Abstract: An exhaust emission control device for an engine is provided with a first purifying catalyst including an HC adsorbent that adsorbs HC at a low temperature and releases HC at a high temperature and a diesel oxidation catalyst capable of oxidizing HC, a second purifying catalyst including a NOx catalyst capable of storing NOx contained in exhaust, a NOx catalyst regenerator that regenerates the NOx catalyst while raising the temperature of the NOx catalyst, and HC controller that decides whether the amount of adsorbed HC that is HC adsorbed by the HC adsorbent is equal to or more than a preset reference amount and, when the amount of adsorbed HC is decided to be equal to or more than the reference amount, raises the temperature of the first purifying catalyst.

Abstract: A control system for an engine is provided, which includes an engine body formed with a cylinder, a NOx catalyst, an oxidation catalyst, a PM filter, a fuel injector configured to perform a main injection and a post injection, and a controller configured to execute a DeNOx control in which the fuel injector is controlled to perform the main and post injections so that an air-fuel ratio of exhaust gas is brought close to the stoichiometric air-fuel ratio or becomes rich and fuel supplied into the cylinder by the post injection combusts therein, and a filter regenerating control in which the fuel injector is controlled to perform the main and post injections so that the air-fuel ratio becomes lean and the fuel supplied into the cylinder by the post injection causes no combustion therein, the controller executing the DeNOx control and the filter regenerating control consecutively in this order.

Abstract: A NOx catalyst is provided on an exhaust passage of an engine. The NOx catalyst reduces the occluded NOx when an air-fuel ratio of exhaust gas is in the vicinity of a stoichiometric air-fuel ratio or in a richer state than the stoichiometric air-fuel ratio. Turbocharging is executed by turbochargers. In a low load region within the reduction execution region, a target air-fuel ratio is achieved, as required for NOx reduction, by air amount adjustment with an air amount control valve provided on an intake passage. Since a large amount of air is needed in the high load region within the reduction execution region, the target air-fuel ratio is achieved by air amount adjustment using turbocharging pressure control.

Abstract: An exhaust emission control system of an engine, including an NOx catalyst disposed in an exhaust passage for storing NOx within exhaust gas when an air-fuel ratio of the exhaust gas is lean, and reducing the stored NOx when the air-fuel ratio is approximately stoichiometric or rich, is provided. The system includes an SCR catalyst disposed in the exhaust passage downstream of the NOx catalyst and for purifying NOx within exhaust gas by causing a reaction with ammonia, a controller executing a NOx reduction controlling module for executing a control in which the air-fuel ratio is controlled to a target air-fuel ratio so that the stored NOx is reduced, and an ammonia adsorption amount acquiring module for acquiring an ammonia adsorption amount of the SCR catalyst by detection or estimation. The NOx reduction controlling module controls the target air-fuel ratio to be leaner as the ammonia adsorption amount increases.

Abstract: An exhaust emission control system of an engine including a NOx catalyst disposed in an exhaust passage and for storing NOx within exhaust gas when an air-fuel ratio of the exhaust gas is lean, and reducing the stored NOx when the air-fuel ratio is approximately stoichiometric or rich, is provided. The system includes a SCR catalyst disposed downstream of the NOx catalyst and for purifying NOx by causing a reaction with ammonia, and a processor configured to execute a NOx reduction controlling module for controlling the air-fuel ratio to a target ratio so that the stored NOx is reduced. The controlling module limits the performance of the NOx reduction control when a temperature of the SCR catalyst is above a given temperature and loosens the limitation in a given engine operating state in which an exhaust gas flow rate is above a given rate despite the SCR catalyst temperature.

Abstract: An exhaust emission control system is provided, which includes a NOx storage catalyst provided in an exhaust passage of an engine and configured to store NOx, a urea SCR catalyst provided in the exhaust passage, downstream of the NOx storage catalyst, and a NOx reduction controlling module configured to set a NOx reduction condition and, when the NOx reduction condition is satisfied, performs NOx reduction processing in which an air-fuel ratio of exhaust gas is set to be one of near a stoichiometric air-fuel ratio and rich, and the NOx stored in the NOx storage catalyst is reduced, the NOx reduction condition being set looser for the NOx reduction processing performed the first time after the engine is started than the NOx reduction processing performed the second and subsequent times after the engine is started.

Abstract: An exhaust emission control system of an engine including a NOx catalyst for storing NOx within exhaust gas when an air-fuel ratio thereof is lean, and reducing the NOx when the air-fuel ratio is approximately stoichiometric or rich, the NOx catalyst also functioning as an oxidation catalyst for oxidizing HC, is provided. The system includes a SCR catalyst for purifying NOx by causing a reaction with NH3, a urea injector, and a processor configured to execute a fuel injection controlling module, and a NOx reduction controlling module for performing a NOx reduction control to enrich the air-fuel ratio to a target ratio. When the urea injection is abnormal, the NOx reduction controlling module performs an NH3-supplied NOx reduction control in which the NOx catalyst supplies NH3 to the SCR catalyst, by performing the NOx reduction control, a lean air-fuel ratio operation control, and then the NOx reduction control again.

