AIRCRAFT WITH CABLE HARNESS

Abstract

The aircraft (100) comprises: - first and second electrical devices (120); - a harness (122) comprising several 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 through which air circulates to cool the cable or cables.In addition: - the sheath (202) has an air inlet; - the aircraft (100) includes a device for generating airflow into 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 any two of the harness cables (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 sheath (202) as long as there is a pressure of at least 500 mbar at the air inlet of the sheath (202). Figure for the abstract: Fig. 3.

Description

Title of the invention: 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 various states. In particular, an ambitious standard applies to both new types of aircraft and those currently 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 aeronautical components and products that are less energy-intensive, more environmentally friendly, and 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 new generations of aircraft engines, the weight reduction of aircraft, particularly through the materials used and lighter on-board equipment, the 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, greater than 230 V between phase and neutral for an alternating voltage and greater than 270 V between phases for a direct or pulse-width modulated voltage), the transient voltages and / or functional voltages may be sufficiently high (e.g., greater than 320 V) to allow the occurrence of partial discharges, in particular taking into account the constraints imposed in aeronautics: low pressure, high temperatures, significant temperature gradient, etc.

[0008] To solve 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 the connectors, metallization of certain parts of the components to reduce voltages across the vacuoles, etc.). All these modifications result in an increase in the volume of the harness, whereas only small spaces are generally available for its routing. The weight of the harness is also increased.

[0009] Furthermore, the use of high power means that, even when using high voltages, the current flowing 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 central conductors with a large cross-section.

[0010] However, partial discharges are a factor in the aging of the harness cables, even more significant 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 provide an aircraft which makes it possible to overcome at least some of the aforementioned problems and constraints. Summary of the invention

[0012] An aircraft comprising: is therefore proposed. - of the 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 duct has an air inlet; - the aircraft includes a device for generating airflow entering the air intake of the duct; - at least one of the first and second electrical devices is designed to provide an electrical voltage of at least 200 V between any two of the harness cables; - 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.

[0013] 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 makes it possible to reduce the volume of the harness.

[0014] The invention may further include one or more of the following optional features, according to any technically possible combination.

[0015] Optionally, the airflow generation device includes a turbomachine designed to be traversed by an upstream to downstream airflow, the duct's air inlet being connected to the airflow so that a portion of the latter circulates within the duct. The turbomachine is, for example, propulsive.

[0016] Optionally also, the aircraft 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.

[0017] Optionally also, the turbomachine is 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.

[0018] Optionally, the airflow generation device also includes a fan.

[0019] Optionally also, the duct has an air outlet defining, with the connector, 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.

[0020] Optionally also, the second electrical device includes a housing from which the complementary 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.

[0021] Optionally also, the second electrical device includes a housing from which the complementary connector is projected, the connector has a so-called transverse part surrounding the complementary connector and extending to the housing, and the air outlet is located around this transverse part and faces the housing.

[0022] Optionally also, the second electrical device includes a housing from which the complementary connector is projected, the sheath extends around the connector to the housing so as not to leave an opening between the sheath and the housing, and the aircraft further includes, on the sheath, a pressure relief valve designed to maintain the air pressure in the sheath at least 500 mbar.

[0023] Optionally also, the second electrical device 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.

[0024] Optionally also, the second electrical device includes an electric machine coupled to a low-pressure body of the turbomachine.

[0025] Optionally also, the first electrical device includes power electronics equipment. Brief description of the figures

[0026] 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 on the aircraft. and an electrical connection between them, - Figure 3 is a cross-sectional view of one end of the electrical connection linked 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 linked 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 linked to one of the electrical devices, according to a third embodiment of the invention. - [Fig. 6] is a cross-sectional view of one end of the electrical connection linked to one of the electrical devices, according to a fourth embodiment of the invention, and - [Fig.7] is a view similar to that of [Fig.2], illustrating a variant of the invention. Detailed description of the invention

[0027] With reference to [Fig.1], an example of aircraft 100 in which the invention is implemented will now be described.

[0028] The aircraft 100 first of all comprises a fuselage 102 and a wing 104 projecting from the fuselage 102. The aircraft 100 further comprises a nacelle 106 located under the wing 104.

[0029] The 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 upstream-downstream airflow. Generally, the turbomachine 110 may be enclosed (turbojet) or not, as in the illustrated example (from the English "open rotor").

[0030] For example, the turbomachine 110 is double-flow and includes an upstream propeller 112 (a blower in the shrouded case) 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 in particular include respective compressors.

[0031] Thus, the air passing through the propeller 112 is compressed by the latter and divided into a primary airflow Fl passing in a first vein in the casing 113 to cross the low pressure body 114 and the high pressure body 116 and into a secondary airflow F2 in a second vein passing outside the casing 113.

[0032] 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.

[0033] The aircraft 100 further comprises a harness 122 with several cables, for example three cables for transmitting a three-phase voltage or two cables for transmitting a 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.

[0034] 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 electric machine 120 can be designed to operate as an electric motor and receive the voltage supplied by the power electronics equipment 118. The electric machine 120 can further be designed to operate as an electric generator and then supply the voltage to the power electronics equipment 118.

[0035] With reference to [Fig. 2], the aircraft 100 has a sheath 202 surrounding at least one of the cables of the harness 122 and through which air circulates to cool the cable(s). In the illustrated example, the harness 122 groups three cables 204A, 204B, 204C which are surrounded by the sheath 202. Generally, each cable 204A-C has a central conductor 206A-C which may be surrounded by a conductive shield and / or mechanical protection.

