Electrical connector

Abstract

The invention relates to an electrical connector (103, 105) comprising a hollow cylindrical body extending around an axis of revolution (X), an electrical contact (107) and an annular insulator (111). The annular insulator (111) has a shape that is complementary to that of the electrical contact (107) and is in contact with the outside of the surface of the electrical contact (107) over the entire longitudinal extent thereof except for a portion of the surface of the electrical contact (107) that is intended to make contact with an electrical contact (107) that is complementary to a complementary electrical connector (103, 105). Furthermore, the annular insulator (111) comprises a first annular insulator (111a) which covers a connection area (117) of the electrical contact (107) and is made of glass-ceramic.

Description

[0001] Description

[0002] TITLE: ELECTRICAL CONNECTOR

[0003] TECHNICAL FIELD

[0004] The invention relates to the field of electrical connection devices for transporting high power in an aircraft. It relates in particular to an electrical connector intended to establish an electrical connection with a complementary electrical connector as well as an assembly comprising two complementary electrical connectors.

[0005] PRIOR ART

[0006] The state of the art includes in particular documents WQ-Al-2014183115, US-A-2824290, EP-A1-3364504 and FR-A1-3110781.

[0007] Current efforts to decarbonize aircraft are leading to the integration of more and more electrical systems within them. The hybridization or electrification of aircraft is part of this trend and is creating a new need for so-called high-power electrical connectors, i.e., connectors capable of withstanding high voltages and currents.

[0008] The preferred approach to achieving high power consists mainly of increasing the voltage levels within the aircraft's on-board networks, since an increase in current levels would imply an increase in the cross-section of the conductors, and therefore their mass, which goes against the objectives sought for use in an aircraft.

[0009] Thus, the voltages currently envisaged for on-board aircraft networks are in the order of 800 to 1,000 Volts (direct voltage) but could eventually tend towards 3,000 Volts for currents of the order of 500 Amps.

[0010] Such voltage and current values, combined with use at high altitude (e.g. 55,000 feet) which involves large variations in temperature (e.g. ranging from -55°C to +250°C), pressure and humidity, lead to the occurrence of physical phenomena that are rare or otherwise non-existent. Thus, a known phenomenon associated with such operating conditions is partial discharge. This is a localized discharge, which results from temporary ionization of a gas in an electrical insulation system, and which occurs when the electrical stress (electric fields) exceeds a critical value.

[0011] This phenomenon is critical as it can lead to reduced performance and deterioration of an electrical system in which it occurs. In the case of electrical connectors, the occurrence of partial discharges within them can deteriorate the insulators included in the connectors (i.e. accelerate their aging) or even, in the long term, generate the presence of a short circuit rendering the connector inoperative.

[0012] In particular, when used in an aircraft, where an electrical connector is subject to significant variations in temperature and pressure (due to altitude), partial discharges can cause an insulation fault in the connector, resulting in the activation of protection devices and the cutting off of the power supply to the loads of the aircraft's electrical system (motors, actuators, etc.).

[0013] For these reasons, in the current state of the art, electrical connectors intended for aeronautical use are replaced by terminal blocks when they must be used for high powers.

[0014] Furthermore, existing electrical connectors are limited to operating voltages between 28 volts DC and 115 volts AC on the one hand, and + / - 270 volts DC and 230 volts AC on the other. These operating voltage values ​​do not cause partial discharges even when used in an aircraft at altitude.

[0015] In these electrical connectors, the electrical insulators used are made of dielectric materials, i.e. materials that do not contain any free charge capable of conducting electrons. Since electricity needs to transfer the electrical charges that compose it in order to be conducted, this type of material is an insulator since it prevents this conduction. In addition, for electrical connectors specifically intended for the transfer of high power, it is known to use elastomers, glass, air, or polymers as insulators.

[0016] However, although they are good electrical insulators, these materials have major drawbacks for high power use.

