Patent ID: 6018943
Filing Date: 2000-02-01
Classification: B01D,F01N,F02B,Y02T

Abstract:
An assembly for elimination of nitrogen oxides (NO.sub.x) present in exhaust gas of a lean-burn diesel or spark-ignition engine, said assembly being part of a main exhaust line coming from the engine and comprising:a plurality of nitrogen oxides conversion catalysts placed in said main exhaust line, said conversion catalysts having non-coinciding temperature ranges for which the NO.sub.x, conversion is below a certain conversion coefficient (C.sub.min),at least one NO.sub.x trapping means placed upstream from said conversion catalysts for trapping, then releasing nitrogen oxides,at least one bypass bypassing said main exhaust line and containing said at least one NO.sub.x trapping means,at least one valve to modulate the flow of gas between said bypass line and said main exhaust line so that said at least one NO.sub.x trapping means can trap said nitrogen oxides notably when said conversion catalysts have a conversion coefficient below said predetermined value (C.sub.min) and so that said at least one NO.sub.x trapping means can release said nitrogen oxides simultaneously with a conversion.