Assembly for an aircraft propulsion unit, comprising an improved mounting system for hinging a movable cowl to a support structure

Abstract

The invention relates to an assembly (200) for an aircraft propulsion unit, comprising a support structure (104) and a first movable cowl (4a) which is pivotably mounted at one of its ends on the support structure, along a hinge axis (8a) of the cowl, the assembly comprising a system (6a) for mounting the first movable cowl on the support structure (104), the mounting system comprising a first mounting device (10a) forming a hinge centred on the hinge axis, and a second mounting device (12a) comprising a connecting rod (14a) having a first connecting rod end mounted on the support structure (104) via a first mechanical connection (15a) and a second connecting rod end mounted on the first movable cowl (4a) via a second mechanical connection (16a). According to the invention, the first mechanical connection (15a) is centred on the hinge axis (8a) of the cowl.

Description

[0001] AIRCRAFT PROPELLER ASSEMBLY, INCLUDING AN IMPROVED MOUNTING SYSTEM FOR ARTICULATING A MOVABLE COWL ON A SUPPORT STRUCTURE

[0002] TECHNICAL FIELD

[0003] The invention relates to the field of aircraft propulsion systems, and more specifically to the mounting of movable cowlings on a support structure, such as an aircraft turbomachine mounting mast.

[0004] The invention applies to propulsion assemblies comprising aircraft turbomachinery of all kinds, such as a turbojet, a turboprop, and even more particularly a turbojet with one or more unfaired fan(s).

[0005] STATE OF PRIOR ART

[0006] Aircraft propulsion systems generally include a turbomachine, such as a turbojet, as well as a nacelle forming the aerodynamic part of the propulsion system, and a mounting mast to which the turbomachine is attached.

[0007] The nacelle includes movable hoods, which are mounted articulated on the towing mast, so that they can be opened by pivoting, in order to carry out maintenance operations, in particular on the turbomachine.

[0008] To achieve this, each movable hood is equipped with a mounting system consisting of several hinges spaced apart along the hood's pivot axis. In addition to conventional hinges, the mounting system may also incorporate another type of mounting device, including a connecting rod to provide flexibility. Such a design, in which the connecting rod introduces a degree of freedom of movement to provide the desired flexibility, is described, for example, in document FR 3087497 A1.

[0009] With this flexibility, when the movable cowling is closed, it engages more easily with another component of the propulsion system, such as a turbomachine housing. For example, this engagement may be desirable to provide axial retention of the movable cowling in the closed position. This retention could take the form of a radially open groove on one of the two components (the turbomachine and the cowling), and a radial rib housed within the groove on the other component. The connecting rod is articulated at both ends. Specifically, it has one end mounted on the mounting mast via a first mechanical linkage, and a second end mounted on the movable cowling via a second mechanical linkage. This second mechanical linkage is centered on the axis of the other conventional hinges of the movable cowling mounting system on the mast.

[0010] Therefore, this solution requires sufficient space to house the connecting rod between the mast and the cowling pivot point, without exceeding the aerodynamic lines defined by the mast cowling, within which the connecting rod must remain concealed when the cowling is closed. Furthermore, this space must remain sufficient to prevent any interference between the moving connecting rod and adjacent components of the propulsion system during cowling opening and closing operations.

[0011] Therefore, there remains a need to optimize the design of aircraft propulsion systems in order to best overcome the aforementioned constraints.

[0012] DESCRIPTION OF THE INVENTION

[0013] To meet the need mentioned above, the invention first relates to an assembly for an aircraft propulsion system, comprising the characteristics of claim 1.

[0014] The proposed design advantageously facilitates the installation of the connecting rod within the propulsion assembly, while also allowing for the desired flexibility within the movable cowling mounting system. This is because the connecting rod is positioned further away from the movable cowling, in a less congested area. This allows, ideally, for the use of an internal space within the cowling to house at least part of the connecting rod. Indeed, the chosen design advantageously minimizes the axial footprint of the assembly by housing the connecting rod within an internal space of the cowling, a space in which the connecting rod moves during the opening and closing of the cowling. Since the connecting rod is isolated from the various gas flows of the propulsion assembly by the cowling's outer layers, it is advantageously unnecessary to install additional, specific cowlings to provide this isolation function.This results in mass gains.

