Abstract: An emission control system and method execute a regeneration control such that a catalyst device recovers from poisoning, in a first control mode in which a temperature raising operation and a releasing operation are alternately repeated and in a second control mode in which the temperature raising operation and the releasing operation are alternately repeated. In the first control mode, the temperature raising operation is performed by post injection from a fuel injector. In the second control mode, the temperature raising operation is performed by adding fuel into exhaust gas from an addition valve such that the HC concentration in exhaust gas oscillates with an amplitude within a first specified range and a cycle within a second specified range. The control mode is switched from the first control mode to the second control mode during the regeneration control.

Abstract: An emission control system and method execute a regeneration control such that a catalyst device recovers from poisoning, in a first control mode in which a temperature raising operation and a releasing operation are alternately repeated and in a second control mode in which the temperature raising operation and the releasing operation are alternately repeated. In the first control mode, the temperature raising operation is performed by post injection from a fuel injector. In the second control mode, the temperature raising operation is performed by adding fuel into exhaust gas from an addition valve such that the HC concentration in exhaust gas oscillates with an amplitude within a first specified range and a cycle within a second specified range. The control mode is switched from the first control mode to the second control mode during the regeneration control.

Abstract: In an internal combustion engine, inside of an engine exhaust passage, a hydrocarbon feed valve (16), an exhaust purification catalyst (13), a particulate filter (14), and an NO2 reduction catalyst (15) are arranged. At the time of engine operation, the amplitude of change of the concentration of hydrocarbons which flow into the exhaust purification catalyst (13) is made to become within a predetermined range of amplitude by control of the injection amount of hydrocarbons from the hydrocarbon feed valve (16). When the NO2 which is produced at the particulate filter (14) should be reduced to NO, the injection amount of hydrocarbons is increased whereby the pass through amount of hydrocarbons which pass straight through the exhaust purification catalyst (13) is increased.

Abstract: An exhaust purification system of an internal combustion engine includes an NOX storage reduction catalyst device which is arranged in an engine exhaust passage. The NOX storage reduction catalyst device stores SOX simultaneously with NOX. When the stored SOX amount exceeds a predetermined allowable amount, the SOX is made to be released by SOX release control which raises the temperature of the NOX catalyst device to the SOX releasable temperature, then makes the air-fuel ratio of the exhaust gas which flows into the NOX catalyst device the stoichiometric air-fuel ratio or rich. The NOX catalyst device has a residual SOX storage amount which finally remains even if performing SOX release control depending on the temperature of the NOX catalyst device when performing SOX release control. The system uses the residual SOX storage amount of the current SOX release control as the basis to calculate the SOX release speed at each timing in the current SOX release control.

Abstract: The present invention is intended to improve a SOx reduction rate which is a ratio of an amount of SOx reduction with respect to an amount of SOx occlusion in SOx poisoning recovery processing. In the present invention, in the SOx poisoning recovery processing in which the SOx occluded in an NOx storage reduction catalyst is reduced by decreasing the air fuel ratio of an exhaust gas flowing into the NOx storage reduction catalyst to a predetermined air fuel ratio in a repeated manner, the length of a period in which the air fuel ratio of an exhaust gas flowing into the NOx storage reduction catalyst is decreased is made longer in a relatively early time during the processing than in a relatively late time during the processing.

Abstract: In an internal combustion engine, inside of an engine exhaust passage, a hydrocarbon feed valve (16), an exhaust purification catalyst (13), a particulate filter (14), and an NO2 reduction catalyst (15) are arranged. At the time of engine operation, the amplitude of change of the concentration of hydrocarbons which flow into the exhaust purification catalyst (13) is made to become within a predetermined range of amplitude by control of the injection amount of hydrocarbons from the hydrocarbon feed valve (16). When the NO2 which is produced at the particulate filter (14) should be reduced to NO, the injection amount of hydrocarbons is increased whereby the pass through amount of hydrocarbons which pass straight through the exhaust purification catalyst (13) is increased.

