Outer rotor and permanent magnet motor

Abstract

This application discloses an external rotor and a permanent magnet motor, including a rotor core and permanent magnets. The rotor core comprises multiple core blocks, one end of which has a protruding dovetail-shaped protrusion, and the other end has a recessed dovetail-shaped groove. Multiple core blocks are sequentially connected end-to-end through the engagement of the dovetail-shaped protrusion and the dovetail-shaped groove to form the rotor body. Multiple limiting parts are connected to the inner surface of the core blocks. The limiting parts have a U-shaped cross-section and engage with the fan-shaped core blocks to form permanent magnet mounting slots. The multiple limiting parts are arranged circumferentially along the rotor body, and the permanent magnet mounting slots extend axially along the rotor body. Each permanent magnet mounting slot has a permanent magnet insertion port, and a permanent magnet is embedded within it. A pressing structure is provided within the permanent magnet mounting slot, applying pressure to the permanent magnet to limit its movement. This solution improves assembly accuracy and mechanical stability, and reduces magnetic field distortion and torque pulsation caused by loosening.

Description

Technical Field

[0001] This application relates to the field of electric motor technology, specifically to an external rotor and permanent magnet motor. Background Technology

[0002] External rotor permanent magnet motors have been widely used in new energy, industrial automation and other fields in recent years due to their advantages such as compact structure, high torque density, and direct load driving capability. An external rotor permanent magnet motor typically includes an external rotor, a stator, and windings on the stator. The external rotor includes a rotor core and several permanent magnets mounted on the rotor core. Traditional external rotors usually adopt an integral structure, with silicon steel sheets stacked into a ring-shaped core and permanent magnets bonded to the inner side. However, as applications become larger and more precise, traditional external rotor designs are unable to meet the demands due to the following drawbacks: 1. When the diameter of the integral iron core reaches a certain limit (e.g., exceeding 1 meter), special large-scale stamping equipment is required to process silicon steel sheets, which is costly and difficult to perform on-site maintenance. When a part is damaged, the entire core needs to be replaced, significantly increasing maintenance costs. To solve this problem, segmented external rotors have emerged, which consist of multiple rotor segments connected by bolts or welding between adjacent segments. However, these segments are prone to breakage due to stress concentration and severe wear during high-speed rotation, leading to safety accidents. 2. Reliable fixation of permanent magnets is the core challenge of external rotor design. The common solution in existing technologies is adhesive fixation, such as using epoxy resin to bond permanent magnets to the iron core. However, the adhesive layer is prone to aging and peeling off under high temperature or vibration conditions. To solve this problem, iron cores with slots have emerged, which improve the problem of adhesive layer aging and peeling by inserting permanent magnets into the iron core. However, the stability of permanent magnets in the slots is poor under high-speed conditions, and micro-displacement is likely to occur. Utility Model Content

[0003] This application provides an external rotor to improve or solve, to some extent, the technical problems of existing permanent magnet motors, such as high manufacturing and maintenance costs, easy breakage, and poor reliability of permanent magnet fixing.

[0004] The technical solution adopted in this application is as follows:

[0005] An external rotor includes a rotor core and a permanent magnet. The rotor core comprises multiple fan-shaped core blocks. One end of each core block has a protruding dovetail-shaped protrusion, and the other end has a recessed dovetail-shaped groove. The multiple core blocks are sequentially connected end-to-end through the engagement of the dovetail-shaped protrusion and the dovetail-shaped groove to form a closed ring rotor body. Multiple limiting parts are connected to the inner surface of each core block. The limiting parts have a U-shaped cross-section and engage with the fan-shaped core blocks to form permanent magnet mounting slots. The multiple limiting parts are arranged circumferentially along the rotor body. The permanent magnet mounting slots extend axially along the rotor body. At least one end of each permanent magnet mounting slot along the axial direction has a permanent magnet insertion port. Each permanent magnet mounting slot contains a permanent magnet. A pressing structure is provided within each permanent magnet mounting slot. The pressing structure applies pressure to the permanent magnet to limit its movement.

