Integrated Self-Driving Cooling Device for Inner and Outer Parts of Power Adaptive Axial Flux Permanent Magnet Motor

Abstract

The present invention discloses an internal and external integrated self-driven cooling device for a power adaptive axial flux permanent magnet motor, comprising: an internal active drive cooling part which is of a sector disk unit structure and is installed between the stator and rotor air gaps; an external passive drive heat dissipation part which is of an arc-shaped cylinder unit structure and is installed at the outer arc of the internal active drive cooling part; a sealed magnetic attraction interface part for tightly connecting the internal active drive cooling part and the external passive drive heat dissipation part; a magnetic shielding heat conduction bridge part for isolating the internal air gap magnetic field and transferring the internal heat to the outside by heat conduction; and a cooling medium which is a magnetic fluid for magnetic sealing, adapting to the magnetic field strength and efficient heat exchange. The present invention designs a heat dissipation structure according to the operation mode of the motor magnetic field and the magnetic force performance and magnetic heat performance of the magnetic fluid to achieve the self-driving and self-cooling of the motor closed cooling system, and has a cooling effect of adapting to the heat generation of motors with different powers, so as to realize the cooling regulation of motor power adaptability.

Description

Technical Field

[0001] The present invention relates to an axial flux permanent magnet motor, and particularly to an integrated self-driven cooling device for the inside and outside of a power adaptive axial flux permanent magnet motor. Background Art

[0002] Due to the topological structure with a high aspect ratio (large radius, short axial length), the axial flux permanent magnet motor has a very significant high torque density. In order to improve the power density of the axial flux permanent magnet motor and miniaturize the drive propulsion system, the trend of its development towards higher speeds has become inevitable. However, with the continuous improvement of the motor power density, the electromagnetic losses inside it will increase accordingly. Without an efficient cooling structure or equipment, the thermal faults caused by overheating of the key parts of the motor have become a bottleneck restricting the development of the electrical industry. In order to improve the cooling and heat dissipation capabilities of the motor, various cooling methods such as air cooling, liquid cooling and phase change cooling have been proposed and achieved good cooling and heat dissipation effects in the actual operation of the motor.

[0003] Currently, the cooling method with better cooling effect adopted by the motor is to pressurize the cooling medium by regulating external pressurizing equipment to achieve the purpose of circulation. At the same time, for the cooling medium after absorbing heat, relatively complex cooling equipment is also required to cool it down. These external devices not only increase the supporting cost and volume of the motor, but also there is a risk of leakage at the connection between the inlet and outlet and the external devices. In addition, it also requires complex program design and condition monitoring to adjust the heat dissipation of the external device to match the heat generation of the motor when operating at different powers, which undoubtedly puts higher requirements on the adaptability and intelligence of the motor cooling equipment.

[0004] Therefore, the applicant of the present invention has proposed a power adaptive integrated self-driven cooling device for an axial flux motor using magnetic fluid as the cooling medium.

[0005] The description of magnetic fluid is as follows. As a colloidal solution mixture of magnetic particles, carrier liquid and active agent, magnetic fluid has a controllable rheological property that changes with the external magnetic field strength. Under the action of an external magnetic field, magnetic fluid can not only exhibit the strong magnetism of solid magnetic materials, but also exhibit the fluidity of liquids. In addition, the magnetocaloric effect exhibited by magnetic materials may be applied to technologies such as heating, refrigeration and magnetic energy conversion. Summary of the Invention

[0006] The purpose of the present invention is to provide an integrated self-driven cooling device for the inside and outside of a power adaptive axial flux permanent magnet motor.

[0007] To solve the above technical problems, the present invention adopts the following technical solutions:

[0008] Power adaptive axial flux permanent magnet motor internal and external integrated self-driven cooling device, including cooling medium, internal active drive cooling part and external passive drive heat dissipation part;

[0009] The internal active drive cooling part is used to absorb the heat generated by the heat-generating structure on the stator side of the motor, the rotor side structure, and the heat conducted into the air gap; the internal active drive cooling part is a sector disk unit structure and is installed between the stator and rotor air gaps. N sector disk unit structures are arranged in a periodic distribution along the circumferential direction to form an annular disk structure;

[0010] Each sector disk unit structure is provided with an inlet channel, an outlet channel, and m cooling elbows arranged radially inside the main body. Each cooling elbow extends along the circumferential direction of the air gap magnetic field movement to form a magnetic field-enhanced cooling elbow. The cooling elbows are located between the internal inlet channel and the internal outlet channel and are connected to both of them;

[0011] The external passive drive heat dissipation part is used to demagnetize the cooling medium so that it can be quickly cooled; the external passive drive heat dissipation part is an arc-shaped cylinder unit structure, which corresponds to the internal active drive cooling part one by one and has the same circumferential coverage angle; the external passive drive heat dissipation part is installed at the outer arc of the corresponding internal active drive cooling part. N arc-shaped cylinder unit structures are arranged in a periodic distribution along the circumferential direction to form a cylindrical structure; the main body of the external passive drive heat dissipation part is provided with a heat dissipation tube with a demagnetization symmetric array, and the heat dissipation tube has a heat dissipation tube inlet and a heat dissipation tube outlet;

[0012] The inlet channel of the internal active drive cooling part is connected to the heat dissipation tube outlet of the external passive drive heat dissipation part, and the outlet channel of the internal active drive cooling part is connected to the heat dissipation tube inlet of the external passive drive heat dissipation part, thus forming a cooling cycle;

[0013] There is a gap in the radial direction between the internal active drive cooling part and the external passive drive heat dissipation part;

[0014] The cooling medium is a magnetic fluid, which is filled in the pipelines of the internal active drive cooling part and the external passive drive heat dissipation part; the magnetic fluid realizes self-driving and power adaptation by the action of the axial magnetic field of the axial flux permanent magnet motor.

