A mechanical limiting mechanism for a multi-spring pneumatic diaphragm actuator

Abstract

This utility model provides a mechanical limiting mechanism for a multi-spring pneumatic diaphragm actuator, installed on a regulating valve. When air enters through the inlet, the push rod drives the limiting frame, diaphragm, and lower diaphragm cover to press the spring device downwards. This mechanical limiting actuator includes a limiting body; the mechanical limiting mechanism has independent upper and lower stroke limiting assembly structures. This utility model has a reasonable structural design. Through the independent upper and lower stroke limiting assembly structures, the valve opening can be effectively limited, achieving a mechanical limiting function. During installation, only the upper diaphragm cover and push rod are added. Most parts are interchangeable with conventional products without limiting requirements, saving costs without affecting functionality, reducing enterprise processing costs and inventory pressure, and improving utilization efficiency.

Description

Technical Field

[0001] This utility model relates to the field of valve technology, particularly regulating valve technology, and more particularly to a mechanical limiting mechanism for a multi-spring pneumatic diaphragm actuator. Background Technology

[0002] A control valve is an automated control device used to control process parameters such as flow rate, pressure, temperature, or level of fluids (e.g., gas, liquid, steam). It typically consists of an actuator and a valve body. The core function of a control valve is to precisely adjust the flow area of ​​the fluid in the pipeline by changing the valve opening, thereby achieving dynamic control of process parameters.

[0003] In practical applications, the minimum and maximum valve opening degrees need to be limited by a control system or mechanical limiter according to process requirements. When optimizing the opening degree limit in real time based on operating conditions, intelligent regulating valves are usually used, or the control system employs an adaptive control algorithm, which results in a relatively complex structure.

[0004] For conventional control valves, a mechanical limit mechanism is added. This common addition structure involves significant modifications to the control valve mechanism, requiring the re-molding and reassembly of all components and parts. This results in low rotational efficiency and substantial processing costs and inventory pressure for the company.

[0005] Therefore, those skilled in the art need to make further structural improvements to the existing mechanical limiting mechanism of the regulating valve to address this issue. Utility Model Content

[0006] The technical problem to be solved by this utility model is: in order to overcome the shortcomings of the prior art, this utility model provides a mechanical limiting mechanism for a multi-spring pneumatic diaphragm actuator, which only requires modification of the upper diaphragm cover and push rod, and can be used with conventional products with unlimited positioning requirements, effectively reducing processing costs and inventory pressure.

[0007] The technical solution adopted by this utility model to solve its technical problem is: a mechanical limiting mechanism for a multi-spring pneumatic diaphragm actuator, which is installed on a regulating valve. The regulating valve includes a push rod and, from top to bottom, an upper diaphragm cover, a limiting frame, a diaphragm, a lower diaphragm cover, and a spring device. The upper diaphragm cover has a mounting hole and an air inlet. The push rod passes through the mounting hole. When air enters through the air inlet, the push rod drives the limiting frame, the diaphragm, and the lower diaphragm cover to press the spring device downward. The mechanical limiting mechanism includes a limiting body. The limiting body is fixed at the mounting hole position and has a through hole inside. The mechanical limiting mechanism has an independent upper stroke limiting assembly structure and a lower stroke limiting assembly structure. The upper stroke limiting assembly structure includes an upper fixed stroke rod and an upper positioning screw. The upper stroke limiter is located within the through hole, and its upper outer circumferential surface has an external thread. The upper stroke limiter is threadedly engaged with the upper end of the limiting body, and its upper end extends beyond the limiting body. An upper positioning nut is threadedly connected to the position where the upper stroke limiter extends beyond the limiting body. When the push rod is in the upper stroke limit position, the push rod moves upward until its upper end face abuts against the lower end face of the stroke limiter; this position is the upper stroke limit position of the push rod. The lower stroke limiter assembly includes a lower stroke limiter, which is vertically and vertically positioned within the through hole. The upper section of the lower stroke limiter extends from the through hole of the limiting body. The lower stroke limiter is vertically and horizontally extendable relative to the limiting body. The outer circumferential surface of the upper section of the lower stroke limiter has an external thread, and an adjusting nut is threadedly connected to this threaded section. The lower end of the lower stroke limiter is connected to the push rod. When the push rod is in the lower stroke limit position, the push rod moves downward, causing the lower stroke limiter to move downward until the lower end face of the adjusting nut abuts against the upper end face of the limiting body; this position is the lower stroke limit position of the push rod.

