Ice protection mat, in particular for aircraft components

Abstract

The invention relates to an anti-icing mat (1) for at least one component (BA), in particular for an aircraft component (BA), comprising at least one heating layer (3), in particular comprising at least one heating resistor, and at least one reinforcement layer (5) located between the heating layer (3) and the external environment, characterized in that the at least one reinforcement layer (5) is arranged between the heating layer (3) and the external environment. The reinforcing layer (5) has a thermal conductivity perpendicular to the total plane of extension of the reinforcements (5), which thermal conductivity is greater than 0.6 W / m.K at ambient temperature.

Description

Technical Field

[0001] The present invention relates to the anti-icing protection of aircraft components. More specifically, the present invention provides an anti-icing pad for protecting aircraft components from icing. Background Art

[0002] Especially during flight, the accumulation of ice on an aircraft can change the aerodynamic characteristics of the aircraft and impair its performance.

[0003] Furthermore, if ice blocks formed or accumulated on elements of the aircraft fuselage or on the engine air intakes break off, such ice blocks may strike parts of the aircraft and damage the aircraft.

[0004] Icing can cause at least partial blockage of the air intakes, which may also result in power loss and even engine shutdown.

[0005] This is why aircraft are usually equipped with anti-icing devices, also known as de-icers, which are installed, for example, on the leading edges of the wings, the rudder, the radome or the engine air intakes.

[0006] Furthermore, on propeller-driven aircraft, the leading edges of the blades or the cones are usually equipped with anti-icing devices.

[0007] Such anti-icing devices have the function of de-icing or preventing icing.

[0008] Combined anti-icing devices for de-icing and preventing icing are also known.

[0009] There are various techniques for anti-icing devices, such as pneumatic devices with mechanical action, hot air circulation de-icers, etc.

[0010] The present invention more particularly relates to an anti-icing device having an anti-icing pad, in particular a thermoelectric pad.

[0011] Such an anti-icing pad is a heating pad attached to the surface of the component to be anti-iced. Such an anti-icing pad de-ices or prevents icing by the Joule effect, by circulating an electric current in a layer comprising at least one heating resistor. Such an anti-icing pad can be controlled cyclically or according to an operating mode that ensures permanent heating.

[0012] Such a heating pad includes heating resistors encapsulated in a matrix of one or more elastomeric materials.

[0013] During takeoff, landing or flight, all components in contact with the external environment equipped with such a heating pad may be subject to impacts, especially from hail, stones, etc., which may cause damage to these components and seriously damage the heating pad.

[0014] The following anti-icing pad structure is known, wherein the elastomer encapsulating the heating resistor is reinforced with a polyamide fabric providing impact protection. However, polyamide is a poor thermal conductor.

[0015] A multi-layer pad structure including a heating resistor sandwiched between two Kapton films glued to each other is also known. However, Kapton has very poor thermal conductivity. SUMMARY OF THE INVENTION

[0016] An object of the present invention is to propose a solution that can protect the anti-icing pad of an aircraft component from impact without reducing the dissipation of the heat flux towards the surface to be de-iced.

[0017] Another object of the present invention is to propose a solution that can save space and reduce the thickness of such an anti-icing pad for protecting aircraft components from icing.

[0018] The present invention relates to an anti-icing pad structure, in particular for aircraft components, which has good temperature uniformity.

[0019] To this end, there is provided an anti-icing pad for at least one component, in particular for an aircraft component, the anti-icing pad including at least one heating layer and at least one reinforcing layer, the at least one heating layer particularly including at least one heating resistor, the at least one reinforcing layer being located between the heating layer and the external environment, characterized in that the reinforcing layer has a thermal conductivity perpendicular to the total extension plane of the reinforcement, which is greater than 0.6 W / m·K at ambient temperature.

[0020] According to advantageous but non-limiting features taken alone or in any combination:

[0021] - The reinforcing layer includes a network of woven, non-woven and / or reticulated fibers or threads, the woven, non-woven and / or reticulated fibers or threads having a longitudinal thermal conductivity greater than 0.6 W / m·K at ambient temperature;

[0022] - The fibers or threads of the reinforcing layer have a longitudinal thermal conductivity greater than 50 W / m·K at ambient temperature;

[0023] - The fibers or threads of the reinforcing layer have a longitudinal thermal conductivity greater than 120 W / m·K at ambient temperature;

[0024] - The reinforcing layer includes carbon threads or fibers;

[0025] - The carbon threads or fibers are pitch threads or pitch fibers, in particular coal pitch or petroleum pitch;

[0026] - The reinforcing layer includes threads or fibers having a polyacrylonitrile (PAN) type precursor;

[0027] - The reinforcing layer comprises wires or fibres selected from glass fibres, basalt fibres, silica fibres or metal wires;

[0028] - The mat comprises an intermediate layer made of an electrically insulating composite material, the composite material comprising:

[0029] - A matrix made of an elastomer or a polymer, and

[0030] - Inclusions,

[0031] Capable of ensuring that the material has a thermal conductivity greater than 0.6 W / m.K at ambient temperature, in particular greater than 1.5 W / m.K at ambient temperature. Thus, the composite material can achieve better heat dissipation while ensuring good electrical insulation;

[0032] - The volume resistivity of the electrically insulating composite material is greater than 1E9 Ω.m, preferably greater than 1E10 Ω.m;

[0033] - The inclusions are ceramics such as boron nitride, aluminium nitride and / or alumina;

[0034] - The matrix is selected from polyurethane, nitrile, neoprene, silicone, fluorosilicone and / or epoxide. The matrix can be made of a thermoplastic polymer, in particular polyetheretherketone "PEEK", polyetherketoneketone "PEKK", polyetherimide "PEI", polysulphone "PSU", polyethersulphone "PESU", polyphenylsulphone "PPSU", polyamide-imide "PAI" or polyphthalamide "PPA";

[0035] - The volume fraction of the inclusions is from 10% to 70%, in particular from 20% to 50%, in particular from 30% to 50%.

