Outer rotor, motor and drive system

Abstract

The application discloses an outer rotor, a motor and a driving system, and relates to the technical field of motors. The outer rotor comprises a ring-shaped main body and a plurality of permanent magnets. The ring-shaped main body is provided with at least one hollow area, the hollow area is provided as a mesh structure, the mesh structure comprises a plurality of concave meshes, at least one side wall of the concave mesh is provided as a concave side wall, and the concave side wall is recessed towards the inside of the concave mesh. The plurality of permanent magnets are arranged on the inner side of the ring-shaped main body. The technical scheme provided by the application can realize the collaborative optimization of the lightweight, efficient heat dissipation and mechanical properties of the outer rotor, effectively reduce the rotational inertia of the rotor, improve the thermal stability of the permanent magnet, and enhance the impact resistance of the rotor.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and in particular to an external rotor, a motor, and a drive system. Background Technology

[0002] The outer rotor of a permanent magnet brushless motor is the core rotating component. It typically supports the permanent magnets and forms the main magnetic circuit of the motor. Under the influence of the rotating magnetic field of the stator, it outputs torque, converting electrical energy into mechanical energy. This component is widely used in drones, robots, new energy vehicles, and aerospace, undertaking functions such as power output and dynamic speed regulation. Its performance directly affects the motor's power density, operating efficiency, and dynamic response capability.

[0003] In existing technologies, the outer rotor of a permanent magnet brushless motor typically adopts a homogeneous solid structure, with the main body machined from a single piece of magnetic steel in a cylindrical shape. Several permanent magnets are evenly bonded or embedded along the circumference of its inner wall, while the outer wall is directly exposed or serves as a rotating shell. One end is fixed to a shaft or output flange, and torque is output externally through the shaft. The entire rotor is supported on a support shaft by bearings and rotates around it. The backs of the permanent magnets are tightly attached to the rotor yoke, forming the main magnetic flux loop. During operation, the eddy current losses generated by the permanent magnets and the iron losses generated by the stator core are collected as heat inside the rotor, then transferred to the outer surface of the rotor via heat conduction, and gradually dissipated into the surrounding environment.

[0004] When the rotor with the above structure is running, the heat mainly comes from the eddy current loss of the permanent magnet and the iron loss generated by the stator core. Since the rotor body is a homogeneous solid, its internal thermal resistance is large and the heat dissipation path is single and long. It is difficult for heat to be transferred from the inside to the outside in a timely manner, and local hot spots are easily formed on the back of the permanent magnet and inside the rotor. When the temperature rise exceeds the working temperature range of high-performance permanent magnet materials such as neodymium iron boron, it may cause irreversible demagnetization, which in turn affects the power density release and long-term operational reliability of the motor. Summary of the Invention

[0005] The main objective of this invention is to propose an external rotor, motor, and drive system, which aims to achieve synergistic optimization of the external rotor's lightweight design, efficient heat dissipation, and mechanical performance. This effectively reduces the rotor's moment of inertia to improve dynamic response, enhances the thermal stability of the permanent magnet to improve operational reliability, and strengthens the rotor's impact resistance to adapt to complex working conditions.

[0006] To achieve the above objectives, the present invention provides an external rotor comprising: A ring-shaped body, wherein the ring-shaped body has at least one hollow area, the hollow area has a mesh structure, the mesh structure includes a plurality of concave mesh holes, at least one sidewall of each concave mesh hole is a concave sidewall, the concave sidewall being recessed into the interior of the concave mesh hole; and... Multiple permanent magnets are disposed on the inner side of the annular body.

[0007] In one embodiment, at least one of the concave sidewalls includes two inclined connecting segments that are inclined toward the interior of the concave mesh in a direction that brings them closer to each other.

[0008] In one embodiment, at least one of the concave mesh holes has two opposite sidewalls configured as the concave sidewalls.

[0009] In one embodiment, at least one of the concave mesh openings is configured as a hexagonal mesh opening.

[0010] In one embodiment, a connecting portion is provided at the lowest point of the concave sidewall, the connecting portion being used to connect with the sidewall of the hollowed-out area or to the lowest point adjacent to the concave sidewall.

[0011] In one embodiment, a plurality of the concave mesh openings are arranged in an array along the outer wall of the annular body.

