Fiberoptic furcation device with crimp

[0001] The present invention relates to devices and methods for breaking out, or furcating, optical fibers from within a fiberoptic cable into a larger cable, such as a protective upjacket.

[0002] Fiberoptic cables often contain one or more individual optical fibers within a jacket. It is desirable to remove the jacket to expose the individual optical fibers, such as for connectorization in order to connect each fiber to telecommunications equipment. Breaking out or furcating of bare optical fibers from within one fiberoptic cable into a larger cable, the upjacket, is known. Typically, the bare optical fibers are inserted into the upjacket before connectorization to provide protection of the optical fiber, including during connectorization. Typically, the upjacket includes an aramid yarn strength member, or other strength member to transfer any loads to the optical connector terminated onto the upjacket, or to the jacket of the fiberoptic cable containing the optical fibers, instead of to the optical fiber.

[0003] There is a need for improved devices and methods for breaking out or furcating optical fibers.

[0004] A cable furcation device and method are provided for upjacketing of optical fibers extending from a fiberoptic cable. The cable furcation device includes a housing for receiving the fiberoptic cable on one end. An opposite end receives each upjacket. A crimp is provided for crimping the strength members of the upjackets to the furcation housing. Preferably, the housing includes a projecting tube for receiving inside the tube each individual optical fiber, and a protective buffer tubing of the upjacket. The projecting tube also receives the outer tube of the upjacket.

[0005] A cable furcation device comprises a body having a front end and an opposite rear end, the body defining a longitudinal axis therebetween. The front end includes a first tube having a first outer diameter, and a first inner diameter. The front end includes a crimp surface having a second outer diameter larger than the first outer diameter, with the crimp surface located between the first tube and the rear end. The rear end has a third outer diameter larger than the second outer diameter and an inner bore has first and second inner bore portions with first and second bore diameters respectively, with the second inner bore diameter being smaller than the first inner bore diameter, the second inner bore portion located between the first bore portion and the front end. The inner bore extends from the rear end and terminates at an end wall. The body defines a first passage from the first tube to the inner bore. The first inner diameter of the first tube and the first and second inner bore diameters are sized for receiving an optical fiber. The first inner bore diameter is further sized for receiving a jacket of a cable surrounding the optical fiber. The crimp surface is sized for receiving a crimp ring to crimp a strength member of an upjacket. The first outer diameter of the first tube is sized to be received inside a tubular member of the upjacket. The first inner diameter of the first tube and the first and second inner bore diameters are sized for receiving an inner tubular member of the upjacket around optical fiber.

[0006] Preferably, the cable furcation device includes a second tube, having the same first outer and inner diameters as the first tube, with the first and second tubes extending parallel to one another.

[0007] A cable breakout assembly is provided comprising a cable furcation device which joins a cable to an upjacket. A strength member is crimped to the device. The device is joined to the cable and the upjacket through a heat shrunk tubing.

[0008] A method of breaking out optical fibers comprising the steps of: positioning a furcation device over the optical fibers extending from within a jacket of a cable; positioning each optical fiber in a protective inner tube of an individual upjacket; passing the protective inner tube of each of the upjackets into an interior of the furcation device; inserting an end of an outer protective tube of each of the upjackets over a tube of the furcation device; crimping a strength member of each of the upjackets to the furcation device; inserting an end of the jacket of the cable into the furcation device; and heat shrinking a tubing around the furcation device, an exposed portion of the jacket of the cable adjacent to the furcation device, and an exposed portion of the upjacket adjacent to the furcation device.

[0025] Referring now to FIGS. 1-7, a cable furcation device or connector 10 is provided for breaking out or furcating individual optical fibers 12, 14 from a first cable 16. Cable 16 may also be known as a drop cable. Cable 16 may include an outerjacket 18, and an innerjacket 20. A strength member, such as a wire (not shown) may also be provided with cable 16.

[0026] When breaking out the individual optical fibers 12, 14, ends of outer jacket 18 and innerjacket 20 are removed exposing a length of optical fibers 12, 14. Outer jacket 18 is terminated at terminal end 22 and inner jacket 20 is terminated at terminal end 24. Typically, optical fibers 12, 14 are connectorized at an opposite end, such as with any of well known connectors, such as SC, FC, ST, or other connectors as desired. An SC connector 100 is shown in FIG. 7. Connector 100 mates with an appropriate adapter to connect the optical fiber 12, 14 to a further cable or to equipment.

[0027] Typically, optical fibers 12, 14 are quite fragile, and susceptible to damage unless otherwise protected in the regions outside of outer and innerjackets 18, 20. An upjacket 30 is provided to protect the individual fibers 12, 14 extending past terminal ends 22, 24. Typically, one upjacket 30 is provided for each optical fiber 12, 14. In the illustrated embodiment of device 10, two optical fibers 12, 14 are shown. Other embodiments include a single optical fiber, or more than two optical fibers such as 4, 6, 8, 12 or any other number of fibers as desired.

