EP1463149B1 - Process for making a multicore connection cable watertight - Google Patents

Abstract

The method involves removing a sheath (3) of a cable to set a lug of connection or to join an end of strands (2) of this cable to strands of other cables to form a splice. The strands of the cables are soldered by depositing a fixed quantity of a resin with high wetting ability with respect to a metal of the strands so as to fill capillary interstices between the strands. Independent claims are also included for the following: (a) a water-tight multi-strand cable; and (b) an electric control system for an equipment of a motor vehicle.

Description

The present invention relates to a method for sealing a multi-stranded connection cable, in particular a grounding cable, or provided with an electrical connection lug, in particular with a part of the box or other similar massive structure. a motor vehicle, is connected to other similar cables by a splice.

In a motor vehicle are usually used multiple electrical or electronic control or control devices, mounted where appropriate in closed housings suitable protection, these devices being joined to the outside by connection cables generally comprising each several metal strands flexible, housed inside a sheath or insulating envelope.

When the internal volume, closed and sealed, of these housings is subjected to temperature variations, frequent according to their conditions of use and their location in the vehicle, as well as because of the external environment to this one, occurs correlatively, within these housings, a variation of internal pressure, the latter may as appropriate become higher or lower than the ambient pressure.

When this volume delimited by the housing is connected to the outside by electrical connection cables, including grounding, these pressure variations are exerted at the end of wires or strands of these cables that end in the housing, and can be transmitted to the other end, located outside thereof.

Thus, if the electric cable consists of several flexible metal strands, as is the most general case, the free spaces between these strands themselves according to the length of the cable and / or between the peripheral strands and its insulating sheath, are not sealed due in particular to the clearance between these strands and between them and their sheath, so that the aforementioned pressure variations are transmitted from one end to the other. In addition, the interstices between the strands being very narrow, they behave as capillary tubes vis-à-vis liquid fluids that can bathe their end, outside the housing.

The classical physical laws of Laplace or Jurin, which govern the process of wetting surfaces by fluids, in particular by a liquid, and the physical behavior of the capillary tubes, make it possible to demonstrate that with a liquid fluid having a high wettability with respect to the metallic material of the conducting strands, this liquid can travel a great length and in particular a great height if the cable is disposed substantially in a vertical position, between these strands, this height being related to the surface tension of the liquid and inversely proportional to the radius of the capillary tubes thus defined. The ability of the liquid to flow between the strands also depends on the surface condition of these strands.

In the more specific case of the automotive industry, the ends of the connecting cables are either connected to a housing supplying any electrical component of a vehicle or to a sealed interconnection box, or are arranged inside the housing. cabin itself, in an area that remains dry permanently. On the other hand, the opposite ends, in the case of grounding cables, are usually fixed directly by terminal lugs to the vehicle body and are thus subjected to splashing water, or even immersion. possible complete in a liquid medium, immersion which may be temporary but which may also extend for a significant period.

Under these circumstances, the water that wets the ground lug and / or the cable connecting strands connected thereto, can penetrate into the insulating sheath of this cable, between its strands and / or its sheath, and be sucked by depression to eventually spread in the interconnection box and thus disrupt the correct operation of the electrical or electronic organs powered by this housing.

It is possible to avoid this disadvantage by locating the grounding points by the connection lugs in specific areas of the passenger compartment that always remain away from projections or water runoff. However, this solution is not possible if we always want to have mass connections that are very short.

It is also possible, after crimping the lug on the cable in a part thereof where the metal strands are exposed, make this area sealed by a subsequent addition of welding, which has the disadvantage of a recovery of cable after crimping by a manual operation, therefore necessarily expensive, and which does not have all the guarantees of efficiency and quality. However, this solution is binding, the use of solder by product, because of the components thereof, being highly regulated.

The foregoing considerations are more particularly concerned in the case of the crimping of a connection terminal of the end of a multi-stranded electrical cable for grounding. However, they apply in a similar way in the case where, to reduce the number of links with the mass by as many connection terminals, the strands are previously joined to a single wire provided with a single ground lug, the connection between this single wire and the strands of other cables being made by what is known in the art as a splice. At the right of the latter, the metal strands of the cables, suitably stripped for a sufficient length, are welded together, generally by the known technique known as ultrasound, and also soldered to the single grounding cable, the sealing being performed around this weld inside a casing or a similar envelope that surrounds the assembly, restoring the continuity of the sheaths of different son.

