WO2020099889A1

WO2020099889A1 - A telescopic connector

Info

Publication number: WO2020099889A1
Application number: PCT/GB2019/053247
Authority: WO
Inventors: George TERRY
Original assignee: Zodiac Interconnect Uk Limited
Priority date: 2018-11-16
Filing date: 2019-11-15
Publication date: 2020-05-22
Also published as: WO2020099883A1; WO2020099896A1; WO2020099881A1

Abstract

A telescopic connector (9) in accordance with the present invention may be used to accommodate a small shortfall in the length of an electrical cable, relative to the location of an item of electrical equipment, or similar, to which the electrical cable is to be connected.

Description

A Telescopic Connector

The present invention relates to an electrical connector that is particularly, but not exclusively, suitable for use in the assembly of an aircraft.

More and more electrical equipment is being used on aircraft, where reliable relatively light and compact electrical motors and actuators may be used instead of the more conventional and heavier mechanical and hydraulic actuators.

The extensive use of electrical equipment in modern aircraft, particularly large commercial aircraft, results in many electrical connections having to be made with numerous terminal blocks and other items of electrical equipment, each of which has to be made in a safe and reliable manner.

Currently electrical power in an aircraft is normally distributed by connecting cables terminated with crimped ring terminals to be connected to terminal blocks or other electrical equipment. In the case of terminal blocks, as for example the terminal block 1 shown in Figure 1 , these typically embody a fixed number of threaded posts 2, overmolded with plastic insulation 3, with the terminal blocks fixed to the aircraft structure by bolts on either end. Power distribution is achieved by placing one or more ring terminals 4 to 6 onto at least one post 2 of a terminal block, as shown in Figure 2. The ring terminals 4 to 6 are then fastened to the post 2 with a washer 7 and nut 8, by a manual torqueing operation.

Items of aerospace equipment often feature similar terminations for power input/output connections. These will typically comprise a threaded post, similar to the threaded post 2 of Figure 2, on the external part of the equipment attached to an internal busbar.

Making electrical connections to conventional terminal blocks and other aircraft electrical equipment is a relatively time consuming process. The torqueing operating, together with the use of crimped ring terminals in general, can often cause delays in installation and may also result in reworking being necessary. This may arise due to issues such as the ring terminals being misaligned, or as a result of damage occurring to the ring terminal from the torqueing tool, which may require a new ring terminal to be crimped to a cable, which in turn may require the reworking of a harness installation to adjust for the reduced available cable length.

Other problem that may arise when connecting cables to a conventional terminal block is that there may be potential FOD issues, arising from the use of loose washers and nuts and the risk of incorrectly connecting different power phases when using conventional ring terminals together with the risk of coming into contact with exposed electrically live components.

Co-pending applications filed by the present applicant address some of the aforementioned issues and these disclose the use of a pin assembly to be received into a socket assembly, which socket assembly may for example form part of a terminal block or be attached to an item of equipment. These may provide a reliable quick connect/disconnect connector, which may be arranged to permit relative rotation between a cable attached to the pin assembly and the socket assembly attached to the terminal block or item of equipment, to avoid a torque being placed on that cable. However, neither ring terminals nor the

aforementioned socket assembly/pin assembly arrangements address issues arising due to cables not being long enough to reach the terminal block, or being slightly too long, resulting in it being difficult to correctly align them.

Although incorrect cable lengths may arise in all sorts of applications, they can be particularly problematic when installing a power distribution network on board on an aircraft, where cables have to be precisely routed. The cables will normally be laid together, or assembled together as a cable bundle, where the cables, although not bound together to form a harness, effectively form a harness by running together through common P-clips and cable clamps used to secure the cable bundle. On board an aircraft such cables of a cable bundle may supply high power equipment aboard aircraft, such as batteries, distribution boxes, inverters, generators, e-taxi, e-brake, with the use of high power equipment steadily increasing as electric motors and actuators are used instead of conventional hydraulic and pneumatic equipment. The requirement to distribute large amounts of power, supplied at the relatively low voltages used aboard an aircraft, means that the power cables can be relatively thick and inflexible. Thus where a cable, due to tolerances during manufacturing and/or routeing during assembly, is too short to reach a terminal block, or slightly too long, then it may not be possible to gain or lose the necessary cable length, without a lengthy rework procedure, to release all the P-clips and cable clamps securing the cable bundle, up to the extra cable loop, which is typically located at one end of the cable bundle.

