GB2424768A

GB2424768A - Insulation for spliced wires

Info

Publication number: GB2424768A
Application number: GB0506162A
Authority: GB
Inventors: John Andrew Nutt
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 2005-03-29
Filing date: 2005-03-29
Publication date: 2006-10-04
Also published as: GB0506162D0

Abstract

Wires 10a, 10b are spliced together, and a flowable silicone gel 18 placed on the splice and over the wires' insulation. A self supporting silicone sleeve 14 is then slid over the splice, and the gel is cured. The splice may be made by crushing a silicone collar 16. The sleeve may be rotated into position to give an even coverage of gel. The splice may be used in the wiring loom of a gas turbine engine.

Description

WIRE SPLICE PROTECTION

The present invention relates to the protection of a splice in an otherwise insulated length of wire.

The present invention has particular efficacy where the wire containing the splice is required to operate i.e. conduct electricity, in a hostile environment, such as an environment that includes fluids, and/or heat and friction.

According to the present invention, a method of protecting spliced wires in an otherwise insulation covered length of wire against ingress of aggressive fluids comprises applying a coating of flowable silicone to the splice and to the wire insulation either side thereof, then bridging the splice and coated insulation portions with a self supporting silicone sleeve.

The invention will now be described, by way of example and with reference to the accompanying drawings, in which: Fig 1 is a part view of opposing ends of a broken insulated wire, the ends of which have been prepared for splicing.

Fig 2 depicts the spliced wire ends of Fig 1.

Fig 3 depicts a self supporting silicon sleeve bridging the splice on a bed of flowable silicone.

Fig 4 illustrates the spliced wire of Figs 1 to 3 further covered in spaced relationship by other protective means.

Fig 5 depicts a ducted fan gas turbine engine supporting wiring looms of a kind on which wire splices having protection in accordance with the present invention could be utilised.

Referring to Fig 1. The broken ends l0a and lOb of a wire 10 have had the insulation 12 on each end stripped back so as to enable joining of the wire ends lOa, lOb by splicing.

Referring to Fig 2. Prior to effecting the splice, a sleeve 14 made from a self supporting BEN-HAR 1151 grade A silicone and having a bore sized so as to easily slide over the wire insulation, is slipped over the wire end lOa, to a position clear of that end. A collar 16, also made from the same self supporting silicone, is located between the wire ends lOa and lOb, and the wire ends lOa and lOb inserted therein, in parallel with each other. Collar 16 is then crushed with an appropriate crimping tool (not shown), thus forcing wire ends lOa and lOb into permanent contact with each other.

Referring now to Fig 3. A circumferential layer of a flowable silicone gel 18 is laid along the wire insulation 12, so as to bridge the spliced portion. Sleeve 14 is then moved along the insulation 12 in a rotary manner so as to ensure that an even circumferential layer of silicone gel is achieved between sleeve 14 and wire 10. The movement is continued until sleeve 14 overlaps both sides of the spliced portion. The silicone gel is then cured in known manner i.e. in the presence of moisture, at room temperature, thus effecting a permanent seal against fluid ingress.

Referring now to Fig 4. In the present example, the insulated wire 10 has an outer protective jacket 20 that has been stripped back to expose a reinforcing wire mesh 22 that has been folded back over outer jacket 20. For reasons explained hereinafter. A first layer consisting of copper tape 24 is bound round the assembly in spaced relationship with wire 10, and is clamped in position between pairs of metal ferrules 26 and 28, and 30 and 32 fixed to respective ends of stripped back outer jacket 20.

The inner ferrules 26 and 30 also clamp the folded back wire mesh 22 to outer jacket 20. This to provide screen continuity. A heat resistant layer of tape 34 sold under (Rlfl) the name KAPTON,,is wrapped round the copper tape 24, followed by a layer of flame resistant self amalgamating tape 36 sold under the name POLAMCO 100P323, and followed again by a layer of abrasion resistant PTFE tape 38. The end extremities of the final layer 38 are bound to outer jacket 20 by lacing tape 40, sold under the classification number ESW1900. The whole thus forms a tubular structure around the spliced wires. Tapes other than those identified herein may provide appropriate protection against the environment in which the spliced wire operates.

In Fig 4, all of the binding materials 24, 34, 36 and 38 are shown in spaced relationship. This is merely to illustrate the individual tapes more clearly.

Referring now to Fig 5. A fan cowl 42 for a ducted fan gas turbine engine (not shown) has wiring looms 44 mounted about its outer surface 46. Should any of the wires in looms 44 break, they can be spliced and the splice or splices protected in the manner described and claimed in

this specification.

The present invention is appropriate for adoption in all environments, on land, sea and in the air, in which electrical wiring is used.

Claims

1. A method of protecting bared spliced wires in an otherwise insulation covered length of wire against ingress of fluids, comprising applying a coating of a flowable silicone to the splice and to the insulation each side thereof, then sliding a self supporting silicone sleeve over the flowable silicone to a position wherein said sleeve bridges said splice, and allowing the flowable silicone to cure.

2. A method of protecting spliced wires as claimed in claim 1 including the step of effecting the splice by arranging the bared wires in overlapping parallel relationship within a self supporting silicone collar and crushing said collar so as to squeeze said bared wires into permanent contact with each other.

3. A method of protecting spliced wires as claimed in claim 1 or claim 2 wherein said self supporting silicone sleeve is slid onto the insulated portion of one of said wires to a position clear of bared wires prior to the splice being effected.

4. A method of protecting spliced wires as claimed in any of claims 1 to 3 wherein said silicone self supporting sleeve is slid in rotary manner over said insulated wire portions so as to bridge said splice with an even covering of flowable silicone.

5. A method of protecting spliced wires substantially as described in this specification and with reference to Figs 1 to 4 of the accompanying drawings.

6. A casing supporting a wiring loom including spliced wires protected by the method claimed in any of claims 1 to 5.