A bottom-mounted disc type axial flux magnetic force stirring device and a working method thereof

Abstract

This invention relates to a bottom-centered disc-type axial flux magnetic stirring device, comprising an axial flux disc-type magnetic coupling positioned at the center of the inner bottom of a stirring tank. The coupling includes, from bottom to top, an outer rotor assembly, an isolation sleeve, and an inner rotor assembly. An agitator assembly is connected to the inner rotor assembly, and a motor drive assembly is connected to the outer rotor assembly. The inner / outer rotor assemblies are equipped with several circumferentially distributed, axially magnetized inner / outer rotor magnets, with the N and S poles of the magnets alternating circumferentially. An isolation sleeve is positioned between the inner and outer rotor assemblies to form a sealed isolation, and a vertical mandrel for vertically mounting the inner rotor assembly is fixedly mounted on the isolation sleeve. A thrust bearing is also provided between the vertical mandrel of the isolation sleeve and the outer rotor assembly. This invention optimizes the amount of magnets used, improves magnet utilization, significantly reduces manufacturing costs, and exhibits significant economic benefits. It also simplifies the equipment structure, reduces the number of parts, and lowers assembly and maintenance difficulty.

Description

Technical Field

[0001] This invention relates to a bottom-centered disc-type axial magnetic flux stirring device and its working method, and relates to the field of stirring equipment technology. Background Technology

[0002] Magnetic stirrers, as a non-contact transmission stirring device, are widely used in the stirring of flammable, explosive, toxic, and highly corrosive materials due to their advantages such as good sealing performance, no leakage, and stable operation. They occupy an indispensable position in industries such as chemical, food, pharmaceutical, and water treatment. Traditional magnetic stirrers mostly use radial magnetic flux magnetic couplings, with the magnets radially magnetized. The magnets of the inner and outer rotors are arranged radially, and the non-contact transmission of power is achieved through radial magnetic attraction. This structural form has been the mainstream design in the industry since the advent of magnetic stirrers. However, this type of traditional magnetic stirrer has many technical defects in practical applications, making it difficult to meet the requirements of modern industrial production for efficient, stable, reliable, and structurally simplified stirring equipment. The specific defects are as follows, and these defects are interconnected, forming a vicious cycle that seriously restricts the improvement of equipment performance and industrial application.

[0003] First, traditional radial flux magnetic stirrers suffer from extremely low magnet utilization, resulting in significant magnet waste and high manufacturing costs. Due to the structural characteristics of radial flux magnetic circuits, magnetic flux transmission involves multiple stages, including the rotor body and air gaps, leading to substantial magnetic circuit losses, typically ranging from 40% to 60%. To ensure sufficient transmission torque for stirring operations, a large number of radially magnetized magnets are required, usually 12-20 pairs (24-40 individual magnets). This magnet usage far exceeds the actual effective work required. For example, a certain model of traditional radial flux magnetic stirrer requires 16 pairs (32 individual) of radially magnetized neodymium iron boron magnets to achieve a transmission power of 5.5kW. However, the effective work contribution of these magnets is only 30%-40%, with the remaining 60%-70% serving only as auxiliary magnetic circuit closure, resulting in a severe waste of magnet resources. Meanwhile, the extensive use of magnets not only significantly increases the manufacturing cost of the equipment but also results in larger and heavier magnetic couplings, hindering miniaturization and bottom-center installation. This is particularly problematic for small mixing tanks, limiting the equipment's application range. Furthermore, the increased use of magnets also increases the assembly difficulty of the magnetic coupling, making it difficult to guarantee assembly accuracy. This further affects magnetic circuit transmission efficiency, creating a vicious cycle of "increased magnet usage - increased size - decreased assembly accuracy - reduced magnetic efficiency - need for further increases in magnet usage."

[0004] Secondly, traditional radial flux magnetic stirrers have extremely complex structures with numerous parts, making assembly and maintenance difficult and costly. The radially arranged magnets require complex rotor supports, magnet mounting bases, protective sleeves, and other components. Furthermore, to ensure the stability of the radial magnetic circuit and prevent magnetic flux leakage, multiple layers of magnetic shielding and positioning components are needed on the outside of the rotor, resulting in a greater number of parts compared to this invention. For example, the outer rotor of a traditional radial flux magnetic coupling requires multiple parts, including a radial magnet support, an outer ring protective sleeve, and an axial positioning bearing. In contrast, the axial flux disc-type outer rotor of this invention only requires three core components: a flange, an outer rotor shaft, and an outer rotor magnet disc, significantly simplifying the structure. Simultaneously, the complex structure leads to cumbersome assembly procedures and long assembly cycles. In addition, subsequent maintenance is difficult and costly. When magnets demagnetize, wear, or parts malfunction, a large number of parts need to be disassembled for repair and replacement, resulting in long maintenance times, high maintenance costs, and the risk of damaging other parts during maintenance, further increasing the operating cost of the equipment and reducing its overall cost-effectiveness. In addition, the rotor radial dimension of traditional radial flux magnetic couplings is large, which makes them poorly compatible with the bottom-center installation space of the mixing tank. To achieve bottom-center installation, a lot of structural modifications to the bottom of the mixing tank are required, such as increasing the size of the mounting flange and reinforcing the bottom structure. This not only increases the installation cost but also reduces the original structural strength of the mixing tank. It has extremely poor versatility and is difficult to adapt to mixing tanks of different specifications and types.

[0005] Furthermore, traditional magnetic stirrers suffer from extremely poor operational stability, exhibiting significant vibration and oscillation, resulting in severe equipment wear and a short service life. The radial flux circuit generates substantial radial eccentric force when transmitting torque. This eccentric force causes noticeable vibration and oscillation during rotor rotation, especially at high speeds (≥500 r / min), where the vibration amplitude typically reaches 0.2-0.5 mm. Vibration not only affects stirring efficiency, leading to uneven material mixing and increased dead zones, but also accelerates the wear of equipment components such as bearings, seals, and the stirring shaft. Bearings wear faster, seals have shorter lifespans, and the stirring shaft is prone to bending and deformation, severely impacting the equipment's lifespan. Furthermore, the isolation sleeves of traditional magnetic stirrers are mostly thin-walled structures, typically 2-5mm thick, and are only fixed by flanges at both ends, lacking an effective intermediate support structure. During stirring operations, the isolation sleeves are prone to deformation, bulging, or even rupture due to the reaction force of the material being stirred, the radial eccentric force of the rotor, and equipment vibration. This can lead to seal failure and material leakage, posing a significant safety hazard, especially when stirring flammable, explosive, or toxic materials. Industry statistics show that the failure rate of isolation sleeves in traditional magnetic stirrers is as high as 25%-35%, making it one of the main causes of equipment failure.

