Fiber optic cable retention

A fiber optic cable retention module includes a housing with a base. A first section extends from the base and defines a pocket for receiving strength members of a fiber optic cable. A second section extends from the base and defines slots that receive a retention member having a generally U shaped frame. The frame has first and second arms extending therefrom that define a cable receiving slot therebetween.

BACKGROUND

The present disclosure relates generally to fiber optic cable systems.

Fiber optic communication systems are becoming prevalent in part because service providers want to deliver high bandwidth communication capabilities (e.g., data and voice) to customers. Fiber optic communication systems employ a network of fiber optic cables to transmit large volumes of data and voice signals over relatively long distances. Fiber management is an important part of operating and maintaining an effective fiber optic communication system.

Optical fibers are often connected to one another via splices. For example, a trunk or main cable may be routed to an area to which service is to be provided and small fiber count “drop cables” may be spliced to the main cable at predetermined spaced apart locations. Splices are often supported within splice enclosures to protect the spliced connections from the environment. The fiber optic cable is typically secured to the enclosure, for instance by removing the cable outer jacket in order to expose some length of the strength members of the cable. The cable strength elements are typically attached to the enclosure so as to provide strain relief.

SUMMARY

In accordance with aspects of the present disclosure a fiber optic cable retention module includes a housing having a base. A first section extends from the base and defines a pocket for receiving strength members of a fiber optic cable. A second section extends from the base and defines first and second generally L shaped opposing slots. A retention member or blade is received in the slots. Examples of the retention member have a generally U shaped frame with first and second arms extending therefrom. The arms are each generally L shaped to correspond to the shape of the slots, and a cable receiving slot is defined between the arms.

In accordance with further aspects of the disclosure, the fiber optic cable retention module may provide strain relief for a fiber optic cable. For example, strength members of the cable may be received in the pocket and a cable jacket of the cable may be received in the cable receiving slot. In some embodiments, a fastener opening is defined in the base that receives a fastener extending from a surface, such as an interior or exterior surface of a cable enclosure. The fastener includes a locking tab that is received by a locking opening defined by the first section of the housing to secure the cable to the surface and provide strain relief.

DETAILED DESCRIPTION

Flat drop style fiber optic cables are broadly used in fiber optic cable networks. In addition to the optical fibers, a typical fiber optic cable may include cable jacketing material, cable strength members and fiber containment tubes, for example. It may be desirable in many situations to provide strain relief and limit or even prevent the cable jacketing and the cable strength members from axial displacement relative to one another, and/or relative to a cable enclosure or other device attached to the cable. A typical situation in which the securing is desired is where an opening has been made in the fiber optic cable for accessing the internal optical fibers, and where a splice enclosure may be installed.

When flat drop style cables enter a fiber optic enclosure such as a splice enclosure and undergo strain relief, strain relief for all individual flat drop cables will commonly occur on a shared single, fixed location component. In accordance with certain aspects of the present disclosure, a fiber optic cable retention module is provided that allows flat drop style cables the flexibility to be strain relieved independently and individually placed. Examples of the disclosed module attach to an end of an individual fiber optic cable, such as a flat drop style cable. Although there is variation in the dimensional size of flat drop cables, embodiments of the disclosed strain relief module can be achieved strain relief for a significant portion of those.

Generally, the examples of the disclosed strain relief module include a housing such as an injection molded plastic body with a press fitted, U-shaped metal retention blade received therein. The body is structured so as to be mounted onto various locations of a receiving structure such as a splice enclosure.FIG. 1illustrates an example of a fiber optic cable retention module100in accordance with aspects of the present disclosure. As noted above the module100is configured for receiving and retaining a fiber optic cable50, which has a lengthwise (longitudinal) cable axis L and includes a plurality of optical fibers52(shown in the figures as contained in a buffer tube), a pair of strength members54and a jacket56surrounding the optical fibers52.

In this disclosure, the terms longitudinal and lengthwise are used interchangeably to refer to a direction along the cable axis L, which is parallel to a longitudinal axis L of the module100when the cable is retained in the module100. Further, portions of the cable50, in practice, will generally be cut so as to provide an access opening to the optical fibers52. In some of the drawings figures discussed herein, all components of the cable50appear cut. However, it will be understood that this is for illustrative purposes as the optical fibers52and/or buffer tube including optical fibers may be cut for splicing in the enclosure or may be uncut through fibers. Furthermore, while in some illustrations the entire jacket56is shown as removed to provide the opening, in some implementations, portions of the jacket56remain while sufficient amounts of the jacket56are removed to allow access to the fiber(s)52and strength member(s)54. One or more splices may be formed between the fiber(s)52and other fibers or the like.

The retention module100includes a housing102having a base101. In some examples, the housing102is an injection molded plastic body. The housing102further includes a first, or forward, section104and a second, or rear, section106extending from the base, with a side wall108extending from the base102between the first section104and the second section106to connect the first and second sections104,106. In the illustrated examples, the sidewall108extends on one side of the module100. On the opposite side of the module, an opening109is defined between the first and second sections104,106. The first section104forms a pocket110for receiving the strength members54of the cable50as will be discussed further below. The second section106forms opposing slots112for receiving a retention member or blade120. In the illustrated example, the retention member120is slidably received in the slots112. A retention ledge114extends from the second section106for receiving the cable50such that the jacket56rests thereon. The ledge114is generally T-shaped, having a central portion116extending from the second section106with a cross member118extending transversely therefrom. The portions of the cross member118extending from the central portion116and the end surface of the second section114of the housing102define cable-securing channels122for receiving a cable-securing member such as a tie wrap124(seeFIGS. 3 and 5-7). The securing member extends around the ledge114and jacket56and seats in the channels122to fasten the cable50to the module100as will be discussed further below.

