Electricity: conductors and insulators – Anti-inductive structures – Conductor transposition
Patent
1987-04-22
1988-11-29
Grimley, Arthur T.
Electricity: conductors and insulators
Anti-inductive structures
Conductor transposition
267167, H05K 900
Patent
active
047883812
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a device for sealing between the edge portions of two metal plates used as screens against electromagnetic fields, including a metallic sealing strip intended to be compressed along the edge portions.
BACKGROUND OF THE INVENTION
Electronic equipment associated, for example, with modern telephony and data transmission installations, is often fitted into metallic apparatus cabinets which screen off electromagnetic fields. For this screening to be effective, metallic sealing strips must generally be applied between the edge portions of the cabinet sides and adjacent to possible doors. Sealing strips are also required at the edges of cable compartment hatches in the floor in front of, and between different apparatus cabinets.
Sealing strips in the prior art are comprised of such as a metallic net, which is placed round an elastic, elongate core, or an elongate metal strip with a plurality of projecting, resilient tongues. A disadvantage with these sealing strips is that their sealing action decreases with time, due to the metal plates oxidising, which give deteriorated metallic contact. The known sealing strips are also relatively expensive, resulting in large costs for the total length of sealing strip required in a modern telephone exchange, for example.
OBJECTS AND SUMMARY OF THE INVENTION
An object of the present invention is to provide a device for sealing between the edge portions of metal plates according to the above, the sealing action of the device being maintained for a considerably longer time than for previously available sealing devices, and which is furthermore cheap to manufacture. This is achieved by the device including a sealing strip, which is a helcially wound metal element of sharp-cornered cross section. If this sealing strip is compressed in a suitable way between the edge portions of the metal plates, parts of the sharp-cornered sides of the element will be pressed against these edge portions so that good metallic contact is obtained.
The distinguishing features of the invention are disclosed in the claims.
BRIEF DESCRIPTION OF THE DRAWING
The invention will now be described in detail with reference to the accompanying drawing, wherein
FIG. 1 is a side view, partially in section, of an apparatus constructed in accordance with the invention prior to a sealing strip being compressed;
FIG. 2 is an end view of the apparatus of FIG. 1;
FIG. 3 is a side view corresponding to the view of FIG. 1, after the compression of a sealing strip; and
FIG. 4 is an end view of the apparatus of FIG. 3.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
In FIGS. 1 and 2 there is illustrated in side view, and end view from the right in FIG. 1, an embodiment of a device implemented in accordance with the invention. The device includes a sealing strip 1, which is accomodated in a through-like groove 2 in the edge portion of one of two metal plates between which sealing is required. The sealing strip 1 is not shown in a compressed state and comprises a metal element wound into a helical shape. The metal element has a sharp-cornered cross section with a thickness of about 1 mm, and is manufactured from a material such as stainless steel. This cross section is preferably quadratic, but may have some other shape with edges, e.g. it may be hexagonal or rectangular. In a practical embodiment, the diameter of the helical strip is about 7 mm.
The through-like groove 2 is in a metal section 3, made from such as aluminium, and constitutes an edge portion of one of the two metal plates between which sealing is required. For example, the metal plates may comprise the lower part of one of the sides in an apparatus cabinet and a hatch to a cable compartment in the floor on one of the sides of the cabinet. Substantially the lower half (in the Figure) of the groove 2 is defined by a semicircular surface and its upper right-hand portion by the two flat surfaces forming a right angle, while its upper left-hand side portion is open. Of these surfaces, the one flat surface
REFERENCES:
patent: 3011775 (1961-12-01), MacLeod
patent: 3502784 (1970-03-01), Kunkel
patent: 3505463 (1970-04-01), McAdams
patent: 4322572 (1982-03-01), Snyder
Grimley Arthur T.
Telefonaktiebolaget L M Ericsson
Tone David A.
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