ATTACHMENT PART FOR AN AIRCRAFT PROPULSION UNIT

Abstract

The invention relates to a fastening part (10) for a propulsion unit (1), in particular an aircraft, the fastening part (10) comprising a metal body having an outer surface (12) covered at least partially by a protective coating (14), this protective coating (14) comprising an anti-corrosion coating (140), the protective coating (14) further comprises at least one shock-resistant coating (142, 144) made of a polymer and / or metal material, and which covers the anti-corrosion coating (140). Abstract figure: Figure 2

Description

Title of the invention: ATTACHMENT PART FOR AN AIRCRAFT PROPULSION ASSEMBLY Technical field of the invention

[0001] The field of the present invention is that of propulsion assemblies, for example for an aircraft, comprising a turbomachine and parts for attaching the turbomachine to a structure of the aircraft.

[0002] The present invention relates in particular to an attachment part for a propulsion unit. Technical background

[0003] A turbomachine (such as a turboshaft or a turbojet) of a propulsion system can be mounted at various locations on an aircraft by being attached to a mast belonging to a structure of the aircraft. The mast can be suspended under the wings of the aircraft, fixed to a fuselage of the aircraft or mounted in a tail of the aircraft by attachment parts. These attachment parts have the function of ensuring the transmission of mechanical forces between the engine and the structure of the aircraft. The loads to be taken into consideration are oriented in the three main directions. These are in particular the weight of the engine of the turbomachine, its thrust, and the lateral aerodynamic loads. The loads to be transmitted also include the recovery of the rotational torque around the axis of the engine.These parts must also absorb the deformations undergone by the turbomachine during the different phases of flight, in particular due to dimensional variations caused by thermal expansion or contraction.

[0004] One method of suspension, for example, in the case of a fan turbomachine, consists of hanging the turbomachine from a mast belonging to the structure of the wing of the aircraft by a front suspension or attachment and a rear suspension or attachment. The front suspension is fixed in particular to an external casing of the fan and the rear suspension to an exhaust casing of the primary flow.

[0005] Some of the attachment parts are essential for the proper functioning of the turbomachine and are therefore classified in the category of higher criticality. Thus, an attachment part with damage (such as impacts, cracks, wear, corrosion, etc.), can cause a loss of performance and operating power of the turbomachine or the turbomachine can stop working.

[0006] Furthermore, the attachment parts being outside the turbomachine, can be difficult for operators to access, which can make aircraft, handling, control and / or maintenance operations of the turbomachine complex. the operators.

[0007] It is known from the state of the art to produce fastening parts which are covered with a sacrificial type protective coating to control corrosion of the parts.

[0008] By sacrificial is meant a coating which is less noble than the material of the fastener which it protects in a corrosive environment in question. This coating corrodes and is therefore consumed over time in place of the fastener.

[0009] This type of prior art coating protects the part only against corrosion and for a limited time. Thus, the prior art coating does not protect the attachment part against possible impacts. Therefore, in the absence of additional control to detect deformations or damage to the attachment part, this part could still be used (without having been repaired or replaced), which will not guarantee reliable operation of the turbomachine.

[0010] In this context, it is necessary to propose a solution making it possible to overcome at least one of the drawbacks of the prior art, in particular by proposing an attachment part for a propulsion unit with reinforced corrosion resistance and mechanical strength, while preferably making it possible to easily control and identify deformation or stress on this part. Summary of the invention

[0011] The invention provides an attachment part for a propulsion unit, in particular an aircraft, the attachment part comprising a metal body having an outer surface covered at least partially by a protective coating, this protective coating comprising an anti-corrosion coating.

[0012] According to the invention, the protective coating further comprises at least one shock-resistant coating made of a polymer and / or metal material, and which covers the anti-corrosion coating.

[0013] The protective coating according to the invention makes it possible to protect the attachment part in operation against corrosion and impacts. For this, the protective coating comprises a superposition of shock-resistant coating on the anti-corrosion coating.

