Environmental legislation and engine design
Published May 23, 1999 by SAE Australasia in Australia
Gasoline engines have had to face increasingly tight limits on HC, CO and NOx. The engine designer has responded by building in features to minimize emissions and reduce the task for the aftertreatment system. At the same time pressure to reduce fuel consumption has forced changes in the design of the engine to minimize friction and reduce the penalties of cold start and warm-up operation.
The same pressure on fuel consumption has led to the introduction of sophisticated small diesels for passenger car use, but these small diesels have been subjected to increasingly severe legislation. Particulates and NOx have been the main focus. The engine designer has responded in a similar manner to that adopted for the gasoline engine, but different design solutions are required for the light-duty diesel.
The paper describes the approaches taken in the basic engine design to achieve compliance with projected emissions and fuel consumption levels.