FR3139855A1 - ROTATING TURBOMACHINE ASSEMBLY INCLUDING AN AXIAL RETAINING DEVICE FOR BLADE FOOT IN THE SOCKETS OF A ROTOR DISC - Google Patents

Abstract

ROTATING TURBOMACHINE ASSEMBLY COMPRISING AN AXIAL RETAINING DEVICE FOR BLADE FOOT IN THE SOCKETS OF A ROTOR DISC One aspect of the invention relates to a rotating turbomachine assembly (1) with an axis (X) of rotation comprising: a disc (5) centered on the axis (X), having teeth (52) and cells (56) formed between the teeth (52), a plurality of blades (6) each comprising a blade root (61 ) mounted in a cell (56), at least one axial retaining device (7) for a blade (6), comprising: at least one axial stop plate (71) facing one part of the blade root ( 61) and on the other hand a bearing surface (50b) of the disc (5), a fixing device (78) fixing the axial stop plate (71) to the blade root, the axial retaining device (7) axially retaining the blade root (61) in the cell (51) at least in one axial direction by means of the axial stop plate (71) pressed against the bearing surface (50b). Figure to be published with the abstract: Figure 2

Description

ROTATING TURBOMACHINE ASSEMBLY INCLUDING AN AXIAL RETAINING DEVICE FOR BLADE FOOT IN THE SOCKETS OF A ROTOR DISC TECHNICAL FIELD OF THE INVENTION

The present invention relates to the field of aeronautics and particularly to turbine wheels of turbomachines for aircraft.

The present invention relates to the technical field of turbomachine rotary assemblies comprising a device for axially retaining the blades of a rotor of a turbomachine, in particular of an aircraft engine. It targets the axial immobilization device of the blade root in the cell.

TECHNOLOGICAL BACKGROUND OF THE INVENTION

Conventionally, a turbomachine turbine for aircraft comprises several successive turbine wheels, separated by distributor stages and crossed by an air stream.

A turbomachine turbine comprises an alternation of moving wheels and distributors. The moving wheels are rotating moving blades belonging to the turbine rotor, while the distributors are fixed blades belonging to the turbine stator.

There represents, in axial section view whose plane includes the axis of rotation, a part of a movable wheel 100 belonging to a low pressure turbine of a twin-body turbojet. The movable wheel 100 comprises an upstream face 100a and a downstream face 100b opposite axially to the upstream face 100a. The mobile wheel 100 comprises a disc 101 and blades 2 distributed over the circumference of the disc 101. Each blade 2 comprises a blade root 21 extended by a stilt 22 which carries a blade 23 extending radially from the stilt 22. The disc 101 has the axis of rotation X and comprises teeth and cells 111 formed between the teeth. Each cell 111 extends longitudinally (axially) between the upstream face 100a and downstream face 100b, more precisely, at an angle of some degrees relative to the axis of rotation. The fixing feet 21 of the blades 2 are engaged axially in the cells 11 and are retained radially by these cells.

The mobile wheel 100 further comprises means for blocking the blades 2 in the cells 111 of the disc 101. These means generally comprise a retaining ring 3 arranged to bear axially against a downstream face of the disk 101 and a downstream face of the different feet of fixing 21 housed in the cells 111. The retaining ring is 360° and therefore includes the axis of rotation. This retaining ring 3 is maintained by hooks 24 provided on the blades 2 and an annular spacer 4, also called a movable ring, separating two stages of the turbine. The spacer 4 comprises a downstream annular wall 41 pressed against the retaining ring 3 and an annular flange 42 fixed to an annular flange of the disc 101. The annular spacer 4 further comprises in this example, an annular wall 44 (visible on the another annular spacer 4) mounted against the upstream face of the disk and in a second hook of the blade root 21 and a seal 49 in an orifice in the annular wall 44 against the upstream face of the disk to ensure sealing when the wheel rotates by means of the centrifugal force exerted on the seal 49. The retaining ring 3 makes it possible to axially retain the blade 2 in the direction from downstream to upstream by means of the hooks 24 and the annular wall 41 downstream of the spacer 4 prevents movement of the blade 2 from upstream to downstream. The mobile wheel may include a second upstream retaining ring mounted in the hook 24 and blocked by the annular spacer 4.

The assembly of the retaining ring 3 is however difficult, due to the lack of space between the disc 1 and the hooks 24 of the blades 2, the assembly of the retaining ring 3 is often mounted by forcing on the ring retainer 3 by inserting it into the hook which may also risk deforming it.

It is also known from document EP1584794B1 to position a downstream retaining ring mounted in an annular groove on a downstream face of the disc to retain all of the blades and an annular lock in the groove of the disc to immobilize it. Furthermore, the upstream retaining ring comprises an internal annular rim oriented radially inwardly housed oppositely in another upstream groove on the upstream face of the disc and further comprises a cylindrical rim oriented downstream inserted in a cylindrical groove on the upstream face of the disc. A radially external part of the upstream retaining ring rests on the upstream end of the roots of the blades of the disc, thus ensuring their axial retention in the upstream direction. Mounting the retaining ring is also difficult to put in place in the groove of the disc with the annular lock which can force the retaining ring during assembly.

