CABLE CONDUIT SYSTEM FOR VEHICLES

Abstract: A conduit system for cables adapted for mounting in a vehi­ cle including constant cross-sectional elongate channel ele­ ments (1) having one or more channels (3) formed therein and retention means (18) and locking means (19) for holding the ca­ bles within the or each channel at intervals along their lengths. The conduit system may comprise a plurality of straight chan­ nel elements (1) connected end to end, for example in an aircraft fuselage. Alternatively, where a change of direction and/or ele­ vation is necessary the straight channel elements may be inter­ connected by curved joining elements (2).

Description: This invention relates to conduit systems for filamentary members such as electrical cables or light guides, which conduit systems are suitable for mounting in vehicles, particularly, but not exclusively, aircraft. For ease of description these filamentary members will henceforth be referred to as cables. More and more cable runs are required in vehicles as technology grows. In aircraft for example, fly-by-wire and fly-by-light systems are becoming the norm both in military and civil projects. Similarly, in other vehicles electrical or light signalling is more and more usual. In vehicles, particularly aircraft, there are problems of access to effect the installation of such cable runs both in original installations and in the installation of additional cable runs during the life of the vehicle, and for inspection of such runs during installation and subsequently. There are also problems of adverse electrical interaction between adjacent cable runs carrying different electrical signals, especially where the runs are forced closely together in congested areas. Additionally, where lightning strikes are possible the system must be totally immune to the high transient voltages which can occur. Moreover, any possibility of damage to the cables during routine work on or adjacent the cable runs must be minimised. The present invention has for an objective the provision of a conduit system which goes some way to overcoming these listed problems in a relatively inexpensive and lightweight manner. One known arrangement of vehicle conduit system for cables is described in DE-A-2103.952 in which two channel sections of constant cross-section are connected end to end. The arrangement further describes means for holding the cables within the conduit system by means of retaining members which are a push-fit inside the channel sections at intervals along their length and locking means which secure each retaining member in position. According to the present invention there is provided a conduit system, especially for mounting cables in a vehicle, said conduit system comprising at least three conduit elements positioned in end to end relationship each having an equal multitude of channels for holding cables and including cable retention means being a push fit within its associated channel for retaining cables at intervals along their lengths when installed therewithin; characterised in that the channels of each conduit element lie substantially in alignment with the channels of the adjacent conduit element and the end of each conduit element lies closely adjacent to but set apart from its adjoining conduit element, at least two of said conduit elements being straight and at least one being curved and two or more straight conduit elements being inter connected by one or more curved conduit elements, the channels of the curved conduit elements being of slightly greater width than the channels of the straight conduit elements and the ends of the straight conduit elements being slightly flared to effect a smooth transmission between the channels of adjacent conduit elements. said cable retention means further comprising a locking member in the form of an elongated tie member secured within the associated channel, said tie member having a series of serrations along its length and said cable retaining member having an aperture therethrough for receiving said tie member and also having means for engaging and interlocking with the serrations of the tie member such that the cable retaining member imparts a retaining force on the cables and the tie member engages with the cable retaining member and locks it in place. Although in the preferred embodiment the channel elements are of metal, non-metallic materials adapted to include electrically conductive pathway means may be utilised. For example, the non-metallic elements may be of a suitable moulded plastic material having a metallised surface or combining metallic particles or elements dispersed within the material in a manner to provide said electrically conductive pathway means. It will be appreciated that the utilisation of non-metallic materials may be additionally beneficial since the individual channel elements may be readily moulded and accommodate necessary changes of direction and/or elevation thereby reducing the need for the provisioning of separate curved joining channel elements, inter-connecting attachment means and electrical continuity bonding between the adjoining elements. There may be additional benefit in terms of weight saving which is a critical factor in aircraft structures. Some embodiments