[0006] Based on this, in order to solve the above technical problems, this case proposes a bottom-centered disc type axial magnetic flux stirring device and its working method. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is to provide a bottom-centered disc type axial magnetic flux stirring device and its working method.

[0008] To solve the above-mentioned technical problems, the technical solution of the present invention is: a bottom-centered disc-type axial magnetic flux magnetic stirring device, including an axial magnetic flux disc-type magnetic coupling disposed in the middle position of the inner bottom of the stirring tank, the axial magnetic flux disc-type magnetic coupling including an outer rotor assembly, an isolation sleeve, and an inner rotor assembly arranged sequentially from bottom to top, a stirrer assembly connected to the inner rotor assembly, and a motor drive assembly connected to the outer rotor assembly; The outer rotor assembly is equipped with several axially magnetized outer rotor magnets arranged in a circular pattern, with the N poles and S poles of the outer rotor magnets arranged alternately in a circular pattern. The inner rotor assembly is equipped with several axially magnetized inner rotor magnets arranged in a circular pattern, with the N poles and S poles of the inner rotor magnets arranged alternately in a circular pattern. The isolation sleeve is disposed between the inner and outer rotor assemblies to form a sealed isolation, and a vertical spindle for vertically mounting the inner rotor assembly is fixedly disposed on the isolation sleeve. A thrust bearing is also disposed between the vertical spindle of the isolation sleeve and the outer rotor assembly.

[0009] Preferably, the outer rotor assembly includes a flange for fixedly connecting to the frame of the motor drive assembly, and an outer rotor component is rotatably connected to the flange and coaxially fixedly connected to the motor connecting shaft of the motor drive assembly. The outer rotor magnets are all disposed on the outer rotor component.

[0010] Preferably, the outer rotor component includes an outer rotor shaft and an outer rotor magnet disk fixedly disposed at the top of the outer rotor shaft. A rolling bearing is installed between the outer rotor shaft and the flange. The bottom end of the outer rotor shaft is coaxially and fixedly connected to the motor connecting shaft. The outer rotor magnets are installed one-to-one in the outer rotor magnet mounting slots opened on the top surface of the outer rotor magnet disk.

[0011] Preferably, the thrust bearing is disposed between the vertical spindle of the outer rotor magnet disk and the isolation sleeve, with the upper ring of the thrust bearing fixed to the isolation sleeve and the lower ring fixed to the outer rotor magnet disk.

[0012] Preferably, the isolation sleeve includes an isolation cover, which covers the outer rotor magnets on the outer rotor assembly from top to bottom inside, and the isolation cover is fixedly connected to the flange on the outer rotor assembly. The vertical spindle is fixedly positioned at the middle of the horizontal isolation end face at the top of the isolation cover.

[0013] Preferably, a jacket is provided inside the periphery of the isolation cover, and a coolant inlet and a coolant outlet are connected to the jacket.

[0014] Preferably, the inner rotor assembly includes an inner rotor component, the top of which is coaxially and fixedly connected to the bottom end of the stirring shaft provided on the stirrer assembly, and the inner rotor magnets are installed one-to-one in the inner rotor magnet mounting grooves opened on the bottom surface of the inner rotor component; the inner rotor component has a vertically arranged inner rotor shaft hole in the middle, and the vertical spindle is coaxially arranged in the inner rotor shaft hole.

[0015] Preferably, a sliding bearing is provided between the inner rotor shaft hole and the vertical spindle, including a male sliding bearing mounted on the upper and lower parts of the vertical spindle and a female sliding bearing mounted on the upper and lower parts of the inner rotor shaft hole. The upper male sliding bearing and the upper female sliding bearing are matched and installed together, and the lower male sliding bearing and the lower female sliding bearing are matched and installed together. The bottom sealing end face of the lower male sliding bearing is provided with an O-ring seal. A sliding sleeve is provided between the upper and lower male sliding bearings and is fitted on the vertical spindle. The sealing end faces of the upper and lower ends of the sliding sleeve are also provided with O-rings. The sleeve is assembled and installed on the vertical spindle with the upper and lower male sliding bearings respectively, and is fastened by a fastening bolt screwed to the top of the vertical spindle.

[0016] Preferably, the inner bottom of the mixing tank is provided with an installation port, and the outer peripheral edge of the isolation sleeve is fixed to the installation port by welding. The welding is argon arc welding, and the weld is free of pores and cracks.

[0017] A method for operating a bottom-mounted disc-type axial magnetic flux stirring device includes the following steps: After the motor drive assembly is started, the variable frequency speed-regulating motor on it outputs power according to the set speed, and the power is transmitted to the outer rotor assembly, driving the outer rotor assembly to rotate around the axis; the N poles and S poles of several outer rotor magnets on the outer rotor magnetic steel disc are arranged alternately around the circumference, forming a uniform axial magnetic flux circuit during rotation, which acts on several inner rotor magnets on the inner rotor assembly through magnetic attraction, driving the inner rotor assembly to rotate synchronously. Since the inner rotor assembly is connected to the stirrer assembly, it drives the stirrer assembly to rotate, thereby realizing the stirring operation of the material in the stirring tank.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. Optimized magnet usage, improved magnet utilization, and significantly reduced manufacturing costs, resulting in substantial economic benefits: This invention abandons the traditional radial magnetic flux circuit structure and innovatively adopts an axial magnetic flux disc-type magnetic coupling. This fundamentally solves the technical pain points of high magnetic loss and large magnet usage in traditional radial magnetic flux circuits, significantly reducing magnet usage and manufacturing costs. Simultaneously, the magnetic flux in the axial magnetic flux circuit is transmitted axially, resulting in lower magnetic circuit losses and a reduced loss rate. This significantly increases the effective work ratio of the magnets, improving magnet utilization and avoiding the waste of magnet resources in traditional radial magnetic flux structures. Furthermore, the magnet design of this invention ensures uniform magnetic circuit distribution and increased magnetic flux density, further enhancing magnet utilization and transmission efficiency, resulting in extremely significant economic advantages.

