CABLE OVER-PULL PROTECTION Background
Optical networks are becoming prevalent in part because service providers want to deliver high bandwidth communication capabilities to customers. The optical networks include multiple optical fiber cables connecting a source location to multiple subscriber locations. One or more feeder optical cables extend from the source location and branch out into subscriber cables at various points in the optical network. Cabinets or other enclosures may be disposed at these branch points to protect and manage the cables.
FIG. 1 illustrates an example optical network 100 deploying fiber optic lines. As shown in FIG. 1, the network 100 may include a central office 110 that connects a number of end subscribers 115 (also called end users 115 herein) in a network. The central office 110 may additionally connect to a larger network such as the Internet (not shown) and a public switched telephone network (PSTN). The various lines of the network can be aerial or housed within underground conduits (e.g., see conduit 105).
The network 100 may include fiber distribution hubs (FDHs) 130 or other types of enclosures at which one or more feeder cables may branch or couple to two or more subscriber cables. In some implementations, the FDHs 130 include one or more optical splitters (e.g., l-to-8 splitters, l-to-16 splitters, or l-to-32 splitters) that generate a number of individual subscriber fibers from one or more feeder fibers. The subscriber fibers may be routed from the FDH 130 to the premises of an end user 115. In other implementations, the FDHs 130 may include one or more splice trays at which feeder fibers and subscriber fibers are connected.
The network 100 also includes a plurality of breakout locations 125 at which branch cables (e.g., drop cables, stub cables, etc.) are separated out from main cables (e.g., subscriber cables). Breakout locations 125 also can be referred to as tap locations or branch locations and branch cables can also be referred to as breakout cables. At a breakout location 125, fibers of the branch cables are typically spliced to selected fibers of the main cable. However, for certain applications, the interface between the fibers of the main cable and the fibers of the branch cables can be connectorized. In certain implementations, a cabinet or other enclosure may be positioned at the breakout locations 125.
Stub cables are typically branch cables that are routed from breakout locations to intermediate access locations such as a pedestals, drop terminals or hubs. Intermediate access locations can provide connector interfaces located between breakout locations and subscriber locations 115. A drop cable is a cable that typically forms the last leg to a subscriber location 115. For example, drop cables are routed from intermediate access locations to subscriber locations 115. Drop cables can also be routed directly from breakout locations to subscriber locations 115, thereby bypassing any intermediate access locations Summary
A method of managing optical fibers within an enclosure includes mounting an over- pull mitigation arrangement within the cabinet between the cable port and the connection region; routing the optical fiber along an extended path within the cabinet from the cable port to a connection region; and storing an overlength of the optical fiber at an over-pull mitigation arrangement disposed within the cabinet so that the overlength is automatically released from the over-pull mitigation arrangement when an over-pull of the optical fiber occurs.
Some example types of over-pull mitigation arrangements include one or more retainers that are configured to releasably hold one or more optical fibers or fiber cables until a predetermined force is applied to the fibers or cables.
Other example types of over-pull mitigation arrangements include one or more retainers that are configured to release from a wall or other mounting surface when a predetermined force is applied to fibers or cables being held by the retainer.
Other example types of over-pull mitigation arrangements include spool
arrangements configured to store a coil of optical fibers having a first diameter and to partially release the optical fibers when an over-pull of the optical fibers occurs so that the coil of fibers shrinks to a second diameter that is less than the first diameter.
A pull-protection arrangement defines a curved path that provides increased retention of the fibers and/or cables to inhibit axial movement of the fibers and/or cables during an over-pull of the fibers and/or cables.
A variety of additional aspects will be set forth in the description that follows. These aspects can relate to individual features and to combinations of features. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the broad concepts upon which the embodiments disclosed herein are based.
Brief Description of the Drawings
FIG. 1 illustrates an example optical network deploying fiber optic lines; FIG. 2 illustrates an example cabinet that receives one or more optical fiber cables from an underground conduit;
FIG. 3 illustrates one example implementation of the cabinet of FIG. 2 in which a plurality of splice cassettes are disposed at a connection region and an over-pull mitigation arrangement is disposed between the connection region and a cable port;
FIGS. 4-14 illustrate a first example over-pull mitigation arrangement;
FIGS. 15-21 illustrate a second example over-pull mitigation arrangement; and
FIGS. 22-24 illustrate a third example over-pull mitigation arrangement;
FIG. 25 illustrates another example cabinet including a pull-protection arrangement disposed within the cabinet adjacent a connection region;
FIGS. 26-33 illustrate various example implementations of the pull-protection arrangement; and
FIG. 34 illustrates one example cabinet in which two pull-protection arrangements are disposed adjacent the connection region. Detailed Description
Reference will now be made in detail to the exemplary aspects of the present disclosure that are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like structure.
