Rotor structure and motor

Abstract

The present application provides a rotor structure and a motor. The rotor structure comprises a rotor core, first permanent magnets, and second permanent magnets; the rotor core is provided with mounting slots, the first permanent magnets are mounted in the mounting slots, and the axial height of the first permanent magnets is greater than the axial height of the rotor core; the second permanent magnets are arranged at the axial end portions of the rotor core, the second permanent magnets are provided with slots, and the parts of the first permanent magnets extending out of the rotor core in the axial direction are inserted into the slots; the first permanent magnets are magnetized in the radial direction and / or tangential direction of the rotor core, and the second permanent magnets are magnetized in the axial direction of the rotor core; recesses are provided on the axial end surfaces of the second permanent magnets; the recesses project onto on one end surface of the rotor core in the axial direction of the rotor core, and in that projection plane, the recesses are located in the slots. The rotor structure of the present application can improve the magnetic flux concentration effect and overload capacity of motors, and has few parts, few assembly steps, simple assembly and low production cost.

Description

Rotor structure and motor

[0001] This application claims priority to Chinese invention patent application number "202410946185.9", application date "July 15, 2024", entitled "Rotor Structure and Motor".

[0002] This application claims priority to Chinese invention patent application number "202411628862.9", filed on "November 14, 2024", entitled "Rotor Structure and Motor". Technical Field

[0003] This application relates to the field of motor technology, and more specifically, to a rotor structure and a motor. Background Technology

[0004] With the improvement of motor energy efficiency standards, higher requirements are placed on the energy efficiency level of motors. For permanent magnet motors, it is necessary to further improve the efficiency and torque density of the motors.

[0005] Currently, there are two main technical approaches to improve motor efficiency and torque density. One approach is to incorporate permanent magnets to achieve a larger air gap magnetic flux and a greater magnetic density. However, due to the fixed rotor magnetic circuit structure, the improvement in energy efficiency is limited. Another approach is to increase the motor's salient pole ratio and magnetic reluctance torque by utilizing the rotor structure to compensate for the lack of permanent magnet torque. Its efficiency can be comparable to that of a permanent magnet motor, but it usually requires a larger rotor volume, which makes the motor's torque density inferior to that of a permanent magnet motor.

[0006] Therefore, for current motors, how to further improve motor efficiency and torque density is an urgent problem to be solved.

[0007] Prior art document 201880064666.X discloses a permanent magnet rotor assembly. This assembly contains two sets of permanent magnets (one set magnetized circumferentially along the rotor, and the second set providing magnetic flux axially along the rotor) that generate magnetic flux concentrated through pole pieces. An end plate made of magnetic material is present. Circumferentially magnetized magnets are placed in the circumferential gap between the pole pieces, and magnets providing axial magnetic flux are placed in the gap between the pole piece array and the end plate. The magnetic end plate in the prior art document provides a return path for the magnetic flux from the magnets providing axial magnetic flux. However, in the home appliance industry, rotor structures involving multiple magnetic pole pieces, multiple dispersed magnets, and magnetic end plates have numerous components, are difficult to fix in place, and have high assembly difficulty, resulting in high production and assembly costs and hindering practical application. Summary of the Invention

[0008] The main objective of this application is to provide a rotor structure and motor that can improve the motor's magnetization effect and overload capacity, and has fewer parts, fewer assembly steps, simpler assembly, and lower production costs.

[0009] To achieve the above objectives, according to one aspect of this application, a rotor structure is provided, including a rotor core, a first permanent magnet, and a second permanent magnet. The rotor core has a mounting groove, and the first permanent magnet is mounted in the mounting groove. Along the axial direction of the rotor core, the axial height of the first permanent magnet is greater than the axial height of the rotor core. The second permanent magnet is disposed at the axial end of the rotor core, and a groove is provided on the second permanent magnet. The portion of the first permanent magnet extending axially from the rotor core is inserted into the groove. The first permanent magnet is magnetized along the radial direction and / or tangential direction of the rotor core, and the second permanent magnet is magnetized along the axial direction of the rotor core. A recess is provided on the axial end face of the second permanent magnet on the side away from the rotor core. The recess on the second permanent magnet does not penetrate the second permanent magnet along the axial direction. Projected along the axial direction of the rotor core onto one end face of the rotor core, the recess is located within the groove in the projection plane.

[0010] In some embodiments, the recesses are evenly distributed along the circumferential direction of the second permanent magnet.

[0011] In some embodiments, the number of recesses is p or 2p, where p is the number of rotor pole pairs.

[0012] In some embodiments, the second permanent magnet is provided with a hole structure, and the rotor core is provided with a through hole, wherein at least one hole structure and at least one through hole are connected along the axial direction of the rotor core.

[0013] In some embodiments, 2p is an integer multiple of the number of hole structures provided on the second permanent magnet, where p is the number of rotor pole pairs.

[0014] In some embodiments, a projection is made on one end face of the rotor core along the axial direction of the rotor core. In this projection plane, there is an angle α between the line connecting the rotor central axis and the geometric center of any recess and the line connecting the rotor central axis and the geometric center of any hole structure. α is an integer multiple of 360 / 4p.

[0015] In some embodiments, the second permanent magnet is an injection-molded magnet.

[0016] In some embodiments, a protrusion is formed between adjacent grooves and projected onto one end face of the rotor core along the axial direction of the rotor core. In this projection plane, the radial width of the groove is smaller than the radial width of the protrusion.

[0017] In some embodiments, on a plane perpendicular to the axial direction of the rotor core, the length of the line connecting the rotor central axis and any point on the end edge of the second permanent magnet near the shaft is Di2, and the length of the line connecting the rotor central axis and the center of the end edge of the first permanent magnet near the shaft is Di3, min(Di2)≥Di3.

[0018] In some embodiments, the second permanent magnet has an outer peripheral surface near the air gap side and an inner peripheral surface near the shaft side, and at least one window is provided on the outer peripheral surface and / or the inner peripheral surface of the second permanent magnet.

[0019] In some embodiments, the recess is located radially inside the window along the radial direction of the second permanent magnet, and the recess is located on the side of the second permanent magnet closer to the window.

[0020] In some embodiments, the grooves provided on the second permanent magnet do not penetrate the second permanent magnet, and the number of grooves is the same as the number of rotor poles.

[0021] In some embodiments, on a plane perpendicular to the axial direction of the rotor core, a polar region of the protrusion is adapted to the shape of a corresponding polar region of the rotor core, and the polar region of the protrusion fills the corresponding polar region of the rotor core.

[0022] In some embodiments, after the first permanent magnet and the second permanent magnet are magnetized, they are divided into multiple polarity regions. The magnetization directions of adjacent polarity regions of the second permanent magnet are opposite. The polarity of one polarity region of the second permanent magnet is the first polarity on the side closer to the rotor core. The polarity of the two first permanent magnets on the adjacent sides of the polarity region of the second permanent magnet is the first polarity on the side closer to the rotor core corresponding to the polarity region.

[0023] According to another aspect of this application, an electric motor is provided, including a stator structure and a rotor structure, wherein the rotor structure is the rotor structure described above, and the stator structure is sleeved on the outer periphery of the rotor structure.

[0024] According to the technical solution of this application, the rotor structure includes a rotor core, a first permanent magnet, and a second permanent magnet. The rotor core has a mounting groove, and the first permanent magnet is installed in the mounting groove. Along the axial direction of the rotor core, the axial height of the first permanent magnet is greater than the axial height of the rotor core. The second permanent magnet is disposed at the axial end of the rotor core, and a groove is provided on the second permanent magnet. The portion of the first permanent magnet extending axially out of the rotor core is inserted into the groove. The first permanent magnet is magnetized along the radial and / or tangential direction of the rotor core. A recess is provided on the axial end face of the second permanent magnet on the side away from the rotor core. The recess on the second permanent magnet does not penetrate the second permanent magnet along the axial direction. Projected along the axial direction of the rotor core onto one end face of the rotor core, the recess is located within the groove in the projection plane.