[0019] 2. Significantly simplified equipment structure, reduced number of parts, lower assembly and maintenance difficulty, and improved assembly efficiency and overall cost-effectiveness: The axial flux disc magnetic coupling of this invention has a disc structure. The magnetic flux of the axial flux circuit is transmitted axially, eliminating the need for complex radial rotor supports, magnet fixing seats, outer protective sleeves, and other components found in traditional radial flux structures. The inner and outer rotor structures of this invention are simple, consisting only of core components, reducing the number of parts compared to traditional radial flux magnetic stirrers. The assembly process is simple, assembly accuracy is easy to ensure, assembly time is shortened, and assembly efficiency is improved. Simultaneously, the thrust bearing of this invention achieves the dual functions of rotational guidance and isolation sleeve support, eliminating the need for additional isolation sleeve support components, further reducing the number of parts and structural complexity. During later maintenance, only a few parts need to be disassembled to complete the replacement of magnets, bearing inspection, and seal replacement, resulting in shorter maintenance time, lower maintenance costs, and reduced maintenance efficiency. Compared to the complex maintenance process of traditional equipment, the convenience of maintenance of this invention is significantly improved. In addition, the disc-type magnetic coupling has a small radial dimension and a smaller radial diameter than traditional equipment, making it well-suited for installation in the bottom center of the mixing tank. It does not require extensive modifications to the bottom of the mixing tank or the equipment itself, making it highly versatile and easy to install, further enhancing the overall cost-effectiveness of the equipment.

[0020] 3. Improve equipment operation stability, reduce vibration and wear, extend equipment service life, and have significant reliability advantages: The axial magnetic flux circuit design of this invention makes the magnetic attraction force distributed along the axial direction, and there is no obvious radial eccentric force during rotation, which effectively avoids the vibration and swaying phenomenon of rotor rotation in traditional radial magnetic flux structures, and greatly improves the operation stability of the equipment.

[0021] 4. Strengthen the structural strength of the isolation sleeve, improve sealing reliability, and completely solve the technical problem of easy failure of traditional isolation sleeves: The thrust bearing of this invention realizes the multi-functional innovative design of the thrust bearing. The thrust bearing not only plays the role of stabilizing and guiding the rotation of the outer rotor, but also forms axial and radial dual support for the isolation sleeve. It effectively prevents the isolation sleeve from deforming, bulging or even breaking due to the reaction force of the material, the radial eccentric force of the rotor rotation and the vibration of the equipment during operation. It is especially suitable for stirring operations of flammable, explosive, toxic and highly corrosive materials, and greatly improves the safety of operation.

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0023] Figure 1 This is a schematic diagram illustrating the structure of an embodiment of the present invention.

[0024] Figure 2 for Figure 1 A magnified view of part A.

[0025] Figure 3 This is a schematic diagram of the external rotor assembly.

[0026] Figure 4 This is a schematic diagram of the magnet distribution in the inner / outer rotor assembly.

[0027] Figure 5 Schematic diagram of the isolation sleeve Figure 1 .

[0028] Figure 6 Schematic diagram of the isolation sleeve Figure 2 .

[0029] Figure 7 This is a schematic diagram of the internal rotor assembly.

[0030] In the diagram: 1. Axial flux disc type magnetic coupling; 2. Outer rotor assembly; 3. Isolation sleeve; 4. Inner rotor assembly; 5. Agitator assembly; 6. Motor drive assembly; 7. Outer rotor magnet; 8. Inner rotor magnet; 9. Vertical spindle; 10. Thrust bearing; 11. Frame of motor drive assembly; 12. Flange; 13. Motor connecting shaft; 14. Outer rotor shaft; 15. Outer rotor magnet disc; 16. Rolling bearing; 17. Outer rotor magnet mounting slot; 18. Jacket; 19. Coolant inlet; 20. Coolant outlet; 21. Inner rotor component; 22. Agitator shaft; 23. Inner rotor magnet mounting slot; 24. Inner rotor shaft hole; 25. Upper male sliding bearing; 26. Upper female sliding bearing; 27. Lower male sliding bearing; 28. Lower female sliding bearing; 29. ​​O-ring; 30. Sliding sleeve; 31. Inner tank bottom; 32. Mounting port; 33. Variable frequency speed control motor; 34. Agitator blade. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0032] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0033] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0034] like Figures 1-7 As shown, this embodiment provides a bottom-center axial flux magnetic stirring device, suitable for bottom-center installation scenarios of various mixing tanks. It includes an axial flux disc magnetic coupling 1 set in the middle of the inner bottom of the mixing tank. The axial flux disc magnetic coupling is the core transmission component of the stirring device, replacing the magnetic coupling of the traditional radial flux magnetic circuit, fundamentally solving the technical problems of high magnetic loss and large amount of magnets in the traditional radial flux magnetic circuit. The axial flux disc magnetic coupling includes an outer rotor assembly 2, an isolation sleeve 3, and an inner rotor assembly 4 arranged sequentially from bottom to top. The stirrer assembly 5 is connected to the inner rotor assembly, and the outer rotor assembly is connected to the output end of the motor drive assembly 6. The outer rotor assembly is equipped with several axially magnetized outer rotor magnets 7 arranged in a circular pattern. The N poles and S poles of the several outer rotor magnets are arranged alternately in a circular pattern, and the magnets are configured in 8 pairs, totaling 16 pieces. The inner rotor assembly is equipped with several axially magnetized inner rotor magnets 8 arranged in a circular pattern. The N poles and S poles of the inner rotor magnets are arranged alternately in a circular pattern, and the magnets are configured in 8 pairs, totaling 16 pieces. This configuration and arrangement of magnets can form a uniform and efficient axial magnetic flux circuit. The magnetic flux is transmitted along the axial direction, and the magnetic circuit loss is greatly reduced. Compared with the traditional radial magnetic flux structure, the amount of magnets used is reduced and the utilization rate of magnets is improved under the same transmission torque.

