| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem that, when a space occupied by a hinge structure is large in an iron lid having a small opening size, the entering and exit of an opener becomes difficult especially in a structure requiring the operation of an internally installed shut-off valve and the like from the outside. SOLUTION: Two rails which are composed of line grooves are vertically symmetrical, and face each other are formed at the inner peripheral surface immediately below a lid mounting portion of an iron lid receiving frame opening whose upper surface is exposed. An upper end grooves of the rails are closed. Parts of rail sides to which a pin corresponding to an approximately entire rail width, tilted at about 30 degrees in the right and left direction viewed from a receiving frame center is projected are notched. A rod-shaped hinge metal fitting which is journaled swingingly in the right-angled direction to a horizontal surface of a lid body is formed on the lid body. The other end of the hinge metal fitting has the pin which is engaged with the rails of the receiving frame, and slides and turns. The pin abuts against the notched portions of the rails and connected by twisting. COPYRIGHT: (C)2011,JPO&INPIT
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