Patent ID: 8805609
Filing Date: 2014-08-12
Classification: G01M

Abstract:
1. An apparatus for detecting an abnormal air-fuel ratio variation, comprising: an abnormality detecting unit that detects an abnormal variation in air-fuel ratio among a plurality of cylinders of an internal combustion engine on the basis of a fluctuation in a predetermined output of the internal combustion engine, the internal combustion engine having a plurality of fuel injection valves for each of the plurality of cylinders; and a setting unit that sets an abnormality determination threshold that determines whether the predetermined output has an abnormality on the basis of a rotational speed of the internal combustion engine and a load of the internal combustion engine, wherein the abnormality detecting unit detects an abnormal variation in each of the plurality of fuel injection valves on the basis of an injection ratio between the plurality of fuel injection valves, and the predetermined output before the injection ratio is changed and the predetermined output after the injection ratio is changed, and wherein the setting unit corrects the abnormality determination threshold on the basis of the injection ratio.