| 摘要 |
PURPOSE:To obtain an inexpensive detector having a simple structure, reduced in the effect of dust or moisture and easy to maintain, by detecting the opening degree of a damper opened and closed by the differential pressure between the inside and outside of a barn and outputting a position signal from an angle- of-rotation sensor. CONSTITUTION:A ventilation fan controlled by a temp. controller, a pressure introducing port 204 and a suction port having a hood outside a barn are provided to the wall 202 of the barn. The damper 208 fixed to a shaft 207 having an angle-of-rotation sensor 210 mounted thereon is provided to the pressure introducing port 203. When the air-flow quantity of the ventilation fan is changed, the differential pressure between the inside and outside of the barn changes and the damper 28 provided to the pressure introducing port 204 rotates along with the shaft 207 corresponding to said differential pressure. The angle- of-rotation sensor 210 detects the angle of rotation of the shaft 207 and outputs the signal corresponding to the angle of rotation. A differential pressure signal output part 211 converts said signal to a differential pressure signal to transmit the same to a pressure controller 212 and outputs a drive signal to a speed reducer 213 to open and close a buffle plate.
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