A packing seal structure and bypass valve

Abstract

The application relates to the technical field of valve sealing, in particular to a packing seal structure and a bypass valve, which comprises a packing seat, the top of the packing seat is provided with a packing groove, the packing groove is filled with sealing packing and a packing pressing sleeve, the inner end of the packing groove is provided with a pressing mechanism for pressing the bottom end of the sealing packing upwards, the pressing mechanism comprises a pressing ring which slides in the packing groove in the vertical direction, the top end of the pressing ring and the bottom end of the sealing packing abut, and the pressing mechanism changes the pressing intensity on the sealing packing by lifting. The application sets the pressing mechanism at the bottom end of the sealing packing, changes the downward movement of the pressing column into the rotary movement of the driving seat by using the transmission mechanism, makes the pressing ring rise through the rotary movement of the driving seat, presses the bottom end of the sealing packing, makes the forces on the two ends of the sealing packing uniform, guarantees the sealing, avoids the damage of the sealing ring caused by the excessive unilateral extrusion force, and prolongs the service life of the packing seal structure.

Description

Technical Field

[0001] This invention relates to the field of valve sealing technology, specifically to a packing seal structure and a bypass valve. Background Technology

[0002] Bypass valves are commonly used control components in conveying systems. They are used for media diversion in main pipelines or media bypass during equipment maintenance. The dynamic sealing performance at the valve stem is directly related to the system's operational safety and the risk of media leakage.

[0003] In existing technologies, bypass valves typically employ a packing seal structure to achieve dynamic sealing at the valve stem. This packing seal structure mainly consists of components such as a stuffing box, sealing packing, a packing sleeve, and a packing gland. The stuffing box houses the sealing packing, and the packing sleeve and packing gland compress the packing, causing radial deformation and bringing it into sealing contact with the valve stem, thus achieving dynamic sealing at the valve stem.

[0004] However, existing packing glands and packing sleeves typically compress the sealing packing from top to bottom, meaning the top of the sealing packing is the first to be subjected to compressive force. Since the sealing packing is formed by stacking multiple sealing rings, the compressive force on the sealing rings farther from the packing sleeve gradually decreases, resulting in uneven compressive force at both ends of the sealing packing and difficulty in forming an effective radial seal. Therefore, this invention proposes a packing seal structure and bypass valve to effectively solve the above-mentioned drawbacks. Summary of the Invention

[0005] The purpose of this invention is to provide a packing seal structure and a bypass valve to solve the problems mentioned in the background art.

[0006] The present invention is achieved through the following technical solution: a packing seal structure, including a packing seat disposed on the top of the valve body and through which the valve stem passes, the packing seat having a through structure, and an annular packing groove radially opened on the inner side of its top, the packing groove being filled with sealing packing along the valve stem axial direction, and a packing pressure sleeve provided at the top opening of the packing groove, the packing pressure sleeve being slidably sleeved on the outside of the valve stem and used to apply downward pressure to the top of the sealing packing; The inner end of the packing groove is provided with a pressure applying mechanism, which is used to apply upward pressure to the bottom end of the sealing packing; The pressure applying mechanism includes a pressure applying ring that is slidably sleeved on the outside of the valve stem along the valve stem axis. The top end of the pressure applying ring abuts against the bottom end of the sealing packing. The pressure applying mechanism changes the pressure applied to the sealing packing by raising and lowering. The packing seat is provided with a clamping column that moves axially along the valve stem. The packing seat is provided with a transmission mechanism. The power input end of the transmission mechanism is connected to the clamping column, and the power output end of the transmission mechanism is used to drive the pressure ring to rise and fall. When the clamping column and the packing sleeve are in the initial stage of synchronous downward movement, the pressure ring is driven to move synchronously upward through the transmission mechanism. The packing sleeve and the pressure ring apply pressure to both ends of the sealing packing respectively. When the clamping column and the packing sleeve continue to move downward, the pressure ring stops moving upward, the packing sleeve applies pressure to the top of the sealing packing, and the pressure ring and the medium pressure below the packing seat together apply pressure to the bottom of the sealing packing.

