Patent ID: 6155232
Filing Date: 2000-12-05
Classification: F02D

Abstract:
A method of control of an air-fuel ratio in an engine, comprising the steps of:setting a first crank angle range in a crank angle region from the end of a compression stroke to the beginning of an expansion stroke,detecting a first angular velocity of the crankshaft in the first crank angle range,setting a second crank angle range in a crank angle region in the middle of the expansion stroke a predetermined crank angle away from the first crank angle range,detecting a second angular velocity of the crankshaft in the second crank angle range,finding the output fluctuation of the cylinders based on the first angular velocity and the second angular velocity,judging whether the vehicle is driving over a rough road from the amplitude and cycle of fluctuation of the vehicle speed, andprohibiting the correction of the air-fuel ratio based on the output fluctuation when it is judged that the vehicle is driving over a rough road.