Rotor structure and electric motor

Abstract

Provided in the present application are a rotor structure and an electric motor. The rotor structure comprises a rotor core, a first permanent magnet, a second permanent magnet and a rotating shaft. The rotor core comprises an outer rotor core and an inner rotor core, a gap being formed between the outer rotor core and the inner rotor core. The outer rotor core is provided with a mounting slot, and the first permanent magnet is mounted in the mounting slot. The second permanent magnet is provided with a groove, and part of the first permanent magnet is inserted into the groove. The first permanent magnet is magnetized in a tangential direction, and the second permanent magnet is magnetized in an axial direction. The second permanent magnet and the rotor core are provided with corresponding through-hole portions, the number of through-hole portions on the outer rotor core being less than or equal to 1. A second connecting portion is provided in the through-hole portion. The rotor structure further comprises a first connecting portion, which is arranged in the gap. The viscoelasticity of the material of the first connecting portion is greater than or equal to that of material of the second connecting portion. The rotor structure of the present application can ensure the torque output capability of the electric motor while effectively reducing vibration and noise in the electric motor.

Description

Rotor structure and motor

[0001] This application claims priority to Chinese invention patent application number "202411802610.3", application date "December 9, 2024", entitled "Rotor Structure and Motor". Technical Field

[0002] This application relates to the field of motor technology, and more specifically, to a rotor structure and a motor. Background Technology

[0003] 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.

[0004] 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.

[0005] Existing technical solutions, while increasing the torque density of the motor, can also lead to oversaturation of the motor's magnetic field, resulting in increased harmonic content and causing vibration and noise problems. There is a conflict between the methods of optimizing vibration and noise from the perspective of electromagnetic principles and the performance requirements of the motor. The existing method of filling the shaft and shaft hole with damping material also has the problem of poor damping effect. Therefore, how to further reduce the vibration and noise of the motor while ensuring the torque output capacity of the motor is an urgent problem to be solved. Summary of the Invention

[0006] The main objective of this application is to provide a rotor structure and motor that can effectively reduce motor vibration and noise while ensuring the motor's torque output capability.

[0007] To achieve the above objectives, according to one aspect of this application, a rotor structure is provided, including a rotor core, a first permanent magnet, a second permanent magnet, and a rotating shaft. The rotor core includes an outer rotor core and an inner rotor core. The outer rotor core is sleeved on the outer periphery of the inner rotor core, forming a gap between them. The outer rotor core has a mounting groove, and the first permanent magnet is mounted in the mounting groove. Along the axial direction of the rotor core, the axial height of the first permanent magnet is greater than the axial height of the outer rotor core. The second permanent magnet is disposed at the axial end of the outer rotor core, and a recess is provided on the second permanent magnet. The first permanent magnet extends axially out of the outer rotor core and is inserted into the groove. The first permanent magnet is magnetized along 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 and the rotor core are respectively provided with through holes that extend axially along the rotor core. Under one pole, the number of through holes on the outer rotor core is less than or equal to 1. A second connecting part is provided in the through hole. The rotor structure also includes a first connecting part, which is provided in the gap. The viscoelasticity of the material of the first connecting part is greater than or equal to the viscoelasticity of the material of the second connecting part.

[0008] In some embodiments, at one pole, a through hole is provided on the outer rotor core and a through hole is provided on the inner rotor core, and a second connecting portion is provided in both the through hole of the outer rotor core and the through hole of the inner rotor core.

[0009] In some embodiments, at one pole, a through hole is provided on the outer rotor core, and no through hole is provided on the inner rotor core; or, at one pole, no through hole is provided on the outer rotor core, and a through hole is provided on the inner rotor core.

[0010] In some embodiments, the outer rotor core or the second connecting portion has a recess on the inner peripheral side near the inner rotor core, and the inner rotor core has a protrusion on the outer peripheral side near the outer rotor core. The protrusion is placed in the recess and a gap is formed between them. The first connecting portion is provided in the gap.

[0011] In some embodiments, the first connecting portion and the second connecting portion are made of a non-magnetic material.

[0012] In some embodiments, the first connecting portion includes a first radial connecting portion and a first axial connecting portion, and the second connecting portion includes a second radial connecting portion and a second axial connecting portion, wherein the second connecting portion is located radially outside the first connecting portion.

