Rotor structure and motor

Abstract

The invention provides a rotor structure and a motor. The rotor structure comprises a rotor iron core, a first permanent magnet and a second permanent magnet, the rotor iron core is provided with an installation groove, the first permanent magnet is installed in the installation groove, and the axial height of the first permanent magnet is larger than that of the rotor iron core in the axial direction of the rotor iron core; the second permanent magnet is arranged at the axial end part of the rotor iron core, a groove is formed in the second permanent magnet, the part, extending out of the rotor iron core in the axial direction, of the first permanent magnet is inserted into the groove, the first permanent magnet is magnetized in the radial direction and / or tangential direction of the rotor iron core, and the second permanent magnet is magnetized in the axial direction of the rotor iron core. And at least two surfaces of the parts of the first permanent magnets extending out of the rotor core along the axial direction are surrounded by the second permanent magnets. According to the rotor structure, the magnetic gathering effect of the motor can be improved, the axial end magnetic leakage of the first permanent magnet is reduced, the number of parts is small, the number of assembling steps is small, assembling is easy, and the production cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of motors, and in particular to a rotor structure and a motor. Background Art

[0002] With the improvement of motor energy efficiency standards, higher requirements are placed on the energy efficiency level of motors. For permanent magnet motors, the efficiency and high torque density of the motors need to be further improved.

[0003] At present, there are two technical means to improve motor efficiency and torque density. One is to embed permanent magnets to obtain a larger air gap flux and a larger magnetic flux. However, due to the fixed rotor magnetic circuit structure, the energy efficiency improvement is limited. Another means is to use the rotor structure to increase the motor salient pole ratio and increase the motor's reluctance torque 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 will make the motor torque density inferior to that of a permanent magnet motor.

[0004] Therefore, for current motors, how to further achieve higher efficiency and higher torque density is an urgent problem to be solved.

[0005] The comparative document 201880064666.X discloses a permanent magnet rotor assembly, in which two permanent magnet sets (the first set is magnetized along the circumferential direction of the rotor, and the second set provides magnetic flux along the axial direction of the rotor) generate magnetic flux gathered by the pole pieces, and there are end plates made of magnetic material, the circumferentially magnetized magnets are placed in the circumferential gap between the pole pieces, and the magnets providing axial magnetic flux are placed in the gap between the pole piece array and the end plates. The magnetic end plates in the comparative document are used to provide a return path for the magnetic flux from the magnets providing axial magnetic flux. However, in the field of household appliances, the rotor structure including multiple pole pieces, multiple scattered magnets and magnetic end plates has many parts, the magnetic end plates are difficult to fix, and the rotor assembly is difficult to assemble, resulting in high production and assembly costs, making it difficult to implement applications. Summary of the invention

[0006] The main purpose of the present invention is to provide a rotor structure and a motor, which can improve the magnetic field concentration effect of the motor and reduce the axial end magnetic leakage of the first permanent magnet, and has fewer parts, fewer assembly steps, simple assembly and low production cost.

[0007] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a rotor structure is provided, including a rotor core, a first permanent magnet and a second permanent magnet, the rotor core having a mounting groove, the first permanent magnet being mounted in the mounting groove, and the axial height of the first permanent magnet along the axial direction of the rotor core being greater than the axial height of the rotor core; the second permanent magnet being arranged at the axial end of the rotor core, the second permanent magnet being provided with a groove, the portion of the first permanent magnet extending axially out of the rotor core being inserted into the groove, the first permanent magnet being magnetized along the radial direction and / or tangential direction of the rotor core, the second permanent magnet being magnetized along the axial direction of the rotor core, and the portion of the first permanent magnet extending axially out of the rotor core having at least two faces surrounded by the second permanent magnet.

[0008] Furthermore, a hole structure is provided on the second permanent magnet.

[0009] Furthermore, a projection is performed on an end surface of the rotor core along the axial direction of the rotor core, and within the projection surface, the shape of the hole structure matches the shape of the rotor core at a corresponding position.

[0010] Furthermore, a marking portion is provided on the second permanent magnet.

[0011] Further, the identification portion is arranged on an end surface of the second permanent magnet on a side close to and / or away from the rotor core.

[0012] Further, the identification portion is arranged in an adjacent area of ​​a certain hole structure.

[0013] Furthermore, the number of hole structures provided on the second permanent magnet is not less than 2.

[0014] Furthermore, the second permanent magnet is an injection-molded magnetic steel.

[0015] Further, the second permanent magnet includes an annular portion and a magnetic pole portion, and the magnetic pole portion is connected to form a whole through the annular portion.

[0016] Furthermore, the annular portion is located radially inward of the second permanent magnet, a groove is formed between adjacent magnetic pole portions, the magnetic pole portions are radially arranged along the circumference of the annular portion, and are connected to the annular portion through connecting ribs to form a whole with the annular portion.

[0017] Furthermore, a through hole is formed between the annular portion and the end surface of the first permanent magnet close to the rotating shaft, and the through hole passes through the rotor core and the second permanent magnet.

[0018] Furthermore, the second permanent magnet includes a first permanent magnet limiting portion and a magnetic pole portion. The first permanent magnet limiting portion is arranged between adjacent magnetic pole portions and connects adjacent magnetic pole portions so that the magnetic pole portions become a whole.

[0019] Furthermore, the first permanent magnet limiting portion is located radially outside the slot and is arranged corresponding to the slot. The first permanent magnet limiting portion connects the second permanent magnets on both sides in the circumferential direction.

[0020] Furthermore, the slots arranged on the second permanent magnet pass through and / or do not pass through the second permanent magnet, and the number of the slots is the same as the number of the rotor poles.

[0021] Furthermore, the second permanent magnet cooperates with the first permanent magnet through a slot arranged thereon, and both the first permanent magnet and the second permanent magnet are magnetic flux sources. Except for the rotor core, no other magnetic conductive components are arranged in the rotor structure.

[0022] Furthermore, magnetic pole portions are formed between adjacent slots, and on a plane perpendicular to the axial direction of the rotor core, radially outer sides of adjacent magnetic pole portions are disconnected and / or connected; radially inner sides of adjacent magnetic pole portions are disconnected and / or connected.

