Method and device for diagnosing an error in an exhaust gas recirculation system

Abstract

In a method for determining a faulty exhaust gas recirculation line in an exhaust gas recirculation system of an internal combustion engine having multiple exhaust gas recirculation lines, a quantity of gas indicated by a specified exhaust gas recirculation rate is provided proportionately via the exhaust gas recirculation lines in accordance with an exhaust gas recirculation apportioning ratio, and the method further includes: testing in order to recognize an error in the exhaust gas recirculation system; when the error is recognized, performing a modification of the exhaust gas recirculation apportioning ratio and renewed testing of the exhaust gas recirculation system; and determination of the faulty exhaust gas recirculation line as a function of a result of the renewed testing.

What is claimed is: 
     
         1 . A method for determining a faulty exhaust gas recirculation line in an exhaust gas recirculation system of an internal combustion engine having a plurality of exhaust gas recirculation lines, wherein a quantity of gas indicated by a specified exhaust gas recirculation rate is provided proportionately via the exhaust gas recirculation line in accordance with an exhaust gas recirculation apportioning ratio, the method comprising:
 testing the exhaust gas recirculation system in order to recognize an error in the exhaust gas recirculation system;   when the error is recognized, performing (i) a modification of the exhaust gas recirculation apportioning ratio and (ii) a renewed testing of the exhaust gas recirculation system; and   determining a faulty exhaust gas recirculation line as a function of a result of the renewed testing of the exhaust gas recirculation system.   
     
     
         2 . The method as recited in  claim 1 , wherein, when the error is recognized, the exhaust gas recirculation apportioning ratio is modified in such a way that the quantity of exhaust gas to be recirculated is recirculated completely through only one of the exhaust gas recirculation lines. 
     
     
         3 . The method as recited in  claim 1 , wherein, when the error is recognized, the quantity of recirculated exhaust gas through one of the exhaust gas recirculation lines is maintained while the recirculation of exhaust gas through the remaining exhaust gas recirculation lines is stopped. 
     
     
         4 . The method as recited in  claim 3 , wherein a target air quantity is adapted in accordance with the maintained quantity of the exhaust gas recirculated through the one of the exhaust gas recirculation lines in order to maintain the exhaust gas recirculation rate. 
     
     
         5 . The method as recited in  claim 2 , wherein the exhaust gas recirculation line through which exhaust gas is exclusively recirculated after the error is recognized is selected as a function of the exhaust gas recirculation apportioning ratio existing before the recognition of the error. 
     
     
         6 . The method as recited in  claim 5 , wherein the selection of the exhaust gas recirculation line through which exhaust gas is exclusively recirculated is carried out as a function of a result of at least one threshold value comparison with at least one threshold value. 
     
     
         7 . The method as recited in  claim 6 , wherein the at least one threshold value is one of fixed or selected as a function of an operating point of the internal combustion engine. 
     
     
         8 . The method as recited in  claim 6 , wherein two threshold values are provided in order to define a range of the exhaust gas recirculation apportioning ratio in which the quantity of exhaust gas to be recirculated is provided through a plurality of exhaust gas recirculation lines after the recognition of the error. 
     
     
         9 . The method as recited in  claim 2 , wherein the testing of the exhaust gas recirculation system is carried out in order to recognize a flow error of the exhaust gas recirculation system. 
     
     
         10 . A device for determining a faulty exhaust gas recirculation line in an exhaust gas recirculation system of an internal combustion engine having a plurality of exhaust gas recirculation lines, wherein a quantity of gas indicated by a specified exhaust gas recirculation rate is provided proportionately via the exhaust gas recirculation line in accordance with an exhaust gas recirculation apportioning ratio, the device comprising:
 means for testing the exhaust gas recirculation system in order to recognize an error in the exhaust gas recirculation system;   means for performing, when the error is recognized, the following: (i) a modification of the exhaust gas recirculation apportioning ratio and (ii) a renewed testing of the exhaust gas recirculation system; and   means for determining a faulty exhaust gas recirculation line as a function of a result of the renewed testing of the exhaust gas recirculation system.   
     
     
         11 . A non-transitory computer-readable data storage medium storing a computer program having program codes which, when executed on a computer, performs a method for determining a faulty exhaust gas recirculation line in an exhaust gas recirculation system of an internal combustion engine having a plurality of exhaust gas recirculation lines, wherein a quantity of gas indicated by a specified exhaust gas recirculation rate is provided proportionately via the exhaust gas recirculation line in accordance with an exhaust gas recirculation apportioning ratio, the method comprising:
 testing the exhaust gas recirculation system in order to recognize an error in the exhaust gas recirculation system;   when the error is recognized, performing (i) a modification of the exhaust gas recirculation apportioning ratio and (ii) a renewed testing of the exhaust gas recirculation system; and   determining a faulty exhaust gas recirculation line as a function of a result of the renewed testing of the exhaust gas recirculation system.