A double-cylinder pneumatic actuator

Abstract

The utility model provides a kind of double-cylinder pneumatic actuator, belong to valve drive actuator technical field.Aiming at the problem that butterfly valve under high temperature condition causes starting torque to increase dramatically due to thermal expansion, the actuator adopts nested double-cylinder structure: including coaxially arranged first cylinder and second cylinder, the piston rod of first cylinder is connected yoke mechanism to drive output shaft rotation, the outer piston rod of second cylinder extends into first cylinder and abuts with first piston.By gas path control, double cylinder is supplied with gas simultaneously in initial stage, so that piston rod obtains double thrust to overcome high temperature static friction force;When second piston moves to the end of stroke, only first cylinder works, and output torque is automatically reduced.Gas path adopts solenoid valve and three-way valve cooperative control, realizes double-cylinder synchronous drive and reset function.Double cylinder shares compact cylinder wall structure, combined with sealing ring design to ensure air tightness, effectively solve the jam when high temperature valve opens, improve equipment safety and life.

Description

Technical Field

[0001] This utility model belongs to the technical field of valve drive actuators, and specifically refers to a dual-cylinder starter actuator. Background Technology

[0002] Butterfly valves, as fluid control components with simple structure and rapid opening and closing, are widely used in industrial pipeline systems. During the opening and closing process of a butterfly valve, especially in the initial stage of the valve's transition from the closed to the open state (typically corresponding to the first 0°~20° of valve plate rotation), the required driving torque usually reaches its maximum value due to the need to overcome the static friction between the valve plate and the valve seat, as well as the fluid pressure difference. As the valve plate gradually opens, the friction and fluid resistance decrease rapidly, and the required driving torque also decreases significantly. Pneumatic actuators are the mainstream device for driving butterfly valves to achieve automated operation. Among them, the fork-type pneumatic actuator is widely used due to its compact structure, high output torque, and simple and reliable operation. It uses compressed air to push a piston, which in turn drives a fork mechanism to convert linear motion into rotary motion, thereby driving the valve shaft to rotate.

[0003] Normally, at room temperature, the pneumatic actuator of a butterfly valve can drive the valve plate to rotate normally. However, when butterfly valves are used in high-temperature conditions, the valve plate and valve body materials are prone to varying degrees of thermal expansion and contraction due to differences in their coefficients of thermal expansion or uneven heating. This phenomenon results in significant frictional resistance between the valve plate and valve seat when the valve is closed, due to the interference fit. Furthermore, when the actuator receives an opening command, the resistance that needs to be overcome in the initial operation phase far exceeds the design starting torque under normal operating conditions.

[0004] Traditional solutions involve increasing the overall output torque margin of the actuator to ensure the valve can be forcibly opened even in high-temperature environments. However, increasing the actuator size doesn't guarantee immediate valve plate rotation in the initial stage. Compressed air continues to act on the piston, causing the actuator internals to accumulate energy. Once the accumulated energy reaches the maximum static friction force caused by thermal expansion, the valve plate rotates at extremely high speed, causing the valve opening to momentarily exceed the preset opening before rebounding to the target opening. This violent movement generates significant impact loads on the valve components, easily causing equipment damage and posing safety hazards. Furthermore, once the valve is normally open, the actual required torque is greatly reduced. Configuring a high-torque actuator to continue outputting high torque during the opening phase results in unnecessary waste and subjects the transmission mechanism and actuator internals to unnecessary mechanical stress, reducing equipment lifespan. Utility Model Content

[0005] The purpose of this invention is to provide a pneumatic actuator with a fork, which adopts a multi-cylinder design to adapt to the torque load requirements of the actuator in high-temperature environments. It provides sufficient high torque in the initial stage of opening to effectively solve the problem of thermal jamming, and then quickly reduces the output torque to the torque required for rotation, thereby improving the safety, reliability and energy efficiency of the actuator.

[0006] The purpose of this utility model is achieved as follows:

[0007] A dual-cylinder pneumatic actuator includes a housing, with end caps and cylinders fixed to both sides of the housing. A shift fork output shaft and a horizontally positioned guide rod are movably connected inside the housing. The piston rod of the cylinder extends into the housing and is parallel to the guide rod. A slider that slides along the guide rod is fixed to the end of the piston rod. A shift fork is axially fixed to the shift fork output shaft, and a limit groove is formed on the shift fork. A guide slider transmission assembly is rotatably connected to the slider. When the piston rod drives the slider to move, the guide slider transmission assembly slides along one end of the limit groove to the other end, realizing the shift fork output shaft... The cylinder is rotated and includes a first cylinder and a second cylinder arranged sequentially on one side of the housing. The first cylinder contains a first piston, and the piston rod is axially fixed to the middle of the first piston. The second cylinder contains a second piston, and an outer piston rod coaxial with the piston rod is axially fixed to the middle of the second piston. The end of the outer piston rod extends into the first cylinder. When the first piston moves to the outer end, the middle of the first piston abuts against the end of the outer piston rod. The first cylinder has a first air port and a second air port on both sides, and the second cylinder has a third air port and a fourth air port on both sides.

