TURBOMACHINE COMPRISING SEVERAL MODULES AND A DEVICE FOR LOCKING THESE MODULES, AND CORRESPONDING DISASSEMBLY PROCEDURE

Abstract

The invention relates to a turbomachine comprising: - a first module including a low-pressure compressor and a low-pressure compressor shaft (15) centered on a longitudinal axis (X), - a second module including a low-pressure turbine and a low-pressure shaft (9) centered on the longitudinal axis and connected to the rotors of the low-pressure turbine and low-pressure compressor, and - a locking device (55) axially immobilizing the low-pressure shaft relative to the low-pressure compressor shaft, the locking device comprising a first nut (56) screwed onto a thread of the low-pressure shaft and bearing against a shoulder of the first module. According to the invention, the locking device comprises: - a second nut (61) screwed onto a thread of the first module and bearing against the first nut to axially immobilize the latter, and - an anti-rotation member (64) configured to hold the second nut against the first nut.Figure for the abbreviation: Figure 2.

Description

Title of the invention: TURBOMACHINE COMPRISING SEVERAL MODULES AND A LOCKING DEVICE THESE MODULES, AND THE CORRESPONDING DISASSEMBLY PROCESS Scope of the invention

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

[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 it to be delivered individually, 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 significant number of engine components. In practice, the turbomachine is configured to be divided into major and minor modules. For example, a turbomachine with an upstream fan (the terms "upstream" and "downstream" refer to the gas flow within the turbomachine) 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 shaft. During an operation of For maintenance, this nut must be unscrewed using a tool that is inserted into the turbine along its longitudinal axis, and therefore inside the low-pressure shaft.

[0005] This maintenance is particularly difficult on a turbomachine including a gearbox and possibly an upstream blade pitch control system. The problem in this case is access to the nut. Access to the nut is achieved with complex tools from upstream of the turbomachine to avoid excessive length and to ensure an acceptable diameter. The tools are inserted through the internal planetary gear of the gearbox, 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 remove the gearbox without disassembling a large part of the turbomachine, including the main downstream module.

[0006] 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.

[0007] 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.

[0008] 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 tools required to access it.

[0009] 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

[0010] We achieve this objective in accordance with the invention by means of a turbomachine, in particular an aircraft turbomachine, the turbomachine having a longitudinal axis and comprising: - a first module comprising a low-pressure compressor and a drive shaft a low-pressure pressor which is centered on the longitudinal axis, - a second module comprising a low-pressure turbine and a low-pressure shaft which is centered on the longitudinal axis X, the low-pressure shaft comprising a downstream end connected to a low-pressure turbine rotor and an upstream end connected to a low-pressure compressor rotor, and - a locking device configured to axially immobilize the low-pressure shaft of the second module relative to the low-pressure compressor shaft of the first module, the locking device comprising a first nut which is screwed onto a thread on the upstream end of the low-pressure shaft and bears against a shoulder of the first module, the locking device comprising: - a second nut which is screwed onto a thread of the first module and which is intended to bear against the first nut in order to axially immobilize the first nut, and - an anti-rotation device which is configured to hold the second nut against the first nut.

[0011] Thus, this solution makes it possible to achieve the aforementioned objective. In particular, this configuration with a captive double nut in a shaft of the second module provides increased modularity. The arrangement of the double nut and the anti-rotation element allows for effective immobilization between the modules and the extraction of a turbomachine component mounted upstream of the first module to access the locking device. This also allows at least one compact tool to be brought inside. More precisely, this configuration allows the first nut to be screwed and unscrewed within a very small radial space. The low-pressure turbine and low-pressure compressor module can therefore be disassembled in fewer operations compared to the other modules and without disassembling the other adjacent modules.This modularity is part of an approach to reducing environmental impact, since it allows only the necessary components to be repaired and checked, thus reducing the turbomachine's downtime.

[0012] The turbomachine according to the invention may comprise one or more of the following features, taken individually or in combination with each other:

[0013] - the first nut and the second nut include handling portions allowing screwing and unscrewing which are radially inside the low pressure compressor shaft.

[0014] - the low-pressure compressor shaft is connected to the low-pressure compressor rotor pressure via a trunnion, the trunnion being integral with the rotor of the low-pressure compressor and an upstream end of the low-pressure compressor shaft pressure.

[0015] - the low-pressure shaft includes an upstream end that extends inside the low pressure compressor shaft, the first nut and the second nut being mounted inside the low pressure compressor shaft which includes the shoulder, the first nut having a downstream face bearing against the shoulder.

[0016] - at least the first nut extends outside the low-pressure shaft.

[0017] - the anti-rotation device includes a nut brake configured so as to im mobilize the rotation of the second nut.

[0018] - the second nut comprises teeth oriented along the longitudinal axis and intended to engage with complementary teeth of the second nut, the nut lock comprising first splines configured to engage with second splines of the low pressure compressor shaft, the nut lock comprising an annular groove intended to receive a split annular ring cooperating with the low pressure compressor shaft.

