Flow meter having airflow sensor

摘要

A flow meter is formed with a passage for introducing and carrying air to measure and has a sensing part disposed in the passage for measuring a flow rate of the air. A contraction part is formed on an inner surface of the passage so that the contraction part faces the sensing part. The contraction part narrows the flow of the air flowing near the sensing part. A flat surface of the contraction part is formed in parallel with the surface of the sensing part and at least upstream of the sensing part. Thus, collision of particles against the sensing part and adhesion of contaminants to the sensing pert are inhibited. Meanwhile, the flow rate of the air is measured stably and accurately.