[0025] By simultaneously incorporating a first permanent magnet and a second permanent magnet in the rotor, the first and second permanent magnets jointly provide magnetic flux to the motor, thereby increasing the motor's output power. The design of the relative positions of the first and second permanent magnets, with the first permanent magnet inserted into the groove of the second permanent magnet, allows the first permanent magnet to serve as part of the magnetic flux path of the second permanent magnet, drawing the magnetic flux lines of the second permanent magnet into the rotor core. After the magnetic flux lines of the first and second permanent magnets are magnetized on the rotor core, they then enter the air gap and stator, significantly improving the rotor's magnetization effect. Furthermore, apart from the rotor core, no other magnetically conductive components are present in the rotor structure, resulting in fewer parts, fewer assembly steps, simpler assembly, and lower production costs. Simultaneously, the axial end leakage magnetic flux lines of the first permanent magnet need to form a closed loop through the second permanent magnet. The non-magnetically conductive second permanent magnet weakens the end leakage magnetic flux of the first permanent magnet, and the flow direction of the magnetic flux lines of the second permanent magnet is opposite to that of the end leakage magnetic flux lines of the first permanent magnet, creating a mutual repulsion effect. This further reduces the axial end leakage magnetic flux of the first permanent magnet, increasing the rotor's magnetic field strength. A recess is provided on the axial end face of the second permanent magnet. This recess serves two purposes: firstly, it acts as a positioning structure during the forming process of the second permanent magnet; secondly, it forms the sealing area after the second permanent magnet is formed. Projecting a view along the axial direction of the rotor core onto one end face of the rotor core, the recess is located within a groove in this projection plane. This is because the magnetic pole boundary lines of adjacent polarity regions of the second permanent magnet are located on the groove. Positioning the recess within the groove allows for more accurate positioning of the different polarity regions of the second permanent magnet. Furthermore, it reduces the influence of the recess on the magnetism of the second permanent magnet during sealing after forming, increasing the contribution of the second permanent magnet to the rotor's magnetic flux linkage and improving the motor's overload capacity. Attached Figure Description

[0026] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0027] Figure 1 shows a perspective structural diagram of the rotor structure of an embodiment of this application;

[0028] Figure 2 shows a partially exploded structural diagram of the rotor structure of an embodiment of this application;

[0029] Figure 3 shows a top view of the rotor structure of an embodiment of this application;

[0030] Figure 4 shows a cross-sectional view along line AA of Figure 3;

[0031] Figure 5 shows a side view of the rotor structure of an embodiment of this application;

[0032] Figure 6 shows a sectional view along the BB direction of Figure 5;

[0033] Figure 7 shows a three-dimensional structural diagram of the second permanent magnet in the rotor structure of an embodiment of this application;

[0034] Figure 8 shows a bottom view of the second permanent magnet in the rotor structure of an embodiment of this application;

[0035] Figure 9 shows a perspective view of a portion of the rotor structure according to an embodiment of this application;

[0036] Figure 10 shows a top view of a portion of the rotor structure according to an embodiment of this application;

[0037] Figure 11 shows a top view of a rotor structure according to another embodiment of this application;

[0038] Figure 12 shows a bottom view of the second permanent magnet in the rotor structure of another embodiment of this application;

[0039] Figure 13 is a side view of the motor structure according to an embodiment of this application;

[0040] Figure 14 shows a schematic diagram of the polarity direction of the rotor structure of this application;

[0041] Figure 15 shows the magnetic circuit schematic diagram of the rotor structure of this application;

[0042] Figure 16 shows a comparison of the magnetic flux density of the motor in the embodiment of this application and the motor in related technologies;

[0043] Figure 17 shows a comparison of the leakage flux coefficients of the motor in the embodiment of this application and motors in related technologies;

[0044] Figure 18 shows a comparison of the no-load magnetic flux of the motor of the embodiment of this application and the motor of related technologies;

[0045] Figure 19 shows a comparison of the air gap magnetic flux density of the motor of the embodiment of this application and the motor of related technologies;

[0046] Figure 20 shows a comparison of the torque-current characteristics of the motor of the embodiment of this application and the motor of related technologies;

[0047] Figure 21 shows a comparison of torque ripple between the motor of the embodiment of this application and the motor of related technologies;

[0048] Figure 22 shows a perspective structural diagram of a rotor structure according to another embodiment of this application;

[0049] Figure 23 shows a top view of the second permanent magnet of a rotor structure according to another embodiment of this application;

[0050] Figure 24 shows a three-dimensional structural diagram of the second permanent magnet of a rotor structure according to another embodiment of this application.

[0051] The above-mentioned figures include the following reference numerals: 11, rotor core; 111, limiting protrusion; 112, opening slot; 113, through hole; 12, first permanent magnet; 21, second permanent magnet; 211, hole structure; 212, marking part; 213, groove; 214, protrusion; 215, recess; 216, countersunk part; 217, window; 218, first magnetic zone; 219, second magnetic zone; 31, stator core. Detailed Implementation

[0052] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0053] Referring to Figures 1 to 15, according to an embodiment of this application, the rotor structure includes a rotor core 11, a first permanent magnet 12, and a second permanent magnet 21. The rotor core 11 has a mounting groove, and the first permanent magnet 12 is mounted in the mounting groove. Along the axial direction of the rotor core 11, the axial height of the first permanent magnet 12 is greater than the axial height of the rotor core 11. The second permanent magnet 21 is disposed at the axial end of the rotor core 11, and a groove 213 is provided on the second permanent magnet 21. The portion of the first permanent magnet 12 extending axially from the rotor core 11 is inserted into the groove 213. The first permanent magnet 12 is magnetized along the radial direction and / or tangential direction of the rotor core 11, and the second permanent magnet 21 is magnetized along the axial direction of the rotor core 11.

[0054] As shown in Figure 15, a first permanent magnet 12 and a second permanent magnet 21 are simultaneously arranged in the rotor. The first permanent magnet 12 and the second permanent magnet 21 together provide magnetic flux to the motor, which can increase the output power of the motor. The relative positions of the first permanent magnet 12 and the second permanent magnet 21 are designed such that the first permanent magnet 12 is inserted into the groove 213 of the second permanent magnet 21. The first permanent magnet 12 serves as part of the magnetic flux path of the second permanent magnet 21, pulling the magnetic flux of the second permanent magnet 21 into the rotor core 11. The magnetic flux of the first permanent magnet 12 and the second permanent magnet 21 in the rotor core 11... After the magnet is concentrated, it enters the air gap and stator, which can greatly improve the magnetization effect of the rotor. In addition, apart from the rotor core 11, no other magnetic conductive components are set in the rotor structure. The leakage magnetic field lines at the axial end of the first permanent magnet 12 need to form a closed loop through the second permanent magnet 21. The non-magnetic conductive component, the second permanent magnet 21, weakens the end leakage magnetic field of the first permanent magnet 12. Moreover, the flow direction of the magnetic field lines of the second permanent magnet 21 is opposite to the flow direction of the end leakage magnetic field lines of the first permanent magnet 12, resulting in a mutual repulsion effect. This will further reduce the axial end leakage magnetic field of the first permanent magnet 12 and improve the rotor magnetic field strength.

[0055] The design of the first permanent magnet 12 and the second permanent magnet 21 in the rotor structure provides a return magnetic path for the magnetic flux of the second permanent magnet 21 through the first permanent magnet 12. There is no need to add an additional magnetic end plate to cooperate with the magnetic path of the second permanent magnet 21. This eliminates the dependence of the second permanent magnet 21 on the magnetic end plate. At the same time, it reduces the number of rotor parts, resulting in fewer assembly steps, simpler assembly, and lower production costs.

[0056] In one embodiment, the first permanent magnet 12 is magnetized along the radial and / or tangential direction of the rotor core 11, and the second permanent magnet 21 is magnetized along the axial direction of the rotor core 11. The magnetic lines of force entering the rotor core 11 from different directions create a magnetic focusing effect on the rotor core 11, increasing the rotor magnetic field strength and simultaneously increasing the utilization rate of the rotor core 11.

[0057] As shown in Figure 15, in this embodiment, the first permanent magnet 12 with a larger axial height is set to tangential magnetization, and the second permanent magnet 21 set at the axial end of the rotor core 11 is set to axial magnetization. This can realize the continuity of the magnetic flux of the first permanent magnet 12 and the second permanent magnet 21, so that the two can more effectively provide magnetic flux to the motor and effectively increase the motor output.

[0058] In one embodiment, the first permanent magnet 12 is a combined magnet design of tangential magnetization and radial magnetization.

[0059] In one embodiment, the magnetization direction of the second permanent magnet 21 is not limited to being parallel to the axial direction of the rotor core 11, but can also be at an acute angle to the axial direction of the rotor core 11.

[0060] In one embodiment, a recess 215 is provided on the axial end face of the second permanent magnet 21. Projected along the axial direction of the rotor core 11 onto one end face of the rotor core 11, the recess 215 is located within the groove 213 within this projection plane. The recess 215 on the axial end face of the second permanent magnet 21 serves two purposes: firstly, it acts as a positioning structure during the forming process of the second permanent magnet 21; secondly, it serves as a sealing area after the second permanent magnet 21 has been formed. Projecting a projection along the axial direction of the rotor core 11 onto one end face of the rotor core 11, the recess 215 is located within the groove 213. This is because the magnetic pole boundary line of adjacent polarity regions of the second permanent magnet 21 is located on the groove 213. Positioning the recess 215 within the groove 213 allows for more accurate positioning of different polarity regions of the second permanent magnet 21. Furthermore, it reduces the influence of the recess 215 on the magnetism of the second permanent magnet 21 during the sealing process after molding, increasing the contribution of the second permanent magnet 21 to the rotor's magnetic flux linkage and improving the motor's overload capacity. Additionally, as the sealing area after molding the second permanent magnet 21, the area where the recess 215 is located cannot be blocked by other media along the axial direction, as this would inevitably affect the magnetization intensity of the area. Positioning the recess 215 within the groove 213 maximizes the reduction of its influence on the magnetism of the second permanent magnet 21.

