Outer rotor electric machine and drive device

Abstract

The application discloses an outer rotor motor and a driving device, which comprises a supporting shaft and at least two motor units installed on the supporting shaft, wherein the at least two motor units are arranged at intervals along the axial direction of the supporting shaft, the motor unit comprises a supporting frame, a stator assembly and a rotor assembly which are coaxially arranged in sequence from inside to outside, the supporting frame is sleeved on the supporting shaft, the stator assembly is located between the supporting frame and the rotor assembly, the supporting frame is provided with a first air channel which penetrates through in the axial direction, the first air channel is provided with a first surface heat exchange structure for heat exchange between the heat generated by the stator assembly and the air flowing through the first air channel; at least one flow channel is arranged on the supporting shaft and extends along the axial direction of the supporting shaft, and the flow channel is used for passing in cooling liquid to realize heat exchange with the heat generated by the stator assembly. The combination of air cooling and liquid cooling can realize rapid cooling, and the power density and continuous operation time of the motor can be improved.

Description

Technical Field

[0001] This invention relates to the technical field of electric motors, and particularly to an external rotor motor and a drive device. Background Technology

[0002] With the rapid development of drones, electric aircraft, industrial fans, and other fields, the demand for dual-motor drive systems is increasing. This is especially true in the field of coaxial dual-propeller drones, where a compact, lightweight, high-power-density, and well-heat-dissipating dual-motor drive system is required.

[0003] Currently, when dual motors are running at high power or in extremely harsh operating environments, a large amount of heat generated by the stator windings cannot be dissipated in time, which limits the power density and continuous operating time of the motor. Summary of the Invention

[0004] The purpose of this invention is to provide an external rotor motor and a drive device.

[0005] A first aspect of the present invention provides an external rotor motor, comprising: a support shaft and at least two motor units mounted on the support shaft, wherein the at least two motor units are arranged axially spaced along the support shaft, each motor unit comprising a support frame, a stator assembly, and a rotor assembly arranged coaxially from the inside out, the support frame being sleeved on the support shaft, the stator assembly being located between the support frame and the rotor assembly, the support frame having a first air passage extending axially, the first air passage having a first surface heat exchange structure for exchanging heat generated by the stator assembly with air flowing through the first air passage; the support shaft having at least one flow channel extending axially along the support shaft, the flow channel being used to introduce coolant to achieve heat exchange with the heat generated by the stator assembly.

[0006] Furthermore, the stator assembly includes a stator core and a plurality of windings distributed along the circumferential direction of the stator core. The stator core is sleeved on the support frame so that the heat on the stator core is conducted to the support frame and heat is exchanged with the air flowing through the first air passage through the first surface heat exchange structure. The external rotor motor further includes a heat dissipation assembly located on one side of the stator assembly. The heat dissipation assembly is connected and fixed to the side of the support frame. The heat dissipation assembly has a second air passage that runs through the axial direction. The second air passage is provided with a second type of surface heat exchange structure. The second air passage is connected to the first air passage. The heat dissipation assembly is in contact with the winding so that the heat on the winding is conducted to the heat dissipation assembly. Heat exchange is carried out between the heat dissipation assembly and the air flowing through the second air passage through the second type of surface heat exchange structure.

[0007] Furthermore, the heat dissipation assembly includes: a heat-conducting element and a sleeve, wherein one end of the heat-conducting element is connected to the outer circumferential surface of the sleeve, and the heat-conducting elements are spaced apart along the circumferential direction of the sleeve, the heat-conducting elements are in contact with the winding, the inner cavity of the sleeve is hollow, the inner cavity of the sleeve forms the second air passage, the sleeve is connected and fixed to one side of the support frame, the second type of surface heat exchange structure is located on the inner circumferential surface of the sleeve, and the second type of surface heat exchange structure is spaced apart along the circumferential direction of the sleeve.

[0008] Furthermore, the heat-conducting element is configured to extend radially along the sleeve, with each heat-conducting element filling the gap between two adjacent windings and contacting both adjacent windings, so that heat on the windings is conducted to the sleeve via the heat-conducting element, and heat exchange occurs with the air flowing through the second air passage through the second surface heat exchange structure; wherein, The second type of surface heat exchange structure includes a heat sink extending radially inward along the sleeve and protruding from the sleeve to the side opposite to the support frame.

[0009] Furthermore, the support frame includes a bracket, an inner ring sleeve and an outer ring sleeve arranged coaxially, the two ends of the bracket are respectively connected to the inner ring sleeve and the outer ring sleeve, and the bracket is spaced apart along the circumferential direction, the space between the inner ring sleeve and the outer ring sleeve constitutes the first airway; The first type of surface heat exchange structure is located on the inner circumferential surface of the outer ring, and the first type of surface heat exchange structure is distributed at intervals along the circumferential direction of the outer ring; wherein, the first type of surface heat exchange structure includes heat dissipation fins, heat dissipation columns, or turbulence grooves; The outer ring sleeve is connected and fixed to the stator core; wherein, the heat on the stator core is conducted to the outer ring sleeve, and heat is exchanged with the air flowing through the first air passage through the first surface heat exchange structure.

[0010] Furthermore, the rotor assembly includes: a rotor housing, a rotor core, and rotor magnets; wherein, The rotor magnets are spaced apart along the circumference of the rotor core, and the rotor magnets are fixedly connected to the inner circumferential surface of the rotor core. The rotor housing is connected and fixed to the rotor core. The rotor housing is used to connect and fix to the driven load. The rotor assembly and the stator assembly form an electromagnetic coupling so that the rotor housing rotates around the axis of the support shaft. A predetermined gap is reserved between the rotor magnet and the stator core.

[0011] Furthermore, the rotor housing may include a housing, a first end cover, and a second end cover; wherein, The housing is fixedly connected to the rotor core, and the first end cover and the second end cover are fixedly connected to the two sides of the housing respectively. The first end cover and the second end cover are rotatably connected to the support shaft through bearings, and the first end cover is located on the side of the housing close to the heat dissipation component. The first end cap is provided with a first weight reduction hole that extends through the axial direction. The first weight reduction holes are distributed at intervals along the circumference of the first end cap, and the first weight reduction holes are connected to the second air passage. The second end cap is provided with a second weight-reducing hole that extends through the axial direction. The second weight-reducing holes are spaced apart along the circumference of the second end cap and are connected to the first air passage. When the rotor housing rotates, the outside air exchanges heat with the heat generated by the stator assembly through the first weight reduction hole, the second air passage, the first air passage, and the second weight reduction hole.

