Electricity: conductors and insulators – Conduits – cables or conductors – Combined
Reexamination Certificate
1999-12-09
2001-06-05
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Conduits, cables or conductors
Combined
Reexamination Certificate
active
06242700
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a conformable seal assembly for cables entering a splice case, and in particular to an end seal assembly that is easily installed and removed while restricting migration of fluids into and out of the splice case.
BACKGROUND OF THE INVENTION
Frequently in the telecommunications industry, it is desirable to splice together two or more cables, either to extend a cable or to tap into another cable. The formation of a splice involves removal of the outerjacket and other layers of the cable to expose the individual conductors or optical fibers which are then individually connected to the conductors or fibers of another cable or cables. After the splice is formed, it must be protected from water and other vapors to prevent corrosion or a short circuit. For this purpose, the splice area is often enclosed in a splice case that is formed from two trough-like half shells with separate end plates or seals. Different end seals are used to accommodate different diameter cables and splice cases of different dimensions.
An example of such an end seal is disclosed in U.S. Pat. No. 5,258,578 (Smith et al.). This end seal is adapted to seal the space between the cables and the splice case to restrict fluid transfer through the seal. The seal is formed from a body of an elastic, flexible material such as a gel having self-adhesive properties. The body comprises a core portion and a tail portion. The core portion has a shape corresponding to the ends of the splice case and includes cylindrical openings through which the cables extend. The opening are exposed at the outer peripheral surface of the core. The body of the seal also includes a tail portion that is integral with, and extends from, the sur face of the core portion. The tail portion has a length sufficient to wrap about the outer peripheral surface of the core to cover all the cylindrical openings. The openings are generally smaller than the diameter of the cables to be placed therein so that the elastic core must expand for the openings to accommodate the cables. When wrapped around the core, the tail seals the portion of the cable between the core and the inside surface of the ends of the splice case.
As a result of its elastic properties, the previously described end seal is capable of sealing a variety of different diameter cables. The diameter of the end seal is determined by the number of cables extending through the core, the diameter of the cables, and the length of the tail portion. As a consequence, the diameter of the end seal is easily changed. This feature allows the end seal to be used in splice cases of differing diameter.
One limitation of this end seal is that, whenever it is removed from a splice case, the seals formed between the core and the cables extending through the openings in the core are disturbed, and therefore the cables must be repositioned upon re-installation of the end seal. Moreover, while the diameter of the end seal can be varied, this feature is unnecessarily cumbersome in those situations where splice cases of a standard size are to be used. In particular, because the end seal is not standardized for any given splice case, additional hardware, such as gaskets or washers, are sometimes required to properly insert the end seal in the closure. In some cases, it is even necessary to trim the end seal so that it will fit in the closure.
There is thus a need in the art for an end seal assembly in which the cables remain fixed in the core even when the assembly is removed from the closure, and which can be made compatible with many different cables and closures with a minimum of effort.
A further problem encountered with some existing end seal assemblies, particularly those which are wrappable (e.g., end seals of the core-and-tail variety) or which have a layered configuration, has to do with telescoping. With a core-and-tail type end seal, for example, the tail portion is often wrapped somewhat loosely around the inserted cable at the time it is placed into the assembly. As a result, a sealant or adhesive which is injected into the end seal has a tendency to ooze through any gaps between overlapping sections of the end seal. Moreover, if a longitudinal force is applied to the inserted cable before the sealant or adhesive has hardened sufficiently, the end seal will tend to telescope inwardly or outwardly from the closure, thereby undermining the integrity and mechanical strength of the seal. There is thus a need in the art for a wrappable end seal which resists telescoping and which minimizes loss of sealant or adhesive through gaps in the end seal.
These and other needs are met by the present invention, as hereinafter described.
SUMMARY OF THE INVENTION
The present invention provides an end seal assembly for use in sealing the area at the end of a splice closure or terminal through which cables are positioned, thereby restricting moisture from entering the closure. The end seal assembly preferably includes an end seal of the core-and-tail type, wherein the end seal has an integral core with a wrappable tail portion extending tangentially therefrom. In some embodiments, the end seal is enclosed in a rigid collar that has an outer surface which provides a standard configuration that fits into a correspondingly configured splice case, regardless of the precise dimensions of the end seal itself. Accordingly, the end seal assembly does not require trimming or additional hardware when it is placed in the closure. A cavity formed between the end seal and the collar may be filled with an expanding sealant material or other suitable sealant or adhesive so as to provide an airtight seal and to bond into an integral unit the wrapped end seal, a cable inserted through the core of the end seal, and the rigid collar.
In accordance with one aspect of the invention, an end seal assembly is adapted to seal the space between at least one cable and a closure to restrict fluid transfer through the seal. The end seal assembly includes an end seal having a body formed from an elastic, flexible material. The body includes a core portion which typically has an outer peripheral surface, spaced ends, and a wall forming at least one cylindrical opening through the core portion, which cylindrical opening extends between the spaced ends. The wall has two edges communicating with the outer peripheral surface of the core portion to define between the two edges an entrance slot to the cylindrical opening. An extended tail portion is integrally formed, with and extends from, the surface of the core portion. The tail portion, which has a surface tangential to the wall forming the cylindrical opening, has a sufficient length to wrap about the peripheral surface of the core portion to form a wrapped end seal such that the tail portion covers the entrance slot of the opening and a cable to be placed therein.
The end seal assembly further comprises a rigid collar having first and second collar portions that are pivotably interconnected. The first and second portions have inner surfaces that conform to, and enclose, the wrapped end seal to form an inner cavity between the wrapped end seal and the first and second portions of the collar. The collar also has an outer surface adapted to sealingly abut an end of the closure. A sealant composition fills the inner cavity to bond together the wrapped end seal, the cable to be placed in the cylindrical opening, and the rigid collar.
In another aspect, the present invention provides a cable splice closure end seal assembly in which the end seal has a core portion with a tail portion extending tangentially therefrom. The tail portion is provided with a mesh on the surface thereof which is adapted to bond tightly to a sealing composition or adhesive, and which is particularly useful with an expandable foam sealing composition. In a related embodiment, the tail portion comprises two substantially parallel rails which are connected to each other by a plurality of transverse members to form a ladder-like configuration. The tail portion in eit
3M Innovative Properties Company
Fortkort John A.
Nguyen Chau N.
Reichard Dean A.
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