Aircraft part comprising a floor connected to a fuselage section by means of elastic connecting rods.

Abstract

- Part of an aircraft comprising a floor connected to a section of the fuselage by means of elastic connecting rods.- The aircraft part (1) comprises a fuselage section (2) and a floor (3), at least a portion of which is connected to said fuselage section (2) by means of elastic connecting rods (13, 14). Each elastic connecting rod (13, 14) is provided with a first end (15, 17) adapted to be fixed to the floor (3) and a second end (16, 18) adapted to be fixed to the fuselage section (2). Said elastic connecting rods (13, 14) are configured to exhibit rigidity that allows both the transmission of forces between the floor (3) and the fuselage section (2) and the absorption of displacements induced by deformations of the fuselage section (2). Said aircraft part (1) thus makes it possible, at a lower cost and with a lower mass, to obtain a connection between the floor (3) and the fuselage section (2) with suitable elasticity capable of transmitting inertial forces while absorbing deformations of said fuselage section(2). Figure for the abbreviation: Fig. 1.

Description

Title of the invention: Aircraft part comprising a floor connected to a fuselage section by means of elastic connecting rods. technical field

[0001] The present invention relates to an aircraft part comprising a floor connected to a fuselage section by means of elastic connecting rods. State of the art

[0002] The fuselage of an aircraft is a structure subjected to significant stresses and strains, which can be caused, for example, by external mechanical stresses, the weight of the aircraft, or control surface deflections. These stresses cause deformations of the fuselage, particularly near the landing gear bay and the center wing box. Because of such deformations, it is not advisable to provide a rigid, continuous floor attached to the fuselage on both sides. Indeed, such a structure would exhibit a high degree of deformation incompatibility; that is, the deformations of the fuselage would induce excessive stresses on the floor and the fuselage.

[0003] One solution to this problem is to provide, at several points along the aircraft, particularly where deformation is greatest, a floor with discontinuous crossbeams, so as to prevent the floor from being coupled to the deformation of the fuselage. However, this solution is not entirely satisfactory, especially in cargo aircraft. Indeed, in a cargo aircraft, containers are generally held to the floor by hooks or latches attached to it. Therefore, if the floor includes discontinuous crossbeams designed to absorb fuselage deformations, sections of the floor may separate from one another, so that the hooks or latches may no longer hold the containers.

[0004] One solution to this problem is to add a robust intermediate structure between the fuselage and the floor, capable of withstanding the mechanical stresses induced by the deformations of the fuselage without transmitting deformations to the floor. However, such a structure has a significant mass and cost.

[0005] These usual solutions are therefore not completely satisfactory. Description of the invention

[0006] The present invention relates to an aircraft part comprising at least one fuselage section and a floor attached to said fuselage section, which has the purpose of remedying the aforementioned drawbacks.

[0007] According to the invention, at least a portion of said floor is connected to said section of fuselage by means of elastic connecting rods, each elastic connecting rod being provided with a first end suitable for being fixed to the floor and a second end suitable for being fixed to the fuselage section, said elastic connecting rods being configured to exhibit a rigidity enabling both the transmission of forces between the floor and the fuselage section and the absorption of displacements induced by deformations of the fuselage section.

[0008] Thus, thanks to the invention, we have, at a lower cost and with a lower mass, a part of an aircraft whose connection between the floor and the fuselage section, formed by elastic connecting rods linking at least a part of the floor to the fuselage section, has an appropriate elasticity capable of transmitting forces while absorbing deformations of said fuselage section, as specified below.

[0009] In a preferred embodiment, said floor comprises crossbeams and at least some of said crossbeams are connected to said fuselage section, for each crossbeam by means of at least one elastic connecting rod. Furthermore, preferably, at least some of said crossbeams are connected on both sides of said fuselage section by means of elastic connecting rods.

[0010] Advantageously, at least one of said elastic connecting rods is linked to the fuselage section at a rigid point on said fuselage section. Preferably, said rigid point is positioned at or below floor level.

[0011] In a first embodiment, at least one of said elastic connecting rods is arranged so that its first end connected to the floor is located towards the inside and towards the top of the aircraft part relative to its second end connected to the fuselage section.