In such a situation it may be possible to rework the offending cable along the length of the cable bundle, to gain the necessary extra length. However, the other cables in the bundle may be dragged along with the offending cable, resulting in these other cables then being too long and having to be bent in some manner to lose the additional length. Where this is not acceptable, the terminals from the ends of the cables might need to be removed, the cables shortened and appropriate terminals refitted before the P-clips and cable clamps are reassembled to secure the cable bundle. It will be appreciated that this may be a lengthy process and thus such an occurrence may significantly delay installation of power distribution equipment aboard an aircraft.

In addition to the above, as previously mentioned, ring terminals can be damaged during installation, or they can be damaged after installation. Where this happens it may be necessary to replace the ring terminal, but as a cable is normally crimped to a ring terminal it will normally be necessary to cut the ring terminal and crimp off the cable, together with the short portion of cable within the crimp. The cable will then need to be paired back and crimped to a new ring terminal, which may result in that cable being too short and thus again result in the cable having to be pulled through the cable bundle, encountering the issues previously mentioned.

It is an object of the present invention to provide an improved connector which addresses the above mentioned problems.

According to the first aspect of the present invention there is provided a telescopic connector for connecting a power cable to an electrical item, the telescopic connector comprising first and second electrically conducting

components, one of which is arranged to be connected, both mechanically and electrically, to a power cable and one of which is arranged to be connected, both mechanically and electrically, to an item of electrical equipment, wherein the first and second components are arranged to be releasably connected together to establish a mechanical and an electrical connection between a power cable and an electrical item, characterised in that:

the first component comprises a first electrically conducting portion arranged to be connected, both mechanically and electrically to one of either a power cable or an electrical item and a second portion arranged to releasably connect, both mechanically and electrically to the second component, wherein the first portion and second portions are retained together, but wherein the first portion is arranged to slide a limited distance relative to the second portion, while maintaining electrical contact between the first and second portions, such that when the second component is connected to a power cable or an electrical item and the first portion of the first component is connected to the other of a power cable or an electrical item, the connector permits the relative separation between any such power cable and electrical item to be varied to a limited extent, while maintaining electrical contact between the two.

The present invention enables any minor discrepancy between the length of a cable and a connection point on a terminal block, or other item of electrical equipment, to be accommodated by the telescopic connector of the invention. Thus multiple such connectors may be particularly advantageous for terminating the cables of a cable bundle, for example power cables on board an aircraft, thus addressing at least some of the aforementioned issues.

Preferably one of the first or second portions of the first component is an inner portion and slides on the other of the of the first and second portions, which is an outer portion, wherein the inner portion has a recess or protrusion, which when inside the outer portion is retained in the outer portion by a retaining element to prevent the first portion from disengaging from the second portion.

The above arrangement may provide for a particularly compact telescopic connector, especially where the inner portion is in the form of a pin with a circular cross section, the outer portion has a circular bore in which the inner portion may slide and wherein the first component further comprises an electrically conducting annular contact band extending around the inner portion, providing a plurality of evenly distributed electrical contact points around the periphery of the inner portion, between the inner and outer portions, which are maintained irrespective of the position of the inner portion within the outer portion. The contact band thus ensures a low resistance connection between the two telescopic portions of the connector, irrespective of their relative positions.

Preferably the inner portion is in the form of a pin with a circular cross section, the outer portion has a circular bore in which the inner portion may slide, wherein the first component further comprises a sleeve located between inner and outer portions, wherein the sleeve is arranged to slide a first limited distance on the inner portion and the outer portion is arranged to slide a second limited distance on the sleeve, such that the outer portion may be displaced relative to the inner portion by a distance equal to the sum of the first and second distances. This arrangement provides a two stage telescopic action, permitting a greater extension to be achieved for a given length of telescopic connector. Alternatively multiple coaxial sleeves may be used to provide a three, or even a four, stage extension. In one embodiment the first portion is arranged to attach to a cable at a first end and is in the form of a pin at a second end, the second end being arranged to be received in a bore of the second portion, the second portion being in the form of a hollow pin arranged to be received in and retained by a socket in the second component. This reflects the normal convention of cable terminations being received in a fixed socket, but the invention is equally applicable to an extendable telescopic socket provided on the end of a cable to be attached to a fixed pin, or to a telescopic pin (or socket) arranged to be mounted to an item of equipment to receive a socket (or pin) on the end of a cable, for all such arrangements are functionally equivalent in that they provide an extension piece between a cable and an item of equipment and the invention, in it’s broadest sense, encompasses all of these alternatives.