It is also known from document FR 2819290, a solution using a wedge between the blade root and the bottom of the cell which keeps the blade root resting against the walls of the corresponding cell, the wedge comprises a protrusion located at the upstream end of the wedge, between the upstream face of the blade root and a flange of revolution bearing against the upstream face of the disc causing an axial shift of the blade root towards the downstream. The puddle is attached by screws to the disc. However, this type of solution by wedging only allows axial retention in one direction (here from downstream to upstream), the blade root is therefore mounted in the cell with an axial play which can induce wear of the blade root and disc which may require the use of foil. In addition, like the previous solutions, mounting the wedge is difficult.

In addition, during the operation phase of the turbine wheel, the mechanical (mainly radial) and thermal stresses between the parts and the alternation of expansion and contraction cycles cause cracking phenomena in the retaining ring or flanges or wedges creating multiple risks.

The risks incurred in the event of a crack in the retaining ring are multiple. Fragments of one of the rings can in particular be released into the aerodynamic vein crossed by the blades and damage the turbine blades located downstream. In the event of a significant crack, blades can be released into the vein, because the retaining ring no longer ensures axial stopping of the blade roots.

For any damage to the retaining ring or flange, its replacement is required, which requires engine removal, which is a long and expensive operation. Indeed, whatever the importance of the damage, replacing the damaged retaining ring requires removal of the turbomachine, which is complex since it is necessary to remove the movable ring then the retaining ring without damaging the hook and carry out the difficult assembly of the new retaining ring, as mentioned previously.

Any crack in the retaining ring causes the release of fragments of the retaining ring or flange into the air stream which can damage the moving blades located downstream of the turbine including the cracked retaining ring. In the case of a crack that is too large, the axial stopping of the blade root is no longer ensured by the retaining ring or flange, creating a risk of the moving blades being released into the air stream.

There is therefore a need for a solution to address at least one of these problems.

The invention offers a solution to the problems mentioned above, by proposing a rotating turbomachine assembly comprising a device for axially retaining a blade root in a cell of the disc, which is fixed to retain the blade so as to simplify its assembly and preserve effective axial support while limiting maintenance costs.

• un disque centré sur l’axe X, qui présente une face amont et une face aval opposée axialement à la face amont et présentant à sa périphéries des dents s’étendant axialement de la face amont à la face avale, et des alvéoles délimitées circonférentiellement et formées entre les dents, le disque présentant en outre au moins une surface d’appui sur une des faces amont ou aval du disque,
• une pluralité d’aubes comprenant chacune un pied d’aube monté dans une alvéole correspondante du disque, le pied d’aube comprenant une face amont, une face aval opposée axialement à la face amont,
• caractérisée en ce que l’ensemble rotatif de turbomachine comprend en outre au moins un dispositif de retenu axial pour une aube, comprenant:
  • au moins une plaque de butée axiale comprenant une face externe et une face interne opposée à la face externe et comprenant deux bords d’extrémités circonférentielles distant l’un de l’autre suivant une longueur maximale mesurée tangentiellement inférieure au rayon du disque, la face interne étant en face d’une part de l’une des faces amont ou aval du pied d’aube de l’aube correspondante et d’autre part de la surface d’appui de la face amont ou aval correspondante du disque,
  • un dispositif de fixation fixant la plaque de butée axiale au pied d’aube ou au disque, le dispositif de retenu axial retenant axialement le pied d’aube dans l’alvéole au moins dans un sens axial par le biais de la plaque de butée axiale en étant plaquée contre la surface d’appui.

A first aspect of the invention relates to a rotating turbomachine assembly with an axis of rotation X comprising:

• a disc centered on the axis formed between the teeth, the disc further having at least one bearing surface on one of the upstream or downstream faces of the disc,
• a plurality of blades each comprising a blade root mounted in a corresponding cell of the disc, the blade root comprising an upstream face, a downstream face axially opposite the upstream face,
• characterized in that the rotating turbomachine assembly further comprises at least one axial retaining device for a blade, comprising:
  • at least one axial stop plate comprising an external face and an internal face opposite the external face and comprising two circumferential end edges spaced from one another along a maximum length measured tangentially less than the radius of the disc, the face internal being facing on the one hand one of the upstream or downstream faces of the blade root of the corresponding blade and on the other hand the bearing surface of the corresponding upstream or downstream face of the disc,
  • a fixing device fixing the axial thrust plate to the blade root or to the disc, the axial retaining device axially retaining the blade root in the cell at least in one axial direction via the axial thrust plate by being pressed against the support surface.

The rotating turbomachine assembly according to the invention makes it possible, thanks to the axial retaining device which is a mechanical part independent of the blade root and the rotor disk, to simplify the geometry of these two elements and to eliminate the need for hooks. on the blade roots to retain a retaining disc. In addition, the mounting of this type of axial retainer on the rotor disk is simplified because a substantially restricted space is sufficient to insert such an axial retainer. The fact that the retaining device does not include a 360° ring in contact with the blade root but an axial stop plate also makes it possible to reduce thermal or mechanical stress and thus reduce the risk of cracking.

