Patent ID: 6460329
Filing Date: 2002-10-08
Classification: F01N,F02D,Y02T

Abstract:
An exhaust gas purifying apparatus 1 having a nitrogen oxides absorption-reduction catalyst comprising:a nitrogen oxides absorption-reduction catalyst 2 having a nitrogen oxides absorbing substance 4 provided in the exhaust passage 11 of the internal combustion engine E for absorbing nitrogen oxides when the air/fuel ratio is lean and discharging nitrogen oxides when the air/fuel ratio is theoretical air/fuel ratio or rich, and a precious metal catalyst 3; and a control apparatus 10 for computing the integrated value of NOx (NOxmass) from the engine load, the number of revolutions of the engine, and the intake air mass, so that a rich spike is executed when the integrated value of NOx (NOxmass) exceeds the predetermined first reference value (NOxSL); characterized in that a NOx sensor 13 is provided downstream from the nitrogen oxides absorption-reduction catalyst 2, and in that the control apparatus 10 corrects the predetermined first reference value (NOxSL) when the value detected by the NOx sensor 13 (RSNOx) immediately after the rich spike is executed exceeds the predetermined second reference value (RSSL).