A reliable connection of outer rotor motor and unmanned aerial vehicle

Abstract

The application relates to a reliable connection outer rotor motor and a drone, the outer rotor motor forms a bidirectional locking mechanism through the abutting of the lower blocking seat and the end of the fastener, so that the fastener is in a prestressed state of being axially compressed, the loosening risk under high-frequency vibration is effectively overcome, and the reliability of the connection is improved; meanwhile, the torsion-resistant structure independently bears the torque transmission, the axial positioning and the circumferential limiting are borne by a rigid frame formed by the upper and lower shaft sleeves and the fastener, stress concentration is avoided, the torsion-resistant performance is improved, and the high-speed operation condition is adapted; therefore, the drone adopting the outer rotor motor has the characteristics of stable and reliable connection and stable operation.

Description

Technical Field

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

[0002] External rotor motors, with their compact structure, large moment of inertia, and excellent heat dissipation, are widely used in drone power systems, power tools, and home appliances. However, the reliability of the connection between the rotor housing and the central shaft, a core transmission component, directly determines the motor's stability and lifespan under high-speed operation. Currently, the industry commonly uses a one-piece stamped metal housing, connecting it to the housing via stamping and riveting with an interference fit or by adding upper and lower bushings. Specifically, while the traditional stamping and riveting process is simple, it requires high ductility of the housing material, and the riveting points are often located in weak areas of the housing. Under long-term high-speed operation or frequent start-stop impact loads, a single riveting point is prone to stress concentration, leading to plastic deformation or fatigue cracking at the riveted area, which can cause the main shaft to loosen or even fall off. Relying solely on an interference fit between the shaft and the housing, under conditions of motor temperature changes or high torque output, the mating surfaces are prone to fretting wear, resulting in increased clearance, ineffective torque transmission, and difficulty in maintaining axial positioning accuracy over the long term.

[0003] Therefore, this invention addresses the aforementioned problems. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a reliable external rotor motor and drone. This external rotor motor uses a bidirectional locking mechanism formed by the lower stop seat abutting against the end of the fastener, placing the fastener in a pre-stressed state under axial compression. This effectively overcomes the risk of loosening under high-frequency vibration and improves connection reliability. Simultaneously, the anti-torsion structure independently bears the torque transmission, while axial positioning and circumferential limiting are provided by a rigid frame composed of upper and lower bushings and fasteners, avoiding stress concentration, improving anti-torsion performance, and adapting to high-speed operating conditions. Therefore, drones using this external rotor motor have the characteristics of stable and reliable connection and stable operation.

[0005] To solve the above-mentioned technical problems, the present invention provides a reliable external rotor motor, including a central shaft 1, a stator assembly 2, and a rotor assembly 3. The central shaft 1 is rotatably connected to the stator assembly 2, and the rotor assembly 3 is fixedly connected to the central shaft 1. A bushing assembly 4 is provided between the rotor assembly 3 and the central shaft 1. The bushing assembly 4 is sleeved on the central shaft 1, and an anti-torsion structure 10 for transmitting torque is provided between the inner side wall of the bushing assembly 4 and the outer side wall of the central shaft 1. The bushing assembly 4 includes an upper bushing 41 and a lower bushing 42 located on the upper and lower sides of the rotor housing 31 of the rotor assembly 3, respectively. Both the upper bushing 41 and the lower bushing 42 are integrally formed aluminum parts. The upper bushing 41 has an upper connecting hole sleeve 411 that can be sleeved on the central shaft 1 and a vertically fixed connection to the upper connecting hole sleeve 411 and the rotor housing. The upper blocking seat 412 is engaged with the upper surface of the rotor housing 31. A fastener 43 is provided between the upper blocking seat 412 and the rotor housing 31 to lock and fix the upper blocking seat 412 relative to the rotor housing 31. The lower bushing 42 has a lower connecting hole sleeve 421 that can be sleeved on the central shaft 1 and a lower blocking seat 422 that is vertically fixed to the lower connecting hole sleeve 421 and engages with the lower surface of the rotor housing 31 and the corresponding end of the fastener 43. A blocking limiting member 11 is provided on the central shaft 1 and located below the lower bushing 42. The blocking limiting member 11 is configured to engage with the lower port of the lower connecting hole sleeve 421 in the assembled state so that the lower blocking seat 422 and the upper blocking seat 412 abut against each other axially to clamp and fix the upper and lower surfaces of the rotor housing 31, thereby limiting the circumferential rotation and axial displacement of the central shaft 1 relative to the rotor housing 31.

