ELECTRICAL CONNECTOR
The electrical connector design with glass ceramic and elastomer insulators, along with a conductive layer, addresses insulation degradation and heat dissipation issues, enhancing reliability and safety under high power and temperature variations.
Patent Information
- Application Number
- FR2023003105
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-03-30
- Publication Date
- 2026-01-30
- Estimated Expiration
- 2043-03-30
AI Technical Summary
Existing electrical connectors in aircraft face issues with partial discharges due to high voltage and temperature variations, leading to insulation degradation and potential short circuits, especially when using dielectric materials like elastomers, polymers, and air, which have porosity and low thermal conductivity, causing premature aging and increased fire risk.
An electrical connector design using a glass ceramic insulator with zero porosity and high thermal conductivity, combined with an elastomer insulator for better sealing and a conductive layer to reduce partial discharges, along with a flat elastomer seal to minimize air gaps, ensuring effective insulation and heat dissipation.
The solution significantly reduces the risk of partial discharges and maintains effective insulation under high power conditions, preventing premature aging and potential short circuits, while maintaining thermal stability and reducing the risk of fire.
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Abstract
Description
Title of the invention: ELECTRICAL CONNECTOR technical field
[0001] The invention relates to the field of electrical connection devices for the transmission of 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 to an assembly comprising two complementary electrical connectors. Previous technique
[0002] Current efforts to decarbonize aircraft are leading to the integration of more and more electrical systems within them. Aircraft hybridization or electrification is part of this trend and is creating a new need for so-called high-power electrical connectors, i.e., those capable of withstanding high voltages and currents.
[0003] The preferred approach to achieving high power levels consists mainly of increasing the voltage levels within the aircraft's onboard 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.
[0004] Thus, the voltages currently envisaged for aircraft onboard networks are in the order of 800 to 1,000 Volts (in direct voltage) but could eventually tend towards 3,000 Volts for currents of the order of 500 Amperes.
[0005] Such voltage and current values, combined with use at a high altitude (e.g. 55,000 feet) which involves large variations in temperature (e.g. from -55°C to +250°C), pressure and humidity, lead to the occurrence of physical phenomena that are rare or otherwise non-existent.
[0006] Thus, a known phenomenon associated with such operating conditions is partial discharge. This is a localized discharge, which results from a temporary ionization of a gas in an electrically insulated system, and which occurs when the electrical stress (the electric fields) exceeds a critical value.
[0007] This phenomenon is critical insofar as it can lead to decreased performance and deterioration of an electrical system in which it occurs.
[0008] With regard to 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.
[0009] In particular, in the context of use in an aircraft, where an electrical connector is subjected 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 protections and the cutting off of the power supply to the loads of the aircraft's electrical system (motors, actuators, etc.).
[0010] For these reasons, in the current state of the art, electrical connectors intended for aeronautical use are replaced by terminal blocks when they are to be used for high power.
[0011] 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.
[0012] In these electrical connectors, the electrical insulators used are made of dielectric materials, that is, materials containing no free charge capable of conducting electrons. Since electricity needs to transfer its constituent electrical charges in order to be conducted, this type of material is insulating because it prevents this conduction.
[0013] 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.
[0014] However, although these materials are good electrical insulators, they have major drawbacks for high-power use.
[0015] Indeed, elastomers and polymers have a non-zero porosity, which results from their manufacture, and which can reduce insulation performance (even making said materials conductive in some cases, for example when they are loaded with impurities).
[0016] Using air as insulation requires significant thicknesses to achieve effective electrical insulation. Furthermore, at high altitudes, the water content of the air can increase its conductivity to levels detrimental to the insulation's performance.
[0017] Glass, on the other hand, has a permittivity that is too high compared to the other materials mentioned.
[0018] In general, these closed-cell materials do not allow for a non-destructive and rapid verification of the porosity of the manufactured parts.
[0019] Moreover, all these materials exhibit low thermal conductivities (for example, on the order of 0.4 W / mK for an elastomer or 0.3 W / mK for a composite material).
[0020] The low thermal conductivity of these materials has the disadvantage of containing these very high temperature increases, particularly for high-power applications. However, the impact of poor heat dissipation (resulting from low thermal conductivity) is also premature degradation of the electrical connector components.
