| 摘要 |
PROBLEM TO BE SOLVED: To provide a heat insulating underfloor inspection port never causing a dew condensation in a metallic lid. SOLUTION: A cavity 14 is provided in the connecting part between metallic inner frame 7 and outer frame 10, and the cold air conduction from the inner frame 7 and outer frame 10 to the metallic lid 2 is interrupted by a heat insulating material 6. A heat insulator 15 is provided between upper frame 4 and lower frame 5 for protecting a heat insulating material lid body 33 along the side circumference of the heat insulating material lid body 33 to break off the upper frame 4 and lower frame 5.
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