[0061] In one embodiment, the recess 215 on the second permanent magnet 21 does not penetrate the second permanent magnet 21 in the axial direction. The recess 215 is a pit on the axial end face of the second permanent magnet 21, which is recessed to a certain depth along the axial direction from the axial end face of the second permanent magnet 21, but does not penetrate the second permanent magnet 21.

[0062] In one embodiment, the recess 215 is provided on the axial end face of the second permanent magnet 21 on the side away from the rotor core 11. This arrangement can increase the probability of forming the second permanent magnet 21 and reduce the manufacturing cost and difficulty.

[0063] In one embodiment, the recesses 215 are evenly distributed along the circumference of the second permanent magnet 21. The even distribution of the recesses 215 can increase the dynamic balance accuracy of the rotor and reduce motor vibration noise.

[0064] In one embodiment, the number of recesses 215 is p or 2p, where p is the number of rotor pole pairs. The number of recesses 215 corresponds to the number of rotor poles or pole pairs to reduce the pressure required during the manufacture of the second permanent magnet 21, thus making the manufacturing and shaping of the second permanent magnet 21 more efficient. The cross-sectional shape of the recesses 215 is not limited to any shape composed of straight lines and / or arcs. In one embodiment, the cross-sectional shape of the recesses 215 is circular or elliptical.

[0065] In one embodiment, the second permanent magnet 21 is provided with a hole structure 211, and the rotor core 11 is provided with a through hole 113. At least one hole structure 211 and at least one through hole 113 are connected along the axial direction of the rotor core 11. The shape of the hole structure 211 and the through hole 113 is not limited to circular, elliptical, square or other shapes.

[0066] On the one hand, the magnetic lines of force of the second permanent magnet 21 enter the rotor core 11 after being guided by the end face of the rotor core 11, becoming the main magnetic field. The hole structure 211 on the second permanent magnet 21 corresponds to the through hole 113 on the rotor core 11, which can improve the utilization rate of the second permanent magnet 21 and the rotor core 11. At the same time, the magnetic field of the second permanent magnet 21 can be guided by the reasonable design of the position and shape of the hole structure 211, ensuring the uniformity and unsaturation of the magnetic field distribution of the rotor core 11 and reducing rotor iron loss. On the other hand, the hole structure 211 on the second permanent magnet 21 and the through hole 113 on the rotor core 11 can be used together as a positioning tool during rotor assembly, improving assembly accuracy and simplifying the assembly process. In addition, the hole structure 211 on the second permanent magnet 21 and the through hole 113 on the rotor core 11 can be used together as a flow path for the molding compound during the molding of the rotor structure, increasing the success rate of the molding process. The hole structure 211 on the second permanent magnet 21 and the through hole 113 on the rotor core 11 can be used together to insert fasteners to fix the rotor assembly together, which can improve the reliability of the rotor during operation.

[0067] In one embodiment, the hole structure 211 on the second permanent magnet 21 and the through hole 113 on the rotor core 11 are both filled with rotor encapsulant.

[0068] In one embodiment, rivets pass through the hole structure 211 on the second permanent magnet 21 and the through hole 113 on the rotor core 11, and are riveted together by riveting.

[0069] In one embodiment, the hole structure 211 on the second permanent magnet 21 and the through hole 113 on the rotor core 11 are not filled with any material and serve only as magnetic field guiding holes.

[0070] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the hole structure 211 on the second permanent magnet 21 is located near the radial inner side of the second permanent magnet 21. The hole structure 211 organizes and guides the magnetic lines of force on the radial inner side of the second permanent magnet 21, thereby limiting the area of ​​action of the magnetic lines of force of the second permanent magnet 21.

[0071] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the length of the line connecting the center of the hole structure 211 to any point on the end edge of the second permanent magnet 21 near the shaft is Di4, and the length of the line connecting the center of the hole structure 211 to any point on the end edge of the second permanent magnet 21 near the air gap is Di5, where min(Di4) ≤ min(Di5). In one embodiment, min(Di4) < min(Di5). This further restricts the position of the hole structure 211, allowing it to organize and guide the magnetic lines of force of the second permanent magnet 21, thereby reducing the repulsive force of the second permanent magnet 21 on the first permanent magnet 12 and simplifying assembly and manufacturing.

[0072] In one embodiment, a projection is made onto one end face of the rotor core 11 along its axial direction. Within this projection plane, an angle α exists between the line connecting the rotor central axis and the geometric center of any recess 215 and the line connecting the rotor central axis and the geometric center of any hole structure 211. α is an integer multiple of 360 / 4π. The recesses 215 and hole structures 211 are positioned offset in the circumferential direction of the second permanent magnet 21 to reduce the risk of localized weakness in the second permanent magnet 21 and ensure that the second permanent magnet 21 possesses sufficient structural strength.

[0073] In one embodiment, the second permanent magnet 21 is provided with a groove 216, which is located on the end face of the second permanent magnet 21 near the rotor core 11. On the one hand, the groove 216 can reduce the volume of raw materials used in the second permanent magnet 21, thereby reducing the material cost of the second permanent magnet 21; on the other hand, the groove 216 can be used for positioning the second permanent magnet 21 during the molding process, reducing the molding difficulty of the second permanent magnet 21.

[0074] In one embodiment, the recess 216 is disposed on the groove 213 of the second permanent magnet 21 so that the recess 216 does not affect the area of ​​the magnetizing surface of the second permanent magnet 21.

[0075] In one embodiment, a marking portion 212 is provided on the second permanent magnet 21. The marking portion 212 is used to identify the polarity order of the second permanent magnet 21, and the marking portion 212 is not limited to letter marking, shape marking or other forms of marking.

[0076] In one embodiment, the marking portion 212 is disposed on the end face of the second permanent magnet 21 on the side near and / or away from the rotor core 11. In another embodiment, the marking portion 212 is disposed on the end face of the second permanent magnet 21 on both the side near and away from the rotor core 11, that is, the marking portion is disposed on both axial end faces of the second permanent magnet 21, which facilitates the identification of the polarity of the second permanent magnet 21.

[0077] In one embodiment, the marking portion 212 is disposed in the adjacent area of ​​a hole structure 211. The cooperation between the marking portion 212 and the hole structure 211 ensures the uniqueness of the polarity sequence of the second permanent magnet 21 after it is magnetized.

[0078] In one embodiment, the number of hole structures 211 provided on the second permanent magnet 21 is not less than two. This ensures the symmetry of the rotor magnetic field and reduces torque pulsation and harmonic losses caused by magnetic field asymmetry. In one embodiment, 2p is an integer multiple of the number of hole structures 211 provided on the second permanent magnet 21. In one embodiment, the number of hole structures 211 provided on the second permanent magnet 21 is p or 2p, where p is the number of rotor pole pairs.

[0079] In one embodiment, a rivet is built into the hole structure 211. The rivet passes through the hole structure 211 on the second permanent magnet 21 and enters the through hole 113 on the rotor core 11. It extends from the other end face of the rotor assembly and is riveted and fastened to achieve the assembly of the rotor assembly.

[0080] In one embodiment, the second permanent magnet 21 is an injection-molded magnet. Using injection-molded magnets can reduce rotor saturation and iron loss; on the other hand, injection-molded magnets have higher shape freedom, which can reduce the manufacturing difficulty of the second permanent magnet 21 and the rotor structure.

[0081] In one embodiment, the second permanent magnet 21 is injection-molded ferrite or injection-molded neodymium iron boron, and the second permanent magnet 21 can also be injection-molded magnet of other material types.

[0082] In one embodiment, at least one end of the axial end of the rotor core 11 is provided with a second permanent magnet 21, and the number of second permanent magnets 21 provided in the rotor structure is not less than one. In one embodiment, the number of second permanent magnets 21 provided in the rotor structure is two, that is, second permanent magnets 21 are provided at both axial ends of the rotor core 11, thereby improving the magnetic circuit at the motor end, resulting in higher torque density, higher motor efficiency, and ensuring high motor performance. The rotor core 11 and the second permanent magnets 21 are attached together axially to reduce the loss of magnetic flux in the second permanent magnets 21 during flow. It should be noted that the single second permanent magnet 21 here refers to all the second permanent magnets 21 located on a certain axial plane at the axial end of the rotor core 11. However, the single second permanent magnet 21 is not limited to an integral structure or a segmented structure.

