Optimized Gasoline Direct Injection Engine for the European Market

GDI (Gasoline Direct Injection) engine adopting new combustion control technologies was developed and introduced into Japanese domestic market in August of 1996. In order to extend its application to the European market, various system modifications have been performed. Injectors are located with a smaller angle to the vertical line in order to improve the combustion stability in the higher speed range. A new combustion control method named “two-stage mixing” is adopted to suppress the knock in the low speed range. As a result of this new method, the compression ratio was increased up to 12.5 to 1 while increasing the low-end torque significantly. Taking the high sulfur gasoline in the European market into account, a selective reduction lean-NOx catalyst with improved NOx conversion efficiency was employed. A warm-up catalyst can not be used because the selective reduction lean NOx catalyst requires HC for the NOx reduction. A new method named “two stage combustion” was adopted for the quick warm-up of the under floor three way catalyst located downstream of the lean NOx catalyst. As a result of these modification, European version GDI engine revealed 10 percent higher torque and the 20 percent better fuel economy than the conventional port injection engines, while maintaining the clean exhaust gas that can meet the European Step 2 and the German D3 regulations.