Abstract: A technique is provided which is capable of completing SOx poisoning recovery control on a NOx storage reduction catalyst in a shorter period of time. In the course of the SOx poisoning recovery control, the degree of decrease of a SOx release speed resulting from a decrease in an amount of SOx occlusion of the NOx catalyst (the degree of decrease of the SOx release speed (Ddw)) with respect to that at the time of start of the SOx poisoning recovery control is estimated. In accordance with the increasing degree of decrease of the SOx release speed (Ddw), a catalyst bed temperature (Tc) is caused to rise up to a higher side target temperature (Tct), and at the same time an exhaust gas air fuel ratio (A/F) is caused to lower up to a richer side target air fuel ratio (A/Ft), whereby the SOx release speed Vsox during the SOx poisoning recovery control is suppressed from lowering.

Abstract: An object of the invention is to recover the capability of an exhaust gas purification apparatus provided in an exhaust passage of an internal combustion engine with improved reliability. According to the invention there are provided recovery control execution unit for executing a recovery control in which the temperature of the exhaust gas purification apparatus is raised by supply of reducing agent to a precatalyst to thereby recover the capability of the exhaust gas purification apparatus and prohibition range setting unit for setting a recovery control prohibition range that is an operation range of the internal combustion engine in which execution of the recovery control by the recovery control execution unit is prohibited. The higher the degree of deterioration of the precatalyst is, the higher the maximum values of the engine torque and the engine revolution number in the recovery control prohibition range are set to be.

Abstract: The present invention is intended to improve a SOx reduction rate which is a ratio of an amount of SOx reduction with respect to an amount of SOx occlusion in SOx poisoning recovery processing. In the present invention, in the SOx poisoning recovery processing in which the SOx occluded in an NOx storage reduction catalyst is reduced by decreasing the air fuel ratio of an exhaust gas flowing into the NOx storage reduction catalyst to a predetermined air fuel ratio in a repeated manner, the length of a period in which the air fuel ratio of an exhaust gas flowing into the NOx storage reduction catalyst is decreased is made longer in a relatively early time during the processing than in a relatively late time during the processing.

Abstract: An exhaust purification system of an internal combustion engine includes an NOX storage reduction catalyst device which is arranged in an engine exhaust passage. The NO storage reduction catalyst device stores SOX simultaneously with NOX. When the stored SOX amount exceeds a predetermined allowable amount, the SOX is made to be released by SOX release control which raises the temperature of the NOX catalyst device to the SOX releasable temperature, then makes the air-fuel ratio of the exhaust gas which flows into the NOX catalyst device the stoichiometric air-fuel ratio or rich. The NOX catalyst device has a residual SOX storage amount which finally remains even if performing SOX release control depending on the temperature of the NOX catalyst device when performing SOX release control. The system uses the residual SOX storage amount of the current SOX release control as the basis to calculate the SOX release speed at each timing in the current SOX release control.

Abstract: A technique is provided which is capable of completing SOx poisoning recovery control on a NOx storage reduction catalyst in a shorter period of time. In the course of the SOx poisoning recovery control, the degree of decrease of a SOx release speed resulting from a decrease in an amount of SOx occlusion of the NOx catalyst (the degree of decrease of the SOx release speed (Ddw)) with respect to that at the time of start of the SOx poisoning recovery control is estimated. In accordance with the increasing degree of decrease of the SOx release speed (Ddw), a catalyst bed temperature (Tc) is caused to rise up to a higher side target temperature (Tct), and at the same time an exhaust gas air fuel ratio (A/F) is caused to lower up to a richer side target air fuel ratio (A/Ft), whereby the SOx release speed Vsox during the SOx poisoning recovery control is suppressed from lowering.

Abstract: An object of the invention is to recover the capability of an exhaust gas purification apparatus provided in an exhaust passage of an internal combustion engine with improved reliability. According to the invention there are provided recovery control execution unit for executing a recovery control in which the temperature of the exhaust gas purification apparatus is raised by supply of reducing agent to a precatalyst to thereby recover the capability of the exhaust gas purification apparatus and prohibition range setting unit for setting a recovery control prohibition range that is an operation range of the internal combustion engine in which execution of the recovery control by the recovery control execution unit is prohibited. The higher the degree of deterioration of the precatalyst is, the higher the maximum values of the engine torque and the engine revolution number in the recovery control prohibition range are set to be.