Patent ID: 6282485
Filing Date: 2001-08-28
Classification: F02D,G01M

Abstract:
An air/fuel ratio control method for controlling an air/fuel ratio injected into a cylinder of an internal combustion engine having a manifold and an air flow sensor couple to the manifold, said method comprising the steps of:measuring a quantity of air entering the manifold based on the air flow sensor, with said measuring step executed at a first sample rate related to engine cycles;measuring an engine speed of the engine at a second sample rate independent of said engine cycles;calculating a first filter parameter at said second sample rate, with said first filter parameter independent of ambient conditions and with said first filter parameter based on a manifold volume, a number of cylinders, a displacement volume, a stored slope of a graph between manifold pressure and air quantity entering any one of the cylinder, and an engine speed;calculating a second filter parameter as one minus said first filter parameter at said second sample rate;estimating an air quantity entering the cylinder based on said measured air quantity entering the manifold, said first filter parameter, and said second filter parameter at said first sample rate; andcalculating a fuel injection quantity based on said air quantity entering the cylinder and a desired air/fuel ratio.