Multi-seal stop valve with pressure self-balancing function for nuclear power

Abstract

This application relates to the field of fluid control, and in particular to a multi-seal shut-off valve for nuclear power plants with pressure self-balancing function. It includes a valve body, valve stem, valve cover, valve disc, and valve seat. The valve body includes a main cavity, an inlet cavity, and an outlet cavity. The valve seat divides the main cavity into an upper cavity and a lower cavity. A first guide hole and a first sealing structure are provided between the inlet cavity and the lower cavity. A second guide hole and a second sealing structure are formed between the outlet cavity and the upper cavity. The valve stem is connected to the first and second sealing structures. Driving the valve stem to slide allows the first and second sealing structures to simultaneously seal the first and second guide holes. By utilizing these structural combinations, this application enables the valve to achieve pressure self-balancing and multiple sealing effects, effectively enhancing the valve's fluid control capability and improving the stability and durability of the valve.

Description

Technical Field

[0001] This application relates to the field of valve technology, and in particular to a multi-seal shut-off valve for nuclear power plants with pressure self-balancing function. Background Technology

[0002] As a key component of pressure pipeline systems in petrochemical, oilfield, metallurgical, thermal power, nuclear power, and shipbuilding industries, valves have witnessed the continuous advancement of industrial technology throughout their development. From early simple shut-off devices to today's multi-functional precision equipment, the improved performance of valves has provided strong support for the stable operation and efficient production of various industries. In the nuclear power sector, valves bear the crucial mission of ensuring nuclear safety, and their quality and reliability are directly related to the overall safety and stability of the nuclear power plant. With the continuous development of industry, the performance requirements for valves are becoming increasingly stringent, demanding not only excellent sealing performance but also the ability to adapt to complex and changing operating conditions.

[0003] Pressure self-balancing valves can achieve self-balancing of medium pressure acting on the opening and closing parts through the principle of pressure self-balancing, fundamentally eliminating the impact of medium pressure on valve operation performance, sealing quality and sealing life.

[0004] In traditional valve technology, different technical methods are typically employed to meet the requirements of shut-off sealing and pressure balance. For shut-off sealing, the conventional approach relies on the direct contact between the valve disc and the valve seat to cut off the pipeline. Regarding pressure balance, some valves employ a self-balancing design. Through the principle of pressure self-balancing, the medium pressure acting on the opening and closing parts is balanced, thereby reducing the impact of medium pressure on valve operating performance, sealing quality, and seal life.

[0005] Traditional valves rely solely on the contact between the valve disc and seat for shut-off sealing, making it difficult to achieve multiple seals and simultaneous sealing of multiple critical channels. Under complex operating conditions, this single sealing method is prone to incomplete sealing, leading to media leakage and affecting the normal operation of the valve and the safe operation of the system. Furthermore, traditional pressure balancing methods are also insufficient to fully adapt to complex and variable operating conditions, failing to meet the extremely high sealing requirements of some scenarios, such as the special needs of the nuclear power industry. Summary of the Invention

[0006] To address the issue of poor valve sealing leading to media leakage, this application provides a multi-seal shut-off valve for nuclear power plants with pressure self-balancing function.

[0007] This application provides a multi-sealed shut-off valve for nuclear power plants with pressure self-balancing function, which adopts the following technical solution: A multi-seal shut-off valve for nuclear power plants with pressure self-balancing function includes a valve body, a valve stem, a valve cover, a valve disc, and a valve seat. The valve body includes a main cavity, an inlet cavity at one end of the main cavity, and an outlet cavity at the other end of the main cavity. The valve seat divides the main cavity into an upper cavity and a lower cavity. A first guide hole is provided between the inlet cavity and the lower cavity. A first sealing structure for blocking the first guide hole is provided on the valve body. A second guide hole is formed between the outlet cavity and the upper cavity. A second sealing structure for blocking the second guide hole is also provided on the valve body. The valve stem is connected to the first sealing structure and the second sealing structure, driving the valve stem to slide so that the first sealing structure and the second sealing structure simultaneously seal the first guide hole and the second guide hole.