FIG. 2 illustrates an example cabinet 200 that receives one or more optical fiber cables 230 from an underground conduit 220. The cabinet 200 may be located at any connection point in an optical network (e.g., at an FDH location 130 or a breakout location 125 of the optical network 100 of FIG. 1). The cables 230 are routed from the conduit 220 into the cabinet 200 through cable ports 210. Optical fibers of the cables 230 are routed within the cabinet 200 from the cable ports 210 to a connection region 215. In the example shown, the fibers are routed to a plurality of splice cassettes or trays 215. In other implementations, the fibers may be routed to a plurality of optical adapters.
Underground conduits, such as conduit 220 of FIG. 2, typically protect the optical fiber cables, such as cable 230, as the cables pass through the conduit 220. For example, the underground conduit 220 may protect the cables from traffic, weather, people, and animals by burying the conduit out of reach beneath the ground. However, during certain situations, the underground conduits may be raised or otherwise moved from where they were laid. For example, during road construction, a backhoe or other construction vehicle may inadvertently hit, lift, or otherwise engage a buried conduit through which live fiber cables are running. Movement of the conduit may pull on the fibers passing through the conduit.
As shown in FIG. 2, movement of the conduit 220 may pull on the optical fiber cables 230 along a direction P, thereby moving the cables 230 within the cabinet 200 in a direction towards the conduit 220. For example, in some situations, the cables 230 may be pulled back ten centimeters, twenty centimeters, forty centimeters, or more during a road construction accident. Such over-pulling of the cables may be problematic for both optical fibers and blown fiber cables. Pulling on the cables 230 may cause the cable fibers to pull away from the connection region 215 or apply significant strain to the cable fibers. In the case of blown fibers, pull-back protectors may apply only to the speedpipes within which the blown fibers are situated, not to the blown fibers themselves. In still other implementations, the cables 230 may be pulled at a point internal to the cabinet 200 by a technician while working within the cabinet 200.
FIG. 3 illustrates one example cabinet 200 in which a plurality of splice cassettes 216 are disposed at a connection region 215. Blown fiber tubes 232 are routed into the cabinet 200 through the cable ports 210. One or more optical fibers 234 pass through the speedpipes 232 at a transition region 212 of the cabinet 200. In certain implementations, the optical fibers 234 are up-jacketed (e.g., are contained within a buffer tube or jacket for protection). In other implementations, optical fibers 234 may be separated out (e.g., at fanout devices) from cables 230 routed into the cabinet 200 at the cable ports 210.
The optical fibers 234 are routed around the cabinet 200 to the trays 216 at which the optical fibers 234 are connected together. For example, one or more of the optical fibers 234 may form a feeder cable and two or more of the optical fibers 234 may form one or more subscriber cables. As shown in FIGS. 2 and 3, an over-pull mitigation arrangement 240 may be disposed within the cabinet 200 to inhibit pulling the cable fibers away from the connection region 215 and/or to inhibit the application of strain to the cable fibers 234. In general, the over-pull mitigation arrangement 240 is disposed between the cable ports 210 and the connection region 216.
The over-pull mitigation arrangement 240 is configured to store an excess length (i.e., an overlength) of optical fibers 234. When an over-pull occurs, the over-pull mitigation arrangement 240 is configured to at least partially release the optical fibers 234 to enable portions of the fibers 234 to move axially towards the conduit 220. In some implementations, the over-pull mitigation arrangement 240 fully releases the optical fibers 234 during an over-pull event. In other implementations, the over-pull mitigation arrangement 240 releases the overlength of the optical fibers 234, but otherwise retains the optical fibers 234 while maintaining a proper bend radius of the fibers 234.
Advantageously, the over-pull mitigation arrangement 240 provides a visual cue for a technician indicating that an over-pull has occurred in the network. Such knowledge may prompt an investigation as to where and how the over-pull occurred and whether any damaged was caused within the enclosure 200 and/or elsewhere in the network 100.
FIGS. 4-24 illustrate various example implementations of over-pull protection devices 240 suitable for use in cabinet 200. FIGS. 4-14 illustrate a first example over-pull mitigation arrangement 250; FIGS. 15-21 illustrate a second example over-pull mitigation arrangement 270; and FIGS. 22-24 illustrate a third example over-pull mitigation
arrangement 290. These example implementations generally provide storage for overlength of fibers and/or cables that may be taken up in the event of an over-pull.
