EP2255417B1 - Method for accelerating individual electromagnetic shielding of a strand of an electrical cable on an electric connector - Google Patents

Description

The present invention relates to a method of taking up the electromagnetic shielding of individual electric cables of a strand on an electrical connector. The invention applies in particular to connection cables used in the aeronautical industry.

In order to ensure optimum protection of the conducting cables, it is desirable to establish an electromagnetic continuity between the individual shielding of the strand cables and the connector, more particularly its rear connection. To do this, it is known to integrate in a rear connection of the connector recovery means of the individual shielding of the cables.

The patent EP 0 739 057 describes an example of such a rear connection, said remote recovery. The end sections of the cables are stripped from their individual shielding coatings, so that each coating thus pulled out from the corresponding cable forms a unitary shielding strand, referred to as a "pigtail", extending from a terminal portion undocked strand. These strands are brought back on an anvil ring at the back of the fitting. A braid crimped on the front of the connector is then crimped via a crimp ring over the individual cable shielding coatings.

The mechanical stresses exerted by the fastening means on the anvil, however, tend to deteriorate the shielding coatings. The portion of strand between the front clamping nut of the connector and the anvil is very fragile. The free length of the strands (about 5 to 10 cm.), Due to the distance between the anvil and the connector and the play necessary to not stress the strands, increases the transmission defects related to crosstalk and deteriorates as well. the electromagnetic protection performance of shielding thus connected. In addition, at each disassembly for maintenance or repair operations and for reassembly, it is necessary to cut the damaged ends by crimping the single strands of shielding. It is therefore necessary to provide an extra length for these strands.

International demand WO 96/33524 describes another example of such a connector rear connector, said chimney. Here, the fireplace is removable. The strands or pigtails are returned to the rear chimney of this rear connection where they are connected by crimping, metal band, shape memory ring, shrinking spring, etc. As in the previous example, the free length (that is to say without effective electrical contact) of the pig tails deteriorates the electromagnetic protection performance of the shielding coatings thus connected, especially since an excess length of the strands is necessary to allow at least two disassemblies for maintenance or repair. The mechanical stresses exerted by the fixing means on the chimney also tend to deteriorate the shielding coatings. Finally, the diameter of the rear outlet of the connection must necessarily be adapted to the diameter of the strand, which implies to provide a large number of different connection references to adjust the diameter of the strand: this solution is very expensive.

There are other types of connector rear connection comprising means for taking up the individual shielding of the cables, such as so-called gland or crimped or lug connections, in which the pigtails are brought back to a cable gland system. or on a point of attachment by lug provided on the fitting. These connections, however, pose substantially the same difficulties as mentioned above in terms of mechanical stresses on the strands, the length of the latter or adaptation of the connection to the diameter of the strand.

US 7,119,281 also discloses a method in which the single shielding strands are brought back to a gland system having comparable disadvantages.

The present invention aims to avoid these drawbacks by proposing a simple and inexpensive method of taking up individual shielding of the cables of a connector, where the strands will not be damaged by the connection means, and making it possible to optimize the length of the strands. shielding units and limit the number of rear connection references to be provided depending on the size of the strand.

• dénuder des tronçons d'extrémités des câbles de leurs revêtements de blindage individuel, de sorte que chaque revêtement ainsi dégagé du câble correspondant forme un brin unitaire de blindage s'étendant à partir d'une portion terminale du toron non déblindé ;
• raccorder lesdites extrémités des câbles au connecteur ;
• enrouler une bande de bourrage conducteur autour de ladite portion terminale du toron jusqu'à ce que le diamètre de cette dernière atteigne une valeur prédéterminée, tout en retroussant et répartissant lesdits brins unitaires de blindage, de façon homogène sur la circonférence de la portion terminale du toron, dans au moins un ou deux enroulements successifs de la bande de bourrage ; caractérisé en ce qu'il consiste à :
• ceindre ladite bande de bourrage enroulée autour de la portion terminale du toron au moyen d'une lame de ressort de frettage de forme annulaire;
• ceindre la lame de ressort de frettage entre deux demi-coquilles électriquement conductrices comportant des moyens d'accouplement complémentaires ;
• accoupler lesdites demi-coquilles l'une à l'autre et les raccorder mécaniquement et électriquement au connecteur.

