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Technical Paper

Gasoline DI Engines: The Complete System Approach By Interaction of Advanced Development Tools

Gasoline direct injection is one of the main issues of actual worldwide SI engine development activities. It requires a comprehensive system approach from the basic considerations on optimum combustion system configuration up to vehicle performance and driveability. The general characteristics of currently favored combustion system configurations are discussed in this paper regarding both engine operation and design aspects. The engine performance, especially power output and emission potential of AVL's DGI engine concept is presented including the interaction of advanced tools like optical diagnostics and 3D-CFD simulation in the combustion system development process. The application of methods like tomographic combustion analysis for investigations in the multicylinder engine within further stages of development is demonstrated. The system layout and operational strategies for fuel economy in conjunction with exhaust gas aftertreatment requirements are discussed.
Technical Paper

Gasoline Direct Injection: Actual Trends and Future Strategies for Injection and Combustion Systems

Recent developments have raised increased interest on the concept of gasoline direct injection as the most promising future strategy for fuel economy improvement of SI engines. The general requirements for mixture preparation and combustion systems in a GDI engine are presented in view of known and actual systems regarding fuel economy and emission potential. The characteristics of the actually favored injection systems are discussed and guidelines for the development of appropriate combustion systems are derived. The differences between such mixture preparation strategies as air distributed fuel and fuel wall impingement are discussed, leading to the alternative approach to the problem of mixture preparation with the fully air distributing concept of direct mixture injection.
Technical Paper

CSI - Controlled Auto Ignition - the Best Solution for the Fuel Consumption - Versus Emission Trade-Off?

In recent years several new gasoline engine technologies were introduced in order to reduce fuel consumption. Controlled autoignition seems to be an alternative to stratified part load operation, which is handicapped due to it's lean aftertreatment system for world wide application. The principal advantages of controlled auto ignition combustion under steady state operation - combining fuel economy benefits similar to stratified charge systems with nearly negligible NOx and soot emissions - are already well known. With the newly developed AVL- CSI system (Compression and Spark Ignition), a precise combustion control is achieved even under transient operation. For compensation of production and operation tolerances a cost optimized cylinder individual control was developed. Completely new functionalities of the engine management system are applied. This lean GDI concept complies with future emission standards without DeNOx catalyst and can be applied worldwide.
Technical Paper

Turbocharging the DI Gasoline Engine

Regarding concepts for naturally aspirated engines, the high potential for fuel economy of Gasoline Direct Injection can only partially be utilized within the constraints of current or future emission legislation like EURO III / IV or LEV/ULEV. Instead of an expected improvement of 20 - 25 % currently only 10 - 15% can be obtained by the engine alone without vehicle optimizations considering all limitations of high volume production. A detailed analysis reveals concrete measures for further improvement. The application of DI gasoline technology clearly favors the combination with other fuel efficient technologies like downsizing by turbocharging and the application of a variable effective compression ratio by intake valve timing variation. Using the flexibility of direct gasoline injection some deficiencies of these technologies can be eliminated.