WO1996009673A1

WO1996009673A1 - Sealing device

Info

Publication number: WO1996009673A1
Application number: PCT/GB1995/002230
Authority: WO
Inventors: Jesper Damm
Original assignee: Nv Raychem S.A.; Raychem Limited
Priority date: 1994-09-21
Filing date: 1995-09-19
Publication date: 1996-03-28
Also published as: GB9419032D0; AU3526895A

Abstract

A sealing device (1) for forming a seal between an elongate object and a hollow article comprises: a) a body portion; b) at least one gripping member (33); and c) at least in use, sealing material; wherein, in use, the or each gripping member (33): (i) can be moved relative to the body portion to grip an elongate object extending through the sealing device (1) and (ii) at least partly retains the sealing material.

Description

Sealing Device

The present invention relates to a sealing device for forming a seal between an elongate object and a hollow article, particularly between a telecommunications or electrical cable and a cable splice closure.

The invention is described primarily in terms of a sealing device for a cable splice closure, but the invention is also applicable to the formation of other kinds of seals, e.g. a seal between cables and/or pipes and a duct (which term includes a feedthrough).

Cable splices generally need to be sealed from the environment, and particularly from moisture, in order for them to maintain their signal integrity or electrical integrity over long periods of time, e.g. many years. Some telecommunications cables are pressurized with compressed air or nitrogen in order to prevent ingress of water, and consequently telecommunications cable splice closures which are used with pressurized cables need to be strong enough and sufficiently well sealed to withstand being pressurized internally. In addition to the requirement of being sealed against external environmental influences (and sometimes internal pressurized gases), cable splice closures generally need to be sufficiently rugged to withstand mechanical abuse (closures are often buried in the ground, for example), and importantly they need to provide mechanical protection for the splice, e.g. so that forces acting on the cables (e.g. axial, lateral, or twisting forces) are not transmitted to the splice such that the splice can become damaged. A further important requirement of many cable splice closures is that it must be possible (and preferably easy) to open them (often termed 're-enterability') in order to gain access to the splice so that modifications may be made to the splice (e.g. adding or removing cables or splices) or so that maintenance work may be carried out, and substantially to be able to close and seal the splice closure. It is not a trivial matter to design a cable splice closure which meets all of these requirements. As evidenced by the huge range of designs which have been proposed over the years, there is a continual need to improve the performance of cable splice closures in all respects.

US Patent No. 5124507 discloses a cable splice assembly comprising a sleeve, sealing members with cable passage openings for insertion in the ends of the sleeve, and semi-circular sealing elements in the form of individually removable bearing shells lining the cable passage openings of the sealing members, for adapting the openings to different cable diameters. In order to eliminate any air gaps between the cable and the surrounding bearing shells, a sealing tape or band is wound onto each cable. The sealing members each have an injection chamber between spaced apart front and rear cable passage openings, the injection chamber having an injection opening and a venting opening so that a sealing material may be injected into the injection chamber to form a seal between the cables and the sealing member.

US Patent No. 4933512 discloses a cable junction closure comprising a sleeve, a pair of rigid end plates for closing the spaces between the cables and the sleeve, an elastic tape wound around the cables for sealing any gaps between the cables and the rigid end plates, and an elastic tape wound around each rigid end plate for sealing any gaps between the end plates and the sleeve. In order to secure the cables to the sleeve, each cable is gripped by means of an annular screw support member which is itself attached to one of the rigid end plates in the sleeve. Three fastening screws having arcuate cable push members are screwed into holes in the circumference of the annular screw support member, and these screws are screwed radially inwards towards the cable in order to grip the cable.

US Patent No. 4341922 discloses a strain-relief device for use in a cable splice case, comprising a horizontal portion having a plurality of tangs projecting therefrom, a vertical portion projecting upwardly from the horizontal portion, and reinforcing means between the horizontal and vertical portions. The tangs on the horizontal portion grip the outer sheath of a communications cable, while the vertical edge abuts a cable collar. A hose clamp extending around the cable and through two of the strain relief devices may be tightened to cause the strain relief devices to grip the cable. The splice case is sealed by means of mastic sealant between pairs of split half washers in the cable collar.

US Patent No. 4538021 discloses a closure for a cable splice comprising first and second end plates, and first and second covers for forming a cylindrical housing. Each end plate includes a pair of jaw-tooth clamps, each of which is slidably mounted on a shelf. The jaw-tooth clamps may be moved along the shelves by tightening a hose clamp which extends around a cable and through slots in the jaw-tooth clamps, until their teeth become embedded in a cable, thereby clamping the cable.

US Patent No. 4295005 discloses a telecommunications cable splice closure comprising a pair of elongated covers and two flat end walls. The closure is provided with clamp supports adjacent each end wall, which are formed with radial slots in which metallic L-shaped, toothed clamping elements are slidably retained. The clamping elements may be slid into gripping engagement with a cable, and a hose clamp may be tightened around the cable and the clamping elements. To seal the closure, a band of compressible mastic sealant is placed about the cable between two washers seated in grooves in the covers.

