A ring-shaped stacked permanent magnet nuclear magnetic resonance device

Abstract

This invention provides a ring-shaped laminated permanent magnet nuclear magnetic resonance (NMR) device. This design addresses eddy current loss, magnetic field stability, and uniformity optimization through modular laminate design and a dynamic rotation mechanism. The device features a split magnet structure: 16 fan-shaped neodymium iron boron laminations block eddy current paths, reducing losses; rotatable magnetic poles dynamically optimize magnetic field uniformity in the imaging area; a closed-loop temperature control system: a bottom fan and top vents form an active heat dissipation channel, combined with a heat-conducting layer to stabilize temperature and suppress thermally induced magnetic field drift; real-time monitoring and control: 24 fiber optic sensors monitor the magnetic field at 15° intervals, working in conjunction with 8 sets of excitation coils for dynamic compensation. The device includes a housing with four support legs fixedly mounted at the bottom. A rotation mechanism is located inside the housing, with a ring-shaped laminated permanent magnet at the top. A fan is mounted on the inner wall of the bottom of the housing, and multiple air inlets are located at the bottom of the housing.

Description

Technical Field

[0001] This utility model relates to the field of nuclear magnetic resonance technology, and in particular to a ring-shaped stacked permanent magnet nuclear magnetic resonance device. Background Technology

[0002] Early nuclear magnetic resonance (NMR) devices used simple water-cooled electromagnets or permanent magnets, resulting in low magnetic field strength (typically below 0.5 Tesla) and poor uniformity, limiting resolution and application range. Permanent magnets were introduced due to their lack of external power supply and low cost; however, early designs were mostly block or C-shaped magnets, exhibiting magnetic field inhomogeneity and temperature drift issues, foreshadowing the later development of toroidal stacked designs. A key background to this stage was the intersection of physics and engineering, which propelled the initial development of magnetic field homogeneity theory. With the widespread application of NMR in chemical analysis and medical imaging (such as MRI), traditional permanent magnets faced problems of low efficiency and high energy consumption. Stacked technology emerged to address this, its core being the division of the magnet into thin slices (stacking), improving magnetic field stability and uniformity by reducing eddy current losses.

[0003] Existing technologies use monolithic ring-shaped permanent magnets, which suffer from severe eddy current losses, poor magnetic field stability, and fixed magnetic pole orientation, making it impossible to optimize the magnetic field uniformity of the imaging area. Utility Model Content

[0004] To address the shortcomings of existing technologies, the present invention provides a ring-shaped permanent magnet nuclear magnetic resonance device. This device features an integral ring-shaped permanent magnet, which suffers from severe eddy current losses, poor magnetic field stability, and a fixed magnetic pole direction, making it impossible to optimize the magnetic field uniformity in the imaging area.

[0005] To achieve the above objectives, this utility model provides:

[0006] A ring-shaped laminated permanent magnet nuclear magnetic resonance device includes a housing with four support legs fixedly installed at the bottom. A rotating mechanism is provided inside the housing, and a ring-shaped laminated permanent magnet is provided at the top of the rotating mechanism. A fan is provided on the bottom inner wall of the housing. Multiple air inlets are provided at the bottom of the housing, and multiple air outlets are provided at the top of the housing. Twenty-four fiber optic sensors are fixedly installed on the inner wall of the housing, with an angle of 15 degrees between every two fiber optic sensors.

[0007] Preferably, the rotating mechanism includes an annular slide rail fixed to the inner wall of the bottom of the housing, an annular slider slidably mounted inside the annular slide rail, an insulating support plate fixedly mounted on the top of the annular slider, and the top of the insulating support plate being fixedly mounted to an annular laminated permanent magnet by insulating adhesive.

[0008] Preferably, an annular bevel gear is sleeved on the outer side of the annular slider, a stepper motor is fixedly installed on the outer side of the housing, a rotating rod is installed on the output shaft of the stepper motor, the rotating rod is rotatably connected to the housing through a bearing, and a bevel gear is fixedly installed on the inner end of the rotating rod, the bevel gear meshing with the annular bevel gear.

[0009] Preferably, the annular laminated permanent magnet comprises multiple annular laminates, which are fixedly connected by insulating adhesive.

[0010] Preferably, the annular stack comprises a NdFeB sector sheet, which includes a surface protective layer, a NdFeB permanent magnet layer, a mica insulating layer, a copper foil thermal conductive layer, and a glass fiber reinforced epoxy resin substrate. The surface protective layer, NdFeB permanent magnet layer, mica insulating layer, copper foil thermal conductive layer, and glass fiber reinforced epoxy resin substrate are fixedly bonded together with insulating adhesive. Dovetail tenons and dovetail grooves are provided on the surface protective layer, NdFeB permanent magnet layer, mica insulating layer, copper foil thermal conductive layer, and glass fiber reinforced epoxy resin substrate. The dovetail tenons and dovetail grooves that are close to each other cooperate to connect the NdFeB sector sheets in an annular manner.

