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. When the air/fuel ratio of exhaust gas flowing into the NOx absorbing agent (17) is to be made rich so as to discharge NOx from the NOx absorbing agent, a higher NOx absorbing agent temperature makes the degree of richness higher and rich time shorter.