Rotor cooling structure of electro-magnetic axial flux motor

Abstract

The utility model discloses a rotor cooling structure of an electro-magnetic axial flux motor. The rotor cooling structure comprises an end cover, back aluminum, a rotor core, a heat pipe, an excitation winding, a pouring sealant, a hollow rotating shaft, a stator and an oil cooling assembly. The heat pipe is formed by distributing a plurality of pipelines in the radial direction of the same circle, the section close to the circle center is a condensation end, and the other section is an evaporation end. The excitation winding is circumferentially wound on the tooth part of the rotor iron core, and a gap is reserved between the excitation winding and a rotor iron core groove to assemble the heat pipe; the evaporation ends of the heat pipes are correspondingly assembled in rotor core grooves, the condensation ends of the heat pipes penetrate through the hollow rotating shaft in the radial direction and are immersed in cooling oil in the hollow rotating shaft, heat generated by the rotor core and the excitation winding is conducted into the cooling oil in the hollow rotating shaft, and the cooling oil is circularly cooled through the oil cooling assembly. The outer side of the rotor core is provided with back aluminum, and the outer side of the back aluminum is provided with an end cover. And a pouring sealant is poured between the rotor iron core and the motor stator. According to the utility model, the working temperature of the rotor is reduced, and the working stability of the motor is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of axial flux motors, in particular to a rotor cooling structure of an electrically excited axial flux motor. Background Art

[0002] Electromagnetic axial flux motors (E-M) are widely used in electric vehicles, aircraft engines, and ship propulsion systems. Compared to traditional motors, they offer advantages such as high power density, a wide speed range, high operating efficiency, and strong anti-interference capabilities. However, the motor's rotor cannot directly exchange heat with the outside world, which leads to excessively high internal rotor temperatures, damaging the motor's internal structure and affecting its dynamic performance and service life. Therefore, effective thermal management of the motor is essential to ensure that heat generated by the rotor is quickly and efficiently transferred to the external environment to ensure stable and safe operation.

[0003] Motor cooling methods are primarily classified into three types: air cooling, water cooling, and oil cooling. Air cooling has become the primary method for rotor heat dissipation due to its simple structure, low cost, and high reliability. However, air cooling can cause significant vibration, noise, and air friction losses, impacting motor efficiency. Furthermore, with the increasing power density of motors, air cooling no longer fully meets heat dissipation requirements. Because water and oil have higher thermal conductivity and specific heat capacity than air, liquid cooling has become a more effective method for rotor thermal management. Water cooling typically involves adding channels within the casing, where water circulates to improve heat dissipation. However, the addition of these channels further increases the axial and radial space in the motor, reducing the system's power density. Furthermore, water cooling requires ensuring the sealing of the circulation channels; leaks can have serious consequences. Oil cooling, on the other hand, offers a more compact design, greater reliability, and suitability for a wider range of operating environments. Hollow shaft oil cooling is commonly used for motor thermal management. It can improve heat dissipation and reduce vibration and noise, but this cooling structure cannot directly cool the rotor and requires an auxiliary cooling system to dissipate heat from the rotor.

[0004] A heat pipe is a highly conductive heat transfer component that transfers heat through the evaporation and condensation of a working fluid within a fully enclosed vacuum tube. The working fluid in the evaporator section of the heat pipe boils or evaporates upon exposure, absorbing heat from an external heat source and generating latent heat of vaporization, transforming from a liquid into steam. Under a pressure differential within the tube, the resulting vapor flows to the condenser section. There, upon encountering the cold walls and an external cooling source, the vapor condenses into a liquid, releasing its latent heat of vaporization. This heat is then transferred through the tube walls to the external cooling source, and the condensed liquid returns to the evaporator section and evaporates again. This cycle completes the heat transfer and exchange between the external hot and cold media. Heat pipes offer a number of advantages, including extremely high thermal conductivity, good isothermal properties, the ability to arbitrarily adjust the heat transfer area between the hot and cold sides, the ability to transfer heat over long distances, and the ability to control temperature. As a heat transfer element with extremely high thermal conductivity, heat pipes can be placed in direct contact with rotor components, rapidly extracting heat from them and transferring it to the cooling medium, thereby achieving a more uniform temperature distribution within the rotor. Therefore, combining heat pipes with traditional oil cooling can significantly improve heat dissipation efficiency while maintaining a compact motor structure and operational safety. Utility Model Content

[0005] The purpose of the utility model is to provide a rotor cooling structure for an electromagnetically excited axial flux motor which can effectively reduce the rotor temperature, improve the output power and overall efficiency of the motor, has low processing and manufacturing difficulty and subsequent maintenance cost, and has strong applicability.

[0006] The technical solution for achieving the purpose of the utility model is: a rotor cooling structure for an electrically excited axial flux motor, comprising an end cover, an aluminum back, a rotor core, a heat pipe, an excitation winding, a potting compound, a hollow shaft, a stator, and an oil cooling assembly; the heat pipe is composed of multiple pipes distributed along the radial direction of the same circle, with a section near the center of the circle being a condensing end and another section being an evaporating end;

[0007] The excitation winding is circumferentially wound around the teeth of the rotor core, and a gap is reserved between the excitation winding and the rotor core slot to assemble the heat pipe; the evaporation end of the heat pipe is correspondingly assembled in the rotor core slot, and the condensation end radially penetrates the hollow shaft and is immersed in the cooling oil inside the hollow shaft. The condensation end conducts the heat generated by the rotor core and the excitation winding to the cooling oil in the hollow shaft, and the oil cooling component circulates and cools the cooling oil; an aluminum back is provided on the outside of the rotor core, and an end cover is provided on the outside of the aluminum back; a potting compound is poured between the rotor core and the stator.