The rotating assembly may include one or more characteristics of the different embodiments described below.

According to one embodiment, the axial stop plate comprises a maximum circumferential length measured along a tangent to the axis of rotation of between one and two times the circumferential width of a cell measured along a tangent to the axis of rotation. This size of axial thrust plate allows easy handling and therefore facilitates the assembly or disassembly of the axial thrust plate. Indeed, the more the axial thrust plate retains several blades, the more the blades will be fixed together, causing difficulties in managing expansions, and the tolerances of these parts between them, thus with such a plate retaining a single blade, makes it possible to reduce expansion problems, and the tolerances of these parts between them.

According to one embodiment, the fixing device is fixed to the blade root and the axial stop plate is fixed to the blade root by being sandwiched between the blade root and the fixing device. Thus, the axial stop plate is integral with the blade root and forms an axial stop against one of the two faces of the disc. This makes it simple, requires no force during assembly and can be easily dismantled. Thus the internal face of the axial thrust plate is in contact against one of the two upstream or downstream faces of the blade root.

According to an example of this embodiment, the blade root comprises a hole extending axially and opening onto the upstream or downstream face of the blade root in contact with the axial stop plate, which comprises an orifice extending axially and opening onto the hole in the blade root, the fixing device comprising a screw passing through the axial stop plate and comprises a part housed in the hole for fixing the axial stop plate against the blade root.

According to one example, the axial stop plate comprises a through orifice from the internal face to the external face, the orifice being opposite the hole in the blade root and is crossed by the fixing screw.

According to a variant of this example, the axial stop plate includes a notch opposite the hole in the blade root and is crossed by the fixing screw.

According to an example of this embodiment, the hole has a tapping, the screw being screwed into the hole in the blade root and comprises a head resting against the external face of the axial stop plate.

According to a variant of this example, the hole is open and extends from the upstream face to the downstream face, the screw passes through the hole and in which the fixing device comprising a nut tightened on the screw by sandwiching the foot of The blade and the axial thrust plate against each other.

According to a variant of this embodiment, the blade root comprises a threaded hole oriented at an angle between 1 and 90° relative to the axial axis of insertion of the blade root into the cell, the screw coming abutting against a surface of the axial thrust plate. For example, the axial stop plate includes a ramp against which the screw presses the axial stop plate against the blade root by screwing into the threaded hole. In these two embodiments, the blade root includes a hole for inserting the screw in order to fix and press the axial stop plate against the blade root.

According to one embodiment, the fixing device is a bolt comprising a nut and a screw comprising a head, the blade root and the axial stop plate being sandwiched between the head and the nut.

Advantageously, the blade root or the axial stop plate comprises a flat surface abutting against a flat surface of the head of the screw or the nut to prevent it from pivoting in the two directions of rotation (screwing and unscrewing). For example, the head of the retaining device comprises a non-cylindrical shape, for example a parallelepiped and the blade root comprises a stop extending axially from the surface against which the head is pressed. According to one example, the blade root or the axial thrust plate comprises an axially open notch housing at least part of the head of the screw or the nut. The notch has the shape of an imprint of the head of the screw or nut. This avoids having to use a wrench to hold the screw and simplifies assembly/disassembly. Indeed, the flat surface of the blade root or the axial stop plate makes it possible to form a rotation stop, which can be an imprint in which the screw head or the nut would come to immobilize by cooperation of shape.

According to one embodiment, the axial retaining device further comprises a second axial stop plate per blade, each second axial stop plate comprising an external face and an internal face opposite the external face, the internal face being pressed against the upstream or downstream face of the blade root of the corresponding blade opposite to that against which the first axial stop plate is pressed, the second axial stop plate and in addition pressed against respectively a bearing surface of the upstream face or corresponding downstream of the disc, the screw of the fixing device passing through the two axial stop plates to sandwich the blade root between the two holding plates each pressed against a bearing surface of the disc. This allows the blade root to be retained axially in both axial directions.

According to a variant of this embodiment, the rotating turbomachine assembly further comprises a spacer fixed to the disk, the spacer comprising an annular wall resting against the external face of the axial thrust plate. This allows the blade root to be retained axially in both axial directions. This embodiment also has the advantage of dispensing with foil, in other words the face of the bottom of the cell of the disc is directly opposite a face forming an internal radial end of the blade root.

According to one embodiment, each axial stop plate comprises an indexing element and each blade root comprises an indexing element cooperating with that of the axial stop plate.

According to one embodiment, the blade root comprises an internal radial end face connecting the upstream face to the downstream face, the disc comprising a bottom surface per cell formed between the two teeth and each axial stop plate comprises a air outlet orifice facing the space extending axially in the cell formed between the bottom surface and the internal radial end surface of the blade root.

According to one embodiment, the disc comprises an axial end surface on each of its upstream face and its downstream face and a housing housing the axial stop plate, the bearing surface of which forms a bottom of the housing set back axially by relative to the axial end surface of at least the thickness of the axial stop plate measured between its internal face and its external face.