[0008] The present invention is further configured such that the outer cylinder wall of the first cylinder and the inner cylinder wall of the second cylinder are a shared structure, and the outer cylinder wall of the first cylinder is provided with a second air port connected to the end of the first cylinder and a fourth air port connected to the end of the second cylinder.

[0009] The present invention is further configured to include a gas path structure, which includes a main gas source. The main gas source is connected to a first gas path and a second gas path via a solenoid valve. The first gas path is connected to a first gas port and a third gas port via a three-way valve. The second gas path is connected to the third gas port.

[0010] The present invention is further configured such that a limiting protrusion is provided on the outer side of the outer cylinder wall of the first cylinder, and when the second piston moves to the end through the third air port, the end of the second piston abuts against the limiting protrusion.

[0011] The present invention is further configured such that a first through hole is provided at the end of the first cylinder for the piston rod to extend out, and a second through hole is provided at the end of the second cylinder for the outer piston rod to extend into the first cylinder. A piston rod sealing ring is provided on the inner wall of both the first through hole and the second through hole.

[0012] The present invention is further configured such that piston sealing rings are fixed on the outer walls of both the first piston and the second piston.

[0013] The outstanding and beneficial technical effects of this utility model compared to the prior art are:

[0014] 1. The dual-cylinder actuator provided by this utility model adopts a multi-cylinder design. In the initial stage where high torque is required, the pistons of the two cylinders can simultaneously provide thrust, giving the piston rod double the thrust, thereby driving the slider and rotating the output shaft of the shift fork. This addresses the problem of valve plate rotation difficulties at high temperatures. Furthermore, after the piston of the second cylinder reaches its maximum stroke distance, the piston rod can only be driven by the first cylinder, reducing torque output and thus reducing energy consumption. At the same time, the effective stroke range in the initial stage reduces violent movements and minimizes damage to the equipment.

[0015] 2. In this utility model, the first cylinder and the second cylinder adopt a common cylinder wall structure, and the overall structure is simple to install and easy to disassemble and install.

[0016] 3. The air passage structure provided by this utility model includes two air passages. One air passage can simultaneously provide power to the first piston and the second piston of the dual cylinders, enabling the dual cylinders to be driven stably at the same time. The other air passage provides an intake function for the second air port, realizing the piston reset effect of the first cylinder and air pressure buffering.

[0017] 4. Furthermore, this utility model provides sealing rings in the first through hole, the second through hole, and on both pistons to provide effective sealing for the operation of each cylinder.

[0018] 5. In this utility model, the first piston and the second piston adopt different stroke distance ratios to achieve high torque output of the valve plate within a fixed angle range. Attached Figure Description

[0019] Figure 1 A schematic diagram of the structure of the box body of this utility model;

[0020] Figure 2 This is a cross-sectional structural diagram of the present invention. Figure 1 ;

[0021] Figure 3 This is a cross-sectional structural diagram of the present invention. Figure 2 ;

[0022] Figure 4 This is a cross-sectional structural diagram of the present invention. Figure 3 ;

[0023] Figure 5 This is a schematic diagram of the gas path structure of this utility model;

[0024] Figure label:

[0025] 1-Box body; 10-End cover; 11-Shift fork output shaft; 12-Guide rod; 13-Shift fork; 130-Limit slide groove;

[0026] 2-First cylinder; 20-Piston rod; 21-Slider; 210-Guide slider transmission assembly; 22-First piston; 23-First air port; 24-Second air port; 25-Limiting protrusion; 26-First through hole;

[0027] 3-Second cylinder; 30-Second piston; 31-Outer piston rod; 32-Third air port; 33-Fourth air port; 34-Second through hole;

[0028] 4-Main air source; 40-Solenoid valve; 41-First air path; 42-Second air path; 43-Three-way valve. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. See also: Figure 1 — Figure 5 :

