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 (14) comprising a compressor (4) and a low-pressure shaft (15),- a second module (16) comprising a turbine (8) and a low-pressure shaft (17), the shaft comprising an upstream end (17a) connected to a rotor of the compressor, and- a locking device (50) configured to axially immobilize the turbine shaft (17) relative to the compressor shaft (15), in which the upstream end (17a) of the turbine shaft (17) comprises a shoulder (150) extending radially inwards, and the locking device comprises:- a clamping wedge (80) arranged around the upstream end (17a) of the turbine shaft (17), and bearing against an annular projection (60) of the first module (14), and- an additional axial locking system (90) configured to immobilize axially the clamping wedge (80) relative to the turbine shaft. Figure for abstract: Figure 4

Description

Title of the invention: TURBOMACHINE COMPRISING SEVERAL MODULES AND A DEVICE FOR LOCKING THEM THESE MODULES, AND CORRESPONDING MOUNTING METHOD Technical field

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

[0002] An aircraft turbomachine is often produced in the form of an assembly of modules that may each include fixed and moving parts. A module is defined as a subassembly of an engine that has geometric characteristics at its interfaces with adjacent modules that are sufficiently precise for it to be delivered individually, and which has undergone separate balancing when it includes rotating parts. Assembling the modules makes it possible to form a complete engine, minimizing the balancing and matching operations of the interface parts.

[0003] The modularity of a turbomachine is a key element for its maintenance. Indeed, during an intervention, the parts must be easily accessible without having to dismantle a large number of parts of the engine. In practice, we try to obtain a division into a few major and minor modules. For example, for a turbomachine having an upstream fan (the terms "upstream" and "downstream" are assessed in relation to the flow of gases in the turbomachine), it is configured with three major modules: an upstream major module for the front part including the fan, an intermediate major module for the intermediate part including the low pressure compressor and the high pressure body and a downstream major module for the rear part including the low pressure turbine and the low pressure shaft. In this specific example, the low pressure body is divided into two modules.It is possible that the low pressure body is divided equally into three modules with the low pressure compressor arranged independently of the rest of the intermediate major module.

[0004] Generally, the major intermediate module and the major downstream module comprising the members of the low-pressure body are fixed to each other by means of a nut which is centered on the axis of the turbomachine and which serves to axially tighten the low-pressure compressor shaft and the low-pressure turbine shaft. During a maintenance operation, this nut must be unscrewed using a tool which 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 reducer in the front or upstream part and possibly a blade pitch change system upstream. The problem in this case is accessibility to the nut. The reducer is located upstream of the nut and must be partially dismantled to gain access to the nut. Furthermore, access to the nut is achieved with complex tools from upstream of the turbomachine to prevent them from being too long and to have an acceptable diameter.

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

[0007] This implies on the one hand that the access diameter of the tools is smaller than that of the nut and on the other hand that the nut is trapped in the turbomachine. Increasing the internal diameter of the internal planetary gear to be greater than that of the nut and allow the nut to be removed would be detrimental to the size of the reducer and the general performance of the turbomachine.

[0008] Furthermore, the tools may present risks of incorrect handling and damage to certain parts of the turbomachine which are located near the nut. Added to this is the fact that the nut also requires a high tightening torque (order of magnitude 2000 Nm). With such a torque, a long and small diameter wrench has the disadvantage of having a high torsion angle and consequently poor precision in finding an exact angular position necessary to access the nut, all this while blind.

[0009] In order to improve their propulsive efficiency, turbomachines tend towards increasing the 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] Furthermore, certain turbomachines, such as those with a single unducted fan (also called USF, acronym for Unducted Single Fan), have a particularly long length and the modules of the high pressure and low pressure bodies have very small internal diameters, which complicates or even makes access to the nut by the tool impossible.

[0011] The present invention provides a solution to at least part 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] For this purpose, 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, - a second module comprising a low pressure turbine and a low pressure turbine shaft which is centered on the longitudinal axis, 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 so as 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 upstream end of the low pressure turbine shaft comprises a shoulder extending radially inwards, and the locking device comprises: - a clamping wedge centered on the longitudinal axis, arranged around the upstream end of the low-pressure turbine shaft, and bearing against an annular projection of the first module, and - an additional axial locking system configured to axially immobilize the clamping wedge relative to the low pressure turbine shaft.

[0013] Thus, this solution makes it possible to achieve the aforementioned objective. In particular, the clamping shim provides an alternative to increasing the implantation radius of the nut of the prior art allowing the coupling between the low pressure compressor shaft and the low pressure turbine shaft.

[0014] The tightening shim makes it possible to remove the threads from the nut in order to overcome their mechanical strength limitation. Tightening by threading is replaced by tightening by elongation, that is to say that an axial force is applied to the low pressure turbine shaft in order to lengthen it. Indeed, the tightening shim advantageously makes it possible to take up the axial force and the tightening force of the torque.

[0015] This configuration provides increased modularity. The arrangement of the clamping wedge allows for effective immobilization between the modules. This also allows at least one non-bulky tool to be brought inside. The low-pressure turbine and low-pressure compressor modules can thus be dismantled in a reduced number of operations compared to the other modules and without dismantling the other adjacent modules. The clamping wedge provides a clamping force sufficient, even for small low pressure shaft diameters.

