Hybrid cooling structure of multi-torque component axial flux motor and axial flux motor

Abstract

The application discloses a hybrid cooling structure of a multi-torque component axial flux motor and the axial flux motor, and belongs to the technical field of axial flux motors. The hybrid cooling structure comprises a casing liquid cooling structure, an in-slot cooling structure and a heat conduction structure. The casing liquid cooling structure comprises a cooling flow channel arranged in a casing. The cooling flow channel has a cooling flow channel inlet and a cooling flow channel outlet. The in-slot cooling structure comprises first and second heat conduction sheets embedded in a stator slot. The first heat conduction sheet is arranged between a first permanent magnet and a stator winding and is in contact with both. The second heat conduction sheet is located between a second stator permanent magnet and the stator winding and is in contact with both. One end of the first and second heat conduction sheets is in contact with a stator core, and the other end extends into the casing. The heat conduction structure comprises a heat conduction ring located between the casing and the casing. The application improves the heat dissipation capacity and avoids excessive temperature rise of the motor stator and rotor cores and the motor stator and rotor permanent magnets.

Description

Technical Field

[0001] This invention belongs to the field of axial flux motor technology, specifically relating to a hybrid cooling structure for a multi-torque component axial flux motor and the axial flux motor itself. Background Technology

[0002] The aviation industry accounts for 2% to 3% of global greenhouse gas emissions, and this proportion has been rising in recent years, making it one of the major sources of global greenhouse gas emissions. With the deepening of energy conservation and emission reduction efforts, electrification, represented by multi-electric / all-electric technologies, has become the mainstream trend in the aviation field.

[0003] As a key technology in aerospace propulsion systems, electric motors require higher performance than conventional motors. Limited installation space necessitates lighter weight, smaller size, and higher torque density. Against this backdrop, axial flux motors, with their high performance specifications, have emerged. Compared to radial flux motors, axial flux motors offer advantages such as smaller size, higher efficiency, and greater power and torque density, making them more suitable for aerospace propulsion. Currently, competitive axial flux motors in aerospace propulsion are primarily based on the YASA structure. However, this structure has two rotor disks, generating only two torque components. Achieving higher torque requires a larger current, which leads to higher stator winding losses, higher winding temperature rise, and increased costs for controller power devices.

[0004] Currently, to address the aforementioned shortcomings, a multi-torque component axial flux motor (CN115733322A axial flux single-tooth winding concentrated winding multi-torque dual-rotor low-speed direct-drive generator [ZH]) has been proposed in existing patents. Permanent magnets are arranged on both the stator and rotor, with the stator permanent magnets positioned at the slots on both sides of the stator core. This motor combines the magnetic field modulation principle with the symmetrical structure of the dual-rotor, dual-air-gap axial motor to generate four torque components. The total torque is a linear superposition of these four torque components, effectively reducing current while maintaining the same output torque, thereby reducing winding temperature rise and power device costs. However, compared to the YASA motor, the sources of loss in this motor are more complex. In addition to the existing stator winding copper loss, stator iron loss, rotor iron loss, and rotor permanent magnet eddy current loss, stator permanent magnet eddy current loss is added. Simultaneously, due to the magnetic field modulation effect, there are more harmonics in the air-gap magnetic field, increasing stator and rotor iron losses and rotor permanent magnet eddy current losses. As can be seen from Table 1, the loss distribution of this motor is completely different from that of a conventional YASA motor. The proportion of stator and rotor iron loss and rotor permanent magnet eddy current loss both exceed that of winding copper loss. The sum of the three types of losses accounts for 80.6% of the total loss, which makes it difficult for the overall heat dissipation of the motor. This leads to excessive temperature rise of the stator and rotor cores and stator and rotor permanent magnets, which can cause permanent demagnetization of the stator and rotor permanent magnets and affect the stable operation of the motor.

[0005] In summary, there is an urgent need for a cooling structure suitable for axial flux motors with multiple torque components.

[0006] Table 1. Loss Distribution of Multi-Torque Component Axial Flux Motor

[0007] Summary of the Invention

[0008] This invention provides a hybrid cooling structure for a multi-torque component axial flux motor and an axial flux motor, which improves heat dissipation capacity and avoids excessive temperature rise of the motor stator and rotor cores and stator and rotor permanent magnets.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A hybrid cooling structure for a multi-torque component axial flux motor includes a housing liquid cooling structure, an in-slot cooling structure, and a heat-conducting structure.

