Internal circulation cooling system for propulsion motor based on high-power external rotor integrated controller

Abstract

This invention relates to an internal circulation cooling system for a propulsion motor based on a high-power external rotor integrated controller, and pertains to the field of aircraft. This technical solution is suitable for rapid internal circulation heat dissipation of a high-power external rotor integrated controller propulsion motor, offering significant advantages such as high integration, superior cooling efficiency, and strong reliability. By integrating the cooling system with the motor and electronic control system, external connecting pipes are eliminated, significantly reducing system size and weight, facilitating installation, maintenance, and replacement on eVTOLs. A series cascade cooling method is employed, utilizing the temperature difference between the controller and stator to cool the controller (with lower temperature resistance) before cooling the stator windings. This simplifies the heat dissipation component structure while achieving efficient coolant utilization, significantly improving overall cooling efficiency. Furthermore, heat dissipation fins are integrated into the controller's cooling oil circuit, oil chamber, and return flow channel, effectively increasing the heat dissipation area and enhancing natural convection cooling.

Description

Technical Field

[0001] This invention relates to the field of aircraft technology, and in particular to an internal circulation cooling system for a propulsion motor based on a high-power external rotor integrated controller. Background Technology

[0002] With the country's vigorous development of the low-altitude economy, domestic and foreign manufacturers have been actively engaged in the research and development of Electric Vertical Take-off and Landing (eVTOL) aircraft. As the power component of eVTOL, the propulsion motor directly determines the aircraft's flight performance and payload capacity. To improve power density and torque density, propulsion motors generally adopt a high-power external rotor structure. Simultaneously, to further improve system integration and reduce cable weight and transmission loss, the controller is typically integrated within the external rotor propulsion motor, forming a high-power external rotor integrated controller propulsion motor system.

[0003] High-power external rotor integrated controller propulsion motor systems generate significant heat during high-load operation. Inadequate heat dissipation can lead to a substantial decrease in system efficiency and, in severe cases, permanent damage to components. In this system, the external rotor can dissipate heat through forced convection with external air during its own rotation. However, the stator and controller are located in a closed space within the rotor and cannot be cooled by air; therefore, an internal circulation cooling system is essential. Traditional internal circulation cooling systems consist of independent components such as cooling pumps, radiators, and cooling pipes, and are generally large and heavy, failing to meet the stringent requirements of eVTOL for compact and lightweight propulsion systems. Therefore, achieving a high degree of integration between the cooling system and the propulsion motor system has become a pressing technical challenge in the development of high-power external rotor integrated controller propulsion motors. Summary of the Invention

[0004] The purpose of this invention is to provide an internal circulation cooling system for a propulsion motor based on a high-power external rotor integrated controller, so as to solve the problems existing in the prior art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An internal circulation cooling system for a propulsion motor based on a high-power external rotor integrated controller includes: The motor stator integrates a controller and has internal cooling oil circuits for the propulsion motor. An electric cooling oil pump with a fan is mounted on the rear cover of the controller to drive the circulation of coolant. The controller rear end cover is sealed between the motor stator and the electric cooling oil pump with a fan, and its interior forms an oil chamber with heat dissipation fins, a controller cooling oil circuit, and a flow channel with heat dissipation fins. The heat dissipation component is connected to the rear end cover of the controller and has a main heat dissipation circulation oil circuit inside. The main heat dissipation circulation oil circuit is connected in series with the controller cooling oil circuit, the propulsion motor cooling oil circuit, and the flow channel with heat dissipation fins. The circulation path of the coolant is as follows: it flows out from the heat dissipation component and enters the oil chamber with heat dissipation fins in the rear end cover of the controller. After being cooled by the cooling motor of the electric cooling oil pump with fan, it is drawn out by the cooling pump and flows sequentially through the cooling oil circuit of the controller, the cooling oil circuit of the propulsion motor, and the flow channel with heat dissipation fins. Then it flows back to the heat dissipation component for heat dissipation and returns to the oil chamber with heat dissipation fins to complete the internal circulation.

[0006] In some embodiments, the electric cooling oil pump with fan includes the cooling pump, the cooling motor, and the cooling fan. The cooling fan is mounted on the shaft of the cooling motor and is synchronously driven by the cooling motor. The cooling fan is located between the cooling motor and the heat dissipation assembly, and the air outlet direction of the cooling fan is towards the heat dissipation assembly for forced air cooling of the heat dissipation assembly.

[0007] In some embodiments, the surface of the oil chamber with heat dissipation fins on the rear end cover of the controller is provided with oil chamber heat dissipation fins, and the outer wall of the flow channel with heat dissipation fins is provided with flow channel heat dissipation fins. Both the oil chamber heat dissipation fins and the flow channel heat dissipation fins are in direct contact with the outside air to enhance the preheating capacity of natural convection.