[0021] Finally, the porosity of these materials leads to the existence of partial discharges. In particular, under high-power conditions, partial discharges occur in the cavities of the porous material and can migrate from cavity to cavity until the electrical insulation function is lost due to the formation of an arc path. Thus, for example, a cavity larger than 17 micrometers is sufficient to cause premature aging of the electrical insulator through erosion.
[0022] The degradation of the insulation leads to carbon deposits in the cavities (due to porosity). These deposits can gradually generate conductive paths, creating an electric arc and, over time, eventually causing a short circuit. Given the voltage and current levels applied in electrical connectors (for high-power applications), the risk of a short circuit or even a fire is significant. Summary of the invention
[0023] The present invention proposes a solution to these drawbacks.
[0024] Thus, an objective of the invention is to obtain an electrical connector using an insulator whose shape and the material(s) which compose it reduce the risks of occurrence of partial discharges during use at high power while allowing good heat dissipation.
[0025] 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:
[0026] - a hollow cylindrical body extending around an axis of revolution;
[0027] - at least one electrical contact positioned inside the hollow cylindrical body and extending parallel to the axis of revolution;
[0028] - at least one annular insulator, extending parallel to the axis of revolution and being positioned radially between at least one electrical contact and the hollow cylindrical body,
[0029] said electrical connector being characterized in that, along 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 portion of said surface of said at least an electrical contact intended to be brought into contact with an electrical contact of the supplementary electrical connector,
[0030] and in that the at least one annular insulator comprises a first annular insulator, made of a glass ceramic, covering a connection area of the at least one electrical contact.
[0031] The electrical connector according to the invention may comprise one or more of the following features, taken individually or in combination with each other:
[0032] - at least one annular insulator further comprises a second annular insulator, made of an elastomer, preferably silicone, covering a conduction area of at least one electrical contact.
[0033] - the electrical connector is of the socket type and at least one electrical contact is electrically connected to a busbar or electrical cable, or the electrical connector is of the plug type and at least one electrical contact is electrically connected to an electrical cable or busbar.
[0034] - at least one electrical contact is of the male type.
[0035] - at least one electrical contact is of the female type.
[0036] - the electrical connector further comprises, at least one flat elastomer seal, positioned at the level of a second surface of at least one electrical contact extending radially, at the interface between said at least one electrical contact and at least one first annular insulator.
[0037] - 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.
[0038] - the glass ceramic in which the first annular insulator is made is a zero porosity ceramic.
[0039] The invention according to a second aspect also relates to an assembly comprising two complementary electrical connectors according to the first aspect.
[0040] The invention according to a third aspect finally relates to an aircraft comprising a set of electrical connectors according to the second aspect. Brief description of the drawings
[0041] The invention will be better understood with the aid of the following description, given solely by way of example and made with reference to the accompanying drawings in which:
[0042] [Fig.1] is a schematic representation of an embodiment of an assembly comprising two electrical connectors according to the invention;
[0043] [Fig.2] is an illustration of an embodiment of annular insulators for an electrical connector according to the invention;
[0044] [Fig.3] is an illustration of an embodiment of annular insulators for an electrical connector according to the invention;
[0045] [Fig.4] is an illustration of an embodiment of annular insulators covering electrical contacts according to the invention;
[0046] [Fig.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;
[0047] [Fig.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;
[0048] [Fig.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;
[0049] Figure 8 illustrates an embodiment of annular insulators covered with a layer of an electrically conductive material for an electrical connector according to the invention; and,
[0050] [Fig.9] is a cross-sectional profile view of an embodiment of an electrical connector assembly where the hollow cylindrical body, on all or part of its radially internal surface, is covered with a layer of a polymer. Description of the implementation methods
[0051] 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.
[0052] 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, comprising a male electrical contact 107, and a socket, comprising a female electrical contact 107. Furthermore, in the example shown in [Fig. 1], the two electrical connectors 103 and 105 are assembled.
[0053] The term "complementary" here means that each electrical connector is complementary to the other in the sense that it is configured to fit into the other so as to be held together (for example via clamping means) and to establish an electrical connection.
[0054] Apart from the non-limiting example shown in these figures, in general, the invention described below applies equally to a socket-type or plug-type electrical connector, in which the electrical contact is electrically connected to a busbar (for example, by forming a single piece with this busbar; (English "bus bar") or to an electrical cable (for example by crimping the electrical cable into the electrical contact).
