Rotor structure and electric machine

Abstract

The application provides a rotor structure and a motor. The rotor structure comprises 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 not 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, and the surface of the second permanent magnet close to the rotor core is a plane. The first permanent magnet is magnetized along the radial direction and / or the tangential direction of the rotor core, and the second permanent magnet is magnetized along the axial direction of the rotor core. The second permanent magnet is an injection-molded magnetic steel. According to the rotor structure, the magnetic aggregation effect of the motor can be improved, the magnetic leakage at the axial end of the first permanent magnet is reduced, and the rotor structure has the advantages of fewer components, fewer assembly steps, simple assembly and low production cost.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and more specifically, to a rotor structure and a motor. Background Technology

[0002] 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.

[0003] 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.

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

[0005] Prior art document 201880064666.X discloses a permanent magnet rotor assembly. This assembly contains two sets of permanent magnets (a first set magnetized circumferentially along the rotor, and a 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 complexity, resulting in high production and assembly costs and hindering practical application. Summary of the Invention

[0006] The main objective of this invention is to provide a rotor structure and motor that can improve the magnetizing effect of the motor, reduce the magnetic leakage at the axial end of the first permanent magnet, and has fewer parts, fewer assembly steps, simpler assembly, and lower production cost.

[0007] To achieve the above objectives, according to one aspect of the present invention, a rotor structure is provided, comprising 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 not greater than the axial height of the rotor core. The second permanent magnet is disposed at the axial end of the rotor core, and the surface of the second permanent magnet near the rotor core is a plane. 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. The second permanent magnet is an injection-molded magnet.

[0008] Furthermore, the second permanent magnet has a flat ring structure, and both the first and second permanent magnets are magnetic flux sources. Apart from the rotor core, no other magnetically conductive components are installed in the rotor structure.

[0009] Furthermore, the second permanent magnet has a first hole structure, and the rotor core has a second hole structure corresponding to the first hole structure.

[0010] Furthermore, a projection is made on one end face of the rotor core along the axial direction of the rotor core, and within this projection plane, the shape of the first hole structure matches the shape of the second hole structure of the rotor core at the corresponding position.

[0011] Furthermore, the second permanent magnet has at least two first hole structures, each with a built-in fastener. The fastener passes through the second hole structure and traverses the rotor core and the second permanent magnet.

[0012] Furthermore, after the first and second permanent magnets are magnetized, they are divided into multiple polarity regions with opposite polarities between adjacent regions. The polarity of one polarity region of the second permanent magnet is the first polarity on the side closest to the rotor core, and the polarities of the two first permanent magnets on the sides adjacent to this polarity region of the second permanent magnet are also the first polarities on the side closest to the rotor core.

[0013] Furthermore, the outer peripheral wall of the rotor core includes multiple spaced arc surfaces, and the distance between a single arc surface and the central axis of the rotor core decreases from the middle to both ends along the circumferential direction of the rotor core.

[0014] Furthermore, the intrinsic coercivity of the second permanent magnet is lower than that of the first permanent magnet.

[0015] Furthermore, the area of ​​a polar region of the second permanent magnet near the rotor core is s1, and the area of ​​the surface of the first permanent magnet perpendicular to the magnetization direction of the first permanent magnet is s2. Then 0.2≤s1 / s2≤1.

[0016] Furthermore, a projection is made on one end face of the rotor core along the axial direction of the rotor core. In this projection plane, the area of ​​a polar region of the rotor core is s3, and the area of ​​a first permanent magnet is s4. Then, s3 / s4≥1.1.

[0017] According to another aspect of the present invention, an electric motor is provided, comprising 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.

[0018] According to the technical solution of this invention, 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 not greater than the axial height of the rotor core. The second permanent magnet is disposed at the axial end of the rotor core, and the surface of the second permanent magnet near the rotor core is a plane. 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. The second permanent magnet is an injection-molded magnet.