[0013] In some embodiments, the first radial connecting portion and the second radial connecting portion are located at the axial ends of the rotor core, and the first axial connecting portion and the second axial connecting portion are embedded in the rotor core.

[0014] According to another aspect of this application, a rotor structure is provided, including a rotor core, a first permanent magnet, a second permanent magnet, and a shaft. A first gap is formed between the rotor core and the first permanent magnet. The rotor core includes an outer rotor core and an inner rotor core. The outer rotor core is sleeved on the outer periphery of the inner rotor core and has a mounting groove. The first permanent magnet is mounted in the mounting groove. Along the axial direction of the rotor core, the axial height of the first permanent magnet is greater than the axial height of the outer rotor core. The second permanent magnet is disposed at the axial end of the outer rotor core and has a groove. A permanent magnet extends axially from the outer rotor core and is inserted into a groove. The first permanent magnet is magnetized along 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 and the rotor core are respectively provided with through holes that extend axially through the rotor core. In one pole, the number of through holes on the outer rotor core is less than or equal to 1. A first connecting part is provided in the through hole. The rotor structure also includes a second connecting part, which is provided in the first gap. The viscoelasticity of the material of the first connecting part is greater than or equal to the viscoelasticity of the material of the second connecting part.

[0015] In some embodiments, the through hole extends through the second permanent magnet and the outer rotor core along the axial direction of the rotor core.

[0016] In some embodiments, the rotor structure further includes an inner rotor core, with a through hole extending through the second permanent magnet and the inner rotor core along the axial direction of the rotor core.

[0017] In some embodiments, the outer rotor core or the second connecting portion has a recess on the inner peripheral side near the inner rotor core, and the inner rotor core has a protrusion on the outer peripheral side near the outer rotor core. The protrusion is placed in the recess and a second gap is formed between them. The first connecting portion is provided in the second gap.

[0018] In some embodiments, a first gap is formed between the sidewall of the mounting groove and the first permanent magnet, and a second connecting portion is provided within the first gap.

[0019] In some embodiments, after the first permanent magnet and the second permanent magnet are magnetized, they are divided into multiple polarity regions. The polarities of adjacent polarity regions of the second permanent magnet are opposite. The polarity of the two first permanent magnets adjacent to a polarity region of the second permanent magnet is the same as the polarity of the side of the polarity region closest to the rotor core.

[0020] In some embodiments, the first permanent magnet is made of sintered magnetic material, and the second permanent magnet is made of plastic magnetic material.

[0021] According to another aspect of this application, an electric motor is provided, including a stator structure and a rotor structure, wherein the rotor structure is the rotor structure described above, and the stator structure is sleeved on the outer periphery of the rotor structure.

[0022] According to the technical solution of this application, the rotor structure includes a rotor core, a first permanent magnet, a second permanent magnet, and a rotating shaft. The rotor core includes an outer rotor core, with a gap between the outer rotor core and the rotating shaft. The outer rotor core has a mounting groove, and the first permanent magnet is installed in the mounting groove. Along the axial direction of the rotor core, the axial height of the first permanent magnet is greater than the axial height of the outer rotor core. The second permanent magnet is disposed at the axial end of the outer rotor core, and a groove is provided on the second permanent magnet. The portion of the first permanent magnet extending axially from the outer rotor core is inserted into the groove. The first permanent magnet is magnetized along the tangential direction of the rotor core, and the second permanent magnet is magnetized along the axial direction of the rotor core. Corresponding through holes are provided on the second permanent magnet and the rotor core, extending axially along the rotor core. A second connecting portion is provided in the through hole. The rotor structure also includes a first connecting portion, and the viscoelasticity of the material of the first connecting portion is greater than or equal to the viscoelasticity of the material of the second connecting portion.

