A passive magnetic levitation vibration isolation device based on high temperature superconductivity
Patent Information
- Application Number
- CN202611113822.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-27
- Publication Date
- 2026-09-15
Smart Images
Figure CN122752467A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of non-contact vibration isolation technology for UAV airborne geophysical sensors, specifically to a passive magnetic levitation vibration isolation device based on high-temperature superconductivity. Background Technology
[0002] Currently, the upper limit of contact vibration isolation is that all passive vibration isolators relying on elastic elements (rubber, steel wire rope, metal spring, MRE) transmit static loads based on physical contact, and residual mechanical coupling cannot be eliminated. The quantum magnetometer and SQUID-type sensors constitute the theoretical noise lower limit.
[0003] Currently, active magnetic bearing (AMB) technology has limitations. While it is widely used in high-speed centrifuges, maglev trains, and flywheel energy storage, AMB stabilizes the levitated body through a closed-loop system of electromagnets, position sensors, and a controller. However, it suffers from three unavoidable problems: ① It requires continuous power to maintain levitation; a power outage causes it to immediately fall, lacking fault tolerance; ② Electromagnetic current fluctuations and PWM switching noise radiate broadband electromagnetic interference (tens of kHz to MHz), severely polluting the magnetometer; ③ The position sensor, power amplifier, and controller constitute a complex electronic link with numerous failure points and limited reliability. These problems prevent AMB from being used for vibration isolation in magnetometer-type sensors. For details, refer to Schweitzer's 2002 paper published at the 6th International Conference on Rotor Dynamics, which systematically analyzes the inherent instability, power-off fall risk, and electromagnetic interference limitations of active magnetic bearings.
[0004] The fundamental physics and current applications of traditional superconducting magnetic levitation, and high-temperature superconducting bulk materials (with Represented by YBCO (with a critical temperature Tc≈92K, and superconductivity achieved at liquid nitrogen temperature of 77K), superconductors exhibit two unique electromagnetic behaviors: the Meissner effect—superconductors completely repel external magnetic fields, causing magnetic field lines to circulate and forming a repulsive force for support; and the flux pinning effect—type II superconductors contain non-superconducting microregions (pinning centers), to which the external magnetic field is "pinned" in the form of magnetic flux vortices, creating the ability to "remember" the magnetic field distribution. This allows the superconductor to self-stabilize and levitate relative to a permanent magnet in any direction (distinct from the lateral instability of pure Meissner levitation). This principle has been applied in engineering fields such as superconducting magnetic levitation trains, superconducting flywheel energy storage, magnetic levitation vibration isolation platforms, and research-grade optical platforms. In 2002, Wang et al. published a study in Physica C, reporting on the world's first manned high-temperature superconducting magnetic levitation test vehicle developed by Southwest Jiaotong University; in 2015, Sotelo completed the construction of a full-scale superconducting magnetic levitation transport line in IEEE Transactions on Applied Superconductivity; in 2003, Ma et al. systematically reviewed the principles and applications of superconductor and permanent magnet levitation devices in Review of Scientific Instruments, confirming that passive magnetic levitation using YBCO bulk material combined with neodymium iron boron permanent magnet tracks has the characteristics of being completely passive, requiring no control, autonomously stable, and frictionless.
[0005] The superconducting magnetic levitation devices mentioned in the literature and engineering applications are all developed for meter-level fixed platforms or rail transportation scenarios. Their liquid nitrogen Dewars are open containers or large-capacity fixed containers (several liters to hundreds of liters), with a total weight ranging from tens of kilograms to several tons, and occupying space ranging from meters to tens of meters. These are unsuitable for UAV airborne conditions in terms of weight, volume, mechanical interfaces, and tolerance to maneuvering acceleration. Furthermore, the aforementioned application scenarios are all ground-based working environments and do not address issues such as liquid nitrogen level disturbances during airborne flight, low-pressure evaporation acceleration, and magnetic flux pinning stability under turbulent conditions. Miniaturizing, lightweighting, and sealing high-temperature superconducting magnetic levitation within the UAV payload envelope (≤2kg, ≤Φ200mm), and maintaining liquid nitrogen cooling and ensuring magnetic levitation stability under maneuvering conditions during flight cycles of 20 minutes to several hours, has not yet been reported in existing technologies. Summary of the Invention
[0006] In view of the above problems, the purpose of this invention is to provide a passive magnetic levitation vibration isolation device based on high-temperature superconductivity, which combines liquid nitrogen cryogenic maintenance, permanent magnet array excitation and field-cooled magnetic flux locking technology to establish a completely contactless, passive self-stabilizing magnetic levitation support vibration isolation device between the sensor load and the UAV fuselage, so as to overcome the shortcomings of the above-mentioned prior art.
