TURBOMACHINE COMPRISING SEVERAL MODULES AND A DEVICE FOR LOCKING THESE MODULES, AND CORRESPONDING ASSEMBLY METHOD

Abstract

The invention relates to an aircraft turbomachine comprising: - a first module comprising a BP compressor shaft (15) including internal splines (49), - a second module comprising a BP turbine shaft (17) including first external splines (50) configured to engage with the internal splines (49) of the BP compressor shaft, and - a locking device (50) configured to axially immobilize the BP turbine shaft relative to the BP compressor shaft. The BP turbine shaft (17) has an annular shoulder (72): - extending radially outwards and arranged upstream of the first external splines (50) forming an axial stop for the first module, - having an external diameter equal to that of the BP turbine shaft at the first external splines, and - comprising second external splines (82) shaped to allow passage of the internal splines of the BP compressor shaft.Figure for the abbreviation: Figure 4.

Description

Title of the invention: TURBOMACHINE COMPRISING SEVERAL MODULES AND A DEVICE FOR LOCKING THESE MODULES, AND CORRESPONDING ASSEMBLY METHOD technical field

[0001] The present invention relates to solutions for facilitating the modularity of an aircraft turbomachine. Previous technique

[0002] An aircraft turbomachine is often manufactured as an assembly of modules, each of which may include fixed and moving parts. A module is defined as a subset of an engine whose geometric characteristics at its interfaces with adjacent modules are sufficiently precise to allow for individual delivery, and which has undergone separate balancing when it includes rotating parts. Assembling the modules makes it possible to create a complete engine, minimizing the balancing and matching operations of the interfacing parts.

[0003] The modularity of a turbomachine is a key element for its maintenance. Indeed, during maintenance, the parts must be easily accessible without having to dismantle a large number of engine components. In practice, the aim is to achieve a division into a few major and minor modules. For example, for a turbomachine with an upstream fan (the terms "upstream" and "downstream" are defined in relation to the gas flow within the turbomachine), it is configured with three major modules: an upstream major module for the front section comprising the fan, an intermediate major module for the middle section comprising the low-pressure compressor and the high-pressure casing, and a downstream major module for the rear section comprising the low-pressure turbine and the low-pressure shaft. In this specific example, the low-pressure casing is divided into two modules.It is possible that the low-pressure unit could also be divided into three modules, with the low-pressure compressor arranged independently of the rest of the main intermediate module.

[0004] Generally, the intermediate major module and the downstream major module, including the low-pressure body components, are fixed to each other by means of a nut centered on the turbomachine axis, which serves to axially tighten the low-pressure compressor shaft and the low-pressure turbine shaft. During a During maintenance operations, this nut must be unscrewed using a tool that is inserted into the turbomachine along its longitudinal axis, and therefore inside the low-pressure shaft.

[0005] This maintenance is particularly difficult on a turbomachine comprising a gearbox in the upstream or forward section and possibly a blade pitch change system upstream. The problem in this case is access to the nut. The gearbox is located upstream of the nut and must be partially disassembled to access it. Furthermore, access to the nut is achieved with complex tools from the upstream side of the turbomachine to avoid excessive length and to ensure an acceptable diameter.

[0006] The tools are inserted through the internal planetary gear of the speed reducer, which, however, generally has an internal diameter smaller than the diameter of the nut (for example, on the order of 60 mm). Indeed, it is generally not possible to disassemble the speed reducer without disassembling a large part of the turbomachine, including the main downstream module.

[0007] This implies, firstly, that the access diameter of the tools is smaller than that of the nut and, secondly, that the nut is captive within the turbomachine. Increasing the internal diameter of the internal planetary gear to be greater than that of the nut and allowing the nut to be removed would negatively impact the size of the gearbox and the overall performance of the turbomachine.

[0008] Furthermore, the tools can present risks of mishandling and damage to certain turbomachine components located near the nut. In addition, the nut also requires a high tightening torque (on the order of 2000 Nm). With such torque, a long, small-diameter wrench has the disadvantage of a high angle of rotation and consequently poor accuracy in finding the exact angular position needed to access the nut, all while operating blindly.

[0009] In order to improve their propulsive efficiency, turbomachinery tends towards increased bypass ratios, which generally results in an increase in the size of the fan (diameter and axial dimension). This makes access to the low-pressure shaft nut even more complex due to the lengthening of the tool required to access it.

[0010] Moreover, some turbomachines, such as the case of unducted single fan turbomachines (also called USF, acronym for Unducted Single Fan), have a particularly large length and the modules of the high pressure and low pressure bodies have very small internal diameters, which complicates or even makes impossible access to the nut by the tool.

[0011] The present invention proposes a solution to at least some of the problems mentioned above which simplifies the modularity of an aircraft turbomachine and which does not penalize the efficiency of the turbomachine. Summary of the invention

[0012] To this end, the invention relates to an aircraft turbomachine, the turbomachine having a longitudinal axis and comprising: - a first module comprising a low-pressure compressor and a low-pressure compressor shaft which is centered on the longitudinal axis and includes internal splines, - a second module comprising a low-pressure turbine and a low-pressure turbine shaft which is centered on the longitudinal axis and includes first external splines configured to engage with the internal splines of the low-pressure compressor shaft, the low-pressure turbine shaft comprising a downstream end connected to a rotor of the low-pressure turbine and an upstream end connected to a rotor of the low-pressure compressor, and - a locking device configured to axially immobilize the low-pressure turbine shaft of the second module relative to the low-pressure compressor shaft of the first module. According to the invention, the low-pressure turbine shaft has an annular shoulder extending radially outwards and arranged upstream of the first external splines forming an axial stop for the first module, the annular shoulder has an external diameter equal to that of the low-pressure turbine shaft at the first external splines and the annular shoulder includes second external splines shaped to allow passage of the internal splines of the low-pressure compressor shaft.

