OPERATION OF AN INTERNAL COMBUSTION ENGINE

摘要

A method is described for operating an engine (12) having an afterburner (16) and a catalytic converter (11) downstream of the afterburner (16). Sufficient excess fuel is introduced into the engine (12) to produce in the exhaust gases fuel constituents including unburnt hydrocarbons, carbon monoxide and hydrogen. Unburnt hydrocarbons are intercepted (10) upstream of the afterburner (16) so as to allow substantially only carbon monoxide and hydrogen to reach the afterburner (16). Sufficient additional air is introduced (30, 32) into the exhaust system to bring the composition of only the carbon monoxide, hydrogen and air stoichiometry or leaner than stoichiometry, the resulting concentration of hydrogen and oxygen in the mixture reaching the afterburner (16) being sufficient for ignition immediately after a cold start. By removing the hydrocarbons temporarily before the exhaust gases reach the afterburner (16), reliable cold ignition can be achieved with lower levels of fuel enrichment.