[0036] There is also provided an assembly comprising at least one component having an outer surface, in particular an aircraft component, characterised in that the outer surface is covered with the anti-icing mat as previously proposed.

[0037] Preferably, the contact layer of the anti-icing mat located between the component and the heating layer is glued or co-vulcanised to the component. Description of the Drawings

[0038] After reading the following description of the preferred embodiments, other features and advantages of the present invention will become apparent. The description will be given with reference to the accompanying drawings, which include:

[0039] - Figure 1 Schematically shows an assembly comprising a component and an anti-icing mat according to an embodiment of the present invention;

[0040] - Figure 2 Schematically shows the multi-layer structure of an anti-icing mat according to an embodiment of the present invention;

[0041] - Figure 3 Schematically shows a composite material of an electrically insulating and thermally conductive layer;

[0042] - Figure 4 Shows a measuring device for determining the electrical resistance of an anti-icing mat according to the present invention; and

[0043] - Figure 5 Shows a measuring device for determining the electrical resistance and leakage current of an anti-icing mat according to the present invention. Detailed Description of the Invention

[0044] In the description of the present invention to be given, the terms "lateral", "longitudinal" and "radial" define the direction of extension of the layer, fiber and / or wire.

[0045] Therefore, the lateral direction corresponds to the direction perpendicular to the extension surface of the layer. The lateral direction corresponds to the thickness of the layer. In addition, the lateral direction can be regarded as the radial direction of the fibers or wires of the elements constituting the layer. The lateral direction is represented by Figure 2 the axis T in.

[0046] In addition, the longitudinal direction corresponds to the direction of extension of the fibers and / or wires of the elements constituting the layer. The fibers and / or wires extend along the surface of the elements constituting the layer, and the longitudinal direction can be based on two components represented by Figure 2 the axis X and axis Y in.

[0047] Figure 1 Schematically shows an assembly including a component BA, particularly an aircraft component BA, particularly the leading edge of an aircraft wing or propeller, and the component BA is protected against icing by an anti-icing mat 1, particularly a thermoelectric mat 1.

[0048] The anti-icing mat 1 is attached to the outer surface 11 of the component BA to which the anti-icing mat is adapted, for example, by gluing using an adhesive layer not shown.

[0049] As Figure 2 schematically shown in, the anti-icing mat 1 includes a multi-layer structure.

[0050] In particular, the multi-layer structure includes a stack of layers, particularly according to Figure 2 the example shown, from the component BA to be protected against icing towards the external environment, the multi-layer structure includes the following stack of layers:

[0051] - A contact layer 2, the contact layer 2 is intended to be in contact with the component BA to be protected (particularly the leading edge), and has the function of forming an electrical barrier and a thermal barrier;

[0052] - A heating layer 3, the heating layer 3 is intended to be a heat source capable of providing a de-icing and / or anti-icing function for the component BA to be protected, particularly through the Joule effect;

[0053] - The intermediate layer 4, which is intended to provide electrical insulation and thermal conductor functions;

[0054] - The reinforcement layer 5, which is intended to provide impact protection for the anti-icing pad 1, especially for the heating layer 3;

[0055] - The outer layer 6, which is intended to provide resistance to the external environment (especially resistance to the harsh weather and temperature conditions that an aircraft may encounter).

[0056] The stacking of the different layers has a low thickness, usually less than 2 mm, especially less than 1.5 mm, and advantageously less than 1 mm.

[0057] If necessary, the multi-layer structure can be covered by a coating layer 7.

[0058] In particular, the anti-icing pad 1 including the multi-layer structure can have an electrical insulation resistance of at least 10 MΩ, especially at least 100 MΩ.

[0059] ]>According to Figure 2 the exemplary embodiment shown, the contact layer 2 is arranged in the multi-layer structure to be positioned between the outer surface 11 of the component BA to be protected against icing and the heating layer 3.

[0060] The contact layer 2 is designed to be in contact with the component BA to be protected (especially the leading edge), and the function of the contact layer 2 is to form an electrical barrier and a thermal barrier.

[0061] In particular, the contact layer 2 can be made of a material having electrical insulation and thermal insulation properties.

[0062] Therefore, the contact layer 2 makes it possible to avoid an excessive contact temperature with the component BA to be protected against icing.

[0063] The material of the contact layer 2 can be an elastomer, a polymer, especially a thermoplastic polymer or a thermosetting polymer, especially epoxy resin.

[0064] Alternatively, the contact layer 2 can be made of insulating foam.

[0065] According to a specific embodiment, the contact layer 2 can also be made of an insulating honeycomb structure. Alternatively or additionally, the contact layer 2 can also be made of a mixture of a polymer or an elastomer filled with glass beads, especially hollow glass beads.

