EP1463149A1 - Process for making a multicore earth 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 to seal a multi-strand connecting cable, in particular a grounding cable, either provided an electrical connection terminal, in particular with part of the body or other massive structure analog of a motor vehicle, either connected to other similar cables by a splice, and also relates to cables sealed by this process as well as the electrical devices to which these waterproof cables are connected.

In a motor vehicle are usually used multiple electrical devices or command or control electronics, mounted on if necessary in closed protective boxes these devices being combined at the exterior by connection cables comprising usually each several metal strands flexible, housed inside a sheath or insulating jacket.

When the internal volume, closed and sealed, of these boxes are subject to variations of temperature, frequent according to their conditions of use and their location in the vehicle, as well because of the external environment, correlatively occurs inside these housings, a variation of internal pressure, this the latter may, as the case may be, become higher lower than ambient pressure.

When this volume delimited by the case is connected to the outside by connection cables electrical, including grounding, these pressure variations are exerted at the end of wires or strands of these cables which ends up in the case, and can be transmitted to each other end, located outside of it.

So if the electrical cable is made up 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 waterproof due in particular to the game between these strands and between them and their sheath, so the aforementioned pressure variations are transmitted from one end to the other. Moreover, the interstices between the strands being very narrow, these behave like capillary tubes vis-à-vis the liquid fluids which can bathe their end, outside the housing.

The classical physical laws of Laplace or Jurin, which govern the wetting process of surfaces by fluids, in particular by a liquid, and the physical behavior of the tubes capillaries, demonstrate that with a liquid fluid with high wettability with respect to the metallic material of the strands conductors, this liquid can travel over a large length and in particular a great height if the cable is arranged substantially in one position vertical, between these strands, this height being linked at the surface tension of the liquid and vice versa proportional to the radius of the capillary tubes as well 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 industry automotive, the ends of the connecting cables are either joined to a housing supplying an organ any electric vehicle or box waterproof interconnection, or are arranged at the interior of the passenger compartment itself, in an area which stays dry all the time. However, opposite ends, in the case of cables of grounded, are usually attached directly by connection lugs with the body of the vehicle and are thus subject to projections of water, or even a possible complete immersion in a liquid medium, immersion which can be temporary but which can also be prolonged during a notable duration.

Under these circumstances, the water that wets the ground lug and / or cable connection strands connected to it, can enter the sheath insulating this cable, between its strands and / or its sheath, and be vacuumed to finally spread in the interconnection box and thus disrupt the correct functioning of electrical or electronic components powered by this case.

This can be avoided by locating the grounding points by the connection lugs in specific areas of the passenger compartment which always stay away from splashes or runoff. However, this solution is not possible if one wishes always have ground connections that are very short.

You can also, after crimping the terminal on the cable in a part of it where the metal strands are laid bare, make this area waterproof by a subsequent addition of solder, which has the disadvantage of a cable recovery after crimping by manual operation, so necessarily expensive, and which does not present all guarantees of efficiency and quality. However, this solution is binding, the use welding by addition of product, due to components of it, being highly regulated.

The above considerations are more particularly concerned in the case of crimping a terminal connection terminal a multi-strand electrical grounding cable. However, they apply similarly in the case where, to reduce the number of connections with the mass by as many connection lugs, the strands are previously joined to a single wire provided a single ground terminal, the connection between this wire single and the strands of other cables being carried by what is called in the art a splice.

To the right of the latter, the strands metallic cables, suitably stripped on sufficient length, are welded together, general by the known technique called ultrasound, and also soldered to the single grounding cable mass, sealing being carried around this welding inside a case or a similar envelope which surrounds the whole, in restoring the continuity of the sheaths of the different son. However, this does not remove the possibility for the water to go from one wire to another at inside this confinement.

The subject of the present invention is a method to seal a cable, and more particularly a ground connection cable, especially at a connection terminal with this one, or even a splice bringing together such earth cable with its connection terminal to several other cables, which can be implemented together with the classic operations of crimping the terminal or making the splice, which avoids any intervention the cable, the process opposing the migration of a fluid, generally water, along the strands of this cable, between the terminal and / or splice at one end and one device electrically connected to the cable provided with its terminal at its opposite end, or to other cables coming out of the splice.

