Four-stroke cycle internal combustion engine and method of identifying cylinder of four-stroke cycle internal combustion engine

A cylinder-identification method of a four-stroke cycle internal combustion engine employing an odd number of cylinders and configured to make a cylinder-identification based on a first signal including a pulse train having pulses generated at each predetermined crankangle and also including a specific portion at each 360° crankangle, and a second signal periodically oscillating according to the number of the cylinders, comprising:

• generating, responsively to rotation of a crankshaft, the 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;
• calculating an integrated value within each of 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;
• and
• identifying a position in phase of the specific portion during each cycle of 720 degrees of crankangle by comparing the integrated values.

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 generator 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 integrator 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 arc arranged substantially in centers of the respective intervals, thereby calculating an integrated value within each of the preset intervals;
• and
• a cylinder-identification circuit for making a cylinder-identification by comparing the integrated values.