Self-sealing gate valve

Abstract

The application relates to a self-sealing gate valve, relates to the technical field of valves, and comprises a valve body, a valve cover, a valve rod, a gate plate and a driving mechanism. The valve body is internally provided with a valve seat, and the gate plate is connected to the lower end of the valve rod. The gate plate is internally hollow to form a pressure cavity, the surface is provided with a Venturi tube structure pressurizing hole communicated between a water inlet and the pressure cavity, and a filter screen is arranged at the inlet. Seal grooves are arranged in the two side walls of the gate plate, a disc spring, a blocking ring and a sealing ring with a lip-shaped structure are sequentially arranged in the grooves, and the front end of the sealing ring is a circular-arc-shaped sealing nose. After medium enters the pressure cavity through the pressurizing hole, fluid pressure and the elastic force of the disc spring push the sealing ring to displace outward, the sealing nose tightly presses the valve seat, and the lip-shaped structure is expanded under pressure to prevent internal leakage. The application has the effects of good sealing performance, high automation degree and long service life.

Description

Technical Field

[0001] This application relates to the field of valve technology, and in particular to a self-sealing gate valve. Background Technology

[0002] Gate valves are widely used in fluid control devices in industries such as petroleum, chemical, power, and metallurgy. Their core function is to cut off or connect pipeline media. Under high temperature and high pressure conditions, the sealing performance of gate valves directly affects the safe operation and production efficiency of the system.

[0003] Traditional gate valves primarily rely on the mechanical force (such as wedging force or torque) applied by the valve stem to force the gate sealing surface to fit tightly against the valve seat to achieve a seal. However, this structure, which relies solely on mechanically forced sealing, faces severe challenges in high-pressure environments. As pipeline pressure increases, the mechanical closing force required to maintain the seal increases dramatically. This not only demands enormous operating torque from the drive mechanism, making valve opening and closing difficult, but also excessive mechanical compression can easily cause plastic deformation or crushing of the sealing surface under high loads, severely shortening the valve's service life.

[0004] Furthermore, due to machining errors, thermal expansion and contraction, or wear caused by long-term operation, microscopic gaps can easily appear between the rigidly connected gate and valve seat. Once the medium pressure exceeds the mechanical preload, internal leakage will occur. Although existing resilient seated gate valves incorporate elastic elements, their elastic materials are prone to aging and failure or being squeezed out by high pressure when facing high-pressure fluids. Moreover, they lack a dynamic pressure compensation mechanism, making it difficult to maintain a constant and reliable sealing effect under conditions of drastic pressure fluctuations. Therefore, developing a gate valve structure that can utilize the medium's own energy for sealing compensation and automatically enhance the sealing specific pressure under high pressure is particularly important.

[0005] In view of the above-mentioned related technologies, the present invention provides a self-sealing gate valve to overcome the shortcomings of the prior art. Summary of the Invention

[0006] The purpose of this application is to provide a self-sealing gate valve that solves the problem that traditional gate valves cannot guarantee reliable sealing under high-pressure conditions by relying solely on mechanical external force, and are prone to short service life due to overload wear of the sealing surface.

[0007] Firstly, this application provides a self-sealing gate valve with the following technical solution: A self-sealing gate valve includes a valve body, a valve cover, a valve stem, a gate plate, a valve seat, and a drive mechanism. The valve body has an inlet and an outlet. The valve cover is disposed on the upper part of the valve body, and the valve stem passes through the valve cover and is located inside the valve body. The top of the gate plate has a mounting groove, and the lower end of the valve stem is connected to the mounting groove. The gate plate is located inside the valve body and between the two valve seats. The drive mechanism is disposed at the top of the valve stem and is used to drive the valve stem to move axially, thereby driving the gate plate to move to control the opening and closing of the gate valve.