In the illustrated embodiment, the slots112formed in the second section106are each generally L-shaped. As best shown in the top view ofFIG. 5, the slots112each have a first portion112aextending generally in the direction of the cable axis L and a second portion112bextending towards the center of the rear portion106and towards the cable50. The retention member120is correspondingly shaped to be received in the slots112. Referring toFIGS. 8-12, an example of the retention member120is illustrated. The retention member120includes a frame130with two arms132extending upwardly therefrom. The arms132are generally L shaped, having first and second portions132a,132bcorresponding to the shape of the slots112a,112b. Thus, the first portion132aextends generally parallel to the axis L, while the second portions132bextend generally towards each other, inwardly toward the center of the module100. In the illustrated example, the second portion132bis bent inwardly from the first portion132asuch that there is a radiused junction132cbetween the portions132a,132bof the arms132. Further, in the embodiment illustrated, the second portion132bdoes not extend from the first portion132aat a right angle, but rather is offset from a line perpendicular to the first portion132aby an angle α. In some embodiments, the angle α is between 12-18°, and in certain embodiments the angle α is 15°.

A gap between the arms132defines a cable receiving slot134. As noted above, in the illustrated embodiment the arms132are angled at an angle α, so that when the retention member120is received in the slots112, the arms132are angled toward the first section104of the housing102. As such, with the cable50inserted therein, the arms132are especially resistant to pulling of the cable longitudinally out of the housing102. In other words, when installed in an enclosure, if an operator were to inadvertently try to pull the cable50out of the enclosure, the arms132would flex to increase the gripping force applied to the cable50and prevent lateral movement thereof.

In the illustrated embodiment, the frame130of the retention member120includes a curved segment136in a central portion of the frame130. As shown in the top view ofFIG. 10, the illustrated example of the frame130of the retention member120is generally U-shaped, and a lower segment of the arm first portions132aproximate the curved segment136of the frame130forms one or more barbs138. The retention member120may be a metal material, such as spring steel, and when the retention member120is inserted in the slots112, an interference fit with the slot112may flex the curved segment136. Further, the barbs138may engage the material of the housing defining the slots112. As a result, a retention force may be applied between the slots112and the frame130to help with secure placement of the retention member120in the slots112.

The second section106includes a longitudinally extending channel140configured to receive a segment of the cable50where the cable jacket56is still intact. In the illustrated examples, the cable50is a flat drop cable. As such, the channel140includes substantially flat sidewalls displaced from each other transversely a distance allowing insertion of the cable50therebetween. In some embodiments, a transverse width of the channel may be slightly less than that of the cable50to allow an interference fit that may serve to hold the cable50in place until it is secured in place by, for example, the tie wrap124or other connector. In other embodiments, the channel width may be slightly more that of the cable50, using other features to retain the cable without use of an interference fit.

The pocket110formed in the first section104of the housing102is configured to receive the strength members54of the cable50. As shown inFIG. 1, the cable50is cut and a portion of the jacket56is removed. The strength members54are cut to the desired length, and the optical fiber(s)52may also be cut as necessary for the particular application. The exposed strength members54slide into the pocket110as shown inFIG. 2, and then the cable50is pushed down into the retention member120and into the gap134between the arms132as illustrated inFIGS. 3 and 4. The fastener124then wraps around the cable50and the retention ledge114to secure the cable50in the module100. The sidewall108extends on only one side of the module100, leaving the opening109so that the optical fiber(s)52can extend from the module100. The process of securing the cable50to the module100can be done outside a fiber optic splice enclosure depending on sealing mechanisms, simplifying the act of fastening the cable50to the module100.

To provide strain relief in an enclosure such as a splice enclosure, the base101of the housing102defines a fastener opening150in a bottom surface opposite the first section104of the housing102as shown inFIG. 7.FIG. 13illustrates the module100prior to being fastened to a splice enclosure200. The splice enclosure200includes a fastener210extending therefrom. The module100is situated over the fastening tab210, such that the fastener opening150receives the fastener210to lock the module100onto the splice enclosure200.FIG. 14illustrates the module100fastened to the splice module, thus providing strain relief for the cable50.

In the example shown inFIG. 7, the fastener opening150is generally cross-shaped. A locking opening152is formed in opposite sides of the first section104of the housing102. Referring back toFIG. 13, the fastener210includes a pair of opposing resilient spring fingers212extending from a surface202of the splice enclosure200. For ease of illustration, inFIG. 13a single fastener210is shown extending from the surface202, which is situated inside the enclosure200. In other implementations, the fastener210may extend from other surfaces internal or external to the enclosure200.

In other embodiments, several fasteners210may be provided. For example, the fasteners210may be arranged in predetermined locations within the splice enclosure200, on one or more surfaces202thereof. The fingers212may be fabricated from a flexible material such as plastic, and may be integrally molded with components of the splice enclosure200. The spring fingers212include respective locking tabs214extending therefrom. When the module100is pushed onto the fastening tab210, the spring fingers212are received in the fastener opening150and flex inwardly as they are inserted into the fastener opening150. When the locking tabs214reach the locking openings152, the fingers212return to their original positions such that the locking tabs214snap into the locking openings152, locking the module100in place on the surface202of the splice enclosure200.

Various modifications and alterations of this disclosure may become apparent to those skilled in the art without departing from the scope and spirit of this disclosure, and it should be understood that the scope of this disclosure is not to be unduly limited to the illustrative examples set forth herein.