According to one embodiment, the assembly comprises an axial retaining device per blade mounted on the disc. Thus the assembly includes a number of axial retaining devices equal to the number of blades mounted on the disc.

• insertion de chaque pied d’aube dans une alvéole axialement par une face amont ou aval d’un disque jusqu’à l’autre face aval ou amont respectivement,
• plaquage d’une plaque de butée axiale par aube contre l’une des faces amont ou aval d’un pied d’aube de l’aube correspondant et contre une surface d’appui de la face amont ou aval correspondante disque,
• fixation de chaque plaque de butée axiale contre le pied d’aube par un dispositif de fixation correspondant.

A second aspect of the invention relates to a method of mounting a rotating turbomachine assembly according to the first aspect of the invention, with or without the different combinations of embodiments, the assembly method comprises the following steps:

• insertion of each blade root in a cell axially by one upstream or downstream face of a disc to the other downstream or upstream face respectively,
• pressing an axial stop plate per blade against one of the upstream or downstream faces of a blade root of the corresponding blade and against a bearing surface of the corresponding upstream or downstream face disc,
• fixing each axial stop plate against the blade root by a corresponding fixing device.

The assembly method according to the invention has the advantage of being relatively simple to implement.

The invention and its various applications will be better understood on reading the following description and examining the accompanying figures.

BRIEF DESCRIPTION OF THE FIGURES

The figures are presented for information purposes only and in no way limit the invention.

is a cross-sectional view of a part of a moving turbomachine wheel comprising a retaining device according to the state of the art;

is a view in an axial section including the axis of rotation, of a part of a rotating turbomachine assembly according to an example of a first embodiment of the invention;

is a perspective view of an upstream face of a part of the rotating turbomachine assembly of the ;

is a partial perspective view of the upstream face of the rotating turbomachine assembly of Figures 2 and 3;

is a perspective view of the downstream face of a part of the rotating turbomachine assembly of Figures 2 to 4.

is a downstream front view of a part of the rotating turbomachine assembly of Figures 2 to 5.

is a perspective view of the downstream face of a disk of the rotating turbomachine assembly of Figures 2 to 6.

is a perspective view of an axial thrust plate of the rotating turbomachine assembly of Figures 2 to 6.

is a perspective view of part of another example of the rotating turbomachine assembly according to the first embodiment.

is a view in an axial section including the axis of rotation, of a part of a rotating turbomachine assembly according to an example of a second embodiment of the invention.

DETAILED DESCRIPTION

The figures are presented for information purposes only and in no way limit the invention.

An exemplary embodiment of a rotating turbomachine assembly comprising at least one device for retaining a blade root in a cell of a disc, according to examples of two embodiments of the invention which are described in detail below, with reference to the attached drawings. These examples illustrate the characteristics and advantages of these different embodiments of the invention.

To understand the invention, we will adopt the radial and axial orientations along the axis of rotation X of the rotating turbomachine assembly. The upstream to downstream is oriented along the axial axis and are defined in relation to the direction of air flow from the entry of the air into the turbine towards the exit of the air out of the turbine . In addition, the terms "interior" and "exterior" are defined in relation to the interior or exterior of the rotating turbomachine assembly in the axial direction, the term "exterior" designates the surfaces or faces oriented or forming facing the outside of the rotating turbomachine assembly, as opposed to the term "interior" which designates the faces or surfaces of an element facing a blade root of the rotating turbomachine assembly. Finally, the terms “internal” and “external” are defined radially with respect to the axis of rotation, an internal face or surface of an element is closer than an external face or surface of the same element.

Figures 2 to 8 represent different part views of a rotating turbomachine assembly 1 according to a first example of a first embodiment.

The invention relates to a rotating turbomachine assembly with an X axis of rotation, which may be a mobile turbine wheel. The rotating turbomachine assembly 1 comprises a disk 5 centered on an axis of rotation perspective view on an upstream face 1a of a part of the rotating turbomachine assembly 1. The disk 5 comprises an upstream face 5a visible in particular on the and in addition a downstream face 5b visible in Figures 6 and 7, opposite axially to the upstream face 5a. There represents a downstream front view 1b of a part of the rotating turbomachine assembly 1, explained in more detail below and the represents a perspective view of a downstream face 5b of the disk 5 alone.

The disc 5 comprises teeth 52 extending axially from the upstream face 5a to the downstream face 5b, and cells 56 formed between the teeth 52. More precisely, as visible in the , each tooth 52 comprises a circumferential end face 526c delimiting a circumferential end of a cell 56 and another circumferential end face 526d delimiting a circumferential end of another cell 56. The disc 5 further comprises a surface of bottom 566 formed between two circumferential end faces 526c and 526d of two neighboring teeth 52, delimiting the bottom of the cell 56. In addition, each circumferential end face 526c and 526d of a tooth 52 comprises a bearing zone to radially retain a blade 6 explained below. The axis of rotation X is schematized but its location is in reality much further away radially from the teeth 52.

