EP3252874B1 - Female contact sleeve, connector using the sleeve and manufacturing method - Google Patents

Description

Technical area

The present invention relates to a metal sleeve that can be used to form a contact of a female electrical connector. It also relates to an electrical connector equipped with the sleeve.

The invention finds applications in the general field of electrical connectors and in particular electrical power connectors. Power connectors are connectors capable of transmitting currents of an intensity of a hundred amperes, or even several hundred to a thousand amperes.

A particular application of the invention is the production of electrical connectors for connecting electric vehicles to a battery pack, and for connecting the battery pack to a charging unit of the battery.

The invention finds particular application in the production of electrical connectors for electric forklifts.

State of the art

Conventionally, the electrical connectors comprise a female contact element, for example a socket and a male contact element, for example a pin, which can be inserted into the socket so as to temporarily establish a contact for the passage of an electric current. The electrical contact is broken when the male element and the female element of the electrical connector are separated. A triple technical problem is traditionally posed when making such electrical connectors.

A first and essential technical problem is the quality of the electrical contact between the male and female contact elements when they are assembled. Indeed insufficient or deficient electrical contact is likely to generate electrical resistance to current flow and Joule heating. This problem is all the more critical as the electric currents to be transmitted are important.

A second technical problem is that of the hardness or "grammage" of the connectors. This is the force that it is necessary to exert on the complementary connectors to insert or extract the male and female contact elements. A high hardness of the connectors makes their use difficult. This difficulty also increases with the intensity of the electric current to be transmitted. Indeed, a large electrical current leads to larger contact elements and a larger contact area. This results in greater friction and greater difficulty of insertion or withdrawal of the contact elements. Incidentally, the search for an improvement in the quality of the electrical contact can lead to reducing a clearance between the male and female contact elements and also increase the hardness of the connectors. In other words the quality of the contact, and the ease of insertion or removal of the connectors appear as antagonistic objectives.

A third technical problem is the durability of the connectors. Sustainability is understood as a number of insertion and separation cycles of complementary connectors during which the quality of contact, and the current carrying of a predetermined intensity can be guaranteed. Durability is also related to the hardness of the connectors and the intensity of the currents to be transmitted.

Connectors using a female contact element in a socket form comprising contact blades and in particular hyperboloid contact blades are known. Such connectors are known, for example documents CN 104 362 452 or US 5,033,982 . The multi-blade bushing is intended to increase the number of contact points between the female part and the male part of the connectors, while limiting the mutual friction between these parts. Document is known EP0442639 A2 a metal sleeve for a female contact as described in the preamble of claim 1.

Presentation of the invention

The invention is based on the observation that hyperboloid blade connectors may be unsuitable or insufficient for the transmission of high intensity electric currents, especially when the connectors are of modest size.

In addition, it turns out that a number of contact blade connectors as mentioned above have insufficient durability. The blades undergo, after a certain number of connections / disconnections, a deformation which, even if slight, no longer makes it possible to guarantee the quality of the contact and the transmission of high currents.

The present invention aims to provide a sleeve for female contact and a connector using the sleeve that allows to transfer a high intensity current, which has a low hardness, and good durability.

An object of the invention is still to provide a sleeve for making connectors of reduced size.

Another object of the invention is to provide a set of male-female connectors adapted to high power applications for vehicles and in particular electric powered forklifts.

To achieve these aims, the invention more specifically relates to a metal sleeve for female contact. The sleeve is provided with a first end portion and a second end portion respectively having a symmetry of revolution about a common axis and having respectively a first and a second diameter. The first and second end portions are interconnected by a plurality of contact blades. The median portions of the contact blades are parallel to the common axis and are arranged in a central cylinder, centered on said common axis and having a diameter less than the first and second diameters. Each contact blade has connection sections connecting the middle portion of the blade respectively to the first and second end portions, the connection sections of the contact blades extending between the middle cylinder and the first and second parts. end by describing at least one frustoconical surface. Moreover, the connecting sections of each contact blade form respectively an angle with respect to a plane passing through the contact blade and the common axis.

In the case of a symmetrical sleeve, the connecting sections describe a frustoconical surface between the median part of the blades, corresponding to the median cylinder, and each of the first and second end portions. However, it is conceivable that the connecting sections describe a frustoconical surface in only one of the end portions of the sleeve.