[0008] By adopting the above technical solution, when the shut-off valve for nuclear power plants needs to be closed, the valve stem is driven to slide, causing the first and second sealing structures to operate synchronously. The first sealing structure blocks the first guide hole, preventing water from the inlet chamber from flowing into the lower chamber; the second sealing structure blocks the second guide hole, preventing water from the outlet chamber from flowing into the outlet chamber. At the same time, the valve disc abuts against the valve seat, restricting liquid from flowing from the lower chamber into the upper chamber, forming a multiple sealing effect. This effectively improves the valve's sealing performance and reliability, fundamentally eliminating the impact of medium pressure on valve operation performance, sealing quality, and sealing life, achieving pressure self-balancing function, and ensuring the stable operation of the nuclear power pipeline system.

[0009] Preferably, the first sealing structure includes an installation cavity formed on the valve body, a first baffle that slides in the installation cavity, and a first linkage assembly disposed between the installation cavity and the valve stem for driving the first baffle to slide. The first baffle has a plurality of water-blocking grooves on the side facing the water inlet cavity to assist in pushing the first baffle to slide. The first guide hole is inclined. When the valve stem is pushed to drive the first baffle to slide toward the first guide hole under the action of the first linkage assembly, the inclined water flow impacts the water-blocking grooves to help the first baffle slide and block the first guide hole.

[0010] By adopting the above technical solution, during valve operation, when the valve stem is pushed, the first linkage component responds to the valve stem's movement, causing the first baffle in the mounting cavity to move towards the first guide hole. Since the first guide hole is inclined, the water flow along its inclined direction generates an impact force with an oblique component. This impact force precisely acts on several water-blocking grooves on the side of the first baffle facing the inlet chamber. This dynamic impact process effectively propels the first baffle to continue sliding smoothly, ultimately sealing the first guide hole promptly and securely, greatly improving the valve's sealing efficiency and reliability.

[0011] Preferably, the water-blocking groove is inclined, and the height of the end of the water-blocking groove near the water inlet cavity is greater than the height of the other end.

[0012] By adopting the above technical solution, when water flows into the inlet chamber, the inclined water-blocking groove, with its height greater than that of the other end near the inlet chamber, can more smoothly and efficiently withstand the impact of the inclined water flow. Compared with ordinary groove type, it can effectively enhance the pushing force of the water flow on the first baffle, so that the first baffle can slide and block the first guide hole with less resistance, making it easier to rotate the valve rod and improving the ease of cutting off the water flow.

[0013] Preferably, the opening of the water-blocking groove is fixed with a soft rubber sheet for sealing the water-blocking groove, an air box is fixed in the mounting cavity, a first pipe is fixed on the side of the first baffle away from the first guide hole, the first pipe is slidably connected to the air box, a piston plate is slidably moved in the air box, a second pipe is fixed on the piston plate and slidably connected to the first pipe, an air collecting cavity is opened on the side wall of the first baffle and communicates with the second pipe, the air collecting cavity is connected to the water-blocking groove, the first pipe is connected to the second pipe, the inner cavity of the second pipe is connected to the side of the piston plate away from the first pipe, and in the initial state, the water-blocking groove is in an inflated state.

[0014] By adopting the above technical solution, the water blocking groove is initially inflated, and both sides of the first baffle are flat. As the valve stem rotates, the valve stem drives the first baffle to slide down. Due to the sealed air box, the piston plate moves down inside the air box, forming a negative pressure cavity above the piston plate. This causes the air in the air collecting cavity to be drawn up to the piston plate. Under the action of negative pressure, the soft rubber outside the water blocking groove gradually adheres to the inner wall of the water blocking groove, initially revealing the concave structure of the entire water blocking groove. Continuing to rotate the valve stem causes the first baffle to continue sliding down. The inclined water impact pulls the first baffle down, making it easy for the operator to rotate the handwheel of the valve stem. Reverse rotation of the valve stem causes the gas in the negative pressure cavity to be squeezed into the air collecting cavity and filled into the water blocking groove, thus making the water blocking groove flat, reducing the downward thrust of the water flow on the first baffle, and making it easier for the operator to open the valve.

