WO2001031380A1

WO2001031380A1 - Optical fibre management

Info

Publication number: WO2001031380A1
Application number: PCT/GB2000/003779
Authority: WO
Inventors: Michel Vanderlinden
Original assignee: Tyco Electronics Raychem Nv; Tyco Electronics Uk Ltd.
Priority date: 1999-10-27
Filing date: 2000-10-03
Publication date: 2001-05-03
Also published as: AU7541000A; GB9925310D0

Abstract

A rack (1) for optical fibre management comprises a plurality of connection units (10) for connecting optical fibre cables (20); and a plurality of guiding members (12) for guiding optical fibre cables (20) to and/or from the connection units (10). For taking up optical fibre cable overlength additional overlength guiding members (15, 16) are provided which are spaced apart so as to provide trajectories having different lengths. At least some of the overlength guiding members (15) constitute a first and second array (18, 19), which are spaced apart. At one end of which an additional guiding member (16) is located so as to direct optical fibre cable originating from the first array (18) towards the second array (19).

Description

OPTICAL FIBRE MANAGEMENT

The present invention relates to the management of optical fibre cables. More in particular, the present invention relates to a rack for optical fibre management, comprising: a plurality of connection units for connecting optical fibre cables and a plurality of guiding members for guiding optical fibre cables to and/or from the connection units, wherein, for taking up optical fibre cable overlength additional overlength guiding members are provided which are spaced apart so as to produce trajectories having different lengths, and wherein at least some of the overlength guiding members constitute a first and a second array, which arrays are spaced apart.

Such racks are used for connecting, splicing and organising fibre optic cables. It will be understood that the term "fibre optic cable" as used here may comprise both single and multi fibre cables and may comprise so-called "pig tail" and "jumper" type cables.

These racks may accommodate several, in fact ten or more connection units, for instance in a stacked arrangement. Due to the distances between the connection units in the rack, some cables may be too long, requiring organised storage of the overlength. The more cables are connected in a rack, the more different cable lengths are bound to be present. Especially in modern high-density fibre optic cable management racks this poses a problem.

An example of an optical fibre management rack having a storage region for storing spare length of optical fibres is disclosed in International Patent Application WO 97/30370 (Raychem). In this known rack, excess lengths of optical fibres extending between connection units are taken up by storage regions each having one or more horizontal arrays of guiding members. The fibre is directed from the access port of the storage region via a single array back to the access port. Although this known arrangement provides an excellent flexibility and manageability, the length of excess fibre stored in each storage region is limited by the width of said region. The known arrangement is therefore less suitable for long excess lengths, for example excess lengths greater than twice the width of the storage region. It is therefore an object of the present invention to provide a rack having a versatile yet compact and economical storage of fibre optic cable overlengths, in particular relatively long overlengths.

It is another object of the present invention to provide a rack allowing large amounts of overlengths to be stored in a small space.

It is yet another object of the present invention to provide an overlength storage unit which can be added to existing racks.

To achieve these and other objects and to avoid the disadvantages of the Prior Art the rack defined in the preamble is according to the invention characterised in that at one end of the arrays an additional guiding member is located so as to direct optical fibre cable originating from the first array towards the second array.

By providing two adjacent arrays of overlength guiding members and at least one additional (pivot) guiding member, a large range of overlengths can be accommodated in a relatively small space as an overlength can be stored using both arrays.

Advantageously, both the first and second array extend vertically, thus providing columns of guiding members. Preferably, the additional guiding member is located above the first and second arrays. In an advantageous and space saving embodiment, the overlength guiding members have a semicircular cross-section and the additional guiding member has a substantially circular cross-section.

The present invention further provides a unit for use with a rack for optical fibre management, which for storing fibre optic cable overlengths is characterised by overlength guiding members for guiding optical fibre cable overlength, wherein at least some of the overlength guiding members constitute a first and second array which are spaced apart and at one end of which a pivot guiding member is located so as to direct optical fibre cable originating from the first array towards the second array. The present invention additionally provides a method for storing optical fibre cable overlength in a rack provided with a first array and a second array of overlength guiding members, the method comprising the step of arranging the optical fibre cable in a loop around at least part of the first array, and characterised by the step of arranging the optical fibre cable, via an additional guiding member, in a loop around the second array.

The invention will further be described with reference to exemplary embodiments illustrated in the accompanying drawings, in which:

Figure 1 shows a front view of a first embodiment of a rack of the present invention. Figure 2 shows a front view of a second embodiment of a rack of the present invention.

Figures 3a and 3b schematically show advantageous cable routing loops in the racks of Figs. 1 and 2 respectively.

The rack 1 shown in Fig.l contains a number of connection units 10 for connecting, splicing and/or arranging optical fibres. These connection units are often constituted by drawer-like structures in which patching and/or splicing trays may be accommodated. Each connection unit 10 is provided with an access part 11, in the example shown having a "trumpet" shape so as to prevent the bending of optical fibres beyond their maximum bend radius. The connection units may be provided with additional access parts (not shown), which may be located at the back of the units.

Fibre optic cables 20 are led from the ports 11 and guided down the rack by guiding members or spools 12 which have a curved surface so as to guide the cables maintaining at least their minimum bend radius. Although Fig. 1 shows spools 12 having a half-circle cross section, fully cylindrical spools may be substituted for some or all spools in Fig. 1.

