Engine pylon rear secondary structure

Abstract

The present invention provides an engine pylon rear secondary structure for an aircraft, the aircraft comprising an engine pylon suspending an engine to a wing, the engine pylon rear secondary structure comprising: a front-side connection arranged to be connected to a main structure of the engine pylon; a rear connection part provided to be connected to the main structure of the wing; a composite beam connecting the front side connecting portion and the rear side connecting portion and attached thereto; the composite beam comprises a first part and a second part integrated with the first part; the second part comprises two branch parts; the first part is connected with the rear side connecting part, and the second part is connected with the front side connecting part; the frame includes an outer surface configured to support the fairing panel and attached to the first portion of the composite beam; and a cowl panel attached to an outer surface of the frame. The composite beam has a U-shaped cross-section, and the frame includes three brackets arranged to be attached to the composite beam on three outer surfaces of the U-shaped cross-section.

Description

[0001] This application claims priority to French application FR2307655 filed on July 17, 2023, the contents of which are hereby incorporated by reference in their entirety. Technical Field

[0002] The present invention belongs to the field of aviation structures, specifically to the field of connection between an engine and an aircraft structure, especially but not limited to the field of connection structures of aircraft wings. Background Art

[0003] The rear secondary structure of an engine pylon, such as a jet engine, is usually abbreviated as RSS, which is an aerodynamic fairing that is connected between the pylon primary structure supporting the engine and the aircraft wing primary structure by three anchor points.

[0004] Its shape is basically semi-conical, truncated, hollow, and trumpet-shaped at the connection with the pylon. Its cross-section becomes narrower both vertically and laterally along the direction from the pylon to the trailing edge to the connection with the wing.

[0005] Two other parts, also aerodynamic fairings, are assembled to the above structure: a lower fairing, usually abbreviated as APF (Aft Pylon Fairing), which matches the shape of the RSS and is affected by the hot air flow (>170°C) exhausted by the engine, so it is made of heat-resistant materials such as titanium alloys; the other is a fairing located at the end of the RSS, called a gutter, which can extend the conical shape of the RSS to the lower surface of the wing.

[0006] Both types of fairings, APF and groove, are supported by RSS.

[0007] RSS is a hollow shell that can accommodate some equipment to protect these equipment from environmental hazards such as fire, lightning, and impact.

[0008] Therefore, although it neither supports the weight of the engine nor transmits thrust, this secondary structure should be able to withstand strong mechanical stresses.

[0009] In addition to the aerodynamic loads during flight, the structure should be able to resist and maintain its integrity when subjected to strong vibrations that may occur after an engine accident such as ingestion of an object, breakage of a rotating blade, or more commonly, an imbalance of the engine's rotating parts.

[0010] In order to achieve the above resistance while maintaining lightness, in the prior art, the rear secondary structure is designed as a grid-like structure, including a skeleton frame composed of frames and pillars fixed to each other by rivet-type fasteners, on which are assembled panels, usually made of integral composite materials or made of sandwich materials.

[0011] Due to its rigidity, this structure cannot adapt by its own flexibility to any shape variations inherent in the mass production process, including those of the assembled elements that make up the rear substructure, such as frames, struts, panels, and the rear substructure itself and its anchor points to the pylons and the aircraft structure (especially the primary structure of the wing). During the assembly process, the slightest deviation may cause huge mechanical stresses in the rear substructure itself and in the aircraft structure to which it is assembled.

[0012] Therefore, the aerodynamic shape of the fairing is simplified, and planes or quasi-planes with large radius of curvature are chosen to avoid excessive shape differences between the assembled parts due to manufacturing dimension dispersion (manufacturing dimensions are always larger on parts with more complex shapes). Therefore, although the assembly structure at the connection between the pylon and the main structure is not simplified, the aerodynamics are still poor.

[0013] The rear secondary structure, including pillars, frames and panels are precision manufactured to limit dimensional deviations and ensure that their assembly does not induce stress, which means that its manufacturing cost is high.