The over-pull mitigation arrangement 250 shown in FIGS. 4-14 includes one or more retainers 251 that are configured to releasably hold one or more optical fibers 234 or fiber cables until a predetermined force is applied to the fibers 234 or cables. In certain implementations, the over-pull mitigation arrangement 250 includes a plurality of retainers 251. In the example shown, the retainers 251 are disposed at a rear wall 201 of the cabinet 200 in a stacked formation. In other implementations, the retainers 251 may be stacked along one of the side walls, an internal panel, or a front wall of the cabinet 200. In still other implementations, the retainers 251 may be disposed in a different configuration (e.g., a rectangular configuration, a ring, etc.).
FIGS. 5 and 6 illustrate how the retainer 251 functions. One or more fibers 234 are routed between a cable port 210 and a connection region 215. As shown, one or more bend radius limiters 213 may be disposed along the path of the fibers 234 between the port 210 and the connection region 215. A direct path between the port 210 and the connection region 215 has a path length L2. The fibers 234 are routed along an extended path (e.g., a detour) between the cable port 210 and the connection region 215. The extended path has a length LI, thereby providing an overlength (i.e., slack length) of the fibers 234 between the port 210 and connection region 215 that is equal to the difference between the length LI and the length L2.
The retainer 251 holds the fibers 234 in the extended path as shown in FIG. 5. When the fibers 234 are pulled (e.g., from within the cabinet, from a conduit outside the cabinet, etc.), the retainer 251 releases the fibers 234 as shown in FIG. 6. Releasing the fibers 234 enables the fibers to be pulled towards (and out of) the port 210 by a distance up to the overlength of the fibers 234. For example, pulling the fibers 234 out of the retainer 251 causes the fibers 234 to move from the extended path towards the direct path as the overlength of the fibers is taken up by the pull. In some implementations, difference between the extended path and the direct path may be about 5-30 cm. In certain
implementations, the difference is about 10-20 cm.
FIGS. 7-12 illustrate one example retainer 251 including a body 252 having a front 260, a rear 261, a first side 262, a second side 263, a top 264, and bottom 265. The body
252 defines a channel 253 extending from the first side 262 to the second side 263. The channel 253 extends between top and bottom walls 254 of the body 252 that connect at the rear 261 of the body 252. The front side 260 of the walls 254 curve towards each other and meet at a seam 256. The inwardly curved sections 255 of the walls 254 define the front of the channel 253.
In some implementations, the walls 254 of the retainer body 252 are sufficiently flexible to enable a user to slide one or more optical fibers into the channel 253 through the seam 256. In certain implementations, the outer surfaces of the walls 254 at the front side 260 of the retainer 251 also are curved to inhibit damage to the fibers 234 when the fibers 234 are inserted into the channel 253 through the seam 256 (e.g., see the right-most side of FIG. 11). In other implementations, optical fibers also may be routed through the channel
253 from one of the sides 262, 263.
As shown in FIG. 10, the front side 260 of the retainer 251 is curved to provide bend radius protection for the fibers in the event of an over-pull. If the fibers are pulled from the extended path within the retainer 251 towards the direct path, then the fibers are pulled forwardly against the inwardly curved surfaces 255 of the walls 254. As shown in FIG. 5, the fibers will curve along the channel 253 at the seam 256. The walls 254 or at least the curved sections 255 of the walls 254 are sufficiently rigid to retain the fibers within the channel 253 under normal operating conditions of the cabinet 200. However, the walls 254 of at least the curved sections 255 of the walls 254 are sufficiently flexible to enable the fibers to exit the channel 253 through the seam 256 when a predetermined amount of force is applied (e.g., by a technician working within the cabinet, by a road construction worker, etc.).
The rear side 261 of the retainer 251 includes a mounting arrangement with which the retainer 251 may be mounted to a wall or panel of the cabinet 200. In the example shown, the mounting arrangement includes a latching tab 259 disposed between two holding tabs 258. Each of the holding tabs 258 includes an L-shaped flange defining a slot 257. The latching tab 259 defines a cam surface and a shoulder. The cam of the latching tab 259 faces the same side as the slots 257 of the holding tabs 258. The retainer 251 is mounted to a surface by sliding the retainer 251 in a first direction relative to the surface to hook the holding tabs 258 into openings in the surface. The retainer 251 is slid until the latching tab 259 snaps over a lug to lock the retainer 251 against sliding movement in the opposite direction.
