WO1992012842A1

WO1992012842A1 - Cable branch-off seal

Info

Publication number: WO1992012842A1
Application number: PCT/GB1991/002308
Authority: WO
Inventors: Alain Wambeke; Vanhentenrijk; Jean-Marie Etienne Nolf
Original assignee: Raychem NV SA; Raychem Ltd
Current assignee: Commscope Connectivity Belgium BVBA; Raychem Ltd
Priority date: 1991-01-18
Filing date: 1991-12-23
Publication date: 1992-08-06
Anticipated expiration: 1993-07-18
Also published as: MX9200233A; GB9101158D0

Abstract

A kit-of-parts suitable for sealing a branched cable splice, which comprises: a) a dimensionally-recoverable sleeve that can surround the splice with branching cables extending from an end thereof; and b) a branch-off clip that can be positioned on the sleeve at the end thereof so as to form at least two terminal conduits in the sleeve through each of which a respective cable can extend, the conduits being formed by bringing together between the cables circumferentially-separated portions of the sleeve; the clip being such that it can be positioned on a sleeve at an end thereof in each of two orientations, thereby bringing together portions of the sleeve of different circumferential extent.

Description

CABLE BRANCH-OFF SEAL

The present invention relates to a way of making a seal particularly an environmental seal around a cable splice,

especially between telecommunication or power cables.

Since cables are supplied in short lengths it is necessary that cables be spliced together. To do this, cable jacket is removed at the ends of the cables to be spliced in order to expose the copper or optical fibre or other conductors to be joined. Once the

conductors are joined the jacket has to be made good across the joint in order to protect the conductors from water or other environmental contaminant. This is done by constructing a so-called splice case across the splice.

In recent years splice cases have been made principally by positioning a heat-shrinkable wraparound or tubular sleeve around the splice, bridging intact cable jacket of the spliced cables. The sleeve is then heated causing it to shrink into tight, sealing, engagement with the cables. Thus, an environmental enclosure is constructed around the spliced conductors. The sleeve may be internally-coated with a hot-melt adhesive or other sealing material, and it may be installed around a liner, previously installed around the splice to provide some mechanical protection. A wraparound sleeve for such purpose is disclosed in

GB 1155470, and a sleeve plus liner is disclosed in GB 1431167.

Such splice cases may be simple to construct where the splice is between two cables, joined end-to-end. Each end of the heat-shrinkable sleeve shrinks around a single cable, which due to its wholly convex cross-section allows a seal easily to be made.

A problem may, however, arise where two (or more) cables or other substrates have to be sealed at one position. This problem, which is known as "branch-off" may occur, for example, at an outlet of a heat-shrinkable sleeve or other dimensionally- recoverable part. The problem arises because two side-by-side cables do not present a wholly convex cross-section to the sleeve shrinking down around them. Leak paths result between the cables and the surrounding sleeve that would allow contaminants to enter the splice case.

This problem has been solved for most purposes by the use of a branch-off clip as disclosed and claimed in GB-B-1604981. That invention provides a method of forming a branch-off seal between a heat-shrinkable sleeve and at least two substrates, which comprises the steps of:

(a) positioning the substrates within the heat-shrinkable sleeve;

(b) forming at least two heat-shrinkable terminal conduits by positioning a clip having at least two elongate legs over the outer surface of the heat-shrinkable sleeve at an open end thereof, wherein at least two of said legs are positioned externally of the sleeve and the substrates are within the terminal conduits; and

(c) while the clip remains on the outer surface of the heat-shrinkable sleeve applying heat so as to effect

shrinkage of the sleeve and to form the desired seal.

Preferred clips disclosed in that patent are formed as a trident where a central leg of the clip is coated with adhesive and passes within the sleeve between the branching cables.

Also disclosed in that patent is an adjustable three-way branch-off clip, where two outer legs are rotatably mounted on an extended part of an inner leg. This allows adjustment according to the nature of the branch-off required. In a further embodiment disclosed a clip is self-adjusting in that gaps between a central leg and outer legs may vary depending on the thickness of the heat- shrinkable sleeve with which the clip is used. This is achieved by constructing the central leg in two tapered parts that telescope together.

Whilst the trident clip disclosed in that patent allows an excellent seal to be produced, and has become the world-wide standard, I have noticed certain circumstances where an

improvement may be desirable.

Those circumstances are where the cables or other

substrates to be sealed are separated by a large, and particularly fixed, distance. The situation is exacerbated where the installer does not know in advance how large will be that separation. I believe that he would find it useful if he could be provided with a single standard kit (or a small number of kits) that allowed him to deal with any cable size and separation that he might meet.

