| 摘要 |
An engine (1) in which an ECU (18) is provided with: a catalyst temperature-increasing means (C5) that increases the temperature of a lean NOx trap (LNT) catalyst (16) by controlling an injector (15) so as to perform multi-stage injection with a temperature increase timing calculated using timing estimation parameters including a temperature parameter detected by a catalyst temperature-detecting means (C1), a NOx concentration parameter detected by a NOx concentration-detecting means (C2), and an exhaust gas flow rate parameter detected by an exhaust gas flow rate-detection means (C3); and a reduction-promoting means (C7) that promotes the reduction of NOx by the LNT catalyst (16) with a reduction timing calculated using re-detected timing estimation parameters after the temperature of the LNT catalyst (16) has been increased by the catalyst temperature-increasing means (C5). Consequently, it is possible to calculate an effective reduction timing that imparts a NOx-eliminating effect and does not decrease fuel economy, and to perform NOx elimination. |
