Disclosed embodiments relate to a hardened drop terminal and clampshell that can be utilized in a fiber optic cable distribution network on a central office side of a telecommunications network. More particularly, the disclosed embodiments relate to a hardened drop terminal and clampshell that minimizes or limits tensile and rotational stresses that are placed on fiber optic cable connections within the hardened drop terminal on the central office side of the telecommunications network.
The telecommunications industry commonly utilizes a fiber optic network to transmit data. A fiber optic telecommunications network typically has a backbone or feed fiber optic cable that supports communications to and from branch or secondary fiber optic cable networks. The backbone or main fiber optic cable has a plurality of individual cables along with strengthening members that are contained within a heavy sheath.
A typical fiber optic cable that is used outdoors and is exposed to the environment includes a heavy and stiff jacket that makes manipulating and positioning the fiber optic cable difficult. When a portion of the fiber optic cable is positioned within an enclosure, the heavy and stiff jacket is typically stripped from the fiber optic cable and replaced with an interior jacket that is more lightweight and flexible jacket compared to the heavy and stiff outdoor rated jacket. The interior jacket allows the fiber optic cable to be more easily manipulated and worked with. The interior jacket can be rated for indoor applications and/or outdoor applications.
A common location where a fiber optic network experiences failure is at a distribution junction from the backbone or main cable to fiber optic networks that branch from the backbone or main cable on the central office side of the fiber optic network. A typical location of the distribution junction is at telecommunications pole for overhead fiber optic networks and at a pedestal for buried fiber optic networks. This failure is typically caused by tensile or rotational stresses at the connection between the individual feed fiber optic cables of the backbone or feed fiber optic cable and the individual branch fiber optic distribution fiber optic cables.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.
Disclosed is an exemplary embodiment of a clampshell that transitions a jacketing of an individual fiber optic cable from a heavy and stiff jacket that is rated for outdoor use to a more flexible and lightweight interior jacket that is rated for either indoor use or outdoor use. It is also contemplated that the clampshell is capable of transitioning one fiber optic cable to another fiber optic cable with a splice connection, such as a fusion splice or a mechanical splice. The clampshell has hingedly connected housing halves that are positionable between an open position and a closed position. The housing halves are typically constructed of a rigid material, such as a high-density polymer. Each of the housing halves includes an inner surface that defines an interior cavity when the housing halves are positioned into the closed position. The housing halves have open opposing first and second ends that are sized to allow the fiber optic cable having the different types of jacketing to be positioned within the interior cavity. The clampshell includes at least one strain relief that has a through bore sized to pass the fiber optic cable with the interior jacket therethrough. The strain relief is constructed of a compressible material and has an outer surface configured to fit into the interior cavity proximate the first end. The strain relief has an outer diameter that is greater than a diameter of the inner cavity when the halves are positioned into the substantially closed position. Outer surfaces of the housing halves have cooperating threads at the opposing first and second ends when the housing halves are in a substantially closed position such that the threaded surfaces are configured to accept a threaded nut. As a nut is threaded onto the outer surface through a threaded engagement proximate the first end, the housing halves are forced together which causes the strain relief to compress and frictionally engage the interior jacketed fiber optic cable. The frictional engagement between the strain relief and the interior jacketed fiber optic cable provides strength to the cable within the strain relief. A second end of the clampshell includes opposing cutouts that accept the heavy and stiff jacketed, flat fiber optic cable while having a sufficient diameter to accept a round heavy and stiff jacketed fiber optic cable to pass therethrough. A second nut is threadably secured to the second end and causes the second ends of the two halves to frictionally engage the heavy and stiff jacketed fiber optic cable portion and retain the interior jacketed cable portion. The engagement between the nuts and the threaded outer surfaces at the first and second ends seal the clampshell such that the clampshell is water-resistant.