[0012] In one embodiment, multiple hollow areas are provided, and the multiple hollow areas are distributed along the circumferential direction of the annular body. There is a gap between adjacent hollow areas to form a solid area on the annular body, and the permanent magnet corresponds to the position of the hollow area.

[0013] In one embodiment, the permanent magnet covers the corresponding hollow area.

[0014] The present invention also proposes an electric motor comprising the aforementioned external rotor.

[0015] The present invention also proposes a drive system including the aforementioned motor.

[0016] In the technical solution of this invention, at least one hollow area is set on the annular body, and the hollow area is set as a mesh structure containing multiple concave mesh holes. At least one sidewall of the concave mesh hole is set as a concave sidewall that is recessed inward, forming a negative Poisson's ratio topological configuration. This negative Poisson's ratio mesh structure utilizes its high specific stiffness and high specific strength characteristics with extremely low material ratio to significantly reduce rotor mass and rotational inertia, thereby improving the dynamic response capability of the motor. At the same time, the mesh structure forms a through-hole three-dimensional porous network inside the annular body, creating a huge inner surface area. When the outer rotor rotates, the porous structure acts like a built-in centrifugal impeller, actively driving the cooling medium to flow in a forced manner inside the network, achieving direct convective cooling of the rotor's interior. This fundamentally changes the passive heat dissipation mode of traditional rotors that rely solely on heat conduction, effectively suppressing the formation of local hot spots in the permanent magnet. In addition, by utilizing the unique deformation mechanism of negative Poisson's ratio, the material contracts and gathers towards the impact point when subjected to impact, giving the rotor excellent impact resistance and energy absorption characteristics, effectively dissipating vibration energy. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of an embodiment of the external rotor provided by the present invention; Figure 2 for Figure 1 A partial structural schematic diagram of an embodiment of the external rotor is provided; Figure 3 A schematic diagram of the structure of an embodiment of the motor provided by the present invention; Figure 4 for Figure 3 The provided exploded view of the motor.

[0019] Explanation of icon numbers: 100. Outer rotor; 1. Annular body; 11. Hollowed-out area; 111. Concave mesh; 1111. Concave sidewall; 1112. Connecting section; 1113. Connecting part; 12. Solid area; 2. Permanent magnet; 200. Motor; 201. Stator; 202. Support shaft; 203. Bearing; 204. Base; 205. Top cover.

[0020] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0023] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0024] Permanent magnet brushless motors, with their outstanding advantages of high power density, high efficiency, and compact structure, have become core power components in fields such as drones, robots, new energy vehicles, and aerospace. However, as application scenarios continue to increase the performance requirements of motors, traditional external rotor motor designs are facing multiple technical bottlenecks: traditional rotors adopt a homogeneous solid structure, resulting in concentrated rotor mass and high rotational inertia, which is not conducive to dynamic response; the rotor has high internal thermal resistance and a single heat dissipation path, making it easy for local hot spots to appear in the permanent magnets under high load operation, leading to irreversible demagnetization; at the same time, the homogeneous structure is difficult to achieve coordinated optimization of stiffness, strength, and toughness when facing multi-axis vibration and impact loads under complex working conditions.

[0025] To address the aforementioned technical problems, this invention provides an external rotor that achieves synergistic optimization of lightweighting, efficient heat dissipation, and mechanical performance by constructing a concave mesh structure with negative Poisson bit properties on a ring-shaped body.

[0026] Please see Figures 1 to 2 The outer rotor 100 includes an annular body 1 and multiple permanent magnets 2. The annular body 1 supports the permanent magnets 2 and forms part of the main magnetic circuit of the motor. The annular body 1 has at least one hollow area 11 with a mesh structure, including multiple concave mesh holes 111. At least one sidewall of each concave mesh hole 111 is a concave sidewall 1111, which is recessed into the interior of the mesh hole 111. The multiple permanent magnets 2 are disposed inside the annular body 1, and the material of the permanent magnets 2 can be neodymium iron boron, samarium cobalt, or ferrite, etc.

