In modern industrial automation system, electric servo valve, as a high-precision fluid control element, is widely used in hydraulic servo system, especially in occasions that need high dynamic response and precise control, such as aerospace, robots, CNC machine tools and other fields. The core function of the electric servo valve is to control the flow in the hydraulic system through electrical signals, so as to realize accurate control of the position, speed and force of the actuator (such as hydraulic cylinder or hydraulic motor).
First, the basic structure and principle of electric servo valve
Electric servo valve usually consists of electromagnetic part and hydraulic part. Its working principle is that after a weak current or voltage signal is input, the electromagnetic part generates corresponding electromagnetic force to drive the valve core to move, thus changing the channel area of hydraulic oil and controlling the flow and direction of the oil.
Compared with ordinary proportional valve, electric servo valve has higher response speed, higher control accuracy and better linearity. It usually adopts a feedback closed-loop control structure, which can adjust the position of the valve core in real time and ensure that the output flow and the input signal maintain an accurate proportional relationship.
Second, the flow control mechanism of electric servo valve
1. Electronic control signal input
The electric servo valve receives the analog voltage or current signal output from the controller (such as PLC or motion controller). This signal represents the expected flow.
2. Electromagnetic drive valve core movement
The electrical signal is converted into electromagnetic force, which pushes the spool inside the servo valve to move. This displacement is accurately controlled by force feedback or position feedback system to ensure that the position of the spool is consistent with the input signal.
3. Control the flow of hydraulic oil
The position change of the valve core changes the opening of the valve port, and then controls the hydraulic oil flow through the valve port. The flow determines the movement speed of the hydraulic actuator.
4. Closed-loop feedback adjustment
Most electric servo valves have built-in position sensors (such as LVDT) or force feedback devices to form a closed-loop control system. The feedback signal is compared with the input signal, and the controller constantly adjusts the current of the electromagnetic coil to correct the error and ensure the high-precision control of the system.
III. Advantages and Challenges in Application
Advantages:
-High responsiveness and dynamic performance: suitable for rapidly changing working conditions and achieving millisecond response.
-High precision control: micron positioning control can be realized.
-Strong integration: easy to integrate with digital control system, supporting automation and intelligent control.
Challenge:
-Higher cost: compared with ordinary hydraulic valves, it is expensive.
-High requirement for oil cleanliness: the servo valve has precise internal structure and is easy to be stuck or worn due to impurities.
-Need a high-performance controller: In order to give full play to its performance, it needs to be equipped with high-precision sensors and high-speed processors.
Fourth, summary
As the core control element in the hydraulic servo system, the electric servo valve is indispensable in the high-precision and high-response industrial control system because of its ability to accurately control the hydraulic flow through electrical signals. With the development of intelligent manufacturing and industrial automation, the application of electric servo valve will be more extensive and will continue to evolve in the direction of higher precision and intelligence. For engineers and technicians, a deep understanding of its working principle and control mechanism is the key to realize efficient and reliable hydraulic control.