Disclosed is an exemplary embodiment of a hardened drop terminal for connecting fiber optic cables on a central office of a telecommunications fiber optic network, typically at a telecommunications pole for overhead fiber optic cables or at a pedestal for underground or buried telecommunication fiber optic distribution cables. The hardened drop terminal includes a base unit having an entrance port for a backbone or main telecommunications cable from central office side of the telecommunications fiber optic network cable. The hardened drop terminal includes a clamp to secure the sheathed telecommunications fiber optic network within an interior cavity and allows a length of the fiber optic cable(s) to be exposed that extend beyond the clamp. The hardened drop terminal also includes a bulkhead connector having one or more paired receptacles that couple one or more the fiber optic cables from the backbone or main fiber optic cables on a first side to one or more fiber optic cable distribution cables on the second side of the bulkhead connector. The fiber optic distribution cables include one or more drop cables having a proximal end connected to the second of the bulkhead connector. The drop cables are typically jacketed with an interior jacket rated for interior use or outdoor use where the jacket is flexible which allows the fiber optic cable to be more easily worked with. A length of the drop cable is jacketed with the interior jacket such that drop cable with the interior jacket is located proximate a wall of the hardened drop terminal. A clampshell is configured to engage and frictionally secure the interior jacketed drop cable while providing strength and strain relief of the drop cable. The clampshell also transitions the drop cable from the interior jacket to a rigid and stiff jacket that is rated for outdoor use. An outer surface of the clampshell includes at least one tongue having a flat surface and at least one groove having a flat surface. The tongue and groove in the clampshell engage corresponding grooves and tongues in a slot within the base unit such that the interaction between the corresponding tongues and grooves prevent rotation of the clampshell relative to the hardened drop terminal such that rotational stresses are minimized at the connection of the drop cable to the bulkhead connector while also preventing pulling forces or tensile stresses from being placed upon the drop cable and thereby increasing the reliability of the fiber optic telecommunications network on the central office side of the telecommunications network.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
Before any embodiments of the disclosure are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. Unless specified or limited otherwise, directional terms, such as “upper,” “lower,” “left,” “right,” “above,” and “below,” are used herein to allow elements of the present disclosure to be described in spatial terms, and are non-limiting as other spatial arrangements of the disclosed elements are contemplated.
Disclosed embodiments include a hardened drop terminal which couples individual fiber optic cables of a backbone or main fiber optic cable to individual distribution fiber optic cables on central office side of a telecommunications network. The hardened drop terminal cooperates with a clampshell that transitions a drop cable jacketed with a lightweight and flexible interior jacket to a heavy and relative rigid jacket that is suitable for outdoor applications. The transition of the jacketing of individual fiber optic cables from the interior jacketing to the heavy and rigid outdoor rated jacketing within the clampshell, where the clampshell cooperates with the housing of the hardened drop terminal, minimizes tensile stresses at a connection between the drop cable and the individual fiber optic cable of the backbone or main fiber optic cable. An engagement of an outer surface of the clampshell with a surface on the housing of the hardened drop terminal also minimizes rotational stresses at the connection of the drop cable to the individual fiber optic cable of the backbone or main fiber optic cable.
Referring now to
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Typically, only one cable entrance port 132 or 134 is necessary. However in some instances both cable entrance ports 132 and 134 can be required. One such instance when both cable ports 132 and 134 are necessary is when a mid-sheath entrance is utilized. When a mid-sheath entrance is utilized, the backbone or main fiber optic cable from the central office is secured through a port, typically port 132. A selected number of the individual fiber optic cables from the backbone or main cable from the central office are utilized in the hardened drop terminal 100 and the remaining number of sheathed individual fiber optic cables of the backbone or main fiber optic cable are then first secured in a clamp 133 and then exit the hardened drop terminal 100, typically through the port 134.
In a typical configuration the fully sheathed backbone or main cable from the central office is positioned through the grommet 136 in the cable entrance port 132 and through an opening 140 in a clamp 143 that is secured to the back wall 122 of the hardened drop terminal 100. With the cable positioned within the opening 140, the clamp 143 is manipulated to constrict the opening 140 with left and right screws and thereby frictionally retaining the fully sheathed backbone or main cable from the central office within the clamp 143. However, other clamping mechanisms or securing mechanisms besides the illustrated clam 143 are also contemplated.
The sheathing is then removed to expose the individual fiber optic cables and strengthening members in the backbone or main cable from the central office. The strengthening members are typically constructed from fiberglass or metal and prevent the cable from being excessively bent and also to provide structural integrity to the fiber optic cable. A fiber optic cable can be damaged when excessively bent, which can limit the effectiveness of the cable in the transmission of data and the strengthening members minimize this type of damage.
