Positioner and limit switch linkage device for valve

Abstract

The invention relates to a positioner and limit switch linkage device for a valve. The storage box comprises a long-strip-shaped storage box body, a first mounting part, at least one middle mounting part and a second mounting part are sequentially arranged in the length direction of the storage box body, and the storage box body further comprises a first fixing part, a second fixing part and a third fixing part; the transmission assembly comprises a first transmission shaft, a middle transmission shaft and a second transmission shaft which are correspondingly and rotationally connected to the placement box through a first mounting part, a middle mounting part and a second mounting part; the actuator is mounted on the outer end face of the placement box through a first fixing part; the positioner is mounted on the outer end face of the placement box through a second fixing part; and the first end of the second transmission shaft is connected with a rotating shaft of the limiting switch through a third connecting interface. When the valve is in an emergency, the valve can be rapidly placed at the safety switch position, the state of the valve is displayed through the limiting switch, and the overall safety of the system is improved.

Description

Technical Field

[0001] The invention relates to the technical field of valves, and in particular to a positioner and limit switch linkage device for valves. Background Art

[0002] At present, the use of valves has been deeply integrated into people's daily lives. Various types of valves, such as gate valves, ball valves, butterfly valves and regulating valves, are widely used in many occasions. Due to differences in valve installation locations and operating conditions, some valves need to be equipped with limit switches, an electronic component. By connecting to the limit switch, its feedback signal can be received on the control device, so as to intuitively understand the switch status of the valve.

[0003] When the valve needs to meet the requirements of parameters such as pressure, temperature or flow rate after the valve, it is usually necessary to use a positioner to adjust the valve opening. However, there is no special adaptation solution for pneumatic actuators. How to effectively link the positioner and limit switch of the pneumatic actuator to intuitively monitor the valve status has become a key issue that needs to be solved urgently. Summary of the invention

[0004] To this end, the present invention provides a positioner and limit switch linkage device with good linkage effect, easy installation and convenient replacement. The linkage device adopts an integral box-type design, and all components are fixed in the placement box, which greatly reduces the difficulty of installation and improves the convenience of spare parts storage and replacement.

[0005] In order to solve the above technical problems, the present invention provides a positioner and limit switch linkage device for a valve, comprising: The placement box is in the shape of an elongated strip, and a first installation portion, at least one intermediate installation portion and a second installation portion are sequentially arranged along the length direction of the placement box, and the placement box further comprises a first fixing portion, a second fixing portion and a third fixing portion; The transmission assembly comprises a first transmission shaft, an intermediate transmission shaft and a second transmission shaft which are rotatably connected to the placement box through the first mounting portion, the intermediate mounting portion and the second mounting portion respectively; wherein the first transmission shaft is mounted with a first gear, the intermediate transmission shaft is mounted with an intermediate gear, and the second transmission shaft is mounted with a second gear, the first gear, the intermediate gear and the second gear are meshed in sequence and are arranged in a straight line inside the placement box respectively, the first transmission shaft comprises a first end and a second end extending outside the two sides of the placement box, the second transmission shaft comprises a first end extending outside the placement box body, and the intermediate transmission shaft is completely accommodated inside the placement box; the first end and the second end of the first transmission shaft are respectively provided with a first connection interface and a second connection interface, and the first end of the second transmission shaft is provided with a third connection interface; An actuator, used to control the opening and closing of the valve, is mounted on the outer end surface of the placement box through the first fixing portion, and the first end of the first transmission shaft is connected to the rotation driving end of the actuator through the first connection interface; A positioner, used for positioning the opening and closing angle of the valve, is mounted on the outer end surface of the placement box through the second fixing portion, and the second end of the first transmission shaft is connected to the rotating shaft of the positioner through the second connecting interface; A limit switch is mounted on the outer end surface of the placement box through the third fixing portion, and the first end of the second transmission shaft is connected to the rotating shaft of the limit switch through the third connection interface; The actuator (3) comprises a first cylinder (32), a second cylinder (33) and a crank (34); the first cylinder (32) comprises a first cylinder body (321), a first piston (322) movably connected to the first cylinder body (321), and a first driving rod (323) connected to the first piston (322); the second cylinder (33) comprises a second cylinder body (331), a second piston (332) movably connected to the second cylinder body (331), and a second driving rod (333) connected to the second piston (332); the first driving rod (323) and the second driving rod (333) are located on a straight line and a slider is connected therebetween; the crank (34) is provided with a sliding groove (341) for the slider to slide; the crank (34) is used to connect to a driving shaft of the valve and is connected to the first connection interface (211).