[0066] Once configured in this way, the contact layer 2 can prevent possible overheating of the component BA equipped with the anti-icing pad 1. In fact, due to the thermal insulation properties of the contact layer 2, the heat released by the heating layer 3 is directed towards the outer surface of the anti-icing pad 1 where ice may form. According to the multi-layer structure, the outer surface of the anti-icing pad 1 faces the contact layer 2 and thus faces the component BA to be protected against icing.

[0067] In addition, it is desirable to avoid any circulation of electric current between the heating layer 3 and the component BA.

[0068] In particular, the contact layer 2 may have a volume resistivity of at least 1E9 Ω·m, preferably greater than 1E10 Ω·m.

[0069] The thermal conductivity (also known as the transverse thermal conductivity) of the contact layer 2, which is considered perpendicular to the total extension plane of the contact layer 2, is less than 0.4 W / m·K at ambient temperature. Throughout this specification, ambient temperature refers to a temperature of approximately 20 °C.

[0070] The contact layer 2 may have a thickness of less than 1.5 mm, particularly less than 1 mm, and advantageously less than 0.7 mm. In addition, the contact layer 2 may have a thickness greater than 0.2 mm, particularly greater than 0.3 mm, and advantageously greater than 0.6 mm.

[0071] According to Figure 2 the exemplary embodiment shown, the heating layer 3 is arranged in the multi-layer structure to be positioned between the contact layer 2 and the intermediate layer 4.

[0072] The heating layer 3 is designed to provide a heat source capable of ensuring the de-icing and / or anti-icing function for the component BA to be protected through the Joule effect.

[0073] In particular, the heating layer 3 may be a resistive layer for Joule heating.

[0074] However, the heating layer 3 can be made of any heating device capable of generating a heat flux, particularly, for example but not limited to, metal tracks, heating wires, conductive inks, fabrics or non-woven fabrics using fibers, etc.

[0075] For example, the heating layer 3 may integrate a grid of metal tracks through which an electric current flows to generate a heat flux through the Joule effect.

[0076] The metal tracks can be very close to each other to cover the surface as uniformly as possible. However, as will be more specifically understood from the following description, the longitudinal heat conduction ensured by the fibers and / or wires of the reinforcement allows the spacing between the metal tracks to be greater than the currently possible spacing of metal tracks according to the prior art.

[0077] In particular, the metal tracks cover at least 50% of the surface of the heating layer 3, especially at least 70% of the surface of the heating layer 3.

[0078] The power supply electrical connection enables connection to a power supply to supply power to the metal tracks.

[0079] Typically, the heating layer 3 releases a heating power between 1 W / cm 2 and 5 W / cm 2 and especially between 2 W / cm 2 and 5 W / cm 2 , depending on whether the heating layer is operating in a cyclic mode or a continuous mode.

[0080] The heating layer 3 may have a thickness of less than 0.3 mm, especially less than 0.25 mm, and advantageously less than 0.15 mm. Additionally, the heating layer 3 may have a thickness greater than 0.015 mm, especially greater than 0.05 mm. Typically, the heating layer 3 may have a thickness of approximately 0.15 mm.

[0081] According to Figure 2 the exemplary embodiment shown, the intermediate layer 4 is arranged in the multi-layer structure to be positioned between the heating layer 3 and the reinforcing layer 5.

[0082] The intermediate layer 4 is designed to provide electrical insulation and thermal conductor functions.

[0083] In particular, the intermediate layer 4 may be made of a composite material selected to have good electrical insulation and good heat conduction properties.

[0084] The intermediate layer 4 helps to direct the heat flux generated by the heating layer 3 to the outer surface of the anti-icing pad 1, that is, the intermediate layer 4 is opposite to the contact layer 2 and thus opposite to the component BA to be protected against icing.

[0085] In particular, the intermediate layer 4 may have a volume resistivity of at least 1E9 Ω·m, preferably greater than 1E10 Ω·m.

[0086] The thermal conductivity (also known as the transverse thermal conductivity) of the intermediate layer 4, determined according to the method described in standard ISO 8302 or ASTM C177 and considered perpendicular to the total extended plane of the intermediate layer 4, is greater than 0.4 W / m·K at ambient temperature, especially greater than 0.6 W / m·K at ambient temperature, especially greater than 0.8 W / m·K at ambient temperature, and especially greater than 1.5 W / m·K at ambient temperature.

[0087] The intermediate layer 4 may have a thickness of less than 1.5 mm, particularly less than 1 mm, and advantageously less than 0.7 mm. Additionally, the intermediate layer 4 may have a thickness greater than 0.2 mm, particularly greater than 0.3 mm. Generally, the intermediate layer 4 may have a thickness of approximately 0.4 mm.

[0088] As Figure 3 more specifically shown in

[0089] According to Figure 2 the exemplary embodiment shown, the reinforcing layer 5 is arranged in the multi-layer structure to be positioned between the heating layer 3 and the outer layer 6.

[0090] The reinforcing layer 5 is designed to provide the function of protecting the anti-icing pad 1, particularly the heating layer 3, from impacts (such as gravel, hail, maintenance-related impacts, etc.).

[0091] In particular, the reinforcing layer 5 may be made of a material that enables the heat flux generated by the heating layer 3 to flow towards the outer surface of the anti-icing pad 1, that is, the reinforcing layer 5 is opposite to the contact layer 2 and thus opposite to the component BA to be protected against icing.

[0092] In particular, the reinforcing layer 5 may be presented, for example, in the form of a fabric, non-woven fabric (such as felt), or mesh reinforcement that extends along the total extension plane of the reinforcing layer 5.

