Leak-proof wellhead gate valve based on oil exploitation and use method thereof

Abstract

The present application relates to the technical field of oil exploitation, in particular to a leak-proof wellhead gate valve based on oil exploitation and a use method thereof, comprising a lower valve body, an oil inlet pipe is communicated with one side wall of the lower valve body, an oil outlet pipe is communicated with the other side wall of the lower valve body, an upper valve body is fixedly connected to the upper end surface of the lower valve body, and the upper valve body is communicated with the lower valve body, a cavity is formed in the upper valve body, and side covers are connected to the two side walls of the upper valve body through bolts. The cavity is divided into two parts by combining two sealing horizontal plates, then the leaked oil will extrude the two extrusion vertical plates, thereby driving the two first connecting rods to move, respectively driving the two second connecting rods to move in the vertical direction, then driving the third connecting rod to move towards the cavity, thereby driving the sealing blocks to move towards the cavity, and finally the two sealing blocks are in contact, so as to close the whole cavity.

Description

Technical Field

[0001] This invention relates to a leak-proof wellhead gate valve, and more particularly to a leak-proof wellhead gate valve based on oil extraction and its usage method, belonging to the field of oil extraction technology. Background Technology

[0002] Gate valves are fluid control devices typically used to cut off and control fluid flow. They are characterized by low fluid resistance, low opening and closing torque, and good sealing performance, making them widely used in various fluid pipelines. Oil wellheads are crucial equipment in the oil extraction process, and gate valves play a vital role in this equipment. By closing the gate valve, the flow of oil in the pipeline is cut off. Since oil is a vital resource, leak prevention is key to the gate valve's function, directly impacting resource waste and safety in production.

[0003] Gate valves are mainly composed of parts such as valve body, valve cover, bracket, valve stem, valve stem nut, gate, valve seat, stuffing box, sealing packing, upper sealing seat, packing gland, and transmission device. During use, the gate is moved up and down by rotating the valve stem to control the flow of the medium through the valve body. However, in oil extraction, because oil is extracted from underground, it contains many impurities. When the gate moves, these impurities may seep into the valve seat, or the valve stem may bend and deform under external forces. Over time, these impurities can lead to various problems. When the gate moves up and down continuously, the valve stem and gate will be damaged, compromising the valve's seal. This will cause oil in the pipeline to seep out from the connection between the valve stem and the valve body, resulting in leakage. If this is not prevented in advance, it will lead to serious waste of resources. Furthermore, during oil extraction, the pressure inside the inlet pipeline is higher than the external pressure. Because the flange at the connection point is frequently opened during valve body maintenance or damaged by external corrosion, if the flange at the connection point cannot guarantee its airtightness, the leakage will become larger and larger when the gate valve leaks, eventually leading to serious consequences.

[0004] Therefore, it is urgent to improve the leak-proof wellhead gate valves based on oil extraction in order to solve the above-mentioned problems. Summary of the Invention

[0005] The purpose of this invention is to provide a leak-proof wellhead gate valve for oil extraction and its usage method. By merging two sealing horizontal plates, the cavity is divided in two. Leaking oil then squeezes the two compression vertical plates, pushing the two No. 1 connecting rods to move. This causes the two No. 2 connecting rods to shift vertically, then the No. 3 connecting rod to move towards the cavity, which in turn moves the sealing blocks towards the cavity. Finally, the two sealing blocks come into contact, sealing the entire cavity and preventing oil seepage. The more oil leaks and the higher the pressure within the cavity, the better the sealing effect of the two sealing blocks. The seal between the two sealing blocks effectively prevents oil from seeping out along the valve stem and the connection between the upper valve body and the valve body guard rod. Even if the upper valve body connection or valve stem is damaged, the lower valve body can still be sealed to achieve leak prevention and ensure its airtightness.

