Method for Operating a Nitrogen Oxide Storage Catalytic Converter in a Motor Vechicle with Consideration of Regional Fuel Qualities

Abstract

The fuel qualities for vehicles differ, for example, in Europe on a regional basis. This applies in particular to the sulphur content of the fuel. If vehicles with modern lean engines or with diesel engines which are equipped with nitrogen oxide storage-type catalytic converters in order to reduce the nitrogen oxide content in their exhaust gas pass through regions with a sulphur content in the fuel which is above the sulphur content which is specified for the vehicle, the engine controller will correspondingly frequently initiate desulphurization of the storage-type catalytic converter after the vehicle has been refuelled with this fuel. Any desulphurization entails an increased level of fuel consumption and greater ageing of the catalytic converter. It is proposed to avoid these adverse effects in that in lean motors the engine controller switches to stoichiometric operation in such a case, and in a diesel engine said engine controller prevents the desulphurization. The information about the region in which the vehicle is moving at a particular time can be transmitted to the engine controller by a navigation system.

1 . A method for operating a nitrogen oxide storage-type catalytic converter on a motor vehicle taking into account regional fuel qualities, wherein the vehicle is equipped with a petrol engine which operates in lean mode or with a diesel engine and has an electronic engine controller and a navigation system, characterized in that the electronic engine controller switches to stoichiometric operation in the case of the petrol engine which operates in the lean mode or prevents the automatic desulphurization of the nitrogen oxide storage-type catalytic converter in the case of the diesel engine if the navigation system recognizes that the vehicle is moving in a region with a high sulphur content in the fuel. 
   
   
       2 . The method according to  claim 1 , characterized in that the switching to stoichiometric operation or the prevention of the automatic desulphurization does not take place until the fuel which is still present in the fuel tank when the region with a high sulphur content has been entered has been consumed and it is necessary to refuel. 
   
   
       3 . The method according to  claim 1 , characterized in that the electronic engine controller is switched back to the normal operating mode again when the vehicle enters a region with the fuel quality which is prescribed for the vehicle, and the fuel with a relatively high sulphur content has been consumed.