[0011] The liquid cooling structure of the casing includes a cooling channel disposed inside the casing, the cooling channel having a cooling channel inlet and a cooling channel outlet;

[0012] The in-slot cooling structure includes a first heat-conducting plate and a second heat-conducting plate embedded in the stator slot. The first heat-conducting plate is disposed between the first permanent magnet and the stator winding and is in contact with both. The second heat-conducting plate is located between the second stator permanent magnet and the stator winding and is in contact with both. One end of the first heat-conducting plate and the second heat-conducting plate is in contact with the stator core, and the other end extends into the housing.

[0013] The heat-conducting structure includes a heat-conducting ring located between the stator core and the housing.

[0014] Furthermore, it also includes an end cap air-cooling structure, which includes a first end cap ventilation hole and a second end cap ventilation hole respectively opened on the first end cap and the second end cap, as well as a heat-conducting ring ventilation hole opened on the heat-conducting ring, wherein the first end cap ventilation hole, the second end cap ventilation hole and the heat-conducting ring ventilation hole form an axial air duct.

[0015] Furthermore, it also includes a self-circulating hollow shaft cooling structure, which includes a flow channel inlet, a first outlet, and a second outlet; the flow channel inlet is connected to the inner cavity of the shaft through a pipe to form a cooling medium inflow channel, and a cooling medium outflow channel is formed between the pipe and the inner wall of the inner cavity; the first outlet and the second outlet are both connected to the cooling medium outflow channel.

[0016] Furthermore, the flow channel inlet, the first outlet, and the second outlet are located on the same side of the rotating shaft.

[0017] Furthermore, the material of the pipe is copper, aluminum, or stainless steel.

[0018] Furthermore, the cooling channel is either circumferentially spiral or axially Z-shaped.

[0019] Furthermore, the second heat-conducting sheet and the first heat-conducting sheet are symmetrical about the central plane of the stator axis.

[0020] Furthermore, the thermal conductivity of the first and second heat-conducting sheets is greater than that of the heat-conducting ring.

[0021] Furthermore, the heat-conducting ring is made of epoxy resin.

[0022] A multi-torque component axial flux motor includes the hybrid cooling structure of the multi-torque component axial flux motor described above.

[0023] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0024] The hybrid cooling structure of the present invention improves upon existing cooling structures by employing casing liquid cooling, stator slot cooling, epoxy resin cooling, and end cover air cooling on the stator.

[0025] Among them, the casing liquid cooling involves arranging cooling channels inside the casing and passing coolant into the channels to cool the casing. Casing liquid cooling has a direct cooling effect on the heat-conducting fins and epoxy resin.

[0026] The stator slot cooling method involves arranging heat-conducting plates within the stator slots to enhance heat conduction. These plates are located between the stator windings and the stator permanent magnets. One axial surface of the plate contacts the stator winding surface, another axial surface contacts the stator permanent magnet surface, and the circumferential surface contacts the stator core. This allows for the simultaneous dissipation of heat generated by the stator windings, stator permanent magnets, and stator core. One end of the heat-conducting plate is positioned at the inner diameter of the stator, while the other end is embedded in the housing for cooling via liquid cooling of the housing. Furthermore, due to the air gap between the stator and the housing, epoxy resin is filled between them to further enhance heat conduction. This epoxy resin encapsulates the stator, stator windings, and stator permanent magnets, guiding the heat generated by these components into the housing for liquid cooling. Additionally, some of the heat-conducting plates within the stator slots are embedded in the epoxy resin. Because of the high thermal conductivity of the heat-conducting plates, the epoxy resin also transfers heat to the plates and then to the housing.

[0027] The rotor section employs self-circulating hollow shaft cooling and end-cover air cooling. The self-circulating hollow shaft cooling structure features a cooling channel inlet and outlet on the same side, forming a "one-in, two-out" structure, which can cool the rotor core and permanent magnets near the shaft. This facilitates the placement of the coolant storage tank, and the two outlets also increase the efficiency of coolant circulation. The end-cover air cooling structure involves ventilation holes in the end covers and epoxy resin on both sides of the motor, forming axial cooling air channels. This directly cools the outer diameter rotor and permanent magnets, as well as the epoxy resin itself, and indirectly cools the heat-conducting fins within the cooling slots.

[0028] This invention employs a hybrid cooling structure for a multi-torque component motor, with coupling relationships between the various cooling structures to form parallel heat transfer paths and cooling methods, resulting in a higher effect than the individual superposition of each cooling structure. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the heat transfer and cooling methods of various components in a multi-torque component axial flux motor.