[0006] To achieve the above objectives, the main technical solution adopted by the present invention includes: a leak-proof wellhead gate valve for oil extraction, comprising a lower valve body, an oil inlet pipe connected to one side wall of the lower valve body, an oil outlet pipe connected to the other side wall of the lower valve body, an upper valve body fixedly connected to the upper end face of the lower valve body, and the upper valve body communicating with the lower valve body, a cavity formed inside the upper valve body, side covers bolted to the two side walls of the upper valve body, each of the two side covers threadedly connected to a push screw, one end of the push screw penetrating the side wall of the upper valve body and movably connected to the side wall of the upper valve body, the other end of the push screw extending to the side of the side cover away from the upper valve body, sealing horizontal plates slidably connected to the two side walls of the upper valve body, and the two sealing horizontal plates rotatably connected to one end of each of the two push screws;

[0007] Sealing blocks and extrusion vertical plates are slidably connected to both side walls of the upper valve body. The two extrusion vertical plates are located below the two sealing blocks respectively. Two No. 1 connecting rods are fixedly connected to the side wall of the extrusion vertical plate away from the cavity, and the two No. 1 connecting rods are symmetrically arranged. A No. 2 connecting rod is rotatably connected to the end of the No. 1 connecting rod away from the extrusion vertical plate. A No. 3 connecting rod is fixedly connected to the side wall of the sealing block away from the cavity. The end of the No. 2 connecting rod away from the No. 1 connecting rod and the end of the No. 3 connecting rod away from the sealing block are rotatably connected, and the connection points of the No. 2 connecting rod and the No. 3 connecting rod are simultaneously slidably connected. Support frames are fixedly connected to both outer walls of the upper valve body. The support frames are located between the No. 3 connecting rod and the No. 1 connecting rod, and the end of the support frame away from the upper valve body is rotatably connected to the No. 2 connecting rod.

[0008] Preferably, each of the two compression plates has two compression springs fixedly connected to the side wall away from the cavity, and the two compression springs are symmetrically arranged. Several No. 1 sealing rings are snapped onto the compression plates.

[0009] Preferably, two limiting frames are fixedly connected to the two side walls of the cavity. The two limiting frames are respectively located on the side of the two extrusion vertical plates close to the cavity, and the limiting frames are in contact with the extrusion vertical plates.

[0010] Preferably, two No. 2 sealing rings are snapped into the upper valve body, and the two No. 2 sealing rings are in contact with two sealing blocks respectively. Each of the two sealing blocks has a sealing layer on the side closest to the cavity. Two limiting strips are fixedly connected to the outer walls on both sides of the cavity, and the two limiting strips are in contact with the side wall of the sealing block away from the cavity.

[0011] Preferably, a valve body cover is bolted to the upper valve body, a rotating block is rotatably connected to the valve body cover, and a valve stem is threaded onto the rotating block.

[0012] Preferably, a protective rod cover is fixedly connected to the upper end face of the rotating block, one end of the valve stem passes through the rotating block and extends into the inside of the protective rod cover, a handle is fixedly connected to the rotating block, and a gate is fixedly connected to the end of the valve stem away from the rotating block.

[0013] Preferably, both the oil inlet pipe and the oil outlet pipe are fitted with No. 3 sealing rings at the ends near the lower valve body, and both No. 3 sealing rings are in contact with the gate plate. Several sealing rings are fitted at the connection between the valve stem and the upper valve body and the valve body cover.

[0014] Preferably, a conical cylinder is fixedly connected to the inner wall of the oil inlet pipe, a cross-shaped fixing bracket is fixedly connected to the inner wall of the end of the conical cylinder near the lower valve body, and a snap-fit ​​circular block is fixedly connected to the side wall of the cross-shaped fixing bracket away from the lower valve body, and the central axis of the snap-fit ​​circular block is collinear with the central axis of the conical cylinder.

[0015] Preferably, a plurality of circular tubes are fixedly connected to the side wall of the cross-shaped fixing bracket away from the lower valve body. The plurality of circular tubes are equidistantly arranged around the central axis of the conical cylinder. An anti-collision spring is fixedly connected to the bottom wall of the cylinder. A circular rod is slidably connected to the circular tube. The end of the anti-collision spring away from the circular tube is fixedly connected to the end of the circular rod close to the circular tube. A hollow circular block is fixedly connected to the ends of the plurality of circular rods away from the circular tube.

