Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
  • H02G15/00—Cable fittings
  • H02G15/013—Sealing means for cable inlets
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
  • H02G15/00—Cable fittings
  • H02G15/007—Devices for relieving mechanical stress
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02G—INSTALLATION OF ELECTRIC CABLES OR LINES, OR OF COMBINED OPTICAL AND ELECTRIC CABLES OR LINES
  • H02G15/00—Cable fittings
  • H02G15/08—Cable junctions
  • H02G15/10—Cable junctions protected by boxes, e.g. by distribution, connection or junction boxes
  • H02G15/117—Cable junctions protected by boxes, e.g. by distribution, connection or junction boxes for multiconductor cables

Definitions

• the present invention relates to cable sealing apparatus and to a method of sealing a cable, and particularly to apparatus for sealing a splice between cables and a method of sealing a splice between cables, for example telecommunications cables.
• Cable splices generally need to be sealed from the environment, and particularly from moisture, in order for them to retain their signal integrity or electrical integrity.
• a variety of ways of sealing cable splices and preventing strain on the sealed splice have been proposed. For example, 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.
• 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.
• Another cable splice assembly which is disclosed in US Patent No. 5124507 comprises 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.
• 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.
• the apparatus can advantageously provide a simple and effective cable sealing compressible sealing member for insertion in a larger sealing device to convert a cable entry aperture of the sealing device to one or more smaller cable entry apertures, thereby increasing the range of sizes of cable that the sealing device can accommodate.
• cable sealing apparatus comprising:
• transverse compression of the sealing member can press the or each gripping member against a cable extending longitudinally through the sealing member, thereby gripping the cable.
• Such transverse compression is preferably in a direction substantially perpendicular to the direction in which the or each cable extends through the sealing member, in use.
• each cable that is sealed by the apparatus is normally secured to the apparatus against longitudinal forces acting on the cable (often referred to as 'axial pull strength'), and is also secured with respect to any other cables which are sealed by the apparatus, by means of the gripping member(s).
• the invention has the advantage that, because transverse compression of the sealing member can press the or each gripping member against a cable thereby gripping the cable, the sealing of the cable (by the sealing member) and the securement of the cable with respect to the apparatus and with respect to any other cables sealed by the apparatus (by the gripping member(s)) are generally carried out in one operation (transverse compression of the sealing member), in contrast with many prior art systems (of which US 4933512 discloses an example) in which the sealing of the cables and the securement of the cables are carried out in separate operations. Because the present invention allows both cable sealing and cable securement to be carried out in the same operation, it can simplify the installation of cable sealing apparatus in the field.
• the cable sealing apparatus further comprises compressing means to compress the sealing member transversely.
• the, or at least one of the, gripping member(s) is located, in use, in a cable aperture of the sealing member. In this way, the gripping member(s) may be pressed against a cable between the cable and the compressible sealing member.
• The, or at least one of the, gripping member(s) may advantageously be substantially rigid. This is preferred, at least in part because it generally enables a firm grip to be applied to the cables, despite the sealing member surrounding the cables being compressible. If, instead, a flexible gripping member is used, such a firm grip may not, in some circumstances, be achievable.
• at least a portion of the, or at least one of the, gripping member(s) is generally arcuate in shape, to conform generally to a cable extending, in use, through the sealing member.
• The, or at least one of the, gripping member(s) preferably has one or more gripping protrusions on a surface thereof.
• the gripping protrusions generally aid the gripping of the cable by the gripping member(s).
• the protrusions may, for example, penetrate the jacket of a cable, or they may merely press against the cable jacket.
• the or each gripping member can engage the sealing member in any of a variety of different ways, for example by means of one or more protrusions and/or recesses interlocking with one or more recesses and/or protrusions.
• the, or at least one of the, gripping member(s) can engage the sealing member by means of one or more lateral protrusions (extensions) which can extend into one or more recesses and/or which can extend along one or more end faces of the sealing member. More preferably, the or each gripping member has two or more lateral extensions which can extend, in use, along opposite end faces of the sealing member at each end of a cable aperture of the sealing member. This has the advantage of providing a simple way of engaging the gripping member(s) with the sealing member such that longitudinal movement (i.e. generally in the direction of extension of the cable(s) through the sealing member) of the gripping member(s) is substantially prevented.