[0014] More particularly, the anti-corrosion coating directly covers at least a portion of the outer surface of the attachment part, to continue to protect the metal body from corrosion in the operating environment of the propulsion assembly. The anti-corrosion coating advantageously has a lower electrochemical potential than the metal body of the part, so that the anti-corrosion coating corrodes preferentially and protects the metal body of the part.

[0015] The shock-resistant coating covers the anti-corrosion coating to form an outermost layer of protection against shocks that may impact the attachment part in operation. This shock-resistant coating is in particular made of polymer and / or metal, and is advantageously more rigid and impact-resistant compared to the anti-corrosion coating.

[0016] The addition of the shock-absorbing coating is compact and requires little or no significant adaptation in the propulsion unit.

[0017] Advantageously, said at least one shock-resistant coating made from the polymer material may comprise a colorimetric marker configured to reveal a mark in the event of deformation or stress on the outer surface of the attachment part.

[0018] The protective coating according to this configuration of the invention also makes it possible to detect by a simple visual inspection the presence of a deformation or stress undergone by the attachment part. For this, the shock-resistant coating, in particular made of polymer, comprises a colorimetric marker.

[0019] The addition of the colorimetric marker makes it possible to guarantee by a simple visual indication that the attachment part has not suffered any shocks that could impact its proper functioning. The detection of one or more deformations or stresses is thus accelerated and made more precise. It is even possible for an operator to be able to become aware of the presence of the deformation or stress himself, such visual observation not requiring any specific skills. Unjustified returns to after-sales service are thus avoided, which represents a saving of time and a lower cost.

[0020] By deformation or stress, we mean a surface unevenness due to a removal of material, local and of variable size, on an external face of the shock-resistant coating of the attachment part.

[0021] The attachment part according to the invention may comprise one or more of the following characteristics, taken in isolation from one another or in combination with one another:

[0022] - the colorimetric marker changes color when a constraint or a de training greater than a predetermined threshold is applied to said outer surface;

[0023] - the colorimetric marker is in the form of nanocapsules containing a pigment, these nanocapsules being configured to break and release said pigment, or in the form of a piezochromic pigment which is configured to change color when subjected to a certain pressure stress;

[0024] - the anti-corrosion coating comprises at least one element chosen from cadmium, zinc, and aluminum, or an alloy chosen from zinc-nickel and zinc-iron;

[0025] — said shock-resistant coating comprises a first layer made of a material made of polymer or metal, and which covers the anti-corrosion coating;

[0026] — the first layer comprises the colorimetric marker when it is made in polymer;

[0027] - said shockproof coating comprises a first layer made of a material of metal which covers the anti-corrosion coating and a second layer made of a polymer material which covers the first layer, wherein the second layer comprises the colorimetric marker;

[0028] - the polymer material is polyurethane, polystyrene, epoxy or polyester;

[0029] - the polymer material is loaded with particles or fibers;

[0030] - the metal material is steel-based and / or nickel-based;

[0031] - said part is a yoke comprising at least one fixing lug;

[0032] — the first layer has a thickness of between 5qm and 2mm;

[0033] — the first layer is in the form of a layer of paint or in the form of a heat-shrinkable sheath;

[0034] — the thickness of the paint layer of the first layer is between 5qm and 500qm;

[0035] — the thickness of the heat-shrinkable sheath of the first layer is between 100qm and 2mm;

[0036] — the polymer material is loaded with particles of aluminum, zinc or oxide of titanium;

[0037] — the polymer material is loaded with fibers

[0038] — the metal body of the attachment part is made of steel.

[0039] The invention also relates to a propulsion assembly, in particular for an aircraft, comprising at least one turbomachine configured to be fixed to a structure of the aircraft, and at least one attachment part according to one of the particularities of the invention. This attachment part is carried by the turbomachine and intended to be fixed to the structure of the aircraft.

[0040] The turbomachine can be a turboshaft engine or a turbojet engine.

