| 摘要 |
PROBLEM TO BE SOLVED: To improve separating performance between inside air and outside air. SOLUTION: The outer circumference part of a partition part 36 in a fan 22 and the tip parts of partition walls 29a, 29b of fan casings 20a, 20b are arranged so as to overlap to each other in the axial direction of the fan 22. Especially, when an overlapping amount g between the partition part 36 and the partition walls 29a, 29b is set to be 3 mm or more, an amount ratio of inside air flowing into a first passage 30a from a second passage 30b via a clearance 35 to the total amount of outside air sucked by means of a first fan 22a is reduced to 10% or less. Consequently, the separation performance between inside air and outside air can be improved.
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