EP1517004A1 - Rotor wheel for a turbomachine and assembly method therefor - Google Patents

Abstract

The wheel (1) has a turbine disk (4) comprising an upstream flange (14a) and a downstream flange (14b), both extending around a main longitudinal axis (2). One of the flanges is conceived in an elastic manner such that the flanges pass from spaced apart position to assembled position and vice-versa, respectively by exerting pressure on the flanges and by releasing the exerted pressure. An independent claim is also included for a method for assembling a turbine wheel.

Description

TECHNICAL AREA

The present invention relates in a turbomachine turbine wheel, type comprising a turbine disk and a plurality of blade segments mounted on this disk of turbine.

Moreover, the invention relates also to a method of mounting such a wheel of turbine.

STATE OF THE PRIOR ART

In a conventional manner and known in the art previous, a turbomachine turbine wheel has a turbine disk and a plurality of vanes mounted on the turbine disc, each dawn having a foot extending from a profile radially inside, and being provided with holdings known as fasteners fir tree ".

To assemble the blades on the turbine disk, the latter is usually provided of a series of essentially open axial grooves radially outward, having a shape complementary to that of the "fir fasteners" above mentioned, and in which the blades may be inserted one after the other, in order to be maintained by this turbine disk.

Although this solution is widespread in the turbines of current turbomachines, she nevertheless presents a number of disadvantages major.

Indeed, it is first stated that the feet of the blades must necessarily be relatively large, just as the shapes (or teeth) of the turbine disk, in the purpose of allowing these elements to be properly maintained against each other, despite the radial efforts generated during the rotation of the wheel of turbine. Naturally, these important volumes are translate directly into weight constraints and material cost constraints. As such, it is also indicated that the complex realization of forms "fir tree" blades and disk generates significant manufacturing costs.

On the other hand, it is obvious that with this type of solution of the prior art, a given foot does not may not have a high number of blades, this one usually less than or equal to two. it can be explained in particular by the fact that if the number of blades belonging to the same foot was more important, the foot should then have a length and a thickness also larger just like the notch provided for the introduction of these blades in the disc. In such a case, it is clear that the mass of the set of "blade-blades" increases by unacceptable way, with regard to the interest in the lower manufacturing costs.

In this respect and as it is in the prior art, it is noted that the impossibility of providing segments with a number of blades, so to design segments of great circumferential length, generates a major disadvantage. Indeed, the longer the length circumferential blade segments is small, more the number of segments provided around the disc of turbine is important, and therefore more the number of spaces to seal between two directly consecutive segments is high.

Moreover, this type of realization not providing a sufficiently satisfactory seal between on the one hand the turbine disk and on the other hand the blade segments, it is usually necessary to add an upstream labyrinth connected by a system of flanges to the turbine disk. The upstream labyrinth allows thus, while playing an axial stopping role of the blades turbine in their fasteners, to protect the circuit cooling the blades of the inadvertent crossing hot gases from the turbine vein, which could cross the turbine wheel by borrowing the existing game between the disc and the blades. Indeed, in a known manner, the addition of the upstream labyrinth strongly limits the passage of air of cooling between the turbine disk and the segments of blades, thanks to his participation in the creation of an intermediate upstream chamber authorizing feeding the blades with cooling air.

However, the upstream labyrinth required is a cumbersome, high mass and extremely complex to realize, so that its presence constitutes undoubtedly a very detrimental disadvantage, especially in terms of extra costs.

STATEMENT OF THE INVENTION

The object of the invention is therefore to propose a Turbomachine turbine wheel having a disk turbine and a plurality of blade segments mounted on this turbine disk, and remedying at least partially to the disadvantages mentioned above relating to the achievements of the prior art.

On the other hand, the invention also purpose of presenting a method of mounting such a wheel of turbine.

To do this, the invention firstly for object a turbomachine turbine wheel having a turbine disk and a plurality vane segments mounted on this turbine disk, each blade segment comprising a foot as well as less a dawn attached to the foot. The turbine disk has an upstream wing and a downstream wing each extending substantially annularly around a longitudinal main axis of the wheel and radially to a radial end of the disc, each vane segment mounted on the turbine disc being likely to be retained by the latter in a external radial direction using means upstream commitment belonging to the foot and able to cooperate with means of upstream commitment complementary constituting a radial end the outer wing of the upstream wing, as well as by means of downstream commitment also belonging to the foot and able to cooperate with means of downstream engagement complementary constituting a radial end external of the downstream wing. In addition, the upstream wings and downstream of the turbine disk are designed to can be brought from a position away commitment to a close position, and vice versa, to allow mounting of each blade segment on the turbine disk. According to the invention, at least one of the upstream and downstream wings is designed so elastic so that the passage of these wings of the position spread to the close position and the passage from the close position to the discarded position can be respectively operated by exercising a pressure on the wings, and releasing the pressure exercised.

Advantageously, the design specific to the turbine wheel according to the invention is such as mounting the blade segments on the disk of turbine is carried out by realizing in particular a simple bringing the upstream and downstream wings together setting up these segments. Yes, the record turbine is advantageously designed so that when the upstream and downstream wings occupy their position close, the means of commitment upstream and downstream additional resources are sufficiently clear of the location they occupy when the upstream wings and downstream are in the open commitment position, to enable segments to be put in place by insertion into each other of each blade segment and the turbine disk.

