Aircraft with cable harness

Abstract

The aircraft (100) comprises: - first and second electrical devices (120); - a harness (122) comprising a plurality of cables connecting the first and second electrical devices (120) to each other and having, at one end, a connector (310) connected to a complementary connector (304) of the second electrical device (120); - a sheath (202) surrounding at least one of the cables and in which air circulates in order to cool the cable or cables. Furthermore: - the sheath (202) has an air inlet; - the aircraft (100) comprises a device for generating an air flow entering the air inlet of the sheath (202); - at least one of the first and second electrical devices (120) is designed to provide an electrical voltage of at least 200 V between two of the cables in the harness (122); - the sheath (202) also surrounds at least part of the connector (310); and - the aircraft (100) comprises a pressure maintaining system designed to maintain an air pressure of at least 500 mbar in the sheath (202) as long as there is a pressure of at least 500 mbar at the air inlet of the sheath (202).

Description

Description TITLE: AIRCRAFT WITH CABLE HARNESS Technical field of the invention

[0001] The present invention relates to an aircraft, in particular comprising a cable harness for connecting together two electrical devices of the aircraft.

[0002] The invention is particularly applicable in the context of high electrical power transmission on board an aircraft. Technological background

[0003] Climate change is a major concern for many legislative and regulatory bodies worldwide. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by different countries. In particular, an ambitious standard applies to both new types of aircraft and those already in operation, requiring the implementation of technological solutions to bring them into compliance with current regulations. Civil aviation has been actively working for several years now to contribute to the fight against climate change.

[0004] Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. The Applicant takes into account the factors impacting all phases of design and development in order to obtain less energy-intensive and more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental impacts, with the aim of improving the energy efficiency of aircraft.

[0005] Consequently, the Applicant is constantly working to reduce its climate impact by using methods and operating virtuous development and manufacturing processes that minimize greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity.

[0006] This sustained research and development work focuses on both new generations of aircraft engines and the reduction of aircraft weight, particularly through the materials used and lighter onboard equipment. development of the use of electrical technologies to provide propulsion, and, as essential complements to technological progress, aviation biofuels.

[0007] When using high voltages (for example, above 230 V between phase and neutral for an alternating voltage and above 270 V between phases for a direct or pulse-width modulated voltage), transient and / or functional voltages may be sufficiently high (for example above 320 V) to allow the occurrence of partial discharges, especially taking into account the constraints imposed in aeronautics: low pressure, high temperatures, large temperature gradient, etc.

[0008] To address the problem of partial discharges in a harness, it is known to reinforce its electrical insulation, for example by changing the insulation or the harness structure (insulation thickness, use of coaxial cables, elimination of gaps or air spaces in connectors, metallization of certain parts of the components to reduce voltages across the vacuoles, etc.). All these modifications result in an increase in the harness's volume, while only limited spaces are generally available for its routing. The harness's weight is also increased.

[0009] Furthermore, the use of high power means that, even with high voltages, the current flow remains significant, resulting in Joule heating losses and a substantial increase in harness temperature. This situation is exacerbated by the fact that the harness typically passes through areas of the aircraft with high temperatures. To reduce temperature and Joule heating losses, the cables are equipped with center conductors of a large cross-section.

[0010] However, partial discharges are a factor in the aging of the harness cables, even more impactful than temperature. Furthermore, as explained previously, known solutions to avoid these problems involve increasing the size of the harness.

[0011] It may therefore be desirable to plan for an aircraft that makes it possible to overcome at least some of the aforementioned problems and constraints.