[0012] Furthermore, the end face of the support shaft is provided with a coolant inlet and a coolant outlet, if the number of flow channels is 2. n When the temperature is -1, the coolant inlet and coolant outlet are located at the two end faces of the support shaft, respectively. If the number of flow channels is 2... n At that time, the coolant inlet and coolant outlet are located on the same end face of the support shaft, where n is an integer greater than or equal to 1; If there are multiple flow channels, and the multiple flow channels are distributed at intervals along the circumference of the support shaft, the two ends of the support shaft are respectively provided with a first confluence channel and a second confluence channel. The first confluence channel and the second confluence channel are both connected to two adjacent flow channels, so that the coolant enters one of the flow channels through the coolant inlet and flows back and forth along the axial direction of the support shaft to the coolant outlet. The distribution circle diameter of the first confluence channel is the same as that of the flow channel, and the distribution circle diameter of the second confluence channel is smaller than that of the flow channel.

[0013] Furthermore, the support shaft is provided with a shoulder, the diameter of which is larger than that of the support shaft. The shoulder is located between the two motor units to maintain a set distance between the two motor units; and / or, The shoulder is used for connection and fixation with the driven device.

[0014] Furthermore, the cooling mode is determined based on the operating power of the motor unit, the stator winding temperature, the operating conditions, and / or the ambient temperature, wherein, If the operating power of the motor unit is less than a first set value, and / or the stator winding temperature is less than a set threshold, the first cooling mode is activated, wherein the first cooling mode includes exchanging the heat generated by the stator assembly with the outside air. If the operating power of the motor unit is greater than the first set value and less than the second set value, the operating conditions do not meet the set requirements and / or the ambient temperature is higher than the preset value, the second cooling mode is activated. The second cooling mode includes heat exchange between the heat generated by the stator assembly and the outside air, and the flow channel is circulated with coolant, which is used to exchange heat with the heat generated by the stator assembly. If the operating power of the motor unit is greater than the second set value, and / or the stator winding temperature is greater than the set threshold, the second cooling mode is activated.

[0015] Furthermore, the support shaft is provided with a central hole and a through hole. The central hole extends through the axial direction of the support shaft, and the through hole is arranged radially along the support shaft. The through hole is connected to the central hole so that the power line of the motor unit is led out through the through hole and the central hole. The end face of the support shaft is provided with mounting threaded holes, which are distributed at intervals along the circumference of the support shaft.

[0016] A second aspect of the present invention provides a drive device including the aforementioned external rotor motor.

[0017] The above-described technical solution of the present invention has the following beneficial technical effects: In this embodiment of the invention, when the motor unit is operating, the heat generated by the stator assembly can be conducted to the support frame. The heat generated by the stator assembly is then exchanged with the air flowing through the air passage via a surface heat exchange structure, achieving air cooling. When coolant is introduced into the flow channel of the support shaft, a large amount of heat generated by the multiple stator assemblies arranged axially along the support shaft is conducted to the support shaft via the support frame, where it rapidly exchanges heat with the coolant or with the hot air in the air passage, thus cooling the motor unit. Therefore, when the motor unit is operating at high power or in extreme operating environments, the combination of air cooling and liquid cooling can achieve rapid cooling and good heat dissipation performance, thereby improving the power density and continuous operating time of the motor. This method can be applied to high power density and high integration scenarios. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of an external rotor motor according to the first embodiment of the present invention; Figure 2 yes Figure 1 Enlarged view of point A; Figure 3 This is an exploded structural diagram of an external rotor motor according to a second embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of the drive device according to the third embodiment of the present invention; Figure 5This is an exploded perspective view of the drive device according to the fourth embodiment of the present invention; Figure 6 This is an exploded perspective view of the drive device according to the fifth embodiment of the present invention; Figure 7 This is a schematic perspective view of the support frame according to the sixth embodiment of the present invention; Figure 8 This is a schematic perspective view of the structure of a heat dissipation assembly according to the seventh embodiment of the present invention; Figure 9 This is a schematic perspective view of the support shaft according to the eighth embodiment of the present invention; Figure 10 This is a structural schematic diagram of the support shaft according to the ninth embodiment of the present invention; Figure 11 yes Figure 10 The right view; Figure 12 yes Figure 11 BB section view; Figure 13 yes Figure 10 CC section view; Figure 14 yes Figure 10 DD sectional view; Figure 15 yes Figure 10 EE sectional view; Figure label: 10. Support shaft; 11. Coolant inlet; 12. Coolant outlet; 13. Flow channel; 14. First manifold channel; 15. Second manifold channel; 16. Center hole; 17. Wiring hole; 18. Mounting hole; 19. Shoulder; 20. Motor unit; 21. Support frame; 22. Stator assembly; 23. Rotor assembly; 24. Heat dissipation assembly; 25. First weight reduction hole; 26. Second weight reduction hole; 27. Power cord; 28. Bearing; 30. Propeller; 40. Fan impeller; 41. Connecting flange; 211. Heat dissipation fins; 212. Inner ring sleeve; 213. Outer ring sleeve; 214. Bracket; 221. Stator core; 222. Winding; 231. Rotor housing; 232. Rotor core; 233. Rotor magnet; 241. Heat dissipation fins; 242. Heat-conducting component; 243. Sleeve; 2311. Housing; 2312. First end cover; 2313. Second end cover. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention. In this document, terms such as first, second, and third are used only to distinguish one feature from another and are not intended to require or imply any order or association between these features.

