PURPOSE: To correct a change of a combustion condition, caused by aged deterioration, so as to maintain optimum thermal efficiency by calculating the thermal efficiency from a cylinder pressure waveform, obtained by a cylinder pressure and a crank angle signal, and controlling a fuel supply amount to an engine, ignition timing and exhaust gas recirculating amount in accordance with a result of this calculation.
CONSTITUTION: In a cylinder pressure detecting means 5, a cylinder pressure waveform is obtained by amplifying a signal detected by a cylinder pressure sensor of an engine 1. A signal of a crank angle sensor is detected by a crank angle detecting means 6. These output signals are input to a control unit 10. In a cylinder pressure supervising means 11 in the unit 10, the cylinder pressure waveform in each cycle is obtained and input to a thermal efficiency calculating means 12. Thermal efficiency ηA is obtained and input to a corresponding region of a map, composed of an engine speed and a basic injection pulse width, to perform an averaging process. The calculated value ηA of thermal efficiency is compared with a reference value η0 of the map 13 by a comparing means 14, and the thermal efficiency can be improved by performing an EGR cut of an EGR rate map 18 and changing ignition timing of an ignition timing map 17 through a combustion control means 15 and a fuel injection amount of a fuel injection pulse width arithmetic means 16.
WASHINO SHOICHI
IZUMI AKIRA
