Fluorine-lined double eccentric butterfly valve

Abstract

This invention relates to the field of double eccentric butterfly valve technology, specifically to a fluoropolymer-lined double eccentric butterfly valve. It solves the problem of excessive friction between the valve plate and valve seat during opening and closing in existing centerline butterfly valves. A fluoropolymer-lined double eccentric butterfly valve includes an upper valve body and a lower valve body, which are detachably connected by bolts. The upper and lower valve bodies together form a valve cavity, within which a lined valve seat is provided, abutting against the inner wall of the valve cavity. A valve stem is rotatably connected within the valve cavity, and a valve plate is welded and fixed to the valve stem. The valve stem axis is offset from the center of the valve plate sealing surface and from the center of the valve cavity channel. This invention solves the problem of excessive friction between the valve plate and valve seat during opening and closing, greatly extending the service life of the fluoropolymer-lined butterfly valve and significantly reducing the operating torque. It allows for the use of a relatively smaller actuator, saving pipeline installation space and making it more convenient for users.

Description

Technical Field

[0001] This invention relates to the field of double eccentric butterfly valve technology, specifically to a fluoropolymer-lined double eccentric butterfly valve. Background Technology

[0002] Butterfly valves are one of the most commonly used valve types in industrial pipelines. Their core opening and closing element is a disc-shaped butterfly plate, which rotates 0° to 90° around the valve stem axis to achieve pipeline on / off switching or flow regulation. They are named for the butterfly plate's resemblance to butterfly wings. Belonging to the rotary valve category, they combine both shut-off and regulation functions and are a mainstream valve type for medium and low-pressure pipeline systems.

[0003] Most butterfly valves on the market adopt a center-line butterfly valve design. This design achieves a sealing effect by squeezing the valve seat, causing it to adhere tightly to the valve plate and generating enormous friction. However, due to constant squeezing and friction during use, the valve plate sealing surface is easily damaged, leading not only to leaks but also restricting the flow of particulate matter and limiting its application scenarios. The high coefficient of friction results in extremely high torque required for opening and closing, necessitating a larger actuator, which reduces pipeline installation space and makes operation inconvenient for users. If a valve leaks, the entire valve must be removed from the pipeline, and the lining components cannot be replaced without individual replacement, resulting in high maintenance costs. Summary of the Invention

[0004] This invention proposes a fluoropolymer-lined double eccentric butterfly valve, which solves the problem of excessive friction between the valve plate and valve seat during opening and closing of existing centerline butterfly valves. This significantly extends the service life of the butterfly valve and greatly reduces the operating torque, thus improving the practicality of the equipment.

[0005] The technical solution of the present invention is as follows: A fluoropolymer-lined double eccentric butterfly valve includes an upper valve body and a lower valve body. The upper valve body and the lower valve body are detachably connected by bolts. The upper valve body and the lower valve body together form a valve cavity. A lined valve seat is provided in the valve cavity. The lined valve seat abuts against the inner wall of the valve cavity. A valve stem is rotatably connected in the valve cavity. A valve plate is welded and fixed on the valve stem. The axis of the valve stem is offset from the center of the sealing surface of the valve plate and offset from the center of the valve cavity channel.

[0006] Furthermore, a corrosion-resistant fluoroplastic packing sealing assembly is provided at the penetration position between the upper valve body and the valve stem. The corrosion-resistant fluoroplastic packing sealing assembly includes one or more of a gland, PTFE packing, a sealing ring, a spring washer, and a valve stem sleeve. A sealing layer is wrapped around the valve plate, and the sealing layer is fluoroplastic.

[0007] Furthermore, the valve stem has an outer shell at its top, which is fixedly connected to the upper valve body. The outer shell has a working chamber, which contains a first force-saving structure for saving valve opening torque and a second force-saving structure for saving valve closing torque. The working chamber also contains a switching structure for activating the first force-saving structure and closing the second force-saving structure during valve opening stroke when the valve stem rotation angle automatically switches, or activating the second force-saving structure and closing the first force-saving structure during valve closing.

[0008] Furthermore, the first labor-saving structure includes a first gear, a sliding frame is slidably connected in the working cavity, the first gear is rotatably connected to the sliding frame, a rotating disk is fixed on the valve stem, a plurality of connecting columns are fixed on the rotating disk, the first gear meshes with the connecting columns, a first cam is also fixed on the first gear, and the sliding frame is provided with a first labor-saving component, which abuts against the first cam.

[0009] Furthermore, a roller is rotatably connected to the first labor-saving component, and the roller rolls against the first cam. A sliding component is fixed on the sliding frame, and a first sliding groove is provided inside the sliding component. The first labor-saving component is slidably connected to the first sliding groove. The first sliding groove is provided with a first limiting spring. The two ends of the first limiting spring are respectively fixedly connected to the first sliding groove and the first labor-saving component. The cross-section of the first sliding groove is a "square" structure.

[0010] Furthermore, the second force-saving structure includes a second gear, which is rotatably connected to the sliding frame and meshes with the connecting column. A second cam is also fixed on the second gear. The sliding frame is also provided with a second force-saving component, which abuts against the second cam. The structure of the second force-saving component is the same as that of the first force-saving component.

[0011] Furthermore, the first cam and the second cam have the same shape, and the angle between the first cam and the second cam is 90°.

[0012] Furthermore, the sliding frame is provided with a first reset component and a second reset component. The first reset component has a reset cavity inside. A rotating shaft is fixed on the first cam. A first locking block is fixed on the rotating shaft. A second locking block is fixed on the inner wall of the reset cavity. A reset spring is wound on the rotating shaft. The two ends of the reset spring are fixedly connected to the first locking block and the second locking block, respectively. The first reset component and the second reset component have the same structure.

[0013] Furthermore, the switching structure includes a third gear, on which a rotating rod is fixed. The rotating rod is sleeved inside the valve stem and rotatably connected to the valve stem. A first limiting protrusion is fixed on the rotating rod, and a second limiting protrusion is fixed on the valve stem. The first and second limiting protrusions abut against each other. A sliding rack is fixed on the sliding frame, and the sliding rack meshes with the third gear. A sliding notch is provided at the top of the sliding frame, through which the third gear passes. A first limiting block and a second limiting block are fixed on both sides of the sliding rack at the top of the sliding frame.

