Fiber optic breakout transition assembly incorporating epoxy plug and cable strain relief

[0001] This application is a National Stage Application of PCT/US2017/056053, filed on Oct. 11, 2017, which claims the benefit of U.S. Patent Application Ser. No. 62/407,746, filed on Oct. 13, 2016, the disclosures of which are incorporated herein by reference in their entireties. To the extent appropriate, a claim of priority is made to each of the above disclosed applications.

[0002] The present disclosure relates generally to telecommunications equipment. More particularly, the present disclosure relates to fiber optic cabling and the method of making thereof.

[0003] Telecommunications equipment containing optical fibers is known. Fiber optic cables that carry a plurality of optical fibers over distances to connect to equipment are also known. In fiber optic networking, it is sometimes advantageous to bundle multiple optical fibers together into a single cable. This is often done to save space since the diameter of the actual fiber (the core and the cladding) is typically considerably smaller than the shielding (buffer and jacket) used to protect said fiber. As a result, it is possible to bundle together relatively large numbers of fibers (e.g., 12, 24, 36, 48, etc.), shielding the entire bundle and avoiding shielding each fiber individually. Such multi-fiber cables can take on many forms, including rounded cables and fiber ribbons.

[0004] Sometimes a multi-fiber bundle may carry signals directed to or from multiple pieces of equipment. Consequently, there is a need to breakout (or “furcate”) individual or a series of individual optical fibers from a multi-fiber cable so that those fibers can be directed to the necessary equipment. Furcation tubing is typically used in such a fiber breakout for transitioning from a single cable with multiple fibers into individual cables with one or more fibers in each furcation cable or tubing.

[0005] One example of achieving such a breakout has been through a cable transition structure. In using such cable transitions, it is desirable to take into account the maximum bend radius of the fibers, the stress which the fibers may undergo as a result of the breakout, and how the environmental conditions may impact the fiber's performance. For the above reasons, fiber optic communication continues to need improved breakout harness designs.

[0006] In one aspect, the present disclosure relates to a fiber optic cable transition assembly for transitioning a plurality of optical fibers from a multi-fiber cable to a plurality of furcation tubes. The fiber optic transition assembly has a housing with a front opening and an internal passageway that is defined by a wall and a narrow region. The housing is adapted to receive epoxy adhesive. The fiber optic transition assembly has a boot that is positioned at least partially inside the housing for receiving the multi-fiber cable to provide strain relief to the plurality of optical fibers extending therethrough. The fiber optic transition assembly has a plug supported by the boot and retained by the housing to prevent epoxy adhesive from entering the multi-fiber cable.

[0007] Another aspect of the present disclosure relates to a cable transition assembly for transitioning a plurality of optical fibers from a multi-fiber cable to a plurality of furcation tubes. The fiber optic transition assembly has a cylindrical housing with an internal passageway. The fiber optic transition assembly also has a first boot that is positioned at least partially inside the housing for supporting the multi-fiber cable. The first boot supports a first plug that is secured with respect to said cylindrical housing internal passageway. The fiber optic transition assembly also has a second boot that is positioned at least partially inside the housing and supports the plurality of furcation tubes. The second boot supports a second plug that is secured with respect to said cylindrical housing internal passageway.

[0008] A further aspect of the present disclosure relates to a fiber optic cable transition assembly for transitioning a plurality of optical fibers from a multi-fiber cable to a plurality of furcation tubes. The fiber optic transition assembly has a cylindrical housing with an internal passageway defined by a wall. The housing includes an epoxy injection port. The fiber optic transition assembly has a first boot that is positioned at least partially inside the housing and supports the multi-fiber cable to provide strain relief to the plurality of optical fibers extending therethrough. The fiber optic transition assembly has a first plug that is supported by the first boot and forms a seal within the housing internal passageway wall. The fiber optic transition assembly has a second boot that is positioned at least partially inside the housing and supports the plurality of furcation tubes and provides strain relief to the plurality of optical fibers extending therethrough. The fiber optic transition assembly has a second plug that is supported by the second boot and forms a seal within the housing internal passageway wall. The fiber optic transition assembly has a volume of hardened epoxy that is contained within the housing internal passageway between the first plug and the second plug.