[0006] In one embodiment of the present invention, the placement box includes a box body and a cover plate that are detachably connected; wherein the first mounting portion and the second mounting portion both include a first step through hole arranged on the bottom wall of the box body and a second step through hole arranged on the cover plate and corresponding to the first step through hole; the intermediate mounting portion includes a step blind hole arranged on the bottom wall of the box body.

[0007] In one embodiment of the present invention, the first step through hole and the second step through hole both accommodate a first deep groove ball bearing for supporting the rotation of the first transmission shaft or the second transmission shaft; the step blind hole accommodates a second deep groove ball bearing for supporting the rotation of the intermediate transmission shaft.

[0008] In one embodiment of the present invention, the first fixing portion includes a first mounting hole arranged on the outer end surface of the box body and distributed in the circumference of the first step through hole in the first mounting portion; the second fixing portion includes a second mounting hole arranged on the outer end surface of the cover plate and distributed in the circumference of the second step through hole in the first mounting portion; the third fixing portion includes a third mounting hole arranged on the outer end surface of the cover plate and distributed in the circumference of the second step through hole in the second mounting portion.

[0009] In one embodiment of the present invention, it also includes a first bracket, a second bracket and a third bracket, the first bracket is installed on the outer end surface of the box body through the first mounting hole, the second bracket is installed on the outer end surface of the cover plate through the second mounting hole, and the third bracket is installed on the outer end surface of the cover plate through the third mounting hole. The actuator is installed on the first bracket, the positioner is installed on the second bracket, and the limit switch is installed on the third bracket.

[0010] In one embodiment of the present invention, the box body further comprises a boss extending vertically along the periphery of the bottom wall thereof, a plurality of threaded holes are distributed on the boss, and the cover plate is provided with countersunk holes matching with the threaded holes.

[0011] In one embodiment of the present invention, a cylindrical head screw and a spring washer are matched between the threaded hole and the countersunk hole.

[0012] In one embodiment of the present invention, the first transmission shaft and the first gear, the intermediate transmission shaft and the intermediate gear, and the second transmission shaft and the second gear are all connected by parallel keys.

[0013] In one embodiment of the present invention, the first connection interface is constructed as a flat body located at the first end of the first transmission shaft and a first hole arranged in the middle of the flat body; the second connection interface is constructed as a cross groove located at the second end of the first transmission shaft and a second hole arranged in the middle of the cross groove; the third connection interface is constructed as a straight groove located at the first end of the second transmission shaft and a third hole arranged in the middle of the straight groove.

[0014] The above technical solution of the present invention has the following advantages compared with the prior art: The positioner and limit switch linkage device for a valve described in the present invention can quickly place the valve in a safe open (closed) position when an emergency occurs, and display the valve status through the limit switch, thereby improving the overall safety of the system. The placement box adopts a closed design to protect the internal transmission components from external environments such as rain and dirt, ensuring the stable operation of the device under harsh conditions.

[0015] The present invention adopts a gear transmission structure, which can effectively avoid transmission deviation caused by manual operation and installation errors, ensure the accurate transmission of the entire device during operation, and reduce the occurrence of mechanical failures. The transmission shaft and the gear are connected by a deep groove ball bearing, which reduces internal friction, improves transmission efficiency, and prolongs the service life of the device.

[0016] All transmission elements of the present invention are fixed inside the placement box, which is convenient for storage, has a compact structure, reduces the complexity of external elements, and is convenient for overall installation and maintenance.

[0017] The placement box of the present invention adopts a detachable box body and cover plate design, which is convenient for disassembly and assembly, simplifies the installation process, and can complete installation or replacement without frequent disassembly of parts.

[0018] The connection interface of the transmission shaft of the present invention is designed in standard forms such as a flat body, a cross slot and a slot, etc., has strong compatibility, and is convenient for quick connection with an actuator, a positioner and a limit switch.

[0019] The present invention has good expansibility and can be realized simply by extending the length of the box body and increasing the number of gear sets. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0021] Figure 1 It is a schematic diagram of the overall structure of a positioner and a limit switch linkage device for a valve according to the present invention.

