| 摘要 |
<p>PROBLEM TO BE SOLVED: To enable air flow rate measurement with high precision by a method wherein a position and a size of an inlet opening face and an outlet conflux part of a sub-air passage and a protrusion shape of an upstream of an outlet conflux part are optimized. SOLUTION: On both sides of a bridge body 2 on an upstream side of an outlet conflux part of a sub-air passage 4, a protrusion 1 is formed. As a flow velocity of an upstream of an outlet of the sub-air passage is increased by the protrusion 1, an outlet part of the sub-air passage 4 acts so that an air flow rate of the sub-air passage is increased. Accordingly, with respect to a drift having a mountain-like flow velocity distribution in an air flowing into an air flow rate measuring device, a flow velocity at near a wall face of a main air passage 5 is slow in a mountain-like flow velocity distribution compared with the case of a uniform flow. Therefore, since separation is small and a pressure depression at a sub-air passage outlet is smaller than the uniform flow, an air flow of the sub-air passage 4 acts to a decreasing direction. Therefore, a sub-air passage inlet 4a has a shape which takes in a flow containing a center of the main air passage 5 and an output increase of the air flow rate measuring device caused by the shape is made possible to be reduced.</p> |