[0011] Preferably, the annular laminated permanent magnet has 8 sets of excitation coils inside.

[0012] Compared with the prior art, the advantages of this utility model are:

[0013] 1. The rotating mechanism is designed with a combination of a ring slide rail and a slider to achieve smooth rotation of the ring-shaped stacked permanent magnet (by the ring slider sliding within the slide rail). Combined with a stepper motor-driven bevel gear meshing system (stepper motor, rotating rod, and bevel gear), it ensures high rotational accuracy (small error) and low power consumption.

[0014] The innovation lies in the application of an insulating support plate (fixed with insulating adhesive), which avoids electromagnetic interference and heat conduction problems during rotation, thereby improving the stability and safety of the device.

[0015] 2. Composite laminated permanent magnet structure: The permanent magnet is composed of multiple ring-shaped laminates, each of which is further divided into NdFeB sector-shaped pieces. Each sector-shaped piece adopts a five-layer composite material design (surface protective layer, NdFeB permanent magnet layer, mica insulation layer, copper foil thermal conductive layer, and glass fiber reinforced epoxy resin substrate), which are bonded together with insulating adhesive.

[0016] The innovation lies in the integration of multiple functions: a mica insulation layer prevents leakage, a copper foil heat-conducting layer enhances heat dissipation efficiency, a glass fiber reinforced substrate provides mechanical strength, and a surface protective layer resists environmental corrosion. This solves the problems of overheating and insufficient insulation in traditional permanent magnets, and improves magnetic field uniformity and lifespan.

[0017] 3. Dovetail tenon-groove connection mechanism: Each neodymium iron boron sector piece is equipped with a dovetail tenon and a dovetail groove, and the sector pieces are connected in a ring shape through the tenon and mortise structure, and fixed with insulating glue.

[0018] Its innovation lies in the fact that the design simplifies the assembly and disassembly process (requiring no complex tools), ensures mechanical robustness between components, and maintains high insulation (avoiding electromagnetic losses caused by metal-to-metal contact). This modular structure facilitates maintenance and customized production.

[0019] 4. Integrated thermal management system: The bottom fan and the multi-hole design (bottom air inlet and top air outlet) form a forced convection heat dissipation path, which, combined with the copper foil heat-conducting layer in the permanent magnet, achieves active cooling.

[0020] The innovation lies in the coordinated operation of the cooling system and the permanent magnet structure (fan-driven airflow draws in from the bottom and exhausts from the top), effectively reducing operating temperature (especially during high-power excitation) and preventing thermal runaway. This is more efficient than passive cooling designs and is suitable for long-term operation.

[0021] 5. High-precision monitoring and magnetic field control: fiber optic sensors are installed on the inner wall of the outer casing, distributed at equal intervals (coverage), in conjunction with the internal excitation coil.

[0022] Innovations include: a fiber optic sensor array that provides real-time magnetic field and temperature monitoring (high resolution, resistant to electromagnetic interference), and an excitation coil group that allows for dynamic magnetic field adjustment (such as compensating for magnetic field fluctuations when a permanent magnet rotates). The combination of these two elements enables closed-loop control, improving the accuracy and adjustability of MRI.

[0023] This invention addresses the issues of eddy current loss, magnetic field stability, and uniformity optimization through a modular stacked design and a dynamic rotation mechanism. The split magnet structure consists of 16 fan-shaped neodymium iron boron laminations (including a mica insulating layer and a copper foil heat-conducting layer) that block eddy current paths, reducing losses. Rotatable magnetic poles are achieved by a stepper motor driving a ring magnet to rotate 360° (15° accuracy), dynamically optimizing the magnetic field uniformity in the imaging area. A closed-loop temperature control system utilizes a bottom fan and top vents to form an active cooling airflow, combined with a heat-conducting layer to stabilize the temperature and suppress thermally induced magnetic field drift. Real-time monitoring and control are achieved through 24 fiber optic sensors monitoring the magnetic field at 15° intervals, working in conjunction with 8 sets of excitation coils to achieve dynamic compensation and improve stability. Attached Figure Description

[0024] Figure 1 This is a sectional structural diagram of the design;

[0025] Figure 2 This is a schematic diagram of the structure of the annular stacked permanent magnet in this design;

[0026] Figure 3 This is a top view of the housing and fiber optic sensor structure of this design;

[0027] Figure 4 This is a schematic diagram of the connection structure of the sixteen NdFeB sector plates in this design;

[0028] Figure 5 This is a schematic diagram of the structure of the surface protective layer, neodymium iron boron permanent magnet layer, mica insulating layer, copper foil thermal conductive layer, and glass fiber reinforced epoxy resin substrate in this design;

[0029] Figure 6 This is a schematic diagram of the structure of the annular slider and the annular bevel gear in this design;

[0030] Figure 7 This is a schematic diagram of the electromagnetic coil in this design.