[0014] Furthermore, the first limiting block and the second limiting block are respectively provided with a first limiting groove and a second limiting groove. A second limiting spring is fixed in the first limiting groove and a third limiting spring is fixed in the second limiting groove. The sliding stroke of the sliding rack is less than the distance between the first limiting groove and the third gear.

[0015] Furthermore, the outer casing is also provided with a knob groove, in which a knob switch is slidably connected. The top of the rotating rod is provided with a third limiting groove, the cross-section of which is circular. The inner wall of the third limiting groove is provided with a slot. A first locking pin is fixed on the knob switch. The knob switch is slidably connected to the third limiting groove, and the first locking pin is inserted into the slot.

[0016] Furthermore, a limiting structure is provided between the outer shell and the rotary switch. The limiting structure includes a fourth limiting spring. A positioning component is fixed on the outer shell. The positioning component has a positioning groove, which is a cross-shaped structure. Second locking pins are also provided on both sides of the rotary switch. The second locking pins are inserted into the positioning groove. The fourth limiting spring is sleeved on the rotary switch. The two ends of the fourth limiting spring are fixedly connected to the second locking pin and the top of the rotating rod, respectively.

[0017] The working principle and beneficial effects of this invention are as follows: The installation process in this embodiment is as follows: The valve plate and valve stem are welded and fixed to form a whole, and then completely wrapped with fluoroplastic. The valve stem is first inserted into the "valve stem hole" on the valve seat, and then the valve seat is squeezed to deform it, and the valve plate is embedded as a whole.

[0018] The PTFE packing block is inserted into the gap between the valve plate and the upper end of the valve seat. The PTFE packing block has a wedge-shaped design, and the pressure from above creates a squeezing force on the inner and outer walls, thereby eliminating the tolerance gap (the upper and lower valve stem parts are exactly the same). The valve stem sleeve provides downward pressure to the PTFE packing block, and the gland provides downward pressure to the valve stem sleeve. The gland is connected to the valve body by screws and has sufficient clearance, allowing users to apply secondary pressure during use to enhance the sealing effect.

[0019] The lining valve seat is inserted entirely into the inner cavity of the lower valve body, ensuring that the outer wall of the lining valve seat is pre-fitted and positioned against the inner wall of the valve cavity of the lower valve body, guaranteeing that the lining valve seat is placed correctly, without offset or wrinkles. Then, the upper valve body is aligned and fastened onto the upper valve body, so that the upper and lower valve bodies together form a complete valve cavity. Simultaneously, the lining valve seat is fully fitted and abutted against the inner wall of the valve cavity. The clamping and holding of the upper and lower valve bodies provides overall restraint to the lining valve seat, thus completing the initial pre-assembly and positioning of the valve body and lining valve seat.

[0020] Tighten the screws on both sides of the valve body to complete the assembly.

[0021] This invention detachably connects the upper and lower valve bodies together with bolts. By offsetting the valve stem axis from the center of the valve plate sealing surface and the valve stem axis from the center of the valve cavity channel, it replaces the valve body structure of the existing butterfly valve that directly passes through the centerline. This invention can solve the problem of excessive friction between the valve plate and the valve seat when opening and closing, greatly extending the service life of the PTFE-lined butterfly valve, and greatly reducing the operating torque. It can use a relatively small actuator, saves installation space, and makes it more convenient for users. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the prior art in this embodiment; Figure 2 This is a schematic diagram of the overall structure of Example 1. Figure 1 ; Figure 3 This is a schematic diagram of the overall structure of Example 1. Figure 2 ; Figure 4 This is a schematic diagram of the internal structure of Example 1; Figure 5 This is a schematic diagram of the overall structure of Example 2; Figure 6 This is a schematic diagram of the internal structure of Example 2; Figure 7 This is a schematic diagram of the connection structure of the first force-saving component in Example 2; Figure 8 This is a schematic diagram of the connection structure of the sliding frame in Example 2; Figure 9 This is a schematic diagram of the structure of the first reset component in Embodiment 2; Figure 10This is a schematic diagram of the rotary switch in Example 2; Figure 11 This is a schematic diagram of the connection structure between the second locking pin and the positioning component in Example 2; Figure 12 This is a schematic diagram of the connection structure between the rotating rod and the valve stem in Example 2.

[0024] Explanation of icon numbers: 11. Valve cavity; 12. Upper valve body; 13. Lower valve body; 14. Gland; 15. Lined valve seat; 16. PTFE packing; 17. Spring washer; 18. Sealing ring; 19. Valve stem sleeve; 2. Valve plate; 21. Sealing layer; 3. Valve stem; 31. Rotating disc; 32. Connecting column; 33. Third limiting groove; 331. Slot; 34. Rotating rod; 341. First limiting protrusion; 35. Second limiting protrusion; 4. Outer shell; 41. Knob groove; 42. Positioning component; 421. Positioning groove; 43. Working chamber; 5. Rotary switch; 51. First locking pin; 52. Fourth limiting spring; 53. Second locking pin; 6. Sliding bracket; 61. Third gear; 611. Sliding rack; 62. First limiting block; 621. First limiting groove; 622. Second limiting spring; 63. Second limiting block; 631. Second limiting groove; 632. Third limiting spring; 64. Sliding notch; 71. First gear; 711. First cam; 7111. Rotating shaft; 7112. First locking block; 712. Sliding component; 713. First labor-saving component; 714. Roller; 715. First sliding groove; 716. First limiting spring; 72. Second gear; 721. Second cam; 722. Second labor-saving component; 81. First reset component; 811. Reset cavity; 812. Second locking block; 82. Second reset component.

[0025] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0027] Example 1: like Figures 2-4 As shown, a fluoropolymer-lined double eccentric butterfly valve includes an upper valve body 12 and a lower valve body 13. In this embodiment, the upper valve body 12 and the lower valve body 13 are detachably connected by bolts. The upper valve body 12 and the lower valve body 13 together form a valve cavity 11. A lined valve seat 15 is provided in the valve cavity 11. The lined valve seat 15 abuts against the inner wall of the valve cavity 11. A valve stem 3 is rotatably connected in the valve cavity 11. A valve plate 2 is welded and fixed on the valve stem 3. The axis of the valve stem 3 is offset from the center of the sealing surface of the valve plate 2. The axis of the valve stem 3 is offset from the center of the channel of the valve cavity 11.

