| 摘要 |
PURPOSE:To enable fuel properties to be detected in s early stages by forcibly changing an air-fuel ratio until fluctuation of combustion pressure exceeds the specific value in the specific cylinder, and detecting fuel properties by detecting the air-fuel ratio in the limit of lean combustion or rich combustion. CONSTITUTION:In detecting of fuel properties (heavy or light) by a control unit 12, a specific one cylinder 1 for forcibly correcting the fuel injection amount (an air-fuel ratio) is discriminated while the amount is increased and corrected after starting, and deviation (fluctuation width) DELTAPi between a last integral value Pi in the integral section in the specific cylinder and a latest integral value Pi in the integral section is calculated. Next, the fluctuation width DELTAPi and the specific value corresponding the allowable limit of the fluctuation width DELTAPi are compared with each other. When the DELTAPi is less than the specific value, the processing for increasing and correcting the correction amount for increasing and correcting an after-starting increasing-correction factor by the specific value alpha until the DELTAPi exceeds the specific value is repeated, and the fuel properties are estimated according to an increasing-correction value set at that time. |