[0035] The isolation sleeve is disposed between the inner and outer rotor assemblies to form a sealed isolation, and a vertical spindle 9 for vertically mounting the inner rotor assembly is also fixedly disposed on the isolation sleeve. A thrust bearing 10 is also disposed between the vertical spindle of the isolation sleeve and the outer rotor assembly.

[0036] The axial air gap between the magnets of the inner and outer rotor assemblies is controlled at 0.5-3mm to ensure efficient transmission of axial magnetic flux. Compared with traditional radial magnetic flux couplings, the amount of magnets used is reduced and the utilization rate of magnets is improved under the same transmission torque.

[0037] The isolation sleeve is a thin-walled stainless steel sleeve, preferably made of 316L stainless steel, with a tensile strength ≥520MPa, a yield strength ≥205MPa, and a thickness of 1-3mm. Compared with traditional isolation sleeves, the thickness is reduced and the weight is lighter.

[0038] Traditional magnetic stirrers lack proper integration of the thrust bearing, resulting in limited functionality and insufficient overall reliability. While some traditional equipment incorporates a thrust bearing, it merely guides the rotor rotation, failing to fully utilize its structural characteristics to support the isolation sleeve. This inadequate reinforcement of the isolation sleeve's structural strength leads to its susceptibility to deformation and failure. This invention, with the support of the thrust bearing, significantly enhances the isolation sleeve's resistance to deformation. The axial support force provided by the thrust bearing is 500-2000N, and the radial support force is 300-1500N, effectively preventing deformation and bulging during operation. This extends the isolation sleeve's service life, improves sealing reliability, and completely resolves the material leakage problems caused by the deformation and cracking of traditional isolation sleeves.

[0039] The thrust bearing is a double-direction thrust ball bearing with a precision grade of P5. It provides stable guidance for the rotation of the outer rotor, reducing vibration and sway during rotor rotation. It also supports the isolation sleeve, strengthening its structural strength and preventing deformation and bulging. This multi-functional integration of the thrust bearing simplifies the equipment structure and improves overall reliability. Its rolling elements are made of silicon nitride ceramic with a hardness ≥ HRC65, enhancing wear resistance.

[0040] This invention features a bottom-center installation design, suitable for bottom-center installation of various vertical mixing tanks. It requires no major modifications to the mixing tank, making installation convenient. It is compatible with mixing tanks with a volume range of 1-50m³ and can be widely used in mixing operations in multiple industries such as chemical, food, pharmaceutical, bioengineering, water treatment, and metallurgy.

[0041] In this embodiment of the invention, the outer rotor assembly includes a flange 12 for fixed connection to the frame 11 of the motor drive assembly. An outer rotor component is rotatably connected to the flange and is coaxially fixedly connected to the motor connection shaft 13 of the motor drive assembly. The outer rotor magnets are all disposed on the outer rotor component.

[0042] In this embodiment of the invention, the outer rotor component includes an outer rotor shaft 14 and an outer rotor magnet disk 15 fixedly disposed at the top of the outer rotor shaft. A rolling bearing 16 is installed between the outer rotor shaft and the flange. The bottom end of the outer rotor shaft is coaxially and fixedly connected to the motor connecting shaft through a coupling. The outer rotor magnets are installed one-to-one in the outer rotor magnet mounting slots 17 opened on the top surface of the outer rotor magnet disk.

[0043] The outer rotor magnet disc is made of high-strength aluminum alloy with a tensile strength of ≥380MPa. Compared with the traditional cast iron rotor, it is lighter, has a lower moment of inertia, and improves the dynamic response speed of the equipment.

[0044] In this embodiment of the invention, the thrust bearing is positioned at the midpoint between the outer rotor magnet disk and the vertical spindle of the isolation sleeve. The upper ring of the thrust bearing is fixed to the isolation sleeve, and the lower ring is fixed to the outer rotor magnet disk.

[0045] This invention relates to a thrust bearing that features a multi-functional and innovative design. The thrust bearing not only serves to guide the rotation of the outer rotor, but also provides axial and radial support to the isolation sleeve. This effectively prevents the isolation sleeve from deforming, bulging, or even breaking due to the reaction force of the material, the radial eccentric force of the rotor rotation, and equipment vibration during operation. It is especially suitable for mixing flammable, explosive, toxic, and highly corrosive materials, significantly improving operational safety.

[0046] In this embodiment of the invention, the isolation sleeve includes an isolation cover, which covers the outer rotor magnets on the outer rotor assembly from top to bottom inside, and the isolation cover is fixedly connected to the flange on the outer rotor assembly. The vertical spindle is fixedly located at the middle position of the horizontal isolation end face at the top of the isolation cover, and the horizontal isolation end face is relatively thin.

[0047] In this embodiment of the invention, due to the lack of an effective cooling structure in traditional magnetic stirrers, the axial flux disc magnetic coupling generates a large amount of eddy current heat during operation. If this heat is not removed in time, it can lead to demagnetization of the magnets due to high temperatures, with a demagnetization rate as high as 10%-15%, affecting the magnetic circuit transmission efficiency. Therefore, this invention provides a jacket 18 inside the periphery of the isolation cover. The jacket is connected to a coolant inlet 19 and a coolant outlet 20. The cooling medium is cooling water or cooling oil, which can remove the eddy current heat generated during the operation of the axial flux disc magnetic coupling in time, keeping the magnet operating temperature below 80°C, preventing demagnetization of the magnets due to high temperatures, reducing the demagnetization rate, and ensuring the long-term stability of the magnetic circuit. Compared with traditional uncooled or simple cooling structures (usually only using natural cooling or small fan cooling), the cooling of this invention can effectively control the magnet operating temperature, extend the continuous operation time of the equipment, and meet the continuous operation requirements of industrial production.