[0014] Finally, the skeleton frame design leaves little room for mounting equipment, and access to the interior of the RSS for equipment control and maintenance is difficult to implement.

[0015] Document FR3120854A1 / US11780599B2 discloses a fairing system for an engine pylon. Summary of the invention

[0016] The deficiencies of the prior art can be solved by an engine pylon rear secondary structure for an aircraft, the aircraft comprising an engine pylon for suspending an engine on a wing, the engine pylon rear secondary structure comprising:

[0017] a front connection portion configured to be connected to the main structure of the engine pylon;

[0018] a rear connection portion configured to be connected to the main structure of the wing;

[0019] a composite beam connecting and attached to the front connecting portion and the rear connecting portion;

[0020] The composite beam includes a first portion and a second portion integral with the first portion;

[0021] The second part includes two branches;

[0022] The first part is connected to the rear connecting part, and the second part is connected to the front connecting part;

[0023] The frame includes an outer surface configured to support the fairing panel and attached to the first portion of the composite beam; and

[0024] A fairing panel is attached to the outer surface of the frame.

[0025] Thus, the generally Y-shaped composite beam provides both assembly rigidity and positioning of the other components of the fairing, the frame on the beam, and the panel on the frame.

[0026] The beam is precision manufactured in one piece to prevent the dimensional chain structure from being stretched.

[0027] Compared to the prior art, the above components are lighter in weight, have improved vibration resistance, and increase the internal space for accommodating equipment.

[0028] The rear substructure may be implemented according to the embodiments and variations described below, which may be applied individually or in any technically feasible combination.

[0029] According to some embodiments, the composite beam has a U-shaped cross-section.

[0030] According to some embodiments, the frame comprises three brackets arranged to be attached to the composite beam on three outer surfaces of the U-shaped cross-section.

[0031] According to some embodiments, the frame is in the shape of a horseshoe as a whole, comprising a frame web and a flange, and a free space is left between the inner sides of the frame web.

[0032] According to some embodiments, the three brackets of the frame are flanges integral with the web.

[0033] According to some embodiments, the outer surface of the frame is part of a flange that is integral with the frame web.

[0034] According to some embodiments, the outer surface of the frame is configured to support a fairing panel, which may have a shape selected from a flat panel, a single curvature panel, and a double curvature panel.

[0035] Preferably, the U-shaped cross section of the first portion of the composite beam gradually widens along a direction from the rear connecting portion to the second portion.

[0036] Preferably, the U-shaped cross-sections of the two branches of the second portion gradually widen in a direction toward the front connecting portion.

[0037] According to some embodiments, a first median plane in which the first portion extends and a second median plane in which the second portion extends intersect.

[0038] According to some embodiments, a composite beam is made of a composite material comprising a polymer matrix and a reinforcement material comprising continuous carbon fibers.

[0039] According to some embodiments, the material of the frame is selected from the group consisting of aluminum alloys, titanium alloys, and composite materials containing a polymer matrix and a reinforcement material comprising continuous carbon fibers.

[0040] Preferably at least one fairing panel has an access opening. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The technical solution of the present invention can be obtained according to the following and with reference to Figure 1-Figure 7 The described non-limiting embodiment is implemented wherein:

[0042] Figure 1 is a partial perspective view showing the positioning of RSS on an aircraft in the prior art;

[0043] Figure 2 A perspective view showing an exemplary embodiment of a skeleton frame of an RSS in the prior art;

[0044] Figure 3 is a three-dimensional illustration of RSS in an exemplary embodiment of the technical solution of the present invention;

[0045] Figure 4 It is a three-dimensional illustration of the skeleton framework of the RSS in an exemplary embodiment of the technical solution of the present invention;

[0046] Figure 5 It is a three-dimensional illustration of a composite beam and its cross section in a skeleton frame;

[0047] Figure 6 It is a three-dimensional illustration of the double curvature fairing panel;

[0048] Figure 7 is a perspective illustration of an exemplary embodiment or framework. DETAILED DESCRIPTION

[0049] like Figure 1 As shown, one side of the front portion of the prior art engine pylon rear secondary structure (hereinafter referred to as RSS) 100 is connected to the pylon 30 for suspending the engine 20 on the wing 10 of the aircraft, and the other side of the rear portion is connected to the underside of the wing.

