Duct closures and methods of sealing ducts using the same

Duct closures include a first member and a second member. The first and second members are configured to define a cavity therebetween when in a closed position. A hinge on a first end of the first member and the second member pivotally connects the first member and the second member for movement between the closed position and an open position. A duct mating region on a second end of the first and second members, opposite from the first end, is configured to define a duct receiving opening receiving and sealingly engaging an outer surface of a duct having longitudinally extending members extending therefrom. A plurality of openings to the cavity are defined by the first and second members on the first end and sized to receive ones of the longitudinally extending members extending therethrough. A sealant material positioned in the cavity environmentally seals the openings with the ones of the longitudinally extending members extending therethrough.

BACKGROUND OF THE INVENTION

The present invention relates to optical fiber products and, more particularly, to optical fiber storage products and methods for using the same.

Optical fiber networks are increasingly being installed to support high-speed voice and data communications. Increasingly, the optical fiber coupling is being expanded out from the central office of the communication service provider companies, such as Regional Bell Operating Companies (RBOCs) to the subscriber locations, such as homes or businesses, where conventional copper wiring was conventionally used. Such alternate methods of providing bandwidth to subscriber locations are often referred to in the telecoms industry as Fiber to the Home FTTH)

Conventional methods for distributing optical fiber cables to customers on a Passive Optical Network (PON) include the form of an overhead distribution network, where the end distribution fiber cables are supported on poles, and/or an underground distribution network, where optical fiber cables extend through ducts between local manhole access points. At the access points, subscribers are provided access through splicing into a main cable from a central office, generally through a drop cable coupled to the main cable at the manhole or other access point.

SUMMARY OF THE INVENTION

Embodiments of the present invention include duct closures including a first member and a second member. The first and second members are configured to define a cavity therebetween when in a closed position. A hinge on a first end of the first member and the second member pivotally connects the first member and the second member for movement between the closed position and an open position. A duct mating region on a second end of the first and second members, opposite from the first end, is configured to define a duct receiving opening receiving and sealingly engaging an outer surface of a duct having longitudinally extending members extending therefrom. A plurality of openings to the cavity are defined by the first and second members on the first end and sized to receive ones of the longitudinally extending members extending therethrough. A sealant material positioned in the cavity environmentally seals the openings with the ones of the longitudinally extending members extending therethrough. The sealant material may have, for example, an elasticity selected to provide a re-enterable environmental seal, such as a gel and/or rubber.

In further embodiments, the seal material includes a portion thereof in the duct mating region that is shaped to sealingly engage a range of diameters corresponding to an outer diameter variability of the duct without removing any of the sealant material. The portion of the sealant material in the duct mating region may be shaped to define at least one annular ring extending radially from a base sealant material portion to a height selected to accommodate the outer diameter variability. A height of the base sealant material portion may be selected to environmentally seal a duct having an outer diameter of about 1.25 inches and a sum of the height of the base sealant material portion and the height selected to accommodate the outer diameter variability may be selected to environmentally seal a duct having an outer diameter of about 1.5 inches.

In other embodiments, the duct mating region on the second end of the first and second members includes an attachment region extending around the second end configured to receive a connector that secures the first and second members to the duct. The attachment region includes flexible members at a first interface region and at a second interface region where the first and second members contact when the duct closure is attached to the duct. The flexible members are configured to be displaced towards the duct when the duct closure is attached to the duct by the connector so that the flexible members displace respective underlying portions of the sealant material to facilitate sealing between the duct and the first and second members in the first and second interface regions. The attachment region may further include a connector retaining member configured to retain the connector.

In further embodiments, the connector retaining member includes a first retaining member positioned proximate the flexible member at the first interface region and a second retaining member positioned proximate the flexible member at the second interface region. The first retaining member and the second retaining member each include an opening configured to receive a longitudinally extending connector. The flexible members may be circumferentially extending cantilevered segments of the first and/or second member. The attachment region may further include mating snap connection members on the first and second members that mechanically connect the first and second members around the duct in the closed position.

