The Influence of DISI Engine Operating Parameters on Particle Number Emissions

Abstract

<div class="section abstract"><div class="htmlview paragraph">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)</div><div class="htmlview paragraph">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.</div><div class="htmlview paragraph">The analyses of current SIDI vehicles show significant PN emission peaks during cold start and transient operation on a NEDC cycle.</div><div class="htmlview paragraph">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.</div><div class="htmlview paragraph">To understand the additional effect of transient engine operation on particles several measurements at a NEDC comparable load step were done and analyzed.</div><div class="htmlview paragraph">Additionally to engine parameter variations also injectors with different spray angles were investigated.</div><div class="htmlview paragraph">The target is to show the main influences and sensitivities on particle emissions at gasoline SIDI engines.</div><div class="htmlview paragraph">All data presented comes from in-house measurement. The data is taken from vehicle and engine dynamometer measurement.</div></div>