PYROTECHNIC SAFETY UNIT FOR AN AIRCRAFT AND AIRCRAFT COMPRISING SUCH A UNIT

Description

DOMAINE TECHNIQUE

[0001] The present invention relates to a system and method for protecting electrical circuits. The invention relates more particularly to an electrical circuit breaker assembly capable of isolating a faulty electrical line in an electrical circuit of an aircraft. The invention also relates to an aircraft comprising such an electrical circuit breaker assembly. ETAT DE LA TECHNIQUE ANTERIEURE

[0002] The electrical power requirements on board an aircraft are constantly increasing, which leads to increasing the voltage levels of electrical sources to maintain acceptable current levels for the transport of energy between a source and the consumer devices connected to it. In the event of an incident on a power line, and an abnormal increase in the current in this line, it is necessary to isolate the line to prevent the fault from spreading to other elements of the electrical circuit. The means usually used to do this no longer meet the specific requirements for use on board an aircraft, given the increasingly high level of voltages and currents used. To isolate a faulty power line, electrical protections including a pyrotechnic element are used in the automotive industry. The advantage of the pyrotechnic element is that it allows for very rapid operation.These systems use a current sensor configured to measure the current drawn in a power line so that, when a sudden and significant increase in current is detected, a control module activates an actuator (or actuator) of a circuit breaker assembly located on the power line, which physically cuts the power line. The actuator is activated by a pyrotechnic element, which gives the short-circuit assembly a very short activation time and therefore allows the faulty power line to be quickly isolated from the rest of the electrical circuit before the fault propagates.

[0003] Equivalent devices exist in aircraft, such as, for example, remote-controlled circuit breakers, sometimes called RCCBs, from the English acronym which stands for " Remote Control Circuit Breaker », electromechanical type, or even semiconductor power controllers, sometimes called SSPC, from the English acronym, which means " Solid State Power Controller » . These devices typically operate functions of protecting cables or power buses, or even switching loads, detecting electric arcs, etc.

[0004] It is known that opening a circuit carrying a current can generate significant overvoltages due to the inductive nature of the circuit. Such an overvoltage, when opening a power supply line, is all the higher when the inductance of the power line is high and the stray capacitances are reduced. The overvoltage at the terminals of an opening point of a power line can be destructive for elements of the circuit. Very often, most of the energy stored in a power line is dissipated in the rupture arc at the moment of opening of the line. The rest of the energy is dissipated in the rest of the electrical circuit, then constituting a defect detrimental to the integrity of the latter.

[0005] The significant increase in the voltage used by aircraft power sources is such that the volume, weight and cost characteristics of certain electrical circuit elements no longer meet the conditions of use on board an aircraft. This is notably due to observed effects described by Paschen's law. Paschen's law makes it possible to characterize the appearance of an electric arc when opening a power supply line as a function of the atmospheric pressure around the point of opening of the power line, and therefore as a function of the altitude of use.

[0006] The situation can therefore be improved.

[0007] Document FR 2 953 324 A1 describes an electrical circuit breaker assembly comprising a conductive element of an electrical circuit and a disconnecting device activatable by a pyrotechnic element, according to the preamble of claim 1. EXPOSE DE L'INVENTION

[0008] The present invention aims in particular to provide an electrical circuit breaker assembly making it possible to quickly isolate a faulty electrical power supply line in an aircraft, before the overvoltage present can be transferred to other elements of the electrical circuit comprising this electrical power supply line, and while avoiding having to oversize components of the aircraft's electrical installation.

[0009] To this end, the subject of the invention is an electrical circuit breaker assembly comprising a conductive element of an electrical supply line of an electrical circuit and a cut-off device activatable by a first pyrotechnic element and configured to cut the conductive element in a predetermined cut-off zone delimited by a downstream point, the electrical circuit breaker assembly further comprising a contactor element activatable by a second pyrotechnic element, the contactor element being configured to connect the downstream point of the predetermined cut-off zone to a ground conductor of the electrical circuit, prior to cutting the conductive element or simultaneously with cutting the conductive element.

