ASSEMBLY FOR AN AIRCRAFT TURBOMACHINE, COMPRISING A SYSTEM FOR AXIALLY LOCKING A PLUG RELATIVE TO A HOLLOW SHAFT OF THE TURBOMACHINE

Abstract

The invention relates to an assembly (30) for an aircraft turbomachine comprising a first part in the form of a hollow shaft (22), a second part (24), as well as a system (20) for coupling the two parts (22, 24), the coupling system comprising a nut (32) for tightening the two parts, the nut (32) being provided with a nut thread (34a) cooperating with a thread (34b) made on the hollow shaft (22), the assembly also comprising a plug (60) closing the hollow (70) of the shaft (22), as well as a system (62) for axially locking the plug (60) relative to the hollow shaft (22). According to the invention, the axial locking system (62) of the cap comprises an axial stop portion (64) provided on the clamping nut (32), as well as at least one axial force transmission element (40, 38) arranged between the cap (60) and the axial stop portion (64) of the clamping nut (32). Figure for abstract: Figure 2.

Description

Title of the invention: ASSEMBLY FOR AN AIRCRAFT TURBOMACHINE, COMPRISING A SYSTEM FOR AXIALLY LOCKING A PLUG RELATIVE TO A HOLLOW SHAFT OF THE TURBOMACHINE Technical field

[0001] The invention relates to assemblies for aircraft turbomachines, comprising a system for axially locking a plug relative to a hollow shaft of the aircraft turbomachine, such as for example a turbojet or a turboprop.

[0002] More particularly, the invention relates to such assemblies also comprising a system for coupling the hollow shaft with a second part of the turbomachine, for example another shaft. By way of example, the two shafts may respectively be a compressor shaft and a turbine shaft coupled within the turbomachine, and belonging to a high pressure body or a low pressure body.

[0003] However, the invention is not limited to this preferred application.

[0004] Another application of the invention lies, for example, in the coupling of a bearing to the hollow shaft of the turbomachine. STATE OF THE PRIOR ART

[0005] Aircraft turbomachine part coupling systems have been widely developed in the prior art. An example of a coupling system is for example disclosed in document FR 2 858 249 AL

[0006] One of the two parts coupled in rotation may be a hollow shaft, which in certain designs should be closed using a plug, in order to prevent the circulation of gas through this shaft. The presence of these gases can lead to pressurization of the plug, which should then be retained by an axial locking system, preventing its translation relative to the hollow shaft on which it is mounted.

[0007] Solutions exist for implementing this locking system, but they remain improvable. Indeed, it is known, for example, to use a circlip as a means of axially stopping the cap, but this solution does not guarantee resistance to high gas pressures, which may be applied to the cap.

[0008] Furthermore, another solution consists of screwing the cap onto the hollow shaft, but in this case, the necessary tapping of the shaft complicates its manufacture, and increases its cost.

[0009] There therefore remains a need to improve the design of the prior art assemblies discussed above. Statement of the invention

[0010] To meet the need mentioned above, the invention firstly relates to an assembly for an aircraft turbomachine comprising a first part in the form of a hollow shaft, a second part, as well as a system for coupling the two parts, the coupling system comprising a nut for tightening the two parts, the nut being provided with a thread cooperating with another thread made on the hollow shaft, the assembly also comprising a plug closing the hollow of the shaft, as well as a system for axially locking the plug relative to the hollow shaft.

[0011] According to the invention, the axial locking system of the cap comprises an axial stop portion provided on the nut, as well as at least one spring arranged between the cap and the nut.

[0012] The proposed technical solution proves to be simple to implement, and inexpensive, in particular because the shaft does not require any particular machining to fulfill the axial locking function of the plug.

[0013] In addition, the use of the clamping nut to axially retain the plug makes it possible to absorb high pressure forces which are likely to be applied to the plug.

[0014] The invention preferably comprises at least any one of the following optional features, taken alone or in combination.

[0015] Preferably, the spring is a spring for transmitting axial forces between the nut and the cap, the spring being arranged between the cap and the axial stop portion of the nut, this spring preferably being a compression spring.

[0016] By introducing such a spring into the axial force transmission chain between the cap and the clamping nut, it is advantageously possible to easily adapt to any force, by correctly dimensioning the spring.

[0017] Preferably, the spring is on the one hand in contact against the axial stop portion and on the other hand in contact against a ring, the ring being arranged axially between the spring and the plug.