[0048] In this embodiment of the invention, the inner rotor assembly includes an inner rotor component 21. The top of the inner rotor component is coaxially and fixedly connected to the bottom end of the stirring shaft 22 provided on the agitator assembly, with a coaxiality error not exceeding 0.02 mm. The fixed connection is made by sanitary bolts. The bolts are high-strength stainless steel bolts, numbering 8-16. Each bolt is equipped with an O-ring, with a preload torque of 50-150 N·m. All O-rings are made of fluororubber or food-grade silicone, adapting to the material requirements of different industries. This achieves a welded seal at the bottom of the mixing tank, ensuring zero leakage and completely preventing material leakage. It is especially suitable for mixing flammable, explosive, toxic, and highly corrosive materials.

[0049] The inner rotor magnets are installed one-to-one in the inner rotor magnet mounting slots 23 opened on the bottom surface of the inner rotor component; the inner rotor component has a vertical inner rotor shaft hole 24 in the middle, and the vertical spindle is coaxially arranged in the inner rotor shaft hole.

[0050] The inner rotor component is made of high-strength aluminum alloy, the same material as the outer rotor magnet disk. The magnet ring composed of several inner rotor magnets corresponds coaxially with the magnet ring composed of several outer rotor magnets, with a coaxiality error not exceeding 0.03mm.

[0051] Meanwhile, aluminum alloy has low magnetic permeability (≤1μH / m), which effectively reduces magnetic flux leakage in the magnetic circuit, further improving the utilization rate of the magnets and reducing magnetic flux leakage. In addition, aluminum alloy has good thermal conductivity (≥150W / (m·K), which can quickly transfer the heat generated during the operation of the magnets to the cooling structure. Together with the cooling structure, it can achieve efficient heat dissipation, further preventing the magnets from demagnetizing due to high temperature and ensuring the stability of the magnetic circuit. Compared with traditional cast iron rotors, aluminum alloy rotors are lighter, which not only reduces the overall weight of the equipment, making it easier to install and transport, but also reduces the load on the motor, reducing energy consumption and demonstrating significant energy-saving effects.

[0052] In this embodiment of the invention, a sliding bearing is provided between the inner rotor shaft hole and the vertical spindle, including a male sliding bearing mounted on the upper and lower parts of the vertical spindle and a female sliding bearing mounted on the upper and lower parts of the inner rotor shaft hole. The upper male sliding bearing 25 and the upper female sliding bearing 26 are matched and installed together, and the lower male sliding bearing 27 and the lower female sliding bearing 28 are matched and installed together. The entire sliding bearing has a two-section structure to ensure the coaxiality of the machining. The bottom sealing end face of the lower male sliding bearing is provided with an O-ring 29 for sealing. A sliding sleeve 30 is provided between the upper and lower male sliding bearings and is fitted on the vertical spindle. The sealing end faces of the upper and lower ends of the sliding sleeve are also provided with O-rings, which are respectively combined and installed with the upper and lower male sliding bearings on the vertical spindle and fastened by fastening bolts screwed to the top of the vertical spindle.

[0053] In this embodiment of the invention, the inner bottom 31 of the mixing tank is provided with an installation port 32, and the top edge of the outer periphery of the isolation cover of the isolation sleeve is fixed to the installation port by welding. The welding is argon arc welding, and the weld is free of pores and cracks.

[0054] In this embodiment of the invention, the motor of the motor drive assembly is a variable frequency speed control motor 33. The output speed is 0-1000 r / min, with a speed regulation accuracy of ±1 r / min. It can achieve stepless speed regulation according to the viscosity of the material and the stirring requirements, and is suitable for materials with a viscosity range of 1-10000 mPa·s. It can achieve good results whether mixing low-viscosity liquids, stirring high-viscosity pastes, or stirring corrosive or food-grade materials. The agitator is connected to the outer rotor via a flexible coupling made of rubber elastomer with a damping ratio ≥0.3, effectively buffering vibrations generated during rotor rotation with a vibration attenuation rate ≥60%. A vibration sensor is installed on the motor housing with a measurement accuracy of ±0.01mm, electrically connected to the control system of the variable frequency speed control motor to achieve real-time monitoring of the agitator's operating status. When the vibration value exceeds the set threshold (0.1mm), the control system automatically reduces the motor speed or issues an alarm signal with a response time ≤0.5s, improving the operational safety of the equipment and reducing the failure rate. Compared to traditional equipment without monitoring structures, the operational reliability of the equipment is improved.

[0055] In this embodiment of the invention, the agitator assembly has multiple layers of agitator blades 34 arranged from top to bottom on the agitator shaft. The agitator blades are connected to the agitator shaft by bolts and nuts and can be disassembled. This achieves omnidirectional agitation of materials at different heights within the mixing tank, effectively eliminating dead zones, improving material mixing uniformity, and increasing agitation efficiency. The detachable blades can be flexibly replaced according to material requirements, adapting to different agitation conditions and improving the versatility of the equipment.

[0056] In this embodiment of the invention, the axially magnetized inner and outer rotor magnets are rare-earth permanent magnets, preferably neodymium iron boron permanent magnets, with a magnetic energy product of 380-450 kJ / m³. The magnets have a fan-shaped structure with a central angle of 22.5°. The fitting gap between the inner and outer rotor magnet mounting slots and their corresponding magnets is 0.05-0.1 mm. The magnets are fixed in the mounting slots by adhesive and snap-fit. The adhesive is high-temperature resistant epoxy resin with a bonding strength of not less than 15 MPa. Magnetic isolation pads are set between adjacent magnets with alternating N / S poles. The magnetic isolation pads are made of silicon steel sheets with a thickness of 0.5-2 mm and a permeability ≥1000 μH / m, effectively preventing magnetic flux leakage between adjacent magnets and reducing magnetic circuit losses. Compared with traditional radially magnetized magnets, the effective work ratio of the magnets is improved.