The disk 5 comprises an axial end surface 54a, 54b on each upstream 5a and downstream 5b face. Each tooth 52 is therefore delimited axially between these two axial end surfaces 54a, 54b of the disc 5. The disc 5 comprises a bearing surface 50b on one of the upstream or downstream faces 5a, 5b. This bearing surface 50b can be a part of one of the two axial end surfaces 54a, 54b or can be, as in the examples illustrated in the figures, formed in a recess relative to the axial end surfaces 54a, 54b of one of the two upstream or downstream faces 5a, 5b. In this example of this first embodiment, the downstream face 5b of the disc 5 comprising the support surface 50b.

The rotating turbomachine assembly 1 further comprises a plurality of blades 6 each comprising a blade root 61 mounted in a corresponding cell 56 of the disk 5. Each blade root 61 is therefore engaged in a cell 56, for example dovetail.

The blade root 61 extends axially between an upstream face 61a and a downstream face 61b opposite axially to the upstream face 61a.

Each blade root 61 comprises two bearing faces 615c, 615d each connecting the upstream face 61a to the downstream face 61b and an internal radial end face 615 connecting the upstream face 61a to the downstream face 61b and the two bearing faces 615c, 615d. Each bearing face 615c, 615d forms a circumferential end of the blade root 61 opposite one to the other and bears against the bearing zone of the circumferential end face 526c and 526d of one of the two corresponding teeth 52 forming the cells 56, when the rotating turbomachine assembly 1 is rotating along its axis of rotation X. In this example, the rotating turbomachine assembly 1 further comprises a foil 8, referenced and visible on the Figures 2, 3 and 4, but could be without it.

The upstream face 61a of the blade root 61 and the upstream axial end surface 54a at the level of the tooth 32 extend in the same first radial plane perpendicular to the axis of rotation blade 61 and the downstream axial end surface 54b at the level of tooth 32 extend in the same radial plane parallel to the first plane.

The rotating turbomachine assembly 1 further comprises at least one axial retaining device 7 for a blade 6, each comprising at least one axial stop plate 71. In this case, as visible in the representing a perspective view of the downstream face 1b of a part of the rotating turbomachine assembly 1, the rotating turbomachine assembly 1 comprises an axial retaining device 7 per blade 6. In other words, the rotating turbomachine assembly 1 comprises a plurality of axial retaining devices 7 each comprising an axial stop plate 71 mounted against a downstream or upstream face of a blade 6 and against a respectively downstream or upstream face of the disk 5 as explained below. Of course, according to another mode not shown, the axial stop plate 71 can retain other blades, for example 2 or 3 blades (i.e. two or three times less axial retaining device 7 than blade), in this example , the wheel would include a number of axial thrust plates 71 which would be a multiple of the number of blades of the wheel.

Each axial stop plate 71 includes an external face 7e visible on the and a 7i internal face visible on the representing the axial thrust plate 71 in a three-dimensional view. The internal face 7i is opposite the external face 7e. The axial stop plate 71 comprises two circumferential end edges 71c, 71d spaced from one another along a maximum tangential length LT. By maximum tangential length we mean the longest length measured between the two edges tangentially to the axis of rotation.

In this case in this example of this embodiment, the maximum tangential length LT is less than the length between two vertices of the two neighboring teeth 52 forming the cell 56 but greater than the maximum tangential width between the two end faces circumferential 526c, 526d of these two teeth 52 (i.e. the maximum width of the cell measured tangentially). In other words, in this example, the axial stop plate 71 axially retains only one blade 6 by closing the cell 56 axially on one side (in this case the downstream side) and overflows on either side circumferentially. of the cell 56 by covering the bearing surface 50b extending over part of the two neighboring teeth 52.

The internal face 7i is pressed against one of the upstream or downstream faces 61a, 61b of the blade root 61 of the corresponding blade 6 and against the bearing surface 50b of the corresponding upstream or downstream face 5a, 5b of the disc 5. In this case, in this example the internal face 7i is pressed against the downstream face 61b of the blade root 61 and the bearing surface 50b of the disc 5. Of course, according to another example not shown, the face internal 7i can be pressed against the upstream face 61b of the blade root 61 and against a bearing surface of the upstream face 5a of the disc 5.

In this case, disk 5 includes a housing 57 visible on the , housing an axial stop plate 71 bearing against the bearing surface 50b forming a bottom of the housing 57. As previously described, in this example the bearing surface 50b is thus set back axially relative to the end surface axial 54, in this case at least the thickness of the axial stop plate 71 measured between its internal face 7i and its external face 7e.

The axial retaining device 7 further comprises a fixing device 78 of the axial stop plate 71 against the blade root 61 to axially retain the blade root 61 in the cell 51 at least in one axial direction by the through the axial stop plate 71 pressed against the support surface 50b. The fixing device 78 in this embodiment fixes the axial stop plate 71 to the blade root 61 and prevents the blade root 61 from moving axially in an axial direction by abutting against the bearing surface 50a. According to another embodiment, the fixing device 78 is fixed to the disc 5 and makes it possible to stop the blade root.

