The Influence of DISI Engine Operating Parameters on Particle Number Emissions 2011-01-0143
The future EURO 6 emission standard will limit the particle number and mass for gasoline engines. The proposed limit for particle mass is 4.5 mg/km. For particle number there is not yet a limit defined but a wide range of proposals are under discussion (6E11 - 8E12 Particles/km)
The particle emissions on a homogeneous SIDI engine are mainly caused by insufficient mixture preparation. A combustion improvement could be achieved by a careful recalibration as well as a hardware optimization that mainly avoids wall impingement and substoichiometric zones in the combustion chamber.
The analyses of current SIDI vehicles show significant PN emission peaks during cold start and transient operation on a NEDC cycle.
To give a better understanding of cause and effect of the particle formation at steady state results so as transient load steps were performed at an engine dynamometer. The steady state measurement contains various parameter variations like A/F ratio or SOI to identify the root cause for particle emissions. These measurements show stabilized results.
To understand the additional effect of transient engine operation on particles several measurements at a NEDC comparable load step were done and analyzed.
Additionally to engine parameter variations also injectors with different spray angles were investigated.
The target is to show the main influences and sensitivities on particle emissions at gasoline SIDI engines.
All data presented comes from in-house measurement. The data is taken from vehicle and engine dynamometer measurement.