I have now invented an improved sealing device which can simplify initial installation and subsequent re-entry and re-sealing, which can provide an excellent seal, and which can be secured extremely firmly to a cable or other elongate object, e.g. so that a splice is not damaged by external forces acting on the cable.

According to a first aspect of the present invention, there is provided a sealing device for forming a seal between an elongate object and a hollow article, the sealing device comprising: (a) a body portion;

(b) at least one gripping member; and

(c) at least in use, sealing material;

wherein, in use, the or each gripping member (i) can be moved relative to the body portion to grip an elongate object extending through the sealing device and (ii) at least partly retains the sealing material. Preferably the sealing material is retained in the body portion, at least in use.

The invention has the advantages of ease of installation and re-entry, and effectiveness of sealing, as explained below.

A particularly important advantage of the invention is that it is normally possible to install the sealing device on a cable or other elongate object intitially at approximately the correct position on the cable and then subsequently to slide the sealing device, if necessary, along the cable to precisely the correct position. For example, the formation of a splice between two or more cables and the installation of a closure around the splice, when carried out in the field, especially for example in a manhole, is a difficult and skilled operation: it is normally difficult to position the sealing device(s) on the cables initially at exactly the correct position such that a cover can then simply be placed around the sealing device(s) to enclose the splice. In practice, it is normally necessary to make adjustments to the positioning of the sealing device(s) so that the surrounding cover is properly located. The present invention normally allows such adjustments of the sealing device(s) since the body portion can generally be initially installed on the cables etc. at only approximately the correct position, and the gripping members then need to be moved relative to the body portion to grip the cable(s) only when all of the necessary positional adjustments have been made. In contrast, for example, the sealing members of the cable splice assembly disclosed in US 5124507 have to grip the cables relatively tightly when initially installed, since, unlike the sealing device of the present invention, those sealing members grip the cables by their two halves being forced together around the cable, and hence subsequent positional adjustments of the sealing members are relatively difficult. The present invention enables the installation of a cable splice closure to be simplified, i.e. made less 'craft-sensitive'.

Another advantage that the sealing device of the invention can provide is that it is generally easy (and quick) to install the sealing device on an elongate object because of the dual function of the gripping member(s), namely gripping of the cable(s) and retention of the sealing material. It is generally not necessary to perform separate operations to grip the elongate objects and to ensure that the sealing material is retained, in contrast to some prior art sealing devices: with the present invention, the gripping member(s) will normally retain the sealing material automatically, at least when moved to grip the elongate objects. The gripping member(s) at least contribute to the retention of the sealing material; they may be said to comprise a dam for the sealing material.

The sealing device of the invention can normally provide an excellent seal, e.g. against environmental influences such as water and (optionally) for maintaining internal pressurisation of a cable splice case. In preferred emboidments of the invention, this excellent sealing characteristic is due. in part, to the sealing material which is used (e.g. gel) and the method of ensuring that the sealing qualities of the sealing material are optimized (e.g. by the use of novel means for compressing the sealing material), but in all embodiments of the invention, the fact that the gripping member(s) themselves retain the sealing material (either alone or in combination with other parts of the sealing device) means that such excellent sealing can be achieved. Since the gripping members can be moved relative to the body portion of the sealing device to grip the cables etc. extending through the sealing device, it is normally possible substantially to prevent unwanted passage of sealing material along the cable(s) by a tight gripping contact of the gripping member(s) on the cable(s). In preferred embodiments of the invention, a retention strip may be wound around a cable prior to actuating the gripping member(s), and therefore the gripping member(s) may not directly contact the cable(s), but in these embodiments of the invention the fact that the gripping member(s) can be brought into tight gripping contact with the retention strip can mean that egress of sealing material around the wound retention strip is substantially prevented.

According to a preferred embodiment of the invention, the body portion of the sealing device comprises first and second spaced apart end plates, between which, at least in use, the sealing material is retained. Preferably, the or each gripping member is attached to the body portion of the sealing device. Accordingly, when the body portion comprises first and second spaced apart end plates, the or each gripping member is preferably movably attached to an end plate. Even more preferably, the or each gripping member may be located at least partly within an end plate of the sealing device, e.g. in a channel in the end plate. This has an advantage in that it provides a guide for the gripping member and may, for example, provide support for the gripping member in a direction perpendicular to its movement in use, e.g. to support it against axial forces acting on a cable. The sealing device preferably has one or more apertures for the elongate object(s), and preferably, therefore, the first and second end plates (where present) have one or more apertures to allow one or more elongate object(s) to extend therethrough. It is most preferred that the or each gripping member is located, in use, at least partly within an aperture of an end plate of the sealing device. This may effectively provide a movable extension of the end plate in an aperture through the end plate, and in this way the gripping member may contribute to the retention of sealing material, e.g. between the end plates. The gripping member(s) in this way comprise(s) a movable dam for the sealing material, preferably at each end plate. The movement of the or each gripping member relative to the body portion of the sealing device may advantageously be in a direction transverse, preferably substantially perpendicular, to the direction in which an elongate object extends, in use, through the sealing device. The or each gripping member may, for example, take the form of a gripping part attached to a shaft, e.g. a threaded shaft so that, for example, the shaft may be screwed (further) into the sealing device so as to push the gripping part against an elongate object extending through the sealing device. The or each gripping member preferably has a generally arcuate gripping surface, e.g. as part of a gripping part, especially so as to grip an elongate object with a curved cross- section (e.g. a substantially circular cross-section cable or pipe) effectively.