[0023] Simultaneously incorporating a first permanent magnet and a second permanent magnet within the rotor, the first and second permanent magnets jointly provide magnetic flux to the motor, increasing its output power. The relative positioning of the first and second permanent magnets, with the first permanent magnet inserted into a groove in the second, allows it to act as part of the magnetic flux path of the second permanent magnet, drawing its magnetic flux lines into the rotor core. After the magnetic flux lines of the first and second permanent magnets are magnetized on the rotor core, they then enter the air gap and stator, significantly improving the rotor's magnetization effect. The presence of the second permanent magnet reduces magnetic leakage at the rotor's axial end, increasing the motor's permanent magnet flux linkage. Axially penetrating through-holes are provided on both the second permanent magnet and the rotor core. These through-holes increase the number of connection points, making the connection between the rotor core, the first permanent magnet, and the second permanent magnet more stable and maintaining the rotor's structural integrity. The connection points within the through-holes of the second permanent magnet hinder the transmission of electromagnetic waves, thereby weakening vibration transmission between the rotor and the shaft and reducing vibration noise in the rotor structure. Attached Figure Description

[0024] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0025] Figure 1 shows an exploded structural diagram of a rotor structure according to an embodiment of this application;

[0026] Figure 2 shows a cross-sectional structural diagram of a rotor structure according to an embodiment of this application;

[0027] Figure 3 shows an exploded structural diagram of a rotor structure according to an embodiment of this application;

[0028] Figure 4 shows a perspective structural diagram of the rotor structure of an embodiment of this application;

[0029] Figure 5 shows a top view of the rotor structure of an embodiment of this application;

[0030] Figure 6 shows a cross-sectional view along line AA of Figure 5;

[0031] Figure 7 shows an exploded structural diagram of a rotor structure according to an embodiment of this application.

[0032] The above-mentioned figures include the following reference numerals: 1. Rotor core; 11. Outer rotor core; 12. Inner rotor core; 13. Mounting groove; 14. Recess; 15. Protrusion; 2. First permanent magnet; 3. Second permanent magnet; 31. Groove; 4. Through hole; 5. First connecting part; 51. First radial connecting part; 52. First axial connecting part; 6. Second connecting part; 61. Second radial connecting part; 62. Second axial connecting part; 8. Shaft. Detailed Implementation

[0033] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0034] Referring to Figures 1 to 7, according to an embodiment of this application, the rotor structure includes a rotor core 1, a first permanent magnet 2, a second permanent magnet 3, and a rotating shaft 8. The rotor core 1 includes an outer rotor core 11, with a gap between the outer rotor core 11 and the rotating shaft 8. The outer rotor core 11 has a mounting groove 13, and the first permanent magnet 2 is installed in the mounting groove 13. Along the axial direction of the rotor core 1, the axial height of the first permanent magnet 2 is greater than the axial height of the outer rotor core 11. The second permanent magnet 3 is disposed at the axial end of the outer rotor core 11, and a groove 31 is provided on the second permanent magnet 3. The portion of the first permanent magnet 2 extending axially from the outer rotor core 11 is inserted into the groove 31. The first permanent magnet 2 is magnetized along the tangential direction of the rotor core 1, and the second permanent magnet 3 is magnetized along the axial direction of the rotor core 1. The second permanent magnet 3 and the rotor core 1 are correspondingly provided with through holes 4 that extend along the axial direction of the rotor core 1, and a second connecting portion 6 is provided in the through holes 4.

[0035] By simultaneously incorporating a first permanent magnet 2 and a second permanent magnet 3 within the rotor, the two magnets work together to provide magnetic flux to the motor, thereby increasing its output power. The design of the relative positions of the first and second permanent magnets, with the first permanent magnet 2 inserted into the groove of the second permanent magnet 3, allows it to function as part of the magnetic flux path of the second permanent magnet 3, drawing its magnetic flux lines into the rotor core. After the magnetic flux lines of the first and second permanent magnets 3 are magnetized on the rotor core 1, they then enter the air gap and stator, significantly improving the rotor's magnetization effect. The presence of the second permanent magnet 3 reduces magnetic leakage at the rotor's axial end, thus increasing the motor's permanent magnet flux linkage. The second permanent magnet 3 and the rotor core 1 are provided with through holes 4 that extend in the axial direction. The projections of the through holes 4 on the XY plane perpendicular to the central axis of the rotor core 1 are completely coincident. The presence of the through holes 4 increases the number of second connecting parts 6, which can make the connection between the outer rotor core 11, the first permanent magnet 2 and the second permanent magnet 3 more stable and maintain the integrity of the rotor structure. The connecting parts provided in the through holes 4 of the second permanent magnet 3 can hinder the transmission of electromagnetic force waves, thereby weakening the vibration transmission between the rotor and the shaft and reducing the vibration noise of the rotor structure.

