Exhaust gas-purifying system for internal combustion engines

摘要

An exhaust gas-purifying system for an internal combustion engine comprises an exhaust gas-purifying device arranged in the exhaust system of the engine and accommodating a nitrogen oxide absorbent for absorbing nitrogen oxides in exhaust gases emitted from the engine when the engine operates in a state where the air-fuel ratio of the exhaust gases is leaner than a stoichiometric air-fuel ratio. A cylinder internal pressure sensor detects pressure within at least one of the cylinders of the engine. The amount of nitrogen oxides generated within the engine is determined based on the pressure within the at least one of the cylinders. It is determined whether the amount of nitrogen oxides absorbed by the nitrogen oxide absorbent has been saturated, based on the determined amount of nitrogen oxides.