CO₂ emission reduction using stratified charge in spark-ignition engines

According to the proposal of the European Commission, the average CO ₂ emission of passenger cars will be limited to 120 g/km by the end of 2012. Decreasing the CO₂ emissions is possible only with the decrease of fuel consumption, and this can be achieved most effectively by operating the engine with the stratified charge principle. With the aid of a thermodynamic internal combustion (IC) engine model, it is seen that stratified charge engines have the potential to attain a reduction in CO₂ emissions up to 19%, by using higher rates of stratification and higher compression ratios. In this context, a stratified charge engine having a unique twin swirl combustion chamber operating with a two-stage combustion mechanism is presented. A 1.6 L 8v single-point injection test engine has been analyzed to compare the power output and specific fuel consumption values of a conventional gasoline engine with a stratified charge engine having a twin swirl combustion chamber. The results show that, when stratified charge is used, specific fuel consumption decreases significantly, which leads to a reduction in CO ₂ emission. Moreover, this combustion mechanism does not require high fuel injection pressures and can be applied easily on current production engines, without significant modification.