[0007] Optionally, the pressure applying mechanism further includes a drive seat movably sleeved on the outside of the valve stem. The drive seat is located at the bottom end of the pressure applying ring. The output end of the transmission mechanism is connected to the drive seat. The transmission mechanism is used to control the rotation of the drive seat. The drive seat controls the lifting and lowering of the pressure applying ring by rotation.

[0008] Optionally, the drive seat includes a drive ring and a bevel gear ring. The bevel gear ring is fixedly connected to the bottom end of the drive ring. Several circumferentially distributed extension rods are fixedly provided on the side of the drive ring. The ends of the extension rods are rotatably connected to sliders. Several circumferentially distributed guide rails for corresponding sliders to slide are provided on the outer wall of the pressure ring.

[0009] Optionally, the guide rail includes a short horizontal section, an inclined section, and a long horizontal section. The short horizontal section is at a higher height than the long horizontal section, and the two ends of the inclined section are respectively connected to the short horizontal section and the inclined section. When the slider is in the short horizontal section, the pressure applied by the pressure ring to the sealing packing is at its minimum; when the slider moves from the inclined section to the long horizontal section, the pressure applied by the pressure ring to the sealing packing gradually increases; when the slider moves in the long horizontal section, the pressure applied by the pressure ring to the sealing packing is at its maximum, and the pressure ring no longer rises.

[0010] Optionally, the pressure ring has several guide posts arranged in a circle on its side. One end of the guide post is elastically connected to the inside of the pressure ring along the radial direction of the pressure ring, and the other end of the guide post protrudes outward from the pressure ring. The inner wall of the packing groove of the packing seat has a guide groove along the valve stem axis for the guide post to slide.

[0011] Optionally, the packing seat has an assembly channel for mounting the transmission mechanism along its width direction. The assembly channel is connected to the packing groove. The transmission mechanism includes a transmission shaft rotatably disposed in the assembly channel. One end of the transmission shaft extends into the packing groove and is fixedly fitted with a bevel gear. The bevel gear meshes with the bevel gear ring.

[0012] Optionally, the packing seat has a movable cavity along the valve stem axial direction for inserting the clamping column. The movable cavity is connected to the assembly channel. A driven gear is fixedly mounted on the outside of the drive shaft. The driven gear is located in the movable cavity. A rack is fixedly connected to the bottom end of the clamping column. The rack and the driven gear mesh with each other.

[0013] Optionally, a sealing sleeve is fixedly fitted on the outside of the drive shaft, the shape of which is adapted to the shape of the assembly channel, and the sealing sleeve and the assembly channel are sealed and fitted together.

[0014] Optionally, a bellows is fitted on the outer side of the top of the clamping column, the top of the clamping column is sealed and fixedly connected to the top of the bellows through a sealing flange, and the bottom of the bellows is sealed and fixedly connected to the packing seat through a sealing flange.

[0015] This application also proposes a bypass valve, including the above-mentioned packing sealing structure, and a valve cover disposed above the packing seat. The valve cover is movably fitted on the outside of the valve stem, and the bottom surface of the valve cover abuts against the top of the packing sleeve and the clamping column.