[0027] In the technical solution provided by this invention, by setting at least one hollow area 11 on the annular body 1 and setting the hollow area 11 as a mesh structure containing multiple concave mesh holes 111, the material usage of the annular body 1 is significantly reduced while maintaining structural integrity, thereby effectively reducing the overall mass and moment of inertia of the rotor. Since at least one sidewall of the concave mesh hole 111 is set as a concave sidewall 1111 that is recessed inward, when the outer rotor 100 is subjected to external compression or impact load, the concave sidewall 1111 further bends and contracts inward, causing the material to accumulate at the stress point, exhibiting a negative Poisson's ratio effect, that is, lateral contraction rather than expansion in the direction of compression, thereby effectively improving the local density and compression resistance of the structure, giving the outer rotor 100 excellent impact energy absorption characteristics and energy dissipation capability.

[0028] Furthermore, a three-dimensional porous network composed of multiple concave meshes 111 forms a continuous flow channel structure and a large inner surface area within the annular body 1. When the outer rotor 100 rotates around its axis, the porous network acts like a built-in centrifugal impeller, actively driving the surrounding cooling medium (such as air) to flow within the porous network under centrifugal force, achieving direct convective cooling of the rotor's interior (especially the back area of ​​the permanent magnet 2). This active heat dissipation mechanism fundamentally changes the passive heat dissipation mode of traditional solid rotors that relies solely on heat conduction, significantly reducing the internal thermal resistance of the rotor, effectively suppressing the formation of local hot spots, thereby ensuring the thermal stability of the permanent magnet 2 and reducing the risk of irreversible demagnetization.

[0029] Furthermore, the specific structure of the concave mesh 111 will be described in detail below.

[0030] Please see Figure 2 The concave sidewall 1111 is recessed into the concave mesh 111, meaning it is not straight but recessed towards the center of the mesh 111. In one embodiment, at least one concave sidewall 1111 includes two inclined connecting segments 1112, which are inclined towards the interior of the mesh 111 in a direction of mutual approach. That is, the two connecting segments 1112 gradually incline towards the interior of the mesh 111, giving the concave sidewall 1111 an overall "V" or "<" shaped concave profile. Specifically, the two connecting segments 1112 may converge at the center of the concave sidewall 1111 to form a sharp angle or a rounded transition.

[0031] For example, the connecting segment 1112 can be a straight segment. The connecting segment 1112 of two straight segments intersects at the middle of the concave sidewall 1111 to form a pointed concave profile, so that the concave mesh 111 presents a concave hexagonal configuration. This configuration is a typical negative Poisson's ratio unit cell structure, which has good mechanical predictability and design controllability.

[0032] By setting two inclined connecting sections 1112 to form a concave sidewall 1111, the concave mesh 111 exhibits a distinct negative Poisson's ratio mechanical response: when the outer rotor 100 is subjected to a compressive load in the radial direction, the two connecting sections 1112 further bend and contract inward, causing the concave mesh 111 to contract synchronously in the compressive direction. The material concentrates at the impact point, increasing the local density and effectively enhancing the structure's resistance to impact compression. This deformation mechanism enables the outer rotor 100 to effectively dissipate impact energy and reduce the risk of structural damage under complex working conditions such as high-speed rotation and vibration impact.

[0033] Furthermore, in one embodiment, at least one concave mesh 111 has two opposing sidewalls configured as concave sidewalls 1111. That is, the concave mesh 111 has an inwardly concave shape on its two opposing sidewalls (e.g., the upper and lower sidewalls along the circumferential direction of the annular body 1). In this structure, each concave mesh 111 has a negative Poisson's ratio mechanical property in both opposing directions. When subjected to compressive or impact loads from the axial direction of the outer rotor, both opposing concave sidewalls 1111 contract inward, making the structure's impact resistance and energy absorption effect more significant. At the same time, the symmetry of the concave mesh 111 also helps to ensure dynamic balance performance during rotation.

[0034] Furthermore, in one embodiment, at least one of the concave mesh openings 111 is configured as a hexagonal mesh opening. That is, based on the fact that both opposite sidewalls of the concave mesh opening 111 are configured as concave sidewalls 1111, the concave mesh opening 111 as a whole presents a concave hexagonal configuration.

[0035] Specifically, the hexagonal mesh includes six sides, four of which are each formed by one of the four connecting segments 1112, i.e., there are two concave sidewalls 1111. Thus, the concave mesh 111 presents a cross-sectional profile similar to an hourglass, further enhancing the negative Poisson's ratio effect.

