A system for retaining cable

Abstract

A cable retention system comprising a longitudinal grip acting as a cable holder with body 1 and a plurality of cable slots 2 spaced apart such that a cable (10, Figure 7) can be inserted into the gri

Description

The present invention concerns a system for retaining cable in a gripping element through a series of slots and channels forming a serpentine routing path. Background Cable retention is used in a vast array of applications, covering a number of industries. Very often, cables of various constructions are required by standards and building codes to be fixed with strain relief to ensure protection against accidental or unauthorised cable removal from cable termination points, whether electrical, fibre optic or data. Cable retention is also required in areas where cables need to be pulled into position - aerially, through ducts, behind walls, through ceiling voids etc. Often in these cases it is impossible or impractical due to the construction of the cable, or the cable having an end-fixed cable connector, for the cable to be pulled from an end, and the cable must necessarily be attached to a pulling element, draw rope, or similar. In certain applications cable retention elements have a requirement to be simple to affix and remove, while also needing to be potentially installed for long periods of time without degradation of the cable restraint properties. An example of this is in the installation of fibre optic drop cables from telegraph poles to customer properties, where both ends of the cable require tensioning to maintain cable height over roadways and other access routes. Cable retention devices have a range of requirements. Most important is the prevention of accidental or unauthorized cable removal or slip through axial loading, either applied instantaneously or incrementally. Additional requirements include resistance to vibration induced failure, and failures due to material degradation through exposure to environmental conditions. For different materials this may include UV damage, oxidisation through exposure to water, or galvanic corrosion due to exposure to other components within the environment. Furthermore, in most cable constructions it is crucial that sharp bends or point loads are not applied to the cable as this has the potential to cause irreparable damage to the cable itself. A variety of known cable retention methods are in widespread use. A preferred method is using a clamping element, either driven by a screw fixture, a sprung element, or another method, to clamp down radially onto the cable to be retained from one or more points on the cable diameter. This has the potential to introduce point loads into the cable and increase stressing in these areas, possibly damaging delicate glass fibre cables or small diameter data cables. Another known method is the use of a contracting rubber sealing grommet, ordinarily inside a screwcap or similar to compress the rubber grommet and provide both a watertight seal, and crucially retention against pull out. While a proven technology with many applications this does require multi-part assemblies to create threaded components able to compress the grommet material. Additionally, it relies on a single area of contact on the cable, which on certain cable constructions where the outer jacket has a low coefficient of friction may require a huge amount of torque to create the requisite clamping force to prevent movement. Summary It is a purpose of the present invention to provide an improved system for gripping and retaining cable which overcomes at least some of the shortcomings mentioned in the above. According to this invention there is provided a system for retaining a cable, comprising a cable, having a circumference and a jacket, and a grip, engaging with the jacket of the cable, the grip having a longitudinal axis, positioned along the longitudinal axis of the cable, and a depth and width forming a main body which has a plurality of slots and channels arranged along its longitudinal axis, and positioned such that the cable is wound in a serpentine manner through said slots and channels, such that the surface area of the grip in contact with the cable jacket is increased. According to this invention there is also provided a system for retaining a cable, where the gripping element, or certain elements within it are formed of a flexible material. According to this invention there is also provided a system for retaining a cable, where the gripping portion comprises a plurality of grooves formed into the body, positioned in opposition to the cable slots. According to this invention there is also provided a system for retaining a cable where the grip is nominally cylindrical. According to this invention there is also provided a system for retaining a cable, where the cable comprises a connector affixed to the proximal end, and the grip comprises a cavity shaped and sized to accommodate the aforementioned connector without inducing an axial load upon it. According to this invention there is also provided a system for retaining a cable, where the gripping element is constructed of material which maintains stable