[0022] FIG. 1 illustrates an example fiber optic cable transition assembly 10 for transitioning a plurality of optical fibers 24 (FIGS. 2, 8, 13) from a multi-fiber cable 20 to a plurality of furcation tubes 22. The illustrated fiber optic transition assembly 10 includes a housing 40, a rear strain-relief boot 30 and a front strain-relief boot 50.

[0023] FIG. 2 illustrates a cross-sectional illustration of the multi-fiber cable 20 inserted into the fiber optic transition assembly 10 through the rear strain-relief boot 30. The illustrated rear strain-relief boot 30 supports a plug 60 that is received within the housing 40. As illustrated, the multi-fiber cable 20 is inserted within, and is secured by, the plug 60 in the rear strain-relief boot 30. The multi-fiber cable 20 can have elastomeric properties and provide flexibility to the optical fibers 24 and strength members 26 (FIGS. 8, 13) therein. The outer jacket of the multi-fiber cable 20 is stripped to reveal the optical fibers 24, which can be coated with a polymer such as polyimide, and any strength members 26 such as aramid yarn extending within. The illustrated front strain-relief boot 50 supports a plug 70 that is received within the housing 40. As illustrated, the plurality of furcation tubes 22 are inserted within, and are secured by, the plug 70 in the front strain-relief boot 50. The optical fibers 24 and strength members 26 are inserted into the plurality of furcation tubes 22, which exit the fiber optic cable transition assembly 10 through the front strain-relief boot 50. The furcation tubes 22 can have elastomeric properties and provide flexibility to the optical fibers 24 and strength members 26 therein.

[0024] FIG. 3 illustrates a cross-sectional view of the example housing 40. The illustrated housing 40 is preferably made of a rigid structure such as plastic. As illustrated, the housing 40 is defined by a rear end 42 and a front end 44. As illustrated in FIG. 1, the housing 40 can be defined by a cylindrical geometry having a circumferential outer wall extending between the rear end 42 and the front end 44. Preferably, the circumferential outer wall of the housing 40 is defined by a diameter that allows the housing and transition assembly 10 to be pulled, pushed and/or blown through cabling conduit or existing and/or fabricated structural holes supporting installation of fiber cables.

[0025] An illustrated internal passageway extends within the housing 40 between the rear end 42 and the front end 44. This internal passageway is defined by a rear receiver 41 (or cavity), a narrow channel 43 and a front receiver 44 (or cavity) and allows for the optical fibers 24 (FIG. 2) to pass therethrough from the multi-fiber cable 20 (FIGS. 1 & 2) to the broken-out furcation tubes 22 (FIG. 2). The rear receiver 41 can be defined by a consistent clearance, for example a consistent diameter, extending from an opening at the rear end 42 to the narrow channel 43. The rear receiver 41 can alternatively be defined by a clearance, for example a diameter, that narrows or tapers from the rear end 42 to the narrow channel 43 This clearance of the rear receiver 41 can define any diameter or geometry that allows the rear strain-relief boot 30 to be inserted therein. The rear receiver 41 can also define a transition surface 47, such as a chamfer, from the consistent clearance to the narrow channel 43, for example if the clearance of the rear receiver is greater than a clearance of the narrow channel.

[0026] The narrow channel 43 illustrates a narrower clearance, for example diameter, than the rear receiver 41 and the front receiver 45. This clearance of the narrow channel 43 can define any diameter or geometry that allows the plug 60 to be inserted therein. The clearance of the narrow channel 43 can be consistent between the rear receiver 41 and the front receiver 45. The front receiver 45 extends from an opening at the front end 44 to the narrow channel 43. The illustrated front receiver 45 can be defined by a clearance, for example a diameter, that narrows or tapers from the front end 44 to the narrow channel 43. This clearance of the front receiver 45 can define any diameter or geometry that allows the front strain-relief boot 50 to be inserted therein. As illustrated, for example, the narrowest clearance of the front receiver 45 is wider than the clearance of the narrow channel 43.

