GB2597837A

GB2597837A - A backshell assembly

Info

Publication number: GB2597837A
Application number: GB2110397.3A
Authority: GB
Inventors: James Robinson Dominic
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-07-20
Filing date: 2021-07-20
Publication date: 2022-02-09
Also published as: GB202110397D0; GB2602179B; GB2602179A; GB202011186D0; GB202110413D0

Abstract

A backshell assembly 1 comprises a cable guide 5 through which a cable bundle can be anchored and pass through to a connector, the cable guide 5 having a proximal face 13 arranged to engage with the connector in a manner that prevents relative rotation between the connector and the cable guide 5. The assembly 1 further comprises a fastening ring 6 to screw to the connector to retain the cable guide 5 in contact with the connector, and an annular locking member 7 arranged to slide in a longitudinal direction along the cable guide 5. The locking member 7 comprises features to prevent rotation relative to the cable guide 5. The annular locking member 7 and fastening ring 6 comprise interlocking splines (figure 3, 16, 18) to prevent relative rotation of the two when the annular locking member 7 is in a locked position and to thus prevent unintentional release of the fastening ring. A transition piece is also disclosed within the application (see figure 31).

Description

A Backshell Assembly The present invention relates to a backshell assembly for connecting a cable bundle to a multi-pin connector and in one embodiment to a backshell assembly suitable for use with a cable having a braid or sleeve for electro-magnetic compatibility (EMC) protection.

In many industrial applications, data and power cables are compiled into bundles, with individual harnesses often connected for distribution through intermediate bulkheads (which may be in the form of an outer casing of an item of equipment) via multi-pin connectors in the bulkhead, into which each cable (wire) of a bundle is independently fastened. To protect the cables from pull-out a device known as a backshell, with a cord lock, similar to that found in a domestic electric plug, is threadedly attached to the back of the connector to provide strain relief.

Some backshells are provided with a means to direct the cable bundle in a precise orientation, usually 00, 45° or 900.

To secure a backshell to a connector, the connector normally has a portion with an external thread, to engage with an internal thread of a fastening ring of the backshell. To prevent the fastening ring unscrewing, which may result from vibration or other means, the fastening ring may be required to be tightened to a torque and the backshell provided with a mechanism, such as a ratchet, to resist unscrewing of the fastening ring.

In order to provide electrical continuity if required, connectors are provided with an annular array of serrated teeth to which the backshell, or a ring with a matching array of teeth inserted into the backshell body, can be attached. In this case, the unlocking prevention facility is particularly relevant to ensure a good connection is maintained. Electrical continuity requires the cable bundle to be encased in a woven metallic braid, to provide electro-magnetic compatibility (EMC) protection against electro-magnetic interference (EMI), radio frequency interference (RFI) and lightning strike. Main bundles are split into smaller bundles for distribution, with every bundle or individual cable terminating in a connector and backshell for attachment to a specific device.

Whether closed braids (in the form of a complete tube) or more recent open sleeves (having a split along their length and which have a bias to self-closure), are used to provide EMC protection, there are precise procedures for making the connections between a backshell and braid, between a braid and an open sleeve and especially for managing transitions, which are elaborate and time consuming and require a diverse range of components that are expensive and wasteful. The 113 bundles are usually compiled on boards with the backshells attached so that they can be tested for integrity. Where protection is needed, the bundles must first be encased in the braid and, to test for electrical continuity, the braid must be attached to the backshell. Where a backshell requires an insert, the insert is provided with a braid sock, a short length of braided hose, to which the braid on the cable bundle, or the open sleeve, must be mated. Where bundles are split a complex overlapping procedure to mate and fasten diverging sleeves has to be performed to prove integrity. This involves tying the harnesses with lacing tape several times in lOmm increments before and after the proposed joint, with redundant lengths being cut off and wasted, and overlapping and tying off the sleeves. In the event of a failure, the entire harness may need to be taken apart to find the fault.

As discussed above, each individual cable is inserted into the connector, with the connector normally having a rubber plan form built into it. To avoid having to dismantle an entire harness in the event of a fault, compilers may prefer to test the harness before backshells and braids or sleeves are added. Open sleeves would permit this if it was not for the backshells and transition components.

The aim of the present invention is to provide an improved backshell and other components for a harness system.

According to a first aspect of the present invention there is provided a backshell assembly for connecting a cable bundle to a connector, the backshell assembly comprising: a cable guide, substantially cylindrical in shape, through which a cable bundle may pass from a distal end to a proximal end of the backshell assembly, wherein the proximal end of the backshell assembly is arranged to connect to a connector, the cable guide having a proximal face arranged to engage with the connector in a manner that prevents relative rotation between the connector and the cable guide, the cable guide further comprising means for engaging directly or 113 indirectly with the cable bundle to retain the cable bundle in position in the cable guide to prevent the cable bundle from being pulled out of the backshell assembly and/or to provide strain relief; a fastening ring coaxial with and extending around the cable guide, the fastening ring being arranged to engage with the cable guide in manner that it may urge the cable guide in a proximal direction towards a connector, in order to retain the cable guide in contact with the connector, the fastening ring being arranged to be rotated on a connector to retain the cable guide in place against the connector in a manner in which the cable guide may not rotate relative to the connector, the fastening ring having a plurality of first splines or grooves extending longitudinally from a distal face of the fastening member; and an annular locking member coaxial with and extending around the cable guide and being arranged to slide in a longitudinal direction along the cable guide, the locking member having a second plurality of splines or grooves extending longitudinally from a proximal face of the locking member and arranged to engage with the first plurality of splines or grooves on the fastening ring, wherein: the locking member and cable guide comprise cooperating engagement means to permit the locking member to slide longitudinally along the cable guide and to prevent rotation of the annular locking member on the cable guide, such that when the cable guide is held in place against a connector by the fastening ring, the cable guide is rotationally fixed to the connector and the locking member may slide proximally to a locked position, wherein the first plurality of splines or grooves engages with the second plurality of splines or grooves to prevent subsequent rotation of the fastening ring.