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

[0017] The turbomachine according to the invention may comprise one or more of the following characteristics, taken in isolation from one another or in combination with one another according to all technically possible combinations: - the additional axial locking system comprises at least one annular row of radial teeth arranged on the clamping wedge and configured to cooperate by dog ​​engagement with an annular row of radial slots of the low pressure turbine shaft; - the low pressure compressor shaft comprises the annular projection and the clamping wedge comprises a downstream face in direct contact with an upstream face of the annular projection; - the axial locking device comprises an adjustment shim arranged axially between the clamping shim and the annular projection, the clamping shim bearing against the annular projection of the first module via the adjustment shim; - the low pressure compressor shaft comprises the annular projection, the adjustment shim comprises a downstream face bearing against an upstream face of the annular projection, and the tightening shim comprises a downstream face bearing against an upstream face of the adjustment shim; - the locking device comprises a rotation locking system configured to lock the rotation of the clamping wedge; - the rotation locking system comprises: a first ring centered on the longitudinal axis and intended to bear against a radial annular face of the clamping wedge, the first ring comprising a plurality of radial teeth each intended to engage in a radial notch of the low-pressure turbine shaft, and a second ring centered on the longitudinal axis and received in an annular groove of the clamping wedge, the annular groove being provided upstream of the radial annular face; - the upstream end of the low pressure turbine shaft extends inside the low pressure compressor shaft, the clamping shim being mounted inside the low pressure compressor shaft which includes the shoulder; - the turbomachine comprises a fan which is connected to a fan shaft and which is arranged upstream of the first module and the low-pressure compressor, a low-pressure shaft driving the fan shaft in rotation via a speed reducer, the low-pressure shaft being formed by the connection of the low-pressure compressor shaft with the low-pressure turbine shaft; - the low pressure compressor shaft is connected to an input shaft of the speed reducer.

[0018] The invention also relates to a method of mounting an aircraft turbomachine according to the invention and as described above, the method comprising the steps of: - insertion of a tool into the low pressure turbine shaft so as to position the tool in abutment against the shoulder of its upstream end; - application of a force from downstream to upstream exerted by the tool against the shoulder of the upstream end; - installation of the clamping shim on the upstream end of the low pressure turbine shaft from upstream to downstream; - axial immobilization of the clamping wedge relative to the low pressure turbine shaft; and - removal of the applied force.

[0019] The method according to the invention may comprise one or more of the following characteristics, taken in isolation from one another or in combination with one another according to all technically possible combinations: - the method comprises a step of locking the clamping wedge in rotation before removing the applied force; - the method comprises a step of inserting an additional adjustment shim bearing against the annular projection of the first module before installing the tightening shim. Brief description of the drawings

[0020] The present invention will be better understood and other details, characteristics and advantages of the present invention will appear more clearly on reading the description of a non-limiting example which follows, with reference to the appended drawings in which: - [Fig.l] is a half schematic view in axial section of an aircraft turbomachine; - [Fig.2] is an enlarged schematic sectional view of the turbomachine of [Fig.l] at the connection between a low-pressure compressor shaft and a low-pressure turbine shaft according to the technique prior to 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 technique prior to the invention; - [Fig.4] is an enlarged schematic sectional view of the turbomachine of [Fig.l] at the connection between a low pressure compressor shaft and a shaft low pressure turbine according to a first embodiment of the invention; - [Fig.5] is a schematic perspective and axial sectional view of a clamping wedge of the connection illustrated in [Fig.4]; - [Fig.6] is a schematic perspective and axial sectional view of the upstream end of the low pressure turbine shaft of the connection illustrated in [Fig.4]; - [Fig.7] is an enlarged schematic sectional view of the turbomachine of [Fig.l] at the connection between a low-pressure compressor shaft and a low-pressure turbine shaft according to a second embodiment of the invention; - [Fig.8] is a schematic perspective view of an anti-rotation device installed on the clamping wedge of the connection of [Fig.5] and the low pressure turbine shaft of the connection illustrated in [Fig.4]; - [Fig.9] is a schematic sectional view of the method of mounting the connection of [Fig.4] illustrating a step of applying a force to the low pressure turbine shaft; - [Fig. 10] is a view similar to [Fig.9] showing a step of inserting the clamping wedge of [Fig.5]; - [Fig. 11] is a view similar to [Fig.9] showing a step of axially abutting the clamping wedge of [Fig.5]; - [Fig. 12] is a schematic sectional view of the method of mounting the connection of [Fig.4] illustrating a step of angular positioning of the intermediate part of [Fig.5]; - [Fig. 13] is a schematic view of the forces dimensioning the connection between the low pressure compressor shaft and the low pressure turbine shaft during the application of the force according to the invention; - [Fig. 14] is a view similar to [Fig. 9] showing a step of locking the position of the clamping wedge; and - [Fig. 15] is a view similar to [Fig. 12] illustrating a step of removing the force exerted on the low pressure turbine shaft.

[0021] Elements having the same functions in different implementations have the same references in the figures.

[0022] In the figures, the scales and proportions are not strictly respected, for the purposes of illustration and clarity.