[0031] In the diagram: 1. Outer shell; 11. Air inlet; 12. Air outlet; 13. Support leg; 2. Rotating mechanism; 21. Insulating support plate; 22. Annular slider; 23. Annular slide rail; 24. Annular bevel gear; 25. Stepper motor; 26. Rotating rod; 27. Bevel gear; 3. Fiber optic sensor; 4. Annular laminated permanent magnet; 41. Neodymium iron boron fan-shaped sheet; 411. Surface protective layer; 412. Neodymium iron boron permanent magnet layer; 413. Mica insulating layer; 414. Copper foil thermal conductive layer; 415. Glass fiber reinforced epoxy resin substrate; 416. Dovetail tenon; 417. Dovetail groove; 5. Excitation coil; 6. Fan. Detailed Implementation

[0032] The embodiments of this utility model will be further described in detail below with reference to the accompanying drawings.

[0033] See Figure 1-7 As shown, a ring-shaped laminated permanent magnet nuclear magnetic resonance device includes a housing 1, four support legs 13 fixedly installed at the bottom of the housing 1, a rotating mechanism 2 inside the housing 1, a ring-shaped laminated permanent magnet 4 at the top of the rotating mechanism 2, a fan 6 on the bottom inner wall of the housing 1, multiple air inlets 11 at the bottom of the housing 1, multiple air outlets 12 at the top of the housing 1, and 24 fiber optic sensors 3 fixedly installed on the inner wall of the housing 1, with an angle of 15 degrees between every two fiber optic sensors 3.

[0034] In this embodiment, the rotating mechanism 2 includes an annular slide rail 23 fixed on the inner wall of the bottom of the outer casing 1. An annular slider 22 is slidably installed inside the annular slide rail 23. An insulating support plate 21 is fixedly installed on the top of the annular slider 22. The top of the insulating support plate 21 is fixedly installed to the annular laminated permanent magnet 4 by insulating glue. An annular bevel gear 24 is sleeved on the outer side of the annular slider 22. A stepper motor 25 is fixedly installed on the outer side of the outer casing 1. A rotating rod 26 is installed on the output shaft of the stepper motor 25. The rotating rod 26 is rotatably connected to the outer casing 1 through a bearing. A bevel gear 27 is fixedly installed on the inner end of the rotating rod 26. The bevel gear 27 meshes with the annular bevel gear 24.

[0035] In this embodiment, the annular laminated permanent magnet 4 includes multiple annular laminates, which are fixedly connected by insulating adhesive. Each annular laminate includes 16 neodymium iron boron (NdFeB) sector-shaped plates 41. Each NdFeB sector-shaped plate 41 includes a surface protective layer 411, a NdFeB permanent magnet layer 412, a mica insulating layer 413, a copper foil thermally conductive layer 414, and a glass fiber reinforced epoxy resin substrate 415. 413. The copper foil thermal conductive layer 414 and the glass fiber reinforced epoxy resin substrate 415 are fixedly bonded together with insulating adhesive. The surface protective layer 411, the neodymium iron boron permanent magnet layer 412, the mica insulating layer 413, the copper foil thermal conductive layer 414 and the glass fiber reinforced epoxy resin substrate 415 are all provided with dovetail tenons 416 and dovetail grooves 417. The dovetail tenons 416 and dovetail grooves 417 are close to each other and cooperate to connect the 16 neodymium iron boron fan-shaped plates 41 in a ring.

[0036] Specifically, the dimensions of the NdFeB sector sheet 41 are: central angle 22.5° (360° / 16), outer diameter 600mm, and inner diameter 400mm.

[0037] In this embodiment, the annular laminated permanent magnet 4 is provided with 8 sets of excitation coils 5 inside.

[0038] Operating mode: When in use, connect the power supply and controller. Dovetail-groove interlocking: 16 overlapping pieces interlock with each other at the ends to form a self-supporting ring structure. Continuous insulation layer coverage: The mica layer overlaps by 0.5mm at the joints to ensure complete eddy current blocking.

