GB2330823A

GB2330823A - Cable storage apparatus

Info

Publication number: GB2330823A
Application number: GB9722897A
Authority: GB
Inventors: Christopher Rodwell; Michael Ernest West
Original assignee: GEC Alsthom Ltd
Current assignee: Alstom UK Ltd
Priority date: 1997-10-30
Filing date: 1997-10-30
Publication date: 1999-05-05
Also published as: GB9722897D0

Abstract

A cable storage apparatus, preferably for the storage of electric/fibre-optic cables, comprises a drum 10 for the main cable 13 and a further cable 17 disposed in an annular space between two concentric members 14,16, wherein one of these members 14 is attached to the drum 10 and the other member 16 is stationary (see Figure 2 for the vice-versa arrangement). The two ends of the further cable 17 are connected to the main cable 13 and to signal-processing circuitry (not shown) respectively, and are anchored to the members 14,16. In use, the further cable 17 winds up against one member 14 when the cable is being deployed (Figure 1b) and against the other member 16 when the main cable 13 is being hauled in (Figure 1a). The effect of this is to avoid twisting of the further cable 17 when the drum 10 is rotated, whilst maintaining an electrical connection between the cables and the signal processing circuitry. To accommodate large numbers of turns of the main cable 13, the further cable 17 may be in sections, each with their own concentric members (see Figures 3, 5, 6 and 8). Preferably, one member of each pair of the rotatable concentric member(s) rotates at a higher speed than the other member of that pair. The first and second cable means 13,17 may also be used as conduits for the conveying of fluids.

Description

CABLE-STORAGE APPARATUS The invention concerns a cable-storage apparatus for the stowing and paying out of a cable means, and in particular a cable-storage apparatus for the stowing and paying out of an electric and/or fibre-optic cable means.

Arrangements for stowing and paying out a cable such as an electric or fibre-optic cable are known in which the connections at the end of the cable are taken to sliprings against which bear corresponding brushes, the brushes being connected to stationary apparatus adapted to process the signals carried by the cable. Use of sliprings in this way helps solve a problem which arises when the cable is attached directly to the stationary processing apparatus, namely the twisting of the cable when the drum is rotated.

The use of sliprings is sometimes not a practical proposal, hence alternative solutions to the twisting problem have been developed, one of which is to arrange for the drum to be stationary and to wind the cable onto the outside of the drum by means of a laying-on mechanism. Such a system, however, has the drawback of being complex and bulky.

In accordance with the invention, there is provided a cable-storage apparatus comprising a rotatable drum for the stowing and paying-out of a first cable means, a pair of substantially annular members disposed one at least partly inside the other so as to form an approximately annular space therebetween, one of said pair of substantially annular members being co-rotational with said rotatable drum and the other being stationary, and a second cable means disposed within said approximately annular space and having a first end which is secured to said rotatable drum and is adapted to be attached to one end of said first cable means, and a second end which is secured to said stationary substantially annular member, whereby, in use, rotation of said rotatable drum in one direction causes a winding of said second cable means against one member of said pair of substantially annular members and rotation of said rotatable drum in the other direction causes a winding of said second cable means against the other member of said pair of substantially annular members.

The second cable means may comprise a plurality of cable sections, there being a pair of substantially annular members associated with each cable section, the pairs of substantially annular members being disposed in series such that one member of each pair is co-rotational with one member of the succeeding pair, a first cable section being secured at one end to said rotatable drum and at the other end to the member of its associated pair of substantially annular members which is not co-rotational with said rotatable drum, and the remaining sections being secured at their ends to their respective pairs of substantially annular members.

When the apparatus is in use, all of the substantially annular members except said stationary member may rotate simultaneously and one member of each pair of substantially annular members may rotate at a higher speed than the other member of that pair.

The apparatus may comprise N cable sections and N pairs of substantially annular members, wherein said rotatable drum, in use, rotates at speed m and the faster-rotating members of the pairs of substantially annular members rotate at the following speeds, in order: N-1 Nd m N 1 N 2 m m, m. , m. , # N N N The slower-rotating member of a pair of substantially annular members and the faster-rotating member of a succeeding pair of substantially annular members may be constituted by the same member, said same member being of sufficient axial dimensions to accommodate both the associated cable sections.