[0015] The invention also features at least one of the following optional characteristics, taken individually or in combination. Preferably, each of the first and second mechanical connections is implemented in one of the following forms:

[0016] - a pivot joint, preferably a sliding pivot;

[0017] - a kneecap.

[0018] Preferably, at least in the closed position of the first movable cowl, the second mechanical linkage has a point of application of a connecting rod force on the first movable cowl. At this point of application, a tangential direction of the first cowl is defined, and the connecting rod extends from its second end to its first end, positioned radially inward with respect to this tangential direction. This design ensures that the forces acting on the cowl in the closed position allow it to be pressed radially inward, preferably against the turbomachine. This function is particularly relevant when such pressing is required to maintain the functionality of an axial retaining device for the movable cowl, which may, for example, have a radially open groove, such as a V-groove.

[0019] One of the advantages of the invention lies in the possibility of using a connecting rod of considerable length, partially embedded in the hood. By providing such a length, it is possible, for example, to design the two mechanical connections of the connecting rod as simple ball joints, rather than as potentially bulkier sliding pivots.

[0020] Preferably, the mounting system comprises several first mounting devices spaced apart along the hood's articulation axis, each of the first devices forming a hinge centered on the articulation axis, and the hinge defining a pivot joint, preferably a sliding pivot.

[0021] Preferably, the first hood has a general half-shell shape, one end of which is mounted on the support structure, and the other end of which is equipped with a locking device.

[0022] Preferably, the assembly includes a second movable cover pivotally mounted at one end on the support structure. This second cover is mounted to the support structure using a mounting system identical or similar to that used for the first movable cover. Consequently, all the features and specifications described above for the first movable cover also apply to the second movable cover.

[0023] Preferably, the support structure is a turbomachine mounting mast. Preferably, the second mounting device is located at an axial end of the mounting system for the first movable cowling.

[0024] Preferably, the first movable cowling is a nacelle cowling, for example a fan cowling or a thrust reverser cowling. Preferably, the first movable cowling radially delimits a portion of a secondary flow of the propulsion system, and more particularly forms an internal and external radial boundary of this secondary flow.

[0025] The invention also relates to an aircraft propulsion system comprising an assembly as described above, as well as a turbomachine surrounded by the first movable cowling. Furthermore, in the closed position of the first cowling, at one axial end thereof, the turbomachine and the first cowling are preferably connected by an axial cowling retention device, preferably comprising a radially open groove provided on one of the two elements between the turbomachine and the first cowling, and a radial rib housed in the groove and provided on the other of these two elements.

[0026] Other advantages and features of the invention will appear in the detailed, non-limiting description below.

[0027] BRIEF DESCRIPTION OF THE DRAWINGS

[0028] This description will be made with reference to the attached drawings, among which are;

[0029] - [Fig. 1] represents a perspective view of an aircraft propulsion assembly, according to the invention;

[0030] - [Fig. 2] represents a perspective view of an assembly forming part of the propulsion assembly shown in Figure 1, the assembly being in the form of a preferred embodiment of the invention;

[0031] - [Fig. 3] represents a front view of the assembly shown in figure 2, with movable nacelle hoods in the closed position;

[0032] - [Fig- 4] represents a view similar to that of the previous figure, with the movable nacelle hoods in the open position;

[0033] - [Fig. 5] represents a schematic top view of the assembly shown in the previous figures;

[0034] - [Fig. 6] represents a rear view similar to that shown in figure 3, showing the forces acting on one of the nacelle hoods, at the junction with a second mounting device for this hood on the mast, this second mounting device being specific to the invention; - [Fig- 7] represents a cross-sectional view taken along line VII-VII of figure 6.

[0035] DETAILED EXPLANATION OF PREFERRED METHODS OF IMPLEMENTATION

[0036] With reference first to Figure 1, a propulsion assembly 100 for an aircraft is shown, comprising an aircraft turbomachine 101, a nacelle 102, and a mounting mast 104 for suspending the turbomachine 101, preferably under an aircraft wing (not shown). The turbomachine preferably corresponds to a twin-spool, turbofan engine, comprising, for example, an unfaired fan (not shown). However, it could be a turbomachine of another type, for example a turboprop, without departing from the scope of the invention.