[0015] Furthermore, the outer diameter of the internal active drive cooling part is the same as the outer diameter of the stator side structure, and the inner diameter is the same as the inner diameter of the rotor side structure; one axial side of the internal active drive cooling part is in contact fit with the stator part, and the other axial side of the internal active drive cooling part is in clearance fit with the rotor part.

[0016] Further, the main body of the internal active drive cooling part is made of non-metallic material, and flow channels are formed in the main body to form an inlet section flow channel, an outlet section flow channel, and a cooling elbow; the inlet section flow channel and the outlet section flow channel are respectively arranged to extend radially, and the inlet and outlet pipe diameters of the two are the same, which is the pipe diameter of the internal magnetic attraction interface.

[0017] The axial thickness of the internal active drive cooling part is positively correlated with the motor power, and a certain margin should be reserved to prevent rubbing phenomenon.

[0018] Further, the number m of the cooling elbows arranged radially is the same as the number of turns of the stator winding; the m cooling elbows are arranged with unequal diameters, and their pipe diameters are distributed in a positive correlation with the air-gap magnetic field intensity, that is, the pipe diameter of the elbow in the middle is the largest, gradually decreasing towards the inside and outside, and does not exceed the axial reliability thickness of the internal active drive cooling part.

[0019] Further, the main body of the external passive drive heat dissipation part is made of a material with high thermal conductivity and low magnetic permeability, and flow channels are formed in the main body to form heat dissipation pipes.

[0020] The heat dissipation pipe inlet and the heat dissipation pipe outlet of the external passive drive heat dissipation part are located at the central radial section of the internal active drive cooling part and the pipe diameters of the two are the same, which is the pipe diameter of the external magnetic attraction interface; two groups of heat dissipation pipes of the external passive drive heat dissipation part are axially symmetrically arranged about the central radial section, and the axial length is greater than the circumferential length; the two groups of heat dissipation pipes are both connected in an S shape.

[0021] The radial thickness of the external passive drive heat dissipation part is positively correlated with the motor power.

[0022] Further, the number N of units of the internal active drive cooling part / the external passive drive heat dissipation part is consistent with the number of rotor magnetic poles; the circumferential span of the units of the internal active drive cooling part .

[0023] Further, internal magnetic attraction interfaces are arranged at the outer side positions of the inlet section flow channel and the outlet section flow channel, and external magnetic attraction interfaces are arranged at the positions of the heat dissipation pipe inlet and the heat dissipation pipe outlet;

[0024] The inlet section flow channel of the internal active drive cooling part and the heat dissipation pipe outlet of the external passive drive heat dissipation part are connected through the matching internal magnetic attraction interface and external magnetic attraction interface to form a sealed magnetic attraction interface part, and the outlet section flow channel of the internal active drive cooling part and the heat dissipation pipe inlet of the external passive drive heat dissipation part are connected through the matching internal magnetic attraction interface and external magnetic attraction interface to form a sealed magnetic attraction interface part, so as to realize a highly sealed cooling cycle.

[0025] Further, the inner magnetic attraction interface is located within the magnetic field. It has a lower flow-through pipe, which is an extension of the inlet channel / outlet channel of the internally actively driven cooling part. There is a main coil on the outer side of the lower flow-through pipe. A plurality of iron core bolts extending upward are arranged around the lower flow-through pipe. The lower half of the iron core bolt is wound with a secondary coil, and the secondary coil is connected to the main coil. When the cooling medium passes through the lower flow-through pipe from bottom to top, a current will be induced on the main coil and transmitted to the secondary coil. The secondary coil makes the iron core bolt magnetic through electric excitation and induces a polarity at the upper end.

[0026] The outer magnetic attraction interface has an upper flow-through pipe, which is an extension of the heat dissipation pipe inlet / heat dissipation pipe outlet of the externally passively driven heat dissipation part. At the position corresponding to the iron core bolt on the outer magnetic attraction interface, there is a card slot, and a strong magnetic material with a polarity different from that of the end of the iron core bolt is arranged inside the card slot. The card slot is communicated with the upper flow-through pipe through an inlet hole below and an outlet hole above.

[0027] The interface between the inner magnetic attraction interface and the outer magnetic attraction interface is composed of strong magnetic materials with different magnetic polarities.

[0028] Further, an arc-shaped area is formed at the gap between the internally actively driven cooling part and the externally passively driven heat dissipation part. An internal and external magnetic isolation heat transfer bridge part is arranged at the arc-shaped area. The internal and external magnetic isolation heat transfer bridge part is closely attached to both the internally actively driven cooling part and the externally passively driven heat dissipation part. The internal and external magnetic isolation heat transfer bridge part is used to isolate the internal air gap magnetic field and transfer the heat of the internally actively driven cooling part to the externally passively driven heat dissipation part by means of heat conduction.

[0029] The internal and external magnetic isolation heat transfer bridge part includes a composite plate, which is laminated by heat-conducting and magnetic-conducting layers and heat-conducting and non-magnetic-conducting layers arranged alternately along the radial direction. At the same time, a plurality of heat-conducting holes are distributed along the circumferential direction on the composite plate. The heat-conducting holes extend along the radial direction and penetrate through the composite plate, and the heat-conducting holes are filled with directional heat-conducting columns.

[0030] Further, the Curie temperature of the magnetic fluid used as the cooling medium is higher than the hot spot temperature of the motor to avoid its demagnetization at high temperature; the saturation magnetization intensity of the magnetic fluid is lower than the air gap synthetic magnetic field intensity to reduce the consumption of magnetic field energy.

[0031] The beneficial effects of the present invention are as follows:

[0032] 1. The present invention designs a main and passive combined self-driven cooling device for the internally actively driven cooling part and the externally passively driven heat dissipation part to realize the self-driving and self-cooling of the cooling system, greatly reducing the cost and system volume of the external pressurization equipment and the auxiliary cooling equipment, and enhancing the reliability and power density of the system.