In other embodiments, the plurality of openings includes a first opening having a first diameter and a plurality of second openings having diameters that are less than the first diameter. The second openings may be non-circular openings, having a width along an axis defined by the hinge shorter than a length along an axis extending perpendicular to the axis defined by the hinge, that are configured to receive a flat drop optical fiber cable. The hinge may include a plurality of discrete hinge elements displaced from each other along the axis defined by the hinge and the first opening and the second openings may be positioned in a non-overlapping relation with the hinge elements along the axis defined by the hinge so that the hinge elements do not interfere with passage of cables inserted in the first and second openings. Ones of the discrete hinge elements may include a first hinge portion on the first member and a mating second hinge portion on the second member, where the first and second hinge portion are configured for detachable engagement therebetween and the duct closure is a wrap around closure.

In further embodiments, a portion of the sealant material in the cavity proximate the first and second openings is shaped to sealingly engage a range of different diameters of longitudinally extending members extending through the first and second openings without removing any of the sealant material. The portion of the sealant material in the cavity proximate the first and second openings may include a void region associated with each of the first and second openings.

In yet other embodiments, a wrap around fiber optic duct closure includes a first member and a second member. The first and second members are configured to define a cavity therebetween when in a closed position. A hinge on a first end of the first member and the second member detachably pivotally connects the first member and the second member for movement between the closed position and an open position. The first and second members have mating snap connection members that mechanically connect the first and second members around a duct in the closed position. A duct mating region on a second end of the first and second members, opposite from the first end, is configured to define a duct receiving opening that wraps around an outer surface of the duct in the closed position, the duct having fiber optic cables extending therefrom. A plurality of openings to the cavity are defined by the first and second members on the first end and sized to receive ones of the fiber optic cables extending therethrough. A gel positioned in the cavity environmentally seals the openings with the ones of the longitudinally extending members extending therethrough. A first portion of the sealant material in the cavity proximate the first and second openings is shaped to sealingly engage a range of different diameters of fiber optic cables extending through the first and second openings without removing any of the gel. A second portion of the sealant material in the duct mating region is shaped to define at least one annular ring extending radially from a base sealant material portion to a height selected to accommodate outer diameter variability of the duct. The first and second members are configured so that rotation to the closed position over the end of the duct with the fiber optic cables passing through the plurality of openings to the cavity on the first end applies pressure to the gel in the first and second portions. A greater pressure is applied by rotation to the closed position in the first portion than the second portion.

In other embodiments, the duct mating region on the second end of the first and second members includes an attachment region extending around the second end configured to receive a connector that secures the first and second members to the duct. The attachment region includes flexible members at a first interface region and at a second interface region where the first and second members contact when the duct closure is attached to the duct. The flexible members are configured to be displaced towards the duct when the duct closure is attached to the duct by the connector so that the flexible members displace respective underlying portions of the gel to facilitate sealing between the duct and the first and second members in the first and second interface regions.

In yet further embodiments, methods of environmentally sealing a duct include providing a duct closure including a first member and a second member having receiving openings in a first end thereof, which members are detachably pivotally connected by a plurality of mating hinge elements at the first end for movement between an open position and a closed position and configured to wrap around an outer surface of a duct at a second end, opposite the first. The first member is placed on the duct proximate an end of the duct with the second end of the first member contacting the outer surface of the duct. Ones of a plurality of longitudinally extending members exiting from the end of the duct are routed through respective ones of the receiving openings in the first end. The mating hinge elements of the first and second members are coupled with the routed longitudinally extending members positioned between the first and second members. The second member is rotated about an axis defined by the mated hinge members to the closed position. The first and second members are coupled at the second end wrapped around the outer surface of the duct. A sealant material is positioned between the first and second members and the outer surface of the duct and the longitudinally extending members and rotating the second member and coupling the first and second members environmentally seals the end of the duct with the longitudinally extending members extending therefrom.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Some embodiments of the present invention provide a device for sealing the end of a duct containing multiple fiber optic cables, or any other similarly sized cables. Typical ducts are between 1 and 3 inch in outer diameter and are constructed with a polyethylene wall thickness of roughly 3/16 inch. These ducts are typically placed underground with pulling tape inside (Mule tape) and then, at a future date, the pulling tape is used to pull lengths of cable into the duct. It is generally desirable to limit or even prevent debris and water from entering the duct both before and after the cables are pulled. For this purpose, duct sealing devices may be employed at the points where the duct enters and exits the ground and is exposed to water ingress.

