GB2475276A - Fibre optical joint system and joint port - Google Patents

Abstract

A fibre optical joint system 1 comprises multiple individual joint enclosures 4, 70 which are connected together to form a single integrated cable management system at one joint 4. A joint port 50 in the system 1 lies between a joint base 3, carrying mechanics of the joint, and joint cover 4. The base 3 holds cables 20 within which are housed data communication lines 30. The joint port has a main body 51 which, in use, is interposed between the joint base 3 and the joint cover 4 and a duct 60 which provides a conduit between the main body 50 and an end of the conduit. A plurality of ducts 60 may connect a plurality of auxiliary joint housings 70 to a common joint base 3.

Description

Title: A Joint Port

Description of Invention

This invention relates to joining optical fibres in an optical fibre network using a joint.

In an optical fibre network many remote geographical locations are connected over the network to one another. Figure 1 of the accompanying drawings shows a schematic of part of an optical fibre network in which three sites A, B and C are connected to one another through a joint 1. Individual fibres are used to connect the sites to one another either directly or indirectly via joints.

In this example, sites A and B are indirectly connected by two fibres, one running from A and one running from B. The fibres end in straight joints which are spliced together in a splice tray held within a joint housing. Sites A and C are directly connected by a single fibre which loops into and out of the joint.

This is a so-called loop joint.

Fibre optic network joints kept in a housing which varies in size but is typically between 50cm to a metre and a half in length with a diameter of approximately 2Ocms. Joints are located at access points, usually inside a footway box.

Joints can be accessed through the footway box or brought to the surface if they are located underground. The joint housing is opened and changes can be made to the interconnections on the network at that joint. New connections can be made or existing connections re-routed. Connections are made by splicing individual fibres together in the joint. This is normally done using a splicing tray in the joint housing.

Normally, the joint housing will be removed from the footway box and worked on in a temporary structure or vehicle adjacent the footway box.

A joint comprises a joint housing having a base with a plurality of knock through ports through which cables can be fed. Typically, a sleeve is passed over the knock-through port and the cable. The sleeve is then heat shrunk to seal the port and cable to prevent ingress of moisture and dirt. The joint base is usually a circular plate from which the knock-through ports depend. The base has a central upstanding spine on the opposite side of the plate to the knock-through ports. The spine provides a structural frame to which are mounted a series of splice trays. The splice trays form a stack on the spine. An elongate joint housing dome sits over the splice tray stack and encloses the stack. The open end of the housing dome has a cover flange extending annularly around the open end and is sealingly engaged with an 0-ring seal clamping ring provided on the joint base.

Cables enter the joint through the various knock-through ports. Each cable houses a cluster of tubes and each of the tubes contains bare optical fibres, typically 12 fibres. The sheath of the cable terminates in the knock-through port so that the only tubes containing the fibres extend out of the joint base.

The exposed tubes may be 2 or 3 metres in length. For straight joints the ends of the tubes are stripped to expose the bare fibres. Where the cable is a loop joint, the tubes are exposed at the joint base and may also be 2 to 3 meters in length but importantly they are not stripped and the bare fibres are not exposed as shown schematically in figure 1 of the accompanying drawings.

The joint itself can have many different configurations determined by the number and type of cables entering the joint, the types of joint, either straight joint or loop joint, the shapes of the knock-through ports on the joint base; and different configurations of frame, spine and splice tray stacks. Certain configurations can omit one or some of these features.

A joint housing offers a predetermined spatial envelope within which the mechanics of the joint are located. There is a large amount of tubing which must be managed within the tight confines of this spatial envelope. When tubes are being manipulated when making new connections or re-routing connections access may be required to specific tubes in a stored bundle of tubes and those stored tubes may be in contact with other tubes whose live fibres are spliced already in the splice trays or otherwise live.

Joints in access networks must often accommodate several connection configurations: tubes may pass through the joint un-interrupted; tubes may be interrupted with the fibres spliced through; tubes from access cables may be terminated with their fibres spliced to other cables; tubes may be stored for future use.

Especially in these hybrid configurations, the housing can be so congested that the unused tubes must literally be swaddled in a storage frame lying along side and in contact with the splice trays and the tubes going into those splice trays. Plastic tape, or duct tape, is commonly used to constrain the tubes to the frame. When one releases the plastic tape swaddling these tubes, the elastic energy in the stored tubes is released and they can unfold quickly, perhaps knocking other tubes containing fibres which are in use. There may also be bending of the tubes either as a result of neighbouring tubes unfurling or being stored with too tight a radius. Knocks, constrictions and overly tight radii can all cause transient losses in the data travelling in the fibres. Such transient losses reflect loss of service to network users and this cannot be tolerated.