[0036] Compared to the prior scheme of the inventors, which set two through-hole structures on the outer rotor core, the applicant has modified the two through-hole structures on the outer rotor core to a through-hole structure of no more than one on the outer rotor core in the embodiments of this application.

[0037] Regarding the inventor's prior art (application number 202410682720.4), the proposed solution involves two through-hole structures on the outer rotor core 11. One through-hole is filled with a second connecting portion 6, connecting the outer rotor core 11, the first permanent magnet 2, and the second permanent magnet 3 into a whole. The other through-hole is filled with a first connecting portion 5, connecting the outer rotor core 11, the first permanent magnet 2, the second permanent magnet 3, and the inner rotor core into a whole. This simultaneously enables the transmission and coupling of forces between the inner and outer rotor cores. The structure of the two through-holes helps to enhance the overall structural strength of the rotor structure. The second permanent magnet 3 is located at the axial end of the outer rotor core 11. To ensure the flow path when the first connecting portion 5 and the second connecting portion 6 are filled, the second permanent magnet 3 also has through-holes at the positions corresponding to the through-holes in the outer rotor core 11.

[0038] In the prior design, two through-hole structures penetrated the second permanent magnet 3 axially, resulting in a reduction in the magnetizing area of ​​the second permanent magnet 3 and a decrease in the magnetic flux provided by the rotor. Therefore, the two through-hole structure sacrificed the rotor magnetic flux to improve the rotor's mechanical strength. However, considering the need to improve motor energy efficiency, during rotor manufacturing, the two through-hole structures were modified to a single through-hole structure. When there is only one through-hole structure located in the outer rotor core 11, the through-hole structure is filled with a second connecting part 6, connecting the outer rotor core 11, the first permanent magnet 2, and the second permanent magnet 3 into a whole, ensuring the rotor's mechanical strength. The inner and outer rotor cores are connected by the interlocking of recesses and protrusions and the first connecting part 5 filled between them, achieving force transmission and coupling between the inner and outer rotor cores through the cooperation of the mechanical structure.

[0039] Meanwhile, the applicant's research found that when the through-hole structure is 1 and located on the outer rotor core 11, the through-hole structure is filled with a first connecting part 5, and the second connecting part 6 is connected through the first gap between the first permanent magnet 2 and the mounting slot to form a cage-like structure. The second connecting part 6 of this cage-like structure also has a certain mechanical strength, which meets the strength requirements in applications where the motor speed requirement is not high. The first connecting part 5 filled in the through-hole structure connects the inner and outer rotor cores 11 to form a whole, realizing the transmission and coupling of forces between the two. Compared with the scheme of two through-hole structures, the embodiment with one through-hole structure located on the outer rotor core 11 can weaken the effect of rotor flux reduction caused by the through-hole structure, while ensuring that the mechanical strength of the rotor meets the usage requirements.

[0040] Furthermore, when the outer rotor core 11 does not have a through-hole structure, but has one through-hole structure on the inner rotor core, the second connecting part 6 still forms a cage-like structure through the first gap between the first permanent magnet 2 and the mounting groove. The through-hole structure is filled with the first connecting part 5, and the force transmission between the inner and outer rotor cores 11 is achieved through the interlocking of the recesses and protrusions. This embodiment moves the through-hole portion on the second permanent magnet 3 to the side closer to the shaft. Because it is farther from the air gap between the stator and rotor, it can further reduce the rotor flux drop caused by the through-hole structure. It has been verified that the embodiments of this application can meet the rotor structure strength requirements in situations where the motor speed requirement is not high (3000 rpm and below), and the motor performance is better.

[0041] In one embodiment, the rotor core 1 further includes an inner rotor core 12, and an outer rotor core 11 is sleeved on the outer periphery of the inner rotor core 12, forming a gap between them. A first connecting portion 5 is provided in the gap.

[0042] In this embodiment, the outer rotor core 11 and the inner rotor core 12 are connected by a first connecting portion 5. The connection between the outer rotor core 11 and the inner rotor core 12 weakens the transmission of rotor vibration in the radial direction. Furthermore, due to the presence of the inner rotor core 12, the connection between the rotor core 1 and the shaft 8 is more stable. The material of the first connecting portion 5 has greater viscoelasticity, which is more conducive to weakening the transmission of vibration between the inner and outer rotor cores and reducing noise.

