| 摘要 |
PURPOSE:To have air-to-fuel ratio control with good performance at all times by changing the ratio of the mixture in the resting side cylinders alternately between rich and lean, during operation of the resting side and working side cylinders, while the working side cylinders are being operated with a mixture of theoretical air-to-fuel ratio, and thereby determining the correction factor. CONSTITUTION:This internal-combustion engine is designed to make partial cylindrical operation in such an arrangement that a suction shut-off valve 29 in a communication pipe 28 in communication with No.1 group of cylinders A is closed during low load operation and, at the same time, the fuel injection valves 17a in divergent pipes 13a are stopped. Here, during all cylindrical operation, the air-to-fuel ratio of the mixture for No.2 group of cylinders B is for a certain prefixed period maintained at a theoretical value in accordance with the output from an oxygen density sensor 21a installed at the exhaust mainfold 15 on the working side. With this condition held, the air-to-fuel ratio of the mixture for the group A is changed to the rich and lean sides alternately until another oxygen density sensor 21b in the downstream of a three- dimentional catalyst converter 20 emits a rich or lean signal, and the injected fuel correction factor for the group A is determined. |