Some embodiments of the present invention, provide fiber optic duct plugs and methods of using the same that may serve the purpose of sealing the duct, either without cables or when the duct contains numerous cables of, for example, various shapes (e.g., round feeder cable, and/or flat drop distribution cable), and the pulling tape.

In some embodiments, the ducts are small and may have numerous cables inside them, which may occupy a large percentage of the space inside the duct. Because of this limited inside space, it is generally difficult to make traditional duct plug devices that seal the cables to the inside wall of the duct. There is typically not enough space between the cables and the inside wall of the duct to insert a sealing member. Therefore, some embodiments of the present invention provide an apparatus that seals the cables to the outside of the duct as illustrated inFIGS. 1-5.

As will be described with reference to the illustrated embodiments, this may be accomplished by enclosing both the end portion of the duct and the protruding cables inside two rigid bodies roughly resembling two halves of a split cylinder with a soft sealing gel inside. This configuration may seal to each individual cable and to the outer surface of the duct.

In some embodiments, at least one of the rigid bodies includes guide members153that guide the cables into a fan shape and location members formed at the exit point(s) of the rigid bodies in at least one of the rigid bodies holds the cable in the fan shape. The inner surface of one or both of the rigid bodies may be covered with an environmental sealant, such as a soft gel sealant material. Note that, for clarity inFIGS. 1-4, the environmental sealant itself is not shown.

In some embodiments, the cables are positioned into the guided orientation in the first rigid body and the second rigid body is then attached to the first rigid body at a first end adjacent the exit point. This attachment may be made by mating connection member features in each of the rigid bodies that interlock. Once interlocked, the two bodies in the illustrated embodiments are rotatably hinged together at the first end and have a closed position in which they enclose the surface of the duct at the second end of the rigid bodies, longitudinally displaced from the first end. The sealing of the cables and the duct may be accomplished by the rigid bodies applying pressure to the gel sealant material in the open areas within the housing defined by the first and second rigid bodies. In the closed position, the housing may apply high amounts of pressure to the cable exit area in particular, due to mechanical advantage when hinging the two halves toward the fully closed position. The two halves in some embodiments are held in the closed sealed position by tightening with a closing member, which may be a band, such as a tie-wrap, at the second end that encloses the duct.

In the case where no cables are present, the gel surfaces in some embodiments seal against each other to seal the device to itself, and to the duct. However, sufficient gel may also be provided in one rigid body to seal to the other rigid body where gel is only provided in one of the rigid bodies.

Duct closures according to some embodiments of the present invention will now be described with reference toFIGS. 1-4. As seen in the embodiments ofFIGS. 1-4, a duct closure100includes a first member110and a second member120pivotally connected thereto. The first and second members110,120are configured to define a cavity121therebetween when in the closed position shown inFIGS. 1 and 2. A hinge122on a first end112of the first and second members110,120pivotally connects the first member110and the second member120for movement between the closed position shown inFIGS. 1 and 2and the open position shown inFIG. 4.FIG. 3shows the first member110positioned proximate an end104of a duct105before the second member120has been pivotally connected thereto.