To this end, the subject of the invention is a method for recovering the individual electromagnetic shielding of electrical cables from a strand to an electrical connector, said method consisting in:

• stripping ends of the cables sections of their individual shielding coatings, so that each coating thus released from the corresponding cable forms a unitary shielding strand extending from an end portion of the undewinded strand;
• connect said ends of the cables to the connector;
• winding a conductive filler strip around said terminal portion of the strand until the diameter thereof reaches a predetermined value, while rolling up and distributing said single strands of shielding, homogeneously over the circumference of the terminal portion of the strand strand in at least one or two successive windings of the stuffing strip; characterized in that it consists of:
• encircling said stuffing strip wound around the end portion of the strand by means of a ring-shaped shrinking spring leaf;
• encircling the shrinking spring blade between two electrically conductive half-shells comprising complementary coupling means;
• coupling said half-shells together and mechanically and electrically connecting them to the connector.

The conductive padding strip makes it possible to bridge the gap between a strand and its connection, whatever the diameter of the strand, and not to excessively constrain the strands of the individual shielding of the cables. The length of pig tails is reduced to a few millimeters.

According to an advantageous possibility, said end portion of the strand is surrounded by a protective tape before winding the stuffing strip around the end portion of the strand thus wrapped. This tape is used to mechanically protect the cables of the strand.

In one embodiment, the electrical connection of the two half-shells to the connector is achieved by means of an annular shoulder formed at the front of an outer wall of the half-shells and provided to be clamped against an inner annular wall of a rear connector connector.

In another embodiment, the electrical connection of the two half-shells to the connector is made by means of an annular toothing arranged in front of the half-shells and designed to mate with a toothing of shape complementary to the connector.

According to an advantageous possibility, the mechanical connection of the two half-shells to the connector is made by means of a rear nut in which the assembly of the half-shells and the shrinking spring leaf are housed and supported, said nut rear screwing on a threaded portion of the connector or the rear connector connector. The rear nut makes it possible to control the tightening torque exerted and the pressurization of the assembly.

The coupling means of the half-shells comprise, for example, an indentation oriented tangentially and made to a first end of the arc formed by each half-shell, and a complementary shape of teeth and made at the other end of the arc.

• les figures 1 à 4 sont des vues schématiques longitudinales illustrant quatre stades successifs de mise en oeuvre d'un premier exemple de procédé de reprise du blindage individuel des câbles d'un toron sur un connecteur électrique ;
• la figure 5 est une vue en coupe selon la ligne V-V de la figure 4 ;
• les figures 6 et 7 sont des vues longitudinales partiellement en coupe illustrant les dernières étapes du procédé ;
• la figure 8 est une vue de face illustrant l'assemblage de deux demi-coquilles apparentes sur les figures 6 et 7 ; les figures 8a et 8b sont des vues de détail de moyens d'accouplement des demi-coquilles de la figure 8 ;
• la figure 9 est une vue en coupe selon la ligne IX-IX de la figure 8 ;
• la figure 10 est une vue en coupe longitudinale d'un écrou arrière apparent sur les figures 6 et 7 ;
• les figures 11 à 15 sont des vues analogues aux figures 6 à 10 et illustrant un second exemple de procédé selon l'invention.

This method is applicable regardless of the type, size or number of cables. The invention will in any case be better understood and other advantages thereof will appear more clearly in the light of the description of two embodiments, given by way of nonlimiting examples and with reference to the accompanying drawings, in which: which :

• the Figures 1 to 4 are schematic longitudinal views illustrating four successive stages of implementation of a first example of a method of recovery of the individual shielding of the cables of a strand on an electrical connector;
• the figure 5 is a sectional view along line VV of the figure 4 ;
• the Figures 6 and 7 are longitudinal views partially in section illustrating the last steps of the process;
• the figure 8 is a front view illustrating the assembly of two apparent half-shells on the Figures 6 and 7 ; the Figures 8a and 8b are detailed views of coupling means of the half-shells of the figure 8 ;
• the figure 9 is a sectional view along the line IX-IX of the figure 8 ;
• the figure 10 is a longitudinal sectional view of an apparent rear nut on the Figures 6 and 7 ;
• the Figures 11 to 15 are views similar to Figures 6 to 10 and illustrating a second example of a process according to the invention.

