Assembly for aircraft turbine engine comprising an improved device for attaching a gas-ejection cone

Abstract

The invention relates to an assembly for an aircraft turbine engine, comprising a first turbine engine part (54) and a second turbine engine part (56) located downstream of the first part, the first and second parts (54, 56) being centred on a longitudinal axis (3), the second part (56) corresponding to all or part of a gas-ejection cone for a turbine engine, the assembly including a device (58) for attaching the first part to the second part. According to the invention, the attachment device (58) is configured so as to allow the first and second turbine engine parts (54, 56) to pass from a position in which they are not axially coupled to one another, to a position in which they are axially coupled, by rotating relative to one another about the longitudinal axis (3).

Description

[0001] 44323 AP

[0002] 1

[0003] DESCRIPTION

[0004] TITLE: AIRCRAFT TURBOMACHINE ASSEMBLY COMPRISING AN IMPROVED DEVICE FOR ATTACHING AN EJECTION CONE

[0005] TECHNICAL FIELD

[0006] The invention relates to the field of aircraft turbomachinery, and more specifically to the mounting of a gas ejection cone within a turbomachine.

[0007] The invention applies in particular to turbojets, and even more particularly to twin-spool, twin-flow turbojets.

[0008] STATE OF PRIOR ART

[0009] In the prior art, it is known to install a gas ejection cone at the rear of an aircraft turbomachine. This cone corresponds to an exhaust system, also known by the English term "plug." Such a cone has a general shape of revolution, with its rear portion having a cross-section that decreases towards the tail, hence its name "cone."

[0010] The exhaust cone is usually mounted on a structural part of the turbomachine, such as the turbine's rear casing. Its mounting must be reversible, allowing it to be removed and providing access to the inside of the turbomachine, particularly for maintenance operations.

[0011] In addition, the cone can be made in two separate pieces, arranged axially in continuity with each other. These two pieces are then mounted one on top of the other, using a fastening device.

[0012] Whether for mounting the cone onto the turbomachine or for mounting one of the two cone parts onto the other, a fastening device in the form of an annular row of bolts is generally used. The bolts, provided in a very large number, then pass through two mounting flanges respectively located on the two parts, in order to secure them together.

[0013] While this annular row of bolts is mechanically sound, it can still be improved. Firstly, it results in particularly long and therefore costly assembly and disassembly times. Costs are also affected by the fact that such an assembly typically requires at least two operators: one to hold the gas ejection cone in place, and the other to assemble the bolts. 44323 AP

[0014] 2

[0015] The high number of bolts also increases the mass of this part of the turbomachine, and therefore fuel consumption. This increase is exacerbated by the fact that these bolts, in addition to being unsightly, generate aerodynamic losses at the outer surface of the exhaust cone.

[0016] DESCRIPTION OF THE INVENTION

[0017] To address the aforementioned drawbacks relating to prior achievements, the invention first of all relates to an assembly for an aircraft turbomachine, according to the characteristics of claim 1.

[0018] The invention thus breaks with the same technology used for decades for mounting the gas ejection cone, by providing axial coupling by simple relative rotation of the parts concerned, over a small angular range, around the longitudinal axis of the turbomachine.

[0019] This solution is advantageous because it is reliable, easy and quick to implement, and inexpensive. In particular, it does not require multiple operators. Due to the elimination or drastic reduction of bolts or similar components, it also generates less aerodynamic drag and less mass. The invention therefore represents a result of technological research aimed at significantly improving aircraft performance and, in this respect, contributes to reducing the environmental impact of these aircraft (decarbonization).

[0020] The invention also has at least one of the following optional features, taken individually or in combination.

[0021] Preferably, the assembly includes at least one locking device for the first and second turbomachine parts in their axial coupling position. Each locking device is arranged to prevent the second part from rotating relative to the first part along its longitudinal axis. Each locking device is preferably a screw. Naturally, the number of these locking devices can be significantly reduced compared to the number of bolts used in conventional prior art solutions. For example, the number of these locking devices can be reduced to between three and six, for instance, four devices arranged at 90° to each other.

[0022] Preferably, the assembly is configured so that each locking member is mounted on the assembly from the outside, each locking member preferably having an orientation with a non-zero radial component, and even more preferably a radial, or substantially radial, or orthogonal, or 44323 AP orientation.

[0023] 3 substantially orthogonal locally to an aerodynamic surface defined externally by the first part and / or the second part of turbomachine.

