An Electrical 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 very 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 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, these typically embody a fixed number of threaded posts, overmolded with plastic insulation, with the terminal blocks fixed to the aircraft structure by bolts on either end. Power distribution is achieved by stacking multiple ring terminals onto at least one post of a terminal block. The ring terminals are then fastened to the post with a nut by a manual torqueing operation. The terminal blocks are often protected with a plastic cover to protect from foreign object debris (FOD) and prevent operators touching live parts. These covers are fixed to the terminal block with quarter turn bolts secured with lock wire.

Items of aerospace equipment often features a similar termination for power input/output connections. This will typically comprise a threaded post on the external part of the equipment attached to an internal busbar. When the feeder cable is secured to the post with a nut, it delivers power to the internal equipment via the busbar. Making electrical connections to conventional terminal blocks and other aircraft electrical equipment is a relatively time consuming process because securing the ring terminals to an appropriate post by a nut, requires the cable to first be assembled on the post and then the nut to be run down the post before being manually torqued, requiring the use of tools in what may be a relatively confined space.

The torqueing operating, together with the use of crimped ring terminals in general, can also often cause delays in installation and may also result in reworking being necessary. This may arise from issues such as the ring terminals being misaligned, which requires the cable to be axially torqued to align the ring terminal with the post, 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.

Additionally the torqueing operation may tend to twist the position of the ring terminal on the post, so that the ring terminal and cable are then skewed and thus may come into undesirable contact with an adjacent cable or with a rigid part of either a terminal block, the frame or other equipment, which again may require reworking to avoid damage to those parts or to the cable.

Another 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.

In addition to the above, other issues which may arise from the use of conventional ring connectors are the risks of incorrectly connecting different power phases and of exposed electrically live metal parts, posing a risk to the operator and also the risk of those exposed metal parts potentially corroding with time, as for example in the case of aluminium ring terminals. It is an objective of the present invention to provide an improved connector which addresses the above mentioned problems.

According to a first aspect of the present invention there is provided an electrical connector for use in an electrical power distribution system, the connector comprising a socket assembly and a pin assembly for connecting to the socket assembly, wherein: the socket assembly comprises an electrically conductive socket arranged to releaseably receive a pin of the pin assembly and an electrically insulating socket housing extending over the socket; the pin assembly comprises an electrically conductive pin arranged to be received in the socket of the socket assembly and an electrically insulating pin housing extending over the pin; and the pin and socket are arranged to permit the pin to be pushed axially into the socket. The socket is arranged to axially lock the pin in the socket, when the pin reaches a lock point within the socket, to provide a first means of retaining the pin in connection with the socket and thus the pin assembly in connection with the socket assembly and the pin housing is arranged to overlap with the socket housing when the pin is received in the socket and the pin housing and socket housing are arranged to rotate axially relative to each other, the pin housing and socket housing being provided with engaging means, such that rotation of the pin housing relative to the socket housing locks the pin housing to the socket housing.

An electrical connector in accordance with the present invention may be used as an alternative to ring terminals, to connect to terminal blocks and other electronic equipment, for example batteries, distribution boxes, inverters, generators, E-taxi, E-brake and actuators, as for example may be found on board an aircraft. However the invention is not limited to an electrical connector for use on board an aircraft, as it will have many other applications.

An electrical connector in accordance with the present invention provides a two stage locking mechanism to avoid unintentional release and thus provides a pin assembly which can be connected to a socket assembly in a safe, reliable manner, without the use of washers, nuts, tools or any other loose components, permitting such a connector to be used in specialists applications, for example on board an aircraft.

When used in such an application, a connector in accordance with the present invention may significantly reduce the installation time that would otherwise be required to secure ring terminals to posts by nuts and washers, avoiding the need torque the nuts and avoiding the possibility of foreign object debris (FOD) arising from misplaced nuts, washers or tools necessary for installation of conventional ring terminals. The invention will also avoid the need for the aforementioned possible reworking, arising as a result of damage to a ring terminal in the torqueing operation.

