| 摘要 |
<p>PURPOSE:To obtain an air flow rate measuring apparatus which does not show the deterioration of the output characteristic even when dirt particles adhere to an air flow rate detecting element. CONSTITUTION:A heat generating resistance body 8 and a heat-sensitive resistance body 9 for temperature compensation which work as air flow rate detecting elements are provided in a sub air passage 3 arranged in a main air passage 2. A catching means 12 is set to catch dirt particles in the sub air passage 3, specifically, at the lower stream than the air flow rate detecting elements 8, 9. The catching means 12 is obtained, for example, by forming a step difference at a wall surface of the sub air passage or by installing a bridge-like obstacle in the passage. A catching face 12a is directed to the upstream, and an exfoliation eddy S is generated on the downstream side of the catching face 12a. Accordingly, the generation of the eddy is restricted as the adhering amount of the dirt particles to the catching face 12a is increased. The resistance when the air runs the sub air passage is changed by utilizing the adhering amount of the dirt particles to the catching face.</p> |
