Electricity: conductors and insulators – Conduits – cables or conductors – Combined
Utility Patent
1999-04-29
2001-01-02
Kincaid, Kristine (Department: 2831)
Electricity: conductors and insulators
Conduits, cables or conductors
Combined
Utility Patent
active
06169250
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to enclosures for cable splices. More specifically, the invention relates to an enclosure for a longitudinally extended cable splice, where the splice includes at least one connector for connecting at least two cables. At least a portion of the enclosure is filled with a sealant to provide electrical insulation and environmental protection to the cable splice.
BACKGROUND OF THE INVENTION
Longitudinally extended cable splices for low voltage power applications are well known. Such cable splices may be of the butt or inline type, and typically require protection against mechanical impact, electrical shock and the ingress of water or humidity. Typically, between two and four cables are spliced together using a connector, such as a screw connector, a crimp connector or any other suitable connector known in the art. The cross section of the cables are typically in the range of 1.5 to 150 mm
2
, corresponding to diameters in the range of 5 to 30 mm. Accordingly, the dimensions of the enclosures are on the order of several centimeters, at least.
The most effective and safest way to achieve a splice enclosure which provides the necessary protection against mechanical impact, electrical shock and ingress of water or humidity is to arrange the cable splice into an splice enclosure or mold into which a hardenable resin is injected. The hardened resin itself then forms the splice body. Unfortunately, this type of splice body does not allow a nondestructive reopening of the splice if required. However, it is often necessary to reopen a splice body for a variety of reasons.
Thus, in a large variety of applications it is desirable to have a splice body that allows reentry without destroying the splice body or using undue force. Further, it would be extremely desirable to maintain the possibility of re-closing the protective splice body after the completion of the work on the spliced cables.
Several splice enclosures and methods of using such enclosures have been developed which allow reentry into the protective enclosure without destroying the enclosure and/or the splice. Typically, the cable splice is surrounded by material having a viscosity which is low enough that the material can easily penetrate into all interstices of the cable connection. Typically, the material does not harden completely, so that the splice can be relatively easily reopened. However, the viscosity of the material must also be high enough so that it remains in position over a long period of time and does not easily flow out of the splice enclosure. The relatively low viscosity of the material, however, causes another problem. Namely, the cable connection is insufficiently mechanically fixed within the splice body, allowing the spliced cables to move within the splice enclosure in an undesired manner. It thus becomes necessary to provide means for mechanically fixing the cables and the connectors within the splice body, to ensure that uncontrolled movement of the spliced cables does not occur.
European Patent No. EP 0328386 describes a splice enclosure which provides the desired electrical and environmental protection to cable splices. The splice enclosure consists of a molded or extruded part where two portions are connected to each other through a hinge. The two portions of the splice body are filled with a sealant material. This configuration is particularly useful for the connection of relatively small cables with a closed system which provides enough pressure onto the cables to keep them in place.
PCT Publication WO 97/16869 describes a system in which a molded body consists of two parts which are connected to each other through a hinge, both parts being filled with a gel-type material. Both parts of the body are provided with internal protrusions or alignment buttons which prevent the connector of the spliced cable from freely moving within the splice body. This particular system can work satisfactorily only if the size of the cable connector approximately corresponds to the positioning of the internal protrusions which prevent the cable connector from freely moving within the splice body. Larger connectors cannot be placed into the system at all, and smaller connectors would have an unacceptable freedom of movement.
U.S. Pat. No. 5,397,859 describes an enclosure with two parts connected to each other through a hinge, and also provided with a lateral flap. The flap prevents the sealant from moving out of the system in an uncontrolled manner when the enclosure is closed over the splice. The enclosure is designed for use with coaxial cables joined using a special connector. When the spliced cables are pressed between specially designed strain relief means in the enclosure, the splice is provided with the necessary mechanical fixation within the enclosure. The enclosure has limited versatility with respect to the use of different cable types and connectors.
U.S. Pat. No. 4,610,738 shows an enclosure for the splice of bundles of telecommunication cables. As in the previous references, two portions of the enclosure are linked together through a hinge. The two cable bundles are fixed together in the middle of the enclosure using a screw which is provided with a slot into which the cable bundles are inserted, and where the bundles are fixed together using an additional nut. The ends of the bundles are then bent in a perpendicular direction and the cables inserted into the gel of the enclosure while the ends of the bundles are sorted. The individual cables of the bundles are connected to each other with a special holding device capable of allowing the fixation of the individual connectors to each individual cable. Such a system would not be useful to protect common low voltage cable splices as described herein, as the connector of the spliced cables would have to be positioned in the location where the holding screw of the reference is positioned.
The above-mentioned references describe a variety of enclosures for cable splices. However the references are only useful with specific configurations of either the cables or the entire cable splice. For relatively small cable and connector dimensions, the sealant compressed within the enclosure provides the necessary mechanical stabilization. In other configurations, alignment protrusions are arranged within the enclosure to provide mechanical stability. However, the alignment protrusions limit the use of the enclosure to splices having a narrowly defined geometry. The strain relief means which are provided in the enclosure are restricted to cables which fall within a small range of sizes. Finally, the use of fixation screws in the middle of the enclosure preclude the use of the enclosure with typical low voltage splice connectors.
It would therefore be desirable to provide a re-enterable splice enclosure which is usable with cables of widely varying diameters and which provides the necessary electrical and environmental protection, as well as a means for fixing the cables securely within the enclosure.
SUMMARY OF THE INVENTION
The present invention provides an easily re-enterable splice enclosure which securely holds a wide variety of connectors and splice configurations. The inventive enclosure comprises a first cover member and a second cover member, each having two longitudinal sides and two end walls. The cover members are configured to releasably engage each other and form a cavity for enclosing a cable splice. The cavity is filled with a sealant material for electrically insulating the cable splice and protecting the cable splice from the environment. The cables of the cable splice project from at least one of the end walls of the cover members. A cable fixation member is provided for attachment to the cable splice. The fixation member and an attached cable splice are inserted into the cavity formed by the first and second cover members. The fixation member is configured such that a wide variety of cable splices may be attached to the fixation member.
The advantage of having a separate fixation member is that the ca
3M Innovative Properties Company
Kincaid Kristine
McNutt Matthew B.
Nguyen Chau N.
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