The invention also relates to cables and connection splices made watertight by placing work of this process.

To this end, the method according to the invention, applicable to a cable comprising a plurality of flexible metal strands, surrounded by a sheath protective insulation, characterized in that it consists, after having stripped one end of the strands by local removal of the cable sheath to crimp a connection terminal or to join said welded end at the end also stripped of the strands of other cables to form a splice, for crimping the terminal or soldering of cable strands by depositing preferably simultaneously on and between these strands a determined amount of a high strength resin wettability with respect to the metal of these strands and of their sheath, in order to fill the interstices capillaries between them and / or their sheath for seal the cable in the direction of its opposite end.

In a first form of implementation of the invention, in which a terminal of connection on one end of the cable strands, this terminal having a fixing lug extended by a crimp bracelet formed by two wings surrounding said end, the process consists in exposing these strands locally metal beyond the crimp bracelet of the lug up to a tightening ring of the sheath of the cable, away from the terminal, and make the crimping, preferably concomitant, of the wings of the bracelet and clamping ring, respectively on the bare strands and on the cable sheath, in preferably depositing simultaneously in the area between the bracelet and the ring, the quantity determined resin ensuring the tightness of this cable.

Advantageously, the bracelet is cut out. crimping, to the right of the deposit area of the resin on the bare strands of the cable, to form a notch in the bracelet, through which we deposit the resin so that it is distributed and spreads easily on and between strands.

In another form of implementation of the invention, in which the strands of the cable at the ends of the strands of other cables by welding to form a splice, the process consists in making the mechanical junction and electrical strands of these cables, previously stripped, preferably depositing simultaneously the determined amount of resin at the strand bond to make them waterproof towards their respective ends.

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

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

According to another characteristic of the process according to the invention, the resin is deposited by means of a tube or the like extending in a direction substantially perpendicular to that of the stripped strands of the cable, this tube having preferably a beveled end or the like, shaped to closely match the profile in look of 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 characteristics of a method according to the invention for sealing a cable at the level of a connection terminal or at a connection splice, will become more apparent from the following description of two examples of layout. work, given for information and not limitation, with reference to the accompanying drawings in which:

• Figure 1 is a perspective view, partially exploded, of the end of a ground cable and a connection lug intended to be crimped on this end during an operation simultaneously sealing 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 apparatus used to crimp the terminal on the end of the cable and simultaneously make it waterproof by a deposit of resin, according to the method of the invention;
• Figures 4, 5 and 6 are sectional views, respectively along 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 applies to a splice between several cables.

In Figures 1 and 2, reference 1 designates 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 ground by a connection terminal 4, able to be crimped on one end of the cable 1.

For this purpose, the terminal 4 has a tab 5 for fixing it on a support 6, not shown in Figure 1 but visible on the Figure 2, constituting an appropriate ground point, such as in particular that an element of the body of a motor vehicle (not shown). Leg 5 includes for this purpose a central bore 7 for the mounting a locking screw (also not shown on the drawing).

Conventionally, the connection terminal 4 has crimping means 8 on the end of the cable where the insulating sheath 3 is previously cut to reveal bare strands metallic 2, so as to allow contact electric satisfying these 8 means with these strands.

Also usually, these means 8 comprise, on the one hand, a crimping bracelet 9, comprising two separate wings, respectively 10 and 11, to clamp the metal strands 2 together in the part of these strands where the insulating sheath 3 has been removed, on the other hand a clamping ring 12, also split, suitable for surrounding and hold 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 sheath insulating 3. This figure also represents schematically, the means to ensure the crimping of bracelet 9 on the strands metallic 2 previously stripped and tightening the ring 12 on the sheath 3, these means comprising two punches or the like, respectively 13 to right of the bracelet and 14 opposite the ring.

Hallmarks 13 and 14, including the detail of the realization does not directly matter to the invention, cooperate with an anvil or the like 15, fixed, and with grooves, respectively 16 (Figure 4) and 17 (Figure 5), to receive and maintain place the end of cable 1, right respectively bracelet 9 and ring 12.