It is considered that the median portion of the contact blades is arranged according to the median cylinder when they extend substantially on a surface defined by a generatrix of a cylinder running through a circle centered on the common axis. This surface is therefore parallel to the common axis. Thanks to this characteristic, the blades, and more precisely their median parts are likely to have an optimal contact surface with a cylindrical pin of a corresponding male connector, inserted coaxially with the common axis. It should be emphasized that the median cylinder is not a material cylinder but an immaterial cylinder defined by the middle parts of the blades.

Moreover, the arrangement of the connection sections according to a frustoconical surface provides radial flexibility to the contact blades while maintaining the flatness of their median parts and their arrangement according to a substantially cylindrical surface. Thus, at the insertion of a male pin, the flexibility provided by the connecting sections makes it possible to slightly increase the diameter of the median cylinder without deforming the median portion of the blades.
This results in a great soft insertion or removal of the spindle while ensuring a quality electrical contact.

The frustoconical shape whose large base is turned towards the end portions of larger diameter also provides a guide facilitating the introduction of a male pin in the cylindrical housing defined by the middle portion of the contact blades.

As mentioned above, the connection sections of each contact blade respectively form an angle with respect to a plane passing through the contact blade and the common axis. In other words, for each blade, the middle part and the connecting sections are not coplanar in a plane passing through the common axis. The connection angle is, for example, an angle of between 30 and 60 degrees.

This feature makes it possible to further increase the flexibility provided by the connecting sections and the smooth insertion or removal of a pin in the sleeve. It also allows the median portions of the blades to bear on the spindle along their entire length, parallel to the axis of the spindle and without deformation, so as to ensure good electrical contact with the spindle. This also results in an increase in the durability of a connector equipped with the sleeve.

The medial portions of the contact blades extend parallel to a generatrix of the median cylinder which they delimit and are parallel to the common axis.

The contact blades may have sections of different shapes, but with a preference for a thin, flat shape. The median portions of the contact blades can thus have a wide side perpendicular respectively to a radius of the median cylinder. This wide side, possibly slightly curved according to the curvature of the median cylinder, can in this case be applied tangentially to the surface of a male pin, when such a pin is inserted into the sleeve.

The end portions of the sleeve may be cylindrical portions, with respectively a diameter equal to the first and second diameters.

Alternatively, the end portions may be frustoconical in shape comparable to the connecting sections. The truncated cone flares then from a small base respectively having the first and the second diameter mentioned above, the small base being turned towards the contact blades. In this case, the end portions of the sleeve extend a cone formed by the connecting sections, to guide a pin to be inserted into the sleeve.

As described later, the end portions of the sleeve can be used to form a permanent electrical contact with other conductors of a connector, and can thus, more generally, have a shape adapting to these conductors.

Incidentally, the sleeve may also be equipped with one or more connection terminals for connecting a conductor, and in particular an electric cable.

In a preferred embodiment of the sleeve, the sleeve is symmetrical with respect to a median plane perpendicular to the common axis. Also the first and second diameters of the end portions may be equal.

The number of contact blades is preferably adapted to the intensity of a current that can be transmitted by a connector receiving the sleeve. The number of blades is, for example, between 10 and 18.
As an illustration, a connector for a current of 160A can be equipped with a sleeve with 12 contact blades. For a rated current of 320A the number of blades can be increased to 14.

The sleeve may be preferably made of a metal such as bronze, bronze-phosphorus, beryllium copper, or nickel silver, for example.

As mentioned above, the invention also relates to a connector comprising one or more sleeves as described above.

In a particular embodiment of the connector, it may comprise at least one sleeve having a cylindrical bore, the sleeve being housed in the bore. The connector may comprise one or more sockets depending on the number of phases of the current or currents to be transmitted and the number of terminals of the connector. For a direct current, the connector, bipolar, may comprise two sockets, each provided with a sleeve as described.

Socket means an intermediate metal part for electrically connecting the sleeve to a conductor such as an electric cable for example. Such a socket is used in particular when the sleeve does not in itself terminal connection for an electric cable.

When the sleeve is inserted into the bore of the socket, the first and second end portions make it possible to establish permanent electrical contact with the socket and thus conductors connected thereto.

In order to maintain the sleeve in the bore, the bore may have a shoulder, for example a cylindrical or conical shoulder, forming a stop for at least one of the first and second end portions of the sleeve. Furthermore, after the introduction of the sleeve into the bore of the sleeve, the sleeve can be crimped into the sleeve by deformation of the sleeve, including its end, to reduce slightly the diameter.