In other words, in the position close, the means of commitment upstream and downstream complementary measures are sufficiently close together for when the blade segments are inserted into the turbine disc by radial displacement thereof towards the inside of the wheel, they do not form stop for the upstream and downstream commitment means belonging to the feet of the segments. Therefore, vane segments can each be moved freely radially with respect to the turbine disk, without being hampered by upstream and downstream commitment complementary, which are respectively further downstream that the means of upstream engagement of the blade segments, and more upstream than the downstream commitment these same segments.

Plus, once all segments of blades have been put in place on the turbine disc, the upstream and downstream wings can again be brought in their outset commitment position, in which complementary upstream and downstream commitment resources are then able to fulfill their primary function, namely, in combination with the means of engagement upstream and downstream, to ensure radial restraint towards the outside of each blade segment with respect to turbine disk.

As such, it is specified that the wheel of turbine according to the invention is such that the assembly of vane segments on the turbine disk can be completed as soon as the upstream and downstream wings are brought in their discarded commitment position after being close-quarters, or understand operations subsequent additions as will be stated from detailed way below.

In the first case where the assembly of segments is completed when the upstream and downstream wings are brought into their disconnected position of engagement, the configuration of the various means of engagement can be such that the mere displacement of the upstream wings and downstream in the disconnected position of engagement, causes the automatic commitment of these means of engagement. In other words, once the upstream and downstream wings occupy their discarded commitment position, the means of upstream and downstream engagement of blade segments cooperate respectively with the means of engagement upstream and downstream of the turbine disk, and the blade segments are automatically blocked in the outer radial direction with respect to disk. It is noted that this configuration can in particular be obtained by providing commitment ensuring not only a blockage of blade segments in the outer radial direction, but also a blockage of these segments in the internal radial direction with respect to the disc of turbine. This avoids the means upstream and downstream commitment of some of these segments of blades does not disengage by gravity means complementary upstream and downstream commitment. In these conditions, once mounted, the blade segments therefore no freedom of radial displacement compared to the turbine disk.

Conversely, it is also possible to provide configuration in which when the segments are in a mounted state, the latter being obtained by a simple displacement of the upstream and downstream wings in the position away from engagement, the blade segments can be move radially in a limited way compared to turbine disk, still being susceptible to be held in the outer radial direction by through the various means of engagement. Of this way, especially when the wheel is not in rotation, the means of commitment upstream and downstream of some segments of blades do not cooperate with complementary upstream and downstream commitment turbine disk, because of the gravity implying that these segments concerned are in radial abutment internal against the turbine disk, so the opposite of the position in which they are retained in the external radial direction by this same disk of turbine. So, in this configuration, it's only when the wheel is rotated generated centrifugal force causes engagement and then the cooperation between the means of upstream commitment and downstream of all the blade segments, and the means complementary upstream and downstream commitment of the turbine. In these dynamic conditions, these means complementary upstream and downstream commitment of the turbine thus actually play the role of thrust external radial for the upstream commitment means and downstream of the blade segments.

In the second case where the assembly of segments is carried out not only by bringing the wings upstream and downstream in their disconnected position of commitment, but also and proceeding with the implementation additional operations, it is stated that these past may be aimed at obtaining a permanent cooperation between means of engagement upstream and downstream of all blade segments and complementary upstream and downstream commitment turbine disc, as will be exposed so detailed later.

So, whatever the configuration adopted for the turbine wheel according to the invention, this hardly gives rise to any more restriction as to the maximum number of blades to provide on each segment. It therefore allows for a considerable reduction the number of these blade segments, and therefore also the number of spaces to be sealed between two segments of blades directly consecutive, compared to the one encountered in the embodiments of the prior art. sealing overall of the turbine wheel is therefore naturally significantly improved.

In addition, the possibility of reducing number of segments by providing a plurality of vanes on each of them causes a drop significant cost of production and assembly.

Finally, it is stated that the fact provide for cooperation between the means upstream commitment and upstream commitment complementary, and secondly between the means downstream commitment and downstream commitment means complements, makes it possible to provide seals upstream and downstream quite satisfactory between the turbine disk and vane segments, so that it is no longer necessary to provide upstream labyrinth for feeding the blades in cooling air.

Of course, this deletion allows also greatly reduce production costs of the turbine wheel.

Preferably, each of the upstream wings and downstream of the turbine disk is elastic. Of this way, by designing the turbine wheel so that the spaced engagement position of these wings corresponds at a rest position, it is then easily possible to bring these wings from the discarded position commitment to the close position by applying a simple effort on the latter, so as to generate a deformation of these same wings. Moreover, as previously mentioned, the return to the discarded position commitment then automatically takes place releasing the effort exerted, because of the elasticity of these wings.

Of course, it would also be possible to provide only one of the two upstream and downstream wings are designed to deform following the application of the effort required to obtain the close position, without departing from the scope of the invention.

