Abstract: Provided is an exhaust purification system including: an NOx occlusion reduction type catalyst that is provided in an exhaust system of an internal combustion engine, and occludes NOx when an exhaust gas is in a lean state, and reduces the NOx when the exhaust gas is in a rich state; a regeneration control unit that executes a regeneration process of bringing the exhaust gas into a rich state to reduce the NOx occluded in the NOx occlusion reduction type catalyst; a storing unit that stores an exhaust lambda prediction value in advance when the regeneration process is executed; a reduction amount estimating unit that estimates an NOx reduction amount when the regeneration process is executed; and a prohibition unit that prohibits the execution of the regeneration process by the regeneration control unit when the estimated NOx reduction amount is less than a predetermined lower limit threshold.

Abstract: An exhaust purification system including a NOx catalyst 32 provided in an exhaust passage of an internal combustion engine 10 and purifying NOx in exhaust; a MAF sensor 40 for acquiring an air flow-rate of the internal-combustion engine 10; a control unit 60, 70 that execute catalyst regeneration treatment of recovering a NOx purification ability of the NOx catalyst 32 by performing, in combination, air-based control of reducing air flow-rate of the internal-combustion engine 10 to a predetermined target air flow-rate and injection-based control of increasing a fuel injection amount, wherein, in a case of executing the catalyst regeneration treatment, the control unit 60, 70 starts with the air-based control and starts the injection-based control when the air flow-rate acquired by the MAF sensor 40 is reduced to the target air flow-rate.

Abstract: There is provided: a NOx occlusion reduction-type catalyst that is provided in an exhaust passage of an internal combustion engine, occludes NOx in exhaust when the exhaust is in a lean state, and reduces and purifies the occluded NOx when the exhaust is in a rich state; an exhaust injector that is provided in the exhaust passage and is positioned further upstream than the NOx occlusion reduction-type catalyst; a NOx-purging control unit that performs NOx purging of reducing and purifying the NOx occluded in the NOx occlusion reduction-type catalyst by lowering the exhaust to a prescribed target lambda by fuel injection by the exhaust injector; and a NOx-purging-prohibition processing unit that inhibits performance of the NOx purging in a case where the exhaust cannot be lowered to the target lambda even if the fuel injection is performed at a maximum limit injection amount of the exhaust injector.

Abstract: An exhaust purification system includes an exhaust after-treatment apparatus which is provided on an exhaust passage of an internal combustion engine and which includes catalysts for purifying exhaust gas, a catalyst temperature retention control module for executing a catalyst temperature retention control in which an intake air flow is reduced to thereby suppress a reduction in the temperature of the catalysts when the internal combustion engine is in a motoring state where fuel injection into the internal combustion engine is stopped, and a prohibition module for prohibiting the execution of the catalyst temperature retention control in a case where an activation of an exhaust brake system is detected while the internal combustion engine is in the motoring state.

Abstract: The embodiments include: a NOx occlusion/reduction catalyst which is provided to an exhaust passage of an internal combustion engine, occludes NOx in exhaust when the exhaust is in a lean state, and reduces and purifies occluded NOx when the exhaust is in a rich state; a NOx purging control unit which, when the exhaust is in the rich state, executes NOx purging in which the NOx occluded in the NOx occlusion/reduction catalyst is reduced and purified; and a NOx-purging-prohibition processing unit which, when at least one of a plurality of prohibition conditions is fulfilled, prohibits execution of catalyst regeneration processing by the NOx purging control unit even if a catalyst-regeneration-processing start request has been issued, and, when one of the prohibition conditions is fulfilled during execution of the catalyst regeneration processing, invalidates the prohibition condition and allows continued execution of the catalyst regeneration processing by the NOx purging control unit.

Abstract: An exhaust purification system includes; a catalyst provided in an exhaust passage of an engine to purify an exhaust gas; a catalyst temperature estimating unit that estimates a temperature of the catalyst based on an initial temperature of the catalyst at the time of starting of the engine and a caloric value of the catalyst which changes depending on an operating state of the internal combustion engine; and an initial catalyst temperature setting unit that sets an initial temperature of the catalyst based on a catalyst temperature stored immediately before stopping the engine, a temperature of an exhaust gas flowing into the catalyst which is stored immediately before stopping the engine, a temperature of an exhaust gas flowing into the catalyst which is acquired at the time of starting the engine, and a temperature of air taken into the engine which is acquired at the time of starting the engine.

Abstract: An exhaust purification system includes; a catalyst provided in an exhaust passage of an engine to purify an exhaust gas; a catalyst temperature estimating unit that estimates a temperature of the catalyst based on an initial temperature of the catalyst at the time of starting of the engine and a caloric value of the catalyst which changes depending on an operating state of the internal combustion engine; and an initial catalyst temperature setting unit that sets an initial temperature of the catalyst based on a catalyst temperature stored immediately before stopping the engine, a temperature of an exhaust gas flowing into the catalyst which is stored immediately before stopping the engine, a temperature of an exhaust gas flowing into the catalyst which is acquired at the time of starting the engine, and a temperature of air taken into the engine which is acquired at the time of starting the engine.