The connector of the present invention preferably permits a cable secured to the pin assembly (or socket assembly) to freely rotate axially, such that when the connector is used to attach a cable to a terminal block, or other item of electrical equipment, no rotational torque can be placed on the cable by the connector. This may again avoid the need for reworking that may otherwise arise after securing a ring terminal to a post of a terminal block, as a result of the ring terminal being misaligned with the post.

A further advantage of the present invention is that a mechanical lock is provided between the pin and the socket, which will both normally be metal components and which will both normally be mechanically connected to a respective cable or item of electrical equipment. Thus the pin and socket will take any strain that may be placed on the connector by such items, instead of the strain being taken by the housing of each, which will normally be formed of plastic, making the connector far less likely to fail if it should experience forces acting to pull it apart.

Preferably, the pin is arranged such that it 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. This ensures that any tensile force (within reason) applied to connector will not result in the connector unintentionally releasing, it first being required to further compress the electrical connector, or at least the pin and socket of that connector, before the pin can be released from the socket.

With the above arrangement, it is preferable that the process of locking the pin housing to the socket housing also prevents the pin from being pushed into the socket to the release point, requiring that the pin housing has to first be rotated to unlock the pin housing from the socket housing, in order to permit the pin to then be pushed further into the socket to the release point, before the pin can be withdrawn from the socket. In this manner the pin housing and socket housing prevent the pin, from being released from the socket until they have been unlocked.

In an alternative arrangement, rotating the pin housing relative to the socket housing to lock the pin housing to the socket housing permits the pin to be pushed into the socket to the release point, in order to release the pin form the socket, but with this arrangement the pin housing then has to be rotated relative to the socket housing before the pin can be withdrawn from the socket. Thus this arrangement also provides a double locking mechanism, but this is slightly inferior to that previously described, in that when the pin is locked in the socket and the pin housing is locked to the socket housing, the pin assembly and socket assembly need only be pushed together to subsequently release the connection between the pin and the socket. At this point the pin assembly would then only be retained in the socket assembly by means of the pin housing engaging with the socket housing and these would normally both be formed of plastic. These would not therefore provide as secure a connection in the partially unlocked state, as would be provided by the pin and socket in the previously described embodiment.

Preferably, the electrical connector further comprises 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 pin, and a slide ring, the slide ring being arranged to slide axially in a second groove on either an outer surface of the pin or an inner surface of the socket wherein, when the pin is pushed into the socket to the lock point, the lock ring expands or contracts to extend into the second groove, preventing the pin from being withdrawn from the socket, and wherein, when the pin 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 pin to be withdrawn from the socket.

The above arrangement permits a pin to engage with the socket by merely being pushed into the socket and permits it to subsequently be released by pushing the pin further into the socket before withdrawing the pin out of the socket. Thus, the pin and socket may be connected and disconnected without the need to rotate the pin relative to the socket, enabling a cable connected to the pin to be connected to and disconnected from a socket fixed to an item of equipment, without the need to rotate the cable. Furthermore the pin and socket, normally being circular in cross-section, enable the pin and associated cable to be aligned with any angular orientation when presented to the socket and pushed into the socket.

Preferably, one of the socket housing or pin housing is arranged to be received in the other of the pin housing or socket housing, wherein one of the pin housing or socket housing has one or more lugs and the other of the pin housing or socket housing has one or more keyways arranged to engage with the one or more lugs, the one or more keyways being shaped to permit the two housings to be pushed axially together and subsequently rotated axially relative to each other.

Such an arrangement permits the pin to be inserted axially to establish a first connection and the pin housing to then be rotated relative to the socket housing to establish a second connection between the two housings.