[0012] Furthermore, in a second embodiment, at least one of said elastic connecting rods is arranged so that its first end connected to the floor is located towards the outside and towards the top of the aircraft part relative to its second end connected to the fuselage section.

[0013] Moreover, in a particular embodiment, at least one of said elastic connecting rods corresponds to one of the following connecting rods: an elliptical spring connecting rod, a spring washer connecting rod, a piston connecting rod.

[0014] In addition, advantageously, the aircraft part comprises at least one shock absorber coupled to at least one of said elastic connecting rods.

[0015] Furthermore, advantageously, the aircraft part includes at least one damping system associated with at least one of said elastic connecting rods.

[0016] The present invention also relates to an aircraft, in particular a cargo aircraft, comprising an aircraft part such as that described above. Brief description of the figures

[0017] The accompanying figures will clearly illustrate how the invention can be implemented. In these figures, identical reference numerals designate similar elements.

[0018] Fig. 1 is a schematic cross-sectional view of a first embodiment of an aircraft part comprising a floor connected to a fuselage section by elastic connecting rods.

[0019] Fig. 2 is a schematic cross-sectional view of the aircraft part according to the first embodiment in which the fuselage section shown in solid line undergoes a particular deformation, the schematic view also showing in dashes the undeformed fuselage section.

[0020] Fig. 3 is a partial cross-sectional view of the aircraft part according to the first embodiment, the floor of which rests on gantries, some of which are linked together by connecting walls.

[0021] Fig. 4 is a partial perspective view of the aircraft part according to the first embodiment showing a plurality of floor crossbeams.

[0022] Fig. 5 is a schematic cross-sectional view of a second embodiment of an aircraft part comprising a floor connected to a fuselage section by elastic connecting rods, the schematic view showing the deformed fuselage section in solid lines and the undeformed fuselage section in dashes.

[0023] Fig. 6 is a schematic, perspective view of an aircraft comprising an aircraft part according to a particular embodiment. Detailed description

[0024] The aircraft part 1 schematically represented in particular embodiments from [Fig.1] to [Fig.6] and used to illustrate the invention is a part (or section) of an AC aircraft ([Fig.6]).

[0025] In the context of the present invention, the term "aircraft part" means a section of the airframe of aircraft AC along the longitudinal direction of said aircraft AC, comprising at least one fuselage section and one segment of the floor of aircraft AC. Although not exclusively, aircraft part 1 is particularly suitable for an aircraft corresponding to a cargo aircraft, namely an aircraft intended for the transport of freight, for example in the form of containers.

[0026] Aircraft part 1, shown in Figures 1 to 5, comprises a fuselage section 2 and a floor 3 connected to said fuselage section 2. Aircraft part 1 has a longitudinal axis XX (shown in Figures 4 and 6) corresponding to the longitudinal axis of the aircraft AC of which it is intended to be a part. It also has a vertical axis ZZ forming with the longitudinal axis XX a vertical plane of symmetry of the aircraft AC, as well as a transverse axis YY orthogonal to both the longitudinal axis XX and the vertical axis ZZ. These axes thus form a coordinate system or- thogonal.

[0027] In the remainder of the description, the following terms are defined as follows: - the terms "superior" or "high" are relative to an element which is located along the direction of the vertical axis ZZ in the direction of an arrow A represented in particular on [Fig.1] and [Fig.5]; - the term "lower" relates to an element which is located along the direction of the vertical axis ZZ in the direction of an arrow B (opposite to arrow A) represented in particular on [Fig.1] and [Fig.5]; - the term "transverse" relates to an element which is located along the direction of the transverse axis YY; - the term "interior" refers to an element that is close to, or oriented towards, the longitudinal axis XX; and - the terms "exterior" or "external" are related to an element that moves away from, or is oriented in the opposite direction to, the longitudinal axis XX.

