GB2169093A

GB2169093A - Optical fibre splice housing

Info

Publication number: GB2169093A
Application number: GB08432777A
Authority: GB
Inventors: Ian Mackinlay
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-12-31
Filing date: 1984-12-31
Publication date: 1986-07-02
Also published as: GB8432777D0

Abstract

An optical fibre splice housing for use in fibre optic cables comprising a plurality of elements of cable, maintains a separation between two or more cable elements, creating sufficient space between them to accommodate one or more lengths of optical fibre (5), optical fibre loops (6), (which may or may not be embedded in a strengthening material such as epoxy resin), optical fibre splices, optical fibre mountings and/or other components. The optical fibre splice housing may be rectilinear in the axial direction, or it may be barrel-shaped or it may contain a helical twist in order to accommodate the cable elements more conveniently. <IMAGE>

Description

SPECIFICATION Optical fibre splice housing for multi-element cables This invention relates to a protective housing for splices made in optical fibres incorporated in multi-element cables, such as hybrid electric and fibre-optic cables, pneumatic cables containing optical fibres, and mechanically strengthened fibre-optic cables of certain configurations.

Optical fibres are a well known means of communication comprising fine strands of glass or plastic through which optical signals can be transmitted. It is necessary to splice together lengths of optical fibre in order to permit signal transmission over long distances.

In a cable comprising one or more optical fibres it is usual to protect sections of optical fibre containing a splice by preventing tension being applied across the splice and by including one or more loops of optical fibre in the region of the splice within the cable. It is also a common requirement at splice sites in cables containing optical fibres to be able to accommodate a range of surplus lengths of the component optical fibres, which it is convenient to accommodate in the form of loops.

All such loops of optical fibre must have a diameter greater than a certain size both in order to prevent optical losses, and to reduce fatigue of the optical fibre due to internal stresses. Limits on the outer diameter of a cable place constraints on the maximum diameter of optical fibre loop that can be accommodated in the cable. In fibre-optic cables and hybrid cables comprising two or more cable elements, there are difficulties in accommodating such loops of optical fibre safely and conveniently. For instance, wrapping a length of fibre around the exterior of the cable exposes it to blows.

According to the present invention there is provided an optical fibre splice housing for use in fibre-optic cables and hybrid cables comprising a plurality of cable elements, which maintains a separation between two or more cable elements, creating sufficient space between them to accommodate one or more lengths of optical fibre, optical fibre loops (which might or might not be embedded in a strengthening material such as epoxy resin), optical fibre splices, optical fibre mountings and/or other components. The optical fibre splice housing may be rectilinear in the axial direction, or it may contain a helical twist in order to accommodate the cable elements more conveniently.

A specific embodiment of the invention is described in the following by way of example with reference to the accompanying drawings in which: Figure 1 shows the optical fibre splice housing in perspective with a loop of optical fibre in place; Figure 2 shows an alternative form of the optical fibre splice housing incorporating a tapered cable support element at each end; Figure 3 shows the optical fibre splice housing with cable elements to be separated in place around the housing; and Figure 4 shows the cross-section of the cable after insertion of the optical fibre splice housing, and illustrates the maximum possible diameter of optical fibre loops that can be accommodated within the optical fibre splice housing.

Referring to the drawings, the optical fibre splice housing comprises a plurality of guideways 1 for the cable elements, configured so as to separate the latter and thereby to provide an enclosed chamber between the cable elements that is sufficiently large to accommodate loops of optical fibre 6 of the required diameter; outer surfaces 2, which might or might not be detachable, to protect the optical fibre splices and loops from external blows and abrasion; ends 3, which might be open or partially open, or closed but for a cable opening (which might or might not be hermetically sealed) to permit access and passage of optical fibres 5; mountings 4 to secure optical fibre splices, optical fibres passing through the housing, cable clamping elements, strength member anchors, and/or other components.

Fig. 2 illustrates a variant of the optical fibre splice housing incorporating tapered cable support elements 7 at each end of the guideways 1.

Fig. 3 illustrates the optical fibre splice housing with cable elements (such as electric cables, air-lines, strength members, or fibreoptic cables not to be spliced at this point) 8 in place, separated by the guide ways of the housing. One or more optical fibres to be spliced 9 enter the housing.

Fig. 4 shows the transverse cross-sections of the optical fibre splice housing 10, of the separated cable elements in place 11, and of optical fibre loops within the housing 12. The maximum diameter of optical fibre loop that can be accommodated 13 within the housing is shown to be very close to the maximum diameter of the cable 14 at the housing in the case illustrated of a cable containing an odd number of cable elements. In cables containing an even number of cable elements the maximum diameter of optical fibre loop that can be accommodated within the housing is equal to the maximum diameter of the cable at the housing less only the thickness of the housing wall.