[0093] The thermal conductivity (also known as the transverse thermal conductivity) of the reinforcing layer 5, which is considered perpendicular to the total extension plane of the reinforcing layer 5 and determined according to the method described in standard ISO 8302 or ASTM C177, is greater than 0.4 W / m.K at ambient temperature, particularly greater than 0.6 W / m.K at ambient temperature, particularly greater than 0.8 W / m.K at ambient temperature, particularly greater than 1.5 W / m.K at ambient temperature.

[0094] More specifically, the reinforcing layer 5 may include fibers and / or threads. In such a configuration, the fibers and / or threads of the reinforcing layer may further have a longitudinal thermal conductivity greater than 0.6 W / m.K at ambient temperature.

[0095] The longitudinal thermal conductivity is the thermal conductivity considered in the direction parallel to the extension direction of the fibers and / or threads. Thus, the longitudinal thermal conductivity of the fibers and / or threads corresponds to the thermal conductivity along the total extension plane of the reinforcing layer 5.

[0096] A longitudinal thermal conductivity greater than 10 W / m.K at ambient temperature enables the temperature of the reinforcing layer 5 to be longitudinally homogenized, that is, enables the temperature of the reinforcing layer 5 to be homogenized in the total extension plane of the reinforcing layer 5.

[0097] Alternatively, in order to ensure uniformity, the longitudinal thermal conductivity, particularly along the fiber axis, can be greater than 50 W / m K.

[0098] Advantageously, the radial conductivity of the fibers corresponds to the transverse conductivity of the anti-icing pad 1. Thus, the radial conductivity of the fibers must logically be equivalent to the radial conductivity of the intermediate layer 4 and the outer layer 6 described below.

[0099] This thermal conductivity is particularly important when the heating layer 3 consists of a network of metal tracks with a non-uniform heating surface. In fact, in this case, the heat flux emitted by the metal tracks of the heating layer 3 is longitudinally non-uniform.

[0100] The homogenization of the heat flux in the total extension plane of the reinforcing layer 5 enables a higher de-icing or anti-icing efficiency to be achieved, since the heat flux generated by the heating layer 3 to ensure the de-icing and / or anti-icing function is diffused over the entire surface of the anti-icing pad 1 without non-uniformity.

[0101] It should also be noted that the homogenization function provided by the reinforcing layer 5 (particularly in the form of a fabric, non-woven fabric, knitted fabric, mesh and / or unidirectional reinforcement, and combinations and / or stacks thereof) enables the restrictions on the spacing of the tracks of the heating layer 3 to be relaxed. Thus, compared to the heating metal tracks currently possible in known solutions of the prior art, heating metal tracks that are further spaced apart from each other can be used.

[0102] Therefore, the present invention provides the possibility of using techniques for manufacturing the heating layer 3, particularly heating resistors, especially by additive manufacturing.

[0103] Preferably, the reinforcing layer 5 comprises a grid of woven, non-woven, knitted, meshed fibers and / or threads, and / or unidirectional reinforcements (particularly carbon fibers made from pitch fiber precursors, particularly coal or petroleum pitch), and / or threads having a longitudinal thermal conductivity greater than 50 W / m.K at ambient temperature.

[0104] More preferably, the woven or meshed reinforcement of the reinforcing layer 5 comprises fibers having a longitudinal thermal conductivity greater than 120 W / m.K at ambient temperature.

[0105] The fibers and / or threads of the reinforcing layer 5 can be of different types, such as glass fibers, basalt fibers, silica fibers, metal wires, etc.

[0106] Preferably, the reinforcing layer 5 (particularly in the form of a woven, non-woven or meshed reinforcement) is made of carbon fibers, which have the advantage of good thermal conductivity.

[0107] More preferably, the carbon fibers of the reinforcing layer 5 are made from coal or petroleum pitch. This production of carbon fibers enables a radial thermal conductivity greater than 0.6 W / m.K, particularly greater than 10 W / m.K, and / or enables a longitudinal thermal conductivity greater than 50 W / mK, particularly greater than 120 W / m.K.

[0108] According to another embodiment, the fibers of the reinforcing layer 5 include carbon fibers having a polyacrylonitrile (PAN) type precursor. Such an embodiment has a radial thermal conductivity greater than 1 W / m.K and a longitudinal thermal conductivity greater than 10 W / m.K.

[0109] It will also be noted that the reinforcing layer 5 can also participate in a protection function, in a protection function against electrostatic discharge, which is also denoted by the acronym "ESD".

[0110] For example, in the case where the reinforcing layer 5 is made of a carbon fabric and / or contains a metal, the reinforcing layer 5 can be used for grounding aimed at ensuring the discharge of electrostatic charges.

[0111] In this hypothesis, the reinforcing layer 5 can at least partly contribute to lightning protection.

[0112] The reinforcing layer 5 can have a thickness less than 1.5 mm, particularly less than 1 mm, particularly less than 0.7 mm, advantageously less than 0.3 mm. In addition, the reinforcing layer 5 can have a thickness greater than 0.02 mm, particularly greater than 0.05 mm. Generally, the reinforcing layer 5 can have a thickness of about 0.1 mm.

[0113] According to Figure 2 the exemplary embodiment shown, the outer layer 6 is arranged in the multi-layer structure to be positioned between the reinforcing layer 5 and the coating layer 7.

[0114] Alternatively, the outer layer 6 is arranged in the multi-layer structure such that the outer layer 6 is disposed on the reinforcing layer 5 and is in direct contact with the external environment.