[0028] The fuselage section 2 comprises frames 4 on which panels 24 (shown partially, very schematically, and in dashed lines in [Fig. 4]) are intended to be arranged to form a skin for the fuselage of the aircraft AC. In a preferred embodiment, shown in more detail in [Fig. 3] and [Fig. 4], the frames 4 are arranged symmetrically on either side of the longitudinal axis XX and are regularly spaced longitudinally from each other. The frames 4 correspond to arcs of circles so that the fuselage section 2 has a substantially cylindrical shape with the longitudinal axis XX as its central axis.

[0029] Furthermore, in a particular embodiment, the aircraft part 1 comprises, towards the bottom, a wall 5, as shown in [Fig. 1], [Fig. 2], [Fig. 3] and [Fig. 5]. This wall 5 may, in particular, correspond to a roof of a conventional landing gear bay or to an extrados panel of a conventional center wing box.

[0030] The floor 3 corresponds to a typical aircraft floor. It may be a complete floor or a floor segment intended, for example, to be joined to one or more other floor segments to form a complete floor. The floor 3 is arranged inside the fuselage section 2, namely in the space delimited by the cylinder formed by the fuselage section 2. Furthermore, the floor 3 includes cross members 6 that bear on longerons (or beams or frames) 7, as shown in [Fig. 1] to [Fig. 5]. The cross members 6 correspond to continuous (or discontinuous) beam elements and are arranged parallel to the transverse axis YY, from one side of the fuselage section 2 to the other. The longerons 7, for their part, correspond to beam elements arranged parallel to the longitudinal axis XX.

[0031] Furthermore, as shown in [Fig. 3], the aircraft part 1 may also include connecting wings 8. The connecting wings 8 correspond to structural elements forming, for example, part of the landing gear bay or the center wing box. They can, in particular, allow the various longerons 7 to be connected transversely to each other.

[0032] The stringers 7 and connecting webs 8 can, in particular, be made of metallic material, for example aluminum. These elements are connected to each other. They can, for example, be fixed together by means of conventional mechanical fasteners or by welding.

[0033] Furthermore, in the embodiments schematically represented in [Fig. 1], [Fig. 2], and [Fig. 5], the floor 3 comprises longitudinal rails 23 equipped with latches (or hooks) 10 and 11 and longitudinal rails 23 equipped with supports 12 (generally rollers). The latches (or hooks) 10 and 11 and the supports 12 are intended to hold a load 9, for example, a container. The latches (or hooks) 10 and 11 and the supports 12, of standard types, are arranged on an upper face 29 of the floor 3. The rails 23 equipped with the latches (or hooks) 10 and 11 are fixed to crossbeams 6 of the floor 3 at their transverse ends. They are configured to hold the load 9 in place at least transversely, namely along the transverse axis YY. The locks (or hooks) 10 and 11 as well as the crossbeams 6 are rigid and non-deformable, particularly transversely.Load 9 therefore cannot be released, for example under the effect of inertial forces.

[0034] In addition, the supports 12 are regularly distributed over at least part of the upper surface 29 of the floor 3 in order to support the load 9 uniformly.

[0035] Furthermore, within the framework of the present invention, at least some of the crossbeams 6 of the floor 3 are linked to the fuselage section 2 by means of elastic connecting rods 13 and 14. The term "elastic connecting rod" means a part provided with articulation at its ends, of adjustable or non-adjustable length, having a sufficiently elastic behavior (low modulus and high elongation) in order to transmit forces while allowing a certain deformation of said elastic element depending on its rigidity, as specified below.

[0036] Aircraft part 1 comprises a plurality of elastic connecting rods 13 and 14 in the longitudinal direction X ([Fig. 4]), of which only two are visible in the cross views of [Fig. 1], [Fig. 2], [Fig. 3], and [Fig. 5]. Each of the elastic connecting rods 13 and 14 is provided with a first end 15, 17 connected to the floor 3 and a second end 16, 18 connected to the fuselage section 2. More specifically, the end 15 of the elastic connecting rod 13 is fixed to one of the cross members 6 of the floor 3, and the end 16 of the elastic connecting rod 13 is fixed to one of the frames 4 of the section of fuselage 2. Similarly, the end 17 of the elastic connecting rod 14 is fixed on the cross member 6 of the floor 3 and the end 18 of the elastic connecting rod 14 is fixed on one of the frames 4 of the fuselage section 2.