[0023] Furthermore, a polarity region of the magnetic pole portion corresponds to a position of a polarity region of the rotor core, and on a plane perpendicular to the axial direction of the rotor core, a polarity region of the magnetic pole portion matches a region shape of a corresponding polarity region of the rotor core.

[0024] Furthermore, at least one of the axial ends of the rotor core is provided with a second permanent magnet, and the number of the second permanent magnets provided in the rotor structure is not less than one.

[0025] Furthermore, the first permanent magnet and the second permanent magnet are divided into multiple polarity regions after magnetization. The first permanent magnet is magnetized with NS poles alternately along the radial direction and / or tangential direction of the rotor core; the second permanent magnet is magnetized with NS poles alternately along the axial direction of the rotor core.

[0026] Further, the polarity of the second permanent magnet on one side close to the rotor core is the first polarity, and the polarities of the two first permanent magnets on both sides adjacent to the second permanent magnet on one side close to the rotor core are the first polarity.

[0027] Furthermore, the axial height of the rotor core is x, the axial height of the first permanent magnet is y, y>x, the axial height of the second permanent magnet is z1, and the axial height of the magnetic pole portion is z2, z2≤z1, wherein 0.2*(yx)≤z1≤1.6*(yx).

[0028] Furthermore, 2*z2≥(yx).

[0029] Further, z2=0.5*(yx).

[0030] Furthermore, on a plane perpendicular to the axial direction of the rotor core, the length of a line connecting the center axis of the rotor and any point on the end edge of the second permanent magnet close to the rotating shaft is Di2, the length of a line connecting the center axis of the rotor and the center of the end edge of one pole of the first permanent magnet close to the rotating shaft is Di3, and max(Di2)≥0.75*Di3.

[0031] Furthermore, max(Di2)≥Di3.

[0032] Furthermore, the outer peripheral wall of the rotor core includes a plurality of arc surfaces arranged at intervals, and along the circumferential direction of the rotor core, the distance between a single arc surface and the central axis of the rotor core decreases from the middle to both ends.

[0033] Furthermore, on a plane perpendicular to the axial direction of the rotor core, the length of a line connecting the center axis of the rotor and any point on the end edge of the second permanent magnet close to the air gap is Do2, and the length of a line connecting the center axis of the rotor and the center of the end edge of one pole of the first permanent magnet close to the air gap is Do3, and max(Do2)≤1.2*Do3.

[0034] Furthermore, |max(Do2)-Do3|≤1.5mm.

[0035] Furthermore, the second permanent magnet is injection-molded ferrite or injection-molded neodymium iron boron.

[0036] Furthermore, the first permanent magnet is a sintered permanent magnet or an injection molded permanent magnet.

[0037] Further, the intrinsic coercive force of the second permanent magnet is lower than the intrinsic coercive force of the first permanent magnet.

[0038] Furthermore, the rotor core is formed by stacking silicon steel sheets, or the rotor core is injection-molded magnetic steel, and the rotor core NS poles are alternately magnetized along the radial direction on a plane perpendicular to the axial direction of the rotor core.

[0039] Furthermore, the second permanent magnet is injection-molded or filled on the rotor core, or the second permanent magnet, the rotor core and the first permanent magnet are separately manufactured and then assembled together.

[0040] Further, the rotor structure is filled with molding compound at the end and the inner gap and molded into a whole, or the rotor structure is assembled and fixed together by fasteners.

[0041] According to another aspect of the present invention, a motor is provided, comprising a stator structure and a rotor structure, wherein the rotor structure is the above-mentioned rotor structure, and the stator structure is sleeved on the outer peripheral side of the rotor structure.

[0042] Furthermore, the axial height of the rotor core is x; the stator structure includes the stator core, and the axial height of the stator core is w, x≥w.

[0043] Furthermore, x≥1.05*w.

[0044] Furthermore, the axial height of the rotor structure is v, the axial height of the stator core is w, and v≥1.4*w.

[0045] According to the technical solution of the present invention, the rotor structure includes a rotor core, a first permanent magnet and a second permanent magnet. The rotor core has a mounting groove, the first permanent magnet is mounted in the mounting groove, and the axial height of the first permanent magnet is greater than the axial height of the rotor core along the axial direction of the rotor core; the second permanent magnet is arranged at the axial end of the rotor core, the second permanent magnet is provided with a groove, the part 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 direction and / or tangential direction of the rotor core, the second permanent magnet is magnetized along the axial direction of the rotor core, and the part of the first permanent magnet extending axially out of the rotor core has at least two faces surrounded by the second permanent magnet.

[0046] A first permanent magnet and a second permanent magnet are simultaneously arranged in the rotor, and the first permanent magnet and the second permanent magnet jointly provide magnetic flux for the motor, which can increase the output of the motor; the relative positions of the first permanent magnet and the second permanent magnet are designed, and the first permanent magnet is arranged to be inserted into the slot of the second permanent magnet, and the first permanent magnet serves as a part of the magnetic circuit for the magnetic flux of the second permanent magnet to flow, and pulls the magnetic flux of the second permanent magnet into the rotor core; after the magnetic flux of the first permanent magnet and the second permanent magnet are concentrated on the rotor core, they enter the air gap and the stator, which can greatly improve the magnetic flux concentration effect of the rotor; the part of the first permanent magnet that extends axially out of the rotor core is restricted to be surrounded by the second permanent magnet on at least two sides, so that the magnetic flux of the second permanent magnet has a path to enter the rotor core to form a magnetic circuit, thereby ensuring the magnetic flux concentration enhancement effect of the rotor. In addition, except for the rotor core, no other magnetic conductive components are arranged in the rotor structure, so there are fewer parts, fewer assembly steps, simple assembly, and low production cost. At the same time, the axial end leakage magnetic lines of the first permanent magnet need to form a closed loop through the second permanent magnet. The second permanent magnet, which is a non-magnetic conductive component, weakens the end leakage magnetic field of the first permanent magnet, and the flow direction of the magnetic lines of the second permanent magnet is opposite to the flow direction of the end leakage magnetic lines of the first permanent magnet, and there is a mutual repulsion effect, which will further reduce the axial end leakage magnetic field of the first permanent magnet and improve the magnetic field strength of the rotor. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0048] Figure 1An exploded structural diagram showing a rotor structure of an embodiment of the present invention;