The punches 13 and 14 themselves include, in look of the grooves 16 and 17 of the anvil 15, recessed parts 18 and 19, part 18 being formed of two cylindrical elements 20 and 21 of axes offset transversely, so that when of the application of the punch 13 on the bracelet 9 mounted in the groove 16 of the anvil 15, both wings 10 and 11 of this bracelet are suitably crushed on the strands 2 of the cable, conforming according 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 blocking effect of bracelet 9 on the metal strands 2. During this operation, these undergo a partial deformation, called compaction, passing from a circular section to a approximately polygonal shape, as shown schematically on 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 hollowed out part 19 of the first and the groove 17 of the second, with profiles this time appreciably circular, this split ring is immobilized on the outer surface of the insulating sheath 3, the strands metallic 2 inside this sheath keeping their section approximately here circular.

According to the invention, the method then consists, as shown in Figure 3, preferably from simultaneously with crimping operations of the bracelet 9 and tightening of the ring 12, respectively on the bare metal strands 2 to the end of the cable and on the insulating sheath 3 of as indicated above, to be injected into the cable area between the bare strands 2 of this one, which are between bracelet 9 and the ring 12, an appropriate amount of a resin or equivalent product, suitable for sealing the cable and in particular to remove any possibility of flow of a liquid fluid, in particular water, between these strands 2 inside the insulating sheath 3, beyond the terminal 4.

For this purpose, the crimping installation additionally comprises a tube 22, joined by a bond 23 to a resin source 25 or a product similar, delivered by the end of this tube in the aforementioned region which separates bracelet 9 from the ring 12. Advantageously, the wings 10 and 11 of bracelet 9 are cut to present in this one notch 24, leaving free space sufficient between the bracelet and the ring so that deposits an appropriate amount 25 of the resin delivered by the tube 22.

Preferably, the end 26 of this tube by which leaves the resin brought into contact with the strands 2 of cable 1, has a beveled shape so to match as best as possible the profile of the strands in the area of transition between the ring and the bracelet. This resin 25 is preferably chosen strongly surfactant and having a high coefficient of wettability with respect to the metal which constitutes the 2 strands of cable, usually copper. This resin may be inert or polymerizable, and if it does not polymerize, must have good hydrophobic properties to oppose the penetration of water into the interstices which form narrow capillary tubes between the strands 2 and between them and the insulating sheath 3, and also between these strands to the right of the bracelet crimping 9 where, due to the partial crushing of strands by the deformation of the wings 10 and 11, these interstices are even narrower.

In this area, the resin put in place allows avoid the presence of air which can, over time, oxidize the copper strands and increase the contact resistance of these strands with each other and between these strands and the bracelet 9.

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

The method according to the invention presents the advantage, apart from sealing particularly safe and effective, to allow inject the resin between the strands of the hidden time cable, simultaneously with setting work of terminal crimping operations, making it unnecessary for any subsequent resumption of this cable ; this can also be done in another workstation, preferably in automatic.

Figure 7 illustrates an alternative layout work of the method of the invention, where a cable 50, comprising as before metal strands 51 surrounded by an insulating sheath 52, comprises one of its ends a connection terminal to the mass 53 whose structure is identical to that adopted in the previous example, the bracelet crimping can be devoid of the notch marked 24 in this first example.

In this case, the ground cable 50 is designed to be connected to several similar cables 54 and 55, by a splice, schematically designated as a whole under reference 56, the cables 54 and 55 being connected directly to housings waterproof (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 on the equally stripped ends of the strands 51 of the first cable 50, this solder by way of example by an apparatus conventional ultrasonic welding, comprising two electrodes 61 and 62 respectively, fixed on electrode holders 63 and 64 joined to a source of appropriate voltage and control device (not shown), classic for this type operation.

