Pressure self-adaptive magnetic liquid sealing stop valve and sealing control method

Abstract

The invention discloses a pressure self-adaptive magnetic liquid sealing stop valve and a sealing control method. The pressure self-adaptive magnetic liquid sealing stop valve comprises a valve body, a valve cover, an opening and closing assembly, a magnetic liquid sealing device and an intelligent monitoring and adjusting system. The opening-closing assembly comprises a valve rod. The magnetic liquid sealing device comprises a ring type electromagnet, a pole shoe and magnetic liquid, the ring type electromagnet, the pole shoe and the valve rod form a closed magnetic circuit, a sealing gap is formed between the pole shoe and the valve rod, and the magnetic liquid is adsorbed and kept at the sealing gap under the action of a magnetic field formed by the closed magnetic circuit to form a magnetic liquid sealing ring; the intelligent monitoring and adjusting system comprises a pressure transmitter, a power supply and a central control system, and the central control system controls the power supply to adjust the current input into the ring type electromagnet according to a pressure signal fed back by the pressure transmitter so as to change the magnetic field intensity and further adjust the sealing force. Through pressure self-adaptive magnetic liquid sealing, the problem of abrasion of dynamic sealing of the valve rod is solved, and intelligent adjustment of the sealing strength is achieved.

Description

Technical Field

[0001] This invention belongs to the field of valve sealing technology, and particularly relates to a pressure-adaptive magnetic liquid sealing shut-off valve and a sealing control method. Background Technology

[0002] Gate valves are critical components of fluid control systems, and the dynamic seal at the valve stem is a common weak point for leakage. Traditional gate valves commonly employ contact sealing methods at the valve stem, such as packing seals, bellows seals, or mechanical seal rings. Packing seals rely on the tight contact between the packing and the valve stem to achieve a seal. The reciprocating motion of the valve stem inevitably generates friction and wear, leading to a decline in sealing performance over time, a risk of leakage, and frequent maintenance. While bellows seals can achieve a leak-free seal, the bellows stroke is limited and there is a risk of metal fatigue fracture, resulting in insufficient reliability under high-pressure and high-frequency conditions. More importantly, the sealing strength of these sealing methods cannot be changed once set, failing to respond to dynamic changes in pipeline system pressure. When pressure increases, the sealing performance is insufficient; when pressure decreases, over-sealing leads to energy waste, lacking intelligent adjustment capabilities. For high-pressure and high-risk media conditions in petrochemical, energy transmission, and other fields, a valve stem sealing solution that can adapt to pressure changes and eliminate wear is needed. Summary of the Invention

[0003] Purpose of the invention: In order to overcome the shortcomings of the existing technology, the present invention provides a pressure-adaptive magnetic liquid seal shut-off valve and a sealing control method. Through pressure-adaptive magnetic liquid sealing, the wear problem of valve stem dynamic seal is solved and the sealing strength is intelligently adjustable.

[0004] Technical solution: To achieve the above objectives, the present invention provides a pressure-adaptive magnetic liquid-sealed shut-off valve, comprising:

[0005] The valve body is a three-way structure with an inlet, an outlet, and an upper port;

[0006] A valve cover, which is fixedly connected to the upper port of the valve body, has a hollow cavity inside.

[0007] An opening and closing assembly, the opening and closing assembly including a valve stem that is reciprocally inserted into the hollow cavity of the valve cover;

[0008] A magnetic liquid sealing device is disposed in the hollow cavity of the valve cover and sleeved on the outside of the valve stem. It includes an annular electromagnet, a pole shoe, and a magnetic liquid. The annular electromagnet and the pole shoe are arranged along the axial direction of the valve stem. The annular electromagnet, the pole shoe, and the valve stem form a closed magnetic circuit. A sealing gap is formed between the inner annular surface of the pole shoe and the outer circular surface of the valve stem. The magnetic liquid is attracted and held at the sealing gap under the action of the magnetic field formed by the closed magnetic circuit to form a magnetic liquid sealing ring.

[0009] The intelligent monitoring and control system includes a pressure transmitter for monitoring the medium pressure at the outlet of the valve body, a power supply electrically connected to the ring electromagnet, and a central control system connected to the pressure transmitter and the power supply. The central control system controls the power supply to adjust the current input to the ring electromagnet according to the pressure signal fed back by the pressure transmitter, so as to change the magnetic field strength and thus adjust the sealing force.