The present invention enables a fastening ring of a backshell to be secured against unintentional rotation and subsequent release, potentially caused by vibration, without the use of tools, with a minimum of components and with components that can be easily assembled and fitted to a connector in a reliable manner.

The fastening ring may have a proximal facing annular surface extending radially inwardly from an inner surface of the fastening ring and the cable guide may have a distal facing annular surface extending radially outwardly from an outer surface of the cable guide, the proximal and distal facing annular surfaces being arranged to engage in a longitudinal direction in order that the fastening ring may retain the cable guide in a proximal position, in contact with a connector, the cable guide further comprising one or more first retention means arranged to engage with one or more second retention means on the annular locking member, to retain the annular locking member in the locked position, wherein engagement of the first and second plurality of splines prevents rotation of the fastening ring relative to the annular locking member and the cable guide. In this manner, relatively few components may enable the annular locking member to prevent the fastening ring coming undone, simply by sliding the annular locking member to the locked position. Furthermore, the retention means then prevents the annular locking member being unintentionally displaced from the locked position.

One or more of the first and/or second retention means may comprise one or more serrations with angled faces, the angled faces being arranged to require a greater force to be required to displace the annular locking member distally on the cable guide, from the locked position to an unlocked position, than is required to displace the annular locking member proximally on the cable guide, from the unlocked position to the locked position. This may permit the annular locking member to be quickly and easily placed in the locked position, with the retention means then requiring a significantly greater force to be exerted to release the annular locking member.

The first retention means may be located on one or more resilient tabs formed in a peripheral wall of the cable guide. The tabs may then provide a resilient biasing means to act to keep the tabs and thus the serrations in contact. With this arrangement the annular locking member may extend substantially over the one or more tabs of the cable guide and prevent access to those tabs, thus preventing the tabs being depressed and unintentionally released, or released by an unauthorised 113 individual. However, one or more passages may be provided through the annular locking member, to permit a tool to pass through the annular locking member and depress the one or more tabs, to permit the annular locking member to move distally along the cable guide so that the fastening ring may then be released to enable the backshell assembly to be removed from a connector. Such an arrangement may thus permit a backshell to be subsequently released, but only with a special tool, which may be provided only to authorised individuals.

The cable guide may have a cradle extending distally therefrom and a clamp or tie to permit the cable bundle to be secured to the backshell assembly.

Preferably, the cradle is pivotally attached to a main body of the cable guide so that the cradle may be set at one of a plurality of predefined angles, relative to a longitudinal axis of the backshell assembly. In this manner a single backshell assembly may permit a cable bundle to exit the assembly at a desired one of a plurality of angles, without the need for any additional components.

The fastening ring preferably has an internal screw thread arranged to screw onto an external screw thread of a connector, but alternatively some other arrangement could be adopted, such as a bayonet type fitting.

In one embodiment the cable guide comprises a first tubular portion and a second tubular portion arranged coaxially inside the first tubular portion, wherein the first and second tubular portions are joined at or towards a proximal end of the cable guide and wherein the first and second tubular portions are radially spaced apart from each other and are open towards a distal end of the cable guide, so as to define an annular cavity between the first and second tubular portions, wherein a central lumen of the second tubular portion is arranged to permit a cable bundle to pass there through and the annular cavity is arranged to receive a braid or sleeve of the cable bundle. In this manner the backshell assembly may provide a termination for a braid or sleeve of the cable bundle, which only requires the end of the braid or cable sleeve to be slid in to the annular cavity. This will also provide a shield for the cut end of the braid or sleeve.

Preferably, the annular cavity has a width in a radial direction around its circumference sufficient to accommodate a single layer of braid or sleeve, but at one portion has a width in a radial direction sufficient to accommodate the double thickness of an overlapping portion of a sleeve.

Advantageously the second tubular portion extends in a distal direction to a greater extent than the first tubular portion; the annular locking member comprises a tubular tail portion which, in the locked position, extends coaxially with and over at least part of the second tubular portion of the cable guide; and the spacing between an inner surface of the tail portion of the annular locking member and the outer surface of the second tubular portion of the cable guide is slightly less than the thickness of a braid or sleeve of a cable bundle, which the backshell assembly is intended to be used with, such that when the locking member is in the locked position the braid or sleeve is at least slightly compressed between the second tubular portion of the cable guide and the tail portion of the annular locking member. In this manner, sliding the annular locking member over the cable guide to the locked position, to lock the fastening ring in place, may also act to hold the braid or sleeve of the cable bundle in place in the backshell assembly.

When in the locked position, the tail portion of the annular locking member preferably extends beyond the end of the second tubular portion of the cable guide, to define a distal end of the tail portion, the distal end of the tail portion then preferably has a reduced inner diameter, equal to or less than the outer diameter of the second tubular portion. This will act to force an annular portion of the braid or sleeve to "chicane" around the distal end of the tail portion at the same time as being compressed between the distal end of the tail portion of the annular locking member and the distal end of the second, inner, tubular member. Thus, the action of moving the annular locking member to the locked position will also lock the braid or sleeve into the backshell assembly.

The reduction in the inner diameter of the tail portion at the distal end of the tail portion preferably defines a proximal facing annular surface which, when in the locked position, is spaced apart from an end face of the second tubular portion of the cable guide by a distance equal to or less than the thickness of a braid or sleeve of a cable bundle which it is intended that the backshell assembly be used with. This will then also act to hold the braid or sleeve in place in the backshell assembly and act to prevent it from being pulled through the "chicane" defined by said components.