[0023] In the description, the expressions "internal" or "interior" and "external" or "exterior" are used without limitation in reference to the radial distance from the longitudinal axis around which the turbomachine extends, the expression "internal" defining a zone radially closer to the longitudinal axis of the nacelle, as opposed to the expression "external". Furthermore, in the description and the claims, the terminology axial, radial and transverse with reference to the trihedron A, R, T indicated in the figures, the axial axis A being parallel to the longitudinal axis of the turbomachine. Description of the embodiments

[0024] Reference is first made to [Fig. 1] which illustrates an aircraft turbomachine which is here a single unducted fan (USF) turbomachine 1 although the aspects of the invention are not limited to this particular type of turbomachine.

[0025] 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.

[0026] In the present invention, and generally, the terms "upstream" and "downstream" are defined with respect to a main direction F of circulation of the fluids inside the turbomachine, and here along the longitudinal axis C, that is to say from left to right with reference to [Fig.l].

[0027] 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.

[0028] The turbomachine 1 is modular and comprises several modules assembled / connected to each other and which make it easier to maintain it. Shafts and / or interfaces make it possible to make these connections.

[0029] A first module 14 comprises the low pressure compressor 4 and a low pressure compressor shaft 15.

[0030] 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 integral with the low-pressure turbine shaft 17 to form the low-pressure shaft 9.

[0031] 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.

[0032] The turbomachine further comprises an upstream module 11 which comprises the fan 2 and a speed reducer 3. The latter comprises an input shaft which is centered on the longitudinal axis C. The input shaft is part of the upstream module 11. The blower 2 comprises a fan shaft 13 which is rotated by the low pressure shaft 9 via the speed reducer 3. The upstream module 11 is mounted upstream of the first module 14.

[0033] The low pressure compressor shaft 15 and the input shaft 12 are both advantageously hollow. The low pressure shaft 9 is also hollow.

[0034] The low pressure shaft 9 extends at least partly inside the high pressure shaft 10 and are coaxial.

[0035] According to this configuration, the low pressure body or LP 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.

[0036] The turbomachine 1 is in fact 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 type gear. A reducer with an epicyclic gear train conventionally comprises a sun gear (or internal planetary gear), a plurality of satellites (which are pinions), a planet carrier and an external ring gear (or external planetary gear). The sun gear is centered on the longitudinal axis C. The external ring gear is centered on the longitudinal axis C and extends around the sun gear. The satellites are arranged between the sun gear and the external ring gear and are carried by the planet carrier. The satellites are each mounted to rotate freely around a satellite axis using a bearing and mesh with external teeth of the sun gear and internal teeth of the external ring gear.

[0037] In the present case, the external crown is stationary and fixed to a stator of the turbomachine which is here an input casing 24. The solar is mobile in rotation and coupled to the input shaft which itself is connected to the low pressure shaft 9. The planet carrier is also mobile in rotation and coupled to the fan shaft 13. The fan 2 is therefore driven in rotation by the low pressure shaft 9 via the reducer 3.

[0038] In the case of a planetary type gear reducer, the external crown is integral in rotation with the fan shaft, the planet carrier is integral with a fixed structure such as the input casing 24.

[0039] The reducer 3 is arranged in a lubrication enclosure 25 which extends around the axis C and therefore has a generally annular shape. At its internal periphery, the enclosure 25 is delimited by the fan shaft 13 and the input shaft. At its external periphery, the enclosure 25 is advantageously, but not limited to, delimited by the input casing 24 which extends around the reducer 3. At its upstream end, the enclosure 25 is delimited by a bearing support for example which is annular. This support has an external periphery which is fixed to the input casing 24 and an internal periphery which holds rolling bearing rings, the internal rings of which are fixed to the fan shaft 13. Finally, the enclosure 25 is closed at its downstream end by an annular cover which is carried by the input casing 24 and the internal periphery of which surrounds the input shaft in a sealed manner.

[0040] The turbomachine 1 also comprises: - 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 inserted 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.

[0041] The low pressure compressor 4 and the high pressure module 18 are surrounded by an annular casing 38, an upstream end of which comprises an annular flange 38a for attachment to an annular flange 24b of the inlet casing 24, and a downstream end of which comprises an annular flange 38b for attachment to an annular flange 36a of the exhaust casing 36.

[0042] As indicated previously, trees and / or interfaces make it possible to create links between several modules.

[0043] In particular, the turbomachine 1 comprises coupling means 40 configured so as to connect the first module 14 and the second module 16. In particular, the low-pressure compressor shaft 15 is rotationally integral with the low-pressure turbine shaft 17 and is also axially immobilized relative to the low-pressure turbine shaft 17.

[0044] 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 partly inside the low-pressure compressor shaft 15. The latter comprises a plurality of internal splines 49 which are oriented along the longitudinal axis. These internal splines 49 are arranged on an internal surface of the low-pressure compressor shaft 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.

[0045] 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 allow the low pressure turbine shaft 17 to rotate the com low pressure presser 15 and torque transmission.

[0046] The coupling means 40 further comprises an axial locking device configured so as to axially immobilize the second module 16 relative to the first module 14. More precisely, the locking device makes it possible to immobilize the low-pressure turbine shaft 17 relative to the low-pressure compressor shaft 15.

[0047] In the current technique and as shown in [Fig.2], such an axial locking device 50A comprises a nut 52A which is configured so as to axially immobilize the low pressure compressor shaft 15 relative to the low pressure turbine shaft 17 and to achieve the recovery of the axial thrust of the low pressure turbine. The nut 52A comprises an axis of revolution which is coaxial with the longitudinal axis C in the installation situation.