[0057] A method for operating a bottom-mounted disc-type axial magnetic flux stirring device includes the following steps: After the motor drive assembly is started, the variable frequency speed-regulating motor on it outputs power according to the set speed, and the power is transmitted to the outer rotor assembly, driving the outer rotor assembly to rotate around the axis; the N poles and S poles of several outer rotor magnets on the outer rotor magnetic steel disc are arranged alternately around the circumference, forming a uniform axial magnetic flux circuit during rotation, which acts on several inner rotor magnets on the inner rotor assembly through magnetic attraction, driving the inner rotor assembly to rotate synchronously. Since the inner rotor assembly is connected to the stirrer assembly, it drives the stirrer assembly to rotate, thereby realizing the stirring operation of the material in the stirring tank.

[0058] Throughout the transmission process, the isolation sleeve seals and isolates the inner and outer rotors, achieving leak-free transmission and preventing material leakage. This is especially suitable for flammable, explosive, toxic, and highly corrosive materials. The thrust bearing guides the rotor's rotation, ensuring the outer rotor's rotational stability and reducing vibration and swaying during rotation. Simultaneously, it provides axial and radial dual support to the isolation sleeve, effectively strengthening its structural strength and preventing deformation, bulging, or even cracking during operation. The cooling structure, through the circulation of cooling medium, promptly removes the eddy current heat generated during the operation of the magnetic coupling, keeping the magnet's operating temperature within a safe range and preventing demagnetization due to high temperatures, thus ensuring the stability of the magnetic circuit and the reliability of the transmission. Vibration sensors monitor the equipment's vibration status in real time, transmitting vibration signals to the motor control system. When the vibration value exceeds a set threshold, the control system automatically reduces the motor speed or issues an alarm signal, promptly handling abnormal situations and improving equipment operational safety. Multi-layered rotating impellers achieve all-around mixing of materials within the mixing tank, eliminating dead zones and improving material mixing uniformity and efficiency.

[0059] Specific implementation process: Example 1: A bottom-mounted, three-layer disc-type axial flux magnetic stirring device suitable for stirring corrosive materials in the chemical industry. This embodiment addresses the stirring needs of corrosive materials commonly found in the chemical industry (such as 30% sulfuric acid solutions). It designs a bottom-mounted, three-layer, disc-type axial flux magnetic stirring device suitable for a 10m³ vertical mixing tank. Specific parameters and implementation details are as follows: 1. Parameter settings for each component: (1) Axial flux disc type magnetic coupling: Both the inner and outer rotors are made of high-strength aluminum alloy (tensile strength 380MPa), the rotor disc diameter is 400mm and the thickness is 50mm; both the inner and outer rotors are equipped with 8 pairs of 16 axially magnetized neodymium iron boron magnets (magnetic energy product 420kJ / m³), the magnets are fan-shaped with a central angle of 22.5°, and the size of a single magnet is 60mm×40mm×15mm, with strict N / S pole alternation; silicon steel sheet magnetic isolation pads (thickness 1mm, magnetic permeability 1200μH / m) are set between adjacent magnets, and the magnets are fixed in the mounting groove by high temperature resistant epoxy glue (bonding strength 18MPa) + elastic retainer, the fitting gap between the mounting groove and the magnet is 0.08mm; the axial air gap between the inner and outer rotor magnets is 1.5mm; (2) Isolation sleeve: Made of 316L stainless steel (tensile strength 520MPa, yield strength 205MPa), 2mm thick, 380mm inner diameter, 200mm long. The isolation sleeve is welded to the bottom mounting port of the mixing tank by argon arc welding. The weld is free of pores and cracks, and the welding strength is consistent with that of the isolation sleeve body. There is a thrust bearing between the vertical spindle of the isolation sleeve and the outer rotor assembly. The upper ring of the thrust bearing is fixed to the isolation sleeve, and the lower ring is fixed to the outer rotor magnet plate. The axial support force of the thrust bearing on the isolation sleeve is 1200N, and the radial support force is 800N. (3) Thrust bearing: P5 grade double thrust ball bearing, model 51218, is selected, and the rolling elements are made of silicon nitride ceramic material (hardness HRC68). (4) Three-layer agitator assembly: made of 316L stainless steel, with a total length of 1800mm; (5) Motor drive assembly: A variable frequency speed control motor with a power of 7.5kW and an output speed of 0-800r / min is selected, with a speed control accuracy of ±1r / min; the motor and the outer rotor are connected by a rubber elastomer elastic coupling (damping ratio 0.35), and a vibration sensor (measurement accuracy ±0.01mm) is installed on the motor housing and electrically connected to the motor control system. The vibration threshold is set to 0.1mm and the response time is 0.3s; the motor has triple protection functions of overload, overheat and phase loss. (6) Cooling structure: The cooling jacket has a volume of 500mL. The cooling medium is cooling oil (high temperature resistant to 120℃). The circulation pipeline for transporting the cooling medium is made of 316L stainless steel with a diameter of 20mm. The circulation flow rate of the cooling medium is 1.2m / s. The external cooling pump is used to achieve circulation heat dissipation to ensure that the working temperature of the magnet is controlled below 75℃. (7) Connection of the bottom of the mixing tank: The isolation sleeve is welded to the installation port at the bottom of the mixing tank. The welding is done by argon arc welding. The weld is free of pores and cracks. The flatness error of the welding position of the isolation sleeve is 0.008mm.

[0060] 2. No-load commissioning: After assembly, no-load testing is performed. The motor is started and the speed is gradually increased from 0 to 800 r / min. Parameters such as equipment vibration amplitude, noise, and magnet temperature are monitored. After 2 hours of no-load operation without any abnormalities, load testing is performed by injecting 30% sulfuric acid solution to simulate actual stirring conditions. The system is run for 4 hours, and parameters such as stirring uniformity, sealing performance, and cooling effect are monitored to ensure that all parameters meet the design requirements.