[0008] Preferably, the gate has a hollow pressure chamber machined inside, and a pressure hole is formed on the surface of the gate, connecting the water inlet and the pressure chamber. The pressure hole adopts a Venturi tube structure, and a filter screen is provided at the inlet of the pressure hole. Sealing grooves are formed on both side walls of the gate, and the sealing grooves are connected to the pressure chamber. A disc spring, a retaining ring, and a sealing ring are sequentially assembled inside the sealing groove from the inside to the outside. The sealing ring slides in fit with the sealing groove, and a protruding sealing nose is integrally formed on the end of the sealing ring facing the valve seat. When the medium flows through the filter screen and enters the pressure chamber through the pressure hole of the Venturi tube structure, the fluid pressure of the medium acts on the inner surface of the retaining ring and the sealing ring. This fluid pressure and the mechanical elasticity of the disc spring form a combined force, pushing the retaining ring and the sealing ring outward along the sealing groove, causing the sealing nose to abut against and press against the valve seat, thereby forming a sealing fit.

[0009] Preferably, the valve cover is installed in the valve body using a pressure self-tightening sealing structure. A sealing ring is fitted onto the outer wall of the valve cover, a washer is positioned above the sealing ring, and a four-ring is positioned above the washer. The four-ring engages with a groove in the upper inner wall of the valve body. The sealing ring, the washer, and the four-ring are stacked axially to restrict the upward displacement of the valve cover and fix it within the valve body. Simultaneously, the central hole of the valve cover provides an axial movement channel for the valve stem.

[0010] Preferably, a sealing cap is fixed to the upper port of the valve body, covering the valve cover and the four-ring. A packing pressure plate is bolted to the top of the sealing cap. The valve cover has an internal sleeve hole for the valve stem to pass through, and multiple packing blocks are filled between the sleeve hole and the valve stem. A packing sleeve is positioned above the packing blocks, and the packing pressure plate applies downward axial pressure to the packing sleeve, causing the packing sleeve to compress the packing blocks, thereby forming a dynamic seal between the valve stem and the sleeve hole.

[0011] Preferably, a bracket is fixedly connected above the packing pressure plate, and a conical cover is fixedly connected to the top of the bracket. The transmission component of the drive mechanism is housed within the conical cover. The drive mechanism includes a handwheel, a first bevel gear, a second bevel gear, and an adjusting nut. Both the first and second bevel gears are located within the conical cover. The handwheel is fixedly connected to and rotates coaxially with the second bevel gear, and the second bevel gear meshes with the first bevel gear for transmission. The first bevel gear is fixedly connected to the adjusting nut, and the adjusting nut engages with the threaded section of the valve stem. The rotational motion of the handwheel is converted into the rotational motion of the adjusting nut, which in turn is converted into the linear lifting and lowering motion of the valve stem.

[0012] Preferably, the sealing nose has an arc-shaped protrusion structure for forming a line contact seal with the valve seat. The outer cylindrical surface of the sealing ring and the inner cylindrical surface of the sealing groove are in clearance fit, allowing the sealing ring to slide back and forth within the sealing groove in a direction perpendicular to the valve flow path. The retaining ring is located within the sealing groove and between the disc spring and the sealing ring, serving to receive the spring force of the disc spring and evenly transmit this force to the inner end face of the sealing ring.

[0013] Preferably, the venturi structure of the pressurization orifice includes, in sequence along the fluid flow direction, a constriction section, a throat, and a diffuser section. The constriction section is used to increase the fluid flow rate, and the diffuser section is used to restore the fluid pressure, thereby maintaining a stable pressure for the fluid entering the pressure chamber.

[0014] Preferably, the valve body, the gate, the valve cover, and the retaining ring are all made of metal; the sealing ring is made of flexible graphite composite gasket; and the filter screen is embedded in the inlet end face of the pressurization hole to intercept solid particles in the fluid.

[0015] In summary, this application includes at least one of the following beneficial technical effects:

[0016] 1. This invention provides a pressure chamber inside the gate and a venturi tube pressurization hole connected to the inlet. The fluid pressure after the medium enters the pressure chamber works in conjunction with a disc spring to push the sealing ring outward. This results in a higher medium pressure and a greater contact pressure between the sealing ring and the valve seat, thus solving the problem that traditional gate valves cannot guarantee sealing performance under high-pressure conditions by relying solely on mechanical locking force.