[0018] Preferably,

[0019] - the ring is an anti-rotation ring intended to limit / prevent the rotation of the clamping nut relative to the hollow shaft;

[0020] - the spring pushes the anti-rotation ring in compression against the plug, the set comprising:

[0021] - a first rotating coupling member intended to cooperate with a first complementary rotational coupling member provided on the hollow shaft, so as to form a first rotational coupling device, said first coupling member forming an axial stop for the plug; and

[0022] - a second rotating coupling member intended to cooperate with a second complementary rotating coupling member provided on the nut, so as to form a second rotating coupling device.

[0023] Preferably, the coupling system is configured so that the anti-rotation ring:

[0024] - can be placed in a temporary axial position relative to the nut, position in which the first rotating coupling device is in a coupling configuration, while maintaining the second rotating coupling device in a non-coupling configuration; and

[0025] - can be moved relative to the nut, from its temporary axial position to a final axial coupling position after a relative rotation between the ring and the nut, in which position the second rotating coupling device is in a coupling configuration, while maintaining the first rotating coupling device in its coupling configuration.

[0026] Thanks to this preferred design, the possible over-torque to be applied to the nut during assembly advantageously remains moderate, so that the assembly proves to be less mechanically constrained, without however requiring an increase in the pitch / fineness of the anti-rotation means, such as grooves and / or finger-notch assemblies.

[0027] Furthermore, this design is also advantageous in that it allows blind mounting of the coupling system, i.e. without visual access to the area of ​​the turbomachine in which the mounting is carried out. This situation occurs in particular when coupling parts with large diameters, such as two turbomachine shafts.

[0028] Preferably, the first rotational coupling device comprises one or more finger-notch assemblies, the number of these assemblies being preferably less than six, and even more preferably less than four, and / or the second rotational coupling device is formed by splines.

[0029] The reduced number of these finger-notch assemblies, to stop the rotation of the first turbomachine part via the ring, significantly reduces manufacturing costs, particularly compared to a splined solution, which can nevertheless be considered. In addition, the splines remain less expensive to produce on these elements than on the parts to be coupled, such as turbomachine shafts.

[0030] In this embodiment, it is therefore the finger-notch assemblies forming the first coupling device which are first engaged, then it is the splines forming the second coupling device which are engaged after having been matched. The pitch of the splines being smaller than that of the notches, the rotation of the nut to be applied to allow the matching re- sought, and the possible resulting over-torque, remain advantageously low.

[0031] Preferably, in the temporary axial position of the anti-rotation ring, the first coupling member and the first complementary coupling member are intended to provide between them a circumferential clearance allowing, by consumption of this clearance, sufficient angular movement of the anti-rotation ring to allow the second coupling member to be placed in correspondence, in the circumferential direction, with the second complementary coupling member, this correspondence allowing the axial displacement of the anti-rotation ring from its temporary axial position to its final axial coupling position.

[0032] In this solution, it is actually the consumption of the aforementioned clearance which makes it possible, where appropriate, to match the second coupling members with the second complementary coupling member(s). Consequently, advantageously, no over-torque is required on the nut to finalize the assembly of the coupling system.

[0033] It is noted that another solution without play could consist of applying a moderate over-torque on the nut, to finalize the assembly. A hybrid solution is also conceivable, in which the finalization of the assembly of the coupling system may require the consumption of the play, and the application of an over-torque on the nut, of even more moderate intensity.

[0034] Preferably, the nut and the anti-rotation ring are concentric, the anti-rotation ring being inserted inside the nut.

[0035] According to another preferred embodiment of the invention, one axial end of the spring bears on the axial stop portion of the clamping nut, and the other axial end of the spring bears on the cap. Preferably, several springs are distributed around a longitudinal central axis of the assembly, or at least one spring is centered on this axis.

[0036] According to yet another preferred embodiment of the invention, the assembly comprises an intermediate stop ring, comprising a first axial stop portion cooperating with the axial stop portion of the tightening nut, as well as a second axial stop portion cooperating with the plug,

[0037] the assembly being configured so that the intermediate stop ring can be moved between an unlocked position in which the second axial stop portion of the intermediate ring does not cooperate with the plug, and a locked position in which the second axial stop portion of the intermediate ring cooperates with the plug, the spring being configured so as to exert a restoring force which forces the intermediate stop ring towards its locked position.

[0038] The invention also relates to an aircraft turbomachine comprising at least one such assembly. It may for example be a turbojet or a turbo- propellant.