[0115] The outer layer 6 is designed to provide a function of resistance to the external environment (particularly resistance to the adverse weather, temperature conditions and fluid jets that an aircraft may encounter).

[0116] In particular, the outer layer 6 can be made of an elastomer or polymer that resists the external environment (particularly resistance to the adverse weather and temperature conditions that an aircraft may encounter).

[0117] In particular, the outer layer 6 resists erosion under the conditions defined by the standard sand and dust RTCA-DO-160.

[0118] In addition, the outer layer 6 contributes to impact protection.

[0119] In addition, the outer layer 6 can also be a composition including a filler that enables the outer layer to dissipate electrostatic charges.

[0120] In addition, the outer layer 6 is thermally conductive and does not necessarily have electrical insulation properties.

[0121] The outer layer 6 may have a thickness of less than 1.5 mm, particularly less than 1 mm, and advantageously less than 0.5 mm. In addition, the outer layer 6 may have a thickness greater than 0.1 mm, particularly greater than 0.2 mm. Generally, the outer layer 6 may have a thickness of about 0.2 mm.

[0122] According to Figure 2 the exemplary embodiment shown, the coating layer 7 may be applied to the multi-layer structure to cover the multi-layer structure.

[0123] In particular, the coating layer 7 is designed to have properties resistant to the external environment and / or erosion, particularly under the conditions of the standard sand and dust RTCA - DO - 160.

[0124] In addition, the coating layer 7 may also be a composition including fillers enabling the coating layer to dissipate static electric charges.

[0125] In addition, coating the coating layer 7 on the multi-layer structure may require pre-coating an adhesion primer on the multi-layer structure, particularly on the reinforcing layer 5, or performing an adhesion treatment by a dry method (such as by plasma).

[0126] After being arranged in this way and according to the present invention, the anti-icing pad 1 has a total thickness of less than 1.9 mm, particularly less than 1.5 mm, and particularly less than 1 mm.

[0127] As previously mentioned, the intermediate layer 4 may be made of a composite material 40 including a matrix 42 and inclusions 41.

[0128] The matrix 42 is made of an electrically insulating elastomer. Such an elastomer is selected to have good tolerance within the typical operating temperature range of the anti-icing pad 1.

[0129] The maximum operating temperature of the anti-icing pad 1 is the temperature that the heating layer 3 can reach during the heat flux required to generate the de-icing cycle.

[0130] Since the intermediate layer 4 is in direct contact with the heating layer 3, one surface of the intermediate layer 4 in contact with the heating layer 3 must withstand the maximum operating temperature.

[0131] Since the heating layer 3 is covered by the intermediate layer 4, there is also an effect of heat flux accumulation at the interface between the heating layer 3 and the intermediate layer 4. The maximum temperature can generally be between 100 °C and 110 °C.

[0132] Preferably, the matrix 42 is made of a thermosetting polymer, particularly an elastomeric material or an epoxy resin.

[0133] However, the matrix 42 can be made of another type of polymer, for example, made of a thermoplastic polymer.

[0134] In order to obtain good resistance within the operating temperature range between the lowest temperature and the highest temperature and to ensure appropriate mechanical properties, it is particularly advantageous that the matrix 42 is made of a polymer selected from polyurethane, nitrile, neoprene, silicone, fluorinated silicone, and / or epoxide.

[0135] In particular, the matrix 42 can be made of a thermoplastic polymer, such as polyetheretherketone (also denoted by the acronym PEEK), polyetherketoneketone (also denoted by the acronym PEKK), polyetherimide (also denoted by the acronym PEI), polysulfone (also denoted by the acronym PSU), polyethersulfone (also denoted by the acronym PESU), polyphenylsulfone (also denoted by the acronym PPSU), polyamide-imide (also denoted by the acronym PAI), or polyphthalamide (also denoted by the acronym PPA).

[0136] This material particularly has the following advantages: it can withstand the contact temperature with the heating layer 3, can continuously generate a heat flux of about 100 °C, and is particularly beneficial for ensuring the de-icing and / or anti-icing functions.

[0137] Advantageously, the material of the matrix 42 is suitable for being formed by a vulcanization method after incorporating the inclusions 41. This method can fix the position of the inclusions 41.

[0138] Another advantage of this vulcanization forming is that it can be co-vulcanized with another material of an adjacent layer (such as the heating layer 3 that needs to be in close contact).

[0139] In an embodiment where the heating layer 3 is made of a metal track or a heating wire, the metal track or the heating wire is advantageously coated with a primer that can ensure connection with the matrix 42.

[0140] In addition, it is entirely possible that there are different connection methods between different layers of the multi-layer structure of the anti-icing pad 1, such as adhesion, co-vulcanization, or more generally co-firing.

[0141] The matrix 42 includes inclusions 41. In particular, the inclusions 41 are made of a material having a high volume resistivity (particularly greater than 1E9 Ω·m, preferably greater than 1E10 Ω·m).

[0142] This resistivity of the inclusions 41 enables a material to be obtained whose total resistivity corresponds to the electrical insulation requirements of the intermediate layer 4, and the intermediate layer 4 is arranged to be in direct contact with the heating layer 3.

[0143] In addition, the inclusions 41 have a thermal conductivity greater than 1.5 W / m·K at ambient temperature, particularly higher than 20 W / m K.