[0083] In one embodiment, when the single second permanent magnet 21 has a segmented structure, the number of its segments is not limited to two or more.

[0084] In one embodiment, the second permanent magnet 21 cooperates with the first permanent magnet 12 through a groove 213 provided thereon. Both the first permanent magnet 12 and the second permanent magnet 21 are magnetic flux sources. Apart from the rotor core 11, no other magnetic conductive components are provided in the rotor structure.

[0085] In one embodiment, the grooves 213 on the second permanent magnet 21 do not penetrate the second permanent magnet 21. The number of grooves 213 is the same as the number of rotor magnetic poles, and protrusions 214 are formed between adjacent grooves 213. The grooves 213 do not penetrate the second permanent magnet 21, making the second permanent magnet 21 a single unit. As shown in Figure 2, in one embodiment of this application, a protrusion 214 is formed between two adjacent grooves, and the outer and inner sides of the two adjacent protrusions 214 are disconnected, which can reduce the processing difficulty of the second permanent magnet 21 and lower the processing cost. In another embodiment of this application, a protrusion 214 is formed between two adjacent grooves 213, and the outer side of the two adjacent protrusions 214 is disconnected, which can reduce magnetic leakage at the outer circumference of the rotor. To ensure rotor strength, a magnetic bridge is provided on the inner side of the rotor core 11. The second permanent magnet 21 connected to the inner side of the protrusion 214 helps the magnetic bridge saturate, reducing the magnetic leakage of the first permanent magnet 12 at the inner magnetic bridge. In another embodiment of this application, a protrusion 214 is formed between two adjacent grooves 213. The outer sides of two adjacent protrusions 214 are connected, while the inner sides are disconnected. This increases the strength of the outer circumference of the second permanent magnet 21 and reduces magnetic leakage on the inner side of the rotor. In another embodiment of this application, to ensure the overall strength of the second permanent magnet 21, the outer sides of two adjacent protrusions 214 are connected, and the inner sides are also connected.

[0086] In one embodiment, a polar region of the protrusion 214 corresponds to a polar region of the rotor core 11. That is, a polar region of the protrusion 214 of the second permanent magnet 21 generates magnetic flux, and a corresponding polar region of the rotor core 11 forms the magnetic path of this magnetic flux. The corresponding arrangement of the two can shorten the magnetic path as much as possible and reduce magnetic loss.

[0087] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the shape of a polar region of the protrusion 214 is adapted to the shape of a corresponding polar region of the rotor core 11, and the polar region of the protrusion 214 completely fills the corresponding polar region of the rotor core 11. Here, "completely fills" means that there is no gap between the protrusion 214 and the rotor core 11 on the plane perpendicular to the axial direction of the rotor core 11.

[0088] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the radial width of the second permanent magnet 21 is c1, the radial width of the groove 213 is c2, and the radial width of the protrusion 214 is c3. Then, 0.3≤min(c2) / max(c1)≤1, 0≤min(c3) / max(c1)≤1. In another embodiment, 0.7≤min(c2) / max(c1)≤0.95, that is, the groove 213 and the protrusion 214 may have radial widths that are not equal to those of the second permanent magnet 21. The appropriate radial widths of the groove and the protrusion are selected according to the assembly requirements and the rotor saturation degree. If the rotor saturation degree is too high, a smaller c3 / c1 value can be selected; if it is necessary to reduce the assembly difficulty, a smaller c2 / c1 value can be selected. It should be noted that the "radial width of the second permanent magnet 21" in this application is defined as the distance between two points where the line connecting the rotor's central axis and any point on the outer circle of the rotor intersects the second permanent magnet 21 on a plane perpendicular to the axial direction of the rotor core 11. The definition of the "radial width" of other components or structures is similar.

[0089] In one embodiment, a projection is made on one end face of the rotor core 11 along the axial direction. Within this projection plane, the radial width of the groove 213 is smaller than the radial width of the protrusion 214. As shown in Figure 12, two adjacent protrusions are connected by a groove. Setting the radial width of the groove of the second permanent magnet to be smaller than the radial width of the protrusion weakens the self-short circuit portion of the magnetic field lines of the protrusion passing through the groove, improving the utilization rate of the second permanent magnet. On the other hand, the smaller radial width of the groove allows the magnetic field lines of the protrusion to selectively enter the rotor core, becoming effective magnetic flux, further improving the utilization rate of the second permanent magnet. In addition, the portion of the groove smaller than the protrusion allows the first permanent magnet and the rotor core, which are located along the rotor axial direction, to be directly exposed on the rotor end face, which is more conducive to the assembly and positioning of the rotor assembly or the molding of the rotor structure.

[0090] In one embodiment, the length of the line connecting the rotor central axis and any point on the end edge of the groove 213 near the air gap is Do5, and the length of the line connecting the rotor central axis and any point on the end edge of the protrusion 214 near the air gap is Do6. Then max(Do5) < max(Do6) to reduce the self-short-circuit leakage flux of the protrusion 214 near the air gap.

[0091] In one embodiment, the length of the line connecting the rotor central axis and any point on the end edge of the groove 213 near the shaft side is Di6, and the length of the line connecting the rotor central axis and any point on the end edge of the protrusion 214 near the shaft side is Di7. Then max(Di6)≥min(Di7) to reduce the self-short-circuit leakage flux of the protrusion 214 near the shaft side.

[0092] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the radial width of the groove 213 is c2, and the radial width of the protrusion 214 is c3, then 0.3 ≤ min(c2) / max(c3) < 1. In one embodiment, 0.55 ≤ min(c2) / max(c3) ≤ 0.98. In another embodiment, 0.7 ≤ min(c2) / max(c3) ≤ 0.95. By limiting the ratio of the radial width of the groove 213 to the radial width of the protrusion 214, the groove 213 weakens the self-short-circuit leakage magnetic flux of the protrusion 214 without affecting the magnetic flux of the second permanent magnet 21, effectively improving the utilization rate of the second permanent magnet 21.

[0093] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the radial width of the second permanent magnet 21 is c1, and the radial width of the hole structure 211 is c4. Therefore, 0.05 ≤ max(c4) / max(c1) ≤ 0.3. In another embodiment, 0.06 ≤ max(c4) / max(c1) ≤ 0.25. The radial width of the hole structure 211 refers to the distance between two points on a plane perpendicular to the axial direction of the rotor core 11, where the line connecting the rotor's central axis and any point on the rotor's outer circle intersects the hole structure 211. Limiting the minimum percentage of the radial width of the hole structure 211 ensures it has a certain width, guaranteeing its guiding effect on the magnetic field of the second permanent magnet 21. Limiting the maximum percentage of the radial width of the hole structure 211 reduces its influence on the magnetizing area of ​​the second permanent magnet 21, ensuring the second permanent magnet 21 contributes a certain amount of magnetic flux.

[0094] In one embodiment, on the outer circumference of the second permanent magnet 21 near the air gap side, on a plane perpendicular to the axial direction of the rotor core 11, the groove 213 has a tangential dimension of d1 and the protrusion 214 has a tangential dimension of d2, then d1 / d2 ≥ 0.2. Limiting the minimum value of d1 / d2 can reduce the saturation of the rotor core 11 and increase the flux utilization of the second permanent magnet 21.

[0095] In one embodiment, the first permanent magnet 12 and the second permanent magnet 21 are divided into multiple polarity regions after being magnetized. The first permanent magnet 12 is alternately magnetized with its N and S poles along the radial and / or tangential directions of the rotor core 11; the second permanent magnet 21 is alternately magnetized with its N and S poles along the axial direction of the rotor core 11.

[0096] The magnetization directions of adjacent polarity regions of the second permanent magnet 21 are opposite. The polarity of one polarity region of the second permanent magnet 21 near the rotor core 11 is the first polarity, and the polarity of the two first permanent magnets 12 on both sides adjacent to this polarity region of the second permanent magnet 21 near the rotor core 11 is also the first polarity. That is, the polarity of one polarity region of the second permanent magnet 21 near the rotor core 11 is the same as the polarity of the two first permanent magnets 12 on both sides adjacent to the second permanent magnet 21 near the rotor core 11. In the embodiment shown in Figure 14, the second permanent magnet 21 is axially magnetized, and the first permanent magnet 12 is tangentially magnetized. Under a certain pole, the magnetization direction of both points to the rotor core 11. Under this magnetization method, the magnetic flux of the first permanent magnet 12 and the second permanent magnet 21 can be superimposed, thereby increasing the no-load magnetic flux.