[0030] Figure 2 This is an exploded view of a multi-torque component axial flux motor and its hybrid cooling structure.

[0031] Figure 3 This is a 1 / 4 cross-sectional view of a multi-torque component axial flux motor and its hybrid cooling structure.

[0032] Figure 4 This is a schematic diagram of the liquid-cooled structure of the stator housing of a multi-torque component axial flux motor;

[0033] Figure 5 This is a schematic diagram of the cooling structure inside the stator slot of a multi-torque component axial flux motor.

[0034] Figure 6 This is a schematic diagram of the epoxy resin cooling structure of the stator of a multi-torque component axial flux motor.

[0035] Figure 7 This is a schematic diagram of a self-circulating hollow shaft cooling structure for a multi-torque component axial flux motor rotor.

[0036] Figure 8 This is a 1 / 4 cross-sectional view of the shaft of a multi-torque component axial flux motor;

[0037] Figure 9 This is a schematic diagram of the cooling medium flow in a self-circulating hollow shaft cooling system;

[0038] Figure 10 This is a schematic diagram of the air-cooled end cover structure of a multi-torque component axial flux motor.

[0039] Figure 11This is a schematic diagram of the heat transfer direction of the rotor section of a multi-torque component axial flux motor.

[0040] Wherein: 100 is the stator core, 101 is the first stator permanent magnet, 102 is the second stator permanent magnet, 103 is the first heat-conducting plate, 104 is the second heat-conducting plate, 105 is the stator winding, 106 is epoxy resin, and 107 is epoxy resin axial ventilation hole; 200 is the first rotor core, 201 is the second rotor core, 202 is the first rotor permanent magnet, 203 is the second rotor permanent magnet, 204 is the first non-magnetic adhesive, 205 is the second non-magnetic adhesive, 206 is the first rotor weight reduction hole, and 207 is the second... Rotor weight reduction hole; 300 is the housing, 301 is the stator bearing, 302 is the inlet of the housing liquid cooling channel, 303 is the outlet of the housing liquid cooling channel, 304 is the cooling channel; 400 is the first end cover, 401 is the second end cover, 402 is the first end cover bearing, 403 is the second end cover bearing, 404 is the first end cover ventilation hole, 405 is the second end cover ventilation hole; 500 is the seal, 501 is the shaft, 502 is the pipe, 503 is the inlet of the hollow shaft channel, 504 is the first outlet of the channel, 505 is the second outlet of the channel. Detailed Implementation

[0041] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0042] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0043] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or may be interposed with another element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or may be interposed with another element. The terms "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," and "outer," etc., used herein to indicate orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0045] Example 1

[0046] refer to Figures 1 to 11 The hybrid cooling structure of a multi-torque component axial flux motor proposed in this invention is mainly divided into a stator cooling structure, a rotor cooling structure, and a shared cooling structure for the stator and rotor.

[0047] For the stator section of the motor, the main heat sources are the stator winding 105, the first stator permanent magnet 101, the second stator permanent magnet 102, and the stator core 100. The stator section is equipped with casing liquid cooling, in-slot cooling, and epoxy resin cooling.

[0048] The casing liquid cooling system comprises a cooling channel 304 arranged inside the casing 300. The cooling channel 304 includes, but is not limited to, circumferential spiral and axial Z-shaped types. Coolant is introduced into the cooling channel inlet 302 and flows out from the channel outlet 303 to cool the casing 300. The coolant includes, but is not limited to, water and oil.

[0049] In-slot cooling involves embedding a first heat-conducting plate 103 and a second heat-conducting plate 104 within the stator slots. One axial surface of the first heat-conducting plate 103 contacts the first permanent magnet 101, and the other surface contacts the stator winding 105, while the circumferential surface contacts the stator core 100. Simultaneously, one end of the first heat-conducting plate 103 is located at the inner diameter of the stator, contacting the stator bearing 301, while the other end is embedded within the stator housing 300. The second heat-conducting plate 104 is symmetrically positioned to the first heat-conducting plate 103 about the stator's axial center plane, located between the second stator permanent magnet 102 and the stator winding 105. Its axial surfaces contact both magnets, its circumferential surface contacts the stator core 100, and its other end is embedded within the stator housing 300. The first heat-conducting plate 103 and the second heat-conducting plate 104 can conduct the heat of the first stator permanent magnet 101, the second stator permanent magnet 102, the stator winding 105, and the stator core 100 into the housing 300, and cool it by means of the cooling channel 304 using the housing liquid cooling method.

