Abstract: In exhaust gas purification system (10) including catalyst unit (50) carrying a NOx occlusion-reduction type catalyst, a first-stage rich control having a target air-fuel ratio lower than theoretical air-fuel ratio is conducted through addition of the amount of reducing agent meeting the amount of oxygen emitted in the initial stage of regeneration control. In the first-stage rich control, the completion of oxygen emission is judged on the basis of the oxygen concentration on the downstream side of catalyst unit (50). Upon determination of the completion of oxygen emission, a later-stage rich control close to the theoretical air-fuel ratio with the target air-fuel ratio increased over that of the first-stage rich control is carried out to thereby accomplish regeneration of the catalyst unit (50).

Abstract: An internal combustion engine exhaust gas purifying system (10) having a continuous regenerating diesel particulate filter system (3) on the exhaust passage (2) of an internal combustion engine (1) is constituted by including collected-quantity estimation means (5A) for estimating the quantity of collected particulate matter in a filter (3b) of the filter system for collecting the particulate matter and maximum-fuel-injection-quantity restricting means (5C) for restricting the maximum fuel injection quantity of the internal combustion engine (1) when the quantity of collected particulate matter estimated by the collected-quantity estimation means (51A) is equal to or more than a predetermined judgment value.

Abstract: To provide an exhaust gas purifying method and an exhaust gas purifying system capable of efficiently purging the sulfur accumulated in a NOx occluding reduction type catalyst, while preventing fuel consumption from deteriorating and preventing NOx, HC, and CO from being discharged into the atmosphere, in an exhaust gas purifying system constituted by combining a NOx purifying function by the NOx occluding reduction type catalyst with a PM purifying function by a DPF.

Abstract: In an exhaust gas purifying system (b 1) that purifies NOx for the exhaust gas from an internal combustion engine (E) through sulfur purging control by a NOx occlusion reduction type catalyst (41), sulfur purging is judged to have started when the oxygen concentration (Co) detected by an oxygen concentration detector (54) disposed downstream of the NOx occlusion reduction type catalyst (41) drops from a first predetermined oxygen concentration indicating that the NOx discharge condition to a second predetermined oxygen concentration indicating that NOx discharge has ended and that Sox discharge has started. Accordingly, during sulfur purging control by the NOx occlusion reduction type catalyst (41), consideration is given to the discharge of NOx without sulfur purging at the start of sulfur purging control; furthermore, this timing is judged by monitoring the concentration of oxygen downstream of the NOx occlusion reduction type catalyst (41), thus optimizing sulfur purging control.

Abstract: An exhaust gas cleaning method capable of maintaining an optimum NOx purification ratio in the continuously regenerative range of DPF in an exhaust gas cleaning system (1) having an NOx purification function and a PM purification function combined with each other and the exhaust gas cleaning system (1). In the exhaust gas cleaning system (1), NOx purification by an NOx occlusion/reduction type catalyst (42) and PM purification by a continuous regeneration type DPF (41) are preformed for exhaust gas from an internal combustion engine.

Abstract: To provide an exhaust gas purifying method for purifying the exhaust gas of an internal combustion engine (1) by an exhaust gas purifying system (10) having an oxidation catalyst (3a), which comprises the steps of estimating the quantity of unburnt hydrocarbon accumulated in a support of the oxidation catalyst (3a), performing a hydrocarbon removal control when an estimated accumulation quantity (Vhc) of the unburnt hydrocarbon exceeds a predetermined judgment value (Vhc0) and raising an exhaust gas temperature (T) to activate the oxidation catalyst (3a) and oxidizing and removing the accumulated unburnt hydrocarbon. Thereby, it is possible to prevent a white fume from being produced after a low exhaust temperature state of an idling operation or the like continues for a long time.

Abstract: In an exhaust gas purifying system wherein an NOx occlusion reduction type catalyst (30) including a catalytic metal and an NOx occluding substance is installed in an exhaust passage (3) of an engine (10), a restore processing against the sulfur poisoning of the NOx occlusion reduction type catalyst (30) is executed, by performing a lax rich control for controlling the air/fuel ratio of the exhaust gas to the theoretical air/fuel ratio or slightly lower than the theoretical air/fuel ratio, when the NOx occlusion reduction type catalyst (30) is heated equal or superior to the sulfur purge temperature. NOx is purified up effectively, by excluding effects of the sulfur poisoning, suppressing the deterioration of fuel-efficiency, by the control method for exhaust gas purifying system.