[0006] As described above, in a reliable external rotor motor, the fastener 43 is a rivet, the shank of which is interference-fitted with the upper blocking seat 412 and the rotor housing 31, and the lower end face of the rivet is in abutting fit with the lower blocking seat 422; the fastener 43 is a fastening bolt, and both the upper blocking seat 412 and the rotor housing 31 are provided with corresponding connecting through holes 44. The fastening bolt passes through the connecting through hole 44 on the rotor housing 31 and is threadedly connected to the connecting through hole 44 on the upper blocking seat 412.

[0007] In the above-described reliable external rotor motor, when the fastener 43 is a rivet, the upper end of the rivet protrudes from the upper surface of the upper stop seat 412 to form an anti-loosening fit for engaging with an external load.

[0008] As described above, in a reliable external rotor motor, both the upper blocking seat 412 and the rotor housing 31 are provided with connecting through holes 44 for fasteners 43 to pass through simultaneously.

[0009] As described above, in a reliable external rotor motor, the upper blocking seat 412 and / or the lower blocking seat 422 are provided with a plurality of anti-rotation protrusions arranged circumferentially on the mating surface with the rotor housing 31. The rotor housing 31 is provided with anti-rotation grooves adapted to the anti-rotation protrusions at corresponding positions. The anti-rotation protrusions are embedded in the anti-rotation grooves to form a secondary anti-torsional fit between the bushing assembly and the rotor housing.

[0010] As described above, in a reliable external rotor motor, the anti-torsion structure 10 is located between the outer wall of the central shaft 1 and the inner wall of the upper bushing 41. The anti-torsion structure 10 includes a straight-knurled or mesh-knurled structure on the outer wall of the central shaft 1, and the knurled structure forms an interference fit with the inner wall of the upper connecting hole sleeve 411; and / or, the anti-torsion structure 10 is a concave-convex anti-rotation fit structure, and the anti-torsion structure 10 includes anti-rotation teeth that extend axially on the outer wall of the central shaft 1 and anti-rotation grooves that are correspondingly provided on the inner wall of the upper connecting hole sleeve 411, and the anti-rotation teeth and anti-rotation grooves are mutually anti-rotation fits.

[0011] As described above, in a reliable external rotor motor, the lower blocking seat 422 is provided with a lower receiving through hole 423 communicating with the lower connecting hole sleeve 421, and the lower end of the upper connecting hole sleeve 411 is inserted into the lower receiving through hole 423; the lower end of the upper connecting hole sleeve 411 is provided with a guide inclined wall 413 for guiding the upper shaft sleeve 41 to be quickly inserted into the lower shaft sleeve 42.

[0012] As described above, in a reliable external rotor motor, a reinforcing shim 12 is sleeved on the central shaft 1 between the blocking and limiting member 11 and the lower shaft sleeve 42. The lower surface of the reinforcing shim 12 is in blocking engagement with the blocking and limiting member 11, and the upper surface of the reinforcing shim 12 is in blocking engagement with the lower end face of the lower shaft sleeve 42.

[0013] As described above, in a reliable external rotor motor, the blocking and limiting member 11 is a shoulder integrally formed with the central shaft 1. The parallelism between the upper surface of the shoulder and the lower end face of the lower connecting hole sleeve 421 is ≤0.02mm, so as to ensure that the axial clamping force is evenly distributed along the circumferential direction and to prevent the rotor housing 31 from tilting due to uneven force.