[0039] Other advantages and characteristics of the invention will appear in the detailed non-limiting description below. Brief description of the drawings

[0040] [Fig-1] is a longitudinal sectional view of a turbojet engine;

[0041] [Fig.2] is a longitudinal half-sectional view of an assembly provided on the turbo reactor shown in the preceding figure, this assembly being in the form of a first preferred embodiment of the invention;

[0042] [Fig.3] is a cross-sectional view of the coupling system shown in [Fig.2], and corresponding to the section taken along line III-III of [Fig.2];

[0043] [Fig.4] is a partial perspective view of a clamping nut of the assembly shown in Figures 2 and 3;

[0044] [Fig.5] is a partial perspective view of an anti-rotation ring of the assembly shown in Figures 2 and 3;

[0045] [Fig.6] is a view similar to the previous one, according to an alternative embodiment;

[0046] [Fig.7] is a partial perspective view of one end of a hollow shaft of the tur- bomachine, belonging to the set shown in figures 2 and 3;

[0047] [Fig.8] is a partial perspective view of the assembly shown in Figures 2 and 3;

[0048] [Fig.9]

[0049] [Fig. 10]

[0050] [Fig. 12]

[0051] [Fig. 13] are longitudinal half-sectional views of the assembly shown in [Fig.2], in different successive states during a process of assembling this assembly;

[0052] [Fig. 11] is a cross-sectional view of the assembly shown in [Fig. 10], and corresponding to the section taken along line XI-XI of [Fig. 10];

[0053] [Fig. 14]

[0054] [Fig. 15] are cross-sectional views of the assembly shown in the preceding figures, according to an alternative, and in different successive states during the process of assembling this assembly;

[0055] [Fig. 16]

[0056] [Fig. 17]

[0057] [Fig. 18]

[0058] [Fig. 19] are partial sectional views of the coupling system according to further another alternative, in different successive states during the assembly process of this coupling system;

[0059] [Fig.20] is a longitudinal half-sectional view similar to that of [Fig.2], with the whole being presented in the form of an alternative;

[0060] [Fig.21] is a longitudinal half-sectional view showing the whole of [Fig.20], during its assembly process;

[0061] [Fig.22] is a longitudinal half-sectional view similar to that of [Fig.2], with the assembly being in the form of a second preferred embodiment of the invention;

[0062] [Fig.23] is a longitudinal half-sectional view similar to that of [Fig.2], with the assembly being in the form of a third preferred embodiment of the invention, the axial locking system of the cap being in an unlocked position; and

[0063] [Fig.24] is a longitudinal half-sectional view similar to the previous one, with the axial locking system of the cap in a locked position. DETAILED DESCRIPTION OF THE INVENTION

[0064] Referring firstly to [Fig.l], an aircraft turbomachine 1 is shown. This is a double-flow, double-spool turbojet. However, it could be a turbomachine of another type, for example a turboprop, without departing from the scope of the invention.

[0065] The turbomachine 1 has an axis X around which its various components extend, this axis being called the longitudinal axis of the turbomachine. It comprises, from upstream to downstream along a main direction 5 of flow of the gases through this turbomachine, a fan 3, a low-pressure compressor 4, a high-pressure compressor 6, a combustion chamber 11, a high-pressure turbine 7 and a low-pressure turbine 8.

[0066] Conventionally, after passing through the blower, the air divides into a central primary flow 12a and a secondary flow 12b which surrounds the primary flow. The primary flow 12a flows in a main gas circulation vein 14a passing through the compressors 4, 6, the combustion chamber 11 and the turbines 7, 8. The secondary flow 12b flows in a secondary vein 14b delimited radially outwards by a motor casing, surrounded by a nacelle 9.

[0067] Figures 2 to 8 represent a system 20 for coupling two rotating parts of the turbojet 1, having the same axis of rotation X. This is a first shaft 22 corresponding to a shaft of the low-pressure turbine, and a second shaft 24 corresponding to a shaft of the low-pressure compressor. These two shafts 22, 24 are hollow, and the upstream end of the first shaft 22 is inserted into the downstream end of the second shaft 24, so as to be coupled in translation and in rotation in the axial direction, via the system 20. The two shafts 22, 24, concentric and centered on the X axis, form with their coupling system 20 an assembly 30, the latter also comprising a plug 60 centered on the X axis. The plug closes the upstream end of the first shaft 22, and the assembly 30 also comprises an axial locking system 62 of the plug 60 relative to the shaft 22, a system which will be described later.