[0008] In some embodiments, the controller cooling oil circuit is divided into a first cooling channel and a second cooling channel, which are independent of each other and correspond to the controller's A heating channel and B heating channel, respectively. The first cooling channel and the second cooling channel are each provided with multiple turbulence columns to disrupt the flow state of the coolant and enhance the heat exchange capacity. All the heating elements of the controller are installed in close contact with the outer wall of the controller cooling oil circuit and dissipate heat through indirect water cooling. The first and second cooling channels of the controller's cooling oil circuit have equal cross-sectional areas, ensuring that the flow rate of coolant through the two channels is consistent and guaranteeing the uniformity of cooling of the controller's A and B heating channels.

[0009] In some embodiments, the motor stator includes a housing, a stator core, stator windings, and an oil separator ring. The propulsion motor cooling oil path is formed by the inner wall of the housing and the outer wall of the oil separator ring. An axial flow channel is provided inside the stator core to connect the upper stator winding cooling area and the lower stator winding cooling area. When the coolant flows through the cooling oil circuit of the propulsion motor, it first enters the upper stator winding cooling area to cool the upper stator winding, and then flows into the lower stator winding cooling area through the axial flow channel of the stator core to cool the lower stator winding. During the cooling process, the coolant directly impacts the ends of the stator winding to enhance the heat exchange effect.

[0010] In some embodiments, the specific flow sequence of the coolant is as follows: after flowing out from the oil chamber with heat dissipation fins on the rear end cover of the controller, it first enters the internal flow channel of the cooling motor to cool it, and then flows into the inlet of the cooling pump; after being pressurized by the cooling pump, it is pumped out to the cooling oil circuit of the controller; the coolant after cooling the controller flows into the cooling oil circuit of the propulsion motor through the internal flow channel of the housing; the coolant after cooling the motor stator flows back to the flow channel with heat dissipation fins on the rear end cover of the controller to converge, and then flows into the heat dissipation assembly through the heat dissipation pipe.

[0011] In some embodiments, the heat dissipation assembly includes a radiator, a radiator inlet pipe, and a radiator outlet pipe; high-temperature coolant flows into the radiator through the radiator inlet pipe, is cooled by the forced airflow of the cooling fan, and then flows back to the oil chamber with heat dissipation fins on the rear end cover of the controller through the radiator outlet pipe.

[0012] In some embodiments, the internal circulation cooling system of the propulsion motor based on the high-power external rotor integrated controller further includes multiple sets of sealing structures, specifically: A sealing connector is provided at the oil circuit interface between the cooling motor and the rear end cover of the controller, and a radial seal is provided on the sealing connector. An end face seal is provided at the first connection interface between the cooling pump and the rear end cover of the controller, and the sealing connector is also provided at the second connection interface. A dynamic seal is provided at the shaft outlet of the cooling motor; All stationary mating surfaces of the electric cooling oil pump with fan are provided with sealing rings, and all dynamic and static mating surfaces are provided with dynamic seals. The sealing connector is also provided at the interface between the rear end cover of the controller and the housing of the motor stator. The sealing ring is also provided at the interface between the motor stator housing and the heat dissipation finned flow channel; The heat dissipation assembly has a sealing pipe nozzle at both the heat dissipation inlet pipe and the heat dissipation interface, and at both the heat dissipation outlet pipe and the heat dissipation interface.

[0013] In some embodiments, the stator winding is cooled by immersion in oil, and the coolant is an insulating coolant. The coolant is in direct contact with the stator winding to remove heat. The controller is completely isolated from the coolant and is indirectly cooled by water through the metal outer wall of the controller's cooling oil circuit. The outlet of the controller cooling oil circuit and the inlet of the propulsion motor cooling oil circuit are connected in series through the internal flow channel of the housing. The coolant first cools the controller with lower temperature resistance, and then cools the stator winding with higher temperature resistance, so as to realize the cascade utilization of the coolant.

[0014] In some embodiments, the bottom of the finned oil chamber at the rear end of the controller is directly connected to the inlet of the cooling pump, and the low-temperature coolant in the finned oil chamber enters the cooling cycle under the negative pressure suction of the cooling pump; the volume of the finned oil chamber is larger than the volume of coolant in a single cycle, which is used to stabilize the flow rate and pressure of the coolant. The number of blades of the cooling fan is matched with the rotational speed of the cooling motor, and the airflow generated by it covers the entire heat dissipation surface of the radiator, forming a uniform forced convection heat transfer field.

