Optical fiber connector assembly

A crimp connector is disclosed for enhancing pull-retention of a fiber optic cable in a fiber optic connector assembly housing. The connector has a flange for engaging with the housing and crimp member for engaging with the cable.

BACKGROUND

The use of fiber optics for communications purposes continues to grow. Data, voice, and other communication networks are increasingly using fiber optics to carry information. In a fiber optic network, each individual fiber is generally connected to both a source and a destination device. Additionally, along the fiber optic run between the source and the destination, various connections or couplings may be made on the optical fiber to adjust the length of the fiber or to provide termination connection ports for end users at which one or more fibers may be branched from a feed cable. Each connection or coupling requires a connector and adaptor to align the fibers such that the light can transmit without interruption, and in instances when the connection may be exposed to weather conditions, an essentially waterproof configuration of components.

To interconnect the cables, numerous, different, cable connector designs and are available. Some example connectors may include, but are not limited to, SC, LC, ST and MPO connectors. In most of these designs, a pair of ferrules (one in each connector, or one in the connector and one in the apparatus or device), each containing an optical fiber end, are butted together end to end and light travels across the junction. To function effectively, an optical connector should join optical fibers with a minimum of insertion loss, and should provide mechanical stability and protection to the junction between the fibers in the operating environment. In general, the stability and protection of the fiber junction may be determined by the connector design.

Standard connector designs however, may not provide a means for a weather tight seal or similar environmental protection, and if used in a location where access is not protected, cables may be jostled or pulled, and possibly become loose or completely disengaged from their connector assemblies. Standard connectors may therefore not be rugged enough for use in extreme environments or locations where the cable connections is not well protected. Therefore, there remains a need for a ruggedized, connector assembly that is easy to install while also meeting the necessary performance requirements.

SUMMARY

In order to enhance pull-retention of a fiber optic cable in a fiber optic connector assembly housing a cable retention member may be provided within the assembly to engage the cable with the housing.

In an embodiment, an optical fiber cable connector includes a connector housing. The connector housing has a first end and a second end spaced longitudinally from the first end, and the housing defines an internal chamber extending between the first end and the second end, the chamber having at least one first cross-sectional dimension, and the second end having a cable passage for receiving an optical fiber cable therethrough for entry of the optical fiber cable into the internal chamber. The cable passage defines at least one second cross-sectional dimension, the second cross-sectional dimension being less than the first cross-sectional dimension to define an internal shoulder disposed radially about at least a portion of the cable passage. The optical fiber cable connector also includes at least one optical fiber connector disposed within the first end of the connector housing and connected to at least one optical fiber of the optical fiber cable, and a cable retention element disposed within the internal chamber about the optical fiber cable. The cable retention element includes a retention member, and the retention member includes a cylindrical portion disposed about at least a portion of the optical fiber cable, the cylindrical portion having a first end and a second end spaced from the first end, with the at least one optical fiber extending through the cylindrical portion from the first end through the second end, and a radial flange extending radially from the cylindrical portion adjacent the second end of the cylindrical portion, the radial flange defining a third cross-sectional dimension less than or equal to the first cross-sectional dimension and greater than the second cross-sectional dimension for engaging the shoulder of the cable passage and preventing entry of the radial flange into the cable passage. The cable retention element also includes a crimp tube having a first end disposed about and crimped to the optical fiber cable, and a second end spaced from the first end and disposed about and crimped to the cylindrical portion of the first retention member to retain the first retention member with the optical fiber cable.

In an embodiment, a cable retention element for retaining an optical fiber cable with a fiber optic cable connector includes a first retention member and a crimp tube. The first retention member includes a cylindrical portion for being disposed about at least a portion of an optical fiber cable, the cylindrical portion having a first end, a second end spaced from the first end, and a central passage extending from the first end to the second end. The retention member also includes a radial flange extending radially outwardly from the cylindrical portion adjacent the second end of the cylindrical portion, the radial flange being configured for engaging with a portion of a fiber optic cable connector. The crimp tube has a first end for being disposed about and crimped to the optical fiber cable, and a second end spaced from the first end for being disposed about and crimped to at least the first end of the cylindrical portion of the first retention member to retain the first retention member with the optical fiber cable.

