To provide an exhaust emission control device for an internal combustion engine improving fuel economy and exhaust gas property by performing temperature rise control of an NOx catalyst for accelerating NOx desorption and purification by exhaust gas reduction control, effectively without loss in relation to exhaust gas reduction control.
The exhaust emission control device for the internal combustion engine carries out exhaust gas reduction control for controlling exhaust gas to a reducing atmosphere to desorb and purify NOx caught by the NOx catalyst 7 (Fig.2) and carries out temperature rise control for the temperature rise of the NOx catalyst 7 to accelerate NOx desorption and purification by exhaust gas reduction control (Fig.5). The device then acquires the caught amount QNOx of NOx caught by the NOx catalyst 7 (S1 in Fig.2 and Fig.3) and forbids temperature rise control when the acquired NOx caught amount QNOx is smaller than a threshold QHEATS (S35 in Fig.5).
ENDO MASATOSHI
ODAJIMA HIKARI
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