[0049] Figure 2 A three-dimensional structural diagram showing a rotor structure of an embodiment of the present invention;

[0050] Figure 3 A three-dimensional structural diagram showing a rotor structure of an embodiment of the present invention;

[0051] Figure 4 An exploded structural diagram showing a rotor structure of an embodiment of the present invention;

[0052] Figure 5 A three-dimensional structural diagram showing a rotor structure of an embodiment of the present invention;

[0053] Figure 6 An exploded structural diagram showing a rotor structure of an embodiment of the present invention;

[0054] Figure 7 A partially exploded structural diagram showing a rotor structure according to an embodiment of the present invention;

[0055] Figure 8 A three-dimensional structural diagram showing a rotor structure of an embodiment of the present invention;

[0056] Fig. 9 A three-dimensional structural diagram of a second permanent magnet of a rotor structure according to an embodiment of the present invention is shown;

[0057] Fig.10 A three-dimensional structural diagram showing a rotor structure of an embodiment of the present invention;

[0058] Fig.11 An exploded structural diagram showing a rotor structure of an embodiment of the present invention;

[0059] Fig.12 A three-dimensional structural diagram showing a rotor structure of an embodiment of the present invention;

[0060] Fig.13 A three-dimensional structural diagram showing a rotor structure of an embodiment of the present invention;

[0061] Fig.14 An exploded structural diagram showing a rotor structure of an embodiment of the present invention;

[0062] Fig.15 A three-dimensional structural diagram showing a rotor structure of an embodiment of the present invention;

[0063] Fig.16 A top view of a rotor structure according to an embodiment of the present invention is shown;

[0064] Fig.17 Shows Fig.16 AA section view;

[0065] Fig.18 A side structural diagram showing a rotor structure of an embodiment of the present invention;

[0066] Fig.19 A side structural diagram showing a second permanent magnet of a rotor structure according to an embodiment of the present invention is shown;

[0067] Fig. 20 A top view of a rotor structure according to an embodiment of the present invention is shown;

[0068] Fig.21 A top view of a partial structure of a rotor structure according to an embodiment of the present invention is shown;

[0069] Fig. 22 A side structural diagram of the motor of the present invention is shown;

[0070] Fig.23 A schematic diagram showing the polarity direction of the rotor structure of the present invention is shown;

[0071] Fig.24 A magnetic circuit schematic diagram of the rotor structure of the present invention is shown;

[0072] Fig.25 A comparison diagram of magnetic concentration coefficients of a motor according to an embodiment of the present invention and a motor according to related art is shown;

[0073] Fig.26 A comparison diagram of magnetic leakage coefficients of a motor according to an embodiment of the present invention and a motor according to a related art is shown;

[0074] Fig. 27 A comparison diagram of no-load flux linkage between a motor according to an embodiment of the present invention and a motor in the related art is shown;

[0075] Fig.28 A comparison diagram of air gap flux density between a motor according to an embodiment of the present invention and a motor in the related art is shown;

[0076] Fig.29 A torque-current characteristic comparison diagram of a motor according to an embodiment of the present invention and a motor according to a related art is shown;

[0077] Fig.30 A torque ripple comparison diagram of a motor according to an embodiment of the present invention and a motor according to a related art is shown;

[0078] Fig.31 A comparison diagram of first permanent magnet utilization rates of a motor according to an embodiment of the present invention and a motor according to a related art is shown; and

[0079] Fig.32A comparison diagram of the first permanent magnet leakage flux of the motor according to the embodiment of the present invention and the motor according to the related art is shown.

[0080] The above drawings include the following reference numerals:

[0081] 11. rotor core; 111. limiting protrusion; 12. first permanent magnet; 13. through hole; 21. second permanent magnet; 211. hole structure; 212. identification part; 213. slot; 214. magnetic pole part; 215. annular part; 216. first permanent magnet limiting part; 31. stator core. DETAILED DESCRIPTION

[0082] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0083] See also Figures 1 to 23 As shown, according to an embodiment of the present invention, 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, the first permanent magnet 12 is mounted in the mounting groove, and 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 arranged at the axial end of the rotor core 11, and a groove 213 is arranged on the second permanent magnet 21, and the part 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 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. At least two faces of the part of the first permanent magnet 12 extending axially out of the rotor core 11 are surrounded by the second permanent magnet 21.

[0084] like Fig.24As shown, a first permanent magnet 12 and a second permanent magnet 21 are simultaneously arranged in the rotor, and the first permanent magnet 12 and the second permanent magnet 21 jointly provide a magnetic flux for the motor, which can increase the output of the motor; the relative positions of the first permanent magnet 12 and the second permanent magnet 21 are designed, and the first permanent magnet 12 is arranged to be inserted into the slot 213 of the second permanent magnet 21, and the first permanent magnet 12 serves as a part of the magnetic circuit for the magnetic flux of the second permanent magnet 21 to flow, and the magnetic flux of the second permanent magnet 21 is pulled into the rotor core 11; the magnetic flux of the first permanent magnet 12 and the second permanent magnet 21 are on the rotor core 11. After magnetic concentration, it enters the air gap and the stator, which can greatly improve the magnetic concentration effect of the rotor. In addition, except for the rotor core 11, no other magnetic conductive components are arranged in the rotor structure. The axial end leakage magnetic lines of force of the first permanent magnet 12 need to form a closed loop through the second permanent magnet 21. The second permanent magnet 21, which is a non-magnetic conductive component, weakens the end leakage magnetic field of the first permanent magnet 12, and the flow direction of the magnetic lines of force of the second permanent magnet 21 is opposite to the flow direction of the end leakage magnetic lines of force of the first permanent magnet 12. There is a mutual repulsion effect, which will further reduce the axial end leakage magnetic field of the first permanent magnet 12 and improve the magnetic field strength of the rotor.

[0085] The matching design of the first permanent magnet 12 and the second permanent magnet 21 in the rotor structure provides a return magnetic circuit for the magnetic flux of the second permanent magnet 21 through the first permanent magnet 12, and there is no need to add an additional magnetic end plate that matches the magnetic circuit of the second permanent magnet 21. This can eliminate the magnetic dependence of the second permanent magnet 21 on the magnetic end plate, while reducing the number of rotor parts, resulting in fewer assembly steps, simpler assembly, and lower production costs.