FIGS. 13 and 14 illustrate the effects of a cable over-pull on one optical fiber 234' routed through the channel 253. In FIG. 13, multiple optical fibers 234 are routed through the channel 253 of one example retainer 251 of an over-pull mitigation arrangement 250. If a predetermined amount of force is applied to one 234' of the optical fibers 234 in a downward and/or forward direction, then the optical fiber 234' will pass through the seam 256 of the retainer 251 to exit the channel 253. In FIG. 14, the optical fiber 234' extends along a more direct path, free from the retainer 251. The other optical fibers 234 remain within the channel 253 of the retainer 251.
In some implementations, the retainer 251 is configured to release the fibers 234 upon the application of a force in the range of at least one Newton (N). In certain implementations, the retainer 251 is configured to release the fibers 234 upon the application of a force of at least 3 N. In certain implementations, the retainer 251 is configured to release the fibers 234 upon the application of a force of at least 5 N. In certain
implementations, the retainer 251 is configured to release the fibers 234 upon the application of a force of at least 10 N. In certain implementations, the retainer 251 is configured to release the fibers 234 upon the application of a force of at least 15 N.
The over-pull mitigation arrangement 270 shown in FIGS. 15-21 includes one or more retainers 271 that are configured to mount to a surface and to hold one or more optical fibers 234 or fiber cables until a predetermined force is applied to the fibers 234 or cables. When the predetermined force is applied, each retainer 271 is configured to release from the surface to enable the fibers 234 to move from the extended path towards the direct path. In certain implementations, each retainer 271 is configured to release from the surface without releasing the optical fibers 234. In certain implementations, the over-pull mitigation arrangement 270 includes a plurality of retainers 271.
FIGS. 15-19 illustrate a second example retainer 271 including a body 272 having a front 280, a rear 281, a first side 282, a second side 283, a top 284, and bottom 285. The body 272 defines a channel 273 extending from the first side 282 to the second side 283. The channel 273 extends between top and bottom walls 274 of the body 272 that connect at the rear 281 of the body 272. The front side 280 of the walls 274 curve towards each other and meet at a seam 276. The inwardly curved sections 275 of the walls 274 define the front of the channel 273. In some implementations, the walls 274 of the retainer body 272 are sufficiently flexible to enable a user to slide one or more optical fibers into the channel 273 through the seam 276. In other implementations, optical fibers also may be routed through the channel 273 from one of the sides 282, 283.
As shown in FIG. 17, the front side 280 of the retainer 271 is curved to provide bend radius protection for the fibers in the event of an over-pull. If the fibers are pulled from the extended path within the retainer 271 towards the direct path, then the fibers are pulled forwardly against the inwardly curved surfaces 275 of the walls 274. The fibers will curve along the channel 273 at the seam 276. The walls 274 or at least the curved sections 275 of the walls 274 are sufficiently rigid to retain the fibers within the channel 273 under normal operating conditions of the cabinet 200.
In some implementations, the walls 274 of the retainer body 272 are sufficiently flexible to enable a user to slide one or more optical fibers into the channel 273 through the seam 276. In certain implementations, the outer surfaces of the walls 274 at the front side 280 of the retainer 271 also are curved to inhibit damage to the fibers 234 when the fibers 234 are inserted into the channel 273 through the seam 276 (e.g., see the left-most side of FIG. 18). In other implementations, optical fibers also may be routed through the channel 273 from one of the sides 282, 283.
The rear side 281 of the retainer 271 includes a mounting arrangement with which the retainer 271 may be mounted to a wall or panel of the cabinet 200. In some
implementations, the mounting arrangement includes at least one flexible finger 277. In the example shown, the mounting arrangement includes first and second flexible fingers 277 protruding rearwardly from the retainer body 251 at opposite sides of the rear 281. Each finger 277 is configured to flex laterally (i.e., towards the first and second sides 282, 283 of the retainer 271. Each finger 277 defines a first ramped surface 278 and a second ramped surface 279 forming a triangle pointing outwardly from the fingers 277.
FIGS. 20 and 21 illustrate the effects of a cable over-pull on one or more optical fibers 234 routed through the retainer channel 273. In FIG. 20, the over-pull mitigation arrangement 270 includes multiple retainers 271 disposed at a rear wall 201 of the cabinet 200 in a stack formation. In other implementations, the retainers 271 may be stacked along one of the side walls, an internal panel, or a front wall of the cabinet 200. In still other implementations, the retainers 271 may be disposed in a different configuration (e.g., a rectangular configuration, a ring, etc.).
Each retainer 271 is mounted to the wall by inserting at least a portion of the flexible fingers 277 into an opening defined in the wall. The cammed surface 279 facilitates insertion of the respective finger 277 through the opening and the cammed surface 278 temporarily secures the retainer against removal from the surface. The fingers 277 are sufficiently stiff so that the weight of the fibers 234 alone is not sufficient to cam the surface 278 out of the opening in the surface. The fingers 277 are sufficiently flexible to enable the ramped surface 278 to slide out of the opening when an over-pull force is applied to the fibers 234 routed through the channel 273 of the retainer 271.