[0006] In this technical solution, the dovetail-shaped protrusions and grooves of the fan-shaped iron core block cooperate to form a closed-loop rotor body, improving the rotor assembly accuracy and mechanical stability, while reducing assembly difficulties caused by machining errors. The U-shaped cross-section of the limiting part and the permanent magnet mounting groove formed by the iron core block extend axially, and the permanent magnet is conveniently installed through the permanent magnet insertion port at the axial end, eliminating the need for traditional adhesive fixation and significantly improving the centrifugal force stability of the permanent magnet. The pressure-retaining structure directly applies pressure to the permanent magnet, ensuring that the permanent magnet will not shift during high-speed rotation or temperature changes, significantly improving fixation reliability and reducing magnetic field distortion and torque pulsation caused by loosening.

[0007] The pressing structure includes an elastic part disposed on at least one side of the groove wall of the permanent magnet mounting groove. An elastic deformation gap is formed between the elastic part and the groove wall. When the permanent magnet is inserted into the permanent magnet mounting groove, the elastic part abuts against the permanent magnet and generates elastic deformation, so as to limit the permanent magnet through elastic restoring force.

[0008] In this technical solution, the elastic deformation gap design between the elastic part and the groove wall allows the elastic part to generate a continuous restoring force through deformation when the permanent magnet is inserted, thereby achieving elastic pressure limiting of the permanent magnet. This structure can absorb the small displacement of the permanent magnet caused by thermal expansion or vibration, and can also compensate for the dimensional tolerance of the permanent magnet, reduce the assembly accuracy requirements, improve the production yield, and compared with the rigid fixing method, the elastic limiting can effectively avoid the risk of breakage of the permanent magnet due to stress concentration.

[0009] The elastic part includes at least one elastic tongue. The inner wall of the limiting part is provided with a relief groove adapted to the elastic tongue. One end of the elastic tongue is a connecting end connected to the limiting part, and the other end is a free end that tilts inward toward the inside of the permanent magnet mounting groove. The free end extends obliquely toward one end opening of the permanent magnet mounting groove. When the permanent magnet is inserted into the permanent magnet mounting groove, the elastic tongue is squeezed into the relief groove by the permanent magnet.

[0010] In this technical solution, the design of the elastic tongue and the clearance groove ensures that when the permanent magnet is inserted into the permanent magnet mounting slot, the elastic tongue is squeezed into the clearance groove, and the rebound force generated by its warping deformation evenly presses the surface of the permanent magnet. The inclined extension structure of the free end of the elastic tongue guides the smooth insertion of the permanent magnet, reducing assembly resistance and preventing fatigue fracture caused by repeated stress. The spatial design of the clearance groove ensures that the elastic tongue does not interfere with other components during deformation, extending its service life. It also allows the outer contour of the permanent magnet to fit the inner contour of the permanent magnet mounting slot as closely as possible, ensuring that the permanent magnet fully fills the mounting slot and improving the reliability of the permanent magnet's positioning.

[0011] The sidewalls of two adjacent limiting parts abut against each other.

[0012] In this technical solution, the sidewalls of adjacent limiting parts abut against each other to form a continuous support structure, enhancing the overall rigidity of the permanent magnet mounting slot and preventing deformation or cracking of the limiting parts due to centrifugal force when the rotor rotates at high speed. The sidewall abutment design of adjacent limiting parts can also reduce magnetic field leakage, improve the magnetic energy utilization rate of the permanent magnet, and provide a stable support foundation for the elastic part.

[0013] The limiting part is integrally connected to the iron core block.

[0014] In this technical solution, the limiting part is integrally connected to the core block (e.g., through stamping or casting), eliminating stress concentration points that may occur with traditional welding or bolted connections and improving the overall structural reliability of the outer rotor. The integral molding process simplifies the production process, reduces assembly steps, lowers manufacturing costs, and simultaneously ensures the consistency of mechanical properties between the limiting part and the core block.

[0015] Both the dovetail protrusion and the dovetail groove extend along the axial direction of the rotor body to both sides of the iron core block. One end of the dovetail protrusion is provided with an arc-shaped guide surface, which is used to guide the dovetail protrusion into the dovetail groove during assembly.

[0016] In this technical solution, the axial extension design of the dovetail protrusions and dovetail grooves ensures smooth axial fit and reliable circumferential contact between adjacent core blocks, improving the balance of the outer rotor. The arc-shaped guide surface simplifies the assembly process of the rotor body, enabling automatic alignment of the core blocks during assembly, reducing manual adjustment time and improving production efficiency. The axial extension structure also enhances the shear resistance of the dovetail connection, adapting to high-speed rotation conditions.