[0086] In one embodiment, 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. The magnetic lines of force entering the rotor core 11 from different directions form a magnetic field concentration effect on the rotor core 11, thereby improving the rotor magnetic field strength and increasing the utilization rate of the rotor core 11.

[0087] like Fig.24 As shown, in this embodiment, the first permanent magnet 12 with a larger axial height is set to be tangentially magnetized, and the second permanent magnet 21 arranged at the axial end of the rotor core 11 is set to be axially magnetized, which can achieve 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 for the motor together, effectively increasing the motor output.

[0088] In one embodiment, the first permanent magnet 12 is a combination of tangential magnetization and radial magnetization.

[0089] 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 may also be at an acute angle to the axial direction of the rotor core 11 .

[0090] In one embodiment, at least two surfaces of the portion of the first permanent magnet 12 extending axially out of the rotor core 11 are surrounded by the second permanent magnet 21. This allows the magnetic field lines of the second permanent magnet 21 to enter the rotor core 11 to form a magnetic circuit, thereby ensuring the magnetic field lifting effect of the rotor. Figures 1 to 4 In the illustrated embodiment, all five faces of the portion of the first permanent magnet 12 that extends axially out of the rotor core 11 are surrounded by the second permanent magnet 21 ; Figures 5 to 7 In the illustrated embodiment, the portion of the first permanent magnet 12 that extends axially out of the rotor core 11 has four faces surrounded by the second permanent magnet 21; Figure 10 to Figure 12 In the illustrated embodiment, the portion of the first permanent magnet 12 that extends axially out of the rotor core 11 has three surfaces surrounded by the second permanent magnet 21; Figure 13 to Figure 14 In the illustrated embodiment, two surfaces of the portion of the first permanent magnet 12 that protrudes axially out of the rotor core 11 are surrounded by the second permanent magnet 21 .

[0091] In one embodiment, a hole structure 211 is provided on the second permanent magnet 21. The shape of the hole structure is not limited to circular, elliptical, square or other shapes.

[0092] In one embodiment, a projection is made on one end face of the rotor core 11 along the axial direction of the rotor core 11, and within the projection face, the shape of the hole structure 211 matches the shape of the rotor core 11 at the corresponding position. The magnetic field lines of the second permanent magnet 21 enter the rotor core 11 to become the main magnetic field after being magnetically guided by the end face of the rotor core 11. The shape of the hole structure 211 matches the shape of the rotor core 11 at the corresponding position, which can improve the utilization rate of the second permanent magnet 21 and the rotor core 11. At the same time, the reasonable design of the position and shape of the hole structure 211 can guide the magnetic field of the second permanent magnet 21, ensure the uniformity and unsaturation of the magnetic field distribution of the rotor core 11, and reduce the rotor iron loss.

[0093] In one embodiment, the second permanent magnet 21 is provided with an identification portion 212. The identification portion 212 is used to identify the polarity sequence of the second permanent magnet 21, and the identification portion 212 is not limited to letter identification, shape identification or other forms of identification.

[0094] In one embodiment, the identification portion 212 is disposed on the end surface of the second permanent magnet 21 close to and / or away from the rotor core 11. Preferably, the identification portion 212 is disposed on the end surface of the second permanent magnet 21 close to and away from the rotor core 11, that is, the axial end surfaces on both sides of the second permanent magnet 21 are provided with identification portions, so as to facilitate the identification of the polarity of the second permanent magnet 21.

[0095] In one embodiment, the identification portion 212 is disposed in an adjacent area of ​​a hole structure 211. The cooperation between the identification portion 212 and the hole structure 211 can ensure the uniqueness of the polarity sequence of the second permanent magnet 21 after magnetization.

[0096] In one embodiment, the number of the hole structures 211 provided on the second permanent magnet 21 is not less than 2, so as to ensure the symmetry of the rotor magnetic field and reduce the torque pulsation and harmonic loss caused by the asymmetric magnetic field.

[0097] In one embodiment, the second permanent magnet 21 is an injection molded magnetic steel. Using the injection molded magnetic steel can reduce the rotor saturation and iron loss on the one hand, and on the other hand, the injection molded magnetic steel has a higher degree of freedom in shape, which can reduce the difficulty of manufacturing the second permanent magnet 21 and the rotor structure.

[0098] In one embodiment, the second permanent magnet 21 is injection-molded ferrite or injection-molded neodymium iron boron. The second permanent magnet 21 may also be injection-molded magnetic steel of other material types.

[0099] In one embodiment, the second permanent magnet 21 includes an annular portion 215 and a magnetic pole portion 214, and the magnetic pole portion 214 is connected to form a whole through the annular portion 215. The annular portion 215 is located on the radial inner side of the second permanent magnet 21, and a groove 213 is formed between each adjacent magnetic pole portion 214. The magnetic pole portion 214 is radially arranged along the circumference of the annular portion 215, and is connected to the annular portion 215 through a connecting rib, and forms a whole with the annular portion 215. In order to ensure the strength of the rotor, a magnetic bridge is provided on the inner side of the rotor core 11, and the annular portion 215 provided on the radial inner side of the second permanent magnet 21 helps to saturate the magnetic bridge and reduce the leakage of the first permanent magnet 12 at the inner magnetic bridge. In this embodiment, the second permanent magnet 21 is connected to form an integral structure through the annular portion 215. That is, the second permanent magnet 21 is a whole, rather than a block.

[0100] In one embodiment, a through hole 13 is formed between the annular portion 215 and the end surface of the first permanent magnet 12 close to the rotating shaft, and the through hole 13 passes through the rotor core 11 and the second permanent magnet 21. The two circumferential surfaces of the portion of the first permanent magnet 12 that extends axially out of the rotor core 11 are surrounded by the second permanent magnet 21. The through hole 13 passes through the rotor core 11 and the second permanent magnet 21, and can be used as a positioning hole in the rotor manufacturing process; if the rotor is a plastic-coated structure as a whole, the through hole 13 can also be used as a circulation hole for the plastic packaging material.