The invention further relates to a male and female connector assembly comprising a female connector as described above, and a male connector with a cylindrical contact pin having a diameter between the diameter of the center cylinder of the sleeve and the smallest of the first and second diameters of the end portions of the sleeve.

The connectors may include insulative housings surrounding the socket, the sleeve and possibly other metal parts likely to be live. The insulating housings of the male and female connectors may also include complementary non-metallic parts, contributing to the quality of the connector assembly and the security of the connection.

In particular, complementary connectors may comprise a connection lock capable of holding the male connector in position in the female connector.

A method of manufacturing the female contact sleeve is shown below.

• le découpage à plat d'une plaque métallique selon un motif comprenant deux bandes latérales pleines s'étendant entre une première et une deuxième extrémité de la plaque, les bandes latérales étant parallèles entre elles, et reliées entre-elles par une pluralité de lames de contact formant entretoises, uniformément espacées les unes des autres et reliées respectivement aux bandes latérales par des sections de raccordement, les parties médianes des lames de contact étant perpendiculaires aux bandes latérales et les sections de raccordement des lames de contact formant un angle avec la partie médiane des lames de contact, et
• le roulage de la plaque métallique de manière à rejoindre les première et deuxième extrémités de la plaque métallique et agencer la partie médiane des lames de contact selon un cylindre.

The method comprises:

• flat cutting of a metal plate in a pattern comprising two solid side strips extending between a first and a second end of the plate, the side strips being parallel to each other, and interconnected by a plurality of blades; contact forming spacers, uniformly spaced from each other and respectively connected to the sidebands by connecting sections, the middle portions of the contact blades being perpendicular to the sidebands and the connection sections of the contact blades forming an angle with the middle part contact blades, and
• rolling the metal plate so as to join the first and second ends of the metal plate and arrange the middle portion of the contact blades in a cylinder.

This cylinder corresponds to the median cylinder mentioned with reference to the description of the sleeve.

During rolling, the lateral strips may be arranged respectively in a second cylinder, or in a truncated cone having a radius greater than the median cylinder.

Advantageously, as the median cylinder has a diameter smaller than that of the end portions, rolling has the effect of bringing the contact blades, and in particular their median parts, closer together after cutting. The approach of the blades has the effect of reducing a spacing between the median portions of the blades on the surface of the central cylinder. It promotes the passage of an electric current and the evacuation of the heat produced by the passage of an electric current. Furthermore, the medial portions of the contact blades retain their character perpendicular to the side strips and are thus arranged parallel to the common axis of the central cylinder obtained after rolling.

After rolling, the first and second ends of the metal plate can be joined by welding. The realization of a weld is however not essential. In particular when the sleeve is crimped in a sleeve, as indicated above, the crimping operation can be used to perfectly fit the first and second ends of the plate forming the sleeve. A weld is then superfluous.

Other features and advantages of the invention emerge from the description which follows, with reference to the figures of the drawings. This description is given for illustrative and not limiting.

Brief description of the figures

• The figure 1 is a side view of a metal sleeve for female contact, according to the invention.
• The figure 2 is an axial view of the sleeve of the figure 1 .
• The figure 3 is a front view of a metal plate used for the manufacture of a sleeve according to the invention.
• The figure 4 is a partial view of a set of male and female connectors according to the invention and using the sleeve of figures 1 or 2

Detailed description of embodiments of the invention

In the following description of the same or equivalent identical parts of the different figures are identified with the same reference characters so as to be able to refer from one figure to another.

The figure 1 shows a metal sleeve 10 according to the invention. The sleeve is usable as a female contact element of a connector.

The sleeve 10 has a first end portion 12a and a second end portion 12b respectively having a first and a second diameter. In the exemplary embodiment of the figure 1 the first and second diameters are equal. This common diameter is greater than the diameter of a male contact pin capable of being accommodated in the sleeve.

The end portions 12a and 12b have a symmetry of revolution about an axis 14 designated "common axis". In the particular case of the sleeve of the figure 1 end portions 12a and 12b are cylindrical.

The end portions 12a and 12b of the sleeve 10 are connected to each other by a plurality of contact strips 20, identical to each other and separated from each other by regular spaces 22.