[0144] This thermal conductivity of the inclusion 41 enables the thermal conductivity of the intermediate layer 4 to be increased. Thus, this configuration enables the heat flux generated by the heating layer 3 to be better transmitted towards the surface to be de-iced.

[0145] By increasing the transmission of the heat flux, the energy savings necessary to ensure the de-icing and / or anti-icing function of the component BA to be protected can be achieved.

[0146] Furthermore, the good thermal conductivity of the intermediate layer 4 enables the cumulative effect of the heat flux at the heating layer 3 to be reduced. Thereby, it is possible to reduce the temperature experienced by the intermediate layer 4 in the vicinity of the contact area with the heating layer 3. This temperature reduction in this contact area to some extent prevents the deterioration of the material of the substrate 42.

[0147] Therefore, the increased thermal conductivity enables the service life of the heating layer 3 to be increased and / or other materials with less high-temperature resistance for manufacturing the substrate 42 to be used, provided that the surface temperature of the component BA to be protected remains within a reasonable range.

[0148] Advantageously, the material of the inclusion 41 is a ceramic with good thermal conductivity and electrical insulation.

[0149] Preferably, the inclusion 41 is made of boron nitride, aluminum nitride, aluminum oxide or a composition of these fillers.

[0150] Other ceramics with different resistivity and thermal conductivity parameters can be used.

[0151] According to a particular embodiment, the volume fraction of the inclusion 41 in the substrate 42 is generally from 10% to 70%, in particular from 20% to 50%, in particular from 30% to 50%.

[0152] Such a volume fraction enables the mechanical properties of the substrate 42 to be maintained for the shaping and use of the intermediate layer 4, while enabling the thermal properties of the inclusion 41 to be utilized to increase the overall thermal conductivity of the material.

[0153] An example of the manufacture of the composite material that can form the intermediate layer 4 will now be described.

[0154] The first step consists of providing a substrate for the formulation of the matrix polymer 42. Such a substrate is generally provided in the form of plates, flakes or granules and does not include any solvent. For example, the starting material can be rubber.

[0155] In a second step, the substrate is mixed, for example, in an enclosed mixer with a plurality of propellers or a cylindrical mixer (also known as an open mixer).

[0156] The elements of the substrate are heated by the shear effect that occurs during mixing.

[0157] During the second step, the substrate is transformed into a homogeneous viscous material.

[0158] In the third step, particles intended to form the inclusions 41 are added. Such particles are provided in powder form and may agglomerate during the production or storage of such particles.

[0159] The particles are added during the third step consisting of a mixing step. The third step makes it possible to separate any agglomerates and to distribute the particles homogeneously in the viscous material intended to form the matrix 42 (especially made of a polymer).

[0160] During the fourth step, when the inclusions 41 are distributed in the matrix 42, an intermediate layer 4 is formed, the thickness of which can be between 0.2 mm and 0.7 mm. Generally, the thickness of the intermediate layer 4 is about 0.4 mm.

[0161] The formation of the intermediate layer 4 can be carried out by calendering, extrusion, especially by extruding a film in a flat die...

[0162] Subsequently, during the fifth step, the matrix 42 is shaped using a dedicated tool and then vulcanized to hold the inclusions 41 in place and to fix the geometry of the intermediate layer 4.

[0163] In some embodiments, an intermediate layer 4 in direct contact with the heating layer 3 can be formed. In this case, co-vulcanization is carried out between the polymer matrix 42 and the heating layer 3. This co-vulcanization makes it possible to ensure good mechanical and thermal contact between the intermediate layer 4 and the heating layer 3.

[0164] To test the intermediate layer 4 and more generally the structure of the anti-icing mat 1, a test device 400 as Figure 4 shown is used.

[0165] Advantageously, the anti-icing mat 1 comprising the contact layer 2, the heating layer 3, the intermediate layer 4, the reinforcement layer 5 and the outer layer 6 is tested.

[0166] The test device 400 comprises an electrically conductive reservoir 401 filled with a certain amount of water 402, usually a metal reservoir.

[0167] A stack comprising at least the contact layer 2, an electrically insulating intermediate layer 4 especially made of a composite material 40, and the heating layer 3 is immersed in a certain amount of water 402.

[0168] Alternatively, the anti-icing mat 1 comprising the contact layer 2, the heating layer 3, the intermediate layer 4, the reinforcement layer 5 and the outer layer 6 is immersed in a certain amount of water 402.

[0169] Thus, the two electrodes 411, 412 are connected to the heating layer 3 via a power line and establish an electrical connection 413 with a resistance measuring device 410 (such as an ohmmeter). The resistance measuring device 410 is electrically connected to the tank 401.

[0170] A voltage is applied between the reservoir 401 and the electrodes 411, 412 connected to the heating layer 3, in particular a DC voltage of 500 V.

[0171] Preferably, the voltage applied during the test is twice the operating voltage of the de-icing and / or anti-icing device for the component BA to be protected against icing, and the operating voltage can be 220 V to 230 V.

[0172] Alternatively, the operating voltage of the de-icing and / or anti-icing device for the component BA to be protected against icing can be supplied as 110 V.

[0173] Therefore, the first test step includes measuring the insulation resistance by the resistance measuring device 410.

[0174] If the following conditions are met, the result of the first test step is considered verified:

[0175] - The stack including the heating layer 3 is complete, i.e., no damage caused by arcing is seen between the surface of the contact layer 2 and the heating layer 3 and / or between the surface of the outer layer 6 and the heating layer 3; and

[0176] - The insulation resistance measured by the resistance measuring device 410 is greater than 10 MΩ, in particular greater than 100 MΩ.