The or each gripping member is preferably operable externally of the sealing device, e.g. by hand. For embodiments in which the gripping member(s) comprise(s) a gripping part and a threaded shaft, the sealing device may advantageously have a passageway communicating between an aperture in the sealing device and the outside of the sealing device, and a shaft may extend between the gripping part of the gripping member through the passageway to the outside of the sealing device, where it can be operated (e.g by hand) to make the required movement of the gripping member.

In preferred embodiments of the invention, two or more gripping members cooperate, in use, to grip one or more elongate objects therebetween. Preferably, therefore, the gripping members operate as jaws which may be opened and closed to release, or to grip, respectively, one or more elongate objects. In embodiments in which the body portion comprises first and second spaced apart end plates, preferably each end plate has one or more gripping members. More preferably, therefore, each end plate has one or more pairs of cooperating gripping members, preferably arranged so that an elongate object extending, in use, through the sealing member may be gripped by one pair of gripping members movably attached to the first end plate and by another pair of gripping members moveably attached to the second end plate. This arrangement has the advantages of enabling a particularly firm grip to be put on an elongate object and substantially ensuring that the elongate object is held rigidly with respect to the sealing material located, in use, between the end plates, thereby substantially ensuring that optimum sealing is achieved. It is particularly preferred that each aperture in an end plate of the sealing device has a pair of cooperating gripping members. An especially preferred arrangement is one in which each end plate has two apertures and each aperture has a pair of cooperating gripping members.

The sealing device may advantageously be 'wrap-around' (by which is meant that it may be positioned around an elongate object without having to slide it on to an end of the object). More preferably, the body portion of the sealing device comprises two major parts which are separable in a plain in which, or substantially parallel to which, an elongate object extending, in use, through the sealing device extends. The two major parts can preferably be joined together by joining means, e.g. screws or bolts or the like. In embodiments in which the sealing device is formed from two major parts, preferably the or each aperture (where present) extending through the sealing device is formed partly by one part and partly by the other part, such that when the parts are brought together the or each aperture is created. It is additionally preferred that each major part of the sealing device has one or more gripping members. For example, in embodiments of the invention in which pairs of cooperating gripping members are provided, each major part of the sealing device preferably provides one gripping member of each pair, for example located in a region of the part which, when the two parts are brought together, forms an aperture.

According to particularly preferred embodiments of the invention, a wall extends between the first and second end plates of the sealing device, which wall substantially encloses at least part of the space between the end plates, thereby providing a cavity in which the sealing material may be retained, at least in use. Preferably, the sealing device is generally, or substantially, circular in cross-section, and the wall is therefore preferably substantially tubular. In embodiments in which the sealing device is divided in two major parts, each part preferably has its respective portion of the wall, e.g. such that the wall comprises two semi-cylindrical portions which, when the two parts are brought together form a substantially continuous tubular wall between the end plates.

The sealing device may advantageously further comprise means for improving the sealing characteristics of the sealing material or for converting the sealing material from a non-sealing state to a sealing state. The means may additionally or alternatively comprise means for moving the sealing material into sealing contact with an elongate object extending through the sealing device. The sealing device therefore preferably further comprises a pressure member which can be moved, in use, towards an elongate object extending through the device, to urge the sealing material against the object. Urging the sealing material against the elongate object in this way may place the sealing material in sealing contact with the object and/or may pressurize the sealing material. Pressurization of the sealing material can often improve the sealing characteristics of the sealing material, especially when it comprises gel, for example. Preferred sealing materials are described below.

In preferred embodiments, the pressure member is located within, and movable relative to, the cavity in which the sealing material is preferably retained, at least in use. More preferably, the pressure member is movable in a direction transverse, preferably substantially perpendicular, to the direction in which an elongate object extends, in use. through the sealing device. The pressure member may, for example, have a shaft, e.g. a threaded shaft, to which it is attached, so that the shaft may be screwed (further) into the sealing device so as to push the pressure member against the sealing material towards an elongate member extending through the device in use. The pressure member is preferably operable externally of the sealing device, e.g. by hand. For embodiments in which a shaft is connected to the pressure member, the shaft preferably extends through a passageway communicating between the cavity in the sealing device and the exterior of the sealing device. The sealing device may advantageously have a resilient member arranged to bias the pressure member against the sealing material. This is desirable since it generally provides a constant application of pressure onto the sealing material during the working lifetime of the sealing device. The resilient member may be a spring, especially a helical spring or the like, and it may, for example, be located on the shaft attached to the pressure member.

