Gate valve with valve rod sealing ring capable of being replaced under pressure

Abstract

The invention relates to a gate valve with a valve rod sealing ring capable of being replaced under pressure. The gate valve comprises a valve body, a valve deck, a valve plate, a first valve rod and a second valve rod, and a sealing assembly is arranged between the second valve rod and the valve deck. The sealing assembly comprises a fixed sealing ring, a second installation part, a movable part and a pressing ring, the second valve rod is sleeved with the movable part, the second valve rod moving downwards can be in threaded fit with the movable part, the first valve rod and the second valve rod are separated from clamping, and the movable part connected to the second valve rod in a threaded mode moves upwards and enables the pressing ring to abut against the fixed sealing ring. When the upper sealing ring needs to be replaced, the second valve rod is moved so that the second valve rod can be disengaged from the first valve rod, then the second valve rod is in threaded connection with the movable part so that the movable part can be driven to move towards the fixed sealing ring in the rotating process of the second valve rod, and the pressing ring can be kept abutting against the fixed sealing ring; and the second valve rod is in threaded fit with the movable part, so that a gap between the second valve rod and the valve cover is sealed.

Description

Technical Field

[0001] The present application relates to the technical field of gate valves, and particularly relates to a gate valve capable of replacing a valve stem seal ring under pressure. Background Art

[0002] Existing externally leak-proof self-sealing valves include a valve body, a valve cover, a gland valve plate, a valve stem and an opening device. During operation, the opening and closing of the valve are controlled by the lifting of the gate plate, thereby achieving the connection or cut-off of the medium in the pipeline. At the same time, an upper seal ring is provided between the valve stem and the gland of the gate valve to prevent the leakage of the medium in the pipeline. The seal ring is a vulnerable part and needs to be replaced frequently, otherwise the phenomenon of medium leakage will occur.

[0003] The above-mentioned sealing form cannot replace the seal ring under working conditions, that is, it cannot be replaced when the pipeline is running without stopping the water supply and under pressure. Only after cutting off the pipeline pressure and disassembling the gland can the seal ring be replaced. The disassembly and replacement are very inconvenient, and the replacement requires the pipeline to stop running, which has an impact on subsequent use and is inconvenient to use.

[0004] Therefore, a new technical solution is needed to solve the above problems. Summary of the Invention

[0005] In order to replace the seal ring without stopping the pipeline operation, the present application provides a gate valve capable of replacing a valve stem seal ring under pressure.

[0006] A gate valve capable of replacing a valve stem seal ring under pressure provided by the present application adopts the following technical solutions: A gate valve capable of replacing a valve stem seal ring under pressure includes a valve body with one end open, a valve cover for closing the opening of the valve body, a valve plate slidably disposed in the valve body, a first valve stem for driving the valve plate to move, and a second valve stem for driving the first valve stem to rotate. A sealing assembly is provided between the second valve stem and the valve cover. The first valve stem is rotatably connected to the valve body, the first valve stem passes through the valve plate and is in threaded cooperation with the valve plate. The second valve stem passes through the valve cover and is in sliding cooperation with the valve cover. The lower end of the second valve stem can be clamped with the upper end of the first valve stem. A cover plate is detachably connected to the valve cover, and an upper seal ring is provided between the cover plate and the second valve stem. The valve body has a water inlet and a water outlet for passing through the fluid. The sealing assembly includes a fixed seal ring fixed on the inner wall of the valve cover, a second mounting member connected to the valve body, a movable member slidably disposed on the second mounting member, and a pressing ring provided on the movable member. The movable member is sleeved outside the second valve stem. The downward moving second valve stem can be in threaded cooperation with the movable member and disengage the first valve stem from the clamping connection. The movable member threaded on the second valve stem moves upward and makes the pressing ring abut against the fixed seal ring. There are gaps between the inner walls of the fixed seal ring and the pressing ring and the second valve stem.

