FR3018313A1 - HOLLOW TREE LINE FOR AIRCRAFT TURBINE, COMPRISING ANTI-ROTATION RING COUPLED WITH AN INTERNAL CLAMP NUT - Google Patents

Abstract

The invention relates to a hollow shaft line (14) for an aircraft turbomachine, comprising a first hollow shaft (30), a second hollow shaft (32), and means (34) for assembling the shafts, comprising a nut (40) for axially clamping the shafts, comprising an external thread (46) screwed onto an internal thread (48) of the first shaft, and comprising a clamping flange (49) bearing axially against the second shaft; - an anti-rotation ring (42) housed inside the second shaft (32), comprising axial projections (50) housed in female parts (52) made on the nut (40), the ring also comprising radial protrusions (54) housed in female portions (56) on an inner surface of the second shaft (32); and - an axial stop segment (44) of the ring (42).

Description

FIELD OF HOLLOW TREES FOR AIRCRAFT TURBOMACHINE, COMPRISING AN ANTI-ROTATION RING COUPLEE WITH AN INTERNAL CLAMP NUT DESCRIPTION TECHNICAL FIELD The invention relates to the field of hollow shaft lines for aircraft turbomachines, and in particular to means of assembly between the various trees of the line. The invention applies to any type of turbomachine, and in particular to those comprising non-careened contra-rotating blowers, these turbomachines being conventionally called "open rotor". STATE OF THE PRIOR ART In the prior art, there are numerous solutions for assembling and securing two shafts of the same line of shafts for aircraft turbomachines. An exemplary embodiment is for example known from document FR 2 857 708. Nevertheless, there is a need to simplify the design of the assembly means of the trees constituting the line, and to make them more suitable for a complex environment offering only limited access. This is particularly the case for tree lines of open rotor turbomachines. SUMMARY OF THE INVENTION To this end, the subject of the invention is a line of hollow shafts for aircraft turbomachines, comprising a first hollow shaft, a second hollow shaft, and means for assembling the first and second shafts. hollow, said first and second hollow shafts being substantially coaxial, one mounted upstream of the other, said assembly means comprising: - axial clamping means, preferably an axial clamping nut of the first and second hollow shafts the nut comprising an external thread screwed onto an internal thread of one of said first and second shafts, and comprising a clamping flange bearing axially against the other of said first and second shafts; anti-rotation means, preferably an anti-rotation ring housed inside the second hollow shaft and intended to block the rotation of the clamping nut with respect to this second shaft, the ring comprising at least one projection axial direction towards the first hollow shaft, said axial projection being housed in a corresponding first female part formed on the clamping nut, the ring also comprising at least one radial projection housed in a corresponding second female part made on an inner surface of the second hollow tree ; and - axial stop means, preferably an axial stop segment of the anti-rotation ring, the stop segment being housed in a groove formed on the inner surface of the second hollow shaft. The invention thus proposes a simple, inexpensive solution of small size and easy to implement from inside the line of hollow shafts.

It is therefore particularly suitable for open rotor turbines, in which access to the lines of coaxial shafts is very limited. Nevertheless, it is only a preferred, non-limiting application of the invention. Preferably, said assembly means also comprise a first thread provided at one end of the first hollow shaft and a second thread provided at one end of the second hollow shaft, the first and second threads being screwed to one another. in a direction opposite to the screwing direction of the tightening nut. In this way, the rotation between the two hollow shafts, in the direction leading to unscrewing of the first and second threads, causes a tightening of the nut. The risk of loosening hollow shafts of the line are therefore extremely limited. Preferably, said axial and radial projections are fingers. Preferably, said first female portion formed on the clamping nut is a notch opening axially and radially outwardly, and said second female portion formed on the inner surface of the second hollow shaft is a notch opening axially and radially to inside. Preferably, the anti-rotation ring comprises a plurality of axial projections regularly distributed about a central axis of the shaft line, and a plurality of radial projections regularly distributed about this axis. The regular spacing of the projections and the fingers makes it possible to limit the appearance of imbalances and facilitates the balancing of the turbomachine. Preferably, the stop segment is split, which facilitates its establishment in the groove provided for this purpose.