[0012] The prior art also includes document US 2022 045573 A1. Summary of the invention

[0013] An aircraft is therefore proposed comprising: first and second electrical devices; a harness comprising several cables connecting the first and second electrical devices to each other and having, at one end, a connector connected to a complementary connector of the second electrical device; a sheath surrounding at least one of the cables and through which air circulates to cool the cable(s); characterized in that: the sheath has an air inlet; the aircraft includes a device for generating airflow entering the air inlet of the sheath; at least one of the first and second electrical devices is designed to provide an electrical voltage of at least 200 V between two of the cables of the harness; the sheath also surrounds at least part of the connector;and the aircraft includes a pressure maintenance system designed to maintain an air pressure of at least 500 mbar in the duct as long as there is a pressure of at least 500 mbar at the air inlet of the duct.

[0014] Thus, thanks to the invention, the sheath is used both to dissipate heat from the harness cables, without requiring a fan to circulate air thanks to the use of the turbomachine's airflow, and also to prevent a drop in air pressure that could increase the risk of partial discharge. This therefore allows for a reduction in the harness's volume.

[0015] The invention may further include one or more of the following optional features, in any technically feasible combination.

[0016] Optionally, the airflow generation device includes a turbomachine designed to be traversed by an upstream to downstream airflow, with the duct's air inlet connected to the airflow so that a portion of it circulates within the duct. The turbomachine may, for example, be propulsive.

[0017] Optionally, the aircraft also includes a wing and a pylon supporting the turbomachine, the second electrical device is attached to the turbomachine and the harness passes through the pylon to join the wing.

[0018] Optionally, the turbomachine is also designed so that, when the turbomachine is in idle mode in flight, the airflow at the duct air inlet has a pressure of at least 500 mbar, when the ambient air pressure is at least 163 mbar.

[0019] Optionally, the airflow generation device also includes a fan.

[0020] Optionally, the duct also has an air outlet which, together with the connector, defines an opening sized so that, as long as there is a pressure of at least 500 mbar at the air inlet of the duct, the air pressure in the duct is at least 500 mbar.

[0021] Optionally, the second electrical device also includes a housing from which the additional connector is projected; the connector has a so-called longitudinal part extending along the housing, and the air outlet is located around this longitudinal part.

[0022] Optionally, the second electrical device also includes a housing from which the additional connector is projected; the connector has a so-called transverse part surrounding the additional connector and extending to the housing, and the air outlet is located around this transverse part and faces the housing.

[0023] Optionally, the second electrical device also includes a housing from which the additional connector is projected, the sheath extends around the connector to the housing so as not to leave any opening between the sheath and the housing, and the aircraft also includes, on the sheath, a pressure relief valve designed to maintain the air pressure in the sheath at least 500 mbar.

[0024] Optionally, the second electrical device also includes a housing from which the complementary connector is projected, and the aircraft further includes an enclosure around the housing defining, with the housing, a cavity, the sheath has an air outlet defining, with the connector, an opening leading into the cavity, and the aircraft further includes, on the enclosure, a pressure relief valve designed to maintain an air pressure of at least 500 mbar in the cavity.

[0025] Optionally, the second electrical device also includes an electric machine coupled to a low-pressure body of the turbomachine.

[0026] Optionally, the first electrical device also includes power electronics equipment. Brief description of the figures

[0027] 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: Figure 1 is a side view of an aircraft according to the invention; Figure 2 is a simplified view of two electrical devices of the aircraft and an electrical connection between them; Figure 3 is a cross-sectional view of one end of the electrical connection connected to one of the electrical devices, according to a first embodiment of the invention; Figure 4 is a cross-sectional view of one end of the electrical connection connected to one of the electrical devices, according to a second embodiment of the invention; Figure 5 is a cross-sectional view of one end of the electrical connection connected to one of the electrical devices, according to a third embodiment of the invention; Figure 6 is a cross-sectional view of one end of the electrical connection connected to one of the electrical devices.according to a fourth embodiment of the invention, and Figure 7 is a view similar to that of Figure 2, illustrating a variant of the invention. Detailed description of the invention

[0028] With reference to Figure 1, an example of aircraft 100 in which the invention is implemented will now be described.