[0014] The present invention also provides a drone, including a drone body, wherein the drone body employs an external rotor motor with reliable connection as described above.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] 1. The external transmitter motor uses a bidirectional locking mechanism formed by the lower stop seat abutting against the end of the fastener, which puts the fastener in a pre-stressed state under axial compression, effectively overcoming the risk of loosening under high-frequency vibration and improving the reliability of the connection. At the same time, the anti-torsion structure independently bears the torque transmission, while the axial positioning and circumferential limiting are borne by the rigid frame composed of the upper and lower bushings and fasteners, avoiding stress concentration, improving anti-torsion performance, and adapting to high-speed operating conditions. Therefore, UAVs using this external transmitter motor have the characteristics of stable and reliable connection and stable operation.

[0017] 2. This invention uses the hard limiting cooperation between the blocking and limiting component and the lower bushing to drive the upper and lower bushings to form an annular clamping surface around the center, firmly clamping the rotor housing. Compared with the point contact of traditional riveting, this surface contact clamping force area is larger and more uniform, greatly enhancing the overall tensile strength. In addition, this gapless rigid closed-loop structure effectively suppresses fretting wear and abnormal noise, improves the dynamic balance performance of the rotor assembly, and ensures the stability and service life of the external rotor motor at high speed.

[0018] 3. In order to improve the stability, reliability and structural rigidity of the connection between the upper stop seat and the rotor housing, the fastener is a rivet, the shank of the rivet is interference-fitted with the upper stop seat and the rotor housing respectively, and the lower end face of the rivet is in abutting fit with the lower stop seat.

[0019] 4. To prevent slippage under high load or rapid acceleration conditions and to ensure a stable and reliable connection between the central shaft and the bushing assembly, the anti-torsion structure includes a straight-knurled or mesh-knurled structure on the outer wall of the central shaft. The knurled structure forms an interference fit with the inner wall of the upper connecting hole sleeve.

[0020] 5. To make the structure more compact and minimize the volume, the lower blocking seat is provided with a lower receiving through hole that communicates with the lower connecting hole sleeve, and the lower end of the upper connecting hole sleeve is inserted into the lower receiving through hole.

[0021] 6. To improve structural strength and reliability, a reinforcing shim is fitted on the central shaft between the blocking and limiting component and the lower shaft sleeve. Attached Figure Description

[0022] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, wherein:

[0023] Figure 1 This is one of the perspective views of the present invention.

[0024] Figure 2 This is a second perspective view of the present invention.

[0025] Figure 3 This is one of the cross-sectional views of the present invention.

[0026] Figure 4 This is a second cross-sectional view of the present invention.

[0027] Figure 5 This is one of the exploded views of the present invention.

[0028] Figure 6 This is the second exploded view of the present invention. Detailed Implementation