[0037] The elastic connecting rods 13 and 14 are connecting rods with calibrated stiffness. More particularly, the elastic connecting rods 13 and 14 are configured to have a stiffness that allows, on the one hand, the transmission of transverse inertial forces between the floor 3 and the fuselage section 2, and on the other hand, the absorption of displacements induced by deformations of the fuselage section 2.

[0038] Thus, when the fuselage section 2 deforms, this deformation is absorbed by the elastic connecting rods 13 and 14, which limits the stresses experienced by the floor 3 and the fuselage section 2. The aircraft part 1 therefore includes a floor 3 which is rigid and allows the load 9 to be held in place securely and which does not create any incompatibility of deformation with the fuselage section 2.

[0039] Furthermore, the elastic connecting rods 13 and 14 are sufficiently rigid to transmit forces to the fuselage section 2, in particular inertial forces transmitted from the load 9 to the floor 3 and then to the fuselage section 2. The elastic connecting rods 13 and 14 therefore also make it possible to keep the floor 3 and the load 9 substantially centered inside the fuselage section 2.

[0040] In a preferred embodiment, the elastic connecting rods 13 and 14 are configured to have a fixed stiffness and a sufficient stroke, adapted to the floor 3 and the load 9 to be supported. For example, depending in particular on the known maximum deformations of the fuselage section 2 and the mass of the load 9 (allowing the inertial forces to be determined), a stiffness and stroke of the elastic connecting rods 13 and 14 suitable for obtaining a desired maximum displacement of the floor 3 can be defined.

[0041] The arrangement of these elastic connecting rods 13 and 14 thus makes it possible, at a lower cost and with less mass, to ensure the transverse (or lateral) connection between the floor 3 with continuous cross members 6 and the fuselage section 2, particularly in areas of the aircraft AC where the fuselage deformation is greatest. In particular, it makes it possible to avoid the need for a rigid structure (such as a longitudinal box girder) dedicated to supporting the floor in the transverse direction.

[0042] In a particular embodiment, the elastic connecting rods 13 and 14 may correspond to adjustable elastic connecting rods, namely connecting rods whose stiffness and stroke can be adjusted to desired values. Thus, the aircraft part 1 can be adapted to carry various loads, in particular loads of different masses.

[0043] Furthermore, in a particular embodiment, the elastic connecting rods 13 and 14 are linked to the fuselage section 2 at so-called "rigid" points of said section. fuselage 2. In particular, the end 16 of the elastic connecting rod 13 is fixed to the fuselage section 2 at a rigid point 19. Similarly, the end 18 of the elastic connecting rod 14 is fixed to the fuselage section 2 at a rigid point 20. The rigid points 19 and 20 correspond to attachment points located on areas of the fuselage section 2 which are less deformable than the rest of the areas concerned.

[0044] Preferably, the rigid points 19 and 20 are positioned on areas of the fuselage section 2 located below the level of the floor 3 (in the Z direction), namely on the downward-facing side of the floor 3 of the aircraft part 1. These areas of the fuselage section 2 undergo less deformation, as illustrated in [Fig. 2] and [Fig. 5], where the fuselage section 2 undergoes specific deformations. In [Fig. 2] and [Fig. 5], the fuselage section 2 is shown in two different embodiments. The solid line represents the deformed fuselage section 2, and the dashed line represents the undeformed fuselage section 2. Consequently, the rigid points 19 and 20 are located in areas that exhibit minimal displacement during the deformation of the fuselage section 2.

[0045] In the embodiment shown in [Fig.1], the rigid points 19 and 20 are positioned on the frames 4. However, the rigid points 19 and 20 can be positioned on other elements of the fuselage section 2, for example on lateral ends of the wall 5, and as specified below with reference to the embodiment of [Fig.5] on the extreme lateral ends, namely those closest to the fuselage section 2.

[0046] In a particular embodiment, shown in [Fig.4], all the crossbeams 6 of the floor 3 are linked to the frames 4 of the fuselage section 2, via two elastic connecting rods 13 and 14. Preferably, all the elastic connecting rods 13 and 14 are identical, that is to say, they all have the same dimensions and the same mechanical properties, in particular the same elastic properties.

