Treatment of gases, emitted from engines with separate ignition systems, involves using reduced, standardized catalyst metal content, with rapid engine warm-up phase

摘要

The exhaust is passed through a pre-catalyst (16) and catalyst (18). pre-catalyst noble metal content (EMVH) is expressed in terms of grams per unit volume of engine displacement volume, being at most 1.1g/dm3 (31 g/ft3). During a heating interval, pre-catalyst temperature (TVK) reaches at least 150 deg C no later than 25 s after engine (10) starting, with engine speed exceeding 2500 per min for 1 s or less. An Independent claim is included for corresponding equipment. Preferred Features: pre-catalyst volume is 0.45, 0.35 or 0.25 (especially) times the engine displacement. Further pre-catalyst temperatures and delays are specified, with related, elevated engine speeds in early operation following starting. Retarded ignition, at least 10 deg after top dead center (TDC) promotes heating. The engine is directly injected and designed for stratified combustion. Heating is achieved by retardation and/or multiple injection. First early injection during the induction phase, is followed by at least one later injection during the in-cylinder (12) compression phase. The last injection is completed under control, at 80 deg -10 deg , 60 deg -25 deg , or 50 deg -35 deg before TDC.