It is noted that fibre optic cables 20 may each contain a single optical fibre or a plurality of optical fibres. It is further noted that the direction of "travel" of the cables 20 through the rack is used for descriptive purposes only and that the actual direction in which the cables are led through the rack on installation may vary. In conventional racks, the cables 20 would leave the rack immediately, possibly via an intermediate spool 13 placed to better control the cables 20 at the bottom of the rack. This causes the problem, however, of very unequal cables lengths. That is, cables 20 connected to the top connection unit 10 would be much shorter by the time they left the rack (for instance through its bottom surface) than cables originating from the bottom connection unit, which is clearly undesirable. Also, it would be difficult or even impossible to reconnect cables 20, for instance from the bottom connection unit to the top one.

To solve this problem, the rack 1 of Fig. 1 is provided with an overlength unit 2 which contains, in the example shown, two adjacent columns 18, 19 of overlength spools 15 as well as a redirection (or pivot) spool 16. The columns of overlengths spools 15 are in this embodiment spaced apart at a distance approximately equal to the width of the spools. The redirection spool 16 is located beneath the two columns, under the gap separating the columns so as to be on the centre line of the unit 2. The redirection spool 16 is preferably fully cylindrical.

By means of the overlength unit 2, almost any cable overlength can be accommodated. The cable 20 is fed into the overlength unit 2 via the intermediate spool 13 and led up over an appropriate left column overlength spool 15, down to and around the redirection spool 16 and up again to an appropriate right column overlength spool 15. Finally, the cable 20 is led down to an access opening (at 9) in the bottom part of the unit 2.

By appropriately choosing a left and a right overlength spool 15, the trajectory of the cable 20 through the unit 2 can be varied to a great extent, the additional trajectory provided by the overlength unit 2 ranging from almost none to about four times its height. In addition, the overlength unit offers a great flexibility, due to the number of different overlengths spools 15. In the example shown, twenty-six overlength spools 15 are provided, resulting in twenty- five different overlength storage lengths.

Should even more overlength storage be required, a second or even third overlength unit 2 may be added to the rack. Alternatively, the overlength unit 2 (or rack 1) may be provided with a second redirection spool 16 and a third column of overlength spools 15. By using the redirection spool 16 in the configuration shown, a very suitable cable trajectory is obtained in which cable crossings are avoided. This will later be further explained with reference to Fig. 3.

The overlength unit 2 may be integral with the rack 1 but may also be provided as a separate unit which can be added to existing racks. It will be understood that the overlength unit 2 may also be arranged horizontally rather than vertically, in which case the columns of overlength spools 15 become rows.

Fig. 2 shows an alternative embodiment of a rack 1 of the present invention in which the cables 20 exit at the top part at 8 of the overlength unit 2 instead of at the bottom part. Again, the cables 20 (which are here drawn only partially for the sake of clarity of the drawing) are fed into the unit 2 via the intermediate spool 13 which here also serves to suspend the cables. Additional intermediate spools 14, 14' may be provided to better guide the cables 20 through the rack 1. In principle the same configuration is obtained as with the rack of Fig. 1, having the same advantages.

In Fig. 3 a the shape of the cable loop provided by the bottom-most overlength spools 15 and the redirection spool 16 is illustrated. This shape, implying the use of the redirection spool 16, prevents any crossing of the cables 20, which might lead to a disadvantageous organisation which would be difficult to manage and to rearrange. Similarly, Fig. 3b renders the shape provided by the top-most overlength spools 15 in conjunction with the redirection spool 16 of Fig. 2, this shape having the same advantages.

It will be understood by those skilled in the art that the embodiments described above are by way of example only and that many modifications and additions may be made without departing from the scope of the present invention as defined in the appended claims.

Claims

1. Rack (1) for optical fibre management, comprising:

- a plurality of connection units (10) for connecting optical fibre cables (20); and

- a plurality of guiding members (12) for guiding optical fibre cables (20) to and/or from the connection units (10), wherein, for taking up optical fibre cable overlength additional overlength guiding members (15, 16) are provided which are spaced apart so as to provide trajectories having different lengths, at least some of the overlength guiding members (15) constituting a first and second array (18, 19), which arrays are spaced apart, characterised in that at one end of the arrays (18, 19) an additional guiding member

(16) is located so as to direct optical fibre cable originating from the first array (18) towards the second array (19).

2. Rack according to claim 1, wherein both the first and the second arrays (18, 19) extend vertically.

3. Rack according to claim 2, wherein the additional guiding member (16) is located above or below the first and second arrays (18, 19).

4. Rack according to claim 3, wherein the overlength guiding members (15) have a semicircular cross-section and the additional guiding member (16) has a substantially circular cross-section.

5. Unit (2) for use with a rack (1) for optical fibre management, characterised by overlength guiding members (15) for guiding optical fibre cable overlength, wherein at least some of the overlength guiding members (15) constitute a first and second array (18, 19) which are adjacent and at one end of which an additional guiding member (16) is located so as to direct optical fibre cable originating from the first array (18) towards the second array (19).

6. Unit according to claim 5, provided with an opening (8, 9) at the bottom or top surface for passing fibre optic cables (20).

7. Method for storing optical fibre cable overlength in a rack (1) provided with a first array (18) and a second array (19) of overlength guiding members, the method comprising the step of: i) arranging the optical fibre cable (20) in a loop around at least part of the first array (18), and characterised by the step of: ii) arranging the optical fibre cable (20), via an additional guiding member (16), in a loop around the second array (19).

8. Method according to claim 7, wherein the additional guiding member (16) is located substantially between the first array (18) and the second array (19).

9. Method according to claim 7 or 8, wherein the additional guiding member (16) is located near one end of the first and second arrays (18, 19).

10. Method according to claim 9, wherein said one end is distant from an access port (2, 9) providing access to the arrays (18, 19).

* * * * * * *