Preferably, the engagement means complementary upstream and downstream annular around the longitudinal main axis of the wheel, and the means of commitment upstream and downstream of each foot of the blade segment are each made of to form an annular portion of the same axis, extending circumferentially all along the foot of the blade segment. Therefore, because of the long circumferential length of cooperation between the various means of engagement it is possible to obtain a mechanical maintenance of the blade segments very powerful and easily resistant to efforts radials generated during the rotation of the wheel of turbine. Moreover, this arrangement also allows to ensure a very satisfactory seal between a apart from the blade segments, and on the other hand the disk of turbine.

Preferably, the engagement means upstream and downstream complementary as well as the means upstream and downstream commitment of the foot of each segment of blades each have a longitudinal section in hook shape, this shape being quite adapted to ensure a locking in the radial direction external.

Indeed, it is then possible to predict complementary means of upstream commitment have a longitudinal section in the form of hook projecting upstream and defining a substantially oriented engagement opening radially towards the inside of the wheel, that the means upstream commitment have a longitudinal section hook-shaped projecting downstream and defining an engagement opening substantially radially outwardly of the wheel, that the complementary downstream engagement means a longitudinal section in the form of a hook projecting downstream and defining an opening substantially radially oriented inside the wheel, and finally that means downstream commitment have a longitudinal section hook-shaped protruding upstream and defining an engagement opening substantially oriented radially outwardly of the wheel.

In these circumstances, once the segments set up and the wings upstream and downstream again brought into the discarded commitment position, this preferred solution makes it possible to obtain a commitment then cooperation between the various means of engagement by simple radial relative movement between each of the vane segments and the turbine disk. Naturally, for each blade segment, the relative radial movement is preferably performed in moving this segment in the outer radial direction, while holding the fixed disk.

Still preferentially, each blade segment further comprises means for maintenance to ensure, when cooperating with the turbine disk, permanent cooperation between the upstream and downstream commitment means of the segment blade mounted on the turbine disk, and respectively upstream and downstream commitment means complementary to this same turbine disk. Of this way, the permanent cooperation between the various means of engagement advantageously allows to maintain the vanes segments fixed with respect to the disk of turbine, and thus to obtain a radial indexing and circumferential accuracy of each of these segments of blades with respect to the turbine disk.

To do this, we can predict that holding means comprise at least one blade flexible belonging to the foot and one end free is able to take support on the record of turbine, each of these flexible blades being then accosted to the disc only after the wings upstream and downstream were brought back into their position spread of commitment, and the paddle segment correspondent having been radially solicited towards the outside to take support on the means of engagement complementary of the disc.

Preferably, the upstream and downstream wings of the turbine disc define between them a space annular arranged around the longitudinal main axis of the wheel, this annular space communicating with cooling passages provided on the feet of segments of blades. In addition, the upstream wing of the turbine has at least one injection hole crossing and opening inside the space ring, each injection hole being intended for cooperate with a cooling air injector from the turbomachine.

Always preferentially, the disc of turbine is monobloc.

• amener les ailes amont et aval du disque de turbine dans la position rapprochée ;
• positionner chaque segment d'aubes par rapport au disque de turbine de sorte que lorsque les ailes amont et aval du disque de turbine sont à nouveau amenées dans leur position écartée d'engagement, les moyens d'engagement amont et aval du pied de chaque segment d'aubes soient en mesure de s'engager respectivement avec les moyens d'engagement amont et aval complémentaires du disque de turbine ; et
• amener les ailes amont et aval du disque de turbine dans leur position écartée d'engagement.

On the other hand, the invention also relates to a method of mounting a turbine wheel such as that just described and also object of the present invention, this method comprising the following successive steps consisting of:

• bringing the upstream and downstream wings of the turbine disk into the close position;
• positioning each vane segment relative to the turbine disk so that when the upstream and downstream wings of the turbine disk are again brought into their spaced engagement position, the upstream and downstream engagement means of the foot of each segment blades are able to engage respectively with the complementary upstream and downstream engagement means of the turbine disk; and
• bringing the upstream and downstream wings of the turbine disk into their spaced engagement position.

The steps of bringing the wings upstream and downstream of the turbine disk in the position close together and bring the upstream and downstream wings of the turbine disc in their discarded position commitment taking place respectively by exercising pressure on the upstream and downstream wings using a appropriate tools and releasing the pressure exercised.

Naturally, as mentioned above, in the step of positioning each segment of blades with respect to the turbine disk, it is understand that the various means of engagement must to be able to engage either directly during the step to bring back the upstream and downstream wings in their excluded position of commitment, either following rotation of the wheel, or following the subsequent operations as will be explained more precisely below.

Other advantages and features of the invention will appear in the detailed description non-limiting below.