[0008] In the above scheme, a limiting body is added to the upper membrane cover, and independent upper stroke limiting assembly structure and lower stroke limiting assembly structure are reasonably set. When the upper stroke limit is required, an upper stroke nut is added. The position where the upper end face of the upper stroke nut abuts against the lower end face of the limiting body is the upper stroke limit position of the push rod. When the lower stroke limit is required, a lower stroke rod and an adjusting nut are added. The position where the lower end face of the adjusting nut abuts against the upper end face of the limiting body is the lower stroke limit position of the push rod.

[0009] Furthermore, when the push rod is in the lower stroke limit position, the lower outer diameter of the limiting body is adapted to the inner diameter of the mounting hole, and the lower end face of the limiting body extends outward in the circumferential direction to have a mounting buckle. The outer diameter of the mounting buckle is larger than the inner diameter of the mounting hole. The limiting body is circumferentially welded and fixed to the upper membrane cover, and the upper end face of the mounting buckle abuts against the inner top surface of the upper membrane cover.

[0010] Furthermore, when the push rod is in the lower stroke limit position, in the connection between the lower stroke rod and the push rod, the lower end face of the lower stroke rod has a recessed mounting cavity, the inner wall of the mounting cavity has an internal thread, the top end of the push rod has an external thread that mates with the thread of the mounting cavity, and the lower end of the push rod and the fixed support rod are connected by the thread of the mounting cavity.

[0011] Furthermore, the lower stroke rod has at least one through threaded hole on the side wall of the mounting cavity. A set screw is threaded into the threaded hole, and when the set screw is threaded into the threaded hole, the end of the set screw abuts against the outer wall of the push rod. The set screw provides further positioning and fastening for the lower stroke rod and the push rod.

[0012] Preferably, there are two adjusting nuts, which are threadedly connected to the lower travel rod from top to bottom. They are an upper tightening nut and a lower limit nut. When the lower limit nut abuts against the upper end face of the limit body, the push rod is at its lower travel limit position. The upper tightening nut is threadedly connected to the lower travel rod and its lower end face abuts against the lower limit nut for tightening.

[0013] Furthermore, the mechanical limiting mechanism includes an adjusting cover, which is detachably mounted on the upper end face of the limiting body and covers the upper or lower travel rod. The adjusting cover provides effective protection for the limiting body, the upper travel rod, the lower travel rod, and the adjusting nut.

[0014] Furthermore, a bushing is provided to seal between the inner wall of the through hole and the lower stroke rod, and a sealing ring is also provided below the bushing between the inner wall of the through hole and the lower stroke rod. The design of the bushing and sealing ring improves the sealing performance between the lower stroke rod and the limiting body, effectively preventing leakage.

[0015] The beneficial effects of this utility model are that the mechanical limiting mechanism of the multi-spring pneumatic diaphragm actuator provided by this utility model has a reasonable structural design. Through independent upper and lower stroke limiting assembly structures, and equipped with an adjusting cover, it can effectively limit the valve opening and play a mechanical limiting role. During the installation process, only the upper diaphragm cover and push rod are added. Most parts are interchangeable with conventional products without limiting requirements, thus saving costs without affecting functionality, reducing enterprise processing costs and inventory pressure, and improving utilization efficiency. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] Figure 1 This is a schematic diagram of the upper travel limit of this utility model.

[0018] Figure 2 yes Figure 1 A schematic diagram of the structure with a limiting body added to the upper membrane cover.

[0019] Figure 3 This is a schematic diagram of the lower stroke limit of this utility model.

[0020] Figure 4 yes Figure 3A schematic diagram of the structure with a limiting body added to the upper membrane cover.