[0015] Preferably, the first linkage component includes a vertical rod fixed to the piston plate and a horizontal rod fixed to the end of the vertical rod away from the gas box. The vertical rod is slidably connected to the gas box and slides within the mounting cavity. The end of the horizontal rod away from the vertical rod is fixedly connected to the valve stem. A guide hole is provided on the inner wall of the upper cavity, and the guide hole communicates with the inner cavity of the mounting cavity. A second baffle is fixed inside the upper cavity to prevent liquid from seeping into the mounting cavity.

[0016] By adopting the above technical solution, the first linkage assembly composed of vertical rod and horizontal rod can drive the valve stem to move the first baffle, thereby blocking the first guide hole; the guide hole can connect the upper cavity and the inner cavity of the installation cavity, making the movement of the first baffle smoother; the second baffle can prevent liquid from seeping into the installation cavity, ensuring the normal operation of the first linkage assembly.

[0017] Preferably, a corrugated plate for sealing the guide hole is fixed at the opening of the guide hole.

[0018] By adopting the above technical solution, a corrugated plate is installed at the opening of the guide hole to further prevent liquid from seeping into the installation cavity from the guide hole, thereby improving the sealing performance and reliability of the valve.

[0019] Preferably, the second sealing structure includes a groove formed at the second guide hole, a third baffle that slides in the groove, and a connecting rod fixedly connected to the valve stem on the third baffle.

[0020] By adopting the above technical solution, when the valve stem slides, the third baffle can be driven to slide in the groove through the linkage rod to block the second guide hole. In conjunction with the first sealing structure to block the first guide hole, multiple seals are achieved, and the first sealing structure and the second sealing structure can simultaneously seal the first guide hole and the second guide hole.

[0021] Preferably, the end edges of both the first guide hole and the second guide hole are arc-shaped.

[0022] By adopting the above technical solution, the resistance of the fluid when passing through the first guide hole and the second guide hole is reduced, the scouring and wear of the fluid on the edge of the guide hole is reduced, and the service life of the valve is extended.

[0023] In summary, this application includes at least one of the following beneficial technical effects: 1. By connecting the first sealing structure and the second sealing structure through the valve stem, the first sealing structure and the second sealing structure can simultaneously seal the first guide hole and the second guide hole, breaking the limitation of the single sealing method of traditional valves, achieving multiple sealing and simultaneous sealing of multiple key channels, effectively solving the problem of traditional valves being prone to poor sealing, and improving the sealing reliability of valves under complex working conditions; 2. The inclined first guide hole and the water blocking groove on the first baffle plate, when the valve stem is pushed, the inclined water flow impacts the water blocking groove and helps the first baffle plate slide to block the first guide hole, which significantly enhances the sealing effect compared with the traditional valve sealing method; 3. Designing the end edges of the first and second guide holes as arcs is an innovative feature that distinguishes it from traditional valves. This reduces the impact and wear of water flow on the edges of the guide holes, significantly improving the service life of the valve. Attached Figure Description

[0024] Figure 1 This is an isometric view of the overall structure of this application.

[0025] Figure 2 This is a cross-sectional view of the overall structure of this application.

[0026] Figure 3 This is a cross-sectional view of the overall structure of this application after removing the inlet and outlet water chambers.

[0027] Figure 4 This is a partial structural cross-sectional view of this application, mainly used to illustrate the first sealing structure.

