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

Abstract

The invention 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, and the cooling flow channel is provided with a cooling flow channel inlet and a cooling flow channel outlet. The in-slot cooling structure comprises a first heat-conducting fin and a second heat-conducting fin which are embedded into the stator slot, and the first heat-conducting fin is arranged between the first permanent magnet and the stator winding and is in contact with the first permanent magnet and the stator winding; the second heat-conducting fin is located between the second stator permanent magnet and the stator winding and makes contact with the second stator permanent magnet and the stator winding, one ends of the first heat-conducting fin and the second heat-conducting fin make contact with the stator iron core, and the other ends extend into the machine shell; the heat conduction structure comprises a heat conduction ring located between the machine shell and the machine shell. Heat dissipation capability is improved, and overhigh temperature rise of the stator and rotor iron cores and the stator and rotor permanent magnets of the motor is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of axial flux motors, and in particular relates to a hybrid cooling structure of a multi-torque component axial flux motor and an axial flux motor. Background Art

[0002] Greenhouse gas emissions from the aviation industry account for 2% to 3% of the world's total emissions, and the proportion has been rising in recent years, making it one of the important sources of global greenhouse gas emissions. With the continuous deepening of energy conservation and emission reduction, electrification represented by multi-electric / all-electric technology has become the mainstream trend of development in the aviation field.

[0003] As one of the key technologies of aviation propulsion systems, motors have higher performance requirements than conventional motors. Due to limited installation space, motors need to have lighter mass, smaller volume and higher torque density. In this context, axial flux motors with high performance indicators came into being. Compared with radial flux motors, axial flux motors have the advantages of smaller volume, higher efficiency, greater power density and torque density, and are more suitable for the field of aviation propulsion. At present, the axial flux motors that are competitive in the field of aviation propulsion are mainly based on the YASA structure. However, this motor structure has two rotor disks and can only generate two torque components. To obtain higher torque, a larger current needs to be passed. The larger current will cause large stator winding losses and higher winding temperature rise, and will also lead to an increase in the cost of controller power devices.

[0004] At present, in response to the above defects, 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, and the stator permanent magnets are arranged at the slots on both sides of the stator core. The motor combines the magnetic field modulation principle with the symmetrical structure of the axial motor's dual rotors and dual air gaps to generate four torque components. The total torque is the linear superposition of the four torque components. Under the condition of the same output torque, the current can be effectively reduced, thereby reducing the winding temperature rise and the cost of power devices. However, compared with the YASA motor, the loss source of this motor is more complicated. In addition to the original stator winding copper loss, stator iron loss, rotor iron loss and rotor permanent magnet eddy current loss, the stator permanent magnet eddy current loss is also added. At the same time, due to the magnetic field modulation effect, there are more air gap magnetic field harmonics, which increases the stator and rotor iron loss and the rotor permanent magnet eddy current loss. It can be seen from Table 1 that the loss distribution of this motor is completely different from that of the conventional YASA motor. The proportion of stator and rotor iron loss and rotor permanent magnet eddy current loss exceeds the winding copper loss. The sum of the three losses accounts for 80.6% of the total loss, which brings difficulties to the overall heat dissipation of the motor, and then causes the temperature rise of the motor stator and rotor core and stator and rotor permanent magnets to be too high, which will 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 a multi-torque component axial flux motor.

[0006] Table 1 Loss distribution of multi-torque component axial flux motor Summary of the invention

[0007] The present invention provides a hybrid cooling structure of a multi-torque component axial flux motor and an axial flux motor, which improves the heat dissipation capacity and avoids excessive temperature rise of the motor stator and rotor iron cores and the stator and rotor permanent magnets.