[0017] Indeed, elastomers and polymers have a non-zero porosity, which results from their manufacture, and which can reduce insulation performance (to the point of making said materials conductive in certain cases, for example when they are loaded with impurities).

[0018] Using air as an insulator requires significant thicknesses to achieve effective electrical insulation. In addition, at altitude, the conductivity of water in the air can increase to levels that are detrimental to the performance of the insulator.

[0019] Glass, on the other hand, has a permittivity that is too high compared to the other materials mentioned.

[0020] Generally, these closed-cell materials do not allow for rapid, non-destructive verification of the porosity of manufactured parts.

[0021] Furthermore, all these materials have low thermal conductivities (for example, around 0.4 W / mK for an elastomer or 0.3 W / mK for a composite material).

[0022] The low thermal conductivity of these materials has the disadvantage of containing these very significant temperature increases, particularly for high power use. However, the impact of poor heat dissipation (which results from low thermal conductivity) is also premature degradation of the components of electrical connectors.

[0023] Finally, the porosity of these materials induces the existence of partial discharges. In particular, in high power use, partial discharges are established in the cavities of the porous material and can migrate from cavity to cavity until the loss of the electrical insulation function due to the appearance of an arc path. Thus, for example, a cavity larger than 17 micrometers is sufficient to cause premature aging of the electrical insulation by erosion.

[0024] The degradation of the insulation leads to carbon deposits in the cavities (linked to porosity). These deposits can gradually generate conductive paths and thus create an electric arc and, over a long period of time, eventually cause a short circuit. Given the voltage and current levels applied in electrical connectors (for high-power use), the risk of short circuit or even fire is then significant.

[0025] SUMMARY OF THE INVENTION

[0026] The present invention provides a solution to these drawbacks.

[0027] Thus, one objective of the invention is to obtain an electrical connector using an insulator whose shape and the material(s) composing it reduce the risks of partial discharges occurring during high power use while allowing good heat dissipation.

[0028] To this end, the invention according to a first aspect relates to an electrical connector intended to establish an electrical connection with a complementary electrical connector, said electrical connector comprising:

[0029] - a hollow cylindrical body extending around an axis of revolution;

[0030] - at least one electrical contact positioned inside the hollow cylindrical body and extending parallel to the axis of revolution;

[0031] - at least one annular insulator, extending parallel to the axis of revolution and being positioned radially between the at least one electrical contact and the hollow cylindrical body, said electrical connector being characterized in that, over its entire longitudinal extent, the at least one annular insulator has a shape complementary to the shape of the at least one electrical contact and externally covers a surface of the at least one electrical contact, with the exception of a part of said surface of said at least one electrical contact intended to be brought into contact with an electrical contact of the complementary electrical connector, and in that the at least one annular insulator comprises a first annular insulator, made of a glass ceramic, covering a connection zone of the at least one electrical contact.

[0032] The electrical connector according to the invention may comprise one or more of the following features, taken in isolation from one another or in combination with one another:

[0033] - the at least one annular insulator further comprises a second annular insulator, made of an elastomer, preferably silicone, covering a conduction zone of the at least one electrical contact.

[0034] - the electrical connector is of the socket type and the at least one electrical contact is electrically connected to a bus bar or an electrical cable, or the electrical connector is of the plug type and the at least one electrical contact is electrically connected to an electrical cable or a bus bar.

[0035] - at least one electrical contact is of the male type.

[0036] - at least one electrical contact is of the female type.

[0037] - the electrical connector further comprises at least one flat elastomer seal, positioned at a second surface of the at least one radially extending electrical contact, at the interface between said at least one electrical contact and the at least one first annular insulator.

[0038] - the at least one first annular insulator further comprises, on all or part of its surface at the interface with the hollow cylindrical body, a layer of an electrically conductive material.

[0039] - the glass ceramic from which the first annular insulator is made is a zero porosity ceramic.

[0040] The invention according to a second aspect also relates to an assembly comprising two complementary electrical connectors according to the first aspect.

