External circulation constant-pressure sealing magnetic transmission pump

Abstract

The utility model discloses an external circulation constant-pressure sealing magnetic transmission pump, and belongs to the field of transmission devices. Comprising a driving part; a shaft system assembly is arranged in the transmission pump shell, and one end of the shaft system assembly is connected with an impeller; the transmission pump shell and the permanent magnet transmission assembly are provided with communicated internal flow channels, the two ends of the permanent magnet transmission assembly are connected to the driving part and the shafting assembly respectively, and the driving part drives the shafting assembly to rotate through the permanent magnet transmission assembly. According to the external circulation constant pressure sealing magnetic transmission pump, leakage-free magnetic transmission is achieved, internal fluid external circulation and external medium conveying and sealing functions are smoothly completed, the dual-sealing function of static sealing and constant pressure sealing is achieved, the internal fluid and the external medium are sealed in a two-way mode, and leakage of the internal fluid is avoided.

Description

Technical Field

[0001] This utility model belongs to the technical field of transmission devices, and specifically relates to an external circulation constant pressure sealed magnetic transmission pump. Background Technology

[0002] In fluid transport equipment, all types of pumps suffer from the problem of drive shaft sealing. Drive shafts can be categorized into magnetic seals and mechanical seals. Mechanical seals are dynamic seals, using various types of sealing rings to provide radial and axial sealing of the rotating shaft, allowing the medium to flow axially. However, over time, leakage occurs, causing environmental pollution, safety risks, and frequent maintenance. Magnetic seals consist of a permanent magnet inner rotor, a permanent magnet outer rotor, and an isolation sleeve. The isolation sleeve seals the permanent magnet inner rotor and the medium within the working chamber. A motor drives the permanent magnet outer rotor, which in turn drives the permanent magnet inner rotor using magnetic coupling, achieving contactless torque transmission and static sealing. Magnetic seals completely eliminate medium leakage, overcoming the shortcomings of mechanical seals.

[0003] To achieve a leak-free seal, a magnetic seal is required. Magnetic drive pumps solve the leakage problem in fluid transportation, but the fluid being transported cannot contain metallic or non-metallic particles. Because the gap between the permanent magnet inner rotor and the isolation sleeve is very small, such particles entering the magnetic seal will cause wear and damage to the permanent magnet inner rotor and the isolation sleeve, and will also damage the transmission components and reduce the service life of the equipment.

[0004] For leak-free transport of fluids containing particulate matter, a common solution is to install a filter at the inlet of the magnetic drive pump to filter out the particulate matter. This eliminates the wear caused by particulate matter entering the magnetic seal structure and damaging the permanent magnet inner rotor, isolation sleeve, and transmission components, ensuring stable system operation.

[0005] For leak-free transport of media that cannot or do not allow the filtration of particulate matter, magnetic drive pumps cannot be selected. Conventional pumps with mechanical seals can transport the media, but they cannot completely solve the problem of leak-free transport. Utility Model Content

[0006] The main purpose of this invention is to provide an external circulation constant pressure sealed magnetic drive pump, which solves the problem that existing magnetic drive pumps will cause damage to the pump body structure when conveying particulate media.

[0007] To achieve the above objectives, the technical solution adopted by this utility model is: an external circulation constant pressure sealed magnetic drive pump, comprising:

[0008] A drive unit, the drive unit being used to provide transmission power to the external circulation constant pressure sealed magnetic drive pump;

[0009] A transmission pump housing, wherein a shaft assembly is provided inside the transmission pump housing, and an impeller is connected to one end of the shaft assembly;

[0010] The permanent magnet drive assembly has a communicating internal flow channel between the drive pump housing and the permanent magnet drive assembly. The two ends of the permanent magnet drive assembly are respectively connected to the drive member and the shaft assembly. The drive member drives the shaft assembly to rotate through the permanent magnet drive assembly.

[0011] In one possible implementation, the transmission pump housing includes a pump body, a pump cover, and a bearing housing connected in sequence, the pump body having a medium transmission inlet and an outlet, and the impeller being mounted inside the pump body.