material properties with prolonged exposure to UV light. Brief Description of the Drawings Figure 1: Isometric view of an embodiment of the invention, showing a single body gripping element. Figure 2: Isometric view of an embodiment of the invention, showing a single body gripping element. Figure 3: 2D view of an embodiment of the invention, showing a single body gripping element, viewed from a plane parallel to the centre of the longitudinal axis. Figure 4: 2D view of an embodiment of the invention, showing a single body gripping element, viewed from a plane parallel to the centre of the longitudinal axis and perpendicular to the planar view shown in Figure 3. Figure 5: 2D view of an embodiment of the invention, showing a single body gripping element, viewed from a plane parallel to the centre of the longitudinal axis and parallel to the planar view shown in Figure 3, from an opposing direction. Figure 6: 2D view of an embodiment of the invention, showing a single body gripping element, viewed from a plane parallel to the centre of the longitudinal axis and parallel to the planar view shown in Figure 4, from an opposing direction. Figure 7: Isometric view of an embodiment of the invention, showing a cable and grip, with the cable tracing a potential lacing pattern, prior to being fitted to the grip. Figure 8: Isometric view of an embodiment of the invention, showing a cable and grip, with the cable lacing a potential lacing pattern, having been fully fitted to the grip. Detailed Description In the following, an exemplary embodiment will be presented with reference to the figures. Figure 1 depicts a system for gripping cable, according to some implementations. With further reference to Figure 2 there is depicted a single body cable gripping device, comprising a body 1 formed along a longitudinal axis in a nominally cylindrical shape. Positioned along body 1 are a plurality of cable slots 2, sized to accommodate a known cable size. These slots may number one, two or more, and may have variable size and shape depending on the diameter of the cable to be used in conjunction with them. With reference to the XYZ axes shown in the figures, these cable slots project radially from the surface of the cylinder towards the central axis to a depth such that when installed, the outer jacket of the cable remains tangent to, or slightly within, the external circumference of the body, and the parallel walls of the slot form a tight fit on the cable such that the cable is installable and removable by hand, but is not able to slip loose on the application of an axial load or to be removed by vibration through the cable or part. In some implementations, these slots are joined by a channel 3 which is formed at an angle to the slots, in this instance 90 degrees, and to a similar depth as that of the slots 2. Alternative implementations may use a greater or lesser angle, depending on the cable construction. This channel 3 allows the joining of pairs of slots, and by forming this channel first on one side of the main body, and then the opposing parallel side of the body when intersecting with a further slot, a serpentine path can be traced along the outer body of the gripping element body 1. This serpentine path forms a complete unbroken cable routing along the longitudinal axis of the body 1 before exiting the rear of the body 1 in a channel exit 4 in a manner nominally concentric with the outside body of the gripping element. Within the aforementioned cable slots 2 and channels 3 may be positioned a number of additional gripping elements including but not limited to ribs 5 or radii 6, in order to apply further friction to the cable both to prevent slip and to accommodate any dimensional variation in either cable or gripping element. Said ribs and grooves have the further advantage of increasing resistance to accidental cable ejection from slots, and said radii allow a further increase in surface area contact between the cable and gripping element, further increasing friction. Also depicted within the figures is a cavity 7 provided in some implementations towards a first end of the body 1 which is sized optimally to receive a cable connector. Said cable connector will vary in size and shape depending on the cable used within the system, and may in some implementations constitute a known and widely used connector, such as fibre optic LC or SC connectors, RJ45 data connectors, or other cable connectors. The cavity 7 in the implementation depicted in the enclosed figures is sized and shaped to receive an LC fibre optic connector (not shown within the figures), and contains a number of ribs 8 projecting from the internal walls of the cavity 7 for increased retention of this connector body. Said ribs 8 allow the connector to be snugly fitted into the cavity 7, without the imparting of axial load to the connector. Further improvements to the retention of both cable and connector body can be provided by the use of a material with an increased coefficient of friction such as a TPU rubber. This material can be used throughout the gripping part, or used selectively as a coating on specified portions of the body such as the slots 2, channels 