[0007] By adopting the above technical solution: when it is necessary to replace the upper sealing ring, the second valve stem is moved so that the second valve stem is disengaged from the first valve stem. After that, the second valve stem is threadedly connected to the movable member, and during the rotation of the second valve stem, the movable member is driven to move towards the fixed sealing ring, so that the pressing ring is kept in contact with the fixed sealing ring. Moreover, the second valve stem is in threaded cooperation with the movable member, so that the gap between the second valve stem and the valve cover is sealed, and it is not easy for the liquid to leak from the gap between the second valve stem and the valve cover, and thus the upper sealing ring on the second valve stem can be directly replaced.

[0008] Optionally: an installation groove is formed in the first valve stem, a snap ring is further fixed to the upper end of the first valve stem, a snap connection block is arranged at the lower end of the second valve stem, the snap connection block can be snap-connected into the inner cavity of the snap ring, the snap connection block can rotate in the installation groove, and a gap is left between the side wall of the snap connection block and the inner wall of the installation groove.

[0009] By adopting the above technical solution, after the second valve stem moves downward, the snap connection block on the second valve stem is disengaged from the snap ring. Thus, during the rotation of the second valve stem, the first valve stem will not be driven to move, the position of the valve plate will not change, and the normal use of the gate valve will not be easily affected.

[0010] Optionally: a chamfer is arranged at the upper end of the snap connection block.

[0011] By adopting the above technical solution, after the snap connection block rotates in the installation groove, when the second valve stem moves upward, the chamfer can first contact the inner wall of the snap ring, and the rotation of the snap connection block can be guided by the inclined surface of the chamfer, so that the snap connection block can be aligned with the inner wall of the snap ring, and thus the snap connection block can more easily enter the snap ring.

[0012] Optionally: the snap connection block is rotatably connected to the lower end of the second valve stem, a sliding groove is formed at one end of the snap connection block close to the valve stem, the sliding groove is arranged around the rotation axis of the snap connection block, a sliding block is fixed to the lower end of the second valve stem, and the sliding block is embedded in the sliding groove and can drive the second snap connection block to rotate synchronously with the second valve stem.

[0013] By adopting the above technical solution, during the upward movement of the second valve stem, the snap connection block can automatically rotate under the push of the chamfer, so that the snap connection block can more easily enter the snap ring. At the same time, when the second valve stem rotates, it can also drive the snap connection block to rotate, and it will not affect the rotation of the second valve stem driving the first valve stem.

[0014] Optionally: a first guiding inclined surface is arranged at one end of the outer wall of the fixed sealing ring close to the pressing ring, a second guiding inclined surface is arranged at one end of the inner wall of the pressing ring close to the fixed sealing ring, and the first guiding inclined surface and the second guiding inclined surface are in contact with each other.

[0015] By adopting the above technical solution, when the fixed sealing ring and the pressing ring are in mutual contact, the first guiding inclined surface and the second guiding inclined surface can guide each other, making it easier for the first guiding inclined surface to align with the second guiding inclined surface. At the same time, deformation can occur during their extrusion, resulting in a better sealing effect between the two.

[0016] Optionally: The inner wall diameter of the movable part is larger than the outer diameter of the second valve stem.

[0017] By adopting the above technical solution, when the movable part does not need to move while the second valve stem needs to rotate, the movable part will not contact the second valve stem, so that the rotation of the second valve stem is not easily affected. At the same time, the internal thread of the movable part will not be worn due to contact with the second valve stem when it is not in use.

[0018] Optionally: A limit ring is provided between the valve cover and the cover plate. A limit groove is coaxially provided on the second valve stem, and the inner wall of the limit ring is sleeved in the limit groove and is in sliding fit with the limit groove.

[0019] By adopting the above technical solution, when the second valve stem moves in the axial direction of its axis, the distance of the axial movement of the second valve stem is limited by the limit ring, so that the second valve stem will not move too much. After the second valve stem moves upward, the clamping block can be stably located in the clamping ring and will not directly fall off.