[0048] The nut 52A is screwed onto the low pressure turbine shaft 17 and is centered on the longitudinal axis C in the installation situation. The nut 52A is arranged radially between the low pressure compressor shaft 15 and the low pressure turbine shaft 17. The nut 52A comprises a thread which is screwed onto the second module 16. More specifically, the nut 52A comprises an internal thread 58A which engages with an external thread 59A of the low pressure turbine shaft 17. The external thread 59A is located at the upstream end 17a of the low pressure turbine shaft 17, and more precisely upstream of the external splines 50 of the low pressure turbine shaft 17.

[0049] The outer diameter of the nut 52A is less than the inner diameter of the low pressure compressor shaft 15 and greater than the outer diameter of the low pressure turbine shaft 17.

[0050] The nut 52A is engaged axially 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 the like of the low-pressure shaft of the first module 14. In particular, the low-pressure compressor shaft 15 comprises 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 52A comprises a downstream lateral face 53A, annular, coming to bear against an upstream annular surface 60a of the projection 60. The low-pressure turbine shaft 17 can no longer move backwards downstream, nor can the low-pressure turbine.

[0051] Furthermore, the turbomachine 1 advantageously comprises an annular adjustment shim 70, arranged between the annular projection 60 of the low-pressure compressor shaft 15 and an annular shoulder 72 of the low-pressure turbine shaft 17. In the present example, the annular shoulder 72 is formed upstream of the internal and external splines 49, 50. The adjustment shim 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.

[0052] This axial adjustment shim 70 advantageously makes it possible to control or choose the position of the different elements of the connection.

[0053] Thus, in the current technique, the assembly of the low pressure shaft in the turbomachine comprises the passage of the low pressure turbine shaft 17, downstream, inside the high pressure body, then the assembly of the low pressure turbine shaft 17 with the rest of the engine by tightening the nut 52A upstream using a dedicated tool, the nut 52A being passed upstream to its position on the low pressure turbine shaft.

[0054] It is understood from this arrangement that the maximum integration diameter of the splines 50 of the shaft of the low pressure turbine 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.

[0055] Similarly, upstream of these grooves 50, the integration diameter of the thread 58A of the nut 52A is limited by several elements, in particular: the integration diameter of the grooves 50, the adjustment shim 70 and the radial offsets necessary for the manufacture and assembly of the different elements.

[0056] It is therefore understood that all these points constrain and limit the possible diameter for the integration of this tightening nut 52A.

[0057] However, new generations of engines will tend, in order to save fuel, to reduce the size of the high-pressure body as much as possible, creating the need to reduce the diameter for the integration of the splines 49, 50, but also of the nut 52A of this connection.

[0058] However, the installation diameter of this connection plays a major role in its mechanical capacity to pass loads. Indeed, this nut and its tightening force must overcome the aerodynamic forces applied to the low-pressure turbine and the low-pressure compressor. [Fig. 3] illustrates the forces sizing this connection. The aerodynamic forces applied to the low-pressure turbine are represented by the arrow F1 and the aerodynamic forces applied to the low-pressure compressor, opposite those of the low-pressure turbine, are represented by the arrow F2. The tightening force of the nut to overcome the external axial forces is represented by the arrow F3.

[0059] The main problem that we are seeking to resolve is therefore to be able to increase the integration diameter of this nut. This is in fact the parameter which plays a first-order role in the dimensioning of the nuts.

[0060] Indeed, even if the number of threads in engagement plays a role in the dimensioning of the nut since the load is distributed over the different threads in engagement at the cost of an increase mentation of the axial size, there is a level because, from 4 or 5 threads in engagement, there is almost no further reduction in the force in the first thread of the nut.

[0061] The invention proposes an alternative solution to increasing the diameter of the nut. Thus, the invention proposes a solution to facilitate the modularity of the turbomachine 1 thanks to another clamping device between the first module 14 and the second module 16 and in particular between the low pressure compressor shaft 15 of the first module 14 and the low pressure turbine shaft 17 of the second module 16.

[0062] Figures 4 to 6 and 8 to 14 illustrate a first embodiment of this device according to the invention in which the elements already described in the above are designated by the same references. In particular, [Fig. 4] is an enlarged schematic sectional view of the turbomachine of [Fig. 1] at the level of 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. Figures 5 and 6 schematically represent parts of this connection and Figures 8 to 14 illustrate steps of the method of mounting this connection which will be described later. [Fig. 12] illustrates the forces dimensioning this connection.

[0063] As described previously, the turbomachine 1 comprises coupling means 40 configured so as to connect the first module 14 and the second module 16. In particular, the low-pressure compressor shaft 15 is rotationally integral with 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 partly inside the low-pressure compressor shaft 15. The latter comprises a plurality of internal splines 49 which are oriented along the longitudinal axis. These internal splines 49 are arranged on an internal surface of the low-pressure compressor shaft 15 and regularly around the longitudinal axis C. These are advantageously 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. 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 allow the low pressure turbine shaft 17 to rotate the low pressure compressor shaft 15 and the transmission of rotational torque.

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

[0067] According to the invention and with reference to [Fig. 4], such an axial locking device 50 comprises a clamping wedge 80 which is configured so as to axially immobilize the low pressure compressor shaft 15 relative to the low pressure turbine shaft 17 and to achieve the recovery of the axial thrust of the low pressure turbine.