[0028] Upjacket 30 includes an inner tube, or buffer tube, 32 for receiving one of the optical fibers 12, 14. Positioned around inner tube 32 is a strength member 34, such as strands of aramid fiber. Such strength member 34 protects the optical fibers 12, 14 from damage, such as during tensile loading. Positioned around inner tube 32 and strength member 34 is an outer tube 36. Device 10 is used to allow breaking out of optical fibers 12, 14 from cable 16 into the individual upjackets 30. During use, the strength member 34 is crimped or otherwise mechanically joined to device 10, and an outer heat shrunk tubing or other mechanical attachment surrounds device 10, and the exposed ends of upjackets 30, and cable 16 to join the elements together. Loads are transferred between connector 100 and cable 16, though strength members 34 and device 10, instead of through the optical fibers 12, 14.

[0029] Device 10 includes a housing or body 40 having a front end 42 and an opposite rear end 44. Body 40 defines a longitudinal axis 46 extending between front and rear ends 42, 44. In one preferred embodiment, body 40 is made from metal.

[0030] Rear end 44 defines an inner bore 48 for receiving cable 16. Inner bore 48 includes a first inner bore portion or passage 50 having a first inner bore diameter 52 and a second inner bore portion or passage 54 having a second inner bore diameter 56 smaller than first inner bore diameter 52. Inner bore 48 terminates at end wall 60. Inner bore 48 further communicates with first passage 62 and second passage 64. First and second passages 62, 64 communicate with first and second tubes 66, 68.

[0031] Front end 42 connects to the upjackets 30. In particular, each of first and second tubes 66, 68 includes a first tube outer diameter 70 and a first tube inner diameter 72. First tube inner diameter 72 is sized to receive inner tube 32 of upjacket 30. Inner tube 32 further receives one of optical fibers 12, 14 within inner tube 32. Tubes 66, 68 are offset from axis 46. Other spacings are possible, but a symmetrical spacing is preferred. As different numbers of tubes are provided, the spacings will vary in order to accommodate different numbers of optical fibers used with device 10.

[0032] Strength member 34 of upjacket 30 is positioned adjacent to a crimp surface 76 of body 40 positioned between first and second tubes 66, 68 and rear end 44. Crimp surface 76 defines a second outer diameter 78. A crimp ring 80 cooperates with crimp surface 76 to crimp to strength member 34. A plurality of barbs 82 on crimp surface 76 further enhance the crimping of strength member 34 to crimp surface 76.

[0033] Outer tube 36 of upjacket 30 is positioned around first tube outer diameter 70 of the respective first and second tubes 66, 68. If desired, a further crimp can be included to crimp outer tube 36 to the respective first and second tubes 66, 68.

[0034] Body 40 further includes a third outer diameter 86 which is larger than second outer diameter 78. In the preferred embodiment, second outer diameter 78 is larger than first tube outer diameter 70.

[0035] In the preferred embodiment, body 40 includes cut outs 90, 92. Cut outs 90, 92 allow access for a user of device 10 to inner bore 48. Also, cut outs 90, 92 can be used to reach in with a tool (tweezers) to pull inner tubes 32 toward inner jacket 20. In some instances, it may be desirable to insert inner tubes 32 into inner jacket 20.

[0036] Referring now to FIGS. 8 through 14 in addition to FIGS. 1 through 7, a preferred method of assembly is shown. In FIG. 8, upjackets 30 are shown where two outer tubes 36 are positioned over first and second tubes 66, 68. Strength member 34, comprised of a plurality of fibers or strands, of each jacket 30 is shown extending from outer tubes 36, prior to crimping. Inner tubes 32 are shown extending through inner bore 48 and exiting device 10 at rear end 44.

[0037] FIG. 9 shows strength members 34 being crimped with a crimp tool 98 to body 40. FIG. 10 shows the resulting crimp ring 80 crimped into position.

[0038] FIG. 11 shows strength members 34 passing into cut outs 90, 92 into inner bore 48.

[0039] FIG. 12 shows cable 16 with terminal ends 22, 24 of outer and inner jackets 18, 20 inserted into inner bore 48.

[0040] FIG. 13 shows a heat shrinkable tube 96 prior to heat shrinking around device 10, cable 16, and upjackets 30. Tube 96 is any of a known heat shrink device, such as a polyolefin tube with heat activated adhesive inside.

[0041] FIG. 14 shows tube 96 after the heat shrinking process is completed.

[0042] Device 10 of the present invention reduces the risk of a fiber breaking within the connector of an upjacket when a tensile load is applied. By crimping strength member 34 to body 40, slack in strength member 34 is avoided. With prior art techniques, any slack in strength member 34 which was not accounting for, could lead to fiber breakage since any tensile loading would be applied to the fiber, until any slack in strength member 34 was taken up. In the present invention, the strength member 34 is crimped adjacent to the location it exits outer tube 36 of upjacket 30. Device 10 is then mechanically attached to cable 16, and to outer tubes 36, such as with a heat shrunk tubing. IN FIGS. 15 and 16 strength members 34 of the prior art were attached only at the exposed ends 101 which extended past sleeve 102.

[0043] Strength members 34 which extend past crimp ring 80 in the present invention are believed to further assist with attachment of upjacket 30 and device 10 to cable 16. It is to be appreciated that the extending strength members 34 past crimp ring 80 is optional.

[0044] The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.