| 摘要 |
PURPOSE:To enable a ceiling cap to be moved downwardly and further enable an amount of ventilation to be freely varied by a method wherein an outer frame is arranged along an opening in a ceiling, a cap having such a size as enabling a closing of the opening is arranged below the opening, an outer frame is provided with a female thread, and a male thread is screwed with the female thread part CONSTITUTION:A cap 4 having the such a size as capable of closing an opening 2 is arranged below the opening 2, a female thread 6 is arranged at a frame 5 installed between the outer frames 3 and at the same time a male thread part 8 of a supporting shaft 7 projected above the cap 4 is screwed wit the female thread part 6 to cause the cap part 4 to be moved up and down. Therefore, the opening 2 is closed by moving the cap part 4 in such a way as it may be abutted against the lower surface of the ceiling 1 so that any ventilation may not be performed and further the up and down positions of the cap part 4 can be adjusted so as to adjust a clearance between the opening 2 and the cap part 4, resulting in that an amount of ventilation can be adjusted.
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