To exactly detect the top dead center of a piston in starting an engine.
This detection method for top dead center includes a step (S120) for calculating an angular speed of a time change in the displacement angle of a resolver provided on a motor generator cranking the engine; a step (S140) for calculating an angular acceleration of a time change of an angular speed; and a step (S190) for determining a position of an inflection point as the top dead center of the piston when a variance in the angular acceleration is larger than its threshold value A (Yes in S180). The inflection point (a minimum point) of the angular acceleration is determined as the compression top dead center in which the direction of a force applied onto the piston changes from a negative (compression) to a positive (expansion).
Toshio Morita
Takao Matsuyama
Tadashi Muto
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