[0028] Specifically, this product adopts a split structure where the upper valve body 12 and lower valve body 13 are detachably connected by bolts. The upper and lower valve bodies together form a complete valve cavity 11. Compared with the traditional integral valve body structure, the assembly process is more flexible. During the production and assembly process, the lined valve seat 15 can be easily placed into the valve cavity 11 and made to fit tightly against the inner wall of the valve cavity 11. Then, the upper valve body 12 and lower valve body 13 are locked together by bolts, which greatly reduces the assembly difficulty of the lined valve seat 15 and effectively avoids problems such as misalignment, poor fit, and lining damage that are prone to occur when installing the lining of an integral valve body. At the same time, the split valve body structure has extremely convenient operation and maintenance. During the later maintenance of the equipment, there is no need to disassemble the entire valve and pipeline structure. Only the connecting bolts need to be loosened to separate the upper valve body 12 and lower valve body 13. The easily damaged fluoropolymer-lined components such as the lined valve seat 15 and valve plate 2 inside the valve cavity 11 can be quickly inspected, repaired, or replaced individually. There is no need to replace the entire valve, which significantly reduces the equipment operation and maintenance costs and downtime losses.

[0029] The lined valve seat 15 is fully abutted against and limited by the inner wall of the valve cavity 11. The overall structure of the valve body can provide all-round stable support and limitation for the lined valve seat 15. Under the conditions of high pressure scouring and fluid impact of pipeline medium, it can effectively limit the bulging, displacement, detachment and deformation of the lined valve seat 15, ensure the structural stability of the sealing fit between the lined valve seat 15 and the valve plate 2, ensure the basic sealing performance of the valve for long-term operation, and adapt to various corrosive media transportation conditions.

[0030] In this embodiment, a corrosion-resistant fluoroplastic packing sealing assembly is provided at the through-hole position between the upper valve body 12 and the valve stem 3. The corrosion-resistant fluoroplastic packing sealing assembly includes one or more of the following: gland 14, PTFE packing 16, sealing ring 18, spring washer 17, and valve stem sleeve 19.

[0031] Specifically, a packing installation groove is provided at the vertical through-fitting position between the upper valve body 12 and the valve stem 3. The packing installation groove is equipped with a sealing ring 18, a spring washer 17 and PTFE packing 16 in sequence from the inside to the outside. A pressure cap 14 is fitted at the port of the packing installation groove. The PTFE packing 16 tightly wraps around the outer periphery of the valve stem 3, serving as the main sealing filling layer within the mating gap between the valve stem 3 and the upper valve body 12. The spring washer 17 is fitted onto the outer end face of the PTFE packing 16, providing continuous elastic tightening. The sealing ring 18 is embedded in the inner root of the packing groove, sealing the inner gap between the valve stem 3 and the upper valve body 12, achieving the first layer of sealing protection. The gland 14 is locked and fixed to the top of the upper valve body 12 by fasteners, axially pressing the entire set of anti-corrosion fluoroplastic packing sealing components, ensuring that each sealing component fits tightly without assembly gaps, forming a multi-layer composite sealing structure that completely covers the rotational mating area between the valve stem and the upper valve body. The valve plate must be completely wrapped in fluoroplastic to ensure that the pipeline medium does not come into contact with the metal parts.

[0032] Installation process: The valve plate 2 and valve stem 3 are welded and fixed to form a whole, and then completely wrapped with fluoroplastic. The valve stem 3 is first inserted into the "valve stem hole" on the valve seat, and then the valve seat is squeezed to deform it, and the valve plate is embedded as a whole.

[0033] The PTFE packing block is inserted into the gap between the valve plate 2 and the upper end of the valve seat. The PTFE packing block has a wedge-shaped design, and the pressure from above creates a squeezing force on the inner and outer walls, thereby eliminating the tolerance gap (the upper and lower valve stem parts are exactly the same). The valve stem sleeve 19 provides downward pressure to the PTFE packing block, and the gland 14 provides downward pressure to the valve stem sleeve 19. The gland 14 is connected to the valve body by screws and has sufficient clearance to allow the user to apply secondary pressure during use to enhance the sealing effect. The lining valve seat 15 is inserted into the inner cavity of the lower valve body 13, ensuring that the outer wall of the lining valve seat 15 fits snugly against the inner wall of the valve cavity of the lower valve body 13, guaranteeing that the lining valve seat 15 is placed upright, without offset or wrinkles. Then, the upper valve body 12 is aligned and fastened above the lower valve body 13, so that the upper valve body 12 and lower valve body 13 together form a complete valve cavity 11. Simultaneously, the lining valve seat 15 is completely fitted against the inner wall of the valve cavity 11. The lining valve seat 15 is thus individually positioned by the clamping of the upper and lower valve bodies, completing the initial pre-assembly positioning of the valve body and the lining valve seat 15. Finally, the screws on both sides of the valve body are tightened to complete the assembly.

[0034] This invention detachably connects the upper valve body 12 and the lower valve body 13 together with bolts. By offsetting the valve stem 3 axis from the center of the valve plate 2 sealing surface and the valve stem 3 axis from the center of the valve cavity channel, it replaces the valve body structure of the existing butterfly valve that directly passes through the centerline. This invention can solve the problem of excessive friction between the valve plate and the valve seat when opening and closing, greatly extending the service life of the PTFE-lined butterfly valve and greatly reducing the operating torque. It can use a relatively small actuator, saves installation space, and makes it more convenient for users.

[0035] Example 2: To ensure rapid disengagement from the valve seat sealing surface within a small turning range, significantly shorten the friction stroke of the sealing surface, and effectively reduce opening and closing wear, existing double eccentric butterfly valves are designed with axial and radial eccentricity.

[0036] While this significantly shortens the friction stroke of the sealing surface, the following problems still exist: In the last segment of the valve closing stroke, the butterfly plate sealing surface rapidly transitions from the initial contact state to the designed interference seal state. The contact pressure of the sealing pair increases exponentially as the rotation angle decreases, and the valve closing torque rises sharply with the contact stress, forming a significant valve closing torque peak. In the initial segment of the valve opening stroke, the actuator must simultaneously overcome the maximum static friction of the sealing surface, the axial thrust torque generated by the medium pressure difference, and the squeezing resistance caused by the interference seal. The valve opening torque reaches its maximum value throughout the entire stroke, forming the valve opening torque peak.