The second component may further comprise an electrically insulating annular housing arranged to be rotatably retained on and extend over the second portion, so that the second portion may rotate in the housing. This may help to avoid contact with live parts. The housing could also be used to provide a second mechanical connection with a socket assembly, or similar and may provide a means of retaining the first component in engagement with the second component.

The first component may further comprise a relatively flexible boot extending from the housing to a cable secured at a first end of the first portion, the boot comprising an outer section secured to the housing and an inner section secured to the first portion, the inner section extending under the outer section in a telescopic manner, such that the inner section of the boot may be withdrawn from under the outer section by the action of the first portion moving axially relative to the second portion.

The first end of the first portion may be arranged to engage with a cable by having an integral crimp for crimping to an electrical conductor of a cable, but any other suitable means, such as soldering or braising, could be used instead. The second component may comprise a metal socket connector having a socket at a first end for receiving the second portion of the first component at any angular rotation and to permit the second portion to rotate in the socket. This arrangement may ensure that no axial torque is placed on a cable by the telescopic connector being connected to a fixed electrical item.

The second component preferably comprises a releasable locking means for releasably locking the second portion of the first component within the socket when the second portion is inserted into the socket beyond a lock point. The advantage of this is that that a cable may be retained in place by the metal components of the telescopic connector, with the cable mechanically locked, via the telescopic connector to the item of equipment and possibly directly to a busbar of that item of electrical equipment, preventing the telescopic connector and cable from becoming disconnected, even if an exceptional tensile force should be experienced by the cable.

One way in which such a locked but releasable connection may be achieved is where the second portion has to be pushed into the socket beyond the lock point to a release point, before the second portion can be released and withdrawn from the socket. This can be achieved by an arrangement where the second component further comprising a radially expandable or compressible lock ring located in a first groove on an inner surface of the socket, or on an outer surface of the second component, and a slide ring, the slide ring being arranged to slide axially in a second groove on either an outer surface of the second component or an inner surface of the socket wherein, when the second component is pushed into the socket to the lock point, the lock ring expands or contracts to extend into the second groove, preventing the second component from being withdrawn from the socket, and wherein, when the second component is pushed into the socket to the release point, the slide ring is forced between the second groove and the lock ring, pushing the lock ring out of the second groove to release the lock ring from the second groove to allow the second component to be withdrawn from the socket. The telescopic connector may have a retaining mechanism acting directly or indirectly between the first and second portions to act to retain them in one of a number of incremental axial positions relative to each other. This may prevent unnecessary and undesirable movement due to, for example, vibration, which could otherwise cause unnecessary wear on components such as any electrical contact band. This retaining mechanism may be achieved by the aforementioned sections of the boot having engaging pips, ridges, grooves or similar, to act to retain the two sections together at one of a number of incremental positions and thus retain the two portions of the first component together in one of a number of incremental positions.

The second component may be arranged to be fixed to an electrical item by having a threaded portion arranged to be secured to a busbar of a terminal block or other item of electrical equipment.

One or more telescopic connectors as discussed above may have particular application to a power distribution system. This may be particularly the case where that power distribution system is aboard an aircraft and comprises a cable bundle having a plurality of cables connected to a terminal block, or other item of electrical equipment, by a plurality of telescopic connectors as discussed above, permitting faster assembly and reducing the reworking likely to be required.

Various embodiments of the present invention will now be described, by way of example only, with reference to the accompanying figures, in which like numerals are used throughout to indicate like parts, and in which:

Figure 1 is a perspective view of a known type of terminal block;

Figure 2 is a side elevation showing a number of ring connectors attached to a post of a known terminal block;

Figure 3 is a perspective view showing three socket assemblies mounted to a busbar;

Figure 4 is a perspective view showing three socket assemblies, similar to those of Figure 3, mounted on an alternative type of busbar; Figure 5 is a perspective view of a socket assembly having an insulated socket housing;

Figure 6 is a perspective view of a socket, without a socket housing;

Figure 7 is a perspective view of a first embodiment of a telescopic connector in accordance with the present invention;

Figure 8 is a section through the telescopic connector of Figure 7, shown in an unextended state and attached to the socket of Figure 6;