[0068] [Fig.5] is a schematic perspective and axial sectional view of the clamping wedge 80 and [Fig.6] is a schematic perspective and axial sectional view of the upstream end of the low pressure turbine shaft 17 of the connection.

[0069] The clamping wedge 80 comprises an axis of revolution which is coaxial with the longitudinal axis C in the installation situation. The clamping wedge 80 is arranged radially between the low-pressure compressor shaft 15 and the low-pressure turbine shaft 17. Furthermore, the clamping wedge 80 at least partially surrounds the upstream end 17a of the low-pressure turbine shaft 17. The clamping wedge 80 is arranged upstream of the external and internal splines 49, 50.

[0070] In the present example, the clamping wedge 80 comprises an upstream portion 80aa and a downstream portion 80bb which are annular and extend along the axis of revolution between an upstream end 80a and a downstream end 80b. The clamping wedge 80 is annular and delimited radially on the outside by an external surface 80c and radially on the inside by an internal surface 80d.

[0071] Unlike the nut or other clamping systems of the prior art, the clamping wedge 80 is devoid of splines or threads for coupling with the low-pressure turbine shaft 17. More precisely, the clamping wedge 80, and more precisely a portion 80db of the internal surface 80d relating to the downstream portion 80bb, is devoid of splines or threads. This portion 80db of the internal surface 80d relating to the downstream portion 80bb is in contact with a portion of a radially external surface 17c of the low-pressure turbine shaft 17 and more precisely of its upstream end 17a.As a result, the downstream portion 80bb, and more precisely the portion 80db of the internal surface in contact makes it possible to center the clamping shim relative to the low-pressure turbine shaft 17, and in particular its upstream end 17a, during the installation of the clamping shim during the assembly of the turbomachine, and in particular the assembly of the first module 14 to the second module 16. The surface portion 80db relating to the downstream portion 80bb in contact with the portion of the radially external surface 17c of the upstream end 17b of the low-pressure turbine shaft 17 extends over a length L1 in the axial direction A of between 3 and 15 mm for example. This distance L1 is advantageously less than the length . L2 extension of internal and external grooves 49, 50.

[0072] In the example shown, the low-pressure compressor shaft 15 comprises a first shaft portion 15aa and a second shaft portion 15bb downstream of the first shaft portion 15aa. The first internal splines 49 are arranged on the second portion 15bb of the low-pressure compressor shaft 15. In this example, the first portion 15aa comprises an internal diameter DI which is slightly greater than the internal diameter D2 of the second portion 15bb.

[0073] We can also see in [Fig.4] that the low-pressure turbine shaft 17, and more precisely its upstream end 17b, comprises from upstream to downstream a first shaft portion 17aa, a second shaft portion 17ab, a third shaft portion 17ba and a fourth shaft portion 17bb, with respective outer diameters D3, D4, D5 and D6. The first portion 17aa comprises an outer diameter D3 which is smaller than the outer diameter D4 of the second portion 17ab. The outer diameter D4 of the second portion 17ab is smaller than the outer diameter D5 of the third portion 17ba, and the outer diameter D5 of the third portion 17ba is smaller than the outer diameter D6 of the fourth portion 17ba.

[0074] The internal diameter D2 of the second portion 15bb of the low pressure compressor shaft 15 is substantially equal to the maximum external diameter of the low pressure turbine shaft 17, and in particular to the external diameter D6 of the fourth portion 17bb of the end of the low pressure turbine shaft 17.

[0075] The internal diameter DI of the first shaft portion 15aa of the low pressure compressor shaft 15 is substantially greater than the external diameters D3, D4 and D5 of the portions 17aa, 17ab and 17ba of the upstream end 17a of the low pressure turbine shaft 17.

[0076] The external diameter of the clamping shim 80 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. More precisely, the external diameter of the clamping shim 80 is less than the internal diameter DI of the first shaft portion 15aa of the low-pressure compressor shaft 15 and greater than the external diameter D5 of the third shaft portion 17ba of the low-pressure turbine shaft 17 (and therefore greater than the external diameter D3 of the first shaft portion 17aa and the external diameter D4 of the second shaft portion 17ab).

[0077] Furthermore, the internal diameter of the clamping shim 80 is substantially equal to the external diameter of the second portion 17ab of the low pressure turbine shaft 17.

[0078] The clamping wedge 80 is engaged axially from upstream on the upstream end 17a of the low-pressure turbine shaft 17 until it is in axial support against an annular projection 60 or the like of the first module 14. In particular, the low-pressure compressor shaft 15 comprises this annular projection 60 which extends radially towards the interior, that is to say towards the longitudinal axis C. In the present example, the annular projection 60 is formed upstream of the internal and external splines 49, 50. In the present example, the annular projection 60 is formed at the limit in the first portion 15aa of the low pressure compressor shaft 15. The clamping wedge 80 comprises a downstream lateral face 82, annular, coming to bear against an upstream annular surface 60a of the projection 60. The low pressure turbine shaft 17 can no longer move backward downstream, nor can the low pressure turbine.

[0079] Furthermore, the turbomachine 1 advantageously comprises an annular adjustment shim 70, arranged between the annular projection 60 of the low-pressure compressor shaft 15 and an annular shoulder or projection 72 of the low-pressure turbine shaft 17. In the present example, the annular shoulder 72 extends radially outwards and is formed upstream of the external splines 50. The adjustment shim 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.