[0016] Compared with the prior art, the present invention provides a packing seal structure and a bypass valve, which have the following beneficial effects: 1. This invention provides a pressure-applying mechanism at the bottom of the sealing packing. The transmission mechanism converts the downward movement of the pressing column into the rotational movement of the drive seat. The rotation of the drive seat causes the pressure ring to rise, thereby applying pressure to the bottom of the sealing packing. This, combined with the packing sleeve, achieves bidirectional synchronous pressure application, resulting in more uniform deformation of the sealing packing and even force distribution at both ends. While ensuring the seal at the valve stem, it also prevents excessive pressure on one side of the sealing packing from damaging the sealing ring, thus extending the service life of the packing sealing structure. 2. In this invention, during the process of the packing sleeve moving downward to compress the sealing packing, the pressure ring first rises synchronously to compress the sealing packing, and then stops rising to stop compressing the bottom end of the sealing packing. This avoids excessive extrusion pressure on the bottom end of the sealing packing when it is subjected to the pressure of the gas medium inside the valve body during valve body use, which would exacerbate the deformation of the bottom end and easily damage the sealing ring, affecting the normal use of the packing sealing structure. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a side sectional view of the packing seat of the present invention; Figure 3 This is a schematic diagram of the pressure application mechanism of the present invention; Figure 4 This is a side cross-sectional view of the pressure ring of the present invention; Figure 5This is a schematic diagram of the drive seat structure of the present invention; Figure 6 This is a schematic diagram of the transmission mechanism structure of the present invention; Figure 7 for Figure 2 Enlarged structural diagram at point A in the middle.

[0018] In the diagram: 1. Packing seat; 101. Compression column; 102. Rack; 103. Bellows; 2. Sealing packing; 3. Packing sleeve; 4. Pressurizing mechanism; 401. Pressurizing ring; 402. Drive seat; 4021. Drive ring; 4022. Bevel gear ring; 4023. Extension rod; 4024. Slider; 403. Guide rail; 4031. Short horizontal section; 4032. Inclined section; 4033. Long horizontal section; 404. Guide column; 5. Transmission mechanism; 501. Drive shaft; 502. Bevel gear; 503. Driven gear; 6. Valve cover. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1: Please refer to Figure 1 - Figure 7 This application proposes a packing seal structure, including a packing seat 1 located at the top of the valve body and through which the valve stem passes. The packing seat 1 is a vertically continuous structure, with an annular packing groove radially opened on the inner side of its top. Sealing packing 2 is filled in the packing groove along the valve stem axial direction. A packing pressure sleeve 3 is provided at the top opening of the packing groove. The packing pressure sleeve 3 is slidably sleeved on the outside of the valve stem and used to apply downward pressure to the top of the sealing packing 2.

[0021] The sealing packing 2 consists of several layers of sealing rings stacked together. The packing sleeve 3 moves from top to bottom, squeezing the top of the sealing packing 2 to deform the sealing rings and tighten them around the valve stem to achieve a seal. The extrusion pressure on the sealing rings far from the packing sleeve 3 decreases relative to the extrusion pressure on the top sealing rings. Therefore, the bottom sealing rings may not be able to guarantee a seal with the valve stem due to insufficient deformation.

[0022] In this embodiment, a pressure applying mechanism 4 is provided at the inner end of the packing groove. The pressure applying mechanism 4 is used to apply pressure upward to the bottom end of the sealing packing 2. Through the cooperation of the pressure applying mechanism 4 and the packing sleeve 3, pressure is applied to both ends of the sealing packing 2, so that the force on both ends of the sealing packing 2 is more uniform, ensuring that the deformation degree of the sealing ring is more uniform, and ensuring the sealing performance between the sealing packing and the valve stem.

[0023] Specifically, the pressure applying mechanism 4 includes a pressure applying ring 401 that is slidably sleeved on the outside of the valve stem along the valve stem axis. The top end of the pressure applying ring 401 abuts against the bottom end of the sealing packing 2. The pressure applying mechanism 4 changes the pressure applied to the sealing packing 2 by raising and lowering.

[0024] Furthermore, the pressure applying mechanism 4 also includes a drive seat 402 movably sleeved on the outside of the valve stem. The drive seat 402 is located at the bottom end of the pressure applying ring 401, and the drive seat 402 controls the lifting and lowering of the pressure applying ring 401 by rotation.

