Research On Theory And Application About Pressure Reduction Of High Pressure Pneumatic Power And Compressed Air Powered Vehicle

High-pressure compressed air (HPCA) as work media that has some special advantages of pollution free, high power density, large distensibility, 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 (CAPV) aspects. However, there is little systemic and experienced investigation on the theory and technology about the elements and the control devices and methods of high-pressure pneumatic system (HPPS). The HPCA is the powered source of the CAPV. The pressure energy transmits from the powered source at higher level into the exhaust gas at lower level, which is used by the CAPV when pressure energy is transformed into kinetic energy.Relied on the Natural Science Foundation of China-Ford Fund— "Research on air powered vehicle engine", aimed at application of the HPPS in the CAPV, the energy transforming and utilizing properties of the HPPS are detailedly analyzed; the pressure reduction principle and its control methods of the HPPS are systemically investigated; which provide a theoretical basis and experimental data for the CAPV to optimize design of the powered system. Therefore, the research will have theoretical significance and engineering values to be benefits to the development of the HPPS. The paper includes contents as follows.In chapter 1, the history and actuality of the pneumatic technique and the HPPS, the current researches on energy saving, the high-pressure element in pneumatic aspect and the problems in the CAPV are summarized. The aim and significance of research and development the CAPV are explained. The main research subjects are summarized in the paper.In chapter 2, the new concept of the pressure reduction with expander of the HPPS is defined. The pressure reduction principles with expander and with throttle regulator are respectively discussed, and their exergy depreciatory equations that can be use to calculate the power in pressure reducing processes are respectively deduced. For compensating the energy loss in pressure reducing processes, the new concept of classification pressure reduction is put forward and its mathematic model is obtained. The energy properties in classification pressure reduction with energy compensating at pressure unchanging processe and volume unchanging processe are respectively analyzed. The simulation results show that work power with two stages is bigger than one stage.In chapter 3, the high-pressure pneumatic on-off valve (HPPon-offV) that is key part used for a new system with pressure reduction by expander of the HPPS in the CAPV is developed. The principle and operating processes of the HPPon-offV are detailedly analyzed. Based on the keypressure points and the operating volume changing or not in the control chamber of the main valve, the subdivision principle is put forward and defined Based on the subdivision principle, the mathematic models and simulation models of the valve are obtained. Considering the factors such as main valve geometrical parameters, friction force, spring force and valve moving body mass, the simulations on the dynamic property of the valve are performed. The results show the validity of the theory and the simulation model that will be used to guide the development of the HPPon-offV.In chapter 4, the construct and principle of the pressure reduction by expander system of the HPPS is introduced. The mathematic model of the pressure reduction by expander system of the HPPS is obtained by theoretical analysis. Based on the mathematic model, the simulation models with different control tragedies such as Bang-Bang control, PID control, predictive PID control and Fuzzy control on the pressure reduction by expander system of the HPPS are created, and the feasibilities and characteristics of these control methods are respectively analyzed. The mathematic model of the pressure reduction with classification system of the HPPS is also obtained by theoretical analysis. The simulation results show that the pressure reduction with classification system of the HPPS has better performance.In chapter 5, the energy system in CAPV is perfectly constructed. The energy analysis shows that the pressure reduction with expander is better than the regulator in energy saving in the HPPS. By analysis of the structure and work parameters, that the expanding ratio of the air engine plays important role on power property of the CAPV is made sure, and should be selected reasonably. Some factors such as body mass, speed, gradient of the road, acting on the running distance of the CAPV are also analyzed. These will bring great benefit to the design and development of the CAPV.In chapter 6, the HPPS experimental table is created. The test of the dynamic pressure of the control chamber in the HPPon-offV is completed. The experimental researches on the pressure reduction by expander of the HPPS by means of the Bang-Bang control, PID control, predictive PID control and Fuzzy control tragedies are performed. The experiment on the pressure reduction with classification of the HPPS by means of the Bang-Bang control tragedy is performed. The results come from experiment are accorded with that come from theoretical analysis. The energy property of the pressure reduction by expander device of the HPPS is tested on table and the CAPV.In chapter 7, some conclusions are reached and some new views are put forward.