The annular members may be rotated through a reduction-gearing mechanism.

Alternatively, each cable section may be allowed to wind at least partly against the relevant member of its associated pair of substantially annular members before succeeding cable sections are allowed to start winding. Control of the substantially annular members may be achieved by means of a Geneva stop mechanism or a clutch mechanism, in particular a slipping-clutch mechanism. A further technique for controlling the substantially annular members is to arrange for the cable section of each successive stage to be of successively greater stiffness.

The substantially annular members will normally be co-axial with the rotatable drum, although at least one of said substantially annular members may have an axis offset from that of said rotatable drum.

The stationary substantially annular member may be disposed within the rotatable substantially annular member, said rotatable substantially annular member being attached to said rotatable drum. The rotatable substantially annular member may then be constituted by a skirt extension of said rotatable drum. Alternatively, the rotatable substantially annular member may be disposed within said stationary substantially annular member and may be constituted by a boss extension of said rotatable drum.

The first and second cable means may be electrical and/or fibre-optic cable, or alternatively fluid-carrying conduits.

Embodiments of the invention will now be described, by way of example only, with the aid of the drawings, of which: Figures la and ib are sectional views in the axial and transverse planes of a cablestorage apparatus according to a first embodiment of the invention showing the apparatus in a stowed and deployed position, respectively; Figure 2 shows an alternative realisation of the first embodiment of the invention; Figure 3 is an axial-sectional view of a cable-storage apparatus according to a second embodiment of the invention; Figures 4a and 4b are end-views showing two possible configurations of the second cable means in the second embodiment; Figures 5 and 6 are axial-sectional views of a cable-storage apparatus according to third and fourth embodiments of the invention incorporating, respectively, three and four stages, Figure 7 shows a geared reduction-drive arrangement which may be used with the second embodiment of Figure 3; Figure 8 illustrates an alternative realisation of the fourth embodiment of the invention; Figure 9 illustrates the principle of the Geneva-stop mechanism; Figure 10 shows the arrangement of Figure 8 and incorporating a Geneva-stop mechanism as shown in Figure 9, and Figures 1 lea andi 1b are end-views of the cable-storage apparatus showing the use of an eccentrically disposed annular member.

In a first embodiment of the invention, as shown in Figure 1, a cable drum 10 has two flanges 11 and 12 for the constraining of a first cable means which takes the form of an electric or fibre-optic cable 13 and is to be stowed on the drum, one of the flanges 12 being provided with an annular member in the form of a skirt 14 extending parallel to the cylindrical surface 15 of the drum. Co-axial with the drum 10 is a further annular member, namely a spigot 16 which is fixed to equipment (not shown) containing circuitry for the processing of signals carried along the cable 13. The spigot 16 is thus stationary. Disposed in an annular space between the skirt 14 and the spigot 16 is a second cable means, namely a flat ribbon cable 17 attached at one end 20 to the spigot 16 and at the other end 21 to the flange 12 of the drum 10 (see Figure 2). An electrical connection is made between the end 21 of the ribbon cable and the corresponding end of the cable 13, a similar connection (not shown) being made between the end 20 of the ribbon cable and the afore-mentioned signal processing circuitry.

Figure la shows the apparatus in a stowed condition in which the cable 13 is wound fully onto the drum 10 and the ribbon cable 17 is wound onto the spigot 16. When it is desired to deploy, i.e. pay out, the cable 13, the drum 10 is rotated anticlockwise, looking along the arrow in Figure la, and during this time the ribbon cable 17 proceeds to wind off of the spigot 16 and against the inside surface of the skirt 14. At the end of the payingout process the apparatus is as shown in Figure ib with the cable 13 fully deployed and the ribbon cable 17 now fully wound against the skirt 14.

