APPARATUS FOR ENCLOSING PART OF AN ELONGATE OBJECT

Abstract: Apparatus for enclosing part of an elongate object (31), comprising: (a) a casing (19, 21) to enclose part of the elongate object (31); (b) a sealing member (1) comprising sealing material to form a seal between the casing (19, 21) and the elongate object (31); and (c) a compression member (25) to compress the sealing member (1) in longitudinal direction with respect to the elongate object (31) thereby causing at least some of the sealing material to be displaced in a lateral direction with respect to the elongate object (31) to form the seal; wherein, in use, the longitudinal compression of the sealing member is caused by moving the sealing member and/or the compression member (25) relative to the casing (19, 21) in a lateral direction with respect to the elongate object (31).

Description: Apparatus for enclosing part of an elongate object The present invention relates to apparatus and a method for enclosing part of an elongate object. The apparatus may be a cable splice closure or other cable closure, the elongate object comprising a cable. Alternatively the apparatus may be a duct seal for attaching to, and sealing, an end of a duct, the elongate object preferably comprising a cable or a pipe. By a cable is meant a telecommunications cable (either conductive or optical fibre), an electrical cable or other conductive cable, a wire or an optical fibre. There are many different types of cable splice closures, duct seals, and other apparatus for enclosing cables or pipes. Some of these apparatus have sealing members which form a seal between a casing and an elongate object extending into the casing by being compressed longitudinally (with respect to the elongate object) by means of longitudinal bolts or the like, which forces some of the sealing member to be displaced laterally into sealing engagement with the elongate object and the interior of the casing. For example, International patent application WO 90/05401 (Raychem) discloses a closure assembly having a cable seal formed from a substantially rigid portion and a sealing material, for example gel, retained by the rigid portion. The rigid portion comprises two end parts that can be moved towards one another thereby providing a compressive force on the sealing material. The two end parts may be moved towards one another by means of a bolt, or two or more bolts, extending through the end parts and the sealing material. A spring or other resilient member may be provided (e.g. on the bolt(s)) to maintain the sealing material under compression. International patent application WO 92/221 14 (Raychem) discloses a sealing device which is similar to that of WO 90/05401 but which has the inventive feature of stop means for limiting the biasing ofthe resilient member at a configuration in which the biasing can be increased by movement ofthe sealing material. This has the advantage that the installer can tighten the resilient member until he feels a stop, knowing that the correct degree of tightening has been applied. Displacement of sealing material will subsequently be able to be accommodated, e.g. due to the material creeping away under the applied bias, or due to the material expanding because of an increase in temperature. These seals perform extremely well, but it would be desirable to have a seal which could function equally well but which would be cheaper to manufacture and as simple, or simpler, to install. A purpose ofthe present invention is to provide apparatus having such a seal. According to the present invention, there is provided apparatus for enclosing part of an elongate object, comprising: (a) a casing to enclose part ofthe elongate object: (b) a sealing member comprising sealing material to form a seal between the casing and the elongate object; and (c) a compression member to compress the sealing member in a longitudinal direction with respect to the elongate object thereby causing at least some ofthe sealing material to be displaced in a lateral direction with respect to the elongate object to form the seal; wherein, in use, the longitudinal compression ofthe sealing member is caused by moving the sealing member and/or the compression member relative to the casing, preferably into the casing, in a lateral direction with respect to the elongate object. According to a second aspect ofthe invention, there is provided a method of enclosing part of an elongate object, comprising: (a) inserting the elongate object into a sealing member comprising sealing material, and inserting the sealing member and the elongate object into a casing to enclose part ofthe elongate object; and (b) moving the sealing member and/or a compression member relative to the casing, preferably into the casing, in a lateral direction with respect to the elongate object, thereby compressing the sealing member in a longitudinal direction with respect to the elongate object and consequently causing at least some of the sealing material to be displaced in a lateral direction with respect to the elongate object, thereby forming a seal between the casing and the elongate object. Preferably step (b) is performed after step (a). The apparatus and method according to the invention have the advantage that because the longitudinal compression ofthe sealing member is caused by moving the sealing member and/or the compression member relative to the casing in a lateral direction with respect to the elongate object, a simple method is provided, and a simple, and preferably inexpensive, design of apparatus is possible, as will be seen from the following description and drawings. The sealing member is preferably compressed, in use, between the compression member and part ofthe casing. The lateral movement ofthe compression member (in embodiments in which the compression member is so moved) may advantageously comprise inserting the compression member between the sealing member and part of the casing or another part ofthe apparatus which is preferably fixed (at