[0029] Aircraft 100 includes first of all a fuselage 102 and a wing 104 projecting from the fuselage 102. Aircraft 100 also includes a nacelle 106 located under the wing 104.

[0030] Aircraft 100 further comprises a pylon 108 and a turbomachine 110 extending into the nacelle 106 and connected to the wing by the pylon 108. The turbomachine 110 is traversed by at least one airflow from upstream to downstream. Generally, the turbomachine 110 can be enclosed (turbojet) or not, as in the illustrated example (from the English "open rotor").

[0031] For example, the 110 turbomachine is a dual-flow turbomachine and features a propeller 112 upstream (a blower in the case shrouded) and, in a casing 113, a low pressure body 114 connected to the propeller 112 and a high pressure body 116. The bodies 114, 116 include in particular respective compressors.

[0032] Thus, the air passing through the propeller 112 is compressed by the latter and divided into a primary airflow F1 passing through a first channel in the crankcase 113 to pass through the low pressure body 114 and the high pressure body 116 and into a secondary airflow F2 in a second vein passing outside the housing 113.

[0033] The aircraft 100 further comprises first and second electrical devices, for example respectively a power electronics unit 118 and an electric machine 120 coupled to the low pressure body 114 of the turbomachine 110 and located in the nacelle 106.

[0034] Aircraft 100 also includes a harness 122 comprising several cables, for example, three cables to transmit three-phase voltage or two cables to transmit direct current voltage, connecting the first and second electrical devices 118, 120 to each other. As in the illustrated example, the harness 122 can pass through the pylon 108 to reach the wing 104.

[0035] At least one of the first and second electrical devices 118, 120 is designed to provide an electrical voltage of at least 200 V between two of the cables of the harness 122. For example, the electrical machine 120 can be designed to operate as an electric motor and receive the voltage supplied by the power electronics equipment 118. The electrical machine 120 can also be designed to operate as an electric generator and then supply the voltage to the power electronics equipment 118.

[0036] Referring to Figure 2, the aircraft 100 has a sheath 202 surrounding at least one of the cables of the harness 122, through which air circulates to cool the cable(s). In the illustrated example, the harness 122 contains three cables 204A, 204B, and 204C, which are surrounded by the sheath 202. Generally, each cable 204A-C includes a central 206A-C conductor which can be surrounded by conductive shielding and / or mechanical protection.

[0037] The duct 202 has an air inlet 210 and the aircraft further includes an airflow generation device 211 designed to provide an airflow entering the air inlet 210 of the duct 202 towards the electrical machine 120, and thus cool cables 204A-C over a section 212 extending from the air inlet 210 to the electrical machine 120.

[0038] For example, the airflow generation device may include the turbomachine 110. In this case, the air inlet 210 is connected to the second vein to receive part of the secondary airflow F2 to circulate the air in the duct 202 towards the electric machine 120.

[0039] With reference to figure 3, the electric machine 120 includes a casing 302 from which is projected a connector called machine connector 304.

[0040] The aircraft 100 further comprises an envelope 306 defining, with the housing 302, a cavity 308 in which the machine connector 304 is located.

[0041] This envelope 306 has at least one opening 309 in communication with the ambient air, so that the pressure within the cavity 308 is not controlled.

[0042] The harness 122 has, at one end, a connector called harness connector 310 connected to the complementary machine connector 304.

[0043] For example, the 310 harness connector has one plug per cable, and the 304 machine connector has a plug-receiving socket for each plug. Again, for example (as in the illustrated example), the 310 harness connector has one lug per cable, and the machine connector has a lug-receiving terminal block for each lug.

[0044] For example, as illustrated, the harness connector 310 has a so-called longitudinal part 312 extending along the housing 302, for example, as illustrated, at a distance from the latter, and a so-called transverse part 314 surrounding the machine connector 304 and extending to the housing 302.

