In modern industrial automation system, servo valve, as a high-precision and high-response hydraulic control element, is widely used in aviation, aerospace, machinery manufacturing, automated production lines and other fields. In order to ensure the efficient operation of the servo system, it is necessary to rely on measuring instruments to monitor and feedback the working state of the servo valve in real time. This feedback mechanism is the core part of the closed-loop control system, which directly affects the stability, accuracy and response speed of the system.
First, the basic working principle of servo valve
Servo valve is a device that accurately controls the flow and pressure of hydraulic oil according to the input electrical signal. It usually consists of electromagnetic torque motor, nozzle baffle mechanism and main valve core. When the control signal changes, the torque motor drives the baffle to change the back pressure of the nozzle, thereby controlling the displacement of the main valve core and adjusting the flow and direction of the oil, thus realizing the accurate control of the actuator (such as a hydraulic cylinder or a hydraulic motor).
Because the servo valve works in a high-speed, high-pressure and high-precision environment, its dynamic performance and working state must be monitored and fed back by measuring instruments.
Second, the role of measuring instruments in the servo system
In the servo control system, commonly used measuring instruments include:
1. Displacement sensor: used to detect the displacement of the actuator or the valve core, and convert physical quantities into electrical signals and feed them back to the controller.
2. Pressure sensor: Monitor the pressure change in the hydraulic system to prevent the system from being overloaded.
3. Flow sensor: It measures the liquid flow through the servo valve to optimize the control strategy.
4. Acceleration sensor and vibration sensor: used to analyze the dynamic characteristics of the system and identify abnormal vibration or unstable factors.
5. Temperature sensor: Monitor the temperature of hydraulic medium to avoid lubrication failure or seal damage caused by high temperature.
The data collected by these sensors are transmitted to the controller (such as PLC or special controller) through analog or digital signals, and compared with the set value, and the opening of the servo valve is adjusted after calculating the error, so as to realize closed-loop control.
Third, the practical application of feedback mechanism
In typical hydraulic servo systems, such as the feed system of CNC machine tools or the rudder control system of aircraft, the feedback mechanism is very important. Taking a numerical control machine tool as an example, in the machining process, the displacement of the feed shaft of the machine tool is measured in real time by a grating ruler or a magnetic grating ruler, the feedback signal is compared with the command signal, the error signal is sent to the controller for processing, and the controller then adjusts the opening of the servo valve and corrects the position of the actuator to ensure the machining accuracy.
In addition, the feedback of the servo valve can also be used to diagnose the system state. For example, if the data returned by the displacement sensor deviates greatly from the theoretical value, it may mean that the valve core is stuck, leaking or the control signal is abnormal. Through data analysis, the hidden trouble can be found in advance, and the reliability and maintainability of the system can be improved.
Fourth, the future development trend
With the development of Industry 4.0, the integration of measuring instruments and servo valves will be more intelligent. The new sensor has higher precision, faster response speed and stronger anti-interference ability; At the same time, the combination of Internet of Things (IoT) and edge computing technology can realize remote monitoring and predictive maintenance, and significantly improve the automation level and operation efficiency of the servo system.
tag
Measuring instrument plays the role of “sensing nerve” in servo valve control system, and its feedback signal is the key factor to realize high precision and high response closed-loop control. With the continuous progress of sensing technology and control theory, the future servo system will be more intelligent and efficient, providing strong support for industrial automation.