The duct105, as seen in the embodiments ofFIGS. 1-4, includes a plurality of longitudinally extending members107,107′ extending therefrom. As shown inFIGS. 1-4, the longitudinally extending members107,107′ include a plurality of fiber optic flat drop cables107and a fiber optic main cable107′ having a larger diameter than the flat drop cables107. The duct105may be, for example, a duct installed in an underground location extending between manhole access points, where the duct105is used for routing fiber optic cables107,107′ between respective manhole cover access points in the fiber optic network. It will be understood that it is desirable to prevent dirt, sand or other such debris from passing into the duct105as such particles may, over time, block the duct105and limit the utility thereof. Thus, the duct closure100may provide an environmental seal to the duct105to limit or even prevent the passage of dirt and other particles into the duct105from the access point at the end104of the duct105within a manhole access closure. In some embodiments, it will be understood that the environmental seal may further be able to limit access of water flow into the duct105, either from incidental water falling thereon or, in some circumstances, sufficient sealing to allow immersion of the duct closure100in water while limiting or preventing liquid flow into the duct105. However, it will be understood that, as used herein, reference to an environmental seal or environmental sealing does not require a water-tight seal.

As best seen inFIG. 2, the first member110and the second member120define a plurality of openings132,134extending into the cavity121with the first and second members in the closed position. As best seen inFIG. 2, the openings132,134are sized to receive ones of the longitudinally extending members107,107′ extending from the end104of the duct105. Also seen inFIG. 3are a plurality of guide members153that guide the longitudinally extending members107,107′ into a fan shape.

In the particular embodiments illustrated inFIGS. 1-4, the first opening132has a first diameter and the plurality of second openings134have effective diameters that are less than the first opening diameter. As best seen inFIG. 2, the illustrated embodiments of the second openings134are noncircular openings, having a width along an access A1(FIG. 1) shorter than a length along an access A2(FIG. 1) extending perpendicular to the access A1defined by the hinge122. Such a configuration may be particularly suited for use with a flat drop optical fiber cable such as the cables107illustrated inFIGS. 1-4. The larger opening132may provide clearance for larger diameter cables, such as the fiber optic main cable107′.

As best seen inFIG. 2, for the illustrated embodiments ofFIGS. 1-4, the hinge122includes four discrete hinge elements displaced from each other along the access A1defined by the hinge122. More particularly, each of the discreet hinge elements includes a first hinge portion122aon the first member110and a mating second hinge portion122bon the second member120. The hinge portion122bis shown as including an opening configured to receive the hinge portion122atherein to provide a detachable pivotal connection for movement of the first member110and the second member120between the closed position and the open position. As will be further described herein, such hinging arrangement may facilitate the use of the duct closure100as a wrap-around closure. As also best seen inFIG. 2, the openings132,134are positioned in a non-overlapping relation with the hinge elements along the axis A1so that the discrete hinge elements do not interfere with passage of cables107,107′ through the openings132,134.

A duct mating region114is provided in the second end of the first and second members110,120opposite from the first end112including the hinge122. The duct mating region114defines a duct receiving opening106that receives and sealingly engages an outer surface105aof the duct105. In the illustrated embodiments ofFIGS. 1-4, the duct mating region114includes an attachment region124extending around the second end that is configured to receive a connector that secures the first and second members110,120to the duct105.

As further shown in the illustrated embodiments, the attachment region124may include flexible members142at a respective first interface region154and second interface region156where the first and second members110,120contact when the duct closure100is in the closed position attached to the duct105. The flexible members142are configured to be displaced towards the duct105when the duct closure100is attached to the duct105by the connector so that the flexible members displace respective underlying portions of a sealant material positioned in the cavity121in a region145. (Note that the sealant material location is indicated by the reference numeral145, but the gel itself is not shown so as to allow clearer viewing of the other features in the region.) The flexible members142in the illustrated embodiments are provided by circumferentially extending cantilevered segments of the first member110. The displacement of the flexible members142may displace respective underlying portions of the sealant material to facilitate sealing between the duct105and the first and second members110,120in the first and second interface regions154,156. Thus, the sealant material may provide environmental sealing around the outer surface105aof the duct105as well as environmentally sealing the openings132,134with the longitudinally extending members107,107′ extending therethrough.

For the illustrated embodiments ofFIGS. 1-4, the attachment region124is shown as further including a connector retaining member140configured to retain the connector. More particularly, as best seen inFIG. 4a first retaining member140is shown positioned proximate the flexible member142at the first interface region154and a second retaining member140is positioned proximate the flexible member142at the second interface region156. The first and second retaining members140each include an opening152configured to receive a longitudinally extending connector.

