ELECTRICAL CONNECTION ASSEMBLY EQUIPPED WITH AN OVERHEAT DETECTOR TO PREVENT THE FORMATION OF AN ELECTRICAL ARC.

Abstract

The invention relates to an electrical connection assembly (1) configured to establish a connection between terminal portions (20, 22) of electrical conductors equipped with eyelet lugs (21, 23) and comprising a thermoformable element (14) configured to deform according to the temperature of the connection assembly (1) so as to establish or break electrical contact between two electrical contact elements (14, 12c). Advantageously, it is thus possible to detect the conditions for the initiation of an electric arc (A) or the presence of a continuous or intermittent electric arc (A) at said connection assembly (1) by heating the thermoformable element (14) during the initiation or in the presence of an electric arc. Fig. 3

Description

Title of the invention: ELECTRICAL CONNECTION ASSEMBLY EQUIPPED WITH AN OVERHEATING DETECTOR TO PREVENT THE FORMATION OF AN ELECTRICAL ARC. technical field

[0001] The present invention relates to an electrical connection assembly, particularly with lugs, configured to detect a fault in electrical continuity that could generate heat and lead to an electric arc. At least one embodiment relates to an electrical connection assembly for an aircraft electrical circuit. PREVIOUS STATE OF THE ART

[0002] Aircraft architectures are evolving, and aircraft are becoming increasingly electrified with the introduction of high-voltage direct current (HVDC) networks. The introduction of this type of electrical network on board aircraft is accompanied by drawbacks such as the potential presence of series arcs. In direct current, since the voltage does not pass through zero, an arc can persist for much longer than in alternating current, where the zero-voltage crossings result in self-extinction. This is particularly true for bolted lug connections, which are preferable for establishing connections in a high-current power line.Indeed, in the event of improper tightening, a loose connection, excessive contact resistance, or a faulty crimped terminal, a hot spot can appear, which is a precursor to an electric arc. Monitoring techniques exist, requiring temperature sensors or optical fibers connected to a receiver, but these solutions involve numerous components, resulting in increased weight and circuit complexity. Furthermore, failures in the detection systems and false readings can occur, thus reducing the overall reliability of the system.

[0003] The situation can be improved. Description of the invention

[0004] An object of the present invention is to provide an electrical connection assembly by tightening eyelet lug connection elements onto a stud equipped with an overheating detector, a precursor sign of a permanent or intermittent electric arc.

[0005] To this end, an electrical connection assembly is proposed comprising a stud fixed rigidly to a support and from which a thread protrudes from the support, the stud having a head protruding on an opposite side of the support relative to the thread, the arrangement of the assembly being configured so that a nut mounted on the thread can clamp one or more ring terminals between the support and the nut, the connection assembly being arranged such that:

[0006] - at least one first electrical contact element, electrically conductive and thermo-deformable is electrically connected to the stud, and is arranged on the head of the stud opposite a second electrical contact element connectable to a reference equipotential, and,

[0007] - the first thermo-deformable electrical contact element is configured to be electrically isolated from the second electrical contact element when its temperature is below a predetermined threshold value and to be electrically connected to said second electrical contact element when its temperature is above or equal to a predetermined threshold value, or vice versa.

[0008] Thus, the thermomechanical deformation of the first electrical contact element resulting from a temperature rise linked to the degradation of the electrical contact and which can lead to the presence of a permanent electric arc or to the repetitive character advantageously brings this first electrical contact element into contact with the second electrical contact element connected to a reference equipotential, or removes this first electrical contact element from contact with the second electrical contact element connected to a reference equipotential, which respectively constitutes a closing or an opening of a switch between the connection point (here the stud) of the connection assembly and the reference equipotential which can be connected to ground or to a reference electrical potential.Advantageously, such an operation makes it possible to then detect the change of state of the power line concerned via remote means connected to that line, such as, for example, an impedance measuring device, a voltage measuring device, or any other device configured to operate supervisor functions of the power supply line to which it is connected.

[0009] The electrical connection assembly according to the invention may further have the following additional characteristics, considered alone or in combination: - The electrical connection assembly includes a single first thermo-deformable electrical contact element, which includes an electrical resistance or is coupled to an electrical resistance arranged electrically in series between the stud head and a point of the first electrical contact element intended to come into contact with the second electrical contact element. - The electrical connection assembly comprises a plurality of first electrical contact elements, respectively thermo-deformable according to mechanical deformation profiles according to temperature different from each other, and each of which comprises an electrical resistance or is coupled to an electrical resistance arranged electrically in series between said stud head and a point of said first electrical contact element considered intended to come into contact with said second electrical contact element, each of said electrical resistances then having an electrical resistance value different from the other electrical resistances.