Mention may be made of an attempt to solve the problem of separated cables. In GB 1604984 a fork-like member is used to bring together opposing portions of sleeve between the branching cables. The two thicknesses of sleeve are threaded between the prongs of the fork, and this holds them together over the

necessary distance.

I have now discovered that a branch-off clip can be

designed that can be used in different orientations depending on the separation between the cables or other substrates to be sealed.

Thus, the invention provides a kit-of-parts suitable for sealing a branched cable splice, which comprises:

(a) a dimensionally-recoverable sleeve that can surround the splice with branching cables extending from an end thereof; and

(b) a branch-off clip that can be positioned on the sleeve at an end thereof so as to form at least two terminal conduits in the sleeve through each of which a respective cable can extend, the conduits being formed by bringing together between the cables circumferentially-separated portions of the sleeve; the clip being such that it can be positioned on a sleeve at an end thereof in each of two orientations, thereby bringing together portions of the sleeve of different circumferential extent.

I prefer that the clip has a plurality of first legs that can be positioned externally of the sleeve, the first legs being

substantially fixed relative to one another. The clip may also have at least one second leg, comprising a hot-melt adhesive or other sealing material, that can be positioned within the sleeve.

Preferably the second leg comprises a support member that carries the sealing material and that can be attached directly or indirectly to the first legs. In a preferred embodiment the clip comprises a base to which the first legs are substantially

irremovably attached and the second leg is removably attached. The second leg can thus be initially positioned in the sleeve between the cables, and the base plus first legs then positioned over the sleeve to form the conduits and to connect to the second leg. A heat path is therefore established such that heat directed at the sleeve (by an open-flame torch etc.) causes shrinkage of the sleeve and heating of the second leg, via first legs and base, to activate the sealing material carried by the second leg.

Reference may be made to DE-OS-3148353 which discloses a cable branch-off clip having a central leg that may be removed from the rest of the clip. Also, a three-legged clip having one of its outer legs inserted into a hole in a base is disclosed in DE-OS - 3430088.

In the present case, at least two second legs may be

provided of different size, either of which can be attached to the first legs. This allows different amounts of sealing material to be delivered and/or different heat-paths to be provided depending on the cable types and branch configurations. Also, the or each second leg may be connectable to the first legs (via a base or otherwise) in two or more orientations, depending on the

orientation with respect to the cables in which the first legs are positioned.

In particular I prefer that the clip has at least four legs that can be positioned externally of the sleeve. In a preferred embodiment these four legs are positioned substantially at the corners of a non-square rectangle.

Thus, I prefer that pairs of legs be provided such that opposite (say upper and lower) pairs each act as does a single outer leg in the existing design disclosed in GB-B-1604981. The clip could, however, have been rotated, generally through 90°, before being put on the sleeve in order to have used different pairs of legs. The separation between the legs of each pair

(equivalent to the width of each leg in GB-B -1604981) determines the circumferential extent of the portions of sleeve brought together. That will of course depend on the separation between the cables. Thus, the chosen rotational orientation of the clip with respect to the cables will depend on the nature of the cable splice.

I prefer that at least some, and preferably all, of the legs used when the clip is in one orientation are the same as those used when the clip is in another orientation; the legs will merely be positioned differently. This will be the case when the legs lie substantially at the corners of a non-square rectangle. There, upper and lower pairs (for example) may be used with the clip in one orientation, and left and right hand pairs otherwise. In general, therefore, the legs of the clip can be nominally grouped as at least two sets of opposing pairs, respective pairs being

positionable at respective sides of the sleeve. Clips having four or more legs are known, although they cannot be used as required herein, and the present problem is not addressed in connection with them. EP-A-0040957 (Raychem) discloses a clip that comprises at least two interengageable parts that define channels and that can be assembled on the end of a heat-shrinkable sleeve. Each part may comprise a planar three- legged clip (the centre legs having recesses allowing their

interengagement) the two parts being slid together in

perpendicular planes to form a multi-legged clip that is cruciform in cross-section. The outer legs are positioned at the corners of a square and the clip cannot therefore solve the problem presently addressed.

A similar cruciform clip is disclosed in DE-OS -3105471 (Rose), and a multi-leg clip with all legs in one plane is disclosed in DE-OS-3430088.