[0020] Optionally: Two limit pins are also inserted through the cover plate. A foolproof groove is coaxially provided on the second valve stem. The limit pins are arranged along the axis of the second valve stem, and the limit pins can respectively penetrate into the foolproof groove. When the upper limit pin is inserted into the foolproof groove, the clamping block is disengaged from the clamping ring, and the length of the foolproof groove is greater than the diameter of the limit pin.

[0021] By adopting the above technical solution, the cooperation between the limit pin and the foolproof groove is used to judge the position of the second valve stem relative to the first valve stem, so that the situation where the second valve stem is rotated when the clamping block has not completely entered the installation groove is not likely to occur.

[0022] In summary, the present application includes at least one of the following beneficial technical effects: 1. When it is necessary to replace the upper sealing ring, the second valve stem is moved so that the second valve stem is disengaged from the clamping connection with the first valve stem. Then, the second valve stem is threadedly connected with the movable part, and during the rotation of the second valve stem, the movable part is driven to move towards the fixed sealing ring, so that the pressing ring remains in contact with the fixed sealing ring. Moreover, since the second valve stem is in threaded cooperation with the movable part, the gap between the second valve stem and the valve cover is closed, and liquid is not easily leaked from the gap between the second valve stem and the valve cover. Thus, the upper sealing ring on the second valve stem can be directly replaced; 2. After the second valve stem moves downward, the clamping block under the second valve stem is disengaged from the clamping ring. Therefore, during the rotation of the second valve stem, the first valve stem will not be driven to move, so that the position of the valve plate will not change, and the normal use of the gate valve will not be easily affected. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic structural diagram of an embodiment of the present application; Figure 2 is a schematic diagram for showing the internal structure of the valve body in an embodiment of the present application; Figure 3 is Figure 2 an enlarged view of part A of Figure 4 is Figure 2 an enlarged view of part B of Figure 5 is a schematic diagram for showing the connection structure between the first valve stem and the second valve stem in an embodiment of the present application; Figure 6 is a schematic diagram for showing the connection structure between the movable part and the second valve stem in an embodiment of the present application; Figure 7 is a schematic diagram for showing the structure for defining the stop position of the second valve stem in an embodiment of the present application.

[0024] In the figure, 1. Valve body; 11. Valve plate; 12. Positioning groove; 13. First mounting member; 131. Mounting ring; 2. Valve cover; 21. First sealing washer; 22. Second sealing washer; 3. First valve stem; 31. Convex ring; 32. Mounting groove; 33. Clamping ring; 4. Second valve stem; 41. Handwheel; 42. Upper sealing ring; 43. Clamping block; 431. Upper clamping portion; 432. Lower clamping portion; 433. Sliding groove; 434. Chamfer; 44. Slide block; 45. Limiting groove; 46. Anti-fooling groove; 5. Cover plate; 51. Limiting ring; 52. Limiting pin; 521. Anti-disengagement groove; 53. Anti-disengagement pin; 6. Sealing assembly; 61. Fixed sealing ring; 611. First guiding inclined surface; 62. Second mounting member; 63. Movable part; 631. Guiding groove; 64. Compression ring; 641. Second guiding inclined surface; 65. Guiding sleeve; 651. Guiding block. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The following further describes the present application in detail with reference to the accompanying drawings.

