| 摘要 |
<p>An airflow meter for measuring an airflow amount comprises an air duct (11), a bypass passage (18) provided in said duct (11) and a flow amount measuring element (29, 30) provided within said bypass passage (18) used for flowing in part of air flowing through said air duct (11). The bypass passage (18) is formed as an inverted U-shape passage in which two adjoining parallel passages (18a, 18c) are linked by a turning section (18b), wherein one passage (18a) is disposed at an upstream side and the other passage (18c) is disposed at a downstream side. Moreover, said turning section (18b) and said downstream side passage (18c) are formed into a particular shape, wherein passage sectional areas A1, A2 and A3 of the upstream side passage (18a), the turning section (18b) and the downstream passage (18c) of the bypass passage (18) are set as A1 < A2 and A1 < A3, more preferably A2/A1 ‰¥ 1.14 and A3/A1 ‰¥ 1.20 to suppress a contraction flow generated at the downstream of said turning section (18b).</p> |