[0010] Advantageously, it is thus possible to isolate an electrical supply line presenting an electrical fault from the rest of the electrical circuit and thus limit the propagation of this electrical fault to other elements of the electrical circuit.

[0011] The electrical circuit breaker assembly according to the invention may also include the following characteristics, considered alone or in combination: The second pyrotechnic element and the first pyrotechnic element constitute a single pyrotechnic element. The cut-off device and the contactor device form a single part or are arranged integrally with each other.

[0012] The invention also relates to an electrical protection system comprising an overcurrent detector, also called here a control module, and an electrical circuit breaker assembly as mentioned above.

[0013] Another object of the invention is an electrical circuit comprising such an electrical circuit breaker assembly or an electrical protection system comprising such an electrical circuit breaker assembly.

[0014] The invention also relates to an aircraft comprising an electrical circuit as mentioned above.

[0015] According to one embodiment, the aircraft comprises at least one electric propulsion means.

[0016] The invention further relates to a method for protecting an electrical circuit of an aircraft, the electrical circuit comprising a conductive element of a circuit and a cut-off (sectioning) device activatable by a first pyrotechnic element and configured to section the conductive element in a predetermined cut-off zone delimited by a downstream point, the electrical circuit breaker assembly further comprising a contactor device activatable by a second pyrotechnic element, the contactor element being configured to connect the downstream point of the cut-off zone to a ground conductor of the electrical circuit, the method comprising steps of: (i) detection of a current representative of a current greater than a predetermined threshold established in the conductive element, (ii) connection of the downstream point of the cut-off zone to a ground conductor of the electrical circuit, and, (iii) sectioning of said conductive element in a predetermined cut-off zone.

[0017] According to one embodiment, step (iii) of sectioning the conductor is subsequent to step (ii) of contact connection of the downstream point of the cut-off zone to a ground conductor of the electrical circuit. BREVE DESCRIPTION DES DESSINS

[0018] The above-mentioned features of the invention, as well as others, will appear more clearly on reading the following description of at least one exemplary embodiment, said description being made in relation to the attached drawings, among which: [ Fig. 1 ] schematically illustrates a portion of an electrical circuit comprising an electrical circuit breaker assembly arranged between an electrical energy source and an electrical energy consuming element according to one embodiment; [ Fig. 2 ] schematically illustrates implementation details of the electrical circuit breaker assembly used in the portion of the electrical circuit already shown in the Fig. 1 , before activation; [ Fig. 3 ] schematically illustrates a state of the electrical circuit breaker assembly already shown on the Fig. 2 , after activation of a contactor device; [ Fig. 4 ] schematically illustrates a state of the electrical circuit breaker assembly already shown on the Fig. 3 , after activation of a sectioning device; [ Fig. 5 ] schematically illustrates a variant implementation of the electrical circuit breaker assembly already shown in the Fig. 2 ; [ Fig. 6 ] schematically illustrates a state of the electrical circuit breaker assembly already shown on the Fig. 5 , after activation; [ Fig. 7 ] schematically illustrates internal control circuits of the electrical circuit breaker assembly already shown in the Fig. 2 ; [ Fig. 8 ] schematically illustrates a variant of the internal control circuits of the electrical circuit breaker assembly already shown in the Fig. 2 ; And, [ Fig. 9 ] schematically illustrates an aircraft comprising an electrical circuit breaker assembly according to one embodiment. EXPOSE DETAILLE DE MODES DE REALISATION

