EP0547969A1 - Electrical contact with resilient strip for electrical connector - Google Patents

Abstract

Female electrical contact comprising at least one axial elongate flexible strip which is away from the axis (A) of the contact and can be elastically deformed transversely. The flexible strip (6) has: a tail (5) fitted into a support (2, 4); a contact part (7); an intermediate part (8) located between the tail (5) and front contact (7) parts and having a longitudinal curvature of large radius and without folding, in order to flex elastically transversely; and a reduced-inertia part (10) located between the intermediate and front parts, conferring a decrease in inertia capable of distributing the stresses over the entire length of the intermediate part and of promoting its progressive and continuous elastic flexing; the parts (5), (7) and (8) possess a predetermined transverse curvature conferring on them a desired stiffness; a stop surface (2a) is located at the rear of the strip in order to keep its deformation within the elastic limits. <IMAGE>

Description

The present invention relates to female type contacts for electrical connector comprising at least one elongated flexible blade, extending substantially axially away from the axis of the contact and elastically deformable transversely during the introduction / extraction of a contact of associated male type.

The invention relates more particularly, although not exclusively, to connector contacts intended for space applications, which contacts, taking into account the characteristics inherent in a space environment (vacuum, weightlessness, large thermal differences, impossibility of corrective maintenance) , must meet requirements of high reliability, long service life and reduction as large as possible of the efforts of insertion / extraction.

Various contacts of the aforementioned type are known, known as split sockets, in which the structure of the socket makes it difficult to control the insertion / extraction effort, in particular because of too wide tolerance ranges. It is thus necessary to perform a sorting of the contacts to discard the non-standard contacts.

In addition, the flexible blade contacts currently produced do not have a sufficient safety margin. The Applicant has been able to establish that this drawback resulted directly from the structure and the method of manufacture of the flexible blades currently used. Indeed, the contact end of the blades is obtained by bending a metal piece initially straight in the longitudinal direction. When the contact end is elastically stressed radially during the insertion / extraction operations, this contact end pivots relative to the fixing part at the level of the fold which acts as an articulation. This results in a concentration of the stresses and therefore a noticeable fatigue of the metal at the level of the bend such that the safety coefficient is insufficient for certain applications such as space applications.

Furthermore, in a flexible blade contact thus arranged, only the contact end is displaceable and it alone determines (in particular by its length and its inclination) the bearing force on the pin of the male contact with which it is called to cooperate, and therefore the insertion / extraction effort. The rest of the blade is not involved in determining this force and this results in too great rigidity of the blade, considered as a whole, so that it is possible to obtain an insertion / extraction force as low than that which one may wish to make the connectors with large or very large number of contacts easily maneuverable.

The object of the invention is therefore precisely to remedy the above-mentioned drawbacks of current electrical contacts with flexible blades so that they better meet the various requirements of practice in terms of reliability, service life and value of the product. '' insertion / extraction effort, in particular for specific applications such as those involving their use in a spatial environment.

• - une partie de queue encastrée dans un support,
• - une partie antérieure de contact, située en avant de la partie intermédiaire, agencée pour être en appui contre un contact de type mâle lorsque celui-ci est introduit dans ledit contact femelle,
• - une partie intermédiaire, située entre les parties de queue et antérieure de contact, qui est courbée longitudinalement en direction de l'axe du contact avec une courbure de grand rayon sans pliure, et apte à fléchir élastiquement dans le sens transversal lors de l'introduction d'un contact de type mâle, et
• - une partie à inertie réduite, située entre les parties intermédiaire et antérieure, conférant une diminution d'inertie apte à répartir les contraintes sur toute la longueur de la partie intermédiaire et à favoriser un fléchissement élastique progressif et continu de ladite partie intermédiaire lorsque la lame souple coopère avec un contact de type mâle,
• - au moins les parties intermédiaire, d'inertie réduite et antérieure possédant une courbure transversale prédéterminée leur conférant une raideur souhaitée,

For these purposes, the invention provides a female type electrical contact for an electrical connector comprising at least one elongated flexible blade, extending substantially axially away from the contact axis and elastically deformable transversely, which being arranged in accordance with l The invention is essentially characterized in that it has:

• - a tail part embedded in a support,
• a front contact part, located in front of the intermediate part, designed to bear against a male type contact when the latter is introduced into said female contact,
• - an intermediate part, located between the tail and front contact parts, which is curved longitudinally in the direction of the contact axis with a large radius curvature without folding, and capable of bending elastically in the transverse direction during the introduction of a male type contact, and
• a part with reduced inertia, situated between the intermediate and anterior parts, conferring a reduction in inertia capable of distributing the stresses over the entire length of the intermediate part and of promoting a progressive and continuous elastic deflection of said intermediate part when the blade flexible cooperates with a male type contact,
• - at least the intermediate parts, of reduced and anterior inertia having a predetermined transverse curvature giving them a desired stiffness,

and in that it further comprises an abutment surface located behind the flexible blade (relative to the axis of contact) to limit the transverse deformation of said blade and keep it within the limits of an elastic deformation.