The figure 1 is a plurality of shielded electrical cables 1 and 1 having contact terminations 4. A first step of the method consists in stripping end sections of the strand 1 cables of their individual shielding coatings, so that each coating thus released from the 3 corresponding bare cable forms a strand unitary shielding 2, called "pigtail", which extends from an end portion of the strand 1 undewinded.

As indicated on the figure 2 , the terminations 4 of the cables are connected to an electrical connector 8, and a taping 5 is wound around the end portion of the strand 1. This tape 5 provides mechanical protection of the strand 1 cables.

A conductive tamping strip 6 is then (see figure 3 ) wrapped around the wrapped end portion of the strand 1, while the unitary shielding strands 2 are rolled up, distributing them homogeneously over the circumference of the end portion of the strand 1, in successive windings of the stuffing strip 6 This winding operation of the stuffing strip 6 continues until the diameter of this end portion of the strand 1 reaches a predetermined value.

Finally, as indicated on figures 4 and 5 the stuffing strip 6, wrapped around the end portion of the strand 1, is encircled and clamped by a constant-force annular shrink spring blade 7. The process is identical regardless of the size of the connector 8 or the strand 1, the type or number of cables.

The same electrical potential of the shielding 2 of the cables and the connector 8 is made by means of two half-shells 12 (see FIG. Figures 6 to 8 ).

A front portion (i.e. left on the longitudinal views) of the hooping spring blade 7 is enclosed between the two electrically conductive half-shells 12 coupled to each other and connected to a coupling rear 31 electrically conductive connector 8. Here, the rear connection 31 is straight but it could very well be bent, for example at 45 ° or 90 °.

An inner annular shoulder 24 of the two half-shells 12 bears on this front portion of the shrinking spring blade 7. An inner annular wall 23 of the two half-shells 12 abuts against the hooping spring blade 7 and ensures thus the centering and the good positioning of the latter.

The electrical connection of the two half-shells 12 to the rear connector 31 of the connector 8 is formed by means of an annular shoulder 29 formed at the front of an outer annular wall 22 of the two assembled half-shells 12 (see FIG. figure 9 ). The annular shoulder 29 is clamped in abutment against an inner annular wall of the rear connector 31 (see FIG. figure 7 ).

The shoulders 24 and 29 of the half-shells 12 are part of the path taken by the possible currents from the individual shielding wires 2 to the connector 8.

The coupling means of the half-shells 12 (see Figures 8a and 8b ) comprise an indentation 27 oriented tangentially and made at a first end of the arc formed by the half-shell 12, and a toothing 28 of complementary shape to said indentation and made at the other end of the arc. These two pairs of indentation 27 and toothing 28 form a self-centering system which provides a baffle for the electromagnetic waves. This system makes it possible to limit as much as possible the penetration of the electromagnetic disturbances in the Faraday chamber formed by the connection 31.

The mechanical connection of the two half-shells 12 to the connector 8 is achieved by means of a rear nut 9 in which the assembly of the half-shells 12 and the shrinking spring blade 7 are housed and supported. The rear nut 9 is screwed by a threaded portion 17 (see figure 10 ) on a threaded part The rear nut 9 is a hexagon nut 25 for torque tightening. He does not conduct electricity.

The outer annular wall 22 of the two half-shells 12 allows their centering and their good positioning in support against an inner annular wall 19 of large diameter of the rear nut 9. An inner annular wall 20 of small diameter defining a well of the The rear nut 9 ensures the centering and the correct positioning of the shrinking spring blade 7. An anti-friction washer 13 is disposed at the bottom 21 of the well of the rear nut 9. The shrinking spring blade 7 receives the pressure of the bottom of the well 21 of the rear nut 9 through the support washer 13. An O-ring 14 placed in an annular groove 18 formed on the inner wall 19 of the rear nut 9 seals between the rear nut 9 and the coupling 31.

The hooping spring blade 7 provides a compression of the stuffing 6 on the shielding strands 2 and a geometric consistency of the end portion of the strand 1 thus coated in terms of diameter (adapted to the rear connection) and width (bearing surface , that one does not try to deform, for the mechanical locking of the rear nut 9).

In a manner known per se, a sealing sleeve 11 is installed on the strand 1, then a heat-shrinkable part 10 seals between the rear nut 9 and the sleeve 11 by sealing bonding.