[0028] Reference numerals: 1. Valve body; 2. Valve stem; 3. Valve cover; 4. Valve disc; 5. Valve seat; 6. Main cavity; 7. Inlet cavity; 8. Outlet cavity; 9. Upper cavity; 10. Lower cavity; 11. First guide hole; 12. First sealing structure; 13. Second guide hole; 14. Second sealing structure; 15. Mounting cavity; 16. First baffle; 17. First linkage assembly; 18. Water blocking groove; 19. Soft rubber sheet; 20. Air box; 21. First pipe; 22. Piston plate; 23. Second pipe; 24. Air collecting cavity; 25. Vertical rod; 26. Horizontal rod; 27. Guide hole; 28. Second baffle; 29. ​​Corrugated plate; 30. Slide groove; 31. Third baffle; 32. Linkage rod. Detailed Implementation

[0029] The following is in conjunction with the appendix Figure 1-4 This application will be described in further detail.

[0030] This application discloses a multi-seal shut-off valve for nuclear power plants with pressure self-balancing function.

[0031] Reference Figure 1 and Figure 2 The nuclear power plant multi-seal shut-off valve with pressure self-balancing function provided in this application embodiment includes a valve body 1, a valve stem 2, and a valve cover 3. In this embodiment, the valve body 1 is rectangular, with round pipe joints fixedly installed on both sides, forming an inlet chamber 7 on one side and an outlet chamber 8 on the other. Specifically, the valve body 1 includes a main cavity 6, an inlet chamber 7, and an outlet chamber 8. The main cavity 6 is the core space of the entire valve, where various media flow and are subject to corresponding control operations. The inlet chamber 7 is located at one end of the main cavity 6 and serves as the inlet for the media to flow into the valve; its structural design facilitates the smooth entry of the media into the main cavity 6. The outlet chamber 8 is located at the other end of the main cavity 6 and serves as the outlet for the media to flow out of the valve; its structure facilitates the smooth discharge of the media.

[0032] Reference Figure 2 and Figure 3 The water inlet chamber 7 and the main chamber 6 are connected by the first guide hole 11, and the water outlet chamber 8 and the main chamber 6 are connected by the second guide hole 13.

[0033] Reference Figure 2 and Figure 3The nuclear power plant multi-sealed shut-off valve with pressure self-balancing function disclosed in this embodiment also includes a valve disc 4, a valve seat 5, a first sealing structure 12, and a second sealing structure 14. The valve stem 2 passes through the main cavity 6 and is connected to the valve seat 5. The valve cover 3 covers the valve body 1 to seal the main cavity 6. A handwheel is coaxially fixed at the end of the valve stem 2 away from the main cavity 6. Rotating the handwheel causes the valve stem 2, which is threaded onto the valve cover 3, to move vertically downward, thereby opening and closing the valve.

[0034] Reference Figure 2 and Figure 3 In this embodiment, the valve stem 2 is connected to the first sealing structure 12 and the second sealing structure 14. By driving the valve stem 2 to slide, the first sealing structure 12 and the second sealing structure 14 can simultaneously seal the first guide hole 11 and the second guide hole 13, thereby enhancing the valve's sealing performance, achieving pressure self-balancing, and adapting to complex working conditions. This is because synchronous sealing can avoid the problem of partial channel sealing failure under traditional single sealing methods, and can better balance the pressure between different cavities within the valve.

[0035] Reference Figure 2 The valve seat 5 divides the main chamber 6 into an upper chamber 9 and a lower chamber 10. This division facilitates zoned control of the media flow. In this embodiment, the main chamber 6 can be made of a robust metal material to ensure it can withstand high pressure and complex operating conditions. The shapes of the inlet chamber 7 and the outlet chamber 8 are usually designed according to specific pipeline connection requirements, commonly circular or square.

[0036] Reference Figure 3 and Figure 4 The first sealing structure 12 includes a mounting cavity 15, a first baffle 16, and a first linkage assembly 17. The mounting cavity 15 is located on the valve body 1, providing space for the installation and movement of the first baffle 16 and the first linkage assembly 17. The first baffle 16 slides within the mounting cavity 15, and its material can be a composite metal material with good sealing performance and high strength to ensure effective sealing of the first guide hole 11. The first linkage assembly 17 is disposed between the mounting cavity 15 and the valve stem 2, and is used to drive the first baffle 16 to slide.

