CABLE TERMINATION AND MANUFACTURING PROCESS

Description

FIELD

[0001] The present disclosure relates to a method of manufacturing a cable termination. Cable terminations for electrical cables are generally known e.g. as Y-splice, H-splice, T-splice or as cable terminations comprising a plug or a socket. Due to high currents flowing through the cables it is necessary to ensure water tightness and electrical insulation as well as EMC shielding according to the requirements.BACKGROUND

[0002] Current solutions use solid gaskets or liquid gaskets based on silicone adhesives placed in a cover of the housing and solid silicone gaskets that seal between the cable and the housing. If the insulation material of the cable consists of a non-PVC material, e.g. of a silicone material or of a cross-linked polyethylene material (XPLE), or other crosslinked and non-cross linked polyolefins, a tight and sealed connection of the whole assembly is difficult to achieve. More specifically, if a polyurethane material, in particular a two-component PUR material is used in sealing applications, it is difficult to be applied due to the non-adhesive behavior of the non-PVC cable insulation.

[0003] Document EP0508629A2 discloses a method according to the preamble of claim 1 and an electrical connector having a neoprene based boot bonded to a polyurethane-jacketed electrical conduit.

[0004] Document CA2728300A1 discloses an overmolding of an electrical circuit, and more particular a system and method for polyurethane bonding during and / or after molding of the circuit.

[0005] Document US4450318A discloses an electrical insulation, and more specifically an improved means and method for splicing together the insulation of a pair of cables whose conductors have been joined.

[0006] Document GB2399235A discloses a pressure vessel and cable seal assembly, and more particularly a pressure vessel and cable seal assembly for housing electronic components is an underwater environment.

[0007] Document DE102012223650A1 relates to the sealing of interfaces on electrical wiring harness.

[0008] Document FR2683379A1 discloses a sealed connections of a multi-conductor electric cable to conductive pads and in particular such fittings where the pads, the conductors and an insulating sheath surrounding the conductors are embedded in an encapsulation product intended to prevent that of the humidity or a corrosive atmosphere reaches the studs.

[0009] Document US5817978A discloses a splicing device and a method of producing a splice intended to connect two electric cables composed of a sheath, a cladding and at least two primary wires comprising a first primary wire and a second primary wire.

[0010] Holloway John: "An Engineer's Mantra: never underestimate overmolded cable", 2 April 2019 (2019-04-02), pages 1-15, XP093088042, discloses thermoplastic urethane for overmolding.

[0011] There is a need to provide an improved cable termination which can be manufactured at low cost and which provides a good sealing against water.SUMMARY

[0012] The present disclosure provides a cable termination and a method of manufacturing a cable termination according to the independent claims. Embodiments are provided in the subclaims, the description and the drawings.

[0013] According to this method, the insulation jacket of the cable end is prepared by the provision of additional means to promote adhesion with a sealant. As a result, a sealing interface is formed between the jacket and the sealant.

[0014] The method comprises the use of a polyurethane material as the sealant. This allows the use of low pressure injection molding technology wherein the overmold of sealant may be molded to form a watertight and sealed outer enclosure of the cable termination without an additional housing being required.

[0015] The method comprises the use of a cable having an insulation jacket of a non-PVC material, e.g. an XLPE material, polyolefins, copolymers of polyolefins, cross-linked polyolefins and their copolymers. Such materials provide a very poor adhesion to polyurethane materials. Therefore, the preparation step according to the present invention provides a substantial improvement to achieve a tight seal after overmolding the cable end.

[0016] The method comprises the application of a tape onto the insulation jacket of the cable end. The cable can be a class T3 or T4 tape and it can be wrapped around a cable end or around a plurality of cable ends which are to be overmolded with the sealant. The adhesion to the insulation jacket can be achieved by using an adhesive tape.

[0017] The method comprises the step of applying a tape of polyethylene terephthalate (PET) material, namely a PET fabric tape having a cloth structure. Such cloth structure provides a good adhesion to polyurethane materials and an adhesion to the insulation jacket is provided by using an adhesive tape.

[0018] In another aspect, the present disclosure is directed at a cable termination, in particular manufactured by a method described herein.