In an embodiment, a method is disclosed for retaining a fiber optic cable with an optical fiber cable connector. The fiber optic cable includes at least one protective layer disposed about at least one optical fiber. The method includes inserting the optical fiber cable through a first end of connector housing and through an internal chamber of the connector housing, wherein the connector housing has a second end spaced longitudinally from the first end with the internal chamber extending between the first end and the second end, the first end including a cable passage for receiving the fiber optic cable therethrough, the cable passage having a first cross-sectional dimension, and the first end defines an internal shoulder within the internal chamber and disposed radially about at least a portion of the cable passage. The method also includes removing a portion of the at least one protective layer of the optical fiber cable to expose a length of the at least one optical fiber, and provide a protective layer end about the at least one optical fiber, and installing a crimp tube about the fiber optic cable, the crimp tube having a first end and a second end spaced from the first end, the first end including at least one radially inwardly extending tooth for engaging into the at least one protective layer of the optical fiber cable. The method also includes inserting the at least one optical fiber through a cable retention member to at least abut a first end of the cable retention member with the protective layer end, wherein the cable retention member includes a cylindrical portion defining the first end, and having a second end spaced from the first end, the cylindrical portion defining a first diameter, and the first end comprising at least one radially outwardly extending annular ring defining a second diameter greater than the first diameter, and the cable retention member also includes a radial flange extending radially from the cylindrical portion adjacent the second end of the cylindrical portion, the radial flange defining a second cross-sectional dimension greater than the first cross-sectional dimension for engaging with the internal shoulder about the cable passage and preventing entry of the radial flange into the cable passage. The method also includes disposing the second end of the crimp tube about the cylindrical portion of the retention member, crimping the second end of the crimp tube about the cylindrical portion of the retention member to reduce an internal diameter of second end of the crimp tube to a diameter less than the second diameter defined by the annular ring, crimping the first end of the crimp tube about the fiber optic cable to engage the at least one tooth into the at least one protective layer, installing at least one optical fiber connector onto the at least one optical fiber, and pulling the optical fiber cable back through the connector housing to abut the radial flange with the internal shoulder wherein abutment of the radial flange with the internal shoulder retains the fiber optic cable with the optical fiber cable connector.

DETAILED DESCRIPTION

It is to be understood that the drawings are solely for purpose of illustration and do not define any limits of the embodiments. Furthermore, the components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. For simplification, many of the drawings do not include a depiction of a fiber-optic cable as it would be disposed therein.

FIGS. 1, 2A and 2Bdepict views of a fiber optic connector assembly10. While the depicted fiber optic connector10is of a dual LC type connector, any description and drawings presented herein are also applicable to other types of fiber optic connectors, such as, for example, MPO, MT-RJ, APC (Angled Polished Connector), SC, SC APC, FC, FC APC, ST, LC APC, dual or simplex, with multi-mode or single-mode fibers. The connector assembly10features push-pull insertion and a bayonet-style mechanical latch12to connect the assembly to a terminal device or another cable.

The connector10may include a housing component14, a tailpiece of a sealing fitting16and a flexible boot18, and an optical connector sub-assembly20. The housing component14may define an internal chamber15configured for receiving at least one optical fiber (such as fibers102inFIGS. 4, 5) therethrough. The optical connector sub-assembly20may seat within the housing14, and may include an adapter clip22and a pair of optical connectors24mounted side-by-side within the clip. The optical connectors24may terminate optical fibers (for example, fibers102such as are depicted inFIG. 4) of a fiber optic cable100and may be any suitable type of connector for providing this function.