[0041] The invention according to a third aspect finally relates to an aircraft comprising a set of electrical connectors according to the second aspect.

[0042] BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood with the aid of the following description, given solely by way of example and with reference to the appended drawings in which: Figure 1 is a schematic representation of an embodiment of an assembly comprising two electrical connectors according to the invention; Figure 2 is an illustration of an embodiment of annular insulators for an electrical connector according to the invention; Figure 3 is an illustration of an embodiment of annular insulators for an electrical connector according to the invention; Figure 4 is an illustration of an embodiment of annular insulators covering electrical contacts according to the invention; Figure 5 is a schematic representation of an embodiment of an assembly comprising two electrical connectors, with a representation of the creepage lines, according to the invention;Figure 6 is a schematic representation of an embodiment of an assembly comprising two electrical connectors, with a representation of the positioning of at least one flat elastomer seal, according to the invention; Figure 7 is an illustration of an embodiment of annular insulators covered with a layer of an electrically conductive material for an electrical connector according to the invention; Figure 8 is an illustration of an embodiment of annular insulators covered with a layer of an electrically conductive material for an electrical connector according to the invention; and, Figure 9 is a sectional side view of an embodiment of an assembly of electrical connectors where the hollow cylindrical body, on all or part of its radially internal surface, is covered with a layer of a polymer.;

[0043] DESCRIPTION OF THE EMBODIMENTS With reference to Figures 1 to 4, we will now describe an embodiment of an assembly 101 comprising two complementary electrical connectors 103 and 105 according to the invention.

[0044] The example shown in these figures relates more particularly to an assembly 101 comprising two complementary electrical connectors 103 and 105 which are respectively a plug, which comprises an electrical contact 107 of the male type, and a base, which comprises an electrical contact 107 of the female type. Furthermore, in the example shown in FIG. 1, the two electrical connectors 103 and 105 are assembled.

[0045] The term "complementary" herein means that each electrical connector is complementary to the other in the sense that it is configured to fit within the other so as to be held together (e.g., via clamping means) and establish an electrical connection.

[0046] In addition to the non-limiting example shown in these figures, in general, the invention described below applies equally well to a socket-type electrical connector or a plug-type electrical connector, in which the electrical contact is electrically connected to a bus bar (for example by forming a single part with this bus bar; from the English "bus bar") or to an electrical cable (for example by crimping the electrical cable in the electrical contact).

[0047] Likewise, the invention applies to an electrical connector, in which the electrical contact can be of the male type or the female type. For example, a male electrical contact can have a general shape of a stud while a female electrical contact can have a general shape of a hole, complementary to the shape of the stud, to allow these conductive elements to fit into each other.

[0048] The electrical connectors described in the following may be, for example, so-called high-power electrical connectors (also called power connectors), i.e., electrical connectors configured to withstand a direct voltage greater than or equal to 800 Volts and a current greater than or equal to 500 Amperes. These may, for example, be electrical connectors used for the transport of high power in an aircraft.

[0049] Thus, the assembly 101 shown in Figure 1 comprises two connectors 103 and 105. Each electrical connector 103 or 105 is intended to establish an electrical connection with the other electrical connector 105 or 103 which is said to be complementary. Each connector 103 and 105 comprises a hollow cylindrical body 109 which extends around an axis of revolution X. This hollow cylindrical body 109, for example made of metal (for example stainless steel or aluminum), is not shown in Figure 1 but is shown in Figure 9.

[0050] Throughout the following, the “longitudinal” and “radial” directions are defined with reference to said axis of revolution of the connector.

[0051] Each connector 103 and 105 also includes an electrical contact 107 which is positioned inside the hollow cylindrical body 109 and which extends parallel to the axis of revolution X.

[0052] Finally, each connector 103 and 105 comprises an annular insulator 111, which extends parallel to the axis of revolution X and which is positioned radially between the electrical contact 107 and the hollow cylindrical body 109.