[0177] The value of the measured insulation resistance can be adjusted according to the specifications of the intended application.

[0178] In addition, in order to confirm the reliability of the material, multiple repeated tests can be carried out continuously.

[0179] Subsequently, the second test step includes verifying the dielectric resistivity and the leakage current.

[0180] Figure 5 The test device 400 for the second test step is shown in. Figure 4 The elements common to the test devices are denoted by the same reference numerals and will not be described again.

[0181] The test device 400 includes a leakage current measuring device 420 electrically connected to the electrodes 411 and 412. The leakage current measuring device 420 is in the form of an ammeter, for example, and the electrodes 411 and 412 are connected to the intermediate layer 4.

[0182] In addition, the test device 400 includes a voltage source 430 electrically connected to the leakage current measuring device 420 and the reservoir 401. As an example, the voltage source 430 provides a voltage of at least 1500 V with an alternating current having a frequency between 50 Hz and 60 Hz.

[0183] In the second test step, a voltage is applied. To this end, the voltage is gradually increased up to 20 seconds within a range between 0 V and twice the operating voltage of the de-icing and / or anti-icing device plus 1000 V. The resulting voltage is then maintained for one minute.

[0184] If the following conditions are met, the result of the second test step is considered to be verified:

[0185] - The stack including the heating layer 3 and the intermediate layer 4 is intact, i.e., no damage caused by arcing is seen between the components of the test device 400 and / or between the heating layer 3 and the intermediate layer 4;

[0186] - The stack including the heating layer 3 is intact, i.e., no damage caused by arcing is seen between the surface of the contact layer 2 and the heating layer 3 and / or between the surface of the outer layer 6 and the heating layer 3; and

[0187] - The leakage current measured by the leakage current measuring device 420 is less than 200 mA, in particular less than 50 mA, in particular less than 30 mA.

[0188] The value of the leakage current measured by the leakage current measuring device 420 can be adjusted according to the specifications of the intended application.

[0189] The intermediate layer 4 can be integrated into any functional layer stack that requires electrical insulation and heat conduction.

[0190] In Figure 1 the case of the thermoelectric anti-icing pad 1, the intermediate layer 4 arranged on the heating layer 3 improves the de-icing performance and can reduce the heating temperature of the heating layer 3.

[0191] Reducing the temperature of the heating layer 3 is beneficial for integrating the anti-icing pad 1 on temperature-sensitive components, in particular composite components.

[0192] In addition, the matrix 41 is advantageously made of an elastomer, and thus can adapt the intermediate layer 4 and the anti-icing pad 1 to complex component shapes, in particular three-dimensional components, in particular non-unfolding three-dimensional components.

[0193] The shaping is carried out with an unvulcanized elastomer, and then the intermediate layer 4 is fixed by vulcanization. However, the elasticity of the intermediate layer 4 can be maintained after vulcanization.

[0194] For the materials just described, other applications besides the thermoelectric anti-icing pad 1 are of course possible, such as heat sinks.

[0195] According to the present invention, different techniques can be used to assemble the different layers of the anti-icing mat 1.

[0196] In one possible embodiment, the contact layer 2 forming the thermal barrier and the electrical barrier can be formed directly on the heating layer 3, in particular by spraying on the reinforcement layer 5.

[0197] Alternatively or additionally, the contact layer 2 comprises elastomeric sheets superimposed manually or by automatic covering. The material of the contact layer 2 can be an elastomer, a polymer, in particular a thermoplastic polymer or a thermosetting polymer, in particular an epoxy resin.

[0198] Similarly, the intermediate layer 4 provides electrical insulation and thermal conductor functions and has a greater thermal conductivity than the contact layer 2 to direct the dissipation of the heat flux towards the external environment.

[0199] The reinforcement layer 5 can then be assembled to the intermediate layer 4 and the outer layer 6, for example by gluing.

[0200] The outer layer 6 can be formed directly on the reinforcement layer 5, in particular by spraying on the reinforcement layer 5.

[0201] In another possible embodiment, the various layers of the multi-layer structure are superimposed on one another manually or by automatic covering and then assembled together by various assembly methods.

[0202] For the various bonding operations, the surfaces to be bonded can be prepared by any bonding treatment, in particular by dry method or by plasma.

[0203] The method for manufacturing the anti-icing mat 1 can include the following steps, used at least individually or in combination:

[0204] - The contact layer 2, the intermediate layer 4 and / or the outer layer 6 are calendered from an elastomeric mixture and are advantageously used in their original form during all steps of the manufacturing method;

[0205] - The heating layer 3 is preferably a heating resistor obtained by chemical cutting of a metal strip, and the heating resistance value of the anti-icing mat 1 is controlled in this step;

[0206] - The heating layer 3 is covered with at least one primer so as to bond with the elastomer during the vulcanization step, and the heating layer 3 can be composed of multiple components;

[0207] - Using a manufacturing tool, the geometry of which corresponds to the shape of the component BA to be protected against icing, and the manufacturing tool is optionally covered with a non-stick coating;

[0208] - The reinforcing layer 5 is a fabric reinforcement adhered by adding a major type of chemical product in an aqueous solution or containing a solvent, by a dry process, by powder deposition, by plasma, etc.;

[0209] - Depositing the outer layer 6 on the manufacturing tool, especially manually or automatically;