[0007] To solve the above-mentioned technical problems, the specific technical solution adopted by the present invention is as follows: A passive magnetic levitation vibration isolation device based on high-temperature superconductivity includes: a vacuum-insulated shell rigidly connected to the fuselage of a UAV via legs; a lower support (fuselage side), an upper support (load side), a liquid nitrogen Dewar cooling cavity (a container filled with liquid nitrogen), a high-temperature superconducting bulk material array, a permanent magnet excitation array, an oxygen-free copper heat sink, a permalloy shielding layer, and a copper eddy current damping plate, all housed within the vacuum-insulated shell. The lower support is fixed to the bottom of the vacuum-insulated shell. The liquid nitrogen Dewar cooling cavity is fixed to the lower support via the oxygen-free copper heat sink. The high-temperature superconducting bulk material array is fixed within the liquid nitrogen Dewar cooling cavity and immersed in liquid nitrogen. The copper eddy current damping plate, the permalloy shielding layer, and the permanent magnet excitation array are sequentially fixed to the lower surface of the upper support. The high-temperature superconducting bulk material array and the permanent magnet excitation array are positioned... Correspondingly, the upper support is magnetically connected to the lower support to form a non-contact magnetic levitation support relationship; the high-temperature superconducting bulk array and the permanent magnet excitation array are magnetically pinned and locked by a field cooling alignment mechanism (establishing a pinned magnetic flux distribution through field cooling process) (based on the magnetic flux pinning effect), so that the upper support and the lower support maintain a non-contact, self-stabilizing magnetic levitation support with a preset working gap; and there is no physical contact path between the upper support and the lower support; the top surface of the vacuum insulation shell is provided with a load interface (mounting surface of the geophysical sensor), and the bottom of the load interface disk is rigidly connected to the upper support directly through the load interface. The upper support and the load interface disk constitute a common levitation body on the load side. The geophysical sensor is installed on the load interface disk, so that the geophysical sensor and the UAV fuselage form a non-contact levitation coupling.
[0008] Among them, the permalloy shielding layer is a high-permeability shielding layer made of high-nickel iron alloy (permalloy), which is used to shield the residual stray magnetic field ≤0.001T at a distance of 50mm from the center of the permanent magnet excitation array.
[0009] As a preferred embodiment of the present invention, the high-temperature superconducting bulk array consists of four sets of rectangularly arranged levitation pivots, and each set of levitation pivots consists of three yttrium barium copper oxide single-domain superconducting blocks (YBCO-123) arranged in a triangular pattern.
[0010] As a preferred embodiment of the present invention, the permanent magnet excitation array comprises four groups of NdFeB-N52 sintered permanent magnets (sintered neodymium iron boron permanent magnet material, grade N52) corresponding to the positions of the high-temperature superconducting bulk material array. Each group of NdFeB-N52 sintered permanent magnets consists of five NdFeB-N52 sintered permanent magnets sequentially spliced in a Halbach array orientation. The permanent magnet excitation array uses NdFeB-N52 material and is arranged in a Halbach array configuration, ensuring that the magnetic field facing the superconductor side is ≥0.5T with a gradient ≥40T / m, and the magnetic field away from the superconductor side is ≤0.05T.
[0011] As a preferred embodiment of the present invention, the cavity wall of the liquid nitrogen Dewar cooling chamber is made of 316L stainless steel double-layer vacuum interlayer, and at least ten layers of heat insulation film are attached inside the double-layer vacuum interlayer. The static heat leakage is ≤0.5W, the single liquid nitrogen filling volume is ≥150mL, and the maintenance time is ≥90 minutes.
[0012] As a preferred embodiment of the present invention, the field cooling alignment mechanism includes four detachable positioning pins, which are shoulder-type pull-out structures; the upper support is provided with a stepped countersunk hole, which includes an upper groove and a lower through hole located below the upper groove, forming a step between the upper groove and the lower through hole; the upper surface of the lower support is provided with a positioning countersunk hole; each detachable positioning pin, from top to bottom, includes an operating cap located above the upper support, a bearing shoulder connected to the operating cap and embedded in the step, a guide section passing through the lower through hole and spanning a preset working gap, and a positioning foot embedded in the positioning countersunk hole; the bearing shoulder... The outer diameter is larger than the diameter of the lower through hole, and the outer diameters of the guide section and the positioning foot are not larger than the diameter of the lower through hole, so that the detachable positioning pin can be pulled out upward as a whole; during field cooling, the load of the upper support is transferred to the lower support in sequence through the bearing shoulder, guide section (rod), and positioning foot and supported by the positioning countersunk hole. The four detachable positioning pins are used to maintain the preset working gap between the yttrium barium copper oxide single-domain superconducting block and the permanent magnet excitation array during the process of liquid nitrogen cooling to the superconducting state. After the liquid nitrogen cooling is completed, the detachable positioning pins are pulled out vertically upward to complete the flux pinning and locking (magnetic flux pinning effect); the preset working gap is 6–10 mm.