FIG. 20 shows multiple optical fibers 234 are routed through the channel 273 of one example retainer 271 of the over-pull mitigation arrangement 270. If force is applied to at least one 234 of the optical fibers 234 in a downward and/or forward direction, then the optical fiber 234 will move downwardly and/or forwardly within the channel 273 towards the curved walls 275 and seam 276. FIG. 21 shows the retainer 271 having been pulled away from the wall 201 so that the optical fibers 234 extend along a more direct path between the port 210 and the connection region 215. In the example shown, all of the optical fibers 234 remained within the channel 273 of the retainer 271. In other
implementations, one or more of the fibers 234 may exit the channel 273 through the seam 276 during the over-pull.
The over-pull mitigation arrangement 290 shown in FIGS. 22-24 includes one or more spool arrangements configured to hold the optical fibers 234 wound at a first diameter Dl (FIG. 23) until an over-pull occurs. When the over-pull occurs, the spool arrangement 290 is configured to partially release the fibers 234 so that the fibers are wound at a second diameter D2 (FIG. 24). The spool arrangement 290 includes a drum 293 extending between first and second parallel plates 291, 292. The drum 293 has a diameter that is sufficiently large to provide bend radius protection to fibers wound around the drum 293.
In some implementations, the plates 291, 292 are generally oblong and the drum 293 is disposed off-center of the plates 291, 292. In other implementations, the plates 291, 292 may have any desired shape (e.g., round, rectangular, obround, triangular, etc.). In still other implementations, the drum 293 may extend between the centers of the plates 291, 292. When optical fibers 234 are wound around the drum 293, the coil has the second diameter D2 (see FIG. 24). The spool arrangement 290 also includes at least one flange 294 extending between the first and second plates 291, 292 at a position spaced from the drum 293. The fiange 294 is curved to provide bend radius protection for any optical fibers wrapped around an outside of the fiange 294. The fiange 294 is positioned and oriented so that the optical fibers can be wound around the drum 293 and the flange 294 so that the coil has a diameter Dl that is larger than the diameter D2 (see FIG. 23). The difference between diameter Dl and diameter D2 and the number of fiber coils yield an overlength (i.e., slack length) of the optical fibers 234. In some implementations, the fiber overlength may be about 5-50 cm. In certain implementations, the fiber overlength may be about 10-40 cm.
The flange 294 is configured to release the optical fibers 234 wound around the flange 294 so that the optical fibers 234 may coil more tightly around the drum 293. In some implementations, the flange 294 or a portion thereof is formed out of a deformable material (e.g., rubber) so that the flange 294 or portion thereof deforms (e.g., bends, folds, squishes, etc.) inwardly to enable the fibers 234 to slide over the flange 294 and into an interior of the cable spool 290. In certain implementations, a first flange 294a extends from the first plate 291 towards the second plate 292 and a second flange 294b extends from the second plate 291 towards the first plate 291. Distal ends of the flanges 294a, 294b overlap to provide a stable surface about which optical fibers 234 may be wrapped. During an over- pull event, the optical fibers 234 press against the flanges 294a, 294b to deform the flanges 294a, 294b inwardly at the overlap so that the optical fibers 234 may pass between the flanges 294a, 294b and into an interior of the cable spool 290 between the drum 293 and the flange 294. If the fibers are pulled further, the coil of fibers 234 continues to shrink until the coil encircles the drum 293 at the reduced diameter D2.
In other implementations, the flange 294 may includes a hinge 295 or other pivot point so that at least a portion of the flange 294 can be pivoted relative to the parallel plates 291, 292. In certain implementations, the flange 294 may include a hinge 295 at an intermediate point along the height of the fiange 294. The hinge 295 separates the flange
294 into a fixed section 294a and a pivotal section 294b. In the example shown, the hinge
295 is a living hinge. When an over-pull occurs, however, the pivotal portion of the fiange 294 is sufficiently flexible to enable the fibers 234 to pivot the flange 294 or portion thereof
294b inwardly so that the fibers 234 slide over the flange 294 and into an interior of the cable spool 290 between the drum 293 and the flange 294.