The strengthening members are typically cut or snipped to a selected length such that ends of the strengthening members can be positioned within through bores 144 in a securing mechanism 146 attached to and extending from the back wall 122 of the hardened drop terminal 100 with a screw 147. Screws 148 are then manipulated through threaded bores in communication with the through bores 144 to frictionally secure the strengthening members between a surface defining one of the through bores 144 and an end of the screw 148 where typically one strengthening member is secured within each of the through bores 144.
While a securing mechanism 146 having two through bores 144 is illustrated, it is also contemplated that a securing member 146 with any number of through bores could be utilized. It is also contemplated that the hardened drop terminal 100 could be utilized without the securing mechanism 146.
Referring to
The bulkhead connector 150 is connected to the back wall 122 with left and right spacers 151 (one of which is illustrated in
Extending from the back wall 122 are a plurality of arcuate storage clips 160 that act as a reel for storing excess length of cable. As the fiber optic cables are typically prefabricated at a factory and include a selected connector, the storage clips 160 allow the excess length to be spooled around the clips 160 and stored without harming the fiber optic cable.
Further, the gap 155 between the bulkhead connector 150 and the back wall 122 provides better access to the storage clips 160 to better allow for management of the excess length of fiber optic cable relative to locating the bulkhead connector 150 proximate the back wall 122.
A second plurality of arcuate storage clips 162 extend form the back wall 122 and are located between the bulkhead adaptor 150 and the bottom wall 124. The second plurality of storage clips 162 act as a reel similar to that of the storage clips 160 to allow excess length of fiber optic cable to be stored without harming the fiber optic cable.
Referring to
The clampshell 200 transitions the drop cables 164 from the interior lightweight and flexible jacket to a heavy and rigid jacket 180 that is suitable for outdoor applications. It is also contemplated that the clampshell 200 provide strength and support to splices of the drop cable 164 to a distribution fiber optic cable, such as but not limited to a fusion splice and a mechanical splice. The clampshell 200 provides a water-resistant closure that increases the uptime and reliability of the telecommunications network.
Referring to
The interaction of the flat surfaces of the tongue 203 in the clampshell 200 with the groove 195 in the slot 190 along with the interaction of the groove 207 in the clampshell 200 with the tongue 192 in the slot 190 prevent rotation of the clampshell 200 relative to the base unit 110 and, therefore, minimize rotational stress and strain on the connection between the drop cable 164 and the bulkhead connector 150 on the second side 154 of the bulkhead connector 150. The interaction of the tongues 203 and 192 with the groves 195 and 207, respectively, also prevent the clampshell 200 from being pulled from the slot 190 and therefore limits the tensile stresses on the connection between the drop cable 164 and the bulkhead connector 150. While a tongue and groove connection between the clampshell 200 and the slot 190 are illustrated, other securing mechanisms besides the tongue and groove securing mechanism are also contemplated.
As illustrated, the base unit 110 includes four slots 190 that are configured to accept two clampshells 200 in each slot 190. Each slot 190 has substantially parallel side walls and arcuate distal end wherein a proximal opening is configured to accept a clampshell 200. However, the number of slots 190 and clampshells 200 that are utilized can be modified to meet the requirements of any particular application.
As illustrated, three of the slots 190 each engage two clampshells 200 while another slot 190 engages a drop cable 164 with a different connector. However, it is contemplated that drop cables 164 secured to the clampshells 200 can be utilized in all of the slots.
Referring to
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The interior of the base 202 includes a shoulder 220 that extends from a left edge 219 to a right edge 221. The shoulder 220 includes an arcuate cutout 224 that is sized to accept the interior sheathed portion 226 of the drop cable 164. Extending from an interior surface of the shoulder 220 is a raised platform 228 that is configured to prevent the interior sheathed portion 226 from flexing towards the interior surface 212 of the base 202.
The interior sheathed portion 226 of the drop cable 164 is retained in the clampshell 200 by inserting the interior sheathed portion 226 of the drop cable 164 through a through bore 232 in a strain relief 230. The strain relief 230 is constructed of a flexible and compressible polymeric material and has a frusto-conical configuration where a larger diameter end 233 is positioned proximate the shoulder 220 and a smaller diameter end 234 extends beyond a top end of the base 202.
