IES64144B2

IES64144B2 - An optical fibre management system

Info

Publication number: IES64144B2
Authority: IE
Inventors: Eamon Daly
Original assignee: Manorbeach Ltd
Priority date: 1995-02-07
Filing date: 1995-02-07
Publication date: 1995-07-12
Also published as: IES950097A2; GB2298053A; GB9502814D0; GB2298053B

Abstract

An optical fibre management system (1) has an hermetically sealed enclosure (4) comprising wall 5, plug 8 with two or more sockets 20, and an annular cap 6. A support plate (2) is cantilevered to a plug (8) via fastener (9) to provide secure support but with a certain amount of resilience. The clamps (22, 25) for cable (7) and strength member (24) are mounted in-line with plugs (20) which are sealed if not used. A flange (26) on the support plate (2) provides support for cables having a number of fibres, the cassettes (3) supporting the individual fibres and being held on plate (2) by bolt and wing nut (15). The support plate may have downwardly-directed flanges to provide the cassettes on both sides for easy segregation of fibres and utilisation of space. (Figs 3-5, not shown).

Description

An optical fibre management system The invention relates to a management system for optical fibres. The term management system is intended to cover a system which provides a housing for fibre splices, excess fibre, and cable ends, and which also provides for access to the fibres for frequent splicing modifications and connection of additional fibres.

An object of the invention is to provide an optical fibre management system which may be repeatedly opened up to provide easy access to optical fibres and their splices.

Another object is that the system provides strong protection for the fibres and the splices, particularly when the system is opened for access. A still further object is to provide a system which applies as little as possible mechanical stress on the fibres. Another object is to provide an hermetically sealed fibre environment.

It is known to provide a housing which supports a number of cassettes which in turn store excess cable and the cable splices. Examples of such housings are described in US 4,266,853, US 4,418,982, US 4,500,166, GB 2,122,378, GB 2,165,661, GB 2,167,877, EP 216,073 and FR 2,573,877. Some of these housings suffer from the disadvantages that they do not provide an hermetic seal for the fibres whereby they can be mounted underground, while at the same time providing ease of access for maintenance and addition of splices and fibres.

The invention is directed towards providing an improved optical fibre management system.

According to the invention, there is provided an optical fibre management system comprising:S 6 41 44 - 2 an hermetically sealed enclosure comprising:a housing wall of substantially circular cross-section and having a domed end; a plug having a plurality of sealed sockets extending from a plug wall; and an annular cap for connecting the plug and housing wall together to form an hermetic seal; a support plate comprising:a planar base; a flange having an upwardly-directed side wall and an inwardly-directed lip defining a cable housing above the base; and a fastener to allow the support plate to be connected to the enclosure plug for cantilevered support within the enclosure; a plurality of cassettes for housing optical fibres and their splices; means for securing the cassettes to the support plate; a cable clamp mounted on the support plate in registry with a socket for mechanical clamping of a multi-fibre cable when inserted in the socket after the latter has been opened; and a strength member clamp mounted on the support plate in-line with the cable clamp.

In one embodiment, the support plate fastener comprises means for securing the support plate to the plug at a plurality of different cantilevered support positions.

Preferably, the fastener comprises an upwardly-directed tab having an elongate aperture for engagement with a bolt.

In another embodiment, the support plate comprises upper and lower flanges to define cable housings both above and below the base.

Ideally, the system further comprises a cable clamp and a strength member clamp mounted on the support plate at its lower surface.

In a still further embodiment, the upper and lower cable clamps are mounted in-line and are secured in place by a single bolt extending through the support plate.

Preferably, the support plate has a plurality of apertures providing passageways for cable.

The invention will be more clearly understood from the following description of some embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which:Fig. 1 is a perspective view of an optical fibre management system of the invention; Fig. 2 is a diagrammatic cross-sectional view of part of the system; Fig. 3 is a perspective view of portion of an alternative system of the invention; Fig. 4(a) is a plan view of a support plate of the system of Fig. 3 and Fig. 4(b) is a cross-sectional front view; and Fig. 5 is a diagrammatic cross-sectional front view of the system of Fig. 3.

Referring to the drawings, and initially to Figs. 1 and 2, there is shown an optical fibre management system of the invention, indicated generally by the reference numeral 1. The system 1 comprises a support plate 2 which supports cassettes 3 which in turn house lengths of excess optical fibres and their splices or joints. The cassettes 3 and the support plates 2 are mounted within an enclosure 4 which provides an hermetic seal. The enclosure 4 comprises an enclosure wall 5 of substantially circular cross-section and with a domed end or an hermetically sealed cap end. There is an annular cap 6 for the enclosure 4. Optical fibre cables 7 enter the enclosure 4 through a plug 8, the plug 8 providing an hermetic seal with the cap 6 and the enclosure wall 5.

At an inner end closest to the plug 8, the support plate 2 comprises a fastener 9 which comprises a tab with an elongate slot. The tab 9 is connected to the plug 8 by way of a bolt. As the support plate 2 is not connected to any other part of the enclosure, it is therefore cantilevered to the plug 8. Accordingly, the support plate 2 provides a certain degree of resilience upon vibration of the enclosure 4 which can help to prevent damage to fibre or cable connections as they are much less likely to be forced. Further, the plug (holding the support plate) may be easily removed.

The cassettes 3 which are mounted on the support plate 2 comprise an aluminium base 10 having side tabs 11. Optical fibres 12 are run in loops between the side tabs 11 and terminate in splices or joints 13. There is a transparent cover 14 which snap-fits over the side tabs 11 in position to support the fibres and the splices. All of the cassettes 3 are secured to the support plates 2 by a fastener 15 which comprises a bolt and wing nut.