[0013] Thus, this solution makes it possible to achieve the aforementioned objective. Indeed, the invention makes it possible to optimize the geometry of the low-pressure shaft, and in particular the geometry along the radial direction which generally constrains the radial position of the nut.

[0014] This optimized geometry makes it possible to increase the radius of implantation of the nut allowing the coupling between the low pressure compressor shaft and the low pressure turbine shaft compared to the prior art.

[0015] This configuration provides increased modularity. The arrangement of the locking device allows for effective immobilization between the modules. The low-pressure turbine and low-pressure compressor modules can thus be disassembled in fewer operations compared to other modules, and without disassembling the other adjacent modules.

[0016] This modularity is part of an approach to reducing environmental impact since it allows only the necessary components to be repaired and controlled and reduces the downtime of the turbomachine.

[0017] The turbomachine according to the invention may comprise one or more of the following features, taken individually or in combination with each other in all technically possible combinations: - the low pressure turbine shaft has an annular projection extending radially outwards forming the annular shoulder; - the low pressure compressor shaft includes an annular projection radially inwards, the annular projection of the low pressure compressor including a downstream face bearing against an upstream face of the annular shoulder of the low pressure turbine shaft; - the turbomachine includes an annular adjusting shim, arranged axially between the first module and the annular shoulder of the low pressure turbine shaft, the adjusting shim having an outside diameter equal to that of the low pressure turbine shaft at the first external splines and being shaped to allow passage of the internal splines of the low pressure compressor shaft; - the adjusting shim is arranged between the annular projection of the low pressure compressor shaft and the annular shoulder of the low pressure turbine shaft; - the adjustment shim includes external grooves shaped to allow passage of the internal splines of the low pressure compressor shaft; - each external groove of the adjustment wedge has a fluted shape; - each external groove of the adjustment wedge has a crenellated shape; - the locking device includes a nut centered on the longitudinal axis and screwed onto a thread of the low pressure turbine shaft, the nut being supported against an annular projection of the first module; - The upstream end of the low-pressure turbine shaft extends inside the low-pressure compressor shaft, the nut being mounted inside the low-pressure compressor shaft which includes the annular projection of the first module. Brief description of the drawings

[0018] The present invention will be better understood and other details, features and advantages of the present invention will become more apparent upon reading the following description of a non-limiting example, with reference to the accompanying drawings in which: - [Fig.1] is a schematic half-view in axial section of an aircraft turbomachine; - [Fig.2] is a schematic enlarged cross-sectional view of the turbomachine of [Fig.1] at the connection between a low-pressure compressor shaft and a low-pressure turbine shaft according to the prior art of the invention; - [Fig.3] represents a schematic view of the forces dimensioning the connection between the low pressure compressor shaft and the low pressure turbine shaft according to the prior art of the invention; - [Fig.4] is a schematic enlarged perspective and axial section view of the turbomachine of [Fig.1] at the connection between the low pressure compressor shaft and a low pressure turbine shaft according to the prior art of the invention; - [Fig.5] is a schematic enlarged axial cross-section view of the connection illustrated in [Fig.4]; - [Fig.6] is a schematic enlarged perspective and axial section view of the turbomachine of [Fig.1] at the connection between a low pressure compressor shaft and a low pressure turbine shaft according to the invention; - [Fig.7] is a schematic enlarged axial cross-section view of the connection illustrated in [Fig.6]; - [Fig.8] is a schematic cross-sectional view of the assembly process of the link in [Fig.7] illustrating a step in the installation of the low-pressure turbine shaft; - [Fig.9] is a view similar to [Fig.8] representing a step of insertion of the optimized adjustment shim and angular alignment with the splines of the low pressure turbine shaft; - [Fig. 10] is a view similar to [Fig. 8] representing a step in the installation of the low pressure compressor shaft up to engagement with the low pressure turbine shaft; - [Fig. 11] is a view similar to [Fig. 8] representing a step of butting the low pressure compressor shaft against the adjusting wedge; - [Fig. 12] is a view similar to [Fig. 8] illustrating a tightening step of a nut of an axial locking device of the low pressure compressor shaft; - [Fig. 13] is a view similar to [Fig. 8] representing a step in the installation of a nut and an anti-rotation system for the nut.

[0019] Elements having the same functions in the different implementations have the same references in the figures.

[0020] In the figures, the scales and proportions are not strictly respected for the purposes of illustration and clarity.

[0021] In the description, the expressions "internal" or "inside" and "external" or "outside" are used by way of non-limiting reference to the radial distance from the longitudinal axis around which the turbomachine extends, the expression "Internal" defines a zone radially closer to the longitudinal axis of the nacelle, as opposed to the term "external". Furthermore, in the description and claims, the terminology axial, radial, and transverse will be adopted without limitation, referring to the trihedral axis A, R, T shown in the figures, with the axial axis A being parallel to the longitudinal axis of the turbomachine. Description of the implementation methods

[0022] Reference is first made to [Fig. 1] which illustrates an aircraft turbomachine which is here a single fan unfaired turbomachine 1 (USF) although aspects of the invention are not limited to this particular type of turbomachine.