[0013] As a preferred embodiment of the present invention, it further includes a liquid nitrogen maintenance and evaporation recovery subsystem, which includes an additional liquid nitrogen storage tank, a supply pipeline, a cryogenic temperature sensor, and a one-way exhaust valve. The additional liquid nitrogen storage tank is used as a liquid nitrogen replenishment tank during the flight of the UAV. The supply pipeline is used to connect the additional liquid nitrogen storage tank and the liquid nitrogen Dewar cooling chamber. The supply pipeline is equipped with a solenoid valve and a throttling orifice. The solenoid valve is used to control the liquid nitrogen replenishment, and the throttling orifice (0.3mm) is used to limit the single replenishment flow rate to ensure that liquid nitrogen flows stably into the liquid nitrogen Dewar cooling chamber. The low-temperature sensor is installed in the liquid nitrogen Dewar cooling chamber near the yttrium barium copper oxide single-domain superconducting block. The low-temperature sensor is used to monitor the heat sink temperature of the yttrium barium copper oxide single-domain superconducting block. When the low-temperature sensor detects that the heat sink temperature has risen to the temperature threshold (85K), it automatically triggers liquid replenishment, and each replenishment is 5mL. The one-way exhaust valve is used to discharge evaporated nitrogen gas through the micro-holes of the one-way valve outside the vacuum insulation shell.
[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention has the advantages of being completely passive and having zero power consumption. The magnetic levitation is naturally formed by the permanent magnetic field and superconductor magnetic flux pinning, without the need for any electrical feedback control. Under normal operating conditions, the power consumption of the device is zero (only the temperature monitoring circuit is at the microwatt level).
[0015] 2. This invention has the advantage of not falling when power is off. Unlike the "loss of control when power is off" of the existing AMB technology, the passive magnetic levitation vibration isolation device will continue to be suspended as long as the liquid nitrogen is maintained in a superconducting state. Even if the entire machine is powered off, the sensor will not fall, which has inherent fault tolerance.
[0016] 3. This invention has the advantage of zero electromagnetic interference. It has no electromagnet, no power amplifier, and no PWM switch. The permanent magnetic field is shielded by Halbach single-sided design and permalloy, and the residual magnetic field interference to the upper sensor is ≤0.001T.
[0017] 4. This invention has the advantages of being non-contact and free of mechanical coupling noise. The working gap is about 8mm, and there is no physical contact path between the load and the machine body. Vibration of the machine body cannot be transmitted to the load through a mechanical path.
[0018] 5. This invention has the advantage of natural synergy with the low-temperature environment of SQUID-type sensors. The SQUID magnetometer itself requires liquid nitrogen or liquid helium cooling. The liquid nitrogen system of the passive magnetic levitation vibration isolation device can simultaneously serve SQUID cooling and magnetic levitation cooling, sharing Dewar resources and reducing the complexity of the overall assembly system.
[0019] 6. This invention can fully meet the preset flight time (≥90 minutes), satisfy the typical single-flight operation cycle of UAV geophysical exploration, and liquid nitrogen can be quickly replenished on site.
[0020] 7. This invention has the advantage of sufficient load-bearing capacity. The total levitation force of the 4 Halbach-YBCO pivots is ≥120N (i.e., 12kg load), which is far higher than the requirements of typical sensors (SQUID magnetometer <3kg, AEM receiving coil <5kg).
[0021] 8. This invention uses embedded attitude damping and passive eddy current damping (copper eddy current damping plate) to reduce underdamped oscillations within 0.5s, preventing continuous load swaying during flight maneuver transitions. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the high-temperature superconducting bulk array in this invention; Figure 3 This is a schematic diagram of the permanent magnet excitation array in this invention; Figure 4This is a schematic diagram of the magnetic field distribution and unilateral pointing characteristics of the permanent magnet excitation array in this invention; Figure 5 This is a schematic diagram of the working process of the field cooling alignment mechanism in this invention; Figure 6 This is a schematic diagram of the liquid nitrogen maintenance and evaporation recovery subsystem in this invention; Figure 7 This is a schematic diagram comparing the oscillation attenuation of damped (solid line) and undamped (dashed line) components in this invention. Figure 8 This is a flowchart illustrating the operation of the device in this invention. Figure 9 This is a schematic diagram of the countersunk shoulder type detachable positioning pin structure of the field cooling alignment mechanism in this invention. Figure 10 This is a schematic diagram of the three working processes of the field cooling alignment mechanism in this invention: ambient temperature bearing, suspension unloading after cooling, and vertical lifting with the cap loosened.