[0019] - the second nut is allowed to move axially between the anti-rotation member and the first nut over a predetermined distance along the longitudinal axis.

[0020] - the low-pressure compressor shaft includes an internal thread which has a length along the longitudinal axis, the length being at least equal to the predetermined distance and being greater than a length of the second nut.

[0021] - the first and second nuts each comprise an external thread and the shaft The low-pressure compressor includes a first shaft portion which has a length that is twice the length of the external threads of the first and second nuts.

[0022] - the turbomachine includes a blower which is connected to a blower shaft and which is arranged upstream of the first module and the low-pressure compressor, the low-pressure shaft driving the blower shaft in rotation via a speed reducer.

[0023] - the blower is faired.

[0024] - the low-pressure compressor shaft is connected to an input shaft of the reducer speed, the low pressure compressor shaft and the input shaft being fixed together by fixing flanges and a bolted connection.

[0025] - the low-pressure compressor shaft comprises a first annular wall radial whose outer periphery is connected to a first of the fixing flanges, the input shaft comprising a second radial annular wall whose outer periphery is connected to a second of the fixing flanges, said first and second annular walls extending opposite each other and conferring a bending deformation capacity to the second module in operation.

[0026] - the turbomachine element is an input shaft coupled to the compressor shaft low pressure.

[0027] - the reducer is located in a lubrication chamber.

[0028] - the input shaft of the speed reducer has an internal diameter which is smaller than the internal diameter of the low-pressure compressor shaft.

[0029] - the turbomachine includes an upstream module mounted upstream of the first module, the upstream module comprising a blower and a speed reducer.

[0030] - the upstream module includes the input tree.

[0031] - the second nut extends outside the low-pressure shaft.

[0032] - the length L of the internal thread is greater than the length of the external threads of the first and second nuts.

[0033] The invention also relates to an assembly of shafts for an aircraft turbomachine, this assembly comprising:

[0034] - a first shaft having external grooves oriented parallel to a axis of rotation of the shaft,

[0035] - a second shaft comprising internal grooves complementary to said external splines, this second shaft being axially engaged on the first shaft and these shafts being rotationally locked together by the engagement of their splines, and

[0036] - a device for axially locking the shafts against each other, the device for axial locking comprising a first nut mounted on an upstream end of the first shaft and axially locked against an annular shoulder of the second shaft, the axial locking device comprising a second nut mounted on the second shaft and axially locked against the first nut, the locking device further comprising an anti-rotation element for the second nut which is mounted inside the second shaft.

[0037] The invention further relates to an aircraft comprising at least one turbomachine as mentioned above.

[0038] The invention also relates to a method for dismantling a turbomachine as described above, the method comprising the steps of: - disengagement of the anti-rotation device from the second nut in order to move it over a predetermined distance,

[0039] - unscrewing the second nut so as to move it away from the first nut, - unscrewing the first nut so as to axially free the low pressure shaft, - removal of the second module from the first module.

[0040] According to the method, the disengagement and unscrewing steps are carried out with external tools which are respectively introduced inside the low pressure compressor shaft.

[0041] According to the method, the external tools are configured to cooperate with the handling portions of the first and second nuts. Brief description of the figures

[0042] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for an understanding of which reference should be made to the accompanying drawings in which:

[0043] Fig. 1 is a schematic half-view and axial cross-section of an aircraft turbomachine;

[0044] Fig. 2 is a schematic axial cross-sectional view of a set of shafts coupled together according to the invention;

[0045] [Fig.3] is a view similar to that of [Fig.1] and illustrates a first step of a method for dismantling an aircraft turbomachine according to the invention;

[0046] Figure 4 is a view similar to that of Figure 1 and illustrates a second stage of dismantling the turbomachine according to the invention; and

[0047] [Fig.5] is a view similar to that of [Fig.1] and illustrates a third stage of dismantling the turbomachine according to the invention. Detailed description of the invention

[0048] The invention applies to an aircraft turbomachine 1 such as that shown in [Fig. 1] and which is a turbojet equipped with a shrouded fan 2 and a speed reducer 3. Of course, the invention is not limited to a turbojet and can be applied to any type of turbomachine equipped in particular with a speed reducer.

[0049] The turbomachine 1 extends along a longitudinal axis X, which is generally the axis of rotation of its rotors. The turbomachine comprises, from upstream to downstream along the longitudinal axis X and the gas flow, a blower 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.

[0050] The turbomachine 1 is configured with several modules which are assembled together and which facilitate its maintenance.

[0051] With reference to figures 1 and 2, a first module 14 includes the low-pressure compressor 4.