[0012] In one possible implementation, the permanent magnet drive assembly includes a permanent magnet outer rotor, an isolation sleeve, and a permanent magnet inner rotor that are sequentially fitted from the outside in. The permanent magnet outer rotor is connected to the drive member, and the isolation sleeve is sealed to the drive pump housing.

[0013] In one possible implementation, the shaft assembly includes a drive shaft, one end of which is connected to the permanent magnet drive assembly, and the other end of which is connected to the impeller.

[0014] In one possible implementation, the transmission pump housing is provided with symmetrical bearing seats, and alloy sliding bearing assemblies are fitted near both ends of the transmission shaft.

[0015] In one possible implementation, a mounting plate is provided at each end of the drive shaft, the mounting plate being used to constrain the alloy sliding bearing assembly.

[0016] In one possible implementation, an intermediate sleeve is fitted onto the drive shaft, with both ends of the intermediate sleeve respectively engaging with the alloy sliding bearing assembly.

[0017] In one possible implementation, the impeller is provided with a balance hole ring, and a combined sealing ring is provided between the drive shaft and the drive pump housing.

[0018] One possible implementation also includes:

[0019] An external circulation device is connected to the internal flow channel via a delivery pipe.

[0020] In one possible implementation, the external circulation device includes a circulation tank, which is equipped with a circulation magnetic pump. The delivery pipe is connected to the circulation magnetic pump, and the circulation tank is equipped with a pressure regulating device and a liquid level regulating device.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This utility model of an external circulation constant pressure sealed magnetic drive pump employs a unique double impeller and double seal structure design, an external circulation constant pressure sealing circuit, a permanent magnet levitation shaft system, and a permanent magnet drive structure. It achieves seamless leakage-free magnetic drive, internal fluid circulation, external media transport, and sealing. The dual sealing function of static and constant pressure sealing ensures bidirectional sealing between the internal fluid and external media, preventing leakage of the internal fluid. Particulate matter from the external media will not enter the magnetic rotor assembly, effectively protecting the magnetic rotor assembly and shaft system from damage caused by the infiltration of particulate-containing external media. Simultaneously, internal fluid will not enter the external media, eliminating contamination of the external media by the internal fluid. This external circulation constant pressure sealed magnetic drive pump utilizes permanent magnet drive technology, external circulation constant pressure sealing circuit technology, and permanent magnet levitation shaft system technology. It features double-seal leakage-free operation, compact structure, reliable operation, maintenance-free operation, and long service life. It is suitable for leak-free transport of particulate-containing media at normal or high temperatures, with inlet pressures of atmospheric or high pressure up to 30MPa, and a head of less than 1000 meters. Attached Figure Description

[0023] Figure 1 This is a cross-sectional structural schematic diagram of an external circulation constant pressure sealed magnetic transmission pump according to the present invention;

[0024] Figure 2 This is a cross-sectional structural schematic diagram of the permanent magnet transmission component of an external circulation constant pressure sealed magnetic transmission pump according to the present invention.

[0025] Figure 3 This is a cross-sectional structural schematic diagram of the shaft system assembly of an external circulation constant pressure sealed magnetic transmission pump according to the present invention.

[0026] Figure 4 This is a cross-sectional structural schematic diagram of the external circulation device of the external circulation constant pressure sealed magnetic transmission pump of this utility model;

[0027] Figure 5 This is a schematic diagram of the operation of an external circulation constant pressure sealed magnetic transmission pump according to the present invention.

[0028] In the diagram: 1. Pump body; 2. Impeller nut; 3. Impeller; 4. Balance hole ring; 5. Combined sealing ring; 6. Drive shaft; 7. Front seat plate; 8. Front bearing housing; 9. Lower alloy sliding bearing assembly; 10. Pressure gauge; 11. Pump cover; 12. Intermediate sleeve; 13. Bearing housing; 14. Rear bearing housing; 15. Pressure ring; 16. Upper alloy sliding bearing assembly; 17. Rear seat plate; 18. Permanent magnet levitation bearing; 19. Permanent magnet inner rotor; 20. Isolation sleeve; 21. Permanent magnet outer rotor; 22. Round nut; 23. Motor support; 24. Connecting bracket; 25. Motor; 26. Delivery pipe; 27. Pressure regulating device; 28. Tank pressure gauge; 29. ​​Control box; 30. Liquid level regulating device; 31. Circulation tank; 32. Circulation magnetic pump. Detailed Implementation

[0029] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present utility model. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present utility model.