[0053] In the non-limiting example shown, each electrical connector 103 and 105 comprises a single electrical contact 107, however the invention also applies to an electrical connector which comprises a number of electrical contacts greater than or equal to 1 and one or more annular insulators surrounding these electrical contacts.

[0054] Furthermore, in the non-limiting example shown, the electrical contact 107 of the electrical connector 103 is electrically connected to an electrical cable 113 (in this case by crimping the electrical cable 113 into the electrical contact 107) while the electrical contact 107 of the electrical connector 105 is electrically connected to a bus bar 115 (in this case by forming only one piece therewith).

[0055] The annular insulator 111 has a shape complementary to the shape of the electrical contact 107 and covers its surface (i.e. the outer surface of the electrical contact) over its entire longitudinal extent (that of the annular insulator) except the part 108 of the surface (visible in FIG. 6) of the electrical contact 107 intended to be brought into contact with an electrical contact of the complementary electrical connector.

[0056] In addition, the annular insulator 111 comprises a first annular insulator 111a, which is made of a glass ceramic and which covers a connection area 117 of the electrical contact 107.

[0057] For each electrical connector 103 and 105, the connection zone 117 designates the part of the longitudinal extent of the electrical contact 107, and by extension the part of the longitudinal extent of the electrical connector itself, which is intended to establish contact between two electrical connectors, in particular by inserting a male electrical contact 107 into a female electrical contact 107.

[0058] The glass ceramic may be, for example, a zero-porosity ceramic, i.e., a ceramic that has high electrical insulation properties, while having zero porosity induced by its manufacture. This may be, for example, Macor®, i.e., a ceramic whose composition consists of 55% fluorophlogopite and 45% borosilicate glass.

[0059] In addition, glass ceramic is known for its high dielectric power and for being naturally resistant to aging induced by the possible appearance of partial discharges in air cavities (or vacuoles).

[0060] Furthermore, glass ceramic also acts as a thermal conductor, as it has a higher thermal conductivity than the materials used in the state of the art and therefore prevents excessive temperature rise.

[0061] Finally, glass ceramic itself has resistance to temperatures above 800°C.

[0062] In the non-limiting example shown, the annular insulator 111 also comprises a second annular insulator 111b, made of an elastomer, such as silicone, which covers a conduction zone 119 of the electrical contact 107.

[0063] For each electrical connector 103 and 105, the conduction zone 119 designates the part of the longitudinal extent of the electrical contact 107, and by extension the part of the longitudinal extent of the electrical connector itself, in which the electrical connection is established with a bus bar or a cable, whether it is a plug-type or receptacle-type connector.

[0064] Thus, the annular insulator 111, which comprises the first annular insulator 111a and the second annular insulator 111b, externally covers the entire (radially external) surface of the electrical contact 107, with the exception of the part 108 of said surface which is intended to be brought into contact with a complementary electrical contact of a complementary electrical connector (as shown in particular in FIG. 6).

[0065] The elastomer has a high dielectric strength, while also being resistant to high temperatures. The use of an elastomer insulator helps limit the existence of air gaps that could cause partial discharges.

[0066] In particular, such an elastomer insulator may be compressed, when the electrical connector is assembled, for example by means of clamping means included in the hollow cylindrical body of the electrical connector 109, to give the assembled electrical connector better sealing and reduce the potential presence of air gaps between the different parts of said electrical connector.

[0067] Furthermore, as can be seen in FIG. 1, the second elastomer insulator 111b bears on the first elastomer insulator 111a so that it can compress the latter, in particular under the effect of thermal expansion, and thus reduce the presence of spaces (i.e. interstices) potentially filled with air.

[0068] More specifically, in the non-limiting example shown, the second annular insulator 111b is located behind the first annular insulator 111a (relative to the connection zone 117) with a flat face extending radially in contact with a complementary face of the first annular insulator 111a.

