A pneumatic piston type long-stroke actuator

Abstract

The present invention discloses a pneumatic piston type long-stroke actuator. The device includes a protective box, inside which a bracket is arranged. The bracket is disposed on an actuator base, and a cylinder base is arranged at the bottom of the bracket. The cylinder base is connected to the bottom of the cylinder through a pin shaft. An air path conversion valve, an electronic switch, a smart valve positioner, a solenoid valve, and a terminal block are arranged on the bracket. The present invention can solve the problems that when the lubricating oil in the cylinder freezes in extremely cold weather in winter for the current pneumatic piston type long-stroke actuator, the cylinder cannot be disengaged in time, resulting in the inability to perform manual operation even when the actuator is switched to manual. At the same time, for an actuator with only one set of manual and automatic operation devices, when a failure occurs and the actuator is switched to the manual state, it is impossible to accurately and timely find and judge the cause of the failure. Moreover, after the valve positioner of the actuator is replaced, it is impossible to perform full-stroke parameter setting, debugging, and no-load test of the valve positioner online, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of instrument automatic control, and particularly relates to a pneumatic piston type long-stroke actuator. Background Art

[0002] The pneumatic piston type long-stroke actuator uses compressed air or nitrogen as the power air source, accepts the 4-20 mA standard current signal given by a regulator (computer) or manually, and converts it into a displacement (angular displacement or linear stroke displacement) corresponding to the input signal, which is used to adjust the opening degrees of various valves and baffles in the process pipeline, so as to achieve the purpose of controlling various process parameters. The main body of the pneumatic piston type long-stroke actuator commonly used in China at present consists of a cylinder, a bracket, and a valve positioner, and the auxiliary system only has a set of manual and automatic operation devices. In the actual use process, when a failure occurs in the cylinder of the pneumatic piston type long-stroke actuator or the electrical valve positioning, the following problems mainly exist in the pneumatic piston type long-stroke actuator using the existing technology:

[0003] 1. In extremely cold weather in winter, the pneumatic piston type long-stroke actuator is prone to the freezing of the lubricating oil in the cylinder, resulting in the inability of the cylinder to move. At this time, the cylinder cannot be disengaged in time, and the actuator cannot be manually operated even when switched to manual.

[0004] 2. When a failure occurs in the actuator with only a set of manual and automatic operation devices, in order to ensure production, the actuator is often switched to manual first. At this time, the working air source of the actuator system is completely cut off, and the air sources of the upper and lower cylinders are connected, which brings inconvenience to further fault judgment and makes it impossible to accurately and timely find and judge the cause of the fault.

[0005] 3. After the valve positioner of the actuator is replaced, it is impossible to perform full-stroke parameter setting, debugging, and no-load test of the valve positioner online.

[0006] 4. During the online parameter setting and debugging of the valve positioner, the actuator must be completely disengaged from the load and the process medium valve must be fixed. At this time, it is impossible to use the manual device of the actuator to control the process parameters.

[0007] 5. During the replacement of the valve positioner, the production post needs to cooperate to fix the process medium valve, which affects the adjustment of process parameters and even forces the production to stop. Moreover, the fault handling time is long and the risk factor is high.

[0008] 6. The existing pneumatic piston type long-stroke actuator has low integration and single function. When the process requires the actuator to be in a certain position for a long time, it is impossible to test and diagnose the functions of the actuator online. Summary of the Invention

[0009] In view of the above technical problems, the present invention provides a pneumatic piston type long-stroke actuator. In the current pneumatic piston type long-stroke actuator, when the lubricating oil in the cylinder freezes in extremely cold weather in winter, the cylinder cannot be disengaged in time, so that the actuator cannot be manually operated even when switched to manual. At the same time, for an actuator with only one set of manual and automatic operation devices, when a failure occurs and the actuator is switched to the manual state, it is impossible to accurately and timely find and judge the cause of the failure. Moreover, after the valve positioner of the actuator is replaced, it is impossible to perform full-stroke parameter setting, debugging, no-load test, etc. of the valve positioner online.