Preferably, the one or more keyways has a linear portion extending in an axial direction with a branch of the keyway extending off the linear portion in a radial direction, at a point remote from the ends of the linear portion of the keyway and at a point along the linear portion of the keyway reached by the lug after the pin has reached the lock point, but before the pin has reached the release point. This permits the pin assembly to be pushed onto a socket assembly until the pin reaches the lock point and is locked in the socket, whereby then rotating the pin housing relative to the socket housing causes the lugs to enter the branch of the keyway preventing the pin assembly and the socket assembly from being pushed further together and preventing the pin from being further inserted into the socket to reach the release point. This arrangement thus prevents any accidental compressive force via the cable on the pin releasing the pin from the socket.

Preferably, the branch has a gate through which the lug passes, providing an audible and tactile signal when the pin assembly is correctly engaged with and locked to the socket assembly. This may be particularly advantageous where the pin assembly is to be connected to the socket assembly in a location where it is difficult to see the connector. This is because, in the process of connecting the pin assembly to the socket assembly, a user will experience a first audible and tactile signal generated by the lock ring engaging with the groove, indicating that the pin is secured in the socket, before experiencing a second audible and tactile signal generated by the lug passing through the gate, indicating that the pin housing is correctly secured on the socket housing.

Advantageously, the pin housing may rotate freely relative to the pin, such that rotating the pin housing relative to the socket housing, even by a few degrees to engage the lugs in a branch of a keyway, will not place any rotational force on a cable connected to the pin.

Preferably, the pin has an integrally formed tail portion arranged to receive and be directly connected to an electrical cable. This may be in the form of a crimp integrally formed in the tail portion of the pin, into which an electrical cable is fed and crimped in place, but alternatively such a cable could braised or secured by other means. Preferably, the pin assembly further comprises an electrically insulating boot arranged to extend over the tail portion of the pin to a sleeve of a cable, to electrically insulate the tail portion. The boot rotatably engages with the pin housing, to permit the pin housing to freely rotate relative to all of the boot, the cable and the pin, and to provide, together with the pin housing, a continuous electrically insulating shield over the pin. In this way, both the pin and a connection to a cable may be electrically insulated by the pin housing and the boot, with the boot rotatably engaging with the pin housing permitting the boot to be sealed (fixed) to an outer casing of the cable while still permitting the pin housing to rotate freely relative to the cable.

The socket may have an integrally formed tail portion arranged to be fixed to, or form part of, a terminal block or other item of electrical equipment, enabling the socket to effectively form part of that equipment. The socket may thus then be held rigidly in place by the equipment, assisting in permitting a pin assembly of the connector to be connected to the socket assembly by a single-handed operation in what is generally termed a quick connect operation.

Preferably, the pin has an electrically insulated cap to prevent accidental contact with the electrically conductive pin when the pin assembly is disconnected from the socket assembly.

Preferably, the socket assembly further comprises an ejector cap and spring captive in the socket, the spring being arranged to urge the ejector cap to close the socket in the absence of the pin. This may stop ingress of debris or liquid into the socket, in the absence of a pin assembly, and may also act to eject the pin once the pin is disconnected, avoiding the possibility of a disconnected pin assembly being retained in a socket.

The socket may preferably further comprises an annular electrically conductive contact band through which the pin is arranged to be inserted, the contact band having an plurality of radially biased electrically conductive contacts, each arranged to engage the pin, so that each contact is sandwiched between the internal surface of the socket and the external surface of the pin and held in electrical contact with both by the applied radial bias. Such a contact band will act as a plurality of resistors arranged in parallel, significantly reducing the bulk resistance of the connection between the pin and the socket. Furthermore, the contact band maintains electrical connection between the pin and the socket even durring small axial displacements between the two and irrespective of their angular alignment.

According to a second aspect of the present invention there is provided a power distribution system comprising a plurality of electrical connectors in accordance with the first aspect of the present invention. The plurality of electrical connectors are preferably of different types, wherein one of each pin assembly or socket assembly has one or more lugs and each of the other of the pin assembly or socket assembly has one or more keyways arranged to engage with the lugs, wherein the lugs and associated keyways of one electrical connector type are different to those of the other electrical connector types, to prevent pin assemblies being connected to incorrect socket assemblies. For example, three connector types may be used with the three different phases of a three phase supply, to ensure the different phases cannot be incorrectly connected to equipment or to a terminal block. The lugs and keyways may be“different” by virtue f their physical form or by virtue of their positioning on their respective housings.