[0022] Figure 2 It is a schematic diagram of the transmission assembly structure of the present invention.

[0023] Figure 3 It is a schematic cross-sectional structural diagram of the box body of the present invention.

[0024] Figure 4 It is a schematic diagram of the top structure of the box body of the present invention.

[0025] Figure 5 It is a bottom view structural schematic diagram of the box body of the present invention.

[0026] Figure 6 It is a schematic diagram of the main structure of the cover plate of the present invention.

[0027] Figure 7 It is a schematic diagram of the top structure of the cover plate of the present invention.

[0028] Figure 8 It is a bottom view structural schematic diagram of the cover plate of the present invention.

[0029] Fig. 9 It is a structural schematic diagram of the transmission gear of the present invention.

[0030] Fig.10 It is a schematic structural diagram of the first transmission shaft of the present invention.

[0031] Fig.11 yes Fig.10 Schematic diagram of direction A.

[0032] Fig.12 yes Fig.10 Schematic diagram of direction B.

[0033] Fig.13 It is a structural schematic diagram of the intermediate transmission shaft of the present invention.

[0034] Fig.14 It is a structural schematic diagram of the second transmission shaft of the present invention.

[0035] Fig.15 yes Fig.14 Left view structural diagram.

[0036] Fig.16 It is a structural schematic diagram of the actuator of the present invention.

[0037] Description of the Figures in the Specification: 1. Placement box; 11a. Box body; 111a. Boss; 112a. Threaded hole; 11b. Cover plate; 111b. Countersunk hole; 11. First mounting portion; 111. First step through hole; 112. Second step through hole; 12. Intermediate mounting portion; 121. Step blind hole; 13. Second mounting portion; 14. First fixing portion; 141. First mounting hole; 15. Second fixing portion; 151. Second mounting hole; 16. Third fixing portion; 161. Third mounting hole; 17. First deep groove ball bearing; 18. Second deep groove ball bearing; 2. Transmission assembly; 21. First transmission shaft; 211. First connection interface; 2111. Flat body; 2112. First hole; 2113. First machining groove; 2114. First shaft keyway; 212. Second connection interface; 2121. Cross groove; 2122. Second hole; 22. Intermediate transmission shaft; 23. Second transmission shaft; 231. Third connection interface; 2311. Slot; 2312. Third hole; 2313. Second machining groove; 2314. Second shaft keyway; 24. First gear; 25. Intermediate gear; 26. Second gear; 271. Shaft hole; 272. Gear flat keyway; 3. Actuator; 31. First bracket; 32. First cylinder; 321. First cylinder body; 322. First piston; 323. First drive rod; 33. Second cylinder; 331. Second cylinder body; 332. Second piston; 333. Second drive rod; 34. Crank; 341. Slide; 4. Positioner; 41. Second bracket; 5. Limit switch; 51. The third bracket. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0039] In the present invention, if directions (up, down, left, right, front and back) are described, it is only for the convenience of describing the technical solution of the present invention, and does not indicate or imply that the technical features referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, it cannot be understood as a limitation of the present invention.

[0040] In the present invention, "several" means one or more, "multiple" means more than two, "greater than", "less than", "exceed" and the like are understood to exclude the number itself; "above", "below", "within" and the like are understood to include the number itself. In the description of the present invention, if there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0041] In the present invention, unless otherwise clearly defined, the words "set", "install", "connect" and the like should be understood in a broad sense, for example, they can be directly connected or indirectly connected through an intermediate medium; they can be fixedly connected or detachably connected or integrally formed; they can be mechanically connected or electrically connected or able to communicate with each other; they can be the internal connection of two elements or the interaction relationship between two elements. Those skilled in the art can reasonably determine the specific meanings of the above words in the present invention in combination with the specific content of the technical solution.