[0020] An embodiment of the present invention provides an external rotor motor, such as Figures 1-8 As shown, the system includes a support shaft 10 and at least two motor units 20 mounted on the support shaft 10. The at least two motor units 20 are arranged at intervals along the axial direction of the support shaft 10. Each motor unit 20 includes a support frame 21, a stator assembly 22, and a rotor assembly 23, coaxially arranged from the inside out. The support frame 21 is sleeved on the support shaft 10, and the stator assembly 22 is located between the support frame 21 and the rotor assembly 23. The support frame 21 has a first air passage extending axially, and the first air passage is provided with a first surface heat exchange structure for exchanging heat generated by the stator assembly 22 with air flowing through the first air passage. The support shaft 10 has at least one flow channel 13 extending axially along the support shaft 10, and the flow channel 13 is used to introduce coolant to achieve heat exchange with the heat generated by the stator assembly 22.

[0021] Specifically, for example, rotor assembly 23 may include rotor housing 231, rotor core 232, and rotor magnet 233; stator assembly 22 may include stator core 221 and winding 222. When current flows through winding 222, according to Ampere's law, an alternating electromagnetic field is generated around winding 222, with the magnetic field direction changing with the current direction. The alternating electromagnetic field generated by winding 222 passes through the air gap and interacts with the permanent magnet magnetic field of rotor magnet 233. According to Lorentz force law, rotor magnet 233 experiences a tangential electromagnetic force, driving rotor assembly 23 to rotate around support shaft 10. Rotor housing 231 is directly connected to the driven load to achieve power output. The driven load can be, for example, a wind turbine impeller, wheel, or propeller. For example, in an industrial-grade coaxial dual-propeller UAV, it is necessary to simultaneously drive two layers of propellers on one arm, with the blades of the two propellers rotating in opposite directions to counteract the counter-torque. Traditional solutions require two motors stacked vertically, which occupies a large space and is heavy. The external rotor motor provided in this embodiment of the invention has two motor units 20 installed on the same support shaft 10. The two motor units 20 can be installed relative to each other, and the middle part of the arm and the support shaft 10 is connected and fixed. That is, the arm is located between the two external rotor motors, which can significantly reduce the overall height dimension of the driven load and improve the power density. For example, multiple supports distributed along the circumference can be provided on the stator core 221, and copper wires are wound on each support to form a winding 222. When the motor unit 20 is working, the heat generated by the stator assembly 22 can be conducted to the support frame 21. The first type of surface heat exchange structure includes, but is not limited to, heat dissipation fins, heat dissipation columns or turbulence grooves. The heat generated by the stator assembly 22 is exchanged with the air flowing through the first air passage through the heat dissipation fins 211 to achieve air cooling. Since the support frame 21 is sleeved on the support shaft 10, when coolant is introduced into the flow channel 13, a large amount of heat generated by the multiple stator assemblies 22 arranged along the axial direction of the support shaft 10 is conducted to the support shaft 10 through the support frame 21 to quickly exchange heat with the coolant or with the hot air in the air passage, thereby cooling the motor unit 20. Therefore, when the motor unit 20 is running at high power, the large amount of heat generated by the stator assembly 22 is dissipated in time by the coolant, which can improve the power density and continuous running time of the motor. The external rotor motor provided in this embodiment of the invention achieves rapid cooling by combining air cooling and liquid cooling, which has good heat dissipation performance and can be applied to high power density and high integration scenarios. In this way, the support shaft 10 not only serves to support the motor unit 20, but also integrates the flow channel 13. The coolant flowing into the flow channel 13 can achieve rapid cooling of the motor unit 20.

[0022] In some embodiments, the stator assembly 22 includes a stator core 221 and a plurality of windings 222 distributed along the circumferential direction of the stator core 221. The stator core 221 is sleeved on the support frame 21 so that the heat on the stator core 221 is conducted to the support frame 21 and heat is exchanged with the air flowing through the first air passage through the first surface heat exchange structure. The external rotor motor further includes a heat dissipation assembly 24, which is located on one side of the stator assembly 22. The heat dissipation assembly 24 is connected and fixed to the side of the support frame 21. The heat dissipation assembly 24 has a second air passage that runs through the axial direction. The second air passage is provided with a second type of surface heat exchange structure. The second air passage is connected to the first air passage. The heat dissipation assembly 24 is in contact with the winding 222 so that the heat on the winding 222 is conducted to the heat dissipation assembly 24. Heat exchange is carried out with the air flowing through the second air passage through the second type of surface heat exchange structure.

[0023] Specifically, for example, the stator core 221 may include a stator collar and multiple supports connected to the outer circumferential surface of the stator collar. The multiple supports are distributed along the circumferential direction of the stator collar, and the stator collar and multiple supports can be manufactured as a whole. Copper wires are wound onto each support to form a winding 222. When the motor unit 20 is working, the heat generated by the stator core 221 in the stator assembly 22 can be conducted to the support frame 21. The heat generated by the stator assembly 22 is exchanged with the air flowing through the first air passage through the first surface heat exchange structure, achieving air cooling. Since there is insulating resin between the support and the winding 222, the heat generated by the winding 222 can be conducted to the heat dissipation assembly 24. The second surface heat exchange structure exchanges heat with the air flowing through the second air passage, achieving air cooling. The two motor units 20 have independent stator assemblies 22 and rotor assemblies 23, which can be controlled independently. When the two motor units 20 are installed on the same support shaft 10, they can be installed opposite each other, that is, the heat dissipation assembly 24 is installed on the outside of the two motor units 20. The second air passage is connected to the first air passage, which allows outside air to enter the second air passage and the first air passage, achieving a better air circulation path and thus achieving a better heat dissipation effect.

[0024] In some embodiments, the heat dissipation assembly 24 includes a heat-conducting element 242 and a sleeve 243. One end of the heat-conducting element 242 is connected to the outer circumferential surface of the sleeve 243, and the heat-conducting elements 242 are spaced apart along the circumferential direction of the sleeve 243. The heat-conducting elements 242 are in contact with the winding 222. The inner cavity of the sleeve 243 is hollow and forms the second air passage. The sleeve 243 is fixedly connected to one side of the support frame 21. One end of the heat sink 241 is connected to the inner circumferential surface of the sleeve 243, and the heat sink 241 is spaced apart along the circumferential direction of the sleeve 243.