[0037] The propulsion unit 100 and its turbojet engine 101 share the same longitudinal central axis 3. The nacelle 102 includes movable nacelle cowlings, such as fan cowlings and reversing cowlings, integrated into a thrust reversing system. These movable cowlings are hinged to the mounting mast 104. Their closed position corresponds to the position occupied during flight, while their open position corresponds to a maintenance position, allowing access to the turbojet engine and its equipment.

[0038] Figures 2 to 6 show an assembly 200 that forms an integral part of the propulsion unit 100. This assembly includes the mounting mast 104 and two movable nacelle cowlings 4a and 4b, for example, reversing cowlings arranged around the turbojet engine 101. These consist of a first movable cowling 4a and a second movable cowling 4b, each with a general half-shell shape facing each other. These two aerodynamic cowlings 4a and 4b, arranged symmetrically with respect to a median axial and vertical plane of the propulsion unit, thus exhibit a so-called "D-duct" or "C-duct" architecture, known by the Anglo-Saxon terms "D-duct" and "C-duct". In the "C-shaped" architecture, each cowling 4a, 4b delimits a secondary flow path of the propulsion system, radially outwards. In the "D-shaped" architecture, each cowling 4a, 4b also delimits this secondary flow path radially inwards.It is this latter configuration that is represented in the preferred embodiment shown in the figures, with several movable cowling skins radially delimiting a portion of the secondary duct 6, intended to be traversed by a secondary airflow corresponding to air from the fan of the turbofan engine. In the preferred embodiment of assembly 200, the two movable cowlings 4a, 4b are symmetrical, as are their mounting systems 6a, 6b on the mounting mast 104. Consequently, only the mounting system 6a of the first cowling 4a will be described in detail below, but it should be understood that the mounting system 6b of the second movable cowling 4b is identical or similar, being arranged symmetrically with respect to the mounting system 6a, always along the axial and vertical median plane of the propulsion assembly.Furthermore, in the figures, identical or similar elements of the hoods 4a, 4b and their mounting systems 6a, 6b have the same numerical references, followed by the extension "a" for those associated with the first hood 4a, and followed by the extension "b" for those associated with the second hood 4b.

[0039] The first movable cover 4a is therefore pivotally mounted on the mounting mast 104, along a cover articulation axis 8a parallel or substantially parallel to axis 3. This mounting is carried out at one of the circumferential free ends of the first movable cover 4a, which is shaped like a half-shell, and more precisely at the end located near the 12 o'clock position. The mounting, which is carried out using the system 6a specific to the invention and which will be detailed below, is performed on a support structure 105 belonging to the mounting mast, and which corresponds to the structural part of this mast, also called the "primary mounting mast structure". Within the mast 104, this support structure 105 is completed by an aerodynamic fairing 107 which covers it, this fairing also being called the "secondary mounting mast structure".

[0040] At its opposite circumferential end, the one located near the 6 o'clock position, the first hood 4a is equipped with a conventional locking device 10, for example, a hook and lever actuating device. This device 10 can be common to both hoods 4a and 4b in order to lock them in the closed position, one against the other. Alternatively, each hood 4a and 4b could be equipped with its own locking device, to cooperate with a structural part of the propulsion assembly, arranged in the 6 o'clock position.

[0041] The mounting system 6a comprises several mounting devices spaced apart along the hood's hinge axis 8a. Among these devices, several initial mounting devices 10a are provided, each forming a hinge centered on the hinge axis 8a. More precisely, each of these initial devices 10a defines a pivot joint, preferably a sliding pivot, with axes centered on the hood's hinge axis 8a. For example, two or three initial devices 10a are arranged successively along the hinge axis 8a, as shown in Figure 5. Upstream of these three initial mounting devices 10a, along a principal flow direction 5 through the propulsion assembly in direct thrust configuration, the system 8a is completed by a second mounting device 12a, specific to the present invention.