[0043] The cross-sectional shape of the through hole 4 is, for example, polygonal, circular, elliptical, etc.

[0044] In one embodiment, the viscoelasticity of the material of the first connecting portion 5 is greater than or equal to the viscoelasticity of the material of the second connecting portion 6.

[0045] Viscoelasticity refers to the combined property of a material in exhibiting both elastic and viscous deformation under stress. When subjected to external forces, a material undergoes elastic deformation, meaning it deforms under the influence of force but returns to its original shape once the force is removed. Simultaneously, the material also exhibits viscous deformation, meaning it stretches and deforms to a certain extent under stress and retains this deformation even after the force is removed. Viscoelasticity is a property between elasticity and plasticity, commonly found in materials such as polymers and biological tissues.

[0046] Viscoelastic materials include, for example, polymers, rubbers, and colloids.

[0047] In one embodiment, the first connecting part 5 and the second connecting part 6 are made of a non-magnetic material.

[0048] The connecting part is made of non-magnetic material, which can more effectively block the transmission of electromagnetic force waves at the connecting part, thereby more effectively weakening the vibration transmission between the rotor and the shaft and reducing the vibration noise of the rotor structure.

[0049] In one embodiment, the cross-sectional shape of the through hole 4 is circular; in another embodiment, the cross-sectional shape of the through hole 4 is rectangular.

[0050] In one embodiment, the first connecting portion 5 includes a first radial connecting portion 51 and a first axial connecting portion 52, and the second connecting portion 6 includes a second radial connecting portion 61 and a second axial connecting portion 62, with the second connecting portion 6 located radially outside the first connecting portion 5. The first radial connecting portion 51 and the second radial connecting portion 61 are located at the axial ends of the rotor core 1, and the first axial connecting portion 52 and the second axial connecting portion 62 are embedded within the rotor core 1.

[0051] The rotor structure has a first radial connection portion 51 formed by filling the axial outer end faces of the inner rotor core 12 and the outer rotor core 11, as well as the gap between the inner rotor core 12 and the outer rotor core 11 with a viscoelastic material. The radial outer surface of the first radial connection portion 51 located in the gap between the inner rotor core 12 and the outer rotor core 11 contacts the radial inner surface of the outer rotor core 11, and the inner surface of the first radial connection portion 51 contacts the radial outer surface of the inner rotor core 12. The first radial connection portion 51 serves to connect the inner rotor core 12, the outer rotor core 11, and the rotating shaft 8 in the radial direction of the rotor structure, and absorbs and blocks the transmission of electromagnetic excitation force in the radial direction of the rotor structure, thereby eliminating vibration noise. The first radial connecting part 51 located on the axial outer end face of the inner rotor core 12 and the outer rotor core 11 is in axial contact with the end faces on both sides of the second permanent magnet 3. The surface of the first radial connecting part 51 close to the rotor core 1 is in contact with the surface of the second permanent magnet 3 away from the rotor core 1. The first radial connecting part 51 plays the role of directly fixing the second permanent magnet 3 and indirectly fixing the first permanent magnet 2 in the axial direction, avoiding axial vibration of the second permanent magnet 3 placed in the axial direction of the rotor core 1 during operation, and also increasing the transmission capacity between the outer rotor core 11 and the inner rotor core 12.

[0052] In one embodiment, the second connecting portion 6 is formed before the first connecting portion 5.

[0053] In this embodiment, during the forming of the rotor structure, the outer rotor core 11, the second permanent magnet 3, and the first permanent magnet 2 can be fixedly connected using the second connecting part 6 to form a pre-formed structure. The structural stability of the pre-formed structure is used to fix the relative positions of the outer rotor core 11 and the inner rotor core 12. Then, the first connecting part 5 is filled to achieve a fixed connection between the inner rotor core 12, the shaft 8, and the pre-formed structure. Since the first connecting part 5 and the second connecting part 6 are not integrally formed, different materials and different forming processes can be selected. This ensures the strength of the connection structure between the rotor core 1 and the shaft 8 while reducing vibration transmission between the rotor core 1 and the shaft 8, resulting in good vibration reduction and noise reduction effects.