[0010] Furthermore, there are multiple ring electromagnets, which are spaced apart along the axial direction of the valve stem, and the pole shoes are disposed between adjacent ring electromagnets.

[0011] Furthermore, the ring electromagnet includes an upper ring electromagnet, a middle ring electromagnet, and a lower ring electromagnet arranged sequentially along the valve stem axial direction, and the pole shoe includes an upper pole shoe disposed between the upper ring electromagnet and the middle ring electromagnet, and a lower pole shoe disposed between the middle ring electromagnet and the lower ring electromagnet.

[0012] Furthermore, the inner annular surface of the pole shoe is provided with multiple levels of pole teeth arranged axially, and multiple sealing gaps are formed between the pole teeth and the outer circular surface of the valve stem.

[0013] Furthermore, the magnetic liquid sealing device is provided with deep groove ball bearings at both axial ends, and the deep groove ball bearings are sleeved on the outside of the valve stem and abut against the inner wall of the hollow cavity of the valve cover.

[0014] Furthermore, the magnetic liquid sealing device also includes a magnetic isolation ring disposed between the annular electromagnet and the deep groove ball bearing.

[0015] Furthermore, a sealing groove is provided on the outer circumferential surface of the pole shoe, and a sealing ring for forming a static seal with the inner wall of the valve cover is embedded in the sealing groove.

[0016] Furthermore, the power supply is a DC power supply with an adjustable output voltage.

[0017] Furthermore, the magnetic liquid is composed of a fluoroether oil-based carrier liquid and magnetite nanoparticles.

[0018] A sealing control method for a pressure-adaptive magnetic liquid-sealed shut-off valve includes the following steps:

[0019] Step S1: Monitor the medium pressure at the valve body outlet in real time using a pressure transmitter and transmit the pressure signal to the central control system;

[0020] Step S2: The central control system compares the received pressure signal with the preset pressure threshold and generates a current adjustment command based on the comparison result, as follows:

[0021] Step S2.1: When the medium pressure is higher than the first preset pressure threshold, the central control system increases the current output to the ring electromagnet to enhance the magnetic field strength and thus improve the sealing force of the magnetic liquid sealing device.

[0022] Step S2.2: When the medium pressure is lower than the second preset pressure threshold, the central control system controls the power supply to reduce the current output to the ring electromagnet, so as to weaken the magnetic field strength and thus reduce the sealing force of the magnetic liquid sealing device.

[0023] Beneficial Effects: This invention replaces the traditional contact seal with a magnetic liquid seal at the valve stem. A magnetic field attracts the magnetic liquid into the sealing gap, forming a liquid O-ring. During valve stem movement, there is no solid contact between the valve stem and the pole teeth, eliminating friction and wear at the source and preventing seal failure due to wear, thus achieving long service life and maintenance-free operation. By arranging multiple sets of ring-type electromagnets and pole shoes along the axial direction, multiple series-connected closed magnetic circuits are formed, ensuring that the valve stem is in a strong magnetic field zone throughout its entire stroke, overcoming the defect of magnetic field attenuation at the edges of the magnetic poles in traditional magnetic liquid seals. Furthermore, this invention constructs a closed-loop control system for pressure monitoring and current regulation. The pressure transmitter collects the medium pressure in real time, and the central control system dynamically adjusts the electromagnet excitation current according to pressure changes, so that the sealing force adapts synchronously with the medium pressure: automatically increasing the sealing force to ensure zero leakage when the pressure rises, and automatically decreasing the sealing force to reduce energy consumption when the pressure drops. This combination of non-contact structure and intelligent control allows the gate valve to actively adapt to complex operating conditions such as high-pressure impacts and pressure fluctuations, making it particularly suitable for demanding applications such as petrochemicals and hydrogen energy where sealing reliability is extremely important. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the pressure-adaptive magnetic liquid-sealed shut-off valve of the present invention;

[0025] Figure 2 This is a partially enlarged schematic diagram of a magnetic liquid sealing device;

[0026] Figure 3 A schematic diagram illustrating the working principle of a magnetic liquid sealing device;

[0027] Figure 4 This is a schematic diagram of the workflow of an intelligent monitoring and control system. Detailed Implementation

[0028] The invention will now be further described with reference to the accompanying drawings.