Advantageously, in a simple embodiment of the flexible blade, the part with reduced inertia has a narrower width than the width of the intermediate and anterior parts which frame it. Still for the same purpose, the flexible blade can have a substantially constant thickness in all of its parts; it is then possible, at least in certain exemplary embodiments, that the flexible blade as a whole is obtained from a sheet of metal.

Still with the aim of simplifying the manufacture of pallets, it is advantageous for the transverse curvature of the flexible blade to be substantially constant at least over the entire length of the intermediate parts, of reduced and anterior inertia. This curvature transverse can then be obtained by a conventional technique of bending the pre-cut blade in a metal sheet.

Constituted according to the invention, each blade is able to exhibit a very gravitational aptitude for elastic deformation, without however that there is a concentration of the stresses in a particular zone, thanks to the elimination of the fold present in the blades flexible from previous contacts.

The limit of elastic deformation can be increased by the use of a cuproberyllium treated in whole or in part, which remains possible under acceptable cost conditions by producing the blades from a thin strip of cuproberyllium cut and arched , whatever the technological solution (individual or grouped blades) that is adopted.

Thanks to these arrangements distributing the stresses over the entire surface of the part while avoiding the concentrations of stresses usually encountered, there is a remarkable safety coefficient, greater than 2, between the usual range of use and the limit deformation of the area of permanent deformation.

By homothety, the same geometry applies to a wide range of contact dimensions.

• - un corps tubulaire rigide externe, à l'intérieur duquel est abritée la susdite lame souple, la partie de la surface interne dudit corps tubulaire située en arrière de la lame souple constituant la surface de butée précitée,
• - et un fût intérieur situé dans la partie arrière dudit corps tubulaire, la partie de queue de la lame souple étant encastrée entre le fût et le corps tubulaire.

In a preferred embodiment which seems to be satisfactory for a large number of uses, the contact further comprises:

• an external rigid tubular body, inside which the said flexible blade is housed, the part of the internal surface of said tubular body located behind the flexible blade constituting the abovementioned abutment surface,
• - And an inner barrel located in the rear part of said tubular body, the tail part of the flexible blade being embedded between the barrel and the tubular body.

The tubular body and the inner barrel can in practice be secured to one another by crimping, and the tail portion of the blades is thus blocked between them.

Different structures, associated with different manufacturing processes, can be envisaged. Thus, in a first possible exemplary embodiment, use is made of pallets produced in unitary form which are embedded by their tail part between the tubular body and the inner barrel and their respective tail parts have widths such that they surround the inner barrel being butted laterally against each other. By cons, in another possible embodiment, it is arranged that the flexible blades are joined in a single component part and their tail parts are joined in the form of a tubular sleeve embedded between the tubular body and the inner barrel. In either case, provision can be made for the tail portion to have at least one radial projection directed inward and engaged in a housing in the inner barrel to provide its axial retention.

• - la figure 1 est une vue en coupe diamétrale d'un contact à trois lames souples agencé conformément à l'invention ;
• - la figure 2 est une vue de dessus d'une lame souple unitaire utilisée dans le contact de la figure 1;
• - les figures 3 à 5 sont des vues en coupe transversales respectivement selon les lignes III-III, IV-IV et V-V de la figure 1 ;
• - la figure 6 est une vue en plan d'un flan métalli- que découpé pour constituer les lames souples du contact de la fig. 1 sous forme groupée ;
• - la figure 7 est une vue en coupe diamétrale d'un contact à lame souple unique agencé selon l'invention ;
• - la figure 8 est une vue de face d'un flan métalli- que découpé pour constituer la lame souple du contact de la fig. 7 ; et
• - les figures 9 et 10 sont des vues en coupe transversale, selon la ligne X-X de la fig. 7, montrant la position des lames respectivement sans et avec un contact mâle engagé dans le contact de la fig. 7.

The invention will be better understood on reading the detailed description which follows of certain preferred embodiments given by way of purely illustrative examples. In this description, reference is made to the attached drawings in which:

• - Figure 1 is a diametrical sectional view of a contact with three flexible blades arranged in accordance with the invention;
• - Figure 2 is a top view of a unitary flexible blade used in the contact of Figure 1;
• - Figures 3 to 5 are cross-sectional views respectively along lines III-III, IV-IV and VV of Figure 1;
• - Figure 6 is a plan view of a metal blank cut to form the flexible contact blades of FIG. 1 in group form;
• - Figure 7 is a diametrical sectional view of a single flexible blade contact arranged according to the invention;
• - Figure 8 is a front view of a metal blank cut to form the flexible blade of the contact of FIG. 7; and
• - Figures 9 and 10 are cross-sectional views along line XX of FIG. 7, showing the position of the blades respectively without and with a male contact engaged in the contact of FIG. 7.

