EP0020241B1 - Connecting device for insulated electrical conductors - Google Patents

Abstract

PCT No. PCT/FR80/00084 Sec. 371 Date Jan. 25, 1981 Sec. 102(e) Date Jan. 13, 1981 PCT Filed May 21, 1980 PCT Pub. No. WO80/02775 PCT Pub. Date Dec. 11, 1980.A connector for self-stripping insulated electric conductors, said conductor including a fork or clip type conductive connection part with at least two resilient arms between which is provided a slot for inserting the electric conductor to be connected, the connection part being designed for inserting in a cavity in a stand made of insulating material. The double fork type connection part (75) has two inclined slots (64, 65) whose axes converge towards the top of the connector. Application to electric connections, in particular in telecommunications.

Description

The invention relates to a device for connecting insulated electrical conductors by a insulation displacement connector comprising a connecting conductive piece of the double elastic fork type, making inclined slots between its branches, the axes of which converge towards the top of the connector, and into which are inserted. electrical conductors to be connected, the connection part being intended to be inserted into a cell of a base made of insulating material.

Such devices are known, for example from document GB-A-906,665. In this case, the slots are obtained by removing a metal strip by cutting, then by folding the branches so that the tops of the two branches touch each other. Such slots therefore widen towards the bottom, which makes it necessary to add means for limiting the sinking of the wire.

Document DE-A-2 142 850 shows a connection device of similar type, in which the connection piece is composed of two distinct elements, namely a U-shaped element constituting the two lateral branches and an element comprising a finger which constitutes the central branch and which forms with the two lateral branches two inclined slots, the axes of which converge towards the top of the connector. Such a composite connection piece is costly, bulky and a delicate adjustment.

Document FR-A-2 122 652, on the other hand, describes a more economical double fork connection device. The two slots are produced by shearing, therefore without removing the material. To ensure a progressive separation of the branches towards the top, the branches are stamped near the bottom. The two slots being parallel to each other, we must widen the base of the connecting piece so that the elasticity is greater and the rigidity lower at the tops of the branches than at their bases. The result is a rather bulky construction that goes against the wishes of miniaturization.

The document FR-A-2 343 343 describes connection pieces with simple forks whose slots are spaced apart by stamping as in the case cited above. Here, the bosses from the stamping are located in such places that they also serve to retain the wires in the slot and to limit their sinking.

The object of the invention is to propose a connection device which differs from the devices mentioned above by its small size and by its high resistance to rupture.

• Les figures du dessin annexé montrent plusieurs exemples de réalisation d'un connecteur.
• La figure 1 représente un connecteur selon l'invention avec double fourche d'un côté et fourche simple de l'autre côté.
• La figure 2 représente un autre connecteur selon l'invention avec double fourche d'un côté et pattes de contact élastiques de l'autre côté.
• La figure 3 est une vue très schématique en perspective montrant comment un connecteur selon l'art antérieur peut être fixé dans un socle en matière isolante.

This object is achieved by the device as specified above, which is characterized by the fact that the connection piece comprises inclined elastic slots whose axes converge towards the base of the connector. Thanks to this inclination of the lights, we gain in total width at the bottom of the lights, which promotes miniaturization, and we avoid breaking at the bottom of the lights, because the width of the lateral branches and thus their rigidity gradually decrease between the area close to the bottom of the lights and the area where these lights lead to the slots.

• The figures of the appended drawing show several exemplary embodiments of a connector.
• Figure 1 shows a connector according to the invention with double fork on one side and single fork on the other side.
• FIG. 2 shows another connector according to the invention with a double fork on one side and elastic contact tabs on the other side.
• Figure 3 is a very schematic perspective view showing how a connector according to the prior art can be fixed in a base of insulating material.

The fork connection piece shown in the figures is made from a spring-quality metallic material, according to a known manufacturing process.

According to fig. 1 and 2, this part is made up of three branches: a left lateral branch 61, a central branch 62, a right lateral branch 63.

Between the branches are V-shaped slots: left slot 64, right slot 65, the openings of which are strictly identical in size and adapted to the diameters of the conductors.

The conductors 8 are inserted one after the other, each in their respective slot, up to a certain distance from the inlet orifice.

Figures 1 and 2 show in detail the particular shape of the slots, which brings a reduction in the dimensions of the fork both at the end and at the base, without however affecting the mechanical characteristics from which the electrical characteristics derive. The central branch 62 has a slight triangular shape so that the slots 64 and 65 are not parallel but are placed on axes which converge towards a point located beyond the top of the fork.

In accordance with the invention, the openings 66 and 67 formed in the base of the fork are not parallel but are placed on axes which converge towards a point situated beyond the base of the fork.

The slots 64 and 65 can be extended by slots 76, 77 which are mutually parallel or have different inclinations from the slots 64 and 65.

