| High-pressure compressed air as work media that has some special advantages of pollution free, high power density, large dispensability, strong burst force, large temperature adaptability, and so on, has been applied to the aeronautics and astronautics domains, the armament scopes and the compressed air powered vehicles aspects. However, up to now, few systematic and detailed researches on parts and control systems of high pressure pneumatic have been done.Aimed at application of the high pressure pneumatic system in the aerospace auto distribution, principle and control methods of high pressure proportional valve are systematically investigated, all of which have significant theoretical and practical values, benefit to the development of the high pressure pneumatic system. The research work is divided into the following chapters:In chapter 1, the history and current researches on high-pressure valve of nationally and internationally are summarized. The origination and significance of this project are introduced. The main research objects are proposed in this chapter, and the major difficulties of this project are summarized.In chapter 2, a new type pneumatic proportional high-pressure valve is introduced. Details of its structure characteristics and mechanics are described. In the pilot valve, a proportional electro-magnet is used as pilot control component, and the control strategy of electric closed-loop feedback is adopted. Such a structure as pilot valve's series air-resistances is a special character of this valve. We analyze the factors that affect the valve's performances and point out that performances of proportional electro-magnet, volume of control chamber, area of pilot through-flow and diameter of pneumatic plunger's orifice are the major factors which determine on the valve's performances.In chapter 3, a nonlinear mathematical model of the valve is built up to analyze the influence of the structural parameters and controller parameters on the valve's dynamic characteristics. Based on the mathematical model, the state equations of this valve are got. And get an open-loop transfer function by liberalized. As a result, system's dynamical performances are related to the valve's structural parameters, the performance of proportional electro-magnet, the input pressure, the output pressure, working temperature and the main valve's spool's velocity.In chapter 4, Matlab's tools box Simulink is used to analyze the valve's performances. According to practical experimental conditions, input pressure is set at 15MPa. As a result, volume of control chamber and diameter of pneumatic plunger's orifice have great effect onsystem's dynamical performances. And the influence of the pilot valve's leakage on the performance of pneumatic pressure proportional valve is analyzed under the condition of the input pressure 31.5MPa. A method of using different widths of two throttle windows is proposed, which improves the working condition of pilot valve and reduces the influence of pilot's leakage.In chapter 5, the experimental system of high-pressure proportional valve is introduced. The dynamical characteristic, discharge characteristic and pressure characteristic of this valve are tested under the input pressure of 14MPa condition. As a result, this valve's output pressure ranges from 1MPa to 12MPa, when input pressure is 14MPa. And the control performance is robust when the loads changed from 4g/s to 120g/s. The results justify the simulation about valve's performances. Fixed parameters of PI controller can't meet the needs of control both in high output pressure and low output pressure. Volume of control chamber and diameter of pneumatic plunger's orifice have a great effect on system's dynamical performances.In chapter 6, the research work is summarized and perspectives on the future are presented.
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