[0021] In the diagram: 1. Adjusting cover; 2. Upper positioning nut; 3. Upper travel rod; 4. Limiting body; 5. Bushing; 6. Sealing ring; 7. Air inlet; 8. Upper diaphragm cover; 9. Limiting frame; 10. Diaphragm; 11. Tray; 12. Spring device; 13. Push rod; 14. Upper tightening nut; 15. Lower limit nut; 16. Lower travel rod; 17. Set screw. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the present invention. Therefore, they only show the components relevant to the present invention. Orientations and references (e.g., up, down, left, right, etc.) are only used to aid in the description of the features in the drawings. Therefore, the following specific embodiments are not intended to be restrictive, and the scope of the claimed subject matter is defined solely by the appended claims and their equivalents.

[0023] like Figures 1 to 4 The mechanical limiting mechanism of a multi-spring pneumatic diaphragm actuator shown is an embodiment of this utility model. This mechanical limiting structure is installed on a regulating valve, which includes a push rod 13 and, from top to bottom, an upper diaphragm cover 8, a limiting frame 9, a diaphragm 10, a tray 11, a lower diaphragm cover, and a spring device 12. The upper diaphragm cover 8 has a mounting hole and an air inlet 7, and the push rod 13 passes through the mounting hole. The upper end of the push rod 13 is typically equipped with an external thread.

[0024] Figure 1 and Figure 3 This is the direct-acting actuator of the regulating valve. Its direction of action is as follows: air is injected through inlet 7, pushing diaphragm 10 vertically downwards. Limiting bracket 9, diaphragm 10, and tray 11 all press downwards, and push rod 13 is also driven to move vertically downwards. The lower limit position (fully open) of the normal stroke (without a mechanical limiting mechanism) is when the bottom surface of the limiting cylinder abuts against the inner wall of the lower diaphragm cover. When air is lost, gas is discharged from inlet 7, the spring gradually returns to its original position, pushing tray 11 and diaphragm 10 vertically upwards until they return to the zero position. Push rod 13 is also driven to move vertically upwards. The upper limit position (zero) of the normal stroke (without a mechanical limiting mechanism) is when the top surface of the direct-acting limiting bracket 9 abuts against the inner wall of the upper diaphragm cover 8.

[0025] This embodiment includes a limiting body 4, which is fixed at the mounting hole position. The limiting body 4 is hollow and has a through hole.

[0026] This embodiment has two independent installation and assembly methods, namely the upper travel limit assembly structure and the lower travel limit assembly structure.

[0027] Upper travel limit assembly structure such as Figure 1 and Figure 2 As shown, in this installation assembly method, a limiting body 4 with an internal thread at the upper end needs to be selected. The upper stroke limiting assembly structure includes an upper fixed stroke rod 3 and an upper positioning nut 2. The upper fixed stroke rod 3 is set in the through hole, and the outer circumferential surface of the upper end of the upper fixed stroke rod 3 has an external thread. The upper fixed stroke rod 3 is threadedly engaged with the upper end of the limiting body 4 and the upper end extends out of the limiting body 4. The upper positioning nut 2 is threadedly connected to the position where the upper fixed stroke rod 3 extends out of the limiting body 4. When the upper stroke of the push rod 13 is limited, the push rod 13 moves up until the upper end face of the push rod 13 abuts against the lower end face of the fixed stroke rod. This position is the upper stroke limit position of the push rod 13.

[0028] Specifically, for ease of adjustment, the top of the upper stroke rod 3 can be milled flat. The upper stroke rod 3 and the push rod 13 are two independently moving components. By milling the top of the stroke rod, the external thread on the upper part of the stroke rod and the internal thread on the upper part of the limit body 4 form a screw-nut engagement, causing the upper stroke rod 3 to rotate vertically downwards. The longitudinal position of the upper stroke rod 3 changes, and the bottom of the upper stroke rod 3 presses against the top surface of the push rod 13 downwards, simultaneously compressing the spring and driving the diaphragm 10 and tray 11 to move downwards. After adjusting to the required upper limit position, the upper positioning nut 2 is tightened to secure the upper stroke rod 3. The push rod 13 is linked with the limit frame 9, diaphragm 10, tray 11, and other components, and their movements are synchronized. When air is lost, the push rod 13 moves vertically upwards. At this time, the upper stroke rod 3 remains stationary, and the upper limit position is when the top of the push rod 13 abuts against the bottom of the upper stroke rod 3.

