Closure fasteners – Extension link – Chain
Patent
1991-06-10
1991-12-31
Moore, Richard E.
Closure fasteners
Extension link
Chain
292201, E05C 1736
Patent
active
050766244
ABSTRACT:
A door chain device not allowing the disengagement of its engaged member from a door-side member by manipulating the chain from the outside. In the door chain device wherein a chain is fixed at one end to the door frame and has an engaging member at the other end, the engaging member has a flanged end which is inserted into a through hole made in the door-side locking member and then fitted into a slit extending from the through hole. The improvement is comprised of the flanged end having a permanent magnet, a door-side member having a bottom plate made of a ferromagnetic material, the bottom plate having an oval hole at a position corresponding to the through hole. Thereby when the flanged end reaches the oval hole the magnetic balance therein is broken to generate a magnetic force by which the flanged end is turned in the oval hole and therefore it cannot pass out from the hole.
REFERENCES:
patent: 3275364 (1966-09-01), Quinn
patent: 3705504 (1972-12-01), Johnson
patent: 3944268 (1976-03-01), Gonyaley et al.
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