[0023] The turbomachine has a longitudinal axis, denoted C, which is generally the axis of rotation of its rotors, around which its various components extend. It comprises, from upstream to downstream: a fan 2, a low-pressure compressor 4, a high-pressure compressor 5, an annular combustion chamber 6, a high-pressure turbine 7, and a low-pressure turbine 8.

[0024] In the present invention, and generally, the terms "upstream" and "downstream" are defined with respect to a main direction F of fluid flow inside the turbomachine, and here along the longitudinal axis C, i.e. from left to right with reference to [Fig.1].

[0025] The low pressure compressor 4 and the low pressure turbine 8 are mechanically connected by a low pressure shaft 9 so as to form a low pressure body. The high-pressure compressor 5 and the high-pressure turbine 7 are mechanically connected by a high-pressure shaft 10 so as to form a high-pressure body.

[0026] The turbomachine 1 is modular and comprises several modules assembled / connected to each other, which facilitate its maintenance. Shafts and / or interfaces are used to make these connections.

[0027] A first module 14 includes the low-pressure compressor 4 and a low-pressure compressor shaft 15.

[0028] A second module 16 comprises the low-pressure turbine 8 and a low-pressure turbine shaft 17 which is centered on the longitudinal axis C. The low-pressure turbine shaft 17 advantageously comprises an upstream end 17a connected to a rotor of the low-pressure compressor 4, and in particular to the low-pressure compressor shaft 15, and a downstream end connected to a low-pressure turbine rotor 8. In operation, the low-pressure compressor shaft 15 is rotationally fixed to the low-pressure turbine shaft 17 to form the low-pressure shaft 9.

[0029] A third module 18, or high-pressure or HP module, comprises the high-pressure compressor 5 and the high-pressure turbine 7, whose rotors are connected by the high-pressure shaft 10 and form the high-pressure body. The third module 18 also comprises the annular combustion chamber 6, which is axially interposed between the high-pressure compressor 5 and the high-pressure turbine 7.

[0030] The turbomachine further comprises an upstream module 11 which includes the fan 2 and a speed reducer 3. The latter includes an input shaft which is centered on the longitudinal axis C. The input shaft is part of the upstream module 11. The fan 2 includes a fan shaft 13 which is driven in rotation by the low-pressure shaft 9 via the speed reducer 3. The upstream module 11 is mounted upstream of the first module 14.

[0031] The low-pressure compressor shaft 15 and the input shaft are both advantageously hollow. The low-pressure shaft 9 is also hollow.

[0032] The low pressure shaft 9 extends at least partly inside the high pressure shaft 10 and they are coaxial.

[0033] According to this configuration, the low-pressure or LP body of the turbomachine 1 is divided into three modules. Alternatively, the low-pressure body is divided into two modules, with the low-pressure compressor 4 forming part of the first module 14.

[0034] The turbomachine 1 is indeed equipped with a speed reducer 3 (known by the English acronym RGB) which advantageously comprises an epicyclic gear train. Of course, the speed reducer could comprise a planetary gear train. An epicyclic gear reducer classically comprises a sun gear (or inner planet gear), a plurality of planet gears (which are pinions), a planet carrier, and an outer ring gear (or outer planet gear). The sun gear is centered on the longitudinal axis C. The outer ring gear is centered on the longitudinal axis C and extends around the sun gear. The planet gears are arranged between the sun gear and the outer ring gear and are carried by the planet carrier. Each planet gear is mounted to rotate freely about a planet gear axis by means of a bearing and meshes with external teeth of the sun gear and internal teeth of the outer ring gear.

[0035] In the present case, the outer ring is stationary and fixed to a stator of the turbomachine, which is here an inlet housing 24. The solar element is free to rotate and coupled to the input shaft, which itself is connected to the low-pressure shaft 9. The planet carrier is also free to rotate and coupled to the fan shaft 13. The fan 2 is therefore driven in rotation by the low-pressure shaft 9 via the reduction gear 3.

[0036] In the case of a planetary type gear reducer, the outer ring is rotationally fixed to the blower shaft, the planet carrier is fixed to a fixed structure such as the input housing 24.

[0037] The gearbox 3 is arranged in a lubrication chamber 25 which extends around the axis C and therefore has a generally annular shape. On its inner periphery, the chamber 25 is delimited by the blower shaft 13 and the input shaft. On its outer periphery, the chamber 25 is advantageously, but not exclusively, delimited by the input housing 24 which extends around the gearbox 3. At its upstream end, the chamber 25 is delimited by a bearing support, for example, which is annular. This support has an outer periphery which is fixed to the inlet housing 24 and an inner periphery which retains bearing rings of roller bearings, the inner rings of which are fixed to the blower shaft 13. Finally, the enclosure 25 is closed at its downstream end by an annular hood which is carried by the inlet housing 24 and whose inner periphery hermetically seals around the inlet shaft.