This arrangement makes it possible to keep the lateral branches 61 and 63 of sufficient material sections in the active parts in particular in the zones 71 and 72 on the one hand and 73 and 74 on the other hand, while reducing both the dimensions at the top and at the base.

The exemplary embodiment according to FIG. 1 allows both the reduction of the crushing precision and the improvement of the retention of the conductive wire in the slot of the fork. The spacing of the lateral branches 61 and 63 relative to the central branch 62 is obtained by crushing 37 and 38 and displacement of the metal of the central branch 62 no longer at the base of the slots 64 and 65, but at an intermediate distance between the base and the top of the slot, crushings which cause bosses 59.

The right part of Figures 1 and 2 shows an example of use. The central branch 62 is immobilized by the stud 13 carried by a base 10 illustrated in FIG. 3 passing through the hole 14 of the central branch. A conductive wire 8 is inserted into the slot 65 until it rests on the upper face of the insulating base 10. At this time, the conductive wire 8 is below the level of the crush 38. The face of the base thus determines the limit lower than the position that the boss 59 can take.

If traction is then exerted on the conductive wire 8, it can be seen that, in this case, the retention of the wire is considerably increased, since in addition to the mechanical pressure exerted by the branches of the fork on the wire is added the action of the mechanical stop formed by the boss 59 of the crush 38.

The crushing of the material which forms the stop must not reduce the thickness of the metal in the bearing area of the boss 59 against the opposite branch. The crushings 37 and 38 are carried out simultaneously by a punch in full material on the two faces of the branch 62 at a certain distance from the support zone, thus pushing the material back without reducing the thickness in the same way on both sides.

The crushings instead of being carried out on only one of the two branches forming the slot, can be provided in smaller dimensions on either side of the slot on each of the branches.

The outer dimensions of the forks vary depending on the state of the idle or working fork. On a fork in the rest state the size of the end of the fork is less than the size of the base of the fork.

FIG. 2 represents a variant of a connector in which the bosses have the shape of a harpoon 68. They are obtained by means of a die cut of triangular shape 69, 70. The shape of the bosses 68 allows the introduction of the wire conductor 8 while preventing the exit of this conductor when a tensile force is exerted on this conductive wire in the direction of the opening of the slot.

• - Association d'une fourche simple et d'une fourche double soit tête bêche (figure 1) soit côte à côte.
• - Association de deux fourches doubles soit tête bêche soit côte à côte.
• - Association d'une fourche double avec des contacts à pression radiale à liaison électrique par les tranches extérieures (figure 2) ou intérieures.
• - Fourche double et fourche simple associées à des contacts à pression axiale à liaison électrique par la surface des branches élastiques.
• - Association d'une fourche double avec des dispositifs de raccordement par connexions enroulées soit double soit simple; ces connexions enroulées peuvent être du type wrapping ou mini-wrapping.

The base of the fork can be extended and terminated in different ways, some examples of which are given below:

• - Combination of a single fork and a double fork either head to tail (Figure 1) or side by side.
• - Association of two double forks either head to tail or side by side.
• - Association of a double fork with radial pressure contacts with electrical connection by the external (figure 2) or internal sections.
• - Double fork and single fork associated with axial pressure contacts electrically connected by the surface of the elastic legs.
• - Association of a double fork with connection devices by rolled up connections either double or simple; these coiled connections can be of the wrapping or mini-wrapping type.

It is possible to associate between them insulation displacement contacts with pressure contacts by pressure, in particular with radial pressure either external or internal, which are respectively double forks terminated by contacts with external and then internal radial pressure, and contacts with simple fork terminated by contacts with external and internal radial pressure.

Such an arrangement, although feasible, is not without drawbacks. In particular with regard to compliance with the geometric dimensions of the pressure contacts when conductive wires are inserted in the forks.

For the explanation, we will take the example of FIG. 2 of a double fork terminated by contacts with external radial pressure. According to FIG. 2, the fork in the left part is in the rest state (absence of conducting wire) while the right part is in working state (presence of a conducting wire).

This fork placed in an insulating support according to the preceding indications, is extended at its base by two elastic tabs 80 and 81 provided with contact pads 82 and 83, which pads must come to bear in a metal part in the shape of, U 84.

When the fork is in the rest state, left part of the figure, the stud 82 is under pressure therefore ensures electrical contact with the part 84.

When the fork is in the working state on the right-hand side of the figure, that is to say that a conducting wire 8 is inserted in the slot 65, the lateral branch 63 moves to the right in the direction of the arrow H by pivoting around a fictitious articulation point 88 located at the base of the clearance light 67. If the bridge 90 did not exist, in its pivoting the lateral branch 63 would cause the elastic tab 81, thus displacing the stud 83 of the metal part 84 and thereby reducing the contact pressure.