least in the longitudinal direction) with respect to the casing. Additionally or alternatively, in embodiments in which the sealing member is moved in a lateral direction with respect to the elongate object, such lateral movement ofthe sealing member may advantageously comprise inserting the sealing member between the compression member and part ofthe casing or another part ofthe apparatus which is preferably fixed (at least in the longitudinal direction) with respect to the casing. In each case, the other part ofthe apparatus may advantageously comprise a fastening device to fasten the elongate object with respect to the casing. The lateral movement ofthe sealing member and/or the compression member relative to the casing preferably comprises slotting the member(s) into one or more slots in the casing or between other parts ofthe apparatus. The casing may, for example, have internal ribs, flanges or other projections between which the sealing member and/or the compression member may be slotted. The slot(s) may, however, be between part ofthe casing and another part ofthe apparatus (e.g. a fastening device for fastening the elongate object to the casing), or may be between two or more other parts ofthe apparatus. For example, the compression member may be slotted between the sealing member and a fastening device, or the sealing member may be slotted between the compression member and a fastening device. Inserting, e.g. slotting, the sealing member and/or the compression member into the casing is normally a very simple and quick way of applying the longitudinal compression to the sealing material and thus of forming the desired seal. It normally avoids having to tighten one or more bolts in order to achieve such compression, as is necessary with the known sealing systems, and this is advantageous because tightening the bolts can, in unfavourable circumstances, e.g. where access is restricted, be time-consuming and difficult. It is particularly preferred that the compression member have a generally flat shape, i.e. a shape which lies generally in a plane. (The compression member may, however, be generally wedge-shaped.) Preferably, the plane ofthe compression member is oriented transversely, more preferably substantially perpendicularly, with respect to the elongate object. One advantage of this is that it normally provides a compact design. The compression member is preferably resilient, at least such that, in use, it applies biased compression to the sealing member. This has the advantage that changes in the volume ofthe sealing material (e.g. due to changes in temperature) and/or creep, exudation etc. ofthe sealing material are normally automatically accommodated by the compression member due to its resilience while maintaining the compression on the sealing material. Put simply, due to the resilience ofthe compression member, it preferably automatically expands or contracts as appropriate in the relevant direction in response to expansion, contraction or loss of sealing material, and thus maintains its compression on the sealing material. The compression member preferably comprises a spring, e.g. a leaf spring or a spring made from metal wire. A particularly preferred form of compression member is formed (e.g. from metal wire) in a generally flat. i.e. generally planar, shape, but which has one or more resilient parts lying out ofthe plane, which apply the resilient compression to the sealing member. The compression member may advantageously be inserted, e.g. slotted, next to the sealing member (or vice versa) such that the resilient part(s) lying out ofthe plane ofthe compression member compress the sealing member. Instead ofthe compression member being a separate part of the apparatus which may be inserted into the casing separately from the other components, it may, in some embodiments ofthe invention, be an integral part ofthe casing and/or ofthe sealing member. By this is meant that the compression member may be integrally formed with the casing or the sealing member or it may be attached to the casing or the sealing member such that the casing and the compression member, or the sealing member and the compression member, together comprise a single component ofthe apparatus. The casing (which is preferably formed from a plastics material) preferably comprises a base and a cover which may be brought together to close the casing. Advantageously, bringing the base and the cover together, in use, may cause, or at least finalise, the lateral movement ofthe sealing member and/or the compression member relative to the base or the cover ofthe casing. For example, the sealing member and/or the compression member may be inserted partially into the casing (e.g. into the base ofthe casing) and the subsequent closing ofthe casing by fastening together the base and the cover may cause further lateral movement ofthe sealing member and/or the compression member into the final working position. The sealing member preferably includes at least one plate or the like next to the sealing material, which, in use, is forced by the compression member against the sealing material, thus applying compression to it. More preferably, the sealing member comprises at least two plates (preferably only two plates) between which is the sealing material, the longitudinal compression ofthe sealing member in use causing the plates to be forced towards each other, or causing one ofthe plates to be forced towards the other plate, thereby applying the compression to the sealing material and causing its lateral displacement. The or each plate may be substantially rigid or may be flexible, e.g. resiliently flexible. The plate(s) may. for example, be formed from a plastics material, e.g. polypropylene, or an elastomeric material e.g. natural or synthetic rubber. Although the apparatus ofthe invention has been described as enclosing part of an elongate object, it is to be understood that this includes enclosing two or more elongate objects. The sealing member can therefore, form a seal around one, and preferably two or more, elongate objects. To this end, the sealing member has, at least in use, one or more ports (i.e. apertures) through which the elongate object(s) extend. When a port is not in use, it is preferably blocked off, e.g. by a plug. Alternatively, the ports may be provided only as and when needed, e.g. by cutting away, or otherwise removing, parts ofthe sealing member. The sealing material may generally comprise any suitable sealing material. A particularly preferred sealing material is gel. 