[0026] A gate valve capable of replacing the valve stem sealing ring under pressure disclosed in the present application, as shown in Figure 1 and Figure 2As shown in the figure, it includes a valve body 1 with an open end, a valve cover 2 for closing the opening of the valve body 1, a valve plate 11 slidably arranged in the valve body 1, a first valve rod 3 for driving the valve plate 11 to move, and a second valve rod 4 for driving the first valve rod 3 to rotate. A handwheel 41 is fixed to the upper end of the second valve rod 4 by bolts. Water inlets and outlets are respectively penetrated through two mutually remote sides of the valve body 1, and both the water inlets and outlets communicate with the inner cavity of the valve body 1. The valve plate 11 slides vertically in the inner cavity of the valve body 1 to close the water inlets and outlets, so that the flow channel in the pipeline can be disconnected after the valve plate 11 moves downward. A positioning groove 12 is coaxially opened at the upper end of the valve body 1, and a first mounting member 13 is coaxially arranged in the positioning groove 12. The first mounting member 13 is embedded in the positioning groove 12 and the thickness of the first mounting member 13 is less than the depth of the positioning groove 12. The first valve rod 3 passes through the first mounting member 13 and rotates, and the lower end of the first valve rod 3 passes through the valve plate 11 and is in threaded cooperation with the valve plate 11. When the first valve rod 3 rotates, the first valve plate 11 can be driven to move along the axis of the first valve rod 3. A convex ring 31 is coaxially arranged on the first valve rod 3, and one end of the convex ring 31 abuts against one end of the first mounting member 13 close to the opening of the valve body 1. An installation ring 131 is also fixed to the first mounting member 13 by bolts. The installation ring 131 is fixed on the end face of the first mounting member 13 close to the opening of the valve body 1, and the installation ring 131 abuts against the end face of the convex ring 31 close to the opening of the valve body 1, so that the relative position between the first valve rod 3 and the first mounting member 13 is not likely to change.

[0027] As Figure 2 and Figure 3 shown in the figure, the valve cover 2 and the valve body 1 are fixedly connected by bolts, and a first sealing washer 21 is also arranged at the connection between the valve cover 2 and the valve body 1 to reduce liquid leakage. A cover plate 5 is also fixed to the upper end of the valve cover 2 by bolts, and a second sealing washer 22 is also arranged between the cover plate 5 and the valve cover 2 to reduce liquid leakage. The second valve rod 4 passes through the cover plate 5 and the valve cover 2, and the second valve rod 4 can rotate along its own axis and can also slide along its own axis. A plurality of upper sealing rings 42 are coaxially sleeved on the second valve rod 4, and the upper sealing rings 42 abut against the through hole on the cover plate 5 for passing through the second valve rod 4 to seal the gap between the second valve rod 4 and the cover plate 5, so that the liquid in the valve body 1 is not likely to leak.

[0028] As Figure 4 and Figure 5As shown, an installation groove 32 is coaxially provided at the upper end of the first valve stem 3. A snap ring 33 is also fixed to the upper end of the first valve stem 3 by bolts. The inner cavity of the snap ring 33 is octagonal, and the edges of the inner cavity of the snap ring 33 are located within the installation groove 32. The first valve stem 3 and the second valve stem 4 are coaxially arranged. A clamping block 43 is rotatably connected to the lower end of the second valve stem 4. The clamping block 43 includes a lower clamping portion 432 and an upper clamping portion 431. The lower end of the second valve stem 4 passes through the upper clamping portion 431 and is arranged between the upper clamping portion 431 and the lower clamping portion 432. The upper clamping portion 431 and the lower clamping portion 432 are fixed by bolts. A plurality of sliding grooves 433 penetrate through the upper end of the upper clamping portion 431. The sliding grooves 433 are arranged around the axis of the second valve stem 4. A slider 44 is fixed to the outer wall of the second valve stem 4. The slider 44 is embedded in the sliding groove 433, so that the clamping block 43 can rotate relative to the second valve stem 4 by a certain angle, and the clamping block 43 can also be driven to rotate synchronously when the second valve stem 4 rotates. The clamping block 43 can completely sink into the installation groove 32 and be disconnected from the snap ring 33. A gap is left between the outer wall of the clamping block 43 and the inner wall of the installation groove 32, so that the first valve stem 3 will not be driven to rotate when the clamping block 43 rotates. After the clamping block 43 moves into the snap ring 33, the clamping block 43 can abut against the inner wall of the snap ring 33, and the first valve stem 3 can be driven to rotate during the rotation of the clamping block 43.