Preferably, the external thread of the axial clamping nut is screwed onto the internal threading provided on the first hollow shaft. Alternatively, the internal thread could be made on the second hollow shaft, without departing from the scope of the invention. Preferably, the first hollow shaft is an upstream shaft of the shaft line and the second shaft is a downstream shaft, or vice versa. The invention also relates to an aircraft turbomachine, preferably of the non-careened counter-rotating fan type, comprising at least one hollow shaft line such as that described above. Finally, the invention relates to a method of mounting such a line of hollow shafts, comprising the following steps, consisting of: - setting up first and second hollow shafts end to end; - Screw the clamping nut, after having introduced inside said other of the first and second hollow shafts, by an end thereof opposite to that for connection with said one of the first and second hollow shafts; inserting the anti-rotation ring inside said second hollow shaft, at one end thereof opposite to that for connecting with said first hollow shaft, then axially moving said anti-rotation ring until the insertion of the axial and radial projections in their respective female parts; and - inserting the axial stop segment inside said second hollow shaft, by the end thereof opposite to that for connection with said first hollow shaft, and axially moving this segment to its insertion in the groove of the inner surface of the second hollow shaft. Other advantages and features of the invention will become apparent in the detailed non-limiting description below.

BRIEF DESCRIPTION OF THE DRAWINGS This description will be made with reference to the appended drawings among which; FIG. 1 represents a schematic perspective view of an aircraft turbomachine with a doublet of non-keeled contra-rotating propellers, according to a preferred embodiment of the invention; - Figure 2 shows a schematic longitudinal half-sectional view of the turbomachine shown in the previous figure; - Figure 3 shows an exploded perspective view of one of the shaft lines of the turbomachine shown in the preceding figures; - Figure 4 is an exploded longitudinal sectional view of the shaft line shown in Figure 3; FIG. 5 is a view similar to that of FIG. 4, with the elements constituting the line of shafts represented in assembled configuration; FIG. 6 is an enlarged view showing part of the assembly means of the shafts of the line; and FIG. 7 is an exploded perspective view of part of these assembly means. DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS Referring firstly to Figure 1, there is shown an aircraft turbine engine 1, according to a preferred embodiment of the invention. This is a preferred solution in which the turbine engine is open rotor, that is to say, it comprises, as a receiver, a pair of non-keeled counter-rotating propellers.

The main constituents of this type of turbomachine are known from the prior art. Consequently, only a brief description will be made with reference to FIGS. 1 and 2. Throughout the following description, the terms "upstream" and "downstream" are to be considered according to a main direction of flow. gases through the turbomachine, this direction being referenced by the arrow 2 in the figures. The turbomachine 1 has a longitudinal axis 3 around which its various components extend. It comprises, upstream downstream in the direction 2, a low pressure compressor 4, a high pressure compressor 6, a combustion chamber 8, a high pressure turbine 10 and a low pressure turbine 12. The low pressure compressor 4 and the low-pressure turbine 12 are connected by a low-pressure hollow shaft line 14a, while the high-pressure compressor 6 and the high-pressure turbine 10 are connected by a high-pressure hollow shaft line 14b. At the downstream end of the gas generator, the turbine engine 1 comprises a receiver 16 of the doublet type of non-keeled contra-rotating propellers. This receiver 16 comprises first of all a free power turbine 18 supplied with the gases leaving the aforementioned low-pressure turbine. The free turbine 18 drives a reduction gear 20 of the epicyclic gear type, which in turn drives an upstream propeller 22 and a downstream propeller 24. Each of the two propellers 22, 24 has a line of hollow shafts 14c, 14d, arranged around each other. a fixed hollow shaft line 14e, the three lines 14c-14e being coaxial and nested one inside the other, with a small radial clearance therebetween. As an indication, it is noted that the inner fixed line 14e serves as a passage to easements, including the crossing of a sleeve 28 dedicated to the receipt and passage of these easements. The fixed line 14e supports, via one or more bearings, the rotary line 14d, itself supporting the rotary line 14c, also via one or more bearings. The invention lies in the particular design of a hollow shaft line, intended to constitute all or part of any of the lines 14a-14e described above. This is preferably line 14e. This line of hollow shafts, referenced 14 in FIGS. 3 to 6, here comprises two coaxial hollow shafts and arranged end to end. This is a first shaft 30 or upstream shaft, and a second hollow shaft 32 or downstream shaft. These two shafts 30, 32, centered on the axis 3, are mounted on one another and secured by assembly means of the invention, which will be described with reference to FIGS. 3 to 7. two shafts 30, 32 are substantially coaxial and mounted in series, one upstream of the other.