It will be understood that the various features described herein may be positioned on either the first member110or the second member120in various combinations in different embodiments of the present invention, such as the connector retaining members140, the flexible members142and the respective mating hinging elements122A,122B. Thus, the particular arrangement of such mating components is not to be limited to the particular combination illustrated for explanatory purposes inFIGS. 1-4. It will also be understood that, in some embodiments, the connector retaining member140may also function to provide a portion of mating snap connection members140on the first and second members110,120that mechanically connect the first and second members110,120around the duct105in the closed position. Such mating snap connection members will be further described with reference to the embodiments ofFIGS. 5-8, where they are provided as separate from the connector retaining member.

A duct closure200according to further embodiments of the present invention will now be described with reference toFIGS. 5-8. Like numbered reference numerals (e.g.114,214) for the embodiments ofFIGS. 5-8may be substantially as described previously with reference to the embodiments ofFIGS. 1-4except as noted particularly herein.

The duct closure200includes a first member210and a second member220, which are detachably pivotally connected at a hinge222on a first end212of the first and second members210,220. A closed position of the first and second members210,220is shown inFIGS. 5 and 6while an open position, showing various features of an environmental sealant material245in a cavity221defined by the first and second members210,220, is shownFIGS. 7 and 8. The sealant material, shown as a gel145in the embodiments ofFIGS. 5-8, is positioned in the cavity221to environmentally seal openings232,234on the first end212.

The illustrated hinge222in the embodiments ofFIGS. 5-8includes a plurality of discrete hinge elements122a,122bdisplaced from each other along the axis defined by the hinge222. More particularly, the discrete hinge elements include a first hinge portion222aon the first member210and a mating second hinge portion222bon the second member220. The respective hinge portions222a,222bare configured for detachable engagement therebetween to facilitate use of the duct closure200as a wrap around closure.

The openings232,234extend to the cavity221and are configured to receive ones of a plurality of longitudinally extending members extending from a duct to which the duct closure200is applied, such as the duct closure105and the fiber optic cables107,107′ shown inFIGS. 1-4. As further described previously with reference to the embodiments ofFIGS. 1-4, the first opening232may be provided a first diameter larger than an effective diameter of the second openings234. Furthermore, the openings234may be non-circular openings configured to receive, for example, a flat drop optical fiber cable107′.

A duct mating region214is provided on a second end of the first and second members210,220opposite from the first end212. The duct mating region214is configured to define a duct receiving opening206and to sealingly engage an outer surface105aof a duct105with longitudinally extending members107,107′ extending therefrom.

In some embodiments of the present invention, the sealant material, such as the gel245, has an elasticity selected to provide a re-enterable environmental seal. In addition to gel, another example of such a sealant material is a rubber. As best seen in the illustration ofFIG. 8, the gel245includes a first portion460thereof in the cavity221proximate the openings232,234that is shaped to sealingly engage a range of different diameters of fiber optic cables or the like extending through the openings232,234without removing any of the gel245. A second portion480of the gel245in the duct mating region214is shaped to sealingly engage a range of diameters of ducts in some embodiments of the present invention. For example, the second portion480may be configured to engage a range of diameters corresponding to an outer diameter variability of the duct without removing any of the sealant material. By way of further example, fiber optic ducts sold as 1.25 inch diameter ducts typically have an outer diameter specified variability of from about 1.25 inches to about 1.5 inches. In some embodiments, as illustrated inFIG. 8, the second portion480of the sealant material (gel)245in the duct mating region214is shaped to define one or more annular rings482A,482B. The annular rings,482A,482B extend radially from a base sealant material portion extending around the circumference of the duct closure200to a height selected to accommodate the outer diameters variability of the duct.

