Method and Device to Determine the Nitrogen Oxide-Storage Capability of a Catalytic Converter of a Vehicle

Abstract

A method to determine a nitrogen oxide storage capacity of a catalytic converter of a vehicle in which a concentration of nitrogen oxides is measured in an exhaust gas downstream of the catalytic converter includes, in at least one first step, setting a concentration of nitrogen oxides in the exhaust gas at which the catalytic converter absorbs nitrogen oxides, and in at least one second step, setting a concentration of nitrogen oxides in the exhaust gas at which a desorption of nitrogen oxides by the catalytic converter takes place. The nitrogen oxide storage capacity of the catalytic converter is determined by considering a behavior of the catalytic converter at least during the desorption of nitrogen oxides.

1 .- 10 . (canceled) 
     
     
         11 . A method to determine a nitrogen oxide storage capacity of a catalytic converter of a vehicle in which a concentration of nitrogen oxides is measured in an exhaust gas downstream of the catalytic converter, comprising the steps of:
 in at least one first step, setting a concentration of nitrogen oxides in the exhaust gas at which the catalytic converter absorbs nitrogen oxides;   in at least one second step, setting a concentration of nitrogen oxides in the exhaust gas at which a desorption of nitrogen oxides by the catalytic converter takes place; and   determining the nitrogen oxide storage capacity of the catalytic converter by considering a behavior of the catalytic converter at least during the desorption of nitrogen oxides.   
     
     
         12 . The method according to  claim 11 , wherein the concentration of nitrogen oxides is set in the exhaust gas at which the catalytic converter absorbs nitrogen oxides such that a saturation of the catalytic converter with nitrogen oxides occurs. 
     
     
         13 . The method according to  claim 12 , wherein after the saturation, an overrun mode of the vehicle is realized, and wherein based on a chronological sequence of the desorption of nitrogen oxides, the nitrogen oxide storage capacity of the catalytic converter is inferred. 
     
     
         14 . The method according to  claim 11 , wherein in a plurality of first steps, the concentration of nitrogen oxides is set in the exhaust gas at which the catalytic converter absorbs nitrogen oxides, and in a plurality of second steps, the concentration of nitrogen oxides is set in the exhaust gas at which the desorption of nitrogen oxides by the catalytic converter takes place, wherein based on a stored and a released amount of nitrogen oxides via the plurality of first steps and second steps, the nitrogen oxide storage capacity of the catalytic converter is inferred. 
     
     
         15 . The method according to  claim 11 , wherein respective initial gradients of a chronological sequence of the concentration of nitrogen oxides in the exhaust gas are determined upstream of the catalytic converter and downstream of the catalytic converter during the at least one first step, wherein respective second gradients of a chronological sequence of the concentration of nitrogen oxides in the exhaust gas upstream of the catalytic converter and downstream of the catalytic converter are determined during the at least one second step, wherein based on the gradients the nitrogen oxide storage capacity of the catalytic converter is inferred. 
     
     
         16 . The method according to  claim 15 , wherein an average value is created from a multitude of totals of the first gradient and from a multitude of totals of the second gradient, wherein the nitrogen oxide storage capacity of the catalytic converter is inferred on a basis of the average value. 
     
     
         17 . The method according to  claim 11 , wherein the nitrogen oxide storage capacity of a passive nitrogen oxide absorber of a vehicle is determined. 
     
     
         18 . The method according to  claim 11 , wherein the nitrogen oxide storage capacity of an oxidation catalytic converter of a vehicle is determined. 
     
     
         19 . The method according to  claim 11 , wherein the nitrogen oxide storage capacity of a passively operated nitrogen oxide storage catalytic converter of a vehicle is determined. 
     
     
         20 . A method to determine a nitrogen oxide storage capacity of a catalytic converter of a vehicle with a sensor to measure a concentration of nitrogen oxides in an exhaust gas downstream of catalytic converter, comprising the steps of:
 in at least one first step, setting a concentration of nitrogen oxides in the exhaust gas at which the catalytic converter absorbs nitrogen oxides by a control device;   in at least one second step, setting a concentration of nitrogen oxides in the exhaust gas at which a desorption of nitrogen oxides by the catalytic converter takes place by the control device; and   determining the nitrogen oxide storage capacity of the catalytic converter by considering a behavior of the catalytic converter at least during the desorption of nitrogen oxides by the control device.