It is also known from DE 41 17 016 a crimping method of using an organic material inside a crimping element to fill the holes between the strands of two cables to seal a splice.

In addition, US Pat. No. 6,334,798 discloses a method for improving the connection between the metal of the terminal and the cable strands of depositing a resin on the crimping.

Finally, the document EP 1 235 305 discloses a method in which resin is deposited at the end of a cable to perform an overmolding.

However, this does not remove the possibility for water to pass from one wire to another within this confinement.

The present invention relates to a method for sealing a cable, and more particularly to a ground connection cable, in particular at a terminal connection with it, or a splice joining such a cable grounded with its terminal connection to several other cables, which can be implemented at the same time as the conventional operations of crimping the terminal or splicing, thereby avoiding further intervention and recovery of the cable , the method opposing the migration of a fluid, generally water, along the strands of this cable, between the terminal and / or the splice at one end and a device electrically connected to the cable provided with its pod at its opposite end, or other cables coming out of the splice.

The method according to the invention, applicable to a cable comprising a plurality of flexible metal strands, surrounded by an insulating protective sheath, is characterized in that it consists, after stripping one end of the strands by localized removal of the sheath of the cable for crimping a connecting lug or for joining said end by welding to the equally stripped end of the strands of other cables to form a splice, to crimp the lug or to weld the strands of the cables by laying on and between these strands a determined amount of a high wettability resin vis-à-vis the metal of these strands and their sheath, to fill the capillary interstices between them and / or their sheath so as to form a cap the end of the sheath to make the cable tight towards its opposite end.

Advantageously, the crimping of the lug or the welding of the strands is carried out simultaneously with the resin deposition.

In a first embodiment of the invention, in which a terminal lug is crimped on one end of the strands of the cable, this lug comprising a fastening lug extended by a crimping bracelet formed by two wings surrounding said end, the method consists in locally exposing these metal strands beyond the crimping ring of the terminal to a clamping ring of the cable sheath, at a distance from the terminal, and to crimping, the wings of the bracelet and the ring of clamping, respectively on bare strands and on the sheath of the cable, by depositing in the zone delimited between the bracelet and the ring, the determined quantity of resin ensuring the sealing of this cable.

Advantageously, the crimping of the wings of the bracelet and the crimping of the clamping ring are made concomitantly.

Advantageously, the deposition of the resin is carried out simultaneously with the crimping of the wings of the bracelet and / or the crimping of the clamping ring.

Advantageously, the crimping bracelet is cut, in line with the zone of deposit of the resin on the stripped strands of the cable, to form an indentation in the bracelet, through which the resin is deposited so that it is distributed and spreads easily on and between the strands.

In another embodiment of the invention, in which the strands of the cable are joined to the ends of the strands of other cables by welding to form a splice, the method consists in making the mechanical and electrical connection of the strands of the cables. , previously stripped, depositing the determined amount of resin to the connection of the strands to make them sealed towards their respective ends.

Advantageously, the deposition of the resin and the mechanical and electrical joining of the cables are carried out simultaneously.

Depending on the case, the resin deposited on the strands of the cable is highly surfactant, inert or capable of polymerizing in situ. In the case however, where the resin does not polymerize, it is preferably a hydrophobic product.

Usefully, the resin can be colored to allow optical control of its deposition and distribution between the strands by means of an automatic camera.

According to another characteristic of the process according to the invention, the resin is deposited by means of a tube, extending in a direction substantially perpendicular to that of the stripped strands of the cable, this tube preferably having a beveled end. or other, shaped to marry more closely the profile opposite these strands.