[0015] The beneficial effects of the technical solution provided by this invention include at least the following: This technical solution is applicable to the rapid internal circulation cooling of high-power external rotor integrated controller propulsion motors, offering significant advantages such as high integration, superior cooling efficiency, and strong reliability. By integrating the cooling system with the motor and electronic control system, external connecting pipes are eliminated, significantly reducing system size and weight, and facilitating installation, maintenance, and replacement on eVTOLs. A series cascade cooling method for the coolant is employed, based on the temperature difference between the controller and stator, cooling the controller (with lower temperature resistance) first, followed by the stator windings. This simplifies the heat dissipation component structure while achieving efficient coolant utilization, significantly improving overall cooling efficiency. Furthermore, heat dissipation fins are integrated into the controller's cooling oil circuit, oil chamber, and return flow channel, effectively increasing the heat dissipation area and enhancing natural convection cooling. Combined with a full-flow-channel multi-seal design, complete isolation between the coolant and the controller's electrical components is achieved, significantly reducing the risk of various failures caused by oil leakage. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0017] Figure 1 A schematic diagram of the internal circulation cooling system for a propulsion motor based on a high-power external rotor integrated controller, provided by an exemplary embodiment of the present invention, is shown.

[0018] Figure 2An exploded view of an internal circulation cooling system for a propulsion motor based on a high-power external rotor integrated controller, provided by an exemplary embodiment of the present invention, is shown.

[0019] Figure 3 A cross-sectional schematic diagram of an internal circulation cooling system for a propulsion motor based on a high-power external rotor integrated controller, provided by an exemplary embodiment of the present invention, is shown.

[0020] Figure 4 A schematic diagram of the oil circuit of an electric cooling oil pump with a fan is shown in an exemplary embodiment of the present invention for an internal circulation cooling system of a propulsion motor based on a high-power external rotor integrated controller.

[0021] Figures 5 to 6 A schematic diagram of the oil circuit of the controller rear end cover of the internal circulation cooling system of the propulsion motor based on a high-power external rotor integrated controller provided in an exemplary embodiment of the present invention is shown.

[0022] Figures 7 to 9 A schematic diagram of the propulsion motor cooling oil circuit of an internal circulation cooling system for a propulsion motor based on a high-power external rotor integrated controller, provided by an exemplary embodiment of the present invention, is shown.

[0023] Figures 10 to 11 This diagram illustrates a heat dissipation component of an internal circulation cooling system for a propulsion motor based on a high-power external rotor integrated controller, provided by an exemplary embodiment of the present invention.

[0024] In the picture: 1. Motor stator; 11. Housing; 12. Stator core; 13. Stator winding; 14. Oil separator ring; 2. Electric cooling oil pump with fan; 21. Cooling pump; 22. Cooling motor; 23. Cooling fan; 24. Sealing connector; 25. End face seal; 26. Sealing ring; 27. Dynamic seal; 3. Controller rear end cover; 31. Controller cooling oil circuit; 32. Flow channel with heat dissipation fins; 321. Flow channel heat dissipation fins; 33. Oil chamber with heat dissipation fins; 331. Oil chamber heat dissipation fins; 4. Heat dissipation components; 41. Radiator inlet pipe; 42. Radiator outlet pipe; 43. Radiator. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] In this specification, identical components are represented by the same reference numerals. It should be noted that the terms "front," "rear," "left," "right," "upper," and "lower" used in the following description refer to directions in the accompanying drawings, while the terms "bottom surface," "top surface," "inner," and "outer" refer to directions towards or away from a specific component. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this specification, "multiple" means two or more.

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0028] Please see Figures 1 to 6 The internal circulation cooling system for a propulsion motor based on a high-power external rotor integrated controller includes: a motor stator 1, which integrates the controller and forms a propulsion motor cooling oil circuit; an electric cooling oil pump 2 with a fan, mounted on the rear end cover 3 of the controller, for driving the coolant circulation; the rear end cover 3 of the controller, which is sealed between the motor stator 1 and the electric cooling oil pump 2 with a fan, and forms an oil chamber 33 with heat dissipation fins, a controller cooling oil circuit 31, and a flow channel 32 with heat dissipation fins; and a heat dissipation assembly 4, which is connected to the rear end cover 3 of the controller. An internal cooling circulation oil circuit is formed, which is connected in series with the controller cooling oil circuit 31, the propulsion motor cooling oil circuit, and the flow channel with heat dissipation fins 32. The circulation path of the coolant is as follows: it flows out from the heat dissipation component 4 into the oil chamber 33 with heat dissipation fins in the rear cover 3 of the controller, is cooled by the cooling motor 22 of the electric cooling oil pump 2 with a fan, and is then drawn out by the cooling pump 21. It flows through the controller cooling oil circuit 31, the propulsion motor cooling oil circuit, and the flow channel with heat dissipation fins 32 in sequence, and then flows back to the heat dissipation component 4 for heat dissipation before returning to the oil chamber 33 with heat dissipation fins to complete the internal circulation.