[0036] Furthermore, in one embodiment, a connecting portion 1113 is connected to the lowest point of the concave sidewall 1111. The connecting portion 1113 is used to connect to the sidewall of the hollow area 11 or to the lowest point of the adjacent concave sidewall 1111. That is, the connecting portion 1113 is provided at the deepest recessed point of the concave sidewall 1111 (i.e., the intersection of the two connecting segments 1112 or a position near the intersection), and the connecting portion 1113 connects the lowest point of the concave sidewall 1111 to the surrounding structure.

[0037] For example, the connecting portion 1113 can be a short connecting rib, which extends radially or axially from the lowest point of the concave sidewall 1111 to the outer sidewall of the hollow area 11 or the solid part of the annular body 1, serving a dual function of mechanical support and heat conduction. For example, the connecting portion 1113 can also be a node connecting block, that is, a small solid connecting block is provided at the lowest point of the concave sidewall 1111 to connect the lowest points of adjacent concave sidewalls 1111 to each other, enhancing the integrity of the mesh structure. For example, the connecting portion 1113 can also be an arc transition section, which smoothly connects the lowest point of the concave sidewall 1111 to the adjacent structure in an arc transition manner, reducing stress concentration and improving fatigue strength.

[0038] By setting the connecting part 1113, on the one hand, the overall structural rigidity and strength of the mesh structure are enhanced, and local instability caused by the lack of effective connection between each concave mesh 111 is avoided; on the other hand, the connecting part 1113 provides a solid path for the conduction of heat in the mesh structure, which is conducive to the rapid transfer of heat from the back of the permanent magnet 2 to the heat dissipation surface of the porous network through the connecting part 1113, thereby further improving the heat dissipation efficiency.

[0039] Specifically, the lowest point of the concave sidewall 1111 is the deepest point of the concave sidewall 1111 along the concave direction, which is also the connection point where the two connecting segments 1112 approach and converge. The connecting portion 1113 extends from this connection point to connect with the sidewall of the hollow area 11 or with the lowest point of the adjacent concave sidewall 1111. When the connecting portion 1113 connects with the lowest point of the adjacent concave sidewall 1111, a new concave mesh 111 is formed by the joint enclosure of two adjacent concave mesh holes 111 along the axial direction of the annular body 1 and two adjacent concave mesh holes 111 along the circumferential direction through their respective connecting segments 1112 and the two connecting portions 1113. That is, the newly formed concave mesh 111 is formed by a connecting segment 1112 contributed by each of the four adjacent concave meshes 111 and two connecting portions 1113 connecting the two adjacent lowest points, which together constitute its outline boundary. In this way, the adjacent concave meshes 111 are no longer simply separated by walls, but new concave meshes 111 are derived in the intersection area of ​​the four concave meshes 111 through the bridging of the connecting portions 1113, so that the entire mesh structure forms a denser and more interconnected multi-level porous network. It can be understood that in this embodiment, each concave mesh 111 can be composed of two connecting portions 1113 and two concave sidewalls 1111.

[0040] This multi-level network further increases the heat dissipation surface area inside the hollow area 11, enriches the flow path of the cooling medium, and makes the load transfer path between adjacent unit cells more diversified, thereby further improving the mechanical redundancy and damage tolerance of the overall structure. In other embodiments, it can also be formed by an interlaced array of multiple concave meshes 111, in which case the wall thickness at the intersection of adjacent concave meshes 111 is twice the wall thickness of a single concave mesh 111.

[0041] Furthermore, in one embodiment, a plurality of concave mesh openings 111 are arranged in an array along the outer wall of the annular body 1. That is, the concave mesh openings 111 are arranged in a regular row and column pattern on the outer wall of the annular body 1, forming a periodic array structure. The array arrangement can be extended in both the circumferential and axial directions of the annular body 1.

[0042] For example, the concave mesh 111 can be arranged in one or more rows along the circumference of the annular body 1, and in one or more columns along the axial direction, forming a rectangular array arrangement. For example, the concave mesh 111 can also be arranged in a staggered array, where adjacent rows (along the axial direction) of the concave mesh 111 are staggered by half a unit cell in the circumferential direction, forming a honeycomb-like arrangement. This arrangement can achieve a more uniform distribution of mechanical properties in the circumferential direction. For example, the concave mesh 111 can also be arranged in a gradient array, where the size, concavity angle, or wall thickness of the concave mesh 111 varies from one end of the annular body 1 to the other to adapt to the heat load distribution and mechanical requirements at different positions along the axial direction.