[0029] Lower stroke limit assembly structure such as Figure 3 and Figure 4 As shown, the lower stroke limiting assembly structure includes a lower stroke rod 16, which is vertically mounted within the through hole. The upper section of the lower stroke rod 16 extends from the through hole of the limiting body 4, and the lower stroke rod 16 is vertically telescopic relative to the limiting body 4. The outer circumferential surface of the upper section of the lower stroke rod 16 has an external thread, and an adjusting nut is threadedly connected to this threaded section. The lower end of the lower stroke rod 16 is connected to the push rod 13. When the push rod 13 is in the lower stroke limiting position, the push rod 13 moves downward, causing the lower stroke rod 16 to move downward until the lower end face of the adjusting nut abuts against the upper end face of the limiting body 4. This position is the lower stroke limit position of the push rod 13.

[0030] Specifically, the upper end of the lower stroke rod 16 extends from the through hole of the limiting body 4, and its outer circumferential surface has external threads. An adjusting nut is threaded onto this threaded section. Two hexagonal nuts are used as the adjusting nuts, threaded sequentially from top to bottom onto the lower stroke rod 16: an upper preload nut 14 and a lower limit nut 15. When the lower limit nut 15 abuts against the upper end face of the limiting body 4, the push rod 13 is at its lower stroke limit position. The upper preload nut 14 is threaded onto the lower stroke rod 16, and its lower end face abuts against the lower limit nut 15 for a preloaded tightening. The hexagonal nuts can be screwed onto the threads of the lower stroke rod 16. Adjusting the position of the hexagonal nuts achieves the user-required limit opening adjustment. The double-nut design, with the upper preload nut 14 acting as a preload, effectively prevents rotation of one nut during vibration or violent movement, thus ensuring the accuracy of the valve's limit opening.

[0031] The lower end of the lower stroke rod 16 is connected to the push rod 13. In the connection between the lower stroke rod 16 and the push rod 13, the lower end face of the lower stroke rod 16 has a recessed mounting cavity with internal threads on the inner wall. The top end of the push rod 13 has external threads that mate with the threads of the mounting cavity. The push rod 13 and the lower end of the fixed support rod are connected via the threads of the mounting cavity. A through-hole threaded hole is opened on the side wall of the mounting cavity corresponding to the lower stroke rod 16. A set screw 17 is threaded into this hole, and when the set screw 17 is threaded into the hole, its end abuts against the outer wall of the push rod 13. The set screw 17 provides further positioning and fastening for the lower stroke rod 16 and the push rod 13. When the push rod 13 moves downwards, it drives the lower stroke rod 16 downwards until the lower end face of the adjusting nut abuts against the upper end face of the limiting body 4. This position is the lower stroke limit position of the push rod 13.

[0032] To address the sealing issues between the regulating valve and the mechanical limit mechanism during assembly and use, a bushing 5 is provided between the inner wall of the through hole and the lower limit rod 16 for sealing. A sealing ring 6 is also provided below the bushing 5 between the inner wall of the through hole and the lower limit rod 16. The design of the bushing 5 and the sealing ring 6 improves the sealing performance between the lower limit rod 16 and the limit body 4, effectively preventing leakage. Simultaneously, the mechanical limit mechanism also includes an adjusting cover 1, which is detachably mounted on the upper surface of the limit body 4 and covers either the upper limit rod 3 or the lower limit rod 16. The adjusting cover 1 provides effective protection for the limit body 4, the upper limit rod 3, the lower limit rod 16, and the adjusting nut.

[0033] This mechanical limit mechanism is ingeniously designed. Considering its commonality and functionality with conventional products, the push rod 13 remains unchanged; only the upper membrane cover 8 is added, along with a limit body 4. Based on the upper and lower limit requirements, independently assembled upper and lower stroke limit assembly structures are provided. Most parts are interchangeable with conventional products without limit requirements, achieving cost savings and improved efficiency without affecting functionality. The limit mechanism features multiple sealing designs, combining radial and planar seals such as O-rings and bushings 5 ​​and sealing rings 6, fully ensuring safe use and superior performance.