[0008] In order to achieve the above object, the present invention adopts the following technical solution: A hybrid cooling structure of a multi-torque component axial flux motor, comprising a housing liquid cooling structure, a slot cooling structure and a heat conduction structure; The casing liquid cooling structure comprises a cooling channel arranged in the casing, wherein the cooling channel has a cooling channel inlet and a cooling channel outlet; The slot cooling structure comprises a first heat conducting sheet and a second heat conducting sheet embedded in the stator slot, wherein the first heat conducting sheet is arranged between the first permanent magnet and the stator winding and contacts the first permanent magnet and the stator winding; the second heat conducting sheet is arranged between the second stator permanent magnet and the stator winding and contacts the second permanent magnet and the stator winding, wherein one end of the first heat conducting sheet and the second heat conducting sheet contacts the stator core and the other end extends into the casing; The heat-conducting structure comprises a heat-conducting ring located between the stator core and the casing.

[0009] Furthermore, it also includes an end cover air cooling structure, which includes a first end cover ventilation hole and a second end cover ventilation hole respectively opened on the first end cover and the second end cover, and a heat conductive ring ventilation hole opened on the heat conductive ring, and the first end cover ventilation hole, the second end cover ventilation hole and the heat conductive ring ventilation hole form an axial air duct.

[0010] 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 rotating shaft through a pipeline to form a cooling medium inlet channel, and a cooling medium outflow channel is formed between the pipeline and the inner wall of the inner cavity; the first outlet and the second outlet are both connected to the cooling medium outflow channel.

[0011] Furthermore, the flow channel inlet, the first outlet and the second outlet are arranged on the same side of the rotating shaft.

[0012] Furthermore, the material of the pipeline is copper, aluminum or stainless steel.

[0013] Furthermore, the cooling channel is of a circumferential spiral type or an axial Z-type.

[0014] Furthermore, the second heat conducting plate and the first heat conducting plate are symmetrically structured with respect to the axial center plane of the stator.

[0015] Furthermore, the thermal conductivity of the first heat conducting sheet and the second heat conducting sheet is greater than the thermal conductivity of the heat conducting ring.

[0016] Furthermore, the heat-conducting ring is made of epoxy resin.

[0017] A multi-torque component axial flux motor comprises the hybrid cooling structure of the multi-torque component axial flux motor.

[0018] Compared with the prior art, the present invention has at least the following beneficial technical effects: The hybrid cooling structure of the present invention improves the existing cooling structure and adopts casing liquid cooling, stator slot cooling, epoxy resin cooling and end cover air cooling on the stator.

[0019] Among them, the casing liquid cooling is to arrange cooling channels inside the casing, and pass the coolant into the channels to cool the casing. The casing liquid cooling has a direct cooling effect on the heat conducting plate and the epoxy resin.

[0020] The cooling method in the stator slot is to arrange a heat-conducting sheet in the stator slot to enhance the heat conduction effect. The heat-conducting sheet is located between the stator winding and the stator permanent magnet. One axial surface of the heat-conducting sheet contacts the surface of the stator winding, the other axial surface contacts the surface of the stator permanent magnet, and the circumferential surface contacts the stator core. The heat generated by the stator winding, the stator permanent magnet and the stator core can be simultaneously conducted out. One end of the heat-conducting sheet is arranged at the inner diameter of the stator, and the other end is embedded in the casing, and it is cooled by the casing liquid cooling. At the same time, since there is air between the stator and the casing, in order to further enhance the heat conduction, epoxy resin is filled between the stator and the casing. The epoxy resin wraps the stator, the stator winding and the stator permanent magnet, and the heat generated by the three can be conducted into the casing and cooled by the casing liquid cooling. At the same time, the heat-conducting sheet in the stator slot is also partially embedded in the epoxy resin. Since the thermal conductivity of the heat-conducting sheet is high, the epoxy resin can also transfer the heat to the heat-conducting sheet and then to the casing.

[0021] The rotor part adopts self-circulating hollow shaft cooling and end cover air cooling. The self-circulating hollow shaft cooling structure has the cooling channel inlet and outlet on the same side, forming a "one-in, two-out" structure, which can cool the rotor core and rotor permanent magnets close to the shaft. It is convenient to arrange the coolant storage box, and the two outlets also increase the efficiency of coolant circulation. The end cover air cooling structure is to open ventilation holes on the end covers and epoxy resin on both sides of the motor to form an axial cooling air duct, which can directly cool the outer diameter side rotor and rotor permanent magnets, and also directly cool the epoxy resin, and indirectly cool the heat conducting plate in the slot.