[0025] The hollow inner cavity of sleeve 243 not only reduces the weight of heat dissipation assembly 24, but also forms a second air passage, which is beneficial for dissipating the heat generated by stator assembly 22. A second type of surface heat exchange structure is, for example, a heat sink 241. A heat conductor 242 is located on the outside of sleeve 243, which is beneficial for conducting heat from winding 222. The heat sink 241 is connected and fixed to the inner wall of sleeve 243, located in the airflow path. By increasing the heat dissipation area, it facilitates heat exchange with the outside air.

[0026] In some embodiments, the heat-conducting element 242 is configured to extend radially along the sleeve 243, with each heat-conducting element 242 filling the gap between two adjacent windings 222 and contacting both adjacent windings 222. This allows heat from the windings 222 to be conducted to the sleeve 243 via the heat-conducting element 242, and then exchanged with air flowing through the second air passage via the heat sink 241. The heat sink 241 extends radially inward along the sleeve 243 and protrudes from the sleeve 243 to the side opposite to the support frame 21. The heat-conducting element 242 can be, for example, a heat-conducting filler block filling the gap between two adjacent windings. It can be cylindrical, trapezoidal, wedge-shaped, or other irregularly shaped blocks that can adaptively conform to the winding contours. The shape of the heat-conducting element 242 is not strictly limited here. To reduce the weight of the heat-conducting component and achieve better contact heat conduction, the heat-conducting component 242 can be made into a cylinder. The axial length of the cylinder can be the same as the height of the winding 222. The cylinder can be hollow. Each heat-conducting component 242 is located between two adjacent windings 222. The wound windings 222 are elliptical, and there is a gap between the arc surfaces of two adjacent windings 222. Each heat-conducting component 242 fills this gap. The outer circumferential surface of the same heat-conducting component 242 is in contact with the two adjacent windings 222, which is beneficial for heat conduction on each winding 222 and for heat exchange between each winding 222 and the outside air. The heat sink 241 extends radially inward along the sleeve 243, and the heat sink 241 protrudes from the sleeve 243 on the side away from the support frame 21. This increases the heat dissipation area of ​​the heat sink 241, which is beneficial for heat exchange with the outside air. Therefore, the design of the heat dissipation component 24 is not only conducive to heat conduction and dissipation on each winding 222, but also conducive to heat dissipation of each winding 222 itself. Furthermore, the design of the heat dissipation component 24 also reduces the overall weight.

[0027] In some embodiments, the support frame 21 includes a bracket 214, an inner ring sleeve 212 and an outer ring sleeve 213 arranged coaxially. The two ends of the bracket 214 are respectively connected to the inner ring sleeve 212 and the outer ring sleeve 213, and the bracket 214 is spaced apart along the circumferential direction. The space between the inner ring sleeve 212 and the outer ring sleeve 213 forms the first air passage. The first surface heat exchange structure is, for example, a heat dissipation fin 211. One end of the heat dissipation fin 211 is connected to the inner circumferential surface of the outer ring sleeve 213, and the heat dissipation fin 211 is located between two adjacent brackets 214. The heat dissipation fin 211 is spaced apart along the circumferential direction of the outer ring sleeve 213. The outer ring sleeve 213 is connected and fixed to the stator core 221. The inner ring 212 and outer ring 213, which are coaxially arranged, are connected into an integral structure by a bracket 214. The bracket 214 is distributed at intervals along the circumference. The outer ring 213 and the stator core 221 can be connected and fixed by an interference fit, and the outer ring 213 and the stator core 221 can be connected and fixed by a locating pin. The inner diameter of the inner ring 212 is adapted to the support shaft 10. The inner ring 212 is sleeved on the support shaft 10. The space between the inner ring 212 and the outer ring 213 forms the first air passage. The heat dissipation fins 211 are located in the first air passage. Therefore, the design of the support frame 21 not only supports the motor unit 20, but also facilitates the conduction and dissipation of heat on the stator core 221, and further reduces its overall weight. The outer ring 213 has a notch, and the inner ring 212 has a corresponding wire hole to facilitate the introduction of the power line from the stator assembly 22 into the support shaft 10, and out from the center of the support shaft 10.

[0028] In some embodiments, the rotor assembly 23 includes: a rotor housing 231, a rotor core 232, and rotor magnets 233; wherein the rotor magnets 233 are spaced apart along the circumferential direction of the rotor core 232, and the rotor magnets 233 are fixedly connected to the inner circumferential surface of the rotor core 232; the rotor housing 231 is fixedly connected to the rotor core 232, and the rotor housing 231 is used to be fixedly connected to the driven load; the rotor assembly 23 forms an electromagnetic coupling with the stator assembly 22, so that the rotor housing 231 rotates around the axis of the support shaft 10; a predetermined gap is reserved between the rotor magnets 233 and the stator core 221.

[0029] The rotor core 232 may have multiple grooves evenly spaced along its circumference. The side of the rotor magnet 233 may be coated with adhesive. The rotor magnet 233 is inserted into the grooves to achieve a firm bond between the rotor magnet 233 and the rotor core 232. The rotor housing 231 may be fitted onto the rotor core 232 and connected and fixed by an interference fit. The rotor housing 231 is connected and fixed to the driven load through its outer circumferential surface or end face. For example, a predetermined gap of 0.5-2mm may be reserved between the rotor magnet 233 and the stator core 221.

[0030] In some embodiments, the rotor housing 231 may include a housing 2311, a first end cover 2312, and a second end cover 2313; wherein the housing 2311 is fixedly connected to the rotor core 232, the first end cover 2312 and the second end cover 2313 are respectively fixedly connected to both sides of the housing 2311, the first end cover 2312 and the second end cover 2313 are respectively rotatably connected to the support shaft 10 through bearings 28, and the first end cover 2312 is located on the side of the housing 2311 closer to the heat dissipation assembly 24; the first end cover 2312 is provided with a first weight-reducing hole 25 extending axially. The first weight-reducing holes 25 are spaced apart along the circumferential direction of the first end cover 2312, and the first weight-reducing holes 25 are connected to the second air passage; the second end cover 2313 is provided with a second weight-reducing hole 26 that extends axially, the second weight-reducing holes 26 are spaced apart along the circumferential direction of the second end cover 2313, and the second weight-reducing holes 26 are connected to the first air passage; when the rotor housing 231 rotates, the outside air passes through the first weight-reducing holes 25, the second air passage, the first air passage and the second weight-reducing holes 26 to achieve heat exchange with the heat generated by the stator assembly 22.