[0010] In order to achieve the above object, the technical solution of the present invention is as follows:

[0011] A pneumatic piston type long-stroke actuator includes a protective box. A bracket is arranged inside the protective box. The bracket is arranged on an actuator base. A cylinder base is arranged at the bottom of the bracket. The cylinder base is connected to the bottom of the cylinder through a pin shaft. An air path change valve, an electronic switch, an intelligent valve positioner, a solenoid valve, a terminal block, a self-locking valve and a pressure reducing filter are arranged on the bracket. The upper part of the bracket is horizontally installed with an output shaft through a bearing seat. An output crank is arranged at the tail end of the output shaft. The output shaft is connected to a cylinder crank through a switching component that can be manually operated and disengaged from the output shaft. The bottom of the cylinder crank is connected to the piston rod of the cylinder through a fork joint. The top of the cylinder crank is hinged to the top of a feedback link through a feedback bracket. The bottom of the feedback link is hinged to a positioner feedback rod on the intelligent valve positioner. A worm gear is installed on the output shaft through short key fitting. The worm gear is connected to a handwheel through a clutch component operated by a manual-automatic switching handle.

[0012] The switching component includes a bushing installed on the output shaft through long key fitting. A flange a, a spring, a pin shaft sleeve, a fixed disk, a cylinder crank and a flange b are sequentially arranged on the bushing. A groove is arranged on the outer wall of one end of the pin shaft sleeve. A fixed pin is arranged at the other end of the pin shaft sleeve. The fixed pin passes through a pin hole on the fixed disk and penetrates into a pin seat arranged on the cylinder crank. A pulling sub-component capable of axially moving the pin shaft sleeve towards the flange a is arranged outside the bushing. The pulling sub-component is connected to the groove in a matching manner.

[0013] The pulling sub-component includes a fixed link arranged on one side of the bushing, a link arranged on the other side of the bushing, and a movable link connected to the groove through a spherical plunger pin shaft. Two ends of the movable link are respectively hinged to one end of the fixed link and one end of the link through screws. The other end of the link is hinged to one end of a rotating plate. The other end of the rotating plate is fixedly connected to a rotating shaft arranged on a fixed seat. A load switching handle is arranged on the rotating shaft.

[0014] The bearing housing is fixedly installed on the bracket by bolts.

[0015] The beneficial effects of the present invention are as follows: The present invention designs and manufactures three sets of switching handles, namely a load switching handle to realize the separation and connection actions of the cylinder crank and the load, a gas path switching handle to flexibly realize the cutting-off and closing actions of the gas path, and a manual-automatic switching handle to realize manual operation and automatic actions. When the main components of the actuator (such as valve positioners, cylinder seals, and transmission parts) are damaged, rotate the manual-automatic switching handle and the load switching handle to the manual position respectively, so that the handwheel is connected to the turbine and the cylinder crank is disengaged from the output shaft. At this time, on the one hand, emergency manual operation can be carried out to ensure that the process parameters in the regulating loop remain unchanged, and on the other hand, fault inspection can be carried out; during the fault handling period, switch the gas path switching handle to the manual position. At this time, the upper and lower air inlet pipes of the cylinder are connected, and the working air source of the self-locking valve is cut off. After the fault handling of the actuator or the replacement of the main components is completed, switch the gas path switching handle to the automatic position, and full-stroke debugging and no-load tests can be directly carried out online without affecting the manual function, ensuring that the regulated action of the medium is not interrupted; when it is confirmed that the fault has been eliminated and the conditions for automatic operation are met, then switch the load switching handle and the manual-automatic switching handle to the automatic position to restore the automatic control function of the pneumatic piston type long-stroke actuator. Description of the Drawings

[0016] Figure 1 is the structural schematic diagram of the present invention.

