| 摘要 |
<P>PROBLEM TO BE SOLVED: To efficiently perform NOx-reduction purification treatment of a NOx-occlusion reduction catalyst and a filter-regeneration treatment of a particulate filter at the same timing. <P>SOLUTION: From the upstream in the engine exhaust-gas passage in the exhaust emission purifier of an internal-combustion engine, a first fuel-addition valve 16, a NOx-occlusion reduction catalyst 13, a second fuel-addition valve 17, and the particulate filter are provided in this order. When an integrated value of fuel consumption has reached a specified value, it is determined that a NOx-reduction purification treatment is conducted, and NOx-reduction purification treatment control is exerted to perform NOx-reduction purification treatment. When the filter regeneration treatment and NOx-reduction purification treatment are being exerted, fuel-addition from the second fuel-addition valve is temporarily suspended; in the case where the filter regeneration treatment is being exerted, and NO<SB>x</SB>-reduction purification treatment is not being exerted, when a temperature in the exhaust-gas passage near the second fuel-addition valve is lowered more than a specified temperature, while holding the air-fuel ratio of exhaust gas lean, fuel is added from the first fuel-addition valve to raise temperature in the exhaust-gas passage around the second fuel-addition valve due to reaction heat of oxidation of the added fuel. <P>COPYRIGHT: (C)2010,JPO&INPIT |