[0038] Turbomachine 1 also includes: - an intermediate casing 34 which is inserted between the low-pressure compressor 4 and the high-pressure compressor 5, - an inter-turbine casing 35 which is interposed between the high-pressure turbine 7 and the low-pressure turbine 8, and - an exhaust casing 36 which is located downstream of the low pressure turbine 8.

[0039] The low pressure compressor 4 and the high pressure module 18 are surrounded by an annular housing 38, the upstream end of which includes an annular flange 38a for fixing to an annular flange 24b of the inlet housing 24, and the downstream end of which includes an annular flange 38b for fixing to an annular flange 36a of the exhaust housing 36.

[0040] As previously stated, trees and / or interfaces allow links to be made between several modules.

[0041] In particular, the turbomachine 1 includes coupling means 40 configured to connect the first module 14 and the second module 16. In particular, the low-pressure compressor shaft 15 is rotationally fixed to the low-pressure turbine shaft 17 and is also axially immobilized relative to the low-pressure turbine shaft 17.

[0042] The low-pressure compressor shaft 15 is coupled to the low-pressure turbine shaft 17 by means of splines. The coupling means 40 are formed by the splines. In particular, the low-pressure turbine shaft 17 extends at least partially inside the low-pressure compressor shaft 15. The latter comprises a plurality of internal splines 49 which are oriented along the longitudinal axis C. These internal splines 49 are arranged on an internal surface of the shaft. low pressure compressor 15 and regularly distributed around the longitudinal axis C. These are advantageously located at the downstream end 15b of the low pressure compressor shaft 15.

[0043] These internal splines 49 are configured to engage with corresponding external splines 50 of the low-pressure turbine shaft 17. The external splines 50 are arranged on an external surface of the low-pressure turbine shaft 17 and towards its upstream end 17a. These internal and external splines 49, 50 enable the low-pressure turbine shaft 17 to drive the low-pressure compressor shaft 15 in rotation and to transmit the rotational torque.

[0044] The coupling means 40 further comprise an axial locking device configured to axially immobilize the second module 16 relative to the first module 14. More specifically, the locking device makes it possible to immobilize the low-pressure turbine shaft 17 relative to the low-pressure compressor shaft 15.

[0045] As shown in Figures 2 to 5, such an axial locking device 50 comprises a nut 52 configured to axially immobilize the low-pressure compressor shaft 15 relative to the low-pressure turbine shaft 17 and to achieve the absorption of the axial thrust of the low-pressure turbine. The nut 52 comprises a rotational axis coaxial with the longitudinal axis C in the installed position.

[0046] The nut 52 is screwed onto the low-pressure turbine shaft 17 and is centered on the longitudinal axis C in the installed position. The nut 52 is arranged radially between the low-pressure compressor shaft 15 and the low-pressure turbine shaft 17. The nut 52 includes a thread that is screwed onto the second module 16. More specifically, the nut 52 includes an internal thread 58 that engages with an external thread 59 of the low-pressure turbine shaft 17. The external thread 59 is located at the upstream end 17a of the low-pressure turbine shaft 17, and more specifically upstream of the external splines 50 of the low-pressure turbine shaft 17.

[0047] The external diameter of the nut 52 is less than the internal diameter of the low pressure compressor shaft 15 and greater than the external diameter of the low pressure turbine shaft 17.

[0048] The nut 52 is axially engaged from the upstream end 17a of the low-pressure turbine shaft 17 and is screwed until it is axially clamped against an annular projection 60 or similar feature of the low-pressure shaft of the first module 14. In particular, the low-pressure compressor shaft 15 includes this annular projection 60 which extends radially inwards, i.e., towards the longitudinal axis C. In the present example, the annular projection 60 is formed upstream of the internal and external splines 49, 50. The nut 52 includes a downstream annular lateral face 53, which is support against an upstream annular surface 60a of the projection 60. The low pressure turbine shaft 17 can no longer move back downstream, nor can the low pressure turbine.

[0049] Furthermore, in the current technique and as shown in Figures 2 to 5, the turbomachine 1 advantageously comprises an annular adjusting shim 70A, arranged between the annular projection 60 of the low-pressure compressor shaft 15 and an annular shoulder 72A of the low-pressure turbine shaft 17. In the present example, the annular shoulder 72A is formed upstream of the internal and external splines 49, 50. The adjusting shim 70A comprises an upstream lateral face 70Aa, annular, bearing against a downstream annular surface 60b of the projection 60 and a downstream lateral face 70Ab, annular, bearing against an upstream annular surface 72Aa of the annular shoulder 72A.

[0050] This axial 70A adjustment wedge advantageously allows control or selection of the position of the various elements of the link.

[0051] Thus, in the current technique, the mounting of the low pressure shaft in the turbomachine includes the passage of the low pressure turbine shaft 17, downstream, into the high pressure body, then the assembly of the low pressure turbine shaft 17 with the rest of the engine by tightening the nut 52 upstream using a dedicated tool, the nut 52 having been passed upstream to its position on the shaft of the low pressure turbine.

[0052] It is understood from this arrangement that the maximum integration diameter of the splines 50 of the low pressure turbine shaft 17 is limited by the size of the high pressure body, in order to allow the mounting of the low pressure shaft in the engine.

[0053] Similarly, upstream of these grooves 50, the integration diameter of the thread 58 of the nut 52 is limited by several elements, including: the integration diameter of the grooves 50, the adjustment shim 70A and the radial offsets necessary for the manufacture and assembly of the different elements.