[0027] The illustrated housing 40 can include up to three apertures, for example at least one adhesive epoxy fill aperture and at least one vent aperture. For example, the illustrated housing can include a pair of adhesive epoxy fill apertures 46 extending through the outer wall relative to the narrow channel 43, and one further vent aperture 48 relative to the front receiver 45, to allow adhesive epoxy (not shown) to be inserted into the internal passageway of the housing. It is contemplated that the location and number of these adhesive fill and vent apertures can vary from that illustrated.

[0028] The rear receiver 41 receives (FIGS. 2 & 3) the rear strain-relief boot 30 therein and the plug 60, which is supported by the rear strain-relief boot 30, is received, for example with a friction fit, by the narrow channel 43. When assembled, as illustrated in FIG. 2, the plug 60 forms a seal with the narrow channel 43 to prevent any adhesive epoxy (not shown) injected within from exiting through the rear receiver 41.

[0029] As illustrated in FIGS. 4-5, the rear strain-relief boot 30 defines a strain-relief body 38 and a mounting flange 32. The rear strain-relief boot 30 is preferably made of some elastomeric material such as, but not limited to, rubber or silicone. The strain-relief body 38 can taper in width, for example diameter, between the mounting flange 32, for example a collar, and a distal end 33. The strain-relief body 38 can be flexible through a plurality of flex features 35, such as notch cutouts, positioned between the mounting flange 32 and the distal end 33. The mounting flange 32 is narrower than the widest part of the strain-relief body 38. The mounting flange 32 can have an outer surface that inserts into the rear receiver 41 of the housing 40 (FIGS. 2 & 3). The widest part of the strain-relief body 38 is wider than the opening of the rear receiver 41, and thus controls the distance into which the mounting flange 32 extends within the rear receiver.

[0030] As particularly illustrated in FIG. 5, the strain-relief body 38 includes a passageway 34 extending from the distal end 33 through the mounting flange 32 to allow the multi-fiber cable 20 (FIGS. 1 & 2) to extend therethrough. The mounting flange 32 includes a hollow interior section 39 (or cavity) defined by a coupling element 36, for example a circumferential mouth. As illustrated, the coupling element 36 can be defined by at least two different geometries having different widths which allow for the plug 60 to be securely received therein.

[0031] As illustrated in FIG. 6, the plug 60 defines an internal passageway 62 to partially receive the multi-fiber cable 20 therein (FIG. 2). Preferably, the internal passageway 62 has a clearance, for example a diameter, which snugly receives a tip of the multi-fiber cable 20, for example through a friction fit, and prevents adhesive epoxy inserted into the narrow channel 43 from travelling through the internal passageway. The plug 60 can define an outer geometry, for example a circumferential outer surface, which is frictionally received within the narrow channel 43 of the housing 40. For example, the plug 60 can have a geometry that is slightly wider than the narrow channel 43 in order to achieve a snug fit therein. The plug 60 can be of a material that is generally rigid with has a slight deformability to allow it to compress past the transition surface 47 and into the narrow channel 43 of the housing 40.

[0032] The plug 60 further includes a coupling feature 64 which correspondingly couples to the coupling element 36 in the rear strain-relief boot 30 (FIGS. 2 & 5). For example, the coupling feature 64 on the plug 60 can have a geometry, for example two different widths, that corresponds with the geometry of the coupling element 36 in the strain-relief boot 30 in order to provide a snap-on fit when inserted into the mouth of the mounting flange 32.