[0029] A chamfer 434 is provided at the edge of the end of the upper clamping portion 431 away from the lower clamping portion 432. The chamfer 434 can abut against the end of the inner wall of the snap ring 33 close to the installation groove 32, so as to guide the clamping block 43, cause the clamping block 43 to rotate by a certain angle, align the clamping block 43 with the inner cavity of the snap ring 33, and make the clamping block 43 better inserted into the snap ring 33.

[0030] As Figure 2 and Figure 3 As shown, a sealing assembly 6 for closing the gap formed by the second valve stem 4 passing through the valve cover 2 is further provided between the second valve stem 4 and the valve cover 2. The sealing assembly 6 includes a fixed sealing ring 61 fixed to the inner wall of the valve cover 2, a second mounting member 62 provided on the valve body 1, a movable member 63 slidably provided on the second mounting member 62, and a pressing ring 64 provided on the second movable member 63. The fixed sealing ring 61 is embedded in a groove provided at a position in the inner cavity of the valve cover 2 away from the valve body 1. The fixed sealing ring 61 is coaxially arranged with the second valve stem 4 and surrounds the second valve stem 4. A gap is left between the inner wall of the fixed sealing ring 61 and the outer wall of the second valve stem 4. The second mounting member 62 is coaxially arranged at the upper end of the first mounting member 13 and is located in the positioning groove 12. The first mounting member 13 and the second mounting member 62 abut against each other and are arranged between the valve cover 2 and the valve body 1. By the mutual extrusion between the valve cover 2 and the valve body 1, the first mounting member 13 and the second mounting member 62 can be limited. As Figure 6As shown, a guide sleeve 65 is integrally formed coaxially at the upper end of the second mounting member 62. A guide groove 631 is formed in the guide sleeve 65. The movable member 63 is arranged in the guide sleeve 65 and slides vertically. A guide block 651 is integrally formed on the outer wall of the movable member 63. The guide block 651 is embedded in the guide groove 631, thereby limiting the movement of the movable member 63 relative to the guide sleeve 65, so that the movable member 63 can only move along its own axis direction. The movable member 63 is sleeved on the outer side of the second valve stem 4. The inner diameter of the movable member 63 is larger than the outer diameter of the second valve stem 4, so that the movable member 63 is not likely to affect the vertical movement of the second valve stem 4. After the clamping block 43 at the lower end of the second valve stem 4 is located in the installation groove 32, the second valve stem 4 is rotated so that the thread on the second valve stem 4 contacts the internal thread on the movable member 63, enabling the movable member 63 to move towards the valve cover 2. A pressing ring 64 is installed at one end of the movable member 63 close to the valve cover 2. When the movable member 63 moves towards the valve cover 2, the pressing ring 64 can abut against the fixed sealing ring 61. At the same time, the movable member 63 is in threaded cooperation with the second valve stem 4, so that the gap between the second valve stem 4 and the valve cover 2 is sealed. When the cover plate 5 is disassembled and the upper sealing ring 42 is replaced, liquid leakage is not likely to occur.

[0031] As Figure 3 and Figure 6 shown, in order to make the sealing effect between the fixed sealing ring 61 and the pressing ring 64 better, a first guiding inclined surface 611 is arranged at one end of the outer wall of the fixed sealing ring 61 close to the pressing ring 64. One end of the first guiding inclined surface 611 close to the pressing ring 64 is inclined towards the second valve stem 4. A second guiding inclined surface 641 is arranged at one end of the inner wall of the pressing ring 64 close to the fixed sealing ring 61. One end of the second guiding inclined surface 641 close to the fixed sealing ring 61 is inclined towards the second valve stem 4. Thus, when the fixed sealing ring 61 and the pressing ring 64 abut against each other, the first guiding inclined surface 611 and the second guiding inclined surface 641 can abut against each other, and certain deformation and guidance will occur during the extrusion process between the two, making the connection between the fixed sealing ring 61 and the pressing ring 64 tighter.