[0025] The pressure ring 401 has several guide posts 404 arranged in a circle on its side. One end of the guide post 404 is elastically connected to the inside of the pressure ring 401 along the radial direction of the pressure ring 401, and the other end of the guide post 404 protrudes outward from the pressure ring 401. The inner wall of the packing groove of the packing seat 1 is provided with a guide groove along the valve stem axis for the guide post 404 to slide.

[0026] One end of the guide post 404 located inside the pressure ring 401 is elastically connected to the pressure ring 401 via a spring, similar to a spring-ball mechanism. In its natural state, the spring is compressed and always applies an elastic force to the guide post 404, causing it to move outward from the pressure ring 401. When installing the pressure ring 401 into the packing groove, the guide post 404 can be manually pressed into the pressure ring 401, or the guide post 404 can be directly driven to retract by the inclined surface at the top of the packing groove until the pressure ring 401 is in place. Then, the pressure ring 401 can be rotated to embed the guide post 404 into the guide groove, thus completing the circumferential limiting operation of the pressure ring 401, preventing it from rotating and allowing it to move only vertically.

[0027] Furthermore, the drive seat 402 includes a drive ring 4021 and a bevel gear ring 4022. The bevel gear ring 4022 is fixedly connected to the bottom end of the drive ring 4021. Several circumferentially distributed extension rods 4023 are fixedly provided on the side of the drive ring 4021. The ends of the extension rods 4023 are rotatably connected to sliders 4024. Several circumferentially distributed guide rails 403 are provided on the outer wall of the pressure ring 401 for sliding of the corresponding sliders 4024.

[0028] The extension rod 4023 is U-shaped, and the slider 4024 is rotatably connected to the end of the extension rod 4023 away from the drive ring 4021. The end of the slider 4024 is a hemispherical structure and slides within the guide rail 403 so that the slider 4024 can slide smoothly within the guide rail 403.

[0029] On the other hand, the extension rod 4023 located at one end of the drive ring 4021 can be installed by welding or flange fixing. During processing, the end of the extension rod 4023 with the slider 4024 needs to be placed into the guide rail 403 first, and then the other end of the extension rod 4023 is welded to the drive ring 4021.

[0030] It should be noted that the guide rail 403 includes a short horizontal section 4031, an inclined section 4032, and a long horizontal section 4033. The short horizontal section 4031 is at a higher height than the long horizontal section 4033. The two ends of the inclined section 4032 are connected to the short horizontal section 4031 and the inclined section 4032, respectively.

[0031] Therefore, when the slider 4024 is in the short horizontal section 4031, the pressure ring 401 is in its initial position, at which point the pressure applied by the pressure ring 401 to the sealing packing 2 is at its minimum. When the drive seat 402 rotates, the slider 4024 moves from the short horizontal section 4031 to the inclined section 4032, and then moves within the inclined section 4032 towards the long horizontal section 4033. During this movement, the height of the pressure ring 401 continuously increases, and the pressure applied by the pressure ring 401 to the sealing packing 2 gradually increases. When the slider 4024 moves within the long horizontal section 4033, the height of the pressure ring 401 is at its maximum, the pressure applied by the pressure ring 401 to the sealing packing 2 is at its maximum, and the pressure ring 401 no longer rises further when the drive seat 402 rotates.

[0032] If the pressure ring 401 continuously increases the pressure on the bottom of the sealing packing 2 during the process of increasing the pressure on the top of the sealing packing 2 by the packing sleeve 3, then when the valve body is in use, the gas medium inside the valve body will exert a certain pressure on the bottom of the sealing packing 2. Obviously, under the condition that the pressure ring 401 continuously increases the pressure, the extrusion force on the bottom of the sealing packing 2 will be too large, which will easily damage the sealing packing 2 and thus affect the normal use of the packing sealing structure.

[0033] In order to enable the drive seat 402 to rotate, in this application, a pressing column 101 is provided on the packing seat 1 along the valve stem axial direction. A transmission mechanism 5 is provided inside the packing seat 1. The power input end of the transmission mechanism 5 is connected to the pressing column 101, and the power output end of the transmission mechanism 5 is used to drive the pressure ring 401 to rise and fall.