[0101] In one embodiment, the second permanent magnet 21 includes a first permanent magnet stopper 216 and a magnetic pole portion 214. The first permanent magnet stopper 216 is disposed between adjacent magnetic pole portions 214 and connects adjacent magnetic pole portions 214 so that the magnetic pole portions 214 become a whole. Fig.31As shown, compared with the motor of the related art, the utilization rate of the first permanent magnet 12 of the motor using the rotor structure of the embodiment of the present invention is significantly improved. The main reason is that under the rotor structure of the present invention, the utilization rate of the part of the first permanent magnet 12 extending out of the rotor core 11 is improved. The second permanent magnet 21 is provided with a first permanent magnet limiter 216, because its polarity repels the first permanent magnet 12, and the leakage magnetic flux of the first permanent magnet 12 can be suppressed. Fig.32 As shown, compared with the motor in the related art, the leakage flux of the first permanent magnet 12 of the motor adopting the rotor structure of the embodiment of the present invention is significantly reduced.

[0102] In one embodiment, the first permanent magnet stopper 216 is located radially outside the slot 213 and is arranged corresponding to the slot 213. The first permanent magnet stopper 216 connects the second permanent magnets 21 on both sides in the circumferential direction. The two circumferential surfaces and one radial surface of the portion of the first permanent magnet 12 extending axially out of the rotor core 11 are surrounded by the second permanent magnet 21.

[0103] In one embodiment, at least one of the axial ends of the rotor core 11 is provided with a second permanent magnet 21, and the number of the second permanent magnets 21 provided in the rotor structure is not less than one. Preferably, the number of the second permanent magnets 21 provided in the rotor structure is two, that is, the second permanent magnets 21 are provided at both axial ends of the rotor core 11, so that the magnetic circuit at the end of the motor can be arranged, so that the torque density is higher, the motor efficiency is higher, and the high performance of the motor is guaranteed. In the axial direction of the rotor core 11, the rotor core 11 and the second permanent magnet 21 are fitted together to reduce the loss of the magnetic flux of the second permanent magnet 21 during circulation. 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 block structure, such as Figure 7 The second permanent magnet 21 shown is an integral structure. Figure 8 to Figure 9 The second permanent magnet 21 shown is a block-type structure.

[0104] In one embodiment, when the single second permanent magnet 21 is a segmented structure, the number of segments is not limited to 2 or more.

[0105] In one embodiment, the second permanent magnet 21 cooperates with the first permanent magnet 12 through the slot 213 provided thereon. Both the first permanent magnet 12 and the second permanent magnet 21 are magnetic flux sources. Except for the rotor core 11, no other magnetic conductive components are provided in the rotor structure.

[0106] In one embodiment, the slots 213 provided on the second permanent magnet 21 penetrate and / or do not penetrate the second permanent magnet 21, the number of the slots 213 is the same as the number of the rotor poles, and magnetic pole portions 214 are formed between adjacent slots 213. When the slots 213 do not penetrate the second permanent magnet 21, the adjacent magnetic pole portions 214 are connected as a whole through the slots 213, which can increase the structural strength of the second permanent magnet 21. Considering the overall mechanical strength of the rotor structure, it can be selected whether the slots 213 penetrate the second permanent magnet 21.

[0107] In one embodiment, magnetic poles 214 are formed between adjacent slots 213. On a plane perpendicular to the axial direction of the rotor core 11, the radially outer sides of adjacent magnetic poles 214 are disconnected and / or connected; the radially inner sides of adjacent magnetic poles 214 are disconnected and / or connected. Figures 5 to 7 As shown, in one embodiment of the present invention, a magnetic pole portion 214 is formed between two adjacent slots 213, and the outer sides between the two adjacent magnetic pole portions 214 are disconnected, which can reduce the magnetic leakage at the outer circle of the rotor; in order to ensure the strength of the rotor, a magnetic bridge is provided on the inner side of the rotor core 11, and the second permanent magnet 21 connected to the inner side of the magnetic pole portion 214 helps to saturate the magnetic bridge and reduce the magnetic leakage of the first permanent magnet 12 at the inner magnetic bridge. Fig.12 As shown, in another embodiment of the present invention, a magnetic pole portion 214 is formed between two adjacent slots, and the outer side and the inner side between the two adjacent magnetic pole portions 214 are disconnected, which can reduce the processing difficulty of the second permanent magnet 21 and reduce the processing cost.

[0108] In one embodiment, a polar region of the magnetic pole portion 214 corresponds to a position of a polar region of the rotor core 11. That is, a polar region of the magnetic pole portion 214 of the second permanent magnet 21 generates a magnetic flux, and a polar region of the rotor core 11 at a corresponding position is a magnetic path of the magnetic flux. The corresponding arrangement of the two can shorten the magnetic path as much as possible and reduce magnetic loss.

[0109] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, a polar region of the magnetic pole portion 214 matches the region shape of a corresponding polar region of the rotor core 11, and a polar region of the magnetic pole portion 214 fills the corresponding polar region of the rotor core 11. "Filling" here means that there is no gap between the magnetic pole portion 214 and the rotor core 11 on a plane perpendicular to the axial direction of the rotor core 11.

[0110] In one embodiment, the first permanent magnet 12 and the second permanent magnet 21 are divided into multiple polarity regions after magnetization. The first permanent magnet 12 is magnetized with NS poles alternately along the radial direction and / or tangential direction of the rotor core 11; the second permanent magnet 21 is magnetized with NS poles alternately along the axial direction of the rotor core 11.

[0111] The polarity of the second permanent magnet 21 on the side close to the rotor core 11 is the first polarity, and the polarity of the two first permanent magnets 12 on both sides adjacent to the second permanent magnet 21 on the side close to the rotor core 11 is the first polarity, that is, the polarity of the second permanent magnet 21 on the side close to the rotor core 11 is the same as the polarity of the first permanent magnets 12 on both sides adjacent to the second permanent magnet 21 on the side close to the rotor core 11. Fig.23 In the illustrated embodiment, the second permanent magnet 21 is magnetized axially, and the first permanent magnet 12 is magnetized tangentially. Under a certain pole, the magnetization directions of both are directed toward the rotor core 11. Under this magnetization mode, the superposition of the magnetic flux of the first permanent magnet 12 and the second permanent magnet 21 can be achieved, thereby improving the no-load magnetic flux.