[0054] A second radial connection 61 is formed by filling the outer radial side and both axial ends of the rotor with a material with weak viscoelasticity. A second axial connection 62 is formed by injecting a plastic material with the same or weaker viscoelasticity as the material of the first connection part into the through hole 4 that passes through the second permanent magnet 3 and the rotor core 1 on the outer radial side of the rotor structure. Since the outer circumference of the entire rotor is wrapped with plastic to form the second radial connection 61, the second axial connection 62 is connected to the second radial connection 61, which can strengthen the connection between the rotor core 1 and the first permanent magnet 2 and the second permanent magnet 3, and ensure the stability of the entire rotor operation in the radial and axial directions.

[0055] The viscoelasticity of the material of the first connecting part 5 is limited to be no weaker than that of the material of the second connecting part 6. Since the main function of a material with strong viscoelasticity is to reduce vibration transmission, and the main transmission path of rotor structure vibration is to be transmitted radially to the shaft 8, the use of a material with good viscoelasticity only between the outer rotor core 11 and the shaft 8 can reduce the overall cost of the rotor.

[0056] In one embodiment, the outer rotor core 11 or the second connecting portion 6 has a groove on its inner circumferential side near the inner rotor core 12, and the inner rotor core 12 has a protrusion on its outer circumferential side near the outer rotor core 11. The protrusion is placed in the groove, forming a gap between them, and the first connecting portion 5 is provided in the gap. The protrusion of the inner rotor core 12 and the groove of the outer rotor core 11 or the second connecting portion 6 cooperate to enhance the mechanical connection between the inner and outer rotor cores, facilitate the transmission of force between them, enhance the overall mechanical strength of the rotor structure, and improve the reliability of motor operation.

[0057] In one embodiment, a rotor structure is characterized by comprising a rotor core 1, a first permanent magnet 2, a second permanent magnet 3, and a rotating shaft 8. The rotor core 1 includes an outer rotor core 11, with a gap between the outer rotor core 11 and the rotating shaft 8. The outer rotor core 11 has a mounting groove 13, in which the first permanent magnet 2 is mounted. Along the axial direction of the rotor core 1, the axial height of the first permanent magnet 2 is greater than the axial height of the outer rotor core 11. The second permanent magnet 3 is disposed at the axial end of the outer rotor core 11. The rotor core 11 has a groove 31. The portion of the first permanent magnet 2 extending axially from the outer rotor core 11 is inserted into the groove 31. The first permanent magnet 2 is magnetized along the tangential direction of the rotor core 1, and the second permanent magnet 3 is magnetized along the axial direction of the rotor core 1. Correspondingly, the second permanent magnet 3 and the rotor core 1 have through holes 4 extending axially along the rotor core 1. A first connecting portion 5 is provided within the through hole 4. The rotor structure also includes a second connecting portion 6. The viscoelasticity of the material of the first connecting portion 5 is greater than or equal to the viscoelasticity of the material of the second connecting portion 6. The first connecting portion 5 within the through hole 4 serves two purposes: firstly, it reduces vibration and noise; secondly, it enhances the mechanical interlocking force between the inner and outer rotor cores, thereby increasing the overall mechanical strength of the rotor structure. In one embodiment, the through hole 4 extends axially through both the second permanent magnet 3 and the outer rotor core 11.

[0058] In one embodiment, the rotor structure further includes an inner rotor core 12, with the through hole 4 extending axially through the second permanent magnet 3 and the inner rotor core 12. The first connecting portion 5 forms a cage-like structure by filling the portion within the through hole 4, which can enhance the mechanical connection strength between the inner rotor core 12 and the shaft 8.

[0059] In one embodiment, the outer rotor core 11 or the second connecting portion 6 has a groove on its inner circumferential side near the inner rotor core 12, and the inner rotor core 12 has a protrusion on its outer circumferential side near the outer rotor core 11. The protrusion is placed in the groove, forming a gap between them, and the first connecting portion 5 is provided in the gap. The protrusion of the inner rotor core 12 and the groove of the outer rotor core 11 or the second connecting portion 6 cooperate to enhance the mechanical connection between the inner and outer rotor cores, facilitate the transmission of force between them, enhance the overall mechanical strength of the rotor structure, and improve the reliability of motor operation.

