Phase change-liquid composite circulation cooling structure of axial magnetic flux motor

Abstract

The invention discloses an axial flux motor phase change-liquid composite circulation cooling structure, which belongs to the technical field of motors and comprises a motor shell, a stator, a rotor and a cooling structure integrated in an inner shell. The motor shell comprises an outer shell and an inner shell which are coaxially arranged, the outer shell is provided with an outer shell liquid inlet, an outer shell liquid outlet and a liquid collecting tank, and the liquid collecting tank is communicated with the outer shell liquid inlet to form an external liquid circulation loop; a plurality of I-shaped notches are formed in the inner shell; the cooling structure comprises an I-shaped heat pipe and a liquid flow channel; the I-shaped heat pipe is inserted into a stator winding reserved gap of the stator along the radial direction and is embedded with the I-shaped notch; the liquid flow channel is arranged in the circumferential direction of the inner shell. The cold end of the I-shaped heat pipe makes contact with the liquid flow channel, and composite cooling is achieved through phase change circulation and liquid circulation. The temperature rise peak value in the motor is remarkably reduced through the characteristics of the phase change material in the motor, heat is continuously and efficiently dissipated through the liquid cooling characteristic, and the heat dissipation efficiency and the motor reliability are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric machines, and particularly relates to a phase change-liquid composite circulation cooling structure of an axial flux motor. BACKGROUND

[0002] As a kind of electromagnetic energy conversion device with high power density and high efficiency characteristics, the axial flux motor has obvious advantages in new energy vehicles, aerospace and industrial servo applications due to its axial distribution of magnetic circuit design and compact overall structure. Compared with the traditional radial flux motor, the motor can realize higher torque output and better space utilization under the same volume condition.

[0003] However, this special structure not only brings excellent performance to the motor, but also faces a serious heat dissipation problem. Especially the close arrangement of its disc type restricts the heat dissipation path in the axial direction. When the motor is in high speed or heavy load working condition, the heat generated by the winding and the core part is difficult to be discharged in time. The resulting high internal temperature not only damages the performance of the insulation material, but also causes irreversible magnetic decay of the permanent magnet, thereby directly affecting the operation reliability and service life of the motor.

[0004] At present, the cooling methods used in engineering practice mainly include air cooling, liquid cooling and phase change cooling. Air cooling generally relies on external devices such as fans to drive air flow for heat exchange, but such a scheme often increases the volume of the whole machine, and is accompanied by noise and pollution sensitivity problems. Although liquid cooling has high heat transfer efficiency, it has leakage risks and medium compatibility challenges due to its high system complexity. The phase change cooling technology relies on the mechanism of absorbing a large amount of latent heat during the material state transition, which can effectively suppress temperature spikes in a short time, but its inherent heat dissipation persistence is poor, and it cannot meet the needs of long-term stable operation of the motor.

[0005] Therefore, the existing various cooling methods have not achieved a good balance between efficient heat dissipation and maintaining system compactness, and there is an urgent need for a composite cooling structure with rapid cooling and persistent heat dissipation capacity to meet the increasingly stringent heat dissipation requirements of modern high-performance axial flux motors. SUMMARY

[0006] The purpose of the present application is to provide a phase change-liquid composite circulation cooling structure of an axial flux motor to solve the above technical problems existing in the prior art.

[0007] To achieve the above object, the application provides the following scheme: an axial flux motor phase change-liquid composite cycle cooling structure, comprising a motor shell, a stator, a rotor and a cooling structure integrated in an inner shell; the stator comprises N non-connected yokeless stator teeth and a stator winding wound on the yokeless stator teeth; the motor shell comprises a coaxial outer shell and an inner shell, the outer shell is provided with an outer shell liquid inlet, an outer shell liquid outlet and a liquid collecting groove, the liquid collecting groove is communicated with the outer shell liquid inlet to form an external liquid circulation loop; a plurality of I-shaped grooves are formed on the inner shell; the cooling structure comprises an I-shaped heat pipe and a liquid flow channel; the I-shaped heat pipe is inserted into a reserved gap of the stator winding in a radial direction and is embedded with the I-shaped groove; the liquid flow channel is arranged in a circumferential direction of the inner shell; the cold end of the I-shaped heat pipe is wrapped by the wall surface of the liquid flow channel, and composite cooling is realized through phase change cycle and liquid cycle; the liquid flow channel is divided into two symmetrical annular flow channels at the flow channel liquid inlet and is finally converged at the flow channel liquid outlet.

[0008] Further, the I-shaped heat pipe is made of epoxy resin material and internally encapsulates liquid-gas phase change material.

[0009] Further, the I-shaped heat pipe comprises a transverse part and a longitudinal part, and the longitudinal part is arranged at both ends of the transverse part and is perpendicular to the transverse part.

[0010] Further, the part of the liquid flow channel between adjacent two I-shaped heat pipes is a continuous flow channel, one side of the transverse part of the I-shaped heat pipe is divided into two parts and respectively extends to the longitudinal part of the I-shaped heat pipe in an axial direction, and the other side of the transverse part converges and extends to the next I-shaped heat pipe in a circumferential direction.

[0011] Further, the gap between the I-shaped heat pipe, the liquid flow channel and the stator winding is filled with epoxy resin material.

[0012] Further, the number of the I-shaped grooves is the same as the number of the stator slots of the stator, and the center angle of adjacent grooves is 360° / N, wherein N is the number of the stator slots.

[0013] Further, all the gaps between the inner shell body of the inner shell and the stator winding are filled with epoxy resin material to form a continuous heat conduction bridge.

[0014] Further, the yokeless stator teeth of the stator are uniformly distributed in a circumferential direction, and the angle difference between adjacent two yokeless stator teeth is 360° / N.

[0015] Further, the stator winding and the front and rear tooth shoes of the yokeless stator tooth respectively leave spaces for the I-shaped heat pipe to enter, and the spaces for the I-shaped heat pipe to enter are also left between adjacent two stator windings.

[0016] Further, the collecting tank is communicated with the liquid inlet of the shell through a liquid pump and a filter.

[0017] Compared with the prior art, the present application at least discloses the following beneficial effects: The present application directly inserts the I-shaped heat pipe into the reserved gap of the stator winding and embeds it into the I-shaped notch of the inner shell, so that the hot end of the heat pipe can closely contact the high heat flux density area of the winding, thereby realizing rapid and direct heat transfer from the core heat source to the heat pipe. The heat pipe is internally encapsulated with liquid-gas phase change material, which can rapidly suppress the transient temperature rise peak during the operation of the motor by absorbing a large amount of latent heat through the phase change process. At the same time, the cold end of the heat pipe is wrapped by the liquid flow channel wall surface arranged in the circumferential direction of the inner shell, and the liquid flow channel adopts a design of being divided into two symmetrical annular flow channels at the liquid inlet and finally converging, so that the cooling liquid can surround each cold end of the heat pipe and form uniform and efficient forced convection heat exchange, continuously and stably leading the heat absorbed by the phase change to the external circulation loop. This close coupling structure of "deep into the heat source-phase change rapid heat absorption-liquid flow continuous heat dissipation" significantly shortens the heat transfer path and reduces the contact thermal resistance and overall thermal resistance, thereby synergistically improving the heat dissipation speed, continuity and uniformity in the limited axial space, and finally effectively reducing the internal working temperature of the motor and improving the heat dissipation efficiency and the reliability of long-term operation of the motor. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0019] Figure 1 Fig. 1 is a schematic diagram of the phase change cooling structure of the prior art axial disc type permanent magnet motor; Figure 2 Fig. 2 is a schematic diagram of the phase change-liquid composite circulation cooling structure of the axial flux motor provided by the embodiment of the present application; Figure 3 Fig. 3 is a schematic diagram of the overall structure of the cooling structure of the embodiment of the present application; Figure 4 Fig. 4 is a schematic diagram of the internal structure of the cooling structure of the embodiment of the present application; Figure 5 Fig. 5 is an axial view of the cooling structure of the embodiment of the present application after removing the outer shell and the inner shell; Figure 1 ; Figure 6 Fig. 6 is an axial view of the cooling structure of the embodiment of the present application after removing the outer shell and the inner shell; Figure 2 ; Figure 7 Fig. 7 is a schematic diagram of the structure of the inner shell in the cooling structure of the embodiment of the present application; Figure 8 Fig. 1 is a structural schematic diagram of a stator in a cooling structure according to an embodiment of the present application; Figure 9 Fig. 2 is a structural schematic diagram of an I-shaped heat pipe in a cooling structure according to an embodiment of the present application; Figure 10 Fig. 3 is a structural schematic diagram of a liquid flow channel in a cooling structure according to an embodiment of the present application.

[0020] In the figure: 100, exhaust hole; 200, rotating shaft; 1, motor shell; 10, shell; 11, shell body; 12, shell liquid inlet; 13, shell liquid outlet; 14, liquid collecting tank; 15, filter; 16, liquid pump; 17, motor shaft; 20, inner shell; 21, inner shell body; 22, I-shaped notch; 23, epoxy resin material; 3, stator; 31, stator tooth; 32, stator winding; 4, rotor; 41, rotor yoke; 42, permanent magnet; 5, cooling structure; 51, I-shaped heat pipe; 511, transverse part; 512, longitudinal part; 52, liquid flow channel; 53, flow channel liquid inlet; 54, flow channel liquid outlet. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0022] In the development process of high-power-density motors, axial flux motors have become a research hotspot due to their compact structure and high torque density. In order to pursue higher power density and efficiency, a stator yokeless structure is widely used, but this structure also introduces severe thermal management challenges. On the one hand, the tooth-shoe area has a significantly increased iron loss due to the high saturation of the magnetic flux density; on the other hand, the winding at the notch generates a large amount of eddy current loss under the skin effect and proximity effect, which together form a local overheating point around the tooth-shoe. More critically, after the stator yoke is removed, the heat dissipation path is significantly reduced, the heat transfer distance is increased, and the closely arranged winding in the slot seriously hinders the heat dissipation, resulting in heat accumulation in the slot, which not only restricts the continuous improvement of motor performance, but also accelerates the insulation aging and causes reliability problems. Existing cooling solutions often cannot effectively cool such special structures.

[0023] For example, the prior art with patent publication number CN119483113A proposes a phase change cooling method and structure for an axial disc-type permanent magnet motor, as shown in Figure 1As shown, the structure utilizes the kinetic energy generated by the rotation of the rotating shaft 200 to drive the airflow, so that the air is cooled by the phase change material inside the rotating shaft 200, then enters the air gap between the stator and the rotor, cools the surfaces of the two, and then is discharged from the exhaust hole 100 at the back of the rotor, thereby improving the cooling efficiency and reducing the cost. However, the airflow path inside the motor is relatively complex, and if the design is not proper, it may cause local airflow to be not smooth, affecting the uniformity of heat dissipation; in addition, this method relies on the rotation of the rotating shaft 200 to generate airflow, and when the motor speed is low, the airflow intensity may be insufficient, and the cooling efficiency will decrease, making it difficult to maintain high cooling efficiency for a long time.

[0024] For example, the prior art with patent publication number CN119787725A proposes a hybrid cooling structure for a multi-torque component axial flux motor and an axial flux motor. The heat-conducting sheet is attached to the surface of the permanent magnet and the stator core winding, and the heat-conducting sheet only contacts the surface of the component, which cannot penetrate into the winding gap, and it is difficult to effectively conduct the core heat accumulated in the slot; at the same time, its heat dissipation path is multi-section conduction, the path is long, the thermal resistance is large, and the efficiency is low. In addition, its cooling flow channel is a simple annular design, and the cooling medium flow is mostly in a laminar state, and the high heat flux density area is not optimized, the heat exchange efficiency is limited, and the overall design is not combined with the electromagnetic field distribution characteristics, and the cooling resources cannot be accurately placed, which may cause uneven cooling. Therefore, how to design a high-efficiency and compact cooling scheme for the yokeless axial flux motor, which can penetrate into the interior of the heat source, shorten the heat transfer path, and be optimized with electromagnetic design, has become a key technical problem to break through the power density and reliability bottleneck.

[0025] In view of the above technical problems existing in the current axial flux motor, the embodiment of the present application proposes an axial flux motor phase change-liquid composite circulation cooling structure and an axial flux motor comprising the structure. Through the combination of the direct contact of the I-shaped structure heat pipe with the winding and the cold end liquid cooling channel provided by the casing, the temperature rise peak of the axial flux motor can be effectively suppressed, and continuous and efficient heat dissipation can be realized, thereby significantly improving the stability of the motor operation.

[0026] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0027] Reference Figures 2 to 10 As shown, the present embodiment provides an axial flux motor phase change-liquid composite circulation cooling structure, which comprises a motor housing 1, a stator 3, a rotor 4, and a cooling structure 5 integrated in an inner shell 20. Overall, the cooling structure 5 realizes rapid heat absorption through the direct contact of the I-shaped heat pipe 51 with the stator winding 32, and combines the continuous transport of heat by the liquid flow channel 52 to form a set of efficient double-circulation heat dissipation system, which can significantly suppress the internal temperature rise of the motor under high-speed and high-load working conditions, and ensure long-term stable operation.

[0028] In the embodiment of the present application, as shown in Figures 2 to 6 The motor housing 1 constitutes the main support and protection structure of the motor, which includes a coaxial outer shell 10 and an inner shell 20. The motor shaft 17 penetrates the entire motor housing 1, connecting the rotor 4 and the external transmission system to realize power transmission. The outer shell 10 serves as the outermost protective structure, and the outer shell body 11 is a cavity structure. The top of the outer shell body 11 is provided with an outer shell liquid inlet 12, and the bottom is provided with an outer shell liquid outlet 13 and a recessed liquid collecting groove 14. The liquid collecting groove 14 stores cooling liquid, and the cooling liquid is driven to circulate by the liquid pump 16 located outside the outer shell 10. After being purified by the filter 15, the cooling liquid flows into the outer shell liquid inlet 12 and finally returns to the liquid collecting groove 14 through the outer shell liquid outlet 13, forming an external liquid circulation loop.

[0029] The liquid pump 16 and the filter 15 are installed outside the outer shell 10. The liquid pump 16 pumps the cooling liquid in the liquid collecting groove 14, which flows through the filter 15 to remove impurities, enters the motor housing 1 through the outer shell liquid inlet 12 to participate in the cooling cycle, and finally the cooling liquid after absorbing heat returns to the liquid collecting groove 14 through the outer shell liquid outlet 13, forming a stable external liquid circulation loop, which is responsible for finally bringing the heat accumulated in the motor to the external environment.

[0030] In the embodiment of the present application, the inner shell 20 is fixedly installed inside the outer shell 10 and serves as a key component for carrying the cooling structure 5. As shown in Figure 4 and 7 The main structure of the inner shell 20 is an annular inner shell body 21, which is uniformly provided with a plurality of I-shaped grooves 22 on its circumferential surface for radially inserting and fixing the I-shaped heat pipes 51. The center angle between adjacent I-shaped grooves 22 is 360° / N, where N is the number of stator slots. Further, the inner shell body 21 is embedded with a liquid flow channel 52, which is arranged along the circumference of the inner shell body 21 and branches into two symmetrical annular flow channels at the flow channel liquid inlet 53, and finally converges at the flow channel liquid outlet 54. In addition to the liquid flow channel 52 itself, all gaps between the inner shell body 21 and the stator winding 32 are filled with epoxy resin material 23 with high thermal conductivity to form a continuous thermal conduction bridge, which not only fixes the I-shaped heat pipes 51 and the stator winding 32, but also reduces the contact thermal resistance.

[0031] In one embodiment, the path of the liquid flow channel 52 is specially designed: the section between two adjacent U-shaped heat pipes 51 is a continuous flow channel; when the flow channel extends to the transverse section 511 of the U-shaped heat pipe 51, it is divided into two branches, which extend to and cover the longitudinal section 512, and then recombine at the other side of the transverse section 511 to continue to the next U-shaped heat pipe 51 along the circumference, thereby achieving comprehensive coverage and efficient heat exchange of the end (cold end) of the U-shaped heat pipe 51.

[0032] As shown in Figure 6 , Figure 10 The liquid flow channel 52 is a closed channel precisely machined inside the inner shell body 21 and arranged along the circumference of the motor. After the cooling liquid enters the flow channel inlet 53, it is immediately divided into two branches and flows in opposite directions (clockwise and counterclockwise), and finally converges at the symmetric position and flows out of the flow channel outlet 54.

[0033] The shape and path of the liquid flow channel 52 are highly matched with the cold end shape of the U-shaped heat pipe 51. When the flow channel extends to the transverse section 511 of the heat pipe, it is divided into two branches and covers the longitudinal section 512 along the axial direction. This bending structure is optimized by fluid mechanics, which can destroy laminar flow and enhance turbulent flow intensity without significantly increasing system pressure drop, thereby greatly improving the convective heat transfer coefficient of the fluid-solid interface. Combined with the symmetric double-channel split design, it ensures that the cooling liquid can quickly circulate and uniformly cover all the cold ends of the heat pipes, overcoming the defects of low heat exchange efficiency and mismatch with heat load distribution of traditional simple ring-shaped flow channels, and achieving the synergistic improvement of heat dissipation capacity and flow efficiency.

[0034] In the embodiment of the present application, as shown in Figure 5 The rotor 4 is the rotating part of the motor, including a rotor yoke 41 and a permanent magnet 42. The rotor yoke 41 and the permanent magnet 42 together form a magnetic pole unit of the rotor 4, which takes into account the integrity of the magnetic circuit, the reliability of the mechanical strength, and the efficiency of heat dissipation. The rotor 4 is connected to the motor shaft 17 by bolts or interference fit to realize effective power output.

[0035] In one embodiment, the rotor yoke 41 is usually made of soft magnetic material with high permeability (such as silicon steel sheet) and has a disc-shaped structure. Its function is to form part of the magnetic circuit, guide and concentrate the magnetic field, and provide a reliable mounting base for the permanent magnet 42. To further reduce weight and enhance heat dissipation capacity, the rotor yoke 41 can be designed with a hollow structure or an auxiliary air duct inside.

[0036] In one embodiment, the plurality of permanent magnets 42 are evenly attached or embedded along the circumferential direction of the rotor yoke 41. Specifically, the permanent magnets 42 can be arranged in a certain polarity pattern to form the required excitation magnetic field of the motor. In an axial flux motor, the permanent magnets 42 usually present a fan shape to adapt to the space constraints of the disc structure.

[0037] In the embodiment of the present application, as shown in Figure 6 and Figure 8 , the stator 3 adopts a yoke-free modular design, which is composed of N independent and circumferentially distributed yoke-free stator teeth 31 and stator windings 32 wound thereon. The included angle between the stator teeth 31 is also 360° / N.

[0038] In the embodiment of the present application, as shown in Figures 6 to 10 , the cooling structure 5 is mainly composed of an I-shaped heat pipe 51 and a liquid flow channel 52. The I-shaped heat pipe 51 is radially embedded in the I-shaped notch 22 of the inner shell 20, and its outer contour is in glue joint or interference fit with the I-shaped notch 22. The I-shaped heat pipe 51 and the liquid flow channel 52 are thermally connected in a "cold end-wall surface coupling" manner, the cold end of the I-shaped heat pipe 51 is wrapped by the wall surface of the liquid flow channel 52, and high thermal conductivity epoxy resin is used for adhesion in between, forming a wall surface coupling that only transmits heat but not mass, so as to realize the rapid transfer of phase change heat to the liquid cooling system.

[0039] In some embodiments, although the yoke-free structure improves the power density, it also brings serious heat dissipation challenges: the tooth-shoe area causes a sharp increase in iron loss due to magnetic flux saturation, and the slot winding generates a large amount of eddy current loss under the skin effect, which is easy to form local hot spots. The traditional cooling method is difficult to efficiently conduct heat into the winding gap. The present scheme is aimed at this special structure, which reserves a gap between the I-shaped heat pipe 51 and the stator winding 32, so that it can be radially inserted into the winding to directly contact the heat source, and at the same time the liquid flow channel 52 directly wraps the cold end of the heat pipe, perfectly matching the axial disc structure. Under the premise of not increasing the axial space, it realizes efficient heat dissipation from the internal core area, and solves the problem of less heat dissipation path and large thermal resistance of the traditional structure.

[0040] As shown in Figure 9 , the structure of the I-shaped heat pipe 51 is in the shape of an "I", which includes a transverse part 511 and longitudinal parts 512 vertically connected on both sides of the transverse part 511. Specifically, the longitudinal parts 512 are embedded in the tooth-shoe interior, which can efficiently conduct heat away from the tooth-shoe and slot area; the transverse part 511 is placed between adjacent windings, which can not only cool the heat accumulated in the slot winding, but also play a physical isolation role to reduce the risk of short circuit between windings. By integrating the heat pipe units at the tooth-shoe and in-slot winding, an I-shaped overall cooling unit, i.e. the I-shaped heat pipe 51, is formed. When local overheating occurs, the remaining part of the heat pipe can be used as a cooling cold end, which significantly improves the overall heat conduction capacity of the system.

[0041] To ensure the smooth implantation of the I-beam heat pipe 51, when the stator winding 32 is wound, a gap suitable for the shape of the I-beam heat pipe 51 is reserved in advance between the front and rear tooth shoes of the stator tooth 31 and the adjacent winding. This allows the I-beam heat pipe 51 to be inserted into the reserved gap in the radial direction and at the same time embedded in the I-beam notch 22 of the inner shell body 21 to form a close physical contact. The I-beam heat pipe 51 is arranged accordingly in the circumferential direction and inserted into the reserved space in the radial direction. At the same time, the end (cold end) of the I-beam heat pipe 51 is also radially embedded into the corresponding I-beam notch 22 opened on the inner shell body 21, thereby achieving its firm installation in the entire radial thickness direction of the motor.

[0042] The I-beam heat pipe 51 is not a simple uniform cooling element, but is designed based on electromagnetic field-temperature field coupling analysis. Its longitudinal part 512 is embedded in the tooth shoes on both sides of the stator tooth 31, and the transverse part 511 is inserted between the adjacent stator windings 32. This arrangement, through accurate calculation of winding loss distribution, directly positions the I-beam heat pipe 51 in the high heat flux density area where iron loss and copper loss are most concentrated, achieving precise deployment of cooling resources. This "magnetic-thermal fusion" design enables the I-beam heat pipe 51 to quickly absorb and transfer core heat, significantly reducing the risk of local overheating and improving heat dissipation efficiency.

[0043] In one embodiment, the I-beam heat pipe 51 itself is made of epoxy resin material, and internally encapsulates a liquid-gas phase change material. When the motor is working, the heat generated by the stator winding 32 is quickly conducted to the I-beam heat pipe 51, causing the internal phase change material to be heated and vaporized; the vapor flows to the cold end of the heat pipe (i.e. the end close to the liquid flow channel 52) under the action of pressure difference, releases heat to the cooling liquid in the flow channel through the epoxy resin material 23 at this place, and then condenses back to the hot end, completing a continuous phase change cycle.

[0044] In one embodiment, as shown in Figure 6 To ensure that heat can be transferred between the stator winding 32, the I-beam heat pipe 51 and the liquid flow channel 52 with extremely low thermal resistance, in this structure, the assembly gaps between all components, such as the small gaps between the I-beam heat pipe 51 and the stator winding 32, the I-beam heat pipe 51 and the I-beam notch 22, and the liquid flow channel 52 wall and the surrounding metal, are completely filled with epoxy resin material 23. This not only enhances the mechanical stability of the overall structure, but also greatly improves the thermal conductivity efficiency between components.

[0045] During operation, the cooling structure realizes a double thermal management mechanism: on the one hand, the I-shaped heat pipe 51 rapidly absorbs the peak heat of the winding area by using the latent heat of phase change, effectively suppressing the instantaneous temperature rise; on the other hand, the cooling liquid in the liquid flow channel 52 continuously flows under the driving of the liquid pump 16, absorbs the heat transferred from the cold end of the heat pipe and the epoxy resin filling layer along the way, and finally takes the accumulated heat energy to the outside of the motor for dissipation. This composite cooling strategy not only overcomes the disadvantage of poor sustainability of pure phase change cooling, but also avoids the slow response and easy leakage of the single liquid cooling system, thereby achieving efficient and durable heat dissipation performance in a limited space, and significantly improving the operation reliability and service life of the axial flux motor.

[0046] In summary, the structure realizes rapid heat absorption by the I-shaped heat pipe 51 deep into the winding, and cooperates with the highly coupled liquid flow channel 52 to continuously dissipate heat, forming an integrated double-circulation heat dissipation system. It not only physically shortens the heat transfer path from the heat source to the cooling medium, reduces the thermal resistance of multi-stage conduction, but also makes the cooling effect directly act on the electromagnetic hot spot through the layout of magnetic heat fusion. The I-shaped structure itself enables each heat pipe unit to form a multi-cold-end cooperative heat dissipation effect in the axial and circumferential directions, further improving the uniformity of heat diffusion and the overall heat conduction capacity. Therefore, the scheme effectively solves the problem of heat accumulation in the slot and local overheating of the toothed shoe of the yokeless axial flux motor due to the compact structure, and provides a key technical guarantee for the reliable operation of high-power density motors.

[0047] In the description of the present application, it should be understood that the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore cannot be understood as a limitation on the present application.

[0048] The above-described embodiments are only preferred modes of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those skilled in the art shall fall within the protection scope of the present application.

Claims

1. A phase change-liquid composite circulating cooling structure for an axial flux motor, characterized in that, Includes motor housing (1), stator (3), rotor (4) and cooling structure (5) integrated in inner shell (20); The stator (3) includes N unconnected unyoke stator teeth (31) and stator windings (32) wound on the unyoke stator teeth (31). The motor housing (1) includes an outer shell (10) and an inner shell (20) arranged coaxially. The outer shell (10) is provided with an outer shell liquid inlet (12), an outer shell liquid outlet (13) and a liquid collection tank (14). The liquid collection tank (14) is connected to the outer shell liquid inlet (12) to form an external liquid circulation loop. The inner shell (20) is provided with a plurality of I-shaped slots (22). The cooling structure (5) includes an I-shaped heat pipe (51) and a liquid flow channel (52); the I-shaped heat pipe (51) is inserted radially into the reserved gap of the stator winding (32) of the stator (3) and fits into the I-shaped slot (22); the liquid flow channel (52) is arranged circumferentially along the inner shell (20); the cold end of the I-shaped heat pipe (51) is wrapped by the wall of the liquid flow channel (52) and composite cooling is achieved through phase change cycle and liquid cycle; the liquid flow channel (52) splits into two symmetrical annular flow channels at the flow channel inlet (53) and finally merges at the flow channel outlet (54).

2. The axial flux motor phase change-liquid composite circulation cooling structure according to claim 1, characterized in that, The I-shaped heat pipe (51) is made of epoxy resin material (23) and is encapsulated with liquid-gas phase change material inside.

3. The axial flux motor phase change-liquid composite circulation cooling structure according to claim 1 or 2, characterized in that, The I-shaped heat pipe (51) includes a horizontal portion (511) and a vertical portion (512). The vertical portion (512) is located at both ends of the horizontal portion (511) and is perpendicular to the horizontal portion (511).

4. The axial flux motor phase change-liquid composite circulation cooling structure according to claim 3, characterized in that, The liquid flow channel (52) is a continuous flow channel between two adjacent I-shaped heat pipes (51). It is divided into two parts on one side of the transverse part (511) of the I-shaped heat pipe (51), and extends axially to the longitudinal part (512) of the I-shaped heat pipe (51), and merges on the other side of the transverse part (511) and extends circumferentially to the next I-shaped heat pipe (51).

5. The axial flux motor phase change-liquid composite circulation cooling structure according to claim 4, characterized in that, The gap between the I-shaped heat pipe (51), the liquid flow channel (52), and the stator winding (32) is filled with epoxy resin material (23).

6. The axial flux motor phase change-liquid composite circulation cooling structure according to claim 5, characterized in that, All gaps between the inner shell (21) of the inner shell (20) and the stator winding (32) are filled with epoxy resin material (23) to form a continuous thermal bridge.

7. The axial flux motor phase change-liquid composite circulation cooling structure according to claim 1, characterized in that, The number of I-shaped slots (22) is the same as the number of stator slots of the stator (3), and the included angle between the centers of adjacent slots is 360° / N, where N is the number of stator slots.

8. The axial flux motor phase change-liquid composite circulation cooling structure according to claim 7, characterized in that, The stator (3) has yokeless stator teeth (31) evenly distributed circumferentially, and the angle difference between two adjacent yokeless stator teeth (31) is 360° / N.

9. The axial flux motor phase change-liquid composite circulation cooling structure according to claim 8, characterized in that, The stator winding (32) and the front and rear teeth of the yokeless stator teeth (31) are respectively provided with space for the I-shaped heat pipe (51) to enter, and there is also space for the I-shaped heat pipe (51) to enter between two adjacent stator windings (32).

10. The axial flux motor phase change-liquid composite circulation cooling structure according to claim 1, characterized in that, The liquid collection tank (14) is connected to the liquid inlet (12) of the outer casing via a liquid pump (16) and a filter (15).

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