[0030] A dual-cylinder pneumatic actuator includes a housing 1, with end caps 10 and cylinders fixed to both sides of the housing 1. A shift fork output shaft 11 and a horizontally positioned guide rod 12 are movably connected inside the housing 1. The piston rod 20 of the cylinder extends into the housing 1 and is parallel to the guide rod 12. A slider 21, which slides along the guide rod 12, is fixed to the end of the piston rod 20. A shift fork 13 is axially fixed to the shift fork output shaft 11, and a limiting groove 130 is formed on the shift fork 13. A guide slider transmission assembly 210 is rotatably connected to the slider 21. When the piston rod 20 drives the slider 21 to move, the guide slider transmission assembly 210 slides along one end of the limiting groove 130 to the other end, realizing the movement of the shift fork output shaft 11. The rotation of 1 is characterized in that the cylinder includes a first cylinder 2 and a second cylinder 3 sequentially arranged on one side of the housing 1. A first piston 22 is provided in the first cylinder 2, and the piston rod 20 is axially fixed to the middle of the first piston 22. A second piston 30 is provided in the second cylinder 3. An outer piston rod 31 coaxial with the piston rod 20 is axially fixed to the middle of the second piston 30, and the end of the outer piston rod 31 extends into the first cylinder 2. When the first piston 22 moves to the outer end, the middle of the first piston 22 abuts against the end of the outer piston rod 31. A first air port 23 and a second air port 24 are provided on both sides of the first cylinder 2. A third air port 32 and a fourth air port 33 are provided on both sides of the second cylinder 3.

[0031] During implementation, such as Figure 1 As shown, the housing part on one side of the actuator is the same as the traditional structure. The piston rod 20 drives the slider 21 to move laterally. The guide slider transmission assembly 210 at the end of the slider slides along the limiting slide groove 130 during the lateral movement, thereby realizing the effect of rotating the output shaft of the shift fork. The output shaft 11 of the shift fork can directly drive the rotation of the valve plate to realize the opening and closing of the valve plate in the butterfly valve.

[0032] In the aforementioned structure, the cylinder structure on the other side of the actuator drives the piston rod. The piston rods in the first and second cylinders, as well as the outer piston rod, are simultaneously supplied with air, generating double the output to the piston rod. This significantly increases the initial torque and effectively addresses the large maximum static friction force generated by thermal expansion of the valve plate in high-temperature operating environments. Furthermore, when the piston in the second cylinder reaches its maximum stroke, the end of the outer piston rod 31 no longer abuts against the end of the first piston 22, allowing subsequent torque output to be driven solely by the first cylinder 2, reducing torque waste.

[0033] and Figure 2 This is a schematic diagram of the piston rod in its initial state. Figure 3 This is a schematic diagram of the structure when the outer piston rod pushes the piston rod to move. Figure 4This is a schematic diagram of the structure where the end of the outer piston rod is separated from the first piston.

[0034] Preferably, the outer cylinder wall of the first cylinder 2 and the inner cylinder wall of the second cylinder 3 share a common structure, and the outer cylinder wall of the first cylinder 2 is provided with a second air port 24 connected to the end of the first cylinder 2 and a fourth air port 33 connected to or not connected to the end of the second cylinder 3.

[0035] In the above structure, the four air ports enable the normal operation of the first cylinder and the second cylinder, and facilitate the normal left and right sliding of the first piston and the second piston.

[0036] In addition, if the outer cylinder wall of the first cylinder is not connected to the fourth air port 33, the fourth air port is opened on the side cylinder wall at the inner end of the second cylinder.

[0037] Preferably, it also includes an air path structure, which includes a main air source 4. The main air source 4 is connected to a first air path 41 and a second air path 42 through a solenoid valve 40. The first air path 41 is connected to a first air port 23 and a third air port 32 through a three-way valve 43. The second air path 42 is connected to the third air port 32.

[0038] During implementation, such as Figure 5 As shown, the main air source serves as the air source for both cylinders. The first air passage 41 is divided into two air passages through the three-way valve 43, and the same air pressure is input to the first air port 23 and the third air port 43. The piston rod 20 provides double the torque through the push of the outer piston rod 31; the second air passage 42 and the second air port 24 provide positive or negative pressure gas.

[0039] In the above structure, a certain positive pressure gas is provided at the second air port 24, so that the first piston will have a reverse buffering force during the driving process, reducing component damage; in another case, the second air port 24 provides a larger air pressure, and at this time the first air passage no longer provides air pressure, thereby realizing the reset of the first piston. During the reset process, the second piston is also driven to reset.

[0040] Preferably, a limiting protrusion 25 is provided on the outer side of the outer cylinder wall of the first cylinder 2. When the second piston 30 moves to the end through the third air port 32, the end of the second piston 30 abuts against the limiting protrusion 25 for buffering.