Figure 9 corresponds to Figure 8, but shows the telescopic connector in an extended state;

Figure 10 corresponds to Figure 8, but is to an enlarged scale and shows the telescopic connector with the socket removed;

Figure 11 corresponds to Figure 9, but to an enlarged scale and shows the telescopic connector with the socket removed;

Figure 12 is a section through a second embodiment of a telescopic connector in accordance with the present invention, in an unextended state, the telescopic connector having an insulated housing and is shown connected to the socket assembly of Figure 5;

Figure 13 corresponds to Figure 12, but shows the telescopic connector in an extended state;

Figure 14 shows the telescopic connector of Figure 12 to an enlarged scale and with the socket assembly removed;

Figure 15 shows the telescopic connector of Figure 13 to an enlarged scale and with the socket assembly removed;

Figure 16 is a side section through of a third embodiment of a telescopic connector in accordance with the present invention, in an unextended state, which telescopic connector is also arranged to connect to the socket assembly of Figure 5;

Figure 17 is a planer section through the telescopic connector of Figure 16;

Figure 18 correspond to Figure 16 but shows the telescopic connector in a partially extended state;

Figure 19 corresponds to Figures 16 and 18, but shows the telescopic connector in a fully extended state; Figure 20 correspond to Figure 17, but shows the telescopic connector in a fully extended state;

Figures 21 to 24 are partial sections through the socket assembly and telescopic connector of Figure 12 showing various stages during the

disengagement of the telescopic connector from the socket assembly;

Figure 25 is a perspective view of a contact band of the type used in the socket assembly of Figures 5, the socket of Figure 6 and in the telescopic connectors of Figure 8, 12 and 16;

Figure 26 is a side elevation of the contact band of Figure 25;

Figure 27 is a section through the socket assembly of Figure 5, showing the contact band of Figures 25 and 26; and

Figure 28 is an end elevation of the socket assembly of Figure 27;

Referring now to Figure 1 , a terminal block indicated generally as 1 , has a plurality of posts 2 encapsulated in an insulating base 3, to permit one or more ring terminals 4 to 6 to be mounted to each post and secured in place by a washer 7 and nut 8, in a known manner, as shown in Figure 2.

Referring to Figure 3, this shows how socket assemblies 9 may be attached to a busbar 10A of a piece of electrical equipment, or forming part of a terminal block, to permit quick connect/disconnect of associated pin assemblies (not shown), which is the subject-matter a co-pending application in the name of the present applicant.

Figure 4 shows socket assemblies 11 , similar to the socket assemblies 9 of Figure 3, attached to a busbar 10B having a circular cross section. The socket assemblies 11 could however also be mounted to a post 2 of the terminal block 1 illustrated in Figure 1 , or to a post of some other type of electrical equipment.

Figure 5 shows one of the socket assemblies 9 of Figure 3 to an enlarged scale. This comprises an insulated socket housing 12 extending over a socket connection 13, the socket connection 13 having a socket at one end, for receiving a pin connector, and a threaded portion 14 at the other end, for attaching to the busbar 10A of Figure 3, or similar.

Referring to Figure 6, here an alternative socket 15 is shown which may be used instead of the socket assembly of Figure 5. This again has a threaded portion 16 for engaging with the busbar 10A of Figure 3, but this socket 15 does not have an insulated socket housing.

Referring now to Figure 7, here there is shown a first embodiment of a telescopic connector 17 in accordance with the present invention, with Figures 8 and 9 showing the telescopic connector 17, in section, connected to the socket 15 of Figure 6, with the telescopic connector 17 shown in an unextended and extended state respectively.

These Figures are provided, by way of example only, to illustrate the function of a telescopic connector of the present invention and it should be appreciated that a telescopic connector in accordance with the present invention may connect to various different types of sockets and /or terminals, including ring terminals. Therefore the sockets 15 and 9, shown and discussed in the present specification, should be considered only as examples of fixed points to which a telescopic connector in accordance with the present invention may be connected to. Similarly, the telescopic connectors shown and discussed with reference to Figure 7 to 9, as well as the other Figures of the present specification, are all shown as pin connectors, or pin assemblies, for connecting with a socket such as socket 15 of Figure 6, or a socket assembly, such as the socket assembly 9 of Figure 5. This though is again for illustrative purposes only, as the telescopic connector of the present invention could equally form part of a socket, as for example a socket such as socket 15 of Figure 6, or socket assembly 9 of Figure 5, or it could form part of some other type of cable terminal, for example a ring terminal. Thus the invention is not limited to any particular connection type, however, for completeness, the connection between a socket 9 of Figure 5 and a telescopic connector 29 of Figure 12 is described in detail subsequently, with reference to Figures 21 to 28.