• this embodiment of the invention may allow some transverse movement of the gripping member(s) with respect to the sealing member (e.g. substantially radial movement with respect to the cable(s) extending through the sealing member) while substantially preventing longitudinal movement.
• This has the advantage of allowing the gripping member(s) to engage the sealing member prior to compression of the sealing member, and allowing the sealing member subsequently to be compressed against the gripping member(s) to press the gripping member(s) against the cable(s).
• the cable sealing apparatus may advantageously further comprise a tape which can be wound, preferably spirally, around a cable and one or more gripping members prior to insertion of the cable into a cable aperture of the sealing member.
• any gaps between the cable and the sealing member in the cable aperture may, for example, be filled, or at least the effective diameter of the cable may be built up so that it is closer in size to the internal diameter of the cable aperture.
• This has the advantage of generally enabling one size of cable aperture in the compressible sealing member to accommodate a range of sizes of cable, thereby reducing the number of different sealing members that need to be supplied in order to accommodate the entire range of cable sizes which need to be sealed.
• the cable gripping apparatus comprises part of the cable sealing apparatus according to the first aspect of the invention.
• a gripping member for gripping a cable comprising a gripping portion to grip a cable and which, in use, lies in contact with the cable, and at least two lateral extensions which extend laterally from the gripping portion and which are spaced apart from each other such that, in use, they are spaced apart longitudinally along the cable.
• the space between the lateral extensions permits a tape to be spirally wound around the gripping member and a cable between the lateral extensions.
• the lateral extensions preferably substantially prevent helical extension of the tape spiral, e.g. as explained below.
• the gripping members of the apparatus may advantageously substantially prevent longitudinal movement of the tape with respect to the sealing member. This is often important due to the fact that the tape is normally located between the or each gripping member and the sealing member, and consequently any longitudinal movement of the tape relative to the sealing member might reduce or even destroy the grip of the gripping member(s) on the cable.
• the two or more lateral extensions (where present) of the sealing member which can extend along opposite end faces of the sealing member at each end of a cable aperture, substantially trap the wound cable in the cable aperture, between the inside of the sealing member and the gripping member(s).
• the tape is preferably spirally wound around a cable and one or more of the gripping members between two of the lateral extensions of the or each gripping member, thereby substantially preventing helical extension of the tape spiral.
• the compressible sealing member comprises two compressible longitudinally spaced end parts and sealing material located between the end parts, the or each cable aperture preferably extending through both end parts.
• This has the advantage of providing cable securement ('axial pull strength') with even greater environmental sealing.
• the compressible end parts of the sealing member may provide longitudinal containment of the sealing material either alone or, for example, in combination with the gripping member(s) and/or the tape (where present).
• the end parts of the sealing member are joined, for example by means of one or more joining arms, which may extend through the sealing material, and/or which may be formed from the same material as the end parts themselves.
• the opposite end faces of the sealing member referred to above preferably comprise opposite end faces of a compressible end part of the sealing member.
• these extensions can preferably extend, in use, along opposite end faces of a compressible end part of the sealing member at each end of a cable aperture extending through the end part.
• each end part of the sealing member has one or more gripping members located, in use, in a cable aperture extending through the end part.
• the sealing member is wraparound.
• 'wraparound' is meant that the sealing member is open in cross-section so that it may be positioned around the or each cable without having to slide the sealing member onto the ends of the cable(s).
• the sealing member may, for example, be hinged.
• the sealing member may have a gap, e.g. a slit, extending along the length of the or each cable aperture and extending between the aperture and the exterior of the sealing member to allow one or more cables to be inserted into the aperture through the gap.
• the sealing member is sufficiently deformable that the gap may be opened to allow a cable to be inserted into the aperture simply by deformation of the sealing member.
