| 摘要 |
PROBLEM TO BE SOLVED: To properly adjust an opening of an EGR valve by using frequency analysis to bring an actual EGR rate close to a target EGR rate.SOLUTION: By using a frequency analysis, exciting force is calculated from an output signal of an in-cylinder pressure sensor 14 for each frequency. A value obtained by subtracting a target resonance primary frequency determined according to a target EGR rate from a resonance primary frequency at which the calculated exciting frequency becomes a peak is set as a first difference, a value obtained by subtracting target exciting force determined according to the target resonance primary frequency from exciting force at the resonance primary frequency is set as a second difference, and a value obtained by subtracting target low frequency range exciting force determined according to the target EGR rate with respect to a low frequency, from low frequency range exciting force at the low frequency that is lower in frequency than the resonance primary frequency, is set as a third difference. When the first difference is a positive value, the second difference is a negative value and the third difference is a negative value, the opening of an EGR valve is set larger than the present opening. When the first difference is a negative value, the second difference is a positive value and the third difference is a positive value, the opening of the EGR valve is set smaller than the present opening.SELECTED DRAWING: Figure 3 |
