Optical branching and termination box

The box comprises a base (10) hinging a lid (20) and a tray (40) carrying fiber splicing and splitting means (AF, EF) and output adapters (AS). A side opening (13) of the base (10) is closed by a sealing bung

FIELD OF INVENTION

The present invention relates to an optical cable termination and drop (splitter) box, to be applied to aerial fiber optic networks called FTTH (“fiber to the home”), to protect an optical splice (“splitter”) between an optical fiber of a multi-fiber distribution cable received in the box and multiple optical terminal cables (“drop” cables), usually in the form of compact (“low friction”) cables, and/or optical splices by fusion between one or more optical fibers of the distribution cable and a respective drop optical cable (continuation multifiber optical cable).

BACKGROUND OF THE INVENTION

Fiber optic networks require the provision of splicing points and termination points, user activation points, which are protected by termination and drop boxes, usually installed externally, overhead and fixed on the strand, on a pole or on the facade of a building.

In a splice point, for example, one or more fibers of a distribution cable, received in a termination/drop box, are fused to the respective fibers of a drop cable that leaves the box to reach a new splice point or a user activation endpoint.

However, at a user activation point, one of the fibers of the optical drop cable arriving at an aerial termination box is submitted to a splitter to provide terminal cables directed to end users of the network. The fibers of the drop optical cable that arrive at a termination box but are not connected to a respective terminal cable (“drop” cable) can pass through the box unmodified, or be spliced to a new continuation cable length to proceed to a new splice point or user activation point.

These termination boxes must be constructed to accommodate at least one multifiber distribution cable, and to allow the exit of one or more drop cables and a plurality of compact “drop” cables, requiring internal accommodation for splitter splices and drop cables.

A problem with these boxes is the risk of damage to the compact terminating cables already installed in them during optical network maintenance operations, when the installer needs to move the internal fiber accommodation elements in the box, often causing undue bending of the terminating compact optical cables and even damaging the connection adapters of these terminating cables, which need to be disconnected from the adapters so that the installer has access to the fiber fusion areas.

To reduce these risks, termination boxes have been proposed with the internal elements for accommodation of the compact terminal cables physically separated from the internal elements for accommodation of the multifiber drop cables, considering that the installers of multifiber drop cables are responsible for the fiber fusion operations, while the installers of compact terminal cables are responsible for the operations of connection of these cables to the respective adapters provided inside the box and connected to the splitter.

With the physical separation of the referred accommodation elements, each installer has his respective work area separated from the other's work area, reducing the possibility of a team damaging the other's work.

Despite minimizing the aforementioned risks of damage and reducing the number of costly calls/attendances for maintenance of the multifiber drop cable network or compact terminal cables, this well-known solution of physical separation of the cable accommodation elements is complex and costly.

Yet another deficiency of the known termination and drop boxes is related to the sealing solutions employed in them, which have their degree of tightness high in conjunction with their constructive complexity and consequent production costs. In some solutions, the constructive simplification leads to deficiencies in the degree of tightness of the sealing rings (grommets) at the cable entries and exits, allowing the entry of humidity and insects inside the box. In other solutions, the increase in the degree of tightness is obtained with high constructive complexity and undesirable production costs.

The known termination boxes have yet another drawback which results from the fact that they allow the lid to be closed even if the installer has not anchored the compact terminating cable (drop cable) correctly, allowing in this case the compact cable and consequently the data transmission network to be susceptible to undesirable movements and even unacceptable by the standards in force.

Examples of termination boxes of the type considered here can be found in U.S. Pat. Nos. 6,226,434, and 9,310,579.

In view of the above-mentioned drawbacks, a termination box and derivation box for the derivation of the type considered herein was proposed by the present applicant in their patent application BR 10 2018 005815-0, a termination and drop box for optical access networks, of aerial installation, presenting a relatively simple construction, with reduced number of parts, of easy and safe handling of the fiber splicing elements by the respective team of installers, without interference in the connection elements of terminal cables to be handled by another team of installers, this box also being equipped with a high degree of watertightness and double sealing system, acting on the distribution cables, the drop cables (continuation) and the terminal cables, and allowing the containment of large water jets in a first stage, as well as droplets and small insects in a second stage, with drainage between the two stages.