[0019] There Fig. 1 schematically represents a portion of an electrical circuit 1000. According to one embodiment, the electrical circuit 1000 is an aircraft electrical circuit. The portion of the electrical circuit 1000 represented comprises an electrical energy source 1 supplying an electrical energy consuming element 11 through an electrical power supply line 10. The electrical power supply line 10 is therefore an electrical power supply line for the consuming element 11. The electrical energy consuming element 11 is any electrical device also commonly called a load, receiver or current receiver. The electrical power supply circuit of the electrical energy consuming element 11 is closed by a connection of the electrical energy source 1 to an electrical ground 14 and a connection of the electrical energy consuming element 11 to this same electrical ground 14.The electrical line 10 comprises an electrical circuit breaker assembly 100 configured to be able to operate, if necessary, a rapid opening of the electrical power line 10 at a location predetermined by the physical position of the electrical circuit breaker assembly 100, between the electrical energy source 1 and the electrical energy consuming element 11. The opening of the electrical power line 10 is required in particular in the event of detection of an electrical fault such as, for example, an overcurrent in this electrical power line. The electrical circuit breaker assembly 100 is configured to be activated, that is to say to be capable of operating an opening of the electrical line 10, from at least one control signal carried by a control line 13. The control signal 13 is delivered by a control module 15 of the electric current present and measured in the electrical power line 10.The control module 15 operates as a supervisor of the electrical current established in the electrical line 10 so that in the event of an overcurrent in the electrical line 10, the control module 15 delivers the activation signal 13 to activate the electrical circuit breaker 100 in order to open the electrical power supply line 10. More precisely, the control module 15 is designed to deliver the activation signal 13 as soon as it detects that the value of the current measured in the electrical power supply line 10 is equal to or greater than a predetermined threshold value. In the present description, the activation signal 13 and the physical medium carrying this signal, i.e. the control line 13, are referred to interchangeably. The control module 15 operates a continuous monitoring of the electrical current present in the electrical power supply line 10.

[0020] The circuit breaker assembly 100 is mounted in series on the electrical supply line 10 between a first point 10a of the electrical line 10, called the “upstream point”, and a second point 10c of the electrical line 10, called the “downstream point”. The electrical circuit breaker assembly 100 is therefore configured to operate an opening of the electrical line in a predetermined zone located between these two points. The term "upstream" is to be interpreted here as meaning arranged on the side of the electrical energy source 1 with respect to an opening point of the electrical power supply line 10, implemented in the electrical circuit breaker assembly 100. Conversely, the term "downstream" is to be interpreted as meaning arranged on the opposite side of the opening point of the electrical power supply line 10 with respect to the electrical energy source 1, that is to say arranged on the side of the electrical energy consuming element 11 with respect to the electrical circuit breaker assembly 100.A ground conductor 12 connects an electrical ground 14 of the electrical circuit 1000 to the electrical circuit breaker assembly 100 at a connection point 12a. The electrical circuit breaker assembly 100 includes an internal contactor device 120 (not shown in the . Fig.1 but visible for example on the Fig. 2 ) allowing the so-called downstream point 10c of the electrical supply line 10 to be connected to the connection point 12a of the ground conductor 12, and therefore consequently to the electrical ground 14 of the electrical circuit 1000, as well as an internal sectioning device 110 (not shown in the Fig. 1 but also visible for example on the Fig. 2 ) capable of physically cutting the electrical line 10 in a predetermined area between the upstream 10a and downstream 10c points, so as to perform a rapid electrical opening of the electrical supply line 10. Advantageously, it is thus possible to short-circuit the electrical supply line 10 in the presence of a fault which occurs downstream of the electrical circuit breaker assembly 100, before disconnecting the electrical supply line 10 from the rest of the electrical circuit 1000. This makes it possible to limit the propagation of an overvoltage or an overcurrent to other elements of the electrical circuit 1000, in particular in the critical case of a highly inductive electrical line which is therefore likely to restore a lot of energy when it opens. Short-circuiting the line before opening makes it possible to make the performance of the electrical circuit breaker assembly 100 independent of the inductance value of the electrical supply line 10.It is advantageously possible to reduce the energy to be dissipated in the electric arc produced by an opening of the electrical supply line 10, and to cancel the overvoltage at the entry points of the electrical circuit breaker assembly 100, and more broadly at all the elements of the electrical circuit 1000.

[0021] The term "contactor" must be interpreted throughout the present description as a device configured to make an irreversible contact between a point of the electrical supply line 10 carrying the electrical circuit breaker device 100, and another point of the electrical circuit 1000 comprising the electrical supply line 10. In this case, the contactor device 120 is configured here to establish a direct electrical contact between the downstream point 10c of the electrical supply line 10 and a point of the ground conductor 12 in the immediate vicinity of the downstream point 10c. In other words, the contactor device 120 operates as a contactor device but also as a diverter, configured and used to divert the energy present in the electrical supply line 10 to the ground conductor 12 and therefore finally to the ground 14 of the electrical circuit 1000, after establishing a contact between these elements.