[0022] The present invention adopts a mixed cooling structure of a multi-torque component motor, and a coupling relationship exists between the cooling structures to form a parallel heat transfer path and cooling method, which has a higher effect than the superposition of each cooling structure separately. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the heat transfer and cooling methods of various components of the multi-torque component axial flux motor; Figure 2 It is an exploded diagram of a multi-torque component axial flux motor and its hybrid cooling structure; Figure 3 It is a 1 / 4 cross-sectional view of a multi-torque component axial flux motor and its hybrid cooling structure; Figure 4 It is a schematic diagram of the liquid cooling structure of the stator housing of a multi-torque component axial flux motor; Figure 5 It is a schematic diagram of the cooling structure in the stator slot of a multi-torque component axial flux motor; Figure 6 It is a schematic diagram of the epoxy resin cooling structure of the stator of a multi-torque component axial flux motor; Figure 7 It is a schematic diagram of the self-circulating hollow shaft cooling structure of the rotor of a multi-torque component axial flux motor; Figure 8 It is a 1 / 4 cross-sectional view of the shaft of a multi-torque component axial flux motor; Fig. 9 It is a schematic diagram of the cooling medium flow in the self-circulating hollow shaft cooling method; Fig.10 It is a schematic diagram of the air-cooled structure of the end cover of a multi-torque component axial flux motor; Fig.11 It is a schematic diagram of the heat transfer direction of the rotor part of the multi-torque component axial flux motor.

[0024] 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 conductive sheet, 104 is the second heat conductive sheet, 105 is the stator winding, 106 is epoxy resin, and 107 is the 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, 207 is the second Rotor weight reduction hole; 300 is the casing, 301 is the stator bearing, 302 is the casing liquid cooling flow channel inlet, 303 is the casing liquid cooling flow channel outlet, 304 is the cooling flow 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 sealing element, 501 is the rotating shaft, 502 is the pipeline, 503 is the hollow shaft flow channel inlet, 504 is the flow channel first outlet, 505 is the flow channel second outlet. DETAILED DESCRIPTION

[0025] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings 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 should fall within the scope of protection of the present invention.

[0027] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be another element centered thereon. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be another element centered thereon at the same time. The terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc. used herein indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0029] Example 1 refer to Figures 1 to 11 The hybrid cooling structure of a multi-torque component axial flux motor proposed in the present invention is mainly divided into a stator part cooling structure, a rotor part cooling structure and a stator-rotor part shared cooling structure.

[0030] For the motor stator part, its heat sources are mainly the stator winding 105, the first stator permanent magnet 101, the second stator permanent magnet 102 and the stator core 100. The stator part is provided with casing liquid cooling, slot cooling and epoxy resin cooling.

[0031] The case liquid cooling is to arrange a cooling channel 304 inside the case 300, and the cooling channel 304 includes but is not limited to a circumferential spiral type, an axial Z-shaped type, etc. The cooling liquid is passed into the cooling channel inlet 302 and flows out from the channel outlet 303 to cool the case 300. The cooling liquid includes but is not limited to water, oil, etc.

[0032] The slot cooling is to embed the first heat conductive sheet 103 and the second heat conductive sheet 104 in the stator slot, wherein one surface of the first heat conductive sheet 103 in the axial direction is in contact with the first permanent magnet 101, the other surface is in contact with the stator winding 105, and the surface in the circumferential direction is in contact with the stator core 100. At the same time, one end of the first heat conductive sheet 103 is located at the inner diameter of the stator, in contact with the stator bearing 301, and the other end is embedded in the stator housing 300. The position of the second heat conductive sheet 104 is symmetrical with the first heat conductive sheet 103 about the axial center plane of the stator, and is located between the second stator permanent magnet 102 and the stator winding 105, and its axial two side surfaces are in contact with the two, the circumferential surface is in contact with the stator core 100, and the other end is embedded in the stator housing 300. The first heat conducting sheet 103 and the second heat conducting sheet 104 can introduce 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 the housing 300 by means of the cooling channel 304 using housing liquid cooling.