Figure 10 shows, to an enlarged scale, the telescopic connector 17 of Figure 8. The telescopic connector 17 comprises an outer pin 18, arranged to engage and be retained in the socket 15 of Figure 6. The telescopic connector 17 further comprises an inner pin 19 slidable in a central bore 20 of the outer pin 18. The inner pin 19 terminates at a proximal end 21 with a crimp portion 22, which is crimped to the conductive core 23 of a cable 24.

An inner wall of the outer pin 18 has an annular recess 25, in which there is retained an annular contact band 28, of the type described more fully below, with reference to Figures 25 to 28. The contact band 28 is a metallic spring which acts as an electrical contact element between the outer pin 18 and the inner pin 19, both of which are metallic, and therefore provides a conductive path between the conductive core 23 of the cable 24 and the outer pin 18, to be connected to the socket 15.

The inner pin 19 has two opposed notches 26 in its outer surface, which extend along either side of a mid-portion of that outer surface. The notches 26 receive respective ones of a pair of limiting pins 27, which each extend through the outer pin 18. (One of the limiting pins 27 can just be seen inserted through the outer pin 18, in the perspective view of Figure 7). The notches 26, together with the limiting pins 27, limit axial moment of the inner pin 19 relative to the outer pin 18, between an unextended state shown in Figure 10 and an extended state shown in Figure 11.

The contact band 28 ensures that a good electrical contact is maintained between the inner pin 19 and the outer pin 18, irrespective of the axial position of the inner pin 19 relative to the outer pin 18. This relatively small amount of axial movement of the inner pin 19 (fixed to the cable 24), relative to the outer pin 18 (retained in the fixed socket 15) may, for example, be sufficient to ensure that each cable of a cable bundle, crimped or otherwise retained in a telescopic connector 17, may correctly engage with a socket, such as socket 15 of Figure 6, fixed to a piece of equipment or forming part of a terminal block, or similar, the telescopic connector 17 accommodating permissible tolerances in the length of an associated cable, possibly resulting from manufacture or installation of the cable in a cable bundle.

The telescopic connector 17 of Figures 7 to 11 and the associated socket 15 of Figure 6, thus far described, are all formed from metal and thus, when

connected to a“live” electrical source, have bare“live” outer surfaces, which may be not be permissible in some applications.

Two further embodiments of telescopic connectors in accordance with the present invention will now be described with reference to Figures 12 to 20, where telescopic connectors in accordance with the present invention have outer electrically insulating housings and which are arranged to engage with a socket assembly 9 of Figure 5, which, as can be seen from Figure 12, has an insulated socket housing 12 extending over a metal socket connector 13 and a plastic socket cap 30 electrically insulating both the outer surface and the distal end of the socket connector 13.

Figure 12 shows a second embodiment of a telescopic connector 29 in an unextended state, connected to the socket assembly 9 and Figure 13 shows how it may be extended to an extended state. Thus, thus telescopic connector 29 provides the same benefits as with the previously described telescopic connector 17 of Figures 7 to 11.

Figure 14 shows the unextended telescopic connector 29 of Figure 12 to an enlarged scale. From this is can be seen that the telescopic connector 29 comprises an inner pin 31 having a crimp portion 32 by which it is crimped to a conductive core of a cable 33. The inner pin 31 is received in a central bore 34 of an outer pin 35 and is retained in place by a pair of limiting pins 36, engaging with notches 37 on opposed sides of the central pin 31. The outer pin 35 has a groove 36 retaining a contact band 38, maintaining electrical contract between the inner pin 31 and outer pin 35, all in the same manner as with the previously described embodiment.