According to the invention, one of the electrode holders, in this case the electrode holder 63 is equipped with a tube 65 to bring an appropriate amount of resin 66 to the right of the weld zone between the strands 51, this resin 66, of the same nature as that used in the first example, allowing the right of splice 56 to make the bond of various strands perfectly waterproof and avoid that any water from pod 53 and traveling between the strands 51 under the insulating sheath 52 of the first cable 50, does not cross the splice 56 and progresses beyond, through the gaps capillaries between the strands and the sheaths, the inside of cables 54 and 55.

The process of the invention presents particularly interesting advantages since, as already indicated above, it allows to perform depositing the resin at the same time as the crimping of the terminal. In addition, we obtain a excellent sealing since it consists in making a resin plug at the end of the sheath, the resin filling the gaps between the strands and / or between these and the sheath and thus preventing any upwelling inside this last. Finally, a small amount of resin suffices since the result can be obtained with a short plug (of the order of a few millimeters or centimeter for applications common especially in the automotive field). Of anyway, the skilled person will know how to determine depending on the nature and geometry of the cable, the amount of resin to obtain a cap long enough to have good tightness and good mechanical resistance.

Of course, it goes without saying that the invention does not not limited to the more specifically described examples and shown above of implementation of the process considered; on the contrary it embraces all variants and extends equally to cables sealed by this process and to installations and assemblies, in particular on a vehicle automotive, which use such waterproof cables from grounding or others.

Claims (11)

Method for sealing a cable, in particular a grounding cable, applicable to a cable (1.50) comprising a plurality of flexible metallic strands (2.51), surrounded by an insulating protective sheath (3.52) , characterized in that it consists, after having stripped one end of the strands by local removal of the cable sheath to crimp a connection terminal (4) or to join said end by welding to the also stripped end of the strands ( 57.58) of other cables (54.55) to form a splice (56), for crimping the terminal or welding the cable strands by preferably depositing simultaneously on and between these strands a determined amount of a resin (25,66) with high wettability vis-à-vis the metal of these strands and their sheath, in order to fill the capillary interstices between them and / or their sheath to make the earthing cable waterproof towards its opposite end . Method according to claim 1, in which a connection terminal (4) is crimped on one end of the strands (2) of the cable, this terminal comprising a fixing lug (5) extended by a crimping strap (9) formed by two wings (10,11) surrounding said end, characterized in that it consists in locally exposing these metal strands beyond the crimping strap of the terminal up to a tightening ring (12) of the sheath (4) of the cable, at a distance from the terminal, and to carry out the crimping, preferably concomitant, of the wings of the bracelet and of the tightening ring, respectively on the stripped strands and on the sheath of the cable, preferably depositing simultaneously in the zone delimited between the bracelet and the ring, the determined quantity of resin (25) ensuring the tightness of this cable. Method according to claim 2, characterized in that the resin is also deposited in line with the crimping strap (9). Method according to one of claims 2 or 3, characterized in that the crimping strap (9) is cut, in line with the resin deposition zone (25) on the stripped strands (2) of the cable, to form a notch (24) in the bracelet. 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 to constitute a splice, characterized in that it consists in making the mechanical junction and electric strands of these cables, previously stripped, preferably simultaneously depositing the determined quantity of resin (66) at the connection of the strands to make them watertight towards their respective ends. Process according to any one of Claims 1 to 5, characterized in that the resin (25,66) deposited on the strands (2, 51) of the grounding cable is highly surfactant, inert or capable of polymerizing in situ. Process according to any one of Claims 1 to 5, characterized in that , if the resin does not polymerize, it consists of a hydrophobic product. Method according to one of the preceding claims, characterized in that the resin (25,66) is colored to allow an optical control of its deposition and of its distribution between the strands. Method according to any one of Claims 1 to 8, characterized in that the deposition of the resin (25,66) is carried out by means of a tube (22,65) or similar member, extending in one direction substantially perpendicular to that of the bare strands (2,51) of the cable, this tube preferably having a beveled end or the like, shaped to closely match the profile facing these strands. Multi-strand waterproof cable, particularly for placing to the mass, obtained by the process according to one any of claims 1 to 9. Electric control or monitoring device control, especially for vehicle equipment automobile, comprising at least one cable according to the claim 10.

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