[0061] 3. Performance Testing and Result Analysis After assembly, this embodiment underwent a 1000-hour continuous load test, and its performance was compared with that of a conventional radial flux magnetic stirrer of the same specifications (control group). The test results are shown in the table below:

[0062] The test results show that the bottom-center three-layer disc-type axial flux magnetic stirring device of this embodiment, while reducing the amount of magnets by 50%, nearly doubles the utilization rate of magnets. The operating vibration amplitude is controlled at 0.07 mm, far lower than the 0.32 mm of the control group, significantly improving operational stability. The stirring uniformity reaches 96%, and the stirring efficiency is increased by 81.8%, completely eliminating the stirring dead zones of traditional stirrers. The isolation sleeve temperature is controlled at 68℃, and the sealing leakage is far lower than the control group, significantly improving corrosion resistance and sealing reliability. Simultaneously, energy consumption is reduced by 18.2%, and continuous operating time is increased by 122.2%, fully demonstrating the technological advancement and practicality of this invention. During the test, the equipment showed no malfunctions, no significant wear on components, and no deformation or bulging of the isolation sleeve, fully meeting the long-term continuous stirring requirements of corrosive materials in the chemical industry.

[0063] Example 2: Bottom-mounted three-layer disc-type axial flux magnetic stirring device suitable for mixing hygienic materials in the food industry. This embodiment addresses the mixing requirements of hygienic materials (such as dairy products and fruit juices) in the food industry. It designs a bottom-mounted, three-layer, disc-type axial magnetic flux stirring device suitable for a 5m³ vertical mixing tank. The design focuses on optimizing the hygienic structural design to ensure no dead corners and easy cleaning. Specific parameters and implementation details are as follows: 1. Parameter settings and structural optimization for each component: (1) Axial flux disc type magnetic coupling: Both inner and outer rotors are made of high-strength aluminum alloy (tensile strength 380MPa), rotor disc diameter 350mm, thickness 45mm; both inner and outer rotors are equipped with 8 pairs of 16 axially magnetized neodymium iron boron magnets (magnetic energy product 400kJ / m³), the central angle of the sector magnet is 22.5°, the size of a single magnet is 50mm×35mm×12mm, and the N / S poles are arranged alternately; the magnetic isolation pad is made of food-grade silicon steel sheet (thickness 0.8mm), the magnet is fixed with food-grade high-temperature resistant epoxy glue (bonding strength 16MPa) + elastic retaining ring, the gap between the mounting groove and the magnet is 0.06mm; the axial air gap between the inner and outer rotor magnets is 1.2mm; (2) Isolation sleeve: Made of food-grade 316L stainless steel, with a thickness of 1.5mm, an inner diameter of 330mm, and a length of 180mm. The surface is mirror polished (roughness Ra≤0.8μm) and there are no dead corners. The isolation sleeve and the bottom installation port of the mixing tank are welded by argon arc welding. The weld is free of pores and cracks. The welding strength is consistent with that of the isolation sleeve body. The weld is polished smooth. There is a thrust bearing between the vertical spindle of the isolation sleeve and the outer rotor assembly. The upper ring of the thrust bearing is fixed to the isolation sleeve, and the lower ring is fixed to the outer rotor magnet plate. The axial support force of the thrust bearing is 800N and the radial support force is 600N. (3) Three-layer mixer assembly: made of food-grade 316L stainless steel, with a total length of 1500mm; (4) Motor drive components: The variable frequency speed control motor has a power of 5.5kW, a speed of 0-700r / min, and a speed control accuracy of ±1r / min; the flexible coupling is made of food-grade rubber, and the motor housing is equipped with a vibration sensor with a vibration threshold of 0.1mm; the motor has waterproof and dustproof functions and is suitable for the hygiene requirements of food workshops.

[0064] (5) Cooling structure: The cooling jacket has a volume of 400mL. The cooling medium is food-grade cooling water. The circulating pipeline for transporting the cooling medium is made of food-grade stainless steel with a diameter of 18mm and a circulation speed of 1.0m / s. The cooling effect ensures that the temperature of the magnet is ≤70℃.

[0065] (6) Connection to the bottom of the mixing tank: The isolation sleeve is welded to the installation port at the bottom of the mixing tank. The welding is done by argon arc welding. The weld is free of pores and cracks. The flatness error of the welding position of the isolation sleeve is 0.007mm.

[0066] 2. Assembly and Testing Key Points: During assembly, all parts undergo food-grade cleaning and disinfection, and the assembly environment meets the hygiene standards of the food industry to avoid surface contamination of parts. After assembly, the sealing performance of the sealing parts and the presence of sanitary dead corners are tested to ensure that there is no possibility of material residue. The load test uses dairy products (milk) as the mixing material and runs continuously for 500 hours to monitor parameters such as mixing uniformity, hygiene, and equipment stability, and compares them with traditional mixers of the same specifications.

[0067] Test results show that the mixer in this embodiment achieves a 97% uniformity in milk mixing, with no dead zones and no material residue; the equipment operates with a vibration amplitude of 0.06mm and noise ≤65dB, meeting the noise requirements for food processing plants; and the sealing leakage is ≤5×10 -7 m³ / h, fully meeting hygiene standards; easy to disassemble and clean, with no residue or odor after cleaning; compared to traditional mixers, the amount of magnets used is reduced by 50%, energy consumption is reduced by 16%, and mixing efficiency is increased by 45%, completely solving the problems of complex structure, inconvenient cleaning, and uneven mixing of traditional food-grade mixers, and adapting to the hygiene-grade mixing needs of the food industry.

[0068] 3. Summary of Implementation Examples and Technical Verification The two embodiments described above address the stirring requirements of corrosive chemical materials and food-grade hygienic materials, respectively, verifying the technical feasibility and versatility of the bottom-mounted three-layer agitator disc-type axial magnetic flux stirring device of the present invention. During implementation, all components were precisely assembled according to the design parameters, and the performance test results all exceeded the design requirements. Furthermore, compared to traditional radial magnetic flux stirring devices, it achieves breakthrough improvements in core indicators such as magnet utilization, operational stability, stirring efficiency, sealing reliability, and energy consumption, fully demonstrating the technological advancement of the present invention.

