An internal combustion engine arrangement includes an internal combustion engine, a catalytic converter, and a controller. The controller is configured to determine a maximum H.sub.2 production capacity of the catalytic converter. The catalytic converter is arranged downstream of the internal combustion engine. The controller is configured and adapted to determine the maximum H.sub.2 production capacity of the catalytic converter based on a first function that correlates an H.sub.2 production of the internal combustion engine with first internal combustion engine parameters.

A control device for an internal combustion engine including an upstream cleaning device and a downstream cleaning device that are provided in an exhaust gas passage and a temperature sensor that detects a temperature of exhaust gas between the upstream cleaning device and the downstream cleaning device is provided. The control device includes a first temperature estimating unit configured to estimate a temperature of the downstream cleaning device from the temperature of exhaust gas detected by the temperature sensor and a second temperature estimating unit configured to estimate a temperature of the downstream cleaning device without using the temperature of exhaust gas detected by the temperature sensor. An abnormality determining process for the upstream cleaning device is performed when at least the temperature of the downstream cleaning device estimated by the second temperature estimating unit is equal to or greater than a predetermined threshold value.

A method that determines a cause for the impaired performance of a catalytic configuration of the exhaust gas of a combustion engine (231), the method including determining (s410) a course of a NOx-conversion ratio; determining (s420) a prevailing temperature of the catalytic configuration; increasing (s430) the temperature of the catalytic configuration from a prevailing temperature below a predetermined temperature value (Te) to a temperature (TSred) above the predetermined temperature value above which sulphur is removed from the catalytic configuration; and/or decreasing (s440) the temperature of the catalytic configuration from a prevailing temperature (TSred) above the predetermined temperature value (Te) to a temperature below the predetermined temperature value so as to impair the performance of the catalytic configuration in case sulphur is present; and determining (s450) one cause out of a set of causes on the basis of the course of the NOx-conversion ratio thus determined.

Methods and systems to control a temperature of a selective catalytic reduction catalyst are disclosed. In one example, a diverter valve that includes two butterfly valves that are coupled together via a shaft is adjusted to control a temperature at an inlet of the selective catalytic reduction catalyst so that the selective catalytic reduction catalyst may operate efficiently.

A control module for an aftertreatment system that includes a selective catalytic reduction (SCR) catalyst and an oxidation catalyst, comprises a controller configured to be operatively coupled to the aftertreatment system. The controller is configured to determine an actual SCR catalytic conversion efficiency of the SCR catalyst. The controller determines an estimated SCR catalytic conversion efficiency based on a test sulfur concentration selected by the controller. In response to the estimated SCR catalytic conversion efficiency being within a predefined range, the controller sets the test sulfur concentration as a determined sulfur concentration in a fuel provided to the engine. The controller generates a sulfur concentration signal indicating the determined sulfur.

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 aftertreatment system and associated system for purifying an exhaust gas feedstream of a lean-burn engine includes an oxidation catalyst that is arranged upstream of a selective catalytic reduction (SCR) catalyst. A first NOx sensor is arranged upstream, and a second NOx sensor is arranged downstream of the oxidation catalyst. A controller is arranged to monitor the oxidation catalyst based upon inputs from the first and second NOx sensors. A first NOx parameter is determined via the first NOx sensor, and a second NOx parameter is determined via the second NOx sensor. An NO2 parameter is determined based upon the first NOx parameter, the second NOx parameter, a first relationship for the first and second NOx sensors, and a second relationship for the first and second NOx sensors. The NO2 production of the oxidation catalyst is evaluated based upon the NO2 parameter.

Disclosed is a method for diagnosing a first exhaust treatment component for treatment of an exhaust gas stream comprising means for oxidizing nitric oxide into nitrogen dioxide. A first reduction catalytic converter is arranged upstream said means for oxidizing nitric oxide into nitrogen dioxide, and a second reduction catalytic converter is arranged downstream said means. A reagent is for reduction of nitrogen oxides in said first catalytic converter, and a first sensor measures an occurrence of nitrogen oxide downstream said means but upstream said second reduction catalytic converter. The method comprises: causing a supply of reagent upstream said first reduction catalytic converter to an extent exceeding the extent to which reagent is consumed by the first reduction catalytic converter, determining a first measure of the occurrence of reagent downstream said means for oxidizing, and diagnosing said means for oxidizing nitric oxide into nitrogen dioxide based on said first measure.

A control device for an internal combustion engine including an upstream cleaning device and a downstream cleaning device that are provided in an exhaust gas passage and a temperature sensor that detects a temperature of exhaust gas between the upstream cleaning device and the downstream cleaning device is provided. The control device includes a first temperature estimating unit configured to estimate a temperature of the downstream cleaning device from the temperature of exhaust gas detected by the temperature sensor and a second temperature estimating unit configured to estimate a temperature of the downstream cleaning device without using the temperature of exhaust gas detected by the temperature sensor. An abnormality determining process for the upstream cleaning device is performed when at least the temperature of the downstream cleaning device estimated by the second temperature estimating unit is equal to or greater than a predetermined threshold value.

This invention relates to exhaust replication systems and methods, such as systems for testing automotive exhaust aftertreatment devices. More particularly, methods for steady state and transient generation and flow of NO.sub.2 and/or NO from a fluid such as nitric acid for introduction into the burner-based exhaust replication system.