Abstract: An exhaust gas purifying system causes less torque fluctuation and is capable of preventing the occurrence of white smoke in a regeneration control operation for regenerating a continuous regeneration DPF 3. When the continuous regeneration DPF 3 with an oxidation catalyst 3Aa on the upstream side of a filter 3Ab is controlled to regenerate, an exhaust throttle valve 31 provided in an exhaust passage 2 is closed and a delay multi-step injection control is performed to increase the temperature of the exhaust gas if an exhaust temperature T1 at the inlet of the oxidation catalyst 3Aa is less than the activation temperature Ta of the oxidation catalyst.

Abstract: A regeneration control method for regenerating a continuously regenerating diesel particulate filter device capable of regenerating a filter by efficiently removing PM while suppressing the deterioration of fuel consumption and preventing a drivability from being deteriorated, wherein the clogged-state of the filter is judged in three or more phases of the clogged-state and, when the clogged-state of the filter reaches a specified phase, a specified regenerating mode operation set in correspondence with the reached phase is performed.

Abstract: In an exhaust gas purifying system (1) for removing NOx by a NOx occlusion reduction type catalyst (11) for exhaust gas of an internal combustion engine, the air-fuel ratio in the exhaust gas is controlled by setting the target air-fuel ratio at a predetermined first air-fuel ratio which is a rich air-fuel ratio by a sulfur purge control means (C24) after the start of sulfur purge, and thereafter, the air-fuel ratio in the exhaust gas is controlled by changing the target air-fuel ratio to the predetermined second air-fuel ratio which is a stoichiometric air-fuel ratio, when the oxygen concentration (Od) in the downstream of the NOx occlusion reduction type catalyst (11) measured by an oxygen concentration detection means (C12) becomes lower than a predetermined threshold. Thereby, sulfur component accumulated in the NOx occlusion reduction type catalyst (11) can be purged efficiently, while preventing carbon monoxide from being discharged into the atmospheric air.

Abstract: A regeneration control method for regenerating a continuously regenerating diesel particulate filter device capable of regenerating a filter by efficiently removing PM while suppressing the deterioration of fuel consumption and preventing a drivability from being deteriorated, wherein the clogged-state of the filter is judged in three or more phases of the clogged-state and, when the clogged-state of the filter reaches a specified phase, a specified regenerating mode operation set in correspondence with the reached phase is performed.

Abstract: To provide an exhaust gas purifying system capable of forcibly regenerating DPF by efficiently raising the temperature of exhaust gas even when an exhaust gas temperature is very low at the time of low load and low engine speed such as an idling operation. In an exhaust purifying system (1) having an exhaust throttling valve (31) and a DPF (3) in an exhaust passage and having regeneration control means (P1) for regenerating the DPF (3), the regeneration control means (P1) is provided with an exhaust gas temperature detection means (P22), a fuel injection control means (P11), and an exhaust throttling control means (P12) and includes regeneration control for performing the exhaust gas temperature raising control through the multistage delay injection by the fuel injection control means (P11) and through the exhaust throttling of the exhaust throttling valve (31).

Abstract: A regeneration control method for regenerating a continuously regenerating diesel particulate filter device capable of regenerating a filter by efficiently removing PM while suppressing the deterioration of fuel consumption and preventing a drivability from being deteriorated, wherein the clogged-state of the filter is judged in three or more phases of the clogged-state and, when the clogged-state of the filter reaches a specified phase, a specified regenerating mode operation set in correspondence with the reached phase is performed.

Abstract: In an exhaust gas purifying system (1) that purifies NOx for the exhaust gas from an internal combustion engine (E) through sulfur purging control by a NOx occlusion reduction type catalyst (41), sulfur purging is judged to have started when the oxygen concentration (Co) detected by an oxygen concentration detection means (54) disposed downstream of the NOx occlusion reduction type catalyst (41) drops from a first predetermined oxygen concentration indicating that the NOx discharge condition to a second predetermined oxygen concentration indicating that NOx discharge has ended and that SOx discharge has started. Accordingly, during sulfur purging control by the NOx occlusion reduction type catalyst (41), consideration is given to the discharge of NOx without sulfur purging at the start of sulfur purging control; furthermore, this timing is judged by monitoring the concentration of oxygen downstream of the NOx occlusion reduction type catalyst (41), thus optimizing sulfur purging control.

