Patent Application
20170059782
This application relates generally to instruments and sensors useable in a downhole environment, and more particularly, but not by way of limitation, to a mechanism for connecting fibre optic cable used to carry signals to and from the instruments and sensors.
Fibre optic cable is used in a wide variety of applications to carry data. Fibre optic cable often includes one or more optical fibres that may be individually wrapped in a plastic sheath and then collectively contained within a protective jacket. The use of fibre optic cable in data transmission applications has expanded significantly in recent decades as a result of advantages in transmission speeds and bandwidth provided by fibre cables.
However, unlike common electrical cables, connecting optical fibre cables presents challenges. Each optical fibre connection may contribute to unwanted signal attenuation (insertion loss) and reflection (return loss). Efforts to minimize these losses have produced a number of optical fibre connections, including the common “LC,” “SC” and “ST” connectors. Although widely adopted and continually refined, these fibre connectors remain poorly suited for use in applications with severe space limitations, where multiple fibre connections are required at the same point. Connectors exist with multiple fibre channels; however, during maintenance all of the fibre channels are broken, this may lead to dirt or contaminants on the fibre end faces. To ensure minimal losses each channel must then be carefully cleaned, drastically increasing the amount of time needed for maintenance, if, for example, only one channel needed maintenance. Accordingly, there is a need for an improved mechanism for connecting and rigidly securing multiple fibre optic cables in a small space envelope, but still being able to individually make and break each connection during servicing.
Embodiments of the present invention include a mechanism for securing a series of fiber optic cables. The mechanism includes a base that has a connector recess and a lid that is removably attached to the base.
In another aspect, some embodiments include a downhole instrument for measuring a condition in an underground wellbore. The downhole instrument includes multiple input fibre optic cables, multiple output fibre optic cables and a connection box providing a secure connection between the fibres. The connection box includes a base that includes several connector recesses, one or more fibre optic connectors secured within the connector recess and a lid that is removably attached to the base. The connection box may have a flat surface, making it suitable for mounting directly to a chassis or PCB in a downhole instrument.
In accordance with an exemplary embodiment of the present invention,
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The connection box 106 further includes a base 116 and a lid 118. Optional fasteners 120 can be used to secure the lid 118 to the base 116. Turning to
In some embodiments, the base 116 is manufactured from a plastic or synthetic rubber material that provides a limited degree of flexibility when exposed to the application of force. For applications of extreme vibrations, the plug recess 128 and receiver recess 130 are each sized such that they are substantially the same size or nominally smaller in an unstressed state than the respective plug 114 and receiver 112. When the plug 114 and receiver 112 are connected and pressed into the respective connector recesses 126 within the base 116, the connector recesses 126 apply a compressive force that holds the fibre optic cable connectors 110 in place. Thus, in some embodiments, the plug recess 128 and receiver recess 130 are configured such that the plug 114 and receiver 112 can be snapped into a secure fit within the base 116.
Notably, each receiver recess 130 and plug recess 128 includes a sloped face 132 that faces the interior portion of the base 116. The sloped face 132 urges the plug 114 and receiver 112 toward the interior of the base 116 when these components are pushed into their respective recesses within the base 116. The application of inward forces on the plug 114 and receiver 112 ensures that the fibre optic cable connector 110 maintains a secure connection in high vibration conditions by pre-loading the spring within the receiver 112 to a desired extent.
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Thus, the connection box 106 provides an improved mechanism for securing the fibre optic cable connectors 110, fibre optic input cables 108 and fibre optic output cables 109. It is to be understood that even though numerous characteristics and advantages of various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and functions of various embodiments of the invention, this disclosure is illustrative only, and changes may be made in detail, especially in matters of structure and arrangement of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. It will be appreciated by those skilled in the art that the teachings of the present invention can be applied to other systems without departing from the scope and spirit of the present invention. For example, it may be desirable to make use of the connection box 106 for securing fibre optic connections in other applications and environments, including, for example, in aeronautical, automotive and manufacturing systems.