[0097] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the area of ​​a polar region of the second permanent magnet 21 is s1, and the area of ​​the outer surface of the rotor core 11 along the axial direction is s2. Therefore, 0.2 ≤ 2p*s1 / s2 ≤ 2.2. The second permanent magnet 21 is a flux source, and the rotor core 11 is a magnetically conductive structure. The flux of the second permanent magnet 21 passes through the rotor core 11 and the air gap sequentially before entering the stator side. The outer surface of the rotor core 11 is directly connected to the air gap. Limiting the minimum value of the magnetizing area of ​​the second permanent magnet 21 and the outer surface area of ​​the rotor core 11 ensures that the rotor core 11 carries a certain amount of flux from the second permanent magnet 21, improving the utilization rate of the rotor core 11. Limiting the maximum value of the magnetizing area of ​​the second permanent magnet 21 and the outer surface area of ​​the rotor core 11 limits the maximum flux carried by the second permanent magnet 21 on the rotor core 11, reducing the saturation degree of the rotor core 11 and reducing losses.

[0098] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the area of ​​one polar region of the rotor core 11 is s6, the area of ​​one polar region of the second permanent magnet 21 is s1, and along the axial direction of the rotor core 11, the area of ​​one polar region of the first permanent magnet 12 is s5. Therefore, 2 ≤ (s1 + s5) / s6 ≤ 10. It should be noted that s5 refers to the area of ​​the magnetic supply surface of one polar region of the first permanent magnet 12. The rotor core 11 carries the magnetic flux of both the second permanent magnet 21 and the first permanent magnet 12. Limiting the ratio of the sum of the magnetic supply surface areas of the first and second permanent magnets 21 to the axial magnetic guide surface area of ​​the rotor core 11 improves the utilization rate of the rotor core 11 while ensuring that the rotor core 11 has a suitable degree of saturation.

[0099] In one embodiment, the axial height of the rotor core 11 is x, the axial height of the first permanent magnet 12 is y, y > x, the axial height of the second permanent magnet 21 is z1, and the axial height of the protrusion 214 is z2, where 0.2*(yx)≤z1≤1.6*(yx).

[0100] In one embodiment, 2*z2≥(yx) can avoid interference between the first permanent magnet 12 and the second permanent magnet 21, so as to realize the assembly of the first permanent magnet 12 and the second permanent magnet 21.

[0101] In one embodiment, z2 = 0.5*(yx) can form an optimal fit, effectively avoiding the gap between the first permanent magnet 12 and the second permanent magnet 21, and reducing magnetic loss.

[0102] In one embodiment, 0.03≤(z1-z2) / z1≤0.7 allows the portion of the groove 213 that does not penetrate the second permanent magnet 21 to have a certain axial thickness proportion in the second permanent magnet 21, so as to ensure the structural strength of the second permanent magnet 21.

[0103] In one embodiment, along the axial direction of the rotor core 11, the axial height of the second permanent magnet 21 is z1, the axial height of the rotor core 11 is x, and the axial height of the groove 213 is z3. Therefore, 0.2 ≤ z3 / z1 ≤ 1, and 0.05 ≤ z3 / x ≤ 0.6. Limiting the z3 / z1 ratio ensures that the groove 213 has a certain axial height, simplifying the assembly process of each rotor component. Limiting the z3 / x ratio ensures that each flux source has a suitable ratio, guaranteeing that the rotor has a suitable degree of saturation. A suitable flux source ratio also helps improve the torque linearity of the motor.

[0104] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the length of the line connecting the rotor central axis and any point on the end edge of the second permanent magnet 21 near the shaft side is Di2, the inner diameter of the rotor core 11 is Di1, and min(Di2)≥0.5*Di1. In another embodiment, min(Di2)≥1.2*Di1. A shaft needs to be assembled at the inner hole of the rotor core 11. The above dimensional relationship allows for space for the shaft assembly; furthermore, without affecting the shaft assembly, the inner hole of the second permanent magnet 21 can be filled with molding compound or other materials to enhance rotor strength.

[0105] In one embodiment, min(Di2) = 0.5*Di1, that is, the inner diameter of the second permanent magnet 21 is the same as the inner diameter of the rotor core 11, which can increase the magnetizing surface of the second permanent magnet 21 and improve the magnetic flux contribution of the second permanent magnet 21.

[0106] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the length of the line connecting the rotor central axis to any point on the end edge of the second permanent magnet 21 near the shaft is Di2, and the length of the line connecting the rotor central axis to the center of the end edge of the first permanent magnet 12 near the shaft is Di3, where max(Di2) ≥ 0.75 * Di3. In one embodiment, max(Di2) ≥ Di3. In another embodiment, min(Di2) ≥ Di3. Near the shaft, on the one hand, the magnetic circuit area of ​​the rotor core 11 is too small, and the core is easily saturated; on the other hand, the permanent magnet at this location contributes little to the torque, resulting in low utilization of the permanent magnet. Therefore, limiting the relationship between Di2 and Di3 can improve the utilization rate of the second permanent magnet 21 while reducing the saturation degree of the rotor core 11 and reducing losses. In addition, limiting the positional relationship between the second permanent magnet and the first permanent magnet near the shaft can also limit the effective area of ​​the magnetic flux of the second permanent magnet and the effective area of ​​the magnetic flux of the first permanent magnet, weaken the repulsive force between the second permanent magnet and the first permanent magnet, and reduce the assembly difficulty.

[0107] In one embodiment, the second permanent magnet 21 has an outer peripheral surface near the air gap side and an inner peripheral surface near the shaft side. At least one window 217 is provided on the outer peripheral surface and / or the inner peripheral surface of the second permanent magnet 21. In one embodiment, windows 217 are provided on both the outer peripheral surface and the inner peripheral surface of the second permanent magnet 21; as shown in FIG7, in one embodiment, windows 217 are provided on the outer peripheral surface of the second permanent magnet 21. Each end edge of the window 217 is a straight line, an arc, or any combination of a straight line and an arc. Providing windows on the outer peripheral surface near the air gap side and / or the inner peripheral surface near the shaft side of the second permanent magnet can limit the effective area of ​​the magnetic flux of the second permanent magnet, allowing the second permanent magnet to have a suitable magnetic field strength near the air gap side or near the shaft side, weakening the repulsive force of the second permanent magnet on the first permanent magnet, and reducing assembly difficulty. Furthermore, the window can also serve as a positioning structure during rotor assembly, improving assembly accuracy.

[0108] In one embodiment, window 217 is disposed on the outer peripheral surface of the second permanent magnet 21. The magnetic supply area of ​​the second permanent magnet 21 near the outer peripheral surface is large, and the magnetic conduction area of ​​the rotor core 11 is large and the magnetic field strength is high. Disposing window 217 on its outer peripheral surface helps to limit the magnetic flux action area of ​​the second permanent magnet 21 and improves the utilization rate of the second permanent magnet 21.

[0109] In one embodiment, along the radial direction of the second permanent magnet 21, the recess 215 is located on the side of the second permanent magnet 21 closer to the window 217. The recess 215 is disposed adjacent to the window 217 and is located radially inner to the window 217. The recess 215 should be disposed as close as possible to the radially outer side of the second permanent magnet 21, allowing for a larger space to facilitate sealing the second permanent magnet 21 after molding.

[0110] In one embodiment, a limiting protrusion 111 is provided on the outer periphery of the rotor core 11. The limiting protrusion 111 extends laterally from both sides of the rotor core 11 in the circumferential direction and forms a radial limit on the first permanent magnet 12. An opening groove 112 is formed between the limiting protrusion 111 and the first permanent magnet 12. The opening groove 112 and the window 217 are connected in the axial direction of the rotor core 11. The window 217 and the opening groove 112, which are connected in the axial direction, are used together as a positioning structure when the second permanent magnet 21 is assembled to the rotor core 11, which can improve the assembly accuracy.

[0111] As shown in Figure 10, the limiting protrusion 111 is located at the outermost periphery of the rotor core 11 and extends circumferentially from two sides of the rotor core 11 in the circumferential direction. The two limiting protrusions 111 extending in opposite directions are spaced apart, thereby forming an opening groove 112 while radially limiting the first permanent magnet 12, reducing the radial magnetic leakage of the first permanent magnet 12.

[0112] In one embodiment, the window 217 is disposed on the groove 213 to minimize the impact of the window 217 on the magnetic supply area of ​​the second permanent magnet 21, thereby ensuring that the second permanent magnet 21 has a suitable magnetic flux contribution.

[0113] In one embodiment, window 217 is disposed on the inner circumferential surface of the second permanent magnet 21. In order to reduce the bottom magnetic leakage of the first permanent magnet 12 near the shaft, a magnetic isolation hole is provided between the rotor core 11 and the side of the first permanent magnet 12 near the shaft, and the window 217 and the magnetic isolation hole are connected along the axial direction of the rotor assembly.