[0008] Furthermore, the heat pipe includes a tube shell, a capillary wick, a steam chamber and a working liquid, and is divided into an evaporation end and a condensation end;

[0009] The tube shell is made of a copper metal tube with a wire mesh capillary wick attached to the inner wall to utilize capillary force to move the working liquid in the steam chamber without changing the position of the heat pipe. The two ends of the tube shell are sealed, the tube is vacuumed, and the working liquid is injected.

[0010] The working fluid at the evaporation end is heated by the rotor components outside the heat pipe, absorbs latent heat and evaporates, and the vapor flows to the condensation end, where it releases latent heat and condenses into liquid. The condensed liquid returns to the evaporation end under the action of capillary force, thereby transferring heat from the rotor components to the cooling oil in the oil cooling assembly.

[0011] Furthermore, the oil inlet and the oil outlet of the oil cooling assembly are on the same side of the hollow shaft, and the oil cooling assembly includes an oil guide pipe, an oil tank, an oil pump, an oil pipe, a cooling oil collector and a dynamic sealing device;

[0012] The heat pipe is embedded in the groove of the rotor core, with the evaporation end placed on the rotor side and the condensation end placed on the shaft side. One end of the hollow shaft is open as an oil inlet and the other end is sealed. A through hole for embedding the heat pipe is provided inside the hollow shaft.

[0013] The oil guide pipe is a fixed device that extends into the interior of the hollow shaft to transport cooling oil. The oil guide pipe is independent of the inner wall of the hollow shaft and the condensation end of the heat pipe and does not contact each other.

[0014] The inner ring of the dynamic sealing device is connected to the rotating shaft for rotation, and the outer ring fixes the cooling oil collector;

[0015] The oil pump pumps cooling oil from the oil tank through the oil pipe into the oil guide pipe, and the oil guide pipe sends the cooling oil into the interior of the hollow shaft. After the cooling oil flows to the closed end of the hollow shaft, the flow is blocked and it is divided into a double loop and flows back to the oil inlet in reverse. When the cooling oil flows in the hollow shaft, the flow rate is slowed down by the pressure of the inner wall of the shaft and the outer wall of the oil guide pipe, and the heat at the rotor conducted by the hollow shaft and the heat pipe is absorbed. The cooling oil flows back to the oil tank and is recycled.

[0016] Furthermore, the oil inlet and the oil outlet of the oil cooling assembly are on different sides of the hollow shaft, and the oil cooling assembly includes an oil tank, an oil pump and an oil pipe;

[0017] One end of the hollow shaft is an oil inlet, and the other end is an oil outlet. Cooling oil is injected into the hollow shaft, and the cooling oil contacts the condensing end of the heat pipe and the inner wall of the hollow shaft, and removes heat by convection.

[0018] The oil pump pumps cooling oil from the oil tank through the oil pipe into the oil inlet of the hollow shaft. Under the action of centrifugal force and oil pressure, the cooling oil flows to the oil outlet side, contacts the inner wall of the hollow shaft and the condensation end of the heat pipe, takes away the heat conducted from the rotor side, and finally flows to the oil outlet of the hollow shaft and flows back to the oil tank through the oil pipe.

[0019] Furthermore, the shell cross-section of the heat pipe is rectangular, matching the slot shape of the rotor core. The working fluid inside the heat pipe is liquid water, and the directional transfer of heat from the evaporation end to the condensation end is achieved through the gas-liquid phase change of water.

[0020] Furthermore, heat dissipation fins are provided inside the hollow rotating shaft; the heat dissipation fins are rectangular and are cast together with the hollow rotating shaft. The heat dissipation fins are a three-section structure, and space is reserved for the installation of heat pipes on both sides.

[0021] Furthermore, the surface of the heat pipe is treated with insulating paint or epoxy resin coating to ensure insulation between the heat pipe and the rotor; the heat pipe is placed in the middle of the slot of the rotor core, and the radial length of the evaporation end is consistent with that of the excitation winding to achieve uniform heat dissipation of the rotor.

[0022] Furthermore, the hollow shaft is made of carbon steel, and a number of through holes are evenly arranged along the circumference of the axis of the hollow shaft. The number of the through holes is the same as that of the heat pipes, and the size is the same as the outer diameter of the heat pipes.

[0023] Furthermore, the back aluminum wraps the rotor core to support the rotor; the potting glue wraps the rotor core teeth, excitation winding, and heat pipe to fix the heat pipe and ensure full contact between the rotor and the heat pipe for heat dissipation; the end cover is made of aluminum alloy.

[0024] Compared with the prior art, the present invention has the following significant advantages:

[0025] (1) Solved the heat dissipation problem of the rotor components of the electromagnetically excited axial flux motor. The evaporation end of the heat pipe with high thermal conductivity is inserted into the rotor slot to provide a low thermal resistance heat dissipation path for the rotor, avoiding the formation of high temperature areas on the rotor, reducing the operating temperature of the rotor, and improving the stability of the motor operation.

