To provide a technique capable of providing high exhaust emission control efficiency in a wide operating state in an exhaust emission control system of an internal combustion engine having the plurality of groups of cylinders.
Exhaust gas passages from the groups of cylinders are branched into a plurality of branch passages, and a part 2a, 52a of the plurality of branched passages 2a, 2b, 52a, 52b is thermally insulated by suppressing the release of exhaust heat to the outside and the remaining 2b, 25b of the plurality of branched exhaust passages are not thermally insulated to properly mix hot exhaust gases provided by thermally insulating the exhaust passages and cold exhaust gases provided by not thermally insulating the exhaust passages. Consequently, the temperature of the exhaust gases introduced into the exhaust emission control devices 4, 54 can be controlled.
MIYASHITA SHIGEKI
NAKADA ISAMU
Hidemi Matsukura
Mayuko Wakuda
Kazunobu Sera
Tsutomu Toyama