[0042] Indeed, the second mounting device 12a comprises a connecting rod 14a, which has a first connecting rod end mounted on the support structure 105 via a first mechanical linkage 15a, and a second connecting rod end opposite the first, mounted on the end of the first movable hood 4a via a second mechanical linkage 16a. Each of the two mechanical links 15a and 16a can also be a pivot joint, preferably a sliding pivot joint. The axis of the sliding pivot joint forming the first mechanical linkage 15a coincides with the axis of the first mounting devices 10a, and therefore coincides with the hood hinge axis 8a. The axis of the sliding pivot joint forming the second mechanical linkage 16a is parallel with the axis of the sliding pivot joint forming the first mechanical linkage 15a.Alternatively, the two mechanical links 15a, 16a could be formed by two ball joints, and a mixed solution between these two designs is also conceivable, with a sliding pivot joint and a ball joint to form the first and second mechanical links 15a, 16a, or vice versa.

[0043] Regardless of the form chosen, one of the distinctive features of the invention lies in the fact that the first mechanical link 15a is centered on the articulation axis of the hood 8a. The second end of the connecting rod, as well as the second mechanical link 16a which connects it to the movable hood 4a, are thus offset radially and / or transversely from the first mechanical link 15a, relative to the axis 3. The placement of the connecting rod 14a is therefore simpler and less subject to risks of kinematic interference with the elements 105, 107 of the mast 104.

[0044] To achieve this, at least part of the connecting rod 14a is housed within an internal space 18a in the first movable hood 4a. This space is radially delimited between the hood skins and opens circumferentially outwards at the hood's end to allow passage of the connecting rod, near the 12 o'clock position. This circumferentially open internal space 18a enables the connecting rod to move when the first movable hood 4a is moved between the open position shown in Figure 4 and the closed position shown in Figure 3, and vice versa. Indeed, when the hood 4a moves, the connecting rod 14a is set in motion without kinematic interference from either the mast 104 or the hood 4a, but rather by moving within the internal space 18a provided for this purpose in the radial thickness of the hood 4a.

[0045] More precisely, the space 18a is radially delimited between an inner cowl skin 17a and an outer cowl skin 19a. The inner cowl skin 17a radially delimits, outwards, with its radially internal surface, the secondary duct 6, while the outer cowl skin 19a has a radially external surface that forms part of an external aerodynamic surface 20a of the cowl, designed to be enveloped by air external to the propulsion assembly. At their extremities, the two skins 17a and 19a define a circumferential opening 21a in the inner space 18a; this opening 21a, at the end of the cowl, thus connects the interior of the space 18a with the exterior of the cowl in a circumferential direction.

[0046] The assembly is configured so that during the entire movement of the connecting rod observed during a displacement of the first movable cover 4a between its open position in Figure 4 and its closed position in Figure 3, and vice versa, this connecting rod moving within the internal space 18a passes only through the said circumferential opening 21a. Indeed, during the displacement of the cover 4a, the connecting rod 14a is set in motion without kinematic interference with the two skins 17a, 19a of the cover 4a which radially delimit the internal space 18a in which this connecting rod is housed.

[0047] The first movable hood 4a therefore has an external aerodynamic surface 20a of generally cylindrical shape, with an average diameter "Dm". In addition, the connecting rod 14a of the second mounting device 14a can have a significant length thanks to its specific arrangement of the invention, this connecting rod length "Lb" being, for example, on the order of 100 to 300 mm.

[0048] With more specific reference to Figure 6, which shows the cowling 4a in the closed position, it is noted that the second mechanical linkage 16a has a point of application 22a of a tensile force 24a from the connecting rod on the first movable cowling 4a. Locally, at this point of application 22a, a tangential direction 26a of the second cowling is defined, this direction being locally parallel to the tangent to the outer aerodynamic surface 20a of this cowling, in a cross-section of the propulsion assembly. It is along this tangential direction 26a that a locking force 28a is exerted on the cowling, at the point of application 22a. This locking force originates from the opposite end of the cowling 4a, where the locking device 10 is located.The two forces 24a and 28a acting at the point of application 22a form a salient angle opening radially towards the axis 3, so that the resultant 30a of the two forces 24a and 28a acting at this point 22a has a radial component oriented inwards. To achieve this, the connecting rod 14a extends from its second end to its first end, positioned radially inwards with respect to the tangential direction 26a.