BRIEF DESCRIPTION OF THE DRAWINGS

• la figure 1 représente une vue en demi-coupe longitudinale d'une roue de turbine selon un premier mode de réalisation préféré de la présente invention, cette roue de turbine étant représentée à l'état monté ;
• la figure 2 représente une vue partielle en perspective de la roue de turbine représentée sur la figure 1 ;
• la figure 3 représente une vue partielle agrandie de la figure 1 ;
• la figure 4 représente une vue partielle en demi-coupe longitudinale d'une roue de turbine selon un second mode de réalisation préféré de la présente invention, cette roue de turbine étant représentée à l'état monté ;
• la figure 5 représente une vue partielle en demi-coupe longitudinale d'une roue de turbine selon un troisième mode de réalisation préféré de la présente invention, cette roue de turbine étant représentée à l'état monté ; et
• les figures 6a à 6d illustrent diverses étapes d'un procédé de montage selon un mode de réalisation préféré de la présente invention, de la roue de turbine représentée sur les figures 1 et 2.

This description will be made with reference to the appended drawings among which;

• FIG. 1 represents a longitudinal half-sectional view of a turbine wheel according to a first preferred embodiment of the present invention, this turbine wheel being shown in the assembled state;
• Figure 2 shows a partial perspective view of the turbine wheel shown in Figure 1;
• Figure 3 shows an enlarged partial view of Figure 1;
• FIG. 4 shows a partial longitudinal half-section view of a turbine wheel according to a second preferred embodiment of the present invention, this turbine wheel being shown in the assembled state;
• FIG. 5 shows a partial longitudinal half-section view of a turbine wheel according to a third preferred embodiment of the present invention, this turbine wheel being shown in the assembled state; and
• Figures 6a to 6d illustrate various steps of a mounting method according to a preferred embodiment of the present invention, of the turbine wheel shown in Figures 1 and 2.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

With reference in conjunction with FIGS. 2, there is shown a turbine wheel 1 for turbomachine, according to a first embodiment preferred embodiment of the present invention.

The turbine wheel 1, main axis longitudinal section 2, comprises a turbine disk 4, monoblock preference, as well as a plurality of segments of blades 6 mounted on the disc 4, only one of these segments 6 being shown in FIG.

Each blade segment 6 comprises a foot 8 extended radially outwards by a blade 10, or preferably by several blades. indicative example, each segment 6 is provided with three blades 10 secured to an outer radial portion 11 of the foot 8, this part 11 of the metal plate type thickness possibly variable, for example take substantially the form of an angular sector of a cylindrical geometry with axis identical to the axis 2. In addition, the wheel of turbine 1 may be designed in such a way as to twenty segments 6 of three blades 10, these segments 6 being regularly distributed around the axis main longitudinal 2 and mounted on the disk of turbine 4. In addition, each space (not shown) between two directly consecutive segments 6 is sealed in a conventional manner using known means of the skilled person.

The turbine disc 4 includes a body internal 12, preferably of the solid body type, or more classically pierced with a central hole if necessary to pass a low pressure turbine shaft through example, this inner body 12 being centered on the axis main longitudinal 2. The inner body 12 is extended radially outwards on the one hand by an upstream wing 14a, and secondly by a downstream wing 14b. As can be seen clearly on the FIG. 1, the upstream wings 14a and the downstream wings 14b extend each substantially annularly around the axis longitudinal head 2 of wheel 1, and extend each radially to a radial end of the disc 4.

Naturally, throughout the description, the terms "upstream" and "downstream" are defined by relative to a main direction of gas flow through the turbine wheel 1, this direction being schematically represented by the arrow Dp on the figure 1.

Preferably, the upstream wings 14a and downstream 14b are both elastic, so as to can be easily moved from one position deviation from commitment as shown on the Figures 1 and 2, at a close position, and Conversely. This specificity makes it possible to authorize mounting the blade segments 6 on the disk 4 monoblock, as will be exposed more detailed later.

In the assembled state shown in FIGS. and 2, the blade segments 6 are not only retained in an external radial direction indicated schematically by the arrow Re, but also held in a specified internal radial direction schematically by the arrow Ri. In this way, as this will appear more clearly in the rest of the description, the specificity of this first mode of Preferred embodiment of the present invention resides in that the blade segments 6 have no freedom of radial displacement relative to the disk of turbine 4.

To ensure the restraint of the segments of blades 6 by the turbine disc 4 in the direction external radial Re, it is expected that each segment 6 includes upstream commitment means 16a as well as downstream engagement means 16b, these extending radially inward from part 11 of the foot 8, to which they are joined. These means upstream 16a and downstream 16b cooperate respectively with means of upstream commitment complementary 18a constituting a radial end external of the upstream wing 14a, and with means complementary downstream commitment 18b constituting a outer radial end of the downstream wing 14b. Good heard, it is to understand by the term "cooperate" that the various means of engagement 16a, 16b, 18a and 18b actually provide restraint, in the direction external radial Re, of each segment 6 with respect to 4. Therefore, in the mounted state in which the various engagement means 16a, 16b, 18a and 18b cooperate with one another, the blade segments 6 are in external radial abutment against the turbine disc 4, and these segments 6 can not therefore move in the external radial direction Re with respect to this same disc 4.

With reference to Figure 3, we can see more detailed ways of engagement 16a, 16b, 18a and 18b, when they cooperate with each other others.