[0041] The invention also relates to a method for detecting at least one deformation or stress on an outer surface of a metal body in a fastener according to the invention. The method comprises the steps of: a step of observation of the external surface coated with the protective coating, and a step of visual detection of a deformation or a constraint on the external surface by identification of a mark of the colorimetric marker. Brief description of the figures

[0042] Other characteristics, aims and advantages of the present invention will appear on reading the detailed description which follows and with regard to the appended drawings given as non-limiting examples and in which:

[0043] [Fig.l] is a schematic exploded perspective view of a propulsion unit and part of an aircraft,

[0044] [Fig.2] is a schematic perspective view of an example of an attachment part according to a first embodiment of the invention for the propulsion assembly of [Fig.1],

[0045] [Fig.3a] is an enlarged view schematically showing in partial section a protective coating of an undeformed portion of the attachment part of [Fig.2],

[0046] [Fig.3b] is an enlarged view schematically showing in partial section a protective coating of a deformed portion of the attachment part of [Fig.2],

[0047] [Fig.4] is a schematic perspective view of an example of an attachment part according to a second embodiment of the invention for the propulsion assembly of [Fig.1],

[0048] [Fig.5a] is an enlarged view schematically showing in partial section a protective coating of an undeformed portion of the attachment part of [Fig.4],

[0049] [Fig.5b] is an enlarged view schematically showing in partial section a protective coating of a deformed portion of the attachment part of [Fig.4],

[0050] [Fig.6] is an enlarged view schematically showing in partial section a protective coating of an undeformed portion of the attachment part according to a third embodiment of the invention.

[0051] It should be borne in mind that the figures are given as examples and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate the understanding of the invention and are not necessarily on the scale of practical applications. In particular, the dimensions of the various elements illustrated are not representative of reality. Detailed description of the invention

[0052] By convention in the present application, the terms "inner" and "outer", and "internal" and "external" are defined radially relative to a longitudinal axis X of the turbomachine engine. Thus, a cylinder extending along the X axis has an inner face facing the X axis and an outer surface, opposite its inner surface.

[0053] [Fig.l] illustrates a propulsion assembly 1, in particular for an aircraft 3, comprising a turbomachine 2 configured to be fixed to a structure 30 of the aircraft 3 via one or more attachment parts 10. The turbomachine 2, in particular of an aircraft, may be a turbojet or a turboprop.

[0054] Generally, a turbomachine 2 extends along a longitudinal axis X and comprises several modules comprising, from upstream to downstream in the direction of gas flow, a fan 2a, one or more compressor stages (for example a low-pressure compressor and a high-pressure compressor), a combustion chamber, one or more turbine stages (for example, a high-pressure turbine and a low-pressure turbine), and a gas exhaust nozzle.

[0055] In [Fig.l], annular casings 2b, 2c may extend around the fan 2a and the engine of the turbomachine 2.

[0056] With reference to [Fig.l], the propulsion assembly 1 may also comprise a nacelle 4 which is configured to be fixed around the turbomachine 2.

[0057] Conventionally, the nacelle 4 also extends along a longitudinal axis which corresponds to the X axis of the turbomachine 2. The nacelle may comprise one or more covers fixed on at least one of the annular casings of the turbomachine. The nacelle is thus a fairing element making it possible to protect the turbomachine.

[0058] In [Fig.l], the nacelle 14 comprises, from upstream to downstream in the direction of gas flow, an annular air inlet structure 4a, a pair of cowls (or half cowls) 4b surrounding the fan 2a, a pair of thrust reverser cowls 4c in which the turbomachine engine is located, and a nozzle 4d.

[0059] As described above, one or more attachment parts 10 may be used to attach the turbomachine 2 to the structure 30 of the aircraft 3. By way of example and in a non-limiting manner, the attachment part 10 may be a yoke or any connecting part making it possible to attach the turbomachine. Generally, the part 10 has a metal body with an outer surface 12. The outer surface 12 is covered at least partially with a protective coating 14 which comprises an anti-corrosion coating 140.