[0026] (2) Combining heat pipes with traditional shaft oil cooling improves the heat dissipation efficiency of the enclosed motor rotor while ensuring the compactness and safety of the motor structure;

[0027] (3) The oil cooling structure is set inside the hollow shaft, which saves internal space of the motor, reduces the weight of the shaft, and improves the power density of the motor;

[0028] (4) The number, shape and size of heat pipes can be reasonably selected according to demand, and the system is highly adjustable;

[0029] (5) The heat pipes work independently, making subsequent maintenance easy. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1a This is a schematic diagram of the overall cooling structure in which the oil inlet and oil outlet of the oil cooling component are on the same side of the hollow shaft.

[0031] Figure 1b This is a schematic diagram of the overall cooling structure in which the oil inlet and outlet of the oil cooling assembly are located on different sides of the hollow shaft.

[0032] Figure 2aThis is an exploded view of the rotor cooling structure in which the oil inlet and outlet of the oil cooling assembly are on the same side of the hollow shaft.

[0033] Figure 2b This is an exploded view of the rotor cooling structure where the oil inlet and outlet of the oil cooling assembly are on different sides of the hollow shaft.

[0034] Figure 3a This is a schematic diagram of the cross-sectional structure of a hollow shaft in which the oil inlet and oil outlet of the oil cooling assembly are on the same side of the hollow shaft.

[0035] Figure 3b It is a schematic diagram of the cross-sectional structure of a hollow shaft in which the oil inlet and oil outlet of the oil cooling assembly are located on different sides of the hollow shaft.

[0036] Figure 4a This is a schematic diagram of the rotor structure of an electrically excited axial flux motor without a heat pipe.

[0037] Figure 4b This is a schematic diagram of the rotor structure of an electromagnetically excited axial flux motor with a heat pipe.

[0038] Figure 4c This is a schematic diagram of the rotor structure of an axial flux permanent magnet motor with a heat pipe.

[0039] Figure 5 It is a schematic diagram of the cross-sectional structure of the heat pipe in the utility model.

[0040] Figure 6 It is a schematic diagram of the heat transfer path of the rotor cooling structure of the electromagnetic axial flux motor of the present invention. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] This utility model addresses the difficulty in dissipating heat from the rotor of an electrically excited axial flux motor, due to its compact structure and high power density. By designing a novel rotor cooling structure for this motor, the evaporating end of a heat pipe with high thermal conductivity is inserted into the rotor core slot, while the condensing end is inserted into the hollow shaft and immersed in cooling oil. This achieves rapid and targeted heat transfer within the rotor. This solution is low-cost, easy to implement, and suitable for widespread practical application.

[0043] This utility model addresses the difficulty in dissipating heat from the rotor of an electrically excited axial flux motor, due to its compact structure and high power density. By designing a novel rotor cooling structure for an electrically excited axial flux motor, the evaporating end of a heat pipe with high thermal conductivity is inserted into the rotor core slot, while the condensing end is inserted into the hollow shaft and immersed in the cooling oil within the shaft. This achieves rapid and targeted heat transfer within the rotor. This solution is low-cost, easy to implement, and suitable for widespread practical application.

[0044] The utility model discloses a rotor cooling structure for an electrically excited axial flux motor, comprising an end cover 1, an aluminum back 2, a rotor core 3, a heat pipe 4, an excitation winding 5, a potting compound 6, a hollow shaft 7, a stator 10, and an oil cooling assembly; the heat pipe 4 is composed of multiple pipes distributed along the radial direction of the same circle, with a section near the center of the circle being a condensation end 4-5 and another section being an evaporation end 4-4;

[0045] The excitation winding 5 is circumferentially wound around the teeth of the rotor core 3, and a gap is reserved between the excitation winding 5 and the slot of the rotor core 3 to assemble the heat pipe 4; the evaporation end 4-4 of the heat pipe 4 is correspondingly assembled in the slot of the rotor core 3, and the condensation end 4-5 radially penetrates the hollow shaft 7 and is immersed in the cooling oil inside the hollow shaft 7. The condensation end 4-5 conducts the heat generated by the rotor core 3 and the excitation winding 5 to the cooling oil in the hollow shaft 7, and the oil cooling component circulates and cools the cooling oil; a back aluminum 2 is provided on the outside of the rotor core 3, and an end cover 1 is provided on the outside of the back aluminum 2; a potting compound 6 is poured between the rotor core 3 and the stator 10.

[0046] As a specific example, the heat pipe 4 includes a tube shell 4-1, a capillary wick 4-2, a steam chamber 4-3 and a working liquid, and is divided into an evaporation end 4-4 and a condensation end 4-5;

[0047] The tube shell 4-1 is made of a copper metal tube with a wire mesh capillary wick 4-2 attached to the inner wall. This uses capillary force to move the working liquid within the steam chamber 4-3 regardless of the position of the heat pipe 4. The tube shell 4-1 is sealed at both ends, the tube is evacuated, and the working liquid is injected.

[0048] The working fluid at the evaporation end 4-4 is heated by the rotor components outside the heat pipe 4, absorbs latent heat and evaporates, and the vapor flows to the condensation end 4-5, where it releases latent heat and condenses into liquid. The condensed liquid returns to the evaporation end 4-4 under the action of capillary force, thereby transferring heat from the rotor components to the cooling oil of the oil cooling assembly.