[0017] Figure 2 is the connection relationship diagram of the load switching handle and the connecting rod.

[0018] Figure 3 is Figure 2 side view of.

[0019] Wherein, 1 - bushing, 2, 8 - flange, 3 - spring, 4 - pin bushing, 5 - fixed disk, 6 - cylinder crank, 7 - feedback bracket, 9 - long key, 10 - short key, 11 - worm gear, 12 - protective box, 13 - fixed connecting rod, 14 - bearing housing, 15 - output shaft, 16 - output crank, 17 - bolt, 18 - movable connecting rod, 19 - load switching handle, 20 - connecting rod, 21 - gas path switching handle, 22 - fork joint, 23 - gas path conversion valve, 24 - feedback connecting rod, 25 - manual-automatic switching handle, 26 - handwheel, 27 - electronic switch, 28 - intelligent valve positioner, 29 - positioner feedback rod, 30 - solenoid valve, 31 - bracket, 32 - terminal block, 33 - self-locking valve, 34 - cylinder, 35 - pressure reducing filter, 36 - pin shaft, 37 - cylinder base, 38 - actuator base, 39 - rotating plate, 40 - fixed seat, 41 - rotating shaft. Detailed Embodiments

[0020] To make the objectives, technical solutions, and advantages of the present invention more clear and understandable, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0021] As Figure 1 shown, a pneumatic piston type long-stroke actuator includes a protective box 12. A bracket 31 is arranged inside the protective box 12. The bracket 31 is arranged on an actuator base 38. A cylinder base 37 is arranged at the bottom of the bracket 31. The cylinder base 37 is connected to the bottom of a cylinder 34 through a pin shaft 36. An air path conversion valve 23, an electronic switch 27, an intelligent valve positioner 28, a solenoid valve 30, a terminal block 32, a self-locking valve 33, and a pressure reducing filter 35 are arranged on the bracket 31. The upper part of the bracket 31 is horizontally installed with an output shaft 15 through a bearing seat 14. An output crank 16 is arranged at the tail end of the output shaft 15. The output shaft 15 is connected to a cylinder crank 6 through a switching component that can be manually operated to disengage from the output shaft 15. The bottom of the cylinder crank 6 is connected to the piston rod of the cylinder 34 through a fork joint 22. The top of the cylinder crank 6 is hinged to the top of a feedback link 24 through a feedback bracket 7. The bottom of the feedback link 24 is hinged to a positioner feedback rod 29 on the intelligent valve positioner 28. A worm gear 11 is installed on the output shaft 15 through a short key 10 in a mating manner. The worm gear 11 is connected to a hand wheel 26 through a clutch component operated by a manual-automatic switching handle 25. When manual operation of the device is required, the clutch component is operated by the manual-automatic switching handle 25 to make the worm on the hand wheel 26 mesh with the worm gear 11. At this time, rotating the hand wheel 26 can achieve manual rotation of the output shaft 15.

[0022] As Figure 1 shown, the switching component includes a bushing 1 installed on the output shaft 15 through a long key 9 in a mating manner. A flange a2, a spring 3, a pin shaft sleeve 4, a fixed disk 5, a cylinder crank 6, and a flange b8 are sequentially arranged on the bushing 1. A groove is arranged on the outer wall of one end of the pin shaft sleeve 4. A fixed pin is arranged at the other end of the pin shaft sleeve 4. The fixed pin passes through a pin hole on the fixed disk 5 and penetrates into a pin seat arranged on the cylinder crank 6. A pulling sub-component capable of axially moving the pin shaft sleeve 4 towards the flange a2 is arranged outside the bushing 1. The pulling sub-component is connected to the groove in a mating manner.

