FIXED INTERNAL STRUCTURE FOR AN AIRCRAFT GONDLE

Description

TECHNICAL FIELD

[0001] The present invention relates to a fixed internal structure for an aircraft nacelle, a nacelle comprising two such structures, and an aircraft comprising at least one such nacelle. PREVIOUS STATE OF THE ART

[0002] An aircraft engine nacelle is attached to the aircraft wing structure by an engine pylon, and the nacelle houses the aircraft engine. The nacelle typically consists of two fixed internal structures (also called IFS for "Internal Fix Structure" in Anglo-Saxon terminology) and two external structures (also called OS for "Outer Structure" in Anglo-Saxon terminology).

[0003] Each structure comprises a section roughly forming a half-cylinder. The two inner structures are positioned opposite each other to form a cylinder housing the engine, and the two outer structures are arranged around the fixed inner structures. A secondary channel is thus formed between the fixed inner structures and the outer structures.

[0004] A fixed internal structure typically consists of a top end panel, an intermediate panel, and a bottom end panel. The end panels are generally flat, and the intermediate panel is generally semi-cylindrical and positioned between the end panels. The end panels are fixed to the intermediate panel to form the fixed internal structure.

[0005] There Fig. 6 shows an example of a fixed internal structure 600 of the prior art at the level of an upper junction 601 between the upper end panel 602 and the intermediate panel 604. Each panel 602, 604 takes the form of a sandwich panel comprising successively a resistive skin 606a, a honeycomb structure 606b and a structural skin 606c.

[0006] The fixed internal structure 600 also includes, at the junction 601, at least one shoe 610, conventionally made of metal, which is fixed a posteriori on panels 602 and 604, for example using fasteners 612. Each shoe 610 also carries a pad 614.

[0007] At the upper junction 601, the two fixed internal structures 600 are positioned on either side of the reactor mast 608 and each skid 614 comes to rest against a surface of the reactor mast 608.

[0008] At a lower junction between the lower end panel and the intermediate panel 604, the two fixed internal structures 600 are positioned opposite each other and each pad 614 of one fixed internal structure 600 rests against a pad of the other fixed internal structure 600.

[0009] In addition, due to the curvature at the junctions 601, the fixed internal structure 600 includes a honeycomb structure 607 which has high flexibility properties to accommodate said curvature.

[0010] Even if such an arrangement is satisfactory from a functional point of view, it is necessary to find a new arrangement, for example to eliminate the flexible 607 honeycomb structure which is relatively expensive.

[0011] Document WO-A-2019 / 155015 discloses a prior art fixed internal structure, said fixed internal structure comprising an upper end panel, a lower end panel, an intermediate panel in the shape of a half-cylinder and disposed between the upper end panel and the lower end panel, an upper splice between the upper end panel and the intermediate panel, a lower splice between the intermediate panel and the lower end panel, wherein each splice has a fastening surface, and for each fastening surface, a pad fixed to said fastening surface, wherein each pad of the upper splice is intended to bear against a surface of the reactor mast, and wherein each pad of the lower splice is intended to bear against a pad of a lower splice of another fixed internal structure. DESCRIPTION OF THE INVENTION

[0012] An object of the present invention is to provide a fixed internal structure for an aircraft nacelle, for which the shoes are integrated directly into a splice fixed to the panels.

[0013] To this end, a fixed internal structure is proposed for an aircraft nacelle comprising a jet engine pylon, said fixed internal structure comprising: an upper end panel, a lower end panel, an intermediate panel in the shape of a half-cylinder and disposed between the upper end panel and the lower end panel, an upper splice between the upper end panel and the intermediate panel, a lower splice between the intermediate panel and the lower end panel, wherein each splice consists of a skin with an inner face and an outer face, wherein the inner face is fixed to the intermediate panel and the end panel in question, and wherein the skin has at least one indentation projecting from the outer face, wherein each indentation has a fastening surface, and for each fastening surface, a pad fixed to said fastening surface, wherein each pad of the upper splice is intended to bear against a surface of the reactor mast,and where each pad of the lower splice is intended to bear against a pad of a lower splice of another fixed internal structure.

[0014] With such an arrangement, it is no longer necessary to implement a honeycomb structure with high flexibility properties and a honeycomb structure with standard flexibility properties is sufficient.

[0015] According to a particular embodiment, each panel is a sandwich panel comprising successively a resistive skin, a honeycomb structure and a structural skin, fixed together, where the inner face of each splice is fixed to the structural skins of the intermediate panel and the end panel considered.