[0031] Specifically, the first end cap 2312 has a first recess along the circumferential direction, and correspondingly, a first convex portion extending axially and a first protrusion extending radially are formed on the first end cap 2312. The first convex portion has a plurality of evenly spaced threaded holes along the circumferential direction. The second end cap 2313 has a second recess along the circumferential direction and a second protrusion extending radially. Correspondingly, a second convex portion is formed on the second end cap 2313. The second convex portion has a plurality of evenly spaced threaded holes along the circumferential direction. The housing 2311 is annular in shape and has a plurality of radially penetrating mounting holes. The plurality of mounting holes are spaced apart along the circumferential direction and are located on both axial sides near the housing 2311. The plurality of mounting holes and the plurality of threaded holes are adapted to each other. The housing 2311 is adapted to the first recess and the second recess, that is, the housing 2311 is embedded in the first recess and the second recess. The screw is inserted into the mounting hole and screwed into the threaded hole to connect and fix the housing 2311 to the first end cover 2312 and the second end cover 2313 respectively. The first protrusion and the second protrusion limit the housing 2311 axially. A third recess is provided on the inner circumferential surface of the housing 2311. The rotor core 232 is adapted to the third recess and is embedded in the third recess. The end of the second protrusion on the second end cover 2313 can abut against the rotor core 232 to cooperate with the housing 2311 to limit the rotor core 232 axially and allow the rotor core 232 and the housing 2311 to rotate synchronously. The first end cover 2312 has an axially penetrating first weight-reducing hole 25 on its side. The first weight-reducing hole 25 can be fan-shaped, annular, or triangular, and its radial extension can cover the air passage and winding 222. Air entering through the first weight-reducing hole 25 can directly exchange heat with the winding 222 and the heat sink 241, achieving good heat dissipation. Similarly, the second end cover 2313 has an axially penetrating second weight-reducing hole 26 on its side. Therefore, the first weight-reducing hole 25 and the second weight-reducing hole 26 not only reduce weight but also connect with the air passage for better heat dissipation. The outer surface of the first end cover 2312 also has a weight-reducing groove located between two adjacent first weight-reducing holes 25. The side of the second end cover 2313 protrudes outward along the axial direction, and the second end cover 2313 is provided with a bushing that extends inward along the axial direction. The inner diameter of the bushing is adapted to the bearing 28, and the bearing 28 is installed in the bushing so that the second end cover 2313 and the bearing 28 can be rotatably connected. The outer diameter of the bushing is small, much smaller than the inner diameter of the housing 2311. Therefore, the design of the second end cover 2313 not only increases the heat dissipation space of the stator assembly 22, but also reduces the weight of the whole machine.

[0032] When the propeller 30 installed on the first end cover 2312 rotates at high speed, the propeller 30 is located outside the motor unit 20. Due to the centrifugal force, the outside air can easily pass through the first weight reduction hole 25, the second air passage, the first air passage and the second weight reduction hole 26 to achieve heat exchange with the heat generated by the stator assembly 22, which can achieve a better air cooling effect.

[0033] In other embodiments, air inlets and air outlets may be respectively provided on the sides of the first end cover 2312 and the second end cover 2313 to form a centrifugal or axial airflow path with the second air duct and / or the first air duct.

[0034] In some embodiments, such as Figures 9-15 As shown, the end face of the support shaft is provided with a coolant inlet and a coolant outlet. If the number of flow channels is 2... n When the temperature is -1, the coolant inlet and coolant outlet are located at the two end faces of the support shaft, respectively. If the number of flow channels is 2... n When the coolant inlet and coolant outlet are located on the same end face of the support shaft, n is an integer greater than or equal to 1; if there are multiple flow channels, and the multiple flow channels are distributed circumferentially along the support shaft, the two ends of the support shaft are respectively provided with a first confluence channel and a second confluence channel, and the first confluence channel and the second confluence channel are connected to two adjacent flow channels, so that the coolant enters one of the flow channels through the coolant inlet and flows back and forth along the axial direction of the support shaft to the coolant outlet.

[0035] Specifically, if the number of flow channels 13 is 2 n n is an integer greater than or equal to 1. For example, the number of flow channels 13 can be set to 2, 4, or 6, etc. Multiple flow channels 13 can be evenly distributed along the circumference of the support shaft 10, with the coolant inlet 11 and coolant outlet 12 located on the same end face of the support shaft 10. If the number of flow channels 13 is 2... n When -1, that is, the number of flow channels 13 is 1, 3 or 5, etc., and the coolant inlet 11 and coolant outlet 12 are located on the two end faces of the support shaft 10 respectively.

[0036] For example, one end of the support shaft 10 is provided with a coolant inlet 11 and a coolant outlet 12, and the other end of the support shaft 10 is provided with a first confluence channel 14. The first confluence channel 14 is connected to two adjacent flow channels 13, so that the coolant enters one of the flow channels 13 through the coolant inlet 11 and flows back and forth along the axial direction of the support shaft 10 to the coolant outlet 12. Specifically, the flow channel 13 can be a circular hole. In order to increase the cross-sectional area of ​​the flow channel 13, it is preferable to make the flow channel 13 a fan-shaped annular hole, and the flow channel 13 can be made close to the outer circumferential surface of the support shaft 10. Those skilled in the art will understand that the flow channel 13 can also be made into other shapes, which are not limited here. The coolant enters one of the two adjacent flow channels 13 through the coolant inlet, reaches the first confluence channel 14 along the axial direction of the support shaft 10, and then enters the other flow channel 13 of the two adjacent flow channels, flowing back and forth to the coolant outlet. In this way, the coolant can carry away a large amount of heat generated by the stator winding, effectively improving the heat dissipation capacity of the external rotor motor provided in this embodiment of the invention. The coolant can be an aqueous solution of ethylene glycol, supplied by the coolant circulation system of the driven equipment.

