This invention relates to a closure for providing protection, particularly environmental protection, around substrates, particularly elongate substrates such as cables and cable splices. The invention is of particular use for protecting telecommunication cables, but it may also be used with other cables such as power cables or with pipes or other conduits. Telecommunication cables with which it may be used include regular copper cables, fibre optic cables and CATV cables. The invention will usually be used with unpressurised cables, but may also be used with pressurised cables.

A particular instance where a cable closure is required is in the protection of a cable splice. Where cables are spliced some form of protective device is usually required to extend from the cable jacket of one cable, across the splice to the cable jacket of the other cable. Thus, the individual conductors of the cable are protected against the environment. Protection against various contaminants is required, in particular protection against moisture.

Whilst it is relatively simple to provide a central part of a splice closure to encase the splice, difficulties arise in providing seals between the ends of the housing and the cables entering the splice closure. Further difficulties arise where the splice closure is to be of the so-called wrap around design. This term simply means that the splice closure can be installed around the cable without access to a free end of the cable. This is frequently necessary because splices are frequently made by joining one cable to an intermediate part, rather than to an end, of a main cable. In such situations the free ends of the main cable may be some long distance away from the position of the splice. Such splices are frequently referred to as branched splices and the splice closure will have provision for sealing more than one cable at one or each end. A further reason why a splice case might need to be of the wrap around design is for repair. An initially-installed splice case is removed, and a new splice case is installed without disconnecting the conductors and therefore without creating free ends of the cable.

Wrap around splice closures may comprise a central housing which is initially in the form of a substantially flat sheet which on installation is wrapped around the cable splice and then joined together along its longitudinal edges. Other designs involve substantially semi-cylindrical half shells which are brought together around the cable to be enclosed. The term "wrap around" applies also to such substantially rigid parts.

As mentioned above, some form of sealing must be provided between the ends of the housing and the cables entering the splice closure. If the splice closure is to be entirely of the wrap around design, then these end seals must also be able to be installed without access to a free end of the cable. A further difficulty arises because of the wide tolerances involved in cable manufacture. The precise diameter, and shape, cannot be predicted. Also, it is desirable that a single product be able to be used with different sizes of cable. This reduces the inventory that must be carried by the engineer in the field. These requirements should be considered in the light of the overall performance requirements. Typically, a cable splice closure is expected to have a life time comparable to that of the cable to protected. That may be as long as twenty or more years. Furthermore, cable closures must perform their function of environmental protection etc under adverse conditions. For example, they may be subjected to daily and seasonal temperature cycling, as well as rain, humidity, environmentally-borne contaminants, and mechanical abuse.

The final consideration that might be mentioned is that splice closures must be simple and foolproof to install, even in awkward places, such as at a top of a telegraph pole, in a manhole, or in a pit for subsequent burial.

The inventors were therefore faced with a problem of providing a seal of wraparound design that can accommodate a range of cable sizes and that meets stringent performance specifications.

Many designs have been proposed for cable closures including the provision of epoxy-filled moulds, hot-melt adhesive-coated heat shrinkable sleeves, and housings having initially separate sealing blocks at each end. The present invention may be regarded as a development of this last type of splice closure.

In particular, the present invention is concerned with a device for containing a sealing material generally at an end of a housing such that the sealing material does not become displaced axially along the cable entering the splice closure. Such displacement may, in the absence of the invention, arise for any of a variety of reasons. The sealing materials will frequently be chosen because of their ability to be deformed into contact with the cable and with the surrounding housing in order to fill any gap between them and thereby prevent contaminants entering the splice closure; and the property that allows a sealing material to be deformed into sealing engagement with the cable and the surrounding housing can of course allow excessive creep which could ultimately lead to failure of the seal. Such creep could arise through various forces, particularly the force applied to the sealing material to achieve sealing engagement, through internal pressurisation of the splice closure (whether deliberately in the case of pressurised cables or unintentionally due to temperature increase) and through gravity etc.

