| 摘要 |
PROBLEM TO BE SOLVED: To provide a combustion state detecting device for an internal combustion engine, for accurately estimating the actual quantity of heat in a cylinder due to combustion even when absolute pressure correction of a cylinder pressure which is detected by a cylinder pressure sensor is not correctly performed.SOLUTION: A combustion state detecting device for a reciprocating internal combustion engine 10 includes a cylinder pressure sensor 34 and a crank angle sensor 42. It uses a cylinder pressure P after absolute pressure correction for calculating data of a calculated heat quantity Q in crank angle synchronization, and calculates a heat quantity change amount &Dgr;Q as a finite difference between a first calculated heat quantity Qat a first crank angle &thetas;on the further advance side than TDC and a second calculated heat quantity Qat a second crank angle &thetas;symmetrical to the &thetas;with reference to the TDC. It estimates an actual heat quantity Qt on the basis of the heat quantity change amount &Dgr;Q which is calculated using a crank angle on the further advance side than a combustion start point as the first crank angle &thetas;and using a crank angle on the further retard side than a combustion end point as the second crank angle &thetas;. |