[0033] As illustrated in FIGS. 6-7, the plug 60 can be formed by more than one, preferably a pair of, separable sections 66a, 66b (arms or halves). These separable sections 66a, 66b can be opposingly symmetrical as illustrated. These separable sections 66a, 66b can be separably secured to each other through mounting features, for example a pair of operably opposing male inserts 65 and female receivers 63. These separable sections 66a, 66b remain aligned together by the resistive force applied by the coupling element 36 in the rear strain-relief boot 30 and the narrow channel 43 of the housing 40, once inserted therein.

[0034] In use, the separable sections 66a, 66b of the plug 60 are placed around the tip of the multi-fiber cable 20 (FIGS. 1-2) and the optical fibers 24 (FIG. 2) that extend therefrom, so that the cable and fibers are snugly contained within the internal passageway 62 once the separable sections are aligned. These optical fibers 24 extend through the narrow channel 43 and toward the front strain-relief boot 50.

[0035] FIG. 8 illustrates an enlarged view of the interconnection of the rear strain-relief boot 30, the rear plug 60 and the housing 40 as the multi-fiber cable 20 and optical fibers 24 and strength members 26 extend therethrough. As illustrated, the rear strain-relief boot 30 snugly inserts into the housing 40. The coupling element 36 (FIG. 5) of the rear strain-relief boot 30 fastens to, for example through a snap-on fit, the coupling element 64 (FIG. 6) of the rear boot 64. As further illustrated, rear plug 60 inserts past the transition surface 47 into the narrow channel 43 of the housing 40 to sealingly engage the inner passageway wall.

[0036] The front receiver 45 of the housing 40 receives (FIGS. 2 & 3) the front strain-relief boot 50 and the plug 70, which is supported by the front strain-relief boot, therein.

[0037] As illustrated in FIGS. 9-10, the front strain-relief boot 50 includes a strain-relief body 58 and mounting collar 59, for example a flange. The rear strain-relief boot 50 is preferably made of some elastomeric material such as, but not limited to, rubber or silicone. The front strain-relief body 58 can taper in width, for example diameter, between the mounting collar 59 and a distal end 53. The front strain-relief body 58 can be flexible through a plurality of notch cutouts 57 positioned between the mounting collar 59 and the distal end 53. The mounting collar 59 can have an outer surface that inserts into the front receiver 45 of the housing 40 (FIGS. 2 & 3). As illustrated, the outer surface of the mounting collar 59 can have a geometry defining tapering widths, for example diameters. As illustrated, the outer surface of the mounting collar 59 can define a first section 54 of increasing/expanding width and a second section 55 of decreasing/narrowing width in a direction toward the distal end 53. The widest point of the mounting collar 59 outer surface, preferably between the first 54 and second 55 sections is wider than the narrowest section of the tapering front receiver 45 of the housing 40, and thus controls the distance into which the connection flange extends within the front receiver. Thus, the mounting collar 59 can secure within the front receiver 45 with a friction fit.

[0038] As particularly illustrated in FIG. 10, the front strain-relief body 58 includes a passageway 51 extending from the distal end 53 through the mounting collar 59 to allow the optical fibers 24 and furcation tubes 22 (FIG. 2) extending from the multi-fiber cable 20 (FIGS. 1 & 2) to extend therethrough. The mounting collar 59 includes a hollow interior section 61 (or cavity), similar to the mounting flange 32 above, defined by a coupling element 56, for example a circumferential mouth. As illustrated, the coupling element 56 can be defined by at least two different geometries having different widths which allow for the plug 70 to be securely received therein.

[0039] As illustrated in FIG. 11, the plug 70 defines an internal passageway 72 to partially receive the optical fibers 24 (FIG. 2) extending through the housing 40 from the multi-fiber cable 20 (FIGS. 1 & 2). The plug 70 can define an outer geometry which is frictionally received within the front receiver 45 of the housing 40. For example, the plug 70 can have an outer geometry that is slightly wider than a section of the tapering front receiver 45 in order to achieve a snug fit therein. The plug 70 can be of a material that is generally rigid but has a slight deformability to allow it to compress into the front receiver 45 of the housing 40.