[0052] An upstream module 11 comprises the blower 2 and the speed reducer 3. The latter includes an input shaft 12 (see [Fig. 2]) which is centered on the longitudinal axis X. The input shaft 12 is part of the upstream module 11. The blower 3 includes a blower shaft 13 which is driven in rotation by a low-pressure shaft 9 via the speed reducer 3. The upstream module 11 is mounted upstream of the first module 14.

[0053] A second module 16 comprises the low-pressure turbine 7 and the low-pressure shaft 9, which is centered on the longitudinal axis X. Advantageously, the low-pressure shaft 9 comprises an upstream end 9a connected to a compressor rotor low pressure and a downstream end connected to a low pressure turbine rotor. The upstream end 9a is connected to the input shaft 12 of the speed reducer.

[0054] A third module 17 comprises the high-pressure compressor 5 and the high-pressure turbine 7, whose rotors are connected by a high-pressure shaft 10 and form the high-pressure housing. The third module 17 also comprises the annular combustion chamber 6, which is axially interposed between the high-pressure compressor 5 and the high-pressure turbine 7. The low-pressure shaft 9 extends at least partially inside the high-pressure shaft 10 and they are coaxial.

[0055] According to this configuration, the low-pressure 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.

[0056] The speed reducer 3 (known by the English acronym RGB) advantageously comprises an epicyclic gear train. Of course, the speed reducer could also comprise a planetary gear. The reducer typically includes a sun gear 20 (or inner planet gear), a plurality of sun gears 21 (which are pinions), a sun carrier 22, and an outer ring gear 23 (or outer planet gear). The solar element 20 is centered on the longitudinal axis X. The outer ring 23 is centered on the longitudinal axis X and extends around the solar element 20. The satellites 21 are arranged between the solar element 20 and the outer ring 23 and are carried by the satellite carrier 22. Each satellite 21 is mounted to rotate freely around a satellite axis by means of a bearing and meshes with external teeth of the solar element 20 and internal teeth of the outer ring 23.

[0057] In the present case, the outer ring 23 is fixed and attached to a stator of the turbomachine which is here an inlet housing 24. The solar 20 is mobile in rotation and coupled to the input shaft 12 which itself is connected to the low pressure shaft 9. The planet carrier 22 is also mobile in rotation and coupled to the blower shaft 13. The blower 2 is therefore driven in rotation by the low pressure shaft 9 via the reduction gear.

[0058] 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.

[0059] The reducer 3 of [Fig. 1] is arranged in a lubrication chamber 25 which extends around the longitudinal axis X and therefore has a generally annular shape. The chamber 25 is delimited by the blower shaft 13 and the input shaft 12 at its inner periphery. At its outer periphery, the lubrication chamber 25 is advantageously, but not exclusively, delimited by the inlet housing 24 which extends around the reducer 3. The chamber 25 is delimited upstream by, for example, a first bearing support 26 which is annular. The first bearing support 26 includes an external end which is fixed to the inlet housing 24 and an internal end which retains outer bearing rings of two roller bearings 27.

[0060] Advantageously, the roller bearings 27 include internal rings that are fixed to the blower shaft 13. These bearings provide rotational guidance for at least the blower shaft 13. One of the upstream bearings closest to the speed reducer also provides more stable rotational guidance for the planet carrier. This bearing closest to the reducer is optional.

[0061] Finally, the enclosure 25 is delimited downstream, for example, by a second bearing support 28, which is annular. The second bearing support 28 comprises an external end that is fixed to the inlet housing 24 and an internal end that retains the outer rings of two roller bearings.

[0062] Advantageously, the two downstream bearings allow for the guidance of the input shaft of the speed reducer and the low-pressure compressor shaft (which is integral with the input shaft). The rolling bearings advantageously comprise internal rings that are fixed to different shafts, namely the input shaft and the low-pressure compressor shaft.

[0063] The second bearing support 28 advantageously comprises an annular ferrule 30, the first internal end 30a of which is fixed to the second bearing support 28 and the second end 30b of which cooperates with sealing elements 31. The latter are advantageously installed around a low-pressure compressor shaft 15.

[0064] With reference to [Fig. 1], the enclosure 25 also includes sealing means for hermetically sealing the enclosure 25. These sealing means comprise a first removable cover 32 for hermetically sealing the enclosure upstream, and a second removable cover 33 for hermetically sealing the enclosure downstream. The first cover 32 is advantageously mounted inside the blower shaft 13 and is located near the speed reducer 3 along the longitudinal axis. The second cover 33 is advantageously mounted inside the low-pressure compressor shaft 15 and at one of its downstream ends. This second cover 33 is mounted downstream of the speed reducer 3.

[0065] The low-pressure compressor shaft 15 and the input shaft 12 are both advantageously hollow. The low-pressure shaft 9 is also hollow.

[0066] The turbomachine also includes an intermediate casing 34 which is interposed 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.