[0080] This axial adjustment shim 70 advantageously makes it possible to control or choose the position of the different elements of the connection.

[0081] The axial locking device 50 further comprises an additional axial locking system 90 configured to axially immobilize the clamping wedge 80 relative to the low pressure turbine shaft 17 and therefore the low pressure compressor shaft 15 relative to the low pressure turbine shaft 17.

[0082] The additional axial locking system 90 comprises an annular row of teeth or dogs 92 arranged on the clamping wedge 80 and configured to cooperate by dog ​​engagement with an annular row of slots 93 of the low-pressure turbine shaft 17.

[0083] Indeed, the clamping wedge 80 comprises an annular row of first radial teeth 92 which extend radially inwards from the inner surface 80d of the clamping wedge. In the present example, the first radial teeth 92 extend in particular from an inner surface of the upstream portion 80aa of the clamping wedge. The first radial teeth 92 are regularly distributed around the longitudinal axis C. Each first radial tooth 92 is intended to engage in a corresponding first radial slot 93 of the low-pressure turbine shaft 17.

[0084] The low-pressure turbine shaft 17 comprises at its upstream end 17a, and more precisely in the first portion 17aa, first radial lugs 94 which extend radially inwards from the external annular face 17c of the low-pressure turbine shaft 17 and at a distance therefrom. Advantageously, each first radial lug 94 extends over an angular sector around the longitudinal axis C. The first lugs 94 are also spaced from each other so as to form the first radial slots 93. In this way, first slots 93 and first lugs 94 are alternated around the longitudinal axis C. The first slots 93 are shaped to allow the passage of the first radial teeth 92 of the clamping wedge 80. The first lugs 94 of the low-pressure turbine shaft 17 are shaped to axially retain the first radial teeth 92 of the clamping wedge 80. In other words, after insertion of the first radial teeth 92 through the first slots 93, a rotation of the clamping wedge 80 around its axis of rotation allows the radial teeth 92 to come into axial abutment against the first lugs 94 of the low-pressure turbine shaft 17. Each first radial tooth 92 has an upstream face 92a intended to bear against a downstream surface 94b of a first lug 94. clamping wedge 80 can no longer move back upstream.

[0085] The locking device 50 advantageously comprises a rotation locking system 100 which is configured so as to lock the clamping wedge 80 in its position. The rotation locking system 100 is configured in particular so as to prevent rotation of the clamping wedge 80.

[0086] With reference to [Fig.8], the rotation locking system 100 advantageously comprises a first ring 102, centered on the longitudinal axis C in the installation situation, intended to come to bear against a first annular face 84 of the clamping wedge 80. Second lugs 104 extend from the first annular face 84 of the clamping wedge 80 and at a distance therefrom, radially inwards.

[0087] Advantageously, each second lug 104 extends over an angular sector around the longitudinal axis C. The second lugs 104 are also spaced from each other so as to form second slots 105. In this way, second slots 105 and second lugs 104 alternate around the longitudinal axis C.

[0088] The first ring 102 comprises at least one second radial tooth 106 which extends from an outer peripheral edge (not shown) thereof. In the case where there are several second radial teeth 106, these are regularly distributed around the longitudinal axis C. Each second radial tooth 106 is intended to engage in a corresponding radial notch 108 of the low-pressure turbine shaft 17. The first slots 93 of the upstream end 17a of the low-pressure turbine shaft 17 advantageously, but not limitatively, form the notches 108.

[0089] Each second radial tooth 106 is also arranged in a second slot 105 of the clamping wedge 80.

[0090] The first rotation locking system 100 further comprises a second ring 110 which is centered on the longitudinal axis C in the installation situation. The second ring 110 is split generally like a circlip. The second ring 110 is received in an annular groove 112 of the clamping wedge 80. The annular groove 112 has an opening oriented towards the longitudinal axis C. The annular groove 112 is advantageously arranged upstream of the first annular face 84. More precisely, the annular groove 112 is formed in the second lugs 104. Alternatively, the annular groove 112 is formed by a distance between the first annular face 84 of the clamping wedge 80 and an internal face of the second lugs. In this way, the second ring 110 extends upstream of the first ring 102 and the second lugs 104 make it possible to achieve axial locking of the second ring 110. Advantageously, the second ring 110 bears against an upstream face 102a of the first ring 102.

[0091] The upstream end 17a of the low-pressure turbine shaft 17, and more precisely its first portion 17aa, has an internal diameter smaller than that of the second portion 17ab. The internal diameter of the first portion is also smaller than that of the second portion 17ba and that of the fourth portion 17bb. Indeed, the low-pressure turbine shaft 17 comprises a shoulder 150 at the boundary between the first and second portions 17aa, 17ab of the upstream end 17a. This shoulder 150 extends radially inwards, that is to say towards the longitudinal axis C, from the second portion 17ab towards the first portion 17aa. In the present example, the shoulder 150 is preferably annular. It is formed upstream of the annular projection 60. This shoulder 150 is shaped to cooperate with a tool 200, visible in figures 8 to 14 relating to the assembly method which will be detailed later.The tool 200 has a longitudinal cylindrical body 202 and a head or hook 204 extending perpendicular to the direction of extension of the cylindrical body 202. The tool 200 and more precisely the head 204 comprises an upstream lateral face 204a, preferably annular, bearing against a downstream annular surface 150b of the shoulder 150. The tool 200 is thus shaped to be able to apply an axial force directed from downstream to upstream on the shoulder 150 of the low-pressure turbine shaft 17 in order to lengthen the latter in the axial direction A to insert the clamping wedge between the projection 60 of the low-pressure compressor shaft 15 and the lugs 94 of the low-pressure turbine shaft 17 so as to axially immobilize the low-pressure compressor shaft 15 relative to the low-pressure turbine shaft 17. .