[0037] Reference Figure 2 , Figure 3 and Figure 4The first baffle 16 has several water-blocking grooves 18 on the side facing the water inlet chamber 7. These water-blocking grooves 18 are inclined, and the height of the end near the water inlet chamber 7 is greater than the height of the other end. This inclined design allows the inclined water flow to better impact the water-blocking grooves 18 when the push valve rod 2 is driven by the first linkage assembly 17 to slide the first baffle 16 toward the first guide hole 11, thereby helping the first baffle 16 slide and block the first guide hole 11. For example, in some operating conditions with large flow and high pressure, this design can reduce the force required to operate the valve by utilizing the impact force of the water flow, thereby improving the opening and closing efficiency of the valve.

[0038] Reference Figure 3 and Figure 4 The opening of the water-blocking groove 18 is fixed with a soft rubber sheet 19 for sealing the water-blocking groove 18. The soft rubber sheet 19 is usually made of rubber and has good flexibility and sealing performance. An air box 20 is fixed inside the mounting cavity 15. The air box 20 provides the basis for subsequent air pressure balance and assist function. A first pipe 21 is fixed on the side of the first baffle 16 away from the first guide hole 11. The first pipe 21 is slidably connected to the air box 20. A piston plate 22 is slidably arranged inside the air box 20. A second pipe 23, which is slidably connected to the first pipe 21, is fixed on the piston plate 22.

[0039] Reference Figure 3 and Figure 4 In this embodiment, the first pipe 21 and the second pipe 23 are configured to slide. In order to drive the valve stem 2 downward in the initial state, since the impact pressure of the water flow is greater than the negative pressure required to absorb the soft rubber 19, the second pipe 23 will be moved to the point where it can no longer slide relative to the first pipe 21. If the valve stem 2 is driven downward at this time, the first pipe 21 will continue to move downward against the second pipe 23, thereby causing the first baffle 16 to move downward with the soft rubber 19 tightly attached to the inner wall of the water blocking groove 18 and block the first guide hole 11.

[0040] Reference Figure 2 , Figure 3 and Figure 4In order to achieve the effect of sealing the valve, the soft rubber 19 on the water blocking groove 18 is tightly attached to the inner wall of the water blocking groove 18 to form a groove structure. When the valve is opened, the soft rubber 19 on the water blocking groove 18 is inflated and expanded, so that the side wall of the first baffle 16 is flat. In this embodiment, an air collecting chamber 24 connected to the second pipe 23 is provided on the side wall of the first baffle 16. The air collecting chamber 24 is connected to the water blocking groove 18, the first pipe 21 is connected to the second pipe 23, and the inner cavity of the second pipe 23 is connected to the side of the piston plate 22 away from the first pipe 21. In the initial state, the water blocking groove 18 is in an inflated state. During valve closing, as the first baffle 16 moves, one side of the piston plate 22 is under negative pressure. This draws in air from the water-blocking groove 18, causing the soft rubber 19 to adhere tightly to the side wall of the water-blocking groove 18, thus creating a groove structure. Water flow impacts the water-blocking groove 18, generating a downward pulling force on the first baffle 16. Conversely, when the valve is closed, air fills the water-blocking groove 18, making one side of the first baffle 16 flat and reducing the impact of water flow on the first baffle 16 when the valve is opened.

[0041] Reference Figure 3 and Figure 4 The first linkage assembly 17 includes a vertical rod 25 and a horizontal rod 26. The vertical rod 25 is fixed to the piston plate 22 and slidably connected to the air box 20, and the vertical rod 25 slides within the mounting cavity 15. The horizontal rod 26 is fixed to the end of the vertical rod 25 away from the air box 20, and the end of the horizontal rod 26 away from the vertical rod 25 is fixedly connected to the valve stem 2. This structural design allows the movement of the valve stem 2 to be effectively transmitted to the piston plate 22 through the horizontal rod 26 and the vertical rod 25, thereby driving the first baffle 16 to move.