[0069] Furthermore, in the implementation of this invention, by optimizing key technologies such as magnet arrangement, thrust bearing integrated design, and three-layer stirring shaft structure, many technical pain points of traditional stirrers are solved: the axial magnetic flux circuit design reduces the amount of magnets used by more than 50% and increases the magnet utilization rate by more than 60%, significantly reducing manufacturing costs; the dual-function integration of the thrust bearing increases the deformation resistance of the isolation sleeve by more than 2 times, completely solving the problem of easy failure of the isolation sleeve; the three-layer stirring shaft eliminates stirring dead corners, improves stirring uniformity by more than 35%, and improves stirring efficiency by more than 40%; the lightweight aluminum alloy rotor design reduces energy consumption by 15%-20%, conforming to the trend of energy conservation and environmental protection; and the diversified material and structural optimization can adapt to the personalized needs of different industries.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A bottom-centered disc-type axial magnetic flux stirring device, characterized in that: The axial flux disc type magnetic coupling is located at the middle position of the inner bottom of the mixing tank. The axial flux disc type magnetic coupling includes an outer rotor assembly, an isolation sleeve, and an inner rotor assembly arranged sequentially from bottom to top. An agitator assembly is connected to the inner rotor assembly, and a motor drive assembly is connected to the outer rotor assembly. The outer rotor assembly is equipped with several axially magnetized outer rotor magnets arranged in a circular pattern, with the N poles and S poles of the outer rotor magnets arranged alternately in a circular pattern. The inner rotor assembly is equipped with several axially magnetized inner rotor magnets arranged in a circular pattern, with the N poles and S poles of the inner rotor magnets arranged alternately in a circular pattern. The isolation sleeve is disposed between the inner and outer rotor assemblies to form a sealed isolation, and a vertical spindle for vertically mounting the inner rotor assembly is fixedly disposed on the isolation sleeve. A thrust bearing is also disposed between the vertical spindle of the isolation sleeve and the outer rotor assembly.

2. The bottom-centered disc-type axial magnetic flux stirring device according to claim 1, characterized in that: The outer rotor assembly includes a flange for fixedly connecting to the frame of the motor drive assembly. An outer rotor component is rotatably connected to the flange and is coaxially fixedly connected to the motor connection shaft of the motor drive assembly. The outer rotor magnets are all disposed on the outer rotor component.

3. The bottom-centered disc-type axial magnetic flux stirring device according to claim 2, characterized in that: The outer rotor component includes an outer rotor shaft and an outer rotor magnet disk fixedly installed at the top of the outer rotor shaft. A rolling bearing is installed between the outer rotor shaft and the flange. The bottom end of the outer rotor shaft is coaxially and fixedly connected to the motor connecting shaft. The outer rotor magnets are installed one-to-one in the outer rotor magnet mounting slots opened on the top surface of the outer rotor magnet disk.

4. The bottom-centered disc-type axial magnetic flux stirring device according to claim 3, characterized in that: The thrust bearing is disposed between the vertical spindle of the outer rotor magnet disk and the isolation sleeve. The upper ring of the thrust bearing is fixed to the isolation sleeve, and the lower ring is fixed to the outer rotor magnet disk.

5. The bottom-centered disc-type axial magnetic flux stirring device according to claim 1, characterized in that: The isolation sleeve includes an isolation cover, which covers the outer rotor magnets on the outer rotor assembly from top to bottom inside the isolation cover, and the isolation cover is fixedly connected to the flange on the outer rotor assembly. The vertical spindle is fixedly located at the middle position of the horizontal isolation end face at the top of the isolation cover.

6. The bottom-centered disc-type axial magnetic flux stirring device according to claim 5, characterized in that: The isolation cover has a jacket inside its periphery, and the jacket is connected to a coolant inlet and a coolant outlet.

7. The bottom-centered disc-type axial magnetic flux stirring device according to claim 1, characterized in that: The inner rotor assembly includes an inner rotor component. The top of the inner rotor component is coaxially and fixedly connected to the bottom end of the stirring shaft provided on the stirrer assembly. The inner rotor magnets are installed one-to-one in the inner rotor magnet mounting slots opened on the bottom surface of the inner rotor component. The inner rotor component has a vertical inner rotor shaft hole in the middle, and the vertical spindle is coaxially arranged in the inner rotor shaft hole.

8. The bottom-centered disc-type axial magnetic flux stirring device according to claim 7, characterized in that: A sliding bearing is provided between the inner rotor shaft hole and the vertical spindle, including a male sliding bearing mounted on the upper and lower parts of the vertical spindle and a female sliding bearing mounted on the upper and lower parts of the inner rotor shaft hole. The upper male sliding bearing and the upper female sliding bearing are matched and installed together, and the lower male sliding bearing and the lower female sliding bearing are matched and installed together. The bottom sealing end face of the lower male sliding bearing is provided with an O-ring seal. A sliding sleeve is provided between the upper and lower male sliding bearings and is fitted on the vertical spindle. The sealing end faces of the upper and lower ends of the sliding sleeve are also provided with O-rings. The sleeve is assembled and installed on the vertical spindle with the upper and lower male sliding bearings respectively, and is fastened by a fastening bolt screwed to the top of the vertical spindle.

9. The bottom-centered disc-type axial magnetic flux stirring device according to claim 1, characterized in that: The inner bottom of the mixing tank is provided with an installation port. The outer peripheral edge of the isolation sleeve is fixed to the installation port by welding. The welding is done by argon arc welding, and the weld is free of pores and cracks.

10. A method for operating the bottom-centered disc-type axial magnetic flux stirring device as described in any one of claims 1-9, characterized in that, The following steps are performed: After the motor drive assembly is started, the variable frequency speed control motor on it outputs power according to the set speed. The power is transmitted to the outer rotor assembly, which drives the outer rotor assembly to rotate around the axis. The N poles and S poles of several outer rotor magnets on the outer rotor magnet disk are arranged alternately around the circumference. During the rotation, a uniform axial magnetic flux circuit is formed. The magnetic attraction acts on the several inner rotor magnets on the inner rotor assembly, which are arranged alternately around the circumference with N poles and S poles, driving the inner rotor assembly to rotate synchronously. Since the inner rotor assembly is connected to the agitator assembly, it drives the agitator assembly to rotate, thereby realizing the stirring operation of the material in the mixing tank.

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