The distal end of the outer pin 35 has an electrically insulating cap 39 screwed into it, to electrically insulate the tip of the outer pin 35. The outer pin 35 has a pin housing 40 rotatably mounted on a shoulder 41 of the outer pin 35 and placed against an annular flange 42 of the outer pin 35. To a proximal end 43 of the pin housing 40 is secured a first crimp boot 44, by means an annular snap 45, which engages with the proximal end 43 of the pin housing 40, acting to retain the pin housing on the flange 42 of the outer pin 35. The first crimp boot 44 is thus retained in place on the outer pin 35, but the pin housing 40 may rotate relative to both the outer pin 35 and first crimp boot 44. In this manner, although not shown in Figure 14, the pin housing 40 could have an inner keyway arranged to engage with lugs on an outer surface of a socket housing 9, to provide a secondary locking feature between the socket assembly 9 and telescopic connector 29.

Referring again to Figure 14, this also shows a second crimp boot 46 extending over the crimp portion 32 of the inner pin 31 and over an insulating sleeve 47 of cable 33. The second crimp boot 46 extends under the first crimp boot 44 and thus, together with the pin housing 40 and socket housing 12 of the socket assembly 9, may provide a totally insulated telescopic connection between the cable 24 and the socket assembly 9.

The second crimp boot 46 is axially extendable and retractable relative to the first crimp boot 44, to permit the inner pin 31 to move from the unextended position in Figure 14 to the extended position shown in Figure 15. Flowever, the outer surface of the second crimp boot 46 is provided with a series of

circumferential grooves 48, as shown in Figure 15, a respective one of which will engage with an annular ridge 49 on the inner surface of the first crimp boot 44.

The annular ridge 49 and circumferential grooves 48 do not prevent the telescopic action of the telescopic connector 29, but they act to prevent minor changes which may result for example from vibration, which could otherwise unnecessarily cause wear to the contact band 38.

Where it is desired to provide a telescopic connector with a greater telescopic extension than is possible with the previously described embodiments, in order to accommodate greater variations in cable lengths of a cable bundle, for example, then the extendable length of telescopic connector 17 of Figures 10 and 11 , or of the telescopic connector 29 of Figure 12 could be increased. This could be achieved by extending the length of the telescopic connector 17 or 29 and the length of the notches 26 or 37 in the outer surface of the inner pin 19 or 31.

Flowever, this may result in the overall length of the telescopic pin 17 or 29, in an unextended position, being unacceptable.

This is addressed by the embodiment disclosed in Figures 16 and 17, which are side and plan sections respectively of a telescopic connector 50 having a two stage extension (although a three stage extension would also be possible). This telescopic connector 50 is very similar to the insulated telescopic connector just described with reference to Figures 12 to 15 and thus only those features that differ are discussed below.

With reference to Figures 16 and 17, an outer pin 51 of telescopic connector 50 has an inner bore with a rear section 52 of a significantly greater diameter than a front portion 53. This larger diameter rear portion 52 accommodates a cylindrical sleeve 54 between the outer surface of the inner pin 31 and the inner surface of the larger diameter rear portion 52 of the bore of the outer pin 51. The sleeve 54 may slide relative to the inner pin 31 and the outer pin 51 and is retained in place on the inner pin 31 by a first pair of limiting pins 55 inserted in the cylindrical sleeve 54 engaging with the notches 37 on the opposed sides of the inner pin 31.

Electrical contact between the cylindrical sleeve 54 and inner pin 31 is maintained by a contact band 59A retained in an annular recess 56 on the inner surface of the cylindrical sleeve 54.

Referring now to Figure 17, a plan section of the telescopic connector 50, shown in side section in Figure 16, this shows two notches 57 in opposed sides of the cylindrical sleeve 54. A second pair of limiting pins 58, secured in the outer pin 51 , engage with the notches 57, permitting limited axial displacement of the cylindrical sleeve 54 relative to the outer pin 51. A contact band 59B, retained in an annular recess 60 on an inner surface of the outer pin 51 , maintains electrical contact between the sleeve 54 and the outer pin 51.

Figures 16 and 17 described above show the inner pin 31 and cable 33 of the telescopic connector 50 in an unextended state, Figure 18, corresponding to Figure 16, shows the inner pin 31 and cable 33 of the telescopic connector 50 in a partially extended state and Figures 19 and 20, corresponding to Figures 16 and 17 respectively, show the inner pin 31 and cable 33 of the telescopic connector 50 in a fully extended state.