[0016] In a particular embodiment, each panel is a sandwich panel comprising successively a resistive skin, a honeycomb structure, a structural skin, fixed together, and a closing skin shaped to be fixed to the structural skin and the edge of said panel, wherein the inner face of each splice is fixed to the closing skins of the intermediate panel and the end panel under consideration. Advantageously, the fixed inner structure comprises a complementary skin fixed between the resistive skins of the intermediate panel and the end panel under consideration, and the closing skins of the intermediate panel and the end panel under consideration are common and thus form a single skin bonded to the complementary skin. Advantageously, the fixed inner structure comprises a complementary honeycomb structure fixed between the complementary skin and the closing skin(s).

[0017] Advantageously, the edge of the intermediate panel and the edge of a considered end panel are at a distance from each other, the considered splint has stiffeners or ribs or embossing arranged against the inner face of the skin of said splint, and each stiffener or rib or embossing is positioned between the edge of the intermediate panel and the edge of said end panel.

[0018] Advantageously, each stiffener or splint or embossing includes a plate fixed to the skin of the splint.

[0019] Advantageously, each stiffener or coil or embossing has a wall attached to the plate and extending perpendicularly to the plate.

[0020] The invention also proposes a nacelle for an aircraft comprising a jet pylon, the nacelle comprising two fixed internal structures according to one of the preceding variants, where the two fixed internal structures are opposite each other, so that the intermediate panels form a cylinder, where each pad of the lower splice of one fixed internal structure is in contact with a pad of the lower splice of the other fixed internal structure.

[0021] The invention also proposes an aircraft comprising a reactor mast and at least one nacelle according to the previous variant where each skid of the upper splice of a fixed internal structure is supported against a surface of the reactor mast. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The features of the invention mentioned above, as well as others, will become clearer upon reading the following description of an exemplary embodiment, said description being made in relation to the accompanying drawings, among which: Fig. 1 is a side view of an aircraft according to the invention, Fig. 2 is a schematic perspective representation of a fixed internal structure according to the invention, Fig. 3 is a perspective and front view of a splint for the fixed internal structure according to the invention, Fig. 4 is a perspective and rear view of the splint of the Fig. 3 , Fig. 5 is a cross-sectional view of the fixed internal structure according to the invention at the level of plane V of the Fig. 2 , And Fig. 6 is a cross-sectional view of a fixed internal structure of the state of the art. DETAILED EXPLANATION OF IMPLEMENTATION METHODS

[0023] There Fig. 1 shows an aircraft 100 which has a fuselage 102 on either side of which is fixed a wing 104 under which is fixed at least one nacelle 106 by means of a reactor mast 108. Inside the nacelle 106 is housed an engine.

[0024] In the following description, and by convention, X is called the longitudinal axis of the nacelle 106, oriented positively in the direction of advance of the aircraft 100, Y is called the transverse axis which is horizontal when the aircraft 100 is on the ground, and Z is called the vertical axis or vertical height when the aircraft 100 is on the ground, these three directions X, Y and Z being orthogonal to each other.

[0025] In the description that follows, terms relating to a position are taken with reference to the direction of movement of aircraft 100 when the turbomachine is operating and represented by arrow F.

[0026] There Fig. 2 shows a fixed internal structure 200 according to the invention. As with the prior art, the nacelle 106 comprises two fixed internal structures 200 (also called IFS for "Internal Fix Structure" in Anglo-Saxon terminology) and two external structures 202 (also called OS for "Outer Structure" in Anglo-Saxon terminology).

[0027] Each structure 200, 202 comprises a part forming overall a half-cylinder, and the two fixed inner structures 200 are arranged opposite each other so that the two half-cylinders join together to form a cylinder in which the engine 204 is housed. The two outer structures 202 are arranged around the fixed inner structures 200 so as to form a secondary air channel 50 between the fixed inner structures 200 and the outer structures 202.

[0028] The fixed internal structure 200 consists of an upper end panel 200a, an intermediate panel 200c, and a lower end panel 200b. The end panels 200a-b are generally flat, and the intermediate panel 200c is generally semi-cylindrical. It is positioned and fixed between the end panels 200a-b to form the fixed internal structure 200. In position within the aircraft 100, the upper end panel 200a is positioned above the intermediate panel 200c, and the lower end panel 200b is positioned below the intermediate panel 200c. Thus, in the nacelle 106, the two fixed internal structures 200 are opposite each other, so that the intermediate panels 200c are opposite each other to form the cylinder in which the engine 204 is housed.

[0029] The fixed internal structure 200 has an upper junction 208a between the upper end panel 200a and the intermediate panel 200c and a lower junction 208b between the intermediate panel 200c and the lower end panel 200b. Fig. 5 shows the fixed internal structure 200 at the upper junction 208a, but the arrangement is similar at the lower junction 208b.