[0034] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A mechanical limiting mechanism for a multi-spring pneumatic diaphragm actuator, mounted on a regulating valve, the regulating valve comprising a push rod and, from top to bottom, an upper diaphragm cover, a limiting frame, a diaphragm, a lower diaphragm cover, and a spring device, wherein the upper diaphragm cover has a mounting hole and an air inlet, the push rod passes through the mounting hole, and when air enters through the air inlet, the push rod drives the limiting frame, the diaphragm, and the lower diaphragm cover to press the spring device downwards, characterized in that: Includes a limiting body; the limiting body is fixed at the mounting hole position, and the limiting body is hollow inside with a through hole; The mechanical limiting mechanism has independent upper stroke limiting assembly structure and lower stroke limiting assembly structure; The upper stroke limit assembly structure includes an upper fixed stroke rod and an upper positioning nut. The upper fixed stroke rod is set in the through hole, and the outer circumferential surface of the upper end of the upper fixed stroke rod has an external thread. The upper fixed stroke rod is threadedly engaged with the upper end of the limit body and extends out of the limit body. The upper positioning nut is threadedly connected to the position where the upper fixed stroke rod extends out of the limit body. When the upper stroke of the push rod is limited, the push rod moves up until the upper end face of the push rod abuts against the lower end face of the fixed stroke rod. This position is the upper stroke limit position of the push rod. The lower stroke limit assembly structure includes a lower stroke rod, which is vertically mounted in the through hole. The upper section of the lower stroke rod extends out from the through hole of the limit body. The lower stroke rod is telescopically mounted relative to the limit body. The outer circumferential surface of the upper section of the lower stroke rod has an external thread, and an adjusting nut is threadedly connected to the threaded section. The lower end of the lower stroke rod is connected to the push rod. When the push rod is in the lower stroke limit position, the push rod moves downward and drives the lower stroke rod downward until the lower end face of the adjusting nut abuts against the upper end face of the limit body. This position is the lower stroke limit position of the push rod.

2. The mechanical limiting mechanism of a multi-spring pneumatic diaphragm actuator as described in claim 1, characterized in that: When the push rod is in the lower stroke limit position, the outer diameter of the lower end of the limit body is adapted to the inner diameter of the mounting hole. The lower end face of the limit body extends outward in the circumferential direction to have a mounting buckle. The outer diameter of the mounting buckle is larger than the inner diameter of the mounting hole. The limit body is circumferentially welded and fixed to the upper membrane cover. The upper end face of the mounting buckle abuts against the inner top surface of the upper membrane cover.

3. The mechanical limiting mechanism of a multi-spring pneumatic diaphragm actuator as described in claim 1, characterized in that: The lower end face of the lower fixed stroke rod has a recessed mounting cavity, the inner wall of the mounting cavity has an internal thread, the top of the push rod has an external thread that mates with the thread of the mounting cavity, and the push rod and the lower end of the fixed support rod are connected by the thread of the mounting cavity.

4. The mechanical limiting mechanism of a multi-spring pneumatic diaphragm actuator as described in claim 3, characterized in that: The lower stroke rod has at least one through threaded hole on the side wall of the mounting cavity. A set screw is installed in the threaded hole. When the set screw is threaded into the threaded hole, the end of the set screw that extends into the threaded hole abuts against the outer wall of the push rod.

5. The mechanical limiting mechanism of a multi-spring pneumatic diaphragm actuator as described in claim 1, characterized in that: The number of adjusting nuts is two, which are threadedly connected to the lower stroke rod from top to bottom. They are the upper tightening nut and the lower limit nut. When the lower limit nut abuts against the upper end face of the limit body, the position of the push rod is its lower stroke limit position. The upper tightening nut is threadedly connected to the lower stroke rod and its lower end face abuts against the lower limit nut for tightening.

6. The mechanical limiting mechanism of a multi-spring pneumatic diaphragm actuator as described in claim 1, characterized in that: It includes an adjustment cover, which is detachably mounted on the upper end surface of the limiting body and covers the upper or lower stroke rod.

7. The mechanical limiting mechanism of a multi-spring pneumatic diaphragm actuator as described in claim 1, characterized in that: A bushing is provided between the inner wall of the through hole and the lower stroke rod for sealing, and a sealing ring is also provided below the bushing between the inner wall of the through hole and the lower stroke rod.

Images