| The electro-hydraulic servo system is a complex structure and much coupled system ,which synthesized the merit of the mechanical technology , electric technology and hydraulic technology and has been an important component in the control field. The system possesses some important features, such as great power, quick response, and high precision and so on, it has widely been used in the field of the industrial product And the electro-hydraulic servo valve is a key component for the system, which is the position with a highest fault rate in the system, its using condition and performance is bad or not directly influences the system performance. Consequently, the important problem now is how to research a really feasible method for intelligent fault diagnosis and use this method to predict , control the potential fault of the electro-hydraulic servo valve or rightly and quickly diagnose the happened fault and support the feasible method for elimination the happened fault.This paper studies in depth the key technology of the electro-hydraulic servo valve, on the base of collecting broadly the relate literature and works, combined with the theories of modern fault diagnosis , recognizing the fault model , artificial intelligence and computer science, which relies on a new kind electric-hydraulic static-dynamistic character test station.1. Antipollution research of the electro-hydraulic servo valve is proposed. The antipollution capability of electro-hydraulic servo valve is not well for the sake of its pilot valve's fixed throttle. In general, the fixed throttle's diameter is too small and is easily to be jammed. In the paper, the author establishes the electro-hydraulic servo valve's simulation model by using the software AMESim. We simulate by changing the two fixed throttle diameter and adding two throttle separately in series with the fixed two throttle and adding two throttle separately in parallel with the fixed two throttle. By analyzing the simulation curves , we can draw a conclusion as follows: the capability antipollution of the valve can be improved by adding a throttle in front of the fixed throttle and increasing their diameter.2. The main fault mechanism of the electro-hydraulic servo valve is studied. The fault mechanism has been considered as the "deep knowledge" in the field of fault diagnosis. The study of the fault mechanism has been a key step for the fault diagnosis. The fault mechanism of the electro-hydraulic servo valve's main fault models, such as wearing , cavitation erosion, hydraulic lock, temperature rise and so on in this paper are studied , the measures to reduce all kinds of fault models of the electro-hydraulic servo valve are discussed and the thermal stress on how to affect the performances of the electro-hydraulic servo valve is analyzed.3. The fault simulation testing for the electro-hydraulic servo valve combined with thecondition of our lab is done. By using digital electric-hydraulic servo valve's test station, on the pressures of system such as 2MPa, 2.5MPa, SMPa, 3 .SMPa, 4MPa, 4.5MPa, SMPa, we can measure static character carves (pressure gain) of servo valve as the static characteristic parameters, in seven conditions of electric-hydraulic servo valve (normal condition , up or down springs fatigue fracture, one side of fixed throttle hole of the pilot valve being blocked , one side of seal of bearer of control chamber being damaged 1/12, 1/2 and wholly. In order to meet the neural network model's input requirements, at first the author processes the pressure gain curves, and then makes the discrete data between -1 and 1.4. The intelligent fault diagnosis' network framework for the electro-hydraulic servo valve is established. In this paper, the author combines an artificial neural network with the genetic algorithms and forms a new algorithm, GA-BP algorithm, and establishes a GA-ANN model for the intelligent fault diagnosis of the electro-hydraulic servo valve, which is used the features and virtues of ANN and GA. The model takes the advantages of traditi...
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