[0016] The method for using leak-proof wellhead gate valves in oil extraction includes the following steps:

[0017] S1: First, fix the two side covers to the two sides of the upper valve body with bolts. While the side covers are fixed to the upper valve body, push the screw near the upper valve body to insert into the side wall of the cavity and abut against the side wall of the sealing plate away from the cavity. When the anti-leakage device is required, rotate the valve stem to seal the gate between the oil inlet pipe and the oil outlet pipe to block the flow of oil in the pipeline. Then, push the screws on both sides. While pushing the screws forward, push the two sealing plates to slide into the cavity until the two sealing plates contact each other, thereby dividing the cavity into upper and lower parts.

[0018] S2: Then, when leakage occurs inside the valve body at the gate and valve stem positions, the oil will first flow into the space below the two sealing horizontal plates. When the oil accumulates to a certain amount, the internal pressure begins to rise. At this time, the two squeezing vertical plates move away from the cavity under the pressure of the increasing oil. While moving, they will push the two No. 1 connecting rods to move.

[0019] S3: Finally, as the two No. 1 connecting rods move, they will also drive the two No. 2 connecting rods to move. Under the action of the support frame, the No. 2 connecting rods will shift vertically. When the No. 2 connecting rods shift at an angle, they will drive the No. 3 connecting rods to move towards the cavity. At the same time as the No. 3 connecting rods move, they will drive the sealing blocks to move towards the cavity. Finally, the two sealing blocks will come into contact with each other, thereby sealing the entire cavity and preventing oil from seeping out.

[0020] This invention has at least the following beneficial effects:

[0021] 1. By merging the two sealing horizontal plates, the cavity is divided into two. The leaking oil then squeezes the two extrusion vertical plates, which in turn pushes the two No. 1 connecting rods to move, causing the two No. 2 connecting rods to shift vertically. This, in turn, causes the No. 3 connecting rod to move towards the cavity, which in turn moves the sealing blocks towards the cavity. Finally, the two sealing blocks come into contact, thus sealing the entire cavity and preventing oil leakage. The more oil leaks and the higher the pressure inside the cavity, the better the sealing effect of the two sealing blocks. The seal between the two sealing blocks effectively prevents oil from seeping out along the valve stem and the connection between the upper valve body and the valve body guard rod. Even if the upper valve body connection or the valve stem is damaged, the lower valve body can still be sealed to achieve the purpose of preventing leakage and ensuring its sealing performance.

[0022] 2. By matching the snap-fit ​​round blocks and hollow round blocks, the flow rate of oil in the oil inlet pipe can be buffered according to the oil flow rate, thereby protecting the gate from the impact of high-velocity oil and further preventing oil leakage caused by damage to the gate. Attached Figure Description

[0023] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0024] Figure 1 This is a three-dimensional structural schematic diagram provided by the present invention;

[0025] Figure 2 A cross-sectional view provided for this invention;

[0026] Figure 3 Provided by the present invention Figure 2 Enlarged structural diagram at point A in the middle;

[0027] Figure 4 Provided by the present invention Figure 2 Enlarged structural diagram at point B;

[0028] Figure 5 Provided by the present invention Figure 2 Enlarged structural diagram at point C;

[0029] Figure 6 Provided by the present invention Figure 2 Enlarged structural diagram at point D;

[0030] Figure 7 This is a partial structural schematic diagram provided for the present invention.

[0031] In the diagram: 1. Lower valve body; 2. Oil inlet pipe; 3. Oil outlet pipe; 4. Upper valve body; 5. Side cover; 6. Push screw; 7. Sealing horizontal plate; 8. Cavity; 9. Sealing block; 10. Extrusion vertical plate; 11. Connecting rod No. 1; 12. Connecting rod No. 2; 13. Connecting rod No. 3; 14. Support frame; 15. Extrusion spring; 16. Sealing ring No. 1; 17. Limiting square frame; 18. Sealing ring No. 2; 19. Sealing layer; 20. Limiting strip; 21. Valve body cover; 22. Rotating round block; 23. Valve stem; 24. Protective rod cover; 25. Handle; 26. Gate plate; 27. Sealing ring No. 3; 28. Sealing ring; 29. ​​Conical cylinder; 30. Cross fixing frame; 31. Snap-fit ​​round block; 32. Round tube; 33. Anti-collision spring; 34. Round rod; 35. Hollow round block. Detailed Implementation