[0029] In valve technology, leakage is clearly classified into internal leakage and external leakage based on its location and flow direction. Internal leakage refers to the leakage of medium from the high-pressure side to the low-pressure side through the sealing pair between the valve disc and the valve seat when the valve is closed. The root cause is damage, deformation, or incomplete closure of the sealing surface, leading to process control failure, increased energy consumption, and difficulty in direct observation. External leakage, on the other hand, refers to the leakage of medium from inside the valve to the external environment. It is most commonly caused by the failure of the dynamic seal at the valve stem or damage to static seals such as flanges and valve body connections.

[0030] In existing gate valve stem dynamic sealing technologies, common methods include packing seals, bellows seals, and dual-seal systems. Packing seals essentially block leakage through close contact and friction between the valve stem and solid sealing material, leading to unavoidable wear. Bellows seals, while achieving dynamic sealing isolation through metal bellows, have limited stroke, posing a risk of metal fatigue fracture and hydrogen embrittlement in high-pressure or corrosive media such as hydrogen. Dual-seal systems improve reliability through redundancy, but their complex structure and high cost fail to fundamentally eliminate failure mechanisms such as contact wear or component fatigue. To improve the sealing effect of gate valves, this invention utilizes a variable magnetic field to attract magnetic liquid into the sealing gap, forming a flexible, self-healing liquid O-ring, achieving non-contact sealing. This method fundamentally eliminates mechanical wear, theoretically enabling extremely long service life and maintenance-free operation, and achieving near-zero leakage sealing levels for high-risk small-molecule media such as hydrogen. More importantly, when using an electromagnet for driving, the sealing force can be precisely and intelligently adjusted in real time through the magnetizing current. The specific technical solution is as follows:

[0031] like Figure 1 As shown, a pressure-adaptive magnetic liquid-sealed shut-off valve includes: a valve body 1, which is a three-way structure with an inlet, an outlet, and an upper port; a valve cover 2, which is fixedly connected to the upper port of the valve body 1 and has a hollow cavity inside; and an opening and closing assembly, which includes a valve stem 3, which is reciprocally inserted into the hollow cavity of the valve cover 10. The opening and closing assembly also includes a valve disc 2 installed at the lower end of the valve stem 3 via a valve disc cover 4, a valve stem nut 11 threaded to the upper part of the valve stem 3, and a handwheel 12 connected to the top of the valve stem 3 via a handwheel nut 13.

[0032] Magnetic liquid sealing devices, such as Figure 1As shown, the magnetic liquid sealing device is connected and pressed and fixed in the inner cavity of the valve cover 10 by a sealing seat 5, a pressure sleeve 8, and a pressure plate 9. More specifically, as... Figure 2 and Figure 3 As shown, the magnetic liquid sealing device is disposed in the hollow cavity of the valve cover 10 and sleeved on the outside of the valve stem 3. It includes an annular electromagnet 702, a pole shoe 703, and a magnetic liquid 704. The annular electromagnet 702 and the pole shoe 703 are arranged along the axial direction of the valve stem 3. The annular electromagnet 702, the pole shoe 703, and the valve stem 3 form a closed magnetic circuit. A sealing gap is formed between the inner annular surface of the pole shoe 703 and the outer circular surface of the valve stem 3. The magnetic liquid 704 is attracted and held at the sealing gap under the action of the magnetic field formed by the closed magnetic circuit to form a magnetic liquid sealing ring. The magnetic liquid sealing device is a key component for solving the dynamic sealing of the valve stem 3. Its principle is as follows: after the annular electromagnet 702 is energized, it generates a magnetic field. This magnetic field is converged by the pole shoe 703, passes through the tiny sealing gap between the inner annular surface of the pole shoe 703 and the outer circular surface of the valve stem 3, and then returns to the annular electromagnet 702 through the valve stem 3 body, forming a closed magnetic circuit with low magnetic resistance. Under the action of magnetic gradient force, the magnetic liquid 704 is firmly adsorbed at the sealing gap and forms a continuous and flexible liquid O-ring seal along the circumference. There is no solid contact between the sealing ring and the valve stem 3. When the valve stem 3 reciprocates, it only needs to overcome the viscous resistance of the magnetic liquid, thus eliminating solid friction and wear in principle.

