Abstract: An exhaust emission control device comprises an oxidizing catalyst, a particulate filter on which soot is deposited, and a temperature sensor for detecting the temperature of exhaust gas on the upper-stream side of the filter. An intake system of an engine is provided with an EGR valve for returning the exhaust gas to the intake system. If the temperature of the oxidizing catalyst is found to be lower than its active temperature as the particulate filter is regenerated, the catalyst is heated by delaying the injection timing for the main fuel injection of the engine and increasing the EGR gas reflux quantity. Thus, the oxidizing catalyst can be heated up without lowering the fuel-efficiency, and soot on the particulate filter can be efficiently subjected to re-combustion.

Abstract: A control unit activates regeneration assist means, if a specific operating state involving incomplete combustion of particulates by NO2 continues for a predetermined period or more, as a first determination condition, and controls an exhaust gas temperature or a temperature of a catalyst to enhance the conversion efficiency of the catalyst into NO2, thereby continuously regenerating the particulates. The control unit activates forced regeneration means, if a deposited amount of particulates detected by deposited amount detecting means exceeds a predetermined value, as a second determination condition, and controls the exhaust gas temperature or a temperature of a filter to be higher than that of when the regeneration assist means is activated to forcibly regenerate the filter.

Abstract: A control unit activates regeneration assist means, if a specific operating state involving incomplete combustion of particulates by NO2 continues for a predetermined period or more, as a first determination condition, and controls an exhaust gas temperature or a temperature of a catalyst to enhance the conversion efficiency of the catalyst into NO2, thereby continuously regenerating the particulates. The control unit activates forced regeneration means, if a deposited amount of particulates detected by deposited amount detecting means exceeds a predetermined value, as a second determination condition, and controls the exhaust gas temperature or a temperature of a filter to be higher than that of when the regeneration assist means is activated to forcibly regenerate the filter.

Abstract: An exhaust emission control device comprises an oxidizing catalyst, a particulate filter on which soot is deposited, and a temperature sensor for detecting the temperature of exhaust gas on the upper-stream side of the filter. An intake system of an engine is provided with an EGR valve for returning the exhaust gas to the intake system. If the temperature of the oxidizing catalyst is found to be lower than its active temperature as the particulate filter is regenerated, the catalyst is heated by delaying the injection timing for the main fuel injection of the engine and increasing the EGR gas reflux quantity. Thus, the oxidizing catalyst can be heated up without lowering the fuel-efficiency, and soot on the particulate filter can be efficiently subjected to re-combustion.