[0023] Reference numerals: 1. Vacuum insulation shell; 2. Lower support; 3. Positioning countersunk hole; 4. Upper support; 5. Upper groove; 6. Lower through hole; 7. Liquid nitrogen Dewar cooling cavity; 8. High-temperature superconducting block array; 9. Yttrium barium copper oxide single-domain superconducting block; 10. Permanent magnet excitation array; 11. NdFeB-N52 sintered permanent magnet; 12. Oxygen-free copper heat sink; 13. Permalloy shielding layer; 14. Copper eddy current damping plate; 15. Field cooling alignment mechanism; 16. Load interface; 17. Load interface disk; 18. Geophysical sensor; 19. Removable positioning pin; 20. Operating cap; 21. Bearing shoulder; 22. Guide section; 33. Positioning foot; 44. Additional liquid nitrogen storage tank; 5. Supply pipeline; 6. Low temperature sensor; 7. One-way exhaust valve; 8. UAV fuselage; 9. Solenoid valve; 10. Throttling orifice. Detailed Implementation
[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the execution process of this invention will be described in detail below with reference to specific embodiments.
[0025] Example 1 See Figure 1-10As shown, this embodiment provides a passive magnetic levitation vibration isolation device based on high-temperature superconductivity, including: a vacuum insulation shell 1 rigidly connected to the fuselage 19 of a UAV via legs; a lower support (fuselage side) 2, an upper support (load side) 3, a liquid nitrogen Dewar cooling cavity (a container filled with liquid nitrogen) 4, a high-temperature superconducting bulk material array 5, a permanent magnet excitation array 6, an oxygen-free copper heat sink 7, a permalloy shielding layer 8, and a copper eddy current damping plate 9, all disposed within the vacuum insulation shell 1; the lower support 2 is fixed to the bottom of the vacuum insulation shell 1; the liquid nitrogen Dewar cooling cavity 4 is fixed to the lower support 2 via the oxygen-free copper heat sink 7; the high-temperature superconducting bulk material array 5 is fixed within the liquid nitrogen Dewar cooling cavity 4 and immersed in liquid nitrogen; the copper eddy current damping plate 9, the permalloy shielding layer 8, and the permanent magnet excitation array 6 are sequentially fixed to the lower surface of the upper support 3; the high-temperature superconducting bulk material array 5 and the permanent magnet excitation array 6 are connected to the lower surface of the upper support 3; and the high-temperature superconducting bulk material array 5 and the permanent magnet excitation array 6 are connected to the lower surface of the upper support 3. The magnetic array 6 is positioned so that the upper support 3 and the lower support 2 form a non-contact magnetic levitation support relationship through magnetic force; the high-temperature superconducting bulk array 5 and the permanent magnet excitation array 6 are magnetically pinned and locked by the field cooling alignment mechanism (establishing the pinned magnetic flux distribution through field cooling process) 10 (based on the magnetic flux pinning effect), so that the upper support 3 and the lower support 2 maintain a non-contact, self-stabilizing magnetic levitation support with a preset working gap; and there is no physical contact path between the upper support 3 and the lower support 2; the top surface of the vacuum insulation shell 1 is provided with a load interface (mounting surface of the geophysical sensor) 11, and the bottom of the load interface disk 12 passes through the load interface 11 and is directly rigidly connected to the upper support 3. The upper support 3 and the load interface disk 12 form a common suspension body on the load side. The geophysical sensor 13 is installed on the load interface disk 12, so that the geophysical sensor 13 and the UAV fuselage form a non-contact levitation coupling.
[0026] In this embodiment, the high-temperature superconducting bulk array 5 consists of four sets of rectangularly arranged levitation pivots. Each set of levitation pivots consists of three yttrium barium copper oxide single-domain superconducting blocks (YBCO-123) 501 arranged in a triangle, for a total of twelve yttrium barium copper oxide single-domain superconducting blocks 501 with a total mass of approximately 450g. The yttrium barium copper oxide single-domain superconducting blocks 501 are prepared using a melt-textured growth (MTG) process. The dimensions of a single yttrium barium copper oxide single-domain superconducting block 501 are Φ30mm × 15mm thick, with a levitation force density ≥10N / cm² (77K, 0.5T external field) and a critical current density Jc ≥5×10⁻⁶. 4 A / cm² (77K, self-field). The yttrium barium copper oxide single-domain superconducting block 501 is fixed on the oxygen-free copper heat sink heat sink base 7 and bonded with Stycast2850 low-temperature epoxy resin to ensure uniform cooling.
