Patent ID: 6195987
Filing Date: 2001-03-06
Classification: F01N,F02D

Abstract:
An exhaust gas purifying apparatus of an internal combustion engine comprising:an NO.sub.x absorption-reduction catalyst placed in an exhaust gas path of the internal combustion engine, acting to absorb nitrogen oxides NO.sub.x included in exhaust when an air/fuel ratio of the exhaust flowing thereinto is lean, and acting to reduce the absorbed NO.sub.x when the air/fuel ratio of the exhaust flowing thereinto is a stoichiometric ratio or rich;NO.sub.x amount estimating means for estimating an amount of NO.sub.x absorbed in said NO.sub.x absorption-reduction catalyst, from an operating condition of said internal combustion engine;atmospheric pressure detecting means for detecting atmospheric pressure;exhaust gas recirculating means for recirculating exhaust gas to an intake system of said internal combustion engine; andNO.sub.x amount correcting means for correcting the amount of NO.sub.x estimated by said NO.sub.x amount estimating means, based on the atmospheric pressure detected by said atmospheric pressure detecting means,wherein said NO.sub.x amount correcting means corrects the amount of NO.sub.x estimated by said NO.sub.x amount estimating means, based on the atmospheric pressure detected by said atmospheric pressure detecting means and on a recirculation amount of the exhaust gas recirculated by said exhaust gas recirculating means, and further wherein the amount of NO.sub.x is corrected larger when the detected atmospheric pressure is lower.