[0010] - The electrical connection assembly comprises at least one first element associated electrical contact (combined) with a non-return mechanism configured to lock in position this first electrical contact element electrically in contact with the second electrical contact element with which it cooperates.

[0011] Another object of the invention is a connecting bomier comprising a plurality electrical connection assemblies such as the connection assembly described above.

[0012] The invention also relates to an electrical circuit comprising at least one electrical connection set as previously described and an electrical circuit supervisory device connected to this connection set.

[0013] Finally, the invention relates to an aircraft comprising an electrical connection assembly as previously described, or a bomier as described above, or an electrical circuit as previously mentioned. Brief description of the drawings

[0014] [Fig.1] schematically illustrates an electrical connection set according to one embodiment and in the absence of an electric arc;

[0015] [Fig.2] schematically illustrates the electrical connection assembly already shown in [Fig.1] used to make a connection between two electrical conductors having eyelet lug type terminations, in the absence of an electric arc;

[0016] [Fig.3] schematically illustrates the electrical connection assembly already shown in [Fig.1], showing a thermomechanical deformation of an electrical contact element, in the presence of overheating linked to a degraded electrical contact and which can lead to the appearance of an electric arc;

[0017] [Fig.4] schematically illustrates a first variant of the electrical connection assembly already shown in [Fig.1] to [Fig.3];

[0018] [Fig.5] schematically illustrates a second variant of the electrical connection assembly already shown in [Fig.1] to [Fig.3];

[0019] [Fig.6] schematically illustrates a third variant of the connection set electrical already represented on [Fig.1] to [Fig.3];

[0020] [Fig.7] is an illustration of an electrical circuit comprising two sets connection according to an embodiment and a supervisory device for the power supply line;

[0021] [Fig.8] schematically illustrates an aircraft equipped with at least one set of electrical connections according to one embodiment; and,

[0022] [Fig.9] illustrates an example of the internal architecture of a line supervisor device power supply as already shown in [Fig.7].

[0023] DETAILED STATEMENT OF IMPROVEMENTS

[0024] Figure 1 schematically represents an electrical connection assembly 1 adapted for interconnecting electrical conductors equipped with terminal elements of the lug type, and in particular of the ring lug type. The connection assembly 1 comprises an electrically conductive stud 10, fixed to a support (or base) 12 and having a threaded portion provided with a thread 10t projecting from the support 12. The support 12 is electrically insulating. The stud 10 further includes a stud head lOh (or shoulder lOh) fixed rigidly to the support 12, and projecting on the opposite side of the support 12, relative to the threaded part of the stud 10. This arrangement allows electrical connection lugs to be clamped around the threaded part of the stud 10, by clamping the lugs between the support 12 and a clamping nut having a thread shape complementary to the lOt thread, mounted on the stud 10.A first electrical contact element 14 is fixedly mounted on the stud head lOh. The first electrical contact element 14 is thermoformable, meaning that it deforms progressively according to temperature variations, following a predefined deformation curve. In one embodiment, the first electrical contact element 14 is a bimetallic element that gradually bends as its temperature rises. The support 12, hollow in shape as illustrated, further includes a second electrical contact element 12c, which is electrically conductive and has a connection point to a reference electrical equipotential 19.In one embodiment, the first thermoformable electrical contact element 14 and the second electrical contact element 12c are arranged opposite each other such that, when the deformation of the first electrical contact element 14 exceeds a certain level, and when its temperature exceeds a threshold temperature value, the end of the first electrical contact element 14 makes mechanical contact with the second electrical contact element 12. Thus, the two electrical contact elements 14 and 12c operate together as a normally open contactor acting according to the temperature of the first electrical contact element. In a variant of... In this design, the first thermo-deformable electrical contact element 14 and the second electrical contact element 12c are arranged opposite each other so that, when the deformation of the first electrical contact element 14, initially in mechanical contact with the second contact element 12c, exceeds a certain level, when its temperature exceeds a threshold temperature value, the end of the first electrical contact element 14 moves away from the second electrical contact element 12. Thus, the two electrical contact elements 14 and 12c operate together as a normally closed contactor acting according to the temperature of the first electrical contact element 14.