From Figure 20 it can be seen that, in this third embodiment, the second pair of limiting pins 58 in the outer pin 51 , (which is held in the socket assembly 9), engaging with the respective notches 57 in the cylindrical sleeve 54, permit the cylindrical sleeve to travel a first distance relative to outer pin 51 and thus relative to the socket assembly 9. This first distance is equal to the extension obtained with the previous embodiments. Flowever, in this third embodiment, as will be apparent from Figure 19, the first pair of limiting pins 55 in the cylindrical sleeve 54, engaging with respective notches 37 on the inner pin 31 , also permit axial movement of the inner pin relative to the cylindrical sleeve 54 to the same extent again. Thus cable 33, fixed to the inner pin 31 , may move twice the distance relative to a fixed socket assembly 9 than is possible with the previously described embodiments, illustrated in Figures 7 to 15. Although the invention has been described above in relation to a telescopic connector having a pin suitable for connecting to a socket, for example the sockets 9 and 11 of Figures 3 and 4, it is to be remembered a similar telescopic

arrangement could be used as part of one of the sockets 6 or socket assemblies 5 shown in Figures 3 to 4 or this could form part of a conventional ring terminal or other type of connector.

In the previously described embodiments, the outer pin could be a push fit in the socket or socket assembly and be retained in place by frictional forces.

Flowever, an outer pin and socket, or socket assembly, of any of the previously described embodiments can be arranged to accommodate a locking mechanism to prevent the outer pin being pulled out of the socket, or socket assembly, and such a locking mechanism will now be described with reference to Figures 21 to 24.

Referring to Figure 21 , this shows to an enlarged scale the distal end of the telescopic connector 29, of Figures 12 for example, and associated socket assembly 9 prior to engagement. The socket assembly 9 has a socket connector 13 forming a socket 61 , which socket 61 has an annular groove 62 in which is retained an expandable split lock ring 63, omitted for clarity from the previous figures. The socket 61 also has an annular recess 60, in which is retained an annular contact band 59. The contact band 59 is described below in greater detail with reference to Figures 25 to 28.

The telescopic connector 29, shown in Figure 21 , is as previously described with reference to Figure 12 and has an outer pin 35 with an annular groove 64 in its outer surface. In the annular groove 64 is located a slide ring 65, omitted for clarity from the previous Figures, which may slide axially within the annular groove 64.

On insertion of the outer pin 35, in the socket 61 , as shown in Figure 22, the lock ring 63 displaces the slide ring 65 to the right, as shown in Figure 22, and snaps into the annular groove 64, preventing the outer pin 35 from being

disconnected from the socket connector 13 of the socket assembly 9. To disconnect the outer pin 35 from the socket connector 13 and thus to disconnect the telescopic connector 29 from the socket assembly 9, the telescopic connector 29 has to be pushed into closer contact with the socket assembly 9, as shown in Figure 23, forcing the slide ring 65 under the lock ring 63, which substantially non-compressible slide ring 65 is then dragged to the left, as shown in Figure 23, maintaining the lock ring 63 in the expanded position shown in Figure 23 and permitting the telescopic connector 29 to be removed from the socket assembly 9, as shown in Figure 24.

Referring now to Figures 25 to 28 these show one example of a contact band 59 and its location within the socket 61 of the socket assembly 2 of the previous Figure 21. The contact band 59 is stamped from a thin sheet of metal to have the form indicated in Figures 25 and 26, with a plurality of upstanding blade contacts 66. The contact band 59 is assembled in the socket 61 of the socket assembly 9, as shown in Figure 27, such that the blade contacts 66 protrude inwardly, as shown in Figure 28. As will be appreciated from Figure 28, when the outer pin 55 of the telescopic connector 29 is pushed into the socket 61 , the blade contacts 66 will be forced outwardly to permit the outer pin 35 to be accommodated in the position shown in Figure 22, for example. In this position the blade contacts 66 are held in compression against the natural resilience of the metal of the contact band. This ensures every contact blade will establish a secure electrical contact with the outer pin 35, even during any slight variations in the axial or lateral positions of the outer pin 35 within the socket 61 and regardless of the angular position of the outer pin 35 within the socket 61 , or any rotation that may occur between the two. The blade contacts 47 also function as resistors in parallel reducing the bulk resistance of the connection.

All the contact bands mentioned with reference to the previously described embodiments may be the same or similar to the one shown in Figure 25 to 28. The above embodiments of the invention have been described by way of example only and it should be appreciated that many further modifications may be made without departing from the scope of the invention, as defined by the following claims.