The inventors have now designed a device that can help to contain or retain a cable sealant, that can be wrap around and that can adapt itself to match the size of the cable. In particular, the device may remain relatively flat and the deformation and/or dimensional adaptation of the device to the size and shape of the cable may stay within a plane perpendicular to the axis of the cable. The device can be easy to install, and can if desired be built into a housing such that it is closed around the cables automatically when the housing is installed.

Thus, in a first embodiment the invention provides a device for retaining a sealing material in a cable closure against movement of the sealing material axially with respect to a cable entering the closure, the device comprising first and second parts that can be brought together around a said cable over a range of a cable sizes; at least one of the parts having deformable and/or displaceable projections that are deformed and/or displaced as the parts are brought together; the extent of deformation and/or displacement depending on the cable size, and the deformation and/or displacement being substantially in a plane perpendicular to the cable.

In a second embodiment the invention provides a device for retaining a sealing material in a cable closure against movement of the sealing material axially with respect to a cable entering the closure, the device being substantially cylindrical and having end faces substantially perpendicular to its axis; the device comprising first and second parts that can be telescoped radially together around a said cable over a range of cable sizes; the extent of telescoping depending on the cable size, and the area of said end faces depending on the extent of telescoping.

In a third embodiment the invention provides a substantially planar device that can be secured around an elongate object, which comprises first and second parts that can be brought together in substantially co-planar fashion; each end part having a plurality of substantially concentric ribs or other elements, the ribs or other elements of the first part becoming increasingly interdigitated with those of the second part as the two parts are brought together.

In a fourth embodiment the invention provides a device for retaining a sealing material in a cable closure against movement of the sealing material axially with respect to a cable entering the closure; the device having deformable and/or displaceable means defining an axial passage for said cable over a range of cable sizes, the extent of deformation and/or displacement depending on (and generally being automatically determined by) the cable size; the device additionally having a locking means to resist reversal of said deformation and/or displacement.

In a fifth embodiment the invention provides a substantially planar device that can provide a radially extending flange or collar around an elongate object over a range of sizes of the elongate object, which comprises first and second substantially planar parts which can be brought together around the object; at least one of the parts having a passage that can accommodate objects of different size; the two parts having locking means by means of which they can be secured together.

In a sixth embodiment the invention provides a substantially planar device that can be secured around an elongate object, which comprises first and second parts which can be brought together in substantially co-planar fashion, at least one part having a plurality of substantially concentric or otherwise arranged deformable and/or displaceable ribs which can be deformed and/or displaced to accommodate between the parts elongate objects over a range of sizes.

In a seventh embodiment the invention provides a cable splice closure which comprises: 1) a housing for enclosing an incoming cable and having a port through which an incoming cable can pass; 2) a sealing material for forming a seal between the cable and the port through which it passes; and 3) a substantially planar device for containing the sealing material against movement of the sealing material axially with respect to the cable and through the port, the device having an axial passage through which the cable passes; the housing having a substantially cylindrical recess (which need not be circular in cross-section, and in fact is preferably substantially rectangular in cross-section) adjacent to the port and inwardly or outwardly of the sealing material within which is positioned the device; the device having a thickness substantially equal to the axial extent of the recess; the device being deformable in a plane substantially perpendicular to the cable by bringing towards one another circumference-separated portions of the periphery thereof thereby reducing the size of the passage to match that of the cable; and the housing optionally including means within the recess for brining the portions towards one another.

It is explicitly stated that any two or more of these seven embodiments may be combined, and that each such possible combination constitutes part of the present invention.