[0042] Reference Figure 3 and Figure 4 A guide hole 27 is provided on the inner wall of the upper cavity 9, which connects to the inner cavity of the mounting cavity 15. Its function is to provide guidance for the movement of the vertical rod 25, ensuring more stable movement of the entire first linkage assembly 17. A second baffle 28 is fixed inside the upper cavity 9 to prevent liquid from seeping into the mounting cavity 15. The second baffle 28 is typically made of a corrosion-resistant and well-sealing material, such as polytetrafluoroethylene (PTFE). A corrugated plate 29 is fixed at the opening of the guide hole 27 to seal it. The corrugated plate 29 can be made of stainless steel or similar materials. It ensures smooth movement of the vertical rod 25 within the guide hole 27 and further prevents liquid from seeping into the mounting cavity 15, protecting the normal operation of the first linkage assembly 17.

[0043] Reference Figure 3The second sealing structure 14 includes a groove 30, a third baffle 31, and a connecting rod 32. The groove 30 is formed at the second guide hole 13, providing a track for the sliding of the third baffle 31. The third baffle 31 slides within the groove 30, and its material and structure are similar to those of the first baffle 16, also requiring good sealing performance. The connecting rod 32 is fixed to the third baffle 31 and is fixedly connected to the valve stem 2. When the valve stem 2 moves, the connecting rod 32 drives the third baffle 31 to slide within the groove 30, thereby achieving a seal on the second guide hole 13.

[0044] Reference Figure 3 In this embodiment, the end edges of both the first guide hole 11 and the second guide hole 13 are rounded. This rounded design can reduce the resistance of the medium when passing through the first guide hole 11 and the second guide hole 13, reduce the impact force of the water flow on the edges, and thus extend the service life of the first guide hole 11, the second guide hole 13 and the sealing parts.

[0045] The implementation principle of this embodiment is as follows: This nuclear power plant multi-sealed shut-off valve with pressure self-balancing function divides the valve body 1 into multiple chambers and sets up a first sealing structure 12 and a second sealing structure 14 to achieve multiple seals. When the valve needs to be closed, the valve stem 2 is pushed. The valve stem 2 drives the first baffle 16 and the third baffle 31 to move through the first linkage assembly 17 and the connecting rod 32, respectively, so that they simultaneously seal the first guide hole 11 and the second guide hole 13. In this process, the inclined water flow of the first guide hole 11 impacts the water blocking groove 18 on the first baffle 16, and the force of the water flow helps to push the first baffle 16 to move. At the same time, the air pressure assist system formed by the gas box 20, piston plate 22 and other structures also provides auxiliary thrust for the movement of the first baffle 16. The second sealing structure 14 seals the second guide hole 13 synchronously with the movement of the valve stem 2. Through the multiple sealing and synchronous sealing, it better adapts to complex and changing working conditions, reduces the risk of medium leakage, and ensures the normal operation of the valve in various harsh environments. Meanwhile, since the upper cavity 9 is connected to the outlet cavity 8 and is located above the lower cavity 10, the fluid entering from the bottom and exiting from the top balances the pressure between the upper cavity 9 and the lower cavity 10, as well as between the inlet cavity 7 and the outlet cavity 8. This avoids the negative impact of the medium pressure on the valve's operating performance, sealing quality, and sealing life, thereby improving the overall reliability and stability of the valve and meeting the high safety and high performance requirements of valves in fields such as nuclear power.

[0046] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A multi-seal stop valve with pressure self-balancing function for nuclear power, comprising a valve body (1), a valve stem (2), a valve cover (3), a valve disc (4) and a valve seat (5), characterized in that: The valve body (1) comprises a main cavity (6), a water inlet cavity (7) arranged at one end of the main cavity (6), and a water outlet cavity (8) arranged at the other end of the main cavity (6), the valve seat (5) divides the main cavity (6) into an upper cavity (9) and a lower cavity (10), a first flow guide hole (11) is arranged between the water inlet cavity (7) and the lower cavity (10), the valve body (1) is provided with a first sealing structure (12) for sealing the first flow guide hole (11), a second flow guide hole (13) is formed between the water outlet cavity (8) and the upper cavity (9), and the valve body (1) is further provided with a second sealing structure (14) for sealing the second flow guide hole (13), the valve rod (2) is connected with the first sealing structure (12) and the second sealing structure (14), and the valve rod (2) is driven to slide, so that the first sealing structure (12) and the second sealing structure (14) synchronously seal the first flow guide hole (11) and the second flow guide hole (13).