[0030] In the description of the embodiments of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing the embodiments of this utility model and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In addition, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this utility model can be understood according to the specific circumstances.

[0031] See Figures 1-4 This utility model provides an external circulation constant pressure sealed magnetic drive pump, comprising:

[0032] The driving component is used to provide power to the external circulation constant pressure sealed magnetic transmission pump of this utility model. In this embodiment, the driving component is a motor 25, which provides power to the pump. Its high-efficiency frequency conversion servo characteristics can ensure the normal operation of the external circulation constant pressure sealed magnetic transmission pump. Of course, the driving component can also be other power components, which are not limited in this embodiment.

[0033] A transmission pump housing, inside which a shaft assembly is installed, and one end of the shaft assembly is connected to an impeller 3;

[0034] The permanent magnet drive assembly has a connected internal flow channel between the drive pump housing and the permanent magnet drive assembly. The two ends of the permanent magnet drive assembly are respectively connected to the drive component and the shaft assembly. The drive component drives the shaft assembly to rotate through the permanent magnet drive assembly.

[0035] In this embodiment, the motor 25 provides transmission power, which is transmitted to the shaft assembly for rotation via the permanent magnet drive assembly. The impeller 3 connected to the shaft assembly transmits the external medium, and the external medium will not damage the shaft assembly and the permanent magnet drive assembly during the transmission process.

[0036] Furthermore, the transmission pump housing in this embodiment includes a pump body 1, a pump cover 11, and a bearing housing 13 connected in sequence. The pump body 1 has a medium transmission inlet at the bottom and a medium transmission outlet on the side. The impeller 3 is installed inside the pump body 1. In this embodiment, the pump body 1 and the pump cover 11 are connected as a whole by screws and sealing rings to form the working chamber of the impeller 3. The impeller 3 and the transmission shaft 6 are connected as a whole by the impeller nut 2 and key strip to form the lower working part. The pump body 1 in this embodiment is a single-stage centrifugal pump with a single-layer shell vertical structure. Of course, the pump body 1 can also be selected from pumps with other structures according to the needs and the external medium actually transmitted.

[0037] Furthermore, a motor support 23 is connected to the bearing housing 13 via a connecting bracket 24, and the motor 25 is fixedly mounted on the motor support 23. The bearing housing 13 is a support component, serving to support the connecting bracket 24, the pump cover 11, the delivery pipe 26, and the shaft assembly.

[0038] Furthermore, a pressure gauge 10 is integrated on the pump cover 11, which monitors the pressure on the back of the impeller 3 in real time and displays the reading.

[0039] Further, see Figure 2The permanent magnet drive assembly includes a permanent magnet outer rotor 21, an isolation sleeve 20, and a permanent magnet inner rotor 19, which are sequentially fitted from the outside in. The permanent magnet outer rotor 21 is connected to the motor, and the isolation sleeve 20 is sealed to the bearing housing 13. In this embodiment, the permanent magnet inner rotor 19 and the drive shaft 6 are connected as a passive component by a round nut 22 and a key. The isolation sleeve 20 and the bearing housing 13 are connected as a whole by screws, sealing rings, and pressure rings 15, forming a static seal structure for the internal fluid in the upper part, ensuring that the internal fluid does not leak. In this embodiment, the permanent magnet inner rotor 19 and the permanent magnet outer rotor 21 are permanent magnet structures with a stainless steel outer covering, which prevents the permanent magnet inner rotor 19 from contacting the internal fluid. The isolation sleeve 20 is a non-rotating component. The isolation sleeve 20 completely isolates the permanent magnet inner rotor 19 and the internal fluid from the permanent magnet outer rotor 21, realizing shaft seal-free power transmission and turning dynamic sealing into static sealing to meet the requirements of leak-free transmission. The permanent magnet outer rotor 21 drives the permanent magnet inner rotor 19 to rotate through magnetic coupling characteristics, completing non-contact torque transmission. The use of a non-heating isolation sleeve 20 does not raise the temperature of the internal fluid, ensuring stable magnetic operation of the system and improving transmission efficiency while achieving zero leakage in the constant pressure circulation process of the internal fluid.