[0025] Cleverly and advantageously, thanks to the described arrangement of the electrical connection assembly 1, it is possible to detect the presence of signs announcing or confirming a continuous or recurring electric arc at the stud 10, since the presence or initiation of an electric arc induces a rise in the temperature of the stud 10, which rise in temperature propagates to the first electrical contact element 14. A power line supervisory device 17 (not shown in [Fig.1], but visible in [Fig.7]) connected between the stud 10 of the connection assembly 1 and the reference equipotential 19, then has the ability to detect a short circuit between these two equipotentials, or at the very least a reduced or very reduced resistance level.

[0026] Fig. 2 is a partial cross-section illustrating the connection assembly 1 on which and by means of which two ring terminals 20 and 22 are interconnected, respectively connected to electrical conductors 21 and 23. The ring terminals are arranged so as to be passed through the stud 10 and clamped between the face of the support 12 from which the stud 10 protrudes, and a nut 24 having a thread complementary to the thread 10 of the stud 10, which is press-fitted onto the stud 10. The electrical connection assembly 1 appears here in the absence of a heating source, such as an electric arc, and the first electrical contact element 14 is in a rest state, in the absence of thermal deformation.

[0027] Figure 3 illustrates the electrical connection assembly 1 operating the electrical connection already shown in Figure 2, but this time subjected to heating that can lead to the appearance of an electric arc A. The origin of this arc is found, for example, in a loose tightening of the nut 24 on the stud 10, resulting in a variable air gap between the ring terminals 20 and 22. According to the configuration illustrated in Figure 3, the electric arc A is an electric arc whose frequency of occurrence produces a temperature rise in the elements in its vicinity and, by conduction through the stud head, in the first electrical contact element 14, of the bimetallic type, which is then deformed sufficiently to enter in mechanical and electrical contact, at least one predetermined point of contact, with the second electrical contact element 12c connected to the reference equipotential 19.

[0028] Figure 4 illustrates a first embodiment of the electrical connection assembly 1 in which a resistive element 16 (an electrical resistance) is electrically inserted in series between the head of the stud 10 and the first electrical contact element 14, so that, when the first electrical contact element 14 is deformed and operates as a closed contactor with the second electrical contact element 12c, the electrical resistance 16 is electrically inserted between the stud 10 and the reference equipotential 19. A first advantage lies in the current limitation implied by the presence of the resistive element 16. A second advantage is that it is possible to separate two electrical connection assemblies made according to the principle of the electrical connection assembly 1 but respectively provided with resistive elements (such as the element 16) of different electrical resistance values.For example, a first set of electrical connections may include a resistive element with an electrical resistance of 5000 ohms and a second resistive element may include a resistive element with an electrical resistance of 6000 ohms.

[0029] Fig. 5 illustrates a second variant of the electrical connection assembly 1 in which the electrical connection assembly 1 comprises a plurality of first thermo-deformable electrical contact elements of the type of element 14. According to the example illustrated in Fig. 5, two first elements 14 and 14' are arranged on the stud head 100, or more precisely on resistive elements 16 and 16' on which they are respectively mounted, opposite the second electrical contact element 12c.

[0030] In this case, the term "first elements" refers to thermo-deformable contact elements, as opposed to one or more "second elements," which are the non-thermo-deformable contact elements with which the first elements come into contact after sufficient deformation, each according to its own calibration. In one embodiment, each of the first thermo-deformable elements 14 and 14' has a different profile of mechanical shape variation (calibration) as a function of temperature, such that one of the first electrical contact elements 14 and 14' comes into contact with the second electrical contact element 12c, while the other of the first electrical contact elements 14 and 14' has not yet been sufficiently deformed by a temperature rise to come into mechanical contact with the second electrical contact element 12c.It is therefore advantageous to perform electric arc detection by degrees or temperature ranges, and consequently, by severity or potential for damage. The example described here is not limiting, and it is possible to arrange a [system / device]. a greater number of first electrical contact elements similar to element 14, for example arranged radially on the stud head lOh and regularly distributed radially around it. In addition, each of the first electrical contact elements 14 and 14' can be associated with a different value of resistive element assembled electrically in series with it, so as to be able to indicate to a remote supervisory device which is or are the first thermo-deformable element(s) in mechanical contact with the second contact element 12c, by detecting its resistive value in the closed electrical circuit.

