EXHAUST EMISSION CONTROL DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an exhaust emission control device capable of reducing NOx while suppressing the exhaust of PM even when the temperature of an exhaust purifying catalyst falls lower than active temperature due to the continuation of idle operation over a long period.

SOLUTION: An exhaust emission control device is provided with a bypass passage which is branched from an exhaust passage to bypass a catalyst and merged with the exhaust passage on the upper reach of a filter. When the temperature of catalyst is lower than a predetermined active lower limit temperature Ta under an idle operation state of an internal combustion engine (S10), an EGR valve is substantially fully opened and exhaust gas is passed through the bypass passage (S12, S14, S16).

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