Thanks to this method, the shielding strands 2 are not damaged by the connection, their length is moderate and the cables are protected inside the connection 31.

Another example of a method according to the invention is shown in the following figures 11 to 15. Here, the number of parts has been optimized, but this optimization can only be suitable for a straight connection. The function of connection to the connector is here ensured by the half-shells 34. This is why the outer wall 22 of the half-shells 24 is strongly prolonged (see figure 14 ). The large diameter inner wall 19 of the rear nut 35 is also extended to the same extent (see figure 15 ).

The electrical connection is made directly between the two half-shells 34 and the connector 8 by means of a ring-shaped connecting gear 16 (see FIG. Figures 13 and 14 ) is formed at the front of the half-shells 34. This toothing 13 is designed to mate with a toothing 15 of complementary shape of the connector 8. The shape of the connecting toothing 16 of the half-shells 34 depends on the standard of which raises the connector 8 which receives this connection. The teeth 15 and 16 are part of the path through which any currents going from the individual shields 2 of the cables 1 to the connector 8 circulate.

It is also possible to add to the recovery of the individual shielding cables an additional system, already known elsewhere, recovery of the general shielding (for example a metal braid, a metal overbraid, an open shielded sheath ...) of the strand 1. In this case, the rear nut (9 or 35) must conduct electricity.

The invention also makes it possible to carry out repairs or evolutions of an electrical harness without the need for specific tools, electrical sources or heat, without the need to degas the aircraft beforehand, or to locate each cable.

As is obvious, and as is apparent from the foregoing, the invention is not limited to the only embodiments described above; it embraces, on the contrary, all the embodiments and applications within the scope of the following claims.

Claims (6)

1. A method of extending the individual electromagnetic shielding of electrical cables (3) of a cable-strand (1) to an electrical connector (8), consisting in:

   a) stripping end segments of the cables (3) of their individual shielding coverings so that each covering as removed in this way from the corresponding cables (3) forms a unit shielding pigtail (2) extending from a terminal portion of the strand (1) from which the shielding has not been removed;

   b) connecting said ends (4) of the cables (3) to the connector (8);

   c) winding a conductive packing strip (6) around said terminal portion of the strand (1) until the diameter thereof reaches a predetermined value, while folding back and distributing said unit shielding pigtails (2) in uniform manner around the circumference of the terminal portion of the strand (1) within at least one or two successive turns of the packing strips (6); characterized in that it consists in:

   d) surrounding said packing strip (6) wound around the terminal portion of the strand (1) with a reinforcing spring blade (7) of annular shape;

   e) surrounding the reinforcing spring blade (7) within two electrically-conductive half-shells (12; 34) including complementary coupling means (27, 28); and

   f) coupling said half-shells (12; 34) to each other and connecting them mechanically and electrically to the connector (8).
2. A method of extending shielding according to claim 1, characterized in that said terminal portion of the strand (1) has protective tape (5) therearound before the packing strip (6) is wound around the terminal portion of the strand (1) as taped in this way.
3. A method of extending shielding according to claim 1 or claim 2, characterized in that the electrical connection between the two half-shells (12) of the connector (8) is provided by means of an annular shoulder (29) formed at the front of an external wall (22) of each half-shell (12) and designed to be clamped against an internal annular wall of a backcoupling (31) of the connector (8).
4. A method of extending shielding according to claim 1 or claim 2, characterized in that the electrical connection between the two half-shells (34) of the connector (8) is provided by means of an annular set of teeth (16) formed at the front of the half-shells (34) and designed to couple with a set of teeth (15) of complementary shape of the connector (8).
5. A method of extending shielding according to claim 3 or claim 4, characterized in that the mechanical connection between the two half-shells (12; 34) and the connector (8) is provided by means of a rear nut (9; 35) in which the assembly of said half-shells (12; 34) together with the reinforcing spring blade (7) is received and comes to bear, said rear nut (9; 35) being screwed onto a threaded portion of the connector (8) or of the backcoupling (31) of the connector (8).
6. A method of extending shielding according to any one of claims 1 to 5, characterized in that the coupling means of the half-shells (12; 34) comprise a tangentially-oriented indentation (27) formed at a first end of the arc formed by each half-shell (12; 34), and a projection (28) of complementary shape formed at the other end of the arc.

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