As represented in more detail inFIG. 5, the terminal optical connectors24may be slidably insertable into the clip22, and the clip may be slidably insertable into an opening28in a first end14aof the housing14. At least one of the housing14and clip22may be configured with a releasable catch configured for retaining the clip within the housing. A second end14bof the housing14may be configured for attachably receiving the fitting16. In an embodiment as shown inFIG. 2B, the fitting16may include a first end16athat is threaded to engage with a threaded portion of the housing end14b. A second end16bof the fitting16may be configured for attachably receiving the boot18. In an embodiment as shown, the second end16bmay be internally threaded to engage with an externally threaded portion of a first end18aof the boot18. The fitting16may define a cable passage17extending through the fitting from the first end16ato the second end16b. The boot18may include a cable passage19for passage of a cable100therethrough.

The connector10is configured for receiving a fiber optic cable100therein. The cable100may be a simplex cable, a duplex cable, a multi-fiber cable, or any fiber optic cable that is appropriate for the above-listed connectors. To provide a more durable, or rugged connector10, a cable retention device30, shown in additional detail inFIG. 2C, may be provided to engage the cable100within the connector in a manner as depicted inFIG. 3. With the cable retention device30holding the cable100within the connector10, the amount of force needed to pull the cable from the connector is substantially increased. In an embodiment, the amount of force needed to pull the cable from the connector may be increased by at least a factor of about 9 over a connector that does not include such retention device. As such, a simple jostling of the cables, or a casual pull on the cable100will not cause the cable to pull away from the connector10. In an embodiment, the amount of pull force required to pull a cable retained by the retention device30from a connector10may be at least about 450N (100 lbs).

The cable retention device30may include a T-shaped component32having a cylindrical post34with a radially extending flange36, and a crimp ring40that fits about the post and is crimpable about the post.FIG. 4shows a perspective view of the T-shaped component32and crimp ring40, andFIG. 5shows the crimp ring disposed about the cylindrical post34. The T-shaped component32and crimp ring40may be formed of a metal, such as aluminum, or nickel plated brass, or any other appropriate types of metals or materials that may be crimped together. In an embodiment, the T-shaped component32and crimp ring40may be formed of the same metal. Alternatively, each of the T-shaped component32and crimp ring40may be formed of different metals.

As shown in greater detail inFIGS. 6A-6C, a first end40aof the crimp ring40may include at least one radially inwardly projecting tooth44. In an embodiment as shown, the teeth44may be disposed circumferentially about the first end40aof the crimp ring40and spaced apart from one another. In an alternate embodiment,FIG. 6Cprovides a cross-sectional view of teeth44a, having an alternative cross-sectional configuration. In further alternative embodiments, not depicted, the teeth44may be spaced axially from the end40a. Alternatively, teeth44may be disposed at the end40a, as shown, and additional teeth44may be provided, for example, in at least one addition ring of such teeth spaced axially away from the teeth at the end. In a further embodiment, teeth44may be provided with various different spacings between the teeth, or randomly within the crimp ring40. In an alternative embodiment, a radially inwardly extending circumferential ring may be provided instead of individual teeth. For a cylindrical crimp ring40as shown, the end40amay include a marking, such as a line or groove41that indicates the end of the cylinder that has the teeth, thereby making it easier to install the crimp ring on a cable.

As shown in greater detail inFIGS. 7A-7C, a first end34aof the post34may include at least one radially outwardly projecting element or tooth46. In an embodiment as shown, the projecting element may be a ridge46that may be disposed circumferentially about the first end34aof the post34.FIG. 7Cprovides an alternate embodiment of a ridge46ahaving an alternative cross-sectional configuration. While not depicted, the ridge46may be disposed spaced axially away from the end34a, or at least one additional ridge may be provided, for example, spaced axially from the ridge at the end. Alternatively, the ridge may not be continuous along the entire circumference, and in essence, may be configured as circumferentially disposed teeth.