In this first preferred embodiment of the present invention, it can be seen that the means complementary upstream commitment 18a and the means additional commitment agreements 18b, as well as upstream engagement means 16a and downstream 16b of the foot 8 of each blade segment 6, each have a section longitudinal hook-shaped.

More specifically, the means of engagement upstream complementary 18a have a section longitudinal hook-shaped projecting towards upstream. In other words, the means of engagement complementary upstream 18a project upstream relative to the rest of the upstream wing 14a. In addition, these means 18a define an engagement opening 20a substantially oriented radially inwards of the wheel 1, as it appears clearly in the figure 3.

Preferably, always in longitudinal section, the free end 22a of the hook point radially inward of the wheel 1.

Moreover, for each blade segment 6 of the wheel 1, the upstream engagement means 16a also have a shaped longitudinal section hook, the latter protruding downstream. Of more, these means 16a define an opening 24a engagement substantially radially oriented towards the outside of the wheel 1. Always in a preferred way and in longitudinal section, the free end 26a of the hook tip radially outward of the wheel 1.

Thus, in the mounted state corresponding to a state in which the upstream commitment means complementary 18a cooperate with the means upstream commitment 16a of each of the blade segments 6, the free end 22a passes through the opening of engagement 24a and is in contact with a background of hook 28a of upstream engagement means 16a. Of the same way, the free end 26a crosses the engagement opening 20a and is in contact with a hook bottom 30a means of upstream commitment complementary 18a. For practical reasons manufacture, it might be decided to favor one or the other of the contacts 28a or 30a, without leaving the framework of the invention.

Therefore, the means of engagement complementary upstream 18a extending preferentially annularly around the main axis longitudinal axis 2 of the wheel 1, and the engagement means upstream 16a of each blade segment 6 being each made to form an annular portion of same axis extending circumferentially all the way of the foot 8 on a circumferential length L, it is then possible to obtain an upstream seal particularly satisfactory. Indeed, it is noted that the centrifugal force generated during the rotation of wheel 1 causes significant pressure on the one hand between the free end 26a and the hook bottom 30a, and / or on the other hand between the free end 22a and the 28a hook background. In both cases, the observed support is substantially circumferential axis identical to the longitudinal main axis 2, and thus contributes strongly to obtain an upstream seal perfectly adapted to the needs encountered.

In a similar way, the means of engagement complementary downstream 18b have a section longitudinal hook-shaped projecting towards downstream. In other words, the means of engagement complementary downstream 18b project downstream through compared to the rest of the downstream wing 14b. In addition, these means 18b define a commitment opening 20b substantially oriented radially inwards of the wheel 1, as it appears clearly in the figure 3.

Preferentially and always in longitudinal section, the free end 22b of the hook point radially inward of the wheel 1.

Moreover, for each blade segment 6 of the wheel 1, the downstream engagement means 16b also have a shaped longitudinal section hook, the latter protruding upstream. Of more, these means 16b define an opening 24b engagement substantially radially oriented towards the outside of the wheel 1. Always in a preferred way and in longitudinal section, the free end 26b of hook tip radially outward of the wheel 1.

Thus, in the mounted state corresponding to a state in which the downstream commitment means complementary 18b cooperate with the means downstream commitment 16b of each of the blade segments 6, the free end 22b passes through the engagement opening 24b and is in contact with a hook bottom 28b of downstream commitment means 16b. In the same way, the free end 26b passes through the engagement opening 20b and is in contact with a hook bottom 30b of complementary downstream commitment means 18b. Right here still, for practical reasons of manufacture, it could be decided to favor one or the other of contacts 28a or 30a, without departing from the invention.

Therefore, the means of engagement complementary downstream 18b also extending preferably annularly around the axis longitudinal head 2 of wheel 1, and the means downstream commitment 16b of each blade segment 6 being each made to form an annular portion of the same axis extending circumferentially all the along the foot 8 along a circumferential length identical to that of the upstream commitment means 16a, it it is possible to obtain a downstream seal particularly satisfactory. This is explained always because of the centrifugal force generated during of the rotation of the wheel 1, causing a pressure important on the one hand between the free end 26b and the 30b hook bottom, and secondly between the end free 22b and hook bottom 28b.

To ensure permanent cooperation between the various engagement means 16a, 16b, 18a and 18b, so a permanent contact between the ends free 22a, 22b, 26a and 26b and respectively the funds hook 28a, 28b, 30a and 30b, each of the segments of blades 6 of the turbine wheel 1 also has holding means 32a and 32b ensuring the retention of these segments 6 in the internal radial direction Ri.

Indeed, again with reference to FIGS. 1 and 2, the holding means 32a of each segment 6 take the form of an upstream flexible blade, the latter extending radially inwards of the wheel 1. Preferably, the upstream flexible blade 32a has a solidarity end of the means upstream commitment 16a of the segment 6, and an end free 34a having a notch 36a. So, in the state mounted shown in Figures 1 and 2, a pin 38a secured to the upstream wing 14a and protruding from this one upstream, is inserted until the bottom notch 36a open radially inwards of the wheel 1. Therefore, the pin 38a therefore ensures the internal radial stop function for segment 6 concerned.

