| 摘要 |
PROBLEM TO BE SOLVED: To provide a duct fan capable of adjusting a total air quantity to a low level by reducing an air quantity of part of centrifugal air blowers, in the duct fan which includes the plurality of built-in centrifugal air blowers and cannot largely suppress the total air quantity since a rotational frequency of a motor cannot be largely reduced due to heat generation and deterioration in the efficiency of the motor when the air quantity is desired to temporarily be reduced as much as possible. SOLUTION: The plurality of centrifugal air blowers 10-1, 10-2 are provided in a box-shaped body 3 including a body suction port 1 and a body blowout port 2 opposing each other, and the air blowers 10-1, 10-2 are arranged forward and backward toward an inspection opening 18 and forward and backward toward the body suction port 1. By adjusting the total air quantity to a lower level by reducing the air quantity of the centrifugal air blower 10-1 with respect to the total air quantity in a state of the normal operation of all of the centrifugal air blowers 10-1, 10-2, the duct fan can largely suppress the total air quantity when the air quantity is desired to temporarily be reduced as much as possible. COPYRIGHT: (C)2010,JPO&INPIT |