[0029] In some embodiments, see Figures 1 to 11 The specific flow sequence of the coolant is as follows: after flowing out from the oil chamber 33 with heat dissipation fins on the rear cover 3 of the controller, it first enters the internal flow channel of the cooling motor 22 to cool it, and then flows into the inlet of the cooling pump 21; after being pressurized by the cooling pump 21, it is pumped out to the controller cooling oil circuit 31, and the coolant after cooling the controller flows into the propulsion motor cooling oil circuit through the internal flow channel of the housing 11; the coolant after cooling the motor stator 1 flows back to the flow channel 32 with heat dissipation fins on the rear cover 3 of the controller to converge, and then flows into the heat dissipation assembly 4 through the heat dissipation pipe.

[0030] In this embodiment, the system addresses the extreme requirements of lightweight, high reliability, and compactness for the propulsion system of electric vertical takeoff and landing (EVTOL) aircraft. Through integrated system design and precise heat load allocation, a closed-loop internal circulation cooling system is constructed. This system deeply integrates cooling power, heat exchange channels, and liquid storage functions into the motor body, eliminating external piping and independent power units. This not only significantly reduces the system's size and weight but also eliminates the risks of pipe vibration leakage and multi-component collaborative failure. First, a low-temperature coolant ensures the stable operation of the cooling pump motor. Then, priority is given to cooling the temperature-sensitive controller, whose failure would have severe consequences. Finally, the heated coolant is used to cool the more temperature-resistant stator windings, maximizing the coolant's heat exchange efficiency. The controller's rear end cover integrates a finned oil chamber and return flow channel, forming an additional natural convection heat dissipation layer. Combined with a coaxially driven forced-air cooling radiator for the oil pump, this ensures the continuous and safe operation of the propulsion system under high-load conditions.

[0031] As a supplementary explanation, the controller in this application is a motor drive controller (inverter / driver) used for high-power power conversion (DC to three-phase AC) to control the speed, torque and direction of the motor. The main component is an IGBT / SiC power module with a power rating of 30-200kW, specifically designed to drive the propulsion motor of an eVTOL aircraft.

[0032] In some embodiments, see Figure 2 , Figure 3 and Figure 6 The electric cooling oil pump 2 with a fan includes a cooling pump 21, a cooling motor 22, and a cooling fan 23. The cooling fan 23 is mounted on the shaft of the cooling motor 22 and is synchronously driven by the cooling motor 22. The cooling fan 23 is located between the cooling motor 22 and the heat dissipation assembly 4, and the air outlet of the cooling fan 23 faces the heat dissipation assembly 4 for forced air cooling of the heat dissipation assembly 4. The bottom of the oil chamber 33 with heat dissipation fins on the rear cover 3 of the controller is directly connected to the inlet of the cooling pump 21. The low-temperature coolant in the oil chamber 33 with heat dissipation fins enters the cooling cycle under the negative pressure suction of the cooling pump 21. The volume of the oil chamber 33 with heat dissipation fins is larger than the volume of coolant in a single cycle, which is used to stabilize the flow rate and pressure of the coolant. The number of blades of the cooling fan 23 is matched with the speed of the cooling motor 22, and the airflow generated by it covers the entire heat dissipation surface of the radiator 43, forming a uniform forced convection heat transfer field.

[0033] In this embodiment, the coaxial integrated design of the electric cooling oil pump 2 with a fan achieves a deep integration of cooling and heat dissipation power, significantly simplifying the system structure and improving energy efficiency. Directly linking the cooling fan 23 with the cooling motor 22 shaft eliminates the need for a separate fan drive unit, reducing the number of components and system weight, simplifying the electrical control logic, and avoiding the complexity of multi-power unit collaborative control. The oil chamber 33 with heat dissipation fins in the controller's rear cover 3 adopts a structure with the bottom directly connected to the inlet of the cooling pump 21. Utilizing negative pressure suction reduces suction resistance, effectively preventing cavitation and improving the pump's operational stability and service life. Its volume design, larger than the volume of a single cycle, can smooth out coolant flow pulsations and pressure fluctuations, and can also buffer temperature shocks caused by sudden load changes through liquid storage and heat storage. Simultaneously, the number of blades in the cooling fan 23 is matched to the speed of the cooling motor 22, ensuring that airflow evenly covers the entire surface of the radiator 43, eliminating heat exchange dead zones, and significantly improving heat dissipation capacity under high load conditions without increasing the size of the heat dissipation module.

[0034] In some embodiments, see Figure 8 and Figure 10 The surface of the oil chamber 33 with heat dissipation fins on the rear cover 3 of the controller is provided with oil chamber heat dissipation fins 331, and the outer wall of the flow channel 32 with heat dissipation fins is provided with flow channel heat dissipation fins 321. Both the oil chamber heat dissipation fins 331 and the flow channel heat dissipation fins 321 are in direct contact with the outside air to enhance the preheating capacity of natural convection.