[0033] The present invention utilizes the magnetic force performance and magnetothermal performance of magnetic fluid to achieve self-driving and self-cooling of a closed cooling system, and has the effect of being affected by a rotating magnetic field to adapt to the power and loss heat generation of the motor at different torques and speeds, so as to achieve self-adaptive cooling control of the motor power.

[0034] 2. The internal filling of the internal active drive cooling part is magnetic fluid as the cooling medium. Utilizing its magnetic force performance can improve the magnetic conductance between the stator and rotor, thereby reducing the magnetic voltage drop in the air gap between the stator and rotor, indirectly increasing the air gap magnetic density, and further improving the electromagnetic performance of the motor. At the same time, the cooling medium magnetic fluid has the effect of being tractioned by the rotating magnetic field to adapt to the power and loss heat generation of the motor at different torques and speeds, so as to achieve self-adaptive cooling control of the motor power.

[0035] 3. In order to maximize the heat transfer efficiency of the cooling device, it is necessary to make full use of the magnetothermal performance of the cooling medium magnetic fluid. For this purpose, this patent designs a degaussing symmetric array heat dissipation tube structure for the internal and external magnetic isolation heat transfer bridge part and the external passive drive heat dissipation part. The combined action of the two will limit the air gap magnetic field only inside the motor, and the magnetic fluid in the external passive drive heat dissipation part will be demagnetized, so as to make full use of the magnetothermal effect to release heat to the external area.

[0036] 4. The present invention also designs a sealed magnetic adsorption interface part, which not only realizes high tightness and super fixing ability during the operation of the motor, but also is used to realize the separable connection of the internal active drive cooling part and the external passive drive heat dissipation part, so that different internal active drive cooling parts and external passive drive heat dissipation parts can be replaced according to motors with different parameters under different operating conditions for combined cooling. Description of the Drawings

[0037] Figure 1 is the overall schematic diagram of the present invention;

[0038] Figure 2 is the overall front view of the present invention;

[0039] Figure 3 is the overall side view of the present invention;

[0040] Figure 4 is the overall top view of the present invention;

[0041] Figure 5 is the structural schematic diagram of the internal active drive cooling part in the present invention

[0042] Figure 6 is the principle schematic diagram of the internal active drive cooling part in the present invention;

[0043] Figure 7 is the structural and principle schematic diagram of the external passive drive heat dissipation part in the present invention;

[0044] Figure 8 This is a schematic diagram of the structure and principle of the sealed magnetic interface part of the present invention;

[0045] Figure 9 It is a front view of the inner and outer magnetic isolation and heat transfer bridge parts of the present invention;

[0046] Figure 10 A top view of the inner and outer magnetic isolation and heat transfer bridges of the present invention;

[0047] Figure 11 It is a side view of the inner and outer magnetic isolation and heat transfer bridge parts of the present invention.

[0048] The accompanying drawings are for illustrative purposes only and should not be construed as limitations on this patent. To better illustrate this embodiment, some parts of the accompanying drawings may be omitted, enlarged, or reduced in size, and do not represent the actual size of the product. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the accompanying drawings may be omitted. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0050] Example 1:

[0051] like Figures 1 to 11 As shown, this embodiment discloses an integrated internal and external self-driven cooling device for a power-adaptive axial flux permanent magnet motor. The device primarily comprises a cooling medium 1, an internal active drive cooling portion 2, an external passive drive heat dissipation portion 3, a sealed magnetic interface portion 4, and internal and external magnetic isolation and heat transfer bridge portions 5. The cooling device is attached to the stator surface between the stator and rotor air gaps to provide sufficient cooling for the stator, rotor, and air gap.

[0052] The cooling medium 1 is a ferrofluid, which is filled in all the pipelines of the cooling device. The cooling medium 1 in the internal active drive cooling part 2 is actively driven by the rotating synthetic magnetic field inside the motor, so that it has a certain momentum (the higher the power of the motor, the higher the driving intensity, and thus the higher the kinetic energy of the cooling medium). At the same time, the synthetic magnetic field magnetizes the cooling medium to make it magnetic (this process uses the magnetocaloric performance of the ferrofluid to absorb heat), thereby reducing the air-gap magnetic resistance and increasing the magnetic field strength of the motor gap. The cooling medium 1 in the internal active drive cooling part 2 enters the external passive drive heat dissipation part 3 due to its own momentum. This process causes the cooling medium 1 in the external passive drive heat dissipation part 3 to be passively driven to continue circulating. At the same time, the heat dissipation pipes 33 of the demagnetization symmetric array and the internal and external magnetic insulation heat transfer bridge part 5 in the external passive drive heat dissipation part 3 will limit the internal synthetic magnetic field only inside the motor and completely demagnetize the magnetized cooling medium 1 (this process uses the magnetocaloric performance of the ferrofluid to release heat). In addition, during the operation of the motor, the sealed magnetic attraction interface part 4 uses the cooling medium 1 with momentum and magnetism for excitation and sealing, so that the internal active drive cooling part 2 and the external passive drive heat dissipation part 3 can be tightly connected. The above cooling device finally achieves the effects of power adaptability, self-driving and self-cooling.

[0053] Since the axial-flux motor has periodicity in the circumferential direction and the unit cooling of the discrete unit can be adjusted according to the structure and power of the motor itself. Therefore, the cooling device will be designed as a unit structure arranged in a periodic distribution (to meet the rotor heat dissipation effect, the number is the same as the number of rotor magnetic poles, which is N periodic units). The main body cooling and heat dissipation structure of the unit is mainly composed of the internal active drive cooling part 2 of the sector disk unit structure with a circumferential span and the external passive drive heat dissipation part 3 of the arc-shaped cylinder thin-wall unit structure with a circumferential span . The internal active drive cooling parts 2 of multiple sector disk unit structures are arranged in a periodic distribution along the circumferential direction and spliced to form an annular disk structure, and the external passive drive heat dissipation parts 3 of multiple arc-shaped cylinder thin-wall unit structures are arranged in a periodic distribution along the circumferential direction and spliced to form a cylindrical structure.

