Magnetic suspension fan permanent magnet heat dissipation structure, working method and permanent magnet forming method

Abstract

The invention discloses a magnetic suspension fan permanent magnet heat dissipation structure, a working method and a permanent magnet forming method.The heat dissipation structure comprises a permanent magnet, a gradually-expanding heat dissipation channel is formed in the permanent magnet in the magnetization direction, and the inner wall of the permanent magnet is provided with a multi-stage reducing structure, a V-shaped micro groove and a titanium nitride coating; the grooves are filled with magnetorheological gel layers containing silver-plated iron powder and the like, and shape memory alloy microwires are embedded in the grooves; the cooling medium circulating system comprises a pressurizing device, a liquid storage device and the like, balanced distribution and collection of multi-channel cooling media are achieved through an annular dispersing main pipe and a collecting main pipe, during work, the electromagnetic excitation device strengthens heat transfer, phase change of the shape memory alloy microwires strengthens disturbance when the permanent magnets are overheated, and accurate preparation is achieved through the forming method through the steps of green body forming, sintering and the like.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of magnetic suspension fans, in particular to a magnetic suspension fan permanent magnet heat dissipation structure, a working method and a permanent magnet forming method. BACKGROUND

[0002] In a magnetic suspension fan, a permanent magnet serves as a core component, and a large amount of heat is generated during the working of the permanent magnet. If the heat cannot be dissipated in time, the temperature of the permanent magnet will rise, thereby causing the risk of demagnetization of the permanent magnet, reducing the performance and reliability of the fan, and seriously affecting the normal operation and service life of the magnetic suspension fan.

[0003] In the prior art, some permanent magnet heat dissipation structures adopt simple air cooling or liquid cooling. The air cooling method is greatly affected by environmental factors, and the heat dissipation efficiency is limited, so it is difficult to meet the heat dissipation requirements of high-power magnetic suspension fans. Although the liquid cooling method has good heat dissipation effect, the traditional structure has problems such as unreasonable design of the heat dissipation channel, insufficient heat exchange between the cooling medium and the permanent magnet, and the like, and cannot realize efficient heat dissipation. Therefore, there is an urgent need for a permanent magnet heat dissipation structure that can effectively improve the heat dissipation efficiency and realize intelligent control. SUMMARY

[0004] The purpose of the present application is to provide a magnetic suspension fan permanent magnet heat dissipation structure, a working method and a permanent magnet forming method, which solve the heat dissipation bottleneck problem of the permanent magnet of the magnetic suspension fan under high-power working conditions.

[0005] Technical scheme:

[0006] A magnetic suspension fan permanent magnet heat dissipation structure comprises:

[0007] A permanent magnet, which is internally provided with a plurality of heat dissipation channels, and the inner wall of the heat dissipation channel is provided with a multi-stage variable-diameter structure;

[0008] The wall surface of the heat dissipation channel is distributed with V-shaped micro grooves, and the surface of the micro grooves is covered with a titanium nitride wear-resistant coating;

[0009] A solid-liquid phase change magnetorheological gel layer is filled in the V-shaped micro grooves and covers the wall surface of the heat dissipation channel, and the magnetorheological gel layer comprises an interpenetrating network gel matrix formed by polyurethane and perfluoropolyether, silver-plated iron powder magnetic particles, and nanocellulose for enhancing the gel network structure;

[0010] Shape memory alloy micro wires are embedded in the magnetorheological gel layer, and the phase transition temperature of the shape memory alloy micro wires matches the working temperature threshold of the permanent magnet;

[0011] A cooling medium circulation system is used to transport a cooling medium containing magnetic nanoparticles.

[0012] Further, the circulation system comprises:

[0013] A pressurizing device is used to pressurize and deliver the cooling medium to the inlet of the heat dissipation channel;

[0014] The liquid storage device is equipped with a cooling device that automatically adjusts the cooling power according to the return temperature of the cooling medium;

[0015] An electromagnetic excitation device is installed near the entrance of the heat dissipation channel to generate a magnetic field that causes magnetic nanoparticles in the cooling medium to align in an orientation to form a microstructure that enhances heat transfer.