As shown in Fig. 2, the plug 8 comprises a pair of sockets 20 which extend away from the wall of the plug and are sealed. For connection of a cable 7, the seal is broken by, for example, sawing away the end of the socket 20. This is the situation shown in Fig. 2 whereby a cable 7 runs through the socket 20 and there is a heat-shrink plastics wrap 21 surrounding both the cable 7 and the socket 20. The end of the cable 7 is clamped by a cable clamp 22 which has a bolt 23. The clamp 22 comprises a pair of opposed clamping jaws of plastics material, the jaws being sized to surround and clamp the cable 7 without providing excessive mechanical stress. The clamp 22 is mounted in registry with the socket 20, also to avoid any mechanical stress on the cable 7. The support plate 2 also holds a clamp 25 for a steel strength member 24 which protrudes from the end of the cable 7. This is mounted in-line with the cable clamp 22. Finally, the support plate 2 comprises an upper flange 26 which has an upwardly-directed side wall and an inwardly-directed lip, the latter acting as a support platform for the cassettes 3.

Because the socket 20 is sealed and must be opened up for use, the system 1 maintains an hermetic seal, even if one of the sockets is not being used. The arrangement of clamps 22 and 25, in registry with the socket 20, provides a simple way of supporting the cable within the system to avoid any undue mechanical stress. The smaller cables or tubes within the cable 7 protrude from the end at the clamp 22 and extend on each side of the clamp 25. They are supported beneath the cassettes 3 and between the flanges 26, the latter defining a cable housing beneath the cassettes. At the far end of the support plate 2, the optical fibres are trained upwardly into an associated cassette 3. Accordingly, the arrangement of support plate 2 provides safe protection for the small cables (which may have up to ten optical fibres) and of the fibres themselves. It will be appreciated that this arrangement is extremely simple for an engineer to understand and there is easy access to the fibres and their splices.

Referring now to Figs. 3 to 5, an alternative system of the invention is shown. The system is indicated by the numeral 30 and is shown with a pair of input sockets 31 and a pair of output sockets 32. An enclosure plug 33 supports a support plate 34 in a cantilevered manner by way of a fastener 35. The support plate 34 has a number of upper flanges 36 and a number of lower flanges 37 so that it effectively provides for symmetrical support. There is a pillar 38 which allows the cassettes to be secured in place on both sides of the support plate 34.

The support plate 34 supports a pair, namely upper and lower cable clamps 39, mounted in registry with sockets 31 for the input cables. There is also a pair, namely upper and lower cable clamps 40 in registry with the output sockets 32 for the output cables. The cable clamps 39 have associated strength member clamps 41 and the cable clamps 40 have associated strength member clamps 42. This arrangement is best viewed in Fig. 5, whereby it is seen that the support plate 34 effectively provides for symmetrical support of cassettes 3 on both sides and within the overall dimensions of the enclosure 4. The dimensions of the support plate 34 are such that there is freedom of movement, as indicated by the arrow A in Fig. 5, to allow the precise location of the support plate 34 to be chosen for best advantage. It may, for example, be preferable to have more cassettes on one side than on the other. This freedom of positioning is also facilitated by the freedom of the cables within the sockets 31 and 32. The cantilevered support and spacings also allow vibration of the support plate 34 so that there is minimal stress on the fibres. For example, the situation is avoided where external applied pressure may cause parts within the enclosure to break or become disconnected if this resilience and freedom of movement is not provided. As shown in Fig. 4, the support plate 34 has a number of apertures 43 which allow cables to be moved between the two sides. Further, these apertures may be used for electrical cable required by maintenance personnel for transmission of signals.

It will be appreciated that the arrangement of support plates shown in Figs. 3 to 5, allows for segregation of different cassettes according to their usage. For example, cassettes which, support optical fibres which have a high usage may be mounted on top of the support plate, while those having a lower usage may be mounted below. Alternatively, working fibres may be placed on top, whereas spare fibres may be placed on bottom. This arrangement of system also provides for additional space for expansion when required.

The invention is not hereinbefore described, construction and detail. desired number of sockets limited to but may be For example, on the plug. the embodiments varied in both there may be any

Claims

1. An optical fibre management system comprising:an hermetically sealed enclosure comprising:a housing wall of substantially circular 5 cross-section and having a domed end; a plug having a plurality of sealed sockets extending from a plug wall; and an annular cap for connecting the plug and housing wall together to form an hermetic 10 seal; a support plate comprising:a planar base; a flange having an upwardly-directed side wall and an inwardly-directed lip defining 15 a cable housing above the base; and a fastener to allow the support plate to be connected to the enclosure plug for cantilevered support within the enclosure; a plurality of cassettes for housing optical 20 fibres and their splices; means for securing the cassettes to the support plate; > a cable clamp mounted on the support plate in registry with a socket for mechanical clamping of a multi-fibre cable when inserted in the socket after the latter has been opened; and a strength member clamp mounted on the support plate in-line with the cable clamp.

2. An optical fibre management system as claimed in claim 1 wherein the support plate fastener comprises means for securing the support plate to the plug at a plurality of different cantilevered support positions, and preferably the fastener comprises an upwardly-directed tab having an elongate aperture for engagement with a holt.

3. An optical fibre management system as claimed in any preceding claim wherein the support plate comprises upper and lower flanges to define cable housings both above and below the base, and preferably the system further comprises a cable clamp and a strength member clamp mounted on the support plate at its lower surface, and preferably the upper and lower cable clamps are mounted in-line and are secured in place by a single bolt extending through the support plate.

4. An optical fibre management system as claimed in any preceding claim wherein the support plate has a plurality of apertures providing passageways for cable.

5. An optical fibre management system substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.