Assuming the left part of the fork also in the working position, the pressure then exerted by the studs 82 and 83 on the metal part 84 could become zero, thus causing the interruption of the electrical circuit.

To remedy this kind of defect, the elastic tabs 80 and 81 are joined together using a bridge 90 which will have the role of suppressing the rotational movement communicated by the lateral branch 63 to the elastic tab 81, now therefore the stud 83 in permanent contact 85 with the metal part 84. Of course the same reasoning is valid for the left part of the fork when the latter is also in the working position. Any intervention on the fork part will therefore have no repercussions on the pressure contact part. By way of reciprocity, any intervention on the pressure contact part will have no repercussions on the fork part.

If a conductor 8 is pushed into the slot, as it moves the elastic branches are progressively spaced from each other which has the effect of increasing the width of the slot, but also and above all would the effect of reducing the width of the slot 4, if the central branch was not maintained.

This reduction in the width of the slot 4 is not desired, since the insertion of a conductor into the slot 4 would not be carried out under the same conditions as the insertion of the conductor 8 into the slot 5. In particular the 'driver insertion effort would become greater and this excessive effort could result in the driver breaking.

A feature of a preferred implementation of the invention aims to remedy this kind of drawback. This peculiarity will be highlighted by fig. 3, which shows a connection piece according to the prior art, namely with slots 4 and 5 parallel between the branches 1, 2 and 3.

In an insulating base 10 is provided a cell 11 receiving the fork 12. Inside the cell 11 a rigid stud 13 is placed in a hole 14 formed in the central branch 2 of the fork. Under these conditions, it can be seen that the introduction of the conductor 8 into the slot 5 progressively separates the right lateral branch 3 from the central branch 2. There is displacement only of the single lateral branch 3, because the central branch 2 is held stationary by the stud 13 passing through the hole 14. It follows that the opening 6 of the slot 4 no longer varies, hence an opening dimension which remains well suited to the diameters of the conductors to be inserted.

However, it appears that to achieve this result without causing the breaking of the lateral branches 1 and 3, it is advantageous to reduce their rigidity in the vicinity of the slots 4 and 5. This property is obtained precisely, by adapting a connection piece having elastic lights 66 and 67 indined, in accordance with the present invention. This is why a device for connecting insulated electrical conductors according to the invention is particularly well suited for being introduced into alvéde 11 of an insulating base 10 illustrated in FIG. 3.

Claims (8)

1. A connecting device for insulated electrical conductors by means of a contact member which penetrates into the insulation, comprising an electrically conductive elastic connection part of the double fork type provided with inclined slots (64, 65) between its branches (61, 62, 63), the axes of which converge towards the summit of the contact member and in which electrical conductors (8) to be connected are inserted, the connection part being intented to be inserted in a cavity (11) of a socket (10) made of insulating material, characterized in that the connection part comprises inclined elasticity holes (66, 67), the axes of which converge towards the base of the connector.

2. A device according to claim 1, characterized in that the wire slots (64, 65) and the elasticity holes (66, 67) are located on axes which converge respectively towards a point situated beyond the summit of the connection part and towards a point situated beyond the base of the connection part, thus reducing the space required for the connection part and particularly at the summit.

3. A device according to claim 1, characterized in that the slots (64, 65) include at least two differently inclined slot portions such as a straight portion (76 or 77) and an inclined portion (64 or 65).

4. A device according to claim 1, comprising a connection part which is provided with at least two push contact arms (80, 81) opposite to the fork branches, characterized in that the connection part comprises a bridge (90) unifying the two arms (80, 81) in such a way that the displacement of the ends of the contact arms is avoided during the insertion of a conductor (8) into the fork.

5. A device according to one of the preceding claims, characterized in that the connection part comprises a hole (14) in the central branch (62) adapted to grip to the stud (13) of the socket (10) to hold the central branch (62) during the insertion of a connection wire (8) into one of the slots (64, 65) of the connection part.

6. A device according to one of the preceding claims, characterized in that the connection part comprises at least one projection (59) at the inner rim of one of the branches (61,62,63) of the connection part, which projection (59) is located between the bottom and the opening of the slot and is adapted on one hand to calibrate the slot opening and on the other hand to retain the conductor (8) in the slot after its insertion, and that the projection (59) is realized by punching, stamping, embossing or others, executed close to the rim of said slot but at a certain distance therefrom, such that the thickness of the connection part is not reduced at its rim.

7. A device according to claim 6, characterized in that the connection part comprises two projections in face to face relationship on the rims of the slot.

8. A device according to claim 6 or 7, characterized in that the projection is harpoon shaped (fig. 2) to facilitate the insertion of the conductor (8) and to avoid its withdrawal.

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