Abstract: An exhaust gas purification device is equipped with: an NOx purification unit disposed in exhaust gas piping of an engine supporting an NOx storage catalyst (NSC); a catalyzed soot filter (CSF) disposed downstream of the NOx purification unit supporting a particulate combustion catalyst causing captured particulates to combust; and an electronic control unit (ECU) which controls exhaust gas flowing into the NSC to be rich and which, by raising the temperature of the NSC, acts as a regeneration device that causes sulfur components captured in the NSC to be desorbed. The particulate combustion catalyst is provided where Ag and Pd have been alloyed on an Al2O3 carrier; the quantity of Ag supported by the Al2O3 carrier is 1.2-2.5 g/L; the quantity of Pd supported by the Al2O3 carrier is 0.7 g/L or less; and the ratio Ag/Pd of the Ag support quantity to the Pd support quantity is 1.7-8.3.

Abstract: An exhaust gas purification device is equipped with: an NOx purification unit disposed in exhaust gas piping of an engine supporting an NOx storage catalyst (NSC); a catalyzed soot filter (CSF) disposed downstream of the NOx purification unit supporting a particulate combustion catalyst causing captured particulates to combust; and an electronic control unit (ECU) which controls exhaust gas flowing into the NSC to be rich and which, by raising the temperature of the NSC, acts as a regeneration device that causes sulfur components captured in the NSC to be desorbed. The particulate combustion catalyst is provided where Ag and Pd have been alloyed on an Al2O3 carrier; the quantity of Ag supported by the Al2O3 carrier is 1.2-2.5 g/L; the quantity of Pd supported by the Al2O3 carrier is 0.7 g/L or less; and the ratio Ag/Pd of the Ag support quantity to the Pd support quantity is 1.7-8.3.

Abstract: An exhaust purification system for an internal combustion engine is provided that can maintain the NOx purification rate of a selective reduction catalyst at near the maximum thereof. The exhaust purification system is provided with an oxidation catalyst and CSF provided in the exhaust plumbing of the engine, a selective reduction catalyst that is provided in the exhaust plumbing on the downstream side of oxidation catalyst and CSF, and selectively reduces NOx in the exhaust, and a NO2 sensor that detects NO2 in the exhaust inside of the exhaust plumbing on the downstream side of the selective reduction catalyst. An ECU executes NO2-NOx ratio decrease processing to cause the NO2-NOx ratio corresponding to the ratio of NO2 to NOx in the exhaust flowing into the selective reduction catalyst to decrease, in a case of a detection value Vno2 from the NO2 sensor being greater than a predetermined value Vno2_th.

Abstract: An exhaust purification system is provided that can decrease the load acting on a device treating PM, even when switched to stoich operation. The exhaust purification system includes: a PM treatment device, a three-way purification catalyst, an LAF sensor, and an ECU (3) that performs feedback control so that an LAF sensor output (Vex) becomes a target value (Vop) determined so that the three-way purification reaction is optimized during stoich operation. The ECU (3) includes a fuel controller (32) that determines a fuel injection amount (Gfuel) so that a state in which an air/fuel ratio of the air/fuel mixture is leaner than stoich and a state richer than stoich are alternately realized by modulating a fuel correction amount (dGfuel) determined so as to cause the LAF sensor output (Vex) to converge to the target value (Vop) by employing a predetermined modulation algorithm.

Abstract: An exhaust gas purifying system includes: a SCR catalyst which has a function of reducing NOx and absorbing NO2; an upstream catalyst which is provided at the upstream side of the SCR catalyst and has a three-way purification function; and an air-fuel ratio controller which controls the air-fuel ratio of the air-fuel mixture. The controller calculates the NO2 storage amount of the SCR catalyst (S2), calculates a value of the NOx correlation parameter that increases in response to the NOx discharge amount (S4), sets the stoichiometry determination threshold value to a small value as the NO2 storage amount increases (S5), and changes the operation mode of the engine to the stoichiometry operation mode in which the air-fuel ratio is controlled to stoichiometry when the value of the NOx correlation parameter is larger than the stoichiometry determination threshold value (S6, S9).

