CA2200283C - Fiber-optic cable having enhanced crushing strength - Google Patents
Fiber-optic cable having enhanced crushing strength Download PDFInfo
- Publication number
- CA2200283C CA2200283C CA002200283A CA2200283A CA2200283C CA 2200283 C CA2200283 C CA 2200283C CA 002200283 A CA002200283 A CA 002200283A CA 2200283 A CA2200283 A CA 2200283A CA 2200283 C CA2200283 C CA 2200283C
- Authority
- CA
- Canada
- Prior art keywords
- cable
- wall
- optical
- diametrically opposed
- ribs
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000013307 optical fiber Substances 0.000 claims abstract description 6
- 230000003287 optical effect Effects 0.000 claims description 10
- 230000002787 reinforcement Effects 0.000 claims description 7
- 239000004033 plastic Substances 0.000 claims description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 239000004760 aramid Substances 0.000 description 1
- 229920003235 aromatic polyamide Polymers 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000008092 positive effect Effects 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 230000008719 thickening Effects 0.000 description 1
- 230000003313 weakening effect Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
- G02B6/4401—Optical cables
- G02B6/4429—Means specially adapted for strengthening or protecting the cables
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
- G02B6/4401—Optical cables
- G02B6/4429—Means specially adapted for strengthening or protecting the cables
- G02B6/443—Protective covering
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
- G02B6/4401—Optical cables
- G02B6/4429—Means specially adapted for strengthening or protecting the cables
- G02B6/443—Protective covering
- G02B6/4432—Protective covering with fibre reinforcements
- G02B6/4433—Double reinforcement laying in straight line with optical transmission element
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Insulated Conductors (AREA)
- Communication Cables (AREA)
Abstract
The cable (1) comprises a plurality of optical fibre micro-modules (2) grouped together inside an external sheath (4). The external portion of the latter has four bosses (5) moulded integral therewith and which extend along the entire length of the cable and form, along the generating lines of the cable, four diametrically opposed ribs. These bosses, by creating a special arrangement for application to the cable of compressive forces, produce an improvement in crushing strength.
Application to fibre-optic cables.
Application to fibre-optic cables.
Description
The invention relates to fibre-optic cables and, more specifically, to cables the structure and shape of which are such that their crushing strength is quite markedly improved, in particular by comparison with cables having a circular cross-section of a conventional design.
Fibre-optic cables are well known and have developed rapidly over the last few years, particularly in the field of telecommunications, owing to the considerable transmission potential of optical fibres of very small dimensions. These fibres nonetheless have to be mechanically protected, by the structure of the cable, from the stresses associated with the radial forces applied to the cable, such as crushing, impact, etc. Cable structures enclosing these fibres have thus been developed to protect them mechanically according to the environments in which they are located.
Known fibre-optic cables have a variety of structures. There is known, for instance, a type of tube-equipped cable comprising a central reinforcement, surrounded by a plurality of helically or pseudo-helically wound tubes enclosing a bundle of optical fibres capable of moving within the tubes. This ability of the fibres to move within the tubes compensates for the variations in the length of the cable due to thermal or tensile stresses.
This structure is, however, too voluminous by comparison with the real space taken up by the fibres it contains and it is unsuitable, for example, for distribution cables in an urban network in which the object is to obtain an optimal ratio of the number of fibres to the diameter of the cable.
It is thus preferred to use cables with a low expansion coefficient, wherein the fibres are, for example, disposed in bundles (round or flat ribbon micro-modules), la the bundles being disposed practically without clearance between them in the inner cylindrical cavity of the cable.
A good ratio of the number of fibres to the outside diameter of the cable can thus be obtained. The cross-section of the cables is circular and the sheaths of the cables may possibly incorporate metallic or non-metallic reinforcements A, such as shown in figure 2, which may be two in number, and which extend along two diametrically opposed generating lines. By reason of the very small radial I Iw~a.,~ a n"~ .i IN a ~ I
Fibre-optic cables are well known and have developed rapidly over the last few years, particularly in the field of telecommunications, owing to the considerable transmission potential of optical fibres of very small dimensions. These fibres nonetheless have to be mechanically protected, by the structure of the cable, from the stresses associated with the radial forces applied to the cable, such as crushing, impact, etc. Cable structures enclosing these fibres have thus been developed to protect them mechanically according to the environments in which they are located.
Known fibre-optic cables have a variety of structures. There is known, for instance, a type of tube-equipped cable comprising a central reinforcement, surrounded by a plurality of helically or pseudo-helically wound tubes enclosing a bundle of optical fibres capable of moving within the tubes. This ability of the fibres to move within the tubes compensates for the variations in the length of the cable due to thermal or tensile stresses.