According to a third aspect of the present invention there is provided an aircraft comprising a power distribution system in accordance with the second aspect of the present invention.

One embodiment 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 of which:

Figure 1 is a perspective view of a pin assembly and socket assembly of a connector in accordance with the present invention, shown disconnected; Figure 2 is a cross-section through the pin assembly and socket assembly of Figure 1 ;

Figure 3 is a perspective view of the pin assembly of Figures 1 and 2, with a pin housing removed to clearly show a connector pin and a crimp boot of the pin assembly;

Figure 4 is a perspective view of the pin assembly of Figures 1 and 2, showing a cable attached to the pin assembly;

Figure 5 is a cross-section through the cable and pin assembly of Figure 4;

Figure 6 is a perspective view of the connector of Figure 1 , but with the pin assembly retained and locked in the socket assembly;

Figure 7 is a cross-section through the connector of Figure 6;

Figure 8 is a transparent side elevation of the connector assembly of Figures 6 and 7;

Figure 9 is a perspective view of the connector of Figures 6 to 8, with the pin assembly retained, but no longer locked, in the socket assembly;

Figure 10 is a cross-section through the connector of Figure 9;

Figure 11 is a transparent side elevation of the connector assembly as shown in Figures 9 and 10;

Figure 12 is a perspective view of the connector of Figures 9 to 11 , but with the pin assembly released, but not withdrawn, from the socket assembly;

Figure 13 is a cross-section through the connector of Figure 12;

Figure 14 is a transparent side elevation of the connector assembly as shown in Figures 12 and 13;

Figure 15 is a cross-section through the connector with the pin assembly partly withdrawn from the socket assembly;

Figure 16 is a transparent side elevation of the connector of Figure 15;

Figure 17 corresponds to the transparent side elevation of Figure 11 but shows an example of an alternative keyway;

Figure 18 is a perspective view of a socket assembly with a sprung ejector;

Figure 19 is a cross-section through a pin assembly and socket assembly of Figure 18 when disconnected; Figure 20 corresponds to Figure 18 but shows the pin assembly and socket assembly when connected;

Figure 21 is a cross-section showing an alternative way in which a crimp boot may be fixed to a pin housing;

Figure 22 is a cross-section of a cable and pin assembly with a heat shrink boot applied;

Figure 23 is a cross-section of a pin assembly with an additional seal between the connector pin and cable;

Figure 24 is a perspective view of an alternative socket assembly;

Figures 25A to 25C illustrate alternative keyways that may be used on the connector of Figure 1 ;

Figure 26 is a perspective view of a contact band of the socket assembly of Figure 2;

Figure 27 is a side elevation of the contact band of Figure 26:

Figure 28 is a cross section of the socket assembly of Figure 2, but with the contact band shown in detail;

Figure 29 is an end elevation of the socket assembly of Figure 28;

Figure 30 is a perspective view of three socket assemblies mounted to busbar;

Figure 31 is a perspective view of three alternative socket assemblies mounted to a circular busbar; and

Figure 32 is a cross-section through the socket assemblies and busbar of Figure 31.

Referring now to Figure 1 this shows a connector in accordance with the present invention, which is indicated generally as 1. The connector 1 comprises a socket assembly 2 arranged to receive and connect with a pin assembly 3 of the connector 1. As can be seen most clearly from Figure 2, the socket assembly 2 comprises a connector socket 4 (which is metallic) and has a threaded connection 5 at its proximal end and a socket 6 towards its distal end. The threaded connection 5 may be mounted to electrical equipment to provide a termination for power input/output connections and this may be attached to an internal busbar, or similar, within the equipment. Alternatively it may be attached to a busbar of a terminal block, where the socket assembly is to be part of the terminal block, to permit appropiate pin assemblies to then make an electrical connection to such a terminal block.