In one embodiment, the first tubular portion of the cable guide may comprise, towards its distal end, a plurality of resilient fingers arranged to be compressed radially inwards, each finger having an engagement member towards its distal end arranged to engage with a corresponding engagement member on an inner face of the annular locking member, wherein pushing the annular locking member proximally over said fingers causes the fingers to be deflected radially inwards, as the engagement members on each finger engage with the engagement member or members on the inner surface of the annular locking member, to act to retain the annular locking member in the locked position. This provides an additional locking mechanism and may be used to provide a permanent locking mechanism in applications where the backshell assembly is never to be released.

In one embodiment every component of the backshell which extends around the cable bundle may be arranged to be split apart in a longitudinal plane of that component. An advantage of using a backshell with components which can be split in a longitudinal plane, is that once the backshell is assembled on a cable assembly having an open cable sleeve, if there is any reason to add or remove a cable to or from the cable bundle, it will then be possible to release the backshell, split the backshell components and open the cable sleeve, to permit a single one or more cables of the cable bundle to be added or removed, without the need to disconnect and possibly retest every other cable within the cable bundle.

In the above arrangement, the fastening ring may comprise two halves split longitudinally, which two halves are arranged to engage with each other by a first 113 half sliding longitudinally relative to the second half, so that appropriate grooves or splines on each engage with corresponding grooves or splines, to resist separation radially of the two halves. Where the fastening ring has an internal screw thread arranged to be screwed onto an external screw thread of a connector, then, when the fastening ring is screwed onto an external screw thread of a connector, the two halves of the fastening ring will then be prevented from being longitudinally displaced relative to each other and will thus be locked together simply by the action of screwing the fastening ring onto a connector.

Similarly, the cable guide may be split longitudinally and comprise two halves which are arranged to engage with each other, by a first half sliding longitudinally relative to a second half, such that appropriate grooves and/or splines engage with each other, wherein the two halves comprise a snap fit mechanism, which acts to retain the two halves in a fixed longitudinal position to each other, preventing the two halves from separating.

In contrast to the above, the annular locking member may be arranged to be split by moving its two halves radially, for in the locked position, the two halves will be retained together as a result of at least part of each of the two halves of the annular locking member extending within the fastening ring.

The backshell assembly is preferably electrically conductive or has an electrically conductive coating. It may also comprise components formed using 3D additive manufacturing.

According to a second aspect of the present invention, there is provided a wiring harness comprising a cable bundle with a sleeve that may be opened along its length, with the harness terminating at one point, at least, in a backshell assembly as described in any of the above-mentioned embodiments.

113 According to a third aspect of the present invention, there is provided a transition piece for a cable bundle, the transition piece having a housing comprising a bottom portion and a top portion, separable from each other such that the top portion may be removed and a cable bundle arranged in the bottom portion, the transition piece having a plurality of apertures each arranged to receive a cable bundle, which apertures in the housing are each of a common diameter, the transition piece further comprising a plurality of reducing members each having a common external diameter to be received in any one of the apertures of the transition piece, with the reducing members selected from a set having different internal diameters, so that the internal diameters may be matched to the diameter of a cable bundle passing therethrough. This provides the advantage of providing a transition piece which can be easily split, to permit a single cable to be removed or added from or to a harness, which is particularly advantageous if used in a system in conjunction with the above described splitable backshells. It also avoids the need for multiple lacing tape joints, which can be difficult to inspect for EMC compliance and the repeated tying of which can result in repetitive strain injuries. It may also provide a more compact and neat transition, while providing strain relief to the portion of the cables within the transition piece.

The two halves of the housing may be arranged to retain each of the reducers in place and compress the reducers such as to at least partly act to retain the cable bundles in place in each respective aperture of the housing.

Each reducer may be shaped to accommodate a cable sleeve having an overlapping portion.

Transition pieces may take the form of a reducer with only two apertures, each arranged to accommodate a common cable bundle, but with different sized sleeves extending into each aperture being matched to an appropriate reducer. Alternatively, they could take the form of a branched "Y" for example. In a particularly advantageous arrangement, the transition piece may have four apertures, with the housing shaped to permit branching of a number of cables from a main cable bundle passing through the housing.

Several 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 to indicate like components and of which: Figure 1 is a front perspective view of a backshell assembly in accordance with a first embodiment of the present invention, shown in a "locked" position; Figure 2 is exploded view corresponding to Figure 1; Figure 3 is a rear perspective view of the backshell assembly of Figure 1, but shown in an "unlocked" position; Figure 4 is a detailed view of an annular locking member of the backshell assembly of Figures 1 to 3; Figure 5 is a longitudinal section through the backshell assembly of Figures 1 to 4, with the annular locking member shown in a position midway between the locked position of Figure 1 and the unlocked position of Figure 3; Figure 6 is a rear perspective view of the backshell assembly of Figures 1 to 5, shown in the locked position; Figure 7 is a longitudinal cross-section of the backshell assembly of Figure 6; Figure 8 shows a tool for unlocking the backshell of Figures 1 to 7; Figure 9 is a rear perspective view of a second embodiment of backshell assembly in accordance with the present invention, for use with a cable bundle having a braid; Figure 10 is an exploded view of the backshell assembly of Figure 9; Figure 11 is a rear perspective view of a third embodiment of a backshell assembly in accordance with the present invention, for use with a cable bundle having a sleeve, Figure 11 showing the cable bundle and sleeve; Figure 12 is a longitudinal cross-section through the backshell assembly and cable bundle of Figure 11; Figures 13 and 14 are rear perspective views a backshell assembly and a cable cradle of the backshell assembly, that may be mounted at different angles; Figure 15 is a perspective view of a fourth embodiment of a backshell 113 assembly in accordance with the present invention in an unlocked state; Figure 16 is a longitudinal cross-section of the backshell assembly of Figure 15 in an unlocked state; Figure 17 corresponds to Figure 16, but shows the backshell assembly in a locked state; Figure 18 is a front perspective view of a fifth embodiment of a backshell assembly in accordance with the present invention, similar to that shown in Figure 1 but where each component of the backshell assembly may be split into two halves in a longitudinal plane; Figure 19 is an exploded view of the backshell assembly of Figure 18; Figures 20 to 22 show, to an enlarged scale, the components of the backshell assembly of Figure 19; Figure 23 is a rear perspective view of a sixth embodiment of a backshell assembly in accordance with the present invention and for use with a cable bundle having a sleeve, the backshell assembly being similar to that shown and described with reference to Figure 11, but which may again be split into two halves in a longitudinal plane; Figure 24 is a longitudinal cross-section of the backshell assembly of Figure 23; Figure 25 is an exploded view of the backshell assembly of Figures 23 and 24; Figures 26 and 27 show the cable guide and annular locking member, of the backshell assembly of Figure 25 but to an enlarged scale; Figure 28 is a perspective view of a transition piece for a cabling system; Figure 29 is a perspective view of a jig for the transition piece of Figure 28; Figure 30 shows the transition piece of Figure 28 mounted on the jig of Figure 29; Figure 31 is a perspective view of a transition piece shown in Figure 30 with a top cover removed; Figure 32 is a perspective view of a further transition piece, similar to that of Figures 28 to 31, for use with a sleeved cable bundles; Figure 33 is an exploded view of the transition piece of Figure 32; and 113 Figure 34 shows the transition piece of Figures 32 and 33 with the top cover removed with cable sleeves shown, but with the cable bundles omitted for clarity.

