| 摘要 |
PROBLEM TO BE SOLVED: To provide a ventilation fan for a duct excellent in facility by providing an air supply opening body to suppress penetration of night air and an air supply opening body. SOLUTION: A shutter disc 33 is rotatably arranged at the internal part of a connection cylinder body 22 for supply air, and the opening area on the suction side of a connection cylinder body 22 for supply air by an air shield plate 36 is reduced to a value smaller than that of a side 33a of a shutter disc 33 by an air shield plate 36. When external air flows toward the suction side of the connection cylinder body 22 for supply air, a force exerted on the shutter plate 33 by external air is decreased, whereby the shutter disc 33 is prevented from rotation in the direction of an arrow mark C in Fig. 1, and penetration of unnecessary air is suppressed. On the contrary, when a blast fan is rotationally driven and the delivery side of the connection cylinder body for supply air is brought into a negative pressure state, the shutter disc 33 is rotated in the direction of the arrow mark C in Fig 1 by a negative pressure, a vent passage 39 is released, and outdoor air is fed in a bath room. |