Any suitable sealing material may be used, but we prefer rubbers, mastics or gels (for example rubber gels). For many uses rubber or other gels would be preferred. Suitable materials are disclosed in WO 90/05401, the disclosure of which is incorporated herein by reference. Preferred gels are liquid-extended polymer compositions preferably having a cone penetration value (measured by a modified of ASTM D217) within the range of from 30 to 400 (10"1 mm); an ultimate elongation (measured by ASTM D412) greater than 100%, with substantially elastic deformation to an elongation of at least 100%. The composition may either contain three-dimensional cross-linked molecular formations, or may merely behave as if it contained such molecular formations. Examples of preferred gels are those comprising a block copolymer having a relatively hard blocks and relatively elastomeric blocks (e.g. hydrogenated rubbers blocks). Examples of such copolymers include styrene- diene block copolymers.

The device which prevents or inhibits movement of the sealing material may be made from any suitable material, and in general metallic or polymeric materials will be preferred. Examples include stainless steel, aluminium, polyethylene, propylene and nylon. In general, the device will be deformable in order to accommodate the range of cable sizes. Such deformation is preferably elastic, at least over the extent of deformation required in practice. Thus, some resilient bias against the cable may remain during the service life of the product. However, in some situations partial or complete plastic/residual deformation may be allowable since cable replacement is unlikely. This deformation to accommodate a range of cable sizes will in general be in a plane perpendicular to the cable, and may though need not be radial with respect to the cable. Preferably there is substantially no deformation and/or displacement of any part of the device in a direction parallel to the cable. Thus, the device (where initially substantially planar) remains substantially planar during installation and service. The deformational characteristics of the material of the device, and the shape of the device, are in general selected to render the device sufficiently stiff in one direction to resist movement of the gel or other sealing material axially along the cable whilst remaining flexible enough for the desired range taking to accommodate a range of cable sizes. Materials and designs to deliver these characteristics will be readily selected by a person skilled in the art after reading this specification.

Overall, the device may be regarded as being substantially cylindrical, at least in envelope or outline. That cylindrical shape need not, of course, be of circular cross section, and a rounded substantially rectangular cross-section may be preferred. The device will in general be substantially disc shaped (by which we do not imply that it must be circular) so that the cylinder has a cross sectional dimension considerably greater than its axial length, for example at least 2X, preferably at least 4X, especially at least 6X, typically at least 8X.

Where the device comprises first and second (and optionally further) parts which are brought together around the cable, they may be urged together by some resilient means (such as a spring) provided as part of the overall splice closure. Each of the parts may be pre- installed in a part of a splice closure. When the closure is assembled around a cable the parts of the device are automatically brought together.

The parts may be interconnected by some means such as a hinge (for example a living hinge) or by a strap.

The parts of the device may be brought together by relative rotational movement between them and/or by relative translation. Translational movement may be radial with respect to the cable (particularly when the device comprises three or more segments) or the parts may simply move together along a common line or axis (particularly when the device consists only of two parts).

The parts may interlock particularly by form of ratchet effect, such that they may be held together at any of a variety of relative positions, thus accommodating the range of cable sizes. A portion of one part may slide within a portion of another part (i.e. may telescope) such that projections of one engage with recesses in the other.

The parts may be provided with means to prevent one being displaced relative to the other in a direction parallel to the cables. Thus, a portion of one part may slide within a recess of the other part, said recess extending in a plain perpendicular to the cable.

The device may provide one or more functions other than (or in addition to) its function of retaining a sealing material. In particular, it may provide meachnical location. Thus, it may restrain the cables from being pulled out of the splice closure, i.e. provide axial pull-strength. A further function is providing resistance to cable twisting (torque strength).

We prefer that any gaps between the device and the cable, between the device and the surrounding cable closure, and within the device itself be less than 3mm especially less than 2mm, more preferably lmm or less.