[0092] Reference is now made to [Fig.7] which represents a sectional view of the connection between the low pressure compressor shaft 15 and the low pressure turbine shaft 17 according to a second embodiment of the invention in which the elements already described in the above are designated by the same references.

[0093] In this second embodiment, the locking device 50 advantageously comprises an additional annular adjustment shim 170, arranged axially between the annular projection 60 of the low-pressure compressor shaft 15 and the clamping shim 80. The additional adjustment shim 170 comprises an upstream lateral face 170a, annular, bearing against a downstream annular surface 82 of the clamping shim clamping 80 and a downstream lateral face 170b, annular, coming to bear against the upstream annular surface 60a of the projection 60.

[0094] This additional axial adjustment shim 170 advantageously makes it possible to control or choose the position of the different elements of the connection. It also allows the application of tightening and to compensate for manufacturing tolerances.

[0095] We now refer to Figures 9 to 15 which illustrate steps of a method of mounting or reassembling the modules of the turbomachine. We understand that the disassembly of the modules of the turbomachine can be carried out by repeating these operations in reverse order in order to carry out maintenance operations on at least one of the modules of the turbomachine.

[0096] The proposed geometry of the various parts of the turbomachine and in particular that of the clamping shim 80, of the low-pressure turbine shaft 17 and of the low-pressure compressor shaft 15, advantageously allows the mounting of the clamping shim 80 from upstream to downstream.

[0097] As indicated previously, the clamping wedge 80 is provided with dogs 92 upstream and a centering portion 80db downstream.

[0098] Where appropriate, the method may include a preliminary step of installing the second adjustment shim 170 from upstream to downstream until it is in axial abutment against the projection 60 of the first module.

[0099] A first step of the method consists of inserting a tool 200 into the low-pressure turbine shaft (17) from upstream to downstream and positioning it so as to be able to cooperate with the low-pressure turbine shaft 17, and in particular its upstream end 17a. During this step and with reference to [Fig.9], the tool 200 is positioned so that the upstream face 204a of the head of the tool 200 is in contact with and even resting against a downstream surface 150b of the shoulder 150 of the low-pressure turbine shaft 17, and more precisely of its upstream end 17a.

[0100] A second step of the method consists in applying a force denoted F5 by the tool 200 on the upstream end 17a of the low pressure turbine shaft 17. This force F5 is an axial force oriented from downstream to upstream as illustrated in [Fig.9]. The force F5 is exerted by the tool 200 against the shoulder 150 of the upstream end 17a. It advantageously makes it possible to lengthen the low pressure turbine shaft 17 upstream in order to allow the insertion of the clamping shim 80. The lengthening of the low pressure turbine shaft depends on the force applied, the working length and section and the material of the shaft. The lengthening of the low pressure turbine shaft is between 5 and 20 nm.

[0101] The method continues by installing the clamping shim 80 on the upstream end 17a of the low-pressure turbine shaft 17, with reference to [Fig.10]. The clamping shim 80 is inserted from upstream to downstream according to the arrow F6 in the direction of the projection 60 of the first module and radially centered on the upstream end 17a thanks to the centering zone 80db. As illustrated, this step is carried out while maintaining the application of the force F5 exerted by the tool 200 on the low pressure turbine shaft.

[0102] During this step and with reference to [Fig.10], the clamping wedge 80 is inserted around the low pressure turbine shaft 17 by aligning the radial teeth or dogs 92 of the clamping wedge 80 with the slots 93 defined between the lugs 94 of the low pressure turbine shaft 17.

[0103] The clamping wedge 80 is thus moved in translation downstream so that the radial teeth or dogs 92 pass through the slots 93 until the downstream face 82 of the clamping wedge 80 comes into axial abutment against the annular projection 60 of the low-pressure compressor shaft 15. The clamping wedge 80 can no longer advance downstream. This step is illustrated in [Fig. 11].

[0104] [Fig. 12] illustrates a step of axial immobilization of the clamping wedge 80 relative to the low-pressure turbine shaft 17. This step comprises the angular positioning of the clamping wedge 80 relative to the low-pressure turbine shaft 17. During this step, the clamping wedge 80 is rotated around the low-pressure turbine shaft 17. In other words, the clamping wedge 80 is moved in rotation around the longitudinal axis C so that the radial teeth or dogs 92 are aligned with the lugs 94 of the low-pressure turbine shaft 17 which then form an axial stop for the radial teeth or dogs 92.

[0105] The clamping wedge 80 is then in axial abutment upstream since the radial teeth 92 come into axial abutment against the lugs 94 of the low-pressure turbine shaft 17 as illustrated in [Fig. 12]. Thus, the upstream faces 92a of the teeth 92 come into abutment against a downstream surface 94b of the lugs 94. The clamping wedge 80 can no longer move upstream.

