Encapsulation of telecommunications cable splices

• US 4,322,573 A
• Filed: 03/11/1980
• Issued: 03/30/1982
• Est. Priority Date: 03/11/1980
• Status: Expired due to Term

• Current Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Original Assignee: Northern Telecom Limited (Nortel Networks Corporation)
• Inventors: Charlebois, Leonard J.
• Primary Examiner(s): Reynolds, B. A.
• Assistant Examiner(s): TONE, DAVID
• Application Number:
  US06/129,246
• Time in Patent Office: 749 Days
• Field of Search: 174/84 R, 174/88 R, 174/71 R, 174/72 R, 156/49
• US Class Current: 174/72.00R
• CPC Class Codes: H02G 1/145 Moulds
• CPC Class Codes: H02G 15/117 for multiconductor cables

Abstract

A cable splice formed by wrapping an electrical connection in sealing tape and injection molding an encapsulation on the connection. The sealing tape is formed of material (e.g. ethylene propylene rubber) which softens under the influence of the injection molding temperature, and is shaped intimately into fluid-tight sealing contact with the electrical connection by shrinkage of the encapsulation during cooling. The material of the sealing tape is also heat insulating to resist increase in temperature of the insulated conductors within the cable during the injection molding process.

Claims

1. A method of forming a splice in a telecommunications cable between a pair of bared conductor ends from a first cable and a pair of bared conductor ends of a second cable comprising:

drawing a selected pair of conductors from the first cable through a slit in the cable, providing said conductors with bared ends, and forming electrical connections between said bared ends of the first cable and the bared ends of the second cable;

wrapping overlapping and contacting windings of heat softenable sealing tape around the first cable and beneath the connections and the bared conductor ends;

wrapping overlapping and contacting windings of the sealing tape in contact with the first windings and around said first cable and over the connections and bared conductor ends so as completely to enclose the connections and bared conductor ends in the overlapped windings;

injection molding an encapsulation of molten plastic material around the sealing tape wrapping and around adjacent insulation covered cable, the injection temperature being sufficiently high to soften the sealing tape and merge it into a single mass to cause the mass to completely and sealingly enclose the bared conductor ends and connections, the plastic material being compatible with the material of the insulation to provide a fluid-tight bond upon cooling; and

cooling the encapsulation during which it shrinks upon the softened sealing tape the resultant pressure causing the merged single mass of tape to become shaped intimately into fluid-tight sealing contact with the connection and bared conductor ends.

2. A method according to claim 1 further comprising surrounding the sealing tape by a material which is unsoftened at the injection moulding temperature.

3. A method according to claims 1 or 2 further comprising wrapping the windings of sealing tape in the form of ethylene-propylene rubber.

4. A telecommunications cable having a splice comprising:

electrical connections between a pair of bared conductor ends of a first cable and a pair of conductor ends of a second cable;

a layer of sealing material sealingly enclosing and in intimate contact with the connections, bared conductor ends, and adjacent insulation on cable parts, the layer formed from overlapped windings of heat softenable sealing tape around the first cable, beneath and then over the bared conductor ends, the tape heat softened and shaped into said intimate contact; and

an injection moulded encapsulation of plastics material completely surrounding the wrapping and adjacent insulation covered cable, the encapsulation being sealingly bonded to the said adjacent insulation.

5. A cable according to claim 4 wherein:

one of the pairs of conductors extend through a slit in the first cable;

the sealing material extends around the first cable to cover the slit and beneath the electrical connections, the sealing material also extending over the electrical connections and over the adjacent insulated end of the second cable to hold it within the sealing material.

6. A cable according to claims 4 or 5 wherein the layer of sealing material which remains unsoftened at the injection moulding temperature of the sealing material, completely surrounds the sealing material.

7. A cable according to claims 4 or 5 wherein the layer of sealing material is formed from sealing tape of ethylene propylene rubber.

8. A cable according to claims 4 or 5 wherein the first cable has an outer sheath which comprises polyethylene and the encapsulation is made from a material selected from the group consisting of ethylene acrylic acid, ionized resin, polyethylene and ethylene vinyl acetate.