[0016] Pressure pulsation suppressor;

[0017] Piping systems using flexible metal corrugated pipes.

[0018] Furthermore, the included angle of the V-shaped microgrooves is 50°-70°, a Ti-OC covalent bond layer is formed at the interface between the titanium nitride coating and the magnetorheological gel layer, and the surface of the covalent bond layer is subjected to nanoscale roughening treatment.

[0019] Furthermore, the cooling medium is a 50% ethylene glycol aqueous solution containing 1-2% Fe3O4 nanoparticles with a particle size of 20-30nm, the silver-plated iron powder magnetic particles have a particle size of 5±1μm and a volume fraction of 35-40%, and the nanocellulose has a mass fraction of 2-3%.

[0020] Furthermore, the multi-stage variable diameter structure includes at least one expansion section with a diameter larger than the channel inlet and outlet, and the length of the expansion section accounts for 15%-35% of the total length of the heat dissipation channel.

[0021] Furthermore, the liquid storage device is equipped with an ultrasonic vibrator for periodically dispersing nanoparticle agglomerates in the cooling medium.

[0022] Furthermore, the shape memory alloy microwires are NiTi alloys with a phase transition temperature of 70±2℃; the volume fraction of the microwires in the magnetorheological gel layer is 0.8-1.2%.

[0023] This invention also discloses a method for operating a permanent magnet heat dissipation structure for a magnetic levitation fan, comprising the following steps:

[0024] S1. The cooling medium is pressurized by a pressurizing device and then delivered to the inlet of the gradually expanding heat dissipation channel;

[0025] S2. Start the electromagnetic excitation device to generate a magnetic field, causing the magnetic nanoparticles in the cooling medium to align in a direction to form a heat transfer-enhancing microstructure, thereby enhancing heat exchange within the heat dissipation channel.

[0026] S3. When the temperature of the permanent magnet reaches the phase transition temperature of the shape memory alloy microwire, the shape memory alloy microwire undergoes a phase transition, which enhances the disturbance of the cooling medium in the heat dissipation channel.

[0027] S4. The cooling medium, after absorbing heat, flows out from the outlet of the gradually expanding heat dissipation channel, returns to the liquid storage device through the pipeline system of the circulation system, and is cooled down by the cooling device in the liquid storage device that automatically adjusts the cooling power before entering the circulation again.

[0028] This invention also discloses a method for forming the permanent magnet of the above-mentioned magnetic levitation fan, comprising the following steps:

[0029] S1. Green blank forming: The neodymium iron boron magnetic powder is mixed with the binder and injected into the mold. The mold is equipped with a detachable heat dissipation channel forming mandrel. The pressure is maintained at 80-120MPa and 150-180℃ for 10-15 minutes to form a permanent magnet green blank with a heat dissipation channel structure.

[0030] S2. Sintering treatment: Place the green blank in a vacuum sintering furnace, heat it to 1050-1100℃ at 5-8℃ / min, introduce argon-hydrogen mixed protective gas, and hold for 2-4 hours.

[0031] S3. Isostatic pressing: When the temperature of the sintered body drops to 600-650℃, it is transferred to a hot isostatic pressing furnace, and 150-200MPa argon pressure is applied and held for 1-2 hours.

[0032] S4. Channel surface treatment: V-shaped microgrooves are etched on the inner wall of the channel using femtosecond laser processing with a laser wavelength of 1030nm and a pulse energy of 0.5-1mJ; a 3-5μm thick titanium nitride coating is deposited on the surface of the groove by magnetron sputtering with a sputtering power of 5-8kW and a substrate temperature of 300-400℃.

[0033] S5. Gel layer filling: The magnetorheological gel precursor is injected into the channel and solidified under a magnetic field of 0.1-0.3T, while shape memory alloy microwires are embedded.

[0034] Furthermore, the femtosecond laser employs a helical feed with a pitch 1.2-1.5 times the groove depth, and the argon-hydrogen mixed protective gas contains 95±1% argon and 5±1% hydrogen.