Abstract: An exhaust emission control device for an engine is provided with a first purifying catalyst including an HC adsorbent that adsorbs HC at a low temperature and releases HC at a high temperature and a diesel oxidation catalyst capable of oxidizing HC, a second purifying catalyst including a NOx catalyst capable of storing NOx contained in exhaust, a NOx catalyst regenerator that regenerates the NOx catalyst while raising the temperature of the NOx catalyst, and HC controller that decides whether the amount of adsorbed HC that is HC adsorbed by the HC adsorbent is equal to or more than a preset reference amount and, when the amount of adsorbed HC is decided to be equal to or more than the reference amount, raises the temperature of the first purifying catalyst.

Abstract: An exhaust emission control system of an engine is provided including a NOx catalyst for oxidizing HC and storing NOx within exhaust gas when an air-fuel ratio of the exhaust gas is lean, and reducing the NOx when the air-fuel ratio is approximately stoichiometric or rich. The system includes a SCR catalyst for purifying NOx by causing a reaction with NH3, a urea injector, a fuel injection controlling module, and a processor configured to execute a NOx reduction controlling module for performing a NOx reduction control to enrich the air-fuel ratio to reach a target ratio. When the urea injection is determined to be abnormal, the NOx reduction controlling module performs a NH3-supplied NOx reduction control in a state where a larger amount of unburned fuel than the amount of unburned fuel in the exhaust passage in the NOx reduction control is supplied to the exhaust passage.

Abstract: An exhaust emission control system of an engine is provided, which includes a NOx catalyst disposed in an exhaust passage for storing NOx within exhaust gas when an air-fuel ratio of the exhaust gas is lean, and reducing the stored NOx when the air-fuel ratio is approximately stoichiometric or rich. A processor executes a NOx reduction controlling module for performing, when the NOx stored amount exceeds a given amount, a NOx reduction control in which a fuel injector performs a post injection of fuel to continuously control the air-fuel ratio to a target ratio so that the stored NOx is reduced to be below a given amount, the target air-fuel ratio being a ratio at which the stored NOx is reducible, the post injection causing the injected fuel to combust inside a cylinder, the execution of the control permitted when an engine load is within a medium load range.

Abstract: A control system for an engine is provided, which includes an engine body formed with a cylinder, a NOx catalyst, an oxidation catalyst, a PM filter, a fuel injector configured to perform a main injection and a post injection, and a controller configured to execute a DeNOx control in which the fuel injector is controlled to perform the main and post injections so that an air-fuel ratio of exhaust gas is brought close to the stoichiometric air-fuel ratio or becomes rich and fuel supplied into the cylinder by the post injection combusts therein, and a filter regenerating control in which the fuel injector is controlled to perform the main and post injections so that the air-fuel ratio becomes lean and the fuel supplied into the cylinder by the post injection causes no combustion therein, the controller executing the DeNOx control and the filter regenerating control consecutively in this order.

Abstract: A NOx catalyst is provided on an exhaust passage of an engine. The NOx catalyst reduces the occluded NOx when an air-fuel ratio of exhaust gas is in the vicinity of a stoichiometric air-fuel ratio or in a richer state than the stoichiometric air-fuel ratio. Turbocharging is executed by turbochargers. In a low load region within the reduction execution region, a target air-fuel ratio is achieved, as required for NOx reduction, by air amount adjustment with an air amount control valve provided on an intake passage. Since a large amount of air is needed in the high load region within the reduction execution region, the target air-fuel ratio is achieved by air amount adjustment using turbocharging pressure control.

Abstract: An exhaust emission control system is provided, which includes a NOx storage catalyst provided in an exhaust passage of an engine and configured to store NOx, a urea SCR catalyst provided in the exhaust passage, downstream of the NOx storage catalyst, and a NOx reduction controlling module configured to set a NOx reduction condition and, when the NOx reduction condition is satisfied, performs NOx reduction processing in which an air-fuel ratio of exhaust gas is set to be one of near a stoichiometric air-fuel ratio and rich, and the NOx stored in the NOx storage catalyst is reduced, the NOx reduction condition being set looser for the NOx reduction processing performed the first time after the engine is started than the NOx reduction processing performed the second and subsequent times after the engine is started.

Abstract: An exhaust emission control system of an engine including a NOx catalyst disposed in an exhaust passage and for storing NOx within exhaust gas when an air-fuel ratio of the exhaust gas is lean, and reducing the stored NOx when the air-fuel ratio is approximately stoichiometric or rich, is provided. The system includes a SCR catalyst disposed downstream of the NOx catalyst and for purifying NOx by causing a reaction with ammonia, and a processor configured to execute a NOx reduction controlling module for controlling the air-fuel ratio to a target ratio so that the stored NOx is reduced. The controlling module limits the performance of the NOx reduction control when a temperature of the SCR catalyst is above a given temperature and loosens the limitation in a given engine operating state in which an exhaust gas flow rate is above a given rate despite the SCR catalyst temperature.