[0068] Several assemblies 30 of this type can be provided within the turbojet engine, with coupled parts which can indifferently belong to various modules of the turbojet engine, including the fan, the compressors, the combustion chamber, or even the turbines.

[0069] Here, preference is given to coupling parts with large diameters, and for which visual access to the coupling zone is limited, or even zero. This is the case in particular for the architecture shown partially in [Fig.2], showing the system 20 in a mounted state, in which the two shafts 22, 24 are coupled.

[0070] The coupling system 20 firstly comprises a nut 32 for tightening the two shafts, this nut being centred on the axis X and provided with a first thread 34a, or nut thread, cooperating with a second thread 34b, or first part thread, made on an external surface of the first shaft 22. As can be seen in FIGS. 2 and 8, in the mounted state of the coupling system 20, the downstream end of the nut 32 exerts an axial force on the second shaft 24, and more precisely on an internal shoulder of the latter. This axial force pushes the second shaft 34 downstream against an external shoulder of the first shaft 22, with an axial wedge 36 possibly interposed between the two shoulders, as has been shown as an example in [Fig.2]. The axial tightening intensity of the nut is sufficient to generate the desired coupling between the two shafts 22, 24.

[0071] The system 20 also comprises an anti-rotation ring 38 intended to limit / prevent the rotation of the nut 32, relative to the first shaft 22, in the mounted state of the system 20.

[0072] The anti-rotation ring 38 is centered on the axis X, being arranged at least partly internally in the nut 32, and being capable of being moved axially relative to the latter, in different axial positions. In Figures 2 and 8, the anti-rotation ring 38 adopts its most downstream position relative to the nut 32, corresponding to a final coupling position of the shafts. It is held there by a spring 40 which is part of the axial locking system of the plug, as will be described below.

[0073] In the final coupling position of the ring 38, the latter is thus retained axially relative to the nut 32, thanks in particular to the spring 40, or to any other translational stop system associated with the ring. In this position, a first rotational coupling device is provided, as well as a second device rotating coupling, both in active coupling configuration.

[0074] The first rotational coupling device is constituted by first rotational coupling members 44a produced on the downstream end of the ring 38, and by first complementary rotational coupling members 44b, provided on the upstream end of the first shaft 22. Here, these are preferably finger-notch assemblies, the fingers 44a being preferably provided on the ring 38, and the notches 44b on the first shaft 22, even if an inverse solution can be envisaged. The notches 44b are also called first notches 44b.

[0075] The number of these finger-notch assemblies is preferably less than four, for example three, or two as in the figures. In this case, the two fingers 44a are preferably diametrically opposed, as are their corresponding notches 44b on the upstream end of the first shaft 22, these notches opening axially upstream.

[0076] The fingers 44a, provided at the downstream end of the ring 38, project axially downstream and radially inwards, as shown in the figures.

[0077] The second rotational coupling device is constituted by second rotational coupling members 46a produced on the external surface of the ring 38, and by second complementary rotational coupling members 46b, provided on the internal surface of the nut 32. Here, these are preferably grooves 46a, 46b cooperating with each other, in the form of two concentric annular rows of grooves. Each annular row of grooves 46a, 46b can be uninterrupted over 360°, or extend only over an angular sector less than 360°, or extend over several angular sectors spaced circumferentially from each other. The number of grooves per annular row is high, for example greater than twenty, thirty or forty. The number of grooves is preferably the same for each of the two annular rows of grooves, and this number is strictly greater than that of the number of notches and the number of fingers.

[0078] Each groove extends radially, in the conventional form of a tooth, and more precisely radially outwards for the grooves 46a, and radially inwards for the grooves 46b.

[0079] One of the particularities lies in the fact that the first grooves 46a are axially spaced from the fingers 44a, towards the upstream. Indeed, there is preferably no axial overlap zone between these elements 46a, 44a.

[0080] As indicated previously, the assembly 30 comprises an axial locking system 62 for the plug 60, relative to the shaft 22. This locking system 62 comprises an axial stop portion 64 provided on the nut 32, being made in one piece with the latter, or preferably attached to it, at the upstream end of the nut 32. This is preferably a ring 64 projecting radially towards the end of the nut 32. the inside, from the upstream end of the nut 32. This ring in fact serves as axial support for an upstream end of the compression spring 40 forming an element for transmitting axial forces between the plug 60, and this same ring 64. The system 62 comprises another element for transmitting axial forces, constituted by the aforementioned anti-rotation ring 38. A downstream end of the spring 40 bears against an upstream end of the ring 38, for example in a housing 66 made in the thickness of the latter, and open axially upstream. Thus, the spring 40 pushes the anti-rotation ring 38 in compression against the plug 60.