[0019] By simultaneously incorporating a first permanent magnet and a second permanent magnet in the rotor, the two magnets jointly provide magnetic flux to the motor, thereby increasing its output power. The magnetic lines of force of the first permanent magnet enter the rotor core tangentially, while those of the second permanent magnet enter from the axial end of the rotor core. After the magnetic lines of force 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 leakage magnetic lines of force at the axial end 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 field of the first permanent magnet, and the flow direction of the magnetic lines of force of the second permanent magnet is opposite to that of the end leakage magnetic lines of the first permanent magnet, resulting in a mutual repulsion effect. This further reduces the axial end leakage magnetic field of the first permanent magnet and increases the rotor's magnetic field strength. Attached Figure Description

[0020] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0021] Figure 1 A perspective structural diagram of a rotor structure according to an embodiment of the present invention is shown;

[0022] Figure 2 An exploded structural diagram of a rotor structure according to an embodiment of the present invention is shown;

[0023] Figure 3A top view of a rotor structure according to an embodiment of the present invention is shown;

[0024] Figure 4 It shows Figure 3 Sectional view along axis AA;

[0025] Figure 5 A side view of a rotor structure according to an embodiment of the present invention is shown;

[0026] Figure 6 It shows Figure 5 CC-direction sectional view;

[0027] Figure 7 A cross-sectional view of a rotor structure according to an embodiment of the present invention is shown;

[0028] Figure 8 A perspective structural diagram of a motor according to an embodiment of the present invention is shown;

[0029] Figure 9 A perspective structural diagram of a rotor structure according to another embodiment of the present invention is shown;

[0030] Figure 10 A comparison diagram of the magnetic flux density of a motor according to an embodiment of the present invention and a motor of related technologies is shown;

[0031] Figure 11 A graph showing the relationship between s1 / s2 and the superposition effect of the magnetic field in the motor of an embodiment of the present invention is shown.

[0032] The above figures include the following reference numerals:

[0033] 11. Rotor core; 111. Second hole structure; 12. First permanent magnet; 21. Second permanent magnet; 211. First hole structure; 31. Stator core. Detailed Implementation

[0034] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0035] See also Figures 1 to 9As 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, 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 not 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 the surface of the second permanent magnet 21 near the rotor core 11 is a plane. 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 second permanent magnet 21 is an injection-molded magnet.

[0036] like Figure 7 As shown, 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 magnetic lines of force of the first permanent magnet 12 enter the rotor core 11 tangentially, and the magnetic lines of force of the second permanent magnet 21 enter from the axial end of the rotor core 11. After the magnetic lines of force of the first permanent magnet 12 and the second permanent magnet 21 are magnetized on the rotor core 11, they enter the air gap and the stator, which can significantly improve the magnetization efficiency of the rotor. Furthermore, apart from the rotor core 11, no other magnetically conductive components are provided 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-magnetically conductive 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 increase the rotor magnetic field strength.

[0037] 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.

[0038] like Figure 7 In the embodiment shown, the first permanent magnet 12 with a larger axial height is configured to be tangentially magnetized, and the second permanent magnet 21 located at the axial end of the rotor core 11 is configured to be axially magnetized. This enables the continuity of the magnetic flux of the first permanent magnet 12 and the second permanent magnet 21, allowing them to more effectively provide magnetic flux to the motor and effectively increase the motor output.

[0039] like Figure 9In the embodiment shown, the first permanent magnet 12 is configured to be radially magnetized and the second permanent magnet 21 is configured to be axially magnetized. The magnetic flux generated by the first permanent magnet 12 and the second permanent magnet 21 enters the air gap through different paths, which has the effect of focusing magnetization. At the same time, it can reduce the saturation of the rotor core 11 and reduce saturation loss.

[0040] In one embodiment, the first permanent magnet 12 is a combined magnet design of tangential magnetization and radial magnetization.

[0041] 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.

[0042] In one embodiment, the axial height of the first permanent magnet 12 is equal to the axial height of the rotor core 11. The magnetic lines of force of the second permanent magnet 21 flow into the rotor core 11 through the first permanent magnet 12 or directly into the rotor core 11. After the magnetic lines of force of the first permanent magnet 12 and the second permanent magnet 21 are magnetized on the rotor core 11, they enter the air gap and the stator, which can greatly improve the magnetization effect of the rotor and increase the torque density of the motor.

[0043] In one embodiment, the axial height of the first permanent magnet 12 is lower than the axial height of the rotor core 11, and the axial end face of the first permanent magnet 12 does not contact the second permanent magnet 21. The first permanent magnet 12 and the second permanent magnet 21 together serve as magnetic excitation sources, and their magnetic circuits are connected in parallel to generate a magnetic focusing effect. The lower axial height of the first permanent magnet 12 can improve its utilization rate.