Abstract: An exhaust emission control system of an engine including a NOx catalyst for storing NOx within exhaust gas when an air-fuel ratio thereof is lean, and reducing the NOx when the air-fuel ratio is approximately stoichiometric or rich, the NOx catalyst also functioning as an oxidation catalyst for oxidizing HC, is provided. The system includes a SCR catalyst for purifying NOx by causing a reaction with NH3, a urea injector, and a processor configured to execute a fuel injection controlling module, and a NOx reduction controlling module for performing a NOx reduction control to enrich the air-fuel ratio to a target ratio. When the urea injection is abnormal, the NOx reduction controlling module performs an NH3-supplied NOx reduction control in which the NOx catalyst supplies NH3 to the SCR catalyst, by performing the NOx reduction control, a lean air-fuel ratio operation control, and then the NOx reduction control again.

Abstract: An exhaust emission control system of an engine is provided including a NOx catalyst for oxidizing HC and storing NOx within exhaust gas when an air-fuel ratio of the exhaust gas is lean, and reducing the NOx when the air-fuel ratio is approximately stoichiometric or rich. The system includes a SCR catalyst for purifying NOx by causing a reaction with NH3, a urea injector, a fuel injection controlling module, and a processor configured to execute a NOx reduction controlling module for performing a NOx reduction control to enrich the air-fuel ratio to reach a target ratio. When the urea injection is determined to be abnormal, the NOx reduction controlling module performs a NH3-supplied NOx reduction control in a state where a larger amount of unburned fuel than the amount of unburned fuel in the exhaust passage in the NOx reduction control is supplied to the exhaust passage.

Abstract: An exhaust emission control system of an engine, including an NOx catalyst disposed in an exhaust passage for storing NOx within exhaust gas when an air-fuel ratio of the exhaust gas is lean, and reducing the stored NOx when the air-fuel ratio is approximately stoichiometric or rich, is provided. The system includes an SCR catalyst disposed in the exhaust passage downstream of the NOx catalyst and for purifying NOx within exhaust gas by causing a reaction with ammonia, a controller executing a NOx reduction controlling module for executing a control in which the air-fuel ratio is controlled to a target air-fuel ratio so that the stored NOx is reduced, and an ammonia adsorption amount acquiring module for acquiring an ammonia adsorption amount of the SCR catalyst by detection or estimation. The NOx reduction controlling module controls the target air-fuel ratio to be leaner as the ammonia adsorption amount increases.

Abstract: An exhaust emission control system of an engine is provided, which includes a NOx catalyst disposed in an exhaust passage for storing NOx within exhaust gas when an air-fuel ratio of the exhaust gas is lean, and reducing the stored NOx when the air-fuel ratio is approximately stoichiometric or rich. A processor executes a NOx reduction controlling module for performing, when the NOx stored amount exceeds a given amount, a NOx reduction control in which a fuel injector performs a post injection of fuel to continuously control the air-fuel ratio to a target ratio so that the stored NOx is reduced to be below a given amount, the target air-fuel ratio being a ratio at which the stored NOx is reducible, the post injection causing the injected fuel to combust inside a cylinder, the execution of the control permitted when an engine load is within a medium load range.

Abstract: An exhaust emission control system of an engine is provided, which includes a NOx catalyst disposed in an exhaust passage for storing NOx within exhaust gas when an air-fuel ratio of the exhaust gas is lean, and reducing the stored NOx when the air-fuel ratio is approximately stoichiometric or rich. A processor executes a NOx reduction controlling module for performing a NOx reduction control in which a fuel injector performs a post injection to control the air-fuel ratio to a target ratio, and an EGR controlling module for controlling an EGR valve to recirculate EGR gas. In the NOx reduction control, the EGR controlling module controls an opening of the EGR valve to a target opening smaller than when the NOx reduction control is not performed. The NOx reduction controlling module starts the control after the EGR valve opening is controlled to the target opening.

Abstract: An exhaust gas recirculation control device of an engine is provided. The device includes: an exhaust turbocharger having a turbine disposed in an exhaust passage and a compressor disposed in an intake passage; an intercooler disposed in the intake passage downstream of the compressor; a low-pressure EGR passage connecting the exhaust passage downstream of the turbine to the intake passage upstream of the compressor; a low-pressure EGR valve disposed in the low-pressure EGR passage and for changing a cross-sectional area thereof; a high-pressure EGR passage connecting the exhaust passage upstream of the turbine to the intake passage downstream of the intercooler; a high-pressure EGR valve disposed in the high-pressure EGR passage and for changing a cross-sectional area thereof; a valve control device for controlling openings of the low-pressure and high-pressure EGR valves; and a gear range detector for detecting a gear range of a transmission.