The axial retaining device 7 thus makes it possible in this example to retain axially the blade root 61 in the cell 56 in the axial direction from downstream to upstream by the axial stop plate 71 fixed to the blade root 61 and pressed against the bearing surface 50b of disc 5.

In this case, in this example of this embodiment, the fixing device 78 is a bolt comprising a nut 781 and a screw 780 comprising a head 782. In this embodiment, the blade root 61 comprises a hole 610 crossing and opening onto the upstream faces 61a and downstream faces 61b (referenced on the ), the screw 780 passing through the 610. The blade root 61 and the axial stop plate 71 are sandwiched between the head 782 and the nut 781. In this embodiment, the fixing device 78 is therefore fixed to the blade root 61 and to the axial thrust plate 71 by sandwiching them.

In this example, the head 782 of the screw 780 is pressed against the upstream face 61a of the blade root 61 and the nut 781 is pressed against the outer surface 7e of the axial stop plate 71. Of course this could be the 'reverse. In this example, the axial stop plate 71 comprises a through orifice 70, opening onto the internal face 7i and the external face 7e, the screw 780 passes through this orifice. According to another example not shown, the axial stop plate 71 comprises a notch through which the screw passes.

There represents a view along the upstream face 1a of a part of the rotating turbomachine assembly 1, according to this example of this embodiment. In this case, we can see in this example that the blade root 61 comprises an axially open notch delimited by two flat abutment surfaces 682c, 682d each extending in a plane parallel to the axis of the screw 780 and parallel between them. The notch is further formed in this example by another flat surface connecting the two flat surfaces. These abutment surfaces 682c, 682d make it possible to abut against a flat surface of the head 782 of the screw 780 to prevent it from pivoting in both directions of rotation (screwing and unscrewing). This simplifies the fixing of the bolt, but also prevents rotation of the 780 screw once screwed. In this example, the head 782 of the retaining device comprises the shape of a parallelepiped, in this case a square section and the notch of the blade root 61 has a section corresponding to the imprint of at least one part of the head, here in a rectangular shape.

Of course, according to another example, the notch of the blade root 61 can be on the side of the nut 781 to prevent it from rotating and have a shape corresponding to the imprint of at least part of the nut.

According to another example, the hole 610 'can be tapped as shown in the representing a downstream front view of a blade root 61' according to another example of this embodiment identical to the previous example except in that this hole 610' is threaded and in that the fixing device 78 comprises only the screw 780 screwed into the tapping of the hole 610'. In this example the hole 610' does not necessarily open out. Furthermore, the blade root 61' is in this example devoid of the notch comprising the abutment surfaces 682, since the screw head necessarily rests against the axial abutment plate 71. Thus the axial abutment plate 71 is in this example pressed against the downstream face of the blade root 61' and a bearing surface of the disc. Of course, the axial stop plate 71 can also be pressed against the upstream face of the blade root 61' (the threaded hole 610' then opens at least on the side of this upstream face).

According to another example not shown, the orifice 70 of the axial stop plate 71 is tapped. In this example, the fixing device 78 only includes the screw 780 screwed into the thread of the orifice 70 and the blade root 61 does not include a notch. In other words, the axial stop plate 71 forms the nut.

According to these different examples of this embodiment, optionally the blade root 61, 61' and the axial stop plate 71 each comprise an indexing element 612, 72 fitted one inside the other making it possible to simplify assembly. (visible in particular in Figures 2, 8 and 9). In this case, the indexing element 612 of the blade root is a non-through hole and the indexing element 72 of the axial stop plate 71 is a protuberance (in the form of a rod) projecting from the internal face surface 7i of the axial stop plate 71, the protuberance being housed in the non-through hole.

According to these different examples of this embodiment, optionally each axial stop plate 71 comprises an air passage orifice 75 (visible in particular in Figures 2 and 8) facing a space formed between the foil 8 covering the internal radial end face 615 of the blade root 61 and the bottom surface 566 of the disc 5 forming the cell 56. This space and the air passage orifice 75 thus allows the air can circulate between the upstream face 1a and the downstream face 1b making it possible to cool the blade root 61 (here by means of the foil), the bottom surface of the disc 5 and the axial thrust plate 71 in operation.

Furthermore, in these examples of this embodiment, the rotating assembly 1 comprises an annular spacer 4 surrounding the axis of rotation, also called a movable ring, separating two stages of the turbine. This annular spacer 4 is for example as in the example of the prior art of the , fixed to the disc 5, in particular by a flange and a bolt. As visible on the and the , the annular spacer 4 comprises an annular wall 47 resting axially against the external surface 7e of each axial stop plate 71. It can be seen in particular on the , that the annular wall 47 of the annular spacer 4 is pressed against the external surface 7e different retaining plates 71 each fixed by a fixing device 78 against the corresponding blade root 61 to axially retain the blade root 61 in the cell 51 at least in one axial direction by means of the stop plate axial 71 pressed against the support surface 50b. This annular spacer thus makes it possible to retain axially the blade assembly 6 and the axial retaining device 7 in the axial direction from upstream to downstream.