[0054] Taking the cooling device of one periodic unit as an example, as Figures 2 - 4 shown.

[0055] The outer radius of the internal active drive cooling part 2 is the same as the outer radius of the stator, and its inner diameter is the same as the minimum inner diameter of the stator and rotor side structures (that is, ), and the radial length of this part is This part of the structure is used to cool the heat - generating stator - side part 6 (which includes the stator core and the stator winding), the air gap 7, and the rotor - side part (which includes the magnetic poles and the rotor core). One side of the internal active - drive cooling part 2 is in contact and cooperation with the stator - side part 6; the other side is the rotating rotor part 8 (which includes the rotor core and the magnetic poles), and there is a certain design gap (i.e., the air gap 7) between them. The external passive - drive heat - dissipation part 3 is located outside the outer radius outside, and the demagnetizing symmetric - array heat - dissipation tubes with a pipe diameter of can make full use of the magneto - thermal effect to dissipate the heat absorbed by the cooling medium 1 from the inside to the external environment. The external passive - drive heat - dissipation part 3 is installed at the outer arc of the internal active - drive cooling part 2 and has the same span angle , and the two are connected through the sealed magnetic - attraction interface part 4 to achieve the cooling cycle. The gap between the internal active - drive cooling part 2 and the external passive - drive heat - dissipation part 3 is the internal - external magnetic - isolation heat - transfer bridge part 5. This part can form a large magnetic resistance in the radial direction to play a shielding role to ensure that the external passive - drive heat - dissipation part 3 has basically no magnetic - field intensity, and the heat - conducting columns inside it can directly transfer the internal active - drive cooling part 2 to the external passive - drive heat - dissipation part 3.

[0056] The cooling medium 1 is a magnetic fluid. Since the magnetic fluid is composed of magnetic particles, carrier liquid, and active agent, the selection of materials and their proportioning of the three determine the magnetic properties, viscosity, specific heat capacity, and magneto - thermal performance of the cooling medium, etc. The magnetic properties of the magnetic fluid determine the magnetic - field force it receives in the magnetic field, the viscosity determines the flow loss caused during the circulation process, the specific heat capacity determines its heat - absorption capacity, and the magneto - thermal performance determines the final effect of its magnetic refrigeration and heat exchange. Therefore, for the composition of the cooling medium, according to the development of materials in the current period, a magnetic - fluid medium that can finally exhibit high magnetism, low viscosity, high specific heat capacity, and strong magneto - thermal performance should be selected. In addition, the magnetic particles in the magnetic fluid are at the nanometer level, and the conductive performance of the carrier liquid is poor, so there is basically no eddy - current loss. At the same time, the magnetic fluid has superparamagnetism, and its hysteresis loss in the alternating magnetic field can also be ignored.

[0057] As Figures 5 to 6 shown, the internal active - drive cooling part 2 absorbs the heat of the heat - generating stator - side part 6, rotor - side part 8, and the heated air - gap part 7 through the cooling medium 1. This part of the structure includes an inlet - section flow channel 21, an outlet - section flow channel 22, and m unequal - diameter cooling elbows 23 arranged radially. The inlet - section flow channel 21 and the outlet - section flow channel 22 extend radially respectively (taking the principle that the sum of the running trajectories of the magnetic - force lines and the flow loss in the pipeline is the smallest, and giving priority to the arrangement method of arranging the inlet - section flow channel and the outlet - section flow channel radially). The cooling elbows 23 are located between the inlet - section flow channel and the outlet - section flow channel and are connected to them. The size of the pipe diameter is designed to be positively correlated with the magnetic - field intensity (the pipe diameter of the elbow in the middle is the largest, and gradually decreases towards the inside and outside, and (being the smallest). Both the inlet channel 21 and the outlet channel 22 are connected to the internal magnetic interface 41. Since the cooling medium 1 filled inside is a magnetorheological fluid, the design method of the unequal-diameter cooling elbow can not only meet the adaptation of the active driving ability of the magnetic field strength at different positions, but also utilize its magnetic properties to increase the magnetic conductance between the stator and the rotor and reduce the magnetic pressure drop, indirectly improving the air-gap magnetic density and thus enhancing the electromagnetic performance of the motor. The internal active driving cooling part 2 has a certain thickness in the axial direction , and the outer diameters of the cooling elbows 23 need to be smaller than the axial thickness and meet the requirements of the mechanical strength design

[0058] To avoid eddy current losses generated by the conductors located in the alternating magnetic field here, the fan-shaped disc body of the internal active driving cooling part 2 is made of a non-metallic material (such as graphene-reinforced composite material, etc.). After being made, flow channels are opened inside to form the inlet channel 21, the outlet channel 22 and the cooling elbows 23. The cooling medium 1 is filled inside the pipes of the internal active driving cooling part 2, which will increase the magnetic conductance of the magnetic circuit in the stator-rotor gap

[0059] As Figure 3 shown in the principle, the magnetic force lines in the magnetic field are represented by "·" when passing through the plane of the figure, and "×" when passing into the plane of the figure. The cooling elbow 23 has an initial velocity and a mass of magnetorheological fluid microelement, and its combined action is mainly composed of the traction force of the magnetic field , the centrifugal force moving along the circumference , the gravity of the magnetorheological fluid , the radial constraint force of the pipe on it , and the frictional force , and finally has an acceleration of . When considering the continuity of the magnetorheological fluid microelement, the magnetorheological fluid microelement at the back will push the magnetorheological fluid microelement in front in the moving direction