[0114] In one embodiment, a projection is made onto one end face of the rotor core 11 along its axial direction. Within this projection plane, the position of the window 217 on the second permanent magnet 21 coincides with the position of the first permanent magnet 12. This arrangement further restricts the position of the window 217 on the circumference and radial direction of the second permanent magnet 21, making the position of the window 217 correspond to the position of the first permanent magnet 12. This weakens the repulsive force between the second permanent magnet 21 and the first permanent magnet 12, reducing assembly difficulty. Simultaneously, the window 217 organizes the magnetic flux of the second permanent magnet 21, allowing it to enter the end face of the rotor core 11 more effectively, thus improving the utilization rate of the second permanent magnet 21.

[0115] In one embodiment, a projection is made onto one end face of the rotor core 11 along its axial direction. Within this projection plane, the second permanent magnet 21 has a portion that does not overlap with the first permanent magnet 12, and the first permanent magnet 12 is exposed outside the second permanent magnet 21. That is, the second permanent magnet 21 does not completely cover the end of the first permanent magnet 12; from the rotor end face, the end of the first permanent magnet 12 has an exposed portion. This arrangement is also to allow the magnetic lines of force of the second permanent magnet 21 to enter the end face of the rotor core 11 more effectively, thereby improving the utilization rate of the second permanent magnet 21.

[0116] In one embodiment, a projection is made onto one end face of the rotor core 11 along the axial direction. Within this projection plane, the area of ​​a window 217 on the second permanent magnet 21 is s7, and the area of ​​a polar region of the second permanent magnet 21 is s1. Then, 0.04 ≤ s7 / s1 ≤ 0.32. Limiting the area ratio between the window 217 and the second permanent magnet 21 serves two purposes: firstly, it ensures that the window 217 has a certain area, allowing it to better perform its function of magnetic flux alignment and positioning; secondly, it limits the maximum area ratio of the window 217 to avoid its influence on the magnetic flux supply surface of the second permanent magnet 21.

[0117] In one embodiment, a projection is made on one end face of the rotor core 11 along the axial direction. Within this projection plane, the area of ​​a window 217 on the second permanent magnet 21 is s7, the area of ​​a groove 213 in a polar region of the second permanent magnet 21 is s8, and the area of ​​a protrusion 214 in a polar region of the second permanent magnet 21 is s9. Then, 0.08 ≤ s7 / s8 ≤ 0.36, and 0.07 ≤ s7 / s9 ≤ 0.32. Similar to limiting the range of s7 / s1, by limiting the proportion of the area of ​​the window 217 in the area of ​​the groove 213, the window 217 is ensured to have a suitable area; by limiting the proportion of the area of ​​the window 217 in the area of ​​the protrusion 214, its influence on the magnetizing surface of the second permanent magnet 21 is avoided.

[0118] In one embodiment, a projection is made onto one end face of the rotor core 11 along the axial direction. Within this projection plane, the area of ​​a window 217 on the second permanent magnet 21 is s7, and the area of ​​the first permanent magnet 12 is s10. Then, 0.07 ≤ s7 / s10 ≤ 0.31. Limiting the range of s7 / s10 allows the window 217 to effectively weaken the repulsive force between the ends of the second permanent magnet 21 and the first permanent magnet 12, reducing assembly difficulty.

[0119] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the length of the line connecting the rotor central axis to any point on the end edge of the second permanent magnet 21 near the air gap is Do2; the length of the line connecting the rotor central axis to the center of the end edge of one pole of the first permanent magnet 12 near the air gap is Do3; and the length of the line connecting the rotor central axis to any point on the end edge of the groove 213 near the air gap is Do5. Then, 0.4 ≤ max(Do5) / max(Do2) < 1.0, 0.45 ≤ max(Do5) / Do3 ≤ 1.1. More preferably, 0.7 ≤ max(Do5) / max(Do2) ≤ 0.98. Most preferably, 0.85 ≤ max(Do5) / max(Do2) ≤ 0.96. After setting the window 217 on the groove 213, the length of the line connecting the rotor central axis and any point on the end edge of the groove 213 near the air gap side is reduced. By limiting this size, the groove 213 can be set with the window 217 in a suitable position, which further enhances the effect of the window 217 on the radial outer magnetic field lines of the second permanent magnet 21 and improves the utilization rate of the window 217.

[0120] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the length of the line connecting the rotor central axis and any point on the end edge of the second permanent magnet 21 near the air gap side is Do2, and the depth of the window 217 along its radial direction is H, then 0.03≤min(H) / max(Do2)≤0.6.

[0121] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the width of the first permanent magnet 12 along the tangential direction is L1, and the width of the window 217 along the tangential direction is L2, then 0.1≤min(L2) / max(L1)≤2.0. More preferably, 0.4≤min(L2) / max(L1)≤1.1.

[0122] As shown in Figure 11, the radial depth H of window 217 refers to the distance between two points where the line connecting the rotor's central axis and any point on the outer circle of the second permanent magnet 21 intersects window 217 in a plane perpendicular to the axial direction of the second permanent magnet 21. The tangential width L2 of window 217 refers to the distance between the two ends of window 217 in a direction perpendicular to the radial direction in a plane perpendicular to the axial direction of the second permanent magnet 21. By limiting the value of H, the radial extension depth of window 217 is selected; by limiting the value of L2, the tangential extension dimension of window 217 is selected, ensuring that window 217 has a suitable position on the second permanent magnet 21, thus more effectively performing its function of magnetic flux alignment and positioning.

[0123] In one embodiment, the rotor structure includes a rotor core 11, a first permanent magnet 12, and a second permanent magnet 21. The rotor core 11 has a mounting groove, and the first permanent magnet 12 is mounted in the mounting groove. Along the axial direction of the rotor core 11, the axial height of the first permanent magnet 12 is greater than the axial height of the rotor core 11. The second permanent magnet 21 is disposed at the axial end of the rotor core 11, and a groove 213 is provided on the second permanent magnet 21. The portion of the first permanent magnet 12 extending axially out of the rotor core 11 is inserted into the groove 213. The first permanent magnet 12 is magnetized along the radial and / or tangential direction of the rotor core 11, and the second permanent magnet 21 is magnetized along the axial direction of the rotor core 11. The second permanent magnet 21 has an outer peripheral surface near the air gap side and an inner peripheral surface near the shaft side. At least one window 217 is provided in the region near the outer peripheral surface and / or inner peripheral surface of the second permanent magnet 21, and the window 217 does not penetrate the outer peripheral surface and / or inner peripheral surface of the second permanent magnet 21 along the radial direction. The radial direction of the second permanent magnet 21 is a radial direction from the center of the second permanent magnet 21 to its outer circle. This arrangement ensures that the window 217 does not cut through the outer circle side and inner hole side of the second permanent magnet 21. While retaining the magnetic flux arrangement and positioning function of the window 217, it can increase the structural strength of the second permanent magnet 21 and improve the reliability of motor operation.

[0124] In one embodiment, the outer peripheral wall of the rotor core 11 includes a plurality of spaced arc surfaces, and the distance between a single arc surface and the central axis of the rotor core 11 decreases from the middle to both ends along the circumferential direction. This arrangement allows a non-uniform thickness air gap structure to be formed between the outer peripheral wall of the rotor core 11 and the inner peripheral wall of the stator structure along the radial direction of the rotor, which can reduce the content of magnetic field harmonics, reduce motor torque pulsation, and weaken motor vibration noise.

[0125] In this embodiment, since the rotor core 11 forms an open slot 112, the outer periphery structure of the rotor core 11 is not a complete circle, but a number of spaced arc segments. The middle of each arc segment protrudes outward along the radial direction, forming an arc structure that is misaligned with the center of the outer circle of the rotor. This can improve the air gap magnetic flux density between the stator and rotor, which is more conducive to forming a sine curve and improving the working performance of the motor.

[0126] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the length of the line connecting the rotor central axis and any point on the end edge of the second permanent magnet 21 near the air gap is Do2, and the length of the line connecting the rotor central axis and any point on the end edge of the rotor core 11 near the air gap is Do1, and max(Do2)≤max(Do1).

[0127] In one embodiment, max(Do2) ≤ 0.98 * max(Do1).

[0128] For the motor, on the one hand, the stator structure is fitted outside the rotor structure, and an air gap is provided between the rotor structure and the stator structure. This arrangement allows space for the stator structure to be assembled. On the other hand, to ensure that the first permanent magnet 12 does not fall off after being assembled into the rotor core 11, the outer circle of the rotor core 11 may be provided with a limiting protrusion 111. The limiting protrusion 111 has a small magnetic circuit area and is easily saturated. Moreover, the limiting protrusion 111 is located close to the air gap, which is a magnetic flux accumulation point, resulting in high iron loss. Max(Do2) ≤ max(Do1) can ensure that the magnetic flux of the second permanent magnet 21 avoids the position of the limiting protrusion 111, thereby reducing the iron loss of the motor. In motors with a low iron loss ratio, max(Do2) = max(Do1) is a better choice. In motors with a high iron loss ratio, in one embodiment, max(Do2) ≤ 0.98 * max(Do1). It should be noted that the end edge of the second permanent magnet 21 near the air gap is not limited to a full circle, a segmented circle, a combination of a circle and a straight line, a straight line, or other shapes.