Referring now to Figures 1 to 8, here there is shown a backshell assembly and the components thereof, in accordance with a first embodiment of the 15 invention.

With reference primarily to Figure 1, the backshell assembly 1, is generally cylindrical in shape and has a central longitudinal axis. The backshell assembly has a proximal end 2 and a distal end 3. The proximal end 2 is arranged to connect to a connector with an external thread (not shown) and the distal end 3 is arranged for receiving a cable bundle of a wiring harness or similar (not shown) which passes through the backshell assembly 1 to the connector (not shown). The connector will normally have a rubber plan form built into it, with a number of connection points into which each cable of the cable bundle will terminate and make electrical connection thereto, in a conventional manner.

The backshell assembly 1 has, at its distal end 3, a cradle 4 for supporting the cable bundle and this has provision for a clip or tie to be secured around the cable bundle. This is used to secure the cable bundle to the cradle 4, such that when the backshell assembly 1 is, in this embodiment, threaded onto the connector, the backshell assembly 1 retains the cable bundle in proximity to the connector and prevents the cable bundle from being pulled away from the connector. The backshell assembly 1 thus provides strain relief for the cables of the cable bundle connected to the connector, in a conventional manner.

Referring now to Figure 2, this shows separately the major components of the backshell assembly 1. At the core of the backshell assembly 1 is a central cable guide 5, coaxially arranged with a fastening ring 6 (for attaching the cable guide 5 to a connector) and an annular locking member 7. As will be seen from subsequent embodiments, the annular locking member 7 may take various forms but, in this embodiment, it is in the form of a generally cylindrical ring. The 113 fastening ring 2 has an internal screw thread 8 for screwing onto an external screw thread of a connector. Behind the internal screw thread 8 is an inwardly extending flange 9, having a proximal facing annular surface 10.

When the backshell is assembled, as best seen in Figures 1 and 5, the cable guide 5 is inserted from the proximal end 2 into the fastening ring 6. A main body portion 11 of the cable guide 5 has an external diameter that substantially matches that of the internal diameter of the inwardly extending flange 9 of the fastening ring 6.

Towards a proximal end of the main body portion 11, of the cable guide 5, is located an outwardly extending annular flange 12, having a serrated proximal facing annular surface 13 and a flat distal facing annular surface 14. The distal facing annular surface 14 of the cable guide 5 abuts the proximal facing annular surface 10 of the fastening ring 6. Thus, once the annular locking member 7 is placed over the end of a cable bundle and the assembled fastening ring 6 and cable guide 5 have subsequently been passed onto the end of the same cable bundle, the cables of the cable bundle may then be connected to the connector in a normal manner. The fastening ring 6 can then be threaded onto an external thread of a connector using the knurled outer surface 15 of the fastening ring 6 to tighten the fastening ring 6 by hand and without the use of tools. The inwardly extending flange 9, acting on the outwardly extending flange 12, then acts to clamp the cable guide 5 to the connector. The serrated proximal facing annular surface 13 of the cable guide 5 is, at that point, then engaged with corresponding serrations on the connector (not shown) to prevent rotation of the cable guide 5 relative to the connector.

When the cable guide 5 and fastening ring 6 have been secured to a connector in the above-described manner, the backshell assembly 1 will be as shown in Figure 3, with the cable bundle (not shown in Figure 3) extending through the backshell assembly and being connected to the connector.

113 In order to prevent the fastening ring 6 from coming undone, previously it has been required to use tools to torque the fastening ring to a specified toque, or to incorporate some type of ratchet mechanism to prevent the fastening ring coming undone. However, the use of tools can result in them accidentally being left behind in a vehicle or the like and thus the use of tools is not particularly desirable.

Furthermore, ratchet like mechanisms may require additional components and may hinder subsequent removal of the backshell assembly, or prevent reuse and more particularly reliable reuse. In order to avoid such issues, the present invention provides an annular locking member 7 to engage with the fastening ring 6, as will subsequently described.

The annular locking member 7, of this embodiment, is shown in Figure 4. This has a plurality of splines 16 extending from a proximal face 17. The splines 16 are arranged to engage with corresponding splines 18 on a distal facing face of the fastening ring 6.

With reference to Figure 4, on an inner surface 19 of the annular locking member 7 there is provided a pair of engagement means 20, the second one opposed to the first one cannot be seen in Figure 4. The inner surface also has two sets of retention means 21, again the second set opposed to the first set cannot be seen in Figure 4. The retention means 21 each comprise two serrations 22, the proximal facing faces of which are less inclined than the distal facing faces, as can perhaps be most clearly seen from the longitudinal cross section of Figure 5.