[0054] It is therefore understood that all these points constrain and limit the possible diameter for the integration of this clamping nut 52.

[0055] Indeed, conventionally, the diameter of the internal and external splines 49, 50 of the low-pressure shaft is limited by the internal diameter of the high-pressure shaft into which the low-pressure shaft must be inserted for the HP assembly. In the context of the invention, the diameter of the internal and external splines corresponds to the external diameter of the teeth of the internal splines. The internal and external splines 49, 50 are machined respectively in the low-pressure compressor and the low-pressure shaft by a machining tool such as a milling cutter. In order to allow the machining tool to be removed, the external diameter of the axial stop 72A and that of the adjusting shim 70A are smaller than the machining diameter of the internal and external splines. This results in a diameter difference forming a radial "step" between the stop and axial 72A (and the adjusting shim 70A) and the diameters of the internal and external splines 49, 50 of the low-pressure shaft. As an example, [Fig. 5] illustrates such a step, denoted A, of approximately 0.5 mm, allowing a diameter D for the integration of this clamping nut 52 of approximately 97 mm. Different measurements of step A and diameter D may also be used.

[0056] However, new generations of engines will tend, in order to save on fuel consumption, to reduce the size of the high-pressure body as much as possible, generating the need to reduce the diameter for the integration of the splines 49, 50, but also of the nut 52 of this connection.

[0057] However, the mounting diameter of this connection has a primary impact on its mechanical load-bearing capacity. Indeed, this nut and its tightening force must overcome the aerodynamic forces acting on the low-pressure turbine and the low-pressure compressor. Figure 3 illustrates the forces that determine the dimensions of this connection. The aerodynamic forces acting on the low-pressure turbine are represented by arrow F1, and the aerodynamic forces acting on the low-pressure compressor, opposing those of the low-pressure turbine, are represented by arrow F2. The tightening force of the nut to overcome the external axial forces is represented by arrow F3.

[0058] The main problem we are trying to solve is therefore to increase the integration diameter of this nut. This is indeed the parameter that plays a crucial role in the dimensioning of the nuts.

[0059] Indeed, even if the number of threads in contact plays a role in the dimensioning of the nut since the load is distributed over the different threads in contact at the cost of an increase in axial space, there is a plateau because, from 4 or 5 threads in contact, there is almost no further reduction of the force in the first thread of the nut.

[0060] The invention proposes to optimize the geometry of the low-pressure shaft, and in particular the geometry along the radial direction which generally constrains the radial position of the nut.

[0061] Figures 6 to 13 illustrate an embodiment of this device according to the invention, in which the elements already described above are designated by the same reference numerals. In particular, [Fig. 6] is a schematic enlarged perspective axial cross-sectional view of the turbomachine of [Fig. 1] at the connection between the low-pressure compressor shaft 15 of the first module and the low-pressure turbine shaft 17 of the second module according to the invention. [Fig. 7] is a schematic enlarged axial cross-sectional view of the connection illustrated in [Fig. 6].

[0062] Figures 8 to 13 illustrate steps in the assembly process of this link which will be described later.

[0063] As described previously, the turbomachine 1 includes coupling means 40 configured to connect the first module 14 and the second module 16. In particular, the low-pressure compressor shaft 15 is rotationally fixed to the low-pressure turbine shaft 17 and is also axially immobilized relative to the low-pressure turbine shaft 17.

[0064] The low-pressure compressor shaft 15 is coupled to the low-pressure turbine shaft 17 by means of splines. The coupling means 40 are formed by the splines. In particular, the low-pressure turbine shaft 17 extends at least partially inside the low-pressure compressor shaft 15. The latter comprises a plurality of internal splines 49 that are oriented along the longitudinal axis. These internal splines 49 are arranged on an internal surface of the low-pressure compressor shaft 15 and are regularly distributed around the longitudinal axis C. Advantageously, they are located at the downstream end 15b of the low-pressure compressor shaft 15.

[0065] These internal splines 49 are configured to engage with corresponding external splines 50 of the low-pressure turbine shaft 17, referred to as the "first external splines" of the low-pressure turbine shaft 17. The external splines 50 are arranged on an external surface of the low-pressure turbine shaft 17 and towards its upstream end 17a. These internal splines 49 and first external splines 50 enable the low-pressure turbine shaft 17 to drive the low-pressure compressor shaft 15 in rotation and to transmit the rotational torque.

[0066] The coupling means 40 further advantageously comprise an axial locking device configured to axially immobilize the second module 16 relative to the first module 14. More specifically, the locking device makes it possible to immobilize the low-pressure turbine shaft 17 relative to the low-pressure compressor shaft 15.

[0067] As described above, the axial locking device 50 includes a nut 52 configured to axially immobilize the low-pressure compressor shaft 15 relative to the low-pressure turbine shaft 17 and to absorb the axial thrust of the low-pressure turbine. The nut 52 includes a rotational axis that is coaxial with the longitudinal axis C in the installed position.

