Fault diagnosis technology of Parker electro-hydraulic servo valve

Parker electro-hydraulic servo valve, as a key control component in modern industrial hydraulic system, is widely used in aerospace, heavy machinery, automated production lines and other fields. Its main function is to convert electrical signals into hydraulic output and realize high-precision control of actuators. However, in the long-term operation process, due to oil pollution, mechanical wear, aging of electrical components and other reasons, servo valves may have various failures, which affect the stability and control accuracy of the system. Therefore, it is particularly important to make effective fault diagnosis for Parker electro-hydraulic servo valve.

A, common fault types and causes

1. Decreased flow gain: slow response of servo valve or weak action of actuator. Common causes include slide valve wear, choke blockage, spring fatigue, etc.
　　. Zero drift: the servo valve still has output when there is no input signal, which leads to unstable system control. It is mostly caused by the stuck slide valve, aging of electromagnetic components or sensor drift.

3. Decreased response speed: the system response is lagging, which may be due to the failure of the electric drive module, abnormal feedback signal or increased internal leakage.

4. High-frequency oscillation or noise: usually caused by hydraulic oil pollution, internal component resonance or unstable control loop.

Second, the fault diagnosis method

1. Signal analysis method: By collecting and analyzing the input and output signals of the servo valve, the abnormal frequency components are identified by means of Fourier transform, and whether there is mechanical vibration or control instability is judged.

2. Pressure-flow test method: Install pressure sensors and flow meters at the inlet and outlet of the servo valve, and judge whether there is leakage, blockage or dynamic response decline by comparing the pressure-flow curves under standard working conditions.

3. Oil pollution detection: regularly sample and analyze the oil in the hydraulic system, detect the granularity and moisture content, and evaluate the potential damage to the servo valve.

4. Model-based fault diagnosis

Using the established mathematical model of servo valve, combined with the actual operation data, the state estimation and residual analysis are carried out to identify the degree of system deviation from the normal state.

5. Intelligent diagnosis technology

With the development of artificial intelligence, fault prediction system based on neural network, support vector machine and other algorithms is gradually applied to the health monitoring of servo valves. Through the training model of historical data, the early fault warning is realized.

III. Maintenance and Preventive Measures

In order to improve the reliability of the servo valve, a perfect maintenance system should be established, including cleaning the filter regularly, replacing the seal and calibrating the electrical parameters. At the same time, the training of operators should be strengthened to improve their perception of the operating state of servo valves.
　　IV. Conclusion

With the continuous improvement of industrial automation level, Parker electro-hydraulic servo valve plays a more and more important role in the system. Mastering its fault diagnosis technology can not only improve the operation efficiency of the equipment, but also reduce the maintenance cost and ensure the production safety. In the future, with the further integration of sensing technology and intelligent algorithm, online monitoring and intelligent diagnosis of servo valves will become the development trend.
　　(Word count: about 850 words)