[0032] As Figure 3 shown, in order to limit the moving distance of the second valve stem 4 relative to the valve cover 2, a limiting ring 51 is further arranged between the valve cover 2 and the cover plate 5. Both ends of the limiting ring 51 abut against the cover plate 5 and the valve cover 2 respectively, and the positions of the limiting ring 51 are limited by the valve cover 2 and the cover plate 5 together. A limiting groove 45 is coaxially formed on the second valve stem 4. A part of the limiting ring 51 is located in the limiting groove 45 and sleeved on the limiting groove 45. With the position of the limiting ring 51 being limited, the second valve stem 4 can move relative to the limiting ring 51, causing a relative position between the limiting ring 51 and the limiting groove 45. Thus, even when the second valve stem 4 can displace, it will not directly disengage from the valve cover 2.

[0033] AsFigure 3 and Figure 7 As shown in Figure 7 , in order to clearly understand whether the clamping block 43 is located in the installation groove 32, two limit pins 52 are also inserted through the cover plate 5. The limit pins 52 are perpendicular to the second valve stem 4 and are arranged along the length direction of the second valve stem 4. An anti-fooling groove 46 is formed on the outer wall of the second valve stem 4. The two limit pins 52 can be respectively inserted into the anti-fooling groove 46. The length of the anti-fooling groove 46 is greater than the diameter of the limit pin 52. When the limit pin 52 is inserted into the anti-fooling groove 46, the second valve stem 4 still has a certain moving space. When the lower limit pin 52 is inserted into the anti-fooling groove 46, the clamping block 43 is located in the installation groove 32, so that the second valve stem 4 will not drive the first valve stem 3 to rotate. When the upper limit pin 52 is inserted into the anti-fooling groove 46, the clamping block 43 is located in the snap ring 33, so that the second valve stem 4 can drive the first valve stem 3 to rotate.

[0034] As Figure 7 shown in Figure 7 , an anti-detachment pin 53 is also vertically inserted through the cover plate 5. An anti-detachment groove 521 is formed along the length direction of the limit pin 52. The anti-detachment pin 53 is inserted into the anti-detachment groove 521. Thus, when the limit pin 52 moves along its own axis, the anti-detachment pin 53 is always located in the anti-detachment groove 521 to limit the moving distance of the limit pin 52, so that the limit pin 52 can move and will not directly fall off the cover plate 5.

[0035] The implementation principle of this embodiment is as follows: Pull out both limit pins 52 outward, and then apply a downward pressure to the handwheel 41 so that the clamping block 43 enters the installation groove 32. Push the lower limit pin 52 towards the inside of the cover plate 5. Press the handwheel 41 and rotate it. The moving part 63 is in threaded cooperation with the second valve stem 4 and is driven by the second valve stem 4. The moving part 63 moves towards the valve cover 2, so that the pressing ring 64 abuts against the fixed sealing ring 61. Stop rotating when the rotation of the second valve stem 4 feels resistance. Pull out the limit pin 52 outward, disassemble the handwheel 41 and the cover plate 5, replace the upper sealing ring 42. After replacement, install the cover plate 5 and the handwheel 41. Insert the lower limit pin 52 into the cover plate 5, and rotate the handwheel 41 in the reverse direction until the rotation of the handwheel 41 no longer feels resistance, and rotate it a few more turns. Then pull out the limit pin 52, move the second valve stem 4 upward until it cannot move, and insert the upper limit pin 52 into the cover plate 5.

