Research On Two-stage Supercharged Engine System Matching

With the development of internal combustion engine, people’s pursuit of the ℃Ar economy and power performance more and more high, turbocharged conform to the trend of The Times, ℃Ame into being. The traditional single stage supercharger, when the engine at low speed, the engine torque is low.The engine exhaust steam, lead to the supercharger in low speed slow response, poor fuel economy. With the rising of on the engine, single-stage booster technology℃ An not meet the demand of future development, and the two-stage supercharging technology solved the problem very well.According to the actual structure sizes and dyno test data of the 1.2L superturbo engine, one-dimensional simulation software GT-Power is utilized to creat the simulation model, with detailed description to the important submodules and parameter settings. The model is then calibrated and validated against experimental data, and the two sets of data match well, it indicates that the simulation model has high precision. Thus, the 1.2L single-stage turbocharged gasoline engine simulation model is created and calibrated.Then, the inlet and exhaust manifold system were optimized for the turbocharged enginemodel. Analysis of the different valve overlap angle indicated that increasing the valve overlapangle was expected to improve the low-speed torque.A knocking module was developed andutilized to analyze the influence on engine knock index of compression ratio and sparktiming, which provided the theoretic support and direction for engine design change and testscheme. Exhaust gas temperature increase after turbocharging, and the influences of the air/fuleratio were analyzed.and put forward relevant suggestions for reducing the exhaust gastemperture.Finally, based on the GT-Power simulation results, the low speed engine torque, transient load-step response characteristic as well as the fuel economy of the three types of charging systems under consideration are compared and analyzed with each other. Results indicate that the superturbo and the two-stage sequential turbocharger could increase the 1000 r/min full load torque by 62.80% and 54.35% respectively, while the engine BSFC at 4000 r/min full load could also be reduced by as much as 23.45% and 22.71% respectively over the single-stage turbocharged baseline engine; Charging systems in the order of fastest to slowest transient load-step response are the superturbo, the two-stage sequential turbo and the single-stage turbo. The three types of charging systems demonstrate the most obvious differences at the engine speed of 1500r/min.