[0036] 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.

[0037] 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.

[0038] With reference to [Fig.3], the electric machine 120 includes a housing 302 from which is projected a connector called machine connector 304.

[0039] The aircraft 100 further comprises an enclosure 306 defining, with the housing 302, a cavity 308 in which the machine connector 304 is located.

[0040] 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.

[0041] The harness 122 has, at one end, a connector called harness connector 310 connected to the complementary machine connector 304.

[0042] For example, the harness connector 310 has one plug per cable and the machine connector 304 has, for each plug, a socket for receiving the plug. Again, for example (as in the illustrated example), the harness connector 310 has one lug per cable and the machine connector has, for each lug, a terminal block for receiving the lug.

[0043] 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.

[0044] 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 by at least 10 mm, so as to present, around this longitudinal portion 312, an air outlet 315 defining, with the longitudinal portion 312, an opening 316.

[0045] 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.

[0046] 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 passes through the secondary airflow F2 which contributes to the thrust of the turbomachine 110.

[0047] The ventilation from the air inlet 210 to the cavity 308 makes it possible to maintain a reasonable size of the service arm, and, in general, of the sheath 202. Indeed, this ventilation of the harness 122 to the cavity 308 makes it possible to reduce the size of the central conductor 206A-C of each cable 204A-C.

[0048] The part of the harness 122 extending into the cavity 308 generally does not need to be ventilated because 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.

[0049] 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.

[0050] 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, such as a material from the polyaryletherketone (PAEK) family (for example, 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 the installation of the 202B cover, the 202B cover is preferably mounted after connecting the harness connector 310 to the machine connector 304.To further facilitate the installation of the 202B cover, it is preferably made of several shells, for example, two half-shells, designed to be assembled around the 122 harness. A system for securing the shells is then provided. For example, the securing 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 of... Securing 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 202B cover at retention points distributed along the length of the harness in the cavity 308 with a spacing that depends on the vibrations of the installation area, the rigidity of the harness 122 and the spacing of the harness relative to the 202 cover.

[0051] In normal operation, the air pressure at the air inlet 210 is at least 500 mbar. More specifically, for a flight up to a usual height (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 height at 43,000 feet and turbomachine 110 in idle mode in flight.

[0052] The aircraft 100 further comprises 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.

[0053] For example, as illustrated in [Fig.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.

[0054] 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 is kept above the voltage that can occur between two cables of the harness 122. Thus, the electrical insulation of the cables can be reduced.

[0055] With reference to [Fig.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 dimensioning 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.

[0056] With reference to [Fig. 5], in another embodiment, the sheath 202 extends around the harness connector 310 to the housing 302 so as not to leave any 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 evacuation) and to open (air evacuation) when the pressure reaches a predefined threshold. greater than 500 mbar. The 502 pressure relief valve includes, for example, a silicone diaphragm pressure relief valve, or a non-return valve pressure relief valve, for example made of titanium or stainless steel.

[0057] With reference to [Fig. 6], in another embodiment, the sheath 202 partially (as in [Fig. 3]) or completely (as in [Fig. 4], the case illustrated in [Fig. 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 sheath 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, for example, includes a silicone diaphragm pressure relief valve, or a non-return valve pressure relief valve, for example made of titanium or stainless steel.

[0058] With reference to [Fig.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.

[0059] The fan 702 can for example be provided 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 on the order of 1000 mbar (therefore there is no pressure problem, but an air flow problem if the turbomachine 110 is stopped), the air flow at the air inlet 210 of the duct 122 can be maintained in order to cool the cable or cables provided in the duct 122.

[0060] Furthermore, the fan 702 can operate in conjunction with the turbomachine 110. For example, if the aircraft 100 is flying between 43,000 feet and 70,000 feet, the surrounding air pressure may 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. In contrast, the combined action of the propeller 112 and the fan 702 makes it possible to maintain this pressure of at least 500 mbar.

[0061] 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 reducing the risk of partial discharges.

[0062] It should also be noted that the invention is not limited to the embodiments described above. It will indeed be apparent to those skilled in the art that various Modifications may be made to the embodiments described above, in light of the teaching which has just been disclosed to him.

[0063] 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 as including all equivalents which can be foreseen by 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); characterized in that: - the sheath (202) has an air inlet (210); - the aircraft (100) comprises an airflow generation device (211) entering the air inlet (210) of the sheath (202); - 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 part 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 sheath (202) as long as there is a pressure of at least 500 mbar at the air inlet (210) of the sheath (202).

2. Aircraft (100) according to claim 1, wherein the airflow generation device (211) comprises a turbomachine (110) designed to be traversed by an upstream to downstream airflow (F2), 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), wherein the second electrical device (120) is attached 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) includes 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, wherein the second electrical device (120) comprises a housing (302) from which the complementary connector (304) is projected, wherein the connector (310) has a so-called longitudinal part (312) extending along the housing (302), and wherein the air outlet (315) is located around this longitudinal part (312).

8. Aircraft (100) according to claim 6, wherein the second electrical device (120) comprises a housing (302) from which the complementary connector (304) is projected, wherein the connector (310) has a so-called transverse part (314) surrounding the complementary connector (304) and extending to the housing (302), and wherein 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 complementary connector (304) is projected, and further comprising an enclosure (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 enclosure (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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