[0049] With this orientation of the resultant force 30a, it is ensured that the cowling 4a is correctly pressed radially against the turbojet 101, and that an axial retaining device for the cowling 4a, relative to this turbojet, is properly maintained during operation. In this respect, in the closed position of the first cowling and at an upstream axial end thereof, the turbojet 101 and the first cowling 4a are indeed preferentially connected by an axial retaining device 32a of the cowling. Referring to Figure 7, such a device 32a preferably comprises a groove 34a open radially outwards and provided on a housing 110 of the turbojet 101, as well as a radial rib 36a housed in the groove 34a and provided on the cowling 4a. A reverse configuration is also possible, without departing from the scope of the invention.The resulting force 30a then facilitates the engagement of the rib 36a in the groove 34a, and maintains this engagement during operation. The groove 34a is preferably V-shaped, and the rib 36a has a complementary shape.

[0050] Such an axial retaining device 32a can also be implanted at the other axial end of the movable hood 4a, always in such a way as to ensure cooperation with the turbojet, and preferably with a casing of it.

[0051] Of course, various modifications can be made by a person skilled in the art to the invention just described, only by way of non-limiting examples, and the scope of which is defined by the attached claims.

Claims

DEMANDS 1. Assembly (200) for an aircraft propulsion unit (100), the assembly comprising a support structure (104), and a first movable cowl (4a) pivotally mounted at one end on the support structure, about a cowl hinge axis (8a), the first movable cowl being intended to be located around a turbomachine of the propulsion unit, the assembly comprising a mounting system (6a) for the first movable cowl (4a) on the support structure (104), the mounting system comprising several mounting devices (10a, 12a) spaced from each other about the cowl hinge axis, including a first mounting device (10a) forming a hinge centered on the hinge axis (8a), and a second mounting device (12a) comprising a connecting rod (14a) having a first connecting rod end mounted on the support structure (104) by means of a first mechanical linkage (15a),as well as a second connecting rod end opposite the first, and mounted on the first movable hood (4a) by means of a second mechanical linkage (16a), characterized in that the first mechanical linkage (15a) is centered on the hood's articulation axis (8a), and in that at least a portion of the connecting rod (14a) is housed in an internal space (18a) of the first movable hood (4a), a space in which the connecting rod (14a) is in motion during a movement of the first movable hood (4a) between an open position and a closed position, and vice versa, this internal space (18a) being radially delimited between hood skins, and opening circumferentially outwards at the end of the hood for the passage of the connecting rod (14a).

2. Assembly according to claim 1, characterized in that each of the first and second mechanical links (15a, 16a) is made in any one of the following forms: - a pivot joint, preferably a sliding pivot; - a kneecap.

3. An assembly according to any one of the preceding claims, characterized in that, at least in the closed position of the first movable cover (4a), the second mechanical linkage (16a) has a point of application (22a) of a force from the connecting rod (14a) on the first movable cover (4a), point of application (22a) at which a tangential direction (26a) of the first cover is defined, and in that the connecting rod (14a) extends from its second connecting rod end towards its first connecting rod end being located radially inwards with respect to said tangential direction (26a).

4. Assembly according to any one of the preceding claims, characterized in that the support structure (104) is a turbomachine attachment mast.

5. Assembly according to any one of the preceding claims, characterized in that the mounting system (6a) comprises several first mounting devices (10a) spaced from each other along the hood articulation axis (8a), each of the first devices (10a) forming a hinge centered on the articulation axis (8a), and the hinge defining a pivot joint, preferably a sliding pivot.

6. Assembly according to any one of the preceding claims, characterized in that the first hood (4a) has a general half-shell shape, one end of which is mounted on the support structure (104), and the other end of which is equipped with a locking device (10).

7. Assembly according to any one of the preceding claims, characterized in that it comprises a second movable hood (4b) mounted pivotally at one of its ends on the support structure (104), by a mounting system (6b) identical to the mounting system (6a) of the first movable hood (4a) on this support structure (104).

8. Aircraft propulsion assembly (100) comprising an assembly (200) according to any one of the preceding claims, as well as a turbomachine (101) surrounded by the first movable cowl (4a), and in that, in the closed position of the first cowl, at an axial end thereof, the turbomachine (101) and the first cowl (4a) are preferably connected by an axial cowl retaining device (32a), preferably comprising a radially open groove (34a) provided on one of the two elements between the turbomachine (101) and the first cowl (4a), as well as a radial rib (36a) housed in the groove (34a) and provided on the other of these two elements (101, 4a).

Images