Patent ID: 8170775

Claim:
A fuel injection device for an internal combustion engine, comprising: an air-fuel ratio sensor for detecting an air-fuel ratio of an exhaust gas; target air-fuel ratio setting means for setting a target air-fuel ratio in accordance with an operating state of the internal combustion engine; air-fuel ratio detecting means for detecting an actual air-fuel ratio based on a detection signal of the air-fuel ratio sensor; fuel correction value calculating means for calculating a correction value for a fuel injection quantity so that the actual air-fuel ratio becomes equal to the target air-fuel ratio; fuel switching detecting means for detecting that fuel switching has occurred; fuel property estimating means for setting a period, in which there is a possibility that a fuel property changes, as a property change period when the fuel switching is detected by the fuel switching detecting means to calculate a fuel property correction value corresponding to another correction value for the fuel injection quantity based on the correction value within the property change period; and property change judging means for judging whether or not a change in the correction value is due to the change in the fuel property in a case where the correction value becomes out of a predetermined range even though the property change period is not set, wherein the fuel property estimating means sets the property change period even when the property change judging means judges that the fuel property has changed.