[0034] The output end of the transmission mechanism 5 is connected to the drive seat 402. The transmission mechanism 5 is used to drive the drive seat 402 to rotate, and the pressure ring 401 is raised and lowered by the rotation of the drive seat 402.

[0035] Specifically, the packing seat 1 has an assembly channel along its width for mounting the transmission mechanism 5. The assembly channel is connected to the packing groove. The transmission mechanism 5 includes a drive shaft 501 rotatably mounted in the assembly channel. One end of the drive shaft 501 extends into the packing groove and is fixedly fitted with a bevel gear 502. The bevel gear 502 meshes with a bevel gear ring 4022. Therefore, by rotating the drive shaft 501 and the bevel gear 502, the bevel gear ring 4022 can be rotated. The bevel gear ring 4022 drives the drive ring 4021 to rotate. The drive ring 4021 drives the pressure ring 401 to rise and fall through the extension rod 4023 and the slider 4024, thereby applying pressure to the bottom end of the sealing packing 2.

[0036] To ensure that the pressure ring 401 can simultaneously apply pressure to the bottom end of the sealing packing 2 when the packing sleeve 3 applies downward pressure to the sealing packing 2, in this application, the packing seat 1 has a movable cavity along the valve stem axial direction for inserting the clamping column 101. The movable cavity is connected to the assembly channel. A driven gear 503 is fixedly fitted on the outside of the drive shaft 501, and the driven gear 503 is located inside the movable cavity. A rack 102 is fixedly connected to the bottom end of the clamping column 101, and the rack 102 meshes with the driven gear 503. Therefore, when the clamping column 101 and the packing sleeve 3 move downward synchronously, the rack 102 can drive the driven gear 503 to rotate, thereby causing the drive shaft 501 and the bevel gear 502 to rotate, ultimately driving the pressure ring 401 to rise.

[0037] Therefore, when the clamping column 101 and the packing sleeve 3 are in the initial stage of synchronous downward movement, the slider 4024 is located in the short horizontal section 4031 and moves from the short horizontal section 4031 to the inclined section 4032 and the long horizontal section 4033. Through the transmission mechanism 5, the pressure ring 401 moves synchronously upward. The packing sleeve 3 and the pressure ring 401 apply pressure to both ends of the sealing packing 2 respectively. When the clamping column 101 and the packing sleeve 3 continue to move downward, the slider 4024 has moved into the long horizontal section 4033. The slider 4024 will continue to move in the long horizontal section 4033, while the pressure ring 401 will stop moving upward, so that the packing sleeve 3 applies pressure to the top of the sealing packing 2. The pressure ring 401 and the medium pressure below the packing seat 1 together apply pressure to the bottom of the sealing packing 2.

[0038] The shape of the clamping column 101 is adapted to the shape of the movable cavity, and a sealing gasket is provided on the outer side of the clamping column 101 to seal against the inner wall of the movable cavity to ensure airtightness.

[0039] On the other hand, a sealing sleeve is provided on the outer fixed sleeve of the drive shaft 501. The shape of the sealing sleeve is adapted to the assembly channel, and the sealing sleeve and the assembly channel are sealed and fitted together, which also ensures the sealing of the assembly channel.

[0040] Meanwhile, a sealing flange is rotatably connected to the end of the drive shaft 501 away from the bevel gear 502. The sealing flange is fixedly installed on the side wall of the packing seat 1 by fasteners such as screws, spirals, and retaining washers. A sealing gasket is provided on the side of the sealing flange facing the packing seat 1 to ensure the sealing effect at the opening of the assembly channel.

[0041] Furthermore, a bellows 103 is fitted around the top of the clamping column 101. The top of the clamping column 101 is sealed and fixedly connected to the top of the bellows 103 via a sealing flange, and the bottom of the bellows 103 is sealed and fixedly connected to the packing seat 1 via a sealing flange. Therefore, the opening at the top of the moving chamber can also be sealed, ensuring that the gas medium in the valve body will not leak from the assembly channel and the moving chamber.