The assembly means 34 comprise firstly a threaded connection between the two ends of the shafts 30, 32. Also, there is provided a first external thread 36 on the end 30a of the first shaft 30, as well as a second thread. 38 on the end 32a of the second shaft 32, the first and second threads 36, 38 being screwed one on the other to form the threaded connection.

Furthermore, the means 34 comprise a clamping nut 40, an anti-rotation ring 42 and an axial stop segment 44, all housed inside the line of shafts 14. More specifically, the nut axial clamping means 40 of the first and second hollow shafts comprises an external thread 46, screwed on an internal thread 48 of the end 30a of the first hollow shaft 30. In addition, the nut 40 has a clamping flange 49 projecting radially towards the outside, in the form of flange and in axial support against an inner shoulder 51 of the end 32a of the second hollow shaft 32. In addition, the anti-rotation ring 42 housed inside the second hollow shaft 32 is intended for blocking the rotation of the clamping nut 40, along the axis 3, relative to this second shaft. The ring 42 includes a plurality of finger-shaped axial projections 50 toward the first hollow shaft. These fingers 50 are evenly spaced about the axis 3, and are respectively housed in corresponding first female portions in the form of notches 52, made on the clamping nut 40. These notches 52, made on the back of the collar 49, are open axially downstream and radially outwardly. It is for example provided three or four axial fingers 50. In addition, the ring 42 comprises a plurality of radial projections also in the form of fingers 54, projecting radially outwardly and respectively housed in corresponding second female portions in the form of fingers. notches 56, formed on the inner surface of the second hollow shaft 32. Specifically, the notches 56 open radially inward and axially downstream at an inner shoulder 60 of the inner surface of the second hollow shaft 32. Also, when the nut 40 is tightened and the anti-rotation ring 42 cooperates with this nut, the fingers and notches 50, 52 couple in rotation the nut 40 and the ring 42, while the fingers and notches 54 , 56 couple in rotation the ring 42 and the second hollow shaft 32. The nut 40 is integral in rotation with the second hollow shaft 32, along the axis 3. Moreover, it is preferentially made so that the first hollow shaft 32 t second threads 36, 38 formed on the shafts 30, 32 are screwed to one another in a screwing direction opposite to the screwing direction of the nut 40. Also, in case of relative rotational movement between the two 30, 32 tending to loosen the nut, the same movement tends to tighten the threads 36, 38 and thus reinforces the axial clamping of the two shafts 30, 32, blocking resulting from the two antagonistic effects. Such a blocking occurs analogously when parasitic phenomena, for example the vibratory environment, tend to loosen at the threaded connection 36, 38. In this case, the blockage is indeed produced by the simultaneous tightening of the nut 40 The radial fingers 54 are also uniformly distributed around the axis 3, for example being provided in the number of three or four, arranged at angular positions which are preferably identical to those of the axial fingers 50.

Finally, the stop segment 44 is housed in a groove 64 of the inner surface of the second shaft 32. This segment 44 blocks the axial displacement of the anti-rotation ring 42 downstream, this ring 42 being then clamped , preferably with a small axial clearance, between the segment 44 and the flange 49 of the nut 40. The stop segment 44 preferably takes the form of a split ring segment, the setting up of which simply by forcing it radially inwards, then releasing the stress so that its elastic expansion forces it to enter the groove 64 centered on the axis 3. In this respect, it is indicated that after screwing the two shafts 30, 32 to one another via the threads 36, 38, the positioning of each of the elements 40, 42, 44 is easily effected from the end 32b of the second hollow shaft 32, opposite the first end 32a. Once introduced into the line 14 by this end 32b, the elements 40, 42, 44 are moved axially upstream until they cooperate with their corresponding elements. The nut 40 is first screwed, the ring 42 is then moved until its fingers 50, 54 cooperate with the corresponding notches 52, 56, and the stress applied on the stop segment 44 is released when this The latter is next to the groove 64. The assembly process is thus simplified to the extreme, and requires no access from the outer zone located around the hollow shaft line 14. All the elements are in fact introduced at the end. the interior of the line 14 through the end 32b of the hollow shaft 32. Of course, various modifications may be made by those skilled in the art to the invention which has just been described without departing from the scope of the presentation of the invention.