[0043] By arranging multiple concave mesh holes 111 in an array, a periodic and regular negative Poisson's ratio porous network is formed within the hollow area 11. This periodic arrangement ensures the uniformity and isotropy of the mechanical properties of the annular body 1 in both the circumferential and axial directions, avoiding localized weak areas or stress concentrations caused by irregular arrangements. Simultaneously, the regularly arranged porous network provides orderly flow channels for the cooling medium, facilitating the uniform distribution and effective flow of the heat dissipation airflow.

[0044] Furthermore, in one embodiment, multiple hollow areas 11 are provided, and the multiple hollow areas 11 are distributed along the circumferential direction of the annular body 1. There is a gap between adjacent hollow areas 11 to form a solid area 12 on the annular body 1. The permanent magnet 2 corresponds to the position of the hollow area 11.

[0045] That is, along the circumferential direction of the annular body 1, the hollowed-out areas 11 do not cover the entire circumferential surface of the annular body 1, but are distributed at intervals. Between two adjacent hollowed-out areas 11, the annular body 1 retains solid material, forming solid regions 12. Solid regions 12 are high-density material areas, which constitute part of the rotor's main magnetic flux path, ensuring that the main magnetic flux can form a complete magnetic circuit through solid regions 12, providing sufficient cross-sectional area for the main magnetic circuit to prevent magnetic saturation, and at the same time providing structural rigidity support and torque transmission function for the annular body 1. The installation position of the permanent magnet 2 on the inner side of the annular body 1 corresponds to the circumferential position of the hollowed-out areas 11, that is, when viewed along the radial direction of the annular body 1's circumferential wall, the permanent magnet 2 is located inside the hollowed-out areas 11.

[0046] The above layout has multiple advantages. First, since the hollow area 11 is located on the back of the permanent magnet 2, the cooling medium can directly conduct convective heat transfer on the back of the permanent magnet 2, greatly shortening the heat dissipation path and making the heat dissipation effect more efficient and direct. The heat generated by the permanent magnet 2 can be quickly transferred to the wall of the porous network through an extremely short conduction path and directly carried away by the forced flow of the cooling medium, thereby suppressing the formation of local hot spots on the back of the permanent magnet 2 to the greatest extent. Second, the solid area 12 is located between adjacent permanent magnets 2, which corresponds precisely to the transition area between adjacent magnetic poles. The high-density solid material of the solid area 12 provides a continuous and sufficient yoke cross-sectional area for the main magnetic flux loop at this location, ensuring the integrity of the main magnetic circuit and effectively avoiding local magnetic saturation caused by magnetic circuit bottlenecks. Third, the solid area 12 serves as a structural load-bearing skeleton along the circumferential direction, mechanically connecting each hollow area 11 into a whole, ensuring the structural integrity and reliability of the annular body 1 under high-speed rotation and vibration impact.

[0047] For example, the solid region 12 can be configured as a strip-shaped solid region extending along the axial direction of the annular body 1, and its circumferential width is determined according to the magnetic circuit design requirements and structural strength requirements.

[0048] Furthermore, in one embodiment, the permanent magnet 2 covers the corresponding hollow area. That is, the installation area of ​​each permanent magnet 2 on the inner side of the annular body 1 roughly corresponds to or completely covers the distribution area of ​​the hollow area 11 corresponding to it in the radial direction on the annular body 1. In other words, when viewed from the radial direction of the annular body 1, the projection range of each permanent magnet 2 covers the projection range of its corresponding hollow area 11.

[0049] By covering the hollowed-out area 11 with the permanent magnet 2, a close one-to-one correspondence is formed between the permanent magnet 2 and the porous network in the hollowed-out area 11 in the radial direction. This structural layout further enhances the direct heat dissipation effect of the hollowed-out area 11 on the permanent magnet 2. Specifically, the permanent magnet 2 is closely attached to the inner side of the annular body 1, while its back (i.e., the outer side) is the porous network in the hollowed-out area 11, which provides a direct heat dissipation channel for the permanent magnet 2. When the outer rotor 100 rotates, the cooling medium flows through the porous network under the action of centrifugal force, directly convectively cooling the back of the permanent magnet 2. Since the permanent magnet 2 completely covers the hollowed-out area 11, the entire back area of ​​the permanent magnet 2 can be cooled and covered by the porous network, avoiding the situation where some areas cannot be effectively cooled, and the heat dissipation uniformity and efficiency are significantly improved.