[0042] It is worth mentioning that, such as Figure 2 and Figure 7 As shown, a packing pad is provided at the bottom of the drive seat 402. The packing pad is made of hard material and is movably sleeved on the outside of the valve stem in an annular shape. It is used to support the drive seat 402 and provide a stable support force for the pressure application mechanism 4, so that the drive seat 402 can stably mesh with the bevel gear 502 and improve the stability of the pressure application mechanism 4 and the transmission mechanism 5.

[0043] The packing gasket can be made of materials such as PTFE and graphite composite gasket, which have high rigidity, pressure resistance and non-deformation, wear resistance and adaptability to temperature and pressure. The top friction surface is made of fine grinding and mirror polishing process to control the surface roughness to Ra0.4-Ra1.6μm, eliminating machining marks and burrs. During use, lubricating oil and other lubricating materials can be applied to the top surface of the packing gasket to reduce micro-mechanical meshing friction and reduce the wear rate of the friction surface, making the rotation of the drive seat 402 smoother and adaptable to the high temperature and high pressure working environment of the bypass valve.

[0044] Example 2: Please refer to Figure 1 - Figure 7 This application also proposes a bypass valve, including the packing seal structure of Embodiment 1, and a valve cover 6 disposed above the packing seat 1. The valve cover 6 is movably fitted on the outside of the valve stem, and the bottom surface of the valve cover 6 abuts against the top of the packing sleeve 3 and the clamping column 101.

[0045] Furthermore, a bolt that can be inserted into the packing seat 1 is provided through the valve cover 6. A nut is fitted on the end of the bolt. By rotating the bolt and nut, the depth of the bolt inserted into the packing seat 1 is changed, thereby changing the height of the valve cover 6, so that the valve cover 6 can drive the packing sleeve 3 and the clamping column 101 to rise and fall synchronously.

[0046] The working principle and usage process of this invention are as follows: In use, firstly, the packing pad, pressure applying mechanism 4, sealing packing 2, and packing sleeve 3 are placed into the packing groove in sequence. Then, the transmission mechanism 5 is installed into the assembly channel, so that the bevel gear 502 and the bevel gear ring 4022 mesh. Finally, the valve cover 6 is installed above the packing seat 1, so that the pressing column 101 extends into the movable cavity, and the rack 102 and the driven gear 503 mesh. By adjusting the height of the valve cover 6, the pressure intensity on the sealing packing 2 can be changed, and both ends of the sealing packing 2 can be subjected to uniform extrusion pressure, so that the deformation of the sealing packing 2 is more uniform, ensuring the sealing performance between the valve stem and the sealing packing 2.

[0047] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0048] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A packing seal structure, comprising a packing seat disposed at the top of a valve body and through which a valve stem passes, the packing seat being a through-structure, wherein an annular packing groove is radially formed on the inner side of its top, and sealing packing is filled in the packing groove along the axial direction of the valve stem, characterized in that: A packing sleeve is provided at the top opening of the packing groove. The packing sleeve is slidably sleeved on the outside of the valve stem and is used to apply downward pressure to the top of the sealing packing. The inner end of the packing groove is provided with a pressure applying mechanism, which is used to apply upward pressure to the bottom end of the sealing packing; The pressure applying mechanism includes a pressure applying ring that is slidably sleeved on the outside of the valve stem along the valve stem axis. The top end of the pressure applying ring abuts against the bottom end of the sealing packing. The pressure applying mechanism changes the pressure applied to the sealing packing by raising and lowering. The packing seat is provided with a clamping column that moves axially along the valve stem. The packing seat is provided with a transmission mechanism. The power input end of the transmission mechanism is connected to the clamping column, and the power output end of the transmission mechanism is used to drive the pressure ring to rise and fall. When the clamping column and the packing sleeve are in the initial stage of synchronous downward movement, the pressure ring is driven to move synchronously upward through the transmission mechanism. The packing sleeve and the pressure ring apply pressure to both ends of the sealing packing respectively. When the clamping column and the packing sleeve continue to move downward, the pressure ring stops moving upward, the packing sleeve applies pressure to the top of the sealing packing, and the pressure ring and the medium pressure below the packing seat together apply pressure to the bottom of the sealing packing.

