Catalyst passing component determining apparatus and exhaust purification apparatus for internal combustion engine

Abstract

The present invention comprises a selective reduction type NOx catalyst located in an exhaust passage and being capable of purifying NOx with ammonia, an oxidation catalyst located downstream of the selective reduction type NOx catalyst, an upstream sensor located between the selective reduction type NOx catalyst and the oxidation catalyst and having ability to detect both ammonia and NOx, a downstream sensor located downstream of the oxidation catalyst and having ability to detect both ammonia and NOx, and determining means for determining a component passing through the selective reduction type NOx catalyst, based upon a relation between output of the upstream sensor and output of the downstream sensor.

1 - 5 . (canceled) 
     
     
         6 . A catalyst passing component determining apparatus comprising:
 a selective reduction type NOx catalyst located in an exhaust passage and being capable of purifying NOx with ammonia;   an oxidation catalyst located downstream of the selective reduction type NOx catalyst;   an upstream sensor located between the selective reduction type NOx catalyst and the oxidation catalyst and having ability to detect both ammonia and NOx;   a downstream sensor located downstream of the oxidation catalyst and having ability to detect both ammonia and NOx; and   determining means for determining a component passing through the selective reduction type NOx catalyst, based upon a relation between output of the upstream sensor and output of the downstream sensor.   
     
     
         7 . A catalyst passing component determining apparatus according to  claim 6 , wherein the determining means determines that the NOx passes when the output of the upstream sensor and the output of the downstream sensor change in a similar manner from target outputs thereof. 
     
     
         8 . A catalyst passing component determining apparatus according to  claim 6 , wherein the determining means determines that the ammonia passes when an output change of the upstream sensor from the target output and an output change of the downstream sensor from the target output each have a different tendency. 
     
     
         9 . A catalyst passing component determining apparatus according to  claim 7 , wherein the determining means determines that the ammonia passes when an output change of the upstream sensor from the target output and an output change of the downstream sensor from the target output each have a different tendency. 
     
     
         10 . An exhaust purification apparatus for an internal combustion engine comprising:
 the catalyst passing component determining apparatus according to  claim 6 .   
     
     
         11 . An exhaust purification apparatus for an internal combustion engine according to  claim 10  comprising:
 reducing agent supplying means for supplying a reducing agent to the selective reduction type NOx catalyst, 
 wherein the reducing agent supplying means controls an addition reducing agent amount to the selective reduction type NOx catalyst based upon a determination result of the catalyst passing component determining apparatus.