[0023] As Figures 1-3As shown in the figure, the pulling sub-assembly includes a fixed connecting rod 13 disposed on one side of the bushing 1, a connecting rod 20 disposed on the other side of the bushing 1, and a movable connecting rod 18 connected to the groove through a spherical plunger pin shaft. Both ends of the movable connecting rod 18 are respectively hinged to one end of the fixed connecting rod 13 and one end of the connecting rod 20 by screws. The other end of the connecting rod 20 is hinged to one end of a rotating plate 39, and the other end of the rotating plate 39 is fixedly connected to a rotating shaft 41 disposed on a fixed seat 40. A load switching handle 19 is disposed on the rotating shaft 41.

[0024] As Figure 1 shown, the bearing housing 14 is fixedly mounted on the bracket 31 by bolts 17.

[0025] When the present invention is in use, the inlet of the pressure reducing filter 35 is connected to a gas source. The outlet pipeline of the pressure reducing filter is respectively connected to the gas source inlet of the intelligent valve positioner 28, and at the same time is connected to the gas source inlet of the solenoid valve 30 through the normally open valve of the gas path conversion valve 23. The outlet of the solenoid valve 30 is connected to the air pressure detection port of the self-locking valve 33. The two output pneumatic signals P1 and P2 of the intelligent valve positioner are respectively connected to the input interfaces IN1 and IN2 of the self-locking valve. The output interfaces OUT1 and OUT2 of the self-locking valve are respectively connected to the upper and lower cylinder head gas paths of the pneumatic piston type actuator cylinder 34 and both ends of the normally closed valve of the gas path conversion valve 23. The terminal block 32 is connected to the input signal, feedback signal, and power supply through a cable inlet.

[0026] The fixed disk 5 and the bushing 1 are integrally connected. The fixed disk 5 is connected to the pin bushing 4, the pin bushing 4 is connected to the spring 3, the spring 3 is connected to the flange disk a2, the flange disk a2 is connected to one end of the bushing 1, the flange disk b8 is connected to the other end of the bushing 1, the bushing 1 is connected to the output shaft 15 through a long key 9, the gas path switching handle 21 is connected to the gas path conversion valve 23, and the size of the protective box body 12 is 1500×750×580 mm in length×width×depth. Two connection ports are provided at the lower part of the protective box body 12, and a gas source inlet and a cable inlet are provided.

[0027] The inlet of the pressure reducing filter 35 is provided with a gas source inlet stop valve. The outlet gas pipeline of the pressure reducing filter 35 is respectively connected to the gas source inlet of the intelligent valve positioner 28, and at the same time is connected to the gas source inlet of the solenoid valve 30 through the gas path conversion valve 23. The maximum working pressure of the pressure reducing filter 35 is 1 MPa, the filtration accuracy is 5 μm, and the pressure regulation range is 0.1~0.8 MPa. The pressure reducing filter 35 filters particles larger than 5 μm in the nitrogen or compressed air gas source and reduces the pressure to 0.4~0.6 MPa. The gas source inlet stop valve can be used to cut off the pressure source when overhauling or replacing the pressure reducing filter 35.

[0028] The maximum pressure that the gas path conversion valve 23 can withstand is 1 MPa. It is opened when manually operating the pneumatic piston actuator. On the one hand, the normally closed valve opens to connect the upper and lower cylinder gas paths. On the other hand, the normally open valve closes to cut off the air source of the self-locking valve, protecting the self-locking valve and cutting off the air supply to the intelligent valve positioner, avoiding the inability to manually operate the pneumatic actuator due to air retention in the upper and lower cylinders.

[0029] The specification of the terminal block 32 is 10×1.5 mm. It realizes the signal connection of the power supply, input signal, feedback signal and the components inside the integrated protection box through the cable inlet. The solenoid valve 30 obtains power through the electronic switch 27, and the electronic switch 27 obtains power through the terminal block 32.