[0033] The intelligent monitoring and regulation system includes a pressure transmitter 14 for monitoring the medium pressure at the outlet of the valve body 1, a power supply 16 electrically connected to the ring electromagnet 702, and a central control system 15 signal-connected to the pressure transmitter 14 and the power supply 16. The central control system 15 controls the power supply 16 to adjust the current input to the ring electromagnet 702 based on the pressure signal fed back by the pressure transmitter 14, thereby changing the magnetic field strength and adjusting the sealing force. The intelligent monitoring and regulation system constructs adaptive sealing control. Its principle is as follows: the pressure transmitter 14 collects the pressure signal of the medium at the outlet of the valve body 1 in real time and transmits it to the central control system 15. The central control system 15 issues a current regulation command to the power supply 16 according to a preset control strategy (i.e., the central control system 15 internally stores or presets the optimal magnetic field current magnitude required under different pressure conditions). The power supply 16 correspondingly changes the excitation current of the ring electromagnet 702. An increase in current strengthens the magnetic field, increases the magnetic gradient force on the magnetic fluid 704, and improves the sealing ring's ability to resist the medium pressure difference; a decrease in current correspondingly reduces the sealing capacity. This enables the sealing force to follow the medium pressure in real time, ensuring that the sealing force always matches the operating conditions.

[0034] like Figure 2As shown, there are multiple annular electromagnets 702, which are spaced apart along the axial direction of the valve stem 3. The pole shoes 703 are positioned between adjacent annular electromagnets 702. Each annular electromagnet 702, its adjacent pole shoe 703, and the corresponding section of the valve stem 3 form an independent closed magnetic circuit. These multiple magnetic circuits are connected in series axially, covering the entire sealing stroke of the valve stem 3. When the valve stem 3 moves axially during opening and closing, regardless of its position in the stroke, at least one magnetic circuit is always in an effective working state, avoiding the problem of a sharp decrease in magnetic field strength after the valve stem 3 moves out of the magnetic pole's area of ​​action, as seen in single-circuit structures. This structure allows the magnetic fluid 704 to be stably maintained in the sealing gap throughout the entire stroke of the valve stem 3, improving the stroke adaptability of the sealing device.

[0035] Furthermore, the ring electromagnet 702 includes an upper ring electromagnet, a middle ring electromagnet, and a lower ring electromagnet arranged sequentially along the axial direction of the valve stem 3. The pole shoe 703 includes an upper pole shoe disposed between the upper ring electromagnet and the middle ring electromagnet, and a lower pole shoe disposed between the middle ring electromagnet and the lower ring electromagnet. That is, by adopting a specific configuration of three sets of ring electromagnets 702 and two sets of pole shoes 703 alternately arranged, two complete closed magnetic circuits are constructed within a limited axial space. Compared with a single magnetic circuit, without increasing the power of a single electromagnet, the axial length of the magnetic field action area is effectively extended by connecting the magnetic circuits in series, while improving the gradient strength of the magnetic field at the sealing gap, thereby improving the accumulation concentration of the magnetic liquid 704 and the sealing pressure difference withstand capability.

[0036] like Figure 2 As shown, the inner annular surface of the pole shoe 703 is provided with multiple levels of axially arranged pole teeth 706, forming multiple levels of sealing gaps between the pole teeth 706 and the outer circular surface of the valve stem 3. The protruding structure of the pole teeth 706 causes the radial gap between the inner annular surface of the pole shoe 703 and the outer circular surface of the valve stem 3 to exhibit periodic changes along the axial direction, with the gap being smallest at the tip of the pole teeth 706 and relatively larger at the tooth groove. When the magnetic field passes through the tip of the pole teeth 706, a large magnetic field gradient is generated at that point due to the abrupt change in the cross-sectional area of ​​the magnetic circuit. Under the action of the magnetic field gradient force, the magnetic liquid 704 preferentially accumulates at the tiny gap at the tip of the pole teeth 706, forming an independent liquid O-ring seal at each pole tooth 706. The multiple levels of pole teeth 706 are connected in series to form multiple sealing barriers. When the medium pressure acts on the first sealing ring, even if a very small amount of magnetic liquid undergoes slight displacement, the subsequent sealing rings can still maintain an intact sealing shape, improving the pressure resistance and reliability of the sealing device.