[0055] Similarly, the invention applies to an electrical connector, in which the electrical contact may be of the male or female type. By way of example, a male electrical contact may have a general stud shape, while a female electrical contact may have a general hole shape, complementary to the stud shape, to allow these conductive elements to be fitted together.
[0056] The electrical connectors described below may be, for example, so-called high-power electrical connectors (also called power connectors), that is, electrical connectors configured to withstand a DC 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 transmission of high power in an aircraft.
[0057] Thus, the assembly 101 shown in [Fig.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.
[0058] Each connector 103 and 105 includes 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 of stainless steel or aluminum), is not represented in [Fig.1] but is shown in [Fig.9].
[0059] Throughout the following, the "longitudinal" and "radial" directions are defined with reference to said axis of revolution of the connector.
[0060] 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.
[0061] Finally, each connector 103 and 105 includes an annular insulator 111, which extends parallel to the axis of revolution X and is positioned radially between the electrical contact 107 and the hollow cylindrical body 109.
[0062] 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.
[0063] 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 with it).
[0064] The annular insulator 111 has a complementary shape 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 for the part 108 of the surface (visible in [Fig.6]) of the electrical contact 107 intended to be made in contact with an electrical contact of the complementary electrical connector.
[0065] In addition, the annular insulator 111 includes a first annular insulator 11la, which is made of a glass ceramic and which covers a connection area 117 of the electrical contact 107.
[0066] For each electrical connector 103 and 105, the connection area 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.
[0067] The glass ceramic may, for example, be a zero-porosity ceramic, that is, a ceramic that exhibits high electrical insulation properties while having zero porosity induced by its manufacturing process. Macor®, for example, is a ceramic whose composition consists of 55% fluorophlogopite and 45% borosilicate glass.
[0068] In addition, glass ceramic is known for its high dielectric power and for being naturally resistant to aging induced by the possible occurrence of partial discharges in air cavities (or vacuoles).
[0069] Furthermore, glass ceramic also plays the role of thermal conductor insofar as it has a thermal conductivity superior to the materials used in the prior art and therefore avoids an excessive rise in temperature.
[0070] Finally, glass ceramic itself exhibits resistance to a temperature exceeding 800°C.
[0071] In the non-limiting example shown, the annular insulator 111 also includes a second annular insulator 111b, made of an elastomer, such as silicone, which covers a conduction zone 119 of the electrical contact 107.
[0072] 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 busbar or a cable whether it is a plug-type or socket-type connector.
[0073] The elastomer exhibits high dielectric strength while also exhibiting resistance to high temperatures. The use of an elastomer insulator makes it possible to limit the existence of air gaps that could cause partial discharges.
[0074] In particular, such an elastomeric insulator can 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 a better seal and reduce the potential presence of air gaps between the different parts of said electrical connector.
[0075] Furthermore, as can be seen in [Fig. 1], the second elastomeric insulator 111b is supported by the first elastomeric insulator 11la so that it can compress the latter, in particular under the effect of thermal expansion, and thus reduce the presence of spaces (i.e. gaps) potentially filled with air.
[0076] 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.
[0077] 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 pieces 11 laa and 11 lab, of complementary shape, which fit into one another.
[0078] In the non-limiting example shown in [Fig. 1] and in Figures 5 and 6 in particular, with regard to the electrical connector 103, the first part 11 laa of the first annular insulator 11 la has a ring shape and the second part 11 lab of the first annular insulator 11 la has a sleeve shape, complementary to the shape of the first part 11 laa on the one hand (and which therefore covers said first part 11 laa of the first annular insulator 11 la of the electrical connector 103) and of the second part 11 lab of the first annular insulator 11 la of the electrical connector 105 (and which therefore also covers said second part 11 lab of the first annular insulator 11 la of the electrical connector 105).
[0079] Furthermore, with regard to the electrical connector 105, the first part 11 laa of the first annular insulator 11 la also has a ring shape, the internal diameter of which varies once (i.e. in a single position along the longitudinal extent of the part), so as to form a support for a complementary shoulder formed in the second part 11 lab of the first annular insulator 111a.
[0080] In all cases, the pressure exerted by the second annular insulator 111b on the first annular insulator 111a tends to keep the parts 11 laa and 11 lab of the latter tight when the electrical connector 103 or 105 is assembled.