[0112] 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 magnetic pole portion 214 is z2, z2≤z1, where 0.2*(yx)≤z1≤1.6*(yx).

[0113] In one embodiment, 2*z2≥(yx), interference between the first permanent magnet 12 and the second permanent magnet 21 can be avoided to enable assembly of the first permanent magnet 12 and the second permanent magnet 21 .

[0114] In one embodiment, z2=0.5*(yx), which can form an optimal fit, effectively avoid the gap between the first permanent magnet 12 and the second permanent magnet 21, and reduce magnetic loss.

[0115] In one embodiment, 0.03≤(z1−z2) / z1≤0.7, so that the portion of the slot 213 that does not penetrate the second permanent magnet 21 has a certain axial thickness ratio in the second permanent magnet 21 to ensure the structural strength of the second permanent magnet 21 .

[0116] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the length of the line between the rotor central axis and any point on the end edge of the second permanent magnet 21 close to the rotating shaft is Di2, the inner diameter of the rotor core 11 is Di1, and min(Di2)≥0.5*Di1. The rotating shaft needs to be assembled at the inner hole of the rotor core 11. On the one hand, the above-mentioned dimensional relationship can make way for the assembly of the rotating shaft; on the other hand, without affecting the assembly of the rotating shaft, the inner hole of the second permanent magnet 21 can be filled with plastic packaging material or other materials to enhance the strength of the rotor.

[0117] 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 magnetic supply surface of the second permanent magnet 21 and improve the magnetic flux contribution of the second permanent magnet 21 .

[0118] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the length of the line between the central axis of the rotor and any point on the end edge of the second permanent magnet 21 close to the rotating shaft is Di2, and the length of the line between the central axis of the rotor and the center of the end edge of one pole of the first permanent magnet 12 close to the rotating shaft is Di3, and max(Di2)≥0.75*Di3. Preferably, max(Di2)≥Di3. When close to the rotating shaft, on the one hand, the magnetic path area of ​​the rotor core 11 is too small and the core is easily saturated. On the other hand, the permanent magnet here contributes little to the torque and the utilization rate of the permanent magnet is low. 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.

[0119] In one embodiment, a limiting protrusion 111 is disposed on the outer circumference of the rotor core 11 . The limiting protrusion 111 extends laterally from both circumferential sides of the rotor core 11 and forms a radial limit for the first permanent magnet 12 .

[0120] In this embodiment, the limiting protrusion 111 is located at the outermost periphery of the rotor core 11, and extends circumferentially from the two side surfaces of the rotor core 11 in the circumferential direction, and the two limiting protrusions 111 extending in opposite directions are arranged at intervals, thereby forming an open slot structure while radially limiting the first permanent magnet 12, thereby reducing the radial magnetic leakage of the first permanent magnet 12.

[0121] In one embodiment, the outer peripheral wall of the rotor core 11 includes a plurality of arc surfaces arranged at intervals, and along the circumferential direction, the distance between a single arc surface and the central axis of the rotor core 11 decreases from the middle to both ends. This arrangement can form an air gap structure with non-uniform thickness along the radial direction of the rotor between the outer peripheral wall of the rotor core 11 and the inner peripheral wall of the stator structure, which can reduce the harmonic content of the magnetic field, reduce the torque pulsation of the motor, and weaken the vibration noise of the motor.

[0122] In this embodiment, since the rotor core 11 forms an open slot structure, the outer peripheral structure of the rotor core 11 is not a full circle, but a plurality of arc segments arranged at intervals. The middle of each arc segment protrudes radially outward to form an arc structure that is misaligned with the center of the rotor outer circle. This can improve the air gap magnetic density between the stator and the rotor, is more conducive to forming a sine curve, and improves the working performance of the motor.

[0123] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the length of a line connecting the center axis of the rotor and any point on the end edge of the second permanent magnet 21 close to the air gap side is Do2, the length of a line connecting the center axis of the rotor and any point on the end edge of the rotor core 11 close to the air gap side is Do1, and max(Do2)≤max(Do1).

[0124] In one embodiment, max(Do2)≤0.98*max(Do1).

[0125] For the motor, on the one hand, the stator structure is sleeved on the outside of the rotor structure, and an air gap is set between the rotor structure and the stator structure. This setting can make way for the assembly of the stator structure; on the other hand, in order to ensure that the first permanent magnet 12 will 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 magnetic circuit area of ​​the limiting protrusion 111 is small and easy to saturate, and the position of the limiting protrusion 111 is close to the air gap, which is the magnetic flux gathering position. The iron loss here is large, and max(Do2)≤max(Do1) can make the magnetic flux of the second permanent magnet 21 avoid the position of the limiting protrusion 111, reducing the iron loss of the motor. In motors with a small iron loss ratio, max(Do2)=max(Do1) is a better choice. In motors with a large iron loss ratio, preferably, max(Do2)≤0.98*max(Do1). It should be noted that the end edge of the second permanent magnet 21 close to the air gap side is not limited to a full arc, a segmented arc, a combination of an arc and a straight line, a straight line or other shapes.

[0126] In one embodiment, on a plane perpendicular to the axial direction of the rotor core 11, the length of a line connecting the center axis of the rotor and any point on the end edge of the second permanent magnet 21 close to the air gap is Do2, and the length of a line connecting the center axis of the rotor and the center of the end edge of one pole of the first permanent magnet 12 close to the air gap is Do3, and max(Do2)≤1.2*Do3.

[0127] In one embodiment, |max(Do2)-Do3|≤1.5 mm.

[0128] Limiting the positional relationship between the first permanent magnet 12 and the second permanent magnet 21 near the air gap can make the magnetic lines of force of the first permanent magnet 12 and the second permanent magnet 21 have a better superposition effect near the air gap, thereby improving the air gap magnetic flux density.

[0129] 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 use occasion and use temperature of the motor.

[0130] In one embodiment, the intrinsic coercive force of the second permanent magnet 21 is lower than the intrinsic coercive force of the first permanent magnet 12. Compared with 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 demagnetization magnetic field. The intrinsic coercive force of the first permanent magnet 12 is set to be higher, which can enhance the anti-demagnetization ability of the motor.