[0017] 2. The present invention provides a lip structure on the back of the sealing ring and an arc-shaped sealing nose at the front end; the lip structure expands radially under the action of medium pressure and fits tightly against the side wall of the sealing groove, effectively blocking the medium from flowing out from the gap between the sealing ring and the sealing groove. Combined with the line contact seal formed by the sealing nose and the valve seat, it greatly improves the airtightness and reliability of the sealing assembly under high pressure.

[0018] 3. The present invention sets a filter screen at the inlet of the pressurization hole, and works with the pressure stabilizing structure of the venturi tube and the pre-tightening compensation mechanism of the disc spring; effectively preventing fluid impurities from clogging the internal channel or jamming the sealing components, while ensuring the valve's continuous sealing ability during the low-pressure start-up stage or after slight wear of the sealing surface, thus extending the valve's service life. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of an embodiment of this application;

[0020] Figure 2 This is a cross-sectional structural schematic diagram of the valve body according to an embodiment of this application;

[0021] Figure 3 This is a schematic diagram of the drive mechanism structure according to an embodiment of this application;

[0022] Figure 4 This is a schematic diagram of the valve cover structure according to an embodiment of this application;

[0023] Figure 5 This is a schematic diagram of the packing pressure plate structure according to an embodiment of this application;

[0024] Figure 6 This is a schematic diagram of the filter structure according to an embodiment of this application;

[0025] Figure 7 This is a cross-sectional structural schematic diagram of the gate in an embodiment of this application;

[0026] Figure 8 yes Figure 7 A magnified view of part A in the middle;

[0027] Explanation of reference numerals in the attached drawings: 1. Valve body; 2. Sealing cover; 3. Bracket; 4. Packing pressure plate; 5. Conical cover; 6. Handwheel; 7. Outlet; 8. Inlet; 9. Gate; 10. Valve seat; 11. Valve stem; 12. Valve cover; 13. Sealing ring; 14. Four-way open ring; 15. Packing sleeve; 16. First bevel gear; 17. Adjusting nut; 18. Second bevel gear; 19. Washer; 20. Sleeve hole; 21. Packing block; 22. Mounting groove; 23. Filter screen; 24. Sealing ring; 25. Pressure chamber; 26. Pressurization hole; 27. Disc spring; 28. Retaining ring; 29. ​​Sealing nose; 30. Sealing groove. Detailed Implementation

[0028] The following is in conjunction with the appendix Figure 1 -Appendix Figure 8 This application will be described in further detail below.

[0029] Example:

[0030] Please see the appendix Figure 1 -Appendix Figure 8This invention provides a self-sealing gate valve, comprising a valve body 1, a valve cover 12, a valve stem 11, a gate 9, a valve seat 10, and a drive mechanism. The valve body 1, valve cover 12, and gate 9 are all made of metal to meet the strength requirements under high-pressure conditions.

[0031] The valve body 1 serves as the main supporting component, with an inlet 8 and an outlet 7 on its two sides, respectively. The inlet 8 and the outlet 7 are coaxially connected to form a fluid channel. The valve body 1 has an internal cavity, and two valve seats 10 are fixedly installed on both sides inside the cavity of the valve body 1, located at the inner ports of the inlet 8 and the outlet 7, for cooperation with the gate 9.

[0032] The valve cover 12 is located inside the valve body 1 at the top and is installed and fixed using a pressure self-tightening structure. Specifically, the outer wall of the valve cover 12 has a step or groove for installing a sealing component, and a sealing ring 13 is fitted onto the outer wall of the valve cover 12. In this embodiment, the sealing ring 13 is a flexible graphite composite gasket, which has the characteristics of high temperature resistance, corrosion resistance and good resilience.

[0033] A gasket 19, which is a rigid metal ring, is positioned above the sealing ring 13. A four-ring 14 is positioned above the gasket 19. An annular groove is machined on the upper inner wall of the valve body 1, and the four-ring 14 is inserted into this groove on the inner wall of the valve body 1.

[0034] When the valve cover 12 is pushed upward by the internal medium pressure, the force is transmitted to the four-ring 14 through the sealing ring 13 and the washer 19. Since the four-ring 14 is locked in the groove of the valve body 1, the upward displacement of the valve cover 12 is restricted. Through the axial stacking and cooperation of the sealing ring 13, the washer 19 and the four-ring 14, the valve cover 12 is firmly locked in the valve body 1.

