| 摘要 |
PURPOSE:To give a decrease in ventilation air volume even when the pressure difference in pressures of the outside and inside of a room is large by providing a ventilation fan with a flow straightening plate which changes its angle with respect to the direction of air flow according to the opening angle of an wind pressure type shutter which is provided at the air discharge port. CONSTITUTION:A fan 2 for sending air flow is mounted on a main body 1 and the fan 2 is driven by a motor 3. On an air discharge port 5 mounted is a wind pressure type shutter 4 which opens by air flow pressure. Further, flow straightening plates 7 which are arranged radially are mounted on a suction port 5, and the flow straightening plates 7 and shutter 4 are connected by a link mechanism 8. The angle of the flow straightening plates 7 with respect to the direction of air flow changes to become larger as the angle of opening of the shutter 4 becomes smaller. When, for instance, the difference of the pressures inside and outside of the room is large, the volume of ventilation air decreases and the angle of opening of the shutter 4 becomes small and the flow straightening plates 7 shall have an angle to the direction of air flow: they work as stationary vanes for the fan 2 and the rotation of the fan 2 is increased. Accordingly the volume of ventilation air increases. |
