Search Results

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.

The goal of the Clean Engine Vehicle project (CEV) was the conversion of a gasoline engine to dedicated natural gas operation in order to achieve a significant reduction in CO2 emissions. The targeted reduction was 30% compared with a gasoline vehicle with similar performance. Along with the reduction in emissions, the second major requirement of the project, however, was compliance of the results with Euro-4 and SULEV emission limits. The project entailed modifications to the engine and the pre-existing model-based engine control system, the introduction of an enhanced catalytic converter and downsizing and turbocharging of the engine. As required by the initiators of the project, all components used were commonly available, some of them just being optimized or modified for natural gas operation.