[0060] At the time from t1 to t2, the cooled temperature is and the demagnetized low-temperature magnetorheological fluid microelement 11 enters each elbow from the inlet channel 21. Assuming that the magnetic force lines of the magnetic field pass through the screen at this time, the low-temperature magnetorheological fluid microelement 11 is magnetized by the magnetic field and is pulled by the magnetic force and gradually moves in a circular direction along the cooling elbow 23

[0061] At the time from t2 to t3, the magnetorheological fluid is gradually moving in a circular direction under the action of its combined force , and at the same time, the temperature of the magnetized medium-temperature magnetorheological fluid microelement 12 rises due to the magnetocaloric effect According to the relevant theory of magnetocaloric effect, the temperature change caused by the change of magnetic field under adiabatic conditions is defined by the following expression:

[0062] (Equation 1.1)

[0063] where is the magnetic field strength between the stator and rotor where the low-temperature magnetic fluid microelement 11 is located, is the specific heat capacity of the low-temperature magnetic fluid microelement 11 under a constant magnetic field, is the magnetization intensity, is the magnetic field strength, is the temperature. It can be seen from this equation that is inversely proportional to and is directly proportional to For the isothermal magnetic entropy related to temperature, its expression is:

[0064] (Equation 1.2)

[0065] For the application of magnetocaloric effect in existing cooling equipment, the and of its materials are both large. Therefore, the above two points should also be fully considered in the material selection and configuration of magnetic fluid. In addition, like other magnetic materials, the magnetization intensity of magnetic fluid will decrease with the increase of temperature, and it will also lose its magnetism when it is heated to a certain high temperature, and this temperature is called the Curie temperature . Therefore, when preparing magnetic fluid, its Curie temperature should be much higher than the hot spot temperature of the motor. The main stage of heat absorption of magnetic fluid is from t2 to t3.

[0066] At the time from t3 to t4, it is assumed that the magnetized medium-temperature magnetic fluid microelements 12 at different radial positions flow through the cooling elbow 23 and absorb the heat of the electromagnetic loss of the stator core 01 and the stator winding 02 and then heat up , and it becomes a high-temperature magnetic fluid microelement 13 and reaches the outlet section flow channel 22. It is assumed that the temperature rise caused by the flow loss during the whole process is , which is mainly affected by the magnetic fluid Reynolds number . The final temperature of the high-temperature magnetic fluid microelement 13 is:

[0067] (Equation 1.3)

[0068] During this process, as the ferrofluid absorbs heat and its temperature rises, affected by the magnetocaloric effect, its magnetization intensity gradually weakens, and thus the force exerted by the magnetic field decreases. Therefore, the magnetization intensity of the low-temperature ferrofluid microelement 11 located in the radial elbow is higher than that of the medium-temperature ferrofluid microelement 12, and similarly, the magnetization intensity of the medium-temperature ferrofluid microelement 12 is higher than that of the high-temperature ferrofluid microelement 13. The magnetic forces exerted on the three also decrease in sequence, and the low-temperature ferrofluid microelement 11 will move towards the high-temperature ferrofluid microelement 13 and thus replace the high-temperature ferrofluid microelement 13. As a result, a pressure difference will be formed between the two ends of the cooling elbow 23, achieving the purpose of self-driving the cooling medium.

[0069] In addition, different rotational speeds of the motor correspond to different powers of the motor , and the resultant magnetic field in the stator-rotor air gap will also have different rotational speeds [[ID=⑨]]After magnetization, the ferrofluid will be subjected to the traction of a rotating magnetic field with different rotational speeds and have different flow velocities, and its work and pressure-increasing capabilities will also be different. When the rotational speed and power are relatively large, the temperature of the high-temperature ferrofluid microelement will also increase, but the ferrofluid will also have a higher flow velocity, which will accelerate the speed of the cooling cycle and ultimately cause the temperature of the motor to drop. This undoubtedly realizes the adaptive regulation of the cooling system for the motor power.

[0070] As Figure 7 shown, the function of the external passive drive heat dissipation part 3 is to quickly demagnetize the cooling medium 1 and make full use of the magnetocaloric effect to improve its cooling efficiency to achieve the rapid cooling of the cooling medium 1. The external passive drive heat dissipation part 3 includes an arc-shaped cylinder thin-wall main body made of materials with high thermal conductivity, low magnetic permeability, and high structural strength (such as 316L stainless steel, C17200 beryllium bronze, 6061 aluminum, C110 copper, etc.). The arc-shaped cylinder thin-wall main body is provided with an external magnetic attraction interface 42 at its central radial section, and a demagnetization symmetric array of heat dissipation tubes 33 is designed inside the arc-shaped cylinder thin-wall main body. The radial thickness of the external passive drive heat dissipation part 3 is the same as the axial thickness of the internal active drive cooling part 2, which is , and the heat dissipation tubes 33 with a diameter of are distributed circumferentially with roots and are axially symmetric about the central radial section. The axial length of a single-sided heat dissipation tube is and the circumferential length is (simultaneously satisfying ), the heat dissipation pipes are connected in an S shape to form two axially symmetric groups. Considering two magnetohydrodynamic micro-elements of a symmetric cooling medium in the axial pipes, the magnetic field line directions of the two are opposite in the axial direction, so they have a strong demagnetizing effect. However, the magnetism in the circumferential pipes is the same and the magnetic fields are superimposed and enhanced. Therefore, it is necessary to ensure that . The units of the external passive drive heat dissipation part 3 and the internal active drive cooling part 2 correspond one by one and the circumferential span angles are all ; the external passive drive heat dissipation part 3 is installed on the radial outside of the internal active drive cooling part 2, so that the inner magnetic attraction interface 41 and the outer magnetic attraction interface 42 are tightly connected.

