| 摘要 |
PURPOSE:To reduce a vent air resistance and an exhaustion sound, to improve a suction force and to arrest discharged particles or liquids thereby to clean the exhaust air by providing a down-drawing ventilating fan for exhaustion within a duct, forming the same ventilating fan, and forming a flow-down liquid receiving groove along the peripheral edge of a downward directed lower end opening. CONSTITUTION:A machine box of a ventilating fan 7, that is, the lower end opening 8 at the lower end part 13 of an exhaust duct 6 opens down-wardly toward the ground surface 9 and the blast area of the lower end portion 13 of the same duct expands larger than the blast area of an exhaust port 5 and the middle part of the duct thereby to increase the negative pressure. The ventilating fan 7 forms a propeller fan by a rotary vane 12, and condensed water drops, oil particles and minute particles such as smoke and the like are attached to the inner peripheral surface (of the lower end 13) of a duct 6 by a centrifugal force to form a centrifugal separation. A flow-down liquid receiving groove 21 is formed in the inner peripheral edge of the lower end opening 8 of the duct 6. A flow-down liquid flow-out port 22 is formed at the downstream end of the groove 21 and a flow-out port 22 in a freely attachable and detachable manner. |