[0024] According to a first configuration, the second turbomachine part is a second part of the gas ejection cone, and the first turbomachine part is a first part of the gas ejection cone, arranged upstream of the second part.

[0025] In a second configuration, the second turbomachine component forms the entire exhaust cone, and the first turbomachine component is a turbomachine housing, preferably a rear turbine housing. However, in this second configuration, the second turbomachine component, which forms the entire exhaust cone, can itself be made of several parts.

[0026] Preferably, the first axial stop members project radially inwards, and the second axial stop members project radially outwards. However, a reverse configuration could be adopted without departing from the scope of the invention.

[0027] Preferably, the first fixing flange includes, associated with one of the first axial openings, an opening bottom forming an axial stop for one of the second axial stop elements, when bringing the first and second parts into their axially uncoupled position.

[0028] Preferably, the first and second fixing flanges have circumferential stop means, configured to stop the relative rotation between the first and second parts, when bringing these parts into their axial coupling position.

[0029] The invention also relates to an aircraft turbomachine, comprising an assembly as described above. Preferably, this is a turbojet engine, and even more preferably a twin-spool, twin-flow turbojet engine. However, other types of turbomachines, such as turboprop engines, remain conceivable without departing from the scope of the invention.

[0030] Finally, the invention relates to a method of assembling such an assembly for an aircraft turbomachine, the method comprising a step of moving the first and second parts from their position not axially coupled to each other, to their axially coupled position, by rotating one relative to the other along the longitudinal axis.

[0031] Other advantages and features of the invention will appear in the detailed, non-limiting description below.

[0032] BRIEF DESCRIPTION OF THE DRAWINGS

[0033] This description will be made with reference to the attached drawings, among which are;

[0034] [Fig. 1] shows a schematic longitudinal cross-sectional view of a turbojet engine according to the invention; 44323 AP

[0035] [Fig. 2] represents a schematic perspective view of the turbojet engine shown in figure 1, equipped with its nacelle;

[0036] [Fig. 3] represents an enlarged perspective view of two component parts of a gas ejection cone equipping the turbojet shown in the previous figure, the two parts being in an unassembled position;

[0037] [Fig. 4] represents an enlarged perspective view of the fixing flange equipping one of the two parts shown in the previous figure, called the second part;

[0038] [Fig. 5] represents a cross-sectional view taken along plane PI of figure 4;

[0039] [Fig. 6] represents a cross-sectional view taken along plane P2 of figure 4;

[0040] [Fig. 7] represents an enlarged perspective view of the fixing flange equipping the other of the two parts shown in figure 3, called the first part, cut in a plane P3 of figure 3;

[0041] [Fig. 8] represents a view similar to the previous one, with the fixing flange shown cut in a plane P4 of figure 3;

[0042] [Fig. 9]

[0043] [Fig. 10]

[0044] [Fig. 11] are perspective views schematically illustrating a first step in assembling the second cone piece onto the first cone piece;

[0045] [Fig. 12] represents a cross-sectional view taken along plane P5 of figure 11;

[0046] [Fig. 13] represents a cross-sectional view taken along plane P6 of figure 11;

[0047] [Fig. 14]

[0048] [Fig. 15] are perspective views schematically illustrating a second stage of mounting the second cone piece onto the first cone piece;

[0049] [Fig. 16] represents a perspective view cut along plane P7 of figure 15;

[0050] [Fig. 17] represents a perspective view cut along plane P8 of figure 15;

[0051] [Fig. 18] is a cross-sectional view schematically illustrating a third step in assembling the second cone piece onto the first cone piece;

[0052] [Fig. 19] is a perspective view schematically illustrating the third step of mounting the second cone piece onto the first cone piece.

[0053] DETAILED EXPLANATION OF PREFERRED METHODS OF IMPLEMENTATION

[0054] With reference first to Figure 1, an aircraft turbomachine 1, according to the invention, is shown. This is a twin-spool, turbofan engine. However, it could be a turbomachine of another type, for example a turboprop, without departing from the scope of the invention. 44323 AP

[0055] 5

[0056] The turbojet 1 has a longitudinal axis 3, around which its various components extend. It comprises, from upstream to downstream along a main direction 5 of gas flow through this turbomachine, a fan 2, a low-pressure compressor 4, a high-pressure compressor 6, a combustion chamber 8, a high-pressure turbine 10 and a low-pressure turbine 12.