[0037] Therefore, this embodiment has been improved based on embodiment 1 as follows, such as... Figures 5-12 As shown, the outer casing 4 is located on top of the valve stem 3 and is fixedly connected to the valve body 1. The working chamber 43 is located inside the outer casing 4. A first force-saving structure is located inside the working chamber 43 to save valve opening torque. A second force-saving structure is located inside the working chamber 43 to save valve closing torque. A switching structure is located inside the working chamber 43 to activate the first force-saving structure and close the second force-saving structure during the valve opening stroke when the valve stem 3 rotation angle automatically switches, or to activate the second force-saving structure and close the first force-saving structure during valve closing.

[0038] Specifically, the present invention sets up a first labor-saving structure and a second labor-saving structure to adapt to the valve opening and closing conditions respectively, and configures a switching structure to automatically realize the two labor-saving mechanisms working in turn as the valve stem 3 rotates; when the valve is opened, the first labor-saving structure is activated and the second labor-saving structure is shut down; when the valve is closed, the second labor-saving structure is activated and the first labor-saving structure is shut down. The two sets of power-assisting mechanisms do not interfere with each other and can respectively match the asymmetrical opening and closing torque of the butterfly valve; the whole is purely mechanically driven, requiring no electrical control, and the modular layout facilitates assembly and modification, while reducing wear of the mechanism in non-working state and steadily reducing the valve opening and closing torque; the fluoroplastic anti-corrosion layer set on the inner wall of the valve cavity 11 and the valve plate 2 can isolate corrosive fluids from contact with the metal substrate, effectively preventing corrosion of the valve body 1 and the valve plate 2, and extending the overall service life of the valve; the low coefficient of friction of fluoroplastics can reduce the frictional resistance during the rotation of the valve plate, reduce the basic opening and closing torque, reduce the load on the force-saving structure, and reduce the wear of moving parts such as cams, gears, and sliding frames; at the same time, fluoroplastics do not easily adhere to media impurities, which can prevent scale buildup and jamming of the valve plate in the valve cavity; and can prevent metal debris generated by corrosion from entering the upper working chamber, preventing debris from interfering with the movement of the first force-saving structure, the second force-saving structure, and the switching structure, ensuring the stable and reliable automatic time-sharing switching action of the two sets of force-saving mechanisms; in addition, the fluoroplastic layer can optimize the valve plate sealing surface fit effect, reduce media leakage, and improve the valve sealing stability.

[0039] The first labor-saving structure in this embodiment includes a first gear 71, a sliding frame 6 which is slidably connected to the working cavity 43, the first gear 71 and the sliding frame 6 are rotatably connected, a rotating disk 31 is fixedly mounted on the valve stem 3, a plurality of connecting columns 32 are fixedly mounted on the rotating disk 31, the first gear 71 meshes with the connecting columns 32, a first cam 711 is fixedly mounted on the first gear 71, and a first labor-saving component 713 is mounted on the sliding frame 6 and abuts against the first cam 711.

[0040] Specifically, the valve stem 3 drives the first gear 71 to rotate through the meshing of the rotating disk 31 and the connecting column 32, which in turn drives the integrated first cam 711 to move synchronously. The cam squeezes the first force-saving component 713 to complete the energy storage and release, realizing the valve opening assistance torque reduction. The first gear 71 is installed on the sliding frame 6 and can move with the sliding frame 6 to achieve meshing and disengagement, which facilitates the switching of the mechanism on and off. The timing of the power assist output can be flexibly adjusted by means of the cam profile. The gear meshing transmission is smooth and reliable. The whole set of components has good pre-assembly and strong environmental adaptability.

[0041] In this embodiment, the roller 714 is rotatably mounted on the first force-saving component 713, and the roller 714 rolls against the first cam 711. The sliding component 712 is fixedly mounted on the sliding frame 6, and the first sliding groove 715 is disposed in the sliding component 712. The first force-saving component 713 is slidably connected to the first sliding groove 715. The first limiting spring 716 is disposed in the first sliding groove 715, and the two ends of the first limiting spring 716 are fixedly connected to the first sliding groove 715 and the first force-saving component 713, respectively. The cross-section of the first sliding groove 715 is a "square" structure.

[0042] Specifically, in this embodiment, a roller 714 is rotatably installed at the end of the first force-saving component 713, changing the traditional sliding friction contact between the first cam 711 and the first force-saving component 713 to a rolling abutment fit. This greatly reduces the frictional resistance and wear during the cam's rotation and pushing of the force-saving component, effectively reducing the risk of mechanical jamming and stagnation, improving the smoothness and stability of the force-saving mechanism's operation, and significantly extending the service life of the cam and the force-saving component, thus reducing the long-term maintenance costs of the equipment. By setting a first sliding groove 715 inside the sliding component 712, the first force-saving component 713 is oriented and slidably assembled, providing a dedicated motion track for the telescopic energy storage action of the force-saving component. This effectively restricts the degree of freedom of movement of the first force-saving component 713, ensuring that the force-saving component can only perform linear reciprocating motion along the axis of the sliding groove, eliminating the problems of force offset, skew, and jamming of the force-saving component, ensuring precise and controllable spring energy storage and release actions, and guaranteeing valve opening efficiency. Stable torque output; the first sliding groove 715 adopts a square cross-section structure, which can achieve all-round anti-rotation limit compared with the circular sliding groove, and can completely avoid the circumferential rotation of the first force-saving component 713 during the force-sliding process. It ensures that the roller 714 at the end of the force-saving component always maintains a positive and close contact with the contour of the first cam 711, and there will be no misalignment, uneven wear, or uneven force. It greatly improves the cam transmission matching accuracy and ensures that the force-saving mechanism works efficiently throughout the process. The first limiting spring 716 is built into the first sliding groove 715, and the two ends of the spring are fixedly connected to the sliding groove and the sliding component 712 respectively. The assembly structure is compact and integrated, and no additional external fixing structure is required. It realizes the elastic energy storage during the cam extrusion process and the automatic reset function after the valve opens and closes. It also effectively saves the internal space of the working chamber 43 of the outer shell 4, making the overall mechanism structure more compact and adaptable to the arrangement requirements of the narrow installation space of the valve top.

[0043] The second force-saving structure in this embodiment includes a second gear 72, which is rotatably connected to the sliding frame 6 and meshes with the connecting column 32. A second cam 721 is fixedly mounted on the second gear 72. A second force-saving component 722 is mounted on the sliding frame 6 and abuts against the second cam 721. The second force-saving component 722 has the same structure as the first force-saving component 713.