[0033] The first heat conducting sheet 103 and the second heat conducting sheet 104 include but are not limited to high thermal conductivity materials such as copper sheets, aluminum sheets and heat pipes.

[0034] Epoxy resin cooling is to fill a heat-conducting ring between the stator core 100 and the housing 300. The heat-conducting ring is a high-thermal-conductivity epoxy resin 106. The epoxy resin 106 wraps the stator winding 105, the first stator permanent magnet 101, the second stator permanent magnet 102, and the stator core 100 and other stator heating components. The heat generated by the four can be transferred to the housing 300 and cooled by the housing liquid cooling. At the same time, the epoxy resin 106 wraps part of the first heat-conducting sheet 103 and the second heat-conducting sheet 104 to form a heat transfer path. Since the heat-conducting sheet has a higher thermal conductivity than epoxy resin, the epoxy resin 106 can also transfer the 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.

[0035] For the rotor part, its heat source is 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 the first non-magnetic adhesive 204, and the second rotor core 201 and the second rotor permanent magnet 203 are fixed together by the second non-magnetic adhesive 205. The first rotor core 200 is provided with a plurality of first rotor weight-reducing holes 206 arranged in the circumferential direction. The second rotor core 201 is provided with a plurality of second rotor weight-reducing holes 207 arranged in the circumferential direction.

[0036] Reference Figure 8 and Fig. 9 In the rotor part, the self-circulating hollow shaft cooling method is mainly adopted, and the cooling medium is not limited to water, oil and other liquids with strong cooling capacity. The self-circulating hollow shaft cooling is to set the hollow shaft flow channel inlet 503, the first outlet 504 and the second outlet 505 on the same side of the rotating shaft 501 to form a single-sided "one inlet and two outlets" structure, and the flow channel inlet 503 is one end of a pipe 502 mechanically coupled to the seal 500, and the other end of the pipe 502 is inserted into the cavity inside the rotating shaft 501 to form a cooling medium inlet channel, and 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 to cool the rotating shaft 501, 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 the flow in the rotating shaft 501. The rotating shaft 501 is partially a cavity and partially a solid. For details, see Figure 8 1 / 4 cross-sectional view of the rotating shaft 501. The material of the pipe 502 includes but is not limited to copper, aluminum, stainless steel, etc. The seal 500 is located between the first end cover 400 and the first rotor core 200, and the two sides are closely attached to the first end cover 400 and the first rotor core 200, playing a sealing role to prevent the cooling medium from flowing out from other positions except the first outlet 504 and the second outlet 505 of the flow channel.

[0037] Reference Fig.10 The end cover air cooling is a common cooling structure for the stator and rotor parts, which can cool the stator and rotor parts at the same time. Its specific structure is: a first end cover vent hole 404 is opened on the first end cover 400, a second end cover vent hole 405 is opened on the second end cover 401, and an epoxy resin vent hole 107 is opened on the epoxy resin 106 to form an axial air duct. The axial wind can directly take away the accumulated heat of the epoxy resin 106 through the epoxy resin vent hole 107, forming a direct cooling effect on it; at the same time, the first end cover vent hole 404 and the second end cover vent hole 405 can also indirectly cool the first heat conductive sheet 103 and the second heat conductive sheet 104.

[0038] Depend on Fig.11 It can be seen from the heat flow direction of the rotor part shown that on the inner diameter side of the rotor, the heat of 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 rotating shaft 501, and is cooled by the self-circulating hollow shaft liquid cooling. On the outer diameter side of the rotor, the heat of the first rotor core 200, the first rotor permanent magnet 202, the second rotor core 201 and the second rotor permanent magnet 203 will be dissipated to the air between the first rotor core 200 and the second rotor core 201 and the casing 300, and is cooled by the end cover air cooling.

