Patent ID: 8033100

Claim:
An exhaust purification device of a compression ignition type internal combustion engine comprising: an SO X trap catalyst, arranged in an engine exhaust passage, for trapping SO X contained in exhaust gas; an NO X storing catalyst, arranged downstream from the SO X trap catalyst, wherein the NO X storing catalyst stores NO X contained in the exhaust gas when an air-fuel ratio of the exhaust gas is lean and releases stored NO X when the air-fuel ratio of the exhaust gas becomes a stoichiometric air-fuel ratio or rich, the air-fuel ratio of the exhaust gas flowing into the SO X trap catalyst is switched from lean to rich so as to make the NO X storing catalyst release NO X , the exhaust purification device prohibits switching the air-fuel ratio of the exhaust gas from lean to rich if the temperature of the SO X trap catalyst is higher than an SO X release lower limit temperature for releasing SO X , and the SO X release lower limit temperature is a function of the SO X storage amount stored in the SO X trap catalyst.