[0035] Beneficial effects: By using a gradually expanding multi-stage variable diameter channel and a V-shaped microgroove synergistic design, the problems of high flow resistance and insufficient heat exchange area in traditional straight channels are solved; by using magnetically controlled nanofluid directional arrangement and microfilament phase change disturbance, the industry problem of local overheating of permanent magnets is overcome. Attached Figure Description

[0036] Figure 1 This is the three-dimensional representation of the present invention. Figure 1 ;

[0037] Figure 2 This is the three-dimensional representation of the present invention. Figure 2 ;

[0038] Figure 3 This is a three-dimensional view of the permanent magnet of the present invention;

[0039] Figure 4 This is a structural diagram of the permanent magnet heat dissipation channel of the present invention;

[0040] Figure 5 This is a flowchart illustrating the working method of the magnetic levitation fan permanent magnet heat dissipation structure of the present invention;

[0041] Figure 6 This is a flowchart of the molding method for the permanent magnet of the magnetic levitation fan of the present invention. Detailed Implementation

[0042] To make the technical solution of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] Example 1

[0044] like Figures 1-4 As shown, a permanent magnet heat dissipation structure for a magnetic levitation fan includes:

[0045] The permanent magnet 1 has multiple heat dissipation channels 2 inside, and the inner wall of the heat dissipation channel 2 is provided with a multi-stage variable diameter structure. The heat dissipation channel is preferably arranged along the magnetization direction. By setting the multi-stage variable diameter structure, when the cooling medium flows through the expansion section, the flow velocity decreases and the pressure increases, forming local eddies, thereby enhancing the heat exchange between the cooling medium and the permanent magnet and improving the heat dissipation efficiency.

[0046] The heat dissipation channel 2 has V-shaped micro-grooves 3 distributed on its wall surface, and the surface of the micro-grooves 3 is covered with a titanium nitride wear-resistant coating 31.

[0047] A solid-liquid phase change magnetorheological gel layer 4 is filled in the V-shaped microgroove 3 and covers the wall of the heat dissipation channel 2. The magnetorheological gel layer contains an interpenetrating network gel matrix formed by polyurethane and perfluoropolyether, silver-plated iron powder magnetic particles, and nanocellulose for enhancing the gel network structure.

[0048] Shape memory alloy microwires are embedded in the magnetorheological gel layer, and the phase transition temperature of the shape memory alloy microwires matches the operating temperature threshold of the permanent magnet.

[0049] Cooling medium circulation system 5 is used to transport cooling medium containing magnetic nanoparticles.

[0050] Furthermore, the circulation system 5 includes:

[0051] The pressurizing device 51 is used to pressurize and deliver the cooling medium to the inlet of the heat dissipation channel; it uses a miniature magnetically driven centrifugal pump to pressurize and deliver the cooling medium to the inlet of the heat dissipation channel.

[0052] The liquid storage device 52 is equipped with a cooling system that automatically adjusts the cooling power based on the return temperature of the cooling medium; a custom-made small titanium alloy container is used. Internally, it integrates a high-precision digital temperature sensor and a miniature semiconductor cooling chip, achieving precise temperature control of the cooling medium through a PID controller. It is also equipped with a miniature ultrasonic vibrator to disperse nanoparticle agglomerates, ensuring the stability of the cooling medium's performance.

[0053] An electromagnetic excitation device 53 is installed near the entrance of the heat dissipation channel to generate a magnetic field to cause the magnetic nanoparticles in the cooling medium to align in an orientation to form a microstructure that enhances heat transfer. The frequency of the excitation magnetic field avoids the magnetic domain resonance frequency of the permanent magnet (usually <100Hz) and adopts a high-frequency excitation of 200-300Hz to reduce the magnetic coupling effect.

[0054] Pressure pulsation suppressor 54; a silicon-based pulsation suppressor manufactured using microelectromechanical systems (MEMS) technology, with an integrated elastic diaphragm structure, which can control pressure fluctuations within ±10 kPa, reduce the impact of pressure fluctuations on heat dissipation, and ensure the stability of cooling medium flow.

[0055] The piping system 55, which uses flexible metal corrugated pipes, has a miniature O-ring sealing structure at the connection with the permanent magnet to ensure the system's sealing and reliability, while also being able to adapt to certain vibrations and displacements to prevent pipe damage and leakage.