Similarly, the holding means 32b of each segment 6 take the form of a blade downstream flexible, the latter extending radially towards the inside of the wheel 1. Preferably, the blade downstream flexible hose 32b has an integral end of downstream commitment means 16b of the segment 6, and a free end 34b having a notch (no referenced). Thus, in the mounted state, a pin 38b secured to the downstream flange 14b and projecting from it downstream, is inserted into the bottom of the notch open radially towards the inside of the wheel 1. Therefore, the pin 38b therefore ensures also the function of internal radial stop for the segment 6 concerned.

Preferably and as it appears clearly in the figures, the flexible blades upstream 32a and downstream 32b can be connected respectively to the upstream commitment means 16a and the means downstream commitment 16b, at a portion of these means 16a and 16b defining the hook bottoms 28a and 28b. In other words, the junction between the blades flexible 32a and 32b and the engagement means 16a and 16b is carried out at the level of a portion of these means 16a and 16b located radially the most inwards of the turbine wheel 1.

In this way, when the flexible blades 32a and 32b are put in place, the contact obtained between the various engagement means 16a, 16b, 18a and 18b as well as the contact between the free ends 34a, 34b and the nipples 38a, 38b makes it possible to precise radial and circumferential indexing of each of the blade segments 6 with respect to the disk of turbine 4.

In this first embodiment preferred, the upstream wings 14a and downstream 14b define between them, when they occupy their position spread of engagement, an annular space 40 arranged around the longitudinal main axis 2. This space ring 40, open radially outward, therefore communicates with cooling passages 42 provided on the foot 8 of the blade segments 6, and more precisely on the outer radial part 11 of this same foot.

In addition, the upstream wing 14a has least one injection hole 44 passing through it and opening into the annular space 40. From this way, each injection hole 44 being intended for cooperate with an air injection system from cooling of the turbomachine (not shown), it so is easily possible to cool the blades 10 without requiring an upstream labyrinth. Indeed, the cooling air ejected injectors can then borrow successively injection holes 44, the annular space 40, then the cooling passages 42 communicating with a cooling circuit (not shown) practiced in inside the blades 10.

With reference to FIGS. 6a to 6d, it is represented various stages of a mounting process according to a preferred embodiment of this invention, of the turbine wheel 1 which has just been described.

Referring first to Figure 6a, we can see that a first step of this process consists in bringing the upstream wings 14a and downstream 14b of the deviated position of commitment, to the position close. This is done using a tool appropriate diagrammatically represented by the references 46, and whose function is to exercise a pressure on the upstream wings 14a and downstream 14b of the disc monobloc 4, so that they deform and become bring one closer to the other. Preferably both wings 14a and 14b are each subjected to pressure distributed annularly around the main axis longitudinal 2, and respectively applied to a upstream face of the upstream wing 14a and on a downstream face of the downstream wing 14b.

The close position is obtained when complementary upstream commitment means 18a and the complementary downstream commitment means 18b are sufficiently clear of the location they occupy when the upstream wings 14a and downstream 14b are in the position of commitment, to allow in place of the segments 6, by inserting one into the other of each blade segment 6 and the disk of turbine 4.

Indeed, a next step is to set up the various segments 6 with respect to turbine disc 4, as shown on the Figure 6b. The installation is preferably carried out in moving radially towards the inside of the wheel 1 each of the segments 6, so that the means complementary upstream commitment 18a and downstream 18b are inserted within those same segments 6, without being hampered by the means upstream commitment 16a and downstream 16b. In such a case, for each blade segment 6, the engagement means complements 18a and 18b can therefore easily be introduced in a space delimited jointly by the upstream commitment means 16a, the means 16b downstream engagement, as well as the radial portion external 11 of the foot 8 of segment 6 concerned.

In addition, this step of setting up is completed only when segments 6 have been placed sufficiently radially inwards by compared to disk 4, so that when the upstream wings 14a and downstream 14b are again brought into their deviated position of commitment, means of engagement upstream 16a and downstream 16b of the foot 8 of each segment 6 able to engage respectively with the complementary upstream commitment means 18a and downstream 18b of the turbine disk 4, during a relative radial displacement of these various elements.

As an illustrative example, it is possible to foresee that this step of setting up only ends when the means of engagement 18a and 18b have come into contact with the part 11 of the foot 8 of each segment 8, as the shows Figure 6b. In this way, the means complementary commitment 18a and 18b then an internal radial stop function for the segments 6, indicating that the blade segments 6 are actually correctly set up.

It is then proceeded to a step consisting of bringing back the upstream wings 14a and downstream 14b in the open position of engagement, by simple release of the pressure exerted on these same wings using appropriate tools 46.

In this excluded commitment position, as can be seen in Figure 6c, the free ends 22a, 22b, 26a and 26b are respectively facing and remote openings 24a, 24b, 20a and 20b, and the means complementary commitments 18a and 18b are always always in contact with the radial part external 11 feet 8. Moreover, one can see in this figure 6c that the flexible blades 32a and 32b are respectively plated against the ends of the nipples 38a and 38b, but that these last do not cooperate yet with the notches 36a because of the radial offset existing at that moment of the implementation of the method.