[0129] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the length of the line connecting the rotor central axis and any point on the end edge of the second permanent magnet 21 near the air gap is Do2, and the length of the line connecting the rotor central axis and the center of the end edge of one pole of the first permanent magnet 12 near the air gap is Do3, max(Do2)≤1.2*Do3, and preferably, min(Do2)≤Do3.

[0130] In one embodiment, |max(Do2)-Do3|≤1.5mm.

[0131] By restricting the positional relationship between the first permanent magnet 12 and the second permanent magnet 21 near the air gap, the magnetic lines of force of the first permanent magnet 12 and the second permanent magnet 21 can have a better superposition effect near the air gap, thereby improving the air gap magnetic flux density.

[0132] In one embodiment, the first permanent magnet 12 is a sintered permanent magnet or an injection-molded permanent magnet, which can be determined according to the application of the motor, the operating temperature, etc.

[0133] In one embodiment, the intrinsic coercivity of the second permanent magnet 21 is lower than that of the first permanent magnet 12. Compared to the second permanent magnet 21 located at the axial end of the rotor core 11, the first permanent magnet 12 is embedded in the rotor core 11 and is directly affected by the stator demagnetizing magnetic field. Setting the intrinsic coercivity of the first permanent magnet 12 to be higher can enhance the motor's anti-demagnetizing ability.

[0134] In one embodiment, the ratio of the remanence of the second permanent magnet 21 to that of the first permanent magnet 12 ranges from 0.3 to 1.5. In another embodiment, the ratio ranges from 0.5 to 0.8. Using injection-molded magnets for the second permanent magnet 21 and sintered magnets for the first permanent magnet 12 is a preferred embodiment. Limiting the minimum remanence ratio of the two flux sources ensures a suitable flux proportion for the second permanent magnet 21, giving the motor a strong overload capacity. Limiting the maximum remanence ratio reduces the repulsive force between the second permanent magnet 21 and the first permanent magnet 12, thus reducing the assembly difficulty of the rotor assembly.

[0135] In one embodiment, the rotor core 11 is formed by stacking silicon steel sheets, or the rotor core 11 is an injection-molded magnet, and the N and N poles of the rotor core 11 are alternately magnetized in the radial direction on a plane perpendicular to the axial direction of the rotor core 11.

[0136] The rotor core 11 serves as the path carrier for the magnetic flux flow between the first permanent magnet 12 and the second permanent magnet 21, and plays a role in unblocking and guiding the magnetic flux.

[0137] In one embodiment, the rotor core 11 is made of stacked silicon steel sheets, which has better magnetic permeability.

[0138] In one embodiment, the rotor core 11 is an injection-molded magnet. After being magnetized, it has a traction effect on the magnetic flux of the first permanent magnet 12 and the second permanent magnet 21, and can also guide the magnetic flux to enter the air gap and stator after being magnetized.

[0139] In one embodiment, the second permanent magnet 21 is injection molded onto or filled onto the rotor core 11.

[0140] In one embodiment, the second permanent magnet 21, the rotor core 11, and the first permanent magnet 12 are manufactured separately and then assembled together.

[0141] The second permanent magnet 21 and the first permanent magnet 12 can be manufactured in different ways, so the manufacturing method of the rotor can be selected according to the production conditions, thereby improving the flexibility of rotor structure production and manufacturing.

[0142] In one embodiment, the rotor structure is filled with molding compound at the ends and internal gaps and molded into a whole, which can ensure the overall structural strength of the rotor assembly.

[0143] In one embodiment, the rotor structure is assembled and secured together using fasteners. The rotors can be fixed together by adhesive bonding, riveting, or other fastening methods, which simplifies the rotor manufacturing process and reduces production costs.

[0144] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the length of the line connecting the rotor central axis and any point on the end edge of the second permanent magnet 21 near the air gap is Do2. After the rotor structure is filled with plastic sealant at the ends and internal gaps and plasticized into a whole, the length of the line connecting the rotor central axis and any point on the end edge of the rotor structure near the air gap is Do4. Then max(Do2)≤min(Do4) so ​​that the plastic sealant has a certain adhesion area and increases the overall strength of the rotor structure after plasticizing.

[0145] Referring to Figures 22 to 24, in one embodiment, the circumferential surface of the second permanent magnet 21 includes a first magnetic region 218 and a second magnetic region 219 arranged alternately in the circumferential direction. The first magnetic region 218 has a stronger magnetism than the second magnetic region 219. Along the axial direction of the rotor core 11, the stronger first magnetic region 218 corresponds to the rotor core 11, which can increase the attractive force between the second permanent magnet 21 and the rotor core 11. The weaker second magnetic region 219 corresponds to the first permanent magnet 12, which can weaken the repulsive force between the first permanent magnet 12 and the second permanent magnet 21. The alternating arrangement of the first magnetic region 218 and the second magnetic region 219 makes the rotor structural strength higher.

[0146] In one embodiment, a projection is made onto one end face of the second permanent magnet 21 along its axial direction. Within this projection plane, the area of ​​the first magnetic region 218 accounts for a proportion of the area of ​​the second permanent magnet 21 ranging from 0.8 to 0.94; more preferably, the proportion range is 0.9 to 0.93. Limiting the area proportion of the stronger magnetic region 218 within the second permanent magnet 21 ensures, on the one hand, that the first magnetic region 218 has a certain area proportion, providing sufficient magnetic flux to the rotor and improving the motor's magnetization effect and overload capacity; on the other hand, it limits the excessively large area proportion of the first magnetic region 218 within the second permanent magnet 21, thus avoiding excessive repulsive force between the second permanent magnet 21 and the first permanent magnet 12, reducing rotor assembly difficulty, and improving rotor structural strength.

[0147] In one embodiment, a recess 215 is provided on the axial end face of the second permanent magnet 21 on the side away from the rotor core 11. Projecting a projection along the axial direction of the second permanent magnet 21 onto one end face, the recess 215 is located within the second magnetic region 219. By placing the recess 215 within the weaker magnetic region 219, the influence of the recess 215 on the magnetism of the second permanent magnet 21 can be reduced, further increasing the magnetic flux linkage of the rotor.

[0148] In one embodiment, a projection is made onto one end face of the second permanent magnet 21 along its axial direction. Within this projection plane, the area of ​​the recess 215 occupies a proportion of 0.03 to 0.12 of the area of ​​the second magnetic region 219. This reduces the influence of the recess 215 on the magnetism of the second magnetic region 219 and increases the structural strength of the second permanent magnet 21.

[0149] In one embodiment, the first magnetic region 218 includes protrusions 214 and partial grooves 213, meaning that all of the protrusions 214 are located within the first magnetic region 218, while not all of the grooves 213 are located within the first magnetic region 218. The protrusions 214 are in direct contact with the rotor core 11, and setting them as the first magnetic region 218 with stronger magnetism helps to increase the magnetic flux linkage of the rotor. The grooves 213 are in direct contact with the first permanent magnet 12, and setting a portion of each groove 213 as a second magnetic region 219 with weaker magnetism can reduce the repulsive force between the second permanent magnet 21 and the first permanent magnet 12, thereby improving the structural strength of the rotor.

[0150] Referring to Figure 16, compared with motors of related technologies, the motor using the rotor structure of this application embodiment has a magnetic flux density increased by more than 60%, and the magnetic flux density performance is significantly improved.

[0151] Referring to Figure 17, compared with motors of related technologies, the motor using the rotor structure of this application embodiment has a leakage flux coefficient reduced by more than 10%, which effectively reduces leakage flux and improves motor performance.

[0152] Referring to Figure 18, compared with motors of related technologies, the motor using the rotor structure of this application has an increase of more than 50% in unloaded flux linkage, which effectively increases the unloaded flux linkage and improves motor performance.

[0153] Referring to Figure 19, compared with motors of related technologies, the motor using the rotor structure of this application has an air gap magnetic flux density increased by more than 60%, which effectively increases the air gap magnetic flux density, improves the motor torque density, and increases the motor output.

[0154] Referring to Figure 20, compared with motors of related technologies, the motor with the rotor structure of this application has a gradually obvious advantage in torque multiplier as current increases, achieving a larger torque multiplier, improving motor torque density, and increasing motor output.

[0155] Referring to Figure 21, compared with motors of related technologies, the motor using the rotor structure of this application embodiment has a torque pulsation reduction of more than 30%, which is significant and can effectively reduce electromagnetic vibration and noise of the motor.