[0031] Figure 6 illustrates a third variant of the electrical connection assembly 1 in which the first thermoformable electrical contact element 14 is provided with a locking system that, once activated, allows a fault occurrence to be memorized after the eventual disappearance of that fault. The locking system comprises, for example, a rod 15 coupled to the first element 14 arranged to be moved in translation through an opening 12o formed in the support 12, which rod 15 is provided with a non-return locking tab 15w arranged to wedge against a surface of the support 12 peripheral to the opening 12o (at the edge of the opening 12o).In one embodiment, the rod 15 is also a thermoformable element of a specific shape designed to create a spring effect and exert pressure on the first electrical contact element 14 after cooling, thus ensuring continuous mechanical and electrical contact between the electrical contact elements 14 and 12c. This implementation is, of course, merely an example provided for illustrative purposes, and many other locking systems can be implemented. In another embodiment, a portion of the rod 15 protrudes from the support 12 through the opening 12a before activation, and no longer protrudes after activation when the lock is operational, acting as a visual activation indicator.According to one embodiment, a large portion of the rod 15 protrudes before activation, and only a small portion of the rod 15 protrudes after activation, allowing the remaining visible portion to be manipulated to unlock the illustrated locking system. More generally, the electrical connection assembly 1 may include an automatic locking system in the activated position as well as a manual or remotely controlled unlocking system, thus allowing the electrical connection assembly 1 to be "reset" to its functional configuration as it was prior to a temperature fault occurrence (for example, in the presence of an electric arc).

[0032] Figure 7 schematically illustrates an electrical power supply line comprising three electrical conductors 21, 26, and 23 assembled by means of two electrical connection assemblies, one of which is electrical connection assembly 1 comprising The stud 10 and the other is an electrical connection assembly 1' comprising a stud 10' and similar to connection assembly 1, except that it includes a resistive element, connected in series with its thermoformable element, having a resistance value different from that of a resistive element of the same function in connection assembly 1. The reference equipotential 19 of connection assembly 1 is connected to an electrical ground, and the reference equipotential 19' of connection assembly 1' is also connected to an electrical ground. In addition, an electronic supervisory device 17 for one or more power supply lines is connected to a point on the power supply line of the electrical conductor 26. The supervisory device 17 includes a reference equipotential 190, which is also connected to an electrical ground.

[0033] According to the example described, the illustrated power supply line is a power supply line delivering direct current on board an aircraft. In some variations, the reference equipotentials 19, 19' and 190 could be connected to a common reference equipotential other than ground.

[0034] Advantageously, in the presence of heating at the interconnection of electrical conductors 21 and 23, local heating causes an increase in the temperature of the stud 10 of the connection assembly 1. This temperature increase propagates to the first thermo-deformable electrical contact element 14, calibrated to deform sufficiently, beyond a threshold temperature value, to make contact with the second electrical contact element 12c, which induces a connection of the resistive element 16 of the electrical connection assembly 1 between the conductor 23 and ground. Consequently, the power line monitoring device 17 has the capacity to detect, and does detect, a fault. For example, the monitoring device 17 measures the voltage level to which the electrical conductor 26 is subjected and can determine the resistance value inserted in the circuit.Thus, the supervisory device 17 can not only detect the presence of a fault of electrical origin but also locate its source in the aircraft from the measured voltage level, if each of the electrical connection assemblies present is provided with a resistance of a different value from the other resistances which equip respectively the other electrical connection assemblies similar to electrical connection assembly 1, such as electrical connection assembly 1'. .

[0035] Figure 8 schematically illustrates an aircraft 100 comprising the electrical power supply line shown schematically in Figure 7. The aircraft therefore includes the electrical connection assembly 1, which advantageously overcomes the drawbacks inherent in the occurrence of a hot spot or an electric arc in the event of a loose connection in an electrical connection made using this electrical connection assembly 1. Advantageously, very Many electrical connection sets such as described can be fitted to aircraft systems 1.

[0036] Fig. 9 schematically illustrates an example of the internal architecture of the supervisory device 17 of the aircraft 1 power supply line.

[0037] According to the hardware architecture example shown in [Fig.9], the power supply line supervisor device 17 then comprises, connected by a communication bus 170: a processor or CPU (Central Processing Unit) 171; a RAM (Random Access Memory) 172; a ROM (Read Only Memory) 173; a storage unit such as a hard disk drive (or a storage media reader, such as an SD card reader (Secure Digital) 174); a power and communication interface module 175 enabling the power supply line supervisor device 17 to communicate with remote devices, such as sensors or actuators, including in particular one or more electrical connection sets similar to the electrical connection set 1 or 1'.