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%, more preferably less than 25%, especially less than 15%. Preferably, the gel has a cone penetration as measured by ASTM D217 of at least 50 (lO 'mm), more preferably at least 100 (lO 'mm), even more preferably at least 200 (10 " 'mm) and preferably no greater than 400 (lO 'mm), especially no greater than 350 (10 " 'mm). The polymer composition ofthe 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 e.g. as disclosed in international patent publication number WO 88/00603. 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 paraffinic or napthenic oils, synthetic 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 (e.g. Benzoyl chloride), antioxidants, pigments and fungicides. Other sealing materials which can be used include polymeric (e.g. silicone) foam materials, elastomeric materials, e.g. natural or synthetic rubber, mastics, or greases, e.g. silicone grease. The invention will now be described, by way of example, with reference to the accompanying drawings, of which: Figure 1 shows a sealing member of an apparatus according to the invention; Figure 2 shows a fastening device of an apparatus according to the invention; Figure 3 shows a casing of an apparatus according to the invention; Figure 4 shows an apparatus according to the invention being closed around some cables; Figure 5 shows a sealing member, compression member, and fastening device of an apparatus according to the invention; Figure 6 shows another sealing member, compression member, and fastening device of an apparatus according to the invention. Figure 1 (a and b) shows a sealing member 1 of an apparatus according to the invention, comprising two plates 3 between which is the sealing material 5 ofthe sealing member. In use, the plates 3 are forced relatively closer together (e.g. by moving one plate towards the other plate), thereby causing some ofthe sealing material to be displaced laterally into sealing contact with the interior of a surrounding casing (not shown) and with cables or other elongate objects extending through ports or apertures 7 extending through the sealing member. The sealing member 1 is split into three separate parts, as shown in Figure lb, to permit side-entry ofthe cables or other elongate objects into the apertures 7. Figure 2 (a and b) shows a fastening device 9 of an apparatus according to the invention, for fastening cables or other elongate objects with respect to a casing. The fastening device 9 has apertures 11 extending through it, which correspond to the apertures 7 in the sealing member. In use, a bolt, screw, or the like extends through hole 13, and the separate parts 15 of the device may thus be tightened around the elongate objects extending through the apertures 1 1. Figure 3 shows a casing 17 of an apparatus according to the invention, comprising a base 19 and a cover 21 which may be brought together to close the casing. The base 19 ofthe casing has slots 23 at each end. for slotting sealing members and fastening devices into it. Figure 4 illustrates schematically an apparatus according to the invention in the form of a cable splice closure, comprising the sealing member 1 , the fastening device 9, the casing 17 of figures 1 to 3 respectively, and further comprising a compression member 25 and an o-ring seal 27 (for forming a seal between the base 19 and the cover 21 ofthe casing 17). Figure 4a shows the compression member 25 being inserted into the casing 17 between the sealing member 1 and the fastening device 9. The compression member 25 is generally flat but has resilient parts 29 which extend out ofthe plane ofthe rest ofthe member. The compression member is advantageously formed from metal, e.g. metal wire. The insertion of the compression member 25 between the sealing member 1 and the fastening device 9 presses the resilient parts 29 ofthe compression member against the sealing member, and because the fastening device is fixed to the casing so that it can not move, the sealing member is compressed. The compression ofthe sealing member causes its plates to become closer together, thereby displacing some ofthe sealing material laterally. The direction of insertion ofthe compression member 25 is substantially peφendicular to the direction in which the cables 31 extend into the casing. Figures 5 and 6 each show a sealing member 1, a compression member 25, and a fastening device 9 in greater detail. Those shown in Figure 5 are for receiving a single cable 31 , whereas those shown in Figure 6 are for receiving up to four cables 31 , and accordingly the sealing members and fastening devices have the appropriate number of cable-entry apertures. The apertures in the sealing member 1 shown in Figure 6 each have a series of concentric removal portions 33 which may be selectively removed, e.g. by cutting, depending on the diameters ofthe cables. Other than this feature, the sealing members 1 and the fastening devices 9 are substantially the same as those shown in figures 1 and 2 respectively. Bolts 35 which fasten together the separate parts 15 ofthe fastening devices around the cables 31, are illustrated. The compression members 25 each comprise a single piece of metal wire bent so as to form three sides of a square, and having kinks 29 bent out ofthe plane of the square to press against the sealing member 1 , thereby forcing the nearer plate 3 closer to the further plate and thus displacing some of the sealing material in a lateral direction.

