| 摘要 |
PROBLEM TO BE SOLVED: To reduce low-frequency sound remarkably. SOLUTION: A square sound-proofing case 51, through which air-conditioning air flows, is provided and an inlet port opening 54 and an outlet port opening 56 are formed on the lower wall unit 53 and the upper wall unit 55 of the sound-proofing case 51 at parts near respective corners. The inlet port unit 61a of a square ventilation duct 61 is attached to the opening rim of the inlet port opening 54 to fix the same under airtight condition by a mounting flange 65 while the outlet port unit 61b of the ventilation duct 61 is supported by the opening rim of the outlet port opening 56. A multitude of through-holes 63 are formed on the four surfaces of the pipe wall 62 of the ventilation duct 61 at the height of half of the four surfaces. |