[0045] The sheath 202 surrounds at least part of the harness connector 310. Thus, the sheath 202 surrounds the harness 122 to its end. For example, as illustrated, the sheath 202 continues until it overlaps the longitudinal portion 312 of the harness connector 310, for example over at least 10 mm, so as to present, around this longitudinal part 312, an air outlet 315 defining, with the longitudinal part 312, an opening 316.

[0046] The sheath 202 can be made in two parts: a first part 202A extending outside the cavity 308 and a second part 202B completing, inside the cavity 308, the first part 202A.

[0047] For example, the first part 202A includes a service arm through which the harness 122 passes. This service arm must be as thin as possible to minimize the impact on the performance of the aircraft 100. Indeed, the service arm crosses the secondary airflow F2 which contributes to the thrust of the turbomachine 110.

[0048] Ventilation from the air inlet 210 to the cavity 308 allows for maintaining a reasonable size of service arm, and, in general, of the sheath 202. Indeed, this ventilation of the harness 122 to the cavity 308 allows for reducing the size of the central conductor 206A-C of each cable 204A-C.

[0049] The portion of the harness 122 extending into the cavity 308 generally does not need to be ventilated as it is cooled by thermal conduction, due to the thermal conductivity of the central conductor 206A-C, in contact with the harness connector 310, and due to the thermal convection of the air in the cavity 308, which is colder than the areas previously traversed by the harness 122.

[0050] However, the second part 202B of the sheath is nevertheless provided to prevent partial discharges in this part of the harness 122, in the same way as in the part of the harness 122 extending into the first part 202A of the sheath 202.

[0051] The second part 202B of the sheath 202 thus forms a cover 202B using, for example, a rigid material such as a high-temperature resistant thermoplastic, like a material from the polyaryletherketone (PAEK) family (e.g., polyetheretherketone (PEEK) or polyetherketone (PEKK)), polyetherimide (PEI), polyimide (PI), polyamide-imide (PAI), or polyphenylene sulfide (PPS). An electromagnetic compatibility (EMC) protection function can be added to this cover 202B. In this case, the cover 202B can be made of a conductive material such as aluminum, titanium, stainless steel, etc., or of a metallized thermoplastic. To facilitate installation The 202B cover is preferably mounted after connecting the harness connector 310 to the machine connector 304. To further facilitate installation, the 202B cover is preferably made of several shells, for example, two half-shells, designed to fit together around the harness 122. A system for retaining the shells is then provided. For example, the retention system includes a clamp for the half-shells and / or, if the half-shells have eyelets, screws for tightening the eyelets of the half-shells. For short harness lengths in the cavity (for example, less than 100 mm), it is not necessary to secure the cable(s) in the 202B cover. For longer lengths (for example, greater than 100 mm), a system for retaining the cable(s) in the center of the 202B cover may be necessary.In this case, the cable(s) are for example held in the center of the cover 202B at holding points distributed over the length of the harness in the cavity 308 with a pitch which depends on the vibrations of the installation area, the rigidity of the harness 122 and the spacing of the harness relative to the cover 202.

[0052] In normal operation, the air pressure at the air inlet 210 is at least 500 mbar. More precisely, for a flight up to a usual altitude (43,000 feet), the surrounding air pressure is greater than or equal to 163 mbar and the propeller 112 compresses the air to at least 500 mbar at the air inlet 210, even in the most unfavorable case: flight altitude of 43,000 feet and turbomachine 110 in idle mode in flight.

[0053] Aircraft 100 further includes a pressure maintenance system designed to maintain an air pressure of at least 500 mbar in the duct 202 (i.e. in the first part 202A and in the cowling 202B) as long as the air pressure at the air inlet 210 of the duct 202 is at least 500 mbar.

[0054] For example, as illustrated in Figure 3, the pressure maintenance system is formed by the opening 316 by sizing the latter so that, when the turbomachine 110 is in an idle regime in flight, the air pressure in the duct 202 is at least 500 mbar.