Abstract: The embodiments include: a NOx occlusion/reduction catalyst which is provided to an exhaust passage of an internal combustion engine, occludes NOx in exhaust when the exhaust is in a lean state, and reduces and purifies occluded NOx when the exhaust is in a rich state; a NOx purging control unit which, when the exhaust is in the rich state, executes NOx purging in which the NOx occluded in the NOx occlusion/reduction catalyst is reduced and purified; and a NOx-purging-prohibition processing unit which, when at least one of a plurality of prohibition conditions is fulfilled, prohibits execution of catalyst regeneration processing by the NOx purging control unit even if a catalyst-regeneration-processing start request has been issued, and, when one of the prohibition conditions is fulfilled during execution of the catalyst regeneration processing, invalidates the prohibition condition and allows continued execution of the catalyst regeneration processing by the NOx purging control unit.

Abstract: An exhaust purification system including a NOx catalyst 32 provided in an exhaust passage of an internal combustion engine 10 and purifying NOx in exhaust; a MAF sensor 40 for acquiring an air flow-rate of the internal-combustion engine 10; a control unit 60, 70 that execute catalyst regeneration treatment of recovering a NOx purification ability of the NOx catalyst 32 by performing, in combination, air-based control of reducing air flow-rate of the internal-combustion engine 10 to a predetermined target air flow-rate and injection-based control of increasing a fuel injection amount, wherein, in a case of executing the catalyst regeneration treatment, the control unit 60, 70 starts with the air-based control and starts the injection-based control when the air flow-rate acquired by the MAF sensor 40 is reduced to the target air flow-rate.

Abstract: Provided is an exhaust purification system including: an NOx occlusion reduction type catalyst that is provided in an exhaust system of an internal combustion engine, and occludes NOx when an exhaust gas is in a lean state, and reduces the NOx when the exhaust gas is in a rich state; a regeneration control unit that executes a regeneration process of bringing the exhaust gas into a rich state to reduce the NOx occluded in the NOx occlusion reduction type catalyst; a storing unit that stores an exhaust lambda prediction value in advance when the regeneration process is executed; a reduction amount estimating unit that estimates an NOx reduction amount when the regeneration process is executed; and a prohibition unit that prohibits the execution of the regeneration process by the regeneration control unit when the estimated NOx reduction amount is less than a predetermined lower limit threshold.

Abstract: An exhaust purification system includes; a catalyst provided in an exhaust passage of an engine to purify an exhaust gas; a catalyst temperature estimating unit that estimates a temperature of the catalyst based on an initial temperature of the catalyst at the time of starting of the engine and a caloric value of the catalyst which changes depending on an operating state of the internal combustion engine; and an initial catalyst temperature setting unit that sets an initial temperature of the catalyst based on a catalyst temperature stored immediately before stopping the engine, a temperature of an exhaust gas flowing into the catalyst which is stored immediately before stopping the engine, a temperature of an exhaust gas flowing into the catalyst which is acquired at the time of starting the engine, and a temperature of air taken into the engine which is acquired at the time of starting the engine.

Abstract: An exhaust purification system includes an exhaust after-treatment apparatus which is provided on an exhaust passage of an internal combustion engine and which includes catalysts for purifying exhaust gas, a catalyst temperature retention control module for executing a catalyst temperature retention control in which an intake air flow is reduced to thereby suppress a reduction in the temperature of the catalysts when the internal combustion engine is in a motoring state where fuel injection into the internal combustion engine is stopped, and a prohibition module for prohibiting the execution of the catalyst temperature retention control in a case where an activation of an exhaust brake system is detected while the internal combustion engine is in the motoring state.

Abstract: There is provided: a NOx occlusion reduction-type catalyst that is provided in an exhaust passage of an internal combustion engine, occludes NOx in exhaust when the exhaust is in a lean state, and reduces and purifies the occluded NOx when the exhaust is in a rich state; an exhaust injector that is provided in the exhaust passage and is positioned further upstream than the NOx occlusion reduction-type catalyst; a NOx-purging control unit that performs NOx purging of reducing and purifying the NOx occluded in the NOx occlusion reduction-type catalyst by lowering the exhaust to a prescribed target lambda by fuel injection by the exhaust injector; and a NOx-purging-prohibition processing unit that inhibits performance of the NOx purging in a case where the exhaust cannot be lowered to the target lambda even if the fuel injection is performed at a maximum limit injection amount of the exhaust injector.