It happens that the said box, object of patent application BR 10 2018 005815-0, is designed to be assembled only in a horizontal position, with the cable entry and exit openings positioned on the opposite sides of a box base, on whose lower horizontal edge a lid is hinged. This former construction does not allow the box to be mounted in a vertical position.

Another particular aspect of the construction of the aforementioned anterior box of the same applicant concerns the large number of sealing elements in elastomer, of relatively complex and costly construction, to provide the tightness, individually and in double level, of the passage of each distribution or drop cable (continuation) through the respective lateral opening of the box and also a pair of sealing elements for the exit of the terminal cables (“drop”) in each of the sides of the optical box.

SUMMARY OF THE INVENTION

Considering the aspects discussed above, the present invention has as its objective the provision of a termination and drop box for optical access networks, of aerial installation and presenting a simple, versatile construction at a substantially lower cost than similar boxes, with a reduced number of sealing elements for obtaining a desired degree of tightness and allowing its installation in the horizontal or vertical position on the cordage or wall of a building or even in the vertical position, also ensuring an easy and safe handling of fiber splice elements by the connecting elements of terminal cables to be handled by another team of installers, regardless of the installation position of the box.

Yet another object of the invention is to provide an aerial installation optical termination and drop box as mentioned above and which ensures the correct anchoring of the terminal cables (“drop” cables) when closing the lid.

The termination and drop box in question is of a type comprising: a base having a bottom wall and a leading edge defined by peripheral walls; a lid having a top wall and a trailing edge defined by peripheral walls and being movable between a closed position, seated and locked against the base, and an open position; and a tray hinged to the base and having a rear face carrying means for accommodating fiber extensions and fiber splicing and splitting means (“splitters”), and a front face carrying output adapters connected to fiber extensions and to respective connectors of a terminating cable, the tray being angularly displaceable between a first position, with its rear face seated against the base, and a second position with its rear face exposed to the installer.

According to the invention, a peripheral wall of the base, not hinged to the lid, is provided with a single lateral opening, defining a recessed extension of the anterior edge of the base and having its cross-section, not occupied by an optical cable, closed by an elastomer sealing bung and presenting a recessed anterior region.

The tray incorporates, on its front face and in a single piece, a lateral anchoring element, in the shape of a channel, having anterior edges provided with anchoring cutouts and posterior edges seated on the sealing bung, inside the recessed anterior region, when the tray is taken to the first seated position on the base, the lateral anchoring element receiving, on its anterior side, the fitting of a sealing element, in elastomer and provided with anterior slots aligned with the anchoring cutouts of the lateral anchoring element, each anterior slot and each pair of anchoring cutouts, aligned among themselves, receiving the tight fitting of an end cable and being a back edge extension of a peripheral lid wall, seated against the sealing element, in order to compress, the latter, around a respective end cable, said peripheral lid wall presenting another back edge extension, more internal and forcing said end cable into the confronting anchoring cutout, when closing the lid.

The construction summarized above is simple, versatile and low cost, and can be installed horizontally or vertically, ensuring easy and safe handling of the fiber splice elements by different teams of installers and ensuring the correct anchorage of the terminal cables (drop cables) when closing the lid.

DESCRIPTION OF THE INVENTION

As illustrated in the drawings and mentioned above, the optical termination and drop box in question comprises a base10and a lid20hinged to the base10, both made of non-electrically conductive material, with the base10incorporating, in one piece, a back wall11(FIGS.2,4and5) and peripheral walls12and defining at least one anterior edge12a, preferably multiple anterior edges12a, which define, between themselves, a rail12b. One of the peripheral walls12, not hinged to the lid20, is provided with a single lateral opening13(FIG.5), defining a recessed extension of the anterior edge12aof the base10, for passage of multi-fiber optical cables CO, which may be defined by a multi-fiber distribution cable or by one or more multi-fiber drop cables.