[0019] The sealant is made of a polyurethane material. Such material is well suited for applying a sealant by low pressure injection molding with a 100% tight insulation against water, a resistance against oils, acids and chemicals and a resistance to temperature and vibrations. By overmolding a polyurethane material, it is further possible to implement markings or logos and to produce the overmolding in any desired color. Furthermore, a PUR overmold material may be solid or foam.

[0020] The overmold of sealant forms an outer enclosure of the cable termination such that no separate housing or enclosure is required. Further embodiments of the cable termination are a Y-splice, T-splice or an H-splice, e.g. for high voltage applications in electric vehicles.DRAWINGS

[0021] Exemplary embodiments and functions of the present disclosure are described herein in conjunction with the following drawings, showing schematically in Fig. 1an embodiment of a cable termination; Fig. 2a cable termination; Fig. 3a further cable termination; Fig. 4a plasma treatment of a cable end; Fig. 5a cross-section through a cable end; Fig. 6a partially cut-off section of a cable termination; and Fig. 7a cable termination in the form of a Y-splice. DETAILED DESCRIPTION

[0022] Fig. 1 depicts an exemplary termination of a cable end 10 in the form of a Y-splice, the cable termination comprising three electrical conductors 12 surrounded by an insulating jacket 14 made of a non-PVC material, e.g. a polyolefin, polyethylene or silicone material. The cable termination comprises a splice, e.g. a copper splice 26 connecting the three electrical conductors 12. In the region of the copper splice 26 the cable end 10 is provided with an overmold 24 of sealant, e.g. of a polyurethane foam material. To improve the adhesion between the insulation jackets 14 and the sealant 24 an adhesive PVC tape 30, e.g. of class T3 or T4, is wrapped around the insulation jackets 14 next to the copper splice 26. The overmold of sealant is applied with an excellent adhesion between the sealant 24 and the insulation14 of the cables.

[0023] Fig. 2 depicts a further embodiment (not claimed) of a cable termination similar to the embodiment of Fig. 1 wherein the preparation of the insulation jackets 14 is performed by applying a cold melt 32 onto the insulation jackets 14 and onto the copper splice 26.

[0024] Fig. 3 depicts a further embodiment (not claimed) of a cable termination wherein sealing rings 34 of a rubber or silicone material are applied onto the insulation jackets adjacent to the copper splice 26 to promote adhesion of the overmold of the sealant 24 and to provide a watertight sealing.

[0025] Fig. 4 depicts a cable end of a cable termination (not claimed) comprising an electrical conductor 12 surrounded by an insulation jacket 14 wherein a plasma head 40 comprising a plasma nozzle 42 is used for treating the insulation jacket 14 with a plasma beam 44 resulting in a plasma treated area 46 extending over the circumference of the insulation jacket 14 which is made of a non-PVC material, e.g. of a XLPE material, polyolefins, copolymers of polyolefins, crosslinked polyolefins and their copolymers.

[0026] Fig. 5 depicts a cross-section of the cable end 10 shown in Fig. 4 which has been overmolded with a sealant 24 of polyurethane foam. The preparation of the insulation jacket 14 through application of atmospheric plasma significantly promotes the adhesion of the sealant 24 to the insulation jacket 14.

[0027] Fig. 6 depicts a termination of a cable end 10 (not claimed), the cable comprising one or more electrical conductors 12 surrounded by an insulating jacket 14 made of a non-PVC material, e.g. a polyolefin, polyethylene or silicone material. The cable termination comprises an annular elastic sealing ring 16, of a rubber or a silicone material or of any other material such as PTFE that has the function of compressed sealing against the cable insulation. The sealing ring 16 is optionally serrated e.g. by providing annular grooves at the outer circumference, and is positioned over the cable end 10 to surround its outer circumference. The sealing ring 16 may comprise at least one of ethylene propylene rubber (EPR), nitrile butadiene rubber (NBR), Standard Indonesia Rubber (SIR), fluororubber (FPM), Ethylene acrylic rubber (AEM), fluorosilicone, fluorocarbon, and polyacrylate rubber.