[0039] Example 2 This embodiment provides a multi-torque component axial flux motor, including the hybrid cooling structure provided in Embodiment 1.

[0040] The term "consisting of" describing a combination shall include the identified elements, ingredients, parts or steps and other elements, ingredients, parts or steps that do not substantially affect the basic novel characteristics of the combination. The use of the terms "comprising" or "including" to describe a combination of elements, ingredients, parts or steps herein also contemplates embodiments that consist essentially of these elements, ingredients, parts or steps. By using the term "may", it is intended to illustrate that any of the attributes described that "may" be included are optional.

[0041] Multiple elements, ingredients, parts or steps can be provided by a single integrated element, ingredient, part or step. Alternatively, a single integrated element, ingredient, part or step can be divided into separate multiple elements, ingredients, parts or steps. The disclosure "one" or "an" used to describe an element, ingredient, part or step is not intended to exclude other elements, ingredients, parts or steps.

[0042] It should be understood that the above description is for illustration and not for limitation. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but rather with reference to the foregoing claims and the full scope of equivalents to which such claims are entitled. For the purpose of comprehensiveness, all articles and references, including disclosures of 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 to be a waiver of such subject matter, nor should it be considered that the applicant has not considered such subject matter to be part of the disclosed inventive subject matter.

Claims

1. A hybrid cooling structure for a multi-torque component axial flux motor, characterized in that: It includes a casing liquid cooling structure, a tank cooling structure and a heat conduction structure; The casing liquid cooling structure comprises a cooling channel (304) arranged in the casing (300), wherein the cooling channel (304) has a cooling channel inlet (302) and a cooling channel outlet (303); The slot cooling structure comprises a first heat conductive sheet (103) and a second heat conductive sheet (104) embedded in the stator slot, wherein the first heat conductive sheet (103) is arranged between the first permanent magnet (101) and the stator winding (105), and is in contact with both of them; the second heat conductive sheet (104) is located between the second stator permanent magnet (102) and the stator winding (105), and is in contact with both of them; one end of the first heat conductive sheet (103) and the second heat conductive sheet (104) is in contact with the stator core (100), and the other end extends into the casing (300); The heat-conducting structure comprises a heat-conducting ring located between the stator core (100) and the casing (300).

2. A hybrid cooling structure for a multi-torque component axial flux motor according to claim 1, characterized in that: The invention also includes an end cover air cooling structure, wherein the end cover air cooling structure includes a first end cover ventilation hole (404) and a second end cover ventilation hole (405) respectively opened on the first end cover (400) and the second end cover (401), and a heat conductive ring ventilation hole opened on the heat conductive ring, wherein the first end cover ventilation hole (404), the second end cover ventilation hole (405) and the heat conductive ring ventilation hole form an axial air duct.

3. The hybrid cooling structure of a multi-torque component axial flux motor according to claim 1, characterized in that: The invention 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 rotating shaft (501) through a pipeline (502) to form a cooling medium inlet channel, and a cooling medium outflow channel is formed between the pipeline (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.

4. The hybrid cooling structure of a multi-torque component axial flux motor according to claim 3, characterized in that: The flow channel inlet (503), the first outlet (504) and the second outlet (505) are arranged on the same side of the rotating shaft (501).

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

6. The hybrid cooling structure of a multi-torque component axial flux motor according to claim 1, characterized in that: The cooling channel (304) is of a circumferential spiral type or an axial Z-type.

7. The hybrid cooling structure of 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 in a symmetrical structure with respect to the axial center plane of the stator.

8. The hybrid cooling structure of 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 the thermal conductivity of the heat conducting ring.

9. A hybrid cooling structure for a multi-torque component axial flux motor according to claim 1 or 8, characterized in that: The heat-conducting ring is made of epoxy resin.

10. A multi-torque component axial flux motor, characterized in that: A hybrid cooling structure comprising a multi-torque component axial flux motor as described in any one of claims 1-9.

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