Abstract: An air flow rate measuring device for an internal combustion engine is disclosed. The air flow rate measuring device has a casing provided downstream from an air cleaner element for purifying intake air to the internal combustion engine, a duct connected fluidly to and downstream from the casing, and an air flow meter provided in said duct, for measuring an air flow rate taken into the internal combustion engine. A cross-sectional area of a connection portion between the casing and the duct, taken perpendicularly to the direction of air flow is the minimum cross-sectional area in the duct.

Abstract: Disclosed is an air flow rate measurement apparatus comprising a heating resistor and a temperature sensing resistor for detecting an intake-air flow rate to be sucked into an internal combustion engine, and a circuit module for outputting an electric signal corresponding to said intake air flow rate, said module being electrically connected to said heating resistor and said temperature sensing resistor. The apparatus is featured in that said heating resistor and said temperature sensing resistor are inserted together with an element for measuring an intake air temperature through an opening formed in the wall of an air passage so that said three elements are located in said air passage and the module is fixed to the air passage. The apparatus is of low cost and small sized.