FIELD OF THE INVENTION

The invention relates to methods of manufacturing wired cables.

BACKGROUND OF THE INVENTION

In particular, the invention is related to wired cables. For example, an electric cable will usually comprise a plurality of wires surrounded together by an outer sheath. For electric cables, wires usually comprise at least an inner electrical core and an outer insulating individual sheath. Such cables usually comprise a front end to be connected mechanically and/or electrically to a complementary device.

Sometimes, the front end is not totally waterproof.

Therefore, there is a risk that water may enter the cable and propagate along the wires all the way to the opposite end. This could be detrimental in case the opposite end of the cable is not designed to receive water. This problem ought to be eradicated in a cost-efficient way, but also in a way which does not impair the manufacturability of the cables too much.

SUMMARY OF THE INVENTION

To this aim, it is provided a method of manufacturing a wired cable.

One provides a plurality of wires. Each wire comprises an outer surface.

One provides a part defining a plurality of passages. The part is made of thermofusible glue.

One assembles the part with the wires. Each wire extends in one passage.

One surrounds the wires together, at the location of the part, with an outer sleeve.

One melts the part.

When melting, the part will flow into every accessible location between the wires and the sleeve. Melting the part will provide a waterproof fit between the wires and the sleeve. Tests have shown that this method was very reliable, and also very easily industrialised.

This method could be applied for other cables than electrical cables. For example, dust could be prevented from propagating between neighbour optical wires toward an optical device at the other end of the cable by such a method .

In some embodiments, one might also use one or more of the features as defined in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Other characteristics and advantages of the invention will readily appear from the following description of one of its embodiments, provided as a non- limitative examples, and of the accompanying drawings.

On the drawings :

Fig. 1 is a schematic view of a possible application of the invention,

- Fig. 2 is a perspective view of an embodiment of a connector,

Fig. 3 is a perspective view of a bundle of wires ,

Fig. 4 is a schematic view of a step of an embodiment of a manufacturing process,

Fig. 5 is a top perspective view of an embodiment of a part,

Fig. 6 is a schematic perspective view of another step of the embodiment of a manufacturing process,

- Fig. 7 is a schematic view of yet another step of the embodiment of a manufacturing process,

Fig. 8 is a photograph of a cross-section through a manufactured embodiment.

On the different figures, the same reference signs designate like or similar elements. DETAILED DESCRIPTION

Fig. 1 very schematically shows an example of application of the invention. Fig. 1 shows an electrical car 100 which is to be charged from an external power supply 200. The car 100 is provided with a connector 101 to be placed in electrical connection with a connector of the power supply 200 to charge battery racks of the car. This application is exemplary only.

Fig. 2 now shows in more details an example of connector to which the invention can be applied. This example also is for the purpose of illustration only. In the present example, the connector 2 is a charge plug of the power supply 200, having a front end 2a and an opposite rear end 2b. The front end 2a has electrical contacts to be connected to complementary contacts of a mating connector. The rear end 2b is assembled to a cable 3 which extends to a remote electrical device such as, in the present case, a casing 201 of the power supply 200. In the present example, the connector 2 has a number of external shells 4, which surround an inside.

It may occur that water or humidity drains or leaks in inside the connector 2. Then it is essential to prevent the water or humidity from reaching the power supply or any other device to which the cable is connected. To this aim a part 11 is provided, as it will be explained below.

Fig. 3 shows in more detail the front end of the cable 3, showing the various wires 8 and respective electrical terminals 7. It will be noted that, within the scope of the invention, the wires of a given cable may have different diameters.

Fig. 4 schematically shows the cable 3 at some distance from its front end. The individual wires 8 can still be seen. Each wire extends along a longitudinal direction X, and the wires generally extend parallel to one another. Each wire has a peripheral outer surface 9. For electrical cables, such a surface is generally made of an electrically insulating material. This outer insulating layer surrounds an electrical core to be electrically connected to a respective terminal by any suitable means.

The cable 3 further comprises an external sheath

10. This sheath also extends along the longitudinal direction X, and surrounds all the individual wires 8. This sheath generally is made from an electrically insulating material. The sheath has a front end 10a.

The cable 3 is provided with a part 11. The part 11 is provided beyond the front end 10a of the sheath 10. The part 11 is provided with a plurality of passages, each passage corresponding to a wire 8. As a purely illustrative embodiment, the part 11 may be provided profiled along the direction X. For example, the part 11 has a cross-shape or star-shaped profile, as visible on Fig. 5, with the number of arms of the star defining the number of passages, and hence the number of wires. In the present example of Fig. 6 and 7, the star has four arms 12a, 12b, 12c, 12d, provided one after the other in this order when turning in the counter-clockwise direction about axis X. Two neighbour arms together define a passage 13 for a wire. For example, the passage 13 defined by the arms 12a and 12b is shown on Fig. 5. Depending on the embodiment, the number of arms may vary from at least n=2, n being an integer.

The part 11 is made from a thermofusible material, such as a suitable wax. For example, it can be made from the product by Steinel® company as Cristal Stick ®. In the context of the invention, a thermofusible material is a material having a point of fusion much lower (for example at least 10°C lower) than that of the other neighbouring materials (materials of the wire, including at least the internal core and its outer insulating material, material of the sheath 10, and material of the sleeve which will be described below) . For example, it can be heated at a temperature in the range of 160°C-200°C.

According to an embodiment of the manufacture of such part 11, as shown on Fig. 6, a stick 14 is provided. The stick is profiled with the appropriate cross-section. Each part 11 can be cut with the appropriate length as indicated by the arrow C and the dotted lines.

The part 11 is assembled to the wires 8, as shown on Fig. 6, with each wire provided in a given passage. For example, the part 11 is inserted between the wires 8. The passages can be provided of uniform size, even though the wires are of different cross-section. This allows to easily insert the part without any specific orientation. Hence, said part is invariant under rotation by an angle Teta with respect to the longitudinal axis, whereby Teta=360/n, where η>1, n being an integer (here n is equal to the number of wires, ie n=4, namely Teta=90°) . Alternatively, the size of the passages could be tailored to the respective wire cross-section diameters, in order to improve the match between the wires and the part.

As shown on Fig. 7, a sleeve 18 is provided to surround the sheath 10, from an intermediate location I at least beyond its front end, to surround the part 11 and to surround wires 8 at the location of the part 11. The sleeve 18 has an outer surface 19 and an opposite inner surface 20. The inner surface 20 can be provided with adhering material (glue) so that the sleeve is fixed and sealed to the outer surface of the sheath 10 of at least one (preferably all) wire 8, and the part 11. The sleeve 11 extends longitudinally along the direction X.

Then heat is applied to the sleeve 18 at the location of the part, as indicated by the arrow H. Sufficient heat is provided so as to melt the part 11, without melting the sleeve, sheath, or wires, as explained above. Heat could be provided all around the periphery of the part at once, or by moving a heat source along the periphery of the cable. When melting, the part 11 will flow into any remaining gap between the wires 8 and the sheath 18. Thus, a water-tight barrier will be provided. This barrier is also dust-proof.

Fig. 9 is a picture taken after performing a cut along a cross-section of the manufactured cable. The adherence between the outer surface 9 of the sheath 22 (surrounding the core 21) of each individual wire 8 and the outer sleeve 18, notably its inner face 20, can be readily witnessed. The part 11 was totally melted.

The above process showed very high reproducibility. Hence, in many cases, sufficient water-tightness was provided, with low amounts of material. This process provides an improvement over the traditional glue-gun process used to fill-in the space between the wires and the outer sleeve, which shows lower reproducibility because the flow of glue between the wires is not controllable.