Procedure for operating an exhaust gas treatment device and the device for implementing the procedure

Abstract

A procedure for operating an exhaust gas treatment device arranged in the exhaust gas area of a combustion engine, which requires for the catalytically supported conversion of the NOx emission of the combustion engine a reagent, whose dosage is determined by a dosage signal depending on a NOx actual value that is contained in the exhaust gas treatment device and that is measured by a NOx sensor, which is contained in the exhaust gas treatment device downstream after a catalyzer, as well as a device for implementing the procedure is suggested. The dosage singal is influenced by a correcting signal depending on a measure for the operating time of the exhaust gas treatment device in the sense of an increase of the dosage of the reagent. The strategy according to the invention allows the condsideration of a long-term drift of the NOx emissions of the combustion engine and/or of long-term drifts of individual drifts of the exhaust gas treatment device and ensures a preset minimum NOx conversion rate for the entire operating time of the exhaust gas treatment device.

1 . Procedure for operating an exhaust gas treatment device ( 14 ,  16 ,  18 ) arranged in the exhaust gas area ( 12 ) of a combustion engine ( 10 ), which requires for the catalytically supported conversion of the NOx emissions (NOx_vK) of the combustion engine ( 10 ) a reagent, whose dosage is determined by a dosage signal (s_D) depending on a NOx actual value (NOx_Mes) that is contained in the exhaust gas treatment device ( 14 ,  16 ,  18 ) and that is measured by a NOx sensor ( 18 ), which is contained in the exhaust gas treatment device ( 14 ,  16 ,  18 ) downstream after a catalyzer ( 16 ), is thereby characterized, in that the dosage signal (s_D) is influenced by a correcting signal (k_Sol) depending on a measure (h, km) for the operating time of the exhaust gas treatment device ( 14 ,  16 ,  18 ) in the sense of an increase of the dosage of the reagent. 
   
   
       2 . Procedure according to  claim 1  is thereby characterized, in that the dosage signal (s_D) is pre-controlled and regulated. 
   
   
       3 . Procedure according to  claim 2  is thereby characterized, in that the dosage signal (s_D) is pre-controlled with the aid of a calculated reagent filling-level actual level (Fuel_Sim) in the catalyzer ( 16 ). 
   
   
       4 . Procedure according to  claim 3  is thereby characterized, in that the calculated reagent filling-level actual value (Fuel_Sim) is calculated with the aid of a catalyzer model ( 32 ), which considers at least the catalyzer temperature (te_Kat) as well as a measure for the NOx emissions (NOx_vK) of the combustion engine ( 10 ). 
   
   
       5 . Procedure according to  claim 3  is thereby characterized, in that the difference (d) between the NOx actual value (NOx_Mes) and a NOx nominal value (NOx_Sol) is regulated. 
   
   
       6 . Procedure according to  claim 5  is thereby characterized, in that the difference (d) influences the calculated reagent filling-level actual value (Fuel_Sim). 
   
   
       7 . Procedure according to  claim 2  or  5  is thereby characterized, in that a short-term adaptation is provided, which intervenes the catalyzer model ( 32 ) at the calculation of the reagent filling-level actual value (Fuel_Sim) in the catalyzer ( 16 ) with a short-term adaptation signal (Adapt_K_ti). 
   
   
       8 . Procedure according to  claim 2  or  5  is thereby characterized, in that a long-term adaptation is provided, which corrects a correcting variable (s) to a dosage signal (s_D) with a long-term adaptation signal (Adapt_L_ti). 
   
   
       9 . Procedure according to  claim 5  is thereby characterized, in that the correcting signal (k_Sol) corrects the NOx nominal value (NOx_Sol). 
   
   
       10 . Procedure according to  claim 3  is thereby characterized, in that the correcting signal (k_Sol) corrects a reagent filling-level nominal value (Fuel_Sol). 
   
   
       11 . Procedure according to  claim 1  is thereby characterized, in that the covered distance (km) of a motor vehicle is used as a measure (h, km) for the operating time of the exhaust gas treatment device ( 14 ,  16 ,  18 ), in which the combustion engine ( 10 ) is used as power train. 
   
   
       12 . Procedure according to  claim 1  is thereby characterized, in that the correcting signal (k_Sol) starts with the value 1 and increases up to the value 1.2. 
   
   
       13 . Device for operating an exhaust gas treatment device ( 14 ,  16 ,  18 ) arranged in the exhaust gas area ( 12 ) of a combustion engine ( 10 ), which requires for the catalytically supported conversion of the NOx emissions (NOx_vK) of the combustion engine ( 10 ) a reagent, whose dosage is determined by a dosage signal (s_D) depending on a NOx actual value (NOx_Mes) that is contained in the exhaust gas treatment device ( 14 ,  16 ,  18 ) and that is measured by a NOx sensor ( 18 ), which is contained in the exhaust gas treatment device ( 14 ,  16 ,  18 ) downstream after a catalyzer ( 16 ), is thereby characterized, in that at least one customized controller ( 20 ) for the implementation of the procedure according to the claims in  1  to  12  is provided. 
   
   
       14 . Control unit program, which implements all steps of a procedure according to one of the claims in  1  to  12 , if the program runs in a controller ( 20 ). 
   
   
       15 . Control unit program with a program code, which is saved on a machine readable medium, for the implementation of the procedure according to one of the claims in  1  to  12 , if the program runs in a controller ( 20 ).