Patent ID: 7204134

Claim:
An engine intake air flow meter for measurement of an engine intake air flow rate employing a device to measure a pressure difference between two points and a pressure at one point in an engine intake pipe and to calculate a mass flow rate of intake air based on the pressure values, comprising a device for measuring a pressure difference between two points in an intake pipe spaced apart lengthwise in said intake pipe, a device for measuring a pressure at a point that is either of said two points or a third point in said intake pipe different from said two points, a device for calculating integration of said pressure difference and double integration that means integration of said integration of said pressure difference, a device for detecting a moment when an air flow rate is a zero according to a time derivative of said pressure at a point and correcting both said integration and said double integration at said moment, and a device for calculating a mass flow rate by said integration and an amount of air by said double integration.