PROCEDURE FOR DECREASING THE NITROGEN OXIDE CONTENT IN THE EXHAUST GASES OF AN INTERNAL COMBUSTION ENGINE LIKELY TO OPERATE IN ALTERNATION OF POOR-RICH MODES

摘要

The invention is applicable to an internal combustion engine having a control unit and having an exhaust gas pipe in which a starting catalyst, a nitrogen oxide storage catalyst and a catalyst of nitrogen are deposited. SCR type. According to the invention, the charge of NH 3 of the SCR-type catalyst is determined by the control unit and, at least in the nitrate regeneration phases, the formation of nitrogen oxide of the internal combustion engine is increased. The SCR-type catalyst is installed at least a distance downstream of the nitrogen oxide storage catalyst, such as a lower temperature of about 50.degree. C. to about 150.degree. C. at the inlet of the accumulator catalyst. Nitrogen oxide is set at the inlet of the SCR type catalyst. Use, for example in motor vehicles.