Abstract: An exhaust purification system for an internal combustion engine is provided that can steadily maintain a NOx purification rate of a selective reduction catalyst to be high without allowing the fuel economy or marketability to deteriorate. The exhaust purification system includes a NO2—NOx ratio adjustment mechanism that causes a NO2—NOx ratio to change; and a NO2—NOx ratio perturbation controller that executes NO2—NOx ratio perturbation control so that a NO2 balance of the selective reduction catalyst in a predetermined time period, with NO2 adsorption being positive and NO2 release being negative, is 0. Herein, NO2—NOx ratio perturbation control is defined as control that alternately executes NO2 increase control to cause the NO2—NOx ratio to be greater than a reference value near 0.5, and NO2 decrease control to cause the NO2—NOx ratio to be less than the reference value.

Abstract: An exhaust purification system is provided that can decrease the load acting on a device treating PM, even when switched to stoich operation. The exhaust purification system includes: a PM treatment device, a three-way purification catalyst, an LAF sensor, and an ECU (3) that performs feedback control so that an LAF sensor output (Vex) becomes a target value (Vop) determined so that the three-way purification reaction is optimized during stoich operation. The ECU (3) includes a fuel controller (32) that determines a fuel injection amount (Gfuel) so that a state in which an air/fuel ratio of the air/fuel mixture is leaner than stoich and a state richer than stoich are alternately realized by modulating a fuel correction amount (dGfuel) determined so as to cause the LAF sensor output (Vex) to converge to the target value (Vop) by employing a predetermined modulation algorithm.

Abstract: An exhaust gas purifying system includes: a SCR catalyst which has a function of reducing NOx and absorbing NO2; an upstream catalyst which is provided at the upstream side of the SCR catalyst and has a three-way purification function; and an air-fuel ratio controller which controls the air-fuel ratio of the air-fuel mixture. The controller calculates the NO2 storage amount of the SCR catalyst (S2), calculates a value of the NOx correlation parameter that increases in response to the NOx discharge amount (S4), sets the stoichiometry determination threshold value to a small value as the NO2 storage amount increases (S5), and changes the operation mode of the engine to the stoichiometry operation mode in which the air-fuel ratio is controlled to stoichiometry when the value of the NOx correlation parameter is larger than the stoichiometry determination threshold value (S6, S9).

Abstract: An exhaust purification system for an internal combustion engine is provided that can steadily maintain a NOx purification rate of a selective reduction catalyst to be high without allowing the fuel economy or marketability to deteriorate. The exhaust purification system includes a NO2—NOx ratio adjustment mechanism that causes a NO2—NOx ratio to change; and a NO2—NOx ratio perturbation controller that executes NO2—NOx ratio perturbation control so that a NO2 balance of the selective reduction catalyst in a predetermined time period, with NO2 adsorption being positive and NO2 release being negative, is 0. Herein, NO2—NOx ratio perturbation control is defined as control that alternately executes NO2 increase control to cause the NO2—NOx ratio to be greater than a reference value near 0.5, and NO2 decrease control to cause the NO2—NOx ratio to be less than the reference value.

Abstract: An exhaust purification system for an internal combustion engine is provided that can maintain the NOx purification rate of a selective reduction catalyst at near the maximum thereof. The exhaust purification system is provided with an oxidation catalyst and CSF provided in the exhaust plumbing of the engine, a selective reduction catalyst that is provided in the exhaust plumbing on the downstream side of oxidation catalyst and CSF, and selectively reduces NOx in the exhaust, and a NO2 sensor that detects NO2 in the exhaust inside of the exhaust plumbing on the downstream side of the selective reduction catalyst. An ECU executes NO2-NOx ratio decrease processing to cause the NO2-NOx ratio corresponding to the ratio of NO2 to NOx in the exhaust flowing into the selective reduction catalyst to decrease, in a case of a detection value Vno2 from the NO2 sensor being greater than a predetermined value Vno2_th.