[0037] like Figure 3As shown, when DC current is applied to the three ring electromagnets 702, each electromagnet is magnetized, generating N and S poles. The presence of the magnetic isolation ring 701 forces the magnetic field to pass through the valve cover 10 in sequence, i.e., ring electromagnet 702 → one side pole shoe 703 → through the sealing gap between the pole shoe tooth tip and the valve stem → valve stem 3 → through the opposite sealing gap → opposite pole shoe 703 → back to ring electromagnet 702, thus forming a closed magnetic circuit with low magnetic resistance. The three electromagnets and the two sets of pole shoes together constitute two effective magnetic field loops that can cover the entire sealing section of the valve stem.

[0038] In addition, the combination design of three electromagnets and two sets of pole shoes has the following advantages: it can ensure that the valve stem surface is always within the effective strong magnetic field range throughout the entire working stroke of the valve stem 3, thus avoiding the problem of decreased magnetic fluid constraint force caused by the valve stem moving to the edge of the magnetic field.

[0039] The sealing gap height formed by the pole tooth 706 and the outer circle of the valve stem 3 is 0.01~0.02mm. Furthermore, as a preferred embodiment, the pole tooth 706 can have a rectangular cross-section, with a tooth width B of 0.15~0.25mm, a tooth height H of 0.6~0.7mm, and a tooth groove width L of 0.75~0.85mm. The rectangular cross-section of the pole tooth 706 facilitates precision machining and enables the formation of a uniform magnetic field gradient distribution on the inner annular surface of the pole shoe, allowing the magnetic liquid 704 to form a stable multi-stage liquid O-ring seal at the sealing gap, thereby achieving a superior sealing effect.

[0040] The magnetic liquid 704 is composed of a fluoroether oil-based carrier liquid and magnetite nanoparticles, and has high saturation magnetization and good thermal stability. The diameter of the magnetite nanoparticles ranges from 0.5 to 3.5 nm.

[0041] like Figure 1 As shown, deep groove ball bearings 6 are respectively provided at both ends of the magnetic liquid sealing device along its axial direction. The deep groove ball bearings 6 are sleeved on the outside of the valve stem 3 and abut against the inner wall of the hollow cavity of the valve cover 10. The functions of the deep groove ball bearings 6 are: 1. To provide precise radial support for the valve stem 3, limiting the offset of the valve stem 3 in the direction perpendicular to the axis, ensuring that the sealing gap between the valve stem 3 and the inner annular surface of the pole shoe 703 remains uniform and stable, and preventing the sealing performance from being affected by the local increase or decrease in the sealing gap due to the misalignment of the valve stem 3; 2. During the reciprocating motion of the valve stem 3, to convert the sliding friction between the valve stem 3 and the valve cover 10 into bearing rolling friction, reducing the opening and closing torque and reducing the load on the drive mechanism; 3. The positioning function of the bearings ensures that the valve stem 3 and the magnetic liquid sealing device maintain precise coaxiality, avoiding the problem of uneven sealing gap caused by misalignment during assembly.

[0042] The magnetic liquid sealing device also includes a magnetic isolation ring 701 disposed between the annular electromagnet 702 and the deep groove ball bearing 6. When the annular electromagnet 702 is energized, the magnetic lines of force generated tend to close along the path of least magnetic resistance. If the magnetic circuit is not forcibly constrained, some magnetic lines of force will pass directly from the annular electromagnet 702 through the valve cover 10 or the deep groove ball bearing 6, forming a short circuit, resulting in a reduction in the effective magnetic flux actually passing through the sealing gap. The magnetic isolation ring 701 utilizes its high magnetic resistance characteristics to form a magnetic barrier between the annular electromagnet 702 and the surrounding metal components, forcing the magnetic lines of force to be unable to return via the valve cover 10 or the bearing, but instead to pass sequentially through the annular electromagnet 702, the pole shoe 703, the sealing gap, and the valve stem 3 before returning, thereby maximizing the concentration of magnetic flux at the sealing gap. This improves the efficiency of magnetic field utilization, achieving stronger sealing capability under the same excitation current, while preventing the magnetic field from magnetizing precision components such as bearings.