[0032] The following will describe in detail the implementation of this application with reference to the accompanying drawings and embodiments, so that the implementation process of how this application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0033] like Figures 1-7 As shown, the leak-proof wellhead gate valve for oil extraction provided in this embodiment includes a lower valve body 1. An oil inlet pipe 2 is connected to one side wall of the lower valve body 1, and an oil outlet pipe 3 is connected to the other side wall of the lower valve body 1. An upper valve body 4 is fixedly connected to the upper end face of the lower valve body 1, and the upper valve body 4 is connected to the lower valve body 1. A cavity 8 is formed inside the upper valve body 4. Side covers 5 are bolted to the two side walls of the upper valve body 4. Both side covers 5 are threaded with push screws 6. One end of the push screw 6 passes through the side wall of the upper valve body 4 and is movably connected to the side wall of the upper valve body 4. The other end of the push screw 6 extends to the side of the side cover 5 away from the upper valve body 4. Sealing plates 7 are slidably connected to the two side walls of the upper valve body 4. The two sealing plates 7 are rotatably connected to one end of the two push screws 6 respectively.

[0034] Both sides of the upper valve body 4 are slidably connected to sealing blocks 9 and compression vertical plates 10. Two compression springs 15 are fixedly connected to the side wall of each compression vertical plate 10 away from the cavity 8, and the two compression springs 15 are symmetrically arranged. Several No. 1 sealing rings 16 are snapped onto the compression vertical plates 10. The two compression vertical plates 10 are located below the two sealing blocks 9 respectively. Two No. 1 connecting rods 11 are fixedly connected to the side wall of the compression vertical plate 10 away from the cavity 8, and the two No. 1 connecting rods 11 are symmetrically arranged. The end of the No. 1 connecting rod 11 away from the compression vertical plate 10 rotates... The valve body 4 is connected by a second connecting rod 12. A third connecting rod 13 is fixedly connected to the side wall of the sealing block 9 away from the cavity 8. The end of the second connecting rod 12 away from the first connecting rod 11 is rotatably connected to the end of the third connecting rod 13 away from the sealing block 9. The connection between the second connecting rod 12 and the third connecting rod 13 is simultaneously slidably connected. Support frames 14 are fixedly connected to the outer walls of both sides of the upper valve body 4. The support frames 14 are located between the third connecting rod 13 and the first connecting rod 11. The end of the support frame 14 away from the upper valve body 4 is rotatably connected to the second connecting rod 12.

[0035] Among them, such as Figures 2-7As shown, two limiting frames 17 are fixedly connected to the side walls of both sides of the cavity 8. The two limiting frames 17 are located on the side of the two extrusion vertical plates 10 near the cavity 8, and the limiting frames 17 are in contact with the extrusion vertical plates 10. Two No. 2 sealing rings 18 are snapped into the upper valve body 4. The two No. 2 sealing rings 18 are in contact with two sealing blocks 9. The side of the two sealing blocks 9 near the cavity 8 is provided with a sealing layer 19. Two limiting strips 20 are fixedly connected to the outer walls of both sides of the cavity 8. The two limiting strips 20 are in contact with the side wall of the sealing block 9 away from the cavity 8. Two side covers 5 are fixedly connected to the upper valve body 4 on both sides by bolts. While the side covers 5 are fixed to the upper valve body 4, the end of the push screw 6 near the upper valve body 4 is inserted into the side wall of the cavity 8 and abuts against the side wall of the sealing horizontal plate 7 away from the cavity 8. When the anti-leakage device is required, the valve stem 23 is rotated to make the gate 26 seal the oil inlet pipe 2. At the location between the oil outlet pipe 3 and the oil outlet pipe 3, the flow of oil in the pipeline is blocked. Then, the push screws 6 on both sides push the two sealing horizontal plates 7 to slide into the cavity 8 while pushing the screws 6 forward, until the two sealing horizontal plates 7 contact each other, thereby dividing the cavity 8 into two parts, upper and lower.