The next step in this assembly process can then consist in carrying out a displacement of each of the blade segments 6 in the radial direction external Re relative to the disk 4, so as to ensure commitment between the various means commitment 16a, 16b, 18a and 18b, that is to say cause the introduction of the free ends 22a, 22b, 26a and 26b respectively in the openings engagement 24a, 24b, 20a and 20b.

Of course, as shown on FIG. 6d, this radial displacement is stopped by the cooperation between the various means of engagement 16a, 16b, 18a and 18b, namely by the coming into contact of the free ends 22a, 22b, 26a and 26b respectively with the hook bottoms 28a, 28b, 30a and 30b.

Finally, if we took the precaution, of this radial displacement operation, circumferentially preposition each of the segments 6 so that the radial direction of the flexible blades 32a and 32b coincides with that of nipples 38a and 38b associated, then at the end of moving, these nipples 38a and 38b are coming automatically lodge at the bottom of the notches of the fact of the elasticity of the flexible blades 32a and 32b, as this is visible in Figure 6d. Naturally, the cooperation between these notches 36a (not referenced on FIG. 6d) and the nipples 38a and 38b provide a circumferential and radial indexing of the segments 6, as well as blocking them from the turbine disk 4.

On the other hand, it is stated that it is from this moment that the assembly of the segments of blades 6 on the turbine disk 4 is completed. Nevertheless, the method of mounting the wheel 1 can understand preliminary or subsequent stages conventional techniques, such as those aimed at various spaces formed between the blade segments 6, by example by introducing sealing tabs 39 such as that shown in Figure 2, at the level of of the foot 8 and between two consecutive segments of blades 6. This step is of course implemented before final indexing of these segments 6 on the disc 4.

Referring now to Figures 4 and 5, it is partially represented turbine wheels 100 and 200 for a turbomachine, respectively according to a second and according to a third embodiment preferred embodiments of the present invention.

The common point between these two modes of preferred embodiment lies in the fact that the assembly blade segments 6 on the turbine disk 4 is completed as soon as the upstream wings 14a and downstream 14b have been brought back to their outset commitment position, the mounting therefore does not require a step of radial displacement of the segments 6, as described previously for the first embodiment prefer. Of course, following the reinstatement of upstream wings 14a and downstream 14b in their separated position commitment, and therefore as soon as the assembly of the segments 6 on disk 4 is completed, it is naturally possible to carry out the classic finishing steps such as those aimed at sealing the various spaces formed between the blade segments 6.

Thus, the turbine wheel 100 according to the second preferred embodiment shown in the FIG. 4 is substantially similar to wheel 1 according to the first preferred embodiment described above. The main difference is that segments 6 of the wheel 100 do not have means of maintenance permitting permanent cooperation between the various engagement means 16a, 16b, 18a and 18b, the latter being moreover substantially identical to those described for the turbine wheel 1. In this way, as can clearly be seen in Figure 4, mounted state and when the wheel 1 is not in rotation, some segments are in radial abutment against additional means of commitment 18a and 18b, because of gravity. Consequently, it is only when the wheel 1 is rotated that the centrifugal force engendered causes the engagement then the cooperation between the means of upstream commitment 16a and downstream 16b of all the blade segments 6, and the complementary upstream commitment means 18a and complementary downstream 18b of the turbine disk 4.

Naturally, this solution is less advantageous than that of the first embodiment preferred, since it is not possible to obtain a radial and circumferential indexation specifies segments 6 with respect to the disc 4.

The turbine wheel 200 according to the third preferred embodiment shown in FIG. 5 differs from the turbine wheels 1 and 100 in that the repositioning upstream wings 14a and downstream 14b in their discarded commitment position causes simultaneously a commitment and a cooperation between the various engagement means 16a, 16b, 18a and 18b. Of more, these various means of engagement 16a, 16b, 18a and 18b are designed so that when they cooperate with each other, they ensure the restraint of segments 6 relative to the disk 4 in the outer radial direction Re, as well only in the internal radial direction Ri. Segments 6 blades do not require means of maintenance such as those described for the turbine wheel 1.

To do this, as shown on the FIG. 5, the upstream commitment means 16a and the downstream commitment device 16b each may have an annular groove 48a and 48b respectively open downstream and open towards upstream. Moreover, the means of engagement complementary 18a and 18b can each be provided an annular projection 50a and 50b making respectively upstream and downstream, and having a form complementary to that of annular grooves 48a and 48b so as to be maintained correctly. With such an arrangement, the engagement means 16a, 16b, 18a and 18b do not require so more to present the shape of a hook in section longitudinal.

Of course, various modifications may be brought by the skilled person to the wheels of turbine 1, 100, 200 and the assembly process which have just been described, only as examples non-limiting.