In other implementations, the flange 294 may include a hinge 295 at one end of the fiange 294 to connect the flange 294 to one of the plates 291, 292. In such implementations, the opposite end of the flange 294 is free to pivot about the hinge 295. In such
implementations, the pivotal portion of the flange 294 is sufficiently rigid to maintain the optical fibers 234 wound around the drum 293 and flange 294 at the coil diameter of Dl . In still other implementations, the flange 294 includes a weakened region (e.g., a section of reduced material, a perforation, a scored section, etc.) that is configured to bend or deform when compressed by the fibers 234.
In some implementations, the flange 294 is configured to release the fibers 234 upon the application of a force in the range of at least one Newton (N). In certain
implementations, the flange 294 is configured to release the fibers 234 upon the application of a force of at least 3 N. In certain implementations, the flange 294 is configured to release the fibers 234 upon the application of a force of at least 5 N. In certain implementations, the flange 294 is configured to release the fibers 234 upon the application of a force of at least IO N. In certain implementations, the flange 294 is configured to release the fibers 234 upon the application of a force of at least 15 N.
In some implementations, retaining tabs 296 extend inwardly from the two plates
291, 292 to aid in managing the optical fibers 234. For example, the retaining tabs 296 may aid in holding optical fibers wound around the drum 293 and the flange 294 within a periphery defined by the perimeter of the plates 291, 292. In certain implementations, the tabs 296 define slots 297 through which one or more optical fibers 234 may pass to wind the fibers 234 around the drum 293 and flange 294. In the example shown, the tab slots 297 are angled between the two plates 291, 292.
FIG. 25 illustrates another example cabinet 200' including a pull-protection arrangement 300 disposed within the cabinet 200' adjacent a connection region 215. The pull-protection arrangement 300 provides increased retention of the fibers and/or cables to inhibit axial movement of the fibers and/or cables. In certain implementations, the pull- protection arrangement 300 may be used in combination with any of the over-pull mitigation arrangements 240 described herein. In some such implementations, the pull-protection arrangement 300 is disposed between the over-pull mitigation arrangements 240 and the connection region 215.
FIGS. 26-33 illustrate various example implementations of the pull-protection arrangement 300. In general, the pull-protection arrangement 300 has a top 301 (FIG. 33), a bottom 302 (FIG. 33), a front 303 (FIG. 26), a rear 304, a first side 305, and a second side 306. The pull-protection arrangement 300 includes a body 310 and a cover 320. The body 310 includes a base 311 that defines the bottom 302 of the pull-protection arrangement 300. The cover 320 includes a cover plate 321 that defines the top 301 of the pull-protection arrangement 300.
The body 310 includes two or more walls 312 that extend upwardly from the base 311. Each set of adjacent walls 312 defines a channel 313 therebetween extending generally from the first side 305 of the pull-protection arrangement 300 to the second side 306. In the example shown, the body 310 includes seven walls 312 that define six channels 313 extending between the first and second sides 305, 306. In other implementations, however, the body 310 may include a greater or lesser number of walls 312 (e.g., four, five, ten, etc.). In some implementations, the walls 312 extend linearly upwardly. In other
implementations, the open top sections 319 of the walls 312 taper to form a wider top entrance to the channels 313 (see FIG. 33).
The channels 313 have a width W that is sufficient large to enable one or more optical fibers to be routed through the channel 313 (see FIG. 33) while being sufficiently small to provide a frictional force against axial movement of the optical fiber through the channel 313. In one example implementation, the walls 312 are spaced to provide a channel width W of about 3 mm. In other implementations, however, the walls 312 may be spaced to provide a greater or lesser width W (e.g., 1 mm, 2 mm, 2.5 mm, 3.5 mm, 4 mm, 5 mm, etc.). In general, the width W of the channel 313 is based on the diameter of the fibers and/or cables to be retained within the channel 313.
In some implementations, the walls 312 of the body 310 do not extend linearly between the first and second sides 305, 306. Rather, the walls 312 are contoured to include at least one convex section 314. In general, the tortuous path of the channel 313 defined by the contoured walls 312 increases the amount of friction that opposes axial movement of the fibers within the channels 313. The convex section 314 of each channel 313 has a radius R that ranges from about 10 mm to about 50 mm. In certain implementations, the convex section 314 of each channel 313 has a radius R that ranges from about 15 mm to about 40 mm. In certain implementations, the convex section 314 of each channel 313 has a radius R that ranges from about 20 mm to about 30 mm.
In some implementations, additional retaining features 316 may be added to the walls 312 to increase the frictional force applied to the fibers or otherwise aid in inhibiting axial movement of the fibers within the channels 313. In some implementations, the retaining features 316 are configured to apply a clamping pressure to the fibers to inhibit axial movement of the fibers. In other implementations, the retaining features 316 do not apply pressure, but simply provide an additional friction force to be overcome to slide the fibers axially within the channels 313.