With reference now to Figure 3, the cable guide 5 has, in the main body portion 11, two opposed cut out tabs 23, which can also be seen in Figure 5. These are resiliently biased to the position shown in Figure 3 and 5, but they may be urged inwardly. Each of the tabs 23 has serrations 24 arranged to engage with the serrations 22 of the angular locking member 7.

The main body portion 11 of the cable guide 5 also has an opposed pair of slot-like recesses 25, arranged to accept respective engagement means 20 of the annular locking member 7.

Thus, with the cable guide 5 positioned on a connector and locked in place by the fastening ring 6, so that is cannot rotate on the connector, the annular locking member 7 may then be pushed in the proximal direction over the cable guide 5, from the position shown in Figure 3, through the position shown in Figure 5 to the position shown in Figures 6 and 7. Here the engagement means 20 of the annular locking member 7 are engaged with the respective slot-like recesses 25 of the cable guide 5, preventing rotation of the annular locking member 7 relative to the cable guide 5. In addition, the splines 16 of the annular locking member 7 are now engaged with the splines 18 of the fastening ring 6, preventing the fastening ring 6 from being rotated. In this "locked" position the retention means 21 on the inside of the annular locking member 7 are engaged with the serrations 24 on the tabs 23 of the cable guide 5, to retain the annular locking member 7 in place in the position shown in Figures 6 and 7.

The sets of serrations 22 and 23 may be dimensioned, as in this embodiment, to make it relatively hard to pull the annular locking member 7 out of engagement with the fastening ring 6. Indeed, they may be dimensioned such that it is not possible to simply pull the annular locking member 7 out of engagement with the fastening ring 6. Where it is desired, the annular locking member may be used to lock the fastening ring in rotational position without the use of tools, merely by pushing the annular locking member into contact with the fastening ring 6, but where it is desirable not to then be able to remove the annular locking member 7, by simply pulling it out of contact with the fastening ring 6 then, as shown in Figure 4, a pair of apertures 26 may be provided to permit prongs 27 of release tool 28 of Figure 8 to pass through the annular locking member 7, to depress the tabs 23 of the cable guide 5 to permit the annular locking member 7 to then be pulled distally away from the fastening ring 6. This will then release the fastening ring 6, so that it may, once again, be unscrewed from the connector to release the backshell 113 assembly 1.

Two further embodiments of backshell assemblies in accordance with the present invention will now be described with reference to Figures 9 to 12. Each of these embodiments comprise a cable guide, annular locking member, fastening ring and cradle similar to, or the same as, those of the above described first embodiment. It will thus be apparent that these each have the same features as the previously described equivalent components of the first embodiment, and that these function in the same manner. For this reason, these common features will not be described again here.

Referring now to the second embodiment, shown in Figures 9 and 10, this comprises a fastening ring 6, identical to that described in the first embodiment. However, in the embodiment of Figures 9 and 10 the backshell assembly, indicated generally as 29, has a cable guide 30 and annular locking member 31 which are slightly modified, relative to the equivalent components of the first embodiment, in order that they may each receive a cable bundle 32 having a braid 33. Thus the cable guide 30 now has a main body which now comprises an outer tubular portion 34 and an inner tubular portion 35, which are spaced apart and joined that their proximal ends to define an annular void 36 dimensioned to receive the cut end of the braid 33. The inner tubular portion 35 extends distally further than the outer tubular portion 34 and the purpose of this will be described subsequently with reference to the embodiment of Figures 11 and 12.

Referring again to Figures 9 and 10, here it can be seen that the annular locking member 31 now has an extended tail portion 37, through which the cable bundle and braid also pass and the purpose of which will again become apparent from the subsequent description of the embodiment of Figures 11 and 12. Figure also illustrates a clip or tie for securing the cable bundle 32 and braid 33 to the cradle 4, a seen in Figure 11.

Shown in Figures 10 and 11 is a lacing tape clip assembly, indicated generally as 101, comprising two parts of a clip 102 attached to either end of a length of lacing tape 103. One part of the clip 2 is attached under the cradle, with the second part of the clip 102 being passed over the cable bundle 32 and braid 33, prior to the second part of the clip 102 then being engaged in the first part. The lacing tape 103 may then be tensioned in the clip 102, to snuggly secure the cable bundle 32 and braid 33 in the cradle 4.

Referring now to the embodiment of Figures 11 and 12, this third embodiment is almost identical to that Figure 9 and 10, except that, in this embodiment, the backshell assembly indicated generally as 38, is arranged to receive a cable bundle 32 having a cable sleeve 41. This cable sleeve 41, although not apparent from Figure 11, is split lengthwise and is manufactured so that it is biased to a closed position, where it wraps over the cable bundle 32 and overlaps on itself and therefore has a portion which is of double thickness. In order to accommodate this double thickness, both the cable guide 39 and annular locking member 40 of this third embodiment have appropriate cutaway portions 42, in order to accommodate the region of double thickness of the cable sleeve 41.

Referring now to Figure 12, it will be appreciated from this that with the embodiment of Figures 11 and 12 (and that of Figures 9 and 10), the cable sleeve 41 (or braid 33) extends over the inner tubular portion 35 of the cable guide 39, with the tail portion 37, of the annular locking member 40, having an internal diameter such that the cable sleeve 41 (or braid 33) is slightly compressed by the action of the annular locking member 40 being moved proximally (to the left as shown in Figure 11) to the locked position indicated in Figure 11. This acts to anchor the cable sleeve 41 (or braid 33) in position. Furthermore, the distal end 43 of the annular locking member 40, in both embodiments, has a further reduced diameter to substantially match that of the cable sleeve 41, when the cable sleeve 41 (braid 33) is on the cable bundle 32, such as to also slightly compress (or pinch) the cable sleeve 41 against the cable bundle.