[0057] In a conventional manner, these elements define a primary channel 14a through which a primary flow 16a circulates, and a secondary channel 14b through which a secondary flow 16b circulates. In this dual-flow design, an intermediate casing 20 is arranged downstream of the blower 2. The intermediate casing comprises a hub 22, radial arms 24, and an external ferrule 26 extending downstream from a blower casing.

[0058] Here, the high-pressure turbine 10 and the high-pressure compressor 6 are connected by a high-pressure shaft 30, while the low-pressure turbine 12 and the low-pressure compressor 4 are connected by a low-pressure shaft 32, preferably passing through the high-pressure shaft 30. A rotating blower shaft 34 is also provided, driving the blower blades in rotation around the axis 3, on which the three shafts 30, 32, 34 are centered.

[0059] In the configuration shown, the blower shaft 34 is driven by means of a reducer 36, which is itself driven by the low-pressure shaft 32. However, driving the blower directly by the low-pressure body remains possible, without departing from the scope of the invention.

[0060] At the rear of the turbojet engine, the low-pressure turbine 12 typically comprises one or more stages, each stage including a bladed rotor wheel and a bladed stator wheel, also known as a turbine distributor. These wheels are arranged axially in alternating positions. At the rear of the last bladed wheel of the last stage of this low-pressure turbine 12, a stator structure is provided, formed by a fixed turbine casing 44, corresponding to a rear turbine casing, or TRF casing. This turbine casing 44 includes a bladed fixed wheel, which is located axially opposite the last bladed turbine wheel.

[0061] A gas ejection cone 50, forming an exhaust structure for the turbojet, is preferably mounted on this rear turbine casing 44. Around an upstream portion of this cone 50, another annular aerodynamic structure 52 is provided, designed to separate the primary flow 14a from the secondary flow 14b in the radial direction. This aerodynamic structure 52 forms part of a nacelle 51 equipping the turbojet, as schematically shown in Figure 2. 44323 AP

[0062] 6

[0063] Downstream of this other aerodynamic structure 52, the gas ejection cone 50 is no longer radially covered, and its outer surface is intended to be embraced by a mixture of the primary flow 16a and the secondary flow 16b.

[0064] In Figure 1, the cone 50 is formed by assembling a first part 54 with a second part 56 arranged in axial continuity with the first part, downstream of it. A fastening device 58 enables such an assembly between the two parts 54, 56, and its design specific to the present invention will be detailed below.

[0065] The axial extent of the first part 54 is identical or substantially identical to the axial extent of the aerodynamic structure 52 that surrounds it. Annular in shape and centered on axis 3, the first part 54 may be cylindrical or flare slightly downstream. The second part 56, on the other hand, is conical or frustoconical in shape, also centered on axis 3, with a cross-section that narrows downstream. In this respect, it is noted that each of the two parts 54 and 56 extends centered around axis 3, preferably in a closed 360° configuration. However, this angular extent may be less than 360° for one or both parts, for example, to allow the passage of other elements, such as the mast, and thus present a non-closed, or open, configuration.Furthermore, regardless of the angular extent of each of these two parts 54, 56, they can each be made in one piece, or obtained by assembling several angular sectors of a part placed end-to-end. Moreover, if the preferred solution provides that the axis 3 on which parts 54, 56 are centered corresponds to the longitudinal axis of the turbojet engine, these parts could nevertheless be centered on an axis other than this longitudinal axis of the turbojet engine, for example, an axis intersecting this longitudinal axis of the turbojet engine. Furthermore, while both remaining arranged around the same axis, the two parts 54, 56 could be centered respectively on two distinct axes, preferably two intersecting axes, one of which would preferably be the longitudinal axis of the turbojet engine.

[0066] The cone 50 is attached to the housing 44 by means of a fastening device 58, via the upstream end of the first part 54. The fastening device 58, which secures the assembly between the two parts 54 and 56, will be described hereafter. However, it is understood that this design can also be adopted for the fastening device securing the connection between the cone 50 and the rear turbine housing 44, the latter then forming the first part within the meaning of the present invention. When this latter embodiment is implemented, the cone 50 may have a two-piece design as described above, or be made of a single piece.

[0067] In the case described below with the cone 50 made by assembling the first and second parts 54, 56, forming respectively a first and a second part of the cone 50, the 44323 AP

[0068] 7. Mounting this component onto the housing 44 can be achieved by a conventional, ring-row bolt connection. To perform maintenance operations inside the turbojet engine, access can be provided by simply removing the second cone piece 56, via the quick disassembly of the fastening device 58 between the two pieces 54, 56.