[0067] With reference to [Fig.2], a set of turbomachine shafts are connected between They are locked in position relative to each other. The assembly includes a first shaft and a second shaft. In this example, the first shaft is the low-pressure compressor shaft 15 and the second shaft is the low-pressure shaft 9. The assembly also includes a third shaft, which is the input shaft 12.

[0068] First coupling means 40 are configured to connect the first module 14 to the upstream module 11. In particular, the first module 14 comprises (in addition to the low-pressure compressor) a trunnion 41 fixed in rotation to the rotor of the low-pressure compressor and to a low-pressure compressor shaft 9. The low-pressure compressor shaft 9 is fixed to the input shaft 12.

[0069] As shown, the trunnion 41 comprises an inner end 41a which is axially fixed to a downstream end 15a of the low-pressure compressor shaft 15. The latter, centered on the longitudinal axis X, comprises an upstream end 15a which is connected to the input shaft 12 of the speed reducer 3 via a flexible coupling. More specifically, the low-pressure compressor shaft 15 advantageously comprises an annular mounting flange 42 which extends radially outward with respect to the longitudinal axis X. This mounting flange 42 is located on the outer periphery of a radial annular wall 43 which is disposed at the upstream end 15a of the low-pressure compressor shaft 15.

[0070] The input shaft 12 advantageously includes an annular mounting flange 44 extending radially outward from the longitudinal axis X. This mounting flange 44 is located on the outer periphery of a radial annular wall 45, which is disposed at the downstream end 12b of the input shaft 12. The mounting flanges 42, 44 are fastened together by a bolted connection 46. For this purpose, the mounting flanges 42, 44 are pressed against each other along the longitudinal axis and include axial holes (along the longitudinal axis) for receiving axial screws 47 to fasten the mounting flanges together. This configuration of the mounting flanges 42, 44 and the radial annular walls 43, 45 allows for a flexible coupling. Of course, the flexible coupling can be achieved by any removable connection allowing movement between the shafts.Thus, a misalignment can occur between the input shaft 12 and the low-pressure compressor shaft 15, which is particularly relevant in the case of a relatively long engine.

[0071] Fig. 2 also illustrates second coupling means 48 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 shaft 9 and is also axially immobilized relative to the low-pressure shaft 9.

[0072] The low-pressure compressor shaft 15 is coupled to the low-pressure shaft 9 by means of splines. The second coupling means 48 are formed by the splines. In particular, the low-pressure shaft 9 extends at least partially to The interior of 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 X. These are advantageously located at the downstream end 15b of the low-pressure compressor shaft 15.

[0073] These internal splines 49 are configured to engage with corresponding external splines 50 of the low-pressure shaft 9. The external splines 50 are arranged on an external surface of the low-pressure shaft 9 and towards its upstream end 9a. These internal and external splines 49, 50 allow the low-pressure shaft 9 to drive the low-pressure compressor shaft 15 in rotation and transmit the rotational torque.

[0074] In the example shown, the low-pressure compressor shaft 15 comprises a first shaft portion 51a and a second shaft portion 51b. The first portion 51a has an internal diameter DI that is greater than the internal diameter D2 of the second portion 51b. The internal diameter D2 of the second portion 51b is substantially greater than the external diameter of the low-pressure shaft 9.

[0075] We can also see in [Fig.2] that the input shaft 12 has an internal diameter D4 which is advantageously smaller than the internal diameter of the low-pressure shaft 15. More precisely, the internal diameter D4 is smaller than the internal diameter DI of the first portion 51a of the low-pressure compressor shaft 15 and also than the internal diameter D2 of the second portion 51b of the low-pressure compressor shaft 15. The efficiency of the turbomachine is also a function of the radial dimensions of the speed reducer; the diameter of the input shaft 12 must be small to limit the diameter of the outer ring.

[0076] Advantageously, the diameter D4 of the input shaft 12 is a compromise between: - a radius sufficient to allow the rotational torque to pass through, - a radius sufficient to allow the passage of an external tool (described later) inside the input shaft 12, - the smallest possible radius for mass reduction, - the lowest possible radius to allow height for the flexible elements (the height of these elements determines the flexibility of the room).

[0077] Advantageously, the reduction ratio of the speed reducer is between 2.5 and 7. The diameter of the input shaft 12 must be large enough to achieve the desired reduction ratio. A ratio between the ring gear diameter and the diameter of the input shaft 12 is preferably greater than 1.5 to ensure a sufficient reduction ratio.

[0078] An axial locking device 55 is configured to axially immobilize the second module 16 relative to the first module 14. More specifically, the locking device 55 makes it possible to immobilize the low-pressure shaft 9 relative to the low-pressure compressor shaft 15.

[0079] The locking device 55 includes a first nut 56 configured to axially immobilize the low-pressure compressor shaft 15 relative to the low-pressure shaft 9 and to absorb the axial thrust of the low-pressure turbine. The first nut 56 has a rotational axis coaxial with the longitudinal axis X in the installed position. As shown in [Fig. 2], the first nut 56 advantageously has an L-shaped axial cross-section. In this example, a first annular portion 57a ​​extends radially and a second annular portion 57b extends along the longitudinal axis.