[0047] Furthermore, in other embodiments (not shown), as a variant of this particular embodiment, only certain crossbeams 6 of the floor 3 are connected to the fuselage section 2 by elastic connecting rods.

[0048] In a first embodiment, shown in [Fig.1] to [Fig.4], the elastic connecting rods 13 and 14 are arranged between the floor 3 and the fuselage section 2 in an oblique (or inclined) manner with respect to the vertical axis ZZ and with respect to the transverse axis YY.

[0049] More specifically, in this first embodiment, the elastic connecting rod 13 is arranged so that its end 15 linked to the floor 3 is located inwards (along the transverse axis YY) and upwards (along the vertical axis ZZ) relative to its end 16 linked to the fuselage section 2.

[0050] Similarly, the elastic connecting rod 14 is arranged so that its end 17 is connected to the floor 3 is located inwards (along the transverse axis YY) and upwards (along the vertical axis ZZ) relative to its end 18 connected to fuselage section 2.

[0051] In this first embodiment, the elastic connecting rods 13 and 14 are connected to the floor 3 under the cross member 6 (the side of the cross member 6 facing downwards towards the aircraft part 1). They are fixed to the cross member 6. In one embodiment, they are fixed to the transverse ends of the cross member 6. In the illustrated embodiment, they are fixed to the cross member 6 near junctions 21 and 22 between said cross member 6 and the two outermost transverse longerons 7, at each transverse end (along the transverse axis YY) of the floor 3. In particular, the end 15 of the elastic connecting rod 13 is fixed near junction 21 and the end 17 of the elastic connecting rod 14 is fixed near junction 22.

[0052] Furthermore, in a second embodiment, represented in [Fig.5], the elastic connecting rods 13 and 14 are oriented obliquely (or inclined) with respect to the vertical axis ZZ and with respect to the transverse axis YY so that their end connected to the floor 3 is located towards the outside of the aircraft part 1, and their end connected to the fuselage section 2 is located towards the inside of the aircraft part 1.

[0053] More specifically, in this second embodiment, the elastic connecting rod 13 is arranged so that its end 15 linked to the floor 3 is located outwards (along the transverse axis YY) and upwards (along the vertical axis ZZ) relative to its end 16 linked to the fuselage section 2.

[0054] Similarly, the elastic connecting rod 14 is arranged so that its end 17 linked to the floor 3 is located outwards (along the transverse axis YY) and upwards (along the vertical axis ZZ) relative to its end 18 linked to the fuselage section.

[0055] In this second particular embodiment, the elastic connecting rods 13 and 14 are connected to the floor 3 under the cross member 6 (the side of the cross member 6 facing downwards towards the aircraft part 1). According to one embodiment, they are connected to the transverse ends of the latter. According to the illustrated embodiment, the end 15 of the elastic connecting rod 13 is fixed to the transverse end 25 of the cross member 6 and the end 17 of the elastic connecting rod 14 is fixed to the transverse end 26 of the cross member 6.

[0056] Furthermore, the elastic connecting rods 13 and 14 are linked to the fuselage section 2 at the transverse ends of the wall 5, for example, the landing gear bay roof or the upper surface panel of the center wing box. In particular, the end 16 of the elastic connecting rod 13 is fixed to a beam 27 of the center box 5 and the end 18 of the elastic connecting rod 14 is fixed to a beam 28 of the center box 5. In the illustrated embodiment, these are the beams 27 and 28 located at the outermost point relative to the others, transversely.

[0057] Of course, the arrangements of the elastic connecting rods 13 and 14, as described below- The above are not limiting. The elastic connecting rods 13 and 14 can, in fact, be arranged between the floor 3 and the fuselage section 2 in various ways.

[0058] Furthermore, the elastic connecting rods 13 and 14 can correspond to any type of conventional connecting rod allowing sufficient rigidity and stroke to be obtained corresponding to the desired values.

[0059] In a particular embodiment, they may correspond to an elliptical spring connecting rod, a spring washer connecting rod, or a piston connecting rod. More generally, they may correspond to any other type of connecting rod exhibiting the aforementioned rigidity and elongation characteristics, that is, offering relatively low calibrated rigidity and relatively high elongation (or stroke).