[0131] In one embodiment, the rotor core 11 is formed by stacking silicon steel sheets, or the rotor core 11 is injection-molded magnetic steel. In a plane perpendicular to the axial direction of the rotor core 11 and in a radial direction, the rotor core 11 is magnetized alternately with N and S poles.

[0132] The rotor core 11 is a path carrier for the flux of the first permanent magnet 12 and the second permanent magnet 21 to flow, and has the function of clearing and guiding the flux.

[0133] In one embodiment, the rotor core 11 is formed by laminating silicon steel sheets and has better magnetic conductivity.

[0134] In one embodiment, the rotor core 11 is an injection-molded magnetic steel, which has a pulling effect on the magnetic flux of the first permanent magnet 12 and the second permanent magnet 21 after magnetization, and can also guide the magnetic flux to enter the air gap and the stator after magnetic concentration.

[0135] In one embodiment, the second permanent magnet 21 is injection-molded or filled on the rotor core 11 .

[0136] 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.

[0137] The second permanent magnet 21 and the first permanent magnet 12 can be processed and manufactured in different ways, so the manufacturing method of the rotor can be selected according to production conditions, thereby improving the flexibility of rotor structure production.

[0138] In one embodiment, the rotor structure is filled with molding compound at the end and the internal gap and molded into a whole, which can ensure the overall structural strength of the rotor assembly.

[0139] In one embodiment, the rotor structure is assembled and fixed together by fasteners. The rotor can be fixed together by gluing, riveting or other fastening methods, which can simplify the rotor production process and reduce production costs.

[0140] See also Fig.25 As shown, compared with the motor in the related art, the magnetic concentration coefficient of the motor using the rotor structure of the embodiment of the present invention is increased by more than 60%, and the magnetic concentration performance is significantly improved.

[0141] See also Fig.26 As shown, compared with the motor in the related art, the magnetic leakage coefficient of the motor using the rotor structure of the embodiment of the present invention is reduced by more than 10%, which effectively reduces the magnetic leakage and improves the motor performance.

[0142] See also Fig. 27 As shown, compared with the motor in the related art, the no-load flux of the motor using the rotor structure of the embodiment of the present invention is increased by more than 50%, which effectively increases the no-load flux and improves the motor performance.

[0143] See also Fig.28 As shown, compared with the motor in the related art, the air gap flux density of the motor using the rotor structure of the embodiment of the present invention is increased by more than 60%, which effectively increases the air gap flux density, improves the motor torque density, and increases the motor output.

[0144] See also Fig.29 As shown, compared with the motors of the related art, the torque multiple of the motor adopting the rotor structure of the embodiment of the present invention becomes increasingly advantageous as the current increases, thereby achieving a larger torque multiple, improving the motor torque density, and increasing the motor output.

[0145] See also Fig.30 As shown, compared with the motor in the related art, the torque pulsation of the motor adopting the rotor structure of the embodiment of the present invention is reduced by more than 30%, the torque pulsation is significantly reduced, and the electromagnetic vibration and noise of the motor can be effectively weakened.

[0146] According to an embodiment of the present invention, the motor comprises a stator structure and a rotor structure, and the rotor structure is the above-mentioned rotor structure. The stator structure is sleeved on the outer circumference of the rotor structure.

[0147] In one embodiment, the axial height of the rotor core 11 is x; the stator structure includes a stator core 31, and the axial height of the stator core 31 is w, where x≥w. Preferably, x≥1.05*w. In the present invention, 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, which does not rely on the excessive magnetic conductivity of the stator core 31, and can also improve the rotor magnetic field strength. Therefore, limiting the relationship between x and w can improve the utilization rate of the stator core 31 and reduce the rotor saturation degree.

[0148] In one embodiment, the axial height of the rotor structure is v, the axial height of the stator core 31 is w, and 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 saturation of the stator.

[0149] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0150] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0151] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A rotor structure, characterized in that: The invention comprises a rotor core (11), a first permanent magnet (12) and a second permanent magnet (21), wherein the rotor core (11) has a mounting groove, the first permanent magnet (12) is mounted in the mounting groove, and 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 arranged at an axial end of the rotor core (11), a groove (213) is arranged on the second permanent magnet (21), a 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 direction and / or tangential direction of the rotor core (11), the second permanent magnet (21) is magnetized along the axial direction of the rotor core (11), and at least two surfaces of the portion of the first permanent magnet (12) extending axially out of the rotor core (11) are surrounded by the second permanent magnet (21).

2. The rotor structure according to claim 1, characterized in that: The second permanent magnet (21) is provided with a hole structure (211).

3. The rotor structure according to claim 2, characterized in that: A projection is made onto an end face of the rotor core (11) along the axial direction of the rotor core (11), and within the projection face, the shape of the hole structure (211) matches the shape of the rotor core (11) at a corresponding position.

4. The rotor structure according to claim 2, characterized in that: The second permanent magnet (21) is provided with an identification portion (212).

5. The rotor structure according to claim 4, characterized in that: The identification portion (212) is arranged on an end surface of the second permanent magnet (21) on a side close to and / or away from the rotor core (11).

6. The rotor structure according to claim 4, characterized in that: The identification portion (212) is arranged in an adjacent area of ​​one of the hole structures (211).

7. The rotor structure according to claim 2, characterized in that: The number of the hole structures (211) provided on the second permanent magnet (21) is no less than 2.

8. The rotor structure according to claim 1, characterized in that: The second permanent magnet (21) is an injection-molded magnetic steel.

9. The rotor structure according to claim 1, characterized in that: The second permanent magnet (21) comprises an annular portion (215) and a magnetic pole portion (214), and the magnetic pole portion (214) is connected to the annular portion (215) to form a whole.

10. The rotor structure according to claim 9, characterized in that: The annular portion (215) is located radially inward of the second permanent magnet (21), and the groove (213) is formed between each adjacent magnetic pole portion (214). The magnetic pole portion (214) is radially arranged along the circumference of the annular portion (215) and is connected to the annular portion (215) via connecting ribs, thereby forming a whole with the annular portion (215).

11. The rotor structure according to claim 9, characterized in that: A through hole (13) is formed between the annular portion (215) and the end surface of the first permanent magnet (12) close to the rotating shaft, and the through hole (13) penetrates the rotor core (11) and the second permanent magnet (21) in the axial direction.