[0060] The anti-corrosion coating 140 may be made of a material having an electrochemical potential (expressed by the unit of measurement volt V) lower than that of the metal body of the part 10. By way of example, the anti-corrosion coating 140 comprises at least one element chosen from cadmium, zinc, aluminum, zinc-nickel alloy and zinc-iron alloy.

[0061] One of the particularities of the invention is that the part 10 further comprises at least one shock-resistant coating 142, 144 arranged on the anti-corrosion coating 140. This makes it possible to reinforce the corrosion resistance and the mechanical strength of the part 10 in operation. The shock-resistant coating(s) 142, 144 may be made of polymer and / or metal.

[0062] For example, the part 10 (and therefore the outer surface 12) is made of steel.

[0063] Several embodiments of the part 10 of the invention are illustrated with reference in Figures 2 to 6.

[0064] A first embodiment of an attachment part 10 according to the invention for the propulsion assembly 3 is shown schematically in Figures 2, 3a and 3b.

[0065] In [Fig.2], the attachment piece 10 is a clevis which can be worn on the pe external rim of the casing 2c of the turbomachine 2. The yoke comprises two fixing ears 16 in the example shown. The ears 16 each comprise an orifice and the orifices of the ears are aligned to receive a hinge pin (not shown in the figures) carried by a pylon, a mast or another element of the structure 30 of the aircraft 3.

[0066] The part 10 comprises a body made of a metallic material, such as steel. The body comprises an outer surface 12 partially or entirely covered by a protective coating 14. Advantageously, the protective coating 14 is applied directly to one or more predetermined areas of the outer surface 12, in particular the areas exposed to an environment external to the part 10 and requiring protection against corrosion and shocks.

[0067] The protective coating 14 comprises an anti-corrosion coating 140 and at least one shock-resistant coating 142, 144.

[0068] In the example of figures 2, 3a and 3b, the shock-resistant coating comprises a first layer 142. In this configuration, the anti-corrosion coating 140 directly covers the outer surface 12, and the first layer 142 covers the anti-corrosion coating 140 and therefore forms the outermost layer of the part 10. This first layer 142 is therefore directly exposed to the external environment of the part 10.

[0069] The anti-corrosion coating 140 may be applied to the exterior surface 12 by a wet, liquid, or electrochemical surface treatment (such as electrolytic metal deposition). The anti-corrosion coating 140 may be applied by an aerosol spray in which the anti-corrosion coating 140 is in the form of a paint.

[0070] The first layer 142 of the first embodiment may be made of a polymer or metal material. For example, the first polymer layer 142 is made of polyurethane, polystyrene or polyester. For example, the first metal layer 142 is made of a steel-based and / or nickel-based material.

[0071] The first polymer layer 142 may be loaded with particles or fibers. This makes it possible to vary the hardness and resistance of the shock-resistant coating depending on the size of the protection desired for the attachment part.

[0072] For example, the polymer material (of the first layer 142 of the shock-resistant coating) is loaded with particles of aluminum, zinc or titanium oxide. This makes it possible to improve the corrosion resistance or the shock resistance. Indeed, the particles metal helps absorb shocks. The polymer loaded with particles also provides a base color (white for titanium oxide, for example).

[0073] The polymer material can be loaded with carbon or glass fibers. This makes it possible to reinforce the mechanical strength of the layer 142.

[0074] The impact-resistant coating 142 may be applied to the anti-corrosion coating 140 by an aerosol spray application in which the impact-resistant coating is in the form of a paint. Alternatively, the impact-resistant coating 142 may be in the form of a heat-shrinkable sleeve or a polymeric envelope that may be welded or assembled onto the anti-corrosion coating 140.

[0075] The first layer 142 may have a thickness E of between 5 μm and 2 mm. More particularly, the thickness E is between 5 μm and 500 μm when the first layer 142 is a layer of paint. The thickness E may be between 100 μm and 2 mm when the first layer 142 is a heat-shrinkable sheath.