[0030] The working process of the pulling sub-assembly is as follows: Rotate the load switching handle 19, the load switching handle 19 drives the rotating shaft 41 to rotate, the rotating shaft 41 drives one end of the rotating plate 39 to rotate. Since the other end of the rotating plate 39 is hinged to the connecting rod 20, the connecting rod 20 will be pulled to move. And the connecting rod 20, the movable connecting rod 18 and the fixed connecting rod 13 form a planar connecting rod mechanism, so the movable connecting rod 18 and the fixed connecting rod 13 will move together, that is, the movable connecting rod 18 will pull the pin sleeve 4 to move axially in the direction of the flange a2, so that the fixed disk 5 is separated from the cylinder crank 6, realizing the separation action of the output shaft 15 and the actuator cylinder.

[0031] The working process of the present invention is as follows:

[0032] Connect a N2 or compressed air gas source with a pressure of 0.8 - 1.0 MPa from the outside. It enters the pressure reducing filter 35 through the gas source inlet stop valve. The pressure reducing filter 35 filters and reduces the gas source pressure to 0.4 - 0.6 MPa. The outlet gas source pipeline of the pressure reducing filter 35 is respectively connected to the gas source inlet of the intelligent valve positioner 28, and at the same time is connected to the air pressure detection port of the solenoid valve 30 through the gas path conversion valve 23; the outlet of the solenoid valve 30 is connected to the gas source inlet of the self-locking valve 33; the two output pneumatic signals P1, P2 of the intelligent valve positioner 28 are respectively connected to the input interfaces IN1, IN2 of the self-locking valve 33; the output interfaces OUT1, OUT2 of the self-locking valve 33 are respectively connected to the upper and lower cylinder head gas paths of the pneumatic piston actuator cylinder 34 and both ends of the normally closed valve of the gas path conversion valve 23; the intelligent valve positioner 28 distributes compressed air into the lower (upper) cavity of the cylinder 34 according to the increment of the input signal, and the upper (lower) cavity exhausts, so that the cylinder piston displacement drives the output shaft 15 to rotate, and the output crank 16 rotates to drive the load. The rotation increment of the output shaft 15 is transmitted to the feedback rod 29 of the intelligent valve positioner through the mechanical feedback connecting rod 24, so that the pneumatic piston actuator reaches the working position (i.e., the balance position) corresponding to the input signal and outputs a position feedback signal.

[0033] When a failure occurs during the normal operation of the actuator, first switch the manual-automatic changeover handle 25 and the pneumatic circuit changeover handle 21 to the manual position, and use the handwheel mechanism 26 for emergency manual operation; during the troubleshooting process, switch the load changeover handle 19 to the manual position to separate the load (output shaft 15) from the cylinder crank 6, and switch the pneumatic circuit changeover handle 21 to the automatic position. At this time, the positioner can still drive the cylinder for no-load operation, enabling quick fault judgment; during the fault handling process, switch the pneumatic circuit changeover handle 21 to the manual position to cut off the power source (pneumatic source), so that the fault handling and manual emergency operation do not affect each other; when parameter setting or full-stroke experiment is carried out after the fault handling is completed, switch the pneumatic circuit changeover handle 21 to the automatic position to restore the pneumatic circuit to normal, enabling on-line positioner parameter setting and actuator commissioning test. After confirming that the performance of the actuator has returned to normal, switch the load changeover handle 19 and the manual-automatic changeover handle 25 to the automatic position, and the actuator resumes the automatic regulation function.

[0034] Air source cut-off and position holding: It is mainly realized by the self-locking valve 33. Adjust the operating pressure of the pneumatic self-locking valve to the set value of 0.35 - 0.45 MPa. When the air pressure is higher than the set value, the self-locking valve opens, and the air paths leading to both ends of the pneumatic actuator cylinder 34 from the intelligent valve positioner 28 are connected, that is, the normal automatic working state. When the air pressure is lower than the set value, the self-locking valve locks, and the air paths leading to both ends of the cylinder 34 from the intelligent valve positioner 28 are cut off, maintaining the original position of the load and realizing air source cut-off and self-locking position holding.