The first legs of the present clip may have any suitable design, but I prefer that each comprises a looped elongate

member (generally U-shaped), the ends of the member being attached to a base of the clip. In another embodiment, each leg comprises substantially flat stock, optionally with holes

therethrough. In each case a balance can be obtained between the ability of the legs to pick up heat applied by a torch etc for conduction to the second leg, and the ability of the legs not to shield the underlying sleeve from the heat. Each loop, or other leg, is preferably substantially planar, the planes of respective legs preferably being substantially mutually parallel. For some uses, it may be desirable that the legs are directed slightly

towards one another towards their distal ends. That may reduce the tendency of the clip to "milk-off" the sleeve during heat-shrinkage.

Installation of the clip may be made easier if the first legs are not all of the same length. All of the legs need not then be pushed over the sleeve at the same moment. Preferably the clip has at least two pairs of legs that can be positioned externally of the sleeve, the legs of each pair being of substantially the same length, and those of different pairs being of different length.

The invention is further illustrated with reference to the accompanying drawings in which: figure 1 shows a prior art branch-off clip on an end of a heat-shrinkable sleeve;

figures 2a, 2b and 2c show a prior art two part branch-off clip and the way in which it is used;

figure 3 shows a four legged clip used in the invention;

figures 4a and 4b show second legs useable with the clip of figure 3;

figures 5a, 5b, 5c, and 6a, 6b and 6c show preferred designs of the general type of clip of figure 3, together with its second leg;

figures 7a, 7b and 7c show alternative designs to that of figures 5a, 5b, 5c. and 6a, 6b and 6c.

figures 8a and 8b show a clip positioned between branching cables that are separated by different distances;

Figure 1 shows use of a branch-off clip as disclosed in GB-B-1604981. A heat-shrink sleeve 1 is used to seal a branch-off splice between cables (not shown). A branch-off clip 2 has been positioned on an open end of the sleeve 1 to form two terminal heat-shrinkable conduits 3. The clip has two outer legs 4 that are positioned externally of the sleeve to bring together

circumferentially-spaced portions of the sleeve. The clip also has a centre leg 5 that may be coated with an adhesive, and that is positioned inside the sleeve between the cables. The sleeve 1 is heated causing it to shrink tightly into engagement with the cables, and causing the adhesive to become heat-activated.

Figures 2a, 2b and 2c show a clip as disclosed in EP-A-0040957. The clip comprises two parts as illustrated in figure 2a. The two parts are slotted together as shown in figure 2b. The clip is used to form a branch-off seal around four cables. Figure 2c is a cross-section through the four cables showing the end of the clip and the end of the sleeve that surrounds them.

The invention is illustrated in figures 3-8.

The clip shown in figure 3 comprises four legs 7

substantially irremovably fixed to a base 8. Each leg comprises a looped elongate member 9, generally of metal and generally U- shaped, mounted on the base 8. The four legs can be positioned substantially at the corners of a non-square rectangle. The long side of the rectangle is preferably at least 1.2 more preferably at least 1.3 times the short side, the corners of the rectangle being taken as the cross-sectional centres of the legs. Alternatively one may consider the widths of pairs of legs taken together, ie dimensions A and B. The width of one pair of legs is preferably at least 1.3, more preferably at least 1.4, particularly at least 1.5 times the width of another pair. This will be the better way of specifying the overall shape of the clip when the legs are not of circular or other simple cross-section.

Figures 4a and 4b show second legs 10 that are to be fixed to a base 8 of figure 3 and that will be positioned within a shrinkable sleeve. The legs 10 comprise a support 11, preferably heat-conductive, and a sealing material 12. The legs 10

preferably have means 13 for fixing them to base 8. The sealing material may comprise a portion 14 of enlarged cross-section for sealing large gaps between cables particularly at regions remote from the end of the sleeve. This may occur where cables to be sealed have at least two jackets that are stripped back different extents from the splice. Portion 14 may comprise novel means for displacing sealing material 12 radially or longitudinally as desired. For example flanges or springs may be provided that can be moved or otherwise activated by an extension of support 11. Figure 5a is a plan view of a clip, particularly for small cable gaps, showing four first legs 7 and one second leg 10 between them. Figure 5b is an end elevation from the distal ends of the legs, and figure 5c is an end elevation towards the base 8. The second leg is secured to the base by means of a nut, or other fixing means. The second leg can be seen to be of non-circular, generally oval, cross-section. It can be oriented as desired with respect to the outer legs, and is shown with its longer cross-sectional dimension aligned with the shorter pair separation of the first legs 7. One pair of legs 7 can be seen from figure 5 to be longer than the other pair. The longer legs may be, for example, 12-16, particularly 14, cms long, and the shorter legs from 1-3, generally 2, cms shorter.

Figures 6a, 6b and 6c show a slightly different design of second leg 10, which is also oriented in line with the outer legs. This is particularly useful for large cable gaps.