Abstract: The present invention concerns an diesel engine fuel injection control, and a regeneration control method of exhaust gas post-treatment apparatus using this fuel injection control, and the engine fuel injection control for performing after injections (Fas, Fam) after a main injection (Fm) for activation and regeneration of the exhaust gas post-treatment apparatus, through the rising of diesel engine exhaust gas temperature or the decrease of the oxygen concentration in the exhaust gas, is composed to perform the after injections (Fas, Fam) in a range of 40° ATDC to 90° ATDC of the crank angle. Whereby, the main injection can be burned, without misfire, even when the main injection is largely retarded, or, the injection quantity is increased/decreased, and the engine operation can be sustained, by keeping the engine combustion in a good state.

Abstract: In an exhaust gas purifying system (1) for applying NOx purification by a NOx occlusion reduction type catalyst (42) and PM purification by a DPF (41) to the exhaust gas of an internal combustion engine, when it is judged that both regeneration of the DPF (41) and sulfur purge of the NOx occlusion reduction type catalyst (42) are necessary, the DPF regeneration control for raising the temperature of the DPF (41) is performed and the sulfur purge control for decreasing the oxygen concentration of the exhaust gas flowing into the NOx occlusion reduction type catalyst (42) is intermittently repeated. Thereby, it is possible to efficiently purge the sulfur accumulated in the NOx occlusion reduction type catalyst while preventing deterioration of fuel efficiency and discharge of NOx, HC, and CO into atmospheric air.

Abstract: In an exhaust gas purifying system (1) for removing NOx by a NOx occlusion reduction type catalyst (11) for exhaust gas of an internal combustion engine, the air-fuel ratio in the exhaust gas is controlled by setting the target air-fuel ratio at a predetermined first air-fuel ratio which is a rich air-fuel ratio by a sulfur purge control means (C24) after the start of sulfur purge, and thereafter, the air-fuel ratio in the exhaust gas is controlled by changing the target air-fuel ratio to the predetermined second air-fuel ratio which is a stoichiometric air-fuel ratio, when the oxygen concentration (Od) in the downstream of the NOx occlusion reduction type catalyst (11) measured by an oxygen concentration detection means (C12) becomes lower than a predetermined threshold. Thereby, sulfur component accumulated in the NOx occlusion reduction type catalyst (11) can be purged efficiently, while preventing carbon monoxide from being discharged into the atmospheric air.

Abstract: An exhaust gas decontamination system and a method of exhaust gas decontamination wherein in the regeneration of NOx occlusion reduction type catalyst with respect to a lean-burn engine or diesel engine, even in the instance of rich burning accompanied by EGR, the NOx released from the NOx occlusion reduction type catalyst can satisfactorily be reduced and purged to thereby exhibit a high NOx removal ratio. The exhaust gas decontamination system (1) provided with the NOx occlusion reduction type catalyst (30) includes control unit (C1) comprising normal control operation means (C10), regeneration control initiation judging means (C20), catalyst activation control operation means (C30) and rich-burn control operation means (C40) capable of lowering the concentration of oxygen in the exhaust gas so as to realize such a constitution that the catalyst is carried out just before rich burning accompanied by EGR.

Abstract: To provide an exhaust gas purifying method and an exhaust gas purifying system capable of efficiently purging the sulfur accumulated in a NOx occluding reduction type catalyst, while preventing fuel consumption from deteriorating and preventing NOx, HC, and CO from being discharged into the atmosphere, in an exhaust gas purifying system constituted by combining a NOx purifying function by the NOx occluding reduction type catalyst with a PM purifying function by a DPF.

Abstract: To provide an exhaust gas purifying system capable of forcibly regenerating DPF by efficiently raising the temperature of exhaust gas even when an exhaust gas temperature is very low at the time of low load and low engine speed such as an idling operation. In an exhaust purifying system (1) having an exhaust throttling valve (31) and a DPF (3) in an exhaust passage and having regeneration control means (P1) for regenerating the DPF (3), the regeneration control means (P1) is provided with an exhaust gas temperature detection means (P22), a fuel injection control means (P11), and an exhaust throttling control means (P12) and includes regeneration control for performing the exhaust gas temperature raising control through the multistage delay injection by the fuel injection control means (P11) and through the exhaust throttling of the exhaust throttling valve (31).