• la Figure 1 est une vue en perspective, partiellement éclatée, de l'extrémité d'un câble de masse et d'une cosse de connexion prévue pour être sertie sur cette extrémité au cours d'une opération réalisant simultanément l'étanchéité de ce câble;
• la Figure 2 est une vue de dessus, à légèrement plus grande échelle, du câble de la Figure 1, avec la cosse de connexion représentée montée sur son extrémité ;
• la Figure 3 est une vue schématique, en coupe longitudinale, de l'appareillage utilisé pour réaliser le sertissage de la cosse sur l'extrémité du câble et le rendre simultanément étanche par un dépôt de résine, conformément au procédé de l'invention ;
• les Figures 4, 5 et 6 sont des vues en coupe, respectivement selon les lignes IV-IV, V-V et VI-VI de la Figure 2, sur lesquelles apparaissent également les outils de sertissage illustrés sur la Figure 3 ;
• la Figure 7 est une vue schématique, en coupe longitudinale partielle, d'une variante où le procédé s'applique à une épissure entre plusieurs câbles.

Other features of a method according to the invention for sealing a cable to the right of a connecting lug or at the level of a splice link, will appear again through the following description of two examples of implementation. the work, given by way of indication and not limitation, with reference to the appended drawings in which:

• Figure 1 is a perspective view, partially exploded, of the end of a ground cable and a connecting lug intended to be crimped on this end during an operation simultaneously making the sealing of this cable ;
• Figure 2 is a top view, on a slightly larger scale, of the cable of Figure 1, with the connection terminal shown mounted on its end;
• Figure 3 is a schematic view, in longitudinal section, of the equipment used to perform the crimping of the terminal on the end of the cable and make it simultaneously sealed by a resin deposit, according to the method of the invention;
• Figures 4, 5 and 6 are sectional views respectively along the lines IV-IV, VV and VI-VI of Figure 2, on which also appear the crimping tools illustrated in Figure 3;
• Figure 7 is a schematic view, in partial longitudinal section, of a variant where the method is applicable to a splice between several cables.

In FIGS. 1 and 2, the reference numeral 1 denotes a conventional electrical connection cable formed by a set of flexible metal strands 2 surrounded by an insulating protective sheath 3, these strands 2 being in particular intended to be placed on the mass by a connection terminal 4, able to be crimped on one end of the cable 1.

For this purpose, the lug 4 comprises a lug 5 for fixing it on a support 6, not shown in Figure 1 but visible in Figure 2, constituting a suitable ground point, such as an element. the body of a motor vehicle (not shown). The lug 5 comprises for this purpose a central bore 7 for mounting a locking screw (also not shown in the drawing).

Conventionally, the connecting lug 4 comprises crimping means 8 on the end of the cable where the insulating sheath 3 is cut beforehand to expose bare metal strands 2, so as to allow a satisfactory electrical contact of these means 8 with these strands.

Also commonly, these means 8 comprise, firstly a crimping bracelet 9, comprising two separate wings, respectively 10 and 11, to clamp together the metal strands 2 in the part of these strands where the insulating sheath 3 has has been removed, on the other hand a clamping ring 12, also split, clean to surround and maintain the sheath 3 beyond the bracelet 9.

Figure 3 shows, in longitudinal section, the end of the cable 1 with its strands 2 and its insulating sheath 3. This figure also shows schematically, the means for ensuring the crimping of the bracelet 9 on the metal strands 2 previously stripped and tightening the ring 12 on the sheath 3, these means comprising two punches or the like, respectively 13 to the right of the bracelet and 14 opposite the ring.

The punches 13 and 14, the details of which do not directly relate to the invention, co-operate with an anvil or the like 15 which is fixed and has grooves 16 (FIG. 4) and 17 (FIG. , to receive and hold in place the end of the cable 1, respectively right of the bracelet 9 and the ring 12.

The punches 13 and 14 themselves comprise, facing the grooves 16 and 17 of the anvil 15, recessed portions 18 and 19, the portion 18 being formed of two cylindrical elements 20 and 21 of axes transversely offset, so when applying the punch 13 to the bracelet 9 mounted in the groove 16 of the anvil 15, the two wings 10 and 11 of this bracelet are properly crushed on the strands 2 of the cable, conforming to a section substantially in the heart, the ends of the wings 10 and 11 bending towards the center of the cable so as to anchor in it and increase the locking effect of the bracelet 9 on the metal strands 2. During this operation, they undergo a partial deformation, called compaction, passing from a circular section to an approximately polygonal shape, as shown schematically in the sectional view of Figure 4.

Similarly, by cooperation of the clamping ring 12 with the punch 14 and the anvil 15, housed in the recessed portion 19 of the first and the groove 17 of the second, this time profiles substantially circular, this split ring is immobilized on the outer surface of the insulating sheath 3, the metal strands 2 inside this sheath retaining approximately their circular section.