[0044] In one embodiment, the second permanent magnet 21 is a flat, ring-shaped structure. Both the first permanent magnet 12 and the second permanent magnet 21 are magnetic flux sources. Apart from the rotor core 11, no other magnetically conductive components are present in the rotor structure. The second permanent magnet 21 is not limited to an integral or modular structure; preferably, it is an integral structure, which reduces rotor components, resulting in fewer assembly steps, simpler assembly, and lower production costs. The absence of other magnetically conductive components besides the rotor core 11 further reduces the number of rotor components and lowers assembly costs.

[0045] In one embodiment, the second permanent magnet 21 is provided with a first hole structure 211, and the rotor core 11 is provided with a second hole structure 111 corresponding to the first hole structure 211. The shapes of the first hole structure 211 and the second hole structure 111 are not limited to circular, elliptical, square or other shapes.

[0046] 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. Within this projection plane, the shape of the first hole structure 211 matches the shape of the second hole structure 111 of the rotor core 11 at the corresponding position. 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 matching of the shape of the first hole structure 211 with the shape of the second hole structure 111 of the rotor core 11 at the corresponding position 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 first hole structure 211 can guide the magnetic field of the second permanent magnet 21, ensuring the uniformity and unsaturation of the magnetic field distribution of the rotor core 11 and reducing rotor iron loss.

[0047] In one embodiment, the number of first hole structures 211 provided on the second permanent magnet 21 is not less than two. Preferably, 2p first hole structures 211 are evenly distributed on the circumference of the second permanent magnet 21, where p is the number of rotor pole pairs, to ensure the symmetry of the rotor magnetic field, reduce torque pulsation and harmonic loss caused by magnetic field asymmetry, and at the same time, make the force on the second permanent magnet 21 and the rotor core 11 at different positions on the circumference uniform when the rotor rotates, preventing local separation between the second permanent magnet 21 and the rotor core 11.

[0048] In one embodiment, a fastener is embedded in the first hole structure 211, and the fastener passes through the second hole structure 111, penetrating the rotor core 11 and the second permanent magnet 21. Fasteners are placed in the first hole structure 211 of the second permanent magnet 21 and the second hole structure 111 on the rotor core 11 for rotor assembly, ensuring that the rotor core 11, the first permanent magnet 12, and the second permanent magnet 21 do not shift in the axial and circumferential directions to maintain the stability of the rotor structure.

[0049] 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.

[0050] 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.

[0051] 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. Preferably, 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 enabling the magnetic circuit at the motor end to be sorted out, resulting in greater torque density, higher motor efficiency, and ensuring high motor performance. Along the axial direction of the rotor core 11, the rotor core 11 and the second permanent magnets 21 are attached together 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.

[0052] 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.

[0053] 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.

[0054] The polarity of a polarity region of the second permanent magnet 21 near the rotor core 11 is the first polarity. The polarity of the two first permanent magnets 12 adjacent to this polarity region of the second permanent magnet 21 near the rotor core 11 is also the first polarity. In other words, the polarity of the side of the second permanent magnet 21 near the rotor core 11 is the same as the polarity of the two adjacent first permanent magnets 12 near the rotor core 11. Figure 7 In the embodiment shown, the second permanent magnet 21 is axially magnetized and the first permanent magnet 12 is tangentially magnetized. At 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 unloaded magnetic flux.

[0055] In one embodiment, a limiting protrusion is provided on the outer periphery of the rotor core 11. The limiting protrusion 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.

[0056] In this embodiment, the limiting protrusions are located at the outermost periphery of the rotor core 11 and extend circumferentially from two sides of the rotor core 11 in the circumferential direction. The two limiting protrusions extending in opposite directions are spaced apart, thereby forming an open slot structure while radially limiting the first permanent magnet 12, reducing the radial magnetic leakage of the first permanent magnet 12.

[0057] 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.

[0058] In this embodiment, since the rotor core 11 forms an open slot structure, the outer periphery of the rotor core 11 is not a complete circle, but rather a plurality 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] In one embodiment, the rotor core 11 is made of stacked silicon steel sheets, which has better magnetic permeability.

[0064] 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.