[0027] In this embodiment, the permanent magnet excitation array 6 consists of four groups of NdFeB-N52 sintered permanent magnets (sintered neodymium iron boron permanent magnet material, grade N52) 601 corresponding to the positions of the high-temperature superconducting bulk array 5. Each group of NdFeB-N52 sintered permanent magnets 601 is composed of five NdFeB-N52 sintered permanent magnets 601 arranged sequentially in a Halbach array direction (magnetization directions are 0°, 90°, 180°, 270°, and 360° respectively). The permanent magnet excitation array 6 uses NdFeB-N52 material and is arranged in a Halbach array form, so that the magnetic field facing the superconductor side is ≥0.5T and the gradient is ≥40T / m, while the magnetic field away from the superconductor side is ≤0.05T; achieving the design of "magnetic field pointing to the superconductor on one side only". The dimensions of the NdFeB-N52 sintered permanent magnets 601 are 15mm × 15mm × 8mm. To prevent the magnetometer above from being interfered with by the magnetic field of the permanent magnet excitation array 6, the permanent magnet excitation array 6 is covered with a 0.1mm thick permalloy shielding layer 8 on the outside (the side away from the lower support) to further suppress stray magnetic fields to ≤0.001T@50mm.
[0028] The permalloy shielding layer 8 is a high-permeability shielding layer made of high-nickel iron alloy (permalloy) and is used to shield the residual stray magnetic field ≤0.001T at a distance of 50mm from the center of the permanent magnet excitation array 6.
[0029] The array is arranged such that the magnetic field facing the superconductor is ≥0.5T and the gradient is ≥40T / m, while the magnetic field away from the superconductor is ≤0.05T.
[0030] In this embodiment, the liquid nitrogen Dewar cooling chamber 4 has a double-layer vacuum jacket made of 316L stainless steel (316L stainless steel is non-magnetic), with an outer diameter of Φ160mm, a height of 60mm, and a jacket spacing of 8mm. At least ten layers of insulation film (MLI, aluminized polyester film + fiberglass separator) are attached inside the double-layer vacuum jacket. Static heat leakage is ≤0.5W. The liquid nitrogen Dewar cooling chamber 4 is filled with liquid nitrogen (LN2) as the cooling medium, with a filling volume of approximately 150mL, which can maintain the liquid nitrogen temperature of the yttrium barium copper oxide single-domain superconducting block 501 at 77K for ≥90 minutes. A vacuum safety valve (opening pressure 0.15MPa) is installed at the top of the liquid nitrogen Dewar cooling chamber 4 to prevent overpressure from liquid nitrogen vaporization. The nitrogen gas generated by liquid nitrogen evaporation is discharged through the top exhaust port and does not enter the engine compartment.
[0031] In this embodiment, the field-cooling alignment mechanism includes four detachable positioning pins 14, and the four detachable positioning pins 14 are of shoulder-type pull-out structures; the upper support 3 is provided with a stepped countersink, the stepped countersink includes an upper groove 301 and a lower through hole 302 located below the upper groove 301, a step is formed between the upper groove 301 and the lower through hole 302, and a positioning countersink 201 is provided on the upper surface of the lower support 2; each detachable positioning pin 14 sequentially includes, from top to bottom, an operating cap 1401 located above the upper support 3, a bearing shoulder 1402 connected to the operating cap 1401 and embedded in the step, a guiding section 1403 passing through the lower through hole 302 and spanning a preset working gap, and a positioning foot 1404 embedded in the positioning countersink 201; the outer diameter of the bearing shoulder 1402 is larger than the aperture of the lower through hole 302, and the outer diameters of the guiding section 1403 and the positioning foot 1404 are both not larger than the aperture of the lower through hole 302, so that the detachable positioning pin 14 can be entirely pulled out upward; during field cooling, the load of the upper support 3 is sequentially transmitted to the lower support 2 through the bearing shoulder 1402, the guiding section (rod body) 1403 and the positioning foot 1404, and is supported by the positioning countersink 201. The four detachable positioning pins 14 are configured to maintain the preset working gap between the single-domain YBCO superconducting block 501 and the permanent magnet excitation array 6 during the process of cooling the single-domain YBCO superconducting block 501 to the superconducting state with liquid nitrogen, and after the liquid nitrogen cooling is completed, the detachable positioning pins 14 are pulled out upward in the vertical direction to complete flux pinning locking (flux pinning effect); the preset working gap is 6–10 mm.