[0042] Reference Figure 1 As shown, a linkage device of a positioner 4 and a limit switch 5 for a valve of the present invention comprises: The placement box 1 is in the shape of an elongated strip, and is provided with a first mounting portion 11, at least one intermediate mounting portion 12 (three in this embodiment) and a second mounting portion 13 in sequence along the length direction of the placement box 1. The placement box 1 also includes a first fixing portion 14, a second fixing portion 15 and a third fixing portion 16; The transmission assembly 2 comprises a first transmission shaft 21, an intermediate transmission shaft 22 and a second transmission shaft 23 which are rotatably connected to the placement box 1 through the first mounting portion 11, the intermediate mounting portion 12 and the second mounting portion 13, respectively; wherein the first transmission shaft 21 is provided with a first gear 24, the intermediate transmission shaft 22 is provided with an intermediate gear 25, the second transmission shaft 23 is provided with a second gear 26, the first gear 24, the intermediate gear 25 and the second gear 26 are meshed in sequence and are arranged in a straight line inside the placement box 1, the first transmission shaft 21 comprises a first end and a second end extending outside the two sides of the placement box 1, the second transmission shaft 23 comprises a first end extending outside the placement box 1, and the intermediate transmission shaft 22 is completely accommodated inside the placement box 1; the first end and the second end of the first transmission shaft 21 are provided with a first connection interface 211 and a second connection interface 212, respectively, and the first end of the second transmission shaft 23 is provided with a third connection interface 231; The actuator 3 is used to control the opening and closing of the valve, and is installed on the outer end surface of the placement box 1 through the first fixing portion 14. The first end of the first transmission shaft 21 is connected to the rotation driving end of the actuator 3 through the first connection interface 211; The positioner 4 is used to position the opening and closing angle of the valve, and is installed on the outer end surface of the placement box 1 through the second fixing portion 15. The second end of the first transmission shaft 21 is connected to the rotating shaft of the positioner 4 through the second connection interface 212; The limit switch 5 is mounted on the outer end surface of the placement box 1 through the third fixing portion 16 , and the first end of the second transmission shaft 23 is connected to the rotation axis of the limit switch 5 through the third connection interface 231 .

[0043] Through the above arrangement, in normal operation, the positioner 4 gives a signal to control the opening and closing angle of the valve. When an emergency occurs, the valve can be urgently controlled to be in an open (closed) safe position. At this time, the limit switch 5 can realize synchronous movement with the positioner 4 through the placement box 1, thereby displaying whether the state of the valve is in an open (closed) safe position. The linkage device adopts an integral box-type structure, and each transmission element is placed inside the placement box 1, which is convenient for storage. The direction of movement is transmitted through the transmission gear set, and the combination of the transmission shaft and the deep groove ball bearing is combined to effectively reduce the internal friction and extend the service life. There is no need to disassemble parts during installation. The basically closed box body 11a structure also effectively prevents the intrusion of rainwater and dirt, simplifying the installation process.

[0044] It should be noted that the (angle) positioner 4 is a device for accurately controlling the opening and closing angle of the valve. It is used to receive signals from the control system and adjust the opening of the valve according to the signals to achieve the required flow or pressure control target. The limit switch 5 is a device for detecting whether the valve has reached a predetermined position (such as fully open or fully closed).

[0045] In an emergency (such as system failure, leakage, fire, etc.), the valve needs to be quickly placed in a safe position (usually fully open or fully closed) to ensure system safety. After the system detects an emergency, it controls the positioner 4 to achieve synchronous movement with the limit switch 5, and the limit switch 5 moves to the corresponding position accordingly. After the limit switch 5 detects that the valve has reached a safe position, it displays the current state of the valve (open or closed) to the control system or operator through a feedback signal to ensure the reliability of the system.

[0046] It should be noted that, compared with the use of connecting rod transmission structure for transmission, although it can also play a transmission role, due to the deviation of the size of the connecting rod during processing, the deviation of the angle when the worker installs it, and the influence of its own strength, the connecting rod structure as a whole often deforms and moves poorly, thus affecting the transmission efficiency. Therefore, compared with the connecting rod transmission structure, the gear transmission structure will not have such influences due to labor and installation reasons, and the overall structure is more stable and reliable.

[0047] Reference Figure 2 As shown, by sequentially meshing the first gear 24, the intermediate gear 25 and the second gear 26, a stable and efficient transmission is achieved, ensuring the accuracy and reliability of power transmission. The linear arrangement of the gears reduces the complexity of the transmission path, reduces the transmission loss, and improves the overall transmission efficiency.

[0048] Reference Figure 1 , Figure 3 , Figure 6 As shown, the placement box 1 includes a box body 11a and a cover plate 11b that are detachably connected.

[0049] Wherein, the first mounting portion 11 and the second mounting portion 13 both include a first step through hole 111 arranged on the bottom wall of the box body 11a and a second step through hole 112 arranged on the cover plate 11b and corresponding to the first step through hole 111; the intermediate mounting portion 12 includes a step blind hole 121 arranged on the bottom wall of the box body 11a.

