 1000 according to the above embodiment. Figure 7 As shown, the motor may be an outer rotor motor, that is, the stator assembly 2000 is arranged inside the rotor assembly 1000. Figure 8As shown, the motor can also be an inner rotor motor, and the rotor assembly 1000 is arranged on the inner side of the stator assembly 2000. The motor of the embodiment of the utility model adopts the rotor assembly 1000 of the above embodiment, and by setting the rotor assembly 1000 to include a permanent magnet 200 and an annular rotor core 100, the permanent magnet 200 is integrally injection molded on the rotor core 100, which can simplify the assembly of the rotor assembly 1000 and improve production efficiency. The inner side wall of the rotor core 100 is provided with a plurality of grooves 110 arranged around the axis of the rotating shaft of the rotor assembly 1000, and the outer side wall of the first magnetic part 210 is provided with convex parts 211 with the same number as the grooves 110, and the convex parts 211 are correspondingly arranged in the grooves 110. Therefore, the contact area between the rotor core 100 and the first magnetic part 210 is increased, which can improve the stability and reliability of the connection. Without substantially changing the outer dimensions of the motor, the volume of the permanent magnet 200 can be effectively increased, thereby increasing the magnetic flux generated by the permanent magnet 200. At the same time, the outer wall of the first magnetic part 210 is provided with a protrusion 211, which can effectively increase the area of ​​the outer wall of the first magnetic part 210. Therefore, the magnetic flux area emitted by the rotor assembly 1000 is larger than the area close to the air gap side, which can form a magnetic concentration effect, thereby increasing the air gap magnetic density, and then increasing the torque density, so as to improve the performance of the motor.

[0071] Since the motor adopts all the technical solutions of the rotor assembly 1000 of the above embodiment, it has at least all the beneficial effects brought by the technical solutions of the above embodiment, which will not be described in detail here.

[0072] A household appliance of an embodiment of the utility model includes the motor of the above embodiment, and the household appliance can be an air conditioner, a refrigerator, a washing machine, a vacuum cleaner, etc. The household appliance of the embodiment of the utility model adopts the motor of the above embodiment, and the motor includes a permanent magnet 200 and an annular rotor core 100 by setting a rotor assembly 1000, and the permanent magnet 200 is integrally injection molded on the rotor core 100, which can simplify the assembly of the rotor assembly 1000 and improve production efficiency. The inner side wall of the rotor core 100 is provided with a plurality of grooves 110 arranged around the axis of the rotating shaft of the rotor assembly 1000, and the outer side wall of the first magnetic part 210 is provided with a convex part 211 with the same number as the groove 110, and the convex part 211 is correspondingly arranged in the groove 110. Therefore, the contact area between the rotor core 100 and the first magnetic part 210 is increased, which can improve the stability and reliability of the connection. Without substantially changing the outer dimensions of the motor, the volume of the permanent magnet 200 can be effectively increased, thereby increasing the magnetic flux generated by the permanent magnet 200. At the same time, the outer wall of the first magnetic part 210 is provided with a protrusion 211, which can effectively increase the area of ​​the outer wall of the first magnetic part 210. Therefore, the magnetic flux area emitted by the rotor assembly 1000 is larger than the area close to the air gap side, which can form a magnetic concentration effect, thereby increasing the air gap magnetic density, and then increasing the torque density, so as to improve the performance of the motor.

[0073] Since the household appliance adopts all the technical solutions of the motor of the above embodiment, it at least has all the beneficial effects brought by the technical solutions of the above embodiment, which will not be described in detail here.

[0074] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A rotor assembly, characterized in that: include: An annular rotor core, wherein the inner side wall of the rotor core is provided with a plurality of grooves, and the plurality of grooves are arranged around the rotation axis of the rotor assembly; A permanent magnet is integrally injection molded on the rotor core, and the permanent magnet includes a first magnetic part, which is arranged around the inner wall of the rotor core, and the outer wall of the first magnetic part is provided with convex parts with the same number as the grooves, and multiple convex parts are correspondingly arranged in multiple grooves.

2. The rotor assembly according to claim 1, characterized in that: The rotor core includes a plurality of transition sections and a plurality of matching sections, the number of the matching sections is the same as the number of the transition sections, the inner wall of the matching section is recessed to form the groove, and the plurality of transition sections and the plurality of matching sections are alternately connected in sequence.

3. The rotor assembly according to claim 1, characterized in that: The rotor core includes a plurality of arc segments, which are sequentially connected along the circumference of the rotor assembly, protrude in a direction away from the rotation axis, and the grooves are formed on the inner sides of the arc segments.

4. The rotor assembly according to claim 2 or 3, characterized in that: Along the radial direction of the rotor assembly, the maximum thickness of the rotor assembly is hx0, and the maximum thickness of the rotor core is hx1, satisfying: 0.3≤hx1 / hx0≤0.

97.

5. The rotor assembly according to claim 2 or 3, characterized in that: Along the radial direction of the rotor assembly, the maximum thickness of the rotor core is hx1, and the minimum thickness of the rotor core is hx2, satisfying: 0.1≤hx2 / hx1≤0.

4.

6. The rotor assembly according to claim 1, characterized in that: The permanent magnet further includes a second magnetic portion, and the second magnetic portion is disposed around an outer side wall of the rotor core.

7. The rotor assembly according to claim 6, characterized in that: In a cross section perpendicular to the rotation axis, the cross-sectional area of ​​the first magnetic portion is S1, and the cross-sectional area of ​​the second magnetic portion is S2, satisfying: S1 / S2≥0.

5.

8. The rotor assembly according to claim 6, characterized in that: The permanent magnet further includes a third magnetic portion, which is disposed at at least one end of the rotor core along the axial direction of the rotor assembly, and is connected to the first magnetic portion and the second magnetic portion.

9. The rotor assembly according to claim 1, characterized in that: The permanent magnet further includes a third magnetic portion, which is disposed at at least one end of the rotor core along the axial direction of the rotor assembly and is connected to the first magnetic portion.

10. The motor is characterized by: It comprises a stator assembly and the rotor assembly according to any one of claims 1 to 9, wherein the stator assembly is arranged on the inner side of the rotor assembly; or the rotor assembly is arranged on the inner side of the stator assembly.

11. A household appliance, characterized in that The motor comprising the motor described in claim 10.

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