[0044] Specifically, this embodiment features a second force-saving structure adapted to the valve-closing operation. Through the cooperation of the second gear 72, the second cam 721, and the second force-saving component 722, it specifically reduces torque during the valve-closing stroke of the double eccentric butterfly valve. This structure is independent of and has a clear division of labor with the first force-saving structure used for valve-opening. It solves the problem that traditional single-unit force-saving mechanisms cannot accommodate the asymmetrical opening and closing torque of the valve. It can specifically match the resistance characteristics of the valve-closing process, significantly optimizing the ease of butterfly valve operation. The second gear 72 is rotatably mounted on the sliding frame 6 and can stably mesh with the connecting column 32 of the rotating disk 31. It can accurately engage and disengage following the displacement of the sliding frame 6, and in conjunction with the overall switching structure, automatically engages during the valve-closing stroke and automatically exits dormancy during the valve-opening stroke. The mechanical linkage switching is precise and reliable, requiring no manual intervention or electronic control assistance. It can achieve independent assistance throughout the valve opening and closing process, eliminating torque cancellation and motion interference problems caused by the simultaneous operation of two sets of labor-saving mechanisms. The second gear 72 and the second cam 721 are rigidly fixed and can rotate synchronously. The cam profile precisely compresses the second labor-saving component 722 to complete the energy storage and release actions. It can optimize the cam curve according to the valve closing resistance change law, and precisely control the output timing and output torque of the valve closing assistance. It is suitable for the working condition of high sealing and pressing resistance at the end of the double eccentric butterfly valve closure, effectively reducing the peak torque of valve closing operation and improving the stability of valve sealing and closing.

[0045] In this embodiment, the first cam 711 and the second cam 721 have the same shape, and the angle between the first cam 711 and the second cam 721 is 90°.

[0046] Specifically, in this embodiment, the first cam 711 and the second cam 721 are completely identical in shape and contour structure, ensuring that the energy storage and release motion laws and mechanical output characteristics of the first and second force-saving structures are consistent. The components are of universal structure and have consistent processing standards, enabling batch interchangeable production of cam parts. This effectively reduces mold development, machining, and component inventory costs, while simplifying the overall assembly and debugging process, improving product assembly consistency and mass production efficiency. The maximum working stroke phase angle of the two cams is set to 90°, precisely matching the standard opening and closing angle stroke of the double eccentric butterfly valve from 0° to 90°, ensuring that the working range of the first cam 711 is strictly controlled. The first cam corresponds to the valve opening stroke, and the second cam 721's working range strictly corresponds to the valve closing stroke. This ensures that the timing of the two sets of force-saving mechanisms is precisely aligned with the valve opening and closing conditions, guaranteeing accurate timing of assistance and eliminating problems of delayed or premature assistance failure. Relying on the staggered layout with a 90° phase difference, it can be ensured that only one set of cams is in an effective working state within a single valve opening and closing stroke, while the other set of cams is in an idle standby state. From a structural phase perspective, this completely avoids the situation where two sets of cams and two sets of force-saving mechanisms are working simultaneously, completely avoiding the defects of mutual interference, cancellation, or even mechanism jamming of bidirectional assistance torques, and greatly improving the stability and reliability of the mechanism's operation.

[0047] In this embodiment, the first reset member 81 and the second reset member 82 are disposed on the sliding frame 6. The reset cavity 811 is disposed inside the first reset member 81. The rotating shaft 7111 is fixedly disposed on the first cam 711. The first locking block 7112 is fixedly disposed on the rotating shaft 7111. The second locking block 812 is fixedly disposed on the inner wall of the reset cavity 811. The reset spring is wound around the rotating shaft 7111. The two ends of the reset spring are fixedly connected to the first locking block 7112 and the second locking block 812 respectively. The first reset member 81 and the second reset member 82 have the same structure.

[0048] Specifically, in this embodiment, a first reset member 81 and a second reset member 82 with identical structures are provided on the sliding frame 6, respectively corresponding to the independent reset of the first cam 711 and the second cam 721, so that both sets of force-saving mechanisms can achieve independent reset actions without interfering with each other. Compared with a single reset structure, this structure can ensure that the cam mechanisms corresponding to the valve opening and closing are accurately returned to their positions after each work, completely solving the problems of cam angle deviation, incomplete reset causing misalignment of force-saving timing and failure of assist, and ensuring the accuracy of long-term cyclic operation of the bidirectional force-saving mechanism; by using the rotating shaft 7111, the first locking block 7112, and the second locking block 812 in conjunction with the limiting and fixing of the reset spring, the reset spring is wound around the outer circumference of the rotating shaft 7111, and the reset cavity 811 is used to completely wrap and protect the spring. The structure layout is compact and reasonable, making full use of the internal space of the sliding frame 6 without occupying the spare space of the working cavity 43, effectively improving The overall mechanism is highly integrated, meeting the assembly requirements of the narrow space on the valve top, while avoiding the problem of external springs being easily deformed by collisions. The snap-lock spring connection structure ensures that the two ends of the return spring are rigidly limited and fixed to the rotating shaft 7111 and the inner wall of the return cavity 811, respectively. There is no slippage or uncoiling during the spring's stretching and retraction, and the force is uniform and stable. It can continuously provide a constant return torque to the cam rotating shaft 7111, ensuring that the cam can quickly and accurately return to the initial reference phase after each work. This ensures that the cam profile and the force-saving roller 714 are precisely matched during the next opening and closing action, guaranteeing a high degree of consistency in the force-saving effect for each opening and closing action.

[0049] The switching structure in this embodiment includes a third gear 61, on which a rotating rod 34 is fixed. The rotating rod 34 is sleeved inside the valve stem 3 and rotatably connected to the valve stem 3. A first limiting protrusion 341 is fixed on the rotating rod 34, and a second limiting protrusion 35 is fixed on the valve stem 3. The first limiting protrusion 341 and the second limiting protrusion 35 abut against each other. A sliding rack 611 is fixed on the sliding frame 6. The sliding rack 611 meshes with the third gear 61. A sliding notch 64 is provided at the top of the sliding frame 6. The third gear 61 passes through the sliding notch 64. A first limiting block 62 and a second limiting block 63 are fixed on both sides of the sliding rack 611 at the top of the sliding frame 6.