[0049] As a specific example, the oil inlet and the oil outlet of the oil cooling assembly are on the same side of the hollow shaft 7, and the oil cooling assembly includes an oil guide pipe 11, an oil tank 12, an oil pump 13, an oil pipe 14, a cooling oil collector 15 and a dynamic sealing device 16;

[0050] The heat pipe 4 is embedded in the groove of the rotor core 3, with the evaporation end 4-4 placed on the rotor side and the condensation end 4-5 placed on the shaft side. One end of the hollow shaft 7 is open as an oil inlet and the other end is sealed. A through hole is provided inside the hollow shaft 7 for embedding the heat pipe 4.

[0051] The oil guide pipe 11 is a fixed device that extends into the interior of the hollow shaft 7 to transport cooling oil. The oil guide pipe 11 is independent of the inner wall of the hollow shaft 7 and the condensation end 4-5 of the heat pipe 4 and does not contact each other.

[0052] The inner ring of the dynamic sealing device 16 is connected to the rotating shaft for rotation, and the outer ring fixes the cooling oil collector 15;

[0053] The oil pump 13 pumps cooling oil from the oil tank 12 through the oil pipe 14 into the oil guide pipe 11, and the oil guide pipe 11 sends the cooling oil into the interior of the hollow shaft 7. After the cooling oil flows to the closed end of the hollow shaft 7, the flow is blocked and it is divided into a double circuit to flow back to the oil inlet in reverse. When the cooling oil flows in the hollow shaft 7, the flow rate is slowed down by the pressure of the inner wall of the shaft and the outer wall of the oil guide pipe 11, and the heat at the rotor conducted by the hollow shaft 7 and the heat pipe 4 is absorbed. The cooling oil flows back to the oil tank 12 and is recycled.

[0054] As a specific example, the oil inlet and the oil outlet of the oil cooling assembly are on different sides of the hollow shaft, and the oil cooling assembly includes an oil tank 12, an oil pump 13 and an oil pipe 14;

[0055] One end of the hollow shaft 7 is an oil inlet, and the other end is an oil outlet. Cooling oil is injected into the hollow shaft 7. The cooling oil contacts the condensation end 4-5 of the heat pipe and the inner wall of the hollow shaft 7, and removes heat by convection.

[0056] The oil pump 13 pumps cooling oil from the oil tank 12 into the oil inlet of the hollow shaft 7 through the oil pipe 14. Under the action of centrifugal force and oil pressure, the cooling oil flows to the oil outlet side, contacts the inner wall of the hollow shaft 7 and the condensation end 4-5 of the heat pipe 4, and takes away the heat conducted from the rotor side. Finally, the cooling oil flows to the oil outlet of the hollow shaft 7 and flows back to the oil tank 12 through the oil pipe 14.

[0057] As a specific example, the shell cross-section of the heat pipe 4 is rectangular, matching the slot type of the rotor core 3. The working fluid inside the heat pipe 4 is liquid water, and the directional transfer of heat from the evaporation end 4-4 to the condensation end 4-5 is achieved through the gas-liquid phase change of water.

[0058] As a specific example, heat dissipation fins are provided inside the hollow shaft 7; the heat dissipation fins are rectangular and cast together with the hollow shaft 7, and the heat dissipation fins are a three-section structure, which reserves space for the installation of the heat pipes 4 on both sides.

[0059] As a specific example, the surface of the heat pipe 4 is treated with insulating paint or epoxy resin coating to ensure insulation between the heat pipe 4 and the rotor; the heat pipe 4 is placed in the middle of the slot of the rotor core 3, and the radial length of the evaporation end 4-4 is consistent with that of the excitation winding 5 to achieve uniform heat dissipation of the rotor.

[0060] As a specific example, the hollow shaft 7 is made of carbon steel, and a number of through holes 7 - 3 are evenly arranged along the circumference of the axial direction of the hollow shaft 7 . The number of the through holes 7 - 3 is the same as that of the heat pipes 4 , and the size is the same as the outer diameter of the heat pipes 4 .

[0061] As a specific example, the back aluminum 2 wraps the rotor core 3 to support the rotor; the potting glue 6 wraps the teeth of the rotor core 3, the excitation winding 5, and the heat pipe 4 to fix the heat pipe and ensure that the rotor and the heat pipe 4 are in full contact and dissipate heat; the end cover 1 is made of aluminum alloy.

[0062] The utility model also provides a method for assembling the rotor cooling structure of the electrically excited axial flux motor, comprising the following steps:

[0063] Step 1: Wind the excitation winding 5 circumferentially on the rotor core 3 using a tool. A gap is reserved between the excitation winding 5 and the slots of the rotor core 3 , and the size of the reserved gap is larger than the size of the heat pipe 4 .

[0064] Step 2: Process the hollow shaft 7 and evenly arrange a number of through holes 7-3 along the axial direction. The hole diameters match the size of the heat pipe 4.

[0065] Step 3: Install the pressed heat pipe 4 into the reserved gap between the excitation winding 5 and the slot of the rotor core 3, inserting it into the reserved gap in a radially parallel state to the slot of the excitation winding 5, and inserting the condensing end 4-5 into the through hole 7-3 of the hollow shaft 7;

[0066] Step 4: Install the aluminum back 2 and the end cover 1, and seal the entire rotor assembly with potting compound 6 to form a complete and sealed rotor structure.