The cable may now be re-stowed onto the drum 10 by rotating the drum clockwise, upon which the ribbon cable 17 will start to wind away from the skirt 14 and onto the spigot 16.

By this means there is achieved a stowing and paying out of the cable in which no twists are introduced into the cable at any time, thus maintaining the integrity of the electrical connections between the cable 13 and the processing circuitry linked to the ribbon cable 17.

An alternative configuration is shown in Figure 2. In this configuration, instead of the skirt being co-rotational with the drum it is the spigot which rotates, while the "skirt" remains stationary. Thus, in Figure 2 the spigot is now made part of the drum 10 and forms a boss 30 thereof, either as an integral extension of the drum itself, or as a separate component secured in a suitable manner to the drum, while the "skirt" takes the form of a short, hollow cylinder 31 which is fixedly attached to equipment bearing the aforementioned signal-processing circuitry. The ribbon cable 17 (not shown in Figure 2) is attached as before at its two ends to the cylinder 31 and the boss 30 and/or flange 12 of the drum. The operation of the invention in this configuration is exactly the same as the operation in the first configuration.

In practice, the overall diameter of the skirt or hollow cylinder and the minimum radius of curvature of the ribbon cable will place a limit on the number of revolutions which can be accommodated in the annular space between the annular members 30, 31, which in turn restricts the length of cable 13 which can deployed or hauled in. In a further development of the invention, this problem is solved by the use of a number of similar ribbon-cable stages working in series, the total number of drum revolutions being then shared between the various stages.

A two-stage arrangement is illustrated in Figure 3. In Figure 3 a first stage comprises a drum boss 30 and a hollow cylinder 31, as in Figure 3, and a second stage comprises an extension of the cylinder 31 and a spigot 32. Ribbon-cable sections 34 and 35 are secured between respective halves of hollow cylinder 31 and the boss 30 and spigot 32, respectively. In a preferred form of the arrangement, the hollow cylinder 31 is made to rotate along with the drum 10 during stowing and paying-out operations, but at a slower speed, preferably at half speed. This can be achieved in a manner to be described later.

The apparatus of Figure 3 is shown in one of its extreme positions, i.e. with the cable either fully stowed or fully deployed. As illustrated, both ribbon cables are wound fully against the hollow cylinder 31 in this position and therefore during movement of the cable to its opposite state the two ribbon-cable sections will move away from the cylinder 31 and towards the boss/spigots 30, 32. In an alternative arrangement, one ribbon-cable section may be wound against the cylinder 31 while the other is wound against the boss or spigot 30, 32 - or vice-versa - in one extreme state of the drum 10.

It is assumed that the cylinder 31 will be moving in the same direction as the drum 10, but at half speed, as mentioned earlier, and so where the two ribbon sections start off wound against the same member (e.g. the cylinder 31), the ribboncable sections will be wound in opposite directions, whereas when the sections start off wound against opposite members (i.e. cylinder 31 and boss 30), they will be wound in the same direction. These two scenarios are illustrated in Figures 4a and 4b, respectively, in which the two stages are shown side by side instead of one behind the other.

In a third embodiment of the invention, three stages are included in the cablestorage apparatus and this is shown in Figure 5.

In Figure 5 the spigot 32 is extended, similar to the cylinder 31 in going from the single-stage to the two-stage arrangement, and the stationary annular member is now a fixed hollow cylinder 36. This time there are three ribbon sections 34, 35 and 37 anchored to their respective pairs of cylinders/spigots and it is assumed that both members 31 and 32 are rotating when the cable is being hauled in or paid out. Speed of rotation in this embodiment is lower with each stage and, in practice, where the drum rotates at speed m, member 31 will be rotating in the same direction at speed 2m/3 and member 32 will be rotating, again in the same direction, at speed m/3. Expressed differently, the relative rotation between stages is m/n for constant rotation.

In the illustration of Figure 5, ribbon sections 34 and 37 start off wound against their respective cylinders 31, 36, whereas ribbon section 35 starts off piled against the spigot 32. In this case the three ribbon sections will be wound in the same direction between their respective annular members (cf. Figure 5b). It is, of course, possible to arrange for section 35 to start off also against the cylinder 31, in which case this section will be counterwound with respect to sections 34 and 37.

