Electricity: conductors and insulators – Conduits – cables or conductors – Single duct conduits
Patent
1996-05-31
1998-08-04
Ledynh, Bot L.
Electricity: conductors and insulators
Conduits, cables or conductors
Single duct conduits
174 77R, 285 12, 285177, H02G 318
Patent
active
057897077
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a sealing device for sealing around elongate objects, and particularly to a sealing device suitable for use as an end plate which can be used in combination with a sleeve to form a closure assembly for enclosing an elongate substrate such as a splice between telecommunications cables.
The invention is described primarily in terms of a sealing device for sealing around elongate objects in the form of cables or joints between cables. However it is also applicable for sealing around other elongate objects, in particular pipes or joints therebetween.
It is often necessary to make seals around cables or other elongate objects for example to prevent moisture or other contaminants having access to part of the elongate object. In particular it is necessary to provide environmental seals for cable systems, such as telecommunication cable systems. It is often necessary to make splices in such cables, either to join cables end to end or to make a branch joint in a cable. Such splices may be protected by splice cases.
Known splice cases may comprise an outer member surrounding the splice and at least one end seal device through which the cable can enter the splice case. The end seal device must provide a good seal around the cable and a good seal to the splice case. Splice cases are in general expected to have a life-time comparable to that of the cables they join, say twenty years. Achieving a high level of environmental and mechanical protection over such lengths of time puts considerable constraints on design.
International patent specification W090/05401 (Raychem) discloses a closure assembly for an elongate object. A preferred embodiment of W090/05401 describes a closure assembly comprising two end plates which are spaced apart within an outer sleeve, and which each have at least one opening for receiving the elongate object. A sealing material is located between the plates and the plates are moved relative to each other to compress the sealing material so as to displace it to give maximum contact between the sealing material and (a) the outer sleeve and (b) the elongate object. After the closure assembly has been placed around the elongate object in the arrangement of W090/05401, all the movement required to compress the sealing material is obtained by moving an end plate through which the elongate object passes.
It is desirable for the end plates to provide strain relief to elongate objects passing through them. This may be achieved by designing the end plates to grip the cable or other elongate object passing through them as firmly as possible so that forces applied to the elongate object are resisted by the end plates rather than by any connectors joining individual conductors of the cable. While the assembly of W090/05401 is very successful in forming a seal around elongate objects it does require relative movement between one or more of the end plates and the elongate object(s)(s) passing therethrough, and this movement may be incompatible with design features of the end plates desirable to optimise grip of the end plates on to the elongate objects.
SUMMARY OF THE INVENTION
We have designed a new device for forming a seal around an elongate object which comprises a sealing plate through which an elongate object can pass but which does not require relative movement between the plate and the elongate object. The invention, therefore, allows more freedom for the designer to provide various features on the sealing plate, for example for strain relieving elongate objects passing therethrough.
A first aspect of the present invention provides a device for forming a seal around an elongate object comprising: containing a chamber in communication with the said hole; chamber; and elongate object passes, in use, through the hole in the sealing plate, the sealing material is positioned between the pressure plate and the elongate object, object in a direction transversely of the object, to urge the sealing material into sealing contact with the object.
Pre
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Damm Jesper
Laeremans Etienne
Michiels Maarten
Nolf Jean-marie Etienne
Burkard Herbert G.
Ledynh Bot L.
N.V. Raychem S.A.
Reinhard Dean A.
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