Claims (12)

Turbomachine turbine wheel (1,100,200) comprising a turbine disk (4) and a plurality of blade segments (6) mounted on said turbine disk (4), each blade segment (6) having a foot (8) and at least one blade (10) integral with said foot (8), the turbine disc (4) having an upstream wing (14a) and a downstream wing (14b) each extending substantially annularly around a longitudinal main axis (2) of the wheel and radially to a radial end of the disk (4), each blade segment (6) mounted on the turbine disk (4) being capable of being retained by the latter in a radial outer direction (Re) using upstream engagement means (16a) belonging to said foot (8) and able to cooperate with complementary upstream engagement means (18a) constituting a radial outer end of the upstream wing (14a), as well as using downstream engagement means (16b) also belonging to said foot (8) and capable to cooperate with complementary downstream engagement means (18b) constituting a radial outer end of the downstream wing (14b), the upstream (14a) and downstream (14b) wings of the turbine disk (4) being designed so as to can be brought from a position spaced engagement to a close position, and vice versa, to allow mounting of each segment of blades (6) on the turbine disc (4), characterized in that at least l one of the upstream (14a) and downstream (14b) wings is elastically designed so that the passage of these wings (14a, 14b) from the spaced apart position to the close position and the passage from the close position to the remote position can respectively be operated by exerting pressure on the wings (14a, 14b), and releasing said exerted pressure. Turbine wheel (1,100,200) according to claim 1, characterized in that each of the upstream (14a) and downstream (14b) wings of the turbine disk (4) is elastic. Turbine wheel (1,100,200) according to claim 1 or claim 2, characterized in that the complementary upstream and downstream engagement means (18a, 18b) extend annularly about the longitudinal main axis (2) of the wheel, and in that the upstream and downstream engagement means (16a, 16b) of each blade segment foot (8) (6) are each made to form an annular portion of the same axis, extending circumferentially all along said foot (8) of the blade segment (6). Turbine wheel (1,100) according to any one of the preceding claims, characterized in that the complementary upstream and downstream engagement means (18a, 18b), as well as the upstream and downstream engagement means (16a, 16b) of the foot (8) of each blade segment (6), each have a hook-shaped longitudinal section. Turbine wheel (1,100) according to claim 4, characterized in that the complementary upstream engaging means (18a) have a hook-shaped longitudinal section projecting upstream and defining an engagement opening (20a) substantially oriented radially inwardly of said wheel, in that the upstream engaging means (16a) have a hook-shaped longitudinal section projecting downstream and defining an engagement opening (24a) substantially radially oriented towards the outside of said wheel, in that the complementary downstream engagement means (18b) have a longitudinal hook-shaped section projecting downstream and defining an engagement opening (20b) substantially oriented radially towards the inside said wheel, and finally in that the downstream engagement means (16b) have a hook-shaped longitudinal section projecting upstream and defined an engagement aperture (24b) substantially radially outwardly of said wheel. Turbine wheel (1) according to any one of the preceding claims, characterized in that each blade segment (6) further comprises holding means (32a, 32b) for ensuring, when they cooperate with the turbine disc (4), a permanent cooperation between the upstream and downstream engagement means (16a, 16b) of the blade segment (6) mounted on the turbine disc (4), and respectively the upstream commitment means and complementary downstream (18a, 18b) of the same turbine disk (4). Turbine wheel (1) according to claim 6, characterized in that for each blade segment (6), the holding means comprise at least one flexible blade (32a, 32b) belonging to said foot (8) and one end free (34a, 34b) is able to bear on the turbine disc (4). Turbine wheel (1,100,200) according to any one of the preceding claims, characterized in that the upstream (14a) and downstream (14b) wings of the turbine disk (4) define between them an annular space (40) arranged around the longitudinal main axis (2) of the wheel, said annular space (40) communicating with cooling passages (42) provided on the feet (8) of blade segments (6). Turbine wheel (1,100,200) according to claim 8, characterized in that the upstream wing (14a) of the turbine disk (4) has at least one injection hole (44) passing through it and opening into the interior of the turbine. annular space (40), each injection hole (44) being intended to cooperate with a cooling air injector of the turbomachine. Turbine wheel (1,100,200) according to any one of the preceding claims, characterized in that each blade segment (6) of said wheel comprises at least two blades (10) integral with the foot (8). Turbine wheel (1, 100, 200) according to any one of the preceding claims, characterized in that said disc (4) is in one piece. A method of mounting a turbine wheel (1,100,200) according to any one of the preceding claims, characterized in that it comprises the following successive steps consisting of: bringing the upstream (14a) and downstream (14b) wings of the turbine disk (4) into the close position; positioning each vane segment (6) with respect to the turbine disk (4) so that when the upstream (14a) and downstream (14b) wings of the turbine disk (4) are again brought into their spaced apart position; commitment, the upstream and downstream engagement means (16a, 16b) of the foot (8) of each blade segment (6) are able to engage respectively with the complementary upstream and downstream engagement means (18a, 18b) of the turbine disk (4); and bringing the upstream (14a) and downstream (14b) wings of the turbine disk (4) into their engaged engagement position, the steps of bringing the upstream (14a) and downstream (14b) wings of the turbine disk (4) into the close position and bringing the upstream (14a) and downstream (14b) wings of the turbine disk (4) into their spaced commitment position being effected respectively by exerting pressure on the upstream wings (14a) and downstream (14b) with the aid of appropriate tools (46), and releasing said exerted pressure.

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