[0055] Thus, the risk of partial discharges can be reduced. Indeed, according to Paschen's law, the voltage at which partial discharges occur decreases as the pressure decreases. By maintaining the pressure above the threshold of 500 mbar, the voltage at which partial discharges occur... maintained above the tension that can appear between two cables of harness 122. Thus, the electrical insulation of the cables can be reduced.

[0056] With reference to Figure 4, in another embodiment, the air outlet, now designated as 402, is located around the transverse part 314 and faces the housing 302. Thus, the air outlet 402 defines, with the transverse part 314, an opening 404. The pressure maintenance system is then formed by the opening 404 by sizing the latter so that, when the turbomachine 110 is in an idle regime in flight, the air pressure in the duct 202 is at least 500 mbar.

[0057] Referring to Figure 5, in another embodiment, the sheath 202 extends around the harness connector 310 to the housing 302 in such a way as to leave no opening between the sheath 202 and the housing 302. Thus, the pressure maintenance system includes, on the sheath 202, a pressure relief valve 502 designed to maintain the air pressure in the sheath 202 at a minimum of 500 mbar. More specifically, the pressure relief valve 502 is designed to be closed by default (no air discharge) and to open (air discharge) when the pressure reaches a predefined threshold above 500 mbar. The pressure relief valve 502 may, for example, be a silicone diaphragm pressure relief valve or a check valve pressure relief valve, for example, made of titanium or stainless steel.

[0058] Referring to Figure 6, in another embodiment, the duct 202 partially (as in Figure 3) or completely (as in Figure 4, the case illustrated in Figure 6) covers the harness connector 310 so that its air outlet 315, 402 defines an opening 316, 404 with the harness connector 310. However, no specific dimensions are required for this opening 316, 404 in this case, which simplifies the design. Indeed, the casing 306 is closed so that the cavity 308 is closed, and the pressure maintenance system includes, on the casing 306, a pressure relief valve 602 designed to maintain the air pressure in the cavity 308, and therefore also in the duct 202, at a minimum of 500 mbar. More specifically, the 602 pressure relief valve is designed to be closed by default (no air venting) and to open (air venting) when the pressure reaches a predefined threshold above 500 mbar.The 602 pressure relief valve includes, for example, a silicone diaphragm pressure relief valve, or a non-return check valve pressure relief valve, for example in titanium or stainless steel.

[0059] With reference to Figure 7, the airflow generation device 211 may include a fan 702, for example an electric fan, designed to blow air into the air inlet 210 of the duct 122.

[0060] The fan 702 can, for example, be designed to operate in place of the turbomachine 110. Thus, when the latter is stopped, for example when the aircraft 100 is on the ground, where the pressure is around 1,000 mbar (therefore there is no pressure problem, but an airflow problem if the turbomachine 110 is stopped), the airflow at the air inlet 210 of the duct 122 can be maintained in order to cool the cable(s) provided in the duct 122.

[0061] Furthermore, the fan 702 can operate in conjunction with the turbomachine 110. For example, if the aircraft 100 is flying between 43,000 and 70,000 feet, the ambient air pressure can drop to 44 mbar. In this case, the propeller 112 alone could not maintain a pressure of at least 500 mbar at the air inlet 210 of the duct 122. However, the combined action of the propeller 112 and the fan 702 makes it possible to maintain this pressure of at least 500 mbar.

[0062] In conclusion, it is clear that an aircraft such as the one described above makes it possible to reduce the volume of a harness, by dissipating heat and decreasing the risk of partial discharges.

[0063] It should also be noted that the invention is not limited to the embodiments described above. Indeed, it will be apparent to those skilled in the art that various modifications can be made to the embodiments described above, in light of the information just disclosed to them.