[0050] Specifically, in this embodiment, a gear and rack meshing switching method is adopted, in which the valve stem 3 is fixedly connected to the third gear 61 and the sliding frame 6 is fixedly connected to the sliding rack 611, which can accurately convert the rotational motion of the valve stem 3 into the linear sliding motion of the sliding frame 6. The entire process relies on the valve's own opening and closing action to complete the mechanism switching, without the need for an additional independent drive source, electrical control induction, or manual intervention. It achieves fully automatic switching of the valve opening and closing strokes corresponding to the labor-saving mechanism, with reliable structural linkage and synchronous response, adaptable to various industrial automation and manual opening and closing conditions. By setting a sliding notch 64 on the top of the sliding frame 6, the third gear 61 is arranged through the notch, effectively utilizing the top space of the sliding frame 6 to achieve gear and rack embedded meshing. The overall structure is nested and integrated with a compact layout, eliminating the need for additional transmission clearance space, greatly improving the internal structural integration of the working chamber 43, adapting to the narrow installation space on the valve top, and avoiding the problems of bulky size and easy damage caused by external transmission structure. The first limit block 62 and the second limit block 63 are fixed on both sides of the sliding rack 611, respectively, which can mechanically limit the left and right sliding stroke of the sliding frame 6, precisely limiting the maximum movement distance of the sliding frame 6, effectively avoiding problems such as excessive gear meshing, tooth disengagement, collision and jamming caused by the sliding frame 6 exceeding its sliding range. This ensures that each switching action can accurately stop at the preset position, ensuring that the first force-saving structure is fully engaged and the second force-saving structure is fully disengaged when the valve is opened, and vice versa when the valve is closed, thus preventing torque interference faults caused by incomplete switching of the mechanism; in this embodiment, a first limiting protrusion 341 is fixed on the rotating rod 34 and a second limiting protrusion 35 is fixed on the valve stem 3, ensuring that the rotating rod 34 will not drive the valve stem 3 to rotate during the switching phase.

[0051] In this embodiment, the first limiting groove 621 and the second limiting groove 631 are disposed within the first limiting block 62 and the second limiting block 63. A second limiting spring 622 is fixed in the first limiting groove 621, and a third limiting spring 632 is fixed in the second limiting groove 631. The sliding stroke of the sliding rack 611 is less than the distance between the first limiting groove 621 and the third gear 61.

[0052] Specifically, in this embodiment, a first limiting groove 621 and a second limiting groove 631 are correspondingly provided inside the first limiting block 62 and the second limiting block 63, respectively, and matching limiting springs are built in each. When the sliding frame 6 reaches the extreme sliding position, the springs can achieve flexible buffering and limiting. This changes the traditional rigid hard-limit contact method, effectively absorbing the impact kinetic energy during the reversing and starting / stopping process of the sliding frame 6, greatly reducing the impact wear of gears, racks, and the sliding frame 6, avoiding problems such as part deformation, broken teeth, and loosening due to long-term reciprocating switching, and significantly improving the service life and operational stability of the mechanism. The structure layout of the double limiting grooves with independently built-in springs can achieve buffering and shock absorption at the two extreme sliding positions of the sliding frame 6, so that the switching process of the mechanism corresponding to opening and closing the valve has a flexible buffering effect. The limiting force on both sides is uniform and the buffering performance is consistent, completely solving the problem of uneven wear on one side of the limiting and the mechanism deviation and deviation, and ensuring the straightness and alignment accuracy of the sliding frame 6 during long-term reciprocating sliding.

[0053] In this embodiment, the outer shell 4 is also provided with a knob groove 41, in which a knob switch 5 is slidably connected. A third limiting groove 33 is provided on the top of the rotating rod 34. The cross-section of the third limiting groove 33 is circular. A slot 331 is provided on the inner wall of the third limiting groove 33. A first locking pin 51 is fixedly provided on the knob switch 5. The knob switch 5 is slidably connected to the third limiting groove 33, and the first locking pin 51 is inserted into the slot 331.

[0054] Specifically, in this embodiment, a knob groove 41 is provided on the outer shell 4, and a knob switch 5 is slidably assembled thereon. This, together with the third limiting groove 33 on the top of the rotating rod 34, forms an integrated manual locking structure. The overall structure is compact, requiring no additional external locking accessories. Mechanical locking of the valve opening and closing angle can be achieved directly at the valve top position. The structure is simple and easy to operate, effectively solving the problem of traditional butterfly valves lacking a locking structure and being susceptible to self-rotation and offset due to medium pressure difference and pipeline vibration after opening and closing. The third limiting groove 33 with a circular cross-section is provided on the top of the rotating rod 34, which can accommodate the axial sliding and circumferential rotation of the knob switch 5, ensuring smooth and unhindered operation of the knob switch 5. Meanwhile, the circular groove structure distributes stress evenly, effectively preventing localized wear and deformation caused by long-term insertion, removal, and rotation operations, thus improving the assembly accuracy and service life of the overall locking structure. A slot 331 is provided on the inner circumference of the third limiting groove 33, which, in conjunction with the first locking pin 51 fixed on the rotary switch 5, achieves circumferential limiting and locking of the rotary switch 5 and the rotating rod 34. The insertion and engagement structure has high positioning accuracy and strong locking rigidity, completely restricting the free rotation of the rotating rod 34, ensuring stable locking of the valve in fully open, fully closed, or any adjusted opening position. This effectively guarantees the stability of the valve's working state under pipeline conditions and prevents malfunctions caused by medium pressure fluctuations.

[0055] In this embodiment, the limiting structure is set between the outer shell 4 and the rotary switch 5. The limiting structure includes a fourth limiting spring 52, a positioning member 42 fixedly set on the outer shell 4, a positioning groove 421 set on the positioning member 42, the positioning groove 421 having a "+" shaped structure, a second locking pin 53 set on both sides of the rotary switch 5, the second locking pin 53 being inserted into the positioning groove 421, and a third limiting spring 632 sleeved on the rotary switch 5, the two ends of the third limiting spring 632 being fixedly connected to the second locking pin 53 and the top of the rotating rod 34, respectively.

