Classification And Function Of Valve Actuator

According to different classification methods, the actuator of control valve has different classification.
(1) Classification by energy used
According to the energy used, the actuator is divided into pneumatic, electric, hydraulic and manual types.
Pneumatic actuator has a long history, low price, simple structure, stable performance, convenient maintenance and intrinsic safety, so it is widely used. According to the different components, the pneumatic actuator can be divided into diaphragm type, drum diaphragm type, bellows type, cylinder piston type, rack and pinion type, fork type and vane type, etc. The fine and small diaphragm actuator is a multi-spring pneumatic actuator introduced in recent years.
The electric actuator can be directly connected to the electric instrument or computer, and does not need the electrical conversion link. However, it is expensive and complex in structure, and explosion-proof and other issues need to be considered in application. According to the different working principles and applications, electric actuators can be divided into straight stroke, angular stroke, multi-rotation and electromagnetic actuators.
The hydraulic actuator has the advantage of large thrust (or thrust moment), but the device has large volume and complex flow path. It is often used in applications requiring large thrust (torque). Electro-hydraulic actuator converts electrical signals into hydraulic signals to push the actuator to move. The pneumatic-hydraulic actuator converts the pneumatic signal into the hydraulic signal to push the actuator to move. The hydraulic actuator is directly connected
Receive the hydraulic signal and push the actuator to move.
The manual actuator is often used in the process of actuator failure or startup and shutdown. The operator changes the flow area in the valve body through the manual actuator to change the fluid flow. It is usually used in conjunction with other actuators.
(2) Classified according to the moving direction of the actuator output
According to the moving direction of the actuator output, the actuator is divided into positive and negative acting actuators. The positive acting actuator is an actuator that can extend outward with the increase of input signal and return inward with the decrease of input signal. The reaction actuator is able to automatically extend outward as the input signal increases and the output rod retracts inward
Actuator.
(3) Classification by actuator output displacement type
According to the type of output displacement of the actuator, the actuator is divided into straight stroke actuator, angular stroke actuator and multi-rotation actuator. Straight stroke actuator outputs linear displacement. Angular stroke actuator outputs angular displacement. The magnitude of angular displacement is less than 360 ^. For example, the actuator of butterfly valve with a rotation angle of 90 ^ or 60 ". Multi-turn actuator and angular stroke actuator
Yes, but the angular displacement of rotation can be multiple turns.
(4) Classified by actuator action mode
According to the action mode of the actuator, the actuator is divided into continuous and discrete types. The output of the continuous type actuator is a continuously changing displacement signal. The output of discrete type actuator is the displacement signal of switch change. Solenoid valve is a common electric discrete control valve of Zui, and safety vent valve is also a common discrete control valve.
(5) Classified by actuator installation method
According to the installation method of the actuator, the actuator is divided into direct-mounted and side-mounted actuators. The direct-mounted actuator is directly installed on the regulating mechanism. The side-mounted actuator is installed on the side of the regulating mechanism, and it changes the position through a force amplifier
Direction of movement and force.
(6) Classification by type of actuator input signal
According to the type of input signal of the actuator, the actuator is divided into analog actuator and digital actuator. Analog actuators receive analog signals, such as 20~100kPa air pressure signal, 4~20mA standard current signal, etc. The digital actuator receives digital signals, usually a series of binary signals, to open and close the corresponding digital valve or adjust the opening of the control valve after digital to analog conversion. With the application of fieldbus technology, the actuators receiving fieldbus digital signals are being widely used.
(7) Classification according to the action characteristics of actuator output and input
According to the action characteristics of the output and input of the actuator, the actuator is divided into proportional type, proportional integral type and other types. There is a linear relationship between the output of the proportional actuator and the input signal. The output of the proportional and integral actuator is the sum of the proportional and integral effects of the input signal.