Patent ID: 8701474

Claim:
An air flow measuring device that is adapted to be disposed in an intake passage through which intake air drawn into an internal combustion engine flows and that is configured to take in a part of a mainstream of intake air and to produce an electrical signal in accordance with a flow rate of intake air, the device comprising: a housing that defines a bypass flow passage through which the taken-in intake air passes and which includes a sensor passage having an outlet that opens into the intake passage toward a downstream side of the mainstream; a sensor that is accommodated in the sensor passage to produce the electrical signal as a result of heat transfer between the taken-in intake air and the sensor; and a projection portion that is provided on an outer wall of the housing on a downstream side of the outlet in the mainstream and extends outward of the housing, wherein a projection portion projected region and an outlet projected region, which are formed respectively by projecting the projection portion and the outlet perpendicularly onto a projection plane that is perpendicular to a direction of the mainstream, overlap with each other.