| 摘要 |
PURPOSE: To forcibly discharge the air heated in a heat insulating air layer by providing a vent pipe communicating the heat insulating air layer formed on a closing member with the outside of a cover through the chamber of the cover. CONSTITUTION: A cylinder section 2 is formed at one end of a cover 1, and a base 3 is fitted to the cylinder section 2. A closing member is fitted to the other end opening of the cover 1. The member 4 is formed with a pair of partition boards 5, 6, and a heat insulating air layer 8 is formed between the boards 5, 6. A lighting circuit component storage chamber 11 is formed in the cover 1, and a lighting circuit component 13 is stored in the chamber 11. A vent pipe 17 is provided through the chamber 11 in the axial direction, one end of the vent pipe 17 is connected to the board 5 and opened to the layer 8, and the other end is connected to a partition wall 10 and communicated with an atmosphere open chamber 12. The air heated in the layer 8 flows out into the chamber 12 through the vent pipe 17 and is discharged to the outside from the chamber 12. |