[0065] In one embodiment, the second permanent magnet 21 is injection molded onto or filled onto the rotor core 11.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] In one embodiment, the area of ​​a polar region of the second permanent magnet 21 near the rotor core 11 is s1, and the area of ​​the surface of the first permanent magnet 12 perpendicular to its magnetization direction is s2, then 0.2 ≤ s1 / s2 ≤ 1. Limiting the ratio of the magnetizing area of ​​the second permanent magnet 21 to the magnetizing area of ​​the first permanent magnet 12 can effectively adjust the intensity ratio of the tangential magnetic field generated by the first permanent magnet 12 and the axial magnetic field generated by the second permanent magnet 21, reducing the impact of saturation on the axial magnetic field, improving the superposition effect of the tangential and axial magnetic fields, and increasing the utilization rate of the axial magnetic field. Figure 11 The figure shows the relationship between s1 / s2 and the magnetic field superposition effect. The magnetic field superposition effect is measured by the ratio of the air gap magnetic field strength of the motor in this embodiment of the invention to the sum of the air gap magnetic field strength generated by the first permanent magnet 12 alone and the air gap magnetic field strength generated by the second permanent magnet 21 alone. As shown in the figure, when s1 / s2 < 0.2, the magnetic field superposition effect is in the climbing stage. When s1 / s2 is in the range of 0.2 to 1, the magnetic field superposition effect is better and maintains a high value. When s1 / s2 > 1, the magnetic field superposition effect begins to decrease due to the saturation of the rotor core 11.

[0071] 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. In this projection plane, the area of ​​a polar region of the rotor core 11 is s3, and the area of ​​a first permanent magnet 12 is s4. Then s3 / s4≥1.1, so as to ensure that the rotor core 11 has a large area on the circumferential surface of the rotor to provide a magnetic flux loop for the first permanent magnet 12, so that the magnetic flux of the first permanent magnet 12 can enter the rotor as much as possible.

[0072] See also Figure 10 As shown, compared with motors of related technologies, the motor using the rotor structure of this invention has a magnetic flux density increased by more than 60%, and its magnetic flux density performance is significantly improved.

[0073] According to an embodiment of the present invention, 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.

[0074] 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.

[0075] 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.

[0076] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A rotor structure, characterized in that, The device 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 installed in the mounting groove along the axial direction of the rotor core (11). The axial height of the first permanent magnet (12) is not 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). The surface of the second permanent magnet (21) near the rotor core (11) is a plane. 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). The second permanent magnet (21) is an injection-molded magnet.

2. The rotor structure according to claim 1, characterized in that, The second permanent magnet (21) is a flat ring structure. 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.

3. The rotor structure according to claim 1, characterized in that, The second permanent magnet (21) is provided with a first hole structure (211), and the rotor core (11) is provided with a second hole structure (111) corresponding to the first hole structure (211).

4. The rotor structure according to claim 3, characterized in that, Projecting a view of one end face of the rotor core (11) along the axial direction of the rotor core (11) into the projection plane, wherein the shape of the first hole structure (211) is adapted to the shape of the second hole structure (111) of the rotor core (11) at the corresponding position.

5. The rotor structure according to claim 3, characterized in that, The number of first hole structures (211) provided on the second permanent magnet (21) is not less than two. The first hole structure (211) has a built-in fastener. The fastener passes through the second hole structure (111) and penetrates the rotor core (11) and the second permanent magnet (21).

6. The rotor structure according to claim 1, characterized in that, After being magnetized, the first permanent magnet (12) and the second permanent magnet (21) are divided into multiple polarity regions. The polarities of adjacent polarity regions are opposite. The polarity of one polarity region of the second permanent magnet (21) on the side closer to the rotor core (11) is the first polarity. The polarities of the two first permanent magnets (12) on the side adjacent to the polarity region of the second permanent magnet (21) on the side closer to the rotor core (11) are also the first polarity.

7. The rotor structure according to claim 1, characterized in that, The outer peripheral wall of the rotor core (11) includes a plurality of spaced arc surfaces. 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.

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

9. The rotor structure according to claim 6, characterized in that, The area of ​​one polar region of the second permanent magnet (21) near the rotor core (11) is s1, and the area of ​​the surface of the first permanent magnet (12) perpendicular to the magnetization direction of the first permanent magnet (12) is s2, then 0.2≤s1 / s2≤1.

10. The rotor structure according to claim 6, characterized in that, Projecting a plane along the axial direction of the rotor core (11) onto one end face of the rotor core (11), within the projection plane, the area of ​​a polar region of the rotor core (11) is s3, and the area of ​​a first permanent magnet (12) is s4, then s3 / s4≥1.

1.

11. An electric 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 10, and the stator structure is sleeved on the outer periphery of the rotor structure.

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