[0050] This secondary structure serves as an aerodynamic fairing and supports a lower fairing 120 and a rear fairing 130 on the lower surface; wherein the lower fairing 120 is called APF, which is affected by the hot air flow ejected by the engine 20, and the rear fairing 130 is also called a groove, which has an aerodynamic shape that ends on the inner side of the wing 10.

[0051] like Figure 2 As shown, the skeleton 200 of the RSS in the prior art is composed of a group of metal parts, which are made of aluminum alloy and are firmly assembled together according to the lattice structure principle through accessories 230 and riveting, so that the structure is very strong and its rigidity is obtained by assembling all the parts into a whole like this.

[0052] The skeleton 200 has a front connection point 210 connecting it to the engine pylon and two rear connection points 221 , 222 connecting it to the main structure of the wing.

[0053] Panels, usually made of sandwich composite materials, are attached to the frame of the skeleton and to the outer surfaces of the spars to form fairings.

[0054] The existence of the above-mentioned structural components leaves almost no space for installing equipment in the frame.

[0055] This design involves a long chain-like structure comprising a plurality of components. Thus, as an example, the distance d between the front connection point 221 and the rear connection point 222 involves at least 8 structural components 201, 202, 203, 204, 205, 206, 207, 208 and is therefore dependent on the sum of the manufacturing and assembly tolerances of these components. Therefore, these components require precise and expensive manufacturing.

[0056] Again, for illustrative purposes, the variation in this distance, due to the deformations produced during operation, generates forces transmitted in all of these components, in particular through the connecting structures between them.

[0057] Therefore, additional assembly parts are required to strengthen these connections, which will increase the mass of the assembly, further increasing the stress level caused by strong vibrations (especially in the case of engine problems causing imbalance of rotating parts in the engine).

[0058] like Figure 3 As shown, according to some exemplary embodiments of the present invention, a RSS 300 that addresses the shortcomings of the prior art includes a composite beam 301 that forms the "spine" of the secondary structure, which is connected with:

[0059] Front connecting portion 310;

[0060] a rear connection portion 320; and

[0061] The frame 330 is configured to support the fairing panels.

[0062] Will Figure 4 and Figure 2 By comparison, the simplification of the skeleton frame can be seen: the composite beam 301 is the main structural component of the skeleton frame, and all other parts, especially the frame 330, are located on it.

[0063] To this end, each of the frames 330 (here, four frames 330 ) includes three brackets 431 , 432 , so that the frames 330 can be carried on the outer surface of the composite beam 301 and assembled therewith.

[0064] As a result, the dimension chain structure will be greatly shortened and the force transmission will be introduced into the composite beam of corresponding dimensions.

[0065] According to some exemplary embodiments, the front side connection part 310 and the rear side connection part 320 are connected to the first frame 330 and the last frame 330 , respectively.

[0066] The fairing panels are attached to the outer surface 435 of the frame. The frame 435 shown here has a curved outer surface, but the same frame structure and the same composite beam 301 can carry a frame with a flat outer surface, and its connection on the composite beam 301 is still completed by the three same brackets on the three outer surfaces of the composite beam 301.

[0067] Therefore, if Figure 6 As shown, by separating the structural function and the panel support function provided by the composite beam, the skeleton frame can mount the fairing panel 340 with double curvature, ie, curvature in at least two cross directions 601, 602, without causing further assembly difficulties.

[0068] From an aerodynamic point of view, this double-curvature shape of the fairing panels is more efficient.