[0040] To prevent external media from entering the pump during transmission, this embodiment features a balance ring 4 on the impeller 3 and a combined sealing ring 5 between the drive shaft 6 and the pump cover 11. This combined sealing ring 5 is a contact-type sealing device that achieves axial and radial sealing through radial clamping force and a special tortuous gap. Due to the set internal fluid circulation pressure, external media delivery pressure, and the multiple effects of the combined sealing ring 5, external media will not enter the pump cover 11, and internal fluid will not enter the pump body 1, thus achieving a constant pressure bidirectional sealing effect.

[0041] Further, see Figure 3The shaft system assembly comprises a drive shaft 6, a front bearing plate 7, a front bearing housing 8, a lower alloy sliding bearing assembly 9, an intermediate sleeve 12, a rear bearing housing 14, an upper alloy sliding bearing assembly 16, a rear bearing plate 17, and a permanent magnet levitation bearing 18. This shaft system is a suspended drive shaft system supported by two alloy sliding bearing assemblies and one permanent magnet levitation support. This ensures the balance of axial forces under various working conditions, greatly eliminates the influence of gravity and working loads on the shaft system assembly, extends the service life of the shaft system assembly, and guarantees the transmission accuracy of drive shaft 6 and the stability and safety of the system operation. The lower alloy sliding bearing assembly 9 and the upper alloy sliding bearing assembly 16 are a combination of radial alloy sliding bearings and axial alloy thrust bearings, which withstand axial and radial forces generated by irregular movement of the medium and have high temperature resistance, high pressure resistance, and wear resistance characteristics. The permanent magnet levitation bearing 18 ensures the stability of the shaft system assembly's suspension, and the permanent magnet inner rotor 19 further eliminates the influence of gravity and working loads on the shaft system assembly. Both the lower alloy sliding bearing assembly 9 and the upper alloy sliding bearing assembly 16 include radial alloy sliding bearings and axial alloy thrust bearings with reasonable fit clearances, front seat plate 7 and rear seat plate 17 are fixed on the drive shaft 6 with key strips, and intermediate sleeve 12 is fixed on the drive shaft 6 with reasonable fit clearances so that its two ends fit against the front bearing housing 8 and the rear bearing housing 14. The front bearing housing 8 and the rear bearing housing 14 are fixed on the bearing housing 13 with screws. The lower alloy sliding bearing assembly 9 and the upper alloy sliding bearing assembly 16 are respectively installed in the rear seat plate 17 and the rear bearing housing 14, which are limited by the front seat plate 7 and the front bearing housing 8.

[0042] In addition, the internal flow channel in this embodiment is specifically provided by opening an inlet and an outlet of the internal flow channel on the side of the pump cover 11. The flow channel enters the middle of the bearing housing 13 through the bearing housing 13, flows into the axial flow channel passing through the drive shaft 6, enters the space of the isolation sleeve 20, cools the permanent magnet drive assembly and shaft components, and then flows out from the outlet of the internal flow channel.