This structure is, however, too voluminous by comparison with the real space taken up by the fibres it contains and it is unsuitable, for example, for distribution cables in an urban network in which the object is to obtain an optimal ratio of the number of fibres to the diameter of the cable.
It is thus preferred to use cables with a low expansion coefficient, wherein the fibres are, for example, disposed in bundles (round or flat ribbon micro-modules), la the bundles being disposed practically without clearance between them in the inner cylindrical cavity of the cable.
A good ratio of the number of fibres to the outside diameter of the cable can thus be obtained. The cross-section of the cables is circular and the sheaths of the cables may possibly incorporate metallic or non-metallic reinforcements A, such as shown in figure 2, which may be two in number, and which extend along two diametrically opposed generating lines. By reason of the very small radial I Iw~a.,~ a n"~ .i IN a ~ I
clearance that remains between the fibres and the inner cavity of the cable, when crushing forces are applied or in the event of impacts, the deformation of the inner cavity containing the fibres that is induced exerts inadmissible compressive stress on the said fibres, leading to additional weakening, or even failure.
The sheath therefore has to be reinforced to limit its deformation as far as possible when the aforementioned stresses are applied.
The solutions adopted to reduce these deformations, such as the use of metallic reinforcements, materials having a high modulus of elasticity, wall thickening, etc., have drawbacks, however.
The Applicant has thus applied itself to finding a solution to this problem to enable an optical cable, whatever the environment in which it is located, to possess increased resistance to the stresses to which it might be subjected and particularly capable of withstanding any localised crushing or impacts that it might be exposed to, for instance at the time of cable laying operations.
According to the invention there is provided an optical fiber cable having improved crushing strength, said cable comprising: a tubular plastic sheath having a length and having a wall of a predetermined inner diameter which encircles a plurality of optical fibers: said wall having a radial thickness at four portions of the wall spaced substantially equally from each other in the circumferential direction of the wall which is greater than the thickness of the wall intermediate said portions to provide two pairs of ribs extending outwardly from said wall and lengthwise of I ~~,NUUr~la~~llq~rn ~~xi~ . ..
' 77909-31 2a said sheath, one pair of said ribs being diametrically opposed with respect to each other and the other pair of said ribs being diametrically opposed with respect to each other.
Other characteristics and advantages of the invention will emerge from the following description of a non-limitative example of a form of embodiment, with reference to the figures, which represent cross-sectional views of optical cables. Figures 1 and 3 are cross-sectional views of the cable according to the invention.
Figure 2 illustrates the application of the stresses to a circular cable of conventional design. Figure 4 diagrammatically represents an alternative form of embodiment.
The sheath therefore has to be reinforced to limit its deformation as far as possible when the aforementioned stresses are applied.
The solutions adopted to reduce these deformations, such as the use of metallic reinforcements, materials having a high modulus of elasticity, wall thickening, etc., have drawbacks, however.
The Applicant has thus applied itself to finding a solution to this problem to enable an optical cable, whatever the environment in which it is located, to possess increased resistance to the stresses to which it might be subjected and particularly capable of withstanding any localised crushing or impacts that it might be exposed to, for instance at the time of cable laying operations.
According to the invention there is provided an optical fiber cable having improved crushing strength, said cable comprising: a tubular plastic sheath having a length and having a wall of a predetermined inner diameter which encircles a plurality of optical fibers: said wall having a radial thickness at four portions of the wall spaced substantially equally from each other in the circumferential direction of the wall which is greater than the thickness of the wall intermediate said portions to provide two pairs of ribs extending outwardly from said wall and lengthwise of I ~~,NUUr~la~~llq~rn ~~xi~ . ..
' 77909-31 2a said sheath, one pair of said ribs being diametrically opposed with respect to each other and the other pair of said ribs being diametrically opposed with respect to each other.
Other characteristics and advantages of the invention will emerge from the following description of a non-limitative example of a form of embodiment, with reference to the figures, which represent cross-sectional views of optical cables. Figures 1 and 3 are cross-sectional views of the cable according to the invention.
Figure 2 illustrates the application of the stresses to a circular cable of conventional design. Figure 4 diagrammatically represents an alternative form of embodiment.
Cable 1, shown in figure 1 lying on a surface 7, comprises in its centre a group of eight optical fibre micro-modules 2. The micro-modules are covered by an outer sheath 4.
The outer portion of sheath 4 is not circular but has, along diametrically opposed generating lines, four bosses 5 which extend over the entire length of the cable.
