Pneumatic actuators are actuators that use air pressure to drive the opening and closing or regulating valves. They are also called pneumatic actuators or pneumatic devices, but they are generally called pneumatic heads. The actuator and adjustment mechanism of the pneumatic actuator are a unified whole, and the actuators are membrane type, piston type, fork type and rack and pinion type. Pneumatic actuators can accept continuous air signals, output linear displacement, and some with the rocker arm, can output angular displacement. The movement speed is large, but the speed will be slower when the load increases. High reliability, but the valve can not be maintained after the gas source is interrupted (can be maintained after the retaining valve is added). It is inconvenient to realize segmentation control and program control, and has an explosion-proof function.
When the compressed air enters the pneumatic actuator from the A nozzle, the gas pushes the double piston to move linearly to the both ends (cylinder end), and the rack on the piston drives the gear on the rotating shaft to rotate counterclockwise by 90 degrees, and the valve is opened. . At this time, the gas at both ends of the pneumatically actuated valve is discharged with the B nozzle. Conversely, when the compressed air enters the two ends of the pneumatic actuator from the B-guest, the gas pushes the double plug to move linearly in the middle, and the rack on the piston drives the gear on the rotating shaft to rotate clockwise by 90 degrees, and the valve is closed. At this point, the gas in the middle of the pneumatic actuator is discharged with the A nozzle. The above is the standard transmission principle. According to the user's requirements, the pneumatic actuator can be installed in the opposite principle to the standard type, that is, the timing axis is rotated clockwise to open the valve, and counterclockwise to close the valve. Single-acting (spring-return type) pneumatic actuator A nozzle is the air inlet, and B nozzle is the air outlet (B nozzle should be installed with silencer). The inlet of the A nozzle is the opening valve, and the valve is closed by the spring force when the gas is cut off.