It is desirable to prevent any new splicing works or reorganisation within the joint from having an effect on the existing live customer circuits running through the joint.

There is thus a problem of accessing joints without causing transient losses in live circuits in complex multi-function joints.

A mechanism for enhancing flexibility and performance of a joint through better tube management whilst not changing the design or ports of an existing joint base is an object of the invention According to one aspect of the present invention, there is provided a single fibre optical joint system comprising multiple individual joint enclosures, connected together to form a single integrated cable management system at one joint.

Preferably the cable management system has a single base from which tubes in the joint are securely physically separated from one another.

Conveniently, a fibre cable network joint port is provided in the joint system, the port, in use, being between a joint base carrying mechanics of the joint and a joint cover, the base holding one or more cables within which are housed one or more data communication lines, wherein the joint port has a main body interposed, in use, between the joint base and the joint cover and a duct providing a conduit between the main body and an end of the conduit.

Advantageously, the main body of the port provides a communication line management space around the mechanics of the joint.

Preferably, the space is generally toroidal.

Conveniently, the space has fibre management retainers to retain communication lines within the space.

Advantageously, a lid is provided for the main body and removal of the lid allows access to the space in the main body.

Preferably, the duct (or ducts) is (or are) a flexible duct(s).

Conveniently, the duct(s), the main body or any other item forming part of an assembly including the flexible duct limits the radius of curvature of the duct from going below a minimum threshold.

Advantageously, a plurality of abutments are provided on the rib, which abut one another when the radius of curvature of the flexible duct approaches the minimum threshold.

Preferably, the abutments are a series of spaced ribs which project outwardly from the flexible duct.

Conveniently, the value of the threshold is greater than or equal to a recommended minimum bending radius of a particular communication line.

Advantageously, the communication line is an optical fibre.

Preferably, the joint has a defined spatial envelope and the main body of the joint port defines a space around that envelope and the duct defines a conduit leading from that space to another area and providing management of communication lines in the space and in the conduit.

Conveniently, the duct has a distal end from the main body for rigid connection to a base of a storage unit.

Advantageously, the storage unit is a joint housing.

Preferably a fibre cable network joint assembly comprises a first housing, a second housing and any subsequent housings, and a joint port, wherein the joint port is rigidly connected between the base and cover of the first housing, the duct is flexible and is a conduit to a rigid interconnection with the second housing and subsequent housings.

Conveniently, the first and second housing (and subsequent housings) are rigidly interconnected to one another.

Preferably, a plurality of ducts are provided.

According to another aspect of the present invention, there is provided a single fibre optical joint system comprising multiple individual joint enclosures, connected together to form a single integrated cable management system at one joint, the port, in use, being between a joint base carrying mechanics of the joint and a joint cover, the base holding one or more cables within which are housed one or more data communication lines, wherein the joint port has a main body interposed, in use, between the joint base and the joint cover and a duct providing a conduit between the main body and an end of the conduit.

In order that the invention may be more readily understood, embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic representation of an optical fibre network, showing the multiple tube configurations; Figure 2 is a perspective view of a straight joint of a cable; Figure 3 is a perspective view of a loop joint of a cable; Figure 4 is a schematic side view of a joint fitted with a joint port embodying the present invention; Figure 5 is a schematic representation of a multi-function joint Figure 6 is an exploded view of a joint port embodying the present invention); Figure 7 is an exploded view of a mounting for use with joint housings; Figure 8 is a perspective view of a joint assembly embodying the invention; Figure 9 is a top view of the joint port embodying the present invention; and Figures lOa and lOb are schematic representations of possible joint configurations.

Referring to the figures, in figure 4 a joint 1 supplies a junction in an optical fibre network between customer sites A, B and C. The existing joint 1 comprises a joint base 3 and a housing dome 4 or housing cover. The housing dome 4 acts as an envelope or enclosure for the mechanics of the joint 1. The joint base 3 has a number of capped ports 5 which are all closed but which can be cut or knocked-through to allow access into the base 3. Cables 10 enter the base 3 through the ports 5. A heat shrink seal (not shown) is applied around the cables 10 and ports 5 to prevent ingress of moisture or dirt.

A central metal spine 6 is upstanding from the base 3 and provides the support or frame for a stack 7 of splice trays 8 on one side of the spine 6. The other side of the spine 6 carries a loop storage frame 9.

The housing dome 4 has an open end with an outwardly extending annular flange 11 which cooperates with an 0-ring seal clamping ring 12 on the joint base 3. Preferably, the cover flange 11 is greased with silicone before forming an 0-ring seal with the clamping ring 12.