[0035] Signal cut-off and position holding: It is realized by the electronic switch 27. The electronic switch can de-energize the solenoid valve 30 according to the value of the input signal, and then realize self-locking position holding through the self-locking valve 33. When the input signal current is greater than the lower limit current set by the electronic switch (3.5 mA), the electronic switch 27 conducts, and the solenoid valve 30 is energized, that is, the normal automatic working state. When the signal current is interrupted instantaneously, the electronic switch 27 blocks, and the solenoid valve 30 is de-energized, that is, the locked state.

[0036] Power cut-off and position holding: When the power supply is cut off, the solenoid valve 30 is de-energized, the control air source of the self-locking valve 33 is emptied, the self-locking valve 33 closes, and the air paths leading to both ends of the cylinder 34 are cut off, maintaining the original position of the load and realizing power cut-off and self-locking position holding.

[0037] It should be understood that the above specific embodiments of the present invention are only used for exemplary illustration or explanation of the principle of the present invention, and do not constitute a limitation to the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention shall be included within the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modification examples that fall within the scope and boundary of the appended claims, or equivalent forms of such scope and boundary.

Claims

1. A pneumatic piston type long-stroke actuator, characterized in that: It includes a protective box (12). Inside the protective box (12), a bracket (31) is provided. The bracket (31) is arranged on an actuator base (38). At the bottom of the bracket (31), a cylinder base (37) is provided. The cylinder base (37) is connected to the bottom of a cylinder (34) through a pin shaft (36). On the bracket (31), an air path conversion valve (23), an electronic switch (27), a smart valve positioner (28), a solenoid valve (30), a terminal block (32), a self-locking valve (33), and a pressure reducing filter (35) are provided. At the upper part of the bracket (31), an output shaft (15) is horizontally installed through a bearing seat (14). At the tail end of the output shaft (15), an output crank (16) is provided. The output shaft (15) is connected to a cylinder crank (6) through a switching assembly that can be manually operated to disengage from the output shaft (15). The bottom of the cylinder crank (6) is connected to the piston rod of the cylinder (34) through a fork joint (22). The top of the cylinder crank (6) is hinged to the top of a feedback link (24) through a feedback bracket (7). The bottom of the feedback link (24) is hinged to a positioner feedback rod (29) on the smart valve positioner (28). A worm gear (11) is installed on the output shaft (15) through a short key (10) in a mating manner. The worm gear (11) is connected to a handwheel (26) through a clutch assembly operated by a manual-automatic switching handle (25) in a mating manner; The switching assembly includes a bushing (1) installed on the output shaft (15) through a long key (9) in a mating manner. On the bushing (1), a flange a (2), a spring (3), a pin bushing (4), a fixed disk (5), a cylinder crank (6), and a flange b (8) are sequentially arranged. On the outer wall of one end of the pin bushing (4), a groove is provided. At the other end of the pin bushing (4), a fixed pin is provided. The fixed pin passes through a pin hole on the fixed disk (5) and penetrates into a pin seat arranged on the cylinder crank (6). On the outside of the bushing (1), a pulling sub-assembly capable of axially moving the pin bushing (4) towards the flange a (2) is provided. The pulling sub-assembly is connected to the groove in a mating manner; The bearing seat (14) is fixedly installed on the bracket (31) through bolts (17).

2. The pneumatic piston type long-stroke actuator according to claim 1, characterized in that: The pulling sub-assembly includes a fixed link (13) arranged on one side of the bushing (1), a link (20) arranged on the other side of the bushing (1), and a movable link (18) connected to the groove through a spherical plunger pin shaft. The two ends of the movable link (18) are respectively hinged to one end of the fixed link (13) and one end of the link (20) through screws. The other end of the link (20) is hinged to one end of a rotating plate (39). The other end of the rotating plate (39) is fixedly connected to a rotating shaft (41) arranged on a fixed seat (40). A load switching handle (19) is arranged on the rotating shaft (41).

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