As represented inFIG. 10, instead of a cylindrical crimp ring40as shown inFIG. 4, a crimp ring140may have alternative configurations to adapt and attach cables of different diameters to the back post. A crimp ring140may be a reducing ring wherein a diameter of the cable is greater than a diameter of the back post, or an enlarging ring wherein a diameter of the cable is less than a diameter of the back post.

As represented inFIG. 5, in an embodiment, a fiber optic cable100may be inserted through the boot18, the fitting16, and the housing14, and the retention device30may be fastened to the cable. As shown inFIGS. 3 and 4, the fiber optic cable100may be stripped of a portion of its outer layers104,105to expose fiber strands102. Fiber strands102may include an inner core107and a protective sheath108. In one embodiment, the cable100may be inserted at least partially through the crimp ring40through the first end40a, or alternately, the crimp ring may be pushed onto the cable, so that the jacketed cable extends approximately half-way through the crimp ring. In additional embodiments, the jacketed cable100may extend through the crimp ring40along at least a portion of the length of the crimp ring, such as, for example, about ¼, about ⅓, about ⅔, about ¾, or any fraction between any of the listed values, of the length of the crimp ring. The first end40aof the crimp ring40may be crimped onto the cable100to force teeth44into the outer jacket104of the cable. When crimped in place, the teeth44of the crimp ring40bite into the outer jacket104to provide a retention mechanism for retaining the cable100within the crimp ring.

Post34may be inserted into the second end40bof the crimp ring40, and the second end of the crimp ring may be crimped to the post34so that the crimp ring diameter at the second end40bis reduced to be less than the external diameter at the ridge46, as depicted by the crimp ring/post configuration shown at A in the bottom half ofFIG. 3. The ridge46may thereby inhibit removal of the post34from the crimp ring, while the teeth44inhibit removal of the cable100from the crimp ring, thereby retaining the cable with the post34.

In an alternative embodiment, as depicted by the crimp ring/post configuration in the upper half ofFIG. 3, at least one reinforcement member106(Kevlar or aramid fibers, for example) of the cable100may be crimped between the post34and the crimp ring40to provide an additional retentive configuration for holding the cable with the post. Similarly, as discussed above, a reduction of the diameter of the end40bof the crimp ring40will inhibit removal of the post from the crimp ring. Additional cable retention may then be provided by the crimp fastened reinforcement member106, wherein if the cable100is disengaged from the teeth44, the bound reinforcement member may still provide a retentive function for keeping the cable in the connector.

In a further embodiment (not shown, but with reference toFIG. 3), an end portion of the outer layer105may extend into the post34. The layer105may, in an embodiment, extend into the post34, at least to the flange36. In an alternate embodiment, the outer layer105may extend completely through the post34and beyond the flange36.

As shown inFIG. 5, an opening28in the housing14may be sized and configured for receiving the adapter clip22therein. In an embodiment, the flange36of the T-shaped component may be configured to fit through the opening28as shown inFIGS. 8A and 8B. After attachment of the retention device30to the cable100(FIG. 5) the cable/retention member assembly may be pulled back through the housing14to seat the retention member against the surface16cof the fitting16in the position as shown in cross-section inFIGS. 2C and 3, and in perspective as shown inFIGS. 9A and 9B(cable not shown). So that the flange36may pass through the opening28yet still be retained by the fitting16, the flange may have a dimension along the axis70, for example, that is configured to fit through a narrower dimension of the opening28, while a dimension along the axis72, for example, may be larger than the diameter of the passage17of the fitting16. In an alternative embodiment, not shown, if a housing14were to be attached to a fitting16after the retention device10is attached to a cable100, the flange would not need to fit through the opening28, and the flange could be circular about its periphery so that the entire flange has a diameter that may be greater than the diameter of the passage17.

While various compositions, methods, and devices are described in terms of “comprising” various components or steps (interpreted as meaning “including, but not limited to”), the compositions, methods, and devices can also “consist essentially of” or “consist of” the various components and steps, and such terminology should be interpreted as defining essentially closed-member groups.