Each cable 10 houses a cluster of tubes 20 and each of the tubes contains bare optical fibres 30, typically 12 fibres. The sheath of the cable 10 terminates in a knock-through port 5 so that only the tubes 20 containing the fibres 30 extend out of the joint base 3. The exposed tubes 20 may be 2 or 3 metres in length. For straight joints the ends of the tubes 20 are stripped to expose the bare fibres 30. Where the cable 10 terminates in a loop joint, the tubes 20 are exposed at the joint base and may also be 2 to 3 meters in length but importantly the tubes 20 are not stripped and the fibres 30 are not exposed.

Existing joints 1 are prone to congestion. The unused ports 5 could be used to take unused tubes 20 out of the joint 1 and ease congestion but that would occupy one of the valuable ports 5 and leave the tubes 20 (which are unprotected at this stage by a cable sheath) vulnerable to knocking, over bending or even permanent damage. Cutting a new port in the joint base 3 or in the dome 4 are not acceptable options as they would suffer from the same problem of porting unprotected tubes into a vulnerable area. Further, dismantling the joint by removing the dome 4 would cause significant problems if tubes were running out of a port cut into the dome 4.

A joint port 50 embodying the present invention comprises a moulded structure with an hexagonal external sidewall 51 and a smooth annular circular inner surface 52. The joint port 50 has a top opening 53 and a bottom opening 54.

The port has a lid 55 comprising the top surface of the joint port. The lid 55 is fixed at its corners to the main body of the port 50 by a series of bolts.

The joint port 50 has a toroidal space 58 surrounding the openings 53,54 to the top and bottom of the joint port 50. The torodial space 58 lies between the smooth cylindrical inner surface 52 of the sidewall 51 and the cylindrical space defined by the co-axial top and bottom openings 53,54.

The space 58 is fitted with tube management guide pins 59 and retaining straps to retain loose tubes 20 within the toroidal space 58 and away from the cylindrical cavity between the top and bottom openings 53,54. The inner radius of the toroidal space 58 has a minimum limit. The radius cannot be smaller than the tightest bending radius permitted for a tube 20 or fibre 30. If tubes or fibres are permitted to bend too tightly, then this can cause transient losses of data over these communication lines. A large margin of safety can be built in here and the inner radius of the toroidal space is around 100mm which is much greater than needed.

There is one opening 56 in the inner surface 52, through the sidewall 51. This opening 56 leads from the toroidal space 58 within the main body of the port joint into a flexible duct 60 mounted onto the side wall 51.

This embodiment of the invention has been designed to accommodate multiple openings (56a, 56b, 56c etc) to connect via multiple flexible ducts (60a, 60b, 60c etc) to multiple shaped manifolds.

The joint port 50 sits in use between the joint base 3 and the housing dome 4.

The top of the joint port 50 has a cover flange 61 and a clamping ring 62 surrounding the cover flange. The housing dome 4 cover flange 11 sits on the top cover flange 61 and the two are sealed together by the clamping ring 62.

Likewise the bottom of the joint port 50 has a cover flange 63 to sit on and adjacent the flange on the joint base 3. The two are sealed together by another clamping ring 64. 0-ring seals are provided between respective pairs of flanges. The joint port 50 is thus sandwiched between the housing dome 4 and the joint base 3 and sealed to these two parts by the clamping rings 62,64.

When fitted between the joint base 3 and the housing dome 4, the joint port 50 provides a sealed and enclosed envelope with the exception of the opening 56 to the flexible duct 60.

A series of tightly and regularly spaced ribs 65 project outwardly from the flexible duct 60. These ribs 65 protect the duct 60 from over flexing and adopting too tight a radius. Again, the radius of the flexed duct 60 cannot be smaller than the tightest bending radius permitted for a tube 20 or fibre 30. If tubes or fibres are permitted to bend too tightly, then this can cause transient losses of data over these communication lines. Before the flexible duct 60 approaches its minimum radius, adjacent ribs close the space between them until they abut one another. The ribs 65 act as stops to prevent over-flexing of the duct 60. The duct, when no forces are acting upon it is substantially straight and offers a clear uninterrupted conduit along its length.

The flexible duct 60 terminates in a shaped manifold 66 for connection to a tube storage unit which can be regarded as a secondary or auxiliary joint housing 70. The auxiliary joint housing 70 includes the normal mechanics of a joint 1 being a spine, splice tray stack and other tube management facilities.

The auxiliary joint housing 70 is secured to the manifold 66.