The internal diameter of the distal end 43 is less than the outer diameter of 113 the inner tubular portion 35 of the cable guide 39 (in both the embodiments of Figures 11 and 12 and that of Figures 9 and 10), with the distal end 43 of the tail portion 37 of the annular locking member 40, extending inwardly at a point separated from the distal end 44 of the inner tubular portion 35, by a distance substantially equal to the thickness of the cable sleeve 41. This forces the cable sleeve 41 (or braid 33) to perform a chicane at the point indicated as 46 in Figure 12, so that in the locked position the distal end 43 of the tail portion 37 prevents the cable sleeve 41 (or braid 33) pulling out from the backshell assembly 29 or 38.

In the previously described embodiments, see Figure 10 for example, it will 20 be apparent that the cradle 4 may adopt a 0° angle as shown, a 45° angle or a 90° angle, as is evident from the "W"-shaped indented portion 47 in the cradle mounting fin 48, extending from annular locking member 31.

Referring now to Figures 13 and 14, here it will be seen that a mounting fin 49 for a cradle 50 may comprise two walls which sandwich a single leg 51 of the cradle 50. One inner facing surface of the fin 49 has a plurality of protrusions 52 which interact with a splined boss on a resilient tab 53a within the (outer) side of leg 51. A control arc boss 53 on one side of leg 51 engages a corresponding cut (not shown) in the opposing inner face of mounting fin 49, trapping leg 51 within mounting fin 49 when deployed. Rotation permits the cradle 50 to be mounted at an almost infinite range of angles between 0 and 90°. The arrangement shown in Figure 10 could be similarly modified to replace the W-shaped recess 47 with a plurality of protrusions, similar to the protrusions 52 of Figures 13 and 14, to cooperate with each of the legs of the cradle 4 of Figure 10.

Referring now to Figures 15 and 16, here there is shown an embodiment very similar to that of Figures 11 and 12, but here the backshell assembly 54 has a further modified cable guide 55 and angular locking member 56. The outer tubular portion 34 of the cable guide 55 now terminates at its distal end in a plurality of fingers 57, which can each be depressed radially inwards against the resilience of the material of the cable guide 55. With reference to Figure 16, showing the 113 backshell assembly 54 in an unlocked position, here an annular ridge 58 can be seen on the inner surface of the annular locking member 56, which ridge 58, when the annular locking member 56 is moved to the locked position as shown in Figure 17, will engage with the fingers 57, by compressing those fingers and sliding over those fingers 57 until the annular ridge 58 engages in grooves 59 in the end of each of the fingers 57. The dimensions of the annular ridge 58 and grooves 59 can be selected so that, once the annular locking member 56 is pushed into the locked position shown in Figure 17, it is no longer possible to release it. This thus provides for a permanent fit of backshell assembly on to a connector, so that the backshell assembly can never subsequently be removed, which is desirable for certain applications.

It will be noted from Figure 15 that, in this embodiment, the previously mentioned tabs 23 and serrations 24 are retained on the cable guide 55, but which have no purpose when used with the annular locking member 56 of Figures 15 and 16. However, these tabs 23 and serrations 24 permit the cable guide 55 to be used with either a one time fit annular locking member 56, as shown in Figures 15 and 16, or a releasable annular locking member, such as the annular locking member 50 of Figures 11 and 12.

Referring now Figures 18 to 21, here there is illustrated a backshell assembly 60 which is very similar to that illustrated with reference to Figures 1 to 8. However, in this embodiment, the fastening ring 61, cable guide 62 and annular locking member 63 can each be split into two halves in a longitudinally extending plane.

Figure 20 shows in greater detail the cable guide 62 split into two parts 62a and 62b. The upper pad 62a has a pair of grooves 64 for receiving splines 65 of the lower portion 62b. This permits the upper portion 62a to slide into position longitudinally on the lower portion 62b, with pips 66 on the upper portion 62a engaging in recesses 67 on the lower portion 62b, to lock the upper and lower portions together.

With reference to Figure 21, this shows the fastening ring 61 comprising an upper portion 61a and lower portion 61b, the upper portion has a pair of grooves 68 for receiving splines 69 on the lower portion, with resiliently mounted pips 70 on the upper portion 61a engaging recesses 71 on the lower portion 61b to lock the upper portion 61a in place on the lower portion 61b.

With reference to Figure 22, this shows the annular locking member 63 comprising an upper portion 63a and lower portion 63b. The lower portion 63b has recesses 72 for receiving legs 73, extending from the upper portion 63a, so that the lower portion 63a and upper portion 63b may be assembled together radially. It will be noted here that the two components 63a and 63b will in use be retained together by being retained within the fastening ring 61, when the backshell assembly 60 is in the locked position.

Another feature to note about the embodiment of Figure 19, is that the cradle 74 is arranged to be a push-fit into a recess 75, provided in the back of cable guide 62, as seen in Figure 20.

Referring now to Figures 23 to 25, these show an embodiment essentially identical in both form and function to that of the embodiment of Figures 11 and 12.

In the embodiment of Figures 23 to 25 each of the components can be split in a similar manner to those previously described with reference to the embodiment of Figures 18 to 22. Thus, the backshell assembly, indicated generally as 76, comprises similar split components and, as shown in Figure 25, comprises a split cable guide 77, a split fastening ring 78 and a split angular locking member 79. The fastening ring 78 is the same as fastening ring 61 previously described with reference to Figure 21. However, the cable guide 77 and annular locking member 79 are slightly different, in that they have inner and outer tubular portions and a tail portion respectively, as can be seen from the enlarged detail of the cable guide 77 shown in Figure 26. This has an upper portion 77a and a lower portion 77b for longitudinal sliding engagement with each other in the manner previously described. Similarly, the angular locking portion 79, shown in enlarged detail in Figure 27, comprises an upper portion 79a and a lower portion 79b arranged to longitudinally slide together in the manner previously described with reference to previous embodiments.