[0081] Figures 2, 3 and 4 show respectively the parts 11 laa and 11 lab of the first annular insulator 111a for a male type electrical contact 107, before mounting of the electrical connector, the parts 11 laa and 11 lab of the first annular insulator 111a for a female type electrical contact 107, also before mounting of the electrical connector, and finally, the male electrical contact 107 (in the left part of [Fig.4]) and the female electrical contact 107 (in the right part of [Fig.4]) covered by their respective annular insulators.
[0082] Dividing the first annular insulator 11 la into several pieces 11 laa and 11 lab facilitates its manufacture and the positioning of the insulator pieces during the assembly of the electrical connector, in particular by allowing the positioning of pieces of the annular insulator on either side of a shoulder of the electrical contact (as is the case in the example shown in [Fig.1]) before tightening the assembly.
[0083] Indeed, the electrical contact 107 can 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 rests in such a way as to block the translation of the electrical contact 107 along the X axis.
[0084] 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 the assembly of the electrical connector 103 or the electrical connector 105.
[0085] In all cases, for each ring insulator, a person skilled in the art will be able to adapt the shape and number of these parts to facilitate the manufacture and assembly of an electrical connector, in particular according to the shape required for the electrical contact and the hollow cylindrical body.
[0086] Furthermore, 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 creepage lines (represented by the lines 123 in [Fig.5]) located at the interfaces between these parts.
[0087] 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.
[0088] Fig. 6 shows a particular embodiment in which each electrical connector 103 and 105 of the assembly 101 further includes a flat gasket 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.
[0089] In other embodiments, the number and position of the flat joints may be different, with the aim in all cases of lengthening the vanishing lines of the currents, but also to further limit the presence of air gaps at the interfaces between the different elements included in the electrical connector.
[0090] 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.
[0091] More specifically, [Fig.7] shows the parts 11 laa and 11 lab of the first annular insulator 111a, adapted to a male type electrical contact, partially covered with a layer 127 of an electrically conductive material, while [Fig.8] shows the parts 11 laa and 11 lab of the first annular insulator 111a, adapted to a female type electrical contact, partially covered with a layer 127 of an electrically conductive material.
[0092] Advantageously, this type of deposition has the advantage of reducing the occurrence of partial discharge by bringing the first annular insulator 11 la and the hollow cylindrical body 109 to the same potential. Indeed, the equipotentiality obtained thanks to the presence of a conductive coating 127 on the external surface of the parts 11 laa and 11 lab reduces the risks of occurrence of electrical discharges.
[0093] Finally, [Fig. 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) has, on a portion of its radially internal surface, a layer 129 of a polymer. This could, for example, be a fluoropolymer material such as PFA (for Perfluoroalkoxy), and here again, the advantage of such a coating is the reduction of the presence of air pockets that could potentially cause partial discharges.
[0094] Finally, the arrangement and the material used for the ring insulator, and in particular the first ring 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
Demands
1. Electrical connector (103, 105) intended to establish an electrical connection with a complementary electrical connector (103, 105), said electrical connector (103, 105) comprising: - a hollow cylindrical body (109) extending about 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 at least one electrical contact (107) and the hollow cylindrical body (109), said electrical connector (103, 105) being characterized in that at least one annular insulator (111) has a shape complementary to the shape of at least one electrical contact (107) and externally covers a surface of 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 ring insulator comprises a first ring insulator (111a), made of a glass ceramic, covering a connection area (117) of the at least one electrical contact (107), and in that the at least one ring insulator (111) further comprises a second ring insulator (111b), made of an elastomer, preferably silicone, covering a conduction area (119) of the at least one electrical contact (107).
2. Electrical connector (103, 105) according to claim 1, wherein said electrical connector (103, 105) is of the base type and at least one electrical contact (107) is electrically connected to a busbar (115) or to an electrical cable (113), or said electrical connector (103, 105) is of the plug type and at least one electrical contact (107) is electrically connected to the electrical cable (113) or to the busbar (115).
3. Electrical connector (103, 105) according to claim 1 or claim 2, wherein at least one electrical contact (107) is of the male type.
4. Electrical connector (103, 105) according to claim 1 or claim 2, wherein at least one electrical contact (107) is of the female type.
5. 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 at least one electrical contact (107), extending radially at the interface between said at least one electrical contact (107) and at least one first annular insulator (111).
6. Electrical connector (103, 105) according to any one of claims 1 to 5, wherein 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 (11la) 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 a set of electrical connectors according to claim 8.