A fourth embodiment (see Figure 6) employs yet a further stage comprised of an extension to the cylinder 36, a fixed, stationary spigot 38 and an interposed additional ribbon section 39. As the various ribbon sections are shown in this illustration, sections 34 and 36 will be wound in one direction, while sections 35 and 39 will be wound in the opposite direction. Hollow cylinder 36 is also made to rotate along with annular members 32, and 31, and in this case the various speeds of rotation are arranged to be, working from the boss 30 to the cylinder 39 : m, 3/4 m, Y2 m and'h m. Thus, in the general case, the speeds of the annular members in sequence starting with the member co-rotational with the drum and finishing with the stationary member are defined as: N-a # =m.

N where X = angular velocity, N = no. of stages and a=0, 1, 2,... N.

A preferred method of providing the above differential speeds is to employ a system of reduction gearing driven by the drum. One example of such a gearing mechanism is shown in Figure 7, in which it is assumed that the flange 12 and the outer surface of the hollow cylinder 31 are toothed, or that these items have attached to them toothed wheels.

Engaging with the teeth of these items are respective gear wheels 36, 37 connected to a common shaft. The ratios of the various toothed wheels, etc, are chosen to ensure that the hollow cylinder 31 rotates at half the speed of the drum.

The multi-stage embodiments of the invention may also operate under the control of a gearing system similar to the one just described and with the ratios suitable chosen to ensure the correct relative speeds as outlined earlier. Figure 8 shows an alternative form of the four-stage configuration of Figure 6, in which the hollow cylinder of one stage is attached to the spigot of the next sequentially through the stages, all the spigots being mounted on a common shaft 40 but allowed freely to rotate thereon. Drive of the stages may then readily take place by engagement of the appropriate toothed wheels in teeth provided on the outer periphery of the various hollow cylinders, analogous to the arrangement of Figure 7.

An alternative drive arrangement in the case of the configuration shown in Figure 6, for example, is to drive the spigot 32 using a shaft (not shown) which extends through a central opening in the fixed spigot 38, this shaft being suitably geared to the two hollow cylinders 31, 36.

The speed-reduction mechanism may alternatively involve the use of a belt drive arrangement instead of a gear train.

A less preferred method of controlling the movement of the various stages is to arrange for each stage to transfer its associated ribbon cable fully, or almost fully, onto the unoccupied annular member before allowing the next stage to come into play. This may be achieved by, for example, employing ribbon cables of successively greater stiffness down through the sequence of stages, so that, during the time a particular stage is transferring its ribbon cable onto its previously unoccupied annular member the ribbon cable of the next stage is not set in motion whereas, once transfer is complete for the particular stage, transfer of the next-stage ribbon cable commences. In this system each subsequent stage, when it comes into play, rotates at the same speed as the drum.

This method of control has the drawback of placing the ribbon cable in tension, which may not be desirable, depending on the nature of the ribbon cable involved. An alternative solution is to lock each stage in turn to the drum when a sufficient number of turns of cable have been wound onto/paid out from the drum. Taking the four-stage arrangement of Figure 6 as an example and assuming it is desired to move the cable from one extreme state (e.g. fully deployed) to the other (fully stowed), rotation of the drum will be commenced and, after so many turns which leaves the ribbon cable 34 not fully transferred and therefore unstrained, the hollow cylinder 31 will be locked to the drum so that it rotates with the drum. Ribbon 35 will then start to be transferred to its unoccupied annular member. Similarly, after nominally the same number of turns of cable (assuming ribbon cable 35 has the same number of turns as ribbon cable 34), spigot 32 will be locked to the rotation of the drum allowing ribbon 37 to be transferred, and so on.

This can be achieved in practice by the use of Geneva stops or by an arrangement of mechanical or electrical counters, to count the drum revolutions, and dog clutches, to lock the annular members to the drum.