[0069] This configuration is particularly relevant for the non-limiting example described here in which the first annular insulator 111a comprises, in the connection zone 117, two distinct parts 111a and 111b, of complementary shape, which fit into each other.

[0070] In the non-limiting example shown in Figure 1 and Figures 5 and 6 in particular, with regard to the electrical connector 103, the first part lllaa of the first annular insulator 111a has a ring shape and the second part lllab of the first annular insulator 111a has a sleeve shape, complementary to the shape of the first part lllaa on the one hand (and which therefore covers said first part lllaa of the first annular insulator 111a of the electrical connector 103) and of the second part lllab of the first annular insulator 111a of the electrical connector 105 (and which therefore also covers said second part lllab of the first annular insulator 111a of the electrical connector 105).

[0071] Furthermore, with regard to the electrical connector 105, the first part lllaa of the first annular insulator 111a also has a ring shape, the internal diameter of which varies once (i.e. in a single position according to the longitudinal extent of the part), so as to form a support for a complementary shoulder formed in the second part lllab of the first annular insulator 111a.

[0072] In any case, the pressure exerted by the second annular insulator 111b on the first annular insulator 111a tends to keep the parts lllaa and lllab of the latter tight when the electrical connector 103 or 105 is assembled.

[0073] Figures 2, 3 and 4 show respectively the parts lllaa and lllab of the first annular insulator 111a for an electrical contact 107 of male type, before mounting of the electrical connector, the parts lllaa and lllab of the first annular insulator 111a for an electrical contact 107 of female type, also before mounting of the electrical connector, and finally, the male electrical contact 107 (in the left part of Figure 4) and the female electrical contact 107 (in the right part of Figure 4) covered by their respective annular insulators.

[0074] The division of the first annular insulator 111a into several pieces lllaa and lllab facilitates its manufacture and the positioning of the pieces of the insulator during the assembly of the electrical connector, in particular by making it possible to position pieces of the annular insulator on either side of a shoulder of the electrical contact (as is the case in the example shown in Figure 1) before tightening the assembly.

[0075] Indeed, the electrical contact 107 may have a shoulder, that is to say a local modification of its section, on which, due to its complementary shape, the first annular insulator 111a comes to bear so as to block the translation of the electrical contact 107 along the axis X.

[0076] In this case, the different parts of the first annular insulator 111a come into contact, on either side of the shoulder, at the time of assembly of the electrical connector 103 or the electrical connector 105.

[0077] In all cases, for each annular insulator, the person skilled in the art will know how to adapt the shape and number of these parts to facilitate the manufacture and assembly of an electrical connector, in particular according to the desired shape for the electrical contact and the hollow cylindrical body.

[0078] In addition, the shape and arrangement of the different parts constituting the first annular insulator 111a can be optimized to reduce the risk of partial discharge occurring, in particular by lengthening the leakage lines (represented by the lines 123 in FIG. 5) located at the interfaces between these parts.

[0079] Indeed, at the working voltage, a sufficient length of these lines is necessary so that localized electrical discharges do not short-circuit the insulating gap separating the electrical contact 107 from the hollow cylindrical body 109.

[0080] Figure 6 shows a particular embodiment in which each electrical connector 103 and 105 of the assembly 101 further comprises a flat seal 125, which is also made of elastomer, and which is positioned at a surface of the electrical contact 107 which extends radially, at the interface between the electrical contact 107 and the first annular insulator 111a.

[0081] In other embodiments, the number and position of the flat seals may be different, with the aim in all cases of lengthening the current leakage lines, but also of further limiting the presence of air gaps at the interfaces between the different elements included in the electrical connector. Figures 7 and 8 show yet another embodiment, in which the first annular insulator 111a further comprises, on all or part of its surface at the interface with the hollow cylindrical body 109, a layer 127 of an electrically conductive material.