It was mentioned above that in preferred embodiments of the invention, a retention strip may be wound around a cable or other elongate object prior to actuating the gripping member(s). The retention strip is preferably constructed such that when, in use, it is wound around an elongate object it can decrease in length when compressed around the object, thereby contracting around the object. Preferably, when the retention strip is contracted around an elongate object, it can grip the object. Advantageously, the retention strip may be wound around a cable or other elongate object in order to increase the effective diameter of the cable to be closer to that of an aperture in the sealing device; one or more (preferably two) gripping members of the sealing device may then compress the retention strip around the cable, and because the strip can decrease in length, it may contract around the cable. The retention strip may help to retain a cable in place with respect to the sealing device and/or may help to retaining the sealing material in the sealing device (e.g. in the cavity of the sealing device, where present).

The retention strip preferably comprises one or more, preferably a plurality, of collapsible portions, and the strip can preferably decrease in length due to the collapsing of one or more of the collapsible portions. The collapsible portion(s) may collapse by means of any of a variety of mechanisms, for example by telescoping (in a manner similar to a collapsible telescope). Preferably, however, the or each collapsible portion can collapse by deforming, e.g. by being crushed or concertinaed or by buckling. Preferably such deformation occurs in a direction generally or substantially parallel to the (axial) direction of extension of the elongate object around which the strip is wound, in use, and can be directed inwardly and/or outwardly, preferably outwardly, with respect to the remainder of the strip. This generally has the advantage of not giving rise to the formation of gaps (or at least significant gaps) between the windings of the strip through which sealing material might otherwise be able to escape. The or each collapsible portion preferably comprises a relatively weak portion of the retention strip. More preferably, the or each collapsible portion comprises one or more webs extending between substantially non-collapsible portions, e.g. one or more relatively thin portions which can deform, e.g. by buckling or concertinaing.

Preferably, the retention strip comprises a plurality of alternately collapsible and non-collapsible portions along at least part, preferably all, of the length thereof. This has the advantage of normally providing substantially uniform collapsibility along the length of the strip, such that the strip may contract relatively or substantially uniformly around an elongate object.

The or each collapsible portion (where present) of the retention strip may advantageously provide the flexibility to enable the retention strip to be wound around an elongate object. The or each substantially non-collapsible portion may, for example, be relatively or substantially inflexible (i.e. stiff): this stiffness can have the advantage of enabling the substantially non-collapsible portions of the strip to grip an elongate object relatively firmly. Advantageously, therefore, the retention strip may comprise a plurality of alternately substantially inflexible and flexible portions along at least part of its length.

The retention strip may advantageously be profiled such that, when wound spirally around an elongate object in use successive windings interlock with each other, thereby substantially preventing helical displacement of the windings with respect to each other along the object. This may provide at least two important advantages. Firstly, it generally provides the retention strip with strength to resist axial forces acting on an elongate object (e.g. a cable) when it is wound around the object, i.e. it can substantially prevent the strip from telescoping out along the elongate object under the action of such axial forces, and therefore the grip of the strip on the elongate object can normally be retained. Secondly, it generally prevents accidental displacement of the windings of the strip with respect to each other (e.g. due to axial forces on the elongate object or for some other reason), which might otherwise compromise the ability of the strip to retain sealing material. The retention strip may, for example, have a plurality of protrusions and recesses which can engage with each other when the strip is wound in use. More preferably, the or each substantially non-collapsible portion (where present) of the retention strip has one or more projections on one surface thereof and one or more cooperating recesses on the opposite surface thereof, such that, for example, when the strip is wound around an object the projection(s) of one non-collapsible portion fit together with the recess(es) of another non-collapsible portion which it overlaps, or by which it is overlapped.

Preferably, the retention strip has a plurality of protrusions on a surface thereof, to enhance the grip of the retention strip on an elongate object around which it is wound in use. These protrusions may advantageously comprise protrusions which fit into cooperating recesses as described above. Preferably these protrusions are located only on the or each substantially non-collapsible portion (where present). The protrusions may, for example, penetrate part of an elongate object (e.g. the outer jacket of a cable) or they may merely press against the object.

The retention strip is preferably formed from a plastics material, e.g. polyethylene or polypropylene.