[0038] The processor 171 of the supervisory device 17 is capable of executing instructions loaded into RAM 147 from ROM 173, external memory (not shown), a storage medium (such as an SD card), or a communication network. When the supervisory device 17 is powered on, the processor 171 is capable of reading instructions from RAM 172 and executing them. These instructions form a computer program causing the processor 171 of the device 17 to implement all or part of a method for monitoring the status of at least one power supply line, in particular based on information obtained from one or more sets of electrical connections.

[0039] All or part of such a method for monitoring the status of a power supply line can then be implemented in software form by executing a set of instructions by a programmable machine, for example a DSP (Digital Signal Processor) or a microcontroller, or be implemented in hardware form by a dedicated machine or component, for example a FPGA (Field-Programmable Gate Array) or an ASIC (Application-Specific Integrated Circuit). In general, the supervisory device 17 of one or more power supply lines comprises electronic circuitry configured to implement a method for monitoring power supply lines.Obviously, the supervisor device 17 also includes or is coupled to all the elements usually present in an electronic system comprising a control unit and its peripherals, such as, a power supply circuit, a power supply supervision circuit, one or more. clock circuits, a reset circuit, input / output ports, interrupt inputs, bus drivers, this list is not exhaustive.

[0040] Advantageously, and thanks to the electrical connection assembly described, it is possible to detect the presence of a heating precursor of an electric arc and, if necessary, to isolate the electrical line concerned to avoid or limit damage to this electrical line or in its vicinity.

[0041] The invention is not limited to the examples and embodiments described, but more generally to any electrical connection device with a stud or screw provided with a thermoformable element arranged such that heating of the retaining element, namely the stud or screw, causes deformation of the thermoformable element, which then acts as a contactor for opening or closing an electrical circuit. In particular, the invention can be applied to various electrical distribution networks, for example, direct current or alternating current.

Claims

Demands

1. An electrical connection assembly (1) comprising a stud (10) fixed rigidly to a support (12) and having a thread (l) projecting from said support (12), said stud (10) having a head (lOh) projecting on an opposite side of said support (12) relative to said thread, the arrangement of said assembly (1) being configured so that a nut (24) mounted on said thread (lOt) can clamp one or more ring terminals between said support (12) and said nut (24), the connection assembly (1) being characterized in that: - at least one first electrically conductive and thermoformable electrical contact element (14) is electrically connected to said stud (10), and is arranged on said head (lOh) of said stud (10) opposite a second electrical contact element (12c) connectable to a reference equipotential (19), and, - said first electrical contact element (14), thermo-deformable,is configured to be electrically isolated from the second electrical contact element (12c) when its temperature is below a predetermined threshold value and to be electrically connected to said second electrical contact element (12c) when its temperature is greater than or equal to a predetermined threshold value, or vice versa.

2. Electrical connection assembly according to claim 1, comprising a single first thermo-deformable electrical contact element, which includes an electrical resistance (16) or is coupled to an electrical resistance (16) arranged electrically in series between said stud head (100) and a point of said first electrical contact element (14) intended to come into contact with said second electrical contact element (12c).

3. An electrical connection assembly according to claim 1, the assembly comprising a plurality of first electrical contact elements (14, 14'), each thermoformable according to different deformation profiles, and each comprising an electrical resistance (16, 16') or is coupled to an electrical resistance (16, 16') arranged electrically in series between said stud head (1Oh) and a point of said first electrical contact element considered (14, 14') intended to come into contact with said second electrical contact element (12c), each of said electrical resistances (16, 16') having an electrical resistance value different from the other electrical resistances (16, 16').

4. Electrical connection assembly according to any one of claims 1 to 3, wherein at least one first electrical contact element (14) is associated with a non-return mechanism (15, 15w, 16o) configured to lock said first electrical contact element (14) in position electrically in contact with said second electrical contact element (12c).

5. Connection terminal block comprising a plurality of electrical connection sets (1, 1') according to any one of claims 1 to 4.

6. Electrical circuit (21, 26, 23) comprising an electrical connection assembly (1) according to any one of claims 1 to 4 and an electrical circuit supervisor device (17) electrically connected to said connection assembly (1).

7. Aircraft (100) comprising an electrical connection assembly (1) according to any one of claims 1 to 4, a terminal block according to claim 5 or an electrical circuit according to claim 6.