| 摘要 |
PURPOSE:To prevent air flowing through an air feed port from leaking toward an exhaust port when the pressure difference between air in the room and air outside the room is small (that is, the density of air in the room is low) by a method wherein in case the titled ventilating fan is capable of supplying and discharging air at the same time, the sectional area of the opening of the air feed port inside the room is made smaller than the opening outside the room. CONSTITUTION:The ventilating fan 1 is formed of a body 2, a vane 3, a motor 4 for driving the vane, the air feed port 5, the exhaust port 6 and a cover 7. When the vane 3 is driven, polluted air is discharged and at the same time, fresh air flows into the room throgh the air feed port 5 because a negative pressure generates in the room. In this case, the sectional area of the opening 5a of the air feed port 5 inside the room is made smaller than that of the opening 5b of the port 5 outside the room so as to increase the flow velocity of air passing through the opening 5a whereby when the pressure difference between the open air and the air in the room (that is, when the density of air in the room is low), the air flowed into the room through the air feed port 5 is prevented from leaking toward the exhaust port 6. |