The sealing device of the invention may advantageously by used in conjunction with an adaptor which can be inserted into an aperture extending through the device to convert the aperture to two or more smaller apertures, or to convert the aperture to one smaller aperture. This may be advantageous when cables or other elongate objects of relatively smaller diameter need to be sealed by the sealing device. The use of an adaptor can therefore increase the range of cable sizes which the sealing device can seal. The adaptor may be used with or without the retention strip. When the retention strip is used, it is preferably wound around the outside of the adaptor.

The adaptor is preferably compressible, so that one or more gripping members of the sealing device can compress it against one or more elongate objects extending, in use, through the sealing device. More preferably, the adaptor comprises a compressible portion and one or more gripping elements which can engage the compressible portion and which can be pressed, due to the compresion of the compressible portion, against an elongate object extending through the compressible portion to grip the object. Preferably the gripping element(s) can engage the compressible portion such that longitudinal (in the direction of extension of the elongate object(s)) movement of the gripping element(s) with respect to the compressible portion is substantially prevented. Advantageously, a tape can be wound around a cable or other elongate object and one or more gripping elements prior to insertion of the cable into the compressible portion of the adaptor, to fill any gaps between the cable and the compresible portion. It is particularly preferred that the adaptor comprises two compressible end portions and sealing material between the end portions. This particularly preferred embodiment of the adaptor may therefore be placed in the sealing device such that each compressible end part is located in an aperture in an end plate of the sealing device and may be compressed by one or more gripping members, and the sealing material of the adaptor is located between the end plates, e.g. in contact with sealing material of the sealing device retained there. The compressible portion of the adaptor is preferably formed from an elastomeric material, e.g. rubber. The sealing material of the adaptor (where present) may comprise any of the sealing materials described below which may be used as the sealing material of the sealing device. Preferably the sealing material of the adaptor is the same as the sealing material of the sealing device. Although the sealing device of the invention can generally be used for a variety of purposes, its primary use is for sealing a cable splice closure. According to a second aspect of the invention, therefore, there is provided a cable splice closure, comprising:

(a) at least one sealing device according to the first aspect of the invention (which may, for example, have any or all of the preferred features described herein with reference to the first aspect of the invention); and

(b) a housing;

wherein the or each sealing device may be located, in use, in the housing to form a seal between the housing and one or more cables extending into the housing.

The cable splice closure according to the second aspect of the invention may, for example, comprise a butt splice closure, i.e. one in which the cables extend into the closure through only one end thereof. In this case, preferably only one sealing device is provided. Alternatively, the cable splice closure may comprise an in-line splice closure. In this case, preferably two sealing devices are provided, one at each end of the housing. More preferably one or more connecting members, e.g. bars, extend between, and interconnect the sealing devices. The housing is preferably wraparound, e.g. having a longitudinally extending opening which may be closed to close the splice closure or comprising two major parts which are separable in a plain extending substantially coplanar with, or substantially parallel to, an elongate object extending, in use, therethrough. The housing need not be, but preferably is, substantially rigid. The housing is preferably formed from a plastics material, e.g. polyethylene or polypropylene. The sealing device may form a seal between its body portion and the housing by means of the sealing material retained by the sealing device. Additionally or alternatively one or more sealing strip(s) or band(s), especially one or more 'O' ring(s), may be provided around the periphery of the body portion to seal between the body portion and the housing. The sealing strip may, for example, be formed from an elastomeric material, e.g. rubber.

The sealing material of the sealing device according to the invention may comprise any of a variety of sealing materials. For example, it may comprise grease, e.g. a silicone grease, especially one having high viscosity. Additionally or alternatively, the sealing material may comprise mastic. Preferably, however, the sealing material comprises gel (which term includes gelloid materials).

The gel may, for example, comprise silicone gel, urea gel, urethane gel, thermoplastic gel, or any suitable gel or gelloid sealing material. Preferred gels comprise an oil - extended polymer composition. Preferably the gel has a hardness at room temperature as determined using a Stevens- Volland Texture Analyser of greater than 45g, particularly greater than 50g especially greater than 55g, e.g. between 55g and 60g. It preferably has a stress-relaxation of less than 12%, particularly less than 10% and especially less than 8%. Ultimate elongation, also at room temperature, is preferably greater than 100%, more preferably greater than 600%, especially greater than 1000%, particularly greater than 1400%, as determined according to ASTM D638. Tensile modulus at 100% strain is preferably at least 1.8 MPa more preferably at least 2.2 MPa. In general, compression set is preferably less than 35%, especially less than 25%. Preferably, the gel has a cone penetration as measured by ASTM

D217 of at least 50 (10"1 mm), more preferably at least 100 (10^"1 mm), even more preferably at least 200 (10^~1 mm) and preferably no greater than 400 (10"1 mm), especially no greater than 350 (10^"1 mm). The polymer composition of the gel may for example comprise an elastomer, or a block copolymer having relatively hard blocks and relatively elastomeric blocks. Examples of such copolymers include styrene-diene block copolymers, for example styrene-butadiene or styrene-isoprene diblock or triblock copolymers, or styrene- ethylene-butylene-styrene triblock copolymers as disclosed in international patent publication number WO88/00603. Preferably, however, the polymer composition comprises one or more styrene-ethylene-propylene-styrene block copolymers, for example as sold under the Trade Mark 'Septon' by Kuraray of Japan. The extender liquids employed in the gel preferably comprise oils. The oils may be hydrocarbon oils, for example paraffmic or naphthenic oils, synthectic oils for example polybutene or polypropene oils, and mixtures thereof. The preferred oils are mixtures of non- aromatic paraffins and naphthenic hydrocarbon oils. The gel may contain additives, e.g. such as moisture scavengers (eg. BenzoyI chloride), antioxidants, pigments and fungicides.