[0068] The nut 52 is screwed onto the low-pressure turbine shaft 17 and is centered on the longitudinal axis C in the installed position. The nut 52 is arranged radially between the low-pressure compressor shaft 15 and the low-pressure turbine shaft 17. The nut 52 includes a thread that is screwed onto the second module 16. More specifically, the nut 52 includes an internal thread 58 that engages with an external thread 59 of the low-pressure turbine shaft 17. The external thread 59 is located at the upstream end 17a of the low pressure turbine shaft 17, and more precisely upstream of the first external splines 50 of the low pressure turbine shaft 17.

[0069] The external diameter of the nut 52 is less than the internal diameter of the low pressure compressor shaft 15 and greater than the external diameter of the low pressure turbine shaft 17.

[0070] The nut 52 is axially engaged from upstream on the upstream end 17a of the low-pressure turbine shaft 17 and is screwed until it is axially tightened against an annular projection 60 or similar feature of the low-pressure shaft of the first module 14. In particular, the low-pressure compressor shaft 15 includes this annular projection 60 which extends radially inwards, i.e. towards the longitudinal axis C. In the present example, the annular projection 60 is formed upstream of the internal splines 49 and first external splines 50. The nut 52 includes a downstream annular lateral face 53 bearing against an upstream annular surface 60a of the projection 60. The low-pressure turbine shaft 17 can no longer move backwards, nor can the low-pressure turbine.

[0071] According to the invention, the low pressure turbine shaft 17 advantageously comprises an annular shoulder 72.

[0072] In the present example, the annular shoulder 72 is formed upstream of the first external splines 50. The annular shoulder 72 extends radially outwards and forms an axial stop for the first module 14, and in particular for the low pressure compressor shaft 15.

[0073] In the illustrated example, the low-pressure turbine shaft 17, and in particular the upstream end 17a of the low-pressure turbine shaft 17, has an annular projection 80 extending radially outwards forming the annular shoulder 72. This annular projection 80 has an upstream face 80a, forming the annular shoulder 72.

[0074] In the illustrated example, the projection 80 is formed at an axial distance from the external grooves 50 of the low pressure turbine shaft 17 in order to allow clearance of a tool used for the assembly of the turbomachine, and in particular for the assembly of the first module and the second module.

[0075] After assembly, the annular projection 60 of the low pressure compressor 15 includes a downstream face 60b bearing against the upstream face 80a of the annular projection 80 forming the annular shoulder 72 of the low pressure turbine shaft.

[0076] According to the invention, the annular projection 80 of the low-pressure turbine shaft forming the annular shoulder 72 has an outside diameter equal to that of the low-pressure turbine shaft 17 at the first external splines 50. In addition, the annular projection 80 forming the annular shoulder 72 includes external splines 82, referred to as the "second external splines 82," shaped to allow the passage of the internal splines 49 of the low pressure compressor shaft 15. The outside diameter of the annular projection 80 corresponds to the outside diameter of the teeth of the "second external splines 82".

[0077] The second external grooves 82 are arranged on an external surface of the annular projection 80 and regularly distributed around the longitudinal axis C. They are oriented along the longitudinal axis C.

[0078] Preferably, the first external splines 50 of the low-pressure turbine shaft are similar to the second external splines 82, that is to say, they have the same cross-section.

[0079] In addition, the turbomachine 1 advantageously comprises an annular adjusting shim 70, arranged axially between the first module 14 and the annular shoulder 72 of the low-pressure turbine shaft 17. More specifically, the adjusting shim 70 is arranged axially between the annular projection 60 of the low-pressure compressor shaft 15 and the annular projection 80 forming the annular shoulder 72 of the low-pressure turbine shaft 17.

[0080] This axial adjustment wedge 70 advantageously allows control or selection of the position of the different elements of the linkage.

[0081] The adjustment wedge 70 comprises an upstream lateral face 70a, annular, bearing against a downstream annular surface 60b of the projection 60 and a downstream lateral face 70b, annular, bearing against an upstream annular surface 72a of the annular shoulder 72.

[0082] According to the invention, the adjusting shim 70 has an outside diameter equal to that of the low-pressure turbine shaft 17 at the first external splines 50. In addition, the adjusting shim 70 is shaped to allow passage of the internal splines 49 of the low-pressure compressor shaft 15.

[0083] For this purpose, the adjusting shim 70 includes external grooves 74 shaped to allow the passage of the internal splines 49 of the low-pressure compressor shaft 15 during assembly. The outside diameter of the adjusting shim 70 corresponds to the outside diameter of the teeth of the external grooves 74.

[0084] The external grooves 74 are arranged on an external surface of the adjustment wedge 70 and regularly distributed around the longitudinal axis C. They are oriented along the longitudinal axis C.

[0085] According to one example, the external grooves form external splines, called "third external splines" shaped to allow the passage of the internal splines 49 of the low pressure compressor shaft 15 during assembly.

[0086] Preferably, the third external splines of the low-pressure turbine shaft adjustment shim are similar to the second external splines 82 and / or to the first external splines 50 of the low pressure turbine shaft, that is to say that they have the same cross-section.

[0087] According to one example, the external grooves have a shape of slotted shapes to allow the passage of the internal splines 49 of the low pressure compressor shaft 15 during assembly.

[0088] The geometry of the annular shoulder 72 of the low-pressure turbine shaft and that of the adjusting shim 70, which allows the internal splines 49 of the low-pressure compressor shaft 15 to pass through during assembly, make it possible to obtain a radially higher axial stop. By increasing the outer diameter of the adjusting shim, its inner diameter can also be increased.

