Patent ID: 8267076
Filing Date: 2012-09-18
Classification: F02D

Abstract:
1. An engine control apparatus provided with a plurality of cylinders, comprising: means for performing feedback control of an air-fuel ratio based on a real air-fuel ratio of an exhaust manifold that communicates with each of the cylinders; means for judging that a difference between a target air-fuel ratio and the real air-fuel ratio is equal to or below a predetermined value during the air-fuel ratio feedback control; means for detecting a cylinder having a largest variation of angular acceleration of a crank shaft of the plurality of cylinders when the difference between the target air-fuel ratio and the real air-fuel ratio is judged to be equal to or below the predetermined value; means for correcting the air-fuel ratio of the cylinder having the largest variation of angular acceleration to a rich side or correcting the air-fuel ratio of a cylinder other than the cylinder having the largest variation of angular acceleration to a lean side; means for comparing angular acceleration of the cylinder having the largest variation of angular acceleration or an average value thereof with angular acceleration of the cylinder other than the cylinder having the largest variation of angular acceleration or an average value thereof, and judging, when angular acceleration of the cylinder having the largest variation of angular acceleration or an average value thereof is greater than angular acceleration of the cylinder other than the cylinder having the largest variation of angular acceleration or an average value thereof, that the amount of air of the cylinder having the largest variation of angular acceleration is greater than the amount of air of the cylinder other than the cylinder having the largest variation of angular acceleration; and means for judging, when angular acceleration of the cylinder having the largest variation of angular acceleration or an average value thereof is smaller than angular acceleration of the cylinder other than the cylinder having the largest variation of angular acceleration or an average value thereof, that the amount of fuel of the cylinder having the largest variation of angular acceleration is smaller than the amount of fuel of the cylinder other than the cylinder having the largest variation of angular acceleration; wherein the means for correcting the air-fuel ratio of the cylinder having the largest variation of angular acceleration to the rich side corrects the amount of fuel of the cylinder having the largest variation of angular acceleration so as to increase or corrects the amount of air so as to decrease; wherein the means for correcting the air-fuel ratio of the cylinder having the largest variation of angular acceleration to the rich side corrects the air-fuel ratio by fuel amount increasing correction and then comparing angular acceleration of the cylinder subjected to the fuel amount increasing correction or an average value thereof with angular acceleration of a cylinder other than the cylinder having the largest variation of angular acceleration or an average value thereof; and wherein the means for correcting the air-fuel ratio of the cylinder having the largest variation of angular acceleration to the rich side additionally or alternatively corrects the air-fuel ratio by air amount decreasing correction and then comparing angular acceleration of the cylinder subjected to the air amount decreasing correction or an average value thereof with angular acceleration of the cylinder other than the cylinder having the largest variation of angular acceleration or an average value thereof.