[0069] However, the structure of the skeleton frame described above also allows the assembly of flat panels or panels of single curvature using a frame with a suitable outer surface, for example replacing an existing structure made according to the prior art.

[0070] The structure of the skeleton frame frees up space inside the RSS for installing equipment.

[0071] This free space is greater than in the prior art, reduces interference with structural members, and enables access to all or part of the space of the device without removing the fairing panels, which may include one or more access openings 640 for this purpose.

[0072] like Figure 5As shown, according to some embodiments, the composite beam 301 may include two integrated parts 501 and 502 , wherein the first part 501 extends along a first middle plane 51 , and the second part 502 extends along a second middle plane 52 , and the first middle plane 51 and the second middle plane 52 intersect.

[0073] The second portion 502 includes two branch portions 511 and 512 , so that the composite beam 301 is in a split Y shape as a whole.

[0074] The composite beam 301 may be an integral structure having a U-shaped cross section 550, wherein the thickness and length of the U-shaped flange vary in the first portion 501 and the second portion 502 of the composite beam 301 and the two branches 511, 512 of the second portion. In particular, the cross section becomes thicker at the connection portions 531, 532 where the frame 330 is connected to the composite beam 301, and the cross section of the two branches 511, 512 of the second portion 502 becomes wider from the connection with the first portion 501 to the front connection portion 310. These cross section changes may be determined by calculation in any manner known to those skilled in the art according to the load conditions of the structure.

[0075] As a non-limiting example, the composite beam 301 is made of a thermosetting resin reinforced with continuous carbon fibers, ie extending continuously from one edge of the beam to the other, with a reinforcement ratio between 50% and 60%.

[0076] Thus, the composite beam 301 may be very durable, rigid, and lightweight, and may be particularly advantageous for withstanding severe vibrations.

[0077] For example, in 1811x 337x 425mm 3 The secondary volume has a thickness of 3.63 mm and a minimum cross section of 551 mm. 2 , Maximum cross section is 883mm 2 The mass of the composite beam is less than 2kg.

[0078] The composite beam 301 can be Sales The RTM 6 resin is infused into a fiber preform, for example by forming the fiber preform in a closed mold by the RTM process (ie, resin transfer molding process), or by any other equivalent method.

[0079] This makes it possible to manufacture relatively complex composite beams in one-piece construction without assembly and with repeatable manufacturability with a precision difference of less than 0.4 mm, the outer surface of the beam, in particular the outer surface of the load-bearing frame, in contact with the forming surface of the closed mold.

[0080] Alternatively, the composite beam may also be made from a thermoplastic polymer matrix containing continuous carbon fibers as reinforcement material.

[0081] In this case, the composite beam can be produced by, for example, shape consolidation of prepreg layers or stamping of a thermoplastic composite blank.

[0082] The frame may be formed or machined from an aluminum alloy or a titanium alloy.

[0083] Alternatively, the frame may also be made of a polymer-based composite material containing fiber reinforcements.

[0084] like Figure 7 As shown, according to some embodiments, the frame 303 includes a web 701 , the outer surface of which has a flange 702 that is integral with the web 701 and extends from the web 701 .

[0085] The brackets 431 , 432 , 433 may also be flanges extending from the web 701 and formed integrally with the web 701 .

[0086] The frame can be made of a composite material including a polymer matrix and a fiber reinforcement material, and can be obtained by preparing a fiber preform by RTM, or by stamping a thermoplastic composite blank.

[0087] The frame may also be made of aluminum or titanium alloy, and the entirety is obtained by forming methods such as superplastic forming and machining.

[0088] Alternatively, whether made of a composite material or a metal material, the frame 330 can be obtained by assembly.

[0089] The frames are positioned by brackets and assembled on the plane of the composite beams, which leaves a lot of freedom in the shape of the fairing panels.