[0037] In some embodiments, one end of the support shaft 10 is provided with a second confluence channel 15. The second confluence channel 15 is located at the same end as the coolant inlet 11. The second confluence channel 15 is connected to two adjacent flow channels 13, so that the coolant enters one of the flow channels 13 through the coolant inlet, reaches the first confluence channel 14, then enters the other flow channel 13, reaches the second confluence channel 15, and then enters the next flow channel 13 through the second confluence channel 15. For example, when the number of flow channels 13 is set to 6, the coolant enters the first flow channel 13 through the coolant inlet, reaches the first confluence channel 14 at the other end along the axial direction of the support shaft 10, then enters the second flow channel 13 adjacent to the first flow channel 13, reaches the second confluence channel 15 along the axial direction of the support shaft 10, and then enters the third flow channel 13 adjacent to the second flow channel 13. This cycle is repeated until the coolant flows out through the sixth flow channel 13 and reaches the coolant outlet.

[0038] In some embodiments, the distribution circle diameter of the first confluence channel 14 is the same as that of the flow channel 13, and the distribution circle diameter of the second confluence channel 15 is smaller than that of the flow channel 13. The second confluence channel 15 is positioned closer to the center of the support shaft 10, allowing the coolant to fully fill the flow channel 13, thus removing more heat and achieving a better cooling effect.

[0039] In some embodiments, the support shaft 10 is provided with a central hole 16 and a through hole 17. The central hole 16 extends axially along the support shaft 10, and the through hole 17 is arranged radially along the support shaft 10 and communicates with the central hole 16, so that the power line 27 of the motor unit 20 is led out through the through hole 17 and the central hole 16. The power line 27 of the motor unit 20 enters the central hole 16 through the through hole 17 and is led out from one end of the support shaft 10. For example, the power line 27 can be led out from the end of the support shaft 10 with a coolant inlet and outlet, which facilitates wiring and piping. The diameter of the central hole 16 in the middle section of the support shaft 10 can be set to be larger than the diameter of the central holes 16 near the two ends. The support shaft 10 can be formed into a hollow shaft structure to reduce the weight of the support shaft 10.

[0040] In some embodiments, the end face of the support shaft 10 is provided with mounting holes 18, which are spaced apart circumferentially along the support shaft 10. When the driven load is mounted on the circumferential surface of the rotor housing, the mounting holes 18 are used to connect and fix the support shaft 10 to the driven device using threaded fasteners. The mounting holes 18 can be threaded holes. The driven device is driven by the driven load, such as a drone, an electric aircraft, or an industrial fan, and the driven load is such as a propeller 30 or a fan impeller 40.

[0041] In some embodiments, the support shaft 10 is provided with a shoulder 19, the diameter of which is larger than that of the support shaft 10. The shoulder 19 is located between the two motor units 20 to maintain a set distance between them; and / or, the shoulder 19 is used for connection and fixation with the driven device. By adjusting the axial length of the shoulder 19, the two motor units 20 can maintain a set distance. For example, when the driven load is an upper and lower propeller 30, one end of the boom can be connected and fixed to the shoulder 19, that is, the boom is located in the middle of the two motor units 20, which significantly reduces the height dimension and improves the working stability of the external rotor motor provided in this embodiment of the invention.

[0042] In some embodiments, the cooling mode is determined based on the operating power of the motor unit, the stator winding temperature, the operating conditions, and / or the ambient temperature. If the operating power of the motor unit is less than a first set value, and / or the stator winding temperature is less than a set threshold, the first cooling mode is activated, wherein the first cooling mode includes exchanging the heat generated by the stator assembly with the outside air. If the operating power of the motor unit is greater than the first set value and less than the second set value, the operating conditions do not meet the set requirements and / or the ambient temperature is higher than the preset value, the second cooling mode is activated. The second cooling mode includes heat exchange between the heat generated by the stator assembly and the outside air, and the flow channel is circulated with coolant, which is used to exchange heat with the heat generated by the stator assembly. If the operating power of the motor unit is greater than the second set value, and / or the stator winding temperature is greater than the set threshold, the second cooling mode is activated.

[0043] Specifically, a temperature sensor can be installed on the stator assembly to measure the temperature of the stator winding in real time. When the obtained stator winding temperature is less than a set threshold, and / or the operating power of the motor unit is less than a first set value, a wind-cooled cooling mode is adopted. That is, air inlets and outlets are respectively set on the first end cover 2312 and the second end cover 2313, or air enters and exits through the first weight reduction hole 25 and / or the second weight reduction hole 26, forming a centrifugal or axial airflow path with the second air passage and / or the first air passage. Heat exchange is carried out with the outside air through the heat exchange structure on the inner surface of the air passage, so as to achieve better cooling of the stator assembly.

[0044] When the obtained stator winding temperature is greater than the set threshold, and / or the operating power of the motor unit is greater than the second set value, a cooling mode combining liquid cooling and air cooling is adopted to achieve rapid cooling of the stator assembly. In the liquid cooling mode, coolant is introduced into the flow channel of the support shaft. When the motor unit is running at high power or high temperature, a large amount of heat generated by the stator assembly is dissipated in time through the coolant.

[0045] Therefore, by selecting appropriate cooling modes, not only can energy be saved and costs reduced, but the heat dissipation capacity and power density of the motor can also be improved. For example, the motor unit can be divided into three power ranges according to its rated power P or continuous operating power, and different cooling modes can be adapted for each power range: 1. Low power region (P≤10kW): The heat generation in this power range is small, and air convection is sufficient to meet the heat dissipation requirements of the motor unit. Therefore, the appropriate cooling mode is air cooling.

[0046] 2. Transition power region (10kW) <P<20kW): This power range falls within the critical zone between air cooling and liquid cooling, allowing for dynamic selection of the cooling mode based on auxiliary criteria. Typical applications include electric motorcycle motors and drive motors for light-duty logistics vehicles. The auxiliary criteria may include the following: 2.1 Duty Cycle / Duty Ratio: For short-duration / intermittent duty cycles S2 / S3, where the motor unit frequently starts and stops, even with a power output of 15-18kW, air cooling can still be used because the motor unit's heat generation is intermittent. For continuous duty cycles S1, where the motor operates at a constant speed for extended periods, such as when the power output exceeds 10kW and the heat generation is consistently high, a combination of air and liquid cooling can be used.

