Research On The In-out Burst Pneumatic Control Valve

For its high power density and strong burst force, high-pressure compressed air and other characteristics, high-pressure air system is widely used in armament scopes,echo ranging and other fields. It is critical to determine the liquid level of the oil or gas well for oil mining. Because of complex structure and cannot be automatically controlled of the existing control valve for measuring well depth, a new pneumatic control valve is developed. Its principle and dynamic characteristics are systematically explained in the paper. The research work is divided into the following five chapters.In chapter 1, the advantages and disadvantages of pneumatic technology, the history and current researches on pneumatic control valve are summarized. The origination and significance of the project are explained. The main research work, difficulties and innovations of this project are developed.In chapter 2, based on the echo ranging principle of pneumatic control valve, the desire requirement of valve is got. A new pneumatic control valve with two stages structure, employing a pilot high-speed on/off solenoid valve to actuate a large diameter main valve, was developed. To realize the seal and reset of the main valve, the three steps structure with differential pressure area is adapted and the controller chamber is connected with high pressure chamber by an orifice.In chapter 3, the dynamic characteristics of the valve are analyzed. A new method which used the pressure variation characteristic in the control chamber during the charging-discharging processes to describe the dynamic characteristics of the valve is proposed. A detailed mathematical model based on the thermodynamics, kinetics, pneumatic transmission and some other theories is established. Based on the mathematical model, the state equations between the diameters of the pilot valve with the pressure of the chamber are got. Simulink is used to analyze the valve's dynamic performance. By comparing the motion curves and the pressure curves to verify the method. Some factors having influences on the dynamic characteristics of the valve, such as the orifice diameter and the control chamber volume, are also analyzed and optimized. Simulation results also show that the diameter of the pilot valve, spring stiffness and other structure parameters have a great influences on the valve.In chapter 4, the experimental system of the pneumatic control valve is developed. the dynamic pressure characteristics in inburst model and outburst model are tested respectively under the input pressure of 9bar. Results show that the valve works well. With the input pressure of 9bar, the open time of the main valve under inburst model condition and outburst model condition are 13 ms and 8ms respectively. The influence of the diameter of the pilot valve, volume of controller chamber, diameter of the orifice, input pressure and output pressure on the dynamic characteristics of the valve is analyzed in experiment. By comparing the simulation curves with the experiment curves under inburst model condition, the mathematic model built above is verified.In chapter 5, the contents of the full text are summarized and the follow-up research works are prospected.