[0056] Specifically, in this embodiment, a dedicated limiting structure is added between the outer shell 4 and the rotary switch 5. This structure, along with the cross-shaped positioning groove 421, the second locking pin 53, and the limiting spring, forms a composite positioning and locking mechanism. This mechanism can precisely limit and fix the unlocking and locking positions of the rotary switch 5, effectively solving the problems of loosening, disengagement, and mis-locking caused by vibration or external force in traditional rotary locking structures. This further improves the stability and safety of valve angle locking. The positioning component 42 adopts a cross-shaped positioning groove 421 structure. Compared to the conventional straight positioning groove 421, this structure enables bidirectional precise positioning of the rotary switch 5's locking position, stably adapting to the locking requirements of the two core working positions of the valve: fully open and fully closed. This provides a wider positioning dimension. The device offers higher limiting accuracy, effectively restricting the circumferential rotation and radial offset of the rotary switch 5, preventing wobbling and displacement of the switch when locked. Symmetrical second locking pins 53 on both sides of the rotary switch 5 engage with the cross-shaped positioning groove 421, forming a double-sided symmetrical limiting structure. This ensures even and symmetrical force distribution, avoiding wear, deformation, and jamming caused by uneven force on one side of the locking pins. This significantly improves the structural strength and service life of the positioning connection structure, ensuring accurate positioning even after frequent locking and unlocking operations. A limiting spring is sleeved on the outside of the rotary switch 5, with its ends fixed to the second locking pins 53 and the top of the rotating rod 34, respectively. The spring force continuously provides axial clamping force to the rotary switch 5. In the locked state, the second locking pins 53 remain tightly engaged inside the positioning groove 421, preventing vibration-induced dislodgement. After unlocking and pulling, the rotary switch 5 automatically resets due to spring force, making operation convenient and effortless, with stable and reliable limiting and reset actions.

[0057] The installation process of this embodiment is as follows: Valve plate 2 is fully closed (valve stem 30°): Valve stem 3 is kept at 0° position, the pressure of the pipeline medium acts on valve plate 2, generating a large opening resistance torque; the third gear 61 fixed to valve stem 3 is in the initial position, driving the sliding rack 611 to make the sliding frame 6 stay at one extreme position; the second gear 72 on the sliding frame 6 is engaged with the connecting column 32 on the rotating disk 31, and the second force-saving structure is in a standby energy storage state; the first gear 71 is disengaged from the connecting column 32, and the first force-saving structure does not participate in the transmission; the second cam 721 contacts the roller 714 of the second force-saving component 722, and the return spring maintains the initial phase of the cam; the locking pin of the external rotary switch 5 is engaged in the valve stem 3 slot 331, mechanically locking the valve stem 3 and preventing it from rotating.

[0058] Valve opening action (valve stem 3 from 0°→90°, from fully closed to fully open): Press down to release the lock of knob switch 5, rotate rotating rod 34 in the forward direction; rotating rod 34 drives rotating disk 31 and third gear 61 to rotate synchronously in the same direction; third gear 61 meshes with sliding rack 611, pushing sliding frame 6 to slide smoothly laterally along working chamber 43; during the movement of sliding frame 6: second gear 72 moves with sliding frame 6, gradually disengaging from connecting column 32, and the second force-saving structure exits work; at the same time, first gear 71 approaches connecting column 32 and completes meshing, automatically completing mechanism switching; at this time, first limiting protrusion 341 abuts against second limiting protrusion 35; rotating rod 34 drives valve stem 3 to continue rotating; connecting column 32 on rotating disk 31 carries The first gear 71 rotates, and the first gear 71 synchronously drives the first cam 711 to rotate. The contour of the first cam 711 presses against the roller 714, pushing the first force-saving component 713 to slide in the first sliding groove 715 of the sliding component 712, compressing the first limiting spring 716. The first limiting spring 716 continuously stores energy. When it rotates to the critical angle for opening the valve, the first limiting spring 716 releases its elastic force, and applies a reverse torque to the first cam 711 through the roller 714. The torque is transmitted to the rotating disk 31 and the valve stem 3 through the first gear 71 and the connecting column 32, which counteracts the valve opening resistance torque generated by the medium, thus achieving effortless valve opening. The valve stem 3 continues to rotate until it reaches 90°, and the valve plate 2 is fully open. At this time, the first cam 711 rotates to the maximum stroke position. At this time, the first gear 71 remains engaged, and the first force-saving structure completes the energy release cycle; the second gear 72 is completely disengaged, and the energy is stored by relying on the return spring; when the pressure knob switch 5 is released, the locking pin cooperates with the cross positioning groove 421 to achieve the fully open position locking, and the return spring of the first cam 711 maintains the initial relative position of the cam, preparing for the phase reset for the subsequent valve closing action.

[0059] Valve closing action (valve stem 3 changes from 90° to 0°, from fully open to fully closed): Press down to release the lock of knob switch 5, and rotate rotating rod 34 in the opposite direction; rotating rod 34 drives third gear 61 to rotate in the opposite direction; third gear 61 drives sliding rack 611, driving sliding frame 6 to slide and reset in the opposite direction; during the movement of sliding frame 6: first gear 71 gradually disengages from connecting column 32, and the first force-saving structure goes into dormancy; second gear 72 re-engages with connecting column 32, completing the reverse switching of the mechanism. At this time, the first limiting protrusion 341 and the second... The limiting protrusion 35 abuts; the rotating rod 34 drives the valve stem 3 to continue rotating; the rotating disk 31 rotates synchronously with the valve stem 3, and the connecting column 32 drives the second gear 72 and the second cam 721 to rotate synchronously; the second cam 721 squeezes the second force-saving component 722 roller 714, compressing the internal spring to store energy; when the critical angle of valve closure is reached, the spring releases its elastic force, outputting auxiliary torque to offset the medium's resistance torque in closing the valve and reduce the valve closure operating torque; the valve stem 3 continues to rotate to 0°, and the valve plate 2 re-seals and closes; the second cam 721 completes its working stroke.

[0060] The present invention provides a valve stem 3 on a valve body 1, and an outer shell 4 on the valve stem 3. The outer shell 4 contains a first force-saving structure that saves valve opening torque and a second force-saving structure that saves valve closing torque. By switching between these structures, the force-saving states for opening and closing the valve can be switched, replacing the prior art which directly achieves valve opening and closing operations by rotating the valve stem 3. The present invention can ensure that opening and closing the valve is more labor-saving and has strong practicality.