[0081] As has been shown diagrammatically in [Fig. 5], it may be a question of several springs 40 oriented axially and arranged around the axis X also corresponding to the longitudinal central axis of the assembly 30. These springs 40 are for example distributed uniformly around the axis X.

[0082] Alternatively, as shown in [Fig.6], it may be a larger spring, namely of a diameter similar to that of the upstream end of the ring 38 with which it cooperates. In this case, the spring 40 is centered on the axis X and arranged around the latter.

[0083] The fingers 44a project radially inwards until they penetrate into the hollow 70 of the first shaft 22, that is to say they extend beyond the notches 44b in the radially inward direction. Their radially internal ends thus form axial stops for the plug 60, for example by being axially opposite a peripheral ring 72 of this plug. In the mounted state shown in [Fig. 2], axial clearance may be provided between the plug 60 and the fingers 44a located further upstream. Alternatively, these elements 60, 44a may be in axial contact. In all cases, the spring 40, arranged between the axial stop portion 64 of the nut 32 and the anti-rotation ring 38, forces the latter axially towards the plug 60 and the shaft 22.

[0084] The system 62 which has just been described in fact allows the axial blocking of the plug 60, relative to the shaft 22, and this in the upstream direction in which it can be constrained due to the pressure of the gases in the hollow 70 of this shaft 22. The axial blocking of the plug 60 in the other direction, downstream, proves to be less critical and can therefore be carried out in a conventional manner, for example using a shoulder, a circlip, etc.

[0085] Figures 9 to 13 illustrate the method of mounting the assembly 30.

[0086] First, the system 20 is placed on the first shaft 22, so that the nut 32 surrounds the upstream end of this shaft, then this nut 32 is tightened via the first and second threads 34a, 34b. The objective of this tightening is to axially press the first shaft 22 against the second shaft 24, by pressing the downstream end of the nut against the second shaft 24. The tightening torque applied to the nut 32 corresponds to a minimum torque to ensure the desired coupling of the two shafts. This step is shown diagrammatically by the arrow in [Fig.9]. It can be carried out with the ring 38 already housed in the nut, or inserted into it only after tightening this nut 32.

[0087] In all cases, the ring 38 is inserted axially so that its fingers 44a come into axial support against the upstream end of the first shaft 22.

[0088] The next step is illustrated in Figures 10 and 11. It consists of rotating the ring 38 along the X axis relative to the fixed nut 32, as well as translating it downstream, as shown diagrammatically by the two arrows. The rotation of the ring serves to align the fingers 44a with the notches 44b, after which an axial introduction of the fingers can be carried out in these same notches. This axial movement of the ring in fact leads to bringing the anti-rotation ring 38 into a temporary axial position relative to the nut, thus placing the first rotational coupling device 44a, 44b in its coupling configuration. However, axial movement of the ring 38 is normally stopped by the lack of correspondence between the splines 46a, 46b, as shown in [Fig. 11] in which it is shown that the first splines 46a are not aligned with inter-spline spaces on the other row of second splines 46b, and vice versa. Therefore, in the temporary axial position of the ring 38, the second rotational coupling device 46a, 46b remains in a non-coupling configuration.

[0089] During this step, the rotation and the translation force on the ring 38 can be exerted simultaneously, in particular when these actions take place blindly in the mounting area of ​​the turbojet. These operations can also be implemented with the springs 40 already housed in their respective housings of the ring 38, or these springs can be mounted subsequently.

[0090] To achieve the desired correspondence between the splines 46a, 46b, shown in particular in [Fig. 3], the nut 32 is tightened again against the second shaft 24. An over-torque is thus applied to the nut, of a measured intensity, until the desired correspondence between the splines 46a, 46b is obtained. This step of applying an over-torque to the nut 32 is shown diagrammatically in [Fig. 12].

[0091] The pitch of the grooves being smaller than that of the notches, the rotation of the nut to be applied to allow the desired correspondence between these grooves, and the resulting overtorque, remain advantageously low.

[0092] Then, a new axial displacement of the ring 38 relative to the nut 32 is carried out, from its temporary axial position to its final axial coupling position, so as to make the splines 46a, 46b cooperate together as shown in [Fig. 2]. Here also, it is noted that the rotation of the nut 32 and the application of the translational force on the ring 38 can be exerted simultaneously, in particularly when these actions are carried out blindly in the turbojet assembly area.

