Patent ID: 8914218

Claim:
A four-stroke cycle internal combustion engine employing an odd number of cylinders, comprising: a crankangle sensor configured to output, responsively to rotation of a crankshaft, a first signal including a pulse train having pulses generated at each predetermined crankangle and also including a specific portion corresponding to a specified position in phase of a specified cylinder of the cylinders; a signal generating means for generating, responsively to the rotation of the crankshaft, a second signal related to an actual stroke of each of the cylinders and periodically oscillating with a period corresponding to the number of the cylinders in a manner so as to have an extreme near a top dead center position on compression stroke of each of the cylinders and have an extreme near a midpoint of the top dead center positions adjacent to each other; an integrating means for integrating the second signal for at least two intervals, which intervals are preset based on the specific portion, used as a reference, in a manner so as to include a ridge and a trough of the second signal such that the extremes are arranged substantially in centers of the respective intervals, thereby calculating an integrated value within each of the preset intervals; and a cylinder-identification means for making a cylinder-identification by comparing the integrated values.