• the compressible sealing member may advantageously be formed from elastomeric material, e.g. a silicone rubber, a nitrile rubber, ethylene/propylene rubbers or natural rubber. Additionally or alternatively, the tape, (where present) may beneficially be formed from elastomeric material, e.g. any of the elastomeric materials from which the sealing member may be formed.
• elastomeric material e.g. a silicone rubber, a nitrile rubber, ethylene/propylene rubbers or natural rubber.
• the tape, (where present) may beneficially be formed from elastomeric material, e.g. any of the elastomeric materials from which the sealing member may be formed.
• the cable sealing apparatus of the invention preferably further comprises a sealing device having one or more apertures extending therethrough, wherein the compressible sealing member can be inserted into one of the apertures in the sealing device, in use, to form a seal between the sealing device and a cable extending through the sealing member and the sealing device.
• the sealing member of the apparatus therefore preferably comprises a compressible sealing member which can be inserted into an aperture extending through the sealing 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 of relatively small diameter, or wires or fibres etc., need to be sealed by the sealing device.
• the sealing device preferably comprises a device to seal an end of a cable splice closure, e.g.
• the apparatus of the invention most preferably comprises a cable splice closure, and the apparatus may advantageously further comprise a housing into which one or more cables may extend.
• the compressing means (where present) is preferably part of the sealing device.
• the compressing means may advantageously comprise one or more piston(s) which can be moved relative to the sealing device.
• the movement of the piston(s) is preferably in a direction transverse, and especially substantially perpendicular, to the direction in which a cable extends, in use, through the sealing member.
• 'piston' is meant a component of the sealing device which may be moved relative to the main part (e.g. body) of the sealing device to exert pressure on the compressible sealing member.
• the or each piston may, for example, take the form of a pressing part attached to a shaft, e.g.
• the sealing device may have a passageway communicating between an aperture extending through the sealing device and the outside of the sealing device and a shaft may extend between the pressing part of the piston through the passageway to the outside of the device, where it can be operated by hand to make the required movement of the piston.
• the sealing device preferably comprises two end plates between which, at least in use, is located sealing material.
• the pistons are located in at least one of the end plates.
• the sealing device is preferably wraparound, and more preferably it comprises two major parts which are separable in a plain extending substantially coplanar with, or substantially parallel to, the or each cable extending, in use, through the sealing device.
• the sealing device may, in use, have a cavity between the end plates thereof to contain the sealing material located therebetween.
• the cavity is preferably substantially closed, in use, circumferentially between the two end plates.
• the sealing material which may be used in the invention may generally comprise any suitable sealing material, for example, a grease, especially a highly viscous grease, e.g.
• the sealing material of the sealing device (where present) and the sealing material of the sealing member (where present) may be the same or they may be different. It is preferred, however, that they comprise the same material.
• the sealing device may comprise means to compress the sealing material located (where present), at least in use, between the end plates thereof.
• the sealing material compressing means also compresses the sealing material (where present) of the sealing member when the sealing member is located, in use, in the sealing device.
• the sealing material compressing means may, for example, comprise a piston similar to those described above for compressing the sealing member.
• the sealing material compressing means is preferably located in the cavity of the sealing device (where present) and is preferably movable relative to the cavity. It is also preferably operable (e.g. by hand) externally of the sealing device. Such compression of the sealing material is particularly advantageous when the sealing material comprises 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 oil - extended polymer compositions.
• 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 less than 12%, particularly less than 10% and especially less than 8%.
• Ultimate elongation, also at room temperature is 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 will preferably be less than 35%, especially less than 25%.
• 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.
• 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.
• 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 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 such as moisture scavengers (eg. Benzoyl chloride), antioxidants, pigments and fungicides.