[0050] Reference Figure 1As shown, in order to effectively reduce friction and wear during the transmission process and improve transmission efficiency and system life, the first step through hole 111 and the second step through hole 112 both accommodate a first deep groove ball bearing 17 for supporting the rotation of the first transmission shaft 21 or the second transmission shaft 23; the step blind hole 121 accommodates a second deep groove ball bearing 18 for supporting the rotation of the intermediate transmission shaft 22.

[0051] In one embodiment, referring to Figure 4 , Figure 5 As shown, the first fixing portion 14 includes first mounting holes 141 disposed on the outer end surface of the box body 11a and distributed around the first step through hole 111 in the first mounting portion 11. Figure 7 , Figure 8 As shown, the second fixing portion 15 includes a second mounting hole 151 which is arranged on the outer end surface of the cover plate 11b and distributed in the circumference of the second step through hole 112 in the first mounting portion 11; the third fixing portion 16 includes a third mounting hole 161 which is arranged on the outer end surface of the cover plate 11b and distributed in the circumference of the second step through hole 112 in the second mounting portion 13.

[0052] Reference Figure 1 As shown, it also includes a first bracket 31, a second bracket 41 and a third bracket 51. The first bracket 31 is installed on the outer end surface of the box body 11a through the first mounting hole 141, the second bracket 41 is installed on the outer end surface of the cover plate 11b through the second mounting hole 151, and the third bracket 51 is installed on the outer end surface of the cover plate 11b through the third mounting hole 161. The actuator 3 is installed on the first bracket 31, the positioner 4 is installed on the second bracket 41, and the limit switch 5 is installed on the third bracket 51.

[0053] In one embodiment, referring to Figure 4 , Figure 7 As shown, the box body 11a further includes a boss 111a extending vertically along the periphery of its bottom wall, the boss 111a is provided with a plurality of threaded holes 112a, and the cover plate 11b is provided with a countersunk hole 111b matched with the threaded hole 112a. Specifically, a column head screw and a spring washer are matched between the threaded hole 112a and the countersunk hole 111b.

[0054] In one embodiment, the first transmission shaft 21 and the first gear 24 , the intermediate transmission shaft 22 and the intermediate gear 25 , and the second transmission shaft 23 and the second gear 26 are all connected by parallel keys.

[0055] Specifically, refer to Fig. 9As shown, the first gear 24, the intermediate gear 25 and the second gear 26 are provided with an axial hole 271 and a gear flat keyway 272; Reference Figures 10 to 12 As shown, the shaft body of the first transmission shaft 21 is provided with a first machining groove 2113 , a first shaft keyway 2114 , a flat body 2111 , and a cross groove 2121 .

[0056] Reference Fig.14 , Fig.15 As shown, the shaft body of the second transmission shaft 23 is provided with a second machining groove 2313 , a second shaft keyway 2314 , and a straight groove 2311 .

[0057] The shaft body of the intermediate transmission shaft 22 is provided with a third machining groove, a third shaft keyway and a step.

[0058] More specifically, refer to Fig.12 As shown, the first connection interface 211 is constructed as a flat body 2111 located at the first end of the first transmission shaft 21 and a first hole 2112 arranged in the middle of the flat body 2111; Fig.11 As shown, the second connection interface 212 is constructed as a cross groove 2121 located at the second end of the first transmission shaft 21 and a second hole 2122 arranged in the middle of the cross groove 2121; Fig.15 As shown, the third connection interface 231 is constructed as a straight groove 2311 located at the first end of the second transmission shaft 23 and a third hole 2312 arranged in the middle of the straight groove 2311 .

[0059] In one embodiment, referring to Fig.16 As shown, the actuator 3 includes a first cylinder 32, a second cylinder 33 and a crank 34, the first cylinder 32 includes a first cylinder body 321, a first piston 322 movably connected to the first cylinder body 321, and a first driving rod 323 connected to the first piston 322, the second cylinder 33 includes a second cylinder body 331, a second piston 332 movably connected to the second cylinder body 331, and a second driving rod 333 connected to the second piston 332, the first driving rod 323 and the second driving rod 333 are located in a straight line and a slider is connected therebetween, the crank 34 is provided with a slide groove 341 for the slider to slide, the crank 34 is used to connect the drive shaft of the valve and is connected to the first connection interface 211.