[0035] A sealing cover 2 is fixedly installed at the top port of the valve body 1. The sealing cover 2 is fixed to the valve body 1 by bolts, completely encapsulating the valve cover 12, the four-ring 14 and the sealing ring 13 and other components in the internal space of the valve body 1, which serves as a dustproof and secondary protection function.

[0036] The valve stem 11 passes vertically through the center of the valve cover 12, and its lower end extends into the valve body 1. A sleeve hole 20 is provided at the center of the valve cover 12 for the valve stem 11 to pass through. To prevent the medium from leaking along the valve stem 11, a plurality of packing blocks 21 are filled in the annular gap between the sleeve hole 20 and the valve stem 11.

[0037] A packing sleeve 15 is provided above the packing block 21, and the lower end face of the packing sleeve 15 abuts against the top surface of the packing block 21. A packing pressure plate 4 is provided above the sealing cover 2, and the packing pressure plate 4 is connected to the sealing cover 2 by studs and nuts.

[0038] By tightening the nut on the packing pressure plate 4, the packing pressure plate 4 presses the packing sleeve 15 downward, thereby causing the packing sleeve 15 to axially compress the packing block 21. The compressed packing block 21 expands radially and fits tightly against the outer cylindrical surface of the valve stem 11 and the inner wall of the sleeve hole 20, thus achieving a dynamic seal while allowing the valve stem 11 to move axially.

[0039] Please see the appendix Figure 1 -Appendix Figure 3 Above the aforementioned packing seal structure, a drive mechanism for controlling valve operation is installed. Specifically, a bracket 3 is fixedly connected to the top surface of the packing plate 4 via a bolt assembly. The bracket 3 is made of high-strength cast steel, with a through hole at the center of its bottom for the valve stem 11 to pass through. A conical cover 5 is fixedly connected to the top of the bracket 3, forming a closed receiving space inside the conical cover 5 for installing the gear transmission assembly and providing dust protection and grease retention.

[0040] The main components of the drive mechanism are housed within a conical cover 5, including a handwheel 6, a first bevel gear 16, a second bevel gear 18, and an adjusting nut 17. The second bevel gear 18 is horizontally supported on the side wall of the conical cover 5 by bearings, and its input shaft end extends outside the conical cover 5. The handwheel 6 is fastened to the input shaft end of the second bevel gear 18, and the operator inputs torque by rotating the handwheel 6.

[0041] The first bevel gear 16 is arranged vertically at the center of the conical cover 5 and meshes perpendicularly with the second bevel gear 18. An adjusting nut 17 is fixedly connected to the lower end of the first bevel gear 16, allowing them to rotate synchronously. The inner hole of the adjusting nut 17 is machined with a trapezoidal thread, and the upper part of the valve stem 11 is machined with a matching trapezoidal external thread. The cross-sectional shape of the valve stem 11 itself, or the restriction imposed by an external guide key, is constrained to allow only axial movement and not circumferential rotation.

[0042] Therefore, when the handwheel 6 is turned, driving the second bevel gear 18 to rotate, the first bevel gear 16 and the adjusting nut 17 are driven to rotate in their original positions through gear meshing. The rotating adjusting nut 17 drives the valve stem 11 to move vertically up and down in the valve body 1 through the action of the threaded pair.

[0043] The lower end of the valve stem 11 extends into the receiving cavity of the valve body 1 for connecting the gate 9. A mounting groove 22 is precisely machined at the top center of the gate 9. In this embodiment, the mounting groove 22 has a T-shaped groove structure, and the end of the valve stem 11 is machined into a matching T-shaped hammerhead structure. The end of the valve stem 11 slides laterally into the mounting groove 22, achieving the connection between the two. This connection method provides rigid transmission in the vertical direction, capable of transmitting the pulling force during opening and the thrust force during closing; while maintaining a certain floating clearance in the horizontal plane. This floating connection design allows the gate 9 to make slight adaptive adjustments under pressure, preventing jamming or uneven sealing due to coaxiality errors between the valve stem 11 and the valve seat 10.