The cross-section of the lateral opening13, not occupied by a multifiber optical cable CO passing through said lateral opening13, is closed by an elastomer sealing bung30, fitted into said lateral opening13and featuring a recessed anterior region31, the function of which will be described later.

According to the illustrated construction, the elastomer sealing bung30is medially and subsequently provided with a groove32(FIG.8) into which a rib15is embedded, longitudinally and medially, along at least part of the recessed extension of the anterior edge12aof the base10, which defines the lateral opening13. With this, the elastomer sealing bung30is solidly retained in the anterior edge12aof the base10.

According to the invention, the elastomer sealing bung30is provided with transverse holes33,34presenting one or more diametrical patterns, wherein the transverse holes33,34of different patterns in the illustrated example, present one end closed by a respective breakable side wall portion35of the elastomer sealing bung30(FIG.7). Thus, it is sufficient that said breakable side wall portion35be easily removed to allow a multi-fiber optical cable CO to pass through the respective transverse hole33,34to enter or exit the box.

To ensure an adequate degree of tightness between the elastomer sealing bung30and each multi-fiber optical cable CO, passing through the elastomer sealing bung30, each transverse hole33,34has at least part of its length having a smaller diameter than the multi-fiber optical cable CO.

The lid20has a top wall21and peripheral walls22defining at least one and preferably multiple back edge extensions22a, which define between them, a lid rail22b, the lid20being hinged to the base10, preferably on a peripheral wall12of the latter, devoid of the lateral opening13, to be movable between an open position (FIGS.3and4), with its back edge extension22aaway from the anterior edge12aof the base10, to allow access to the interior of the box by the operator/installer of the fiber optic network, and a closed position (FIGS.1,2,7and8), locked to the base10and in which the anterior edges12aand back edge extensions22a, of the base10and the lid20, in the region devoid of the lateral opening13, are seated together and preferably fitted together forming a sealing labyrinth.

In the illustrated construction, the back edge extension22aof the lid20presents the form of a small channel into the interior of which a sealing gasket24(FIGS.3,4,7and8), in the form of a bead of elastomer material, provides tightness in the seating region between the base10and the lid20.

The optical termination box further comprises a tray40having an edge hinged to the base10and presenting a rear face41and a front face42, the tray40being angularly movable between a first position, with its rear face41seated on the base10above the lateral opening13and exposing the front face42to the multi-fiber optical cable CO installer, and a second position in which it exposes the rear face41to the terminal cable CT installer.

The tray40incorporates, on its front face42and in one piece, a channel-shaped lateral anchoring element45having anterior edges45aprovided with anchoring cutouts45band posterior edges45cseated on the elastomer sealing bung30inside the recessed anterior region31of the latter when the tray40is brought to the first position seated on the base10. The lateral anchoring element45is fitted with an elastomer sealing element50and provided with anterior slots51aligned with the anchoring cutouts45bof the lateral anchoring element45. The anterior slots51extend from a side face of the elastomer sealing element50, facing out of the box, to an opposite, breakable side wall52which closes the adjacent end of the set of anterior slots51. Upon engagement of a terminal cable CT in one of said anterior slots51, the respective portion of the opposite, breakable side wall52is broken off and removed. This arrangement ensures that the unused previous slots are sealed.

With the above construction, each anterior slot51of the elastomer sealing element50and each pair of anchoring cutouts45b, aligned with each other receives the tight fit of a terminal cable CT, promoting adequate axial retention of the latter and further adequate tightness between each terminal cable CT in the elastomer sealing element50.

In the illustrated construction, a back edge extension22aof a peripheral wall22of the lid20is seated against the elastomer sealing element50, compressing the latter around a respective terminal cable CT, wherein the peripheral wall22of the lid20presents yet another back edge extension22a, further inward and forcing said terminal cable CT into the confronting anchoring cutout45bupon closure of the lid20. This construction ensures the correct anchoring of the terminal cables CT upon closure of the lid20.

