Importance

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Abstract

An exhaust gas purifying apparatus of an internal combustion engine containing: an absorption-reduction catalyst which absorbs nitrogen oxides NO.sub.x included in exhaust when an air/fuel ratio of the exhaust is lean and reduces the absorbed NO.sub.x when the air/fuel ratio of the exhaust is a stoichiometric ratio or rich; and NO.sub.x amount estimating apparatus for estimating an amount of NO.sub.x absorbed in the NO.sub.x absorption-reduction catalyst; a rich spike executing apparatus for executing a rich spike while switching the air/fuel ratio to the stoichiometric ratio or to a rich air/fuel ratio when the amount of NO.sub.x estimated by the NO.sub.x amount estimating apparatus exceeds a permissible reference value; an atmospheric pressure detector for detecting atmospheric pressure; and an amount correcting apparatus for correcting the amount of NO.sub.x estimated by the NO.sub.x amount estimating apparatus, based on the atmospheric pressure detected by the atmospheric pressure detector, such that the amount of correction increases as atmospheric pressure decreases, whereby NO.sub.x absorbed in the NO.sub.x absorption-reduction catalyst can be reduced into harmless matter with accuracy and whereby deterioration of emissions can be restrained.

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First Claim