How do pneumatic actuators work

Pneumatic actuators are a key device widely used in the field of industrial automation. Their working principle is mainly based on the effect of gas pressure and the conversion of mechanical structure. When compressed air or other pressurized gas enters the chamber of the pneumatic actuator, a certain pressure will be formed in the chamber. The difference between this pressure and the resistance of the external environment or the inside of the actuator enables the piston, gear or other mechanical parts inside the actuator to move effectively when the pressure reaches a certain threshold. Depending on the design and application scenario of the actuator, this movement can be linear or circular.

The internal structure of the pneumatic actuator usually contains one or more chambers, which are effectively controlled by precise sealing and valve systems. When the gas enters a chamber, it pushes the piston or diaphragm in the chamber to move in the opposite direction. Through the transmission of mechanical parts such as connecting rods and gears, this movement is ultimately converted into rotation or linear motion at the output end of the actuator. For example, in a standard double-acting pneumatic actuator, when compressed air enters from the A pipe port, the gas pushes the double pistons to move linearly at both ends. The rack on the piston then drives the gear on the rotating shaft to rotate counterclockwise, thereby opening the valve. When compressed air enters from the B pipe port, the gas pushes the double pistons to move linearly in the middle, and the rack on the piston drives the gear on the rotating shaft to rotate clockwise to close the valve. This transmission principle is not only simple in structure, but also has high reliability and stability.

In addition to double-acting pneumatic actuators, single-acting pneumatic actuators are also an important part of pneumatic technology. Single-acting pneumatic actuators usually have only one air chamber, one of their switching actions is driven by the air source, and the other action depends on the reset of the spring. This design enables the single-acting pneumatic actuator to maintain a certain position or state without the need for continuous air supply, thereby effectively saving energy and reducing costs.

The working principle of pneumatic actuators also involves the compressibility and fluid dynamics of gas. Due to the high compressibility of gas, the smoothness of the movement of pneumatic actuators may be affected to a certain extent when the load is large. In order to improve the smoothness and precision of movement, some high-end pneumatic actuators use technologies such as gas-liquid damping cylinders to combine air cylinders with hydraulic cylinders. This combination can not only achieve smoother movement and higher precision, but also achieve adjustable and controllable speed.