[0028] In the disclosed embodiment the cable end 10 extends into a conductive housing 18 wherein the sealing ring 16 is located adjacent an end surface of the housing 18. Next to the sealing ring 16 the housing 18 is provided with a collar 20 forming an annular protrusion.

[0029] Before the cable 14 is inserted into the housing 18, a sleeve 15 which is made of heat shrinkable material (e.g. a polyvinyl chloride (PVC) material, polyvinylidene fluoride (PVDF), or fluorinated ethylene propylene (FEP) material) and the sealing ring 16 are positioned over the cable end and a braided shield 22 of the cable is folded backwards. Thereafter, the cable end 10 is inserted into the housing 18 such that the braided shield 22 is located between the inner circumference of the housing 18 and the insulating jacket 14 of the cable end 10. Thereafter, the housing 18 is caulked at a location C around its outer circumference to connect the cable end 10 with the housing 18 and to provide an electrically conductive interconnection between the housing 18 and the braided shield 22.

[0030] To compress the sealing ring 16 and to provide a tight seal against water and humidity, the sealing ring 16 is compressed by the sleeve 15 which is positioned over the sealing ring 16 and the collar 20. The sleeve 15 is thereafter heat shrunk over the sealing ring 16 and the collar 20 of the housing 18 and snuggly fits against the insulating jacket 14 of the cable end 10. Thereafter, the housing 18, the sealing ring 16, the sleeve 15 and the cable end 10 are connected to form a unit.

[0031] Finally, the sleeve 15, the sealing ring 16 the adjacent region of the cable end 10 and the housing 18 are provided with an overmolding of sealant 24 (e.g. PUR sealant), said sealant forming an outer enclosure of the cable end 10.

[0032] To improve the adhesion between the sleeve 15, the sealing ring 16, the insulating jacket 14 and the optional housing 18 an adhesive 17 may be provided at the inner surface of the sleeve 15. Such adhesive can be coated onto the sealing ring or can be provided as a separate intermediate layer.

[0033] It should be noted that the adhesive layer 15 and also the housing 18 are merely optional and not necessarily required to provide a cable end which is sealed and isolated against humidity and water. Furthermore, the housing 18 may be designed as or to comprise a plug or a socket. Further embodiments of the cable termination are a Y-splice, T-splice or an H-splice, e.g. for high voltage applications in electric vehicles.

[0034] Fig. 7 depicts an example of a Y-splice comprising three cable ends 10 enclosed in an overmold 24 of polyurethane material having a block shape and forming an outer enclosure of the Y-splice.

Claims

1. A method of manufacturing a cable termination, the method comprising the steps of: - providing a cable end (10) of a cable (10) having a protective outer insulating jacket (14) of a non-PVC material; - preparation of the insulating jacket (14) of the cable end (10) to promote adhesion with a sealant (24) by applying a tape onto the insulating jacket (14) of the cable end (10); and - overmolding the cable end (10) with the sealant (24), to form a watertight and sealed outer enclosure of the cable termination, characterized in that - the sealant (24) is a polyurethane, PUR, material, and - the tape is an adhesive PET fabric tape.

2. The method of claim 1, wherein the insulating jacket (14) comprises at least one of polyolefins, copolymers of polyolefins, crosslinked polyolefins and their copolymers.

3. The method of any of the preceding claims, wherein the tape is a class T3 or T4 tape.

4. The method of any of the preceding claims, wherein the preparation step comprises: plasma treating or corona treating the insulating jacket (14) of the cable end (10).

5. A cable termination comprising a cable end (10) of a cable (10) having a protective outer insulating jacket (14) of a non-PVC material, and an overmolded sealant (24) of a polyurethane, PUR, material forming a watertight and sealed outer enclosure of the cable termination, and an adhesive PET fabric tape, e.g. a class T3 or T4 tape, applied onto the insulating jacket (14) of the cable end (10), wherein the cable termination is manufactured using a method in accordance with any of the preceding claims.

6. The cable termination of claim 5, wherein the non-PVC material comprises at least one of a polyolefin, copolymers of polyolefins, crosslinked polyolefins and their copolymers.

7. The cable termination of any of claims 5 or 6, comprising a plug, a socket, a Y-splice, H-splice, or T-splice.