Patent ID: 7640728

Claim:
An exhaust gas purification apparatus for an internal combustion engine including a plurality of independent exhaust passages provided one for each cylinder group, and a plurality of catalysts each having a NOx trapping ability and/or a PM trapping ability and being arranged in said exhaust passages, respectively, characterized by comprising: an upstream side communication passage connecting mutually portions of said exhaust passages at upstream of said catalysts; an upstream side switching valve opening and closing said upstream side communication passage; reducing agent addition valves being arranged in said exhaust passages between their connecting portions with said upstream side communication passage and said catalysts, respectively; a plurality of flow rate regulation valves being arranged at downstream of connecting portions of said exhaust passages with said upstream side communication passage, respectively; and a control section controlling said upstream side switching valve and said respective flow rate regulation valves in accordance with the states of said respective catalysts, wherein when the NOx trapping ability of one of said plurality of catalysts is regenerated, said control section opens said upstream side switching valve, decreases the degree of opening of one flow rate regulation valve in one of said exhaust passages in which said one catalyst is arranged, and supplies a reducing agent to said one catalyst from one reducing agent addition valve in said one exhaust passage in which said one catalyst is arranged.