Patent ID: 8141537

Claim:
A controlling device for an internal combustion engine comprising: an intake flow controlling valve to generate vortex flow of intake air in a combustion chamber of the internal combustion engine by opening and closing an intake passage arranged at an upstream side of the combustion chamber; an estimating portion to calculate an estimation value relative to an open degree of the valve based on a predetermined estimation formula, while the valve has an operation between a full close and a full open; and a ON-OFF sensor to output a signal, wherein the signal of the sensor is changed, when the valve has a predetermined open degree defined between the full close and the full open, the estimating portion determines that an actual open degree of the valve is smaller than the predetermined open degree, in a case where the signal of the ON-OFF sensor is not changed when the estimation value becomes equal to or larger than the predetermined open degree, and the estimating portion keeps the estimation value to be fixed, until the signal of the ON-OFF sensor is changed, while the actual open degree of the valve is determined to be smaller than the predetermined open degree.