Within the socket 6 is located an annular contact band 7 arranged to receive a pin of the pin assembly 3. The contact band 7 is in effect similar to multiple parallel resistors of low resistance between the socket and the pin, thus reducing the bulk resistance and allowing for rotational contact with the pin to be received in the socket 6. For clarity, the contact band 7 is shown schematically throughout the figures, with the exception of Figures 26 to 29. In Figures 26 to 29 the contact band 7 is shown in detail and the contact band is discussed later with reference to those figures.

Referring again to Figure 2, the socket 6 has a groove 8 on an inner wall in which a lock ring 9 is retained. The lock ring 9 is a split ring, which in a natural state has an outer diameter less than the outer diameter of the groove 8, but which outer diameter is greater than the inner diameter of the groove 8. Thus the lock ring 9 is retained by the groove 8 but may expand radially in the groove 8.

The pin assembly further comprises a socket housing 10 made of an electrically insulating plastic which encapsulates most of the connector socket 4, with the exception of a portion of the threaded connection 5. Secured into a front open end of the socket housing 10 is a socket cap 11 , also made of an insulating plastic. This retains the socket 6 within the socket housing 10 and insulates the end of the electrically conductive socket 6.

The pin assembly 3 comprises a metallic connector pin 12 having a crimp portion 13 at one end and a pin 14 at an opposite end for engaging in the socket 6 of the socket assembly 2. The pin 14 has an electrically insulating plastic pin cap 15 screwed into it, but alternatively this could be a clip fit, to insulate the potentially exposed tip of the electrically conductive pin 14. The pin 14 has a circumferential groove 16 in its outer surface and towards its base in which is located slide ring 17. The slide ring 17 has a narrower width in an axial direction than the groove 16, and therefore the slide ring 17 may slide back and forwards axially within the groove 16. This is perhaps seen more clearly seen from Figure 3.

Referring again to Figure 2, the pin assembly 3 further comprises a plastic pin housing 18 with an inner shoulder 19 which axially abuts an outer shoulder 20 of the connector pin 12. The diameter of the connector pin 12 in the region of the inner shoulder 19 of the pin housing 18 is of a greater diameter than the diameter of pin 14 and this portion of the connector pin together with the shoulder 19 of the pin housing define the end of a cavity between an external surface of the pin 14 and an internal surface of the pin housing 18, into which cavity the distal portion of the socket assembly 2 may be received.

The internal surface of the pin housing 18 has two keyways 22 and 23 formed therein. These are arranged to engage with lugs 24 and 25 on the external surface of the socket housing 10 of the socket assembly 2, when the distal portion of the socket assembly is received in the pin assembly 3.

The pin assembly 3 further comprises a plastic crimp boot 26 which electrically insulates the crimp portion 13 of the connector pin 12. The crimp boot 26 has an annular snap 27 which engages with an inner shoulder 28 of the pin housing 18, as shown in Figure 2.

Referring now to Figure 3, this shows the pin assembly 3 prior to the pin housing 18 being fitted. Flere the crimp boot 26 is shown positioned on the connector pin 12, over the crimp portion 13 and with the annular snap 27 ready to engage with the pin housing 18 and hold the pin housing 18 in contact with face 29 of the outer shoulder 20 of the connector pin 12. Thus, the crimp boot 26 and pin housing 18, when assembled together as shown in Figure 2, effectively sandwich the shoulder 20 of the connector pin 12 and thus provide a simple means of assembling the three major components of the pin assembly 3.

Referring to Figures 4 and 5, these show the assembled pin assembly 3 with a cable 30 attached thereto. The conductive core 31 of the cable 30 is received in the crimp portion 13 of the connector pin 12, where it is secured in place by being crimped within the crimp portion 13. The sleeve 32 of the cable 30 extends into the crimp boot 26, such that the cable sleeve 32 and crimp boot 26 together form a continuous insulated shield over the conductive core 31 and the conductive connector pin 12.

