Rotor cooling structure of electro-magnetic axial flux motor

Abstract

The invention 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 exciting winding, 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. Back aluminum is arranged outside the rotor iron core, and an end cover is arranged outside the back aluminum; and a pouring sealant is poured between the rotor iron core and the motor stator. The working temperature of the rotor is reduced, and the working stability of the motor is improved.

Description

Technical Field

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

[0002] Electromagnetic axial flux motors are widely used in electric vehicles, aircraft engines, ship propulsion systems and other fields. Compared with traditional motors, they have the advantages of high power density, wide speed regulation range, high operating efficiency, and strong anti-interference. However, the rotor of the motor cannot directly exchange heat with the outside world, which leads to excessively high internal temperature of the rotor, which will damage the internal structure of the motor and affect the dynamic performance and service life of the motor. Therefore, effective thermal management of the motor must be carried out to ensure that the heat generated by the rotor can be quickly and efficiently transferred to the external environment to ensure the stability and safety of the motor operation.

[0003] There are three main cooling methods for motors: air cooling, water cooling, and oil cooling. Air cooling has become the main 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 loss, affecting the operating efficiency of the motor. Moreover, with the continuous increase in motor power density, air cooling can no longer fully meet the heat dissipation requirements. Since water and oil have higher thermal conductivity and specific heat capacity than air, liquid cooling has become a more effective way to manage rotor heat. Water cooling usually involves adding water channels inside the casing, and water-based media circulate in the channels to improve heat dissipation capacity. However, due to the addition of structures such as water channels, the axial and radial space of the motor is further increased, reducing the power density of the system. In addition, the use of water cooling requires the sealing of the circulation channel, and leakage will cause serious consequences. The design structure of oil cooling is more compact, more reliable, and suitable for a wider range of working environments. Hollow shaft oil cooling is often used for thermal management of motors. It can improve heat dissipation performance and reduce vibration noise, but this cooling structure cannot directly cool the rotor, and an auxiliary cooling system is required to achieve rotor heat dissipation.

[0004] A heat pipe is a heat transfer component with high thermal conductivity. It transfers heat by evaporating and condensing the working fluid in a fully enclosed vacuum tube shell. The working fluid in the evaporation section of the heat pipe will boil or evaporate after being heated, absorb heat from the external heat source, generate latent heat of vaporization, and change from liquid to steam. The generated steam flows to the condensation section under the action of a certain pressure difference in the tube. The steam encounters the cold wall and the external cold source, condenses into liquid, and releases the latent heat of vaporization at the same time. It is transferred to the external cold source through the tube wall, and the condensate flows back to the evaporation section and evaporates again. This reciprocating process realizes the heat transfer and exchange of the external cold and hot media. It has a series of advantages such as extremely high thermal conductivity, good isothermal properties, the heat transfer area on both sides of the cold and hot sides can be arbitrarily changed, heat transfer can be carried out over a long distance, and the temperature can be controlled. As a heat transfer element with extremely high thermal conductivity, the heat pipe can be in direct contact with the rotor components, quickly extract heat from them and transfer it to the cooling medium, so that the temperature distribution inside the rotor is more uniform. Therefore, combining the heat pipe with the traditional oil cooling method can significantly improve the heat dissipation efficiency while ensuring the compactness of the motor structure and the safety of operation. Summary of the invention

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

[0006] The technical solution to achieve the purpose of the present invention is: a rotor cooling structure of an electrically excited axial flux motor, comprising an end cover, back aluminum, 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 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, and the other section is an evaporation 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; and potting glue is poured between the rotor core and the stator.

[0008] Further, 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, and a wire mesh capillary wick is attached to the inner wall to use 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 evacuated, 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 of 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, the evaporation end is placed on the rotor side, and the condensation end is 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, extending into 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 into the oil guide pipe through the oil 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 circuit to flow 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] Further, 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 condensation end of the heat pipe and the inner wall of the hollow shaft, and transfers heat by convection.

[0018] The oil pump pumps cooling oil from the oil tank into the oil inlet of the hollow shaft through the oil pipe. 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 the cooling oil 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 type of the rotor core, and the working fluid inside the heat pipe is liquid water, which realizes the directional transfer of heat from the evaporation end to the condensation end through the gas-liquid phase change of water.