[0035] In this embodiment, by integrating oil chamber heat dissipation fins 331 and flow channel heat dissipation fins 321 on the rear cover 3 of the controller, a passive pre-cooling layer without power is constructed, which significantly improves the system's heat dissipation redundancy without adding extra components or energy consumption. The flow channel heat dissipation fins 321 with heat dissipation fins on the outer wall of the flow channel 32 can perform the first-stage pre-cooling of the high-temperature coolant that has just completed stator cooling, diverting some heat to the external environment in advance and greatly reducing the heat load of the coolant entering the radiator 43; the oil chamber heat dissipation fins 331 with heat dissipation fins on the surface of the oil chamber 33 perform secondary cooling of the low-temperature coolant after the main cooling, further reducing the initial temperature of the coolant entering the cooling pump 21 and increasing the heat exchange temperature difference of the subsequent cooling stage.

[0036] In some embodiments, see Figure 5The controller cooling oil circuit 31 is divided into a first cooling channel and a second cooling channel, which are independent of each other and correspond to the controller's A heating channel and B heating channel, respectively. The first cooling channel and the second cooling channel are equipped with multiple turbulence columns to disrupt the flow of the coolant and enhance the heat exchange capacity. All the heat-generating elements of the controller are installed in close contact with the outer wall of the controller cooling oil circuit 31 and are cooled by indirect water cooling. The first cooling channel and the second cooling channel of the controller cooling oil circuit 31 have the same cross-sectional area, so that the flow rate of the coolant flowing through the two channels is consistent, ensuring the cooling uniformity of the controller's A and B heating channels.

[0037] In this embodiment, by dividing the cooling channel into independent first and second cooling channels, corresponding to the A and B heating channels of the controller respectively, thermal crosstalk between different power modules is blocked, avoiding cascading overheating caused by local heat accumulation. Simultaneously, the channel layout can be flexibly matched according to the heat density. The densely packed turbulence columns inside the channels not only strongly disrupt the laminar boundary layer of the coolant, significantly improving the convective heat transfer coefficient, but also enhance the mechanical strength of the oil circuit structure, improving the pressure resistance and vibration resistance of the controller's rear cover 3. All heating elements are directly mounted against the outer wall of the oil circuit, eliminating the additional thermal resistance caused by air gaps; the symmetrical design with equal cross-sectional areas ensures that the coolant flow rates of the two channels are completely consistent, achieving matching of the cooling capacities of channels A and B.

[0038] In some embodiments, see Figure 3 , Figure 5 and Figure 7 The motor stator 1 includes a housing 11, a stator core 12, a stator winding 13, and an oil separator ring 14. The propulsion motor cooling oil path is formed by the inner wall of the housing 11 and the outer wall of the oil separator ring 14. An axial flow channel is provided inside the stator core 12 to connect the upper stator winding cooling area and the lower stator winding cooling area. When the coolant flows through the propulsion motor cooling oil path, it first enters the upper stator winding cooling area to cool the upper stator winding, and then flows into the lower stator winding cooling area through the axial flow channel of the stator core 12 to cool the lower stator winding. During the cooling process, the coolant directly impacts the end of the stator winding 13 to enhance the heat exchange effect. The stator winding 13 is cooled by immersion in oil. The coolant is an insulating coolant that comes into direct contact with the stator winding 13 to remove heat. The controller is completely isolated from the coolant and is indirectly cooled by water through the metal outer wall of the controller cooling oil circuit 31. The outlet of the controller cooling oil circuit 31 and the inlet of the propulsion motor cooling oil circuit are connected in series through the internal flow channel of the housing 11. The coolant first cools the controller with lower temperature resistance and then cools the stator winding 13 with higher temperature resistance, thus realizing the cascade utilization of the coolant.

[0039] In this embodiment, the integrated cooling structure design of the motor stator 1 achieves efficient heat dissipation of the stator winding 13 and maximizes the utilization of the coolant. The cooling oil circuit for the propulsion motor is constructed using the structural gap between the housing 11 and the oil separator ring 14, eliminating the need for additional independent pipelines and significantly simplifying the internal structure of the stator. The axial flow channels inside the stator core 12 enable series connection between the upper and lower cooling areas, employing a top-down flow path and utilizing the gravity-assisted flow of the coolant to effectively reduce the power consumption of the cooling pump 21. The coolant directly washes over the ends of the stator winding 13, covering the area where heat is most concentrated. Combined with the direct immersion cooling method of the insulating coolant, the high thermal conductivity of the insulating coolant is fully utilized. Simultaneously, the controller is completely isolated from the coolant, with indirect heat exchange through the metal wall of the controller's cooling oil circuit 31, balancing cooling efficiency and electrical safety. The two oil circuits are connected in series through the internal flow channels of the housing 11, achieving tiered utilization of the coolant based on the temperature differences of the components.