[0060] In one embodiment, a gap is formed between the mounting groove 13 and the first permanent magnet 2, and a second connecting part 6 is provided within the gap. The second connecting part 6 forms a cage-like structure by filling the gap between the mounting groove 13 and the first permanent magnet 2, which can enhance the mechanical connection strength between the outer rotor core 11, the first permanent magnet 2, and the second permanent magnet 3.

[0061] In one embodiment, after the first permanent magnet 2 and the second permanent magnet 3 are magnetized, they are divided into multiple polarity regions. The polarities of adjacent polarity regions of the second permanent magnet 3 are opposite. The polarity of the two first permanent magnets 2 adjacent to a polarity region of the second permanent magnet 3 is the same as the polarity of the side of the polarity region closest to the rotor core 1. The magnetic flux of the first permanent magnet 2 and the second permanent magnet 3 can be used to increase the air gap magnetic flux density, thereby increasing the permanent magnet flux linkage of the motor and improving the torque density of the motor.

[0062] In one embodiment, the first permanent magnet 2 is made of sintered magnetic material, and the second permanent magnet 3 is made of plastic magnetic material.

[0063] The first permanent magnet 2 is made of sintered magnetic material. The characteristics of sintered magnetic material are strong magnetism, brittle material and difficult processing. The first permanent magnet 2 has a regular shape, which is suitable for using sintered magnetic material. The strong magnetism of sintered material can be used to relatively increase the permanent magnet flux. The second permanent magnet 3 requires the processing of grooves 31. The shape is complex and the processing is more difficult. Plastic magnetic material is suitable for use. Using integrated injection molding technology, through mold design, the second permanent magnet 3 can be produced quickly and in large quantities.

[0064] In one embodiment, the first radial connecting portion 51, the second radial connecting portion 61, the first axial connecting portion 52, and the second axial connecting portion 62 are all implemented using integrated injection molding technology.

[0065] According to an embodiment of this application, the motor includes a stator structure and a rotor structure, wherein the rotor structure is the rotor structure described above, and the stator structure is sleeved on the outer periphery of the rotor structure.

[0066] 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.

[0067] 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.

[0068] The above are merely some embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A rotor structure, characterized in that, The system includes a rotor core (1), a first permanent magnet (2), a second permanent magnet (3), and a shaft (8). The rotor core (1) comprises an outer rotor core (11) and an inner rotor core (12). The outer rotor core (11) is fitted around the outer periphery of the inner rotor core (12), forming a gap between them. The outer rotor core (11) has a mounting groove (13). The first permanent magnet (2) is installed in the mounting groove (13) along the axial direction of the rotor core (1). The axial height of the first permanent magnet (2) is greater than the axial height of the outer rotor core (11). The second permanent magnet (3) is disposed at the axial end of the outer rotor core (11). The second permanent magnet (3) has a groove (31). The portion of the outer rotor core (11) extending axially is inserted into the groove (31). The first permanent magnet (2) is magnetized along the tangential direction of the rotor core (1), and the second permanent magnet (3) is magnetized along the axial direction of the rotor core (1). The second permanent magnet (3) and the rotor core (1) are respectively provided with through holes (4) that extend axially along the rotor core (1). In one pole, the number of through holes (4) on the outer rotor core (11) is less than or equal to 1. A second connecting part (6) is provided in the through hole (4). The rotor structure also includes a first connecting part (5). The first connecting part (5) is provided in the gap. The viscoelasticity of the material of the first connecting part (5) is greater than or equal to the viscoelasticity of the material of the second connecting part (6).

2. The rotor structure according to claim 1, characterized in that, In one pole, a through hole (4) is provided on the outer rotor core (11), and a through hole (4) is provided on the inner rotor core (12). The second connecting part (6) is provided in both the through hole (4) of the outer rotor core (11) and the through hole (4) of the inner rotor core (12).

3. The rotor structure according to claim 1, characterized in that, In one pole, the outer rotor core (11) is provided with a through hole (4), and the inner rotor core (12) is not provided with the through hole (4); or, in one pole, the outer rotor core (11) is not provided with the through hole (4), and the inner rotor core (12) is provided with a through hole (4).