[0076] The first layer 142 can further participate in the protection against corrosion of the part 10, by being made of an electrically non-conductive material, so that the anti-corrosion coating 140 is preferentially corroded first. For example, the non-conductive anti-shock material is preferentially made of a polymer, such that the aforementioned polymers are electrically non-conductive if they are not heavily loaded with conductive particles. Thus, these polymers make it possible to create an electrochemical barrier to limit corrosion of the attachment part.

[0077] [Fig.3a] illustrates a first portion of the protective coating 14 which has not undergone deformation. [Fig.3b] illustrates a second portion of the protective coating 14 which has undergone deformation D. This damaged second portion is still protected by the anti-corrosion coating 140.

[0078] Thus, the first layer 142 of the first embodiment makes it possible to protect the metal body of the attachment part against impacts during operation.

[0079] Another of the particularities of the invention is that the shock-resistant coating comprises a colorimetric marker 146 configured to cause a mark C2 to appear in the event of deformation or stress on the outer surface 12 of the attachment part 10. This makes it possible to easily detect the presence of deformation or stress on the outer surface 12.

[0080] Figures 4, 5a and 5b illustrate the attachment part 10 according to a second embodiment, in which the shock-resistant coating 142 comprises at least one layer made of polymer and comprising the colorimetric marker 146.

[0081] The part 10 of the second embodiment of [Fig.4] is different from the part 10 of the first embodiment of [Fig.2] by the shock-resistant coating of the coating 14.

[0082] In Figures 4, 5a and 5b, the anti-corrosion coating 140 is identical to the first embodiment. In this configuration, the anti-corrosion coating 140 also directly covers the outer surface 12, the first layer 142 covers the anti-corrosion coating 140, so as to form the outermost layer of the part 10.

[0083] The shock-resistant coating of [Fig.4] comprises a first layer 142 made of polymer (as described above with reference to the first embodiment) and comprising the marker 146 capable of making the mark C2 appear.

[0084] The C2 mark may be a color pigment that is visually observable by an operator. This C2 mark may be irreversible.

[0085] The colorimetric marker may be dispersed in the material of the shock-resistant coating made of polymer.

[0086] The marker 146 may be chosen to react according to a predetermined threshold of stress or strain, so that the marker 146 changes from a first color C1 to a second color or mark C2 when this threshold is reached. The predetermined threshold of stress or strain to be applied to cause the mark C2 to appear may be variable and calibrated according to the type of pigment of the marker 146.

[0087] For this, the marker 146 can be in the form of nanocapsules (“core-shell” in English) which therefore comprises a pigment. This pigment can be visible in the form of the first color CL. These nanocapsules are capable of breaking and releasing the pigment forming the mark C2 when a deformation or stress is applied to the shock-resistant coating.

[0088] Alternatively, the marker 146 may be in the form of a piezochromic pigment. This piezochromic pigment reacts to a certain specific pressure stress. Therefore, the piezochromic pigment is able to change color when a specific pressure is reached.

[0089] [Fig.5a] illustrates a first portion of the protective coating 14 which has not undergone deformation. In this first portion of the protective coating 14, the marker 146 (and consequently the intact first layer 142) can be visually observed by the first color CL

[0090] [Fig.5b] illustrates a second portion of the protective coating 14 which has undergone a deformation D. In this second portion, the mark C2 is visible on an area of ​​the first layer 142 corresponding to the deformation D.

[0091] Thus, the first layer 142 of the second embodiment makes it possible to ensure a dual function which is, on the one hand, to protect the metal body against impacts, and on the other hand, to detect a deformation or stress on the protective coating.

[0092] [Fig. 6] illustrates a third embodiment of the attachment part 10 according to the invention. The attachment part 10 of the third embodiment is distinguished from the attachment part 10 of the second embodiment by the shock-resistant coating 142, 144 of the protective coating 14.