[0056] The cooling medium circulation system also includes an inlet annular dispersion main pipe and an outlet annular collection main pipe respectively located at the upper and lower ends of the permanent magnet. The inlet annular dispersion main pipe is connected to a pressurizing device to evenly distribute the cooling medium to the inlets of each heat dissipation channel; the outlet annular collection main pipe is connected to a liquid storage device to collect the cooling medium from the outlets of each heat dissipation channel. Through the design of the annular dispersion main pipe and the collection main pipe, the balanced distribution and efficient collection of the multi-channel cooling medium are achieved, further improving the overall heat dissipation efficiency.

[0057] Furthermore, the included angle of the V-shaped microgrooves 3 is 50°-70°, and a Ti-OC covalent bonded layer is formed at the interface between the titanium nitride coating and the magnetorheological gel layer. The surface of the covalent bonded layer undergoes nanoscale roughening treatment. Within this angle range, the V-shaped microgrooves can effectively guide the flow of the cooling medium and enhance fluid turbulence while increasing the heat dissipation area. The formation of the Ti-OC covalent bonded layer at the interface between the titanium nitride coating and the magnetorheological gel layer, and the nanoscale roughening treatment of the surface of the covalent bonded layer, significantly enhances the bonding force between the titanium nitride coating and the magnetorheological gel layer, prevents coating peeling, and further increases the heat dissipation area, thereby improving heat dissipation performance.

[0058] Furthermore, the cooling medium is a 50% ethylene glycol aqueous solution containing 1-2% Fe3O4 nanoparticles with a particle size of 20-30 nm. The silver-plated iron powder magnetic particles have a particle size of 5±1 μm and a volume fraction of 35-40%, while the nanocellulose has a mass fraction of 2-3%. The interpenetrating network gel matrix formed by polyurethane and perfluoropolyether endows the magnetorheological gel layer with good flexibility and stability. The silver-plated iron powder magnetic particles give the magnetorheological gel layer magnetic response characteristics, allowing it to change its properties under the influence of a magnetic field. The nanocellulose enhances the gel network structure, improving the strength and durability of the magnetorheological gel layer. Simultaneously, the Fe3O4 nanoparticles added to the cooling medium can significantly improve the thermal conductivity of the cooling medium, further enhancing the heat dissipation effect.

[0059] Furthermore, the multi-stage variable diameter structure includes at least one expansion section with a diameter larger than the channel inlet and outlet, and the length of the expansion section accounts for 15%-35% of the total length of the heat dissipation channel.

[0060] Furthermore, the liquid storage device 52 is equipped with an ultrasonic vibrator for periodically dispersing nanoparticle agglomerates in the cooling medium.

[0061] Furthermore, the shape memory alloy microwires are NiTi alloys with a phase transition temperature of 70±2℃; the volume fraction of the microwires in the magnetorheological gel layer is 0.8-1.2%. When the temperature of the permanent magnet reaches the phase transition temperature of the shape memory alloy microwires, the microwires undergo a phase transition, changing their shape and enhancing the disturbance of the cooling medium in the heat dissipation channel, thereby achieving the purpose of intelligently regulating the heat dissipation effect.

[0062] The heat dissipation structure of this invention is particularly suitable for permanent magnets with magnetization direction along the axial direction. The heat dissipation channel is arranged axially through the permanent magnet, with its inlet and outlet located at the upper and lower end faces of the permanent magnet, respectively. This layout achieves efficient heat dissipation without affecting the radial installation gap between the permanent magnet and the rotor, ensuring the compactness and stability of the overall structure of the magnetic levitation fan. By coordinating the design of the heat dissipation channel with the magnetization direction of the permanent magnet, interference with the main magnetic circuit is avoided, and the heat conduction path is optimized by utilizing the axial temperature gradient characteristics.

[0063] Example 2

[0064] like Figure 5 As shown, the present invention also discloses a method for operating a permanent magnet heat dissipation structure for a magnetic levitation fan, comprising the following steps:

[0065] S1. The cooling medium is pressurized by a pressurizing device and then delivered to the inlet of the gradually expanding heat dissipation channel;

[0066] S2. Start the electromagnetic excitation device to generate a magnetic field, causing the magnetic nanoparticles in the cooling medium to align in a direction to form a heat transfer-enhancing microstructure, thereby enhancing heat exchange within the heat dissipation channel.