The invention is further illustrated with respect to the accompanying drawings, in which: Figure 1 shows in perspective view a two part device prior to installation around a cable; Figures 2A and 2B show the device installed around a cable and positioned within a splice closure; Figures 3 A and 3B show the parts of a device preinstalled in a cable splice closure; Figures 4A, 4B and 4C show how the device accommodates a range of cable sizes; and Figure 5 shows the device together with integrated springs. Figure 1 shows a containment device comprising a first part 1 and a second part 2 prior to installation around a cable 3. The parts are substantially planar (at least in outline or envelope), and the device may be regarded as substantially disc shaped although not of circular cross section. Each part has a plurality of substantially concentric or otherwise arranged ribs that may be regarded as being secured together by a projection 5 which also secures them to a base 6 of each part. When installed the bases 6 could be regarded as forming an anulus around the cable, the gap between that anulus and the cable being substantially filled by the deformed and/or displaced ribs. The initial separation between adjacent ribs is preferably less than 5mm, more preferably less than 2 mm, in particularly less than 1 mm. Clearly the greater the initial separation the larger would be the biggest cable that can be accommodated. However, if the separation between the ribs is too large, then the ability of the device to contain the sealing material will be impaired. The greatest separation that can be tolerated will depend on the pressure to which the sealing material is subjected and on the deformability of the sealing material.

The parts are provided with means 7, in this case interlocking projections and recesses that provide a ratchet effect, thereby allowing the parts to be brought together and preventing subsequent separation. Relative movement between the first and the second parts in a direction parallel to a cable may be prevented by each part having a surface 8 perpendicular to the cable against which the other parts abuts. In this way, one part may be slid within the recess in the other part.

Stop means 9 may be provided to prevent the parts being brought too far together since stop means 9 will ultimately abut the cable.

In figure 2A the parts have been brought together around cable 3. The ribs of one part can be seen to be interdigitated with those of the other part at positions 10. The four curved arrows show roughly the directions in which the ribs have been deformed.

Figure 2B shows a cable closure, or more precisely an end part of a cable closure. The closure comprises a housing 11 into which the cable 3 passes. The device of the invention (consisting of parts 1 and 2) is housed in a substantially cylindrical, or disc shaped, recess 12, generally of substantially rectangular cross-section. It can be seen that the device has a thickness substantially equal to the axial extent of the recess. Thus, gaps 13 are small or non-existent. In this way, sealing material is prevented from transversing the device of the invention by first moving radially outwards and then around its ends.

The sealing material is shown as item 14, and it can be seen to be forced into sealing engagement with the cable and with parts of the housing 11 by means of springs or other resilient means 15. It can be seen that springs 15 will cause the sealing material additionally to be deformed axially with respect to the cable and along or adjacent the surface of the cable, since pressure within the sealing material will act in all directions. It is this movement that the device of the invention prevents or restricts.

Each of parts 1 and 2 of the device can be seen to have a stepped shape so that they interlock at 16 with the entire device being substantially planar, and therefore able to fit into the substantially cylindrical recess 12.

An additional feature is shown, namely support 17 for aiding transmission of the compressive force provided by springs 15 to the sealing material 14. This support may itself be a sealing material, but generally one harder than that of the bulk of the sealing material 14.

Figure 3A shows the device pre-installed within a splice closure prior to installation of the splice closure around the cable 3. In figure 3B the parts have been brought together. The sealing material 14 has been forced into contact with the cable and with parts of the housing, and the parts 1 and 2 of the device of the invention have been brought together to prevent axial displacement of the sealing material 14.

The parts 1 and 2 are provided with springs or other resilient means 18 in order that they can be brought together to the appropriate extent depending on the size of the cable 3. Also, the springs may provide a continuing resilient bias on the parts during the service life of the product.

Figures 4A, 4B and 4C show the device and the entire closure for three different sizes of cable. The curved arrows represent approximately the extent of deformation of the circumferentially-extending ribs of the device.

In Figure 5 the first and second parts of the device are provided with integral resilient means 19 which bear against the splice closure housing to force the parts together to the correct extent. In the illustrated embodiment means 19 is integral with the remainder of the parts, but it may be initially separate and later attached, or it may be an integral part of the housing or it may merely be located between the housing and the device.

Each part of the device may be monolithic or it may comprise various separate parts which are joined together in some way, for example by bonding. We prefer that each part be a single molded article.