[0020] Furthermore, a heat dissipation fin is provided inside the hollow rotating shaft; the heat dissipation fin is rectangular and is cast together with the hollow rotating shaft. The heat dissipation fin is 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 spray 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 plurality of through holes are evenly arranged on the hollow shaft along the circumference of the axis direction. 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 make the rotor fully contact with the heat pipe and dissipate heat; the end cover is made of aluminum alloy.

[0024] A method for assembling a rotor cooling structure of an electrically excited axial flux motor as described above comprises the following steps:

[0025] Step 1: Wind the excitation winding circumferentially on the rotor core by using a tool, and reserve a gap between the excitation winding and the rotor core slot, and the size of the reserved gap is larger than the size of the heat pipe;

[0026] Step 2: Process the hollow shaft and evenly arrange a number of through holes along the axis, with the hole diameter matching the size of the heat pipe;

[0027] Step 3, install the pressed heat pipe into the reserved gap between the excitation winding and the rotor core slot, insert it into the reserved gap in a state of being radially parallel to the excitation winding slot, and insert the condensing end into the through hole of the hollow shaft;

[0028] Step 4: Install the back aluminum and end cover, and use potting glue to seal the end face of the entire rotor assembly to form a complete and sealed rotor structure;

[0029] Step 5: Arrange the oil cooling assembly. The condensing end transfers the heat generated by the rotor core and the excitation winding to the cooling oil in the hollow shaft. The oil cooling assembly circulates and cools the cooling oil.

[0030] Compared with the prior art, the present invention has the following significant advantages:

[0031] (1) Solved the heat dissipation problem of the rotor components of the electrically excited axial flux motor. The evaporating 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 a high temperature zone on the rotor, reducing the operating temperature of the rotor, and improving the stability of the motor operation;

[0032] (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;

[0033] (3) The oil cooling structure is set inside the hollow shaft, which saves the internal space of the motor, reduces the weight of the shaft, and improves the power density of the motor;

[0034] (4) The number, shape and size of heat pipes can be reasonably selected according to demand, and the system is highly adjustable;

[0035] (5) The heat pipes work independently, making subsequent maintenance easy. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1a It is a schematic diagram of the overall cooling structure in which the oil inlet and the oil outlet of the oil cooling component are on the same side of the hollow shaft.

[0037] Figure 1b It is a schematic diagram of the overall cooling structure in which the oil inlet and the oil outlet of the oil cooling assembly are on different sides of the hollow shaft.

[0038] Figure 2a It 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.

[0039] Figure 2b It 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.

[0040] Figure 3a It is a schematic diagram of the cross-sectional structure of a hollow shaft in which the oil inlet and the oil outlet of the oil cooling assembly are on the same side of the hollow shaft.

[0041] Figure 3b It is a schematic diagram of the cross-sectional structure of a hollow shaft in which the oil inlet and the oil outlet of the oil cooling assembly are located on different sides of the hollow shaft.

[0042] Figure 4a It is a schematic diagram of the rotor structure of an electrically excited axial flux motor without a heat pipe.

[0043] Figure 4b It is a schematic diagram of the rotor structure of an electrically excited axial flux motor with a heat pipe.

[0044] Figure 4c This is a schematic diagram of the rotor structure of an axial flux permanent magnet motor with a heat pipe.

[0045] Figure 5 It is a schematic diagram of the cross-sectional structure of the heat pipe in the present invention.

[0046] Figure 6It is a schematic diagram of the heat transfer path of the rotor cooling structure of the electrically excited axial flux motor of the present invention. DETAILED DESCRIPTION

[0047] 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 described embodiments 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 creative work are within the scope of protection of the present invention.

[0048] Aiming at the problem of difficulty in rotor heat dissipation caused by compact structure and high power density of electric excitation axial flux motor, the present invention proposes a novel rotor cooling structure of electric excitation axial flux motor, inserting the evaporation end of the heat pipe with high thermal conductivity into the rotor core slot, and inserting the condensation end into the hollow shaft and immersed in the cooling oil in the shaft, so as to realize the rapid and directional transfer of heat inside the rotor. The solution is low in cost, easy to implement in process, and suitable for wide application in practice.