The bosses, which are integrally moulded into the body of the sheath, form, as it were, external ribs which project in relation to a tangent to the circular portion of sheath, and which have a rounded external profile. If necessary, traction reinforcements 6 can be provided inside one or more of these bosses, the reinforcements being metallic or non-metallic, for example made of aramid resin, and being embedded in the sheath in the area of the bosses when the cable is extruded. Alternatively, traction elements or copper wires can also be housed in the bosses. These elements can serve as leads or limit the minimum radius of curvature of the cable.
This arrangement thus makes it possible to avoid making the sheath 4, one of the functions of which is to withstand crushing, very thick. Thanks to the bosses, it is thus possible to reduce the thickness of the sheath, which reduces the weight of the cable by a corresponding amount and lowers the thermal expansion coefficient.
When a compressive stress, represented in figure 1 by the presence of a plate 3 pushed by a force F, is applied to the cable, the stable position of the cable is as shown in figure 1. If the stress is applied thereto along another generating line, it will automatically tip over to resume the position represented.
The outer portion of sheath 4 is not circular but has, along diametrically opposed generating lines, four bosses 5 which extend over the entire length of the cable.
The bosses, which are integrally moulded into the body of the sheath, form, as it were, external ribs which project in relation to a tangent to the circular portion of sheath, and which have a rounded external profile. If necessary, traction reinforcements 6 can be provided inside one or more of these bosses, the reinforcements being metallic or non-metallic, for example made of aramid resin, and being embedded in the sheath in the area of the bosses when the cable is extruded. Alternatively, traction elements or copper wires can also be housed in the bosses. These elements can serve as leads or limit the minimum radius of curvature of the cable.
This arrangement thus makes it possible to avoid making the sheath 4, one of the functions of which is to withstand crushing, very thick. Thanks to the bosses, it is thus possible to reduce the thickness of the sheath, which reduces the weight of the cable by a corresponding amount and lowers the thermal expansion coefficient.
When a compressive stress, represented in figure 1 by the presence of a plate 3 pushed by a force F, is applied to the cable, the stable position of the cable is as shown in figure 1. If the stress is applied thereto along another generating line, it will automatically tip over to resume the position represented.
For the same sheath thickness, the case in which the stress is applied illustrated in figure 3 is clearly more favourable, among other positive effects, than the case shown in figure 2, as it produces a smaller bending moment at the inferior point. The result is, for the same stress, a deflection under load that is smaller in the case shown in figure 3 than in that of figure 2.
According to the same principle, the external shape could be practically square, as illustrated in figure 4.
For maximum efficiency, distance X must be positive, or at the very least nil, as shown in figure 1.
According to the same principle, the external shape could be practically square, as illustrated in figure 4.
For maximum efficiency, distance X must be positive, or at the very least nil, as shown in figure 1.
Claims (5)
1. An optical fiber cable having improved crushing strength, said cable comprising:
a tubular plastic sheath having a length and having a wall of a predetermined inner diameter which encircles a plurality of optical fibers;
said wall having a radial thickness at four portions of the wall spaced substantially equally from each other in the circumferential direction of the wall which is greater than the thickness of the wall intermediate said portions to provide two pairs of ribs extending outwardly from said wall and lengthwise of said sheath, one pair of said ribs being diametrically opposed with respect to each other and the other pair of said ribs being diametrically opposed with respect to each other.
a tubular plastic sheath having a length and having a wall of a predetermined inner diameter which encircles a plurality of optical fibers;
said wall having a radial thickness at four portions of the wall spaced substantially equally from each other in the circumferential direction of the wall which is greater than the thickness of the wall intermediate said portions to provide two pairs of ribs extending outwardly from said wall and lengthwise of said sheath, one pair of said ribs being diametrically opposed with respect to each other and the other pair of said ribs being diametrically opposed with respect to each other.
2. Optical cable according to claim 1, characterized in that two of the diametrically opposed ribs enclose metallic or non-metallic reinforcements.
3. Optical cable according to claim 1, characterized in that the optical fibres are grouped together in micro-modules.
4. Optical cable according to claim 1, characterized in that the optical fibres are grouped together in ribbons.
5. Optical cable according to claim 1, characterized in that at least two of the diametrically opposed ribs enclose metallic or non-metallic reinforcements which can serve as leads or limit the minimum radius of curvature of the cable.