According to the invention, the method then consists, as represented in FIG. 3, preferably simultaneously with the operations of crimping the bracelet 9 and tightening the ring 12, respectively on the stripped metal strands 2 at the end. of the cable and on the insulating sheath 3 in the manner indicated above, to be injected in the zone of the cable situated between the stripped strands 2 thereof, which are between the strap 9 and the ring 12, an appropriate quantity a resin or equivalent product, adapted to make the cable tight and in particular to eliminate any possibility of routing a liquid fluid, especially water, between these strands 2 inside the insulating sheath 3, at the beyond pod 4.

For this purpose, the crimping installation further comprises a tube 22, joined by a connection 23 to a source of resin 25 or a similar product, delivered by the end of this tube in the aforementioned region which separates the bracelet 9 of the ring 12. Advantageously, the wings 10 and 11 of the bracelet 9 are cut to present therein a notch 24, leaving free space between the bracelet and the ring for deposit there an appropriate amount 25 of the resin delivered by the tube 22.

Preferably, the end 26 of this tube through which the resin brought into contact with the strands 2 of the cable 1 has a bevelled shape in order to better match the profile of the strands in the transition zone between the ring and the bracelet. This resin 25 is preferably selected strongly surfactant and having a high coefficient of wettability vis-à-vis the metal which constitutes the strands 2 of the cable, usually copper. This resin can be inert or polymerizable, and if it does not polymerize, must have good hydrophobic properties to oppose the penetration of water into the interstices that form narrow capillary tubes between the strands 2 and between them. ci and the insulating sheath 3, and also between these strands to the crimping wrist strap 9 where, due to the partial crushing of the strands by the deformation of the wings 10 and 11, these interstices are even narrower.

In this zone, the resin put in place makes it possible to avoid the presence of air which may, over time, oxidize the copper strands and increase the contact resistance of these strands between each other and between these strands and the bracelet 9.

Thanks to these arrangements, these interstices initially filled with air, are progressively occupied by the resin which forms a rigid plug, making the cable perfectly tight and avoiding any upflow of water from the ground connection terminal to the ground. opposite end of the cable which enters a housing (not shown) where it can be directly connected to a device electrical or electronic control or control of the motor vehicle.

The method according to the invention has the advantage, apart from a particularly safe and effective sealing, of allowing the resin to be injected between the strands of the cable in masked time, simultaneously with the implementation of the operations of crimping the terminal, making any subsequent recovery of this cable unnecessary; this operation can also be performed in another workstation, preferably automatically.

FIG. 7 illustrates an alternative embodiment of the method of the invention, in which a cable 50, comprising, as previously, metal wires 51 surrounded by an insulating sheath 52, comprises at one of its ends a connection lug 53 whose structure is identical to that adopted in the previous example, the crimping bracelet may be devoid of the indentation marked 24 in this first example.

In the present case, the ground cable 50 is intended to be joined to several similar cables 54 and 55 by a splice, schematically designated as a whole under the reference 56, the cables 54 and 55 being connected directly to sealed housings ( not shown).

In this case, the metal strands 57 and 58 of the cables 54 and 55 are stripped beyond their own sheath, respectively 59 and 60, and are directly welded to the equally stripped ends of the strands 51 of the first cable 50, this weld by way of example by conventional ultrasonic welding equipment, comprising two electrodes respectively 61 and 62, fixed on electrode holders 63 and 64 joined to a suitable voltage source and to a control device ( not shown), classic for this type of operation.

According to the invention, one of the electrode carriers, in this case the electrode holder 63, is equipped with a tube 65 to bring a suitable quantity of resin 66 to the right of the welding zone between the strands 51, this resin 66, of the same nature as that used in the first example, allowing the right of the splice 56 to make the connection of the various strands perfectly tight and to prevent any water from the pod 53 and running between them strands 51 under the insulating sheath 52 of the first cable 50, does not cross the splice 56 and progresses beyond, through the capillary interstices between the strands and the sheaths, inside the cables 54 and 55.

