Browse Publications Technical Papers 2008-01-0426

An Evaluation of Different Combustion Strategies for SI Engines in a Multi-Mode Combustion Engine 2008-01-0426

Future pressures to reduce the fuel consumption of passenger cars may require the exploitation of alternative combustion strategies for gasoline engines to replace, or use in combination with the conventional stoichiometric spark ignition (SSI) strategy. Possible options include homogeneous lean charge spark ignition (HLCSI), stratified charge spark ignition (SCSI) and homogeneous charge compression ignition (HCCI), all of which are intended to reduce pumping and thermal losses.
In the work presented here four different combustion strategies were evaluated using the same engine: SSI, HLCSI, SCSI and HCCI. HLCSI was achieved by early injection and operating the engine lean, close to its stability limits. SCSI was achieved using the spray-guided technique with a centrally placed multi-hole injector and spark-plug. HCCI was achieved using a negative valve overlap to trap hot residuals and thus generate auto-ignition temperatures at the end of the compression stroke.
The experiments were performed using a 6 cylinder, 3.2 liter Volvo engine equipped with cam profile switching (CPS), variable cam timing (VCT) for both intake and exhaust valves, and a spray guided direct injection (SGDI) system. In conjunction with a fully programmable control unit these features allowed the engine to be run in all the tested modes without any hardware modifications.
Five operating points in the low load/speed zone of the engine map were optimized for fuel consumption using full factorial, 2-D and 3-D experimental designs (with centre points). The same operating points were used for each combustion strategy and their effects on exhaust emissions, combustion and fuel-consumption were evaluated.


Subscribers can view annotate, and download all of SAE's content. Learn More »


Members save up to 16% off list price.
Login to see discount.
We also recommend:

New Generation Multi-hole Fuel Injector for Direct-Injection SI Engines - Optimization of Spray Characteristics by Means of Adapted Injector Layout and Multiple Injection


View Details


Expanding the Low Load Limit of HCCI Combustion Process Using EIVO Strategy in a 4VVAS Gasoline Engine


View Details


Influence of the Valve-lift Strategy in a CAI™ Engine using Exhaust Gas Re-Breathing - Part 2: Optical Diagnostics and 3D CFD Results


View Details