[0156] According to an embodiment of this application, the motor includes a stator structure and a rotor structure, wherein the rotor structure is the rotor structure described above. The stator structure is sleeved on the outer periphery of the rotor structure.

[0157] In one embodiment, the axial height of the rotor core 11 is x; the stator structure includes a stator core 31 with an axial height of w, where x ≥ w. In one embodiment, x ≥ 1.05 * w. In this application, the end magnetic lines of force of the rotor core 11 can enter the rotor core 11 through magnetic guidance to become the main magnetic flux, without relying on the excessively high magnetic permeability of the stator core 31, and can also increase the rotor magnetic field strength. Therefore, limiting the relationship between x and w can improve the utilization rate of the stator core 31 while reducing the rotor saturation.

[0158] In one embodiment, the axial height of the rotor core 11 is x, the axial height of the stator core 31 is w, and the axial height of the second permanent magnet 21 is z1. Then, 0.2 ≤ z1 / x ≤ 0.8, 0.2 ≤ z1 / w ≤ 0.8, and 2.5 ≤ z1 / (xw) ≤ 10. The axial height of the second permanent magnet 21 is also one of the key parameters determining its magnetic flux strength. Limiting the values ​​of z1 / x and z1 / w can improve the utilization rate of the rotor and stator cores, and allow for the reasonable design of the thickness of the second permanent magnet 21 based on the core saturation level, resulting in a better magnetic flux strength. Furthermore, since the second permanent magnet 21 is located at the axial end of the rotor core 11, its magnetic lines of force must pass through the magnetic circuit at the end of the rotor core 11 before entering the stator. Limiting the ratio of z1 / (xw) ensures that the second permanent magnet 21 has a suitable magnetic circuit, reducing magnetic flux loss caused by magnetic reluctance.

[0159] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the area of ​​a polar region of the second permanent magnet 21 is s1, and the area of ​​the rotor core 11 above the outer surface of the stator core 31 along the axial direction of the rotor core 11 is s3. Therefore, 0.2 ≤ s1 / s3 ≤ 2.8. The second permanent magnet 21 is disposed at the axial end of the rotor core 11. Its magnetic lines of force must pass through the magnetic circuit at the end of the rotor core 11 before entering the stator, limiting the value of s1 / s3. This ensures that the end of the rotor core 11 has a suitable area to bear the magnetic flux of the second permanent magnet 21, thereby improving the rotor flux utilization rate.

[0160] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the area of ​​a polar region of the second permanent magnet 21 is s1, and the stator core 31 includes multiple stator teeth, with the area of ​​one stator tooth being s4. Therefore, 0.6 ≤ s1 / s4 ≤ 5.0. The stator teeth are an important part of the stator magnetic circuit, directly affecting the magnetic reluctance on the stator during magnetic flux flow. Limiting the value of s1 / s4 ensures, on the one hand, that the stator teeth have a suitable degree of saturation and high stator core utilization; on the other hand, it results in low stator magnetic circuit reluctance and high rotor magnetic flux utilization.

[0161] In one embodiment, the axial height of the rotor structure is v, and the axial height of the stator core 31 is w, where v ≥ 1.4 * w. Limiting the relationship between v and w can further improve the utilization rate of the stator core 31 while ensuring proper stator saturation.

[0162] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0163] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0164] The above are merely some embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A rotor structure, characterized by, The rotor core (11) has a mounting groove, the first permanent magnet (12) is mounted in the mounting groove, the axial height of the first permanent magnet (12) is greater than the axial height of the rotor core (11) along the axial direction of the rotor core (11), and the second permanent magnet (21) is arranged at the axial end of the rotor core (11). The second permanent magnet (21) is provided with a groove (213), the part of the first permanent magnet (12) extending out of the rotor core (11) in the axial direction is inserted into the groove (213), the first permanent magnet (12) is magnetized in the radial direction and / or the tangential direction of the rotor core (11), the second permanent magnet (21) is magnetized in the axial direction of the rotor core (11), the second permanent magnet (21) is provided with a recess (215) on the axial end face of the side away from the rotor core (11), and the recess (215) on the second permanent magnet (21) does not penetrate the second permanent magnet (21) in the axial direction. Projecting on one end face of the rotor core (11) along the axial direction of the rotor core (11), in the projection plane, the recess (215) is located in the groove (213).

2. The rotor structure of claim 1, wherein The recesses (215) are uniformly arranged along the circumferential direction of the second permanent magnet (21).

3. The rotor structure of claim 2, wherein The number of the recesses (215) is p or 2p, wherein p is the number of rotor pole pairs.

4. The rotor structure of claim 1, wherein The second permanent magnet (21) is provided with a hole structure (211), and the rotor core (11) is provided with a through hole (113). At least one hole structure (211) and at least one through hole (113) penetrate in the axial direction of the rotor core (11).

5. The rotor structure of claim 4, wherein 2p is an integer multiple of the number of hole structures (211) provided on the second permanent magnet (21), and p is the number of rotor pole pairs.

6. The rotor structure of claim 4, wherein Projecting on one end face of the rotor core (11) along the axial direction of the rotor core (11), in the projection plane, there is an included angle α between the line connecting the rotor center axis and the geometric center of any one recess (215) and the line connecting the rotor center axis and the geometric center of any one hole structure (211), and α is an integer multiple of 360 / 4p.

7. The rotor structure of claim 1, wherein The second permanent magnet (21) is an injection molded magnetic steel.

8. The rotor structure of claim 1, wherein The protrusions (214) are formed between adjacent grooves (213), and projecting on one end face of the rotor core (11) along the axial direction of the rotor core (11), in the projection plane, the radial width of the groove (213) is less than the radial width of the protrusion (214).

9. The rotor structure of claim 1, wherein In the plane perpendicular to the axial direction of the rotor core (11), the length of the line connecting the rotor center axis and any point on the end edge of the second permanent magnet (21) close to the rotor shaft side is Di2, the length of the line connecting the rotor center axis and the center of the end edge of the first permanent magnet (12) close to the rotor shaft side is Di3, and min(Di2)≥Di3.

10. The rotor structure of claim 1, wherein The second permanent magnet (21) has an outer circumferential surface close to the air gap side and an inner circumferential surface close to the shaft side, and at least one window (217) is arranged on the outer circumferential surface and / or the inner circumferential surface of the second permanent magnet (21).

11. The rotor structure of claim 10, wherein In the radial direction of the second permanent magnet (21), the recess (215) is located radially inside the window (217), and the recess (215) is located on the side of the second permanent magnet (21) close to the window (217).

12. The rotor structure of claim 1, wherein The groove (213) arranged on the second permanent magnet (21) does not penetrate the second permanent magnet (21), and the number of grooves (213) is the same as the number of rotor magnetic poles.

13. The rotor structure of claim 8, wherein In a plane perpendicular to the axial direction of the rotor core (11), one polarity area of the protrusion (214) is adapted to the area shape of one polarity area of the corresponding rotor core (11), and one polarity area of the protrusion (214) fills the corresponding polarity area of the rotor core (11).

14. The rotor structure of claim 1, wherein The first permanent magnet (12) and the second permanent magnet (21) are magnetized into multiple polarity areas, the magnetization directions of adjacent polarity areas of the second permanent magnet (21) are opposite, and the polarity of one polarity area of the second permanent magnet (21) close to the rotor core (11) is the first polarity, and the polarities of the two first permanent magnets (12) close to the corresponding rotor core (11) on the two sides of the polarity area of the second permanent magnet (21) are the first polarity.

15. The rotor structure of claim 1, wherein The circumferential surface of the second permanent magnet (21) includes a first magnetic area (218) and a second magnetic area (219), the magnetic property of the first magnetic area (218) is stronger than that of the second magnetic area (219); in the projection on one end surface of the second permanent magnet (21) along the axial direction of the second permanent magnet (21), the recess (215) is located in the second magnetic area (219) in the projection plane.

16. The rotor structure of claim 15, wherein In the projection on one end surface of the second permanent magnet (21) along the axial direction of the second permanent magnet (21), the area of the recess (215) accounts for 0.03-0.12 of the area of the second magnetic area (219).

17. The rotor structure of claim 15, wherein On the circumferential surface of the second permanent magnet (21), the first magnetic area (218) and the second magnetic area (219) are arranged alternately in the circumferential direction.

18. The rotor structure of claim 15, wherein, The protrusion (214) is formed between adjacent grooves (213), and the first magnetic area (218) includes the protrusion (214) and part of the groove (213).

19. An electric machine comprising a stator structure and a rotor structure, characterized in that The rotor structure is the rotor structure of any one of claims 1-18, and the stator structure is sleeved on the outer circumferential side of the rotor structure.

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