Priority Applications (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR9602542A FR2745642B1 (en) | 1996-02-29 | 1996-02-29 | OPTICAL FIBER CABLE HAVING INCREASED CRUSHING RESISTANCE |
| DE69737577T DE69737577T2 (en) | 1996-02-29 | 1997-02-24 | Fiber optic cable with increased crush resistance |
| ES97400396T ES2285724T3 (en) | 1996-02-29 | 1997-02-24 | OPTICAL FIBER CABLE WITH AN INCREASED CRUSHING RESISTANCE. |
| EP97400396A EP0793127B1 (en) | 1996-02-29 | 1997-02-24 | Fibre optical cable with enhanced crush-resistance |
| CA002200283A CA2200283C (en) | 1996-02-29 | 1997-03-18 | Fiber-optic cable having enhanced crushing strength |
| AU16440/97A AU729539B2 (en) | 1996-02-29 | 1997-03-20 | Fibre-optic cable having enhanced crushing strength |
| NZ314463A NZ314463A (en) | 1996-02-29 | 1997-03-21 | Optical fibre cable with crushing strength enhancing externally ribbed sheath |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR9602542A FR2745642B1 (en) | 1996-02-29 | 1996-02-29 | OPTICAL FIBER CABLE HAVING INCREASED CRUSHING RESISTANCE |
| CA002200283A CA2200283C (en) | 1996-02-29 | 1997-03-18 | Fiber-optic cable having enhanced crushing strength |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2200283A1 CA2200283A1 (en) | 1998-09-18 |
| CA2200283C true CA2200283C (en) | 2006-07-25 |
Family
ID=25679137
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002200283A Expired - Fee Related CA2200283C (en) | 1996-02-29 | 1997-03-18 | Fiber-optic cable having enhanced crushing strength |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0793127B1 (en) |
| AU (1) | AU729539B2 (en) |
| CA (1) | CA2200283C (en) |
| DE (1) | DE69737577T2 (en) |
| ES (1) | ES2285724T3 (en) |
| FR (1) | FR2745642B1 (en) |
| NZ (1) | NZ314463A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10035268A1 (en) * | 2000-07-20 | 2002-01-31 | Scc Special Comm Cables Gmbh | Optical cable for sewer conduit or pipe system has reinforcement elements on one half of cable sheath surrounding core element containing optical transmission elements |
| AU2002358588A1 (en) | 2002-12-03 | 2004-06-23 | Pirelli And C. S.P.A. | High count telecommunication optical cable with controlled fiber length, method and apparatus for manufacturing the same |
| CN110858019A (en) * | 2018-08-26 | 2020-03-03 | 北京亨通斯博通讯科技有限公司 | Reinforced flat optical cable |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2260806B1 (en) * | 1974-02-13 | 1976-10-08 | Fort Francois | |
| US3941157A (en) * | 1974-07-24 | 1976-03-02 | Barnett Louis H | High strength multiple passageway plastic conduit |
| US4761053A (en) * | 1985-08-28 | 1988-08-02 | American Telephone And Telegraph Company, At&T Bell Laboratories | Communications transmission media |
| US5031997A (en) * | 1990-03-28 | 1991-07-16 | Hughes Aircraft Company | Open breech hot launched fiber optic payout system |
| FI91333C (en) * | 1990-07-19 | 1994-06-10 | Nokia Kaapeli Oy | Cable |
| US5155304A (en) * | 1990-07-25 | 1992-10-13 | At&T Bell Laboratories | Aerial service wire |
-
1996
- 1996-02-29 FR FR9602542A patent/FR2745642B1/en not_active Expired - Lifetime
-
1997
- 1997-02-24 ES ES97400396T patent/ES2285724T3/en not_active Expired - Lifetime
- 1997-02-24 DE DE69737577T patent/DE69737577T2/en not_active Expired - Lifetime
- 1997-02-24 EP EP97400396A patent/EP0793127B1/en not_active Expired - Lifetime
- 1997-03-18 CA CA002200283A patent/CA2200283C/en not_active Expired - Fee Related
- 1997-03-20 AU AU16440/97A patent/AU729539B2/en not_active Ceased
- 1997-03-21 NZ NZ314463A patent/NZ314463A/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| NZ314463A (en) | 1998-01-26 |
| ES2285724T3 (en) | 2007-11-16 |
| FR2745642B1 (en) | 1998-08-14 |
| CA2200283A1 (en) | 1998-09-18 |
| DE69737577D1 (en) | 2007-05-24 |
| AU1644097A (en) | 1998-09-24 |
| DE69737577T2 (en) | 2008-01-03 |
| EP0793127B1 (en) | 2007-04-11 |
| FR2745642A1 (en) | 1997-09-05 |
| AU729539B2 (en) | 2001-02-01 |
| EP0793127A1 (en) | 1997-09-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |
Effective date: 20170320 |