[0043] like Figure 2 As shown, a sealing groove is formed on the outer circumference of the pole shoe 703, and a sealing ring 705 is embedded in the sealing groove to form a static seal with the inner wall of the valve cover 10. In the magnetic liquid sealing device, the pole shoe 703 and the valve cover 10 are at a static fit interface. If a leakage channel exists at this interface, the medium will bypass the magnetic liquid sealing ring and leak outward along the gap between the outer wall of the pole shoe 703 and the inner wall of the valve cover 10, causing the magnetic liquid sealing ring to lose its main sealing function. By establishing a reliable static seal at this interface through the sealing ring 705, the medium is forced to flow along the sealing gap between the valve stem 3 and the pole tooth 706, ensuring that the magnetic liquid sealing ring becomes the only leakage path, thereby fully utilizing the sealing efficiency of the multi-stage magnetic liquid seal.

[0044] Preferably, the power supply 16 is a DC power supply with an adjustable output voltage ranging from 30 to 150V.

[0045] A sealing control method for a pressure-adaptive magnetic liquid-sealed shut-off valve, characterized by comprising the following steps:

[0046] Step S1: Monitor the medium pressure at the outlet of valve body 1 in real time through pressure transmitter 14, and transmit the pressure signal to central control system 15.

[0047] Step S2: The central control system 15 compares the received pressure signal with the preset pressure threshold and generates a current adjustment command based on the comparison result, as follows:

[0048] Step S2.1: When the medium pressure is higher than the first preset pressure threshold, the central control system 15 controls the power supply 16 to increase the current output to the ring electromagnet 702 to enhance the magnetic field strength and thus improve the sealing force of the magnetic liquid sealing device.

[0049] For example, when the medium pressure is greater than 2MPa, the central control system 15 sends an enhanced magnetization current command to the power supply 16 to increase the voltage. The current is increased to more than 5A by monitoring the ammeter 17, so as to strengthen the magnetic field strength and sealing force of the magnetic liquid sealing device.

[0050] Step S2.2: When the medium pressure is lower than the second preset pressure threshold, the central control system 15 controls the power supply 16 to reduce the current output to the ring electromagnet 702, so as to weaken the magnetic field strength and thus reduce the sealing force of the magnetic liquid sealing device.

[0051] For example, when the pressure of the medium in the pipeline is less than 1MPa, the central control system 15 sends a command to the power supply 16 to reduce the magnetization current and lower the voltage. The current is then reduced to below 2A by monitoring the current through the ammeter 17, thereby reducing the magnetic field strength and sealing force of the magnetic liquid sealing device.

[0052] In summary, this invention uses a magnetic liquid seal at the valve stem instead of a traditional contact seal. A magnetic field attracts the magnetic liquid into the sealing gap, forming a liquid O-ring. During valve stem movement, there is no solid contact between the valve stem and the pole teeth, eliminating friction and wear at the source and preventing seal failure due to wear, thus achieving long service life and maintenance-free operation. By arranging multiple sets of annular electromagnets and pole shoes along the axial direction, multiple series-connected closed magnetic circuits are formed, ensuring that the valve stem is in a strong magnetic field zone throughout its entire stroke, overcoming the defect of magnetic field attenuation at the edges of the magnetic poles in traditional magnetic liquid seals.

[0053] Furthermore, this invention constructs a closed-loop control system for pressure monitoring and current regulation. The pressure transmitter collects the medium pressure in real time, and the central control system dynamically adjusts the excitation current of the electromagnet according to pressure changes, so that the sealing force adapts synchronously with the medium pressure. That is, when the pressure increases, the sealing force is automatically strengthened to ensure zero leakage, and when the pressure decreases, the sealing force is automatically weakened to reduce energy consumption. This combination of non-contact structure and intelligent control enables the shut-off valve to actively adapt to complex working conditions such as high-pressure impacts and pressure fluctuations, making it particularly suitable for harsh applications with extremely high requirements for sealing reliability, such as petrochemical and hydrogen energy industries.