[0040] In some embodiments, see Figure 2 , Figure 3 and Figure 6 The heat dissipation component 4 includes a radiator 43, a radiator inlet pipe 41, and a radiator outlet pipe 42. The high-temperature coolant flows into the radiator 43 through the radiator inlet pipe 41, and after being cooled by the forced air cooling of the cooling fan 23, it flows back to the oil chamber 33 with heat dissipation fins on the rear cover 3 of the controller through the radiator outlet pipe 42.

[0041] In this embodiment, the modular integrated design of the heat dissipation component 4 enables efficient exhaust of heat carried by the coolant. The high-temperature coolant, carrying the heat of the entire system, flows into the radiator 43 through the radiator inlet pipe 41, where it undergoes efficient heat exchange with the forced convection airflow driven by the cooling fan 23, rapidly dissipating the heat in the coolant to the external environment. The cooled coolant then flows back to the finned oil chamber 33 of the controller's rear cover 3 through the radiator outlet pipe 42, storing cooling capacity for the next cooling cycle. This heat dissipation component 4, together with the pre-cooling stage of the finned flow channel 32 at the front end, forms a gradient heat dissipation system, maximizing heat dissipation capacity within a limited installation space. Simultaneously, the modular structure facilitates quick disassembly and maintenance.

[0042] In some embodiments, see Figure 4 , Figure 8 , Figure 9 and Figure 11The internal circulation cooling system of the propulsion motor based on the high-power external rotor integrated controller also includes multiple sets of sealing structures, specifically: a sealing nozzle 24 is provided at the oil circuit interface between the cooling motor 22 and the controller rear end cover 3, and a radial seal is provided on the sealing nozzle 24; an end face seal 25 is provided at the first connection interface between the cooling pump 21 and the controller rear end cover 3, and a sealing nozzle 24 is also provided at the second connection interface; a dynamic seal 27 is provided at the shaft outlet of the cooling motor 22; and the electric cooling oil pump 2 with fan... All static mating surfaces are provided with sealing rings 26, and all dynamic and static mating surfaces are provided with dynamic seals 27; a sealing nozzle 24 is also provided at the interface between the controller rear cover 3 and the housing 11 of the motor stator 1; a sealing ring 26 is also provided at the interface between the housing 11 of the motor stator 1 and the flow channel 32 with heat dissipation fins; a sealing nozzle 24 is provided at the interface between the radiator inlet pipe 41 and the radiator 43 of the heat dissipation assembly 4, and at the interface between the radiator outlet pipe 42 and the radiator 43 of the heat dissipation assembly 4.

[0043] In this embodiment, for the rigid connection interfaces between pipelines and components, a sealing nozzle 24 with radial sealing is used, which can effectively compensate for assembly deviations caused by vibration during aircraft flight and prevent loosening and leakage of the interface; the high-pressure connection surface between the cooling pump 21 and the rear cover 3 of the controller uses an end face seal 25, which forms a high-pressure sealing barrier by adhering to ensure that the coolant does not leak during pressurized delivery. All stationary mating surfaces are equipped with sealing rings 26 to achieve large-area reliable sealing at low cost; dynamic and static mating surfaces such as the shaft of the cooling motor 22 use dynamic seals 27, which perfectly solves the problem of dynamic sealing between rotating and stationary components.

[0044] Next, the working principle of an internal circulation cooling system for a propulsion motor based on a high-power external rotor integrated controller, as described in the embodiments of the present invention, will be explained.

[0045] After the system starts, the pre-cooled low-temperature coolant in the oil chamber 33 with heat dissipation fins first enters the internal flow channel of the cooling motor 22 under the negative pressure suction of the cooling pump 21, giving priority cooling to the circulating power source and ensuring the stable operation of the cooling pump 21. After being pressurized by the cooling pump 21, the coolant enters the dual-channel symmetrical flow path of the controller cooling oil circuit 31 and is equally distributed to the controller A and B heating channels. The internal turbulence column destroys the laminar boundary layer to enhance heat transfer, and the heating element is in close contact with the outer wall of the oil circuit to achieve indirect water cooling, thus completely blocking thermal crosstalk. Subsequently, the coolant enters the propulsion motor cooling oil circuit through the internal flow channel of the housing 11. The oil circuit is formed by the housing 11 and the oil separator ring 14. The coolant cools the upper stator winding 13 from top to bottom, and then cools the lower winding through the axial flow channel of the stator core 12. It directly impacts the winding ends and uses oil immersion to efficiently remove heat, realizing the cascade utilization of the coolant. The coolant carrying the heat of the entire system flows back to the flow channel 32 with heat dissipation fins. After being pre-cooled by the heat dissipation fins 321, it enters the radiator 43 through the radiator inlet pipe 41. The cooling fan 23 and the cooling motor 22 are driven coaxially to generate a uniform airflow that covers the entire surface of the radiator 43 for forced air cooling. After cooling, the coolant returns to the oil chamber 33 with heat dissipation fins through the radiator outlet pipe 42. After being cooled again by the heat dissipation fins 331 in the oil chamber, a complete cycle is completed.