The cover 204 has a similar construction proximate a bottom end as that of the top end of the base 202 where the cover 204 includes a similarly configured shoulder 240 to that of the shoulder 220 where the shoulder 240 includes a cutout 242 with substantially the same radius as the cutout 224 where the cutouts 224 and 242 form a through bore that is sized to accept and pass the interior sheathed portion 226 of the fiber optic drop cable 164 therethrough. The cover 204 also includes a raised platform 244 that also prevents excessive flexing of the interior sheathed portion 226 of the fiber optic drop cable 164.
The larger end 233 of the strain relief 230 engages the shoulder 240, which prevents the strain relief 230 from being inserted into the interior cavity 216 beyond the shoulder 220. In the closed position, the shoulder 240 also engages the larger end 233 of the strain relief 230 and prevents the strain relief 230 from being inserted further into the interior cavity 216.
A diameter of the strain relief 230 at the larger end 233, and extending a distance toward the smaller end 234, is greater than the diameter of the inner surfaces of the base 202 and the cover 204 at the top end when positioned in the closed position. When in the closed position, the base 202 and the cover 204 have cooperating threaded surfaces 250 and 252 in the outer surfaces 203 and 205, all respectively.
The cooperating threaded surfaces 250 and 252 accept the top threaded nut 208 which forces the cover 204 and the base 202 together and compresses the portion of the strain relief 230 within the interior cavity 216. As the strain relief 230 compresses, the through bore 232 constricts which causes a frictional engagement between the strain relief and the interior sheathed portion 226 of the drop cable 164. The strain relief 230 therefore provides strength to the interior sheathed portion 226.
A bottom end 260 of the clampshell 200 is configured to accept the portion 181 of the fiber optic drop cable 164 having a flat, heavy and rigid outdoor jacket 180 (as illustrated in
Referring to
With the strengthening members 282 and 284 retained to the base 202 with the locking members 292 and 294 and the portion 181 of the outdoor jacket 180 transitioned to the interior jacketed portion 226 of the drop cable 164, the cover 202 is closed and the bottom nut 210 along with the top nut 208 threadably engage the threaded outer surfaces of the base 202 and the cover 204. The engagement of the nut 208 was previously discussed. The engagement of the nut 210 with the outer surfaces of the base 202 and the cover 204 constrict the opening at bottom end 260 and frictionally engage the jacket 180 to retain the portion 181 within the clampshell 200.
Referring to
With the cover 204 in a closed position relative to the base 202, a diameter of the round jacket 180 is larger than a diameter of the opening at the bottom 260. As the nut 210 threadably engages the threaded outer surfaces, the base 202 and the cover 204 are forced together, which constricts the opening at the bottom end 260 such that the base 202 and cover 204 frictionally engage the round jacket 180 to retain the portion 181 of the drop cable 164 within the clampshell 200.
Referring back to
The hardened drop terminal 100 is then moved to position the second slot shaped portions 179 about the shaft of the bolt or screw, such that the head of the screw or bolt cannot pass therethrough and thereby mount the hardened drop terminal 100 to the surface. To remove the hardened drop terminal 100 from the surface, the hardened drop terminal 100 is raised to position the screw or bolt head in alignment with the circular first portion 177 of the aperture 175. The hardened drop terminal 100 is the moved away from the surface until each of the mounting plates 171 is spaced from each of the heads of the screws or bolts.
A best illustrated in
The splice plate 300 includes a top spool 306 and a bottom spool 308 to manage the unjacketed or unsheathed fiber optic cables. The splice plate 300 includes two storage tools 310 and 312 that are configured to retain the splices for the installer. While a splice tray 300 is a convenient tool for the installer, the splice plate 300 is not necessary to practice the present disclosure.
Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims. For example, in various embodiments, the hardened drop terminal can be made from materials other than plastic. Further, the various components can be arranged in different ways than those specifically illustrated. Other examples of modifications of the disclosed concepts are also possible, without departing from the scope of the disclosed concepts.
Filing Document | Filing Date | Country | Kind |
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PCT/US2015/031489 | 5/19/2015 | WO | 00 |
Number | Date | Country | |
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62003166 | May 2014 | US |