[0017] The edges of the dovetail-shaped protrusion adopt a rounded transition structure, and the edges of the dovetail-shaped groove adopt a rounded transition structure.

[0018] In this technical solution, the edges of the dovetail protrusions and dovetail grooves adopt a rounded transition structure to eliminate stress concentration at sharp corners and prevent cracks from forming in the core block due to excessive local stress during assembly or operation. The rounded transition also reduces frictional resistance, decreases wear on the core block connection surfaces, and extends the service life of the outer rotor.

[0019] The outer surface of the dovetail-shaped protrusion is provided with a wear-resistant coating, which is a titanium nitride coating or a diamond-like carbon coating; or, the inner surface of the dovetail-shaped groove is provided with a wear-resistant coating, which is a titanium nitride coating or a diamond-like carbon coating.

[0020] In this technical solution, the outer surface of the dovetail-shaped protrusion or the inner surface of the dovetail-shaped groove is coated with a wear-resistant coating of titanium nitride or diamond-like carbon, which significantly improves the wear resistance and corrosion resistance of the contact surface, reduces the frictional loss of the iron core block during long-term operation, and ensures the stability of the outer rotor connection. The low frictional characteristics of the coating surface can reduce local stress concentration, making the load distribution of the dovetail connection surface more uniform and avoiding fatigue cracks caused by stress concentration.

[0021] A ceramic coating is provided on the contact surface of two adjacent iron core blocks.

[0022] In this technical solution, the ceramic coating on the contact surface of adjacent core blocks has high hardness and insulation properties, which can reduce contact surface wear, block eddy current paths between core blocks, reduce rotor iron losses, and improve motor efficiency. The ceramic coating can also withstand high-temperature environments, avoiding coating failure due to temperature rise, making it particularly suitable for high power density motor applications.

[0023] This application also provides a permanent magnet motor, including a stator, a stator winding, and an outer rotor as described above. The outer rotor and the stator are arranged coaxially, and the outer rotor is located outside the stator. The stator winding includes coils wound on the stator. Since the permanent magnet motor includes the outer rotor as described above, the effects of the outer rotor are all included in the permanent magnet motor and will not be elaborated here. Attached Figure Description

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

[0025] Figure 1 The assembly drawing of the external rotor provided in the embodiment of this application;

[0026] Figure 2 This is a schematic diagram of the structure of the iron core block and the limiting part provided in the embodiments of this application. Figure 1 ;

[0027] Figure 3 for Figure 2 Enlarged view of point A in the middle;

[0028] Figure 4 for Figure 2 Enlarged view at point B in the middle;

[0029] Figure 5 This is a schematic diagram of the structure of the iron core block and the limiting part provided in the embodiments of this application. Figure 2 ;

[0030] Figure 6 for Figure 5 Enlarged view at point C;

[0031] Figure 7 This is a schematic diagram of the rotor body provided in an embodiment of this application;

[0032] Figure 8 This is a schematic diagram of the structure of the limiting part and the elastic tongue provided in the embodiments of this application;

[0033] Figure 9 This is a partial cross-sectional view of the outer rotor provided in an embodiment of this application;

[0034] Figure 10 This is a schematic diagram of the permanent magnet motor provided in the embodiments of this application.

[0035] List of components and reference numerals:

[0036] 1 Rotor core, 11 Core block, 111 Dovetail protrusion, 1111 Arc-shaped guide surface, 112 Dovetail groove, 12 Limiting part, 121 Clearance groove, 13 Permanent magnet mounting groove, 14 Elastic tongue.

[0037] 2 permanent magnets;

[0038] 3 stators;

[0039] 4 coils. Detailed Implementation

[0040] To more clearly illustrate the overall concept of this application, a detailed explanation is provided below with reference to the accompanying drawings.

[0041] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below.

[0042] Furthermore, it should be understood in the description of this application that the terms "upper," "lower," "top," "bottom," "inner," "outer," "axial," "radial," "circumferential," "lateral," and "longitudinal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0043] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0044] In this application, unless otherwise expressly specified and limited, the "above" or "below" of the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples.

[0045] In the embodiments of this application, an external rotor is provided. For ease of explanation and understanding, the following content is based on the illustrated product structure. Of course, those skilled in the art will understand that the above structure is merely a specific example and illustrative illustration, and does not constitute a specific limitation on the technical solution provided in this application. It should be noted that...

[0046] Reference Figures 1 to 9 As shown, the external rotor provided in this application includes a rotor core 1 and a permanent magnet 2. The rotor core 1 includes multiple fan-shaped core blocks 11. One end of each core block 11 has a protruding dovetail-shaped protrusion 111, and the other end has a recessed dovetail-shaped groove 112. The multiple core blocks 11 are connected end to end to form a closed ring rotor body through the cooperation of the dovetail-shaped protrusion 111 and the dovetail-shaped groove 112. The inner surface of the core block 11 is connected to multiple limiting parts 12 to limit the movement of the core blocks. The cross-section of part 12 is U-shaped. The limiting part 12 and the fan-shaped iron core block 11 cooperate to form a permanent magnet mounting groove 13. Multiple limiting parts 12 are arranged circumferentially along the rotor body. The permanent magnet mounting groove 13 extends axially along the rotor body. At least one end of the permanent magnet mounting groove 13 along the axial direction is provided with a permanent magnet insertion port. A permanent magnet 2 is embedded in each permanent magnet mounting groove 13. A pressing structure is provided in the permanent magnet mounting groove 13. The pressing structure applies pressure to the permanent magnet 2 to limit the permanent magnet 2.

[0047] like Figure 2 The diagram shows the structure of a single iron core block 11, as follows: Figure 7 The diagram shows a rotor body structure formed by four iron core blocks 11 connected end-to-end through the cooperation of dovetail protrusions 111 and dovetail grooves 112, creating a closed loop. It should be noted that the inclusion of four iron core blocks 11 in the rotor body does not limit this application; other suitable numbers of iron core blocks 11 can be used. Adjacent iron core blocks 11 can have the same arc length or different arc lengths. In a preferred embodiment, both ends of the permanent magnet mounting groove 13 can be provided with permanent magnet insertion ports, meaning the permanent magnet mounting groove 13 is open at both ends. In other embodiments, one end of the permanent magnet mounting groove 13 can be provided with a permanent magnet insertion port, while the other end is closed. In this application, the dovetail protrusions 111 and dovetail grooves 112 of the fan-shaped iron core blocks 11 form a closed loop rotor body, improving rotor assembly accuracy and mechanical stability while reducing assembly difficulties caused by processing errors. The U-shaped cross-section of the limiting part 12 and the permanent magnet mounting groove 13 formed by the iron core block 11 extend axially, and the permanent magnet 2 is conveniently installed through the permanent magnet insertion port at the axial end, without relying on traditional adhesive fixation, which significantly improves the centrifugal force stability of the permanent magnet 2. The pressure-retaining structure directly applies pressure to the permanent magnet 2, ensuring that the permanent magnet 2 will not shift when rotating at high speed or when the temperature changes, which significantly improves the fixation reliability and reduces magnetic field distortion and torque pulsation caused by loosening.

[0048] This application does not limit the pressing structure. As a preferred embodiment of this application, the pressing structure includes an elastic portion provided on at least one side of the permanent magnet mounting groove 13. An elastic deformation gap is formed between the elastic portion and the groove wall. When the permanent magnet 2 is inserted into the permanent magnet mounting groove 13, the elastic portion abuts against the permanent magnet 2 and generates elastic deformation, thereby limiting the permanent magnet 2 through elastic restoring force. The design of the elastic deformation gap between the elastic portion and the groove wall allows the elastic portion to generate a continuous restoring force through deformation when the permanent magnet 2 is inserted, thereby achieving elastic pressing and limiting of the permanent magnet 2. This structure can absorb the small displacement of the permanent magnet 2 caused by thermal expansion or vibration, and can also compensate for the dimensional tolerance of the permanent magnet 2, reduce the assembly accuracy requirements, improve the production yield, and compared with the rigid fixing method, the elastic limiting can effectively avoid the risk of breakage of the permanent magnet 2 due to stress concentration.