[0067] S3. When the temperature of the permanent magnet reaches the phase transition temperature of the shape memory alloy microwire, the shape memory alloy microwire undergoes a phase transition, which enhances the disturbance of the cooling medium in the heat dissipation channel.

[0068] S4. The cooling medium, after absorbing heat, flows out from the outlet of the gradually expanding heat dissipation channel, returns to the liquid storage device through the pipeline system of the circulation system, and is cooled down by the cooling device in the liquid storage device that automatically adjusts the cooling power before entering the circulation again.

[0069] Example 3

[0070] like Figure 6 As shown, the present invention also discloses a method for forming the permanent magnet of the above-mentioned magnetic levitation fan, comprising the following steps:

[0071] S1. Green blank forming: Neodymium iron boron magnetic powder is mixed with binder and injected into mold. The mold is equipped with a detachable heat dissipation channel forming mandrel. The pressure is held at 80-120MPa and 150-180℃ for 10-15 minutes to form a permanent magnet green blank with heat dissipation channel structure.

[0072] S2. Sintering treatment: Place the green blank in a vacuum sintering furnace, heat it to 1050-1100℃ at 5-8℃ / min, introduce argon-hydrogen mixed protective gas, and hold for 2-4 hours.

[0073] S3. Isostatic pressing: When the temperature of the sintered body drops to 600-650℃, it is transferred to a hot isostatic pressing furnace, and 150-200MPa argon pressure is applied and held for 1-2 hours.

[0074] S4. Channel surface treatment: V-shaped microgrooves are etched on the inner wall of the channel using femtosecond laser processing with a laser wavelength of 1030nm and a pulse energy of 0.5-1mJ; a 3-5μm thick titanium nitride coating is deposited on the surface of the groove by magnetron sputtering with a sputtering power of 5-8kW and a substrate temperature of 300-400℃.

[0075] S5. Gel layer filling: The magnetorheological gel precursor is injected into the channel and solidified under a magnetic field of 0.1-0.3T, while shape memory alloy microwires are embedded.

[0076] Furthermore, the femtosecond laser employs a helical feed with a pitch 1.2-1.5 times the groove depth, and the argon-hydrogen mixed protective gas contains 95±1% argon and 5±1% hydrogen.

[0077] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A permanent magnet heat dissipation structure for a magnetic levitation fan, characterized in that, include: A permanent magnet, wherein the permanent magnet has multiple heat dissipation channels inside, and the inner wall of the heat dissipation channels is provided with a multi-stage variable diameter structure; The heat dissipation channel wall is distributed with V-shaped microgrooves, and the surface of the microgrooves is covered with a titanium nitride wear-resistant coating. A solid-liquid phase change magnetorheological gel layer is filled in the V-shaped microgroove and covers the heat dissipation channel wall. The magnetorheological gel layer includes an interpenetrating network gel matrix formed by polyurethane and perfluoropolyether, silver-plated iron powder magnetic particles, and nanocellulose for enhancing the gel network structure. Shape memory alloy microwires are embedded in the magnetorheological gel layer, and the phase transition temperature of the shape memory alloy microwires matches the operating temperature threshold of the permanent magnet. A cooling medium circulation system is used to transport cooling medium containing magnetic nanoparticles.

2. The permanent magnet heat dissipation structure for a magnetic levitation fan according to claim 1, characterized in that, The circulatory system includes: A pressurizing device is used to pressurize and deliver the cooling medium to the inlet of the heat dissipation channel; The liquid storage device is equipped with a cooling device that automatically adjusts the cooling power according to the return temperature of the cooling medium; An electromagnetic excitation device is installed near the entrance of the heat dissipation channel to generate a magnetic field that causes magnetic nanoparticles in the cooling medium to align in an orientation to form a microstructure that enhances heat transfer. Pressure pulsation suppressor; Piping systems using flexible metal corrugated pipes.