As will be seen from a general review of Figures 3, 4 and 5, all the interconnecting components of the pin assembly 3 are circular in axial cross- section, including the annular snap 27 which, as can be seen from Figure 5, engages under the circular inner shoulder 28 of the pin housing 18. This, in combination with the inner shoulder 19 of the pin housing 18 being circular and riding upon the circular external surface of the connector pin 12, permits the pin housing 18 to freely rotate relative to the cable 30, the connector pin 12 and the crimp boot 26. Thus, the cable 30 and connector pin 12, to which the cable 30 is crimped, may freely rotate relative to the pin housing 18. Furthermore, the pin 14 is also circular in cross section and thus, when received in the connector band 7 in the socket 6 of socket assembly 2 of Figure 2, may rotate relative to the socket assembly 2. Thus, when the pin housing 18 is connected to the socket housing 10 of the socket assembly 2, in the manner discussed below, the cable 30 may rotate relative to both the pin housing 18 of the pin assembly and relative to the socket assembly 2, preventing the socket assembly 2 from applying a rotational torque to the cable 30.

Referring now to Figures 6, 7 and 8 these show the connector 1 with the pin assembly 2 retained and locked in the socket assembly 3. In this position, a visual indicator 33 on the socket assembly 3 is aligned with visual indicator 34 on the pin assembly 2. In this position, the lugs 24 and 25 on the outer surface of the socket housing 10 are engaged in respective keyways 22 and 23 on an inner face of the pin housing 18. The shape of both keyways 22 and 23 is the same and, as can be seen from Figure 8, these are t-shaped and in this retained and locked position the lugs 24 and 25 are captive in the branch 35 of the‘t’. The branch 35 is waisted to form a gate which provides both tactile and audible signals when the lugs 24 and 25 engage or disengage with the end of the branch 35, on rotation of the pin housing 18 relative to the socket housing 10.

As can be seen from Figure 7, in this retained and locked position the electrically conductive pin 14 of the pin assembly 3 is engaged with the contact band 7 in the socket 6 of the socket assembly 2. In this position, not only are the socket assembly 2 and pin assembly 3 engaged by means of the lugs 24 and 25 engaging in the respective keyways 22 and 23, but the pin 14 is also prevented from being pulled out of the socket 6 by the lock ring 9 captive in the inner groove 8 engaging with the distal end of groove 16 in the pin 14. Flowever, as mentioned above, the pin 14 may still rotate in the socket 6, such that when the socket 6 is secured to a piece of equipment or a terminal block, by means of the threaded connection 5, a cable crimped in the crimp portion 13 of the pin assembly 3 may rotate with the pin thus avoiding any axial torque being placed on such a cable.

To release the pin assembly 3 from the socket assembly 2, the pin housing 18 is rotated to the“unlocked” position shown in Figures 9, 10 and 11. Flere the lugs 24 and 25 disengage from each branch 35 of respective keyways 22 and 23, to adopt the position shown in Figure 11. In this position, the pin 14 is still retained in socket 6 by the lock ring 9. Flowever, the visual indicators 33 and 34 are no longer aligned, indicating that the pin assembly 3 is no longer correctly locked to the socket assembly 2.

In order to subsequently release the pin assembly 3 from the socket assembly 2, it is necessary to push the pin assembly 3 and socket assembly 2 further together to the“released” position shown in Figures 12 to 14. This causes the proximal face of the groove 16, with the slide ring 17 in it, to force the tapered slide ring 17 between the pin 14 and the lock ring 9, expanding the lock ring 9 radially into the groove 8 on the inner face of the socket 6. In this position the pin 14 is released from the socket 6 and may be drawn out of socket 6 through the lock ring 17, as the pin assembly 3 is withdrawn from the socket assembly 2, as show in Figures 15 and 16, to adopt the position illustrated in Figure 1.

