Method of operating an internal combustion engine in particular in a motor vehicle

Abstract

An internal combustion engine ( 1 ), in particular for a motor vehicle, is described; it is equipped with a catalytic converter ( 12 ) which may be exposed to nitrogen oxides. A lambda probe ( 13 ) is provided for measuring the oxygen concentration downstream from the catalytic converter ( 12 ). The nitrogen oxides supplied to the catalytic converter ( 12 ) are increased by a controller ( 18 ), and the conversion capacity of the catalytic converter ( 12 ) is concluded from the increase in oxygen concentration downstream from the catalytic converter ( 12 ).

What is claimed is:  
     
         1 . A method of operating an internal combustion engine ( 1 ), in particular in a motor vehicle, a catalytic converter ( 12 ) being exposed to nitrogen oxides, and the oxygen concentration (O2free) downstream from the catalytic converter ( 12 ) being measured, 
 wherein the nitrogen oxides supplied to the catalytic converter ( 12 ) are increased, and the conversion capacity of the catalytic converter ( 12 ) is concluded from the increase in the oxygen concentration (O2free) downstream from the catalytic converter ( 12 ).    
     
     
         2 . The method according to  claim 1 , 
 wherein the oxygen concentration (O2Exhaust) upstream from the catalytic converter ( 12 ) is kept constant.    
     
     
         3 . The method according to one of claims  1  or  2 , 
 wherein the lambda value upstream from the catalytic converter ( 12 ) is kept constant.  
 
     
     
         4 . The method according to  claim 2  or  3 , 
 wherein the measured oxygen concentration (O2free) downstream from the catalytic converter ( 12 ) represents the oxygen concentration (O2Cat) released by the catalytic converter ( 12 ) from the nitrogen oxides supplied.  
 
     
     
         5 . The method according to one of claims  1  through  4 , 
 wherein the concentration (O2Cat) is used as a measure of the conversion capacity of the catalytic converter ( 12 ).  
 
     
     
         6 . The method according to one of claims  1  through  5 , 
 wherein the increase in nitrogen oxides supplied to the catalytic converter ( 12 ) is achieved by detuning the ignition time and/or through other measures in the control and/or regulation of the internal combustion engine ( 1 ).  
 
     
     
         7 . A control element, in particular a flash memory, for a controller ( 18 ) of an internal combustion engine ( 1 ) in a motor vehicle in particular, a program being stored on it, capable of running on a computer, in particular a microprocessor, and suitable for execution of a method according to one of claims  1  through  6 .  
     
     
         8 . A controller ( 18 ) for an internal combustion engine ( 1 ) of a motor vehicle in particular, the engine ( 1 ) having a catalytic converter ( 12 ) which may be exposed to nitrogen oxides, and having a lambda probe ( 13 ) for measuring the oxygen concentration (O2free) downstream from the catalytic converter ( 12 ), 
 wherein the controller ( 18 ) is capable of increasing the nitrogen oxides supplied to the catalytic converter ( 12 ), and the controller ( 18 ) is capable of determining the conversion capacity of the catalytic converter ( 12 ) on the basis of the increase in oxygen concentration (O2free) downstream from the catalytic converter ( 12 ).    
     
     
         9 . An internal combustion engine ( 1 ) for a motor vehicle in particular, having a catalytic converter ( 12 ) which may be exposed to nitrogen oxides, and having a lambda probe ( 13 ) for measuring the oxygen concentration (O2free) downstream from the catalytic converter ( 12 ) and having a controller ( 18 ), wherein the controller ( 18 ) is capable of increasing the nitrogen oxides supplied to the catalytic converter ( 12 ) and of concluding the conversion capacity of the catalytic converter ( 12 ) on the basis of the increase in oxygen concentration (O2free) downstream from the catalytic converter ( 12 ).