Patent ID: 9587575
Date: 2017-03-07
CPC Classifications: F02D

Claim:
1. A cylinder-to-cylinder variation abnormality detecting device, comprising: a rotational fluctuation detecting module that detects a rotational fluctuation among cylinders of an engine having at least two or more cylinders; a rotational fluctuation type abnormality determining module that determines whether or not a cylinder-to-cylinder variation abnormality is occurring, based on the rotational fluctuation detected by the rotational fluctuation detecting module; an air-fuel ratio detecting module that detects an air-fuel ratio of an air-fuel mixture, from oxygen content and unburned fuel content in an exhaust gas from the engine; an air-fuel ratio fluctuation type abnormality determining module that determines whether or not the cylinder-to-cylinder variation abnormality is occurring, based on a fluctuation in the air-fuel ratio detected by the air-fuel ratio detecting module; a frequency component extracting module that extracts a particular frequency component corresponding to an engine combustion cycle, included in the rotational fluctuation detected by the rotational fluctuation detecting module; a frequency component type abnormality determining module that determines whether or not the cylinder-to-cylinder variation abnormality is occurring, based on the particular frequency component extracted by the frequency component extracting module; and a cylinder-to-cylinder variation abnormality determination finalizing module that finalizes a determination that the cylinder-to-cylinder variation abnormality is occurring, in the case where the rotational fluctuation type abnormality determining module determines that the cylinder-to-cylinder variation abnormality is there, and also the air-fuel ratio fluctuation type abnormality determining module determines that the cylinder-to-cylinder variation abnormality is there, wherein, in the case where the rotational fluctuation type abnormality determining module determines that the cylinder-to-cylinder variation abnormality is there but the air-fuel ratio fluctuation type abnormality determining module determines that there is no abnormality, if the frequency component type abnormality determining module determines that the cylinder-to-cylinder variation abnormality is there, the cylinder-to-cylinder variation abnormality determination finalizing module finalizes the determination that the cylinder-to-cylinder variation abnormality is occurring.