Patent ID: 6708486
Filing Date: 2004-03-23
Classification: B01D,F01N,F02B,F02D,F02M,Y02T,Y10S

Abstract:
An exhaust gas purification device of an internal combustion engine provided with a pair of particulate filters arranged in parallel in an engine exhaust passage, an exhaust flow switching means for switching almost all of the engine exhaust gas emitted from an engine to cause it to flow into one of the particulate filters, and a combustion device for feeding to a particulate filter an exhaust gas having a higher temperature elevation capability than a temperature elevation capability of an engine exhaust gas able to cause the temperature of the particulate filters to rise, an NOx catalyst able to absorb NOx in the exhaust gas when an air-fuel ratio of the inflowing exhaust gas is lean and to release the absorbed NOx when the air-fuel ratio of the inflowing exhaust gas becomes rich so as to enable the NOx to be reduced and purified by hydrocarbons in the exhaust gas and an oxidizing substance able to continuously oxidize and remove particulate being carried in the particulate filters, said NOx catalyst being able to release and reduce NOx when its temperature is in an NOx reduction temperature range, and said oxidizing substance being able to continuously oxidize and remove almost all inflowing particulate when the temperature of said oxidizing substance is higher than a particulate continuous oxidation temperature, said exhaust gas purification device of an internal combustion engine characterized by being provided with a reduction judging means for judging if the NOx absorbed in the NOx catalyst should be reduced, suppressing by said exhaust flow switching means the inflow of engine exhaust gas to the one of the particulate filters carrying the NOx catalyst for which it is judged the NOx absorbed in the NOx catalyst should be reduced when it is judged by said reduction judging means that the NOx absorbed in the NC should be reduced, and feeding rich air-fuel ratio exhaust gas to said particulate filter from a combustion device so that the temperature of said particulate filter is maintained higher the particulate continuous oxidation temperature in a NOx reduction temperature range.