[0067] Step 5: Arrange the oil cooling assembly. The condensing end 4-5 transfers the heat generated by the rotor core 3 and the excitation winding 5 to the cooling oil in the hollow shaft 7. The oil cooling assembly circulates and cools the cooling oil.

[0068] As a specific example, the hollow shaft is evenly provided with through holes on both sides along the circumferential direction of the axis, and the through holes penetrate the hollow shaft in the radial direction. The number and shape of the through holes are consistent with those of the heat pipe.

[0069] The heat pipe is pressed from a circular cross-section to a rectangular cross-section, and the surface is passivated and sprayed with insulation paint; the evaporation end of the heat pipe is on the rotor side, and the condensation end is on the shaft side, so as to carry out directional heat transfer.

[0070] As a specific example, the rotor unit and the stator unit are symmetrically distributed along the axial center line, the stator unit is arranged between the two rotors, and equal air gap lengths are set between the rotor unit and the stator unit.

[0071] As a specific example, insulating paper is wrapped between the winding and the iron core to ensure insulation safety.

[0072] As a specific example, the heat pipe is in close contact with the rotor core and the excitation winding to reduce thermal resistance and improve heat transfer efficiency.

[0073] As a specific example, the evaporation end of the heat pipe is consistent with the radial length of the excitation winding, and the condensation end radially penetrates the hollow shaft and is immersed in the cooling oil.

[0074] As a specific example, the number of heat pipes is consistent with the number of rotor core slots, and the heat pipes are inserted into the reserved gaps and the through holes of the hollow rotating shaft in a radially parallel state to the excitation winding slots; the heat pipes are independent of each other and do not cross-interfere with each other. Even if some of them are damaged during operation, it will not affect the operation of other heat pipes.

[0075] The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

[0076] Example 1

[0077] Combine Figure 1a 、 Figure 1b 、 Figure 2a 、 Figure 2b The utility model discloses a rotor cooling structure for an electrically excited axial flux motor, comprising an end cover 1, an aluminum back 2, a rotor core 3, a heat pipe 4, an excitation winding 5, a potting compound 6, a hollow shaft 7, a housing 9, a stator 10, and an oil cooling assembly; wherein the oil cooling assembly comprises an oil guide pipe 11, an oil tank 12, an oil pump 13, an oil pipe 14, a cooling oil collector 15, and a dynamic sealing device 16;

[0078] The excitation winding 5 is circumferentially wound around the teeth of the rotor core 3, and a gap is reserved between the excitation winding 5 and the slot of the rotor core 3 to assemble the heat pipe 4; the evaporation end 4-4 of the heat pipe 4 is correspondingly assembled in the slot of the rotor core 3, and the condensation end 4-5 radially penetrates the hollow shaft 7 and is immersed in the cooling oil inside the hollow shaft 7, so as to conduct the heat generated by the rotor core 3 and the excitation winding 5 to the cooling oil in the hollow shaft 7, and then the cooling oil is circulated and cooled by the oil cooling assembly; an aluminum back 2 is provided on the outside of the rotor core 3, and an end cover 1 is provided on the outside of the aluminum back 2; a potting compound 6 is poured between the rotor core 3 and the motor stator.

[0079] As a specific example, the rotor core 3 is made of thin silicon steel sheets wound circumferentially, impregnated with paint and cured to ensure good magnetic flux conduction. The rotor core 3 includes a rotor yoke and rotor teeth, which are evenly distributed on the axial end face of the rotor yoke along the circumference of the axis.

[0080] As a specific example, the excitation winding 5 is wound around the teeth of the rotor core 3 in the circumferential direction, and a gap is reserved between the excitation winding 5 and the slot of the rotor core 3 to accommodate the heat pipe.

[0081] As a specific example, the heat pipe 4 adopts a passive heat transfer element with high thermal conductivity, which can adjust the heat flux density at the evaporation end and the condensation end within a large range; the cross-section of the heat pipe 4 is a rectangular structure, which matches the slot type of the rotor core 3.

[0082] As a specific example, the surface of the heat pipe 4 is passivated, sprayed with insulating paint or coated with epoxy resin to ensure insulation safety between the heat pipe 4 and the rotor.

[0083] As a specific example, combining Figure 5 The heat pipe 4 includes a tube shell 4-1, a capillary wick 4-2, a steam chamber 4-3 and a working liquid, and is divided into an evaporation end 4-4 and a condensation end 4-5;

[0084] The tube shell 4-1 is made of a copper metal tube, and a wire mesh capillary wick 4-2 is attached to the inner wall of the tube shell so as to utilize capillary force to move the working liquid in the steam chamber 4-3 without changing the position of the heat pipe 4; the two ends of the tube shell 4-1 are sealed, the tube is evacuated, and an appropriate amount of working liquid is injected. During operation, the working liquid at the evaporation end 4-4 is heated by the rotor component outside the heat pipe 4, absorbs latent heat and evaporates, and its vapor flows to the condensation end 4-5, releases the latent heat at the condensation end 4-5 and condenses into liquid, and finally returns to the evaporation end 4-4 under the action of capillary force, thereby achieving the purpose of transferring heat from the rotor component to the cooling oil of the oil cooling component.

[0085] As a specific example, the potting glue 6 is used to fix the rotor and the heat pipe 4, ensuring that the heat pipe 4 is in full contact with the rotor for heat dissipation.