3, and the ribs 5 and 8 and radii 6 of the gripping element. Further advantages to the use of a material such as a TPU rubber can be found in such implementations as depicted in figures 1 to 8 where the gripping element is intended for use as a pulling element, both as the increased friction provided by the material can assist the pulling of the element from an external body such as an external pulling sock, and as the properties of a material such as a TPU rubber may impart some flexibility into the part, and facilitate the pulling of cables over such items as pulleys or capstans. By allowing the body of the gripping element to deform in conjunction with the installed cable element, the cable can be protected from any point loads potentially imparted by a harder material when an angular force is applied. This aspect can be further improved by the addition of grooves 9 formed into the surface of the grip body axially from a plane tangent to the outer surface of the body, projecting in towards the central axis of the body. Such grooves serve to increase the allowable bend of the body, and their position relative to the cable slots 2 can be tuned to relieve point stresses on the cable 10 as the gripping element body 1 deforms. Figures 3, 4, 5 and 6 successively show top, first side, bottom and second side views of an example embodiment of the invention, shown at 90 degree increments in viewing angle. These figures, viewed in sequence depictthe serpentine cable routingformed by the slots 2 and channels 3, and further details including ribs 5, radii 6, connector cavity 7 and cavity ribs 8. Figure 7 depicts a system for gripping cable, according to some implementations, and indicates a potential cable lacing pattern with cable 10 routed through slots 1 and channels 3 in order to provide an optimised gripping system. Figure 8 depicts the same system, with the cable 10 fully installed and tensioned. Tension is provided to the cable through the means of increased contact between the cable jacket and various points of contact on the grip, essentially acting as multiple capstans to introduce increased friction without the risk of cable damage. In applications where the cable grip element is intended for semi-permanent or permanent use in an outdoor environment, the cable grip element may be formed of a material with resistance to degradation through environmental conditions. Key amongst these is resistance to UV light, and as such the element may be formed entirely or in part from a UV resistant polymer or similar UV resistant material. The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiment described above. On the contrary, many modifications and variations are possible within the scope of the claims. Further additional implementations could include alternative external shapes of the gripping element to suit alternative applications, while maintaining the serpentine cable routingas described in the above. While embodiments comprising a nominally cylindrical gripping element designed for cable pulling are the focus of the above description it is envisaged that some embodiments may only feature the serpentine cable routing that is described in the claims. For example, the gripping element may take the form of a panel mounted fixture, while maintaining the serpentine cable routing as described in the claims, as a means of retaining cable at a panel ingress location. Other potential applications for the described invention are in use for semi-permanent and permanent cable tensioning applications, including but not limited to the fixing of fibre optic drop cables to buildings and access poles. Similarly, while the focus of the above detailed description is on a fibre optic cable with an installed connector, it is envisaged that other embodiments may be configured to accept cable of alternative constructions and a range of jacket diameters, with the gripping element sized as to fit the intended cable.

Claims

1. A system for retaining a cable, comprising:a cable, having a circumference and a jacket;a grip, engaging with the jacket of the cable;the grip having a longitudinal axis, positioned along the longitudinal axis of the cable, and a depth and width forming a main body;the grip main body having a plurality of slots arranged along its longitudinal axis, and positioned such thatthe cable can be wound in a serpentine manner through said slots, such thatthe surface area of the grip in contact with the cable jacket is increased.

2. The system of claim 1, wherein the grip, or certain elements within it, are formed of a flexible material.

3. The system of claim 1, the grip comprising a plurality of grooves formed into the outer surface of the grip body, and positioned in opposition to the cable slots.

4. The system of claim 1, wherein the grip is nominally cylindrical.

5. The system of claim 1, the cable comprising a connector on the proximal end, and the grip comprising a cavity shaped and sized to accommodate said connector, without inducingan axial load upon it.

6. The system of claim 1, wherein the grip is formed of a material which maintains stable material properties with prolonged exposure to UV light.

Images