For example, in FIG. 29, detents 316a protrude into the channels 313 towards the fibers. In the example shown, the detents 316a are rounded. In certain implementations, the detents 316a are disposed on fingers 315 extend outwardly from the first and second sides 305, 306 of the walls 312. In other implementations, the detents 316a may be disposed on the walls 312. In certain implementations, the detents 316a are located at the ends of the channels 313. In other implementations, the detents 316a are spaced along the lengths of the channels 313. In certain implementations, the fingers 215 are configured to flex forwardly and rearwardly relative to the walls 312. Providing the detents 316a on flexible fingers 315 enables the body 310 to accommodate optical fibers of varying sizes.
FIG. 30 shows a body 310' having other example types of retaining features 316 suitable for use with walls 312. Typically, each body 310 would use the same retaining feature 316 for each channel 313. In some implementations, however, different types of retaining features 316 may be used on the same body 310. For example, one or more tabs 316b may extend upwardly from the base 311 and into each channel 313. In the example shown, a tab 316b extends upwardly at the first and second ends of one of the channels 313. In other implementations, multiple tabs 316b may extend upwardly along the length of each channel 313. In still other implementations, one or more tabs 316b may extend downwardly from the cover 320.
FIG. 30 also shows walls 312 having one or more teeth 316c protruding into the channels 313 towards the fibers. In certain implementations, each tooth 316c is sufficiently sized and sufficiently sharp to cut into a buffer tube surrounding an optical fiber routed through the respective channel 313. In certain implementations, two opposing teeth 316b protrude inwardly from opposite sides of a channel 313. In the example shown, the teeth
316b are disposed on the walls 312 at either end of a channel 313. In other implementations, the teeth 316b may be disposed along the length of the respective channel and/or on flexible fingers 315 extending outwardly from the walls 312. In still other implementations, the walls 312 may define a straight slot at the end of each channel 313 (e.g., see the left-most channel 313 of FIG. 30).
In some implementations, the fibers may be secured within the channels 313 by the cover 320. The cover 320 includes a cover plate 321 that defines ribs 322, 323 extending downwardly from a bottom 302 of the cover plate 321. The ribs 322, 323 are sized and shaped to fit into the channels 313 of the body 310 when the cover 320 is disposed on the body 310. In the example shown, the cover plate 321 includes a central column of ribs 322 disposed between two side columns of ribs 323. In other implementations, the cover plate 321 includes a continuous rib for each channel 313 of the body 310.
In certain implementations, the top 301 of the cover plate 320 includes a labeling region at which indicia may be disposed to identify the channels 313 of the body 310 or fibers laid therein. In the example shown, the cover plate 320 includes a label platform 324 for each channel 313 of the corresponding body 310. Ribs 325 extend outwardly from the label platform 324 to the opposite ends of the channels 313 to identify which label platform 324 corresponds with which channel 313. In certain implementations, the label platforms 324 are raised above the top surface of the cover plate 321. In other implementations, the label platforms 324 are recessed into or flush with the top surface of the cover plate 321.
In some implementations, the body 310 and the cover 320 are configured to releasably secure together. In certain implementations, the cover 320 is pivotally coupled to one end of the body 310. In other implementations, however, the cover 320 may be snap-fit, friction- fit, tethered, latched, or otherwise releasably secured to the body 310. In certain implementations, the cover 320 is configured to move relative to the body 310 while remaining attached to the body 310. In the example shown, the body 310 includes hinge members 317 and the cover 320 includes a hinge member 327 that fits between the hinge members 317 of the body 310. Hinge pins are inserted through the hinge members 317, 327 to enable the cover 320 to pivot relative to the body 310.
In some implementations, the cover 320 moves between a closed position and an open position. When in the closed position, the cover 320 inhibits access to the channels 313 of the body 310 from the top 301 of the pull-protection arrangement 300. When in the open position, the channels 313 are accessible from the top 301 of the pull-protection arrangement 300. In some implementations, the cover 320 may be releasably secured in the closed position. For example, the cover 320 may be latched to the body 310. As shown in FIG. 28, the body 310 includes a lug 318 having an upper ramped surface and a lower shoulder. The cover 320 includes a downwardly protruding flange 328 that is generally aligned with the lug 318 of the body 310 when the cover 320 closed. The flange 328 defines a through-hole 329 sized to receive the lug 318 when the cover 320 is closed relative to the body 310.