[0036] The embodiments of this specific implementation manner are all preferred embodiments of this application, and do not limit the protection scope of this application accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. A gate valve capable of replacing the valve stem seal ring under pressure, characterized in that: It includes a valve body (1) with one end open, a valve cover (2) for closing the opening of the valve body (1), a valve plate (11) slidably arranged in the valve body (1), a first valve rod (3) for driving the valve plate (11) to move, and a second valve rod (4) for driving the first valve rod (3) to rotate. A sealing assembly (6) is arranged between the second valve rod (4) and the valve cover (2). The first valve rod (3) is rotatably connected to the valve body (1). The first valve rod (3) passes through the valve plate (11) and is in threaded cooperation with the valve plate (11). The second valve rod (4) passes through the valve cover (2) and is in sliding cooperation with the valve cover (2). The lower end of the second valve rod (4) can be clamped with the upper end of the first valve rod (3). A cover plate (5) is detachably connected to the valve cover (2). An upper sealing ring (42) is arranged between the cover plate (5) and the second valve rod (4). The valve body (1) has a water inlet and a water outlet for fluid to pass through; The sealing assembly (6) includes a fixed sealing ring (61) fixed on the inner wall of the valve cover (2), a second mounting member (62) connected to the valve body (1), a movable member (63) slidably arranged on the second mounting member (62), and a pressing ring (64) arranged on the movable member (63). The movable member (63) is sleeved outside the second valve rod (4). The downward moving second valve rod (4) can be in threaded cooperation with the movable member (63) and make the first valve rod (3) and the second valve rod (4) disengage from the clamping connection. The movable member (63) threaded on the second valve rod (4) moves upward and makes the pressing ring (64) abut against the fixed sealing ring (61). A gap is left between the inner walls of the fixed sealing ring (61) and the pressing ring (64) and the second valve rod (4).

2. The gate valve capable of replacing the valve stem sealing ring under pressure according to claim 1, characterized in that: An installation groove (32) is formed on the first valve rod (3). A snap ring (33) is further fixed to the upper end of the first valve rod (3). A clamping block (43) is arranged at the lower end of the second valve rod (4). The clamping block (43) can be clamped in the inner cavity of the snap ring (33). The clamping block (43) can rotate in the installation groove (32) and a gap is left between the side wall of the clamping block (43) and the inner wall of the installation groove (32).

3. The gate valve capable of replacing the valve stem seal ring under pressure according to claim 2, wherein: A chamfer (434) is arranged at the upper end of the clamping block (43).

4. The gate valve capable of replacing the valve stem sealing ring under pressure according to claim 2, wherein: The clamping block (43) is rotatably connected to the lower end of the second valve rod (4). A sliding groove (433) is formed at one end of the clamping block (43) close to the valve rod. The sliding groove (433) is arranged around the rotation axis of the clamping block (43). A slider (44) is fixed to the lower end of the second valve rod (4). The slider (44) is embedded in the sliding groove (433) and slides to drive the second clamping block (43) to rotate synchronously with the second valve rod (4).

5. The gate valve capable of replacing the valve stem seal ring under pressure according to claim 1, characterized in that: A first guiding inclined surface (611) is arranged at one end of the outer wall of the fixed sealing ring (61) close to the pressing ring (64). A second guiding inclined surface (641) is arranged at one end of the inner wall of the pressing ring (64) close to the fixed sealing ring (61). The first guiding inclined surface (611) and the second guiding inclined surface (641) are in mutual abutment.

6. The gate valve capable of replacing the valve stem sealing ring under pressure according to claim 1, characterized in that: The inner wall diameter of the movable part (63) is greater than the outer diameter of the second valve stem (4).

7. The gate valve capable of replacing the valve stem sealing ring under pressure according to claim 1, wherein: A limit ring (51) is provided between the valve cover (2) and the cover plate (5). A limit groove (45) is coaxially formed on the second valve stem (4). The inner wall of the limit ring (51) is sleeved in the limit groove (45) and is in sliding fit with the limit groove (45).

8. The gate valve capable of replacing the valve stem seal ring under pressure according to claim 2, wherein: Two limit pins (52) are also inserted through the cover plate (5). An anti-fooling groove (46) is coaxially formed on the second valve stem (4). The limit pins (52) are arranged along the axis of the second valve stem (4). The limit pins (52) can be respectively inserted into the anti-fooling groove (46). When the upper limit pin (52) is inserted into the anti-fooling groove (46), the clamping block (43) is disengaged from the snap ring (33). The length of the anti-fooling groove (46) is greater than the diameter of the limit pin (52).

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