Claims

1 . A telescopic connector for connecting a power cable to an electrical item, the telescopic connector comprising first and second electrically conducting

components, one of which is arranged to be connected, both mechanically and electrically, to a power cable and one of which is arranged to be connected, both mechanically and electrically, to a terminal block or other item of electrical equipment, wherein the first and second components are arranged to be releasably connected together to establish a mechanical and electrical connection between a power cable and an electrical item, characterised in that:

2. A telescopic connector as claimed in Claim 1 wherein one of the first or second portions of the first component is an inner portion and slides in the other of the first and second portions, which is an outer portion, wherein the inner portion has a recess or protrusion, which when inside the outer portion is retained in the outer portion by a retaining element to prevent the first portion from disengaging from the second portion.

3. A telescopic connector as claimed in Claim 2 wherein the inner portion is in the form of a pin with a circular cross section, the outer portion has a circular bore in which the inner portion may slide and wherein the first component further comprises an electrically conducting annular contact band extending around the inner portion, providing a plurality of evenly distributed electrical contact points around the periphery of the inner portion, between the inner and outer portions which contact points are maintained irrespective of the position of the inner portion relative to the outer portion.

4. A telescopic connector as claimed in Claim 2 or 3 wherein the inner portion is in the form of a pin with a circular cross section, the outer portion has a circular bore in which the inner portion may slide, wherein the first component further comprises a sleeve located between inner and outer portions, wherein the sleeve is arranged to slide a first limited distance on the inner portion and the outer portion is arranged to slide a second limited distance on the sleeve, such that the outer portion may be displaced relative to the inner portion by a distance equal to the sum of the first and second distances.

5. A telescopic connector as claimed in any preceding claim wherein the first portion is arranged to attach to a cable at a first end and is in the form of a pin at a second end, the second end being arranged to be received in a bore of the second portion, the second portion being in the form of a hollow pin arranged to be received in and retained by a socket in the second component.

6. A telescopic connector as claimed in Claim 5 wherein the second portion further comprises an electrically insulating annular housing arranged to be rotatably retained on and extend over the second portion, so that the second portion may rotate in the housing.

7. A telescopic connector as claimed in Claim 6 wherein the first component further comprises a relatively flexible boot extending from the housing to a cable secured at a first end of the first portion, the boot comprising an outer section secured to the housing and an inner section secured to the first portion, the inner section extending under the outer section in a telescopic manner, such that the inner section of the boot may be withdrawn from under the outer section by the action of the first portion moving axially relative to the second portion.

8. A telescopic connector as claimed in Claim 5, 6 or 7 wherein the first end of the first portion has an integral crimp for crimping to an electrical conductor of a cable.

9. A telescopic connector as claimed in any preceding claim wherein the second component comprises a metal socket connector having a socket at a first end for receiving the second portion of the first component at any angular rotation and to permit the second portion to rotate in the socket.

10. A telescopic connector as claimed in any preceding claim wherein the second component comprises a releasable locking means for releasably locking the second portion of the first component within the socket when the second portion is inserted into the socket beyond a lock point.

11. A telescopic connector as claimed in Claim 10 wherein the second portion has to be pushed into the socket beyond the lock point to a release point, before it can be released and withdrawn from the socket.

12. A telescopic connector as claimed in Claim 11 wherein the second component further comprising a radially expandable or compressible lock ring located in a first groove on an inner surface of the socket, or on an outer surface of the second component and a slide ring, the slide ring being arranged to slide axially in a second groove on either an outer surface of the second component or an inner surface of the socket wherein, when the second component is pushed into the socket to the lock point, the lock ring expands or contracts to extend into the second groove, preventing the second component from being withdrawn from the socket, and wherein, when the second component is pushed into the socket to the release point, the slide ring is forced between the second groove and the lock ring, pushing the lock ring out of the second groove to release the lock ring from the second groove to allow the second component to be withdrawn from the socket.

13. A telescopic connector as claimed in any preceding claim comprising a retaining mechanism acting directly or indirectly between the first and second portions to act to retain them in one of a number of incremental axial positions relative to each other.

14. A telescopic connector as claimed in any preceding Claim wherein the second component has a threaded portion arranged to be secured to a busbar of a terminal block or other item of electrical equipment.

15. A power distribution system comprising one or more telescopic connectors as claimed in any preceding Claim.

16. An aircraft comprising a cable bundle having a plurality of cables connected to a terminal block, or other item of electrical equipment, by a plurality of telescopic connectors as recited in any one of Claims 1 to 15.