2. The multi-seal stop valve with pressure self-balancing function for nuclear power plants according to claim 1, characterized in that: The first sealing structure (12) comprises a mounting cavity (15) arranged on the valve body (1), a first baffle (16) sliding in the mounting cavity (15), a first linkage assembly (17) arranged between the mounting cavity (15) and the valve rod (2) and used for driving the first baffle (16) to slide, a plurality of water resistance grooves (18) are arranged on one side of the first baffle (16) facing the water inlet cavity (7) and used for assisting the first baffle (16) to slide, and the first flow guide hole (11) is arranged obliquely, when the valve rod (2) is driven to slide the first baffle (16) towards the first flow guide hole (11) under the action of the first linkage assembly (17), the inclined water flow impacts the water resistance grooves (18) to help the first baffle (16) slide and seal the first flow guide hole (11).

3. The multi-seal stop valve with pressure self-balancing function for nuclear power plants according to claim 2, characterized in that: The water resistance grooves (18) are arranged obliquely, and the height of the water resistance grooves (18) near one end of the water inlet cavity (7) is greater than the height of the other end.

4. The multi-seal stop valve with pressure self-balancing function for nuclear power plants according to claim 3, characterized in that: A soft rubber (19) is fixed in the notch of the water resistance groove (18) and used for sealing the water resistance groove (18), an air tank (20) is fixed in the mounting cavity (15), a first pipe (21) is fixed on the side of the first baffle (16) away from the first flow guide hole (11), the first pipe (21) is slidingly connected with the air tank (20), a piston plate (22) is slidingly arranged in the air tank (20), a second pipe (23) is fixed on the piston plate (22) and slidingly connected with the first pipe (21), a gas collection cavity (24) is arranged on the side wall of the first baffle (16) and connected with the second pipe (23), the gas collection cavity (24) is connected with the water resistance groove (18), the first pipe (21) is connected with the second pipe (23), the inner cavity of the second pipe (23) is connected with the side of the piston plate (22) away from the first pipe (21), and in the initial state, the water resistance groove (18) is in an inflated state.

5. The multi-seal stop valve with pressure self-balancing function for nuclear power plants according to claim 4, characterized in that: The first linkage assembly (17) comprises a vertical rod (25) fixed on the piston plate (22), a horizontal rod (26) fixed on the end of the vertical rod (25) away from the air tank (20), the vertical rod (25) is in sliding connection with the air tank (20), the vertical rod (25) slides in the installation cavity (15), the end of the horizontal rod (26) away from the vertical rod (25) is fixedly connected with the valve rod (2), the inner wall of the upper cavity body (9) is provided with a guide hole (27), the guide hole (27) is communicated with the inner cavity of the installation cavity (15), and the second baffle (28) for preventing liquid from seeping into the installation cavity (15) is fixed in the upper cavity body (9).

6. The multi-seal stop valve with pressure self-balancing function for nuclear power plants according to claim 5, characterized in that: The opening of the guide hole (27) is fixed with a corrugated plate (29) for plugging the guide hole (27).

7. The multi-seal stop valve with pressure self-balancing function for nuclear power plants according to claim 1, characterized in that: The second sealing structure (14) comprises a sliding groove (30) provided at the second flow guide hole (13), a third baffle (31) sliding in the sliding groove (30), and a linkage rod (32) fixed on the third baffle (31) and fixedly connected with the valve rod (2).

8. The multi-seal stop valve with pressure self-balancing function for nuclear power plants according to claim 1, characterized in that: The end edges of the first flow guide hole (11) and the second flow guide hole (13) are in arc shape.

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