In modern flight control system, the precise control of aircraft rudder surface is very important for flight stability and handling performance. As the core executive component of hydraulic system, servo valve undertakes the key task of transforming control signal into hydraulic power output. This paper will introduce how the control surface of aircraft can accurately adjust the motion of the control surface by controlling the servo valve.
First, the basic principle of servo valve
Servo valve is a high-precision hydraulic control valve, which can adjust the flow and pressure of hydraulic oil in proportion according to the input electrical or mechanical signals. It usually consists of torque motor, nozzle baffle mechanism and slide valve. Its working principle is to control the electromagnetic force through electrical signals, and then change the position of the valve core, so as to realize accurate control of the flow direction and flow rate of hydraulic oil.
Second, the linkage mechanism between rudder surface and servo valve
The control surfaces of aircraft (such as ailerons, elevators, rudders, etc.) are usually driven by hydraulic actuators, and servo valves are the core components to control the actions of actuators.
When the pilot or flight control computer sends a rudder deflection command, the control system will convert the command into an electrical signal and transmit it to the corresponding servo valve. According to the magnitude and direction of the signal, the servo valve adjusts the position of its internal spool, thus controlling the hydraulic oil to flow into or out of different cavities of the actuator. The pressure difference of hydraulic oil makes the piston of the actuator move and drives the rudder surface to deflect; When the predetermined angle is reached, the system adjusts the state of the servo valve through the feedback device to keep the rudder surface at the target position.
Third, the accuracy and response of servo valve control
Electro-hydraulic servo valves are widely used in modern aircraft for control, which have fast response, high control accuracy and good dynamic characteristics. Especially in the Fly-by-Wire system, the servo valve directly receives the digital signal from the flight control computer, which realizes more precise control of the rudder surface. In addition, servo valves are usually equipped with position or force feedback devices to form a closed-loop control system, thus further improving the stability and accuracy of control.
Fourth, the safety and redundancy design of servo valve system
Because the control of rudder surface is related to flight safety, the servo valve and its hydraulic system usually adopt redundant design. For example, a rudder surface may be driven by multiple independent servo valves and hydraulic circuits. Even if one loop fails, other loops can continue to work to ensure that the maneuverability of the aircraft will not be affected. At the same time, modern aircraft is also equipped with fault detection and isolation system, which can monitor the working state of servo valve in real time and find and deal with anomalies in time.
V. Conclusion
To sum up, the precise control of the servo valve on the aircraft rudder surface enables the aircraft to achieve stable and flexible control in a complex and changeable flight environment. As a key component of hydraulic control system, servo valve not only determines the speed and accuracy of the control surface, but also affects the flight safety and reliability to a great extent. With the continuous development of aviation technology, the future servo valve will also develop in the direction of higher response speed, lower energy consumption and stronger adaptability, which will bring better performance to the flight control system.