[0046] In summary, this technical solution is suitable for rapid internal circulation cooling of high-power external rotor integrated controller propulsion motors, offering significant advantages such as high integration, superior cooling efficiency, and strong reliability. By integrating the cooling system with the motor and electronic control system, external connecting pipes are eliminated, significantly reducing system size and weight, and facilitating installation, maintenance, and replacement on eVTOLs. A series-stage cooling method for the coolant is adopted, based on the temperature difference between the controller and stator, cooling the controller (with lower temperature resistance) first, followed by the stator windings. This simplifies the heat dissipation component structure while achieving efficient coolant utilization, significantly improving overall cooling efficiency. Furthermore, the controller's cooling oil circuit, oil chamber, and return flow channel all integrate heat dissipation fins, effectively increasing the heat dissipation area and enhancing natural convection cooling. Combined with a full-channel multi-seal design, complete isolation between the coolant and the controller's electrical components is achieved, significantly reducing the risk of various failures caused by oil leakage.

[0047] In the embodiments disclosed in this invention, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; "linking" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments disclosed in this invention according to the specific circumstances.

[0048] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An internal circulation cooling system for a propulsion motor based on a high-power external rotor integrated controller, characterized in that, include: The motor stator (1) has an integrated controller and a propulsion motor cooling oil circuit inside; An electric cooling oil pump (2) with a fan is mounted on the rear cover (3) of the controller to drive the circulation of coolant; The controller rear end cover (3) is sealed between the motor stator (1) and the electric cooling oil pump (2) with a fan, and has an oil chamber (33) with heat dissipation fins, a controller cooling oil passage (31) and a flow channel (32) with heat dissipation fins inside. The heat dissipation component (4) is connected to the rear cover (3) of the controller and has a main heat dissipation circulation oil circuit inside. The main heat dissipation circulation oil circuit is connected in series with the controller cooling oil circuit (31), the propulsion motor cooling oil circuit, and the flow channel with heat dissipation fins (32). The circulation path of the coolant is as follows: it flows out from the heat dissipation component (4) into the oil chamber (33) with heat dissipation fins of the controller rear end cover (3), is cooled by the cooling motor (22) of the electric cooling oil pump (2) with fan, and is then drawn out by the cooling pump (21). It flows through the controller cooling oil circuit (31), the propulsion motor cooling oil circuit, and the flow channel (32) with heat dissipation fins in sequence, and then flows back to the heat dissipation component (4) to dissipate heat and return to the oil chamber (33) with heat dissipation fins to complete the internal circulation.

2. The internal circulation cooling system for a propulsion motor based on a high-power external rotor integrated controller as described in claim 1, characterized in that, The electric cooling oil pump (2) with fan includes the cooling pump (21), the cooling motor (22) and the cooling fan (23). The cooling fan (23) is mounted on the shaft of the cooling motor (22) and is synchronously driven by the cooling motor (22). The cooling fan (23) is located between the cooling motor (22) and the heat dissipation component (4). The air outlet direction of the cooling fan (23) is towards the heat dissipation component (4) for forced air cooling of the heat dissipation component (4).

3. The internal circulation cooling system for a propulsion motor based on a high-power external rotor integrated controller according to claim 1, characterized in that, The surface of the oil chamber (33) with heat dissipation fins of the controller rear cover (3) is provided with oil chamber heat dissipation fins (331), and the outer wall of the flow channel (32) with heat dissipation fins is provided with flow channel heat dissipation fins (321). Both the oil chamber heat dissipation fins (331) and the flow channel heat dissipation fins (321) are in direct contact with the outside air to enhance the natural convection preheating capacity.

4. The internal circulation cooling system for a propulsion motor based on a high-power external rotor integrated controller according to claim 1, characterized in that, The controller cooling oil circuit (31) is divided into a first cooling channel and a second cooling channel, which are independent of each other and correspond to the controller's A heating channel and B heating channel, respectively. The first cooling channel and the second cooling channel are equipped with multiple turbulence columns to disrupt the flow state of the coolant and enhance the heat exchange capacity. All the heating elements of the controller are installed close to the outer wall of the controller cooling oil circuit (31) and are cooled by indirect water cooling. The first and second cooling channels of the controller cooling oil circuit (31) have equal cross-sectional areas, so that the flow rate of the coolant flowing through the two channels is consistent, ensuring the uniformity of cooling of the controller's A and B heating channels.