[0043] Further, see Figure 1 and Figure 4This embodiment also includes an external circulation device, which is connected to the inlet and outlet of the internal flow channel via two delivery pipes 26. Specifically, the external circulation device consists of delivery pipes 26, a pressure regulating device 27, a tank pressure gauge 28, a control box 29, a liquid level regulating device 30, a circulation tank 31, and a magnetic circulation pump 32, forming a pressure vessel for a gas-liquid two-phase carrier with internal fluid circulation. It has the function of adjusting the internal fluid pressure in both manual and automatic modes and is a key component for fluid circulation in the internal flow channel. Manually adjusting the pressure regulating device 27 can change the gas volume inside the circulation tank 31, and manually adjusting the liquid level regulating device 30 can change the liquid volume inside the circulation tank 31. The magnetic circulation pump 32 provides the driving force for the internal fluid flow. Of course, the pressure and liquid level can also be adjusted through automatic control. This embodiment further includes a control box 29, which is signal-connected to the regulating device 27, the liquid level regulating device 30, and the magnetic circulation pump 32, and performs automatic control through real-time monitoring and preset normal values. In this embodiment, the conveying pipe 26 and the circulation tank 31 are connected as a single unit using welding and flange connections. See [link to documentation]. Figure 5 The conveying pipe 26 is a pipeline for internal fluid circulation, divided into a lower output pipe (indicated by the arrow) and an upper input pipe (indicated by the arrow). The pressure regulating device 27, tank pressure gauge 28, liquid level regulating device 30, and circulation tank 31 are connected as a single unit using welding and threaded connections. The control box 29 is mounted on the circulation tank 31 or placed independently beside the equipment using screw connections. The tank pressure gauge 28 monitors the internal pressure of the circulation tank 31 in real time and displays the reading. The circulation tank 31 contains a gas-liquid two-phase carrier, with gas at the top and liquid at the bottom. The circulation tank 31 can also be equipped with accessories such as a liquid level display window and a bottom discharge valve. The external circulation device works by adjusting the ratio of the gas and liquid two-phase carriers to balance the pressure. When the internal air pressure of the circulation tank 31 exceeds the hydraulic reading of pressure gauge 10, the pressure regulating device 27 is manually or automatically opened to release pressure until its reading matches the hydraulic reading of pressure gauge 10, after which the pressure regulating device 28 is closed. If the internal air pressure of the circulating tank 31 is lower than the hydraulic reading of the pressure gauge 10, the liquid level adjustment device 30 can be opened manually or automatically to replenish the liquid. After that, the air pressure reading of the tank pressure gauge 28 will gradually increase until its reading is the same as the hydraulic reading of the pressure gauge 10, and then the liquid level adjustment device 30 will be closed.

[0044] Therefore, the external circulation device is a key component for achieving constant pressure sealing. It adjusts the pressure value of the tank pressure gauge 28 according to the pressure change of the pressure gauge 10, ensuring that the pressure value on the upper and lower parts of the combined sealing ring 5 is always the same, thereby avoiding leakage problems caused by pressure difference.

[0045] When working, see Figure 5The motor 25 drives the permanent magnet outer rotor 21 to rotate at high speed. Due to the magnetic field between the permanent magnet inner rotor 19 and the permanent magnet outer rotor 21, the permanent magnet outer rotor 21 drives the permanent magnet inner rotor 19 inside the isolation sleeve 20 to rotate synchronously through magnetic coupling characteristics, and drives the transmission shaft 6 to rotate, transmitting the torque of the motor 26 to the impeller 3 without contact. Under the driving action of the circulating magnetic pump 32, the internal fluid is drawn in from the upper B inlet (indicated by the arrow) and flows out from the upper B outlet (indicated by the arrow), realizing internal fluid circulation. The internal fluid is drawn into the pump cover 11 from the upper B inlet (indicated by the arrow) and flows upward from the side hole of the bearing housing 13 into the middle of the bearing housing 13 and flows out. At the same time, it flows upward along the center hole of the transmission shaft 6 and flows out from the gap between the permanent magnet inner rotor 19 and the isolation sleeve 20, realizing internal fluid circulation. The isolation sleeve 20 ensures that the internal fluid is leak-free. The rotation of the transmission shaft 6 drives the lower impeller 3 to rotate and do work on the external medium. The external medium is drawn in axially from the lower A inlet (indicated by the arrow) and flows out radially from the lower A outlet (indicated by the arrow), realizing external medium transportation. The rotation of impeller 3 generates a specific back pressure on the external medium, which is detected in real time by pressure gauge 10. The balance ring 4 is a multi-layer filter that filters particulate matter from the external medium. External medium meeting filtration requirements enters the back of impeller 3 and creates pressure, which is detected and displayed in real time by pressure gauge 10. The combined sealing ring 5 is a contact sealing device that achieves axial and radial sealing through radial clamping force and a special tortuous gap. Due to the set internal fluid circulation pressure, external medium delivery pressure, and the multiple functions of the combined sealing ring 5, external medium will not enter the pump cover 11, and internal fluid will not enter the pump body 1, thus achieving constant pressure bidirectional sealing. In case of overload, the permanent magnet inner rotor 19 and permanent magnet outer rotor 21 slip relative to each other, protecting the motor 26. The automatic protection function of motor 25 ensures the normal operation of the drive pump.

