Measurement of the pulsating air mass flow in the intake duct of an internal combustion engine

摘要

The invention relates to a thermal type flow rate measurement apparatus comprising a sub-passage having a detour passage and a hole just before a flow rate measuring part. A slit is formed downstream of a flow rate detecting element (3) located after the detour passage. The slit hole may be arranged between the flow rate detecting element (3) and the outlet port part (14), and may be opened between a wall surface side and a recess part (17). Thereby, it is possible to prevent the output value from falling in the negative side upon rise-up thereof.