Robert Boschgmbh

Frank Schweizer

Stefan Scherer

Andreas Pfaeffle

Wolfgang Klenk

Christian Walz

Stefan Forthmann

Gerd Hartmann

Andreas Schaffrath

A method for controlling an SCR catalytic converter (), comprising detecting () concentration values () in the exhaust gas downstream of the catalytic converter (), wherein at least one concentration value for NHand one concentration value for NOis detected; calculating () modeled concentration values () for NHand NOdownstream of the catalytic converter on the basis of a catalytic converter model, wherein the model comprises an aging parameter () which at least partially describes aging of the modeled catalytic converter; comparing () the detected concentration values with the modeled concentration values; and, in a manner dependent on the result of the comparison, changing the aging parameter () of the model and/or changing a predefined dosing quantity for a reducing agent in the SCR catalytic converter.

Method for controlling an SCR catalytic converter

The invention concerns a method for controlling an SCR catalytic converter. A first modelled level of ammonia (NH3_mod1) and a second modelled level of ammonia (NH3_mod2) of the SCR catalytic converter are determined from two different models. The second modelled level of ammonia (NH3_mod2) is assessed by comparing it with the first modelled level of ammonia (NH3_mod1).

A method () for operating an SCR catalytic converter system which has a first SCR catalytic converter () and a second SCR catalytic converter, characterized by a step of controlling () an NHmass flow after the first SCR catalytic converter ().

Method for operating an SCR catalytic converter system which has a first SCR catalytic converter and a second SCR catalytic converter

A method for determining a mass flow of ammonia between two SCR catalytic converters disposed one after the other in an SCR catalytic converter system in an exhaust system, which comprises only one reduction agent dosing unit upstream of the first SCR catalytic converter, characterized in that the determination is carried out from the signal of a NOx sensor disposed between the two SCR catalytic converters and the signal of a NOx sensor disposed downstream of the second SCR catalytic converter.

Determining an ammonia mass flow between two SCR catalytic converters

In a method for operating an SCR catalytic converter provided for the reduction of NOx in exhaust gases of an internal combustion engine, which SCR catalytic converter is operated with a reagent which can be stored in the SCR catalytic converter such that there is a certain reagent fill level in the SCR catalytic converter, wherein the actual NOx concentration downstream of the SCR catalytic converter is monitored on the basis of the signal of a sensor, which is arranged downstream of the SCR catalytic converter and which is sensitive at least with respect to NOx, in comparison with a calculated NOx concentration downstream of the SCR catalytic converter, it is provided according to the invention that, in the case of a comparison result which represents a conversion deficit as a difference between the measured actual NOx concentration and the previous calculated reagent fill level in the SCR catalytic converter is corrected to a new calculated reagent fill level, whereby an immediate dosing of reagent takes place.

Method for operating an SCR catalyic converter provided for the aftertreatment of exhaust gases of an internal combustion engine

A procedure for metering a reagent into an exhaust duct of a combustion engine, which is required for a catalytic conversion of NOx in a SCR-catalyzer and a device for implementing the procedure are suggested. Determined is the difference between a calculated and a measured NOx-concentration each downstream after the SCR-catalyzer. The difference is compared to a difference threshold. After an exceeding of the difference threshold a lowering of the metering rate on to a sinking metering rate is undertaken, which is higher than zero. After a waiting time, a comparison of the calculated and the measured NOx-concentration is provided each downstream after the SCR-catalyzer. If the measured NOx-concentration is above the calculated NOx-concentration the metering rate is increased. If the measured NOx-concentration is below the calculated NOx-concentration the metering rate is lowered. The approach according to the invention enables an adaptation of the metering, at which it is ensured that a NOx-conversion can always take place.

Procedure for metering a reagent and device for implementing the procedure

A combustion engine has in the exhaust gas area a SCR-catalyzer with a NH-filling level, a metering device for supplying the SCR-catalyzer with reactant for reducing nitrous gases, and a downstream NH-sensitive NOx-sensor. One theoretical value for the NOx downstream of the SCR-catalyzer is compared to an actual NOx-value downstream of the SCR-catalyzer. A reasonability check includes determining a first value for one comparison parameter, which represents the state before a system intervention for adapting the NH-filling level. A system intervention for adapting the NH3-filling level is carried out and a second value of the comparison parameter is detected. From the comparison of the first value and the second value the reasonability, the non-reasonability, or non-preciseness of the system intervention is assumed.

Procedure for operating a combustion engine with a SCR-catalyzer

The invention relates to a method for regenerating an emission control system of an internal combustion engine, comprising a storage catalytic converter, a first exhaust gas probe being situated in an exhaust gas tract upstream of the storage catalytic converter and a second exhaust gas probe being situated in a second exhaust gas tract downstream of the storage catalytic converter. A first output signal of a first exhaust gas probe and a second output signal of a second exhaust gas probe are supplied to an engine management system and the storage catalytic converter is regenerated by being exposed to a reductant in a regeneration phase. If the quantity of reductant is controlled by the engine management system during the regeneration phase, whereby said system detects the quantity of reductant that is present downstream of the storage catalytic converter by means of the second output signal of the second exhaust gas probe situated downstream of said converter, the charging of reductant can be significantly reduced with respect to an optimised dosage. Excess consumption of fuel or reductant as a result of the regeneration of the storage catalytic converter is minimised. In addition, the method improves the emission values, thus significantly contributing to the maintenance of emission limits.

Method and device for regenerating an emission control system

The disclosure concerns a procedure for the regeneration of a particle filter and the desulfurization of a NOstorage catalytic converter in an exhaust gas aftertreatment system of an internal combustion engine. The disclosed procedure allows for the necessary heating energy and fuel consumption required to completely or partially regenerating the particle filter to be significantly reduced. Furthermore, an increase in efficiency of the NOstorage catalytic converter results, because the process reduces the average sulfur absorption on account of a greater frequency of desulfurization phases. In so doing, the NOemissions after the NOstorage catalytic converter can further be reduced.

[object Object]

A procedure is introduced to operate a diesel engine, which has a catalytic converter with three-way conversion characteristics. The procedure is characterized thereby, in that if the engine rotational speed increases without in the process exceeding an engine rotational speed threshold value and the engine's load is greater than a load threshold value, the diesel engine is operated in such a manner that the diesel engine alternately generates an oxidizing and a reductive exhaust gas atmosphere before the catalytic converter. Additionally a control unit is introduced, which controls the sequence of the procedure.

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Schwaikheim, Germany

Frank Schweizer