[0069] With reference now to figures 3 to 18, a first preferred embodiment of the invention will be described, in which the fastening device 58 comprises a first fastening flange 64 belonging to the first part 54, and a second fastening flange 66 cooperating with the first fastening flange 64, and belonging to the second part 56. The two fastening flanges 64, 66 are annular, centered on the axis 3.

[0070] With reference first to figures 3 to 8, the two fixing flanges 64, 66 of the fixing device 58 will be described, in an unassembled position of the two parts 54, 56, forming an assembly 55 specific to the invention.

[0071] The first flange 64 comprises, alternately along a circumferential direction of the assembly relative to axis 3, first axial openings 68 and first axial stop elements 70 projecting radially inwards. Similarly, the second flange 66 comprises, alternately along this same circumferential direction, second axial openings 78 and second axial stop elements 80 projecting radially outwards. The angular range of each of these elements 68, 70, 78, 80 is preferably identical or similar, for example, on the order of 15 to 30°.

[0072] The first mounting flange 64 has, associated with each first axial opening 68, an opening base 72, which obstructs its corresponding opening 68 axially upstream. As will be detailed below, the opening base 72, projecting radially inwards, constitutes an axial stop for one of the second axial stop members 80, when the first and second parts 54, 56 are brought into their uncoupled axial position. It is noted that each opening bottom 72 is therefore circumferentially located between two first axial stop members 70, being arranged upstream of these two members 70, with an axial offset substantially equal to the axial thickness of the second axial stop members 80. Each opening bottom 72 can be in the form of a tongue extending circumferentially, over all or part of the angular extent of the first axial opening 68 which it obstructs upstream.

[0073] Furthermore, each second axial stop member 80 also takes the form of a circumferential tongue projecting radially outwards from an upstream axial end of a flange 74 of the second mounting flange 66. The flange 74 and each stop member 80 thus form a hook, designed to cooperate with a first stop member 70. 44323 AP

[0074] 8

[0075] At one of its circumferential ends, each stop member 80 defines a circumferential opening 76 with the base 74, as can be seen in Figure 4. At the opposite circumferential end, the second stop member 80 is connected to an axial edge 82, which runs axially along the base 74, downstream. The radial height of the second stop member 80 is preferably identical or substantially identical to the radial height of this axial edge 82. The distinctive feature of this edge is that it forms part of the circumferential stop means, configured to prevent the relative rotation between the first and second parts 54, 56, when these parts are brought into their axial coupling position, as will be described later.

[0076] With reference now more specifically to figures 9 to 13, a first step of a method of assembling the assembly 55 is shown, consisting of bringing the first and second cone pieces 54, 56 from the unassembled position shown in figure 3, to a position of engagement between these pieces, but not yet axially coupled to each other.

[0077] To do this, the two cone pieces 54, 56 are arranged coaxially, at a distance from each other, and then brought together axially so as to insert the first stop members 70 into the second axial openings 78, and so as to insert the second stop members 80 into the first axial openings 68. The relative axial displacement is stopped by the contact of the second stop members 80 with the corresponding opening bottoms 72, as is best seen in figure 12.

[0078] This first step can be carried out manually by a single operator. Once the two parts 54, 56 are in their engagement position, but not axially coupled to each other, they are temporarily held relative to each other by means of the radial guidance provided by the cooperation between the elements 68, 70, 78, 80.

[0079] A second step in the process involves moving the first and second parts 54, 56 from their uncoupled axial position to an axially coupled position by rotating the two parts relative to each other along the longitudinal axis 3. This second step is illustrated schematically in Figures 14 to 17. The initiation of this relative rotation causes each second axial stop 80 to position itself upstream of the first axial stop 70 that is directly adjacent to it in the direction of rotation. In other words, this first stop 70 enters circumferentially into the circumferential opening 76 described with reference to Figure 4, and this leads to the axial cooperation of the stop 70, 80 in pairs.The rotation is stopped when the axial edge 82, also described with reference to Figure 4, comes into circumferential contact against one end of the first stop member 70, thus forming a complementary part of the aforementioned circumferential stop means. 44323 AP.

[0080] 9

[0081] At this stage, the two parts 54 and 56 are axially coupled in such a way as to allow the mechanical forces to be transferred in the axial direction, in the radial direction, and also in a first direction of the circumferential direction. This results in particular from the hooks formed by the first axial thrust bearing elements 80, which radially curve inwards around the first axial thrust bearing elements 70, the latter fitting with a small radial clearance inside these same hooks.