[0089] Consequently, the invention makes it possible to increase the diameter D for the integration of the clamping nut 52. This increase in the radius of the nut allows for a better mechanical capacity of the latter. In this case, the diameter increases from 97 mm to 103 mm.

[0090] Furthermore, the invention advantageously includes a rotation locking system 90, visible in [Fig. 6], which is configured to lock the clamping nut 52 in its position. The rotation locking system 90 is configured in particular to prevent / block the rotation of the clamping nut 52.

[0091] The rotation locking system 90 comprises a cylindrical locking piece 92 centered on the longitudinal axis C in the installation position.

[0092] The blocking piece 92 comprises an upstream portion 92a, a downstream portion 92b and an intermediate portion 92c arranged between the upstream portion 92a and the downstream portion 92b along the longitudinal axis C.

[0093] The external diameter of the locking piece 92 is less than the internal diameter of the clamping nut 52, and in particular less than the internal diameter of an upstream portion 52a of the clamping nut 52.

[0094] Furthermore, the external diameter of the blocking piece 92 is less than the internal diameter of the low pressure turbine shaft 17 and in particular less than the internal diameter of the upstream end 17a of the low pressure turbine shaft 17.

[0095] In the example illustrated in [Fig.6], the upstream end 52a of the clamping nut 52 has an external diameter smaller than the diameter of the rest of the clamping nut 52, i.e. of a downstream portion 52b in which the internal thread 58 is formed.

[0096] More specifically, in the illustrated example, the external diameter of the upstream end 52a is substantially equal to the external diameter of the low pressure turbine shaft 17, and in particular of the upstream end 17a in which the external thread 59 is provided.

[0097] The locking piece 92 is coupled to the low-pressure turbine shaft 17 by means of splines. In particular, the locking piece 92 extends at least partially inside the low-pressure turbine shaft 17. The latter comprises a plurality of internal splines 94, referred to as the "second internal splines" of the turbine shaft. low pressure 17. They are oriented along the longitudinal axis. These internal grooves 94 are arranged on an internal surface of the low pressure turbine shaft 17 and regularly distributed around the longitudinal axis C. These are advantageously located at the upstream end 17a of the low pressure turbine shaft 17.

[0098] These internal splines 94 are configured to engage with corresponding external splines 95 of the locking piece 92, referred to as the "first external splines" of the locking piece 92. The first external splines 95 are arranged on an external surface of the locking piece 92 and towards its downstream end, more precisely on its downstream portion 92b. These second internal splines 94 and the first external splines 95 enable the low-pressure turbine shaft 17 to rotate the locking piece 92.

[0099] The locking piece 92 is coupled to the clamping nut 52 by means of splines. In particular, the locking piece 92 extends at least partially inside the clamping nut 52. The latter comprises a plurality of internal splines 96, referred to as the "third internal splines" of the clamping nut 52. These are oriented along the longitudinal axis. These third internal splines 96 are arranged on an internal surface of the clamping nut 52 and are regularly distributed around the longitudinal axis C. Advantageously, they are located at the upstream portion 52a of the clamping nut 52.

[0100] These internal third splines 96 are configured to engage with corresponding external splines 97 of the locking piece 92, referred to as the "external second splines" of the locking piece 92. The external second splines 97 are arranged on an external surface of the locking piece 92, more precisely on its intermediate portion 92c. The internal third splines 96 and the external second splines 97 enable the locking piece 92 to rotate the clamping nut 52.

[0101] The rotation-locking system 90 further comprises a ring 98 or circlip which is centered on the longitudinal axis C in the installed position. The ring 98 is generally split like a circlip.

[0102] The ring 98 is partially received in an annular groove 99 of the clamping nut 52, referred to as the "first annular groove 99". The first annular groove 99 has an opening oriented towards the longitudinal axis C. The first annular groove 99 is formed in the upstream portion 52a of the clamping nut 52. It is advantageously located upstream of the third internal splines 96 of the clamping nut 52.

[0103] The ring 98 is also partially received in a second annular groove 100 of the locking piece 92, referred to as the "second annular groove 100". The second groove The annular groove 100 has an opening oriented opposite to the longitudinal axis C. The second annular groove 100 is formed in the upstream portion 92a of the locking piece 92. It is advantageously positioned upstream of the second external grooves 97 of the locking piece 92.

[0104] Thus, the ring 98 is configured, in the installation position, to axially lock the locking piece 92 relative to the clamping nut 52

[0105] Furthermore, the low-pressure turbine shaft 17, and more specifically the upstream end 17a, includes an annular projection 110 which extends radially inwards, i.e. towards the longitudinal axis C. The locking piece 92 includes a downstream lateral face 93, annular, bearing against an upstream annular surface 110a of the projection 115. In the installation position, the locking piece 92 can no longer move backwards downstream thanks to this annular projection 115 forming an axial stop.

[0106] Reference is now made to Figures 8 to 13, which illustrate steps in a process for assembling or reassembling the turbomachine modules. It is understood that disassembling the turbomachine modules can be carried out by repeating these operations in reverse order in order to perform maintenance on at least one of the turbomachine modules.

[0107] The proposed geometry of the various parts of the turbomachine and in particular that of the low pressure turbine shaft 17, the low pressure compressor shaft 15, the adjusting shim 70 and the nut 52, advantageously allows the mounting of the low pressure compressor shaft 15 and the nut 52 from upstream to downstream.

