Air-fuel ratio control device for an internal combustion engine

摘要

An air-to-fuel ratio control device for an internal combustion engine is disclosed, which comprises a pressure sensor for detecting the pressure P within a cylinder of the engine, and means for computing an actual value of the ratio (dP/d theta )max/Pmax, wherein (dP/d theta )max is the maximum rate of change in pressure P within the cylinder with respect to the crank angle theta and Pmax is the maximum pressure in the cylinder during a predetermined interval in a cycle of the cylinder. A target value of the ratio (dP/d theta )max/Pmax is obtained by converting the optimum air-to-fuel ratio corresponding to the operating condition of the engine, the conversion being effected by means of a relationship established between the values of the air-to-fuel ratio and those of the ratio (dP/d theta )max/Pmax. A control element controls the amount of injected fuel to reduce the deviation of the actual value of the ratio (dP/d theta )max/Pmax with respect to the target value thereof.