To provide a practical combustion state detecting device for an internal combustion engine capable of judging misfire with accuracy even in a low load area or the like and usable being mounted on an automobile.
Cylinder pressure signals of the respective cylinders of an internal combustion engine detected by a plurality of cylinder pressure detecting means 10A, 10B, 10C, 10D are superposed by a signal superposing means 20. On the basis of the superposed cylinder pressure signals, a signal detecting means 30 computes a misfire judgment index, and a misfire judging means 40 judges a misfire state using the misfire judgment index and a misfire judgment level. With the use of the superposed cylinder pressure signals, a notable change in the symmetry of signal waveform across TDC can be obtained according to the presence of misfire, so that misfire judgment can be positively made in the whole combustion area of the engine.
KURIHARA NOBUO
KODAMA ATSUNORI
SAKAGUCHI TATSUNORI
FUMINO TAKAYUKI
WATANABE SHIZUHISA