[0030] According to the invention, at the upper junction 208a, the fixed internal structure 200 comprises an upper splice 210a and at the lower junction 208b, the fixed internal structure 200 comprises a lower splice 210b. Each splice 210a-b ensures the junction and fixing between the intermediate panel 200c and the end panel 200a-b considered.

[0031] THE Figs. 3 et 4 show the upper splice 210a, but the principle is identical for the lower splice 210b. The splice 210a-b consists of a skin 312 having an inner face 312a and an outer face 312b where the inner face 312a is fixed to the intermediate panel 200c and to the end panel 200a-b considered.

[0032] The edge of the intermediate panel 200c and the edge of the end panel 200a-b considered are at a distance from each other, and the splice 210a-b thus fills the space between said edges and holds them together.

[0033] The skin 312 is thus shaped according to the form of the fixed internal structure 200 and has one or more recesses 314, where each recess 314 projects from the outer face 312b. Each recess 314 is therefore integral with the skin 312, forming a single component. Each recess 314 thus forms a raised area on the outer face 312b and a recess on the inner face 312a. The skin 312 is secured by any suitable means, such as the installation of fasteners 504 like blind bolts, bonding, etc.

[0034] Each recess 314 has a fixing surface 316 on which a pad 506 is fixed.

[0035] At the upper junction 208a and therefore of the upper splice 210a, the two fixed internal structures 200 are positioned on either side of the reactor mast 108 and each pad 506 of an upper splice 210a bears against a surface of the reactor mast 108. At the lower junction 208b, and therefore of the lower splice 210b, the two fixed internal structures 200 are positioned opposite each other, and each pad 506 of the lower splice 210b of one fixed internal structure 200 bears against a pad 506 of the lower splice 210b of the other fixed internal structure 200.

[0036] Thus, with this arrangement, there is no longer a need for a flexible honeycomb structure, resulting in cost savings. Integrating the recesses into the splice allows for a single component that can be easily installed, instead of the multiple components required by prior art.

[0037] Each 210a-b splice can be made from any suitable materials such as metal (aluminum alloys, steel), thermosetting composite or thermoplastic, and by any suitable processes such as stamping, pressing, molding, machining or others.

[0038] In the embodiment of the invention presented to the Fig. 5 , each 200a-c panel takes the form of a sandwich panel comprising successively a resistive skin 500a, a honeycomb structure 500b and a structural skin 500c which are fixed to each other.

[0039] The structural skin 500c and the honeycomb structure 500b ensure the rigidity of the panel 200a-c and ensure the transfer of forces that pass through the panel 200a-c.

[0040] The resistive skin 500a is perforated with holes that open into the honeycomb structure 500b to ensure the absorption of acoustic waves. The resistive skin 500a is positioned towards the secondary air stream 50, and the structural skin 500c is oriented towards the engine 204. The honeycomb structure 500b consists of open cells that extend between the resistive skin 500a and the structural skin 500c.

[0041] In an embodiment of the invention not shown, the inner face 312a of each splice 210a-b is fixed to the structural skins 500c of the intermediate panel 200c and the end panel 200a-b considered.

[0042] In the embodiment of the invention presented to the Fig. 5 Each panel 200a-c also includes a closing skin 502 which is shaped to be fixed to the structural skin 500c of said panel 200a-c and to the edge of said panel 200a-c to close the honeycomb structure 500b. In this embodiment of the invention, the inner face 312a of each splice 210a-b is fixed to the closing skins 502 of the intermediate panel 200c and the end panel 200a-b considered.

[0043] Furthermore, in the embodiment of the invention presented to the Fig. 5 An additional skin 501 is fixed between the resistive skins 500a of the intermediate panel 200c and the end panel 200a-b, forming the junction 208a-b under consideration. The closing skins 502 of the intermediate panel 200c and the end panel 200a-b under consideration are common and thus form a single skin which is abutted against the additional skin 501.

[0044] In the embodiment of the invention presented to the Fig. 5 , a complementary honeycomb structure 503 is fixed between the complementary skin 501 and the closing skin(s) 502.

[0045] To adjust the rigidity of the skin 312 of the splice 210a-b, stiffeners 318, also known as corrugations or embossing, are positioned against the inner face 312a. In the case of stiffeners 318, these are fixed to the inner face 312a. Each stiffener 318, or corrugation, is positioned in the space between the edge of the intermediate panel 200c and the edge of the end panel 200a-b. In the embodiment of the invention presented in the Fig. 5 , each stiffener 318 is thus arranged between the skin 312 of the splice 210a-b and the closing skin 502 between the intermediate panel 200c and the end panel 200a-b.