[0050] Meanwhile, the structural layout of the permanent magnet 2 covering the hollow area 11 also has a sealing function. The permanent magnet 2 forms a certain degree of shielding on the opening of the hollow area 11 on its inner side, which helps guide the cooling medium to flow along the channel direction of the porous network, reduces the leakage of cooling medium from the inside, and improves the efficiency of forced convection. In addition, the coverage of the permanent magnet 2 also provides a certain degree of physical protection for the hollow area 11, preventing external foreign objects from entering the motor through the porous network.

[0051] The working mechanism of the negative Poisson's ratio porous network composed of concave mesh 111 will be further explained below.

[0052] The design of the concave mesh 111 gives the mesh structure a negative Poisson's ratio mechanical property. Unlike ordinary materials or ordinary mesh structures that expand perpendicular to the direction of force under compression, the negative Poisson's ratio structure contracts synchronously perpendicular to the direction of force under compressive load. When an external compressive load is applied to the annular body 1, the two connecting segments 1112 of the concave sidewall 1111 are forced to bend further into the concave mesh 111, thereby causing the entire unit cell to contract laterally, prompting the surrounding structure to converge towards the loaded area, thus significantly increasing the local apparent density of that area.

[0053] This structure offers the following advantages: First, when subjected to impact loads, the negative Poisson's ratio porous network gradually absorbs and dissipates impact energy through large deformation, enabling the outer rotor 100 to exhibit impact toughness far superior to that of traditional homogeneous structures, effectively protecting the permanent magnet 2 from impact damage. Second, under the radial centrifugal force generated by high-speed rotation, the lateral contraction characteristics of the negative Poisson's ratio structure help maintain the radial compactness of the structure, avoiding structural loosening or increased air gaps due to centrifugal expansion.

[0054] Regarding the overall heat dissipation operation mode of the outer rotor 100, when the motor 200 containing the outer rotor 100 is running, the outer rotor 100 rotates at high speed around the support shaft 202. During this process, the porous network composed of multiple concave mesh holes 111 in the hollow area 11 on the annular body 1 rotates accordingly. Due to the interconnected three-dimensional channel structure of the porous network, under the action of centrifugal force, the cooling medium (e.g., air) near the inner side of the rotor is forced to flow radially outward, while the cooling medium on the outer side is replenished from the openings of the porous network, forming a continuous forced convection circulation.

[0055] This active forced convection cooling mechanism has the following significant characteristics: First, the cooling medium flows directly through the interior of the porous network, directly contacting the walls of the concave mesh 111 for heat exchange. The heat transfer distance is extremely short, and the heat transfer efficiency is far higher than that of traditional solid rotors through natural convection and radiation cooling of the rotor's outer surface. Second, the concave contour of the concave mesh 111 increases the heat dissipation surface area per unit volume. Compared to circular or rectangular meshes of the same volume, the concave mesh 111 provides a larger heat exchange area. Third, the "V"-shaped contour of the concave sidewall 1111 generates local eddies and turbulence effects when the fluid passes through, further enhancing the convective heat transfer coefficient and improving the heat dissipation efficiency. In addition, the multiple hollow areas 11 are evenly distributed circumferentially, ensuring uniform heat dissipation capacity in the circumferential direction and avoiding localized overheating.

[0056] By adjusting the geometric parameters of the concave mesh 111, the performance of the outer rotor 100 can be controlled for different application scenarios. The geometric parameters include, but are not limited to, the concave angle of the concave sidewall 1111, the arm length of the connecting section 1112, the wall thickness of the concave mesh 111, and the row and column spacing of the array arrangement.

[0057] For example, the concave angle of the concave sidewall 1111, the arm length of the connecting section 1112, and the wall thickness of the concave mesh 111 can all be adjusted according to actual conditions to achieve a balance between lightweight, heat dissipation efficiency, and mechanical properties.