[0049] In a preferred embodiment, such as Figure 8 As shown, the elastic part includes at least one elastic tongue 14, and the inner wall of the limiting part 12 is provided with a relief groove 121 adapted to the elastic tongue 14. One end of the elastic tongue 14 is a connecting end connected to the limiting part 12, and the other end is a free end that tilts towards the inside of the permanent magnet mounting groove 13. The free end extends obliquely toward the opening at one end of the permanent magnet mounting groove 13. When the permanent magnet 2 is inserted into the permanent magnet mounting groove 13, the elastic tongue 14 is squeezed into the relief groove 121 by the permanent magnet 2. Figure 8 The illustration shows an embodiment where the limiting portion 12 is provided with an elastic tongue 14. The elastic tongue 14 can be connected to the limiting portion 12 by welding or other suitable means. In other embodiments, multiple elastic tongues 14 can also be provided on one limiting portion 12, with the upward and extending directions of the multiple elastic tongues 14 being consistent. Figure 8 The image shows the state where the elastic tongue 14 pops out of the self-avoiding groove 121, as shown. Figure 9The diagram shows the state where the elastic tongue 14 deforms and enters the clearance groove 121 under the pressure of the permanent magnet 2. At this time, the tendency of the elastic tongue 14 to recover its deformation applies pressure to the permanent magnet 2 against the inner wall of the permanent magnet mounting groove 13. Since the free end of the elastic tongue 14 is inclined towards the permanent magnet insertion port at one end of the permanent magnet mounting groove 13, the permanent magnet 2 needs to be inserted through the permanent magnet insertion port at the other end of the permanent magnet mounting groove 13 to avoid interference with the elastic tongue 14. In embodiments where the permanent magnet insertion port is provided at one end of the permanent magnet mounting groove and the other end is closed, the free end of the elastic tongue needs to be inclined towards the closed end of the permanent magnet mounting groove. In this technical solution, the cooperative design of the elastic tongue 14 and the clearance groove 121 ensures that when the permanent magnet 2 is inserted into the permanent magnet mounting groove 13, the elastic tongue 14 is squeezed into the clearance groove 121, and the rebound force generated by its warping deformation evenly presses the surface of the permanent magnet 2. The inclined extension structure of the free end of the elastic tongue 14 guides the smooth insertion of the permanent magnet 2, reducing assembly resistance and preventing fatigue fracture caused by repeated stress. The spatial design of the clearance groove 121 ensures that the elastic tongue 14 does not interfere with other components during deformation, extending its service life. It also allows the outer contour of the permanent magnet 2 to fit the inner contour of the permanent magnet mounting groove 13 as closely as possible, ensuring that the permanent magnet 2 fully fills the permanent magnet mounting groove 13 and improving the reliability of the permanent magnet 2's positioning. More preferably, the elastic tongue 14 can be made of stainless steel, titanium alloy, or other materials to reduce the impact on the main magnetic circuit of the permanent magnet motor. In other embodiments, the elastic part can also adopt other suitable structures, such as a spring structure.

[0050] As a preferred embodiment of this application, such as Figure 2 and Figure 7 As shown, the sidewalls of adjacent limiting parts 12 abut against each other, forming a continuous support structure, which enhances the overall rigidity of the permanent magnet mounting groove 13 and prevents the limiting parts 12 from deforming or cracking due to centrifugal force when the rotor rotates at high speed. The sidewall abutment design of adjacent limiting parts 12 can also reduce magnetic field leakage, improve the magnetic energy utilization rate of the permanent magnet 2, and provide a stable support foundation for the elastic part. In other embodiments, the limiting parts 12 can also be arranged in a circumferentially spaced manner along the rotor body as needed.

[0051] In a preferred embodiment, the limiting part 12 is integrally connected to the core block 11, such as through stamping or casting processes. This eliminates stress concentration points that may occur with traditional welding or bolting connections, improving the overall structural reliability of the outer rotor. The integral molding process simplifies the production process, reduces assembly steps, lowers manufacturing costs, and simultaneously ensures the consistency of mechanical properties between the limiting part 12 and the core block 11.

[0052] As a preferred embodiment of this application, such as Figure 2 , Figure 5 and Figure 6As shown, both the dovetail protrusion 111 and the dovetail groove 112 extend axially along the rotor body to both sides of the core block 11. One end of the dovetail protrusion 111 is provided with an arc-shaped guide surface 1111, which guides the dovetail protrusion 111 into the dovetail groove 112 during assembly. In this technical solution, the axial extension design of the dovetail protrusion 111 and the dovetail groove 112 ensures smooth axial fit and reliable circumferential contact between adjacent core blocks 11, improving the balance of the outer rotor. The arc-shaped guide surface 1111 simplifies the assembly process of the rotor body, enabling automatic alignment of the core blocks 11 during assembly, reducing manual adjustment time and improving production efficiency. The axial extension structure of the dovetail protrusion 111 and the dovetail groove 112 also enhances the shear resistance of the dovetail connection, adapting to high-speed rotation conditions. During assembly, simply align the arc-shaped guide surface 1111 with one end opening of the dovetail groove 112, and then move the two adjacent iron core blocks 11 relative to each other along the axial direction so that the arc-shaped guide surface 1111 guides the dovetail protrusion 111 to slide into the dovetail groove 112 until the axial end faces of the two adjacent iron core blocks 11 are aligned.

[0053] Furthermore, such as Figure 3 and Figure 4 As shown, the edges of the dovetail-shaped protrusion 111 and the dovetail-shaped groove 112 adopt a rounded transition structure. Specifically, the edges of the dovetail-shaped protrusion 111 away from the end face of the core block 11 adopt a rounded transition structure, and the position where the edges of the dovetail-shaped protrusion 111 meet the end face of the core block 11 also adopts a rounded transition structure. Similarly, the inner edges of the dovetail-shaped groove 112 adopt a rounded transition structure, and the position where the edges of the dovetail-shaped groove 112 meet the end face of the core block 11 also adopts a rounded transition structure. In this technical solution, the edges of the dovetail-shaped protrusion 111 and the dovetail-shaped groove 112 adopt a rounded transition structure to eliminate stress concentration at sharp corners and prevent the core block 11 from cracking due to excessive local stress during assembly or operation. The rounded transition can also reduce frictional resistance, reduce wear on the connecting surface of the core block 11, and extend the service life of the outer rotor.

[0054] In a preferred embodiment, the outer surface of the dovetail protrusion 111 is provided with a wear-resistant coating, the material of which is titanium nitride or diamond-like carbon. In another preferred embodiment, the inner surface of the dovetail groove 112 is provided with a wear-resistant coating, the material of which is titanium nitride or diamond-like carbon. Those skilled in the art will understand that the dovetail protrusion 111 and the dovetail groove 112 need to slide together during assembly. Without a coating, direct contact between the metals will cause scratches or burrs, leading to increased assembly resistance or even jamming. When the motor rotates at high speed, the outer rotor core 1 is subjected to centrifugal force, and the dovetail connection surface may experience fretting wear due to minor vibrations. Therefore, to improve this problem, this solution coats the outer surface of the dovetail protrusion 111 or the inner surface of the dovetail groove 112 with a wear-resistant coating of titanium nitride or diamond-like carbon, which significantly improves the wear resistance and corrosion resistance of the contact surface, reduces the frictional loss of the core block 11 during long-term operation, and ensures the stability of the outer rotor connection. Moreover, the low friction characteristics of the coating surface can reduce local stress concentration, making the load distribution of the dovetail connection surface more uniform and avoiding fatigue cracks caused by stress concentration.

[0055] A ceramic coating is provided on the contact surface of two adjacent core blocks 11. It should be noted that the contact surface referred to here is the area around the dovetail protrusion 111 and the area around the dovetail groove 112. Those skilled in the art will understand that when the outer rotor rotates at high speed, this location may experience slight relative slippage due to vibration or centrifugal force, leading to fatigue and spalling of the contact surface material. Over long-term operation, this results in decreased rotor body splicing accuracy, uneven air gap, and deterioration of electromagnetic performance. In this technical solution, the ceramic coating on the contact surface of adjacent core blocks 11 has high hardness and insulation properties, which can reduce contact surface wear and block eddy current paths between core blocks 11, reducing rotor iron loss and improving motor efficiency. The ceramic coating can also withstand high-temperature environments, preventing coating failure due to temperature rise, making it particularly suitable for high-power-density motor applications.

