Pneumatic actuator with top mounted handwheel?
Introduction of pneumatic actuator
As we all know, actuator is one of the most important knowledge points in our life. However, in some textbooks or works, some knowledge points about actuator are worth discussing. Today we will give a brief description of pneumatic actuators in the actuator category.
The actuating mechanism and adjusting mechanism of the pneumatic actuator are a unified whole, and its actuating mechanism includes membrane, piston, fork and gear rack. The piston has a long travel, which is suitable for occasions with large thrust; The diaphragm travel is small and can only drive the valve stem directly. Fork type pneumatic actuator has the characteristics of large torque, small space, torque curve more in line with the valve torque curve, but it is not beautiful; Commonly used for high torque valves. The rack and pinion pneumatic actuator has the advantages of simple structure, stable and reliable operation, safety and explosion-proof. It is widely used in power plants, chemical industry, oil refining and other production processes with high safety requirements.
Working principle of pneumatic actuator
When the compressed air enters the pneumatic actuator from the nozzle of pipe a, the gas pushes the double pistons to move in a straight line along both ends (cylinder head end). The frame on the piston rotates the gear on the rotating shaft 90 degrees counterclockwise, and the valve opens. At this time, the gas at both ends of the pneumatic actuating valve is connected with pipe B. On the contrary, when the compressed air enters both ends of the pneumatic actuator from the mouth of valve B, the gas pushes the double plug straight to the middle, the rack on the piston drives the gear on the rotating shaft to rotate 90 degrees clockwise, and the valve is closed. At this time, the gas in the middle of the pneumatic actuator is discharged with nozzle A. The above is the standard transmission principle. According to the user's needs, the pneumatic actuator can be installed with the transmission principle opposite to the standard type, that is, select the shaft to rotate clockwise to open the valve and counterclockwise to close the valve. Pneumatic actuator spring reset type) The nozzle a of pneumatic actuator is the air inlet, and the nozzle B is the exhaust hole (the muffler B should be installed at the nozzle). The air inlet of nozzle A is an open valve, and the valve is closed by spring force when the air is cut off.
Basic composition of pneumatic actuator
The regulating mechanism type and structure of pneumatic actuators are roughly the same, mainly because the actuators are different. Therefore, when introducing the pneumatic actuator, it is divided into two parts: the actuator and the regulating valve. Pneumatic actuator is composed of two parts: actuator and regulating valve regulator). According to the size of the control signal, the corresponding thrust is generated to push the action of the control valve. The regulating valve is the regulating part of the pneumatic actuator. Under the thrust of the actuator, the regulating valve generates a certain displacement or angle to directly regulate the flow of fluid.
Characteristics of pneumatic actuator
1. Double piston gear is compact, rack structure, high meshing accuracy, high efficiency, and constant output torque.
2. Aluminum cylinder block, piston and end cover are lighter than actuators of the same specification and structure.
3. The cylinder body is made of extruded aluminum alloy, which is hard anodized, with hard inner surface and high strength. The sliding bearing is made of low friction materials to avoid direct contact between metals, with low friction coefficient, flexible rotation and long service life.
4. Install pneumatic actuator and valve. According to international standard connection size ISO5211.DIN3337 and VDI/VDE384545, it can be exchanged with ordinary pneumatic actuator.
5. The air supply hole complies with NAMUR standard.
6. The bottom shaft mounting hole of the pneumatic actuator (pneumatic actuator) is in double square shape according to ISO5211 standard, which is convenient for linear valve installation or 4511 standard angle installation.
7. The top and top holes of the output shaft are NAMUR compliant.
8. The adjusting screws at both ends can adjust the opening angle of the valve.
9. Double acting and single acting (spring return) with the same specification.
10. The direction can be selected according to the valve needs, clockwise or counterclockwise rotation.
11. Install solenoid valves, positioners (opening indication), loopers, limit switches and manual operating devices as required.