2. The packing sealing structure according to claim 1, characterized in that: The pressure-applying mechanism also includes a drive seat movably sleeved on the outside of the valve stem. The drive seat is located at the bottom end of the pressure-applying ring. The output end of the transmission mechanism is connected to the drive seat. The transmission mechanism is used to control the rotation of the drive seat. The drive seat controls the lifting and lowering of the pressure-applying ring by rotating.

3. The packing sealing structure according to claim 2, characterized in that: The drive base includes a drive ring and a bevel gear ring. The bevel gear ring is fixedly connected to the bottom end of the drive ring. Several circumferentially distributed extension rods are fixedly provided on the side of the drive ring. The ends of the extension rods are rotatably connected to sliders. Several circumferentially distributed guide rails for corresponding sliders to slide are provided on the outer wall of the pressure ring.

4. The packing seal structure according to claim 3, characterized in that: The guide rail includes a short horizontal section, an inclined section, and a long horizontal section. The short horizontal section is at a higher height than the long horizontal section. The two ends of the inclined section are respectively connected to the short horizontal section and the inclined section. When the slider is in the short horizontal section, the pressure applied by the pressure ring to the sealing packing is at its minimum; when the slider moves from the inclined section to the long horizontal section, the pressure applied by the pressure ring to the sealing packing gradually increases; when the slider moves in the long horizontal section, the pressure applied by the pressure ring to the sealing packing is at its maximum, and the pressure ring no longer rises.

5. The packing seal structure according to claim 4, characterized in that: The pressure ring has several guide posts arranged in a circle on its side. One end of the guide post is elastically connected to the inside of the pressure ring along the radial direction of the pressure ring, and the other end of the guide post protrudes outward from the pressure ring. The inner wall of the packing groove of the packing seat has a guide groove along the valve stem axis for the guide post to slide.

6. The packing seal structure according to claim 3, characterized in that: The packing seat has an assembly channel for installing the transmission mechanism along its width. The assembly channel is connected to the packing groove. The transmission mechanism includes a transmission shaft that is rotatably installed in the assembly channel. One end of the transmission shaft extends into the packing groove and is fixedly fitted with a bevel gear. The bevel gear meshes with the bevel gear ring.

7. The packing seal structure according to claim 6, characterized in that: The packing seat has a movable cavity along the valve stem axial direction for inserting the clamping column. The movable cavity is connected to the assembly channel. A driven gear is fixedly mounted on the outside of the drive shaft. The driven gear is located in the movable cavity. A rack is fixedly connected to the bottom end of the clamping column. The rack and the driven gear mesh with each other.

8. The packing seal structure according to claim 7, characterized in that: A sealing sleeve is fixedly fitted on the outside of the drive shaft. The shape of the sealing sleeve is adapted to the assembly channel, and the sealing sleeve and the assembly channel are sealed and fitted together.

9. The packing seal structure according to claim 7, characterized in that: A bellows is fitted on the outer side of the top of the clamping column. The top of the clamping column is sealed and fixedly connected to the top of the bellows through a sealing flange. The bottom of the bellows is sealed and fixedly connected to the packing seat through a sealing flange.

10. A bypass valve, comprising the packing seal structure according to any one of claims 1-9, characterized in that: It also includes a valve cover disposed above the packing seat, the valve cover being movably fitted on the outside of the valve stem, the bottom surface of the valve cover abutting against the top of the packing sleeve and the clamping column.

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