Exhaust gas-purifying system for internal combustion engines

An exhaust gas-purifying system for an internal combustion engine having a plurality of cylinders, and an exhaust system, comprising:

• exhaust gas-purifying means arranged in said exhaust system and accommodating a nitrogen oxide absorbent for absorbing nitrogen oxides in exhaust gases emitted from said engine when said engine operates in a state where an air-fuel ratio of said exhaust gases is leaner than a stoichiometric air-fuel ratio;
• cylinder internal pressure-detecting means for detecting pressure within at least one of said cylinders;
• nitrogen oxide generation amount-determining means for determining an amount of nitrogen oxides generated within said engine, based on said pressure within said at least one of said cylinders;
• and
• saturation state-determining means for determining whether an amount of nitrogen oxides absorbed by said nitrogen oxide absorbent has been saturated, based on said amount of nitrogen oxides determined by said nitrogen oxide generation amount-determining means.