[0058] Please see Figure 3 and Figure 4 The present invention also provides an electric motor 200, which includes an outer rotor 100 from the above embodiments. The specific structure of the outer rotor 100 is as described in the above embodiments. Since the present motor 200 adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0059] Specifically, the motor 200 also includes a stator 201, a support shaft 202, a bearing 203, a base 204, and a top cover 205. The stator 201 is located inside the outer rotor 100, and a preset air gap is maintained between the stator 201 and the outer rotor 100. The stator 201 is made of laminated silicon steel sheets and has embedded stator windings, generating a rotating magnetic field when energized. The support shaft 202 is fixed to the base 204, used to mount the stator 201 and as the inner ring support for the bearing 203, ensuring coaxiality and uniformity of the air gap between the stator 201 and the outer rotor 100. The bearing 203 supports the outer rotor 100, allowing it to rotate smoothly around the support shaft 202, while reducing frictional losses and bearing radial and axial loads. The base 204 is the fixed base of the motor 200, used to mount the entire machine on external equipment, and simultaneously supports the support shaft 202 and the stator 201, ensuring structural stability. The top cover 205 encloses the top of the motor 200, protecting the internal components from external contamination, and together with the base 204, supports the bearing 203, ensuring the axial positioning of the outer rotor 100.

[0060] Motor 200 is a permanent magnet brushless motor. The permanent magnet 2 provides a constant excitation magnetic field, which interacts with the rotating magnetic field generated by the stator 201, driving the outer rotor 100 to rotate and output torque. During operation, the negative Poisson's ratio porous network within the hollowed-out area 11 of the outer rotor 100 actively dissipates heat. The cooling medium flows within the porous network under centrifugal force, directly convectively cooling the permanent magnet 2. For example, motor 200 can be applied to the field of unmanned aerial vehicles (UAVs) as a power motor, its lightweight outer rotor 100 effectively reducing the UAV's takeoff weight and improving endurance and maneuverability. For example, motor 200 can also be applied to the field of industrial robots as a joint drive motor, its low moment of inertia enabling faster dynamic response. For example, motor 200 can also be applied to the field of new energy vehicles as a drive motor or auxiliary motor, its efficient heat dissipation ensuring continuous and reliable operation under high load conditions.

[0061] The present invention also provides a drive system including the aforementioned motor 200. The drive system further includes a drive controller for driving the motor 200 and a load device transmittedly connected to the motor 200. By employing a motor 200 with an outer rotor 100 having a negative Poisson's ratio mesh structure, the drive system achieves higher power density, better thermal management capabilities, and stronger environmental adaptability at the overall level. Exemplarily, the drive system can be a drone power system. Exemplarily, the drive system can also be a robot servo drive system. Exemplarily, the drive system can also be an electric vehicle drive assembly.

[0062] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An external rotor, characterized in that, include: A ring-shaped body, wherein the ring-shaped body has at least one hollow area, the hollow area has a mesh structure, the mesh structure includes a plurality of concave mesh holes, at least one sidewall of each concave mesh hole is a concave sidewall, the concave sidewall being recessed into the interior of the concave mesh hole; and... Multiple permanent magnets are disposed on the inner side of the annular body.

2. The external rotor as described in claim 1, characterized in that, At least one of the concave sidewalls includes two inclined connecting segments, which are inclined toward the interior of the concave mesh in a direction that brings them closer to each other.

3. The external rotor as described in claim 1, characterized in that, At least one of the concave meshes has two opposite sidewalls configured as concave sidewalls.

4. The external rotor as described in claim 3, characterized in that, At least one of the concave meshes is configured as hexagonal meshes.

5. The external rotor as described in claim 1, characterized in that, The lowest point of the concave sidewall is connected to a connecting part, which is used to connect to the sidewall of the hollow area or to the lowest point adjacent to the concave sidewall.

6. The outer rotor as described in any one of claims 1 to 5, characterized in that, The plurality of the concave mesh holes are arranged in an array along the outer wall of the annular body.

7. The external rotor as described in claim 1, characterized in that, The hollowed-out areas are provided in multiple ways, and the multiple hollowed-out areas are distributed along the circumferential direction of the annular body. There are gaps between adjacent hollowed-out areas to form solid areas on the annular body. The permanent magnet is positioned corresponding to the hollowed-out areas.

8. The external rotor as described in claim 7, characterized in that, The permanent magnet covers the corresponding hollow area.

9. An electric motor, characterized in that, Includes an outer rotor as described in any one of claims 1 to 8.

10. A drive system, characterized in that: Includes the motor as described in claim 9.

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