Research On Structure Optimization And Characteristics Of A High Pressure Pneumatic Proportional Pressure Reducing Valve

High pressure gas has some unique characteristics such as high power density, huge instant dispensability, and well thermal adaptability. It has been widely applicated in special fields like aerospace, pneumatic vehicles and so on. High pressure pneumatic proportional pressure reducing valve(PPRV) is one of the key components that restrict the automation and remote control of high pressure pneumatic systems. But there are lack of deep research and report about the PPRV in existing references. This paper focuses on the structure design, dimension optimization and clearance leakage characteristic etc. to investigate the high pressure pneumatic PPRV. The main contents are as follows:In chapter one, current research status high pressure components and systems is summarized. The research status of pneumatic resistance and capacitance network, dewing and icing characteristics, structure and dimension optimization, as well as clearance leakage characteristics is introduced. Then the research background and importance of this study are given out. Finally the main research content is proposed.In chapter two, new structure type of high pressure pneumatic PPRVs are proposed, the optimization design on both dimension and structure of the PPRV is carried out. Firstly, the principle and characteristic of the high pressure pneumatic PPRV is introduced, the two-way poppet valve and three-way pilot valve as pilot valve are proposed. Secondly, the mathematic model for static characteristics analysis is derived based on resistance network, the dimension optimization of the pilot valve is carried out based on genetic algorithm. Finally, the method of reducing the throttle width ratio is proposed to avoid dewing, the passage area inside the pilot spool is also optimized based on CFD results.In chapter three, mathematical models of the PPRVs are built up. Firstly, contract coefficients and critical pressure ratios of choking flow of different valve ports are derived based on the CFD tools. Then, the dynamic models from gas supply to laod for different PPRVs are analyzed. Finally, the simulation models are built up in AEMSim, and these models will be used as the foundation of characteristics analysis of these PPRVs.In chapter four, the leakage characteristics of annular clearances of the PPRVs are analyzed. An indirect measuring method is proposed to measure concentric annular clearance. Then the leakge characteristics of PPRVs are carefully investigated:the influence of operation conditions and structure paramters are analyzed, the influence of leakage on the PPRV's performance is also researched, the suggetions for reducing leakage are given out.In chapter five, the operating characteristics of these PPRVs are analyzed. The pressure, flow rate and frequency characteristics etc. of PPRVs are simulated. The influences of structural parameters, friction force, and proportional electro-magnet etc. on the performance of PPRVs are also researched. Finally, the key factors that could improve the PPRV's performance are pointed out.In chapter six, the experiments are carried out to test the PPRV. The clearcance indirectly measuring set-up is built up, and the expriments are carried out. The results show that the measument is accurate and the indirect method is simple and practicable. The high pressure pneumatic PPRV test set-up is also built up, and systematic experiments are carried out. The test results verified that the PPRV could achieve steady pressure adjusting within a wide pressure range, the design scheme is reasonable and the simulation model is trustable.In chapter seven, main work of the paper is summarized, then the research conclusions and innovations are introduced, the succeeding research on the PPRV is also prospected at last.