| 摘要 |
PURPOSE:To improve the rain drop resistance by generating a pressure signal in accordance with the pressure of the inside of a cylindrical member provided in parallel to the flow of a fluid, and deriving the flow velocity from this pressure signal. CONSTITUTION:A wind flows in parallel roughly along passage plates 17, 18, in a passage 20 formed by the plates 17, 18, and flows at the highest speed in the vicinity of the opening end 22a of a wind velocity detecting cylinder 22, therefore, negative pressure is generated in the cylinder 22. This negative pressure has a characteristic by which it becomes high as the wind velocity rises. Therefore, the pressure generated in the cylinder 22 is led to a semiconductor pressure sensor 24 by a pressure port 22b and a pressure leading-out tube 23, and measured, and from this pressure signal, the wind velocity is measured. Also, in case of a windy state, the negative pressure is generated in the cylinder 22, and the opening end 22a opens downward, therefore, it does not occur that a rain drop, dust, etc., invade the pressure port 22b and the pressure leading-out tube 23.
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