TGDI Engine Fuel System Pressure Control And Optimization

Turbocharged gasoline direct injection technology is a main tech to cope with the fuel consumption requirements.But this TGDI tech results in the fuel and air mixture uneven,further cause the HC and PM/PN emission out in the air.In TGDI engine,fuel injection system optimization is the core parts to improve the fuel/air mixture formation.In this dissertation,a variety of methods were used together to get the best injection strategy for low fuel consumption and emissions,including constant-volume tank test,numerical simulation and thermodynamic test bench experiment.First,using constant-volume tank to get the spray shape and calibrate CFD spray models.Second,by validated CFD method,different injection phase,injection times and injection ratio were analyzed to get the effects on mixture formation process,the mass of fuel film in the piston and cylinder wall were also studied to get the best fuel injection strategy.In thermodynamic test bench period,the combustion stability,combustion duration,HC emission and fuel consumption were investigated to find out the best injection strategy.The results and conclusions are as follows:(1)Catalyst heating operating point: the mass of fuel film in the piston and cylinder wall has big influence on HC emission,the injection strategy aimed to reduce fuel film can reduce HC emission at the same time;(2)Minimum brake specific fuel consumption(BSFC)operation point: due to the mixture uniformity has the biggest influence on BSFC,although double injection strategy can improve combustion by forming rich mixture around spark plug,can't reduce BSFC any further,but is good to reduce piston wetting by retard the first injection timing without sacrificing fuel economic,so is good to balance fuel consumption and emissions.