In order to connect, the pin assembly 3 to the socket assembly 2 the procedure is reversed. With reference to Figure 1 , the visual indicator 34 is aligned with either of the lugs 24 or 25, only one of which can be seen in Figure 1 , and the pin assembly 3 is then pushed onto the socket assembly 2, while urging the pin housing 18 in a clockwise direction. This action causes the lock ring 9 to initially be expanded by the pin cap 15 and pin 14 passing through it, until it reaches the slide ring 17. The lock ring 9 then drags the slide ring 17 to the left, until the lock ring 9 snaps into the groove 8, as shown in Figure 10, locking the pin 14 in the socket 6. This snapping action makes a first tactile and audible signal, indicating that the pin assembly 3 is engaged with the socket assembly 2, but not yet locked in the socket assembly 2.

At this point the components of the connector 1 are again as shown in Figures 9 to 11 , with the visual indicators 33, 34 not yet aligned and the lugs 24, 25 adjacent their respective branches 35 in the keyways 22 and 23. The pin housing 18 may then be rotated clockwise, relative to the socket assembly 2, with the lugs 24, 25 following the branches 35 until the they pass through the waisted gate, producing a second audible and tactile signal, indicating that the connector 1 is now locked. Flere the connector 1 will be in the position shown in Figures 6 to 8, where the visual indicators 33 and 34 are aligned, indicating that the pin assembly 3 is correctly locked on the socket assembly 2, which is also indicated by the double“click” experienced when making the connection, which may be convenient if the connection is in a difficult to view location. Very many modifications may be made to the connector illustrated and described with reference to Figures 1 to 16 and examples of some of these will now be illustrated with reference to Figures 17 to 25.

Referring to Figure 17, this illustrates just one example of an alternative shaped keyway 37, which may be used instead of the keyways 22 and 23 of the previous figures. With the arrangement of Figure 17, the pin assembly 3 would be retained on the socket assembly 2 and locked to the socket assembly 2 when the lugs 24 and 25 adopt the same position as in the previously described

embodiment. Flowever, in the Figure 17 embodiment, in order to release the pin assembly 3, the pin housing 18 would first have to be pressed towards the socket assembly and pulled back again before being rotated to the position shown in Figure 17 and withdrawn. This is thus a functionally equivalent operation to that previously described.

Referring now to Figures 18 to 20, these show a socket assembly similar to that previously described, but incorporating a spring ejector comprising an ejector cap 38 biased by a spring 39, such that when the pin assembly 3 is disconnected from the socket assembly 2, the ejector cap adopts the position shown in Figures 18 and 19 and seals with the socket cap 11. The ejector cap 38 may thus then act to prevent the ingress of FOD or fluid. Flowever, as shown in Figure 20, the ejector cap will automatically be pushed into the socket assembly 2 by the pin cap 15 when the pin assembly 3 is connected to the socket assembly 2.

Referring now Figure 21 , this shows a pin assembly 3 having a slightly modified pin housing 40 and crimp boot 41 , where the previously mentioned annular snap 27 (see Figure 20 for example) has been replaced with a spring retaining ring 42, captive in a groove in the pin housing 40 and engaging with a similar groove 43 in the crimp boot 41.

Referring to Figure 22, this shows how an elastomeric or heat shrink boot 44 may be used to prevent the ingress of fluid between the cable 30 and crimp boot 26. Alternatively, the ingress of fluid between the cable 30 and crimp boot 26 could be avoided by the provision of an O-ring seal 45 inside the crimp portion 13 of the connector pin 12, as shown in Figure 23. In addition, although the cable 30 is shown as being crimped, this could be retained in place by any suitable means with the connector pin 12 modified accordingly, for example it could be braised or soldered, or a press fit. Similarly the threaded connector 5 could be replaced with some other type, for example the press fit connector 46, shown in Figure 24.