The body portion of the sealing device is preferably substantially rigid. Preferred materials for the body portion include metals and plastics materials, e.g. polyethylene or polypropylene.

The invention will now be described, by way of example, with reference to the accompanying drawings, of which:

Figure 1 shows two sealing devices according to the invention arranged as for an in-line splice closure, i.e. spaced apart from each other and connected together by two elongate connecting members;

Figure 2 shows half of a sealing device according to the invention; Figure 3 shows two views of half of another form of sealing device according to the invention;

Figure 4 shows another view of the sealing device half, shown in Figure 2;

Figure 5 shows, in cross-section, an assembled cable splice closure according to the invention;

Figure 6 shows one of the sealing devices of the closure shown in Figure 5 in cross-section A-A;

Figure 7 shows the sealing device of Figure 6 in cross-section B-B;

Figures 8a and 8b show schematic representations of two forms of sealing device according to the invention;

Figures 9 to 1 1 show three forms of retention strip according to the invention;

Figures 12a and 12b show gripping elements of an adaptor according to the invention;

Figures 13a and 13b show adaptors according to the invention; and Figure 14 shows, schematically how an adaptor fits into a sealing device according to the invention.

Figure 1 shows two sealing devices 1 according to the invention arranged for an in-line cable splice closure, i.e. spaced apart from each other and arranged in line, but connected together by means of two elongate connecting members 3, in the form of bars, extending between them at their peripheries. Each sealing device 1 is hollow and comprises first and second spaced apart end plates 5 and a peripheral, i.e. circumferential, wall 7 extending between the end plates. The wall 7 substantially encloses the space between the end plates, thereby providing a cavity 9 in which, at least in use, sealing material, e.g. gel, (not shown), may be retained. Each sealing device 1 has two cable entry apertures extending through it.

Each sealing device 1 , has channels 1 1 located in its first and second end plates 5, in each of which a gripping member (not shown) is located in use. The bottom left hand sealing device 1 as drawn shows two of these channels in dotted outline, and also shows arrows illustrating the direction in which the gripping members are moved in order to grip a cable, namely substantially perpendicular to the cable. Each channel 1 1 has a relatively wide part 13 to accommodate a gripping part of the gripping member and a relatively narrow part 15 to accommodate a threaded shaft of the gripping member. The narrow part 15 of the channel extends to the periphery of the sealing device so that the shaft may be screwed, from the exterior of the device, further into the sealing device so as to push the gripping part of the gripping member against a cable extending through the sealing device.

Each sealing device 1 comprises two major parts (half pieces as shown) which are separable in a plain extending substantially coplanar with the cables which extend, in use. through the device. The half pieces are bolted together at points 17. Figures 2 to 4 show a variety of views of two different, but similar, sealing device half pieces: figures 2 and 4 show two views of one form of sealing device and figures 3a and 3b show two views of another, more preferred, form of sealing device. Each half piece is bolted to its mating half piece through holes 17. End plates 5, peripheral walls 7, cavities 9, and channels 11 (and narrow parts 15) are shown. The periphery of each half piece has a substantially semi -circular channel or groove 19 (which forms a substantially circular channel or groove in the assembled sealing device) for an O-ring seal. The O-ring (which may for example be formed from an elastomeric material, especially rubber) forms a seal between the sealing device and the housing of the splice closure. Each of the half pieces have windows (i.e. gaps) 21 communicating between the cavity 9 and the channel 19, through which, in use, extends sealing material from the cavity. These windows generally have a dual function: firstly they enable the sealing material to form a seal which substantially blocks longitudinal passage of fluid (e.g. moisture or gas) between mating faces 23 of each half piece; secondly they enable the sealing material to contact the sealing O-ring, thereby forming a good seal at each so-called triple point, i.e. where the longitudinal seal for the sealing device (provided by the sealing material in the window) meets the circumferential seal for the sealing device (provided by the O-ring).

The sealing device half pieces of figures 2 to 4 are shown without their respective pressure members which, in use, are moved towards the cables to urge the sealing material (also not shown) against the cables. However, passageways 25 communicating between the cavity of each device and the exterior of the device are shown. Each passageway accommodates, in use, a threaded shaft connected to the pressure member for screwing the pressure member towards the cables.