[0064] In the detailed presentation of the invention given above, the terms used shall not be interpreted as limiting the invention to the embodiments set forth in this description, but shall be interpreted to include all equivalents within the scope of the claims, the prediction of which is within the reach of a person skilled in the art by applying their general knowledge to the implementation of the teaching which has just been disclosed to them.

Claims

Demands [1] Aircraft (100) comprising: first and second electrical devices (118, 120); a harness (122) comprising several cables (204A-C) connecting the first and second electrical devices (118, 120) to each other and having, at one end, a connector (310) connected to a complementary connector (304) of the second electrical device (120); a sheath (202) surrounding at least one of the cables (204A-C) and through which air circulates to cool the cable(s) (204A-C), the sheath (202) having an air inlet (210); and an airflow generation device (211) entering the air inlet (210) of the sheath (202); characterized in that: at least one of the first and second electrical devices (118, 120) is designed to provide an electrical voltage of at least 200 V between two of the cables (204A-C) of the harness (122); the sheath (202) also surrounds at least a portion of the connector (310); and the aircraft (100) includes a pressure maintenance system designed to maintain an air pressure of at least 500 mbar in the duct (202) as long as there is a pressure of at least 500 mbar at the air inlet (210) of the duct (202). [2] Aircraft (100) according to claim 1, wherein the airflow generation device (211) comprises a turbomachine (110) designed to be traversed by an airflow (F2) from upstream to downstream, the air inlet (210) of the duct (202) being connected to the airflow (F2) so that a portion of the latter circulates in the duct (202). [3] Aircraft (100) according to claim 2, comprising a wing (104) and a pylon (108) supporting the turbomachine (110), in which the second electrical device (120) is fixed to the turbomachine (110) and in which the harness (122) passes through the pylon (108) to join the wing (104). [4] Aircraft (100) according to claim 2 or 3, wherein the turbomachine (110) is designed so that, when the turbomachine (110) is in idle mode in flight, the airflow (F2) at the air inlet (210) of the duct (202) has a pressure of at least 500 mbar, when the ambient air pressure is at least 163 mbar [5] Aircraft (100) according to any one of claims 1 to 4, wherein the airflow generation device (211) comprises a fan (702). [6] Aircraft (100) according to any one of claims 1 to 5, wherein the duct (202) has an air outlet (315; 402) defining, with the connector (310), an opening (316; 404) dimensioned so that, as long as there is a pressure of at least 500 mbar at the air inlet (210) of the duct (202), the air pressure in the duct (202) is at least 500 mbar. [7] Aircraft (100) according to claim 6, in which the second electrical device (120) comprises a housing (302) from which the complementary connector (304) is projected, in which the connector (310) has a so-called longitudinal part (312) extending along the housing (302), and in which the air outlet (315) is located around this longitudinal part (312). [8] Aircraft (100) according to claim 6, in which the second electrical device (120) comprises a housing (302) from which the complementary connector (304) is projected, in which the connector (310) has a so-called transverse part (314) surrounding the complementary connector (304) and extending to the housing (302), and in which the air outlet (402) is located around this transverse part (314) and faces the housing (302). [9] Aircraft (100) according to any one of claims 1 to 5, wherein the second electrical device (120) comprises a housing (302) from which the complementary connector (304) is projected, in which the sheath (202) extends around the connector (310) to the housing (302) so as not to leave an opening between the sheath (202) and the housing (302), and further comprising, on the sheath (202), a pressure relief valve (502) designed to maintain the air pressure in the sheath (202) at least 500 mbar. [10] Aircraft (100) according to any one of claims 1 to 5, wherein the second electrical device (120) comprises a housing (302) from which the additional connector (304), and further comprising a casing (306) around the housing (302) defining, with the housing (302), a cavity (308), in which the sheath (202) has an air outlet (315; 402) defining, with the connector (310), an opening (316; 404) leading into the cavity (308), and further comprising, on the casing (306), a pressure relief valve (602) designed to maintain an air pressure of at least 500 mbar in the cavity (308).

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