[0032] Superconducting magnetic levitation requires flux pinning locking established through a field cooling (fieldcooling, FC) process, that is, when the single-domain YBCO superconducting block 501 is in the normal conducting state (T>Tc), a permanent magnetic field is applied first, and then the block is cooled to the superconducting state (T<Tc), so that the flux vortices can "remember" their positions at that time by the pinning centers. The working process of the field-cooling alignment mechanism in this embodiment is as follows: ① During ground preparation, the upper support (load side) 3 and the lower support (airframe side) 2 are fixed at a position with the preset working gap (8 mm) through the four detachable positioning pins 14, that is, the vertical spacing between the upper surface of the high-temperature superconducting bulk array 5 and the lower surface of the permanent magnet excitation array 6 is 8 mm, see Figure 5 part a of Figure 5 ; ② Liquid nitrogen is injected into the liquid nitrogen dewar cooling chamber 4, and cooling is performed for 10 minutes to make the single-domain YBCO superconducting block 501 completely enter the superconducting state, see 5 part b of; ③ The detachable positioning pins 14 are pulled out, and at this time the passive magnetic levitation vibration isolation device automatically enters the flux pinning levitation state, the upper support 3 is self-stably levitated relative to the lower support 2, the vertical stiffness is approximately 1×10 4 N / m, and the lateral stiffness is approximately 3×10 Figure 5 N / m, see Figure 5 part c of; ④ The alignment mechanism is recovered, the device enters a flyable state, see part d of
[0033] The liquid nitrogen maintenance and evaporation recovery subsystem in this embodiment serves as an in-flight replenishment system. Specifically, it includes an additional liquid nitrogen storage tank 15, a supply pipeline 16, a cryogenic temperature sensor 17, and a one-way exhaust valve 18. The additional liquid nitrogen storage tank 15 is used as a liquid nitrogen replenishment tank during UAV flight. The supply pipeline 16 connects the additional liquid nitrogen storage tank 15 to the liquid nitrogen Dewar cooling chamber 4. The supply pipeline 16 is equipped with a solenoid valve 20 and a throttle orifice 21. The solenoid valve 20 controls the on / off flow of liquid nitrogen replenishment, and the throttle orifice (0.3 mm) 18 limits the amount of liquid nitrogen replenished at a time. The flow rate ensures a stable inflow of liquid nitrogen into the liquid nitrogen Dewar cooling chamber 4. A cryogenic temperature sensor (Pt100, 77K grade) 17 is installed in the liquid nitrogen Dewar cooling chamber 4 near the yttrium barium copper oxide single-domain superconducting block 501. The cryogenic temperature sensor 17 monitors the heat sink temperature of the yttrium barium copper oxide single-domain superconducting block 501. When the cryogenic temperature sensor 17 detects that the heat sink temperature has risen to the temperature threshold (85K), it automatically triggers liquid replenishment, with 5mL replenished each time. A one-way exhaust valve 18 is used to discharge evaporated nitrogen gas through the micropores of the one-way valve outside the vacuum insulation shell. Nitrogen gas does not accumulate inside the shell (to avoid the risk of asphyxiation to ground personnel and personnel unrelated to low-altitude reconnaissance). The total liquid nitrogen filling volume (main chamber + storage tank) is 200mL, with a typical sustaining time of 120 minutes (including a 25% safety margin).
[0034] In this embodiment, the passive magnetic levitation between the high-temperature superconducting bulk array and the permanent magnet excitation array exhibits inherent oscillation modes (vertical mode ≈ 8Hz, lateral mode ≈ 5Hz, and swaying mode ≈ 3Hz), which can lead to underdamped oscillations under flight disturbances. This embodiment addresses this by adding an attitude damping auxiliary subsystem, which employs a passive eddy current damping scheme: a 3mm thick copper eddy current damping plate 9 is fixed below the upper support (load side) 3. When the copper eddy current damping plate 9 moves relative to the stray magnetic field of the permanent magnet excitation array 6, it generates eddy currents that dissipate energy, providing a damping ratio of approximately 0.15–0.25 for the passive magnetic levitation vibration isolation device, controlling the oscillation mode decay time to <0.5s. Eddy current damping is completely passive, with no power consumption, no electronic components, and no interference.
[0035] In this embodiment, the vacuum insulation shell 1 has an outer diameter of Φ200mm, a height of 140mm, and a total mass (including a full load of liquid nitrogen) of ≤1.8kg. The vacuum insulation shell 1 is composed of a carbon fiber shell consisting of multiple layers of non-magnetic carbon fiber (non-magnetic, low density, high rigidity).
[0036] In this embodiment, for flight safety considerations, the total liquid nitrogen filling volume of the device is ≤200mL, and the total mass of the yttrium barium copper oxide single-domain superconducting block 501 + NdFeB-N52 sintered permanent magnet 601 + copper eddy current damping plate 9 is controlled within a total mass envelope of 1.8kg. To ensure flight safety, the device design includes: ① The vacuum safety valve at the top of the liquid nitrogen Dewar cooling chamber 4 automatically opens to release pressure when the pressure inside the chamber exceeds 0.15MPa, preventing vaporization overpressure from causing structural damage; ② The exhaust port is equipped with an anti-backflow one-way valve and a hydrophobic bend structure to prevent liquid nitrogen droplets from splashing out under maneuvering conditions; ③ A temperature indicator (reversibly color-changing) is added to the outer surface of the vacuum insulation shell 1 to facilitate ground personnel in quickly determining whether the device is in a low-temperature state and avoid accidental activation; ④ The entire device undergoes MIL-STD-810G conducted vibration, maneuvering acceleration (3g for 10s), and drop tests (1m free fall) to verify structural integrity and magnetic levitation stability.