of a conduct system suitable for mounting in an aircraft structure are described by way of example with reference to the accompany drawings in which: Figure 1 is a plan view of portion of conduit system, Figure 2 is a section on line II-II of Figure 1, Figure 3 is a section on line III-III of Figure 1, Figure 4 and 5 respectively show typical channel elements in cross section with suitable dimensions in millimetres. Figures 6, 7 and 8 show a plan, an elevation, and cross section, the cross section being taken from arrows VIII-VIII of Figure 6, respectively of a region of the conduit system loaded with cable and attached to an aircraft structure, Figures 9 and 10 respectively show small and large cable retaining members in both plan and cross section, Figure 11 is a similar view to that of Figures 5 and 8 illustrating the incorporation of a fairlead arrangement, Figure 12 is a similar view to that of Figure 11 showing an alternative fairlead arrangement, and, Figure 13 illustrates a tie member. Figure 14 illustrates a further typical channel element as an alternative embodiment of this invention. A conduit system basically comprises two types of channel element, namely, straight elements 1 and curved elements 2. These combine, when in end to end relationship, to form what can be described as a raceway within which lengths of filamentary signal carrying members such as electrical cables or light guides can be placed and retained. The straights 1 are formed of light alloy sheet pressed to provide the plurality of channels 3, each of constant width and depth. The interior of each channel 3 is coated with PTFE to give both insulation and low friction, the latter being necessary if cables are to be moved. The coating is also instrumental in the avoidance of chaffing. The curves 2 are formed of precision cast light alloy with the same number of channels therein as the straights with which they will be associated in use. These channels, referenced 4, are again PTFE coated. The individual channels 4 are formed of slightly greater width than the individual channels 3 with which in use they will be in register; that is to say their sidewalls are thinner. This means that precise lateral location between the straights and curves is unnecessary. Naturally, the end regions of the channels 3 and 4 are rounded so that no sharp edges are present to interfere with the cable runs. This is particularly important where the channels 3 and 4 are not in exact register; it is also important where, as in this embodiment, gaps are provided as a matter of design choice between successive elements of the raceway. Referring now to Figures 6-8, and in particular to Figure 7, a mounting arrangement for a) connecting adjacent straights together, and b) mounting said interconnected straights to an aircraft structure shown in Figure 7 at reference 5 is illustrated. A Z-section bracket 6 is arranged to extend from the structure 5 and on the respective ends of the straights similar joggled interconnecting lugs 7 are arranged to extend rearwardly of the straights and are coupled one to another and to the bracket 6 by means of a nut and bolt arrangement 8. Naturally, the shape of the bracket 6 is a matter of design; it could be "top hat" shape if desired. Access to the nut and bolt arrangement 8 is from the front of the raceway through the gap 9, to which reference has been previously made, incorporated between the ends of the adjacent straights. The ends of the straights, in addition to being radiused, are bell-mouthed at 10 to prevent cables being snagged by sharp edges. Reverting to Figures 1-3, mounting arrangements are shown for the interconnecting regions between the curves at the straights. Again a bracket 11 of Z-section projects from the aircraft structure 5. Each straight has a mounting lug 12 extending from its end and is coupled to the bracket 11 by means of two nut and bolt arrangements 13. Access to these nut and bolt arrangements is with the curve removed; again access is from the front. The curves are attached to the bracket 11 by means of similar nut and bolt arrangements 14 lying on wings 15 positioned one to each side of the raceway itself. The nut and bolt arrangements 14 are thus accessible from the front. Referring again to Figures 6-8, which show cables 16 in place in the raceway, means are now described by which these cables are actually held in place. Such means comprise retention units positioned at space intervals along the straights. Each retention unit includes two members, one is a cable retaining member of block-like form whilst the other is a locking member designed to hold the cable retaining member in a cable retaining position. Each retaining member is in the form of a plastic block 18 which is a push-fit into each channel and closely engages the internal flanks of its associated channel. Whilst it would be possible to ensure that the mere engagement of the block with the flanks of its associated channel would be sufficient to hold the block in its cable retention position, particularly if the flanks of the channels were provided with serrations engagable by ratchet means on the block, it is found that more conveniently the locking means can be in the form of a tie member 19 which projects