Method for Determining a Soot Load of a Particle Filter Provided with a Selective Catalytic Coating

Abstract

A method for determining a soot load on a particle filter provided with a selective catalytic coating is disclosed. The method includes determining a nitric oxide conversion on the particle filter and determining a soot load on the particle filter from the determined nitric oxide conversion.

1 .- 10 . (canceled) 
     
     
         11 . A method for determining a soot load of a particle filter provided with a selective catalytic coating, comprising the steps of:
 determining a nitric oxide conversion on the particle filter; and   determining a soot load of the particle filter from the determined nitric oxide conversion.   
     
     
         12 . The method according to  claim 11 , wherein the soot load is determined if an exhaust gas temperature in an exhaust tract upstream of the particle filter is greater than or equal to a predetermined minimum temperature and less than or equal to a predetermined maximum temperature and wherein the predetermined minimum temperature is from at least 175° C. to at most 210° C. and/or the predetermined maximum temperature is from at least 240° C. to at most 280° C. 
     
     
         13 . The method according to  claim 11 , wherein the soot load is determined if an exhaust gas temperature in an exhaust tract upstream of the particle filter is from at least 150° C. to at most 300° C. 
     
     
         14 . The method according to  claim 11 , wherein for the determining the soot load from the determined nitric oxide conversion, a ratio of a nitrogen dioxide concentration to a total nitrogen oxide concentration in exhaust gas upstream of the particle filter is used. 
     
     
         15 . The method according to  claim 14 , wherein the soot load is determined when the ratio of the nitrogen dioxide concentration to the total nitrogen oxide concentration is greater than a predetermined minimum value and wherein the predetermined minimum value is at least 10% to at most 50%. 
     
     
         16 . The method according to  claim 11 , wherein the nitric oxide conversion on the particle filter is determined by respective nitric oxide sensors disposed upstream and downstream of the particle filter. 
     
     
         17 . The method according to  claim 14 , wherein the ratio is determined based on a temperature of the exhaust gas upstream of the particle filter or a temperature of the exhaust gas upstream of an oxidation catalyst, a mass flow of the exhaust gas over the oxidation catalyst, and/or an aging status of the oxidation catalyst. 
     
     
         18 . The method according to  claim 11 , further comprising the step of comparing the determined nitric oxide conversion with a predetermined nitric oxide conversion of an unloaded particle filter, wherein the predetermined nitric oxide conversion is determined depending on an exhaust gas mass flow over the particle filter, an exhaust gas temperature upstream of the particle filter, a ratio of a nitrogen dioxide concentration to a total nitrogen oxide concentration upstream of the particle filter, a reducing agent load of the particle filter, an aging status of the particle filter, and/or on an operating point of an internal combustion engine that has the particle filter. 
     
     
         19 . The method according to  claim 11 , wherein the soot load of the particle filter is additionally determined by a load model and a differential pressure model, wherein a regeneration is performed if one of the soot load determinations returns a soot load that reaches or exceeds a predetermined maximum value. 
     
     
         20 . The method according to  claim 19 , wherein the soot load is determined from the determined nitric oxide conversion if a determined first load value based on the load model and a determined second load value based on the differential pressure model have a difference that reaches or exceeds a predetermined difference threshold. 
     
     
         21 . The method according to  claim 20 , wherein the soot load determined from the determined nitric oxide conversion is used for correction of the first and/or the second load values and/or for correction of at least one of the load model and the differential pressure model. 
     
     
         22 . The method according to  claim 11 , wherein specific conditions are set by controlling an exhaust gas recirculation device and/or by active heating of an oxidation catalyst under which the soot load of the particle filter is determined from the determined nitric oxide conversion.