[0082] More specifically, Figure 7 shows the parts lllaa and lllab of the first annular insulator 111a, adapted to a male type electrical contact, partly covered with a layer 127 of an electrically conductive material, while Figure 8 shows the parts lllaa and lllab of the first annular insulator 111a, adapted to a female type electrical contact, partly covered with a layer 127 of an electrically conductive material.

[0083] Advantageously, this type of deposition has the advantage of reducing the occurrence of partial discharge by placing the first annular insulator 111a and the hollow cylindrical body 109 at the same potential. Indeed, the equipotentiality obtained thanks to the presence of a conductive coating 127 on the external surface of the parts lllaa and lllab reduces the risks of the occurrence of electric discharges.

[0084] Finally, Figure 9 shows (for a socket-type electrical connector in the upper part and for a plug-type electrical connector in the lower part) an embodiment in which the hollow cylindrical body 109 of the electrical connector (not shown) comprises, on a part of its radially internal surface, a layer 129 of a polymer. It may for example be a fluoropolymer material such as PFA (for Perfluoroalkoxy) and here again, the advantage of such a deposit is the reduction of the presence of air gaps potentially at the origin of the occurrence of partial discharges.

[0085] Finally, the arrangement and material used for the annular insulator, and in particular the first annular insulator, make it possible to considerably reduce the presence of air zones (vacuoles), to increase the permittivity of the insulator and the resistance to high temperatures of the electrical connector as a whole.

Claims

CLAIMS [1] Electrical connector (103, 105) for establishing an electrical connection with a complementary electrical connector (103, 105), said electrical connector (103, 105) comprising: - a hollow cylindrical body (109) extending around an axis of revolution (X); - at least one electrical contact (107) positioned inside the hollow cylindrical body (109) and extending parallel to the axis of revolution (X); - at least one annular insulator (111), extending parallel to the axis of revolution (X) and being positioned radially between the at least one electrical contact (107) and the hollow cylindrical body (109), said electrical connector (103, 105) being characterized in that the at least one annular insulator (111) has a shape complementary to the shape of the at least one electrical contact (107) and externally covers a surface of the at least one electrical contact (107), with the exception of a portion (108) of said surface of said at least one electrical contact (107) intended to be brought into contact with a complementary electrical contact (107) of the complementary electrical connector (103, 105), in that the at least one annular insulator comprises a first annular insulator (111a), made of a glass ceramic, covering a connection zone (117) of the at least one electrical contact (107),and in that the at least one annular insulator (111) further comprises a second annular insulator (111b), made of an elastomer, preferably silicone, covering a conduction zone (119) of the at least one electrical contact (107)., [2] The electrical connector (103, 105) of claim 1, wherein said electrical connector (103, 105) is of the socket type and the at least one electrical contact (107) is electrically connected to a bus bar (115) or to an electrical cable (113), or said electrical connector (103, 105) is of the plug type and the at least one electrical contact (107) is electrically connected to the electrical cable (113) or to the bus bar (115). [3] Electrical connector (103, 105) according to claim 1 or claim 2, wherein the at least one electrical contact (107) is of the male type. [4] Electrical connector (103, 105) according to claim 1 or claim 2, wherein the at least one electrical contact (107) is of the female type. [5] An electrical connector (103, 105) according to any one of claims 1 to 4, said electrical connector (103, 105) further comprising at least one flat elastomer gasket (125), positioned at a second surface of the at least one electrical contact (107), extending radially at the interface between said at least one electrical contact (107) and the at least one first annular insulator (111). [6] Electrical connector (103, 105) according to any one of claims 1 to 5, wherein the at least one first annular insulator (111a) further comprises, on all or part of its surface at the interface with the hollow cylindrical body (109), a layer (127) of an electrically conductive material. [7] Electrical connector (103, 105) according to any one of claims 1 to 6, wherein the glass ceramic in which the first annular insulator (111a) is made is a zero porosity ceramic. [8] Assembly (101) comprising two complementary electrical connectors (103, 105) according to any one of claims 1 to 7. [9] Aircraft comprising an assembly of electrical connectors according to claim 8.

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