As a key component in hydraulic control system, servo valve is widely used in industrial equipment with high precision and high response. Among them, the direct-acting servo valve is widely used in situations where the actuator needs to be directly driven because of its simple structure, fast response speed and high control accuracy. This paper will focus on the working principle, structural characteristics and how to realize direct drive of direct-acting servo valve.
First, the basic structure and working principle of direct-acting servo valve
Direct-acting servo valve is a hydraulic control valve that directly controls the displacement of the valve core through electromagnetic force. Its core structure includes electromagnetic coil, armature, spring, valve body and valve core. Its working principle is that when the input control current passes through the electromagnetic coil, electromagnetic force is generated to push the armature to drive the valve core to move, thus changing the flow direction and flow rate of hydraulic oil. Because there is no pilot stage amplification mechanism, the output flow and pressure of the direct-acting servo valve are completely controlled by electromagnetic force, with faster response speed and more direct control.
Second, why can the direct-acting servo valve realize direct drive?
Compared with the pilot servo valve, the direct-acting servo valve has no intermediate amplification link, so there is almost no delay between its control signal and the action of the actuator. This characteristic makes it very suitable for systems that need fast response and high dynamic performance, such as robots, precision machine tools, aerospace and other high-precision control systems.
In hydraulic system, direct-acting servo valve can directly control the action of hydraulic cylinder or hydraulic motor. By accurately controlling the current magnitude and direction of the electromagnetic coil, the closed-loop control of the position, speed and force of the actuator can be realized. This “direct drive” mode reduces unnecessary intermediate links in the system and improves the stability and control accuracy of the system.
In addition, the structure of direct-acting servo valve is relatively simple, and there is no pilot valve or nozzle baffle mechanism, so the requirement for oil cleanliness is relatively low and the maintenance cost is lower. This makes it more advantageous in some situations with harsh environment or inconvenient maintenance.
Third, the application example of direct-acting servo valve
In practical applications, direct-acting servo valves are often used to directly drive hydraulic servo cylinders or hydraulic motors. For example, in a CNC machine tool, the direct-acting servo valve can adjust the moving direction and speed of the hydraulic cylinder in real time according to the instructions of the CNC controller, so as to realize high-precision cutting; On the automatic assembly line, it can quickly and accurately control the trajectory of the manipulator, and improve the production efficiency and product quality.
Another typical application is in the flight control system, the pilot’s operating instructions are input into the servo valve through electrical signals, and then the deflection angle of the rudder surface is controlled, so as to realize the rapid adjustment of the aircraft attitude. This application requires extremely high response speed and reliability, and the direct-acting servo valve just meets these requirements.
IV. Conclusion
To sum up, the direct-acting servo valve has irreplaceable advantages in the hydraulic system that needs to directly drive the actuator because of its advantages of compact structure, rapid response, accurate control and convenient maintenance. With the increasing demand for efficiency and precision in modern industry, the application prospect of direct-acting servo valve will be broader. In the future, with the development of new materials and electronic control technology, the performance and reliability of direct-acting servo valves will be further improved, which will provide more powerful support for various high-precision hydraulic control systems.