[0080] The first nut 56 is screwed onto the low-pressure shaft 9 and is centered on the longitudinal axis. The first nut 56 is arranged radially between the low-pressure compressor shaft 15 and the low-pressure shaft 9. The first nut 56 includes a thread that is screwed onto the second module 16. More specifically, the first nut 56 includes an internal thread 58 that engages with an external thread 59 of the low-pressure shaft 9.

[0081] Advantageously, the internal thread 58 is carried by an internal surface of the second portion 57b of the first nut 56. The external thread 59 is located at the upstream end 9a of the low pressure shaft 9.

[0082] In the present example, the external diameter of the first nut 56 is smaller than the internal diameter of the low-pressure compressor shaft 15 and larger than the external diameter of the low-pressure shaft 9. We can see that the external diameter of the first nut 56 (delimited at least in part by the bottom of the external thread 59) is also larger than the internal diameter D4 of the input shaft 12. This implies that the input shaft 12 will have to be disassembled and removed in order to access the nut 56 and unscrew it and the second module 16. In other words, the first nut 56 is captive inside the low-pressure compressor shaft 15.

[0083] Advantageously, the first nut 56 is of type M70 with a nominal thread diameter of 70 mm.

[0084] In the example shown, the first nut 56 is axially engaged from upstream on the upstream end 9a of the low-pressure shaft 9 and is screwed until it is axially clamped against an annular shoulder 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 shoulder 60 which extends radially towards the X-axis. In the present example, the annular shoulder 60 is formed upstream of the internal and external splines 49, 50. The first nut 56 includes a downstream, annular lateral face 56b, coming into contact with an upstream annular surface 60a of the shoulder 60. The low pressure shaft 9 can no longer move back downstream, nor can the low pressure turbine.

[0085] The locking device 55 includes a second nut 61 configured to immobilize the first nut 56 relative to the low-pressure compressor shaft 15. The second nut 61 is mounted to provide moderate tightening sufficient to prevent the first nut 56 from loosening. To this end, the second nut 61 is mounted upstream of the first nut 56 along the longitudinal axis. The second nut 61 includes an axis of revolution coaxial with the longitudinal axis.

[0086] With reference to [Fig.2], the second nut 61 includes an external thread 62 which engages with an internal thread 63 of the low pressure compressor shaft 15. The internal thread 63 is located towards the upstream end of the low pressure compressor shaft 15. The second nut 61 includes a downstream face 61b, annular, which bears against a corresponding upstream lateral face 56a, annular, of the second portion 57a ​​of the first nut 56.

[0087] Still on [Fig. 2], the second nut 61 also comprises an upstream face 61a (axially opposite the downstream face 61b). Advantageously, it has a plurality of teeth 72 extending axially upstream and distributed regularly around the longitudinal axis. The external diameter (delimited at least in part by the root of the external thread) of the second nut 61 is substantially equal to that of the first nut 56. In other words, the external diameter of the second nut 61 is greater than the internal diameter D4 of the input shaft 12. Furthermore, the second nut 61 is also captive inside the low-pressure compressor shaft 15.

[0088] In Figures 3 and 4, advantageously, the internal thread 63 of the low-pressure compressor shaft 15 has a length L along the longitudinal axis X. In the embodiment, the length L is at least equal to the length L4 of the external thread 62 along the longitudinal axis of the second nut 61. Preferably, the length L of the internal thread 63 is greater than the length L4 of the external thread of the second nut 61. As illustrated, the second nut 61 has an axial length L5 which is greater than the length L4 of the external thread.

[0089] According to another advantageous feature, the length L of the internal thread 63 is greater than the length L6 of the external thread of the first nut 56. The first nut 56 includes an axial length L7 which is greater than the length L6 of the external thread.

[0090] Advantageously, the length L of the internal thread 63 is greater than the length of the external threads of the first and second nuts 56, 61.

[0091] According to yet another advantageous feature and according to [Fig. 3], the first shaft portion 51a of the low-pressure compressor has a length L8 which is twice greater than the length of the external threads of the first and second nuts 56, 61.

[0092] The ratios between at least the lengths of the external threads of the first and second nuts 56, 61, of the length of the first portion of shaft 51a makes it possible to disengage the low pressure shaft 9 and thus to free or extract it without having to uncouple the first and second nuts 56, 61 from the low pressure compressor shaft 15.

[0093] The second nut 61 is engaged axially from upstream in the low pressure compressor shaft 15 and is screwed until it is axially tightened against the upstream lateral face 56a of the first nut 56. The low pressure compressor shaft 15 can no longer move backwards either, nor can the low pressure compressor 15 (i.e., the second nut 61 prevents the low pressure compressor and the low pressure turbine from coming together).