[0047] 2.2 Installation environment and ventilation conditions: For open-type / self-forced air-cooled applications, such as exposed propeller drives, the rotation itself generates airflow, resulting in good heat dissipation. In the 10-20kW range, air-cooling is preferred.

[0048] If the operating conditions are in a closed / semi-closed compartment, such as the chassis or engine compartment where air circulation is poor, liquid cooling mode can be used even if the power is only 10kW.

[0049] 2.3 Ambient temperature: For example, when the ambient temperature is above 40℃, the air temperature difference decreases and the heat dissipation capacity decreases. Liquid cooling can be used for cooling. That is, a 10kW motor that is originally air-cooled needs to start liquid cooling in high-temperature environments to achieve a cooling mode that combines air cooling and liquid cooling, so as to quickly cool down the single unit.

[0050] 3. High power region (P≥20kW): This power range generates significant heat, and pure air cooling cannot meet the heat dissipation requirements in enclosed or semi-enclosed environments; liquid cooling is necessary to remove the heat. Typical applications include passenger car traction motors (such as 80kW drive wheel motors) and large industrial pump motors.

[0051] Embodiments of the present invention provide a driving device, with reference to Figures 4-6This includes the aforementioned external rotor motors. For example, if the drive unit is an electric ducted fan, it may also include a fan impeller 40 and a connecting flange 41. The fan impeller 40 is mounted on the circumferential surface of the rotor housing; the connecting flange 41 is connected and fixed to the end face of the support shaft. For example, if the drive unit is a propeller thruster used on an aircraft, it may also include a propeller 30. The propeller 30 is mounted on the end face of the rotor housing, that is, the propeller 30 is connected and fixed to the first end cover 2312 by a threaded connector; the aircraft arm can be mounted at the shoulder 19 of the support shaft 10, that is, the arm is located between the two external rotor motors, which can significantly reduce the overall height dimension of the driven load and improve the power density. The speed and rotation direction of the two external rotor motors can be controlled independently, and precise differential control can be achieved through independent controllers, meeting the yaw control requirements of application scenarios such as coaxial dual-propeller UAVs, and improving the control flexibility and applicability of the system. When the motor unit 20 is working, the heat generated by the stator assembly 22 can be conducted to the support frame 21. The heat generated by the stator assembly 22 is exchanged with the air flowing through the first air passage through the heat dissipation fins 211, thus achieving air cooling. Since the support frame 21 is sleeved on the support shaft 10, when coolant is introduced into the multiple flow channels 13, a large amount of heat generated by the multiple stator assemblies 22 arranged along the axial direction of the support shaft 10 is conducted to the support shaft 10 through the support frame 21, and rapidly exchanged with the coolant or with the hot air in the air passage, thus achieving cooling of the motor unit 20. Therefore, when the motor unit 20 is running at high power, the large amount of heat generated by the stator assembly 22 is dissipated in time by the coolant, which can improve the power density and continuous running time of the motor. The external rotor motor provided in this embodiment of the invention achieves rapid cooling by combining air cooling and liquid cooling, which has good heat dissipation performance and can be applied to high power density and high integration scenarios. In this way, the support shaft 10 not only serves to support the motor unit 20, but also integrates the flow channel 13. The coolant flowing into the flow channel 13 can achieve rapid cooling of the motor unit 20.

[0052] The above-mentioned technical solution of the present invention has the following technical effects: 1. In this embodiment of the invention, two external rotor motors are mounted on the same support shaft, and loads such as fans and propellers are connected through the rotor housing. The cantilever of the aircraft can be directly mounted on the support shaft, and the cantilever is located between the two external rotor motors. This solves the technical problems of the internal rotor motor requiring the same shaft to pass through the internal rotor assembly of another motor, the cantilever being inserted into the shaft to form a slender shaft, and the concentricity deviation of the inner and outer shafts directly affecting the stability of operation. In this way, the external rotor structure directly connects to the load, avoiding the problems of slender shafts and concentricity, and the structure is more compact and reliable. Furthermore, the two motors adopt the same external rotor structure design, which has good consistency and interchangeability.

[0053] 2. In this embodiment of the invention, two independent motor units are controlled separately, which is simple to control. The two independent motor units can be set to be identical, with strong interchangeability and maintainability. Each motor unit can be disassembled and replaced independently, resulting in low maintenance costs, short repair time, and modular design that facilitates large-scale production and quality control.

[0054] 3. In this embodiment of the invention, the support shaft with integrated multi-channels not only serves as a wiring hub, but the channels inside the support shaft can also carry away the heat from the stator through the working fluid (such as coolant) flowing through the channels, effectively improving the heat dissipation capacity of the dual-motor unit. In this way, the liquid cooling system can enable the external rotor motor to achieve higher power density and extend the continuous running time of the motor.

[0055] 4. In this embodiment of the invention, the external rotor motor has a compact structure and light weight. Furthermore, through the ingenious design of each component, functional reuse is achieved, which effectively improves the utilization rate of the components and enhances the motor's heat dissipation capacity and power density.

[0056] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. An external rotor motor, characterized in that, include: A support shaft and at least two motor units mounted on the support shaft, wherein, At least two motor units are arranged axially spaced along the support shaft. Each motor unit includes a support frame, a stator assembly, and a rotor assembly arranged coaxially from the inside out. The support frame is sleeved on the support shaft, and the stator assembly is located between the support frame and the rotor assembly. The support frame has a first air passage that runs through it axially. The first air passage is provided with a first surface heat exchange structure, which is used to exchange the heat generated by the stator assembly with the air flowing through the first air passage. The support shaft is provided with at least one flow channel, which extends along the axial direction of the support shaft. The flow channel is used to introduce coolant to achieve heat exchange with the heat generated by the stator assembly.