[0029] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0030] like Figure 1-6 As shown, the present invention discloses a reliable external rotor motor, comprising a central shaft 1, a stator assembly 2, and a rotor assembly 3. The central shaft 1 is rotatably connected to the stator assembly 2, and the rotor assembly 3 is fixedly connected to the central shaft 1. A bushing assembly 4 is provided between the rotor assembly 3 and the central shaft 1, and the bushing assembly 4 is sleeved on the central shaft 1. An anti-torsion structure 10 for transmitting torque is provided between the inner side wall of the bushing assembly 4 and the outer side wall of the central shaft 1. The bushing assembly 4 includes an upper bushing 41 and a lower bushing 42 located on the upper and lower sides of the rotor housing 31 of the rotor assembly 3, respectively. Both the upper bushing 41 and the lower bushing 42 are integrally formed aluminum parts. The upper bushing 41 has an upper connecting hole sleeve 411 that can be sleeved on the central shaft 1 and a bushing that is perpendicularly fixedly connected to the upper connecting hole sleeve 411 and to the upper surface of the rotor housing 31. The upper blocking seat 412 is in contact with the rotor housing 31, and a fastener 43 is provided between the upper blocking seat 412 and the rotor housing 31 to lock and fix the upper blocking seat 412 relative to the rotor housing 31. The lower bushing 42 has a lower connecting hole sleeve 421 that can be sleeved on the central shaft 1 and a lower blocking seat 422 that is vertically fixed to the lower connecting hole sleeve 421 and in contact with the lower surface of the rotor housing 31 and the corresponding end of the fastener 43. A blocking limiting member 11 is provided on the central shaft 1 and located below the lower bushing 42. The blocking limiting member 11 is configured to engage with the lower port of the lower connecting hole sleeve 421 in the assembled state so that the lower blocking seat 422 and the upper blocking seat 412 abut against each other axially and clamp and fix the upper and lower surfaces of the rotor housing 31 to limit the circumferential rotation and axial displacement of the central shaft 1 relative to the rotor housing 31. The external transmitter motor uses a bidirectional locking mechanism formed by the lower stop seat abutting against the end of the fastener, which puts the fastener in a prestressed state of axial compression, effectively overcoming the risk of loosening under high-frequency vibration and improving the reliability of the connection. At the same time, the anti-torsion structure independently bears the torque transmission, while axial positioning and circumferential limiting are borne by the rigid frame composed of the upper and lower bushings and fasteners, avoiding stress concentration, improving anti-torsion performance, and adapting to high-speed operating conditions. Therefore, UAVs using this external transmitter motor have the characteristics of stable and reliable connection and stable operation.

[0031] This invention uses a blocking and limiting component to rigidly limit the lower bushing, driving the upper and lower bushings to form an annular clamping surface around the center, firmly clamping the rotor housing. Compared to the point contact of traditional riveting, this surface contact clamping force area is larger and more uniform, significantly enhancing the overall tensile strength. In addition, this gapless rigid closed-loop structure effectively suppresses fretting wear and abnormal noise, improves the dynamic balance performance of the rotor assembly, and ensures the stability and service life of the external rotor motor during high-speed operation.

[0032] During assembly, fasteners are first inserted into the connecting through holes of the rotor housing. Then, the upper bushing is connected to the rotor housing, so that the connecting through hole of the upper stop seat is fitted onto the fastener, and the upper connecting hole sleeve is inserted into the through hole 311 of the housing. At this time, the upper stop seat and the rotor housing are fixed by fastener riveting. After that, the reinforcing shim and the lower bushing are sequentially fitted onto the central shaft from top to bottom. Then, the upper end of the central shaft is passed through the upper connecting hole sleeve until the knurled structure of the central shaft and the upper connecting hole sleeve are pressed together, and the lower stop seat and the lower surface of the rotor housing 31 and the corresponding end of the fastener 43 are blocked and limited. Therefore, the present invention, through the multiple locking fits of rivet limiting, upper bushing interference clamping, and lower bushing reverse fixing, enables the rotor assembly to have excellent anti-loosening, anti-torsion and anti-tensile properties, effectively improving the overall assembly structure stability of the rotor assembly.

[0033] like Figure 3-6 As shown, to further ensure a very high degree of coaxiality between the rotor housing and the upper bushing, the upper end of the rotor housing 31 has a housing through hole 311 for fitting onto the upper connecting hole sleeve 411. In some embodiments, the inner wall of the housing through hole 311 and the outer wall of the upper connecting hole sleeve 411 are interference-fitted, ensuring a reliable connection.

[0034] like Figure 3-6 As shown, the stator assembly 2 includes, but is not limited to, a stator mounting base 21 and a stator winding 22 disposed on the stator mounting base 21, and the central shaft 1 is rotatably connected to the stator mounting base 21 via a bearing 23.