[0093] At the end of this step, the second rotational coupling device 46a, 46b is in its coupling configuration, due to the cooperation between the splines. Similarly, the first rotational coupling system 44a, 44b remains in its coupling configuration, after its fingers 44a have been further inserted into their respective notches 44b, following the additional axial displacement of the ring 38 relative to the nut 32.

[0094] Once this state is obtained, the axial stop portion 64 is mounted at the upstream end of the nut 32, axially constraining the springs 40 to bear on the ring 38. This makes it possible both to maintain the entire system 20 in a mounted state, ensuring the translational and rotational coupling of the two shafts 22, 24, without risk of loosening the nut 32, and also the activation of the axial locking system 62 of the plug 60. This final step is shown in [Fig. 13]. As indicated previously, the activation of the system 62 is obtained by axially matching the fingers 44a with the plug 60, which may be required to support significant loads, in particular pressure loads, which the locking system 62 must be able to withstand.

[0095] Figures 14 and 15 represent an alternative, the design of which advantageously does not require the application of an over-torque on the nut, for finalizing the assembly of the coupling system 20.

[0096] This alternative has many technical characteristics in common with the embodiment shown in Figures 2 to 13, and moreover, in the figures, the elements which bear the same numerical references correspond to identical or similar elements.

[0097] In the alternative of Figures 14 and 15, it is shown the existence, in the temporary axial position of the ring 38, of a circumferential clearance 48 between each finger 44a and its corresponding notch 44b. This arrangement allows, by partial or total consumption of the clearance 48, sufficient angular movement of the ring 38 relative to the nut 32 remaining fixed, to allow the splines 46a, 46b to be placed in correspondence, still in the circumferential direction. After such an operation, the coupling system 20 adopts a state such as shown in [Fig. 15]. In this respect, it is noted that the circumferential direction, which extends around the axis X, also corresponds to the tangential direction.

[0098] As indicated previously, the desired correspondence between the grooves 46a, 46b allows the axial displacement of the anti-rotation ring 38, from its temporary axial position to its final axial coupling position.

[0099] It is noted that a hybrid solution is also possible, in which the implementation correspondence of the grooves 46a, 46b is obtained on the one hand thanks to the rotation of the ring 38 by consuming the aforementioned clearance 48, and on the other hand thanks to the application of a slight over-torque on the nut 32.

[0100] Figures 16 to 19 represent different states of the coupling system 20 according to another alternative, in which each finger 44a and its corresponding notch 44b have inclined circumferential stop surfaces, forming an angle with respect to the axial direction. In other words, each of these two surfaces 52a, 52b forms an angle of non-zero value with the axial direction, parallel to the X axis.

[0101] The inclined circumferential abutment surfaces 52a, 52b are shown in [Fig. 16]. They are parallel or substantially parallel, and respectively constituted by a lateral flank of the finger 44a, and by a lateral flank 68 of the notch 44b. The inclination of the circumferential abutment surface 52b of the notch 44b is such that it widens circumferentially when going axially upstream. Conversely, the inclination of the circumferential abutment surface 52a of the finger 44a is such that it narrows circumferentially when going axially downstream.

[0102] The position of [Fig. 16] corresponds to that of [Fig. 9], in which the finger 44a is not yet in correspondence with its associated notch 44b. When such a correspondence is reached following the rotation of the ring 38, under the effect of the operator, the finger 44a is partially introduced into the notch 44b, as has been shown diagrammatically in [Fig. 17]. The axial introduction is stopped by the stop between the splines. The circumferential clearance 48 observed between the inclined circumferential stop surfaces 52a, 52b can then be consumed, partially or completely by rotation of the ring 38, in order to bring these same splines (not shown in FIGS. 16 to 19) into correspondence. This step is shown diagrammatically in [Fig. 18]. Then, when the correspondence between the grooves is obtained, the ring 38 is moved axially to its final axial coupling position, still by the operator or under the effect of the compression of the springs 40.This position is reached when the circumferential abutment surfaces 52a, 52b come into contact with each other as shown in [Fig. 19], this contact being preferentially surface-based.

[0103] Due to the inclination of the contact surfaces 52a, 52b, the finger 44a in abutment, on the lateral flank of the notch 44b, exerts on the shaft 22 via the springs 40 an inclined force with a circumferential component. This component has a direction such that the finger 44a forces the second shaft 22 in a direction of rotation leading the nut 32 to tighten more on this shaft 22.