[0086] As a specific example, combining Figure 3a 、 Figure 3b The hollow shaft 7 is made of high-quality carbon steel. A number of through holes 7-3 are evenly arranged on the hollow shaft 7 along the axial direction. The number of the through holes 7-3 is the same as that of the heat pipes 4, and the size is the same as the outer diameter of the heat pipes 4.

[0087] As a specific example, the back aluminum 2 wraps around the rotor core 3 to support the rotor.

[0088] As a specific example, the end cover 1 is made of aluminum alloy, which is light in weight and has good thermal conductivity.

[0089] Figure 4a to Figure 4c This is a schematic diagram of the heat pipe installation position of the axial flux motor rotor cooling structure of the utility model, wherein Figure 4a Schematic diagram of the rotor structure of an electrically excited axial flux motor without a heat pipe, wherein the excitation winding 5 is wound around the teeth of the rotor core 3 in the circumferential direction. Figure 4b This is a schematic diagram of the rotor structure of an electromagnetically excited axial flux motor with heat pipes. The heat pipes are evenly arranged along the axial circumference, with the evaporation end radially inserted into the slot 3 of the rotor core and the condensation end radially inserted into the through hole 7-3 of the hollow shaft 7. Figure 4c This is a schematic diagram of the rotor structure of an axial flux permanent magnet motor with heat pipes. The heat pipes 4 are evenly arranged along the axial circumference and embedded in the grooves of the rotor core 3. The heat pipes 4 are in close contact with the rotor core 3 and the permanent magnets 8, quickly transferring the heat on the rotor side to the cooling medium inside the hollow shaft 7, effectively reducing the temperature on the rotor side and avoiding the risk of high-temperature demagnetization of the permanent magnets 8.

[0090] Figure 6 This is a schematic diagram of the heat transfer path of the rotor cooling structure of the electrically excited axial flux motor in the present invention. The heat pipe 4 does not directly absorb heat, but quickly transfers the heat from the rotor side to the hollow shaft 7 side, and finally the cooling oil takes away the heat through convection heat transfer.

[0091] The present invention uses heat pipes for heat transfer and hollow shaft oil cooling to cool the rotor. Since the heat pipes have excellent thermal conductivity, they can quickly transfer the heat generated by the rotor to the shaft. A cavity is provided inside the hollow shaft 7. When cooling oil is injected into the cavity, it comes into contact with the hollow shaft 7 and the heat pipe 4, rapidly removing most of the heat generated by the rotor through convection heat transfer, greatly improving heat dissipation efficiency. Inserting the heat pipe 4 into the rotor slot helps transfer heat from the high-temperature area of ​​the rotor to the evaporation end of the heat pipe, reducing the rotor temperature gradient and distributing the heat more evenly across the rotor, thereby extending the rotor's service life.

[0092] Example 2

[0093] This embodiment provides a rotor cooling structure for an electrically excited axial flux motor, wherein the oil inlet and the oil outlet of the oil cooling assembly are on the same side of the hollow shaft. Figure 1aAs shown, the oil cooling assembly includes an oil guide pipe 11, an oil tank 12, an oil pump 13, an oil pipe 14, a cooling oil collector 15 and a dynamic sealing device 16. The heat pipe 4 is embedded in the groove of the rotor core, the evaporation end 4-4 is placed on the rotor side, and the condensation end 4-5 is placed on the shaft side. The tube shell cross-section of the heat pipe 4 is rectangular, which matches the groove type of the rotor core 3. The liquid working medium inside the heat pipe 4 is liquid water, and the gas-liquid phase change of water can realize the directional transfer of heat from the evaporation end 4-4 to the condensation end 4-5; the shaft is a hollow shaft 7, one end of which is open as an oil inlet and the other end is sealed. A through hole is provided inside the hollow shaft 7 for the heat pipe 4 to be embedded; the oil guide pipe 11 is a fixing device, which extends into the hollow shaft 7 to transport cooling oil. The oil guide pipe 11 is independent of the inner wall of the hollow shaft 7 and the condensation end 4-5 of the heat pipe and does not contact each other; the inner ring of the dynamic sealing device 16 is connected to the rotating shaft for rotation, and the outer ring fixes the cooling oil collector 15; in this scheme, the oil guide pipe 11 sends the cooling oil into the interior of the hollow shaft 7, and the cooling oil is blocked after flowing to the closed end of the hollow shaft 7, and is divided into a double circuit to flow back to the oil inlet in reverse; when the cooling oil flows in the hollow shaft 7, the flow rate slows down due to the pressure of the inner wall of the shaft and the outer wall of the oil guide pipe 11, and the heat at the rotor conducted by the hollow shaft 7 and the heat pipe 4 is fully absorbed, which prolongs the heat exchange time, balances the temperature distribution, and avoids insufficient cooling or local overheating; the cooling oil can be recycled after flowing back to the oil tank 12, saving costs and improving resource utilization.

[0094] Figure 3a This is a schematic cross-sectional view of the shaft of this embodiment. The two ends of the hollow shaft 7 are the hollow shaft open end 7-1 and the hollow shaft closed end 7-2 respectively. Twelve through holes 7-3 are respectively opened on both sides of the hollow shaft 7 along the circumferential direction of the axis to place heat pipes.