The cavity of the sealing device of Figure 3b has a region 27 of alternating ridges and grooves adjacent to one of its end plates. These ridges and grooves increase the path length along which any moisture ingressed between the body portion of the sealing device and the sealing material would have to travel in order to pass through the sealing device and into the splice closure. They therefore provide an extra barrier against ingress of moisture.

Figure 5 shows, in cross-section, an assembled in-line cable splice closure according to the invention. The closure comprises two sealing devices 1, each located at an end of a substantially cylindrical housing 29. Connecting bars 3 extend between and interconnect the two sealing devices. In this embodiment, each sealing device has bolts 31 which join the two half pieces of each sealing device together. Pairs of gripping members 33 are located in the end plates of each sealing device, and wound spirally between the gripping members of each pair, in a cable entry aperture, is a retention strip 34 (described in detail with reference to figures 9 to 11). Each sealing device also has a pressure member 35 located in its central cavity. Each pressure member has a resilient member in the form of a helical spring 51 mounted on a shaft 47 thereof, to bias the pressure member against the sealing material.

The housing 29 is wraparound and has a longitudinally extending opening provided with a longitudinal seal 37, which contacts O-rings 39 located around the sealing devices. The housing 29 is preferably closed by means of closing members 40 which have wedge-shaped channels which are slid onto wedge-shaped rails (not shown) on the outside of the housing. Any other suitable way of closing the housing could, of course, be used.

Figure 6 shows one of the sealing devices of the splice closure shown in Figure 5, in cross-section A-A. This cross-section illustrates the gripping members 33 of the sealing device, movably located in channels 1 1. Each gripping member 33 has an arcuate gripping surface 41 provided with gripping protrusions 43. The main, i.e. side, portion of each gripping member 33 preferably acts as a dam for sealing material located in the sealing device. Figure 7 shows the sealing device of Figure 6 in cross-section B-B. This cross-section illustrates the pressure member 35 comprising two pressure parts 45 mounted on a shaft 47 extending between the two sealing device half pieces. Tightening the nut 49 on the shaft 47 forces the two pressure parts 45 towards each other and consequently, in use, towards the cables extending into the closure. The shaft 47 has a helical spring 51 located on it, to bias the pressure parts 45 towards each other.

Figures 8a and 8b illustrate, schematically, the mechanism of a pressure member in relation to two different sealing material arrangements. In both arrangements, the sealing material preferably comprises gel, and the pressure member comprises a pressure part 53 mounted on a shaft 55 which extends between the sealing device half pieces. A helical spring 57 is located on the shaft 55 to bias the pressure part 53 towards the sealing material and the cables 59. In Figure 8a, some sealing material 61 (e.g. gel) is located on a pressure surface of the pressure member (ie the surface facing the cables); there is also some additional sealing material 63 (e.g. gel, which is preferably, although not necessarily, the same as gel 61) located around each cable 59. This latter sealing material 63 preferably comprises a strip or tape, most preferably of gel, which has been wound around its respective cable prior to inserting the cable into the sealing device. Figure 8b shows an alternative arrangement in which substantially all of the sealing material 63 in the cavity is in the form of tapes or strips, preferably of gel, wound around the cables.

Figures 9, 10 and 11 each show a different design of retention strip according to the invention. In preferred embodiments of the invention, a retention strip is wound around a cable prior to moving the gripping members towards the cable, in order to increase the effective diameter of the cable to be closer to that of an aperture in the sealing device.

Figures 9a and 9b show opposite sides of a first design of retention strip. The strip comprises a plurality of alternately collapsible and non-collapsible portions along at least part of its length: only one collapsible portion 63 and one non-collapsible portion 65 are shown in these figures. The collapsible portion 63 comprises two webs 67 extending between two non-collapsible portions at the edges of the strip. The webs 67 can deform, e.g. by buckling, concertinaing or by being crushed, preferably outwardly and/or inwardly with respect to the rest of the strip in the direction of the arrows. This deformation is therefore preferably in a direction generally or substantially parallel to the axial direction of extension of a cable etc. around which the strip is wound in use, such that substantially no gaps are formed between adjacent windings of the strip through which sealing material might be able to escape.

The strip of figures 9a and 9b has protrusions 69 and recesses 71 which can engage corresponding recesses 71 and protrusions 69 of adjacent windings when, in use, the strip is wound around a cable etc. As mentioned above, this has the advantage of substantially preventing accidental axial displacement of the windings of the strip with respect to each other. Some of the protrusions may advantageously help the retention strip to grip a cable around which it is wound. Also, the protrusions and recesses of the strip may engage the gripping members of the sealing device, e.g. they may interlock with gripping protrusions on the gripping members.