[0035] like Figure 3-6 As shown, in order to improve the stability, reliability and structural rigidity of the connection between the upper blocking seat and the rotor housing, the fastener 43 is a rivet. The rivet shank is interference-fitted with the upper blocking seat 412 and the rotor housing 31 respectively, and the lower end face of the rivet is in abutting fit with the lower blocking seat 422.

[0036] In other embodiments, the fastener 43 is a fastening bolt, and the upper blocking seat 412 and the rotor housing 31 are respectively provided with connecting through holes 44. The fastening bolt passes through the connecting through hole 44 on the rotor housing 31 and is threadedly connected to the connecting through hole 44 on the upper blocking seat 412.

[0037] like Figure 1 ,3 As shown in Figure 4, when the fastener 43 is a rivet, the upper end of the rivet protrudes from the upper surface of the upper stop seat 412 to form an anti-loosening mating part for engaging with an external load. This anti-loosening mating part is embedded in the corresponding hole of the blade mounting seat, forming a double guarantee of anti-torsion of the central shaft and anti-rotation of the rivet head. When the external rotor motor rotates at high speed, the torsional torque of the external load is directly borne by the rivet head, rather than being entirely transmitted to the mating interface between the central shaft and the bushing, effectively preventing relative rotation between the load and the shaft end and eliminating slippage. The anti-loosening mating part can be a flat, slotted, or polygonal end, etc.

[0038] like Figure 3-6 As shown, to ensure the coaxiality of the central shaft and the rotor housing, both the upper stop seat 412 and the rotor housing 31 are provided with connecting through holes 44 for fasteners 43 to pass through simultaneously. During press fitting, the rivet passes through the connecting through holes 44 on both the upper stop seat 412 and the rotor housing 31, serving a positioning function and ensuring that the upper bushing and the rotor housing are precisely aligned before assembly, effectively preventing circumferential deflection or radial offset of the upper bushing relative to the rotor housing. Simultaneously, the through holes allow the fasteners to form an interference or transition fit with the inner walls of both holes, creating a rigid surface-hole constraint relationship. When the rotor housing is subjected to torque, the load can be directly transferred between the upper stop seat and the rotor housing through the fasteners, avoiding the load being concentrated only at the contact point between the rivet head and the rotor housing surface. This increases the torsional stiffness of the connection and prevents fretting rotation of the rotor housing relative to the upper bushing under high loads.

[0039] The upper stop seat 412 and / or the lower stop seat 422 have multiple anti-rotation protrusions arranged circumferentially on their mating surfaces with the rotor housing 31. Corresponding positions on the rotor housing 31 have anti-rotation grooves adapted to the anti-rotation protrusions. The anti-rotation protrusions are embedded in the anti-rotation grooves to form a secondary anti-torsional fit between the bushing assembly and the rotor housing (not shown in the figure). Embedding the anti-rotation protrusions in the anti-rotation grooves automatically completes the circumferential positioning of the upper bushing, lower bushing, and rotor housing during the assembly stage, ensuring circumferential alignment of the connecting hole sleeve under the upper bushing and the accommodating through hole under the lower bushing. This avoids bushing cracking caused by press-fit misalignment and improves assembly yield.

[0040] To prevent slippage under high load or rapid acceleration conditions and ensure a stable and reliable connection between the central shaft and the bushing assembly, the anti-torsion structure 10 is located between the outer wall of the central shaft 1 and the inner wall of the upper bushing 41. The anti-torsion structure 10 includes a straight-knurled or mesh-knurled structure on the outer wall of the central shaft 1, and the knurled structure forms an interference fit with the inner wall of the upper connecting hole sleeve 411. In some embodiments, for a more secure connection, the knurled structure forms an interference fit with the inner wall of the lower connecting hole sleeve 421.