[0094] The locking device 55 includes an anti-rotation member 64 configured to lock the second nut 61 in its position. The anti-rotation member 64 is specifically configured to hold the second nut 61 against the first nut 56 (upstream of the first nut). This prevents the rotation of the second nut 61. Since the second nut 61 is locked in place, this in turn prevents the rotation of the first nut 56 and thus its loosening.

[0095] The anti-rotation member 64 in this example comprises a nut lock 65. Alternatively, the anti-rotation member may be a radial pin or any other element having an analogous function.

[0096] In Figures 2, 4, and 5, the nut lock 65 comprises an annular body having an axis of revolution that is coaxial with the longitudinal axis of the turbomachine. The annular body of the nut lock 65 extends between a first end 65a and a second end 65b along the longitudinal axis. The second end 65b advantageously comprises a plurality of teeth 66 complementary to the teeth 63 of the second nut 61.

[0097] The nut lock 65 is also coupled to the low-pressure compressor shaft 15 by means that facilitate its assembly and disassembly. Here, the means include, for example, at least splines. To this end, the annular body of the nut lock includes external splines 67 (first splines) that are oriented along the longitudinal axis. These external splines 67 are provided on an external surface of the annular body and are evenly distributed around the longitudinal axis X. The external splines 67 engage with corresponding internal splines 68 (second splines) of the low-pressure compressor shaft 15. The external splines 67 are arranged on an internal surface of the low-pressure compressor shaft and towards its upstream end. These splines 67, 68 allow that the nut lock 65 slides inside the low pressure compressor shaft 15.

[0098] The nut lock 65 further advantageously comprises an annular groove 69 centered on the longitudinal axis and intended to receive a ring 70 or split annular segment. The latter is intended to axially retain the nut lock 65 in the second module 16, and here in particular in the low-pressure compressor shaft 15.

[0099] By sliding, the nut lock 65 locks the second nut 61 against rotation. The second nut 61, being prevented from rotating, prevents the first nut 56, which absorbs the forces from the rear of the turbomachine, from loosening. Thus, the nut lock 65 is not directly engaged with the first nut 56. This configuration is advantageous because it is not necessary to align the teeth 66 of the nut lock with any teeth of the first nut 56. Angular precision is not required for an external tool used to screw and tighten the first nut.

[0100] Figures 3 to 5 illustrate disassembly steps for the turbomachine modules. It is understood that the turbomachine modules can be assembled or reassembled by repeating these operations in reverse order. Figure 3 is similar to Figure 2, in which the anti-rotation member 64 (here, a locking nut), the first nut 56, and the second nut 61 are mounted in the low-pressure compressor shaft 15. The first nut 56 is screwed onto the low-pressure shaft 9 and bears against the low-pressure compressor shaft 15. The second nut 61 is screwed onto the low-pressure compressor shaft 15 and bears against the first nut 56. The anti-rotation member 64 is mounted on the low-pressure compressor shaft 15 and engaged with the second nut 61.

[0101] As illustrated in [Fig. 3], a first step of the process consists of inserting an external tool 100 through the low-pressure compressor shaft 15. The tool 100 is shown schematically. The tool 100 has an elongated shape enabling it to reach the anti-rotation element 64, here the nut lock 65. The tool 100 must first pass through the input shaft 12 of the speed reducer 3, which has a very small and compact diameter compared to the diameters of the other shafts. The diameter of the input shaft 12 may have an internal diameter D4 that would be between 20% and 50% smaller than that of the low-pressure compressor shaft 15, for example.

[0102] Prior to inserting the tool 100 into the low-pressure compressor shaft 15, the first cover 32 and the second cover 33 are removed so as to free the inside of the input shaft 12 and the low-pressure compressor shaft 15.

[0103] In [Fig. 4], the method includes a second step of disengaging the nut lock 65 so as to move it from an engaged position to a disengaged position of the second nut 61. The disengagement is carried out with tool 100. which includes at one of its ends a U-shaped end piece 101 intended to couple with an annular collar 71 of the nut lock 5. Once the nut lock 65 is in the disengaged position, the nut lock 65 can slide relative to the low pressure compressor shaft 15 upstream along the longitudinal axis thanks to the internal and external splines 67, 68.

[0104] The nut lock 65 moves away from the second nut 61 by a predetermined distance L1 (see [Fig. 5]), subsequently allowing the second nut 61 to move as well. The predetermined distance L1 is approximately 30 mm. In the example shown in [Fig. 4], the nut lock 65 is located at the upstream end 15a after its movement and is in a waiting position. The nut lock 15 remains centered in the low-pressure compressor shaft 15. For this purpose, the low-pressure compressor shaft 15 includes a groove 73 designed to receive the circlip 70 when the nut lock 65 is in the disengaged position. The groove 73 is centered on the longitudinal axis. The groove 73 is open on the inner surface of the low-pressure compressor shaft 15.

