A Study on HCCI(Homogeneous Charge Compression Ignition) Gasoline Engine Supercharged by Exhaust Blow Down Pressure 2007-01-1873
Research into HCCI technology has been based on gasoline or diesel engines, using a large amount of EGR and supercharging(1). In this paper, a new method is introduced, which realizes heavy internal EGR and supercharging simultaneously using exhaust blow down pressure without a super charger.
A four cylinder HCCI gasoline engine is initially introduced with a BDSCac (Blow Down Super-Charging by accumulation) system which achieves a large amount of EGR and simultaneously supercharging without a supercharger. This is brought about by accumulating the exhaust blow down pressure in one of two separate exhaust systems, and its characteristics are explained.
Further research has been made into a new method to achieve a similar effect as BDSCac by using a common exhaust system and a simple mechanical cam-driven variable valve actuation system. The system is called BDSCpw (Blow Down Super-Charging by pressure wave).
The potential of expanding the operating area of HCCI to high loads is shown, by assuming 4-cylinder engine specifications and valve timing with a 6 degree of freedom variable valve actuation system, optimized using mode-FRONTIER and GT-POWER. Also the performance is estimated by considering a feasible BDSCpw system with a mechanical cam driven, 4 degree of freedom, variable valve actuation mechanism. It is shown that ultra-low NOx HCCI operation at 2000rpm is possible up to IMEP 6.8bar covering Japanese 10-15 driving mode area.