[0060] Furthermore, in a particular embodiment, shown in [Fig.5], the aircraft part 1 includes conventional shock absorbers 30, for example hydraulic shock absorbers, coupled to at least some of the elastic connecting rods 13 and 14, and preferably to all of the elastic connecting rods 13 and 14. A shock absorber 30 can be coupled in parallel or in series to the elastic connecting rod 13, 14. In addition, it can be directly integrated into the latter (as shown schematically in [Fig.5]) or not.

[0061] Thanks to the dampers 30, it is possible to eliminate or at least mitigate an undesirable dynamic response or resonance, in particular of the floor 3 and its load 9.

[0062] The aircraft part 1 described above is intended to be part of an AC aircraft as illustrated in [Fig. 6]. Preferably, the aircraft part 1 corresponds to a central part of the AC aircraft, as shown in [Fig. 6]. This central part may, in particular, correspond to the part located along the longitudinal axis XX at the level of the wing center box and the landing gear bay.

[0063] The aircraft part 1 comprising a fuselage section 2 and a floor 3 connected to said fuselage section 2 by means of elastic connecting rods 13 and 14, as described above, has many advantages. In particular: - it allows for a suitable elastic connection between the floor 3 and the fuselage section 2 at a lower cost and with a lower mass; - it helps to avoid any incompatibility of deformation between the rigid floor 3 and the fuselage section 2, particularly in areas where said fuselage section 2 undergoes significant deformations; - it allows the transmission of forces, particularly inertial forces, between the floor 3 and the fuselage section 2; and - it avoids the need for a complex, expensive and heavy rigid structure between floor 3 and fuselage section 2.

Claims

Demands

1. Aircraft part comprising at least one fuselage section and a floor connected to said fuselage section, at least a portion of said floor (3) being connected to said fuselage section (2) by means of elastic connecting rods (13, 14), each elastic connecting rod (13, 14) having a first end (15, 17) adapted to be fixed to the floor (3) and a second end (16, 18) adapted to be fixed to the fuselage section (2), said elastic connecting rods (13, 14) being configured to exhibit rigidity enabling both the transmission of forces between the floor (3) and the fuselage section (2) and the absorption of displacements induced by deformations of the fuselage section (2), characterized in that at least one of said elastic connecting rods (13, 14) is arranged such that its first end (15, 17) connected to the floor (3) is located outwards and upwards from the aircraft part (1) relative to its second end (16,18) linked to the fuselage section (2).

2. Aircraft part according to claim 1, characterized in that said floor (3) comprises crossbeams (6) and in that at least some of said crossbeams (6) are connected to said fuselage section (2), for each crossbeam (6) by means of at least one elastic connecting rod (6).

3. Aircraft part according to claim 2, characterized in that at least some of said cross members (6) are linked on both sides to said fuselage section (2) by means of elastic connecting rods (6).

4. Aircraft part according to any one of the preceding claims, characterized in that at least one of said elastic connecting rods (13, 14) is linked to the fuselage section (2) at a rigid point (19, 20) of said fuselage section (2).

5. Aircraft part according to claim 4, characterized in that said rigid point (19, 20) is positioned at the level of the floor (3) or below the level of the floor (3).

6. Aircraft part according to any one of the preceding claims, characterized in that at least one of said elastic connecting rods (13, 14) is arranged so that its first end (15, 17) connected to the floor (3) is located towards the inside and upwards of the aircraft part (1) relative to its second end (16, 18) connected to the fuselage section (2).

7. Aircraft part according to any one of the preceding claims, characterized in that at least one of said elastic connecting rods (13, 14) corresponds to one of the following connecting rods: an elliptical spring connecting rod, a spring washer connecting rod, a piston connecting rod.

8. Aircraft part according to any one of the preceding claims, characterized in that it comprises at least one damper (30) coupled to at least one of said elastic connecting rods (13, 14).

9. Aircraft, in particular a cargo aircraft, characterized in that it comprises an aircraft part (1) according to any one of claims 1 to 8.

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