4. The rotor structure according to any one of claims 1 to 3, characterized in that, The outer rotor core (11) or the second connecting part (6) has a recess (14) on the inner circumferential side near the inner rotor core (12), and the inner rotor core (12) has a protrusion (15) on the outer circumferential side near the outer rotor core (11). The protrusion (15) is placed in the recess (14) and a gap is formed between them. The first connecting part (5) is provided in the gap.

5. The rotor structure according to claim 1, characterized in that, The first connecting part (5) and the second connecting part (6) are made of non-magnetic material.

6. The rotor structure according to claim 1, characterized in that, The first connecting part (5) includes a first radial connecting part (51) and a first axial connecting part (52), and the second connecting part (6) includes a second radial connecting part (61) and a second axial connecting part (62). The second connecting part (6) is located radially outside the first connecting part (5).

7. The rotor structure according to claim 6, characterized in that, The first radial connecting part (51) and the second radial connecting part (61) are located at the axial end of the rotor core (1), and the first axial connecting part (52) and the second axial connecting part (62) are embedded in the rotor core (1).

8. A rotor structure, characterized in that, The system includes a rotor core (1), a first permanent magnet (2), a second permanent magnet (3), and a rotating shaft (8). A first gap is formed between the rotor core (1) and the first permanent magnet (2). The rotor core (1) includes an outer rotor core (11) and an inner rotor core (12). The outer rotor core (11) is sleeved on the outer periphery of the inner rotor core (12). The outer rotor core (11) has a mounting groove (13). The first permanent magnet (2) is installed in the mounting groove (13). Along the axial direction of the rotor core (1), the axial height of the first permanent magnet (2) is greater than the axial height of the outer rotor core (11). The second permanent magnet (3) is disposed at the axial end of the outer rotor core (11). The second permanent magnet (3) has a groove (31). The portion of the body (2) extending axially from the outer rotor core (11) is inserted into the groove (31). The first permanent magnet (2) is magnetized along the tangential direction of the rotor core (1), and the second permanent magnet (3) is magnetized along the axial direction of the rotor core (1). The second permanent magnet (3) and the rotor core (1) are respectively provided with through holes (4) that penetrate along the axial direction of the rotor core (1). In one pole, the number of through holes (4) on the outer rotor core (11) is less than or equal to 1. A first connecting part (5) is provided in the through hole (4). The rotor structure also includes a second connecting part (6). The second connecting part (6) is provided in the first gap. The viscoelasticity of the material of the first connecting part (5) is greater than or equal to the viscoelasticity of the material of the second connecting part (6).

9. The rotor structure according to claim 8, characterized in that, The through hole (4) extends through the second permanent magnet (3) and the outer rotor core (11) along the axial direction of the rotor core (1).

10. The rotor structure according to claim 8, characterized in that, The rotor structure also includes an inner rotor core (12), and the through hole (4) passes through the second permanent magnet (3) and the inner rotor core (12) along the axial direction of the rotor core (1).

11. The rotor structure according to claim 10, characterized in that, The outer rotor core (11) or the second connecting part (6) has a recess (14) on the inner circumferential side near the inner rotor core (12), and the inner rotor core (12) has a protrusion (15) on the outer circumferential side near the outer rotor core (11). The protrusion (15) is placed in the recess (14) and a second gap is formed between them. The first connecting part (5) is provided in the second gap.

12. The rotor structure according to claim 8, characterized in that, The first gap is formed between the side wall of the mounting groove (13) and the first permanent magnet (2), and the second connecting part (6) is provided in the first gap.

13. The rotor structure according to claim 8, characterized in that, After being magnetized, the first permanent magnet (2) and the second permanent magnet (3) are divided into multiple polarity regions. The polarities of adjacent polarity regions of the second permanent magnet (3) are opposite. The polarities of the two first permanent magnets (2) adjacent to a polarity region of the second permanent magnet (3) are the same as the polarities of the side of the first permanent magnet (2) closest to the rotor core (1).

14. The rotor structure according to claim 8, characterized in that, The first permanent magnet (2) is made of sintered magnetic material, and the second permanent magnet (3) is made of plastic magnetic material.

15. 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 14, and the stator structure is sleeved on the outer periphery of the rotor structure.

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