Referring firstly to Figures 1 to 5, the female type contact 1 comprises for example an outer tube or tubular body 2 open at its two ends, one of the ends, intended to receive a male contact for example pin type (whose lateral outline has been simply shown by the dotted lines designated by the letter M), having its edge curved inward to form a guide lip 3.

At its rear part, the tube 2 is threaded on a solid barrel 4 which itself is, towards the rear, shaped in any suitable manner (not shown) to be connected to an electric cable.

Between the outer tube 2 and the barrel 4 are embedded the tail parts 5 of several (here three) flexible blades 6 regularly distributed circumferentially.

As can be seen better in FIG. 2, each blade 6 is in the form of an elongated metal blade, for example made of cuproberyllium treated at least locally with a core, having a contact part 7 situated towards the front and a part of tail 5 located towards the rear which are separated by an intermediate part 8 provided with a continuous curvature and of large radius, without bending, in the direction of the axis A of the contact.

So that this blade has sufficient stiffness with respect to its relatively modest thickness, it is bent transversely over its whole length. The radius of curvature of the transverse bending is the same at least over the entire length of the parts 7 and 8 above.

To increase the longitudinal flexibility of the metal strip and to obtain a distribution of the stresses over the entire length of its intermediate part 8, and therefore to provide the latter with a greater capacity for elastic deflection when it is stressed transversely, a zone is provided. reduction in inertia (here achieved by reducing the width of the metal strip) located at 10 between the front contact part 7 and the intermediate part 8; the reduced width zone 10 is surrounded by the parts 7 and 8 which have progressively increasing widths.

Finally, the flexible blade has, in top view (FIG. 2), a variable width contour which, in combination with the transverse curvature, leads to a member with longitudinally variable stiffness and with controlled longitudinal flexibility.

The cross section of the different parts of the contact 1 are shown in Figures and 5, namely: cross section at the contact part of the blades in Figure 4 along line IV-IV of Figure 1; cross section at the tail portion 5 of the blades in Figure 5, along the line V-V in Figure 1; and finally seen at the end of contact 1 along line 111-III of FIG. 1, in FIG. 3.

During a connection operation, the introduction of the pin M of a male contact into the female socket 1 causes the front contact parts 7 of the blades 6 to be raised transversely, as shown in FIG. 1. The wall z of the tubular body 2 serves as a stop which limits the transverse deflection of the blade 6.

The controlled deformation of each blade in its different zones allows, while maintaining good quality electrical contact with the male pin, to reduce the bearing force of the contact part 7 on the pin, and therefore to reduce the wear of these organs.

Above all, such a conformation makes it possible to work the metal well below the elastic deformation limit (for example in a deformation range corresponding approximately to half the value of this limit, that is to say with a safety factor of 2), and it is thus ensured that the metal will never have to work in the zone of permanent deformation.

In addition, a flexible blade thus formed can be made of a material with highly elastic properties, such as cuproberyllium treated at heart, according to a simpler manufacturing process than that required by female contacts made in one piece. Here, as shown in Figure 2 each blade is cut in one piece flat in a sheet of metal, then bent transversely and longitudinally; it is then treated at heart as a whole. The tails 5 of the blades 6 have a width such that, when they are placed in the tubular body, they are butted laterally against each other and, together, they completely surround the barrel 4, as seen in the Figure 5. This results in a lateral locking of the blades 6 in a suitable position.

In addition, each blade 6 may have, at or towards the free end of its tail 5, a radial projection 11 directed inwards which is engaged in a housing (for example an annular groove 12) hollowed out in the barrel 4. The blades 6 are thus retained axially.

FIG. 6 shows an exemplary embodiment in which the tail parts 5 ′ are all joined together and form a tubular sleeve which is fitted on the external tube 2 and embedded between it and the barrel 4. All the blades 6 ′ and the tubular sleeve 5 ′ are in one piece and therefore form a single, single piece designated as a whole by the reference 13.

The part 13 can be manufactured in various ways, for example by machining the individual blades 6 'in a section of tube, or even, in a simpler and more economical manner, by flat cutting of a metal blank shown in the figure. 6, then rolling thereof to form the transverse camber of the blades 6 'and the sleeve 5'. Cutouts made at the base of the metal blank make it possible to form radial projections 12 for axial retention.

