Gasoline Direct Injection - SULEV Emission Concept 2004-01-0041
Gasoline Direct Injection (GDI) engines can play an important role in future powertrain concepts. They show potential for enhanced fuel economy and at the same time fulfill demands for higher specific power output. For a successful placement in the NAFTA market especially against other competing concepts such as the gasoline port fuel injection engine and the Diesel engine, GDI has to demonstrate its ability to meet existing and future emission legislation.
This contribution demonstrates GDI as a low emission concept. It proposes a reliable and efficient cold-start strategy called “High-Pressure Stratified Start”. Fuel is injected by means of increased fuel pressure during compression stroke instead of the conventional start with low-pressure fuel injection during intake stroke. Consequently, mixture preparation is greatly enhanced and wall wetting is reduced. The high-pressure start produces less unburned hydrocarbon emissions and enhances start reliability at low temperatures. Further improvements in the catalyst-heating strategy, known as “Homogeneous-Split Injection” are demonstrated. With the inclusion of new component design in injection technology, e.g. flexible and optimized spray patterns, GDI engines will be presented as a clean and efficient propulsion system for the future.