Patent attributes
A rotation speed calculation interval is set near a combustion top dead center of each cylinder of an engine. An interval rotation time necessary for a crankshaft to rotate through the rotation speed calculation interval is calculated as angular speed information of the crankshaft in the rotation speed calculation interval for each combustion stroke of the engine. Engine rotation speed is calculated based on the interval rotation time. The angular speed information of the crankshaft in the rotation speed calculation interval set near the combustion top dead center reflects a combustion state or generated torque. By calculating the engine rotation speed based on the angular speed information, the engine rotation speed highly correlated with the combustion state or the generated torque of the engine can be calculated.