[0056] This application also provides a permanent magnet motor, such as Figure 10 As shown, the motor includes a stator 3, stator windings, and an outer rotor as described above. The outer rotor and stator 3 are coaxially arranged, with the outer rotor located outside the stator 3. The stator windings include coils 4 wound around the stator. Since the permanent magnet motor includes the outer rotor as described above, all the effects of the outer rotor are inherent to permanent magnet motors. In particular, the modular design and limiting function of the pressure-resistant structure of the outer rotor significantly reduce torque ripple and electromagnetic noise, making it suitable for applications with stringent space and performance requirements, such as electric vehicles and industrial fans. The synergistic design of the ceramic coating and the wear-resistant coating further extends the motor's service life and reduces overall maintenance costs.

[0057] For any parts not mentioned in this application, existing technologies may be used or referenced.

[0058] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0059] The above description is merely an embodiment of this application and is not intended to limit the scope of 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 scope of the claims of this application.

Claims

1. An external rotor, characterized in that, It includes a rotor core and a permanent magnet. The rotor core includes multiple fan-shaped core blocks. One end of each core block has a protruding dovetail protrusion and the other end has a recessed dovetail groove. Multiple core blocks are connected end to end to form a closed ring rotor body through the cooperation of the dovetail protrusion and the dovetail groove. The inner surface of the iron core block is connected to multiple limiting parts. The cross-section of the limiting parts is U-shaped. The limiting parts cooperate with the fan-shaped iron core block to form a permanent magnet mounting groove. The multiple limiting parts are arranged circumferentially along the rotor body. The permanent magnet mounting groove extends axially along the rotor body. At least one end of the permanent magnet mounting groove along the axial direction is provided with a permanent magnet insertion port. Each permanent magnet mounting groove is embedded with a permanent magnet. The permanent magnet mounting groove is provided with a pressing structure. The pressing structure applies pressure to the permanent magnet to limit the permanent magnet.

2. The external rotor according to claim 1, characterized in that, The pressing structure includes an elastic part disposed on at least one side of the groove wall of the permanent magnet mounting groove. An elastic deformation gap is formed between the elastic part and the groove wall. When the permanent magnet is inserted into the permanent magnet mounting groove, the elastic part abuts against the permanent magnet and generates elastic deformation, so as to limit the permanent magnet through elastic restoring force.

3. The external rotor according to claim 2, characterized in that, The elastic part includes at least one elastic tongue. The inner wall of the limiting part is provided with a relief groove adapted to the elastic tongue. One end of the elastic tongue is a connecting end connected to the limiting part, and the other end is a free end that tilts inward toward the inside of the permanent magnet mounting groove. The free end extends obliquely toward one end opening of the permanent magnet mounting groove. When the permanent magnet is inserted into the permanent magnet mounting groove, the elastic tongue is squeezed into the relief groove by the permanent magnet.

4. The external rotor according to claim 1, characterized in that, The sidewalls of two adjacent limiting parts abut against each other.

5. The external rotor according to claim 4, characterized in that, The limiting part is integrally connected to the iron core block.

6. The external rotor according to claim 1, characterized in that, Both the dovetail protrusion and the dovetail groove extend along the axial direction of the rotor body to both sides of the iron core block. One end of the dovetail protrusion is provided with an arc-shaped guide surface, which is used to guide the dovetail protrusion into the dovetail groove during assembly.

7. The external rotor according to claim 6, characterized in that, The edges of the dovetail-shaped protrusion adopt a rounded transition structure, and the edges of the dovetail-shaped groove adopt a rounded transition structure.

8. The external rotor according to claim 7, characterized in that, The outer surface of the dovetail-shaped protrusion is provided with a wear-resistant coating, which is a titanium nitride coating or a diamond-like carbon coating. Alternatively, the inner surface of the dovetail groove is provided with a wear-resistant coating, which is a titanium nitride coating or a diamond-like carbon coating.

9. The external rotor according to claim 1, characterized in that, A ceramic coating is provided on the contact surface of two adjacent iron core blocks.

10. A permanent magnet motor, comprising a stator and stator windings, characterized in that, It also includes an outer rotor as described in any one of claims 1 to 9, wherein the outer rotor and the stator are arranged coaxially and the outer rotor is located outside the stator, and the stator winding includes coils wound on the stator.

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