Research On Hybrid Effects And Electronic Controlled Air-powered Engine Of Hybrid Air-fuel Car

Oil resource crisis together with environmental problems bring about the emergence and development of various kinds of new-energy-automobile such as electrical vehicle, biology-fuel-vehicle and gas vehicle. As well, with compressed air or liquid nitrogen as its energy source, air-powered vehicle has received much attention these years. However, air-powered vehicle has its limitation of application due to the low energy density of its energy source and the poor energy conversion rate, despite its advantage of no oil consumption and pollutant emission. It could achieve a mutual-benefit to establish a hybrid power system with air-powered engine(APE) and internal combustion engine(ICE). The dynamic advantage of APE and ICE could be made into play by the hybrid system. Besides, the system could realize the oil and energy saving and emission reduction by cancellation of idle, optimization of working area of ICE, downsizing ICE, regenerative braking and exhaust heat reuse. As an orientation research project, an easily-realized parallel hybrid air-fuel vehicle(PHAV) was adopted as the research object within the paper. The design of electronic controlled APE, the match of powertrain parameters and the research of control strategy were accomplished, and the effects of oil and energy saving, and the emission reduction were analyzed. The main contents and conclusion are as follows:The research of electro-pneumatic valve(EPV) of APE. A new electro-pneumatic variable valve system was designed to meet the demands of the fast mode change of APE for PHAV. The system could be driven by the recirculation of the wasted energy during the pressure-reduction of APE power system. The dynamic mathematic model of the valve system was established based on thermodynamics and kinetics. Experiments were set up to validate the model. Both the simulation and experimental results suggest that the designed valve system could satisfy the frequency demands of APE at the speed of 2000 r/min. Then the variable mass mathematical model of APE with the electro-pneumatic valve was built up. The effects of the design and working parameters on the dynamic characteristics of the valve were analyzed, and it provides the theoritical principle for optimizing the design and working parameters of such kind of valve.The design of electronic control system and the evaluation experiment of electronic controlled APE. An 195 diesel engine was changed into the prototype of electronic controlled APE. The electronic control system of the APE were designed. Then the test bench of electronic controlled APE was constructed. The feasibility evaluation experiment on the prototype shows that the designed electro-pneumatic valve is practical and proper for electronic controlled APE. In addition, the experiment to varidate the mathematic model of electronic controlled APE shows the model has enough accuracy in the analysis of the effect of eletro-pneumatic valve parameters on the valve dynamic characteristics, as well as the performance of eletronic controlled APE.The modeling of PHAV and the research on the method to design powertrain parameters. With reference to the ADVISOR, the simulation analysis platform of PHAV was set up using MATLAB/SIMULINK. It provided the design theory of powertrain parameters of PHAV. With the combination of real examples, the optimization method of powertrain parameters was raised based on orthogonal optimization theory.The research on control stragety of PHAV. The development principal of control strategy of the PHAV was raised by the analysis of its characteristics. According to the development principle, a comprehensive control strategy was developed based on the combination of logic threshold value and torque distribution real time optimization strategy. The simulation result showed the proper torque allocation of the two power sources could be realized according to total torque requried of the driving cylce using the control strategy. Furthermore, ICE could stay in the working area of high efficiency and low emission, and the economic characteristic of APE could be ensured.The hybrid effects analysis of PHAV. The hybrid effects of PHAV were analyzed by its comparison with traditional diesel vehicle. The result showed:For the driving cycles as NEDC, UDDS, HWFET and JAPAN10-15, the PHAV could have an oil saving of 48.34%,44.96%, 20.66% and 55.15%, respectively, and the emission decreased by 58.84%,38.76%,14.54%, and 66.59%, respectively, with an increase of compressed air consumption of 99.73 kg/100km, 87.39 kg/100 km,55.60 kg/100 km, and 90.59 kg/100 km, respectively. The PHAV could have an energy saving by 13.12%,14.06%,-6.27%and 28.06%, respectively, if evaluated with diesel equivalent as the standard for PHAV. In addition, five hybrid ways were analyzed to estimate their contribution to total hybrid effects, including the cancellation of idle, the optimization of ICE working area, downsizing ICE, exhasut heat recycle and regenerative braking. The results were as follows:For the dirving cycles with similar average speed such as NEDC and UDDS, the oil saving effect order of the five ways are "the optimization of ICE working area>the cancellation of idle>the downsizing ICE> exhaust heat recycle>regenerative braking". As for the JAPAN10-15 with the longest idle time, the cancellation of idle contributed the most oil saving effects. And for the HWFET with highest average speed, the recycle of exhaust heat had the most effect on oil saving. The emission reduction and oil saving effects were similar for the five hybrid ways. The exhaust heat recycle along with the cancellation of idle had the most effect on energy saving, and then is the downsizing ICE, but the exhasut heat recycle would increase energy consumption. The efficiency of regenerative braking is low, as well as the heat exchange efficieny of the adopted heat exhanger, requiring further optimization and design.