[0037] In this embodiment, when the passive magnetic levitation vibration isolation device is used in conjunction with the liquid nitrogen high-temperature SQUID magnetometer, the liquid nitrogen Dewar cooling chamber 4 and the SQUID's own low-temperature Dewar share the bottom cold stage interface, so that a single cooling system can simultaneously serve magnetic levitation and SQUID cooling.
[0038] Example 2 This embodiment uses a DJI M600Pro hexacopter drone equipped with an aviation electromagnetic receiving coil (1.2kg, Φ100mm ring shape) as the application scenario.
[0039] Includes the following steps: Step 1. Assembly of high-temperature superconducting bulk array 5: Purchase 4 sets of 12 yttrium barium copper oxide single-domain superconducting blocks (MTG-YBCO bulk material) 501, with dimensions of Φ30mm×15mm and a measured levitation density of 10.5N / cm²@77K@0.5T; use Stycast2850 to bond them to the oxygen-free copper heat sink 7, with 3 blocks in each set arranged in a 120° triangular array.
[0040] Step 2. Assembly of permanent magnet excitation array 6: Purchase 60120 pieces of NdFeB-N52 sintered permanent magnets (15×15×8mm), splice 4 groups of 5 pieces / group in the Halbach direction, cover with 0.1mm permalloy shielding layer 8, and use a gaussmeter to check that the residual magnetism on the upper surface is <0.05T.
[0041] Step 3. Preparation of liquid nitrogen Dewar cooling chamber 4: The chamber is made of 316L stainless steel with a double-layer outer diameter of Φ160mm and a height of 60mm, and 10 layers of MLI are attached; the bottom of the chamber is fixed with oxygen-free copper heat sink 7; the top of the chamber has liquid nitrogen filling port, exhaust port and temperature sensor interface.
[0042] Step 4. Establishment of the field cooling alignment mechanism 10: Assemble the complete device on the ground. The upper support 3 and the lower support 2 are fixed with 4 M3 shoulder-type detachable positioning pins 14 at an 8mm working gap. Inject 150mL of liquid nitrogen into the liquid nitrogen Dewar cooling chamber 4. The reading of the Pt100 low temperature sensor 17 is stabilized at 77.2K for 3 minutes. Pull out the 4 detachable positioning pins 14 vertically upwards. The upper support 3 is self-stabilized and suspended. The suspension gap is measured to be 7.98mm using a ranging laser, with a stability of ±0.05mm.
[0043] Step 5. Payload Installation and Flight Test: The AEM receiving coil is installed onto the upper support interface panel; it is then fully installed into the M600Pro payload bay; four consecutive flights are conducted (25 minutes each), completing a total of 100 minutes of operation. The residual liquid nitrogen is 15 mL (replenished twice as planned, 5 mL each time); the measured vibration noise RMS of the geophysical sensor (AEM receiving coil) has decreased from 28 μV under traditional rubber vibration isolation to 2.3 μV, a reduction of approximately 12 times; the baseline drift of the received signal has decreased to 1 / 8 of its original value.
[0044] Step 6. Ground reset: After the mission is completed, the device lands and the upper support 3 and lower support 2 automatically fall back to the limit elastic block (there is no impact at the moment of contact because the suspension stiffness has provided a buffer); disassemble and clean, the liquid nitrogen Dewar can be reused.
[0045] Example 3 This embodiment is for the flight survey application of the cryogenic SQUID magnetometer (liquid nitrogen high-temperature type, operating temperature 77K, payload mass approximately 2.5kg). The number of suspension fulcrums has been increased from 4 to 6 (arranged in a hexagonal pattern), expanding the total suspension force to 180N. The liquid nitrogen Dewar cooling chamber 4 shares a bottom cooling platform structure with the SQUID's own liquid nitrogen Dewar (sharing an interface, but the cooling chamber is independent), reducing the complexity of the overall assembly system. During flight testing, the SQUID sensitivity maintained its nominal value of 15fT / √Hz and did not deteriorate due to fuselage vibration.