[0105] With reference to [Fig. 5], a third step consists of unscrewing the second nut 61. In this way, the second nut 61 is moved from a tightened position to an unscrewed position. For this purpose, the second nut 61 includes a manipulation portion allowing it to be tightened and unscrewed. Advantageously, the manipulation portion is arranged radially inside the low-pressure compressor shaft 15. In the present example, the manipulation portion includes protrusions 102b (referenced in [Fig. 4]). In this way, the second nut is manipulated from the inside by a suitable tool passing through the small-diameter input shaft.

[0106] The unscrewing step is advantageously carried out using another suitable tool 102, which is also inserted inside the input shaft 12 and the low-pressure compressor shaft 15. This tool 102 is a counter-torque device such as a counter-torque wrench. Any other tool for applying counter-torque to the second nut 61 may be used. The tool 102 includes additional protrusions 102a that engage with the protrusions 102b of the second nut 61. The protrusions 102b extend radially inward from a radially internal surface of the second nut 61.

[0107] In the unscrewed position, the second nut 61 is re-engaged with the nut lock 65 located upstream of the low-pressure compressor shaft 15. The nut 61 has moved (unscrewed and displaced) over at least a predetermined distance L2 (see [Fig. 5]). The second nut 61 also remains centered in the low-pressure compressor shaft 15. This is made possible by the internal thread 63 (for the movement of the second nut 61) which extends over the predetermined distance L2.

[0108] In the present example, the second predetermined distance L2 is twice greater than the first predetermined distance L1.

[0109] According to an advantageous feature, the distance L2 is greater than the length L5 of the second nut 61. According to yet another advantageous feature, the first nut 56 has a length L7 at least equal to the distance L2.

[0110] With reference to [Fig. 6], a fourth step of the process consists of unscrewing the first nut 56. This nut is also moved from a tightening position to an unscrewing position. The first nut 56 includes a manipulation portion that allows it to be tightened and loosened. The manipulation portion is arranged radially inside the low-pressure compressor shaft 15. In the present example, the manipulation portion includes protrusions 103b (referenced in [Fig. 4]). Similarly, the first nut 56 is manipulated from the inside by a suitable tool passing through the small-diameter input shaft.

[0111] This unscrewing step is advantageously carried out using another suitable tool 103 which is also inserted inside the input shaft 12 of the speed reducer and the low-pressure compressor shaft 15. The tool 103 advantageously comprises additional protrusions 103a which engage with the protrusions 103b of the first nut 56. Unscrewing the first nut 56 allows the low-pressure shaft 9 to be axially freed from the second module 16. The protrusions 103b extend radially inwards from a radially internal surface of the first nut 61. The first nut 56 also remains centered in the low-pressure compressor shaft.

[0112] The method includes a step of withdrawing the second module 16 from the first module 14. During this step, the low-pressure shaft 9 is moved downstream. The low-pressure shaft 9 is free to slide along the longitudinal axis relative to the low-pressure compressor shaft 15 by means of the splines 49, 50. For this purpose, another suitable tool 104 is advantageously inserted inside the input shaft 12 and the low-pressure compressor shaft 15. The tool 104 includes protrusions 104a that engage with complementary protrusions 104b of the low-pressure shaft 9 (referenced in [Fig. 4]).

[0113] The method includes a step of separating the fixing flanges 42, 44 from each other. This separation step can take place before the step of disengaging the nut lock 65 or after the step of removing the second module 16.

[0114] After disassembly, the speed reducer 3 and the input shaft 12 can be removed from the rest of the turbomachine illustrated in [Fig. 1]. However, with the locking device and the configuration of the shaft assembly, the second module 16 can be removed without affecting the components of the other modules, which can remain in place. The lubrication chamber 25 can also remain closed, which limits the risk of oil leakage.

[0115] Of course, the different modules of the turbomachine can be separated from each other and can undergo maintenance operations with the reassembly of the turbomachine.

[0116] The disassembly of the second module 16 can be carried out from the downstream side as illustrated in [Fig. 7]. The elements already described above are designated by the same reference numerals. The external tools 100, 102, 103, 104 used to perform the various steps mentioned above could be longer and inserted into the low-pressure shaft. In this case, the high-pressure compressor shaft 15 and the low-pressure turbine are removed. It is then possible to extract the high-pressure housing as a whole, since there is no shaft to divide into several parts for the high-pressure housing. This solution is particularly feasible when an oil transfer bearing (known by the English acronym OTB) is installed upstream of the speed reducer, thus blocking the input shaft.