• Figure 1 a shows a gripping member of a compressible sealing member according to the invention
• Figure 1b shows a cable and two gripping members, with a tape wrapped around them
• Figures 2a and 2b each show a compressible sealing member according to the invention
• Figure 3 shows, schematically, how a compressible sealing member fits into a sealing device according to the invention
• Figure 4 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 5 shows half of a sealing device according to the invention
• Figures 6a and 6b show two views of half of another form of sealing device according to the invention.
• Figure 7 shows another view of the half of the sealing device shown in Figure 5;
• Figure 8 shows, in cross-section, an assembled cable splice closure according to the invention
• Figure 9 shows one of the sealing devices of the closure shown in Figure 8 in cross-section A-A.
• Figure 10 shows the sealing device of Figure 9 in cross-section B-B.
• Figures 1to 3 show features of a compressible sealing member according to the invention.
• Figure 1a shows a gripping member 77 of a compressible sealing member, 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 pe ⁇ endicular to the gripping portion, one extension at each end of the gripping portion. The lateral extensions are for engaging a compressible end part of a compressible sealing member, as shown in Figure 1b.
• Figure 1b shows, schematically two gripping members 77 positioned on a cable 85, with a tape 87 wrapped around the cable and both gripping members.
• Figure 2a shows a compressible sealing member, comprising two compressible end parts 89 and sealing material 91 (e.g. gel) located between the end parts.
• sealing material 91 e.g. gel
• 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 compressible sealing member to permit side-entry of a cable etc. into the compressible sealing member.
• 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 members 77 can preferably be inserted into the compressible sealing member by opening up the slits 95, pushing the cable, tape and gripping members into an aperture 94 and arranging the lateral extensions 83 of the gripping members so that they extend along opposite end faces 97 of a compressible end part of the sealing member as illustrated in Figure 2b.
• the gripping members are engaged with the compressible sealing member such that longitudinal movement of the gripping members 77 with respect to the compressible sealing member is substantially prevented.
• Transverse compression of the compressible end parts 89 for example in the direction of the arrows, causes the gripping members 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 3 shows, schematically, how a compressible sealing member 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.
• FIG. 4 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 11 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 pe ⁇ endicular to the cable.
• Each channel 11 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 5 to 7 show a variety of views of two different, but similar, sealing device half pieces: figures 5 and 7 show two views of one form of sealing device and figures 6a and 6b 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).
• fluid e.g. moisture or gas
• the sealing device half pieces of figures 5 to 7 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.
• 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 6b 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.
• FIG. 8 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.
• each sealing device has bolts 31 which join the two half pieces of each sealing device together. Pairs of pistons 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.
• the retention strip may advantageously be wound around either a cable or a compressible sealing member according to the invention, in order to increase the effective diameter of the cable or sealing member to be closer in size to the internal diameter of the cable entry aperture of the sealing device, or at least closer in size to the radii of the arcuate gripping surfaces of the pistons 33.
• 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 9 shows one of the sealing devices of the splice closure shown in Figure 8, in cross-section A-A.
• This cross-section illustrates the pistons 33 of the sealing device, movably located in channels 11.
• Each piston 33 has an arcuate gripping surface 41 provided with gripping protrusions 43.
• Figure 10 shows the sealing device of Figure 9 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.

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• Cable Accessories (AREA)
• Installation Of Indoor Wiring (AREA)

Applications Claiming Priority (3)

Publications (1)

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Family Applications (1)

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• 1994
  • 1994-09-21 GB GB9419034A patent/GB9419034D0/en active Pending
• 1995
  • 1995-09-19 AU AU35266/95A patent/AU3526695A/en not_active Abandoned
  • 1995-09-19 WO PCT/GB1995/002228 patent/WO1996009671A1/en not_active Application Discontinuation
  • 1995-09-19 EP EP95932075A patent/EP0782777A1/de not_active Withdrawn
  • 1995-09-21 PE PE27967895A patent/PE26496A1/es not_active Application Discontinuation

Non-Patent Citations (1)

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