[0095] During system operation, the rotor core 3 and the field winding 5 generate heat losses, which is transferred to the heat pipe 4 within the rotor slots. The evaporation end 4-4 of the heat pipe 4 absorbs heat, causing the liquid water within the steam chamber 4-3 to evaporate. Under the influence of a pressure differential, the water vapor flows to the condensation end 4-5, releasing latent heat. Because the heat pipe 4 is embedded in the hollow shaft 7, some of the heat from the condensation end 4-5 is transferred to the hollow shaft 7. Simultaneously, cooling oil is pumped into the oil conduit 11 by the oil pump 13 through the oil pipe 14. Centrifugal force and oil pressure cause the cooling oil to flow to the closed end 7-2 of the hollow shaft 7, where its flow is blocked and redirected. The cooling oil then flows to the open end 7-1 of the hollow shaft 7, removing heat conducted from the hollow shaft 7 and the heat pipe condensation end 4-5. It then flows into the cooling oil collector 15 and ultimately returns to the oil tank 12 through the oil pipe 14, completing a complete cycle.

[0096] Example 3

[0097] This embodiment provides a rotor cooling structure for an electrically excited axial flux motor, wherein the oil inlet and the oil outlet of the oil cooling assembly are on different sides of the hollow shaft, such as Figure 1b As shown, the shaft is a hollow shaft 7, one end of which is an oil inlet and the other end is an oil outlet. The hollow shaft 7 is provided with heat dissipation fins to increase the convection heat exchange area and improve the heat dissipation efficiency; the heat dissipation fins are rectangular and cast together with the hollow shaft 7. The heat dissipation fins are a three-section structure, and space is reserved for the installation of heat pipes 4 on both sides; in this solution, the electromagnetic losses inside the rotor core 3 and the excitation winding 5 are converted into heat and transferred to the evaporation end 4-4 of the heat pipe 4. After the evaporation end 4-4 of the heat pipe 4 is heated, the internal liquid working medium quickly absorbs heat and evaporates. Driven by a small pressure difference, the steam flows to the condensation end 4-5 to release latent heat, thereby realizing the directional transfer of heat from the rotor side to the shaft side. Cooling oil is injected into the hollow shaft 7, and the cooling oil is in full contact with the condensation end 4-5 of the heat pipe and the inner wall of the shaft, and the heat is quickly taken away by convection heat transfer.

[0098] Figure 3b This is a schematic cross-sectional diagram of the shaft of this embodiment. The inner wall of the hollow shaft 7 has three-section heat dissipation fins 7-4 to increase the contact area with the cooling oil and promote rapid heat transfer and absorption. The size, number and shape of the heat dissipation fins can be adjusted according to actual needs to enhance the turbulence between the cooling oil and the heat dissipation fins and improve the heat dissipation efficiency.

[0099] Figure 1b This is a schematic diagram of the overall cooling structure of this embodiment. During system operation, cooling oil is pumped by oil pump 13 through oil pipe 14 into the oil inlet of hollow shaft 7. Under the influence of centrifugal force and oil pressure, the cooling oil flows toward the outlet, where it fully contacts the inner wall of hollow shaft 7 and the condenser ends 4-5 of the heat pipes, removing heat conducted from the rotor. Finally, the cooling oil flows to the oil outlet of hollow shaft 7 and back to oil tank 12 through oil pipe 14.

[0100] The above are only preferred embodiments of the present invention. It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as illustrative and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and range of equivalents of the claims be included in the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

Claims

1. A rotor cooling structure for an electrically excited axial flux motor, characterized in that: It comprises an end cover (1), an aluminum back (2), a rotor core (3), a heat pipe (4), an excitation winding (5), a potting compound (6), a hollow shaft (7), a stator (10) and an oil cooling assembly; the heat pipe (4) is composed of a plurality of pipes distributed along the radial direction of the same circle, a section close to the center of the circle is a condensation end (4-5), and the other section is an evaporation end (4-4); The excitation winding (5) is circumferentially wound around the teeth of the rotor core (3), and a gap is reserved between the excitation winding (5) and the slot of the rotor core (3) to assemble the heat pipe (4); the evaporation end (4-4) of the heat pipe (4) is correspondingly assembled in the slot of the rotor core (3), and the condensation end (4-5) radially penetrates the hollow shaft (7) and is immersed in the cooling oil inside the hollow shaft (7); the condensation end (4-5) conducts the heat generated by the rotor core (3) and the excitation winding (5) to the cooling oil in the hollow shaft (7), and the oil cooling component circulates and cools the cooling oil; the outer side of the rotor core (3) is provided with a back aluminum (2), and the outer side of the back aluminum (2) is provided with an end cover (1); and a potting glue (6) is poured between the rotor core (3) and the stator (10).

2. The rotor cooling structure of the electrically excited axial flux motor according to claim 1, characterized in that: The heat pipe (4) comprises a tube shell (4-1), a capillary wick (4-2), a steam chamber (4-3) and a working liquid, and is divided into an evaporation end (4-4) and a condensation end (4-5); The tube shell (4-1) is a copper metal tube with a wire mesh capillary wick (4-2) attached to the inner wall, so as to utilize capillary force to move the working liquid in the steam chamber (4-3) without being affected by changes in the position of the heat pipe (4); the tube shell (4-1) is sealed at both ends, the tube is vacuumed, and the working liquid is injected; The working fluid at the evaporation end (4-4) is heated by the rotor component outside the heat pipe (4), absorbs latent heat and evaporates, and the vapor flows to the condensation end (4-5), releases latent heat at the condensation end (4-5) and condenses into liquid. The condensed liquid returns to the evaporation end (4-4) under the action of capillary force, thereby transferring heat from the rotor component to the cooling oil of the oil cooling component.

