Method for metering a reagent into the exhaust gas flow of an internal combustion engine

Abstract

A method for metering a reagent into the exhaust gas flow of an internal combustion engine is provided, in which the reagent is guided in at least one component and in which a measure for the temperature of the component is recorded. The measure for the temperature is compared to a predefined temperature threshold value. A counter counts the number of times the threshold is exceeded. If the counter state exceeds a predefined count threshold value, a service signal is emitted. The temperature threshold value is fixed, for example, at the freezing temperature of the reagent. One embodiment provides that the counter counts an exceeding of the temperature threshold value only when the component is filled with the reagent.

1 - 10 . (canceled)  
   
   
       11 . A method for metering a reagent into an exhaust gas flow of an internal combustion engine, the method comprising: 
 guiding the reagent in at least one component;    recording a measure for a temperature of the component;    comparing the measure for the temperature to a predefined temperature threshold value;    counting a number of times the temperature threshold value is exceeded in a counter;    predefining a count threshold value for the number of times the temperature threshold value is exceeded; and    making available a service signal in response to an exceeding of the count threshold value.    
   
   
       12 . The method according to  claim 11 , wherein the temperature threshold value is equivalent to a freezing temperature of the reagent.  
   
   
       13 . The method according to  claim 12 , further comprising, after shutting down the internal combustion engine, during coasting, ascertaining whether the component is filled with the reagent.  
   
   
       14 . The method according to  claim 13 , wherein the counter is an ice counter, and the ice counter counts an exceeding of the temperature threshold value only when the component is filled with the frozen reagent.  
   
   
       15 . The method according to  claim 13 , wherein, during the ascertaining of whether the component is filled with the reagent, a compressed air signal is evaluated.  
   
   
       16 . The method according to  claim 13 , wherein, during the ascertaining of whether the component is filled with the reagent, an operation of an emergency stop switch is taken into consideration.  
   
   
       17 . The method according to  claim 11 , further comprising counting an exceeding of the temperature threshold value only at a start of the internal combustion engine.  
   
   
       18 . The method according to  claim 11 , further comprising obtaining the measure for the temperature of the component from a signal of at least one temperature sensor.  
   
   
       19 . The method according to  claim 18 , wherein the temperature sensor records the temperature of the component.  
   
   
       20 . The method according to  claim 18 , wherein the temperature sensor records an air temperature.