[0071] The high-temperature magnetohydrodynamic micro-elements 13 flowing out from the outlet section flow channel 22 of the internal active drive cooling part 2 flow into the heat dissipation pipe 33 from one side of the outer magnetic attraction interface 42. There is a flow channel for the high-temperature magnetohydrodynamic micro-elements 13 inside the heat dissipation pipe 33, and the high-temperature magnetohydrodynamic micro-elements 13 are demagnetized without the action of an external magnetic field. At the same time, heat exchange occurs between the inner wall surface of the flow channel inside the heat dissipation pipe 33 and the high-temperature magnetohydrodynamic micro-elements 13, and the heat is transferred to the heat dissipation pipe 33. The outer circumferential surface of the arc-shaped cylinder thin-wall main body of the external passive drive heat dissipation part can be in contact with air or other cooling media to achieve secondary heat exchange.

[0072] When the power is large and the heat generation is large, the number of heat dissipation pipes and the pipe diameter correspondingly increase to achieve a strong cooling effect. On the contrary, the number of heat dissipation pipes and the pipe diameter correspondingly decrease to achieve the effects of cost saving and weight reduction. Finally, it is necessary to ensure that the high-temperature magnetohydrodynamic micro-elements 13 are cooled down to . Since the magnetohydrodynamic fluid is continuous and there is a pressure difference in the internal active drive cooling part 2, the cooled low-temperature magnetohydrodynamic micro-elements 11 will be transported from the outlet 32 to the inlet section flow channel 21 of the internal active drive cooling part 2, thereby realizing the overall cooling cycle and finally realizing the self-cooling of the system.

[0073] The number of cycle unit N, thickness , regional span and pipe diameter of the assembly of this cooling device should be adjusted according to the power and heat generation of the motor. When the power is large and the heat generation is large, the number of cycle units N, thickness , regional span and pipe diameter correspondingly increase to achieve a strong cooling effect. On the contrary, the number of cycle units N, thickness , regional span and pipe diameter correspondingly decrease to achieve the effects of cost saving and weight reduction.

[0074] As Figure 8 shown, the sealed magnetic interface part 4 is composed of an inner magnetic interface 41 and an outer magnetic interface 42. The two are respectively fixed to the internal active drive cooling part 2 and the external passive drive heat dissipation part 3.

[0075] The inner magnetic interface 41 is located within the magnetic field. It has a lower flow-through pipe 410, and the lower flow-through pipe 410 is an extension of the inlet section flow path / outlet section flow path of the internal active drive cooling part. There is a main coil 413 outside the lower flow-through pipe 410; four iron core bolts 412 extending upward are arranged around the lower flow-through pipe 410, and the lower half of the iron core bolts 412 is wound with a secondary coil 414. The secondary coil 414 is connected to the main coil 413 through a terminal.

[0076] The outer magnetic interface 42 has an upper flow-through pipe 420, and the upper flow-through pipe 420 is an extension of the heat dissipation pipe inlet / heat dissipation pipe outlet of the external passive drive heat dissipation part. Four card slots 424 are provided at positions corresponding to the four iron core bolts 412 on the outer magnetic interface, and a strong magnetic material is arranged inside the card slots 424; the card slots 424 are communicated with the upper flow-through pipe 420 through the lower inlet hole 422 and the upper outlet hole 423.

[0077] The magnetic interface between the inner magnetic interface 41 and the outer magnetic interface 42 is composed of strong magnetic materials with different magnetic polarities. Assume that the magnetic polarity of the first magnetic interface 411 is N and the magnetic polarity of the second magnetic interface 421 is S. When the motor is not running, the two can also be fixed through the magnetic interface, and a little cooling medium 1 can achieve magnetic fluid sealing.

[0078] When the motor is running, the inner magnetic interface 41 is located at the boundary part of the magnetic field. The cooling medium 1 still has strong magnetism and large momentum. When the cooling medium 1 passes through the lower flow-through pipe 410 from bottom to top, a current will be induced on the main coil 413 and transmitted to the secondary coil 414 through the terminal (only one secondary coil is marked in the figure for illustration). At this time, the secondary coil is wound around the iron core bolt 412 and is magnetized through electric excitation to have a magnetic polarity, and an S polarity is induced at the upper end.

[0079] When the motor is running, the outer magnetic interface 42 is located outside the magnetic field (basically no magnetic field). The magnetic fluid still has some magnetism and momentum. Most of the cooling medium 1 passes through the upper flow-through pipe 420 from bottom to top, and a small part flows into the card slot 424 from the inlet hole 422. When the iron core bolt 412 completely enters the card slot 424, its gap will be filled with the cooling medium 1, and the excess will flow into the upper flow-through pipe 420 from the outlet hole 423. A strong magnetic material with a magnetic polarity different from that of the end of the iron core bolt 412 is arranged inside the card slot 424, which can ensure that the sealed magnetic interface part 4 has higher adsorption force and sealing performance when the motor is running.

[0080] AsFigures 9 to 11 As shown in the figure, the internal and external magnetic isolation heat transfer bridge part 5 is used to isolate the internal air gap magnetic field and transfer the heat of the internal active drive cooling part to the external passive drive heat dissipation part by heat conduction, while realizing the separation design concept of the internal and external, active and passive. This part is located in the arc-shaped area between the internal active drive cooling part and the external passive drive heat dissipation part.

[0081] The internal and external magnetic isolation heat transfer bridge part is located in the arc-shaped gap and is in close contact with both the internal active drive cooling part and the external passive drive heat dissipation part. The internal and external magnetic isolation heat transfer bridge part 5 is composed of a heat-conducting and magnetic-conducting layer 51, a heat-conducting and non-magnetic-conducting layer 52, and a directional heat-conducting column 53.