[0022] According to one embodiment, the contactor device 120 and the line sectioning device 110, internal to the electrical circuit breaker assembly 100, are both configured to be activatable using pyrotechnic means which allow high responsiveness in the event of a fault occurring on the electrical supply line 10.

[0023] The current control circuit 15 can operate by direct or indirect measurement. In the case of a direct measurement, the current measured in the power supply line 10 flows in the control device 15, which comprises a shunt resistor or a transistor. According to a variant, an indirect measurement of the current in the power supply line 10 is used and the control device 15 then comprises a galvanic isolation system between the power supply line 10 and its internal measurement means. According to this variant, a parameter representative of the current established in the power supply line 10 is measured, such as, for example, the magnetic field induced by this current in a coil.

[0024] There Fig. 2 schematically illustrates a principle of implementation of the electrical circuit breaker assembly 100. The electrical circuit breaker assembly 100 comprises a conductive element 10b which connects the upstream 10a and downstream 10c points of the electrical supply line 10. The upstream 10a and downstream 10c points advantageously each comprise electromechanical connection elements (not shown in the figure), such as, for example, a screw terminal, a crimping means, or any equivalent configured for the series connection of the electrical circuit breaker assembly 100 to the electrical supply line 10. A pyrotechnic circuit breaker is arranged opposite the conductor 10b. The pyrotechnic circuit breaker is mainly composed of the disconnecting device 110 made of insulating material and a pyrotechnic element 112 housed in a body 114. This pyrotechnic circuit breaker can be activated from an external signal delivered by a control module.This signal, not shown on the . Fig.2 for simplification purposes, is the activation signal 13 visible on the Fig. 1 . When the activation signal 13 is controlled so as to present its active state, a pyrotechnic solution of the pyrotechnic element 112 is ignited so as to activate the sectioning device 110 by the movement of a piston in a chamber of the body 114. When the sectioning device 110 is moved following the ignition of the pyrotechnic element 112, the sectioning device 110 physically cuts the conductor 10b, at a predetermined cutting point, that is to say opposite the sectioning device 110, and in any case, between the upstream point 10a and the downstream point 10c of the electrical supply line 10.If such irreversible sectioning is very rapid, i.e. in a few milliseconds, the sudden opening of the electrical power supply line 10, which is always more or less inductive in nature, is likely to generate an electric arc that must be controlled as best as possible, unless the effectiveness and integrity of the electrical circuit breaker assembly 100 are compromised. This is all the more true in the context of an aircraft, where pressure variations may occur around the electrical circuit breaker assembly 100 and inside it. Advantageously, and for the purpose of best controlling the desired rapid opening of the electrical power supply line 10 by means of sectioning the conductor 10b, the contactor device 120 is used close to the sectioning device 110.The contactor device 120 is arranged and configured to compress, or even crush, a portion of the ground conductor 12, connecting the circuit breaker assembly 100 to a ground 14 of the electrical circuit 100, so as to short-circuit the electrical supply line 10. Such a short-circuit is carried out by connecting the downstream point 10c of the supply line 10 to the grounding conductor 12. To operate the electrical contact, a contactor device 120, preferably made of conductive material, is also cleverly driven by a pyrotechnic element 122, comprising a pyrotechnic solution. Advantageously and according to a preferred embodiment, the contactor device 120 is activated prior to the activation of the cut-off device 110. This sequencing is carried out by firing the pyrotechnic element 122 before firing the pyrotechnic element 112.According to one embodiment of the invention, the delay between the two firings is fixed and calibrated during the manufacture of the electrical circuit breaker assembly 100. This delay can be determined by a control circuit intended to delay the activation signal of the pyrotechnic element 112 relative to the activation signal of the pyrotechnic element 122. Obviously, the sectioning devices 110 and contactor 120 are arranged so that the activation of one in no way compromises the integrity of the other prior to its activation. Conventionally, the sectioning device 110 comprises a sectioning point configured to operate a cut along a section of the conductor 10b, in a cutting chamber delimited by the body 124 comprising ferromagnetic elements arranged and means for controlling the speed of the piston in the combustion chamber, etc.The contactor device 120 operates according to a similar principle, except that the contactor device 120 is configured not to cut the portion of conductor 12 arranged facing it, but to compress, or even crush, this portion of conductor on the conductor 10c of the power supply line 10, and consequently establish sufficient electrical contact for short-circuiting the electrical power supply line 10. The implementation details of the pyrotechnic elements 112 and 122, respectively arranged in the bodies 114 and 124, are not described here further to the extent that they are not useful for understanding the invention.