The tray40incorporates, on its rear face41, fiber extension accommodation means AF, fiber splicing means EF, a fiber splitting element (“splitter”) SF, and connectors C receiving optical fibers FO split from a fiber derived from a multi-fiber optical cable CO. The front face42of the tray40carries angularly scalable output adapters AS to each receive the fit of a respective connector C of a terminal cable CT.

With the provision of a single tray40hinged to the base10, it is possible for an installation crew to perform fusion splicing and further splitting of an optical fiber FO using the rear face41of the tray40which may define a kind of horizontal table, when mounting the box on a string or building, with the hinge of the lid20arranged horizontally. However, when mounting the box with the articulation axis of the lid20in a vertical position, the rear face41of the tray40remains in a vertical plane when the tray40is moved to its second position illustrated inFIG.4. In this case, the optical splicing or splitting team can simply move the tray40to its second position and work on the rear face41without risk of producing damage to the connections of the terminal cables CT arranged on the front face42of the tray40.

To facilitate working on the rear face41of the tray40when the box is installed vertically, the base10incorporates, in the region of its peripheral wall12of lid20, a pair of coupling means16(FIGS.4,5and8) in which are hinged, removably by elastic deformation, a corresponding pair of articulation tabs46(FIGS.5A and6) incorporated in an edge of the tray40adjacent to the articulation axis of the lid20. This enables the operator/installer to detach the tray40from the base10in order to work on either side of the tray40on a work platform mounted, in an elevated manner, adjacent to a string, a building wall or even a pole. This feature is particularly useful when the box is mounted vertically.

As illustrated inFIGS.1,23, and4, the back wall11of the base10is usually arranged in a vertical mounting plane to remain mounted to a ropeway (not illustrated) by means of suspension hooks18, removably attached to the base10and which can take different constructions, such as that illustrated exemplarily.

However, the suspension hooks18may be suppressed when the box has the outer face of the back wall11of the base10fixed, directly against a building wall, with a hinge axis vertically or horizontally, by means, for example, of screws (not illustrated) passing through side tabs17incorporated laterally and externally into the base10, or against a pole with the hinge axis of the lid20disposed vertically.

When mounting the box on a pole, a concave cradle60illustrated inFIGS.2,7is provided and is externally and removably attached to the back wall11, of the base10, by screws61, attachable in watertight housings provided in said back wall11, or by other suitable removable attachment means, said concave cradle60provided with pairs of side openings62, opposed two by two, for the passage of straps (not shown) for tying the box to a pole.

Particularly when mounting the box with the hinge of the lid20horizontal, the tray40can be stabilized in its second position by partially seating it against a peripheral wall22of the lid20, adjacent to its articulation to the base10, the lid20being in an open position coplanar to and pendent from the base10.

In the illustrated exemplary configuration, the tray40has its rear face41covered by a film70, in flexible polymeric material, for protecting the optical fiber fusions, and on the front face42of the tray40is mounted a complementary lid47partially covering the angularly scalable output adapters AS and a reserve region of optical fiber extensions derived from the fiber splitting element (“pig tails”) and connected to the angularly scalable output adapters AS. Between the front face42of the tray40and the lid20is provided a sealing tape80, in elastomer, flexible or not, for protecting the connections of the terminal cable CT connectors to the respective angularly scalable output adapters AS, as illustrated inFIG.5.

In the illustrated construction, the base10incorporates, internally, a locking tab19, elastically deformable from an operative position, in which it locks the tray40in its first position seated on the base10, to an inoperative position, in which it releases the angular displacement of the tray40from its first position to its second position.

In a particular construction of the invention, the lid20is locked to the base10by a T-lock carried by a peripheral wall12of the base10, opposite to that hinging the lid20to the base10and moveable between an open position and a closed position, in which it latches, to each other, confronting peripheral walls12of the base10and the lid20. It is to be understood that the T-lock may also be mounted via hinge to a peripheral wall22of the lid20, to act against the base10when closing the optical termination box.

Although only one configuration of the optical termination and drop box in question has been illustrated here, it is to be understood that changes may be made in the shape and arrangement of the components, without departing from the constructive concept defined in the claims accompanying this report.