With a backshell assembly comprising components that can each be split in a longitudinal plane, it is possible, after assembly on a cable bundle having an openable cable sleeve, to replace, add, or remove one or more cables, whilst leaving the remaining cables of the cable bundle connected to a connector.

Referring now to Figure 28, here there is shown a first transition element for a cable system, which transition element may advantageously be used in a cable system having backshells which can be split in the longitudinal plane, as previously described, but they may also find use in other applications.

The transition element 80, shown in Figure 28, can be mounted on a jig 81, in the same manner as an alternative transition element 82 is shown mounted on the jig 81 in Figure 30. This permits the transition element 80 to be conveniently retained in place.

Referring now to Figure 31, this shows the transition element 80 of Figure 28 with an upper portion of housing 83 removed. Here a cable bundle 84a can be seen to transition into two smaller cable bundles 84b and 84c. The housing 83 has apertures 86 to 89 of equal size. In each is located an appropriate reducer 90 to 93, each of which can be split into two halves. Each of the reducers 90 to 93 is formed of a compressible material, such as rubber, such that a reducer having an appropriately sized internal diameter may be selected for the size of cable bundle to pass therethrough, with the reducer positioned on the cable bundle and sandwiched in place between the two parts of the housing 83, to hold the cable bundles 84a, 84b and 84c in place and reduce strain on the cables inside the transition.

113 Figures 32 to 34 illustrate a similar embodiment, but in this embodiment two reducers 94, 95, again of different internal diameters, are located in uniformly sized apertures in housing 96. Each of the reducers 94, 95 are arranged to receive cable bundles having cable sleeves 97, 98 of different diameters. The cable sleeves 99 and 100, associated with different cable bundles, each have a diameter matching that of the apertures in the housing 96, such that they do not require the use of a reducer within the housing 98 and instead the cable sleeves 99, 100 each engage directly with the apertures in the housing 96. In this embodiment all the components are metal, or made in an alternative plastic or resin (non-metal) material, which may have a conductive coating, so at to ensure EMC continuity across the transition 82.

Several embodiments of the present invention have been described by way of example only, with reference to the accompanying drawings, so it will be apparent that many modifications may be made which fall within the scope of the appended claims.

