As a key control component in hydraulic system, servo valve is widely used in industrial automation, aerospace, construction machinery and other fields. Its main function is to accurately control the movement of hydraulic actuator according to the input signal, and realize high-precision position, speed or force control. Sensitivity is a very important index in the performance parameters of servo valve, which directly affects the response speed and control accuracy of the system. Therefore, it is of great significance to adjust the sensitivity of servo valve reasonably to improve the performance of the system.
First, the definition of servo valve sensitivity
The sensitivity of servo valve usually refers to its ability to respond to changes in input signals. Specifically, it refers to the ability of the servo valve to control the hydraulic flow or pressure change under small input signal changes. Excessive sensitivity may lead to system instability and oscillation; However, if the sensitivity is too low, the response of the system will be slow and the control accuracy will decrease.
Second, the main factors affecting the sensitivity of servo valve
1. Characteristics of electro-hydraulic converter: such as response speed and linearity of torque motor or proportional electromagnet.
2. Valve core structure and clearance: The design, manufacturing accuracy and fit clearance of the valve core will affect its sensitivity.
3. Feedback mechanism: Servo valves usually have feedback devices (such as position feedback or flow feedback) to adjust and stabilize the output.
4. Cleanliness and temperature of hydraulic oil: Oil pollution or temperature change will affect the internal friction and viscosity of the valve, thus affecting the sensitivity.
5. System pressure and load fluctuation: the change of external load will also affect the control accuracy of servo valve.
Third, the adjustment method of
servo valve sensitivity
1. Adjust the electrical input signal
By adjusting the amplitude and frequency of input voltage or current, the action amplitude and response speed of servo valve can be changed. In practical application, PID controller is usually used to optimize the input signal to achieve more accurate control.
2. Adjust the mechanical feedback device
For servo valves with mechanical feedback, the sensitivity can be
indirectly adjusted by adjusting the length or angle of the feedback rod and changing the intensity of the feedback signal.
3. Replace or adjust the valve core clearance.
In some high-precision occasions, the sensitivity can be adjusted by replacing the spool with different clearance. The smaller the gap, the higher the sensitivity, but at the same time it will increase the risk of sticking.
4. Optimize hydraulic system parameters
Keeping the cleanliness and proper temperature of hydraulic oil, and choosing proper system pressure and pipeline layout are helpful to improve
the working stability of servo valve, thus indirectly improving its sensitivity performance.
5. Use intelligent control algorithm
In modern control system, advanced control strategies such as fuzzy control, adaptive control or neural network algorithm can dynamically adjust the sensitivity of servo valve to meet different working conditions.
Fourth, matters needing attention
When adjusting the sensitivity of servo valve, we should follow the principle of “low first and then high”, gradually improve the sensitivity, and monitor the stability of the system in real time. In the process of adjustment, the system oscillation or out of control caused by blindly improving the sensitivity should be avoided. At the same time, regular maintenance and inspection of the servo valve and its hydraulic system to ensure that it is in good working condition is a necessary measure to ensure long-term stability of sensitivity.
V. Conclusion
The adjustment of servo valve sensitivity is a highly technical work, involving hydraulic, electrical and mechanical aspects. Only on the basis of fully understanding the system characteristics and mastering the correct adjustment methods can the servo valve run efficiently and stably. With the development of intelligent control technology, the sensitivity adjustment of servo valve will be more intelligent and automatic, which will bring higher precision and reliability to industrial control system.