| 摘要 |
<p>PURPOSE:To provide the device low in cost, by simplifying an air passage. CONSTITUTION:A bell mouth 1 for controlling the drift of air is provided, as a body different from the detecting part 5, on the upper or down stream side of a detecting part 5 of an air flow within a cylindrical air passage body 3. By thus being provided, the structures of the air passage and bell mouth 1 become simple, and the device low in cost can be provided.</p> |
