Abstract: An exhaust emission control system for an internal combustion engine is provided. The exhaust emission control system (4) includes a monolith catalyst (MC) that includes an oxygen storage agent and a noble metal-based three-way catalyst including Pd, Rh, and Pt disposed at an upstream location in the exhaust gas flow in the internal combustion engine (2), and a perovskite-type double oxide having a three-way catalytic function disposed at a downstream location in the exhaust gas flow. The amount C1 of Pd carried is 0.97 g/L?C1?1.68 g/L, the amount C2 of Rh carried is 0.11 g/L?C2?0.2 g/L, the amount C3 of Pt carried is 0.06 g/L?C3?0.11 g/L, the amount C4 of the oxygen storage agent carried is 25 g/L?C4?75 g/L, and the amount C5 of the perovskite-type double oxide carried is 5 g/L?C5?15 g/L.

Abstract: The air-fuel ratio of an air-fuel mixture to be combusted in an internal combustion engine 1 is manipulated to converge an output VO2/out of an O2 sensor 6 which is disposed downstream of a catalytic converter 3 to a target value VO2/TARGET depending on an operating state of the internal combustion engine 1, while at the same time a deterioration evaluating parameter is determined from time-series data of the output VO2/out of the O2 sensor 6. The value of the deterioration evaluating parameter is corrected depending on an average value of the output VO2/out of the O2 sensor 6 or the target value VO2/TARGET, and the deteriorated state of the catalytic converter 3 is evaluated based on the corrected value of the deterioration evaluating parameter.

Abstract: There is provided an exhaust gas recirculation control system and method and an engine control unit for an internal combustion engine, which is capable of properly controlling an exhaust gas recirculation rate in advance according to the NOx-eliminating performance of a catalyst, thereby reducing exhaust emissions. An internal combustion engine eliminates NOx in exhaust gases by a catalytic converter, and recirculates the exhaust gases into an intake pipe. An exhaust gas recirculation control system for the engine includes an ECU. The ECU calculates a NOx exhaust estimate based on the intake pipe absolute pressure and the engine rotational speed detected by the respective sensors, calculates an estimated NOx elimination ratio of the catalytic converter based on an estimated catalyst temperature and the space velocity through the catalytic converter.

Abstract: An exhaust emission control system for an internal combustion engine is provided. The exhaust emission control system (4) includes a monolith catalyst (MC) that includes an oxygen storage agent and a noble metal-based three-way catalyst including Pd, Rh, and Pt disposed at an upstream location in the exhaust gas flow in the internal combustion engine (2), and a perovskite-type double oxide having a three-way catalytic function disposed at a downstream location in the exhaust gas flow. The amount C1 of Pd carried is 0.97 g/L≦C1≦1.68 g/L, the amount C2 of Rh carried is 0.11 g/L≦C2≦0.2 g/L, the amount C3 of Pt carried is 0.06 g/L≦C3≦0.11 g/L, the amount C4 of the oxygen storage agent carried is 25 g/L≦C4≦75 g/L, and the amount C5 of the perovskite-type double oxide carried is 5 g/L≦C5≦15 g/L.

Abstract: The air-fuel ratio of an air-fuel mixture to be combusted in an internal combustion engine 1 is manipulated to converge an output VO2/out of an O2 sensor 6 which is disposed downstream of a catalytic converter 3 to a target value VO2/TARGET depending on an operating state of the internal combustion engine 1, while at the same time a deterioration evaluating parameter is determined from time-series data of the output VO2/out of the O2 sensor 6. The value of the deterioration evaluating parameter is corrected depending on an average value of the output VO2/out of the O2 sensor 6 or the target value VO2/TARGET, and the deteriorated state of the catalytic converter 3 is evaluated based on the corrected value of the deterioration evaluating parameter.

Abstract: An exhaust gas purification device for a lean-burn engine that can be produced at a low cost. The exhaust gas purification device includes a three-way catalyst that, during stoichiometric operation of the engine, removes a lower proportion of CO than the proportion of HC removed. The three-way catalyst is positioned in the device on the upstream side of an exhaust pipe of the lean-burn engine, and a lean NOx catalyst is positioned in the device on the downstream side of the exhaust pipe. A perovskite type double oxide is used as the three-way catalyst instead of a precious metal.

Abstract: There is provided an exhaust gas recirculation control system and method and an engine control unit for an internal combustion engine, which is capable of properly controlling an exhaust gas recirculation rate in advance according to the NOx-eliminating performance of a catalyst, thereby reducing exhaust emissions. An internal combustion engine eliminates NOx in exhaust gases by a catalytic converter, and recirculates the exhaust gases into an intake pipe. An exhaust gas recirculation control system for the engine includes an ECU. The ECU calculates a NOx exhaust estimate based on the intake pipe absolute pressure and the engine rotational speed detected by the respective sensors, calculates an estimated NOx elimination ratio of the catalytic converter based on an estimated catalyst temperature and the space velocity through the catalytic converter.

Abstract: The invention provides a catalyst deterioration detecting system that is capable of detecting the degree of deterioration of each catalyst in a catalyst converter which includes two or more catalysts in series.