 Image Number 13 for United States Patent #7011055.
A centric phase of an operating angle of an engine valve is detected on the basis of an interval between a reference rotational position of a crankshaft and a reference rotational position of a camshaft, and on the other hand, the centric phase is detected at a period shorter than a period between the reference rotational positions, and one of those detected results is selected on the basis of a predetermined regulation, and an opening characteristic of the engine valve is operated on the basis of the selected centric phase.
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