[0082] The internal and external magnetic isolation heat transfer bridge part includes a composite plate, which is laminated by a heat-conducting and magnetic-conducting layer 51 (high magnetic-conducting and heat-conducting material) and a heat-conducting and non-magnetic-conducting layer 52 (material with weak magnetic conductivity but strong heat conductivity) arranged alternately along the radial direction. At the same time, a plurality of heat-conducting holes are distributed along the circumferential direction on the composite plate. The heat-conducting holes extend along the radial direction and penetrate the composite plate, and the directional heat-conducting column 53 is filled in the heat-conducting holes.

[0083] When the edge magnetic field of the motor enters the internal and external magnetic isolation heat transfer bridge part 5, its magnetic circuit will preferentially select the heat-conducting and magnetic-conducting layer 51, and there is partial magnetic leakage located in the heat-conducting and non-magnetic-conducting layer 52. As the radial position increases, the magnetic field strength will continuously decrease, and there is basically no magnetic field on the outer side of the internal and external magnetic isolation heat transfer bridge part 5, which ensures the magnetic isolation environment of the external passive drive heat dissipation part 3. The directional heat-conducting column 53 can not only directly conduct the heat of the internal active drive cooling part 2 to the external passive drive heat dissipation part 3 to achieve efficient heat transfer, but also partition the heat-conducting and magnetic-conducting layer 51 to reduce the eddy current loss of each layer.

[0084] Embodiment 2:

[0085] In this embodiment, the external passive drive heat dissipation part can be cooled by an externally added cooling device.

[0086] In other embodiments, the structural form of the heat dissipation tube can also be changed or replaced to achieve cooling.

[0087] Embodiment 3:

[0088] This embodiment also discloses the composition of the magnetic fluid, which is composed of magnetic particles, a carrier liquid, and an active agent. The selection of materials and the ratio of the three are within the conventional test capabilities of those skilled in the art.

[0089] According to the current research progress on magnetic fluids:

[0090] (1) Magnetic particles: Use Gd5Si2Ge2, MnAs, MnFeP 0.45 As 0.55 La(Fex Si 1-x ) 13 , Mn 0.78 Zn 0.22 Any one of Fe2O4, etc.

[0091] (2) Base carrier liquid: Any one of liquids such as water, organic solvents (hydrocarbon-based carrier liquids), oils, phenols, etc.

[0092] (3) Activator: Any one of oleic acid, etc.

[0093] Taking manganese-zinc ferrite magnetic fluid as an example, when the insulation requirement of the designed motor satisfies that the hot spot temperature is lower than 220 °C, and the content of zinc is selected to be lower than 0.3, the Curie temperature of the manganese-zinc ferrite magnetic fluid is higher than the hot spot temperature of the motor (220 °C), it can meet the requirements.

[0094] The preparation of manganese-zinc ferrite magnetic fluid can refer to the literature: Yang Gang. Research on the Preparation and Properties of Manganese-Zinc Ferrite Magnetic Fluid [D]. Nanjing University of Science and Technology, 2006.

[0095] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the present invention can still be modified or equivalently replaced, and any modification or partial replacement without departing from the spirit and scope of the present invention should be covered by the scope of the claims of the present invention.

[0096] If terms such as "first" and "second" are used in this article to limit components, those skilled in the art should be aware that: the use of "first" and "second" is only for the convenience of describing the present invention and simplifying the description. Without additional declaration, the above terms have no special meaning.

[0097] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is 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 should not be construed as a limitation of the present invention.

[0098] In the description of the present invention, it should be noted that, unless otherwise clearly specified and defined, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

Claims

1. The integrated self-driven cooling device for the inner and outer parts of a power adaptive axial flux permanent magnet motor, characterized in that: It includes a cooling medium, an internal actively-driven cooling part, and an external passively-driven heat dissipation part; The internal actively-driven cooling part is used to absorb the heat generated by the heat-generating structures on the stator side and rotor side of the motor, as well as the heat conducted into the air gap; the internal actively-driven cooling part is a sector disk unit structure and is installed between the stator and rotor air gaps. N sector disk unit structures are arranged periodically along the circumferential direction to form an annular disk structure; Each sector disk unit structure is provided with an inlet section flow channel, an outlet section flow channel, and m cooling elbows arranged radially. Each cooling elbow extends along the circumferential direction. The cooling elbows are located between the internal inlet section flow channel and the internal outlet section flow channel and are connected to both of them; The external passively-driven heat dissipation part is used to demagnetize the cooling medium so that it can be quickly cooled; the main body of the external passively-driven heat dissipation part is provided with symmetrically arranged heat dissipation tubes, and the heat dissipation tubes have a heat dissipation tube inlet and a heat dissipation tube outlet; The inlet section flow channel of the internal actively-driven cooling part is connected to the heat dissipation tube outlet of the external passively-driven heat dissipation part, and the outlet section flow channel of the internal actively-driven cooling part is connected to the heat dissipation tube inlet of the external passively-driven heat dissipation part, thus forming a cooling cycle; A gap is left radially between the internal actively-driven cooling part and the external passively-driven heat dissipation part; The cooling medium is a magnetic fluid, which is filled in the pipelines of the internal actively-driven cooling part and the external passively-driven heat dissipation part; the magnetic fluid realizes self-driving and power adaption by the axial magnetic field action of the axial-flux permanent magnet motor.

2. The self-driven cooling device for the integrated interior and exterior of the power adaptive axial flux permanent magnet motor according to claim 1, wherein: The outer diameter of the internal actively-driven cooling part is the same as the outer diameter of the stator side structure; one axial side of the internal actively-driven cooling part is in contact fit with the stator part, and the other axial side of the internal actively-driven cooling part is in clearance fit with the rotor part.

3. The integrated self-driven cooling device for the power adaptive axial flux permanent magnet motor according to claim 2, wherein: The main body of the internal actively-driven cooling part is made of a non-metallic material, and flow channels are opened in the main body to form an inlet section flow channel, an outlet section flow channel, and cooling elbows; the inlet section flow channel and the outlet section flow channel extend radially respectively; The axial thickness of the internal actively-driven cooling part is positively correlated with the motor power.