[0046] According to the process used to make the 210a-b splice, each stiffener 318 is added by overmolding, mechanical bonding, welding, etc.

[0047] Each stiffener 318 or coiling or embossing here includes a plate 318a fixed to the skin 312 of the splint 210a-b and which is here curved.

[0048] Depending on the constraints, each stiffener 318 or coil or embossing may also include a wall 318b attached to the plate 318a and extending perpendicularly to the plate 318a.

Claims

1. Internal fixed structure (200) for a nacelle (106) of an aircraft (100) comprising an engine pylon (108), said internal fixed structure (200) comprising: - an upper end panel (200a), - a lower end panel (200b), - an intermediate panel (200c) in the form of a half-cylinder and disposed between the upper end panel (200a) and the lower end panel (200b), - an upper splice plate (210a) between the upper end panel (200a) and the intermediate panel (200c), - a lower splice plate (210b) between the intermediate panel (200c) and the lower end panel (200b), wherein each splice plate (210a-b) is made up of a skin (312) with an inner face (312a) and an outer face (312b), wherein the inner face (312a) is fastened to the intermediate panel (200c) and to the end panel (200a-b) considered, and wherein the skin (312) comprises at least one indentation (314) protruding with respect to the outer face (312b), wherein each indentation (314) has a fastening surface (316), and - for each fastening surface (316), a pad (506) fastened to said fastening surface (316), wherein each pad (506) of the upper splice plate (210a) is intended to bear against a surface of the engine pylon (108), and wherein each pad (506) of the lower splice plate (210b) is intended to bear against a pad (506) of a lower splice plate (210b) of another internal fixed structure (200).

2. Internal fixed structure (200) according to Claim 1, characterized in that each panel (200a-c) is a sandwich panel successively comprising a resistive skin (500a), a honeycomb structure (500b) and a structural skin (500c), which are fastened to one another, wherein the inner face (312a) of each splice plate (210a-b) is fastened to the structural skins (500c) of the intermediate panel (200c) and of the end panel (200a-b) considered.

3. Internal fixed structure (200) according to Claim 1, characterized in that each panel (200a-c) is a sandwich panel successively comprising a resistive skin (500a), a honeycomb structure (500b), a structural skin (500c), which are fastened to one another, and a closure skin (502) shaped so as to be fastened to the structural skin (500c) and to the edge of said panel (200a-c), wherein the inner face (312a) of each splice plate (210a-b) is fastened to the closure skins (502) of the intermediate panel (200c) and of the end panel (200a-b) considered.

4. Internal fixed structure (200) according to Claim 3, characterized in that it comprises a complementary skin (501) fastened between the resistive skins (500a) of the intermediate panel (200c) and of the end panel (200a-b) considered, and in that the closure skins (502) of the intermediate panel (200c) and of the end panel (200a-b) considered are common and thus form a single skin placed against the complementary skin (501).

5. Internal fixed structure (200) according to Claim 4, characterized in that it comprises a complementary honeycomb structure (503) fastened between the complementary skin (501) and the closure skin / skins (502).

6. Internal fixed structure (200) according to one of Claims 1 to 5, characterized in that the edge of the intermediate panel (200c) and the edge of an end panel (200a-b) considered are at a distance from one another, in that the splice plate (210a-b) considered comprises stiffeners (318) or extruded elements or corrugations disposed against the inner face (312a) of the skin (312) of said splice plate (210a-b), and in that each stiffener (318) or extruded element or corrugation is positioned between the edge of the intermediate panel (200c) and the edge of said end panel (200a-b).

7. Internal fixed structure (200) according to Claim 6, characterized in that each stiffener (318) or extruded element or corrugation comprises a plate (318a) fastened to the skin (312) of the splice plate (210a-b).

8. Internal fixed structure (200) according to Claim 7, characterized in that each stiffener (318) or extruded element or corrugation comprises a wall (318b) that is rigidly connected to the plate (318a) and extends perpendicularly with respect to the plate (318a).

9. Nacelle (106) for an aircraft (100) comprising an engine pylon (108), the nacelle (106) comprising two internal fixed structures (200) according to one of Claims 1 to 8, wherein the two internal fixed structures (200) face one another, in such a way that the intermediate panels (200c) form a cylinder, wherein each pad (506) of the lower splice plate (210b) of one internal fixed structure (200) bears against a pad (506) of the lower splice plate (210b) of the other internal fixed structure (200).

10. Aircraft (100) comprising an engine pylon (108) and at least one nacelle (106) according to the preceding claim, wherein each pad (506) of the upper splice plate (210a) of an internal fixed structure (200) bears against a surface of the engine pylon (108).