A system includes a catalyst for receiving and treating exhaust gas generated by an engine, a passive NOx adsorber (PNA) positioned upstream of the catalyst, a bypass valve positioned upstream of the catalyst and the PNA, and a controller. The controller is configured to, determine that the catalyst is operating under cold start conditions, control the bypass valve to direct exhaust gas to the PNA, determine that the catalyst is no longer operating under cold start conditions and continue to control the bypass valve to direct exhaust gas to the PNA for a predetermined duration, and after the elapse of the predetermined duration, control the bypass valve to direct exhaust gas to the catalyst bypassing the PNA. The controller is also configured to detect a high transient torque demand while the exhaust gas is provided to the PNA, and split the torque demand between the engine and an electric motor.

Controlling exhaust after-treatment in a heavy-duty motor vehicle includes operating a diesel engine of a heavy-duty truck such that the diesel engine generates an exhaust gas flow that enters an exhaust after-treatment system of the heavy-duty truck, the exhaust after-treatment system including a selective catalytic reduction system, measuring a level of NO.sub.x gases in the exhaust gas flow downstream of the selective catalytic reduction system, and controlling a diesel exhaust fluid injector upstream of the selective catalytic reduction system to inject diesel exhaust fluid into the exhaust gas flow upstream of the selective catalytic reduction system at an injection rate that is based on the measured level of NO.sub.x gases.

A method (200) for ascertaining a catalytic converter state is proposed, wherein an exhaust-gas catalytic converter (130) is monitored on the basis of a catalytic converter model. Here, the catalytic converter model is adapted (250) in a manner dependent on measured values detected by means of one or more sensors (145, 147), wherein a frequency and/or a degree of the adaptation of the catalytic converter model is detected (260). The catalytic converter state is ascertained (270) as non-critical if the frequency and/or the degree of the adaptation do not exceed a predeterminable threshold value or is ascertained (270) as critical if the frequency and/or the degree of the adaptation exceed the predeterminable threshold value.

An exhaust purification system of an internal combustion engine includes a catalyst arranged in an exhaust passage of the internal combustion engine and able to store oxygen, a storage amount calculating part configured to calculate an oxygen storage amount of the catalyst, a poisoning amount calculating part configured to calculate a poisoning amount of the catalyst, and an oxygen amount control part configured to control an amount of oxygen supplied to the catalyst based on the oxygen storage amount and the poisoning amount.

Various embodiments include a catalyst measuring system for determining the aging of an SCR catalytic converter, the system comprising: a control device with a processor; an SCR catalytic converter for treating the exhaust gases of a vehicle; a high-frequency sensor for measuring a level of ammonia loading of the SCR catalytic converter; and an ammonia dosing system for injecting ammonia into an exhaust system of the vehicle. The control device instructs the ammonia dosing system to inject ammonia selectively into the exhaust system. The control device compares data measured by the high-frequency sensor with a predefined threshold value to determine the aging of the SCR catalytic converter.

An abnormality determination apparatus for an ammonia sensor is usable in an exhaust purification system including a catalyst, a supply apparatus, an ammonia sensor, an NO.sub.X sensor, and an oxygen sensor. During a continuation period within which ammonia supply to the catalyst continues after the supply apparatus stops supply of reductant, the abnormality determination apparatus calculates the ammonia concentration on a downstream side of the catalyst as a first concentration value, based on an output of the ammonia sensor and an output of the oxygen sensor. During the continuation period, the abnormality determination apparatus calculates the ammonia concentration on the downstream side of the catalyst as a second concentration value, based on an output of the NO.sub.X sensor and the output of the oxygen sensor. The abnormality determination apparatus determines presence or absence of abnormality in the ammonia sensor based on the first concentration value and the second concentration value.

This degradation diagnosis device for an exhaust purification system makes it possible to discover degradation of a constituting component in an exhaust purification system at an early stage. The degradation diagnosis device for an exhaust purification system that purifies exhaust gas discharged from an internal combustion engine into an exhaust pipe is provided with: a degradation degree estimation unit that estimates the degree of degradation due to corrosion of a constituting component in the exhaust purification system based on the temperature of exhaust gas and the amount of a reducing agent injected into the exhaust pipe; a determination unit that determines whether the degradation degree estimated by the degradation degree estimation unit exceeds a predetermined threshold; and an output unit that outputs the result of determination made by the determination unit.

Systems, apparatuses, and methods include an upstream exhaust analysis circuit structured to determine a characteristic of an exhaust gas stream entering a nitrous oxide (NOx) storage catalyst; a prediction circuit structured to predict a downstream NOx concentration of an exhaust gas stream exiting the NOx storage catalyst based on a model of a NOx storage capacity or a dynamic response of the NOx storage catalyst; a downstream exhaust analysis circuit structured to determine a downstream NOx concentration of the exhaust gas stream exiting the NOx storage catalyst; and a comparison circuit structured to compare the predicted downstream NOx concentration to the determined downstream NOx concentration, and determine a health of the NOx storage catalyst based on the comparison.

A method for diagnosing an aftertreatment component, wherein nitrogen oxide is reduced using a first catalytic converter upstream said aftertreatment component and a second catalytic converter downstream said aftertreatment component, said aftertreatment component oxidizing nitric oxide into nitrogen dioxide. A first sensor measure nitrogen oxide downstream said first catalytic converter but upstream said aftertreatment component, and a second sensor measure nitrogen oxide downstream said aftertreatment component. The method includes: supplying additive upstream said first catalytic converter; using said first and second sensors, performing a first measurement at a first temperature of said first aftertreatment component; using said first and second sensors, performing a second measurement at a second temperature of said first aftertreatment component; and diagnosing oxidation of nitric oxide into nitrogen dioxide in said aftertreatment component using said first and second measurements.

This degradation diagnosis device for an exhaust purification system makes it possible to discover degradation of a constituting component in an exhaust purification system at an early stage. The degradation diagnosis device for an exhaust purification system that purifies exhaust gas discharged from an internal combustion engine into an exhaust pipe is provided with: a degradation degree estimation unit that estimates the degree of degradation due to corrosion of a constituting component in the exhaust purification system based on the temperature of exhaust gas and the amount of a reducing agent injected into the exhaust pipe; a determination unit that determines whether the degradation degree estimated by the degradation degree estimation unit exceeds a predetermined threshold; and an output unit that outputs the result of determination made by the determination unit.