Patent ID: 7707823
Filing Date: 2010-05-04
Classification: F01N,F02D

Abstract:
1. An exhaust purification method for an internal combustion engine, comprising: a combustion purge control process for supplying fuel for reduction for a NOx catalyst arranged in an exhaust apparatus of the internal combustion engine by setting an amount of fuel supplied for the internal combustion engine in such a manner that an air/fuel ratio becomes rich; and an exhaust addition purge control process for adding fuel for reduction to a part of the exhaust apparatus of an upstream side of exhaust gas with respect to the NOx catalyst, wherein: the combustion purge control process and the exhaust addition purge control process are selectively performed in response to an operation state of the internal combustion engine; and the combustion purge control process is performed in the case where a NOx occlusion amount of the NOx catalyst is larger than or equal to a first threshold value, and the exhaust addition purge control process is performed in the case where the NOx occlusion amount of the NOx catalyst is larger than or equal to a second threshold value which is larger than the first threshold value.