[0049] The present invention aims at the problem of difficulty in heat dissipation of the rotor caused by the compact structure and high power density of the electromagnetic axial flux motor, and proposes a new rotor cooling structure for the electromagnetic axial flux motor. The evaporation end of the heat pipe with high thermal conductivity is inserted into the rotor core slot, and the condensation end is inserted into the hollow shaft and immersed in the cooling oil in the shaft, so as to realize the rapid and directional transfer of heat inside the rotor. The solution is low-cost, easy to implement in terms of technology, and suitable for wide application in practice.

[0050] The present invention discloses a rotor cooling structure of 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 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 another section is an evaporation end 4-4;

[0051] 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 glue 6 is poured between the rotor core 3 and the stator 10.

[0052] 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;

[0053] The tube shell 4-1 is made of a copper metal tube, and a wire mesh capillary core 4-2 is attached to the inner wall to use capillary force to make the working liquid move 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 the working liquid is injected;

[0054] The working liquid 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.

[0055] 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;

[0056] 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.

[0057] The oil guide pipe 11 is a fixed device, extending 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 4 and does not contact each other.

[0058] 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;

[0059] The oil pump 13 pumps the cooling oil from the oil tank 12 into the oil guide pipe 11 through the oil pipe 14. The oil guide pipe 11 delivers the cooling oil into 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 and flows 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.

[0060] 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;

[0061] 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, and the cooling oil contacts the heat pipe condensation end 4-5 and the inner wall of the hollow shaft 7, and transfers heat by convection.

[0062] 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, takes away the heat conducted from the rotor side, and 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.

[0063] 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.

[0064] As a specific example, a heat sink fin is provided inside the hollow shaft 7; the heat sink fin is rectangular and is cast together with the hollow shaft 7. The heat sink fin is a three-section structure, and space is reserved for the installation of the heat pipes 4 on both sides.

[0065] 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.

[0066] As a specific example, the hollow shaft 7 is made of carbon steel, and a plurality 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 .

[0067] 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 make the rotor fully contact with the heat pipe 4 and dissipate heat; the end cover 1 is made of aluminum alloy.

[0068] The present invention also provides a method for assembling the rotor cooling structure of the electrically excited axial flux motor, comprising the following steps:

[0069] Step 1: Wind the excitation winding 5 circumferentially on the rotor core 3 by using a tool, and reserve a gap between the excitation winding 5 and the slot of the rotor core 3, and the size of the reserved gap is larger than the size of the heat pipe 4;

[0070] Step 2, processing the hollow shaft 7, and evenly arranging a number of through holes 7-3 along the axial direction, the hole diameters of which match the size of the heat pipe 4;

[0071] 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, insert it into the reserved gap in a state of being radially parallel to the slot of the excitation winding 5, and insert the condensing end 4-5 into the through hole 7-3 of the hollow shaft 7;

[0072] Step 4: Install the aluminum back 2 and the end cover 1, and use the potting glue 6 to seal the end face of the entire rotor assembly, thereby forming a complete and sealed rotor structure;

[0073] Step 5, arrange the oil cooling assembly, the condensation 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, and the oil cooling assembly circulates and cools the cooling oil.

[0074] As a specific example, through holes are evenly arranged on both sides of the hollow shaft 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.

[0075] After the heat pipe is pressed from a circular cross section to a rectangular cross section, the surface is passivated and spray-painted with insulation; 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.

[0076] 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 the same air gap length is arranged between the rotor unit and the stator unit.

[0077] As a specific example, insulating paper is wrapped between the winding and the core to ensure insulation safety.

[0078] 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.

[0079] 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.

[0080] As a specific example, the number of the 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 shaft in a radially parallel state to the slots of the excitation winding; the heat pipes are independent of each other and do not cross-interfere with each other, and even if some of them are damaged during operation, it will not affect the operation of other heat pipes.