As also shown in the embodiments ofFIGS. 5-7, the duct mating region214may include an attachment region224extending around the second end that is configured to receive a connector that secures the first and second members210,220to the duct105. The illustrated attachment region224includes flexible members224at a first interface region254a,254band a second interface region256a,257bwhere the first and second members210,220contact when the duct closure200is attached to the duct105in the closed position of the members210,220. The flexible members242are configured to be displaced toward the duct105when the duct closure is attached to the duct105by a connector so that the flexible members242displace respective underlying portions of the gel245to facilitate sealing between the duct105and the first and second members210,220in the interface regions254a,254b,256a,256b.

For the embodiments illustrated inFIGS. 5-8, the attachment region224includes connector retaining members340proximate the respective interface regions254a,254b,256a,256bthat are configured to retain a connector. Each of the respective connector retaining members340is positioned proximate a corresponding one of the flexible members242and each includes an opening352configured to receive a longitudinally extending connector. Furthermore, the embodiments illustrated inFIGS. 5-8include separate mating snap connection members240,241on the first and second members210,220that mechanically connect the first and second members210,220around the duct105in the closed position. The respective snap connection members240on the second member220include openings configured to receive and engage corresponding tabs241on the first member210in the closed position.

Referring again to the gel245in the cavity221, a portion460of the sealant material in the cavity221proximate the openings232,234is shaped to sealingly engage a range of different diameters of longitudinally extending members107,107′ extending through the openings232,234without removing any of the sealant material. More particularly, as best seen in the embodiments ofFIG. 8, the portion460of the gel245in the cavity221proximate the openings232,234in some embodiments includes a void region462,464associated with each of the respective openings232,234. In the particular embodiments shown inFIG. 8, the void462is larger and less longitudinally extending than the voids464, where the void462is configured to receive a larger cable, such as a fiber optic main cable, while the voids464are particularly suited for use with a flat drop cable and define a non-circular cross section void extending through the portion460of the gel245. The respective voids462,464do not, in some embodiments, extend all the way to the openings232,234so that, when longitudinally extending members are not extending through the respective openings, environmental sealing is still provided by the portion460of the gel245closing (environmentally sealing) unused ones of the openings232,234.

Methods of environmentally sealing a duct according to some embodiments of the present invention will now be described with reference toFIG. 9. As shown in the flow chart illustration ofFIG. 9, operations begin by providing a duct closure (block900). As described above with respect to the duct closures ofFIGS. 1-8, the duct closure has receiving openings in a first end thereof defined by first and second members that are detachably pivotally connected by a plurality of mating hinge elements on the first end for movement between an open position and a closed position and configured to wrap around an outer surface of a duct at a second end opposite the first.

The first member is placed on the duct proximate an end of the duct, the second end of the first member contacting the outer surface of the duct (block910). Ones of the plurality of longitudinally extending members exiting from the end of the duct are routed through respective ones of the receiving openings in the first end (block920). Such an arrangement is illustrated, for example, by the fan out arrangement shown inFIG. 3.

The mating hinging elements of the first and second members are coupled with the routed longitudinally extending members positioned between the first and second members (block930). Such an arrangement is illustrated, for example, inFIG. 4. The second member is rotated about an axis defined by the mated hinge members to the closed position illustrated, for example, inFIGS. 1 and 2(block940). The first and second members are coupled at the second end that is wrapped around the outer surface of the duct (block950). A sealant material, such as a gel, is positioned between the first and second members and the outer surface of the duct and the longitudinally extending members and rotating the second member and coupling the first and second members environmentally seals the end of the duct with the longitudinally extending members extending thereform. More particularly, rotation to the closed position over the end of the duct with cables or the like extending therefrom applies pressure to the gel in the respective first and second gel portions to aid in environmental sealing. In some embodiments, using a hinged arrangement at the first end as described above, a greater pressure may be applied by rotation to the closed position in the first portion proximate the hinge and the exiting cables than the force applied in the second portion environmentally sealing to the outer surface of the duct. Such a greater pressure application, which may require little additional operator force as a result of the hinging arrangement pivoting about the end proximate the cable exit point, may facilitate effective environmental sealing about the more complex and potentially variable geometry of the respective cables to provide an effective environmental seal across a range of different cable sizes and shapes in some embodiments of the present invention.