Diagnostic method for a reagent material to be introduced into an exhaust gas region of an internal combustion engine and device for performing the method

Abstract

The invention relates to a diagnostic method for a reagent to be introduced into an exhaust gas region of an internal combustion engine, or a precursor of the reagent, which is required to convert at least one exhaust gas component in a catalytic converter, and to a device for performing the method. A change in the load of the internal combustion engine is first determined relative to time. If a load change threshold is exceeded, a first release signal is provided. The relative reagent material fill level in the catalytic converter is further determined. If a relative fill level threshold value is exceeded, a second release signal is provided. The reagent material slack occurring downstream of the catalytic converter is compared to a reagent material slack threshold value. If the first and second release signals are present and the reagent material slack threshold value is exceeded, the reagent material is considered to be of sufficient quality.

1 - 10 . (canceled) 
     
     
         11 . A method of introducing a reagent, or a precursor of the reagent, into an exhaust gas region of an internal combustion engine to convert at least one exhaust gas component in a catalytic converter, the method comprising:
 determining a change in a load of the internal combustion engine with respect to time, wherein a first release signal is provided if a load change threshold is exceeded;   determining a relative reagent fill level in the catalytic converter, wherein a second release signal is provided if a relative fill level threshold value is exceeded; and   comparing a measured reagent material slack occurring downstream of the catalytic converter to a reagent material slack threshold value, wherein the reagent is considered to be of sufficient quality if the first and second release signals are provided and the measured reagent material slack exceeds the reagent material slack threshold value.   
     
     
         12 . A method according to  claim 11 , further comprising creating, upon provision of the first and the second release signal, an average value of the reagent material slack threshold value based on the number of times the measured reagent material slack exceeds the reagent material slack threshold value and number of times the measured reagent material slack does not exceed the reagent material slack threshold value, wherein the reagent is assigned with a sufficient quality if the average value exceeds an average threshold value. 
     
     
         13 . A method according to  claim 11 , further comprising postponing the comparing of the measured reagent material slack occurring downstream of the catalytic converter by a delay time calculated after the last of the first and second release signals is provided. 
     
     
         14 . A control unit configured to implement, a method of introducing a reagent, or a precursor of the reagent, into an exhaust gas region of an internal combustion engine to convert at least one exhaust gas component in a catalytic converter, the method comprising: determining a change in a load of the internal combustion engine with respect to time, wherein a first release signal is provided if a load change threshold is exceeded; determining a relative reagent fill level in the catalytic converter, wherein a second release signal is provided if a relative fill level threshold value is exceeded; and comparing a measured reagent material slack occurring downstream of the catalytic converter to a reagent material slack threshold value, wherein the reagent is considered to be of sufficient quality if the first and second release signals are provided and the measured reagent material slack exceeds the reagent material slack threshold value. 
     
     
         15 . The control unit of  claim 14 , wherein the control unit comprises:
 a load change detection for determining a change of a load of the combustion engine with respect to time;   a reagent filling level detection for determining the relative reagent filling level;   a filling level comparator for comparing the relative reagent filling level in the catalytic converter with a relative filling level threshold value; and   a reagent material slack comparator for comparing a reagent material slack with the reagent material slack threshold value.   
     
     
         16 . The control unit of  claim 14 , wherein a NOx-sensor is further provided as an exhaust gas sensor that has a cross sensitivity towards the reagent. 
     
     
         17 . The control unit of  claim 14 , wherein a NH3-sensor is further provided and used as an exhaust gas sensor. 
     
     
         18 . The control unit of  claim 14 , wherein a urea/water solution is provided as the reagent. 
     
     
         19 . A control unit program that executes, if the program runs on a control unit, the steps of a method of introducing a reagent, or a precursor of the reagent, into an exhaust gas region of an internal combustion engine to convert at least one exhaust gas component in a catalytic converter, the method comprising: determining a change in a load of the internal combustion engine with respect to time, wherein a first release signal is provided if a load change threshold is exceeded; determining a relative reagent fill level in the catalytic converter, wherein a second release signal is provided if a relative fill level threshold value is exceeded; and comparing a measured reagent material slack occurring downstream of the catalytic converter to a reagent material slack threshold value, wherein the reagent is considered to be of sufficient quality if the first and second release signals are provided and the measured reagent material slack exceeds the reagent material slack threshold value, and further comprising creating, upon provision of the first and the second release signal, an average value of the reagent material slack threshold value based on the number of times the measured reagent material slack exceeds the reagent material slack threshold value and number of times the measured reagent material slack does not exceed the reagent material slack threshold value, wherein the reagent is assigned with a sufficient quality if the average value exceeds an average threshold value, and further comprising postponing the comparing of the measured reagent material slack occurring downstream of the catalytic converter by a delay time calculated after the last of the first and second release signals is provided. 
     
     
         20 . A control unit program product with a program code that is stored on a machine readable device to implement, if executed in a control unit, a method of introducing a reagent, or a precursor of the reagent, into an exhaust gas region of an internal combustion engine to convert at least one exhaust gas component in a catalytic converter, the method comprising: determining a change in a load of the internal combustion engine with respect to time, wherein a first release signal is provided if a load change threshold is exceeded; determining a relative reagent fill level in the catalytic converter, wherein a second release signal is provided if a relative fill level threshold value is exceeded; and comparing a measured reagent material slack occurring downstream of the catalytic converter to a reagent material slack threshold value, wherein the reagent is considered to be of sufficient quality if the first and second release signals are provided and the measured reagent material slack exceeds the reagent material slack threshold value, and further comprising creating, upon provision of the first and the second release signal, an average value of the reagent material slack threshold value based on the number of times the measured reagent material slack exceeds the reagent material slack threshold value and number of times the measured reagent material slack does not exceed the reagent material slack threshold value, wherein the reagent is assigned with a sufficient quality if the average value exceeds an average threshold value, and further comprising postponing the comparing of the measured reagent material slack occurring downstream of the catalytic converter by a delay time calculated after the last of the first and second release signals is provided.