By addition of multiple shaped manifolds (60a, 60b, 60c etc) and auxiliary joint housings (70a, 70b, 70c etc), multiple differing tube and fibre management functions can be securely physically separated from one another, while sharing a common joint base as shown in figures 1 Oa and 1 Ob.

The existing joint housing 4 and the auxiliary joint housing 70 may be either cylindrical or flat in nature and elongate. Other housing configurations are possible. The two joint housings 4, 70 are attached to one another by a pair of strapped brackets 80 for a cylindrical housing or one strap for a flat design of housing. Each bracket or strap partially encircles a respective joint housing 4, and can be strapped thereto by a ratchet mechanism. The two brackets 80 are locked together back-to-back to form a rigid connection between the joint housing dome 4 and the storage unit 70. In this manner the two housings (the storage unit 70 and the joint housing 4, now with joint port fitted) are rigidly interconnected via the brackets and all the other interconnections between the elements are rigid save the flexible duct which is rigidly connected at its ends to the housing and the main body.

When assembled, the flexible duct 60 between the joint port 50 and the storage unit 70 passes through approximately 90° with a gentle radius of around 40-50mm. It is important that the radius of the flexible duct is substantially greater than the minimum bend radius for the tubes so that the tubes are not overly flexed on too tight a radius which would otherwise cause transient losses in the lives fibres inside the tubes.

It should be noted that the use of the joint port 50 creates a headspace in the top of the domed housing 4 as the mechanics of the joint have effectively been dropped in the housing by the height of the joint port 50. A shorter housing can be used to remove the headspace or the headspace utilised by extending the height of the mechanics to occupy the headspace.

The joint port 50 is fitted to an existing joint as follows: The existing joint housing is removed from the footway box and placed on a workbench. The clamping ring 12 is unlocked and removed and the housing dome 4 is removed from the base 3. Tubes to be relocated in the storage unit are identified. The swaddled tape bundle is gently released and those tubes to be stored in the storage unit are slowly folded out. The loop storage frame 9 can be made redundant at this point and disposed of if sufficient loops can be stored in the storage unit. In any event, more room is provided for live fibres by removing any of the tubes, easing congestion.

Any 0-rings can be re-siliconed or replaced at this point prior to re-assembly.

The lid 55 of the port 50 is detached, ready to fit the joint and the main body of the joint port passes over the splice tray stack of the joint at the same time as the released tubes destined for storage are fed through the bottom opening 54 taking care not to trap or kink any tubes 20.

The joint base 3 is then fitted to the main body of the joint port 50 in a desired orientation, preferably with the duct 60 pointing away from and on the opposite side to any major knock-through port 5 on the base 3. The clamping ring 64 secures to the cover flanges and is locked in place by a locking screw which should then not be removed and the joint port 50 and the base 3 are then considered and handled as a single unit.

The splice tray rack stands above the open main body of the joint port 50 and tubes 20 can be routed around the toroidal space 58, held in place by the guide pins and retaining straps 59. The space 58 can be used for storage of an entire tube or to take up a wound length of part of a tube. The tubes to be stored in the storage unit 70 are carefully fed through the opening 56 and on through the flexible duct 60.

The lid 55 is carefully rnanoeuvred down the splice tray rack which passes through the top opening 53 and is then secured to the main body of the joint port by the bolts. PVC tape or the like is used to secure the mechanics of the joint, such as the splice tray rack. The dome housing 4 is then secured to the joint port 50.

The storage unit 70 has a base with knock-through ports, one of which is opened or cut. The relocation tubes protruding from the flexible duct 60 are fed through the storage unit port and then the manifold mounted at the end of the flexible duct 60 is fitted to the open port in the storage unit 70.

The tubes in the storage unit 70 can be stored on the mechanics of the storage unit 70 which may have its own splice tray, rack, loop or tube storage frames or other configurations. PVC tape or the like is used to secure the mechanics of the storage unit 70. The dome housing of the storage unit is then fitted and sealed to the storage unit base.

The strap brackets 80 are secured back to back to one another and secured in turn around respective housing domes to provide the assembled and secure unit shown in figure 8.

The joint port 50 enhances the existing joints by providing a solution to the problem of accessing joints in existing installations without causing transient losses in live circuits. The joint port provides a managed release of the tube congestion present in existing installations and absolutely minimises any disruption to network users. The joint port offers a mechanism for enhancing a joint through better tube management whilst not changing the design or ports of an existing joint base.

Many different configurations of the mechanics of a joint are possible within either of the housing domes used. A splice tray rack may be omitted entirely and the joint could consist entirely of loops in one extreme, necessitating only loop storage.

In other embodiments the duct is not flexible but is radiussed in a rigid curve.