The contact blades 20 each have a flat medial portion 24 and are arranged in a symmetry of revolution about the common axis 14 so that the median portions 24 of the blades define a cylinder 26 designated a central cylinder.

The diameter of the median cylinder 26 is smaller than the diameter of the end portions 12a and 12b of the sleeve 10. The diameter of the center cylinder is also slightly smaller than the diameter of a conjugate male contact pin that can be received. in the sleeve.

The middle portions of the contact blades 20 are respectively connected to the first and second end portions 12a, 12b by connection sections 28. The connection sections extend between the middle cylinder 26 defined by the middle portions of the blades and the end portions 12a, 12b, being arranged in frustoconical surfaces. The truncated cones described by the connection sections have a small base corresponding to the median cylinder 26 and a large base corresponding to the diameter of the cylinders formed by the end portions 12a, 12b. In the example of the figure 1 the truncated cones defined by the connecting sections towards each end portion are symmetrical with respect to a median plane perpendicular to the common axis 14.

Moreover, and always in the example of the figure 1 the median portions 26 of the contact blades 20 extend along a generatrix of the median cylinder. The middle portion 24 of the contact blades 20 is thus substantially flat and parallel to the common axis 14.

We can observe on the figure 1 that the connecting sections 28 are not in the extension of the contact blades 20 but form respectively an angle relative to these blades. More precisely, the connecting sections form an angle with respect to a plane passing through the contact blades 20, and in particular through the middle of the blades, and the common axis 14. The angle formed at the two ends of each blade is opposite.

It should be emphasized that the transitions between the middle portion 24 of the contact blades 20 and the connecting sections 28, as well as the transitions between the connecting sections 28 and the end portions 12a, 12b are smooth transitions, curve. They do not present a sharp stop that can come into contact with a conjugate male contact element.

The particular conformation of the blades gives the sleeve flexibility to introduce and remove a male contact element with low mechanical strength while ensuring good electrical contact.

As shown in figure 2 , the flexibility of the sleeve results from a flexibility of the connection sections 28. The flexibility is accompanied by a limited possibility of twisting each connection section around a torsion point T respectively offset from the middle portion 24 of the corresponding blade. This characteristic promotes a good durability of the sleeve. The flexibility given by the connecting sections makes it possible to slightly vary the diameter of the median cylinder 26 as indicated by dashed lines. This variation of the median cylinder is done without deformation of the middle portion 24 of the contact blades 20. These remain flat and substantially parallel to the common axis and a generatrix of the central cylinder.

The figure 3 shows the result of a first step of manufacturing a sleeve as described above. This step comprises cutting a plate 11, for example by punching, to obtain the plate of the figure 3 . The plate 11 has two lateral strips 12a, 12b which after rolling will form the end portions 12a and 12b of the sleeve mentioned above. Since they are the same parts, they are designated by the same references.

The plate 11, and in particular the lateral strips 12a, 12b, extend between a first and a second end of the plate. These ends are identified with references 41, 42.

The lateral strips 12a, 12b, parallel to one another, are connected by the contact blades 20 which form spacers. The middle portions 24 of the contact blades are also parallel to each other and regularly spaced. They are also perpendicular to the lateral strips 12a, 12b in the exemplary embodiment illustrated.

Finally, it can be observed that the median portions 24 of the contact blades 20 are connected to the lateral strips 12a, 12b by connection sections forming an angle with respect to the median portions. It is considered that the connecting sections form an angle with respect to the median portions when this angle is a non-zero and not straight angle. The angle is preferably between 30 and 60 degrees.

A second step of the manufacturing process comprises rolling the plate so as to join the ends 41 and 42 of the plate. The rolling makes it possible to arrange the lateral strips 12a, 12b so as to form the corresponding cylindrical end portions from there figure 1 . It also makes it possible to arrange the median portions 24 of the contact blades 20 according to the median cylinder.

The figure 4 shows a detail of a set of connectors comprising a female connector 50 and a male connector of which only a cylindrical pin 52 is visible.

The female connector comprises a socket 60 of a material such as copper covered with a thin layer of silver, brass, bronze, or aluminum, for example. The bushing 60 is provided with a bore 62 receiving a sleeve 10 as described above. The bore has a diameter substantially adjusted to the diameter of the end portions 12a and 12b of the sleeve.