[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Those skilled in the art can make various modifications and variations to the present invention without departing from its principles. Any modifications, equivalent substitutions, and improvements made within the principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A passive magnetic levitation vibration isolation device based on high temperature superconductivity, characterized in that, include: A vacuum-insulated shell is rigidly connected to the bottom of the drone fuselage. Inside the vacuum-insulated shell are a lower support, an upper support, a liquid nitrogen Dewar cooling chamber, a high-temperature superconducting bulk material array, a permanent magnet excitation array, an oxygen-free copper heat sink, a permalloy shielding layer, and a copper eddy current damping plate. The lower support is fixed to the bottom of the vacuum-insulated shell. The liquid nitrogen Dewar cooling chamber is fixed to the lower support via the oxygen-free copper heat sink. The high-temperature superconducting bulk material array is fixed inside the liquid nitrogen Dewar cooling chamber. The copper eddy current damping plate, permalloy shielding layer, and permanent magnet excitation array are sequentially fixed to the lower surface of the upper support. The high-temperature superconducting bulk material array and the permanent magnet excitation array... The magnetic array positions correspond, enabling the upper support to form a non-contact magnetic levitation support relationship with the lower support through magnetic force; the high-temperature superconducting bulk array and the permanent magnet excitation array are magnetically pinned and locked by a field cooling alignment mechanism, so that the upper support and the lower support maintain a non-contact, self-stabilizing magnetic levitation support with a preset working gap; the top surface of the vacuum insulation shell is provided with a load interface, and the bottom of the load interface disk is directly and rigidly connected to the upper support through the load interface. The upper support and the load interface disk form a common levitation body on the load side. Geophysical sensors are installed on the load interface disk, so that the geophysical sensors and the UAV fuselage form a non-contact levitation coupling.
2. A passive magnetic levitation vibration isolation device based on high temperature superconductivity according to claim 1, characterized in that, The high-temperature superconducting bulk array consists of four sets of rectangularly arranged levitation pivots, and each set of levitation pivots consists of three yttrium barium copper oxide single-domain superconducting blocks arranged in a triangle.
3. A passive magnetic levitation vibration isolation device based on high temperature superconductivity according to claim 1, characterized in that, The permanent magnet excitation array consists of four groups of NdFeB-N52 sintered permanent magnets corresponding to the positions of the high-temperature superconducting bulk material array. Each group of NdFeB-N52 sintered permanent magnets consists of five NdFeB-N52 sintered permanent magnets sequentially spliced in the Halbach array direction.
4. A passive magnetic levitation vibration isolation device based on high temperature superconductivity according to claim 1, characterized in that, The wall of the liquid nitrogen Dewar cooling chamber is made of a double-layer vacuum interlayer, and at least ten layers of heat insulation film are attached to the double-layer vacuum interlayer.
5. A passive magnetic levitation vibration isolation device based on high temperature superconductivity according to claim 1, characterized in that, The field cooling alignment mechanism includes four detachable positioning pins; the upper support is provided with a stepped countersunk hole, the stepped countersunk hole including an upper groove and a lower through hole located below the upper groove, forming a step between the upper groove and the lower through hole, and the upper surface of the lower support is provided with a positioning countersunk hole; each of the detachable positioning pins, from top to bottom, includes an operating cap located above the upper support, a bearing shoulder connected to the operating cap and embedded in the step, a guide section passing through the lower through hole and spanning a preset working gap, and a positioning foot embedded in the positioning countersunk hole; the bearing shoulder The outer diameter of the guide section is larger than the diameter of the lower through hole, and the outer diameters of the guide section and the positioning foot are not larger than the diameter of the lower through hole, so that the detachable positioning pin can be pulled out upward as a whole. During field cooling, the load of the upper support is transferred to the lower support in sequence through the bearing shoulder, guide section and positioning foot and supported by the positioning countersunk hole. The four detachable positioning pins are used to maintain the preset working gap between the yttrium barium copper oxide single-domain superconducting block and the permanent magnet excitation array during the process of liquid nitrogen cooling to the superconducting state. After the liquid nitrogen cooling is completed, the detachable positioning pin is pulled out vertically upward to complete the magnetic flux pinning and locking.
6. A high temperature superconductor based passive magnetic levitation vibration isolation device according to claim 1, wherein, It also includes a liquid nitrogen maintenance and evaporation recovery subsystem, which includes an additional liquid nitrogen storage tank, supply pipeline, cryogenic temperature sensor, and one-way exhaust valve; The additional liquid nitrogen storage tank is used as a liquid nitrogen replenishment tank during the flight of the UAV. The supply pipeline is used to connect the additional liquid nitrogen storage tank and the liquid nitrogen Dewar cooling chamber. The supply pipeline is equipped with a solenoid valve and a throttle orifice. The solenoid valve is used to control the liquid nitrogen replenishment flow. The throttle orifice is used to limit the single replenishment flow rate to ensure that liquid nitrogen flows stably into the liquid nitrogen Dewar cooling chamber. The cryogenic temperature sensor is installed in the liquid nitrogen Dewar cooling chamber near the yttrium barium copper oxide single-domain superconducting block. The cryogenic temperature sensor is used to monitor the heat sink temperature of the yttrium barium copper oxide single-domain superconducting block. When the cryogenic temperature sensor detects that the heat sink temperature has risen to the temperature threshold, it automatically triggers liquid replenishment. The one-way exhaust valve is used to discharge evaporated nitrogen gas outside the vacuum insulation shell.