Claims

Demands

1. Turbomachine (1), in particular aircraft turbomachine, the turbomachine having a longitudinal axis (X) 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 (X), - a second module (16) comprising a low-pressure turbine (8) and a low-pressure shaft (9) which is centered on the longitudinal axis X, the low-pressure shaft (9) comprising a downstream end (9b) connected to a low-pressure turbine rotor and an upstream end (9a) connected to a low-pressure compressor rotor, and - a locking device (55) configured to axially immobilize the low-pressure shaft (9) of the second module (16) relative to the low-pressure compressor shaft (15) of the first module,the locking device (55) comprising a first nut (56) which is screwed onto a thread of the upstream end (9a) of the low-pressure shaft (9) and bearing against a shoulder (60) of the first module (14), characterized in that the locking device (55) comprises: - a second nut (61) which is screwed onto a thread of the first module (14) and which is intended to bear against the first nut (56) so as to axially immobilize the first nut (56), and - an anti-rotation member (64) which is configured so as to hold the second nut (61) against the first nut (56), the anti-rotation member not being directly engaged with the first nut 56.

2. Turbomachine (1) according to claim 1, characterized in that the first nut (56) and the second nut (61) comprise handling portions allowing screwing and unscrewing which are radially inside the low pressure compressor shaft (15).

3. Turbomachine (1) according to any one of the preceding claims, characterized in that the low pressure compressor shaft (15) is connected to the low pressure compressor rotor via a trunnion (41), the trunnion (41) being integral with the low pressure compressor rotor and an upstream end (15a) of the low pressure compressor shaft (15).

4. Turbomachine (1) according to any one of the preceding claims, characterized in that the low-pressure shaft (9) comprises an upstream end (9a) which extends inside the low-pressure compressor shaft pressure (15), the first nut (56) and the second nut (61) being mounted inside the low pressure compressor shaft (15) which includes the shoulder (60), the first nut (56) having a downstream face (56b) bearing against the shoulder (60).

5. Turbomachine (1) according to any one of the preceding claims, characterized in that at least the first nut (56) extends outside the low-pressure shaft (9).

6. Turbomachine (1) according to any one of the preceding claims, characterized in that the anti-rotation member (64) includes a nut brake (65) configured to immobilize the rotation of the second nut (61).

7. Turbomachine (1) according to the preceding claim, characterized in that the second nut (61) comprises teeth (72) oriented along the longitudinal axis and intended to engage with complementary teeth (66) of the nut lock (65), the nut lock (65) comprising first splines (67) configured to engage with second splines (68) of the low pressure compressor shaft (15), the nut lock (65) comprising an annular groove (69) intended to receive a split annular ring (70) cooperating with the low pressure compressor shaft (15).

8. Turbomachine (1) according to any one of the preceding claims, characterized in that the second nut (61) is allowed to move axially between the anti-rotation member (64) and the first nut (56) over a predetermined distance (L2) along the longitudinal axis (X).

9. Turbomachine (1) according to the preceding claim, characterized in that the low pressure compressor shaft (15) includes an internal thread (63) which has a length (L) along the longitudinal axis (X), the length (L) being at least equal to the predetermined distance (L2) and being greater than a length (L5) of the second nut (61).

10. Turbomachine (1) according to any one of the preceding claims, characterized in that the first and second nuts (56, 61) each comprise an external thread and in that the low pressure compressor shaft (15) comprises a first shaft portion (51a) which has a length (L8) which is twice a length (L4, L6) of the external threads of the first and second nuts (56, 61).

11. Turbomachine (1) according to any one of the preceding claims, characterized in that it comprises a blower (2) which is connected to a blower shaft (13) and which is arranged upstream of the first module (14) and the low pressure compressor (4), the low pressure shaft (9) driving the blower shaft (13) in rotation via a speed reducer (3).

12. Turbomachine (1) according to the preceding claim, characterized in that the blower (3) is shrouded.

13. Turbomachine (1) according to any one of claims 11 and 12, characterized in that the low pressure compressor shaft (15) is connected to an input shaft (12) of the speed reducer (3), the low pressure compressor shaft (15) and the input shaft (12) being fixed together by fixing flanges (42, 44) and a bolted connection (46).

14. Turbomachine (1) according to the preceding claim, characterized in that the low pressure compressor shaft (15) comprises a first radial annular wall (43) whose outer periphery is connected to a first of the fixing flanges (42), the inlet shaft (12) comprising a second radial annular wall (45) whose outer periphery is connected to a second of the fixing flanges (44), said first and second annular walls (43, 45) extending opposite each other and conferring a bending deformation capacity to the second module (14) in operation.

15. Method of dismantling a turbomachine (1) according to any one of the preceding claims, characterized in that it comprises the steps of: - disengaging the anti-rotation member (64) from the second nut (61) so as to move it over a predetermined distance (L1), - unscrewing the second nut (61) so as to move it away from the first nut (56), - unscrewing the first nut (56) so as to axially release the low pressure shaft (9), - removing the second module (16) from the first module (14).

16. Method according to claim 15, characterized in that the disengagement and unscrewing steps are carried out with external tools (100, 102, 103, 104) which are respectively introduced inside the low pressure compressor shaft (15).

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