It will be understood that an electrical contact according to the invention can be arranged with any number of flexible blades on the basis of the arrangements which have just been stated. The flexible blades are then distributed angularly in a regular manner, so that the male contact is guided axially by the blades or parts of blades facing each other.

However, with regard to a contact provided with a single flexible blade, certain features must be provided as will now be indicated with reference to FIGS. 7 to 10 so as to ensure proper guidance of the associated male contact.

The contact 14 shown in FIG. 7 is constituted, in general, in the same way as the contact 1 in FIG. 1 (the same reference numbers have been kept to designate the identical members), except that the contact 14 is equipped with a single flexible blade 6.

To compensate for the transverse force exerted by the contact part 7 on the pin M of the associated male contact and to guide the latter during the introduction / extraction, provision is made, opposite the flexible blade 6, support and guide 15 which can be shaped approximately as a contact blade, except that it is not arranged for chirtransversally. The support and guide piece 15 has a tail portion 5 arranged to be embedded between the tubular body 2 and the barrel 4 of the same way as a flexible contact blade 6 or 6 'mentioned above; it is bent transversely; however, it does not have a reduced inertia zone; it can advantageously have a width greater than that of a flexible blade, in order to facilitate guiding the male pin M, as can be seen in FIG. 10 which shows the respective position of the parts 6 and 15 against the pin M pressed in contact. Figure 9 shows the same contact in the absence of the pin.

The single flexible blade 6 and the support and guide piece 15 can be arranged as already indicated above either in the form of two separate members, unitarily embedded and retained between the tube 2 and the barrel 4, or in the form of a monobloc member obtained by flat cutting of a metal blank 16 as shown in Figure 8, then camber and rolling thereof. The one-piece member 16 is then mounted like the member 13 in FIG. 6.

As goes without saying and as it already follows from the above, the invention is in no way limited to those of its modes of application and embodiments which have been more particularly envisaged; on the contrary, it embraces all its variants.

Claims (9)

1. Electrical contact of female type for electrical connector comprising at least one elongated flexible blade, extending substantially axially away from the axis of the contact and elastically deformable transversely characterized in that this flexible blade (6, 6 ') has : - a tail part (5, 5 ') embedded in a support (2, 4), a front contact part (7) arranged to bear against a male type contact (M) when the latter is introduced into said female contact, - an intermediate part (8), located between the tail (5, 5 ') and anterior contact parts (7), which is curved longitudinally in the direction of the contact axis with a large radius curvature and without bending, and capable of flexing elastically in the transverse direction when a male type contact is introduced, and - a reduced inertia part (10), located between the intermediate and anterior parts, imparting a reduction in inertia capable of distributing the stresses over the entire length of the intermediate part and of promoting a progressive and continuous elastic deflection of said intermediate part when the flexible blade cooperates with a male type contact, - at least the intermediate parts, of reduced and anterior inertia having a predetermined transverse curvature giving them a desired stiffness,
and in that it further comprises an abutment surface (2a) located behind the flexible blade (relative to the axis of the contact) to limit the transverse deformation of said blade and keep it within the limits of a elastic deformation. 2. Contact according to claim 1, characterized in that the reduced inertia part (10) has a narrower width than the width of the intermediate and front parts which surround it. 3. Contact according to claim 1 or 2, characterized in that the flexible blade has a substantially constant thickness in all its parts. 4. Contact according to any one of claims 1 to 3, characterized in that the transverse curvature of the flexible blade is substantially constant at least over the entire length of the intermediate parts, of reduced and anterior inertia. 5. Contact according to any one of claims 1 to 4, characterized in that it further comprises: - an external rigid tubular body (2), inside which the aforesaid flexible blade (6, 6 ′) is housed, the internal surface z) of said tubular body constituting the abovementioned abutment surface located behind the flexible blade , - And an inner barrel (4) located in the rear part of said tubular body, the tail part (5, 5 ') of the flexible blade being embedded between the barrel and the tubular body. 6. Contact according to claim 5, characterized in that it comprises several separate flexible blades (6) whose tail parts have widths such that they surround the internal shaft (4) being butted laterally against each other . 7. Contact according to claim 5, characterized in that it comprises at least two flexible blades (6 ') joined in a single piece (13) and in that their tail parts form a tubular sleeve (5) surrounding the barrel . 8. Contact according to claim 5, characterized in that it comprises a single flexible blade (6) and in that it further comprises a support piece and the guide (15) for the cooperating male contact which is situated opposite the flexible blade. 9. Contact according to any one of claims 5 to 8, characterized in that the tail part (5, 5 ') has at least one radial projection (11) directed inwards and engaged in a housing (12) of the inner barrel (4) for the axial retention.

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