[0025] According to an implementation variant, the activation signals of the pyrotechnic elements 112 and 122 are distinct and controlled independently of each other. Advantageously, it is thus possible for an external activation controller, such as the control module 15 shown in the Fig. 1 , to define the predetermined delay between the two respective firings of the two pyrotechnic elements 112 and 122. According to this variant, two activation signals are then connected between the control module 15 and the electrical circuit breaker assembly 100.

[0026] There Fig. 3 illustrates a first internal state of the electrical circuit breaker assembly 100 after activation of the contactor device 120 and before activation of the sectioning device 110. It is possible to observe the electrical contact established between the conductor 12 and the point 10c of the electrical supply line 10.

[0027] There Fig. 4 illustrates a second internal state of the electrical circuit breaker assembly 100 after activation of the contactor device 120 and after subsequent activation of the sectioning device 110. It is possible to observe, in addition to the electrical contact established between the conductor 12 and the point 10c of the electrical supply line 10, the electrical opening of the supply line 10 by physical sectioning of the conductor 10c opposite the sectioning device 110.

[0028] There Fig. 5 schematically illustrates an alternative implementation of the electrical circuit breaker assembly 100 according to which the disconnecting devices 110 and contactor 120 are arranged in a single piece or in two elements mounted integrally with each other, driven by the firing of a single pyrotechnic element 112. Obviously, according to this alternative, a single activation signal is used to activate the establishment of a short circuit between the conductor 10c and the ground conductor 12, and to activate the rapid opening of the electrical supply line 10, by physical sectioning of the conductor 10c. If the structure of the circuit breaker assembly 100 is simplified, which makes the manufacture of the electrical circuit breaker assembly 100 easier and less expensive, the control of the sequencing of the operations of first short-circuiting, then opening of the electrical supply line, is more complex.Indeed, only the mechanical arrangement of the sectioning devices 110 and contactor 120 makes it possible to create a short circuit first and then sectioning, for example, if the contactor device 120 has a more substantial projecting shape than the sectioning device 110. The . Fig. 6 schematically illustrates an internal state of the electrical circuit breaker assembly 100 after activation and in the implementation variant according to which the electrical circuit breaker 100 comprises only one pyrotechnic element 112. It is possible to observe the contact established by compression or crushing between the conductor 10c and the conductor 12, operated by the contactor device 120, as well as the opening of the conductor 10b by sectioning, and therefore of the electrical supply line 10, under the effect of the physical sectioning of the conductor 10b operated by the sectioning device 110 made of insulating material. According to this variant, the two sectioning devices 110 and contactor 120 are set in motion following the firing of the single pyrotechnic element 112.

[0029] There Fig. 7 schematically illustrates an internal activation circuit of the pyrotechnic elements 122 then 112 comprising a delay module Δt which allows a predetermined delay to be defined between the activation of the pyrotechnic element 122 and the subsequent activation of the pyrotechnic element 112. The delay module Δt comprises a delay circuit defining a propagation delay, for example from the combination of a resistive component and a capacitive component. According to the embodiment shown, a single activation signal is used, coming from an element external to the electrical circuit breaker assembly 100, such as the control and activation module 15 shown in the Fig. 1 .

