Splice protection system

Details Splice protection system Splice protection system

2001-06-20

2004-04-13

Ullah, Akm Enayet (Department: 2874)

Optical waveguides

With disengagable mechanical connector

Optical fiber to a nonfiber optical device connector

C385S147000

Reexamination Certificate

active

06719462

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
Embodiments of the present invention relate generally to systems for protecting signal transmission devices from adverse conditions that could alter operation of the signal transmission device, such as adverse environmental conditions including dirt, moisture, insects, local chemical and biological contaminants, and microorganisms. More particularly, embodiments of the present invention relate to the protection of a splice or other connection in a signal transmission device, such as an electrical or optical cable. Even more particularly, embodiments of the present invention relate to a novel closure for protecting splice connections from exposure to moisture or other environmental elements that may harm or otherwise interfere with operation of the signal transmission device.
2. Description of Related Art
Changes in plant construction philosophy and methods have often led to the need for new products. The telephone subscriber loop presents one such case. The initial deployment of buried drop wires envisioned a continuous, monolithic run between the terminal and the customer premises. It was expected that, due to the low cost of materials, faulty or faulted runs would be replaced rather than repaired. Today, with the high costs involved with disrupting existing landscaping, the practice of splicing buried drop wire has become common enough to require a special system to protect the integrity of the connection.
The initial distribution plant in coaxial cable used a mechanical connector that was thought to be weather resistant by design. Over the years, these connections have shown themselves to be prone to failure from water intrusion and corrosion. The protection of existing splice connections can require a “split sleeve” system that can be placed mid-span in an existing cable run. The complex geometry of the mechanical connector or connector/tap oftentimes requires the system to be capable of having an encapsulant that will penetrate thoroughly, exclude oxygen to reduce oxidative corrosion, exclude water to prevent signal degradation and electrolysis. A complete potting of the entire connection will help prevent the formation of differential aeration cells. Encapsulants should not exhibit any creep over time since these connections are often made in aluminum conductors and the aluminum can be prone to cold flow. Encapsulant entry could cause an increase in resistance that would lead to cable heating and signal loss at the potentials that are imposed on coaxial cable.
There are several types of systems used for the protection of a buried drop wire splice. The first kind of system uses a two part chemical system that is mixed in the field in a container that may also serve as the final closure. The wires are immersed in the container or the mixture may be poured over the wires in an additional enclosure. There is considerable worker and environmental exposure and hence, resistance to handling small chemical mixes in the field. They can be messy, difficult to handle and apply. There is also the related expense in time lost while waiting for the system to cure. In cold climates the time can be appreciable relative to the entire repair operation.
A second system uses a grease or polymeric filling material confined in a multi-part rigid closure. The joined wires and bonding are inserted in the closure and the parts manually pressed or mechanically forced together to distribute the filling material into all of the void spaces. This approach is vulnerable to the effects of temperature on the flow of filling compound and the volume of wirework placed. Also, quality of work is difficult to monitor since there is no indication of completeness of the interstitial fill. Historically, inadequate filling leaves these systems vulnerable to water ingress from without and via the core of the drop wire. They exhibit severely limited life spans relative to the 40 years expected of most outside plant equipment.
A third system involves a rubber, generally cylindrical, elongated tubular member the inside surface of which is coated with a sealant. The tubular member is secured around the splice with the sealant on the inside surface used to secure the tubular member to the splice and to itself. No filling material is used to encapsulate the splice and prevent the ingress of water from without and via the core of the drop wire.
A fourth system commonly used is a heat-shrinkable sleeve. In addition to requiring special heating tools, there is the potential for deterioration of the integrity of the material due to overheating. Also, the available heat shrinkable materials for such applications are typically of high durometer to withstand the hostile environment, making re-entry as by slitting more difficult and limiting the flexibility of the spliced area. It is for these reasons that heat shrinkable materials have found little acceptance in the coaxial plant as well.
The nature of the mechanical connectors used in coaxial plant may necessitate periodic adjustment of the connector. Hence, any protective device must be easily removed and replaced. An advantage is gained if the same device can be reused as in the case where the encapsulant gel would return into the storage media leaving the connector clear and clean.
In the case of optical fibers, the present systems use large closures to house splices and provide mechanical strain relief and fiber alignment against micro bending losses. The use of mechanical connectors for fiber connections will increase as wider use of fiber is made in distribution plant and single fibers, rather than bundles or cables, are brought to the end use point. These connections will require protection from many environments from the weather to industrial environments on the factory floor to ordinary housekeeping activities in offices. The constant rearrangement of devices will require a protective device that is easily removed and that removes cleanly.
SUMMARY OF THE INVENTION
Splice protection systems of the present invention are useful for preventing unwanted entry of external elements into the splice regions of signal transmission devices, thus preserving the integrity and function of the signal transmission devices. In addition, embodiments of the present invention relate to closures for protecting signal transmission devices from adverse environmental conditions such as dirt, moisture, chemical contaminants and microorganisms that may adversely affect the operation of the signal transmission device. The adverse effects of dirt and moisture are of concern especially when the signal transmission devices are buried underground or placed in contaminated micro environments such as machine tool housings.
The protective sheathing or other coating (collectively “coating”) of signal transmission devices, such as electrical or optical cables, are oftentimes opened to fix the conductors, i.e. wires or optical fibers, therein or otherwise splice additional signal transmission devices together. Once the integrity of the protective coating is breached, dirt and moisture will penetrate the signal transmission device oftentimes causing failure unless steps are taken to seal out dirt and moisture and restore the original integrity of the cable.
In its simplest embodiment, the closures of the present invention include a wrapper, such as a flexible sheet of plastic, in combination with a water resistant material deposited onto or otherwise connected, affixed or adhered to the preferably flexible wrapper. The flexible wrapper with the water resistant material is then wrapped around the desired portion of the signal transmission device, such as a splice, and the water resistant material is manually massaged into the splice connection. The massaging of the material may be accomplished using numerous methods, such as, for example, manually massaging the material or massaging the material using mechanical tools, such as pliers, compression rings, and the like. The water resistant material is typically disposed on the wrapper and acts to invas

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