According to a second embodiment of a rotating turbomachine assembly 1', represented in , identical to the first rotating turbomachine assembly 1 except with regard to its upstream face 1a', in particular the differences are explained below.

Mainly, the difference with the first embodiment is that each retaining device 7' of the turbomachine rotary assembly 1' further comprises the axial stop plate 71, hereinafter called first axial stop plate 71, a second axial abutment plate 7' against the other face (in this case the upstream face 61a') of the blade root 61'. This second axial stop plate 7' faces another bearing surface 50a on the upstream face 5a' of the disc 5' opposite axially to the first axial stop plate 71. This bearing surface 50a is in this case like the bearing surface 50b of the upstream face 5a, formed in a recess relative to the axial end surfaces 54a, the bottom of a housing housing the second axial stop plate 7'.

This second axial stop plate 71' is identical to the first axial stop plate 71 on the side of the downstream face 1b (identical to that of the example of the first embodiment) except in that it optionally also comprises a anti-rotation abutment surface 7182 extending axially upstream of the external surface 7e' of the second axial abutment plate 71', makes it possible to abut against a flat surface of the head 782 (this could also be against a flat surface of the nut 781).

The fixing device 78 is also identical to that of the first example of the first embodiment, but could be two screws screwed into a tapped hole as in the example of the of the first embodiment, either a tapped hole opening out on either side of the downstream and upstream faces of the blade root or two holes, one of which opens onto the downstream face and the other onto the upstream face of the blade root.

The axial retaining device 7' thus makes it possible to retain the blade root 61' in the cell 56 of the disc 5 in both axial directions. In fact, the second axial stop plate 71' retains the blade assembly 6 axially, the fixing device 78 and the first axial stop plate 71 in the axial direction from upstream to downstream.

In this example, the blade 6' is different from the first embodiment, in that the upstream face 61a' of the blade root 61' further comprises a second indexing element 612' extending axially towards the upstream from the surface in contact with the internal facing surface 7i of the second axial stop plate 71'. As in the example of the first embodiment, and as on the side of the downstream face 1b, the second indexing element 612' is a hole housing the indexing element 72 of the second axial stop plate 71'.

For reasons of axial sizing constraints (which may be thermal or manufacturing) of the different parts (axial length of the blade root, axial length between two contact surfaces 50a, 50b, of the disc 5) a clearance is formed at least between one of the two axial stop plates 71, 71', and one of the two corresponding contact surfaces 50a, 50b. In other words, the axial length of the blade root 61 is designed to be smaller than that between the two contact surfaces 50a, 50b, of the disc 5 taking the axial dimensioning constraints. Thus, each blade 2 is independent, and has a freedom of axial movement corresponding to this clearance. However, the axial retaining device 7' ensures its role of axially retaining the blade root 61 in its cell 56. Another solution is also to reduce the axial thickness of one of the axial stop plates 71, 71' at the level of its internal surface 7i (shoulder on the periphery of the internal surface 7i) in contact with the contact surface 50a, 50b. According to one example, a leaf spring can be placed between one of the two axial stop plates 71, 71', to reduce the vibrations between the axial stop plates 71, 71' and the disc 5. The leaf spring can be be on the periphery of the axial thrust plate.

In these different examples of these different embodiments, the fixing device 78 uses a screw 780 to screw the axial stop plate(s) 71, 71', but other fixing possibilities are possible, such as by riveting, or welding, fitting for example bayonet type etc.

The rotating turbomachine assembly 1, 1' thus comprises at least one retaining device 7, 7' according to the invention which ensures axial blocking of the blade roots 61, 61' in the cells 56 of the disc 5, 5' without requiring any hook on the blade 6, 6', nor any retaining disc retaining all of the blade roots. In addition, such a retaining device is easily assembled (without forcing assembly), it can be dismantled individually in the event of wear of this retaining device or of another element such as the foil and has a reduced size making it easier to install. mounting on the disk 5 of the rotating turbomachine assembly 1. Consequently, the various parts of the retaining device 7 are not mounted under stress by deformation, but only fixed for example by screwing, which considerably limits the risk of damage to the retaining device 7 and the various problems that result from it. The lifespan of the rotating turbomachine assembly 1 according to the invention is then increased and costly engine maintenance interventions are limited as well as the need to change the elements of the damaged retaining device 7, 7'.

Unless otherwise specified, the same element appearing in different figures presents a unique reference.

Claims (11)

Rotary turbomachine assembly (1, 1’) with axis (X) of rotation comprising:

• a disk (5, 5') centered on the axis (X), which has an upstream face (5a, 5a') and a downstream face (5b) opposite axially to the upstream face (5a, 5a') and having at its peripheries of the teeth (52) extending axially from the upstream face (5a, 5a') to the downstream face (5b), and cells (56) delimited circumferentially and formed between the teeth (52), the disc (5 , 5') furthermore having at least one bearing surface (50a, 50b) on one of the upstream or downstream faces (5a, 5b) of the disc (5, 5'),
• a plurality of blades (6) each comprising a blade root (61, 61') mounted in a corresponding cell (56) of the disc (5, 5'), the blade root (61, 61') comprising an upstream face (61a, 61a'), a downstream face (61b) opposite axially to the upstream face (61a, 61a'),
• characterized in that the rotating turbomachine assembly (1, 1') further comprises at least one axial retaining device (7, 7') for a blade (6, 6'), comprising:
  • at least one axial stop plate (71, 71') comprising an external face (7e) and an internal face (7i) opposite the external face (7e) and comprising two circumferential end edges (71c, 71d) spaced apart 'one from the other following a maximum length measured tangentially less than the radius of the disc (5, 5'), the internal face (7i) being opposite one of the upstream or downstream faces (61a, 61a ', 61b) of the blade root (61, 61') of the corresponding blade (6, 6') and on the other hand of the bearing surface (50a, 50b) of the upstream or downstream face (5a , 5a', 5b) corresponding to the disk (5, 5'),
  • a fixing device (78) fixing the axial thrust plate (71, 71') to the blade root (61, 61') or to the disc (5, 5'), the axial retaining device (7, 7' ) axially retaining the blade root (61, 61') in the cell (51) at least in one axial direction by means of the axial stop plate (71, 71') while being pressed against the surface of support (50a, 50b).

Rotary turbomachine assembly (1, 1') for a turbomachine according to the preceding claim, in which the fixing device (78) is fixed to the blade root (61, 61') and the axial thrust plate (71, 71' ) is fixed to the blade root (61, 61') by being sandwiched between the blade root (61, 61') and the fixing device (78). Rotary turbomachine assembly (1, 1') for a turbomachine according to claim 2, in which the blade root (61, 61') comprises a hole (610, 610') extending axially and opening onto the upstream face or downstream (61a, 61a', 61b) of the blade root (61, 61') in contact with the axial stop plate (71, 71'), which comprises an orifice (70) extending axially and opening onto the hole (610, 610') of the blade root (61, 61'), the fixing device (78) comprising a screw (780) passing through the axial stop plate (71, 71') and comprises a housed part in the hole (610) to fix the axial thrust plate (71, 71') against the blade root (61, 61'). Rotary turbomachine assembly (1, 1') according to claim 3, in which the hole (610') has a thread, the screw (780) being screwed into the hole (610') of the blade root (61, 61 ') and comprises a head (782) bearing against the external face of the axial stop plate (71, 71'). Rotary turbomachine assembly (1, 1') according to claim 3, in which the hole (610) is through and extends from the upstream face (61a, 61a') to the downstream face (61b), the screw (780 ) passes through the hole and in which the fixing device (78) comprising a nut (781) tightened on the screw (780) by sandwiching the blade root (61, 61') and the axial thrust plate (71 , 71') against each other. Turbomachine rotary assembly (1') according to the preceding claim, in which the axial retaining device (7') further comprises a second axial stop plate (71') per blade (6'), each second axial stop plate (71') comprising an external face (7e) and an internal face (7i) opposite the external face (7e), the internal face (7i) being pressed against the upstream or downstream face (61a', 61b) of the foot d 'blade (61') of the corresponding blade (6') opposite that against which the first axial stop plate (71) is pressed, the second axial stop plate (71') is further pressed against respectively a surface support (50a) of the upstream or downstream face (5a', 5b) corresponding to the disc (5'), the screw (780) of the fixing device (8) passing through the two axial stop plates (71, 71' ) to sandwich the blade root (61, 61') between the two axial thrust plates (71, 71') each pressed against a bearing surface (50a, 50b) of the disc (5, 5') . Rotary turbomachine assembly (1) according to one of claims 1 to 5, further comprising a spacer (4) fixed to the disc (5), the spacer (4) comprising an annular wall (47) resting against the face external (7e) of the axial stop plate (71). Turbomachine rotary assembly (1, 1') according to one of the preceding claims, in which each axial thrust plate (71, 71') comprises an indexing element (72) and each blade root (61, 61 ') comprises an indexing element (612, 612') cooperating with that of the axial stop plate (71, 71'). Turbomachine rotary assembly (1, 1’) according to one of the preceding claims, in which:

• the blade root (61, 61') comprises an internal radial end face (615) connecting the upstream face (61a, 61a') to the downstream face (61b), the disc (5, 5') comprising a bottom surface (566) per cell formed between the two teeth (52),
• each axial stop plate (71, 71') comprises an air outlet orifice (75) facing the space extending axially in the cell (56) formed between the bottom surface ( 566) and the internal radial end surface (615) of the blade root (61, 61').

Turbomachine rotary assembly (1, 1') according to one of the preceding claims, in which the disk (5, 5') comprises an axial end surface (54a, 54b) on each of its upstream face (5a, 5a ') and its downstream face (5b) and a housing (57) housing the axial stop plate (71, 71'), whose bearing surface (50a, 50b) forms a bottom of the housing (57) in axial recess relative to the axial end surface (54a, 5b) of at least the thickness of the axial stop plate (71, 71') measured between its internal face (7i) and its external face (7e). Rotary turbomachine assembly (1, 1') according to one of the preceding claims, comprising an axial retaining device (7, 7') per blade (6, 6') mounted on the disk (5).