초록 ▼

In a diesel particulate filtering device1A,1B which is provided with a diesel particulate filter units10, 20, 30for cleaning exhaust gas, and in which cleaning of the exhaust gas and the recovery thereof are performed, diesel particulate filter controllers60, 62for determining a recovery time based

In a diesel particulate filtering device1A,1B which is provided with a diesel particulate filter units10, 20, 30for cleaning exhaust gas, and in which cleaning of the exhaust gas and the recovery thereof are performed, diesel particulate filter controllers60, 62for determining a recovery time based on detected values PI, PO0, PO1, PO2 of exhaust pressure sensors51to55in an upstream side of said diesel particulate filter units10, 20, 30and a downstream side thereof are provided with determination-value update means60a,62aresetting determination values R0, R1, R2 for determining a recovery time by comparing the detected values, PO0, PO1, PO2 with a standard exhaust pressure value P0. According to this constitution, the determination values R0, R1, R2 for determining the recovery time can be corrected simply by using determination-value update means60a,62awithout changing contents of a control program when mounting it on a motor vehicle and coping with variations in output of the pressure sensors51to55due to time aging and so forth.

대표청구항 ▼

In a diesel particulate filtering device1A,1B which is provided with a diesel particulate filter units10, 20, 30for cleaning exhaust gas, and in which cleaning of the exhaust gas and the recovery thereof are performed, diesel particulate filter controllers60, 62for determining a recovery time based

In a diesel particulate filtering device1A,1B which is provided with a diesel particulate filter units10, 20, 30for cleaning exhaust gas, and in which cleaning of the exhaust gas and the recovery thereof are performed, diesel particulate filter controllers60, 62for determining a recovery time based on detected values PI, PO0, PO1, PO2 of exhaust pressure sensors51to55in an upstream side of said diesel particulate filter units10, 20, 30and a downstream side thereof are provided with determination-value update means60a,62aresetting determination values R0, R1, R2 for determining a recovery time by comparing the detected values, PO0, PO1, PO2 with a standard exhaust pressure value P0. According to this constitution, the determination values R0, R1, R2 for determining the recovery time can be corrected simply by using determination-value update means60a,62awithout changing contents of a control program when mounting it on a motor vehicle and coping with variations in output of the pressure sensors51to55due to time aging and so forth. until a predetermined air/fuel ratio correction period has passed, when the first air/fuel ratio control portion switches the air/fuel ratio A/F in the combustion chamber from the lean state to the state near the theoretical air/fuel ratio, andwherein the first air/fuel ratio control portion,controls the air/fuel ratio A/F of the combustion chamber to the lean state, when the engine is in a predetermined operating region of low revolution speeds or low loads,feedback controls the air/fuel ratio A/F in the combustion chamber to a predetermined target value near the theoretical air/fuel ratio, based on a signal from the sensor, when the engine is in a preset operating region of at least one of higher revolution speeds and higher loads than that predetermined operating region, andfeedback controls the air/fuel ratio A/F of the combustion chamber to the slightly richer target value corrected by the air/fuel ratio correction portion, after the engine has shifted from the predetermined operating region to the preset operating region and until a predetermined air/fuel ratio correction period has passed.2. An exhaust gas purifying system for an engine, comprising: a catalyst provided in an exhaust duct, which is connected to a combustion chamber of the engine, and displaying a three-way purification function when an air/fuel ratio state of at least an exhaust gas corresponds substantially to a theoretical air/fuel ratio,wherein the catalyst is a NOx catalyst provided with an NOx absorbing material that absorbs NOx in the exhaust gas in an oxygen-rich atmosphere, and releases absorbed NOx when the oxygen concentration has dropped;a sensor for detecting concentration of a predetermined component of the exhaust gas upstream from the catalyst; anda control unit for controlling an air/fuel ratio A/F of the combusting gas mixture in the combustion chamber of the engine,wherein the control unit comprises:a first air/fuel ratio control portion for controlling the air/fuel ratio A/F in the combustion chamber by switching to either a lean state that is leaner than the theoretical air/fuel ratio or a state near the theoretical air/fuel ratio and richer than the lean state, depending on the operating state of the engine; andan air/fuel ratio correction portion for correcting a control target value of the air/fuel ratio A/F by the first air/fuel ratio control portion such that the control target value is slightly richer than the theoretical air/fuel ratio and within a range of 14.0≦A/Fa catalyst provided in an exhaust duct, which is connected to a combustion chamber of the engine, and displaying a three-way purification function when an air/fuel ratio state of at least an exhaust gas corresponds substantially to a theoret