Where selective connectivity is required, for example when using a three phase supply to ensure that the different phases cannot be incorrectly connected, then sets of appropriate pin assemblies 3 and socket assemblies 2 may be provided, generally as previously described, but having different keyways. For example, Figure 25A shows end elevations of a pin assembly 3 and the associated socket assembly 2 which has two lugs on the socket assembly 2, to engage with respective keyways 24, 25 of the pin assembly 3, as previously described.

Flowever, the pin assemblies and socket assemblies of Figures 25B and 25C are provided with three and five keyways respectively, preventing a pin assembly from connecting to the wrong socket assembly. Flowever means other than the keyways could be used to achieve the same purpose.

Alternatively, different sets of socket assemblies and key assemblies could be colour coded, possibly by having components moulded in plastics of different colours, but this would not physically prevent an incorrect connection being made.

In addition to the above, the pin assemblies and socket assemblies may be scaled up or down in size, depending on the power to be handled, and a range of pin assemblies and socket assemblies may be provided of different sizes. Flere the difference in size will itself prevent inappropriate connections being made.

In all of the above embodiments a threaded connection 5 has been shown forming part of the socket assembly 2 with the pin assembly 3 having a crimp portion 13 for receiving a cable 30, however these could be reversed. Alternatively both the socket assembly 2 and the pin assembly 3 could have a crimp portion, or some other means of attaching to respective cables, so that the connector could then function as an in-line connector for connecting two cables together.

Referring now to Figures 26 to 29 these show one example of a contact band 7 and its location within the socket 6 of the socket assembly 2 of the previous figures. The contact band is stamped from a thin sheet of metal to have the form indicated in Figures 26 and 27, with a plurality of upstanding blade contacts 47.

The contact band 7 is assembled in the socket 6 of the socket assembly 2, as shown in Figure 28, such that the blade contacts 47 protrude inwardly, as shown in Figure 29. As will be appreciated from Figure 29, when a pin 14 of the pin assembly 3 is pushed into the socket 6, the blade contacts 47 will be forced outwardly to permit the pin 14 to be accommodated in the position shown in Figure 7, for example. In this position the blade contacts 47 will be 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 pin 14, even during any slight variations in the axial or lateral positions of the pin 14 within the socket 14 and regardless of the angular position of the pin 14 within the socket 6 or any rotation that may occur between the two.

Not only does the contact band ensure a reliable contact that permits rotation between the pin 14 and the socket 6, but the blade contacts 47 also function as resistors in parallel reducing the bulk resistance of the connector 1.

Referring now to Figure 30, this shows three socket assemblies 2 mounted to a common busbar 48, so that socket assemblies 2 are electrically connected together and may function to supply power to a number of pin assemblies and associated cables 30 (not shown in Figure 30). A similar arrangement is shown in Figure 31 where three socket assemblies 49, of a modified design to those previously described, are shown attached to a circular busbar 50, shown in cross- section in Figure 32. From the cross-section of Figure 32, it will be seen that each socket assembly 49 is similar to the socket assemblies 2 previously described. Flowever, the connector socket 51 has a planar tail portion 52 (instead of the threaded connection 5 of the previous embodiments) with an aperture 53 extending through the tail portion 52. Each socket assembly 49 has a socket housing 54 extending over the connector socket 51 , including over the tail portion 52. Each socket housing 54 has apertures in register with the aperture 53 through the tail portion 52, so that each socket assembly 49 may slide onto circular busbar 50, as shown. Each aperture 53 has a groove 55 in a mid-portion, as shown in Figure 32, which contains a contact band similar to the contact band 7 previously described, which establishes a secure and reliable electrical contact with the busbar 50.

Although the busbar 50 illustrated is circular in cross-section, it could have any alternative cross-section, for example square, with corresponding apertures 51 provided in the socket assemblies 49. Flowever, the circular cross-section is preferred for it enables socket assemblies 49 to be aligned at any angular position on the busbar 50. This may be particularly advantageous where the socket assemblies 49 are to be mounted to a pin or busbar of a terminal block, permitting cables 30 connected to pin assemblies 3 to be arranged at different angles relative to the busbar 50.

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.