[0090] In addition, if Figure 4 As shown, the overall horseshoe shape of the frame leaves a free space between the inside of the frame web 701 in the RSS and the inner surface of the fairing panel 340 without structural components, so that equipment can be installed there.

[0091] During the assembly process, a positioning tool may be used to position the frame on the composite beam and to drill holes in the frame and the composite beam.

[0092] Frames can use HI-LITE for final fixing of composite beams TM (LISI AEROSPACE) type fasteners are made in drilled holes.

[0093] Then, assemble the fairing panels to the frame.

[0094] Therefore, the number of assembly parts and fasteners is greatly reduced compared to the prior art.

[0095] The technical solution proposed by the present invention thus enables the manufacture of a lighter RSS 300, with a mass increase of about 30% compared to the prior art, with more precise manufacturing and using fewer components, while providing greater flexibility in the choice of the shape of the fairing panels, thereby achieving better aerodynamics, and having a larger free internal space capable of installing more or larger equipment while making it easier to reach these equipment.

Claims

1. An engine pylon rear secondary structure for an aircraft, the aircraft comprising an engine pylon (30) for suspending an engine (20) on a wing (10), the engine pylon rear secondary structure comprising: A front connecting portion (310) configured to be connected to the main structure of the engine pylon (30); a rear connection portion (320) configured to be connected to the main structure of the wing (10); a composite beam (301) connecting and attached to the front connecting portion (310) and the rear connecting portion (320); The composite beam (301) comprises a first portion (501) and a second portion (502) integrated with the first portion (501); The second part includes two branches (511, 512); The first part (501) is connected to the rear connecting part (320), and the second part (502) is connected to the front connecting part (310); The frame (330) includes an outer surface (435) configured to support a fairing panel (340) and attached to the first portion (501) of the composite beam (301); and a fairing panel attached to said outer surface of said frame; The composite beam has a U-shaped cross section, and the frame (330) includes three brackets (431, 432, 433), which are arranged to be attached to the composite beam (301) on three outer surfaces of the U-shaped cross section.

2. The rear secondary structure of the engine bracket according to claim 1, characterized in that: in, The frame is in the shape of a horseshoe as a whole, and comprises a frame web (701) and a flange, and a free space is left between the inner sides of the frame web.

3. The rear secondary structure of the engine bracket according to claim 2, characterized in that: in, The three brackets of the frame are flanges integral with the web.

4. The rear secondary structure of the engine bracket according to claim 2, characterized in that: in, The outer surface (435) of the frame is part of a flange (702) that is integral with the frame web (701).

5. The rear secondary structure of the engine bracket according to claim 1, characterized in that: in, The outer surface (435) of the frame (330) is configured to support a fairing panel (340) having a shape selected from a flat panel, a single curvature panel, and a double curvature panel.

6. The rear secondary structure of the engine bracket according to claim 1, characterized in that: in, The U-shaped cross section (550) of the first portion (501) of the composite beam gradually widens in a direction from the rear connecting portion (320) upward to the second portion (502).

7. The rear secondary structure of the engine bracket according to claim 1, characterized in that: in, The U-shaped cross-section of the two branches (511, 512) of the second portion (502) gradually widens in a direction toward the front connecting portion (310).

8. The rear secondary structure of the engine bracket according to claim 1, characterized in that: in, A first middle plane (51) extending from the first portion (501) and a second middle plane (52) extending from the second portion (502) intersect.

9. The rear secondary structure of the engine bracket according to claim 1, characterized in that: in, The composite beam (301) is made of a composite material comprising a polymer matrix and a reinforcement material comprising continuous carbon fibers.

10. The rear secondary structure of the engine bracket according to claim 1, characterized in that: in, The material of the frame (330) is selected from aluminum alloy, titanium alloy and a composite material containing a polymer matrix and a reinforcing material containing continuous carbon fibers.

11. The rear secondary structure of the engine bracket according to claim 1, characterized in that: in, The fairing panel (340) has an access opening (640).

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