The Geneva-stop mechanism is illustrated in Figure 9 and comprises a first, driving wheel 50 having a projection 51 and a second wheel 52 having a series of recesses 53 for taking the projection 51 and also a series of concave arcs 54 which mate with the convex curvature of the first wheel 50 and a final, convex, arc 55. Wheel 50 makes, in this example, four revolutions before being prevented from rotating further by the interference between the convex arc 55 and the circumference of the wheel 50.

A simple, representative application of this principle to the invention is shown in Figure 10 and includes the provision of three Geneva stop mechanisms in the 4-stage arrangement of Figure 8. Wheels 50 are fixed to the boss 60 and the other spigots 62, respectively, while wheels 52, which co-operate with wheels 50 as described in Figure 9, are rotatably attached to respective hollow cylinders 65 on an end-face 63 thereof. When sufficient revolutions of the boss/spigot have been performed on any one stage, the wheels 50, 52 on that stage lock and further rotation of the boss/spigot causes corresponding corotation of the hollow cylinder to which wheel 52 is attached.

A greater number of rotations of wheel 50 up to locking may be accommodated by providing a reduction-geared drive (not shown) between the boss/spigot and the wheel 50.

The advantage of using a geared drive, as described earlier, instead of other drive mechanisms such as the Geneva stop is that, because all the elements in the train move simultaneously and at lower speeds than the drum, the kinetic energy in the system is reduced and sudden accelerations, which would otherwise occur if the various stages were brought into operation from standstill, are avoided.

In the various embodiments described so far, it has been assumed that the annular members will be co-axial with the drum. While this is perhaps the most convenient arrangement, it is also possible to cater for an eccentricity in the axis of one or more annular members, should that be necessary in any particular application. An example of this is shown in Figure 11, where a boss or spigot 42 is shown offset from centre by a distance x. The drawing shows the two extreme states of the arrangement in which, in the one case, the ribbon cable is wound fully against the outer hollow cylindrical member (Figure 1 la) and, in the other case, it is wound fully round the eccentric spigot (Figure 1 lib). Operation of the device in this case is similar to that of the co-axial arrangements already covered.

Although the second cable means has been described as being a ribbon cable, other forms of cable, including round-section cable, may be employed. Ribbon cable, however, has the advantage that it will in practice lie flat against the annular members and against itself during winding, whereas the use of, for example, round-section cable may lead to untidy winding and therefore snagging, a strain being thereby imposed on the cable during operation.

Instead of the interface between one stage and the next taking the form of an extension of the relevant annular member (e.g. the hollow cylinders 31 and 36 and the spigot 32 in Figure 6), it may take the form of separate annular members. In that case it is possible, where convenient for the sake of any geared drive used, to arrange for one of the discrete annular-members (corresponding, for example, to the righthand half of cylinder 31) to rotate in the opposite direction to the other (corresponding to the lefthand half of cylinder 31).

While the cable in, say, its fully stowed position may be associated with a ribbon cable wound either against the spigot or against the outer hollow cylinder, it may be preferable to employ a specific one of these ribbon-cable configurations in practice. Thus, it may be found that, where it is desired to ensure optimum speed of payout, it is better to have the ribbon cable wound against the outer cylinder when the cable is fully stowed.

Further, the invention is not restricted to use with electric or fibre-optic cables, but is applicable to any sort of cable. However, it is of greatest use in situations where twisting of the cable is likely to have severe consequences, such as in the transfer of electrical/optical signals. It is also envisaged that the invention could be applied to the paying-out and hauling-in of fluid-carrying conduits, which conventionally require the use of rotary couplings; such couplings could be dispensed with using the present arrangement.

Finally, it is not essential that the annular members be strictly circular in section; other sections, e.g.polygonal, may be used, although it will normally be most expedient, and may result in least wear on the second cable means, to employ circular-cylindrical members.