[0093] More particularly, the dual function provided by the first layer of the second embodiment is separated and carried out by two separate shock-resistant coatings.

[0094] Indeed, the protective coating 14 of the third embodiment comprises two shock-resistant coatings, respectively, the first layer 142 and a second layer 144. The anti-corrosion coating 140 is identical to the first and second embodiments. In this configuration, the anti-corrosion coating 140 also directly covers the outer surface 12, the first layer 142 covers the anti-corrosion coating 140, and the second layer 144 covers the first layer of the shock-resistant coating so as to form the outermost layer of the part 10. It is therefore the second layer 144 which is directly exposed to the external environment of the part 10.

[0095] Furthermore, the first layer 142 is made of metal and the second layer 144 is made of polymer in the example of [Fig.6].

[0096] In addition, the colorimetric marker 146 of the second embodiment is present only in the second coating 144 which corresponds to the surface coating making it possible to detect deformation or stress. The first layer 142 does not include a marker 146 and only makes it possible to protect the outer surface 12 against impacts.

[0097] The second layer 144 can be made of polyurethane, polystyrene, epoxy or polyester.

[0098] A method for detecting at least one deformation D or stress on the outer surface 12 of the metal body in the attachment part 12 of the invention is described below.

[0099] Such a method comprises the steps of: a step of observing the outer surface 12 coated with the protective coating 14, and a step of visual detection of a deformation D or a stress on the outer surface 12 by a change in color of the colorimetric marker 16 of the shock-resistant coating 142, 144.

[0100] The invention is in no way limited to the embodiments described and illustrated which have been given only as examples.

Claims

Claims

1. Attachment part (10) for a propulsion unit (1), in particular an aircraft, the attachment part (10) comprising a metal body having an outer surface (12) covered at least partially by a protective coating (14), this protective coating (14) comprising an anti-corrosion coating (140), characterized in that the protective coating (14) further comprises at least one shock-resistant coating (142, 144) made of a polymer and / or metal material, and which covers the anti-corrosion coating (140), and in that said shock-resistant coating (142) comprises a first layer made of a polymer material, and which covers the anti-corrosion coating (140), wherein the first layer is in the form of a heat-shrinkable sheath.

2. Fastening part according to claim 1, characterized in that the thickness of the heat-shrinkable sheath of the first layer is between 1 00qm and 2mm.

3. Fastener according to claim 1 or 2, characterized in that said shock-resistant coating (142, 144) made of the polymer material comprises a colorimetric marker (146) configured to cause a mark (C2) to appear in the event of deformation or stress on the outer surface (12) of the fastener (10).

4. A fastener according to claim 3, the colorimetric marker (146) changes color when a stress or strain greater than a predetermined threshold is applied to said outer surface (12).

5. Fastener according to claim 4, characterized in that the colorimetric marker (146) is in the form of nanocapsules containing a pigment, these nanocapsules being configured to break and release said pigment, or in the form of a piezochromic pigment which is configured to change color when it is subjected to a certain pressure stress.

6. Fastener according to any one of claims 1 to 5, characterized in that the anti-corrosion coating (140) comprises at least one element chosen from cadmium, zinc, and aluminum, or an alloy chosen from zinc-nickel and zinc-iron.

7. A fastener according to any one of claims 1 to 6, ca- characterized in that the polymer material is polyurethane, polystyrene, epoxy or polyester.

8. Fastener according to any one of claims 1 to 7, characterized in that the polymer material is loaded with particles or fibers.

9. Attachment part according to any one of claims 1 to 8, characterized in that said part is a yoke comprising at least one fixing lug.

10. Propulsion assembly (1) for an aircraft (3), comprising at least one turbomachine (2) configured to be fixed to a structure (30) of the aircraft, and at least one attachment part (10) according to any one of the preceding claims, characterized in that the attachment part (10) is carried by the turbomachine (2) and intended to be fixed to the structure (30) of the aircraft.

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