[0061] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this application, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, they are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0062] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A fluoropolymer-lined double eccentric butterfly valve, comprising an upper valve body (12) and a lower valve body (13), characterized in that, The upper valve body (12) and the lower valve body (13) are detachably connected by bolts. The upper valve body (12) and the lower valve body (13) together form a valve cavity (11). A lined valve seat (15) is provided in the valve cavity (11). The lined valve seat (15) abuts against the inner wall of the valve cavity (11). A valve stem (3) is rotatably connected in the valve cavity (11). A valve plate (2) is welded and fixed on the valve stem (3). The axis of the valve stem (3) is offset from the center of the sealing surface of the valve plate (2). The axis of the valve stem (3) is offset from the center of the channel of the valve cavity (11).

2. The fluoropolymer-lined double eccentric butterfly valve according to claim 1, characterized in that, A corrosion-resistant fluoroplastic packing sealing assembly is provided at the through position between the upper valve body (12) and the valve stem (3). The corrosion-resistant fluoroplastic packing sealing assembly includes one or more of the following: gland (14), PTFE packing (16), sealing ring (18), spring washer (17), and valve stem sleeve (19). A sealing layer (21) is wrapped on the valve plate (2), and the sealing layer (21) is fluoroplastic.

3. The fluoropolymer-lined double eccentric butterfly valve according to claim 1, characterized in that, The valve stem (3) is provided with an outer shell (4) at the top. The outer shell (4) is fixedly connected to the upper valve body (1). The outer shell (4) is provided with a working chamber (43). The working chamber (43) is provided with a first force-saving structure for saving valve opening torque. The working chamber (43) is also provided with a second force-saving structure for saving valve closing torque. The working chamber (43) is also provided with a switching structure for activating the first force-saving structure and closing the second force-saving structure when the valve stem (3) rotation angle is automatically switched, or activating the second force-saving structure and closing the first force-saving structure when the valve is closed.

4. A fluoropolymer-lined double eccentric butterfly valve according to claim 3, characterized in that, The first labor-saving structure includes a first gear (71), a sliding frame (6) is slidably connected in the working cavity (43), the first gear (71) is rotatably connected to the sliding frame (6), a rotating disk (31) is fixed on the valve stem (3), a plurality of connecting columns (32) are fixed on the rotating disk (31), the first gear (71) meshes with the connecting columns (32), a first cam (711) is also fixed on the first gear (71), the sliding frame (6) is provided with a first labor-saving component (713), and the first labor-saving component (713) abuts against the first cam (711).

5. A fluoropolymer-lined double eccentric butterfly valve according to claim 4, characterized in that, A roller (714) is rotatably connected to the first labor-saving component (713). The roller (714) rolls against the first cam (711). A sliding component (712) is fixed on the sliding frame (6). A first sliding groove (715) is provided in the sliding component (712). The first labor-saving component (713) is slidably connected to the first sliding groove (715). A first limiting spring (716) is provided in the first sliding groove (715). The two ends of the first limiting spring (716) are fixedly connected to the first sliding groove (715) and the first labor-saving component (713) respectively. The cross-section of the first sliding groove (715) is a "square" structure.

6. A fluoropolymer-lined double eccentric butterfly valve according to claim 5, characterized in that, The second force-saving structure includes a second gear (72), which is rotatably connected to the sliding frame (6). The second gear (72) meshes with the connecting column (32). A second cam (721) is also fixed on the second gear (72). A second force-saving component (722) is also provided on the sliding frame (6). The second force-saving component (722) abuts against the second cam (721). The second force-saving component (722) has the same structure as the first force-saving component (713). The first cam (711) and the second cam (721) have the same shape. The angle between the first cam (711) and the second cam (721) is 90°.

7. A fluoropolymer-lined double eccentric butterfly valve according to claim 4, characterized in that, The sliding frame (6) is provided with a first reset component (81) and a second reset component (82). The first reset component (81) is provided with a reset cavity (811). A rotating shaft (7111) is fixed on the first cam (711). A first locking block (7112) is fixed on the rotating shaft (7111). A second locking block (812) is fixed on the inner wall of the reset cavity (811). A reset spring (813) is wound on the rotating shaft (7111). The two ends of the reset spring (813) are fixedly connected to the first locking block (7112) and the second locking block (812) respectively. The first reset component (81) and the second reset component (82) have the same structure.

8. A fluoropolymer-lined double eccentric butterfly valve according to claim 3, characterized in that, The switching structure includes a third gear (61), on which a rotating rod (34) is fixed. The rotating rod (34) is sleeved inside the valve stem (3) and rotatably connected to the valve stem (3). A first limiting protrusion (341) is fixed on the rotating rod (34), and a second limiting protrusion (35) is fixed on the valve stem (3). The first limiting protrusion (341) and the second limiting protrusion (35) abut against each other. A sliding rack (611) is fixed on the sliding frame (6), and the sliding rack (611) meshes with the third gear (61). A sliding notch (64) is provided at the top of the sliding frame (6), through which the third gear (61) passes. A first limiting block (62) and a second limiting block (63) are fixed on both sides of the sliding rack (611) at the top of the sliding frame (6).

9. A fluoropolymer-lined double eccentric butterfly valve according to claim 8, characterized in that, The first limiting block (62) and the second limiting block (63) are respectively provided with a first limiting groove (621) and a second limiting groove (631). A second limiting spring (622) is fixed in the first limiting groove (621) and a third limiting spring (632) is fixed in the second limiting groove (631). The sliding stroke of the sliding rack (611) is less than the distance between the first limiting groove (621) and the third gear (61).

10. A fluoropolymer-lined double eccentric butterfly valve according to claim 9, characterized in that, The outer casing (4) is also provided with a knob groove (41), and a rotary switch (5) is slidably connected in the knob groove (41). The top of the rotating rod (34) is provided with a third limiting groove (33). The cross-section of the third limiting groove (33) is circular. A slot (331) is provided on the inner wall of the third limiting groove (33). A first locking pin (51) is fixed on the rotary switch (5). The rotary switch (5) is slidably connected to the third limiting groove (33). The first locking pin (51) is inserted into the slot (331). The outer casing (4) and the rotary switch (5) are connected. A limiting structure is also provided, the limiting structure includes a fourth limiting spring (52), a positioning component (42) is fixed on the outer shell (4), the positioning component (42) is provided with a positioning groove (421), the positioning groove (421) is a "+" shaped structure, the knob switch (5) is also provided with a second locking pin (53) on both sides, the second locking pin (53) is inserted into the positioning groove (421), the fourth limiting spring (52) is sleeved on the knob switch (5), and the two ends of the fourth limiting spring (52) are fixedly connected to the second locking pin (53) and the top of the rotating rod (34) respectively.

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