12. The rotor structure according to claim 1, characterized in that: The second permanent magnet (21) comprises a first permanent magnet limiting portion (216) and a magnetic pole portion (214); the first permanent magnet limiting portion (216) is arranged between adjacent magnetic pole portions (214) and connects adjacent magnetic pole portions (214) so ​​that the magnetic pole portions (214) become a whole.

13. The rotor structure according to claim 12, characterized in that: The first permanent magnet limiting portion (216) is located radially outside the slot (213) and is arranged corresponding to the slot (213). The first permanent magnet limiting portion (216) connects the second permanent magnets (21) on both sides in the circumferential direction.

14. The rotor structure according to claim 1, characterized in that: The slots (213) provided on the second permanent magnet (21) penetrate and / or do not penetrate the second permanent magnet (21), and the number of the slots (213) is the same as the number of rotor poles.

15. The rotor structure according to claim 1, characterized in that: The second permanent magnet (21) cooperates with the first permanent magnet (12) via a slot (213) provided thereon; the first permanent magnet (12) and the second permanent magnet (21) are both magnetic flux sources; and except for the rotor core (11), no other magnetic conductive components are provided in the rotor structure.

16. The rotor structure according to claim 12, characterized in that: The magnetic pole portions (214) are formed between adjacent slots (213), and on a plane perpendicular to the axial direction of the rotor core (11), the radial outer sides of adjacent magnetic pole portions (214) are disconnected and / or connected; the radial inner sides of adjacent magnetic pole portions (214) are disconnected and / or connected.

17. The rotor structure according to claim 16, characterized in that: A polar region of the magnetic pole portion (214) corresponds in position to a polar region of the rotor core (11); and on a plane perpendicular to the axial direction of the rotor core (11), a polar region of the magnetic pole portion (214) is adapted in shape to a corresponding polar region of the rotor core (11).

18. The rotor structure according to claim 1, characterized in that: At least one axial end of the rotor core (11) is provided with the second permanent magnet (21), and the number of the second permanent magnet (21) provided in the rotor structure is not less than one.

19. The rotor structure according to claim 1, characterized in that: The first permanent magnet (12) and the second permanent magnet (21) are divided into a plurality of polarity regions after being magnetized. The first permanent magnet (12) is magnetized with N-polarity alternating along the radial direction and / or tangential direction of the rotor core (11); and the second permanent magnet (21) is magnetized with N-polarity alternating along the axial direction of the rotor core (11).

20. The rotor structure according to claim 1 or 19, characterized in that: The polarity of the second permanent magnet (21) on the side close to the rotor core (11) is the first polarity, and the polarity of the two first permanent magnets (12) on both sides adjacent to the second permanent magnet (21) on the side close to the rotor core (11) is the first polarity.

21. The rotor structure according to claim 16, characterized in that: 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 magnetic pole portion (214) is z2, z2≤z1, wherein 0.2*(yx)≤z1≤1.6*(yx).

22. The rotor structure according to claim 21, characterized in that 2*z2≥(yx).

23. The rotor structure according to claim 22, characterized in that: z2=0.5*(yx).

24. The rotor structure according to any one of claims 1 to 19, characterized in that In a plane perpendicular to the axial direction of the rotor core (11), the length of a line between the rotor center axis and any point on the end edge of the second permanent magnet (21) close to the shaft side is Di2, and the length of a line between the rotor center axis and the center of the end edge of one pole of the first permanent magnet (12) close to the shaft side is Di3, and max(Di2)≥0.75*Di3.

25. The rotor structure according to claim 24, characterized in that max(Di2)≥Di3.

26. The rotor structure according to claim 1, characterized in that The outer peripheral wall of the rotor core (11) comprises a plurality of arc surfaces arranged at intervals, and along the circumferential direction of the rotor core (11), the distance between a single arc surface and the central axis of the rotor core (11) decreases from the middle to both ends.

27. The rotor structure according to any one of claims 1 to 19, characterized in that In a plane perpendicular to the axial direction of the rotor core (11), the length of a line between the rotor center axis and any point on the end edge of the second permanent magnet (21) close to the air gap is Do2, and the length of a line between the rotor center axis and the center of the end edge of one pole of the first permanent magnet (12) close to the air gap is Do3, and max(Do2)≤1.2*Do3.

28. The rotor structure according to claim 27, characterized in that |max(Do2)-Do3|≤1.5mm.

29. The rotor structure according to claim 8, characterized in that The second permanent magnet (21) is injection-molded ferrite or injection-molded neodymium iron boron.

30. The rotor structure according to claim 1, characterized in that The first permanent magnet (12) is a sintered permanent magnet or an injection-molded permanent magnet.

31. The rotor structure according to claim 1, characterized in that The intrinsic coercive force of the second permanent magnet (21) is lower than the intrinsic coercive force of the first permanent magnet (12).

32. The rotor structure according to claim 1, characterized in that The rotor core (11) is formed by stacking silicon steel sheets, or the rotor core (11) is injection-molded magnetic steel. In a plane perpendicular to the axial direction of the rotor core (11), along the radial direction, the rotor core (11) is magnetized alternately with N and S poles.

33. The rotor structure according to claim 1, characterized in that The second permanent magnet (21) is injection-molded, coated or filled on the rotor core (11), or the second permanent magnet (21), the rotor core (11) and the first permanent magnet (12) are separately manufactured and then assembled together.

34. The rotor structure according to claim 1, characterized in that The rotor structure is filled with molding compound at the end and the inner gap and molded into a whole, or the rotor structure is assembled and fixed together by fasteners.

35. A motor, comprising a stator structure and a rotor structure, characterized in that: The rotor structure is the rotor structure according to any one of claims 1 to 34, and the stator structure is sleeved on the outer peripheral side of the rotor structure.

36. The electric machine according to claim 35, characterized in that The axial height of the rotor core (11) is x; the stator structure comprises a stator core (31), and the axial height of the stator core (31) is w, where x≥w.

37. The electric machine according to claim 36, characterized in that x≥1.05*w.

38. The electric machine according to claim 36, characterized in that The axial height of the rotor structure is v, the axial height of the stator core (31) is w, and v≥1.4*w.

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