[0210] - Depositing the reinforcing layer 5 on the outer layer 6, and particularly optionally, pre-forming the reinforcing layer 5 into a fan shape to be able to fit the manufacturing tool;

[0211] - Depositing the intermediate layer 4 on the reinforcing layer 5;

[0212] - Depositing the heating layer 3 on the intermediate layer 4;

[0213] - Making an electrical connection, for example by welding;

[0214] - Depositing the contact layer 2 on the heating layer 3;

[0215] - Then manufacturing a vacuum bag on the thus formed multi-layer structure;

[0216] - Then subjecting the whole to vacuum vulcanization in an autoclave;

[0217] - At the end of vulcanization, performing a demolding step and various finishing operations, such as a trimming operation in particular;

[0218] - A coating layer 7 can be added on the outer layer 6;

[0219] - Subsequently, the anti-icing pad 1 thus formed can be assembled to the component BA to be protected, for example by a cold bonding method.

[0220] The anti-icing pad 1 thus manufactured can be added by gluing the contact layer 2 to the outer surface 11 of the component BA to be protected.

[0221] Other assembly techniques besides gluing are also possible, such as co-curing or co-vulcanization, especially when the component BA to be protected is made of a composite material.

[0222] Before depositing the glue on the component BA to be protected against icing and / or on the contact layer 2, a bonding primer can be added, aiming at enabling at least one of the surfaces of the component BA or the contact layer 2 arranged on top of each other to withstand surface preparation treatments, such as abrasion, primer deposition, or any other dry or plasma bonding treatment.

[0223] In the previous description, for the purpose of example, the component BA to be protected is the leading edge of an aircraft wing.

[0224] The anti-icing mat 1 according to the present invention can be attached to any other aircraft component that requires anti-icing protection, such as engine inlets, turbine fairings, aircraft or helicopter propeller blades, propeller engine cones, protective radomes, etc.

[0225] It should be noted that the proposed multi-layer structure for the anti-icing mat 1 is particularly flexible and conformable. This multi-layer structure is capable of adapting to the different three-dimensional shapes that can be considered for the component BA.

[0226] In the case of the de-icing type of operation mode, the heating layer 3 is advantageously supplied in a cyclic manner so as to be able to detach the ice that has formed on the outer surface of the anti-icing mat 1.

[0227] For example, in the case of the de-icing type of operation mode, electrical power is supplied to the heating layer 3 at regular intervals for a determined period of time.

[0228] Generally, in the case of the de-icing type of operation mode, the electrical power applied to the heating layer 3 is between 1 W / cm 2 and 3 W / cm 2 , particularly between 2 W / cm 2 and 3 W / cm 2 .

[0229] In the case of the anti-icing type of operation mode, the heating layer 3 is supplied continuously to permanently prevent any ice from forming on the component BA to be protected against icing.

[0230] Generally, in the case of the anti-icing operation mode, the electrical power applied to the heating layer 3 can reach 5 W / cm 2 .

[0231] In the detailed description of the present invention given above, the terms used should not be considered as limiting the present invention to the embodiments set forth in the description just elaborated, but should be interpreted as including all equivalents within the scope of prediction that a person skilled in the art can reach by applying their common general knowledge to the embodiments just disclosed to them.

Claims

1. An anti-icing mat (1) for at least one component (BA), in particular for an aircraft component (BA), said anti-icing mat comprising at least one heating layer (3) and at least one reinforcing layer (5), said at least one heating layer particularly comprising at least one heating resistor, said at least one reinforcing layer being located between the heating layer (3) and the external environment, characterized in that, The reinforcing layer (5) has a thermal conductivity perpendicular to the total extension plane of the reinforcement (5), and the thermal conductivity is greater than 0.6 W / m·K at ambient temperature.

2. The anti-icing mat (1) according to claim 1, wherein, The reinforcing layer (5) comprises a network of woven, non-woven and / or reticulated fibres or threads, and the woven, non-woven and / or reticulated fibres or threads have a longitudinal thermal conductivity greater than 0.6 W / m·K at ambient temperature.

3. The anti-icing mat (1) according to claim 2, wherein, The fibres or threads of the reinforcing layer (5) have a longitudinal thermal conductivity greater than 50 W / m·K at ambient temperature.

4. The anti-icing mat (1) according to claim 3, wherein, The fibres or threads of the reinforcing layer (5) have a longitudinal thermal conductivity greater than 120 W / m·K at ambient temperature.

5. The anti-icing mat (1) according to any one of claims 2 to 4, wherein, The reinforcing layer (5) comprises carbon threads or fibres.

6. The anti-icing mat (1) according to claim 5, wherein, The carbon threads or fibres are pitch threads or pitch fibres, especially coal pitch or petroleum pitch.

7. The anti-icing mat (1) according to any one of claims 2 to 5, wherein, The reinforcing layer (5) comprises threads or fibres having a polyacrylonitrile (PAN) type precursor.

8. The anti-icing mat (1) according to any one of claims 2 to 5, wherein, The reinforcing layer (5) comprises threads or fibres selected from glass fibres, basalt fibres, silica fibres or metal wires.

9. A component, the component comprising at least one part (BA), in particular an aircraft part (BA), having an outer surface (11), characterized in that, The outer surface (11) is covered by the ice protection mat (1) according to any one of the preceding claims.

10. The component according to claim 9, wherein, The contact layer (2) of the ice protection mat (1) located between the component (BA) and the heating layer (3) is glued or co-vulcanized to the component (BA).

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