3. The rotor cooling structure of the electrically excited axial flux motor according to claim 2, characterized in that: The oil inlet and the oil outlet of the oil cooling assembly are on the same side of the hollow rotating shaft (7), and the oil cooling assembly includes an oil guide pipe (11), an oil tank (12), an oil pump (13), an oil pipe (14), a cooling oil collector (15) and a dynamic sealing device (16); The heat pipe (4) is embedded in the groove of the rotor core (3), the evaporation end (4-4) is placed on the rotor side, and the condensation end (4-5) is placed on the shaft side. One end of the hollow shaft (7) is open as an oil inlet, and the other end is sealed. A through hole for embedding the heat pipe (4) is provided inside the hollow shaft (7); The oil guide pipe (11) is a fixed device that extends into the interior of the hollow rotating shaft (7) to transport cooling oil. The oil guide pipe (11) is independent of the inner wall of the hollow rotating shaft (7) and the condensation end (4-5) of the heat pipe (4) and does not contact each other. The inner ring of the dynamic sealing device (16) is connected to the rotating shaft for rotation, and the outer ring fixes the cooling oil collector (15); The oil pump (13) pumps cooling oil from the oil tank (12) through the oil pipe (14) into the oil guide pipe (11), and the oil guide pipe (11) sends the cooling oil into the interior of the hollow rotating shaft (7). After the cooling oil flows to the closed end of the hollow rotating shaft (7), the flow is blocked and the cooling oil is divided into two circuits and flows back to the oil inlet in reverse. When the cooling oil flows in the hollow rotating shaft (7), the flow rate is slowed down by the pressure of the inner wall of the rotating shaft and the outer wall of the oil guide pipe (11), and the heat at the rotor conducted by the hollow rotating shaft (7) and the heat pipe (4) is absorbed. The cooling oil flows back to the oil tank (12) and is recycled.

4. The rotor cooling structure of the electrically excited axial flux motor according to claim 2, characterized in that: The oil inlet and the oil outlet of the oil cooling assembly are on different sides of the hollow shaft, and the oil cooling assembly includes an oil tank (12), an oil pump (13) and an oil pipe (14); One end of the hollow rotating shaft (7) is an oil inlet, and the other end is an oil outlet. Cooling oil is injected into the hollow rotating shaft (7), and the cooling oil contacts the condensation end (4-5) of the heat pipe and the inner wall of the hollow rotating shaft (7), and removes heat by convection. The oil pump (13) pumps cooling oil from the oil tank (12) into the oil inlet of the hollow shaft (7) through the oil pipe (14). Under the action of centrifugal force and oil pressure, the cooling oil flows to the oil outlet side, contacts the inner wall of the hollow shaft (7) and the condensation end (4-5) of the heat pipe (4), and takes away the heat conducted from the rotor side. Finally, the cooling oil flows to the oil outlet of the hollow shaft (7) and flows back to the oil tank (12) through the oil pipe (14).

5. The rotor cooling structure of the electrically excited axial flux motor according to claim 3, characterized in that: The heat pipe (4) has a rectangular shell cross-section that matches the slot shape of the rotor core (3); the working fluid inside the heat pipe (4) is liquid water, and the directional transfer of heat from the evaporation end (4-4) to the condensation end (4-5) is achieved through the gas-liquid phase change of water.

6. The rotor cooling structure of the electrically excited axial flux motor according to claim 4, characterized in that: The hollow rotating shaft (7) is provided with heat dissipation fins inside; the heat dissipation fins are rectangular and cast together with the hollow rotating shaft (7); the heat dissipation fins are a three-section structure, and space is reserved for the installation of heat pipes (4) on both sides.

7. The rotor cooling structure of the electrically excited axial flux motor according to claim 5 or 6, characterized in that: The surface of the heat pipe (4) is subjected to an insulating paint spray or epoxy resin coating treatment to ensure insulation between the heat pipe (4) and the rotor; the heat pipe (4) is placed in the middle of the slot portion of the rotor core (3), and the radial length of the evaporation end (4-4) is consistent with that of the excitation winding (5), thereby achieving uniform heat dissipation of the rotor.

8. The rotor cooling structure of the electrically excited axial flux motor according to claim 7, characterized in that: The hollow rotating shaft (7) is made of carbon steel. A plurality of through holes (7-3) are evenly arranged along the circumference of the axial direction of the hollow rotating shaft (7). The number of the through holes (7-3) is the same as that of the heat pipes (4), and the size is the same as the outer diameter of the heat pipes (4).

9. The rotor cooling structure of the electrically excited axial flux motor according to claim 7, characterized in that: The back aluminum (2) wraps around the rotor core (3) to support the rotor; the potting glue (6) wraps around the teeth of the rotor core (3), the excitation winding (5), and the heat pipe (4) to fix the heat pipe and ensure that the rotor and the heat pipe (4) are in full contact and dissipate heat; the end cover (1) is made of aluminum alloy.

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