[0081] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0082] Example 1

[0083] Combination Figure 1a , Figure 1b , Figure 2a, Figure 2b The present invention discloses a rotor cooling structure of 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 glue 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;

[0084] 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 that the heat generated by the rotor core 3 and the excitation winding 5 is transferred to the cooling oil in the hollow shaft 7, and then the cooling oil is circulated and cooled through the oil cooling component; a back aluminum 2 is arranged on the outside of the rotor core 3, and an end cover 1 is arranged on the outside of the back aluminum 2; a potting glue 6 is poured between the rotor core 3 and the motor stator.

[0085] As a specific example, the rotor core 3 is formed by circumferentially winding thin silicon steel sheets, and is varnished and cured to ensure a good magnetic flux conduction effect. The rotor core 3 includes a rotor yoke and rotor teeth, and the rotor teeth are evenly distributed on the axial end surface of the rotor yoke along the circumference of the axis.

[0086] 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 place the heat pipe.

[0087] 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.

[0088] As a specific example, the surface of the heat pipe 4 is passivated, spray-painted with insulation or coated with epoxy resin to ensure insulation safety between the heat pipe 4 and the rotor.

[0089] 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;

[0090] The tube shell 4-1 is made of a copper metal tube, and a wire mesh capillary core 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 being affected by the change of 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 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.

[0091] 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.

[0092] 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 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.

[0093] As a specific example, the back aluminum 2 wraps around the rotor core 3 to support the rotor.

[0094] As a specific example, the end cover 1 is made of aluminum alloy, which is light in weight and has good thermal conductivity.

[0095] Figure 4a to Figure 4c The schematic diagram of the heat pipe installation position of the axial flux motor rotor cooling structure of the present invention is shown in FIG. Figure 4a It is a schematic diagram of the rotor structure of an electrically excited axial flux motor without a heat pipe, in which the excitation winding 5 is wound around the teeth of the rotor core 3 in the circumferential direction. Figure 4b It is a schematic diagram of the rotor structure of an electrically excited axial flux motor with a heat pipe. The heat pipe is evenly arranged along the axial circumference, the evaporation end is radially inserted into the groove 3 of the rotor core, and the condensation end is radially inserted into the through hole 7-3 of the hollow shaft 7. Figure 4c It is a schematic diagram of the rotor structure of an axial flux permanent magnet motor with a heat pipe. The heat pipe 4 is evenly arranged along the axial circumference and embedded in the groove of the rotor core 3. The heat pipe 4 is in close contact with the rotor core 3 and the permanent magnet 8, and the heat on the rotor side is quickly transferred to the cooling medium inside the hollow shaft 7, which effectively reduces the temperature on the rotor side and avoids the risk of high-temperature demagnetization of the permanent magnet 8.

[0096] Figure 6 The heat transfer path diagram of the rotor cooling structure of the electrically excited axial flux motor in the present invention is as follows: the heat pipe 4 does not absorb heat directly, 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.

[0097] The present invention uses heat pipe heat transfer and hollow shaft oil cooling to cool the rotor. Since the heat pipe has excellent thermal conductivity, the heat generated by the rotor can be quickly transferred to the shaft. A cavity is provided inside the hollow shaft 7. When the cooling oil is injected into the cavity, it contacts the hollow shaft 7 and the heat pipe 4, and most of the heat generated by the rotor is quickly taken away by convection heat transfer, which greatly improves the heat dissipation efficiency. Inserting the heat pipe 4 in the rotor slot helps to transfer heat from the high temperature area of ​​the rotor to the evaporation end of the heat pipe, reduce the gradient of the rotor temperature, make the heat more evenly distributed on the rotor, and extend the service life of the rotor.

[0098] Example 2

[0099] 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, such as Figure 1a As 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, matching the groove type of the rotor core 3. The liquid working medium 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 can be achieved through the gas-liquid phase change of water; 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 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 the opposite direction; 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 fully absorbed, thereby extending the heat exchange time, balancing the temperature distribution, and avoiding 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.

[0100] Figure 3a Schematic diagram of the cross-section of the shaft of this embodiment, the two ends of the hollow shaft 7 are respectively the hollow shaft opening end 7-1 and the hollow shaft closed end 7-2, and 12 through holes 7-3 are respectively opened on both sides of the hollow shaft 7 along the circumferential direction of the axis to place the heat pipe.