[0041] To prevent slippage under high load or rapid acceleration conditions and ensure a stable and reliable connection between the central shaft and the bushing assembly, the anti-torsion structure 10 is a concave-convex anti-rotation fit structure. The anti-torsion structure 10 includes anti-rotation teeth extending axially on the outer wall of the central shaft 1 and corresponding anti-rotation grooves on the inner wall of the upper connecting sleeve 411. The anti-rotation teeth and anti-rotation grooves engage with each other to prevent rotation, but this is not shown in the figure. In some embodiments, for a more secure connection, the concave-convex anti-rotation fit structure is also provided between the central shaft 1 and the inner wall of the lower connecting sleeve 421.

[0042] like Figure 3-5 As shown, in order to make the structure more compact and minimize the volume, the lower blocking seat 422 is provided with a lower receiving through hole 423 communicating with the lower connecting hole sleeve 421, and the lower end of the upper connecting hole sleeve 411 is inserted into the lower receiving through hole 423; the lower end of the upper connecting hole sleeve 411 is provided with a guide inclined wall 413 for guiding the upper bushing 41 to be quickly inserted into the lower bushing 42.

[0043] like Figure 3-6 As shown, to improve structural strength and reliability, a reinforcing shim 12 is fitted onto the central shaft 1 between the blocking and limiting member 11 and the lower bushing 42. The lower surface of the reinforcing shim 12 engages with the blocking and limiting member 11, and the upper surface of the reinforcing shim 12 engages with the lower end face of the lower bushing 42. During the press-fitting process, this reinforcing shim, as a rigid element with a certain radial dimension, can evenly distribute the concentrated force exerted by the blocking and limiting member on the lower end of the lower bushing to the entire lower end face of the lower bushing. This effectively prevents the lower bushing from collapsing, cracking, or undergoing permanent plastic deformation due to excessive local pressure, significantly improving the durability and safety of the structure under heavy load conditions.

[0044] like Figure 3-6 As shown, in order to improve structural strength and reduce assembly steps, the blocking and limiting member 11 is a shoulder integrally formed with the central shaft 1. The parallelism between the upper surface of the shoulder and the lower end face of the lower connecting hole sleeve 421 is ≤0.02mm, so as to ensure that the axial clamping force is evenly distributed along the circumferential direction and to avoid the rotor housing 31 from tilting due to uneven force.

[0045] The present invention provides a drone, including a drone body, wherein the drone body employs an external rotor motor with reliable connection as described above.

Claims

1. A reliable external rotor motor, characterized in that... The assembly includes a central shaft (1), a stator assembly (2), and a rotor assembly (3). The central shaft (1) is rotatably connected to the stator assembly (2), and the rotor assembly (3) is fixedly connected to the central shaft (1). A bushing assembly (4) is provided between the rotor assembly (3) and the central shaft (1). The bushing assembly (4) is fitted onto the central shaft (1), and an anti-torsion structure (10) for transmitting torque is provided between the inner wall of the bushing assembly (4) and the outer wall of the central shaft (1). The bushing assembly (4) includes an upper bushing (41) and a lower bushing (42) located on the upper and lower sides of the rotor housing (31) of the rotor assembly (3), respectively. Both the upper bushing (41) and the lower bushing (42) are integrally formed aluminum parts. The upper bushing (41) has an upper connecting hole sleeve (411) that can be fitted onto the central shaft (1) and a bushing that is vertically fixedly connected to the upper connecting hole sleeve (411) and abuts against the upper surface of the rotor housing (31). The upper blocking seat (412) is provided with a fastener (43) between the upper blocking seat (412) and the rotor housing (31) for locking and fixing the upper blocking seat (412) relative to the rotor housing (31); the lower bushing (42) has a lower connecting hole sleeve (421) that can be sleeved on the central shaft (1) and a lower blocking seat (43) that is vertically fixed to the lower connecting hole sleeve (421) and abuts against the lower surface of the rotor housing (31) and the corresponding end of the fastener (43). 22), a blocking limit member (11) is provided on the central shaft (1) and located on the lower side of the lower bushing (42). The blocking limit member (11) is configured to cooperate with the lower port of the lower connecting hole sleeve (421) in the assembled state so that the lower blocking seat (422) and the upper blocking seat (412) abut against each other in the axial direction to clamp and fix the upper and lower surfaces of the rotor housing (31) to limit the circumferential rotation and axial displacement of the central shaft (1) relative to the rotor housing (31).

