Types and working principles of pneumatic actuators

Aug 23, 2019

Several questions about the type, function and working principle of the pneumatic actuator play a very important role as a common valve pneumatic actuator. There are mainly three different classifications.

Actuators are divided into three categories according to their energy form: pneumatic, electric and hydraulic. They have their own characteristics and are suitable for different occasions. Pneumatic actuators are a category in actuators. Pneumatic actuators can also be divided into single-acting and double-acting types. Double-acting actuators The actuator's switching action is driven by a gas source called DOUBLE ACTING. The selection of the double acting actuator is based on the DA series pneumatic actuator: The output torque of the gear bar actuator is obtained by multiplying the piston pressure (provided by the air supply pressure) by the pitch radius (force arm), as shown in Fig. 4. And the friction resistance is small and efficient. As shown in Figure 5, the output torque is linear when rotating clockwise and counterclockwise. Under normal operating conditions, the recommended safety factor for a double-acting actuator is 25-50%. Single-acting actuators SPRINGRETURN (single-acting) switching action is only the air source drive when the open action, and the spring reset when the action is closed. Taking the SR series pneumatic actuator as an example, in the application of spring return, the output torque is obtained in two different operating processes. According to the stroke position, two different torque values are generated for each operation. The output torque of the spring return actuator is multiplied by the force (air pressure or spring force) by the force arm. The output torque is obtained by the air pressure entering the middle cavity compression spring, which is called the "air stroke output torque". In this case, the source pressure forces the piston to move from 0 degrees to 90 degrees, and the reaction force is generated by the compression of the spring. The torque gradually decreases from the maximum value at the starting point until the second condition: the output torque is obtained by the spring restoring force acting on the piston when the middle cavity is out of gas, which is called "spring stroke output torque". In this case, due to the extension of the spring Long, the output torque is gradually decreasing from 90 degrees to 0 degrees. As mentioned above, the single-acting actuator is designed based on the generation of a balancing torque under two conditions. In each case, by varying the relationship between the number of springs on each side and the source pressure, it is possible to obtain an unbalanced torque, which is available in spring-return applications: out of gas or off. Under normal operating conditions, the recommended safety factor for spring return actuators is 25-50%.