4. The integrated self-driven cooling device for the power adaptive axial flux permanent magnet motor according to claim 3, characterized in that: The number m of the cooling elbows arranged radially is the same as the number of turns of the stator winding; the m cooling elbows are of unequal diameters, and their diameters are distributed in a positive correlation with the air gap magnetic field intensity, that is, the diameter of the elbow in the middle is the largest, gradually decreasing towards the inside and outside, and does not exceed the axial reliability thickness of the internal actively-driven cooling part.

5. The integrated self-driven cooling device for the power adaptive axial flux permanent magnet motor according to claim 1, characterized in that: The external passively-driven heat dissipation part is an arc-shaped cylinder unit structure, which corresponds to the internal actively-driven cooling part one by one and has the same circumferential coverage angle; the external passively-driven heat dissipation part is installed at the outer arc of the corresponding internal actively-driven cooling part. N arc-shaped cylinder unit structures are arranged periodically along the circumferential direction to form a cylindrical structure by splicing; The main body of the external passively-driven heat dissipation part is made of a material with high thermal conductivity and low magnetic permeability, and flow channels are opened in the main body to form heat dissipation tubes; The inlet and outlet of the heat dissipation tubes of the external passive drive heat dissipation part are located at the central radial section of the internal active drive cooling part; two sets of heat dissipation tubes of the external passive drive heat dissipation part are axially symmetrically arranged about the central radial section, and the axial length of the heat dissipation tubes is greater than the circumferential length; the two sets of heat dissipation tubes are connected in an S shape; The radial thickness of the external passive drive heat dissipation part is positively correlated with the motor power.

6. The self-driven cooling device for the integrated interior and exterior of the power adaptive axial flux permanent magnet motor according to claim 5, wherein: The number N of units of the internal actively-driven cooling part / external passively-driven heat dissipation part is the same as the number of rotor magnetic poles; the circumferential span of the units of the internal actively-driven cooling part .

7. The self-driven cooling device for the integrated interior and exterior of the power adaptive axial flux permanent magnet motor according to claim 6, characterized in that: Inner magnetic attraction interfaces are arranged at the outer positions of the inlet section flow channel and the outlet section flow channel, and outer magnetic attraction interfaces are arranged at the positions of the inlet and outlet of the heat dissipation tubes; The inlet section flow channel of the internal active drive cooling part is connected to the outlet of the heat dissipation tubes of the external passive drive heat dissipation part through the matching inner and outer magnetic attraction interfaces to form a sealed magnetic attraction interface part, and the outlet section flow channel of the internal active drive cooling part is connected to the inlet of the heat dissipation tubes of the external passive drive heat dissipation part through the matching inner and outer magnetic attraction interfaces to form a sealed magnetic attraction interface part, so as to realize a highly sealed cooling cycle.

8. The integrated self-driven cooling device for the power adaptive axial flux permanent magnet motor according to claim 7, wherein: The inner magnetic attraction interface is located in the magnetic field and has a lower flow-through pipe, and the lower flow-through pipe is an extension of the inlet section flow channel / outlet section flow channel of the internal active drive cooling part. A main coil is arranged outside the lower flow-through pipe; a plurality of iron core bolt columns extending upward are arranged around the lower flow-through pipe, and a secondary coil is wound around the lower half of the iron core bolt column, and the secondary coil is connected to the main coil; when the cooling medium passes through the lower flow-through pipe from bottom to top, a current will be induced on the main coil and transmitted to the secondary coil, and the secondary coil makes the iron core bolt column magnetic through electric excitation and induces a polarity at the upper end; The outer magnetic attraction interface has an upper flow-through pipe, and the upper flow-through pipe is an extension of the inlet / outlet of the heat dissipation tubes of the external passive drive heat dissipation part. A slot is arranged at the position corresponding to the iron core bolt column on the outer magnetic attraction interface, and a strong magnetic material with a polarity different from that of the end of the iron core bolt column is arranged inside the slot; the slot is communicated with the upper flow-through pipe through an introduction hole below and a lead-out hole above; The interface between the inner magnetic attraction interface and the outer magnetic attraction interface is composed of strong magnetic materials with different magnetic polarities.

9. The self-driven cooling device for the integrated interior and exterior of the power adaptive axial flux permanent magnet motor according to claim 6, characterized in that: An arc-shaped area is formed at the gap between the internal active drive cooling part and the external passive drive heat dissipation part, and an internal and external magnetic isolation heat transfer bridge part is arranged at the arc-shaped area; The internal and external magnetic isolation heat transfer bridge part is closely attached to both the internal active drive cooling part and the external passive drive heat dissipation part, and the internal and external magnetic isolation heat transfer bridge part is used to isolate the internal air gap magnetic field and transfer the heat of the internal active drive cooling part to the external passive drive heat dissipation part by means of heat conduction; The internal and external magnetic isolation heat transfer bridge part includes a composite plate, and the composite plate is laminated by heat-conducting and magnetic-conducting layers and heat-conducting and non-magnetic-conducting layers arranged alternately in the radial direction. At the same time, a plurality of heat-conducting holes are distributed on the composite plate along the circumferential direction, the heat-conducting holes extend radially and penetrate through the composite plate, and the heat-conducting holes are filled with directional heat-conducting columns.

10. The integrated self-driven cooling device for the power adaptive axial flux permanent magnet motor according to claim 1, characterized in that: The Curie temperature of the magnetorheological fluid used as the cooling medium is higher than the hot spot temperature of the motor to avoid demagnetization at high temperatures; the saturation magnetization of the magnetorheological fluid is lower than the air-gap synthetic magnetic field intensity to reduce the consumption of magnetic field energy.

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