1. An optical fibre splice housing for use in fibre optic cables and hybrid cables comprising a plurality of cable elements, maintains a separation between two or more lengths of optical fibre (5), optical fibre loops (6), (which

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Optical fibre splice housing for multi-element cables This invention relates to a protective housing for splices made in optical fibres incorporated in multi-element cables, such as hybrid electric and fibre-optic cables, pneumatic cables containing optical fibres, and mechanically strengthened fibre-optic cables of certain configurations. Optical fibres are a well known means of communication comprising fine strands of glass or plastic through which optical signals can be transmitted. It is necessary to splice together lengths of optical fibre in order to permit signal transmission over long distances. In a cable comprising one or more optical fibres it is usual to protect sections of optical fibre containing a splice by preventing tension being applied across the splice and by including one or more loops of optical fibre in the region of the splice within the cable. It is also a common requirement at splice sites in cables containing optical fibres to be able to accommodate a range of surplus lengths of the component optical fibres, which it is convenient to accommodate in the form of loops. All such loops of optical fibre must have a diameter greater than a certain size both in order to prevent optical losses, and to reduce fatigue of the optical fibre due to internal stresses. Limits on the outer diameter of a cable place constraints on the maximum diameter of optical fibre loop that can be accommodated in the cable. In fibre-optic cables and hybrid cables comprising two or more cable elements, there are difficulties in accommodating such loops of optical fibre safely and conveniently. For instance, wrapping a length of fibre around the exterior of the cable exposes it to blows. According to the present invention there is provided an optical fibre splice housing for use in fibre-optic cables and hybrid cables comprising a plurality of cable elements, which maintains a separation between two or more cable elements, creating sufficient space between them to accommodate one or more lengths of optical fibre, optical fibre loops (which might or might not be embedded in a strengthening material such as epoxy resin), optical fibre splices, optical fibre mountings and/or other components. The optical fibre splice housing may be rectilinear in the axial direction, or it may contain a helical twist in order to accommodate the cable elements more conveniently. A specific embodiment of the invention is described in the following by way of example with reference to the accompanying drawings in which: Figure 1 shows the optical fibre splice housing in perspective with a loop of optical fibre in place; Figure 2 shows an alternative form of the optical fibre splice housing incorporating a tapered cable support element at each end; Figure 3 shows the optical fibre splice housing with cable elements to be separated in place around the housing; and Figure 4 shows the cross-section of the cable after insertion of the optical fibre splice housing, and illustrates the maximum possible diameter of optical fibre loops that can be accommodated within the optical fibre splice housing. Referring to the drawings, the optical fibre splice housing comprises a plurality of guideways 1 for the cable elements, configured so as to separate the latter and thereby to provide an enclosed chamber between the cable elements that is sufficiently large to accommodate loops of optical fibre 6 of the required diameter; outer surfaces 2, which might or might not be detachable, to protect the optical fibre splices and loops from external blows and abrasion; ends 3, which might be open or partially open, or closed but for a cable opening (which might or might not be hermetically sealed) to permit access and passage of optical fibres 5; mountings 4 to secure optical fibre splices, optical fibres passing through the housing, cable clamping elements, strength member anchors, and/or other components. Fig. 2 illustrates a variant of the optical fibre splice housing incorporating tapered cable support elements 7 at each end of the guideways 1. Fig. 3 illustrates the optical fibre splice housing with cable elements (such as electric cables, air-lines, strength members, or fibreoptic cables not to be spliced at this point) 8 in place, separated by the guide ways of the housing. One or more optical fibres to be spliced 9 enter the housing. Fig. 4 shows the transverse cross-sections of the optical fibre splice housing 10, of the separated cable elements in place 11, and of optical fibre loops within the housing 12. The maximum diameter of optical fibre loop that can be accommodated 13 within the housing is shown to be very close to the maximum diameter of the cable 14 at the housing in the case illustrated of a cable containing an odd number of cable elements. In cables containing an even number of cable elements the maximum diameter of optical fibre loop that can be accommodated within the housing is equal to the maximum diameter of the cable at the housing less only the thickness of the housing wall. CLAIMS

1. An optical fibre splice housing for use in fibre optic cables and hybrid cables comprising a plurality of cable elements, maintains a separation between two or more lengths of optical fibre (5), optical fibre loops (6), (which may or may not be embedded in a strengthening material such as epoxy resin), optical fibre splices, optical fibre mountings and/or other components.

2. An optical fibre splice housing as claimed in Claim 1., which may be rectilinear in the axial direction, or which may be barrelshaped or which may contain a helical twist in order to accomodate the cable elements more conveniently.

3. An optical fibre splice housing, as claimed in Claims 1 and 2, which incorporates a tapered element for cable support at one or both ends.

4. An optical fibre splice housing as claimed in Claims 1,2, and/or 3, which incorporates (outer) surfaces which may or may not be detatchable, to protect the optical fibres, splices and splice loops from external blows and abrasion.

5. An optical fibre splice housing as claimed in Claims 1,2,3 or 4, which may be open or partially open or closed but for a cable opening, (which may or may not be hermetically sealed,) to permit access and passage of optical fibres and mountings to secure optical fibre splices, optical fibres passing through the housing, cable clamping elements, strength member anchors, and/or other components.

6. An optical fibre splice housing as claimed in Claims 1,2,3,4, or 5, in which the maximum diameter of optical fibre loop that can be accomodated within the housing is close to the maximum diameter of the overall multi-element cable diameter at the housing.