초록 ▼

A device for purifying the exhaust gas of an internal combustion engine is disclosed. The device includes a particulate filter arranged in the exhaust system, which carries a catalyst for absorbing and reducing NOx. The catalyst absorbs NOx when the air-fuel ratio in the surrounding atmosphere there

A device for purifying the exhaust gas of an internal combustion engine is disclosed. The device includes a particulate filter arranged in the exhaust system, which carries a catalyst for absorbing and reducing NOx. The catalyst absorbs NOx when the air-fuel ratio in the surrounding atmosphere thereof is lean and releases the absorbed NOx to purify NOx by reduction when the air-fuel ratio is stoichiometric or rich. The device further includes a catalytic apparatus for purifying NOx arranged in the exhaust system upstream of the particulate filter, which has an oxidation function.

대표청구항 ▼

The invention claimed is: 1. A device for purifying the exhaust gas of an internal combustion engine comprising: a particulate filter arranged in the exhaust system, wherein said particulate filter is a wall-flow particulate filter comprising a partition wall having pores, said partition wall carry

The invention claimed is: 1. A device for purifying the exhaust gas of an internal combustion engine comprising: a particulate filter arranged in the exhaust system, wherein said particulate filter is a wall-flow particulate filter comprising a partition wall having pores, said partition wall carrying a catalyst for absorbing and reducing NOx on the exhaust gas upstream side surface thereof, said catalyst absorbing NOx when the air-fuel ratio in the surrounding atmosphere thereof is lean and releasing the absorbed NOx when said air-fuel ratio is stoichiometric or rich; a catalytic apparatus for purifying NOx arranged in the exhaust system upstream of said particulate filter, which catalytic apparatus carries a catalyst absorbing NOx when the air-fuel ratio in the surrounding atmosphere thereof is lean and releasing the absorbed NOx when said air-fuel ratio is stoichiometric or rich; and control means for making the air-fuel ratio in said catalytic apparatus rich to release NOx from said catalyst of said catalytic apparatus to purify the released NOx by reduction, and making the air-fuel ratio in the particulate filter rich to release NOx from said catalyst of said particulate filter to purify the released NOx by reduction so that said catalyst of said particulate filter also releases active-oxygen to oxidize and remove the particulates trapped on said particulate filter without producing luminous flame. 2. A device for purifying the exhaust gas of an internal combustion engine comprising: a particulate filter arranged in the exhaust system, which carries a catalyst for absorbing and reducing NOx, said catalyst absorbing NOx when the air-fuel ratio in the surrounding atmosphere thereof is lean and releasing the absorbed NOx when said air-fuel ratio is stoichiometric or rich; a catalytic apparatus for purifying NOx arranged in the exhaust system upstream of said particulate filter, which catalytic apparatus carries a catalyst absorbing NOx when the air-fuel ratio in the surrounding atmosphere thereof is lean and releasing the absorbed NOx when said air-fuel ratio is stoichiometric or rich; control means for making the air-fuel ratio in said catalytic apparatus rich to release NOx from said catalyst of said catalytic apparatus to purify the released NOx by reduction, and making the air-fuel ratio in the particulate filter rich to release NOx from said catalyst of said particulate filter to purify the released NOx by reduction so that said catalyst of said particulate filter also releases active-oxygen to oxidize and remove the particulates trapped on said particulate filter without producing luminous flame; and bypassing means to make possible the exhaust gas bypass said particulate filter downstream said catalytic apparatus. 3. A device for purifying the exhaust gas of an internal combustion engine according to claim 2, wherein during the recovery process of the SOx pollution of said catalytic apparatus, said bypassing means makes the exhaust gas bypass said particulate filter. 4. A device for purifying the exhaust gas of an internal combustion engine according to claim 2, wherein immediately after the finishing of the recovery process of the SOx pollution of said catalytic apparatus, said bypassing means does not make the exhaust gas bypass said particulate filter and thus the exhaust gas passes through said particulate filter.