[0104] [Fig. 20] represents an alternative for the production of the assembly 30. The springs 40 are here held by an axial rim 80 extending upstream from the internal radial end of the axial stop portion 64 provided on the nut 32. The axial rim 80 can be annular, centered on the axis X. All these elements can be made from a single piece, and together they define an annular cavity open axially upstream, in which the upstream end of the springs 40, or of the single spring 40, is housed.

[0105] This alternative allows the implementation of a mounting method identical or similar to that described previously for the first preferred embodiment of [Fig.2]. Alternatively, just as for this first embodiment, this alternative also allows the ring 38 to be mounted first on the first shaft 22 so as to place this ring in the temporary axial position in which the first rotational coupling device 44a, 44b is in the coupling configuration. Then, the nut 32 is put in place around the ring 38 with its springs 40, so as to screw this nut onto the first shaft 22, until a minimum tightening is obtained.During this screwing, the second rotating coupling device 46a, 46b remains in its non-coupling configuration, and it is only when a slight over-torque is applied to the nut 32 that the second coupling device 46a, 46b switches into its coupling configuration, thanks to the correspondence obtained between its grooves 46a, 46b, and to the axial force generated by the springs 40 on the ring 38 which can then move axially.

[0106] Another mounting possibility for this alternative, just as for the first preferred embodiment described previously, lies in the application of a minimal tightening of the nut 32 on the shaft 22 with the second rotational coupling device 46a, 46b in its coupling configuration, and the first rotational coupling device 44a, 44b in its non-coupling configuration. Such a step is shown diagrammatically in [Fig. 21]. It is followed by a step of applying an over-torque on the nut 32, so as to obtain the correspondence between the fingers 44a and the notches 44b, in order to tilt the first rotational coupling device 44a, 44b into its coupling configuration, also under the effect of the axial displacement of the ring 38 thanks to the springs 40.

[0107] In order to facilitate the rotation of the nut 32 despite the presence of the axially constrained springs 40, the axial stop portion 64 can be equipped with a support part 65 for the springs, free to rotate relative to this axial stop portion 64. This advantageously avoids the rotation of the springs 40 around the axis X, when tightening the nut 32. An identical or similar solution can be provided for the first preferred embodiment, without departing from the scope of the invention.

[0108] Referring now to [Fig. 22], a second preferred embodiment of the invention is shown, in which the anti-rotation ring 38 is no longer implemented. The nut 32 remains screwed onto the first shaft 22 via the corresponding threads 34a, 34b, and within the axial locking system 62 of the plug 60, only one or more springs 40 are provided to form the axial force transmission elements.

[0109] Indeed, an upstream end of each spring 40 is in support and preferably in contact with the axial stop portion 64 of the nut 32, and its downstream end is in support on the plug, and also preferably in contact with the latter.

[0110] Here also, it may be a question of several springs 40 oriented axially and arranged around the axis, or it may be a larger spring, centered on the axis X and arranged around the latter.

[0111] A third preferred embodiment of the invention is shown in Figures 23 and 24.

[0112] In this third embodiment, one or more springs 140 are also provided, but no longer as axial force transmission elements arranged between the plug 60 and the axial stop portion 64 of the nut 32. These springs 140, preferably oriented radially and operating in compression, nevertheless still form part of the axial locking system 62 of the plug 60. They are arranged around the axis X, preferably distributed uniformly, with an external radial end bearing against the nut 32, and an internal radial end bearing against a ring 90 forming an axial force transmission element of the locking system 62. They are called actuating springs 140.

[0113] More precisely, the intermediate stop ring 90 comprises a first axial stop portion 92, arranged upstream, cooperating with the axial stop portion 64 of the nut 32. As can be seen in FIGS. 23 and 24, the outer radial end of the first axial stop portion 92 is in fact housed in an annular groove 93 of the nut, opening radially inwards and one of the side walls of which forms the axial stop portion 64. The intermediate ring 90 also comprises, offset downstream, a second axial stop portion 94, cooperating with the plug 60. Indeed, this second stop portion 94 also extends radially, and its radially inner end is housed in an annular groove 96 of the plug 60, open radially outwards.

[0114] The assembly 30 is configured such that the intermediate stop ring 90 can be moved between an unlocked position shown in [Fig.23], and a locked position shown in [Fig.24].