[0054] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A pressure-adaptive magnetic liquid-sealed shut-off valve, characterized in that: include: Valve body (1), wherein the valve body (1) is a three-way structure having an inlet, an outlet and an upper port; Valve cover (2), which is fixedly connected to the upper port of valve body (1), and has a hollow cavity inside; An opening and closing assembly, the opening and closing assembly including a valve stem (3), the valve stem (3) being reciprocally inserted into the hollow cavity of the valve cover (10); A magnetic liquid sealing device is disposed in the hollow cavity of the valve cover (10) and sleeved on the outside of the valve stem (3). It includes an annular electromagnet (702), a pole shoe (703), and a magnetic liquid (704). The annular electromagnet (702) and the pole shoe (703) are arranged along the axial direction of the valve stem (3). The annular electromagnet (702), the pole shoe (703), and the valve stem (3) form a closed magnetic circuit. A sealing gap is formed between the inner annular surface of the pole shoe (703) and the outer circular surface of the valve stem (3). The magnetic liquid (704) is adsorbed and held at the sealing gap under the action of the magnetic field formed by the closed magnetic circuit to form a magnetic liquid sealing ring. The intelligent monitoring and regulation system includes a pressure transmitter (14) for monitoring the medium pressure at the outlet of the valve body (1), a power supply (16) electrically connected to the ring electromagnet (702), and a central control system (15) signal-connected to the pressure transmitter (14) and the power supply (16). The central control system (15) controls the power supply (16) to adjust the current input to the ring electromagnet (702) according to the pressure signal fed back by the pressure transmitter (14), so as to change the magnetic field strength and thus adjust the sealing force.

2. The pressure-adaptive magnetic liquid-sealed shut-off valve according to claim 1, characterized in that: The number of ring electromagnets (702) is multiple, and the multiple ring electromagnets (702) are spaced apart along the axial direction of the valve stem (3), and the pole shoes (703) are arranged between adjacent ring electromagnets (702).

3. The pressure-adaptive magnetic liquid-sealed shut-off valve according to claim 2, characterized in that: The ring electromagnet (702) includes an upper ring electromagnet, a middle ring electromagnet and a lower ring electromagnet arranged sequentially along the axial direction of the valve stem (3), and the pole shoe (703) includes an upper pole shoe disposed between the upper ring electromagnet and the middle ring electromagnet, and a lower pole shoe disposed between the middle ring electromagnet and the lower ring electromagnet.

4. The pressure-adaptive magnetic liquid-sealed shut-off valve according to claim 1, characterized in that: The inner ring surface of the pole shoe (703) is provided with multiple levels of pole teeth (706) arranged axially, and the pole teeth (706) and the outer circular surface of the valve stem (3) form a multi-level sealing gap.

5. The pressure-adaptive magnetic liquid-sealed shut-off valve according to claim 1, characterized in that: The magnetic liquid sealing device is provided with deep groove ball bearings (6) at both ends of the axial direction. The deep groove ball bearings (6) are sleeved on the outside of the valve stem (3) and abut against the inner wall of the hollow cavity of the valve cover (10).

6. The pressure-adaptive magnetic liquid-sealed shut-off valve according to claim 5, characterized in that: The magnetic liquid sealing device also includes a magnetic isolation ring (701) disposed between the annular electromagnet (702) and the deep groove ball bearing (6).

7. The pressure-adaptive magnetic liquid-sealed shut-off valve according to claim 1, characterized in that: The outer ring surface of the pole shoe (703) is provided with a sealing ring groove, and a sealing ring (705) for forming a static seal with the inner wall of the valve cover (10) is embedded in the sealing ring groove.

8. The pressure-adaptive magnetic liquid-sealed shut-off valve according to claim 1, characterized in that: The power supply (16) is a DC power supply with an adjustable output voltage.

9. The pressure-adaptive magnetic liquid-sealed shut-off valve according to claim 1, characterized in that: The magnetic fluid (704) is composed of a fluoroether oil-based carrier fluid and magnetite nanoparticles.

10. The sealing control method for a pressure-adaptive magnetic liquid-sealed shut-off valve according to claim 1, characterized in that: Includes the following steps: Step S1: Monitor the medium pressure at the outlet of the valve body (1) in real time through the pressure transmitter (14) and transmit the pressure signal to the central control system (15). Step S2: The central control system (15) compares the received pressure signal with the preset pressure threshold and generates a current adjustment command based on the comparison result. The command is as follows: Step S2.1: When the medium pressure is higher than the first preset pressure threshold, the central control system (15) controls the power supply (16) to increase the current output to the ring electromagnet (702) to enhance the magnetic field strength and thus improve the sealing force of the magnetic liquid sealing device; Step S2.2: When the medium pressure is lower than the second preset pressure threshold, the central control system (15) controls the power supply (16) to reduce the current output to the ring electromagnet (702) to weaken the magnetic field strength and thus reduce the sealing force of the magnetic liquid sealing device.

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