Any curvature of the rigid duct is controlled to be at a radius less than the minimum bending radius of the fibres being carried.

An advantage of the duct being flexible is that tubes can be fed easily and smoothly through a straight duct and then the duct bent through a controlled angle smoothly and in a controlled manner without the flexing action causing any stress to the fibres within. With a rigid duct which is bent through an angle, it is less easy to feed the fibres through smoothly and the fibres are more at risk of being stressed.

The joint port provides a rigid platform in a joint assembly, the joint port being interposed between a joint base and a joint cover and a flexible duct feeding away from the main joint to another unit for receiving tubes. The flexible duct is rigidly connected to the other unit. The other unit is rigidly connected to the joint so that the whole assembly provides a secure environment for retaining cables, tubes and fibres without danger of transient losses being caused in the network when the joint is being accessed.

It should be noted that all the joint housings, bases, the joint port and the flexible duct of the joint port are manufactured from extremely robust materials.

Even though the duct can be flexed manually (without tools) to bend through a right angle, its construction is extremely robust and will withstand significant maltreatment whether intentional or otherwise.

The invention is not limited to specific cables of the type described above but can cater for any form of cabling.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims (23)

1. CLAIMS: 1. A single fibre optical joint system comprising multiple individual joint enclosures, connected together to form a single integrated cable management system at one joint.
2. 2. The cable management system according to claim 1, having a single base from which tubes in the joint are securely physically separated from one another.
3. 3. A fibre cable network joint port in the joint system of claim 1, the port, in use, being between a joint base carrying mechanics of the joint and a joint cover, the base holding one or more cables within which are housed one or more data communication lines, wherein the joint port has a main body interposed, in use, between the joint base and the joint cover and a duct providing a conduit between the main body and an end of the conduit.
4. 4. A port according to claim 3, wherein the main body of the port provides a communication line management space around the mechanics of the joint.
5. 5. A port according to claim 3, wherein the space is generally toroidal.
6. 6. A port according to claim 4 or 5, wherein the space has fibre management retainers to retain communication lines within the space.
7. 7. A port according to any one of claims 2 to 6, wherein a lid is provided for the main body and removal of the lid allows access to the space in the main body.
8. 8. A port according to any preceding claim, wherein the duct (or ducts) is (or are) a flexible duct(s).
9. 9. A port according to claim 8, wherein the duct(s), the main body or any other item forming part of an assembly including the flexible duct limits the radius of curvature of the duct from going below a minimum threshold.
10. 10. A port according to claim 9, wherein a plurality of abutments are provided on the rib, which abut one another when the radius of curvature of the flexible duct approaches the minimum threshold.
11. 11. A port according to claim 9, wherein the abutments are a series of spaced ribs which project outwardly from the flexible duct.
12. 12. A port according to any one of claims 8 to 11, wherein the value of the threshold is greater than or equal to a recommended minimum bending radius of a particular communication line.
13. 13. A port according to any one of claims 3 to 12, wherein the communication line is an optical fibre.
14. 14. A port according to any one of claims 3 to 13, wherein the joint has a defined spatial envelope and the main body of the joint port defines a space around that envelope and the duct defines a conduit leading from that space to another area and providing management of communication lines in the space and in the conduit.
15. 15. A port according to any one of claims 3 to 14, wherein the duct has a distal end from the main body for rigid connection to a base of a storage unit.
16. 16. A port according to claim 15, wherein the storage unit is a joint housing.
17. 17. A fibre cable network joint assembly comprising a first housing, a second housing and any subsequent housings, and a joint port according to any one of claims 3 to 16, wherein the joint port is rigidly connected between the base and cover of the first housing, the duct is flexible and is a conduit to a rigid interconnection with the second housing and subsequent housings.
18. 18. A port according to claim 17, wherein the first and second housing (and subsequent housings) are rigidly interconnected to one another.
19. 19. A port according to any one of claims 3 to 18, wherein a plurality of ducts are provided.
20. 20. A single fibre optical joint system comprising multiple individual joint enclosures, connected together to form a single integrated cable management system at one joint, the port, in use, being between a joint base carrying mechanics of the joint and a joint cover, the base holding one or more cables within which are housed one or more data communication lines, wherein the joint port has a main body interposed, in use, between the joint base and the joint cover and a duct providing a conduit between the main body and an end of the conduit.
21. 21. A joint port substantially as hereinbefore described with reference to and as shown in the accompanying figures.
22. 22. A cable network joint assembly substantially as hereinbefore described with reference to and as shown in the accompanying figures.
23. 23. Any novel feature or combination of features described, claimed or illustrated herein.