2. The external rotor motor with reliable connection according to claim 1, characterized in that... The fastener (43) is a rivet, the shank of which is press-fitted with the upper stop seat (412) and the rotor housing (31) respectively, and the lower end face of the rivet is in contact with the lower stop seat (422); the fastener (43) is a fastening bolt, and the upper stop seat (412) and the rotor housing (31) are respectively provided with connecting through holes (44), and the fastening bolt passes through the connecting through hole (44) on the rotor housing (31) and is threadedly connected to the connecting through hole (44) on the upper stop seat (412).

3. The external rotor motor with reliable connection according to claim 2, characterized in that... When the fastener (43) is a rivet, the upper end of the rivet protrudes from the upper surface of the upper stop seat (412) to form an anti-loosening fit part for cooperating with an external load.

4. A reliable external rotor motor according to any one of claims 1-3, characterized in that... Both the upper blocking seat (412) and the rotor housing (31) are provided with connecting through holes (44) for fasteners (43) to pass through simultaneously.

5. The external rotor motor with reliable connection according to claim 1, characterized in that... The upper blocking seat (412) and / or the lower blocking seat (422) are provided with a plurality of anti-rotation protrusions arranged circumferentially on the mating surface of the rotor housing (31). The rotor housing (31) is provided with an anti-rotation groove adapted to the anti-rotation protrusion at the corresponding position. The anti-rotation protrusion is embedded in the anti-rotation groove to form a secondary anti-torsional fit between the bushing assembly and the rotor housing.

6. The external rotor motor with reliable connection according to claim 1, characterized in that... The anti-torsion structure (10) is located between the outer wall of the central shaft (1) and the inner wall of the upper bushing (41). The anti-torsion structure (10) includes a straight knurled structure or a mesh knurled structure on the outer wall of the central shaft (1). The knurled structure forms an interference fit with the inner wall of the upper connecting hole sleeve (411). And / or, the anti-torsion structure (10) is a concave-convex anti-rotation fit structure. The anti-torsion structure (10) includes anti-rotation teeth on the outer wall of the central shaft (1) and extending axially, and anti-rotation grooves corresponding to those on the inner wall of the upper connecting hole sleeve (411). The anti-rotation teeth and anti-rotation grooves are mutually anti-rotation fits.

7. The external rotor motor with reliable connection according to claim 1, characterized in that... The lower blocking seat (422) is provided with a lower receiving through hole (423) communicating with the lower connecting hole sleeve (421), and the lower end of the upper connecting hole sleeve (411) is inserted into the lower receiving through hole (423); the lower end of the upper connecting hole sleeve (411) is provided with a guide inclined wall (413) for guiding the upper bushing (41) to be quickly inserted into the lower bushing (42).

8. The external rotor motor with reliable connection according to claim 1, characterized in that... A reinforcing shim (12) is fitted on the central shaft (1) between the blocking limit member (11) and the lower shaft sleeve (42). The lower surface of the reinforcing shim (12) is in blocking engagement with the blocking limit member (11), and the upper surface of the reinforcing shim (12) is in blocking engagement with the lower end face of the lower shaft sleeve (42).

9. The external rotor motor with reliable connection according to claim 1, characterized in that... The blocking and limiting member (11) is a shoulder integrally formed with the central shaft (1).

10. An unmanned aerial vehicle (UAV), characterized in that... It includes a drone body, wherein the drone body employs a reliable external rotor motor as described in any one of claims 1-9.

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