[0108] Figure [Fig.8] illustrates a low-pressure turbine shaft 17 as described above.

[0109] The assembly method then includes a step of mounting an adjusting shim 70 as described above from upstream to downstream until it is axially abutted against the annular projection 80 forming the annular shoulder 72 of the low-pressure turbine shaft 17 ([Fig. 9]). The adjusting shim is then angularly aligned so that the external grooves 74 of the adjusting shim 70 are each angularly aligned with an external spline 50 of the low-pressure turbine shaft 17 and / or with an external spline 82 of the annular projection 80 forming the annular shoulder 72 of the low-pressure turbine shaft 17.

[0110] The process continues by inserting the low pressure compressor shaft 15 onto the upstream end 17a of the low pressure turbine shaft 17. During this step, the low pressure compressor shaft 15 is inserted from upstream to downstream so as to seat it in the grooves 74 of the adjusting shim 70 and then in the external splines 82 of the annular projection 80 forming the annular shoulder 72 of the low pressure turbine shaft 17 with reference to [Fig. 10].

[0111] Then, with reference to [Fig. 1 1], the low-pressure compressor shaft 15 is engaged in the external splines 50 of the low-pressure turbine shaft 17 until it is butted against the annular shoulder 72 of the low pressure turbine shaft 17 via the adjusting shim 70.

[0112] Fig. 12 illustrates the insertion of nut 52 from upstream to downstream and the tightening of nut 52. During the tightening of nut 52 by threading, nut 52 moves downstream relative to the low pressure turbine shaft 17 and the low pressure compressor shaft 15 until it comes into axial contact with the annular projection 60 of the low pressure compressor shaft 15.

[0113] Fig. 13 illustrates the upstream to downstream insertion of the anti-rotation device of nut 52.

[0114] With such a configuration, it is possible to disassemble and assemble only the low pressure shaft 9 while maintaining the other shafts of the other modules in the assembled position.

Claims

Demands

1. Aircraft turbomachine (1), the turbomachine having a longitudinal axis (C) and comprising: - a first module (14) comprising a low-pressure compressor (4) and a low-pressure compressor shaft (15) which is centered on the longitudinal axis (C) and includes internal splines (49), - a second module (16) comprising a low-pressure turbine (8) and a low-pressure turbine shaft (17) which is centered on the longitudinal axis (C) and includes first external splines (50) configured to engage with the internal splines (49) of the low-pressure compressor shaft (15), the low-pressure turbine shaft (17) comprising a downstream end connected to a rotor of the low-pressure turbine and an upstream end (17a) connected to a rotor of the low-pressure compressor,and - a locking device (50) configured to axially immobilize the low-pressure turbine shaft (17) of the second module (16) relative to the low-pressure compressor shaft (15) of the first module (14), characterized in that the low-pressure turbine shaft (17) has an annular shoulder (72) extending radially outwards and arranged upstream of the first external splines (50) forming an axial stop for the first module (14), the annular shoulder (72) has an external diameter equal to that of the low-pressure turbine shaft (17) at the first external splines (50), and the annular shoulder (72) includes second external splines (82) shaped to allow passage of the internal splines (49) of the low-pressure compressor shaft (15).

2. Turbomachine (1) according to claim 1, wherein the low pressure turbine shaft has an annular projection extending radially outwards forming the annular shoulder (72).

3. Turbomachine (1) according to claim 1 or 2, wherein the low pressure compressor shaft (15) comprises an annular projection (60) radially inward, the annular projection (60) of the low pressure compressor (15) comprising a downstream face (60b) bearing against an upstream face (72a) of the annular shoulder (72) of the low pressure turbine shaft.

4. Turbomachine (1) according to any one of claims 1 to 3, comprising an annular adjusting shim (70) arranged axially between the first module (14) and the annular shoulder (72) of the low pressure turbine shaft (17), the adjusting shim (70) having an outside diameter equal to that of the low pressure turbine shaft (17) at the first external splines (50) and being shaped to permit passage of the internal splines (49) of the low pressure compressor shaft (15).

5. Turbomachine (1) according to claim 4 when it depends on claim 3, wherein the adjusting shim (70) is arranged between the annular projection (60) of the low pressure compressor shaft (15) and the annular shoulder (72) of the low pressure turbine shaft (17).

6. Turbomachine (1) according to claim 4 or 5, wherein the adjusting shim (70) comprises external grooves shaped to permit passage of the internal splines (49) of the low-pressure compressor shaft (15).

7. Turbomachine (1) according to claim 6, wherein each external groove of the adjusting wedge (70) has a fluted shape.

8. Turbomachine (1) according to claim 6, wherein each external groove of the adjusting wedge (70) has a notched shape.

9. Turbomachine (1) according to any one of the preceding claims, wherein the locking device (50) comprises a nut (52) centered on the longitudinal axis (C) and screwed onto a thread of the low pressure turbine shaft (17), the nut bearing against an annular projection of the first module (14).

10. Turbomachine (1) according to the preceding claim, wherein the upstream end (17a) of the low pressure turbine shaft (17) extends inside the low pressure compressor shaft (15), the nut (52) being mounted inside the low pressure compressor shaft (15) which includes the annular projection of the first module (14).

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