Claims (10)

REVENDICATIONS1. A hollow shaft line (14) for an aircraft turbomachine, comprising a first hollow shaft (30), a second hollow shaft (32), and means (34) for assembling said first and second hollow shafts, said first and second hollow shafts (30, 32) being substantially coaxial, one mounted upstream of the other, characterized in that said connecting means (34) comprise: - means (40) for axial clamping of the first and second hollow shafts (30, 32), said means (40) comprising an external thread (46) threaded on an internal thread (48) of one (30) of said first and second shafts (30, 32), and comprising a clamping flange (49) axially against the other (32) of said first and second shafts; anti-rotation means (42) housed inside the second hollow shaft (32) and intended to block the rotation of the clamping means (40) with respect to this second shaft (32), the anti-rotation means ( 42) comprising at least one axial projection (50) towards the first hollow shaft (30), each axial projection being accommodated in a corresponding first female part (52) on the clamping means (40), the anti-rotation means (42) further comprising at least one radial projection (54) housed in a corresponding second female portion (56) provided on an inner surface of the second hollow shaft (32); and - means (44) for axial stop of the anti-rotation means (42), the axial stop means being housed in a groove (64) formed on the inner surface of the second hollow shaft (32). 2. hollow shaft line according to claim 1, characterized in that said axial clamping means (40) is a nut, in that said anti-rotation means (42) is an anti-rotation ring, and in that said axial stopping means (44) is an axial stopping segment. 3. hollow shaft line according to claim 2, characterized in that said connecting means (34) also comprise a first thread (36) provided at an end (30a) of the first hollow shaft (30) and a second threading (38) provided at one end (32a) of the second hollow shaft (30), the first and second threads (36, 38) being screwed to one another in a screwing direction opposite to the screwing direction of the clamping nut (40). Hollow shaft line according to claim 2 or 3, characterized in that said axial and radial projections (50, 54) are fingers. 5. hollow shaft line according to any one of claims 2 to 4, characterized in that said corresponding first female part (52) formed on the clamping nut (40) is a notch opening axially and radially to the outside, and in that said second corresponding female portion (56) formed on the inner surface of the second hollow shaft (32) is a notch opening axially and radially inwards. 6. hollow shaft line according to any one of claims 2 to 5, characterized in that the anti-rotation ring (42) comprises a plurality of axial projections (50) regularly distributed about a central axis (3). of the shaft line (14), and in that it comprises a plurality of radial projections (54) regularly distributed about this axis. 7. Shaft lines according to any one of claims 2 to 6, characterized in that the stop segment (44) is split. 8. hollow shaft line according to any one of claims 2 to 7, characterized in that the external thread (46) of the axial clamping nut (40) is screwed onto the internal thread (48) provided on the first hollow shaft (30). 9. An aircraft turbomachine (1), preferably of the non-careened counter-rotating fan type, comprising at least one hollow shaft line (14) according to any one of the preceding claims. 10. A method of mounting a hollow shaft line (14) according to any one of claims 2 to 8, comprising the following steps, consisting of: - set up first and second hollow shafts (30, 32) end to end ; - screw the tightening nut (40), after having introduced it inside said other (32) of the first and second hollow shafts (30, 32), by one end (32b) thereof opposite to that (32a) for connecting with said one (30) first and second hollow shafts; - inserting the anti-rotation ring (42) inside said second hollow shaft (32), by an end (32b) thereof opposite that (32a) for connection with said first hollow shaft (30), then axially moving the anti-rotation ring (42) to the insertion of the axial and radial projections (50, 54) into their respective female portions (52, 56); and - inserting the axial stop segment (44) inside said second hollow shaft (32), by the end (32b) thereof opposite to that (32a) serving to connect with said first hollow shaft ( 30), then axially moving this segment (44) to its insertion into the groove (64) of the inner surface of the second hollow shaft (32).