EXHAUST EMISSION CONTROL SYSTEM FOR INTERNAL COMBUSTION ENGINE

摘要

An NOx absorbing agent (17) is disposed inside an exhaust gas passage of a combustion engine. This NOx absorbing agent (17) absorbs NOx when the air/fuel ratio of exhaust gas flowing thereinto is lean, and discharges NOx which it has absorbed when the air/fuel ratio of exhaust gas flowing thereinto becomes rich. The amount of NOx absorbed in the NOx absorbing agent (17) is estimated from the engine load and the number of revolutions of the engine, and when this estimated NOx amount becomes the maximum NOx absorbing capacity of the NOx absorbing agent (17), the air/fuel ratio of exhaust gas flowing into the NOx absorbing agent (17) is made rich.