METHOD FOR DETERMINING AIR-FUEL RATIO IMBALANCE (EMBODIMENTS) Russian patent published in 2019 - IPC F02D41/00 

FIELD: machine building.

SUBSTANCE: invention relates to vehicle engine control systems. Result is achieved by determining presence or absence of errors in air-fuel ratio by deviation from expected air-fuel ratio during deceleration fuel shut off (DFSO) mode. For this purpose, one spark is sent to one selected cylinder once (once or several times in time of DFSO) in order to determine imbalance of air-fuel ratio for separate engine cylinder in comparison with expected deviation. Further, each of the engine cylinders is actuated in the same manner during the DFSO to track imbalance of all cylinders. At that, as the measurement version of the unbalance, after the air-fuel ratio of the maximally lean mixture is detected during the DFSO, the cylinder or group of cylinders is selected depending on the time of the spark supply, the cylinder position, or both factors, wherein a spark is supplied to the said cylinder or a group of cylinders, while the remaining cylinders remain in the disconnected state during the DFSO. Air-fuel ratio of said cylinder or group of cylinders is measured and compared with expected air-fuel ratio. If the difference between the measured and expected air-fuel ratio exceeds the threshold, the cylinder or group of cylinders has an unbalance of the air-fuel ratio.

EFFECT: technical result is tracking of imbalance of air-fuel ratio between engine cylinders during deceleration fuel shut off (DFSO) mode.

20 cl, 10 dwg