from a central region of the base of a channel outwards into the channel. Each tie member can be formed of a resilient plastics material of a strip like form with a series of serrations 23 along its flanks. In this case each block 18 has an aperture through its centre through which the tie member extends, the aperture being provided with ratchet means integrally formed with the block to resiliently engage the serrations on the tie member in such a way that once the block is inserted it cannot be removed without a special tool. Again, insertion is from the front. The tie member 19 may merely have anchorage means at one end which allows the tie member itself to protrude through a specially formed aperture in the base of the channel and the anchorage means engages with the base of the channel, in which case insertion would require to be from the rear of the raceway. Alternatively, and as illustrated in Figure 13, the tie member 19 may have a spear or harpoon shaped arrangement at its anchorage end which allows insertion from the front of the raceway and also prevents easy removal. In Figures 9 and 10 two examples of the blocks 18 are illustrated, that of Figure 9 being suitable for small width channels, and that of Figure 10 being suitable for larger width channels. In each case the ratchet means, integrally formed with the block, is illustrated at 20. The cable holding capacity of a channel can be arranged such that the cable retaining block 18 lies flush with the channel mouth when the channel is full. The block is accordingly sized so that this can take place. Indeed, the cable holding capacity may be arranged to be, say 10% greater than that initially required so that extra cables can be added. This extra capacity is shown cross hatched in Figures 11 and 12 for reference only. As further illustrated in Figures 11 and 12, fairlead blocks can be inserted in the channel and held in by means of the blocks 18. Those fairlead blocks referenced 21 have apertures therein so that further cables can be passed through them and introduced into the channel as required. Those referenced 22 have open mouthed slots therein to accommodate the cables, the slots being closed by the walls of the channels 3 as the fairlead blocks are urged in and held by the blocks 18. This is a preferred arrangement since it facilitates the slipping in and out of cables during modifications to the cable runs. In yet a further embodiment, not illustrated, the fairlead blocks are incorporated into the retaining blocks 18 to provide a dual purpose block which performs both fairlead and retaining functions. It is found that the depth of the channels provides sufficient screening to prevent adverse interaction between cable runs. Referring briefly to Figure 14 this illustrates, as an alternative embodiment, a further typical channel element of extruded cross-sectional form provided with a plurality of Channels 3. As in the case of the channel element previously described, the interior of each channel is coated with PTFE to give both insulation and a low friction characteristic whilst additionally assisting in the avoidance of chaffing.

Claims: A conduit system, especially for mounting cables (16) in a vehicle, said conduit system comprising at least three conduit elements (1,2) positioned in end to end relationship each having an equal multitude of channels (3,4) for holding cables and including cable retention means (18,21,22) being a push fit within its associated channel for retaining cables (16) at intervals along their lengths when installed therewithin; characterised in that the channels (3,4) of each conduit element lie substantially in alignment with the channels of the adjacent conduit element and the end of each conduit element lies closely adjacent to but set apart from its adjoining conduit element, at least two of said conduit elements (1) being straight and at least one (2) being curved and two or more straight conduit elements being inter connected by one or more curved conduit elements, the channels (4) of the curved conduit elements being of slightly greater width than the channels (3) of the straight conduit elements and the ends of the straight conduit elements being slightly flared (10) to effect a smooth transmission between the channels of adjacent conduit elements. said cable retention means (18,21,22) further comprising a locking member (19) in the form of an elongated tie member secured within the associated channel, said tie member having a series of serrations (23) along its length and said cable retaining member having an aperture therethrough for receiving said tie member and also having means (20) for engaging and interlocking with the serrations of the tie member such that the cable retaining member imparts a retaining force on the cables and the tie member engages with the cable retaining member and locks it in place. A conduit system, according to Claim 1 in which each cable retaining member comprises a fairlead block having at least one cable passageway therethrough.

Inventors: LOCK, STANLEY ANTHONY BRITISH AEROSPACE P. L. C., MILLS, BRIAN EDWARD BRITISH AEROSPACE P. L. C.
Applicants: BRITISH AEROSPACE PUBLIC LIMITED COMPANY
Application year: 1985
Main classification: H02G3
IPC codes: B64D47, H02G3