[0115] To move from the locked position to the unlocked position, the springs 140 are radially stressed. Thus, the release of this stress allows, thanks to the actuating springs 140, the locking system 62 to automatically switch into the locked position, due to the cooperation of each portion 92, 94 with its corresponding groove 93, 96.

[0116] In this regard, it is indicated that this preferred embodiment could be implemented without the annular groove 96 on the plug 60, without departing from the scope of the invention.

[0117] Of course, various modifications may be made by those skilled in the art to the invention which has just been described, solely by way of non-limiting examples, and the scope of which is defined by the appended claims. In particular, the technical characteristics of the different embodiments and their alternatives are interchangeable and combinable.

Claims

Claims

1. An assembly (30) for an aircraft turbomachine comprising a first part in the form of a hollow shaft (22), a second part (24), and a system (20) for coupling the two parts (22, 24), the coupling system comprising a nut (32) for tightening the two parts, the nut (32) being provided with a thread (34a) cooperating with another thread (34b) made on the hollow shaft (22), the assembly also comprising a plug (60) closing the hollow (70) of the shaft (22), and a system (62) for axially locking the plug (60) relative to the hollow shaft (22), characterized in that the axial locking system (62) of the plug (60) comprises an axial stop portion (64) provided on the nut (32), and at least one spring (40, 140) arranged between the plug (60) and the nut (32).

2. Assembly according to claim 1, characterized in that the spring (40) is a spring (40) for transmitting axial forces between the nut (32) and the cap (60), the spring (40) being arranged between the cap (60) and the axial stop portion (64) of the nut (32).

3. Assembly according to claim 2, characterized in that the spring (40) is on the one hand, in contact against the axial stop portion (64) and on the other hand, in contact against a ring (38), the ring (38) being arranged axially between the spring (40) and the plug (60).

4. An assembly according to claim 3, characterized in that - the ring (38) is an anti-rotation ring intended to limit / prevent rotation of the nut (32) relative to the hollow shaft (22); - the spring (40) pushes the anti-rotation ring (38) in compression against the plug (60), the assembly further comprising: - a first rotation coupling member (44a) intended to cooperate with a first complementary rotation coupling member (44b) provided on the hollow shaft (22), so as to form a first rotation coupling device, said first coupling member (44a) forming an axial stop for the plug (60); and - a second rotation coupling member (46a) intended to cooperate with a second complementary rotation coupling member (46b) provided on the nut (32), so as to form a second rotation coupling device.

5. Assembly according to claim 4, characterized in that the system coupling is configured so that the anti-rotation ring (38): - can be placed in a temporary axial position relative to the nut (32), in which position the first rotational coupling device (44a, 44b) is in a coupling configuration, while maintaining the second rotational coupling device (46a, 46b) in a non-coupling configuration; and - can be moved relative to the nut (32), from its temporary axial position to a final axial coupling position after a relative rotation between the ring (38) and the nut (32), in which position the second rotational coupling device (46a, 46b) is in a coupling configuration, while maintaining the first rotational coupling device (44a, 44b) in its coupling configuration.

6. An assembly according to claim 4 or 5, characterized in that the first rotational coupling device (44a, 44b) comprises one or more finger-notch assemblies, the number of these assemblies being preferably less than six, and even more preferably less than four, and / or in that the second rotational coupling device (46a, 46b) is formed by grooves.

7. Assembly according to claim 2, characterized in that one axial end of the spring (40) bears on the axial stop portion (64) of the nut (32), and the other axial end of the spring (40) bears on the plug (60).

8. Assembly according to any one of claims 2 to 7, characterized in that several springs (40) are distributed around a longitudinal central axis (X) of the assembly, or in that at least one spring (40) is centered on this axis (X).

9. An assembly according to claim 1, characterized in that it comprises an intermediate stop ring (90), comprising a first axial stop portion (92) inserted into the axial stop portion (64) of the tightening nut (32), as well as a second axial stop portion (94) cooperating with the plug (60), the assembly being configured so that the intermediate stop ring (90) can be moved between an unlocked position in which the second axial stop portion (96) of the intermediate ring (90) does not cooperate with the plug (60), and a locked position in which the second axial stop portion (94) of the intermediate ring (90) cooperates with the plug, the spring (140) being configured so as to exert a restoring force which forces the intermediate stop ring (90) towards its locked position.

10. Aircraft turbomachine (1) comprising at least one assembly (30) according to any one of the preceding claims.

Images