Charging System Matching And Performances Optimization Of Small Turbocharged Gasoline Engine

Since the 21st century,China's auto industry has developed rapidly,forming a full range of vehicles producing and supporting system,whose improving industrial concentration and product technology have made China a worldwide automobile production power.In recent years,to meet people's practical requirements for power and economy,researchers have been using a series of advanced engine technology on the gasoline engine,such as variable valve timing(VVT),variable intake manifold,exhaust turbocharging,exhaust gas recirculation(EGR),gasoline engine direct injection(GDI),homogenous charge compression ignition(HCCI),etc.At the same time,with the promotion of national energy-saving and emission-reducing policies and increasingly draconian emission regulations,small-displacement turbocharging gasoline engine,which has low fuel consumption,less pollutant emissions and some other advantages,has become an important research direction of major automobile manufacturers.Using both turbocharging and VVT on the gasoline engine can greatly increase the intake efficiency in full speed range,and then the power and economy are improved obviously.Based on the major Project of Hunan Science and Technology[2014FJ1013],this paper studies the turbocharging technology of the small displacement gasoline engine with the combination of simulation and experiment.Following research works have been done:(1)The simulation model of turbocharged gasoline engine with wastegate was established using GT-POWER.The matching performance of different turbocharger and engine was compared,and the selection of supercharger was completed.Then the engine model is checked using the machine bench test data.(2)Based on the established model of reliable turbocharged gasoline engine,the influence of the length and diameter of the intake manifold on the performance of the engine is analyzed,and the length and diameter of the intake manifold are optimized to determine the optimal intake manifold size.At the same time,VVT technology is used on the original gasoline engine,and then optimal valve timing under engine external characteristics conditions is determined while taking the maximum torque as the optimization goal.(3)Based on the steady state model of turbocharging gasoline engine,it is realized to control the boost pressure by taking the boost pressure as control target and taking the opening of wastegate as control amount,and then the opening of wastegate under different conditions is determined.At the same time,the transient simulation model of the engine is established and determining the transient control strategy of the wastegate under different conditions to optimize the transient response performance.