3. The permanent magnet heat dissipation structure for a magnetic levitation fan according to claim 1, characterized in that, The included angle of the V-shaped microgrooves is 50°-70°, and a Ti-OC covalent bond layer is formed at the interface between the titanium nitride coating and the magnetorheological gel layer. The surface of the covalent bond layer is subjected to nanoscale roughening treatment.

4. The permanent magnet heat dissipation structure for a magnetic levitation fan according to claim 1, characterized in that, The cooling medium is a 50% ethylene glycol aqueous solution containing 1-2% Fe3O4 nanoparticles with a particle size of 20-30nm, the silver-plated iron powder magnetic particles have a particle size of 5±1μm and a volume fraction of 35-40%, and the nanocellulose has a mass fraction of 2-3%.

5. The permanent magnet heat dissipation structure for a magnetic levitation fan according to claim 1, characterized in that, The multi-stage variable diameter structure includes at least one expansion section with a diameter larger than the channel inlet and outlet, and the length of the expansion section accounts for 15%-35% of the total length of the heat dissipation channel.

6. The permanent magnet heat dissipation structure for a magnetic levitation fan according to claim 1, characterized in that, The liquid storage device is equipped with an ultrasonic vibrator for periodically dispersing nanoparticle agglomerates in the cooling medium.

7. The permanent magnet heat dissipation structure for a magnetic levitation fan according to claim 1, characterized in that, The shape memory alloy microwires are NiTi alloys with a phase transition temperature of 70±2℃; the volume fraction of the microwires in the magnetorheological gel layer is 0.8-1.2%.

8. A method for operating the permanent magnet heat dissipation structure of a magnetic levitation fan as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. The cooling medium is pressurized by a pressurizing device and then delivered to the inlet of the gradually expanding heat dissipation channel; S2. Start the electromagnetic excitation device to generate a magnetic field, causing the magnetic nanoparticles in the cooling medium to align in a direction to form a heat transfer-enhancing microstructure, thereby enhancing heat exchange within the heat dissipation channel. S3. When the temperature of the permanent magnet reaches the phase transition temperature of the shape memory alloy microwire, the shape memory alloy microwire undergoes a phase transition, which enhances the disturbance of the cooling medium in the heat dissipation channel. S4. The cooling medium, after absorbing heat, flows out from the outlet of the gradually expanding heat dissipation channel, returns to the liquid storage device through the pipeline system of the circulation system, and is cooled down by the cooling device in the liquid storage device that automatically adjusts the cooling power before entering the circulation again.

9. A method for forming a permanent magnet for a magnetically levitated fan as described in claim 1, characterized in that, Includes the following steps: S1. Green blank forming: Neodymium iron boron magnetic powder is mixed with binder and injected into mold. The mold is equipped with a detachable heat dissipation channel forming mandrel. The pressure is held at 80-120MPa and 150-180℃ for 10-15 minutes to form a permanent magnet green blank with heat dissipation channel structure. S2. Sintering treatment: Place the green blank in a vacuum sintering furnace, heat it to 1050-1100℃ at 5-8℃ / min, introduce argon-hydrogen mixed protective gas, and hold for 2-4 hours. S3. Isostatic pressing: When the temperature of the sintered body drops to 600-650℃, it is transferred to a hot isostatic pressing furnace, and 150-200MPa argon pressure is applied and held for 1-2 hours. S4. Channel surface treatment: V-shaped microgrooves are etched on the inner wall of the channel using femtosecond laser processing with a laser wavelength of 1030nm and a pulse energy of 0.5-1mJ; a 3-5μm thick titanium nitride coating is deposited on the surface of the groove by magnetron sputtering with a sputtering power of 5-8kW and a substrate temperature of 300-400℃. S5. Gel layer filling: The magnetorheological gel precursor is injected into the channel and solidified under a magnetic field of 0.1-0.3T, while shape memory alloy microwires are embedded.

10. The method for forming a permanent magnet for a magnetic levitation fan according to claim 9, characterized in that, The femtosecond laser uses a helical feed with a pitch of 1.2-1.5 times the groove depth. The argon-hydrogen mixed protective gas has an argon content of 95±1% and a hydrogen content of 5±1%.

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