[0101] When the system is running, the rotor core 3 and the excitation winding 5 generate heat loss, and the heat is transferred to the heat pipe 4 in the rotor slot. The evaporation end 4-4 of the heat pipe 4 absorbs heat, causing the liquid water in the steam chamber 4-3 to evaporate. Under the action of the pressure difference, the water vapor flows to the condensation end 4-5 and releases latent heat. Since the heat pipe 4 is embedded in the hollow shaft 7, part of the heat of the heat pipe condensation end 4-5 is transferred to the hollow shaft 7. At the same time, the cooling oil is pumped into the oil guide pipe 11 by the oil pump 13 through the oil pipe 14. Under the action of centrifugal force and oil pressure, the cooling oil flows to the closed end 7-2 of the hollow shaft 7, the flow is blocked, and the cooling oil is redirected. The cooling oil flows to the open end 7-1 of the hollow shaft 7, and during the flow, it takes away the heat conducted by the rotor on the hollow shaft 7 and the heat pipe condensation end 4-5, flows into the cooling oil collector 15, and finally flows back to the oil tank 12 through the oil pipe 14, forming a circulation process.

[0102] Example 3

[0103] 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 located 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 cooling fins to increase the convection heat exchange area and improve the heat dissipation efficiency. The cooling fins are rectangular and cast together with the hollow shaft 7. The cooling fins are a three-section structure, and space is reserved for the installation of heat pipes 4 on both sides. In this scheme, 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 fluid 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.

[0104] 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.

[0105] Figure 1bThis is a schematic diagram of the overall cooling structure of this embodiment. When the system is running, the cooling oil is pumped into the oil inlet of the hollow shaft 7 by the oil pump 13 through the oil pipe 14. Under the action of centrifugal force and oil pressure, the cooling oil flows to the outlet side, fully contacts the inner wall of the hollow shaft 7 and the heat pipe condensation end 4-5, 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.

[0106] 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 basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary 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 falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

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 glue (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 install the heat pipe (4); the evaporation end (4-4) of the heat pipe (4) is correspondingly installed 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, and a wire mesh capillary wick (4-2) is 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 the change of the position of the heat pipe (4); both ends of the tube shell (4-1) are sealed, the tube is evacuated, and the working liquid is injected; 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 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 shaft (7), and 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); 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, extending into the interior of the hollow rotating shaft (7) to transport cooling oil, and the oil guide pipe (11) and the inner wall of the hollow rotating shaft (7) and the condensation end (4-5) of the heat pipe (4) are independent of each other and do 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) delivers 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 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 shaft (7), the flow velocity 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. After the cooling oil flows back to the oil tank (12), it 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 component are located on different sides of the hollow shaft, and the oil cooling component comprises 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 heat transfer; 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), takes away the heat conducted from the rotor side, and finally 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 groove 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 are 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 of the rotor core (3), and the radial length of the evaporation end (4-4) is consistent with that of the excitation winding (5), so as to achieve 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, and a plurality of through holes (7-3) are evenly arranged on the hollow rotating shaft (7) along the axial direction of the circumference, 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 enable the rotor to fully contact with the heat pipe (4) and dissipate heat; the end cover (1) is made of aluminum alloy.

10. A method for assembling a rotor cooling structure of an electrically excited axial flux motor according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: Winding the excitation winding (5) circumferentially on the rotor core (3) by means of a tool, leaving a gap between the excitation winding (5) and the slot of the rotor core (3), and the size of the reserved gap is larger than the size of the heat pipe (4); Step 2, processing the hollow shaft (7), evenly arranging a plurality of through holes (7-3) along the axial direction, and the hole diameters match the size of the heat pipe (4); Step 3, installing 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 state of being radially parallel to the slot of the excitation winding (5), and inserting the condensation end (4-5) into the through hole (7-3) of the hollow shaft (7); Step 4: Install the aluminum back (2) and the end cover (1), and use the potting glue (6) to seal the end face of the entire rotor assembly, thereby forming a complete and sealed rotor structure; Step 5: Arrange an oil cooling assembly. 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). The oil cooling assembly circulates and cools the cooling oil.

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