How do electric valves work
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Introduction
Electric valves are key control components in modern automation systems. They use electrical energy to drive valve movements to achieve automatic control of liquid or gas flow. This article will analyze its working principle in detail, from structural composition to driving method to control logic, analyzing it layer by layer to help readers truly understand "how electric valves work."
An electric valve is actually an ordinary valve with an electric motor added to it. Ordinary valves need to be opened and closed by hand; while electric valves have an "actuator", which is an electric device. When an electrical signal is sent, it will automatically rotate to open or close the valve. In this way, the system can automatically control the direction and speed of the fluid without the need for human operation, which greatly saves manpower and improves efficiency.
Electric valves are composed of two parts: electric actuator (that is, electric motor plus control module) and valve body. The valve body is the component responsible for controlling the flow of fluid, such as our common ball valves, gate valves, butterfly valves, etc.; the actuator is responsible for "driving" the movement of the valve body. They are connected through a shaft. When the electric part turns, the valve will follow.
This step is key. When the control system (such as PLC) sends an electrical signal, the motor in the actuator starts to work. The motor drives the gear set or worm gear to generate a rotational torque. This torque will push the connected valve stem to rotate or move up and down, thereby opening or closing the internal components of the valve (such as the ball core and butterfly plate). This series of actions is just like when you manually open and close a valve, except now electricity is controlling everything.
Where does the "signal" to control the electric valve come from?
The electric valve is not always fully open or fully closed, it can be controlled to open half, a quarter, etc. This requires "signals" to regulate. There are usually two types of signals: one is a simple on/off signal, which tells the valve to "open to the end" or "close to the end"; the other is an analog signal, such as a 4~20 mA current signal, indicating the specific opening (such as 10%, 50%, 75%, etc.). After receiving the signal, the actuator will rotate to the specified position according to the command, and then use the built-in sensor to determine "whether it has been rotated." If it doesn't turn enough, it keeps moving until it reaches its target.
How does the valve know where it is "opened"?
In order to prevent excessive opening and closing of the valve or position deviation, electric valves are usually equipped with mechanical limit devices and position feedback systems. The limit device can automatically cut off power when the valve reaches the fully open or fully closed position to prevent damage to the motor or valve core caused by excessive rotation; while the position feedback system monitors the valve opening in real time through potentiometers, encoders and other components, and feeds the data back to the control center. In this way, the system can make the next adjustment according to the actual status, making the entire control process form a closed loop. With this mechanism, the electric valve can not only open and close, but also "know where it has opened."
The essence of electric valves is to use "motor drive + control signal + feedback system" to replace manual operation to achieve automated and precise control of the fluid system. Its emergence has greatly promoted the intelligent development of various industrial and civil systems.