FIG. 33 is a side elevational view of an example body 310" of another example pull- protection arrangement 300. The body 310" includes walls 312 that define six channels 313 through which optical fibers 324 may be routed. In the example shown, six fibers 324 are routed through each channel 313. In other implementations, however, a greater or lesser number of fibers 324 (e.g., one, two, three, eight, ten, etc.) may be routed through each channel 313. The body 310 " includes one or more hinge member 317 at which a corresponding cover may be coupled to the body 310 " . The body 310 " also includes a mounting base 340 that is structured to facilitate mounting the pull-protection arrangement 300 to a cabinet 200'. In the example shown, the mounting base 340 includes a snap-fit lug 345 configured to extend into an aperture in a cabinet surface. In other implementations, the mounting base 340 is otherwise configured to secure the body 310" to a surface in the cabinet 200'.
In some implementations, a user may lift one or more fibers 234 out of the open top
319 of the channels 313 to remove the fibers 234 from the pull-protection arrangement 300. In these or other implementations, a user may pull one or more fibers 234 axially out of one or more of the channels 313 to remove the fibers 234 from the pull-protection arrangement 300. For example, the structure of any of the above-described pull-protection arrangements 300 may slow axial movement of an optical fiber 234 through one of the channels 313.
Slowing the axial movement will inhibit significant axial movement of the fibers 234 during a short over-pull event.
By still allowing the fibers 234 to be axially moved through the channels 313, however, a user may remove a fiber 234 from a pull-protection arrangement 300 without lifting any other fibers (e.g., fibers stacked on top of the fiber to be removed) out of the pull- protection arrangement 300. For example, a broken or otherwise damaged optical fiber 234 may be removed by cutting the fiber 234 at one end of the pull-protection device 300 and slowing pulling the optical fiber 234 through the channel 313 from the other end of the device 300. The ability to remove one fiber from an intermediate or bottom portion of the fiber stack without moving any of the other fibers in the stack protects the other optical fibers 234 from damage during the removal process.
FIG. 34 illustrates one example cabinet 200' in which a plurality of splice cassettes 216 are disposed at a connection region 215 and speedpipes 232 are routed into the cabinet 200 through one or more cable ports 210. One or more blown optical fibers 234 pass through the speedpipes 232 at a transition region 212 of the cabinet 200. The optical fibers 234 are routed around the cabinet 200 to the trays 216 at which the optical fibers 234 are connected together. For example, one or more of the optical fibers 234 may form a feeder cable and two or more of the optical fibers 234 may form one or more subscriber cables. A pull-protection arrangement 300 may be disposed within the cabinet 200 to inhibit pulling of the fibers 324 away from the trays 216 at the connection region 215. In general, the pull-protection arrangement 300 is disposed adjacent the connection region 216. For example, the pull-protection arrangement 300 may be disposed next to a strain-relief device disposed at the connection region 216. In certain implementations, multiple pull-protection arrangements 300 are disposed within the cabinet 200'. In the example shown, two pull- protection arrangements 300 are disposed at an entrance/exit of the connection region 215.
As shown in FIG. 34, one or more pull-protection arrangements 300 may function in cooperation with one or more over-pull mitigation arrangements 240. In such
implementations, the pull-protection arrangements 300 are disposed between the more over- pull mitigation arrangements 240 and the connection region 215.
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.
Parts List
100 optical network
110 central office 110
115 end subscribers
105 conduit
130 fiber distribution hubs
125 breakout locations
200, 200' enclo sure/ cabinet
210 cable port
215 connection region
216 cassettes
220 conduit
230 cable
232 speedpipes
234 optical fibers
240 over-pull mitigation arrangement
250 first example over-pull mitigation arrangement
251 retainer
252 retainer body
253 channel
254 walls
255 curved surfaces
256 seam
257 slot
258 holding tab
259 latching tab
260 front side
261 rear side
262 first side
263 second side
264 top
265 bottom
270 second example over-pull mitigation arrangement
271 retainer 272 retainer body
273 channel
274 walls
275 curved surfaces
276 seam
277 fingers
278 first ramped surface
279 second ramped surface
280 front side
281 rear side
282 first side
283 second side
284 top
285 bottom
290 spool arrangement
291 first plate
292 second plate
293 drum
294 flange
294a fixed section
294b pivotal section
295 hinge section
296 retaining tab
297 slot
300 pull-protection arrangement
301 top
302 bottom
303 front
304 rear
305 first side
306 second side
310, 310' body
311 base
312 walls 313 channel
314 convex section
R radius
W width
315 fingers
316 retaining feature
316a rounded tabs
316b tabs
316c cutting teeth
317 hinge members
318 lug
319 top section of channels
320 cover
321 cover plate
322 ribs in central column
323 ribs in side column
324 label platforms
325 ribs
327 hinge member
328 flange
329 through-hole