[0050] The aforementioned first heat-conducting sheet 103 and second heat-conducting sheet 104 include, but are not limited to, high thermal conductivity materials such as copper sheets, aluminum sheets, and heat pipes.

[0051] Epoxy resin cooling involves filling a heat-conducting ring between the stator core 100 and the housing 300. The heat-conducting ring is made of high thermal conductivity epoxy resin 106, which encapsulates the stator heating components, including the stator winding 105, the first stator permanent magnet 101, the second stator permanent magnet 102, and the stator core 100. This allows the heat generated by these components to be transferred to the housing 300, where it is cooled by liquid cooling. Simultaneously, the epoxy resin 106 encapsulates a portion of the first heat-conducting sheet 103 and the second heat-conducting sheet 104, forming a heat transfer path. Because the heat-conducting sheet has a higher thermal conductivity than the epoxy resin, the epoxy resin 106 can also conduct heat generated by the four heat sources to the first heat-conducting sheet 103 and the second heat-conducting sheet 104, and then to the housing.

[0052] For the rotor section, the heat sources are mainly the first rotor core 200, the first rotor permanent magnet 202, the second rotor core 201, and the second rotor permanent magnet 203. The first rotor permanent magnet 203 and the first rotor core 200 are fixed together by a first non-magnetic adhesive 204, and the second rotor core 201 and the second rotor permanent magnet 203 are fixed together by a second non-magnetic adhesive 205. The first rotor core 200 has several circumferentially arranged first rotor weight-reducing holes 206. The second rotor core 201 has several circumferentially arranged second rotor weight-reducing holes 207.

[0053] Reference Figure 8 and Figure 9 The rotor section primarily employs a self-circulating hollow shaft cooling method. The cooling medium can be any liquid with strong cooling capacity, including but not limited to water and oil. The self-circulating hollow shaft cooling system involves placing the hollow shaft inlet 503, the first outlet 504, and the second outlet 505 on the same side of the rotating shaft 501, forming a single-sided "one inlet, two outlets" structure. The inlet 503 is one end of a pipe 502 mechanically coupled to a seal 500. The other end of the pipe 502 is inserted into the cavity inside the rotating shaft 501, forming a cooling medium inflow channel. A cooling medium outflow channel is formed between the pipe 502 and the inner wall of the cavity. The cooling medium flows into the rotating shaft 501, cooling it, and then flows from the cooling medium outflow channel to the first outlet 504 and the second outlet 505. The cooling medium cools the rotating shaft 501 during its flow within the shaft. The rotating shaft 501 has a cavity portion and a solid portion; see details below. Figure 8 A 1 / 4 cross-sectional view of the rotating shaft 501. The materials of the pipe 502 include, but are not limited to, copper, aluminum, and stainless steel. The seal 500 is located between the first end cover 400 and the first rotor core 200, and is tightly attached to the first end cover 400 and the first rotor core 200 on both sides, serving a sealing function to prevent the cooling medium from flowing out from any position other than the first outlet 504 and the second outlet 505 of the flow channel.

[0054] Reference Figure 10 The end-cover air-cooling system is a shared cooling structure for both the stator and rotor, allowing simultaneous cooling of both components. Specifically, it features a first end-cover ventilation hole 404 on the first end-cover 400, a second end-cover ventilation hole 405 on the second end-cover 401, and epoxy resin ventilation holes 107 on the epoxy resin 106, forming an axial airflow channel. Axial airflow through the epoxy resin ventilation holes 107 directly carries away the accumulated heat in the epoxy resin 106, providing direct cooling. Simultaneously, the first end-cover ventilation hole 404 and the second end-cover ventilation hole 405 indirectly cool the first heat-conducting plate 103 and the second heat-conducting plate 104.

[0055] Depend on Figure 11 As shown in the diagram, the heat flow of the rotor section indicates that on the inner diameter side of the rotor, the heat from the first rotor core 200, the first rotor permanent magnet 202, the second rotor core 201, and the second rotor permanent magnet 203 mainly flows to the shaft 501, where it is cooled by a self-circulating hollow shaft liquid cooler. On the outer diameter side of the rotor, the heat from the first rotor core 200, the first rotor permanent magnet 202, the second rotor core 201, and the second rotor permanent magnet 203 dissipates into the air between the first rotor core 200 and the second rotor core 201 and the housing 300, where it is cooled by end cover air cooling.

[0056] Example 2

[0057] This embodiment provides a multi-torque component axial flux motor, including the hybrid cooling structure provided in Embodiment 1.

[0058] The term "constituting of" in describing a combination should include the identified elements, components, parts, or steps, as well as other elements, components, parts, or steps that do not substantially affect the essential novel features of the combination. The use of the terms "comprising" or "including" to describe combinations of elements, components, parts, or steps herein also contemplates embodiments that are essentially composed of such elements, components, parts, or steps. The use of the term "may" herein is intended to indicate that any described attribute included by "may" is optional.

[0059] Multiple elements, components, parts, or steps can be provided by a single integrated element, component, part, or step. Alternatively, a single integrated element, component, part, or step can be divided into multiple separate elements, components, parts, or steps. The use of "a" or "an" to describe an element, component, part, or step does not imply the exclusion of other elements, components, parts, or steps.

[0060] It should be understood that the above description is for illustrative purposes and not for limitation. Many embodiments and applications beyond the provided examples will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this teaching should not be determined by reference to the above description, but rather by reference to the foregoing claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the foregoing claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the applicant has not considered that subject matter as part of the disclosed inventive subject matter.

Claims

1. A hybrid cooling structure for a multi-torque component axial flux motor, characterized in that, This includes the casing liquid cooling structure, the in-tank cooling structure, and the heat conduction structure; The liquid cooling structure of the housing includes a cooling channel (304) disposed in the housing (300), the cooling channel (304) having a cooling channel inlet (302) and a cooling channel outlet (303). The in-slot cooling structure includes a first heat-conducting plate (103) and a second heat-conducting plate (104) embedded in the stator slot. The first heat-conducting plate (103) is disposed between the first permanent magnet (101) and the stator winding (105) and is in contact with both. The second heat-conducting plate (104) is located between the second stator permanent magnet (102) and the stator winding (105) and is in contact with both. One end of the first heat-conducting plate (103) and the second heat-conducting plate (104) is in contact with the stator core (100), and the other end extends into the housing (300). The heat-conducting structure includes a heat-conducting ring located between the stator core (100) and the housing (300), the heat-conducting ring being made of epoxy resin; the epoxy resin (106) encapsulates a portion of the first heat-conducting sheet (103) and the second heat-conducting sheet (104). It also includes an end cap air-cooling structure, which includes a first end cap ventilation hole (404) and a second end cap ventilation hole (405) respectively opened on the first end cap (400) and the second end cap (401), and a heat-conducting ring ventilation hole opened on the heat-conducting ring. The first end cap ventilation hole (404), the second end cap ventilation hole (405) and the heat-conducting ring ventilation hole form an axial air duct. It also includes a self-circulating hollow shaft cooling structure, which includes a flow channel inlet (503), a first outlet (504), and a second outlet (505); the flow channel inlet (503) is connected to the inner cavity of the shaft (501) through the pipe (502) to form a cooling medium inflow channel, and a cooling medium outflow channel is formed between the pipe (502) and the inner wall of the inner cavity; the first outlet (504) and the second outlet (505) are both connected to the cooling medium outflow channel.

2. The hybrid cooling structure for a multi-torque component axial flux motor according to claim 1, characterized in that, The flow channel inlet (503), the first outlet (504), and the second outlet (505) are located on the same side of the rotating shaft (501).

3. The hybrid cooling structure for a multi-torque component axial flux motor according to claim 1, characterized in that, The material of the pipe (502) is copper, aluminum or stainless steel.

4. The hybrid cooling structure for a multi-torque component axial flux motor according to claim 1, characterized in that, The cooling channel (304) is either circumferentially spiral or axially Z-shaped.

5. The hybrid cooling structure for a multi-torque component axial flux motor according to claim 1, characterized in that, The second heat-conducting plate (104) and the first heat-conducting plate (103) are symmetrical about the central plane of the stator axis.

6. The hybrid cooling structure for a multi-torque component axial flux motor according to claim 1, characterized in that, The thermal conductivity of the first heat-conducting sheet (103) and the second heat-conducting sheet (104) is greater than that of the heat-conducting ring.

7. A multi-torque component axial flux motor, characterized in that, The hybrid cooling structure includes the multi-torque component axial flux motor as described in any one of claims 1-6.

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