[0039] The annular laminated permanent magnet 4 consists of 16 neodymium iron boron sector-shaped plates (1.8T) + a 0.1mm mica insulation layer, which blocks eddy currents and has a temperature rise of ≤3℃. The stepper motor 25 drives the bevel gear 27 to rotate via the rotating rod 26. The bevel gear 27 drives the annular slider 22 to rotate via the annular bevel gear 24. The annular slider 22 slides within the annular slide rail 23. The annular slider 22 drives the annular laminated permanent magnet 4 to rotate 15 degrees via the insulating support plate 21, driving the magnetic ring to rotate (0-30°) and optimizing the magnetic field uniformity in the imaging area. The magnetic field monitoring network has 24 fiber optic sensors (anti-magnetic interference) to generate a 3D field strength map in real time with an accuracy of ±0.001T. The zoned excitation system has 8 sets of excitation coils (embedded in the gaps between the laminates) to actively compensate for weak magnetic field areas (±0.05T). The fan 6 operates for forced air cooling (airflow speed 5m / s) and maintains a constant temperature of ±0.5℃.

[0040] The structural functions of the neodymium iron boron sector sheet 41 are as follows:

[0041] Surface protective layer 411 (0.05mm aluminum nitride ceramic coating) ← Anti-oxidation / mechanical wear;

[0042] Neodymium iron boron permanent magnet layer 412 (10mm thick, N52 grade, 1.8T) ← Main magnetic field source;

[0043] Mica insulation layer 413 (0.1mm, including silicone adhesive) ← blocks eddy currents;

[0044] Copper foil thermal conductive layer 414 (0.05mm, corrugated protrusions) ← Lateral thermal conductivity;

[0045] Fiberglass reinforced epoxy resin substrate 415 (1.5mm) ← Mechanical support.

[0046] This utility model is not limited to the above-described preferred embodiment. Anyone can derive other products in various forms under the guidance of this utility model. However, regardless of any changes made in its shape or structure, any technical solution that is the same as or similar to this utility model is within its protection scope.

Claims

1. A toroidal annular stacked permanent magnet nuclear magnetic resonance apparatus comprising a housing (1) characterised in that: The bottom of the outer shell (1) is fixedly equipped with four support legs (13). The interior of the outer shell (1) is provided with a rotating mechanism (2). The top of the rotating mechanism (2) is provided with an annular stacked permanent magnet (4). The bottom inner wall of the outer shell (1) is provided with a fan (6). The bottom of the outer shell (1) is provided with multiple air inlets (11). The top of the outer shell (1) is provided with multiple air outlets (12). The inner wall of the outer shell (1) is fixedly equipped with 24 fiber optic sensors (3). The included angle between every two fiber optic sensors (3) is 15 degrees.

2. A toroidal gapped permanent magnet nuclear magnetic resonance apparatus as defined in claim 1, characterized in that: The rotating mechanism (2) includes an annular slide rail (23) fixed on the inner wall of the bottom of the outer shell (1). An annular slider (22) is slidably installed in the annular slide rail (23). An insulating support plate (21) is fixedly installed on the top of the annular slider (22). The top of the insulating support plate (21) is fixedly installed to the annular laminated permanent magnet (4) by insulating glue.

3. A toroidal gapped permanent magnet nuclear magnetic resonance apparatus according to claim 2, wherein: The outer side of the annular slider (22) is fitted with an annular bevel gear (24), and the outer side of the outer shell (1) is fixedly installed with a stepper motor (25). A rotating rod (26) is installed on the output shaft of the stepper motor (25). The rotating rod (26) is rotatably connected to the outer shell (1) through a bearing. A bevel gear (27) is fixedly installed at the inner end of the rotating rod (26). The bevel gear (27) meshes with the annular bevel gear (24).

4. A torroidal annular stacked permanent magnet NMR apparatus as defined in claim 1, wherein: The annular laminated permanent magnet (4) includes multiple annular laminates, which are fixedly connected by insulating adhesive.

5. A toroidal gapped permanent magnet nuclear magnetic resonance apparatus as claimed in claim 4, characterized in that: The annular stack includes 16 neodymium iron boron (NdFeB) sector-shaped sheets (41). Each NdFeB sector-shaped sheet (41) includes a surface protective layer (411), a NdFeB permanent magnet layer (412), a mica insulating layer (413), a copper foil thermal conductive layer (414), and a glass fiber reinforced epoxy resin substrate (415). The resin substrates (415) are fixed and bonded together by insulating adhesive. Dovetail tenons (416) and dovetail grooves (417) are provided on the surface protective layer (411), neodymium iron boron permanent magnet layer (412), mica insulating layer (413), copper foil thermal conductive layer (414) and glass fiber reinforced epoxy resin substrate (415). The dovetail tenons (416) and dovetail grooves (417) that are close to each other cooperate to connect the (16) neodymium iron boron fan-shaped pieces (41) in a ring.

6. A torroidal annular stacked permanent magnet NMR apparatus as defined in claim 1, wherein: The annular laminated permanent magnet (4) has 8 sets of excitation coils (5) inside.

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