[0040] The plug 70 further includes a coupling feature 74 which correspondingly couples to the coupling element 56 in the front strain-relief boot 50 (FIGS. 2 & 9). For example, the coupling feature 74 on the plug 70 can have a geometry, for example two different widths, that corresponds with the geometry of the coupling element 56 in the front strain-relief boot 50 in order to provide a snap-on fit when inserted into the mouth of the mounting collar 59.

[0041] As illustrated in FIGS. 11-12, the plug 70 can be formed by more than one, preferably a pair of, separable sections 76a, 76b (arms or halves). These separable sections 76a, 76b can be opposingly symmetrical as illustrated. These separable sections 76a, 76b can be separably secured to each other through mounting features, for example a pair of operationally opposing male inserts 75 and female receivers 73. These separable sections 76a, 76b remain aligned together by the resistive force applied by the coupling element 56 in the front strain-relief boot 50 and the front receiver 45 of the housing 40, once inserted therein. In use, the separable sections 76a, 76b of the plug 70 are placed around the optical fibers 24 (FIG. 2) extending from the multi-fiber cable 20 (FIGS. 1 & 2), so that the fibers are snugly contained within the internal passageway 72 once the separable sections are aligned.

[0042] FIG. 13 illustrates an enlarged view of the interconnection of the front strain-relief boot 50, the front plug 70 and the housing 40 as the furcation tubes 22, optical fibers 24 and strength members 26 extend therethrough. As illustrated, the front strain-relief boot 50 snugly inserts into the housing 40. The coupling element 56 (FIG. 10) of the front strain-relief boot 50 fastens to, for example through a snap-on fit, the coupling element 74 (FIG. 11) of the front plug 70. As further illustrated, front plug 70 sealingly engages the inner passageway wall of the housing 40.

[0043] When the transition assembly 10 is assembled, as illustrated in FIGS. 1-2, the plugs 60, 70 form a seal within the housing 40 on either side of a length-wise axis of the narrow channel 43 (FIG. 3). Further, the optical fibers 24 and strength members 26 extend within the narrow channel 43 from one plug 60 to the other plug 70. Adhesive epoxy (not shown) is then injected into the internal passageway of the housing 40 through the adhesive epoxy fill apertures 46. As the internal passageway of the housing 40 fills with adhesive epoxy, an excess air and/or epoxy exits the housing through the venting aperture 48. The adhesive epoxy is then allowed to harden around the optical fibers 24 and strength members 26.

[0044] The adhesive epoxy used can be any suitable adhesive that can transition from a fluid state to a rigid hardened state over a period of some time. For example, the adhesive may be an epoxy-like substance which cures over a period of several minutes after injection. For example, the adhesive epoxy can be an ultra-violet reactive substance which hardens under an ultra-violet light source. In this embodiment, the transition assembly would require a means to allow the ultra-violet rays to reach the adhesive. For example, the housing 40 can be made of clear or a semi-clear plastic. Alternatively, using the multiple apertures 46, 48 in the housing 40, multiple different adhesive epoxies can be injected so that they react upon contacting each other.

[0045] Once hardened, the adhesive ensures that the furcation tubes 22 are linked to the multi-fiber cable 20 via a rigid structure. As a result, stress placed on the multi-fiber cable 20 and furcation tubes 22 is transferred directly to the furcation tubes and multi-fiber cable via the hardened adhesive without being transferred to the optical fibers 24. In addition, in embodiments where the strength members 26, such as aramid yarn, are present in the furcation tubes 22 and/or the multi-fiber cable 20, these strength members provide further structural elements which may be linked by way of the cured adhesive. These configurations may further decrease the likelihood of having forces placed on the multi-fiber cable 20 and furcation tubes 22 being transferred to the fibers 24 and strength members 26 within the transition.