5. The internal circulation cooling system for a propulsion motor based on a high-power external rotor integrated controller according to claim 1, characterized in that, The motor stator (1) includes a housing (11), a stator core (12), a stator winding (13), and an oil separator ring (14). The propulsion motor cooling oil route is formed by the inner wall of the housing (11) and the outer wall of the oil separator ring (14). An axial flow channel is provided inside the stator core (12) to connect the upper stator winding cooling area and the lower stator winding cooling area. When the coolant flows through the cooling oil circuit of the propulsion motor, it first enters the upper stator winding cooling area to cool the upper stator winding, and then flows into the lower stator winding cooling area through the axial flow channel of the stator core (12) to cool the lower stator winding. During the cooling process, the coolant directly impacts the end of the stator winding (13) to enhance the heat exchange effect.

6. The internal circulation cooling system for a propulsion motor based on a high-power external rotor integrated controller according to claim 1, characterized in that, The specific flow sequence of the coolant is as follows: after flowing out from the oil chamber (33) with heat dissipation fins of the controller rear cover (3), it first enters the internal flow channel of the cooling motor (22) to cool it, and then flows into the inlet of the cooling pump (21); after being pressurized by the cooling pump (21), it is pumped out to the controller cooling oil circuit (31), and the coolant after cooling the controller flows into the propulsion motor cooling oil circuit through the internal flow channel of the housing (11); the coolant after cooling the motor stator (1) flows back to the flow channel (32) with heat dissipation fins of the controller rear cover (3) to merge, and then flows into the heat dissipation assembly (4) through the heat dissipation pipe.

7. The internal circulation cooling system for a propulsion motor based on a high-power external rotor integrated controller according to claim 1, characterized in that, The heat dissipation assembly (4) includes a radiator (43), a radiator inlet pipe (41), and a radiator outlet pipe (42). High-temperature coolant flows into the radiator (43) through the radiator inlet pipe (41), and after being cooled by the forced air cooling of the cooling fan (23), it flows back to the oil chamber (33) with heat dissipation fins of the controller rear end cover (3) through the radiator outlet pipe (42).

8. The internal circulation cooling system for a propulsion motor based on a high-power external rotor integrated controller according to claim 1, characterized in that, The internal circulation cooling system of the propulsion motor based on the high-power external rotor integrated controller also includes multiple sets of sealing structures, specifically: A sealing connector (24) is provided at the oil circuit interface between the cooling motor (22) and the rear end cover (3) of the controller, and a radial seal is provided on the sealing connector (24); The cooling pump (21) is provided with an end face seal (25) at the first connection interface with the controller rear end cover (3), and the sealing pipe nozzle (24) is also provided at the second connection interface. A dynamic seal (27) is provided at the shaft outlet of the cooling motor (22). All static mating surfaces of the electric cooling oil pump (2) with fan are provided with sealing rings (26), and all dynamic mating surfaces are provided with dynamic seals (27). The sealing connector (24) is also provided at the interface between the controller rear cover (3) and the motor stator (1) housing (11). The sealing ring (26) is also provided at the interface between the housing (11) of the motor stator (1) and the heat dissipation finned flow channel (32). The heat sink inlet pipe (41) of the heat sink assembly (4) and the heat sink (43) of the heat sink assembly (4) are provided with the sealing pipe nozzle (24) at the interface between the heat sink inlet pipe (41) of the heat sink assembly (4) and the heat sink (43) of the heat sink assembly (4).

9. The internal circulation cooling system for a propulsion motor based on a high-power external rotor integrated controller according to claim 5, characterized in that, The stator winding (13) is cooled by immersion in oil. The coolant is an insulating coolant. The coolant is in direct contact with the stator winding (13) to remove heat. The controller is completely isolated from the coolant and is indirectly cooled by water through the metal outer wall of the controller's cooling oil circuit (31). The outlet of the controller cooling oil circuit (31) and the inlet of the propulsion motor cooling oil circuit are connected in series through the internal flow channel of the housing (11). The coolant first cools the controller with a lower temperature resistance, and then cools the stator winding (13) with a higher temperature resistance, so as to realize the cascade utilization of the coolant.

10. The internal circulation cooling system for a propulsion motor based on a high-power external rotor integrated controller according to claim 2, characterized in that, The bottom of the oil chamber (33) with heat dissipation fins on the rear cover (3) of the controller is directly connected to the inlet of the cooling pump (21). The low-temperature coolant in the oil chamber (33) with heat dissipation fins enters the cooling cycle under the negative pressure suction of the cooling pump (21). The volume of the oil chamber (33) with heat dissipation fins is greater than the volume of coolant in a single cycle, which is used to stabilize the flow rate and pressure of the coolant. The number of blades of the cooling fan (23) is matched with the rotational speed of the cooling motor (22), and the airflow generated by it covers the entire heat dissipation surface of the radiator (43) to form a uniform forced convection heat transfer field.

Images