A yet different design is shown in figures 7a, 7b and 7c.

Here two different designs of second leg 10 are shown, having different cross-sectional shapes of sealing material and different orientations.

Figures 8a and 8b show in cross-section how the clip is used in different orientation depending on the separation between, and size of, cables 6. A portion of the heat-shrinkable sleeve 1 is shown in figure 8a, but the remainder of it, and all of it in figure 8b, is omitted for clarity.

In figure 8a there is a large separation between the cables 6 and the clip is orientated so that legs 15 and 16 act as one, and legs 17 and 18 act as the other of a pair. In figure 8b where the cable gap is small, legs 17 and 15 act as one, and legs 18 and 16 act as the other of a pair. For the avoidance of doubt it is noted that the invention provides kits, articles and methods for sealing or forming a branch-off, particularly where orientation of a clip can be altered according to substrate size or configuration. Any of the leg types, leg arrangements, clip positionings may be selected.

Claims

1 . A kit-of-parts suitable for sealing a branched cable splice, which comprises:

(b) a branch-off clip that can be positioned on the sleeve at the end thereof so as to form at least two terminal conduits in the sleeve through each of which a respective cable can extend, the conduits being formed by bringing together between the cables circumferentially-separated portions of the sleeve; the clip being such that it can be positioned on a sleeve at an end thereof in each of two orientations, thereby bringing together portions of the sleeve of different circumferential extent.

2. A kit according to claim 1, in which the clip has a plurality of first legs that can be positioned externally of the sleeve, the first legs being substantially fixed relative to one another.

3. A kit according to claim 2, in which the clip has at least one second leg that can be positioned within the sleeve.

4. A kit according to claim 3, in which the second leg comprises a sealing material.

5. A kit according to claim 4, in which the second leg comprises a support member that carries the sealing material and that can be attached to the first legs.

6. A kit according to claim 5, having at least two said second legs of different size, either of which can be attached to the first legs.

7. A kit according to claim 5 or 6, in which the clip comprises a base to which the first and second legs are attached.

8. A kit according to claim 7, in which the second leg is

removable attached to the base, and the first legs are substantially irremovably attached to the base.

9. A kit according to any preceding claim, in which the clip has at least four legs that can be positioned externally of the sleeve.

10. A kit according to claim 9, in which the four legs are

positioned substantially at the corners of a non-square rectangle.

1 1. A kit according to any preceding claim, in which legs that can be positioned externally of the sleeve comprise

respective looped elongate members, the ends of the members being attached to a base of the clip.

12. A kit according to claim 11, in which each loop is

substantially planar, the planes of respective loops being substantially mutually parallel.

13. A kit according to any preceding claim, in which the clip has at least two pairs of legs that can be positioned externally of the sleeve, the legs within each pair being of substantially the same length, and those of different pairs being of different lengths.

14. A branch-off clip that can be positioned on a dimensionally- recoverable sleeve at an end thereof so as to form at least two terminal conduits in the sleeve through each of which a cable can extend, the conduits being formed by bringing together between the cables circumferentially-separated portions of the sleeve;

the clip being such that it can be positioned on a sleeve at an end thereof in each of two orientations, thereby bringing together portions of the sleeve of different circumferential extent.

15. A branch-off clip according to claim 14, having at least four legs that can be positioned over the outer surface of the sleeve to form the conduits, and that can be nominally grouped on at least two sets of opposing pairs, respective pairs being positionable at respective sides of the sleeve.

16. A branch-off clip according to claim 15, in which the two

sets of opposing pairs consist of the same legs.

17. A branch-off clip according to claim 16, having four legs

positioned substantially at the corners of a non-square rectangle.

18. A branch-off clip according to any of claims 14-17, having a leg comprising a sealing material that can be positioned within the sleeve.

19. A branch-off clip according to claim 18, in which the leg

comprising a sealing material is detachable from the remainder of the clip.

20. A method of forming a branch-off seal between a

dimensionally heat-recoverable sleeve and at least two substrates, which comprises the steps of: (a) positioning the substrates within the sleeve.

(b) forming at least two recoverable conduits by positioning a clip according to any of claims 14-19 over an outer surface of the sleeve at an open end thereof, wherein at least two legs of the clip are positioned externally of the sleeve and the substrates are within the terminal conduits; and

(c) while the clip remains on the outer surface of the sleeve applying heat so as to effect recovery of the sleeve and to form the desired seal.

21. A method according to claim 20, in which the substrates comprise telecommunications cables. * * * * * * * * * * * * * * *