| 摘要 |
PURPOSE:To reduce the cost of a system and to mount it on even an engine in operation by detecting a start period of exhaustion from variation in in- cylinder pressure and finding a crank position on the basis of it. CONSTITUTION:A signal outputted from an in-cylinder sensor 2 is differentiated 4 to find the rate of variation in in-cylinder pressure, and the output result has two plus-side and minus-side peaks. The latter minus-side peak is generated on the basis of the start period of exhaustion as a start point and an exhaustion start period calculation device 5 detects it for >=2 turns of the engine. The elapsed time between those two peaks is measured by a frequency divider 6 to obtain a time T. When the top dead center (TDC) of the engine is 120 deg. before the exhaustion start period, the TDC is TX240/360sec after the point (A). At the same time, the elapsed time from the point (A), i.e. T/360sec is obtained as in-cylinder pressure data of every crank angle 1 deg.. Thus, the TDC and time of every crank angle are found and displayed 7 having the time information on a lateral axis and in-cylinder pressure on a longitudinal axis, thereby measuring variation in pressure to the crank angle.
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