Abstract: When a catalyst temperature of a catalyst device is at or below a lower limit air-fuel ratio richness control is prohibited. When a first timing, where an estimated value of a NOx storage amount has reached an enrichment start threshold value, and a second timing, based on a set interval time in an enrichment interval time map, are both satisfied, the control is started. The second timing is corrected by multiplying the set interval time by an enrichment interval correction coefficient preset based on the catalyst temperature and a storage ratio of the estimated value of the NOx storage amount to an enrichment start threshold value of the NOx storage amount. The frequency of the air-fuel ratio richness control of a catalyst device configured to recover a purification capacity of a catalyst is reduced, and the catalyst temperature is raised while preventing white smoke development and hydrocarbon slip, to thereby achieve improvement in exhaust gas composition and improvement in fuel efficiency.

Abstract: A diesel oxidation catalyst, a NOx occlusion reduction catalyst, and a diesel particulate filter are connected to an exhaust pipe of an engine, downstream of an exhaust pipe injector provided on the exhaust pipe. NOx in the exhaust gas is occluded by the NOx occlusion reduction catalyst when an air-fuel ratio is lean. The occluded NOx is reduced and purified when the air-fuel ratio is rich. When a prescribed amount of particulate matter has accumulated in the diesel particulate filter, the exhaust gas temperature is raised when performing particulate matter regeneration. The exhaust gas temperature is further raised to perform a sulphur purge. The rich condition is prohibited during the particulate matter regeneration period and the sulphur purge period.

Abstract: When a catalyst temperature of a catalyst device is at or below a lower limit air-fuel ratio richness control is prohibited. When a first timing, where an estimated value of a NOx storage amount has reached an enrichment start threshold value, and a second timing, based on a set interval time in an enrichment interval time map, are both satisfied, the control is started. The second timing is corrected by multiplying the set interval time by an enrichment interval correction coefficient preset based on the catalyst temperature and a storage ratio of the estimated value of the NOx storage amount to an enrichment start threshold value of the NOx storage amount. The frequency of the air-fuel ratio richness control of a catalyst device configured to recover a purification capacity of a catalyst is reduced, and the catalyst temperature is raised while preventing white smoke development and hydrocarbon slip, to thereby achieve improvement in exhaust gas composition and improvement in fuel efficiency.

Abstract: An exhaust gas purification system including a catalyst device configured to recover a purification capacity of a catalyst by an air-fuel ratio richness control, based on a richness control permission range where the air-fuel ratio richness control is permitted to be performed, and a richness control prohibition range where the air-fuel ratio richness control is prohibited from being performed. A catalyst temperature of the catalyst device and an air intake amount of an internal combustion engine are parameters for determining the richness control permission range or the richness control prohibition range. The richness control prohibition range is set as a range where the catalyst temperature of the catalyst device is lower than a preset lower limit catalyst temperature and the air intake amount is larger than a preset upper limit air intake amount. The lower limit catalyst temperature is set to a temperature lower than a catalyst activation temperature.

Abstract: A diesel oxidation catalyst, a NOx occlusion reduction catalyst, and a diesel particulate filter are connected to an exhaust pipe of an engine, downstream of an exhaust pipe injector provided on the exhaust pipe. NOx in the exhaust gas is occluded by the NOx occlusion reduction catalyst when an air-fuel ratio is lean. The occluded NOx is reduced and purified when the air-fuel ratio is rich. When a prescribed amount of particulate matter has accumulated in the diesel particulate filter, the exhaust gas temperature is raised when performing particulate matter regeneration. The exhaust gas temperature is further raised to perform a sulphur purge. The rich condition is prohibited during the particulate matter regeneration period and the sulphur purge period.

Abstract: An exhaust gas purification method of a diesel engine, which purifies exhaust gas while suppressing deterioration in drivability and fuel consumption, including when exhaust gas enters a rich reduction state, opening an EGR valve and closing an intake throttle, if a temperature of an NOx occlusion reduction catalyst is at or above a predetermined temperature, and a vehicle having a diesel engine is decelerating from a speed at or above a predetermined speed, and then closing an exhaust throttle provided downstream of the NOx occlusion reduction catalyst and supplying fuel to the NOx occlusion reduction catalyst as a reductant.

Abstract: An exhaust gas purification device 1 includes an exhaust gas processing device 30 provided in an exhaust passage 11 of an internal combustion engine 10, an in-exhaust pipe fuel injection device 24 provided on an upstream side of the exhaust gas processing device 30 to supply fuel to the exhaust gas processing device 30, a NOx sensor 13 provided on a downstream side of the exhaust gas processing device 30, and a control unit 40 that controls combustion in the internal combustion engine 10 based on operating state of the engine 10. To burn and remove PM trapped in the exhaust gas processing device 30, the control unit 40 causes the in-exhaust pipe fuel injection device 24 to supply the fuel to the exhaust gas processing device 30 and stores a detection value from the NOx sensor 13 as a NOx value at an outlet of the engine 10.