As a power device, actuators integrate pneumatics, hydraulics, control, electromechanical, computer, and communications technologies to precisely control the position of controlled objects quickly and stably. They are not only used to drive and control various valves, but are also widely used in numerous applications requiring power in fields such as electricity, water conservancy, metallurgy, papermaking, aerospace, pipelines, petrochemicals, industrial equipment, and food processing.
Actuators can be categorized by the type of power source used: pneumatic, electric, and electro-hydraulic.
Electro-hydraulic actuators integrate a control module and a hydraulic power module and are available in linear and angular versions. The control module issues commands to an intelligently controllable motor or servo valve, which controls the hydraulic power module to output force (or torque) in the form of linear displacement (or angular displacement), thereby driving the controlled object. Displacement feedback is used to complete the regulation process, enabling various functional control functions.
At present, the most commonly used electro-hydraulic actuators on the market can generally be divided into two types: one is the servo valve controlled electro-hydraulic actuator, that is, the traditional electro-hydraulic servo actuator, which usually adopts an open-circuit hydraulic system and adjusts the flow direction and flow rate of the hydraulic oil by controlling the servo valve to achieve regulation of the controlled object, such as the German Reineke electro-hydraulic actuator; the other is the motor controlled electro-hydraulic actuator, which adopts a closed-circuit hydraulic system and controls the direction and speed of the stepper motor or servo motor to control the output direction and flow rate of the bidirectional pump pressure oil to precisely control the controlled object, such as the American REXA and other electro-hydraulic actuators.