Claims

Claims 1. A backshell assembly, for connecting a cable bundle to a connector, the backshell assembly comprising: a cable guide, substantially cylindrical in shape, through which a cable bundle may pass from a distal end to a proximal end of the backshell assembly, wherein the proximal end of the backshell assembly is arranged to connect to a connector, the cable guide having a proximal face arranged to engage with the connector in a manner that prevents relative rotation between the connector and the cable guide, the cable guide further comprising means for engaging directly or indirectly with the cable bundle to retain the cable bundle in position in the cable guide to prevent the cable bundle from being pulled out of the backshell assembly and/or to provide strain relief; a fastening ring coaxial with and extending around the cable guide, the fastening ring being arranged to engage with the cable guide in manner that it may urge the cable guide in a proximal direction towards a connector, in order to retain the cable guide in contact with the connector, the fastening ring being arranged to be rotated on a connector to retain the cable guide in place against the connector in a manner in which the cable guide may not rotate relative to the connector, the fastening ring having a plurality of first splines or grooves extending longitudinally from a distal face of the fastening member; and an annular locking member coaxial with and extending around the cable guide and being arranged to slide in a longitudinal direction along the cable guide, the locking member having a second plurality of splines or grooves extending longitudinally from a proximal face of the locking member and arranged to engage with the first plurality of splines or grooves on the fastening ring, wherein: the locking member and cable guide comprise cooperating engagement means to permit the locking member to slide longitudinally along the cable guide and to prevent rotation of the locking member on the cable guide, such that when the cable guide is held in place against a connector by the fastening ring and the cable guide is rotationally fixed to the connector, the locking member may slide proximally to a locked position wherein the first plurality of splines or grooves engages with the second plurality of splines or grooves to prevent subsequent rotation of the fastening ring.
2. A backshell assembly as claimed in Claim 1, wherein the fastening ring has a proximal facing annular surface extending radially inwardly from an inner surface of the fastening ring and wherein the cable guide has a distal facing annular surface extending radially outwardly from an outer surface of the cable guide, the proximal and distal facing annular surfaces being arranged to engage in a longitudinal direction in order that the fastening ring may retain the cable guide in a proximal position, in contact with a connector, the cable guide further comprising one or more first retention means arranged to engage with one or more second retention means on the annular locking member, to retain the annular locking member in the locked position, wherein engagement of the first and second plurality of splines prevent rotation of the fastening ring relative to the annular locking member and the cable guide.
3. A backshell assembly as claimed in Claim 2, where one of the first and second retention means comprises one or more serrations with angled faces, the angled faces being arranged to require a greater force to be required to displace the annular locking member distally on the cable guide, from the locked position to an unlocked position, than is required to displace the annular locking member proximally on the cable guide, from the unlocked position to the locked position.
4. A backshell assembly as claimed in Claim 2 or 3, wherein the first retention means is located on one or more resilient tabs formed in a peripheral wall of the cable guide.
5. A backshell assembly as claimed in Claim 4, wherein the annular locking member substantially extends over the one or more tabs of the cable guide and prevents access to those tabs, but wherein one more passages are provided through the annular locking member to permit a tool to pass through the annular locking member and depress the one or more tabs to release an associated first retention means to permit the annular locking member to move distally along the cable guide.
6. A backshell assembly as claimed in any preceding claim, wherein the cable 5 guide has a cradle extending therefrom and a clamp arranged to secure the cable bundle to the cradle.
7. A backshell assembly as claimed in any preceding claim, wherein the cradle is pivotally attached to a main body of the cable guide, so that the cradle may be 113 set at one of a plurality of predefined angles, relative to a longitudinal axis of the backshell assembly.
8. A backshell assembly as claimed in any preceding claim, wherein the fastening ring has an internal screw thread arranged to screw onto an external screw thread of a connector.
9. A backshell assembly as claimed in any preceding claim, wherein the cable guide comprises a first tubular portion and a second tubular portion arranged coaxially inside the first tubular portion, wherein the first and second tubular portions are joined at or towards a proximal end of the cable guide and wherein the first and second tubular portions are spaced apart from each other and are open towards a distal end of the cable guide, so as to define an annular cavity between the first and second tubular portions, wherein a central lumen of the second tubular portion is arranged to permit a cable bundle to pass there through and the annular cavity between the first and second tubular portions is arranged to receive a braid or sleeve of the cable bundle.
10. A backshell assembly as claimed in Claim 9, wherein the annular cavity has a width in a radial direction around its circumference sufficient to accommodate a single layer of braid or sleeve, but at one portion has a width in a radial direction sufficient to accommodate the double thickness of an overlapping portion of a sleeve.
11. A backshell assembly as claimed in Claim 9 or 10, wherein: the second tubular portion extends in a distal direction to a greater extent that the first tubular portion; the annular locking member comprises a tubular tail portion which, in the locked position, extends coaxially with and over at least part of the second tubular portion of the cable guide; and wherein the spacing between an inner surface of the tail portion of the annular locking member and the outer surface of the second tubular portion of the cable guide is 113 slightly less than the thickness of a braid or sleeve of a cable bundle, which the backshell assembly is intended to be used with, such that when the locking member is in the locked position the braid or sleeve is at least slightly compressed between the second tubular portion of the cable guide and the tail portion of the annular locking member.
12. A backshell assembly as claimed in Claim 11, wherein, when in the locked position, the tail portion of the annular locking member extends beyond the end of the second tubular portion of the cable guide, to define a distal end of the tail portion, the distal end of the tail portion having a reduced inner diameter equal to or less than the outer diameter of the second tubular portion.
13. A backshell assembly as claimed in Claim 12, wherein the inner diameter of the distal end of the tail portion of the annular locking member is substantially equivalent to the diameter of a braid or sleeve of a cable bundle that the backshell assembly is intended to be used with.
14. A backshell assembly as claimed in Claim 12 or 13, wherein the reduction in the inner diameter of the tail portion at the distal end of the tail portion defines a proximal facing annular surface which, when in the locked position, is spaced apart from an end face of the second tubular portion of the cable guide by a distance equal to or less than the thickness of a braid or sleeve of a cable bundle which it is intended that the backshell assembly be used with.
15. A backshell assembly as claimed in any one of Claims 12 to 14, wherein the second tubular portion and tail portion are arranged to cooperate with each other, such that moving the annular locking member from an unlocked position to the locked position causes a braid or sleeve of a cable bundle passing through the backshell to both be sandwiched and compressed between the second tubular portion of the cable guide and an inner surface of the tail portion of the annular locking member, and causes the braid or sleeve sandwiched therein to transition, at a point beyond the distal end of the second tubular portion, to a reduced diameter, where it is compressed by the tail portion of the annular locking member against cables of a cable bundle.
16. A backshell assembly as claimed in any of Claims 9 to 15, wherein the first tubular portion of the cable guide comprises, towards its distal end, a plurality of resilient fingers which may be compressed radially inwards, each finger having an engagement member towards its distal end arranged to engage with a corresponding engagement member on an inner face of the annular locking member, wherein pushing the annular locking member proximally over said fingers causes the fingers to be deflected radially inwards, as the engagement members on each finger engage with the engagement member or members on the inner surface of the annular locking member, to act to retain the annular locking member in the locked position.
17. A backshell assembly as claimed in any preceding claim, wherein each component of the backshell may be split in half longitudinally.
18. A backshell assembly as claimed in Claim 17, wherein the fastening ring comprises two halves split longitudinally, which two halves are arranged to engage with each other by a first half sliding longitudinally relative to the second half, so that appropriate grooves or splines on each engage with each other to resist separation radially of the two halves.
19. A backshell assembly as claimed in Claim 18, wherein the fastening ring has an internal screw thread arranged to be screwed onto an external screw thread of a connector whereby, when the fastening ring is screwed onto an external screw thread of a connector, the two halves of the fastening ring are prevented from being longitudinally displaced relative to each other and are thus locked together.
20. A backshell assembly as claimed in any one of Claims 17 to 19, wherein the cable guide is split longitudinally and comprises two halves which are arranged to engage with each other by a first half sliding longitudinally relative to a second half, 113 such that appropriate grooves and/or splines engage with each other, wherein the two halves comprise a snap fit mechanism, which acts to retain the two halves in an assembled configuration.
21. A backshell assembly as claimed in Claims 17 to 20, wherein the annular member is split longitudinally into two halves, which two halves are arranged to be brought together radially to engage with each other.
22. A backshell assembly as claimed in any preceding claim, which is electrically conductive or has an electrically conductive coating.
23. A wiring harness comprising a cable bundle with a sleeve that may be opened along its length, with the harness terminating at one point in a backshell as recited in any one of claims 17 to 21.
24. A transition piece for a cable bundle, the transition piece having a housing comprising a bottom portion and a top portion, separable from each other such that the top portion may be removed and a cable bundled arranged in the bottom portion, the transition piece having a plurality of apertures each arranged to receive a cable bundle, which apertures in the housing are each of a common diameter, the transition piece further comprising a plurality of reducing members each having a common external diameter to be received in any one of the apertures of the transition piece, with the reducing members selected from a set having different internal diameters so that the internal diameters may be matched to the diameter of a cable bundle passing therethrough.
25. A transition piece as claimed in Claim 24, where the two halves of the housing are arranged to retain each of the reducers in place and compress the reducers such as to at least partly act to retain the cable bundle in place in each respective aperture of the housing.