[0082] The extent of rotation of the two parts relative to each other, to move from the uncoupled axial position to the axially coupled position, remains advantageously small thanks to the design of the invention. For example, it is less than 30°.

[0083] In order to lock the fastening device 58 in the axial coupling position of the two parts 54, 56, and thus prevent their relative movement in the second direction of the circumferential direction, the method includes a third locking step in position, shown schematically in figures 18 and 19. For this purpose, locking members 84 are mounted on the parts 54, 56, these members 84 preferably taking the form of screws. Indeed, each screw 84 is mounted radially from the outside of the assembly 55, so as to pass through the two flanges 64, 66. More precisely, each locking screw 84 passes through a through hole of one of the first axial stop members 70, as well as a through hole located in continuity with the previous one, and passing through the base 74 of the second fixing flange 66. This may include a nut 86, for example mounted floating on the base 74, into which the screw 84 is screwed.Alternatively, it may be a set screw, not requiring a nut to achieve the desired effect, namely locking the second part 56 in rotation, relative to the first part 54, along the longitudinal axis 3.

[0084] The installation of these screws 84 can thus be carried out blindly from outside the gas ejection cone. Furthermore, since the circumferential forces resisted by these screws 84 remain low, their number can be significantly reduced compared to conventional solutions with two simply bolted flanges. For example, this number can be reduced to between three and six, for instance, four screws 84 arranged at 90° to each other. To limit aerodynamic losses at the outer surface of the cone, the head of each of these locking screws is housed in a counterbore 88 of the first flange 64.

[0085] In this first preferred embodiment, each locking screw 84 preferentially has a radial, or substantially radial, orientation, although other orientations remain conceivable, preferably always with a non-zero radial component.

[0086] Of course, various modifications can be made by a person skilled in the art to the invention just described, by way of non-limiting examples only. Furthermore, all 44323 AP

[0087] The 10 features disclosed above, in the various preferred embodiments and their alternatives, are combinable. Furthermore, it should be noted that in all the figures described above, elements bearing the same numerical references correspond to identical or similar elements.

Claims

44323 AP 11 DEMANDS 1. Aircraft turbomachine assembly (55), comprising a first turbomachine component (54) and a second turbomachine component (56) located downstream of the first component, the first and second components (54, 56) extending about a longitudinal axis (3), the second component (56) corresponding to all or part of a turbomachine exhaust cone (50), the assembly comprising a fastening device (58) for the first component on the second component, characterized in that the fastening device (58) is configured to allow the first and second turbomachine components (54, 56) to move from a position uncoupled axially to a position of axial coupling by rotation of one relative to the other about the longitudinal axis (3), the fastening device (58) comprising a first fastening flange (64) belonging to the first component (54), and a second fastening flange (66) cooperating with the first fixing flange,and belonging to the second part (56), the first flange (64) comprising, alternately in a circumferential direction of the assembly, first axial openings (68), and first axial stop members (70) projecting radially, the second flange (66) comprising, alternately in the circumferential direction of the assembly, second axial openings (78), and second axial stop members (80) projecting radially, the fastening device (58) being configured so as to first bring the first and second parts into their uncoupled axial position, by inserting the first stop members (70) into the second axial openings (78) and by inserting the second stop members (80) into the first axial openings (68), then to bring the first and second parts into their axially coupled position, by rotating one relative to the other about the longitudinal axis (3),leading the first and second axial thrust bearings (70, 80) to cooperate with each other.

2. Assembly according to claim 1, characterized in that it comprises at least one locking member (84) of the first and second turbomachine parts (54, 56) in their axial coupling position, each locking member (84) being arranged so as to lock the second part (56) in rotation, relative to the first part (54), along the longitudinal axis (3), each locking member preferably being a screw.

3. Assembly according to any one of the preceding claims, characterized in that the second turbomachine part (56) is a second part of the gas ejection cone, and in that the first turbomachine part (54) is a first part of the gas ejection cone (50), arranged upstream of the second part. 44323 AP 12 4. An assembly according to any one of claims 1 and 2, characterized in that the second turbomachine part (56) forms the entire exhaust cone, and in that the first turbomachine part is a turbomachine housing (44), preferably a rear turbine housing.

5. A method for assembling an aircraft turbomachine assembly (55) according to any one of the preceding claims, comprising a step of moving the first and second parts (54, 56) from their uncoupled position to their axially coupled position by rotating one relative to the other about the longitudinal axis (3).

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