[0041] In the above structure, the limiting protrusion can effectively abut and buffer the second piston 30, prevent the second piston from adhering to the side wall of the second cylinder, and also reduce the wear on the second piston.

[0042] Preferably, the end of the first cylinder 2 is provided with a first through hole 26 for the piston rod 20 to extend out, and the end of the second cylinder 3 is provided with a second through hole 34 for the outer piston rod 31 to extend into the first cylinder 2. Piston rod sealing rings are provided on the inner walls of both the first through hole 26 and the second through hole 34.

[0043] Preferably, piston sealing rings are fixed to the outer walls of both the first piston 22 and the second piston 30.

[0044] In the above structure, both the piston rod seal and the piston seal provide a better sealing effect for the moving piston and piston rod, ensuring the airtightness of the cylinder.

[0045] During implementation, the valve plate typically rotates at an angle of 90°, with 0° to 90° corresponding to the first piston moving from its initial stage to its maximum stroke. Under thermal expansion conditions, the first 15° of rotation usually requires a large torque. The stroke distance of the second piston 30 corresponds to approximately the first 15° of the stroke range, providing sufficient torque.

[0046] The above embodiments are merely preferred embodiments of the present utility model and are not intended to limit the scope of protection of the present utility model. Therefore, all equivalent changes made to the structure, shape, and principle of the present utility model should be covered within the scope of protection of the present utility model.

Claims

1. A double-cylinder pneumatic actuator, comprising a box (1), end covers (10) and cylinders fixed on both sides of the box (1), a shift fork output shaft (11) and a transverse guide rod (12) movably connected inside the box (1), a piston rod (20) of the cylinder extending into the box (1) and parallel to the guide rod (12), a slider (21) fixed on the end of the piston rod (20) and sliding along the guide rod (12), a shift fork (13) axially fixed on the shift fork output shaft (11) and provided with a limiting sliding groove (130), a guide slider transmission assembly (210) rotatably connected on the slider (21), when the piston rod (20) drives the slider (21) to move, the guide slider transmission assembly (210) slides along one end of the limiting sliding groove (130) to the other end, so as to realize the rotation of the shift fork output shaft (11), characterized in that, The cylinder comprises a first cylinder (2) and a second cylinder (3) arranged in sequence on one side of the cylinder block (1), the first cylinder (2) is provided with a first piston (22), and the piston rod (20) is axially fixed to the middle part of the first piston (22), the second cylinder (3) is provided with a second piston (30), the middle part of the second piston (30) is axially fixed with an outer piston rod (31) coaxial with the piston rod (20), and the end part of the outer piston rod (31) extends into the first cylinder (2), when the first piston (22) moves to the outer end, the middle part of the first piston (22) abuts against the end part of the outer piston rod (31), the first cylinder (2) is provided with a first gas port (23) and a second gas port (24) on both sides, and the second cylinder (3) is provided with a third gas port (32) and a fourth gas port (33) on both sides.

2. A double cylinder pneumatic actuator according to claim 1, characterized in that The outer cylinder wall of the first cylinder (2) and the inner cylinder wall of the second cylinder (3) are of a common structure, and the second gas port (24) and the fourth gas port (33) are arranged on the outer cylinder wall of the first cylinder (2) and are connected with the end part of the first cylinder (2) and the end part of the second cylinder (3) respectively.

3. A double cylinder pneumatic actuator according to claim 2, characterized in that Further comprising a gas path structure, the gas path structure comprises a main gas source (4), the main gas source (4) is connected with a first gas path (41) and a second gas path (42) through an electromagnetic valve (40), the first gas path (41) is connected with the first gas port (23) and the third gas port (32) through a three-way valve (43), and the second gas path (42) is connected with the second gas port (24).

4. A double cylinder pneumatic actuator according to claim 2, characterized in that The outer side of the outer cylinder wall of the first cylinder (2) is provided with a limiting protrusion (25), when the second piston (30) moves to the end part through the third gas port (32) and is pressurized, the end part of the second piston (30) abuts against the limiting protrusion (25) to be buffered.

5. A double cylinder pneumatic actuator according to claim 1, characterized in that, The end part of the first cylinder (2) is provided with a first through hole (26) for the piston rod (20) to extend out, and the end part of the second cylinder (3) is provided with a second through hole (34) for the outer piston rod (31) to extend into the first cylinder (2), and the inner hole walls of the first through hole (26) and the second through hole (34) are both provided with a piston rod sealing ring.

6. A double cylinder pneumatic actuator according to claim 1 or 5, characterized in that The outer walls of the first piston (22) and the second piston (30) are both fixed with a piston sealing ring.

Images