JPS6473147A - Air-fuel ratio control device for engine - Google Patents

Abstract

PURPOSE:To improve warming up performance, by a method wherein, in a device which performs air-fuel ratio feedback control and feed forward control responding a running state by means of a linear type O2 sensor, an air-fuel ratio is controlled so that an average effective pressure shown in Fig. produces a reference pressure value. CONSTITUTION:Detecting values from a key switch 1d, a heat ray type airflow meter 4, a throttle sensor 9, a linear output type O2 sensor 10, an in-cylinder pressure sensor 11, a crank angle sensor 14, and a water temperature sensor 15 are inputted to a control means 16 to control and compute the opening time of a fuel injection valve 7. When it is decided based on a cooling water temperature that an engine is in a warming up mode, the control means 16 compares an average effective pressure shown in Fig, calculated from detecting values from the in-cylinder pressure sensor 11 and the crank angle sensor 14, with a reference pressure value. When the average effective pressure exceeds the reference pressure value, an air-fuel ratio is rarefied, and when it is below the reference pressure value, the air-fuel ratio is enriched to feedback-control the average effective pressure in Fig, to the reference pressure value.