[0030] There Fig. 8 schematically illustrates an internal activation circuit of the pyrotechnic elements 122 then 112 without an internal delay module which makes it possible to define a predetermined delay between the activation of the pyrotechnic element 122 and the subsequent activation of the pyrotechnic element 112. According to this configuration, two independent activation signals 13 and 23 are connected between the control module 15 and the electrical circuit breaker assembly 100. According to this exemplary embodiment, the control module 100 defines the delay between the firing of the pyrotechnic element 122 and the firing of the pyrotechnic element 112. This delay can be fixed or determined according to a criterion, such as, for example, the electrical potential measured by the control module 15 of the electrical supply line 10, or the current established in the electrical supply line 10, measured by the control module 15.

[0031] There Fig. 9illustrates an aircraft 1 comprising the electrical circuit portion 1000 already described and at least one electrical circuit breaker assembly 100 implemented according to one of the embodiments previously described.

[0032] Advantageously, it is possible to quickly control a fault detected on the electrical line 10 of the aircraft 1 thanks to the implementation of the electrical circuit breaker 100 and to isolate the electrical line 10 from the rest of the electrical circuit of the aircraft, quickly and with improved control of the electrical arc phenomena.

[0033] The invention is not limited to the embodiments and examples described above, but more generally relates to any electrical circuit breaker assembly comprising a device for sectioning an electrical supply line as well as a contactor device configured to operate a short circuit between a point of the electrical supply line, downstream of the sectioning point, and a ground or a ground conductor of the electrical circuit which comprises the electrical circuit breaker assembly.

Claims

1. Electrical circuit breaker assembly (100) comprising a conductive element (10b) of an electrical circuit (1000) and a severing device (110) that can be activated by a first pyrotechnic element (112) and that is configured to sever said conductive element (10) in a predetermined cut-off zone (10b) delimited by a downstream point (10c), said electrical circuit breaker assembly (100) being characterized in that it further comprises a contactor element (120) that can be activated by a second pyrotechnic element (122), the contactor element (120) being configured to connect said downstream point (10c) of the cut-off zone to an earth conductor (12) of said electrical circuit (1000) prior to a severing of said first conductor (10b) or simultaneously with the severing of said conductor (10b).

2. Electrical circuit breaker assembly (100) according to Claim 1, wherein the second pyrotechnic element (122) and the first pyrotechnic element (112) constitute one and the same pyrotechnic element.

3. Electrical circuit breaker assembly according to Claim 2, wherein the cut-off device (110) and the contactor device (120) form one and the same part or are arranged integrally with each other.

4. Electrical protection system comprising a control module (15), an overcurrent detector and an electrical circuit breaker assembly (100) according to any one of the preceding claims.

5. Electrical circuit (1000) comprising an electrical circuit breaker assembly (100) according to one of Claims 1 to 3 or an electrical protection system according to Claim 4.

6. Aircraft (1) comprising an electrical circuit (1000) according to Claim 5.

7. Aircraft (1) according to the preceding claim comprising at least one means of electric propulsion.

8. Method for protecting an electrical circuit (1000) of an aircraft (1), the electrical circuit (1000) comprising a conductive element (10b) of a circuit and a severing device (110) that can be activated by a first pyrotechnic element (112) and that is configured to sever said conductive element (10b) in a predetermined cut-off zone delimited by a downstream point (10c), said electrical circuit breaker assembly (100) being characterized in that it further comprises a contactor element (120) that can be activated by a second pyrotechnic element (122), the contactor element (120) being configured to connect said downstream point (10c) of the cut-off zone to an earth conductor (12) of said electrical circuit (1000), said method comprising steps of: - (i) detecting a current that is representative of a current greater than a predetermined threshold established in said conductive element (10), - (ii) connecting said downstream point (10c) of the cut-off zone to an earth conductor (12) of said electrical circuit (1000), and - (iii) severing said conductive element (10b) in a predetermined cut-off zone.

9. Method for protecting an electrical circuit (1000) according to the preceding claim, wherein step (iii) of severing said conductor (10b) is after step (ii) of connecting said downstream point (10c) of the cut-off zone to an earth conductor (12) of said electrical circuit (1000).