The retention strips shown in figures 10 and 11 are similar to that shown in Figure 9, except that the designs of the recesses and protrusions are different. Figures 10a and 10b show opposite sides of one design of strip, and figures 1 la and l ib show opposite sides of another design of strip. Each of these strips, however, has alternately collapsible portions 63 and non-collapsible portions 65. Both designs of strip illustrated in figures 10 and 11 have a tapered non-collapsible portion 73 which is intended to be located at the end of the strip (the strip of Figure 10 may be severed at the dotted line) to smooth either the inner or the outer end of the strip when wound. Figure 1 lb shows a plurality of gripping protrusions 75 on one side of the strip for gripping a cable etc.

Figures 12 to 14 show features of an adaptor according to the invention. Figure 12a shows a gripping element 77 of an adaptor, comprising an arcuate gripping portion 79 having gripping protrusions 81 on its gripping surface, to aid in the gripping of a cable, and two lateral extensions 83 extending substantially perpendicular to the gripping portion, one extension at each end of the gripping portion. The lateral extensions are for engaging a compressible end part of an adaptor, as shown in Figure 13b. Figure 12b shows, schematically two gripping elements 77 positioned on a cable 85, with a tape 87 wrapped around the cable and both gripping elements.

Figure 13a shows an adaptor, comprising two compressible end parts 89 and sealing material 91 (e.g. gel) located between the end parts. Two joining arms 93, preferably formed from the same material as the end parts, extend through the sealing material and interconnect the end parts. Each end part has two apertures 94 for cables or the like, and there is a slit 95 extending from each aperture to the exterior of the adaptor to permit side-entry of a cable etc. into the adaptor. The cables may either simply be pushed through the sealing material 91, or the sealing material may also be provided with slits for receiving cables.

A cable 85 having a tape 87 wound around it and one or more (e.g. two as shown) gripping elements 77 can preferably be inserted into the adaptor by opening up the slits 95, pushing the cable, tape and gripping elements into an aperture 94 and arranging the lateral extensions 83 of the gripping elements so that they extend along opposite end faces 97 of a compressible end p art of the sealing member as illustrated in Figure 13b. In this way the gripping elements are engaged with the adaptor such that longitudinal movement of the gripping elements 77 with respect to the adaptor is substantially prevented. Transverse compression of the compressible end parts 89, for example in the direction of the arrows, causes the gripping elements to be pressed against the cable 85 and thereby grip the cable. This transverse compression is preferably performed by means of the gripping members of a sealing device of the invention.

Figure 14 shows, schematically, how an adaptor is positioned inside an aperture in the sealing device 1 of the invention, thereby converting the aperture to one or more (e.g. two as shown) smaller apertures.

Claims

1. A sealing device for forming a seal between an elongate object and a hollow article, the sealing device comprising:

(a) a body portion;

(b) at least one gripping member; and

(c) at least in use, sealing material;

wherein, in use, the or each gripping member (i) can be moved relative to the body portion to grip an elongate object extending through the sealing device and (ii) at least partly retains the sealing material.

2. A sealing device according to claim 1 , in which the body portion comprises first and second spaced apart end plates, between which, at least in use, the sealing material is retained.

3. A sealing device according to claim 1 or claim 2, in which the or each gripping member is movably attached to the body portion.

4. A sealing device according to claim 3 when dependent on claim 2, in which the or each gripping member is movably attached to an end plate thereof.

5. A sealing device according to claim 4, in which the or each gripping member is located at least partly within an end plate thereof.

6. A sealing device according to any one of claims 2 to 5, in which the first and second end plates have one or more apertures to allow one or more elongate objects to extend therethrough.

7. A sealing device according to claim 6, in which the or each gripping member is located, in use, at least partly within an aperture of an end plate thereof.

8. A sealing device according to any preceding claim, in which the or each gripping member is operable by hand externally of the sealing device.

9. A sealing device according to any preceding claim, in which the or each gripping member has a generally arcuate gripping surface.

10. A sealing device according to any preceding claim, in which the movement of the or each gripping member relative to the body portion is in a direction transverse, preferably substantially perpendicular, to the direction in which an elongate object extends, in use, through the sealing device.

1 1. A sealing device according to any preceding claim, in which the body portion comprises two major parts which are separable in a plain in which, or substantially parallel to which, an elongate object extending, in use, through the sealing device extends.

12. A sealing device according to any one of claims 2 to 1 1, in which a wall extends between the first and second end plates, which wall substantially encloses at least part of the space between the end plates, thereby providing a cavity in which the sealing material may be retained, at least in use.

13. A sealing device according to any preceding claim, which further comprises a pressure member which can be moved, in use, towards an elongate object extending through the device, to urge the sealing material against the elongate object.

14. A sealing device according to claim 13 when dependent on claim 12, in which the pressure member is located within, and movable relative to, the cavity.

15. A sealing device according to any preceding claim, in which the sealing material comprises gel.

16. A cable splice closure, comprising:

(a) at least one sealing device according to any preceding claim; and

(b) a housing;