2. The external rotor motor according to claim 1, characterized in that, The stator assembly includes a stator core and multiple windings distributed along the circumference of the stator core. The stator core is sleeved on the support frame so that the heat on the stator core is conducted to the support frame and heat is exchanged with the air flowing through the first air passage through the first surface heat exchange structure. The external rotor motor further includes a heat dissipation assembly located on one side of the stator assembly. The heat dissipation assembly is connected and fixed to the side of the support frame. The heat dissipation assembly has a second air passage that runs through the axial direction. The second air passage is provided with a second type of surface heat exchange structure. The second air passage is connected to the first air passage. The heat dissipation assembly is in contact with the winding so that the heat on the winding is conducted to the heat dissipation assembly. Heat exchange is carried out between the heat dissipation assembly and the air flowing through the second air passage through the second type of surface heat exchange structure.

3. The external rotor motor according to claim 2, characterized in that, The heat dissipation assembly includes: a heat-conducting component and a sleeve, wherein... One end of the heat-conducting element is connected to the outer circumferential surface of the sleeve, and the heat-conducting elements are spaced apart along the circumferential direction of the sleeve. The heat-conducting elements are in contact with the winding. The sleeve has a hollow inner cavity, which forms the second air passage. The sleeve is fixedly connected to one side of the support frame. The second type of surface heat exchange structure is located on the inner circumferential surface of the sleeve, and the second type of surface heat exchange structure is distributed at intervals along the circumferential direction of the sleeve.

4. The external rotor motor according to claim 3, characterized in that, The heat-conducting element is configured to extend radially along the sleeve, with each element filling the gap between two adjacent windings and in contact with both adjacent windings. This allows heat from the windings to be conducted to the sleeve via the heat-conducting element, and then exchanged with air flowing through the second air passage through the second surface heat exchange structure. The second type of surface heat exchange structure includes a heat sink extending radially inward along the sleeve and protruding from the sleeve to the side opposite to the support frame.

5. The external rotor motor according to claim 2, characterized in that, The support frame includes a bracket, an inner ring sleeve and an outer ring sleeve arranged coaxially. The two ends of the bracket are respectively connected to the inner ring sleeve and the outer ring sleeve, and the bracket is spaced apart along the circumferential direction. The space between the inner ring sleeve and the outer ring sleeve constitutes the first airway. The first type of surface heat exchange structure is located on the inner circumferential surface of the outer ring, and the first type of surface heat exchange structure is distributed at intervals along the circumferential direction of the outer ring; wherein, the first type of surface heat exchange structure includes heat dissipation fins, heat dissipation columns, or turbulence grooves; The outer ring sleeve is connected and fixed to the stator core; wherein, the heat on the stator core is conducted to the outer ring sleeve, and heat is exchanged with the air flowing through the first air passage through the first surface heat exchange structure.

6. The external rotor motor according to claim 2, characterized in that, The rotor assembly includes: a rotor housing, a rotor core, and rotor magnets; wherein... The rotor magnets are spaced apart along the circumference of the rotor core, and the rotor magnets are fixedly connected to the inner circumferential surface of the rotor core. The rotor housing is connected and fixed to the rotor core. The rotor housing is used to connect and fix to the driven load. The rotor assembly and the stator assembly form an electromagnetic coupling so that the rotor housing rotates around the axis of the support shaft. A predetermined gap is reserved between the rotor magnet and the stator core.

7. The external rotor motor according to claim 6, characterized in that, The rotor housing includes a shell, a first end cover, and a second end cover; wherein... The housing is fixedly connected to the rotor core, and the first end cover and the second end cover are fixedly connected to the two sides of the housing respectively. The first end cover and the second end cover are rotatably connected to the support shaft through bearings, and the first end cover is located on the side of the housing close to the heat dissipation component. The first end cap is provided with a first weight reduction hole that extends through the axial direction. The first weight reduction holes are distributed at intervals along the circumference of the first end cap, and the first weight reduction holes are connected to the second air passage. The second end cap is provided with a second weight-reducing hole that extends through the axial direction. The second weight-reducing holes are spaced apart along the circumference of the second end cap and are connected to the first air passage. When the rotor housing rotates, the outside air exchanges heat with the heat generated by the stator assembly through the first weight reduction hole, the second air passage, the first air passage, and the second weight reduction hole.

8. The external rotor motor according to claim 1, characterized in that, The end face of the support shaft is provided with a coolant inlet and a coolant outlet. If the number of flow channels is 2... n When the temperature is -1, the coolant inlet and coolant outlet are located at the two end faces of the support shaft, respectively. If the number of flow channels is 2... n At that time, the coolant inlet and coolant outlet are located on the same end face of the support shaft, where n is an integer greater than or equal to 1; If there are multiple flow channels, and the multiple flow channels are distributed at intervals along the circumference of the support shaft, the two ends of the support shaft are respectively provided with a first confluence channel and a second confluence channel. The first confluence channel and the second confluence channel are both connected to two adjacent flow channels, so that the coolant enters one of the flow channels through the coolant inlet and flows back and forth along the axial direction of the support shaft to the coolant outlet. The distribution circle diameter of the first confluence channel is the same as that of the flow channel, and the distribution circle diameter of the second confluence channel is smaller than that of the flow channel.

9. The external rotor motor according to claim 1, characterized in that, The support shaft is provided with a shoulder, the diameter of which is larger than that of the support shaft. The shoulder is located between the two motor units to maintain a set distance between them; and / or, The shoulder is used for connection and fixation with the driven device.

10. The external rotor motor according to any one of claims 1-9, characterized in that, The cooling mode is determined based on the operating power of the motor unit, the stator winding temperature, the operating conditions, and / or the ambient temperature, wherein... If the operating power of the motor unit is less than a first set value, and / or the stator winding temperature is less than a set threshold, the first cooling mode is activated, wherein the first cooling mode includes exchanging the heat generated by the stator assembly with the outside air. If the operating power of the motor unit is greater than the first set value and less than the second set value, the operating conditions do not meet the set requirements and / or the ambient temperature is higher than the preset value, the second cooling mode is activated. The second cooling mode includes heat exchange between the heat generated by the stator assembly and the outside air, and the flow channel is circulated with coolant, which is used to exchange heat with the heat generated by the stator assembly. If the operating power of the motor unit is greater than the second set value, and / or the stator winding temperature is greater than the set threshold, the second cooling mode is activated.

11. A driving device, characterized in that, include: The external rotor motor as described in any one of claims 1-10.

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