The bore 62 of the sleeve comprises a shoulder 64 against which abuts one of the end portions 12b of the sleeve. The other end portion 12a of the sleeve, turned towards the opening 66 of the sleeve is held by a slight conical narrowing of the opening of the sleeve made during a crimping operation of the sleeve in the sleeve. The end portions 12a and 12b of the sleeve form a permanent electrical contact between the sleeve 10 and the socket 60 of the female connector.

The diameter of the opening 66 of the sleeve, slightly smaller than the diameter of the end portions of the sleeve after crimping thereof, is greater than that of the pin 52 of the conjugate male connector.

The frustoconical portion of the sleeve 10 formed by the connecting sections 28 in the vicinity of its end 12a turned towards the opening of the bushing 66 constitutes a conical guide allowing, when the pin 52 is inserted, to guide it according to FIG. axis of the sleeve. The connecting sections cooperate with a rounded end 54 of the pin 52.

When the pin 52 is inserted, the latter slightly bends the connecting sections 28 of the sleeve 10, so as to adjust the median cylinder defined by the median portions 24 of the contact blades 20 to the diameter of the pin 52 of FIG. male connector. This makes it possible to effortlessly introduce the pin into the socket while ensuring excellent electrical contact between the middle portion 24 of the contact blades with the pin 52. The middle portions 24 of the contact blades 20 are supported flat on the brooch. According to a plane perpendicular to the axis of the sleeve, the median portions 24 of the contact strips 20 bear tangentially to the surface of the pin 52, or even slightly curved to fit the surface of the pin 52. The blades have indeed a wide side, visible on the figure 2 substantially perpendicular to a corresponding radius of the center roll, or a radius of the spindle when inserted.

The female connector and / or the male connector may be provided with housings of an electrical insulating material, for example plastic, which protect the metal parts. The housings can in particular constitute a protection for a user entering the connectors. The boxes are however not represented on the figure 4 for the sake of simplification.

Claims (12)

1. A metal sleeve (10) for a female contact, the sleeve being provided with a first end part (12a) and a second end part (12b) respectively of rotational symmetry around a common axis (14) and being of a first and a second diameter respectively, the first and second end parts being Interconnected by a plurality of contact blades (20) each having a median part (24) and connecting sections (28) connecting the median part (24) to the first and second end parts respectively, the median parts (24) of the contact blades being arranged along a median cylinder (28) centred on said common axis (14) and being of a diameter smaller than the first and second diameters, and the connecting sections (28) of the contact blades (20) extending from between the median cylinder and the first and second end parts (12a, 12b) describing at least one frustoconical surface, wherein the connecting sections (28) of each contact blade (20) respectively form an angle with respect to a plane passing through the contact blade and the common axis (14), characterised in that the median parts (24) of the contact blades (20) are parallel to the common axis.
2. A sleeve according to claim 1 wherein the median parts (24) of the contact blades (20) extend In parallel relationship to a generatrix of the median cylinder (26).
3. A sleeve according to claim 1 wherein the median parts (24) of the contact blades (20) extend helicoidally along the median cylinder (20).
4. A sleeve according to one of claims 1 to 3 wherein the median parts (24) of the contact blades (20) respectively have a wide side perpendicular to a radius of the median cylinder.
5. A sleeve according to one of claims 1 to 4 wherein the end parts (12a, 12b) of the sleeve (10) are cylindrical.
6. A sleeve according to one of claims 1 to 4 wherein the end parts (12a, 12b) of the sleeve (10) are of a frustoconical shape with a small base which are respectively of the first and second diameters, the small base being turned towards the contact blades.
7. A sleeve according to one of claims 1 to 6 wherein the first and second diameters are the same.
8. A sleeve according to one of the preceding claims comprising a number of contact blades of between 10 and 18.
9. A female connector (50) comprising at least one sleeve (10) according to any one of the preceding claims.
10. A connector according to claim 9 comprising at least one socket (60) with a cylindrical bore (62), the sleeve (10) being accommodated in said bore.
11. A connector according to claim 10 wherein the bore (62) has a shoulder (84) forming a stop for at least one of the first and second end parts of the sleeve.
12. An assembly of male and female connectors comprising a female connector (50) according to one of claims 9 and 10, and a male connector with a cylindrical contact pin (52) of a diameter between the diameter of the median cylinder of the sleeve (10) and the smaller of the first and second diameters of the end parts of the sleeve.

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