Patent ID: 9097193
Filing Date: 2015-08-04
Classification: F02D

Abstract:
1. An inter-cylinder air-fuel ratio variation abnormality detection apparatus for a multicylinder internal combustion engine having a plurality of cylinders connected to a common crank shaft and forming a plurality of banks, the apparatus comprising: an imbalance determination unit determining imbalance of an air-fuel ratio among the cylinders based on a difference between index values correlated with crank angular velocities detected in a set of opposite cylinders belonging to different banks and having crank angles different from one another by 360°; and an air-fuel ratio feedback processing unit carrying out an air-fuel ratio feedback process for controlling an amount of injected fuel for each of the banks so as to make the air-fuel ratio equal to a predetermined target air-fuel ratio, wherein the apparatus further comprises a correction unit correcting, before determining the air-fuel ratio imbalance, the difference between the index values in a direction of combustion improvement for opposite cylinders that are opposite to cylinders belonging to a bank identical to a bank of a cylinder with an index value deviating most from a standard value among all the cylinders and being other than the cylinder with the most deviating index value.