Claims

CLAIMS 1. Cable-storage apparatus comprising a rotatable drum for the stowing and paying-out of a first cable means, a pair of substantially annular members disposed one at least partly inside the other so as to form an approximately annular space therebetween, one of said pair of substantially annular members being co-rotational with said rotatable drum and the other being stationary, and a second cable means disposed within said approximately annular space and having a first end which is secured to said rotatable drum and is adapted to be attached to one end of said first cable means, and a second end which is secured to said stationary substantially annular member, whereby, in use, rotation of said rotatable drum in one direction causes a winding of said second cable means against one member of said pair of substantially annular members and rotation of said rotatable drum in the other direction causes a winding of said second cable means against the other member of said pair of substantially annular members.
2. Cable-storage apparatus as claimed in Claim 1, wherein said second cable means comprises a plurality of cable sections, there being a pair of substantially annular members associated with each cable section, the pairs of substantially annular members being disposed in series such that one member of each pair is co-rotational with one member of the succeeding pair, a first cable section being secured at one end to said rotatable drum and at the other end to the member of its associated pair of substantially annular members which is not co-rotational with said rotatable drum, and the remaining sections being secured at their ends to their respective pairs of substantially annular members.
3. Cable-storage apparatus as claimed in Claim 1 or Claim 2, wherein, in use, all of said substantially annular members except said stationary member rotate simultaneously.
4. Cable-storage apparatus as claimed in Claim 3, wherein one member of each pair of substantially annular members rotates at a higher speed than the other member of that pair.
5. Cable-storage apparatus as claimed in Claim 4, comprising N cable sections and N pairs of substantially annular members, wherein said rotatable drum, in use, rotates at speed m and the faster-rotating members of the pairs of substantially annular members rotate at the following speeds, in order: N-1 N-1 N-2 m m, m. , m. , ...

N N N
6. Cable-storage apparatus as claimed in Claim 4 or Claim 5, wherein the slowerrotating member of a pair of substantially annular members and the faster-rotating member of a succeeding pair of substantially annular members are constituted by the same member, said same member being of sufficient axial dimensions to accommodate both the associated cable sections.
7. Cable-storage apparatus as claimed in any one of Clairns 2 to 6, wherein said annular members are rotated through a reduction-gearing mechanism
8. Cable-storage apparatus as claimed in Claim 2, wherein each cable section is allowed to wind at least partly against the relevant member of its associated pair of substantially annular members before succeeding cable sections are allowed to start winding.
9. Cable-storage apparatus as claimed in Claim 8, wherein control of the substantially annular members is achieved by means of a Geneva stop mechanism.
10. Cable-storage apparatus as claimed in Claim 8, wherein control of the substantially annular members is achieved by means of a clutch mechanism.
11. Cable-storage apparatus as claimed in Claim 10, wherein said clutch mechanism is a slipping clutch mechanism.
12. Cable-storage apparatus as claimed in Claim 8, wherein control of the substantially annular members is achieved in that the cable section of each successive stage is of successively greater stiffness.
13. Cable-storage apparatus as claimed in any one of the preceding claims, wherein said substantially annular members are co-axial with said rotatable drum.
14. Cable-storage apparatus as claimed in any one of Claims 1 to 12, wherein at least one of said substantially annular members has an axis offset from that of said rotatable drum.
15. Cable-storage apparatus as claimed in Claim 1, wherein the stationary substantially annular member is disposed within the rotatable substantially annular member, said rotatable substantially annular member being attached to said rotatable drum.
16. Cable-storage apparatus as claimed in Claim 15, wherein said rotatable substantially annular member is constituted by a skirt extension of said rotatable drum.
17. Cable-storage apparatus as claimed in Claim 1, wherein the rotatable substantially annular member is disposed within said stationary substantially annular member and is constituted by a boss extension of said rotatable drum.
18. Cable-storage apparatus as claimed in any one of the preceding claims, wherein said first and second cable means are electrical and/or fibre-optic cables.
19. Cable-storage apparatus as claimed in any one of Claims 1 to 17, wherein said first and second cable means are conduits for the conveying of fluid.
20. Cable-storage apparatus sustantially as shown in, or as hereinbefore described with reference to the drawings.