Claims: Claims 1. Apparatus for enclosing part of an elongate object, comprising: (a) a casing to enclose part ofthe elongate object; (b) a sealing member comprising sealing material to form a seal between the casing and the elongate object; and (c) a compression member to compress the sealing member in a longitudinal direction with respect to the elongate object thereby causing at least some ofthe sealing material to be displaced in a lateral direction with respect to the elongate object to form the seal; wherein, in use, the longitudinal compression ofthe sealing member is caused by moving the sealing member and/or the compression member relative to the casing in a lateral direction with respect to the elongate object. 2. Apparatus according to claim 1, in which, in use, the sealing member is compressed between the compression member and part of the casing. 3. Apparatus according to claim 1 or claim 2, in which the lateral movement of the compression member comprises inserting the compression member between the sealing member and part ofthe casing or another part of the apparatus which is fixed with respect to the casing. 4. Apparatus according to any preceding claim, in which the lateral movement of the sealing member comprises inserting the sealing member between the compression member and part ofthe casing or another part ofthe apparatus which is fixed with respect to the casing. 5. Apparatus according to claim 3 or claim 4, in which the other part ofthe apparatus comprises a fastening device to fasten the elongate object with respect to the casing. 6. Apparatus according to any preceding claim, in which the compression member has a shape which lies generally in a plane, wherein, in use, its plane is oriented transversely, preferably substantially peφendicularly, with respect to the elongate object. 7. Apparatus according to any preceding claim, in which the lateral movement of the sealing member and/or the compression member relative to the casing comprises slotting the member(s) into one or more slot(s) in the casing or between other parts of the apparatus. 8. Apparatus according to any preceding claim, in which the compression member is resilient, preferably comprising a spring. 9. Apparatus according to any preceding claim, in which the compression member is an integral part ofthe casing and/or the sealing member. 10. Apparatus according to any preceding claim, in which the casing comprises a base and a cover which may be brought together to close the casing, and bringing the base and the cover together in use preferably causes the lateral movement ofthe sealing member and/or the compression member relative to the base or the cover of the casing. 11. Apparatus according to any preceding claim, in which the sealing member comprises at least two plates between which is the sealing material, the longitudinal compression ofthe sealing member in use causing the plates to be forced towards each other. 12. Apparatus according to any preceding claim, which comprises a cable splice closure, the elongate object comprising a spliced cable. 13. Apparatus according to any one of claims 1 to 1 1 , which comprises a duct seal for attaching to, and sealing, an end ofa duct, the elongate object preferably comprising a cable or a pipe. 14. A method of enclosing part of an elongate object, comprising: (a) inserting the elongate object into a sealing member comprising sealing material, and inserting the sealing member and the elongate object into a casing to enclose part ofthe elongate object; and (b) moving the sealing member and/or a compression member relative to the casing in a lateral direction with respect to the elongate object, thereby compressing the sealing member in a longitudinal direction with respect to the elongate object and consequently causing at least some ofthe sealing material to be displaced in a lateral direction with respect to the elongate object, thereby forming a seal between the casing and the elongate object. 15. A method according to claim 14 carried out by apparatus according to any one of claims 1 to 13.

Inventors: DAMM JESPER, DAMM, JESPER
Applicants: DAMM JESPER, RAYCHEM LTD, RAYCHEM SA NV, DAMM, JESPER, N.V. RAYCHEM S.A., RAYCHEM LIMITED
Application year: 1996
Main classification: H02G15
IPC codes: H02G15