[0060] By setting the first cylinder 32 and the second cylinder 33 and connecting them through a slider, the torque applied by the actuator 3 can be balanced, the load of a single cylinder during the transmission process can be reduced, and the stability and smoothness of the system can be improved. The design of the crank 34 can efficiently convert the linear motion of the cylinder into the rotational motion of the valve drive shaft, ensuring the rapid and accurate opening and closing of the valve, and improving the response speed and accuracy of the control system. The dual-cylinder structure is easy to maintain and adjust independently. Users can inspect or replace any cylinder as needed without affecting the operation of the entire transmission system, thereby improving the maintainability and service life of the system.

[0061] The gear structure adopted by the linkage device effectively avoids problems caused by manual operation and installation, making the overall structure more stable and reliable. At the same time, the structure has good scalability. At present, the single transmission shaft of the actuator 3 is converted into a double transmission shaft of the placement box 1. In the future, if more parts (such as 3 or 4) need to be connected in series, it is only necessary to adjust the length of the box body 11a and increase the number of gear sets.

[0062] The linkage device adopts an integral box-type structure, and each transmission element is placed inside the placement box 1. The direction of movement is transmitted through the transmission gear set, and the combination of the transmission shaft and the deep groove ball bearing effectively reduces the internal friction and prolongs the service life. In addition, since each transmission shaft and deep groove ball bearing are installed in the corresponding position inside the box body 11a, the problem of inaccurate position caused by improper operation of the installer is greatly reduced, and there is no need to disassemble parts during installation. The closed box body 11a structure also effectively prevents the intrusion of rainwater and dirt, simplifying the installation process. During installation and disassembly, for the placement box 1 of the same specification, it is only necessary to disassemble the first bracket 31 connected to the actuator 3.

[0063] In normal operation, the control system sends a signal to the positioner 4, which adjusts the valve opening through the transmission component 2 to control the flow. When the system detects an abnormal situation (such as system failure, leakage, fire, etc.), the emergency control positioner 4 is activated and fed back to the actuator 3, and the limit switch 5 is activated synchronously.

[0064] The linkage device of the positioner 4 and the limit switch 5 of the present invention can realize precise control of the valve through precise mechanical design and synchronous motion mechanism in normal operation and emergency situations. This not only improves the operating accuracy and response speed of the system, but also enhances the overall safety and reliability, and is suitable for various industrial application scenarios requiring high-precision valve control.

[0065] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A positioner and limit switch linkage device for a valve, characterized in that: include: The placement box (1) is in the shape of an elongated strip, and is provided with a first mounting portion (11), at least one intermediate mounting portion (12) and a second mounting portion (13) in sequence along the length direction of the placement box (1); the placement box (1) also includes a first fixing portion (14), a second fixing portion (15) and a third fixing portion (16); The transmission assembly (2) comprises a first transmission shaft (21), an intermediate transmission shaft (22) and a second transmission shaft (23) which are rotatably connected to the placement box (1) via the first mounting portion (11), the intermediate mounting portion (12) and the second mounting portion (13) respectively; wherein the first transmission shaft (21) is mounted with a first gear (24), the intermediate transmission shaft (22) is mounted with an intermediate gear (25), the second transmission shaft (23) is mounted with a second gear (26), and the first gear (24), the intermediate gear (25) and the second gear (26) are meshed in sequence and are arranged in a straight line inside the placement box (1), the first transmission shaft (21) includes a first end and a second end extending outside the two sides of the placement box (1), the second transmission shaft (23) includes a first end extending outside the placement box (1), and the intermediate transmission shaft (22) is completely accommodated inside the placement box (1); the first end and the second end of the first transmission shaft (21) are respectively provided with a first connection interface (211) and a second connection interface (212), and the first end of the second transmission shaft (23) is provided with a third connection interface (231); an actuator (3) for controlling the opening and closing of the valve, mounted on the outer end surface of the placement box (1) via the first fixing portion (14), the first end of the first transmission shaft (21) being connected to the rotation driving end of the actuator (3) via the first connection interface (211); A positioner (4) for positioning the opening and closing angle of the valve, mounted on the outer end surface of the placement box (1) via the second fixing portion (15), the second end of the first transmission shaft (21) being connected to the rotating shaft of the positioner (4) via the second connection interface (212); A limit switch (5) is mounted on the outer end surface of the placement box (1) via the third fixing portion (16); the first end of the second transmission shaft (23) is connected to the rotation axis of the limit switch (5) via the third connection interface (231); The actuator (3) comprises a first cylinder (32), a second cylinder (33) and a crank (34); the first cylinder (32) comprises a first cylinder body (321), a first piston (322) movably connected to the first cylinder body (321), and a first driving rod (323) connected to the first piston (322); the second cylinder (33) comprises a second cylinder body (331), a second piston (332) movably connected to the second cylinder body (331), and a second driving rod (333) connected to the second piston (332); the first driving rod (323) and the second driving rod (333) are located on a straight line and a slider is connected therebetween; the crank (34) is provided with a sliding groove (341) for the slider to slide; the crank (34) is used to connect to a driving shaft of the valve and is connected to the first connection interface (211).