The method of the invention has particularly advantageous advantages since, as already indicated above, it makes it possible to perform the deposition of the resin at the same time as the crimping of the terminal. In addition, an excellent seal is obtained since it consists in making a resin plug at the end of the sheath, the resin filling the interstices between the strands and / or between these and the sheath and thus preventing any recovery of water inside the latter. Finally, a small amount of resin is sufficient since the result can be obtained with a plug of short length (of the order of a few millimeters or centimeter for the usual applications especially in the automotive field). In any case, the skilled person will determine depending on the nature and geometry of the cable, the amount of resin to obtain a sufficiently long plug to have a good seal and good mechanical strength.

Of course, it goes without saying that the invention is not limited to the examples more specifically described and represented above implementation of the method in question; on the contrary, it embraces all the variants and extends equally to the cables made waterproof by this method and the installations and assemblies, in particular on a motor vehicle, which use such sealed cables grounding or other.

Claims (13)

1. Method for sealing a cable, applicable to a cable (1, 50) comprising a plurality of flexible metal strands (2, 51), surrounded by an insulating protective sleeve (3, 52), characterised in that it consists, after one end of the strands has been stripped by localised removal of the sheath of the cable in order to crimp a connector terminal (4) thereto or to join said end by welding to the end, also stripped, of the strands (57, 58) of other cables (54, 55) in order to form a splice (56), in crimping the terminal or welding the strands of the cables while depositing on and between these strands a given amount of a resin (25, 66) that is highly wettable with respect to the metal of these strands and their sheath, in order to fill the capillary interstices between said strands and/or their sheath so as to form a plug at the end of the sheath in order to seal the cable in the direction of its opposite end.
2. Method according to Claim 1, characterised in that the crimping of the terminal or the welding of the strands is carried out simultaneously with the deposition of the resin.
3. Method according to Claim 1 or 2, in which a connector terminal (4) is crimped over one end of the strands (2) of the cable, this terminal comprising a mounting lug (5) extended by a crimping cuff (9) formed by two wings (10, 11) surrounding said end, characterised in that it consists in locally exposing these metal strands beyond the crimping cuff of the terminal as far as a compression ring (12) of the sheath (4) of the cable, at a distance from the terminal, and in carrying out the crimping of the wings of the cuff and the compression ring, on the stripped strands and the sheath of the cable respectively, while depositing, in the delimited zone between the cuff and the ring, the predetermined amount of resin (25) for sealing this cable.
4. Method according to Claim 3, characterised in that the crimping of the wings of the cuff and the crimping of the compression ring are carried out concomitantly.
5. Method according to Claim 3 or 4, characterised in that the deposition of the resin is effected simultaneously with the crimping of the wings of the cuff and/or the crimping of the compression ring.
6. Method according to any one of Claims 3 to 5, characterised in that the resin is also deposited in line with the crimping cuff (9).
7. Method according to one of Claims 3 to 6, characterised in that the crimping cuff (9) is cut out, in line with the zone where the resin (25) is deposited on the stripped strands (2) of the cable, so as to form a notch (24) in the cuff.
8. Method according to Claim 1, in which the strands (51) of the cable are joined to the ends of the strands (57, 58) of other cables by welding in order to constitute a splice, characterised in that it consists in making the mechanical and electrical join of the strands of the cables, previously stripped, by depositing the given amount of resin (66) at the connection of the strands in order to seal them in the direction of their respective ends.
9. Method according to Claim 8, characterised in that the deposition of the resin and the mechanical and electrical joining of the cables are carried out simultaneously.
10. Method according to any one of Claims 1 to 9, characterised in that the resin (25, 66) deposited on the strands (2, 51) of the earth conductor is strongly surface-active, inert or likely to polymerise in situ.
11. Method according to any one of Claims 1 to 10, characterised in that, if the resin does not polymerise, it is constituted by a hydrophobic compound.
12. Method according to one of the preceding claims, characterised in that the resin (25, 66) is coloured in order to allow a visual inspection of its deposition and its distribution among the strands.
13. Method according to any one of Claims 1 to 12, characterised in that the resin (25, 66) is deposited by means of a tube (22, 65), extending in a direction substantially perpendicular to that of the stripped strands (2, 51) of the cable, this tube preferably having a bevelled end, shaped so as to fit as closely as possible against the profile facing these strands.

Images