[0106] During this step of axial immobilization of the clamping wedge 80, the end 17a of the low-pressure turbine shaft 17 is still subjected to the force F5 exerted by the tool 200 to maintain the elongation of the end 17a of the low-pressure turbine shaft.

[0107] [Fig. 13] illustrates the forces sizing this connection. The aerodynamic forces applied to the low-pressure turbine are represented by the arrow F1 and the aerodynamic forces applied to the low-pressure compressor, opposite those of the low-pressure turbine, are represented by the arrow F2. The tightening force of the tightening wedge 80 to overcome the external axial forces is represented by the arrow F3 downstream and the arrow F4 upstream. The arrow F5 illustrates the force exerted by the tool 200 on the end 17a of the low-pressure turbine shaft 17.

[0108] The method continues with a step of locking the clamping wedge 80 in rotation as illustrated in [Fig.14]. This comprises the installation of the first ring 102 then the installation of the second ring 110 of the rotation locking system 100 from upstream to downstream. The first ring 102 is installed in abutment against the first annular face 84 of the clamping wedge 80 so that each second radial tooth 106 of the first ring engages in a second slot 105 of the clamping wedge 80 then in a corresponding radial notch 108 of the low-pressure turbine shaft 17 in order to immobilize the clamping wedge 80 in rotation. The second ring 110 is inserted into the annular groove 112 of the clamping wedge 80 to axially lock the first ring 102.

[0109] Finally, the method ends with a step of releasing the stress, i.e. removing the force F5 applied by the tool as illustrated in [Fig. 15] then removing the tool 200.

[0110] 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. The clamping wedge 80 as well as the members (rings 102 and 110) are clamped against each other to perform, on the one hand, anti-rotation functions and, on the other hand, anti-axial displacement functions.

Claims

Claims

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), - 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), 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 so as 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 upstream end (17a) of the low-pressure turbine shaft (17) comprises a shoulder (150) extending radially inwards,and the locking device (50) comprises: - a clamping wedge (80) centered on the longitudinal axis (C), arranged around the upstream end (17a) of the low-pressure turbine shaft (17), and bearing against an annular projection (60) of the first module (14), and - an additional axial locking system (90) configured to axially immobilize the clamping wedge (80) relative to the low-pressure turbine shaft (17).,

2. Turbomachine (1) according to claim 1, in which the additional axial locking system (90) comprises at least one annular row of radial teeth (92) arranged on the clamping wedge (80) and configured to cooperate by dog-engaging with an annular row of radial slots (93) of the low-pressure turbine shaft (17).

3. Turbomachine (1) according to claim 1 or 2, in which the low pressure compressor shaft (15) comprises the annular projection (60) and the clamping wedge (80) comprises a downstream face (82) bearing directly against an upstream face (60a) of the annular projection (60).

4. Turbomachine (1) according to claim 1 or 2, in which the axial locking device (50) comprises an adjustment shim (170) arranged axially between the clamping wedge (80) and the annular projection (60), the clamping wedge (80) bearing against the annular projection (60) of the first module (14) via the adjusting wedge (170).

5. Turbomachine (1) according to claim 4, in which the low pressure compressor shaft (15) comprises the annular projection (60), the adjustment shim (170) comprises a downstream face (170b) bearing against an upstream face (60a) of the annular projection (60), and the tightening shim (80) comprises a downstream face (82) bearing against an upstream face (170a) of the adjustment shim (170).

6. Turbomachine (1) according to any one of the preceding claims, wherein the locking device (50) comprises a rotation locking system (100) configured to block the rotation of the clamping wedge (80).

7. Turbomachine (1) according to the preceding claim 6, characterized in that the rotation locking system (100) comprises: - a first ring (102), centered on the longitudinal axis (C) and intended to bear against a radial annular face (84) of the clamping wedge (80), the first ring (102) comprising a plurality of radial teeth (106) each intended to engage in a radial notch (105) of the low-pressure turbine shaft (17), and - a second ring (110), centered on the longitudinal axis (C) and received in an annular groove (112) of the clamping wedge (80), the annular groove (112) being formed upstream of the radial annular face (84).

8. A turbomachine (1) according to any preceding claim, wherein the upstream end (17a) of the low pressure turbine shaft (17) extends inside the low pressure compressor shaft (15), the clamping shim (80) being mounted inside the low pressure compressor shaft (15) which comprises the shoulder (60)

9. Method for mounting an aircraft turbomachine (1) according to one of the preceding claims, characterized in that it comprises the steps of: - inserting a tool (200) into the low-pressure turbine shaft (17) so as to position the tool in abutment against the shoulder (150) of its upstream end (17a); - applying a force (F5) from downstream to upstream exerted by the tool (200) against the shoulder (150) of the upstream end (17a); - installing the clamping wedge (80) on the upstream end (17a) of the low pressure turbine shaft (17) from upstream to downstream; - axial immobilization of the clamping wedge (80) relative to the low pressure turbine shaft (17); and - removal of the applied force (F5).

10. Method for mounting a turbomachine (1) according to the preceding claim, comprising a step of locking the clamping wedge (80) in rotation before removing the applied force.

11. Method of mounting a turbomachine (1) according to claim 9 or 10, comprising a step of inserting an additional adjustment shim (170) bearing against the annular projection (60) of the first module (14) before installing the tightening shim.

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