2. A positioner and limit switch linkage device for a valve according to claim 1, characterized in that: The placement box (1) comprises a detachably connected box body (11a) and a cover plate (11b); wherein the first mounting portion (11) and the second mounting portion (13) both comprise a first step through hole (111) arranged on the bottom wall of the box body (11a) and a second step through hole (112) arranged on the cover plate (11b) and corresponding to the first step through hole (111); and the intermediate mounting portion (12) comprises a step blind hole (121) arranged on the bottom wall of the box body (11a).

3. A positioner and limit switch linkage device for a valve according to claim 2, characterized in that: The first step through hole (111) and the second step through hole (112) both accommodate a first deep groove ball bearing (17) for supporting the first transmission shaft (21) or the second transmission shaft (23) for rotation; the step blind hole (121) accommodates a second deep groove ball bearing (18) for supporting the intermediate transmission shaft (22) for rotation.

4. A positioner and limit switch linkage device for a valve according to claim 2, characterized in that: The first fixing portion (14) comprises a first mounting hole (141) arranged on the outer end surface of the box body (11a) and distributed in the circumference of the first step through hole (111) in the first mounting portion (11); the second fixing portion (15) comprises a second mounting hole (151) arranged on the outer end surface of the cover plate (11b) and distributed in the circumference of the second step through hole (112) in the first mounting portion (11); and the third fixing portion (16) comprises a third mounting hole (161) arranged on the outer end surface of the cover plate (11b) and distributed in the circumference of the second step through hole (112) in the second mounting portion (13).

5. A positioner and limit switch linkage device for a valve according to claim 4, characterized in that: The invention also comprises a first bracket (31), a second bracket (41) and a third bracket (51), wherein the first bracket (31) is mounted on the outer end surface of the box body (11a) through the first mounting hole (141), the second bracket (41) is mounted on the outer end surface of the cover plate (11b) through the second mounting hole (151), and the third bracket (51) is mounted on the outer end surface of the cover plate (11b) through the third mounting hole (161). The actuator (3) is mounted on the first bracket (31), the positioner (4) is mounted on the second bracket (41), and the limit switch (5) is mounted on the third bracket (51).

6. A positioner and limit switch linkage device for a valve according to claim 2, characterized in that: The box body (11a) further comprises a boss (111a) extending vertically along the periphery of its bottom wall, a plurality of threaded holes (112a) are distributed on the boss (111a), and the cover plate (11b) is provided with countersunk holes (111b) matching the threaded holes (112a).

7. A positioner and limit switch linkage device for a valve according to claim 6, characterized in that: A column head screw and a spring washer are matched between the threaded hole (112a) and the countersunk hole (111b).

8. A positioner and limit switch linkage device for a valve according to claim 1, characterized in that: The first transmission shaft (21) and the first gear (24), the intermediate transmission shaft (22) and the intermediate gear (25), and the second transmission shaft (23) and the second gear (26) are all connected by means of a flat key.

9. A positioner and limit switch linkage device for a valve according to claim 1, characterized in that: The first connection interface (211) is constructed as a flat body (2111) located at the first end of the first transmission shaft (21) and a first hole (2112) arranged in the middle of the flat body (2111); the second connection interface (212) is constructed as a cross groove (2121) located at the second end of the first transmission shaft (21) and a second hole (2122) arranged in the middle of the cross groove (2121); the third connection interface (231) is constructed as a straight groove (2311) located at the first end of the second transmission shaft (23) and a third hole (2312) arranged in the middle of the straight groove (2311).

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