Patent ID: 8191413

Claim:
A method for calculating an oxidation rate of soot retained in a particle filter that is arranged in an exhaust tract of a combustion device, downstream of an oxidation-catalytically active exhaust gas treatment element having a capability of converting nitrogen monoxide to nitrogen dioxide, using oxide sensors that are sensitive with regard to nitrogen monoxide and nitrogen dioxide, and that provide a nitrogen oxide output signal correlating with a total nitrogen oxide concentration representing the sum of the concentration of nitrogen monoxide and nitrogen dioxide; said method comprising: determining one of a nitrogen dioxide concentration and a concentration ratio of nitrogen dioxide and nitrogen monoxide downstream of said oxidation-catalytically active exhaust gas treatment element and upstream of said particle filter in said exhaust gas tract, by comparing a nitrogen oxide output signal of a first nitrogen oxide sensor that is arranged upstream of said oxidation-catalytically active exhaust gas treatment element in said exhaust gas tract, with a nitrogen oxide output signal of a second nitrogen oxide sensor that is arranged downstream of said oxidation-catalytically active exhaust gas treatment element and upstream of said particle filter in said exhaust gas tract; and calculating said oxidation rate of soot from the determined nitrogen dioxide concentration or concentration ratio of nitrogen dioxide and nitrogen monoxide.