[0036] Furthermore, such as Figures 1-7 As shown, a valve body cover 21 is bolted to the upper valve body 4. A rotating block 22 is rotatably connected to the valve body cover 21. A valve stem 23 is threaded onto the rotating block 22. A rod guard 24 is fixedly connected to the upper end face of the rotating block 22. One end of the valve stem 23 passes through the rotating block 22 and extends into the inside of the rod guard 24. A handle 25 is fixedly connected to the rotating block 22. A gate plate 26 is fixedly connected to the end of the valve stem 23 away from the rotating block 22. A No. 3 sealing ring 27 is snapped into the end of the oil inlet pipe 2 and the oil outlet pipe 3 near the lower valve body 1. Both No. 3 sealing rings 27 are in contact with the gate plate 26. Several sealing rings 28 are snapped into the connection between the valve stem 23 and the upper valve body 4 and the valve body cover 21 to maintain the sealing of the valve stem 23 during operation.

[0037] Furthermore, such as Figure 2 as well as Figure 6As shown, a conical cylinder 29 is fixedly connected to the inner wall of the oil inlet pipe 2. A cross-shaped fixing bracket 30 is fixedly connected to the inner wall of the end of the conical cylinder 29 closest to the lower valve body 1. A snap-fit ​​circular block 31 is fixedly connected to the side wall of the cross-shaped fixing bracket 30 away from the lower valve body 1, and the central axis of the snap-fit ​​circular block 31 is collinear with the central axis of the conical cylinder 29. Several circular tubes 32 are fixedly connected to the side wall of the cross-shaped fixing bracket 30 away from the lower valve body 1. The several circular tubes 32 are equidistantly arranged around the central axis of the conical cylinder 29. An anti-collision spring 33 is fixedly connected to the bottom wall of the cylinder. A circular rod 34 is slidably connected to the circular tube 32. The end of the anti-collision spring 33 away from the circular tube 32 is fixedly connected to the end of the circular rod 34 closest to the circular tube 32. A hollow circular block 35 is fixedly connected to the ends of the several circular rods 34 away from the circular tube 32. Oil with a higher flow rate is directed to the hollow circular block 35. When the circular block 35 impacts, the higher the flow rate of the oil, the stronger the impact force on the hollow circular block 35. Under the action of several anti-collision springs 33, the hollow circular block 35 and the locking block 31 will gradually approach each other. The flow rate of the oil passing through the hollow circular block 35 will continuously change according to the distance between the hollow circular block 35 and the locking block 31. The higher the flow rate of the oil, the lower the flow rate of the oil before it reaches the gate 26 after passing through the hollow circular block 35. The locking block 31 and the hollow circular block 35 are paired with each other and can buffer the oil according to the flow rate of the oil in the oil inlet pipe 2, thereby protecting the gate 26 from the impact of high-velocity oil and further preventing oil leakage caused by damage to the gate 26.

[0038] like Figures 1-7 As shown in this embodiment, the method for using a leak-proof wellhead gate valve based on oil extraction includes the following steps:

[0039] S1: First, the two side covers 5 are fixed to the upper valve body 4 on both sides by bolts. While the side covers 5 are fixed to the upper valve body 4, the end of the push screw 6 close to the upper valve body 4 is inserted into the side wall of the cavity 8 and abuts against the side wall of the sealing plate 7 away from the cavity 8. When the anti-leakage device is required, the valve stem 23 is rotated to make the gate 26 seal between the oil inlet pipe 2 and the oil outlet pipe 3 to block the flow of oil in the pipeline. Then, the push screws 6 on both sides are pushed forward. While the push screws 6 are pushed forward, the two sealing plates 7 are pushed to slide into the cavity 8 until the two sealing plates 7 contact each other, thereby dividing the cavity 8 into two parts, upper and lower.

[0040] S2: Then, when leakage occurs inside the valve body at the positions of the gate 26 and the valve stem 23, the oil will first flow into the space below the two sealing horizontal plates 7. When the oil accumulates to a certain amount, the internal pressure begins to rise. At this time, the two squeezing vertical plates 10 move away from the cavity 8 under the squeezing of the increasing oil. While moving, they will push the two No. 1 connecting rods 11 to move.

[0041] S3: Finally, as the two No. 1 connecting rods 11 move, they will also drive the two No. 2 connecting rods 12 to move. Under the action of the support frame 14, the No. 2 connecting rods 12 will shift vertically. When the No. 2 connecting rods 12 shift, they will drive the No. 3 connecting rod 13 to move towards the cavity 8. At the same time as the No. 3 connecting rod 13 moves, it will drive the sealing block 9 to move towards the cavity 8. Finally, the two sealing blocks 9 will come into contact with each other, thereby sealing the entire cavity 8 and preventing oil from seeping out.

[0042] If certain terms are used in the specification and claims to refer to specific components, those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The term "comprising" as used throughout the specification and claims is an open-ended term and should be interpreted as "comprising but not limited to." "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error.

[0043] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes that element.

[0044] The foregoing description illustrates and describes several preferred embodiments of the present invention. However, as previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A leak-proof wellhead gate valve for oil extraction, comprising a lower valve body (1), characterized in that: The lower valve body (1) has an oil inlet pipe (2) connected to one side wall and an oil outlet pipe (3) connected to the other side wall. The upper valve body (4) is fixedly connected to the upper end face of the lower valve body (1) and the upper valve body (4) is connected to the lower valve body (1). A cavity (8) is formed inside the upper valve body (4). Side covers (5) are bolted to the two side walls of the upper valve body (4). Both side covers (5) are threaded with push screws (6). One end of the push screw (6) passes through the side wall of the upper valve body (4) and is movably connected to the side wall of the upper valve body (4). The other end of the push screw (6) extends to the side of the side cover (5) away from the upper valve body (4). Sealing plates (7) are slidably connected to the two side walls of the upper valve body (4). The two sealing plates (7) are rotatably connected to one end of the two push screws (6). The upper valve body (4) has a sealing block (9) and a pressing vertical plate (10) slidably connected to both side walls. The two pressing vertical plates (10) are located below the two sealing blocks (9). Two No. 1 connecting rods (11) are fixedly connected to the side wall of the pressing vertical plate (10) away from the cavity (8), and the two No. 1 connecting rods (11) are symmetrically arranged. A No. 2 connecting rod (12) is rotatably connected to the end of the No. 1 connecting rod (11) away from the pressing vertical plate (10). A No. 3 connecting rod (12) is fixedly connected to the side wall of the sealing block (9) away from the cavity (8). 3) The end of the second connecting rod (12) away from the first connecting rod (11) is rotatably connected to the end of the third connecting rod (13) away from the sealing block (9), and the connection between the second connecting rod (12) and the third connecting rod (13) is simultaneously slidably connected. Support frames (14) are fixedly connected to the outer walls on both sides of the upper valve body (4). The support frame (14) is located between the third connecting rod (13) and the first connecting rod (11). The end of the support frame (14) away from the upper valve body (4) is rotatably connected to the second connecting rod (12).

2. The leak-proof wellhead gate valve based on oil extraction according to claim 1, characterized in that: Two compression springs (15) are fixedly connected to the side wall of each of the two compression vertical plates (10) away from the cavity (8), and the two compression springs (15) are symmetrically arranged. Several No. 1 sealing rings (16) are snapped on the compression vertical plates (10).

3. The leak-proof wellhead gate valve based on oil extraction according to claim 2, characterized in that: Two limiting frames (17) are fixedly connected to the two side walls of the cavity (8). The two limiting frames (17) are located on the side of the two extrusion vertical plates (10) close to the cavity (8), and the limiting frames (17) are in contact with the extrusion vertical plates (10).

4. The leak-proof wellhead gate valve based on oil extraction according to claim 3, characterized in that: The upper valve body (4) is fitted with two No. 2 sealing rings (18), and the two No. 2 sealing rings (18) are in contact with two sealing blocks (9) respectively. The two sealing blocks (9) are provided with sealing layers (19) on the side of the cavity (8) near the cavity. The outer walls of both sides of the cavity (8) are fixedly connected with two limiting strips (20), and the two limiting strips (20) are in contact with the side wall of the sealing block (9) away from the cavity (8).

5. The leak-proof wellhead gate valve based on oil extraction according to claim 4, characterized in that: The upper valve body (4) is bolted to a valve body cover (21), and a rotating block (22) is rotatably connected to the valve body cover (21). A valve stem (23) is threaded onto the rotating block (22).

6. The leak-proof wellhead gate valve based on oil extraction according to claim 5, characterized in that: A rod cover (24) is fixedly connected to the upper end face of the rotating block (22). One end of the valve stem (23) passes through the rotating block (22) and extends into the inside of the rod cover (24). A handle (25) is fixedly connected to the rotating block (22). A gate plate (26) is fixedly connected to the end of the valve stem (23) away from the rotating block (22).

7. The leak-proof wellhead gate valve based on oil extraction according to claim 6, characterized in that: The oil inlet pipe (2) and the oil outlet pipe (3) are both fitted with No. 3 sealing rings (27) at the end near the lower valve body (1), and both No. 3 sealing rings (27) are in contact with the gate plate (26). Several sealing rings (28) are fitted at the connection between the valve stem (23) and the upper valve body (4) and the valve body cover (21).

8. The leak-proof wellhead gate valve based on oil extraction according to claim 7, characterized in that: A conical cylinder (29) is fixedly connected to the inner wall of the oil inlet pipe (2). A cross-shaped fixing bracket (30) is fixedly connected to the inner wall of the end of the conical cylinder (29) close to the lower valve body (1). A snap-fit ​​round block (31) is fixedly connected to the side wall of the cross-shaped fixing bracket (30) away from the lower valve body (1), and the central axis of the snap-fit ​​round block (31) is collinear with the central axis of the conical cylinder (29).

9. The leak-proof wellhead gate valve based on oil extraction according to claim 8, characterized in that: The cross-shaped fixing bracket (30) has several round tubes (32) fixedly connected to the side wall away from the lower valve body (1). The several round tubes (32) are equidistantly arranged around the central axis of the conical cylinder (29). The inner bottom wall of the round tube (32) is fixedly connected to an anti-collision spring (33). A round rod (34) is slidably connected to the round tube (32). The end of the anti-collision spring (33) away from the round tube (32) is fixedly connected to the end of the round rod (34) close to the round tube (32). The ends of the several round rods (34) away from the round tube (32) are all fixedly connected to a hollow round block (35).

10. A method of using the leak-proof wellhead gate valve for oil extraction as described in claim 9, characterized in that: Includes the following steps: S1: First, fix the two side covers (5) to the upper valve body (4) on both sides with bolts. While the side covers (5) are fixed to the upper valve body (4), push the screw (6) to insert one end close to the upper valve body (4) into the side wall of the cavity (8) and abut against the side wall of the sealing plate (7) away from the cavity (8). When the leak prevention device is needed, rotate the valve stem (23) to seal the gate (26) between the oil inlet pipe (2) and the oil outlet pipe (3) to block the flow of oil in the pipeline. Then push the screw (6) on both sides. While pushing the screw (6) forward, push the two sealing plates (7) to slide into the cavity (8) until the two sealing plates (7) contact each other, and then divide the cavity (8) into two parts, upper and lower. S2: Then, when leakage occurs inside the valve body at the positions of the gate (26) and the valve stem (23), the oil will first flow into the space below the two sealing horizontal plates (7). When the oil accumulates to a certain amount, the internal pressure begins to rise. At this time, the two squeezing vertical plates (10) are squeezed by the increasing amount of oil and move away from the cavity (8). While moving, they will push the two No. 1 connecting rods (11) to move. S3: Finally, as the two No. 1 connecting rods (11) move, they will drive the two No. 2 connecting rods (12) to move. Under the action of the support frame (14), the No. 2 connecting rods (12) will move vertically. When the No. 2 connecting rods (12) move at an angle, they will drive the No. 3 connecting rods (13) to move towards the cavity (8). While the No. 3 connecting rods (13) are moving, they will drive the sealing block (9) to move towards the cavity (8). Finally, the two sealing blocks (9) will come into contact with each other to seal the entire cavity (8) and prevent oil from seeping out.

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