[0046] This utility model's external circulation constant pressure sealed magnetic drive pump employs a unique double impeller and double seal structure design, a unique external circulation constant pressure sealing circuit, a permanent magnet levitation shaft system, and a permanent magnet drive structure. Through magnetic coupling, the motor torque is transmitted to the impellers at both ends without contact, achieving non-contact torque transmission. This enables cooling and lubrication of transmission components, leak-free internal fluid operation, bidirectional sealing of internal fluid and external media, and effective external media transport. It extends equipment lifespan, ensures stable system operation, and improves transmission efficiency. It is suitable for leak-free transport of particulate media at normal or high temperatures, with inlet pressures of at least 30 MPa and head less than 1000 meters.

[0047] The various embodiments in this specification are described in a progressive manner. For the same or similar parts between the various embodiments, please refer to each other. Each embodiment focuses on describing the differences from other embodiments.

[0048] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. An external circulation constant pressure sealed magnetic drive pump, characterized in that, include: A drive unit, the drive unit being used to provide transmission power to the external circulation constant pressure sealed magnetic drive pump; A transmission pump housing, wherein a shaft assembly is provided inside the transmission pump housing, and an impeller is connected to one end of the shaft assembly; The permanent magnet drive assembly has a communicating internal flow channel between the drive pump housing and the permanent magnet drive assembly. The two ends of the permanent magnet drive assembly are respectively connected to the drive member and the shaft assembly. The drive member drives the shaft assembly to rotate through the permanent magnet drive assembly.

2. The magnetic drive pump according to claim 1, characterized in that, The transmission pump housing includes a pump body, a pump cover, and a bearing housing connected in sequence. The pump body has a medium transmission inlet and an outlet, and the impeller is installed in the pump body.

3. The magnetic drive pump according to claim 1, characterized in that, The permanent magnet transmission assembly includes a permanent magnet outer rotor, an isolation sleeve, and a permanent magnet inner rotor that are sequentially fitted together from the outside to the inside. The permanent magnet outer rotor is connected to the driving component, and the isolation sleeve is sealed to the transmission pump housing.

4. The magnetic drive pump according to claim 1, characterized in that, The shaft system assembly includes a drive shaft, one end of which is connected to the permanent magnet drive assembly, and the other end is connected to the impeller.

5. The magnetic drive pump according to claim 4, characterized in that, The transmission pump housing is provided with symmetrical bearing seats, and alloy sliding bearing assemblies are sleeved near both ends of the transmission shaft.

6. The magnetic drive pump according to claim 5, characterized in that, The drive shaft has a base plate at each end, which is used to constrain the alloy sliding bearing assembly.

7. The magnetic drive pump according to claim 5, characterized in that, An intermediate sleeve is fitted onto the drive shaft, and the two ends of the intermediate sleeve are respectively fitted to the alloy sliding bearing assembly.

8. The magnetic drive pump according to claim 4, characterized in that, The impeller is provided with a balance hole ring, and a combined sealing ring is provided between the drive shaft and the drive pump housing.

9. The magnetic drive pump according to claim 1, characterized in that, Also includes: An external circulation device is provided, wherein the external circulation device is circulated in connection with the internal flow channel through a delivery pipe.

10. The magnetic drive pump according to claim 9, characterized in that, The external circulation device includes a circulation tank, which is equipped with a circulation magnetic pump. The delivery pipe is connected to the circulation magnetic pump. The circulation tank is equipped with a pressure regulating device and a liquid level regulating device.

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