[0044] Please see the appendix Figure 6 -Appendix Figure 8 The gate 9 is the core functional component of this invention. It has a wedge-shaped structure and is positioned between the two valve seats 10. The gate 9 is not a solid structure; its interior is formed by casting or machining to create a hollow pressure chamber 25. The pressure chamber 25 serves as an energy storage space for the medium pressure and extends through most of the internal area of ​​the gate 9.

[0045] To introduce external media into the pressure chamber 25, a pressurizing orifice 26 is provided on the surface of the gate 9 facing the direction of media flow, i.e., the side facing the inlet 8. The pressurizing orifice 26 is not a straight orifice of uniform diameter, but rather employs a Venturi tube structure from fluid mechanics. Specifically, the pressurizing orifice 26 includes, in sequence along the direction of media flow, a contraction section, a throat, and a diffuser section. The orifice diameter of the contraction section gradually decreases, used to accelerate and rectify the incoming media; the throat is the point with the smallest orifice diameter; the orifice diameter of the diffuser section gradually increases, connecting to the pressure chamber 25, used to convert the kinetic energy of the media into pressure energy, ensuring that the media entering the pressure chamber 25 has a stable static pressure value.

[0046] A countersunk hole is provided at the inlet end face of the pressure port 26, and a filter screen 23 is interference-fitted into the countersunk hole. The filter screen 23 is made of stainless steel sintered mesh, and its pore size is smaller than the diameter of the throat of the pressure port 26 and the fitting clearance of the subsequent sealing components. It is used to intercept solid particles such as welding slag and iron filings in the medium to prevent the internal flow channel from being blocked or the seal from being stuck.

[0047] Sealing grooves 30 are respectively provided on both sides of the gate 9. The sealing groove 30 is an annular groove, and its bottom is directly connected to the pressure chamber 25 through an internal flow channel, so that the pressure of the medium in the pressure chamber 25 can directly act on the bottom area of ​​the sealing groove 30.

[0048] Inside the sealing groove 30, a disc spring 27, a retaining ring 28, and a sealing ring 24 are assembled sequentially from the inside out.

[0049] First, multiple sets of stacked disc springs 27 are placed at the bottom of the sealing groove 30.

[0050] Secondly, the retaining ring 28 covers the outside of the disc spring 27. The retaining ring 28 is a rigid metal ring, and its outer diameter is in clearance fit with the inner wall of the sealing groove 30. Its function is to provide a flat force-bearing surface, so as to evenly transmit the elastic force of the disc spring 27, while preventing local stress concentration of the spring from damaging subsequent components.

[0051] Finally, the sealing ring 24 is installed on the outermost side of the sealing groove 30 and partially protrudes from the surface of the gate plate 9. The outer cylindrical surface of the sealing ring 24 and the inner wall of the sealing groove 30 are precisely fitted with a clearance, and the mating surfaces are ground to ensure that the sealing ring 24 can slide back and forth in the sealing groove 30 in a direction perpendicular to the valve flow path without jamming or tilting.

[0052] On the outer end face of the sealing ring 24 facing the valve seat 10, a protruding sealing nose 29 is integrally formed. The cross-section of the sealing nose 29 is semi-circular. Compared with traditional flat seals, the arc-shaped sealing nose 29 forms a line contact or an extremely narrow strip contact when it contacts the flat valve seat 10. Under the same axial thrust, this geometry can generate extremely high Hertzian contact stress, thus making it easier to cut off the fluid passage and achieve a tight seal.

[0053] A lip structure is machined on the back side of the sealing ring 24, facing the bottom of the retaining ring 28 and the sealing groove 30. The sealing ring 24 and this lip structure are integrally machined. The lip structure is a flexible edge formed by a thin-walled extension or groove around the back edge of the sealing ring 24. This design utilizes the elastic deformation properties of the material. When the high-pressure medium enters the sealing groove 30, the fluid fills the inside of the lip structure, and the radial component of the medium pressure forces the thin wall of the lip structure to expand outward and fit tightly against the side wall of the sealing groove 30. This pressure self-tightening mechanism effectively prevents the medium from leaking out from the tiny fit gap between the sealing ring 24 and the sealing groove 30, ensuring that all hydraulic thrust is effectively applied in the direction of pushing the sealing ring 24 toward the valve seat 10.

[0054] Working principle: When the valve needs to be closed, the operator turns the handwheel 6 of the drive mechanism clockwise. After the bevel gear set reduces speed and increases torque, the adjusting nut 17 rotates and drives the valve stem 11 to move downward, pushing the gate 9 down into the flow channel of the valve body 1.

[0055] Once the gate 9 has fully descended into position, the sealing nose 29 on the sealing ring 24 initially contacts the sealing surface of the valve seat 10. At this time, although the medium pressure has not yet been fully established, the disc spring 27 located in the sealing groove 30 is in a pre-compressed state. The disc spring 27 releases its axial elastic force, which is transmitted to the sealing ring 24 through the retaining ring 28, giving the sealing nose 29 an initial mechanical preload. This preload is sufficient to overcome the penetration of low-pressure medium and compensate for the microscopic unevenness between the sealing ring 24 and the valve seat 10, establishing an initial sealing interface.

[0056] As the valve closes, the upstream fluid medium impacts the surface of the gate 9. Some of the medium passes through the filter screen 23 and enters the pressure port 26. As it flows through the venturi structure of the pressure port 26, the contraction section accelerates the fluid, reaching its peak velocity at the throat; subsequently, it enters the diffusion section, where the velocity decreases, and the dynamic pressure is converted into static pressure. This process reduces turbulence and pressure pulsation as the fluid enters the internal cavity, allowing the pressure of the medium entering the pressure chamber 25 to rise smoothly and quickly match the system pressure within the pipeline.

[0057] The high-pressure medium filling the pressure chamber 25 enters the bottom space of the sealing groove 30 through the internal flow channel, directly acting on the back of the sealing ring 24 and the inner side of the retaining ring 28. At this time, the sealing ring 24 is subjected to the superposition of thrust from two directions: one is the constant mechanical elastic force of the disc spring 27, and the other is the hydraulic thrust generated by the medium pressure multiplied by the pressure-bearing area;

[0058] When the system pressure increases, the hydraulic thrust increases proportionally, resulting in an automatic increase in the total sealing force. This mechanism ensures that the contact pressure between the sealing nose 29 and the valve seat 10 is always higher than the medium pressure, thus achieving a self-sealing effect where the higher the pressure, the tighter the seal.

[0059] Meanwhile, the high-pressure medium entering the sealing groove 30 acts on the lip structure on the back of the sealing ring 24. Under the action of pressure difference, the edge of the lip expands elastically radially, eliminating the gap between the sealing ring 24 and the side wall of the sealing groove 30, realizing the dynamic sealing of the sealing ring itself, preventing the pressure medium from flowing around and leaking from the back, and ensuring the effective transmission of hydraulic thrust.

[0060] When the valve needs to be opened, the handwheel 6 is turned in the reverse direction, and the valve stem 11 moves the gate 9 upward. As the gate 9 moves away from the center of the flow channel, the pressure at the inlet 8 is no longer continuously introduced through the pressure port 26. After the external pressure decreases, the sealing ring 24 is maintained in the appropriate position only by the disc spring 27, ready for the next working cycle. Since the sealing ring 24 and the valve seat 10 are not rigidly interference-locked but elastically abutted, the frictional resistance at the moment of opening is less than that of a traditional wedge gate valve, reducing the opening and closing torque.

[0061] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be covered within the scope of protection of this application.

Claims

1. A self-sealing gate valve, characterized in that, include, Valve body (1), the valve body (1) having an inlet (8) and an outlet (7); A valve cover (12) is disposed above the interior of the valve body (1); The valve stem (11) passes through the valve cover (12) and is located inside the valve body (1); Gate (9), the top of the gate (9) is provided with a mounting groove (22), and the lower end of the valve stem (11) is connected in the mounting groove (22); Valve seat (10) is disposed inside the valve body (1) and located on both sides of the gate (9); A drive mechanism is provided at the top of the valve stem (11) to drive the valve stem (11) to move, thereby controlling the opening and closing of the entire gate valve; The gate (9) has a hollow interior forming a pressure chamber (25). A pressure hole (26) is formed on the surface of the gate (9) connecting the inlet (8) and the pressure chamber (25). The pressure hole (26) uses a Venturi tube structure, and a filter screen (23) is provided at the inlet of the pressure hole (26). Sealing grooves (30) are formed on both sides of the gate (9), and these grooves are connected to the pressure chamber (25). The interior of the sealing groove (30)... The valve seat (10) is provided with a disc spring (27), a retaining ring (28) and a sealing ring (24) arranged sequentially from the inside to the outside. The sealing ring (24) has a protruding sealing nose (29) integrally formed at the end facing the valve seat (10). When the medium enters the pressure chamber (25) through the pressurization hole (26) of the venturi tube structure, the medium pressure, together with the disc spring (27), pushes the retaining ring (28) and the sealing ring (24), so that the sealing nose (29) presses against the valve seat (10) outward.

2. The self-sealing gate valve according to claim 1, characterized in that, The valve cover (12) is installed inside the valve body (1). A sealing ring (13) is fitted on the outer wall of the valve cover (12). A gasket (19) is provided above the sealing ring (13). A four-ring (14) is provided above the gasket (19). The four-ring (14) is inserted into the groove of the inner wall of the valve body (1). The valve cover (12) is fixed inside the valve body (1) by the stacking and cooperation of the sealing ring (13), the gasket (19) and the four-ring (14), and provides a moving channel for the valve stem (11).

3. A self-sealing gate valve according to claim 2, characterized in that, A sealing cover (2) is fixed to the upper port of the valve body (1). The sealing cover (2) encapsulates the valve cover (12), the four-ring (14) and related sealing components inside the valve body (1). A packing pressure plate (4) is fixed above the sealing cover (2).

4. A self-sealing gate valve according to claim 3, characterized in that, The valve cover (12) has an opening (20) for the valve stem (11) to pass through. The opening (20) is filled with a plurality of packing blocks (21). A packing sleeve (15) is provided above the packing blocks (21). The packing sleeve (15) is pressed and fixed by the packing plate (4) to lock the packing blocks (21) and seal the valve stem (11).

5. A self-sealing gate valve according to claim 3, characterized in that, A bracket (3) is fixedly connected above the packing pressure plate (4) by screws, and a conical cover (5) is fixedly connected to the top of the bracket (3). The driving mechanism is located inside the conical cover (5).

6. A self-sealing gate valve according to claim 5, characterized in that, The drive mechanism includes a handwheel (6), a first bevel gear (16), a second bevel gear (18), and an adjusting nut (17). The first bevel gear (16) and the second bevel gear (18) are both located inside the conical cover (5). The handwheel (6) is fixedly connected to the second bevel gear (18) and is used to drive the second bevel gear (18) to rotate. The second bevel gear (18) meshes with the first bevel gear (16). The first bevel gear (16) is fixedly connected to the adjusting nut (17). The adjusting nut (17) is threadedly connected to the valve stem (11). By rotating the handwheel (6), the second bevel gear (18) is driven to rotate, thereby driving the first bevel gear (16) and the adjusting nut (17) to rotate, thereby driving the valve stem (11) to move up and down inside the valve body (1) and adjusting the position of the gate (9) to control the opening and closing of the valve.

7. A self-sealing gate valve according to claim 1, characterized in that, The sealing nose (29) is arc-shaped, and the sealing ring (24) and the sealing groove (30) are in clearance fit. The sealing ring (24) slides back and forth in the sealing groove (30) in a direction perpendicular to the valve flow channel.

8. A self-sealing gate valve according to claim 1, characterized in that, The retaining ring (28) is located in the sealing groove (30) and is used to receive the elastic force of the disc spring (27) and transmit it evenly to the inner end face of the sealing ring (24).

9. A self-sealing gate valve according to claim 1, characterized in that, The venturi structure of the pressurizing orifice (26) includes a constriction section, a throat, and a diffuser section, which are used to accelerate the fluid into the pressure chamber (25) and maintain pressure stability.

10. A self-sealing gate valve according to claim 2, characterized in that, The valve body (1), the gate (9), and the valve cover (12) are all made of metal, and the sealing ring (13) is a flexible graphite composite gasket.

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