[0046] Furthermore, when assembled, the elastomeric nature of the front boot 50 can provide improved optical performance when a bending load is applied to the furcation tubes 22. For example, when applying a load at 90 degrees relative to the transition assembly 10, the boot 50 contours to a slight radius instead of allowing the furcation tubes 22 to bend abruptly at 90 degrees. This helps to reduce stresses on the fibers 24 and strength members 26 and thereby improve optical performance when bending and applying a load to the furcation tubes 22. In one embodiment, the stress on the fibers 24 and strength members 26 is reduced and thereby optical performance is improved when a bending load is applied to the furcation tubes 22 between 90 degree and 135 degrees relative to the length-wise axis of the transition assembly 10. Without the plugs 60, 70 leaking adhesive epoxy can travel into, and harden within, the multi-fiber cable 20 and furcation tubes 22, thus reducing or preventing the ability for the multi-fiber cable and furcation tubes to flex. The plugs 60, 70 thus prevent adhesive epoxy from exiting the internal passageway of the housing 40 into the multi-fiber cable 20 and the furcation tubes 22, thus maintaining their elastomeric nature.

[0047] The present embodiment also relates to a fiber optic cable transition assembly and method for transitioning a plurality of optical fibers from a multi-fiber cable to a plurality of furcation tubes. The fiber optic transition assembly includes a cylindrical housing with an internal passageway defined by a wall. The housing includes a flowable fixation material injection port. The fiber optic transition assembly includes a first boot being positioned at least partially inside the housing and supporting the multi-fiber cable for providing strain relief to the plurality of optical fibers extending therethrough. The fiber optic transition assembly includes a first plug supported by the first boot and forming a seal within the housing internal passageway wall. The fiber optic transition assembly includes a volume of flowable fixation material which is cured, dried, and/or hardened and contained within the housing internal passageway between the first plug and a second end of the housing.

[0048] The present embodiment also relates to a fiber optic cable transition assembly and method for transitioning a plurality of optical fibers from a multi-fiber cable to a plurality of furcation tubes with the above features. The fiber optic transition assembly includes a second boot being positioned at least partially inside the housing and supporting the plurality of furcation tubes for providing strain relief to the plurality of optical fibers extending therethrough. The fiber optic transition assembly includes a second plug supported by the second boot and forming a seal within the housing internal passageway wall. The fiber optic transition assembly includes a volume of flowable fixation material which is cured, dried, and/or hardened and contained within the housing internal passageway between the first plug and the second plug.

[0049] The present embodiment also relates to a fiber optic cable transition assembly and method for transitioning a plurality of optical fibers from a multi-fiber cable to a plurality of furcation tubes. The fiber optic transition assembly includes an elongated housing with a first end opening, an opposite end opening and an internal passageway. The housing is adapted to receive a flowable fixation material, such as epoxy adhesive. The fiber optic transition assembly includes a boot being positioned at least partially inside the housing and receiving either the multi-fiber cable to provide strain relief to the plurality of optical fibers extending therethrough, or the plurality of furcation tubes. The fiber optic transition assembly includes a plug supported by the boot and retained by the housing to prevent epoxy adhesive from entering either the multi-fiber cable or the plurality of furcation tubes.

[0050] In one embodiment, the housing is cylindrical.

[0051] In one embodiment, a boot and a corresponding plug is positioned at both of the first end and the opposite end of the housing.

[0052] In one embodiment, the boot or boots snap or clip onto the respective plug or plugs.

[0053] Although specific embodiments of the disclosure have been described, numerous other modifications and alternative embodiments are within the scope of the disclosure. For example, any of the functionality described with respect to a particular device or component may be performed by another device or component. Further, while specific device characteristics have been described, embodiments of the disclosure may relate to numerous other device characteristics. Further, although embodiments have been described in language specific to structural features and/or methodological acts, it is to be understood that the disclosure is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as illustrative forms of implementing the embodiments. Conditional language, such as, among others, “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments could include, while other embodiments may not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments.