| 摘要 |
PROBLEM TO BE SOLVED: To prevent deterioration of transient exhaust state caused in transition between the operation regions (H) and (D) in a combustion control device of a direct-injection type diesel engine in which fuel is early injected in a pre-mix combustion region (H) on low load side, the EGR rate is set to a first set value or higher to set a pre-mix combustion mode, and on the other hand, a diesel combustion mode is set in a diffusion combustion region (D) on high load side, and the EGR rate is set to a second set value or lower. SOLUTION: At the time of transition from one of the pre-mix combustion region (H) and the diffusion combustion region (D) of the engine 1 to the other, an opening of an EGR valve 35 is changed, and after the actual EGR rate EGR reaches a designated switching EGR rate (a designated EGR 1), the injection mode of fuel is switched. At the time, when the EGR rate EGR is within a designated range (SB5→SB13→SB15), follow-up injection is performed so that combustion starts substantially at the end of main combustion started near TDC (SB15, SB7). Thus, soot generated in main combustion is effectively re-burnt to remarkably reduce the concentration of soot in exhaust emission. COPYRIGHT: (C)2004,JPO
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